PIM International March 2016

Vol. 10 No. 1 MARCH 2016

in this issue Company visit: Indo-MIM PIM particulate composites PIM at Euro PM2015, Part 2 Published by Inovar Communications Ltd

www.pim-international.com

CataMIM™ the next generation of MIM/PIM Feedstocks CataMIM™ • A direct replacement for all current commercially available catalytic debind feedstocks

• Water Debind

• Improved flow

• Large selection of available materials

• Stronger green and brown parts • More materials available • Better surface finish • Custom scale-up factors available RYER, Inc. 42625 Rio Nedo Unit B Temecula, CA 92590 USA Tel: +1 951 296 2203 Email: dave@ryerinc.com

AquaMIM®

• Faster cycle times • 65°C / 150°F mold temperature

• Custom scale-up factors available

SolvMIM® • Solvent, Super Critical Fluid Extraction (SFE) or Thermal Debind methods • Hundreds of materials available • Custom scale-up factors available

www.ryerinc.com • At RYER, all our feedstocks are manufactured to the highest level of quality, with excellent batch-to-batch repeatability.

• RYER is the ONLY commercially available feedstock manufacturer to offer all five debind methods.

• RYER offers the largest material selections of any commercially available feedstock manufacturer.

• RYER offers technical support for feedstock selection, injection molding, debinding and sintering.

Publisher & editorial offices Inovar Communications Ltd 2 The Rural Enterprise Centre Battlefield Enterprise Park Shrewsbury SY1 3FE, United Kingdom Tel: +44 (0)1743 454990 Fax: +44 (0)1743 469909 Email: info@inovar-communications.com www.pim-international.com Managing Director and Editor Nick Williams Tel: +44 (0)1743 454991 Email: nick@inovar-communications.com

For the metal, ceramic and carbide injection moulding industries

Publishing Director Paul Whittaker Tel: +44 (0)1743 454992 Email: paul@inovar-communications.com Consulting Editors Professor Randall M German Associate Dean of Engineering, Professor of Mechanical Engineering, San Diego State University, USA Dr Yoshiyuki Kato Kato Professional Engineer Office, Yokohama, Japan Professor Dr Frank Petzoldt Deputy Director, Fraunhofer IFAM, Bremen, Germany Dr David Whittaker DWA Consulting, Wolverhampton, UK Bernard Williams Consultant, Shrewsbury, UK Production Hugo Ribeiro, Production Manager Tel: +44 (0)1743 454990 Email: hugo@inovar-communications.com

Advertising Jon Craxford, Advertising Director Tel: +44 (0) 207 1939 749, Fax: +44 (0) 1743 469909 E-mail: jon@inovar-communications.com Subscriptions Powder Injection Moulding International is published on a quarterly basis as either a free digital publication or via a paid print subscription. The annual print subscription charge for four issues is £135.00 including shipping.

Accuracy of contents Whilst every effort has been made to ensure the accuracy of the information in this publication, the publisher accepts no responsibility for errors or omissions or for any consequences arising there from. Inovar Communications Ltd cannot be held responsible for views or claims expressed by contributors or advertisers, which are not necessarily those of the publisher.

Advertisements Although all advertising material is expected to conform to ethical standards, inclusion in this publication does not constitute a guarantee or endorsement of the quality or value of such product or of the claims made by its manufacturer.

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ISSN 1753-1497 (print) ISSN 2055-6667 (online)

A resurgence of interest in metal powder based technologies There is no escaping the fact that thanks to Additive Manufacturing we are experiencing a resurgence of interest in metal powder based technologies. Powder Metallurgy conference organisers worldwide have seen their audiences expand and diversify, news pages are filled with reports of new metal powder producers, and a new generation of end-users are discovering what really can be achieved with metal - and ceramic - powders.

How the current surge in interest in AM will play out is yet to be seen, but it does bring unexpected opportunities for the MIM industry. With a number of new specialist powder producers on the horizon, the promise of affordable titanium powder, for example, may yet materialise, enabling Ti-MIM to finally achieve the much anticipated growth.

There is also an opportunity for the MIM industry to be discovered by the new audience that has been drawn to AM. Thanks to MIM’s ability to produce highly complex components in high-volumes from many of the key materials that are so important to AM, it is inevitable that our technology will also be discovered for new, high-performance applications.

Where MIM leads AM is that it can now be regarded as a maturing technology, with established markets, materials and standards.

It is also an industry with a growing number of global players that are able to offer even the largest of end-users the security of knowing that global projects can be fulfilled by the industry. In this issue we report on a recent visit to one such global player, Indo-US MIM Tec. Pvt., and discover how Bangalore has become one of the most important centres for MIM worldwide.

Nick Williams Managing Editor

Cover image Vacuum sintering furnaces at Indo-MIM, Bangalore, India (Photo courtesy Indo-US MIM Tec. Pvt.)

Vol. 10. No. 1 March 2016 © 2016 Inovar Communications Ltd

March 2016 Powder Injection Moulding International

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As a full-service MIM provider, ARCMIM offers its customers the convenience, efficiency, quality and cost advantages inherent with a one-source partner. As a MIM veteran – and technology leader – ARCMIM ensures the precision, ingenuity, product efficacy and superior quality necessary in today’s competitive marketplace. We support and provide our customers with: > Metal injection molding > Plastic injection molding > Magnesium injection molding > Medical cleanroom molding > 3D printing in metal and plastic > State-of-the-art tool center > Custom hermetic seals, flanges and fittings > World-class facilities in USA and Europe

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March 2016

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In this issue 47

Indo-MIM: A giant in Metal Injection Moulding expands to build on strong international growth

It is just under twenty years since Indo-US MIM Tec Pvt. Ltd., better known by its abbreviated name Indo-MIM, was established in Bangalore, India. Within this short period of time the company has evolved into one of the world’s largest MIM producers. Dr Georg Schlieper visited Indo-MIM for PIM International to discover the secret behind this remarkable expansion and the company’s plans for maintaining this rapid growth in the future.

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Opportunities in the PIM of particulate composites

At the first PIM Symposium in 1990, the Marketing Manager for a leading MIM facility outlined where and how MIM would grow. His analysis was based on the conversion of small investment castings to MIM. Although his predictions took a while, MIM did reach those sales predictions. Now MIM is seeking the next big thing. One opportunity for differentiation comes from mixed powder composites. The field of particulate composites is poorly organised and poorly recognised by suppliers, yet the products have significant added value since there are few competitive processes for complex shaped composites. Prof Randall German reviews emerging opportunities and introduces promising compositions and processing options and applications.

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Euro PM2015: Innovative materials offer growth opportunities for PIM

The Euro PM2015 Congress & Exhibition, Reims, France, October 4-7 2015, proved to be an essential destination for those looking to understand the latest technical and commercial advances in PIM. In the second part of his review for PIM International, Dr David Whittaker reports on a series of papers that cover the processing of a range of materials that all offer potential for future growth, including Fe-Si for soft magnetic applications, titanium, nickel-based superalloy CM247LC, aluminium and silicon carbide.

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High Pressure Capillary Rheometer, a simple way to measure the viscosity of MIM feedstocks?

Process simulation is a widely used tool in the development phase of injection moulded parts. The key variable describing the deformation behaviour of melted polymers is the viscosity and the most common method to calculate the viscosity of plastics is the High Pressure Capillary Rheometer.

As Timo Gebauer and Vanessa Schwittay from SIGMA Engineering GmbH explain, several virtual experiments have been performed to understand the limits of this method and establish how it can be used for MIM feedstocks.

Regular features 5

Industry news

87

Events guide

88

Advertisers’ index

March 2016 Powder Injection Moulding International

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Industry News

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Industry News To submit news for inclusion in Powder Injection Moulding International please contact Nick Williams, nick@inovar-communications.com

Epson Atmix’s new powder treatment plant will double capacity for superfine alloy powders Japan’s Seiko Epson Corp has announced that its subsidiary company, Epson Atmix, is to construct a new factory on a 10,000 m2 plot adjoining its existing Kita-Inter plant, located in the city of Hachinohe, Aomori Prefecture.

The Kita-Inter Plant, which came online in October 2013, produces water atomised superfine alloy powders used in the production of high-performance precision metal injection moulded components for vehicles, smartphones, tablet PCs, wearable products, medical equipment and a wide variety of other products. Epson states that annual global market demand for its superfine powders is growing and this trend is expected to continue for the foreseeable future.

Epson Atmix will invest a total of Yen 1.2 billion in the construction of the new factory, which was planned to begin in March 2016. The factory is scheduled to begin operations in April 2017. The company reports that the additional facility will focus on back-end processes including the treatment, packaging and shipping of

alloy powders and will help to raise overall production efficiency by working in tandem with existing atomisation processes. It will approximately double the company’s current superfine alloy powder treatment capacity to more than 10,000 tonnes and provide greater supply stability and reduced lead times from order to shipping.

Epson Atmix has a broad lineup of MIM powders that includes stainless steels and low-alloy steels. In addition, the size of powder particles can be adjusted to suit a given application, helping to increase the strength of metal injection moulded parts. www.atmix.co.jp

Epson Atmix’s Kita-Inter plant for the production of atomised superfine alloy powders. The red area indicates the planned new factory

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Worldwide

Global manufacturer of nodular and spherical aluminum powders, pre-alloyed aluminum powders, and aluminum premixes for PM www.ampal-inc.com www.poudres-hermillon.com

In the Americas

Supplier of carbonyl iron and atomized stainless steel powders for the MIM and PM industries United States Metal Powders, Incorporated 408 U.S. Highway 202, Flemington, New Jersey 08822 USA Tel: +1 (908) 782 5454 Fax: +1 (908) 782 3489 email: rhonda.kasler@usbronzepowders.com

Industry News

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High Temperature Furnaces up to 3,000 °C

REEgain investigates MIM of NdFeB magnets The REEgain consortium was established in Denmark in October 2012 with partners from Danish research establishments and industry and with sponsorship from the Danish Agency for Science, Technology and Innovation. The consortium has as one of its main objectives the development of a high performance rare earth permanent magnet based on Nd, Pr and Dy mixtures as found in the rich Tanbreez mineral deposit in Greenland. A further objective is to develop the recycling of permanent magnets in order to prevent the loss of rare earth elements in the future product cycles of Danish industry. This, it is stated, will be achieved by developing and demonstrating a high field alignment of fine rare earth-Fe-B powder using advanced sintering and magnetisation processes.

Martin Sorensen, from the Danish Technological Institute (DTI) in Taastrup, presented an update on the work of the REEgain consortium on the use of Metal Injection Moulding for the production of NdFeB magnets at a “Metal Injection Moulding (MIM) – Technology and Applications Seminar” held in Taastrup, November 17, 2016. Sorensen focused on the special challenges of MIM NdFeB magnets compared to the production of ferrous MIM parts and discussed how these challenges are being addressed in REEgain. This includes the supply of the necessary rare earth elements from Greenland, the improved reliability and lifetime of permanent magnets and advanced process technologies, enabling complex geometries for strong permanent magnets.

Other presentations at the Taastrup MIM Seminar covered Catamold MIM feedstock (BASF), injection moulding machines and tooling (Arburg), debinding and sintering (Eisenmann Thermal Solutions), MIM case studies (Sintex A/S) and the state-of-the-art and future of MIM (Technical University of Denmark). www.atv-semapp.dk | www.REEgain.dk

Based on more than 30 years of heat treatment experience Carbolite Gero offer standard products as well as customerspecific solutions. n Furnaces for MIM and CIM production and quality testing n Thermal or catalytic debinding without the need for condensate traps n Sintering furnaces under partial pressure or low overpressure

POWDERMET2016: Programme now available The Conference Programme for POWDERMET2016 is available now on the event’s website. The popular conference, which this year takes place in Boston, Massachusetts, USA, June 5 - 8, 2016, is organised by the Metal Powder Industries Federation (MPIF) and will also feature a major PM trade exhibition. The Opening General Session will feature a keynote presentation entitled, “The New Face of Manufacturing” by Jim Carroll, the worldrenowned author, futurist, and trends and innovation expert. www.powdermet2016.org

Vol. 10 No. 1 © 2016 Inovar Communications Ltd

www.carbolite-gero.com

Gero-Advert-GB-PM-105x297.indd 1 March 2016 Powder Injection Moulding International

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Industry News

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Hoeganaes Corporation announces AS9100C Certification Hoeganaes Corporation, based in Cinnaminson, New Jersey, USA, has announced that it has achieved AS9100C Quality Management System certification for its Innovation Center facility located in Cinnaminson. The AS9100C Quality Management System provides the basic quality framework necessary to address both civil and military aviation and aerospace needs.

This enhancement to Hoeganaes’s quality systems follows a multimillion-dollar investment in 2015 for the commercialisation of advanced powders for Additive Manufacturing and MIM. The production, design and distribution of its AncorTi™ range of gas atomised titanium powders are now certified under the scope of this rigorous aerospace quality standard.

“The attainment of AS9100C certification further demonstrates our long term commitment to delivering high performance powders for AM to world class customers operating in aerospace markets,” stated Mike Marucci, Global VP, Advanced Technology. Hoeganaes continues to be certified under the ISO/TS 16949 for automotive quality management, ISO 14001 environmental management and OHSAS 18001 safety management systems. www.hoeganaes.com

EPMA launches 2016 PM Thesis Competition The European Powder Metallurgy Association (EPMA) has announced the launch of its 2016 Powder Metallurgy Thesis Competition at both Diploma (Masters) and Doctorate (PhD) levels. The aim of the competition is to develop an interest in Powder Metallurgy, including Metal Injection Moulding, among young scientists at European academic establishments and to encourage research at under-graduate and post-graduate levels.

The competition is open to all applicants who have graduated from a European university and who have had their theses approved during the 2013/2014, 2014/2015 or 2015/2016 academic years. The subject must be classified under the topic Powder Metallurgy.

The prizes, sponsored by Höganäs AB, will be presented at the World PM2016 Congress & Exhibition, which will take place October 9 - 13, in Hamburg, Germany. The winner of the diploma category will receive a cheque for €750 and the doctorate category winner will receive €1,000.

Both winners will also receive free registration to the World PM2016 Congress.

The deadline for submitting entries to the Powder Metallurgy Thesis Competition is April 29, 2016. www.epma.com

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© 2016 Inovar Communications Ltd

Vol. 10 No. 1

EPSON ATMIX CORPORATION

Finer Powder Production Cleaner Powder Production Shape Control of Powders • Low Alloy Steel • High Alloy Steel • Stainless Steel • Magnetic Materials • Granulated Powder

JAPAN Mr. Numasawa, Ryo Numasawa.Ryo@exc.epson.co.jp ASIA and OCEANIA Mr. Yoshida, Shunsuke yoshida-s@pacificsowa.co.jp CHINA Mr. Ota, Arata ota-a@pacificsowa.co.jp

U.S.A and SOUTH AMERICA Mr. Pelletiers, Tom tpelletiers@scmmetals.com EU Dr. Pyrasch, Dieter Dieter.Pyrasch@thyssenkrupp.com KOREA Mr. Yun, John dkico@hanafos.com

Industry News

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Carpenter expands From powder to part – Osram offers metal powder vertically integrated PIM production facility Carpenter Technology Corporation, Wyomissing, Pennsylvania, USA, is reported to be spending an additional $23 million to add titanium furnace equipment to its new superalloy powder facility in Limestone County, Alabama. The purchase will raise Carpenter’s investment in the plant to $61 million. The new plant’s titanium powder product offering will increase Carpenter’s reach into aerospace and medical markets and offer growth opportunities in transportation, Tony R. Thene, Carpenter President, Chief Executive Officer told the Decatur Daily. Carpenter is close to completing its second Limestone County plant. The company’s first Limestone County plant, a $518 million superalloy metal plant, began production in early 2014. www.cartech.com

Osram, based in Munich, Germany, is a leading global manufacturer of lighting products with a history dating back more than 100 years.

The company reported that sales revenue in the first quarter of its current financial year starting October 2015 increased by 6% from a year earlier to €1.48 billion. However, the continuing decline in demand for traditional lamps and associated products saw the company embark on an innovation and growth initiative last November to exploit the potential offered by semiconductor based lighting technologies.

Following the carve-out of the general lighting lamps business, the company will focus on three main strategic pillars in the future: LED components, specialty lighting, and luminaires, solutions and electronic components.

OSRAM is also a significant producer of tungsten (W) and molybdenum (Mo) powders including powder grades with various dopings which are used in the manufacture of lamp filaments and other PM-based refractory metal products such as sintered rods. The company states that its W and Mo powders are also used for Powder Injection Moulding and that it operates a vertically integrated PIM process from powder to the finished part. The PIM facility at OSRAM additionally processes cermet, ceramic and thermally conducting polymers (TCP) for heat sinks and thermal management.

Applications for PIM parts besides lighting applications may include radiation shielding, counterweights, components in sports equipment, automotive, aerospace and medical. www.osram.com

cartech.com/powderproducts

• Ultra--ne particle sizes for complex parts.

• Clean, consistent chemistries.

• Several size ranges to meet customer requirements.

• Wide range of powder alloys available.

Carpenter Powder Products is one of the largest global producers of prealloyed, gas atomized, spherical metal powders and leads the way as a supplier for Additive Manufacturing, Metal Injection Molding, Surface Enhancement, and Near Net Shapes/Hot Isostatic Pressing processes.

© 2016 CRS Holdings, Inc. All rights reserved.

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© 2016 Inovar Communications Ltd

Vol. 10 No. 1

Beware of Elnik MIM-itations

DELIVERS THE CUTTING EDGE TECHNOLOGICAL INNOVATIONS LEADING THE INDUSTRY TODAY. The Metal Injection Molding process can be risky because small processing errors could be very costly. Elnik Systems has made technological innovation it’s cornerstone but beware there are a lot of “MIM-itators” in the industry. While such MIM-itations are flattering, they have not grown from innovations. Innovative thinking leads to smarter MIM performance, which we call “MIM-telligenceTM”. Elnik’s innovations undergo extensive field testing in production sized furnaces at DSH Technologies LLC before the new technology hits the market. DSH is a sister company of Elnik providing R&D and Consulting help to the MIM industry. Elnik also offers free DSH services for one year with the purchase of each new MIM furnace, providing every Elnik customer with additional customized technical support and dependability. Another Elnik “MIM-telligenceTM” benefit.

107 Commerce Road, Cedar Grove, NJ 07009 USA • +1.973.239.6066 • www.elnik.com

Industry News

Numanova Srl established to manufacture range of metal powders Italian investment group Italeaf has announced it has established Numanova Srl to produce metal powders suited to a range of applications including Additive Manufacturing, MIM and HIP applications. The production plant will be located at Italeaf’s facility in Nera Montoro, near Rome, and the company plans to have operating offices in Milan, London and Hong Kong.

The metal powders will be suited to advanced uses in areas such as aerospace, energy, mechanical and biomedical. An investment of some €12 million has been announced and the company will be equipped with advanced gas atomised metal powder production technology. It will also use plasma atomisation technologies

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and total production capacity is expected to be around 500 tons/year of metal powders. “The production of metal powders and the research and development activity to make new alloys are attracting interest and growing expectations on the global market,” stated Paolo Folgarait, Numanova’s Executive Director and General Manager. “The versatility of the techniques of Powder Metallurgy can help to create complex and innovative metallic materials (and ceramic) and introduce new forms of production in advanced sectors with high added value.”

Numanova added that it has concluded a number of framework agreements for business collaboration and technical-scientific cooperation with metal Additive Manufacturing systems providers and companies operating in the metallurgical sector. It has also signed agreements with national and international universities and research centres. www.italeaf.com

AMPM conference programme published The third annual AMPM Conference on Additive Manufacturing with Powder Metallurgy, organised by the Metal Powder Industries Federation, takes place in Boston, USA, June 5-7, 2016. The popular event will feature worldwide industry experts presenting the latest developments in metal AM. The programme has now been published and includes two days of technical sessions that cover topics such as materials, metal powder production, powder characterisation, modelling and processes.

The event is co-located with POWDERMET2016, MPIF’s International Conference on Powder Metallurgy & Particulate Materials, and is essential for anyone interested in metal components produced via metal AM. www.ampm2016.org

Inject design freedom into advanced technical ceramics Philips Ceramics Uden is the world leader in translucent ceramics for lighting. Now we’re applying our expertise to a wide variety of applications - from complex technical products to aesthetic components. We can co-create a solution to meet any brief with the highest accuracy and a very competitive price. So whether you’re looking for ceramic injection moulding or extrusion, we make sure you can inject exceptional design freedom into your next project.

Philips Ceramics www.philips.com/ceramics or call +31 (0)6 11 38 64 00

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Vol. 10 No. 1

VISIT US AT

PM CHINA 2016 BOOTH A100

On the leading edge of metal powder manufacture With over 35 years’ experience in gas atomisation, Sandvik Osprey offers the world’s widest range of high quality, spherical metal powders for use in Metal Injection Moulding. Our products are used in an increasingly diverse range of applications including automotive, consumer electronics, medical and aerospace.

Our extensive product range includes stainless steels, nickel based superalloys, master alloys, tool steels, cobalt alloys, low alloy steels and binary alloys.

Using gas atomised powders can enhance your productivity and profitability: contact our technical sales team today for more information.

Sandvik Osprey Limited Milland Road Neath SA11 1NJ UK Phone: +44 (0)1639 634121 Fax: +44 (0)1639 630100 www.smt.sandvik.com/metalpowder e-mail: powders.osprey@sandvik.com

Industry News

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Ceramco introduces microPIM ceramic components Ceramco Inc., a leading North American manufacturer of complex shaped technical ceramics based in Center Conway, New Hampshire, has added micro Powder Injection Moulding to its production offering.

The company will utilise many of the alumina and zirconia production formulations currently used for high volume PIM ceramics.

“The incredibly small size parts in microPIM require more careful adjustments to the feedstock to achieve a very low viscosity. Other than that, it is virtually the same process that Ceramco has been using successfully for 30 years,” stated Thomas Henriksen, President of Ceramco. Henriksen added that microPIM technology developed by the company would allow it to produce ceramic components as light as 0.05 g in series production and that

World’s largest gas atomised powder plant planned

These clamping frames are typical of the scale and precision achieved by Ceramco’s MicroPIM process he would never again have to tell a customer “the part you’re asking us to make is too small”. It was stated that microPIM ceramic components are already found in numerous applications including fibre-optic ferrules and wire bonding nozzles and they are serving more broadly defined markets including medical and electrical interconnects. www.ceramcoceramics.com

France’s Metalvalue SAS and Asco-Industries have set up a joint venture forming Metalvalue Powder, to produce gas atomised metal powders in what they claim will result in the building of the world’s largest gas atomising plant. Studies are underway to finalise the location of the site. Following the acquisition of Swedish company Bofors Bruk, parent company of Metec/ Hydropulsor, Metalvalue acquired patents relating to the Scanpac® MMS Powder Metallurgy process.

The Scanpac® MMS process has already been licensed to a number of companies and the new atomising plant will supply metal powders to these clients, as well as supplying those using current PM processes. www.metalvalue.fr

CM Furnaces, long recognized as an industrial leader in performance-proven, high temperature fully continuous sintering furnaces for MIM, CIM and traditional press and sinter now OFFERS YOU A CHOICE, for maximum productivity and elimination of costly down time.

Choose one of our exclusive BATCH hydrogen atmosphere Rapid Temp furnaces.

Designed for both debinding and sintering, these new furnaces assure economical, simple and efficient operation.

OR... choose our continuous high temperature sintering furnaces with complete automation and low hydrogen consumption.

CONTACT US for more information on our full line of furnaces with your choice of size, automation, atmosphere capabilities and temperature ranges up to 3100˚F / 1700˚C.

E-Mail: info@cmfurnaces.com Web Site: http://www.cmfurnaces.com

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Powder Injection Moulding International

FURNACES INC. 103 Dewey Street Bloomfield, NJ 07003-4237 Tel: 973-338-6500 Fax: 973-338-1625

March 2016

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Vol. 10 No. 1

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OBE produces MIM copper components and targets weight saving devices OBE Ohnmacht & Baumgartner GmbH, based in Ispringen, Germany, introduced copper MIM for the first time on its stand at the Sensor + Test Exhibition 2015 held in Nuremburg.

OBE stated that it is using copper and copper alloy powders to produce MIM parts having excellent electrical and thermal conductivity properties for electromechanical applications, as well as for semiconductor elements and propulsion and battery technology. Target markets are therefore IT, electronics, e-mobility and renewable energy (Fig. 1).

At the Engine Expo 2015 Trade Fair held in Stuttgart, OBE also introduced MIM as an effective weight-reduction alternative for lightweight construction. Prof Carlo Burkhardt, Managing Director of OBE, stated in an Open Technology Forum presentation that because

Vol. 10 No. 1 Š 2016 Inovar Communications Ltd

of the wide variety of materials available, including titanium and other lightweight alloys, MIM can provide the unique combination of outstanding design possibilities and good mechanical properties. Prof Burkhardt gave the example of a lightweight stainless steel MIM airconditioner flange. He stated the use of CO2 as a refrigerant requires the use of stainless steel hoses for flex-

ible lines and OBE developed a MIM stainless steel flange which can be integrated into aluminium refrigerant lines. The MIM flange has exactly the same weight as the aluminium flange it replaced.

Prof Burkhardt also showed a MIM fastener developed together with KIT Karlsruhe for the attachment of high performance, lightweight CFC structures. Using the optimised geometry of the patented MIM fastener is said to avoid damage to the carbon fibre structure (Fig. 2). www.obe.de

Fig. 1 Copper MIM part produced by OBE

Fig. 2 A MIM fastener developed by OBE with KIT Karlsruhe

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Industry News

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Liquidmetal aims to grow the market for injection moulded amorphous alloys in Europe For two days in mid-January, Liquidmetal was the centre of attention at the Engel Deutschland Technologieforum in Stuttgart, Germany. At an exclusive event, the Austrian injection moulding machine manufacturer Engel, together with its system partners Liquidmetal Technologies and Materion Corporation, presented the potential of their technology developments to more than 200 customers and interested visitors.

Guests accepted the invitation from Engel to visit the Liquidmetal

Forum at its subsidiary in southwestern Germany. “The number of registrations far exceeded our expectations,” stated Claus Wilde, Managing Director at Engel Deutschland and head of the Technologieforum Stuttgart, who opened the event. The forum, which was originally planned to last just one day, was prolonged to last two days because of the unexpectedly high number of registrations. Guests came not only from the territory served by the subsidiary but from all regions of Germany, as well as from Austria,

Fig. 1 Participants at the Liquidmetal Forum in Stuttgart, Germany

Fig. 2 An Engel e-motion injection moulding machine specifically adapted for the production of Liquidmetal components

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Switzerland, France, Great Britain and Sweden. It was reported that besides plastics processors, many metal processors also took the opportunity to get to know the new technology.

Liquidmetal Technologies, based in Rancho Santa Margarita, California, USA, has developed a group of zirconium-based alloys that can be ‘liquid metal injection moulded’. As Liquidmetal’s exclusive engineering partner, Engel is the only supplier in the world offering machinery and system solutions for the injection moulding of these materials. A third partner is Materion Corporation, the material producer and distributor based in Mayfield Heights, Ohio, USA. During the event, the three partners jointly presented the new materials, injection moulding for processing them efficiently and the potential they have for applications.

“Thanks to their amorphous, non-crystalline structure, components made of Liquidmetal are extremely hard, but at the same time very elastic, which leads to very good recovery behaviour,” stated Steffen Mack, Business Development Manager at Materion. “They have low specific weight, are corrosionresistant and biocompatible.”

The fact that the alloys can be processed by injection moulding is a further advantage compared to other metal materials, because this makes particularly efficient, highly automated and integrated processing methods possible. In only one step, injection moulding delivers fit-forpurpose components with very high quality surfaces.

“These characteristics are fascinating for anyone who works with plastics or metals,” stated Heinz Rasinger, Vice President Engel teletronics. “Now it is all about the question of how we can make the best possible use of these characteristics.

We have discussed some very concrete ideas together with the participants at our forum. The results have shown that it will be less a question of substituting the material in existing products, but much rather how we can design components in a way that can take full advantage of

© 2016 Inovar Communications Ltd

Vol. 10 No. 1

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emphasised Christoph Lhota, Vice President Engel medical, giving as an example the long and sometimes very delicate instruments for keyhole surgery. Further application examples that were discussed in Stuttgart include functional components for electrical devices and decorative elements for automotive interiors.

In a recent technology development, combining Liquidmetal with other metals or plastics in a multi-component process has been investigated. “At our technology centre in California we have already fabricated sample multi-component parts with Liquidmetal and another metal,” stated Thomas Steipp, CEO at Liquidmetal Technologies.

In 2014 Liquidmetal began

installing capacity for contract manufacturing. It now has its ISO 9001:2008 certification and is manufacturing parts for customers.

“It is not necessary for those who would like to get started with the new technology to first invest in a manufacturing cell of their own,” stated Steipp. “We are prepared to supply prototype and production parts now from our Manufacturing Center of Excellence in California.

Additionally, it is our goal to also establish contract manufacturing capacities in Europe.” All that is needed for getting started is a licence that is conferred by Liquidmetal Technologies. Apple and Swatch are already among the first licensees. www.liquidmetal.com

Further reading The article “Liquidmetal® and MIM: Two complementary metal forming technologies” was published in the September 2014 issue of PIM International, available to download free of charge from www.pim-international.com

Vol. 8 No. 3 SEPTEMBER 2014

the potential of the material. What we experienced during these two days is an almost euphoric optimism, comparable with the emergence of thermoplastics.”

A panel of experts gave conference participants the opportunity to discuss their product ideas and questions in a small, confidential circle of experts from Engel, Liquidmetal Technologies and Materion. Some companies brought sample components and CAD drawings for this purpose. “For some products, the discussions led to some very promising approaches,” stated Rasinger. “We will be starting the first projects shortly.”

The panel of experts confirmed once again that there will be a broad field of applications, from medical technology to electronics, automotive to aerospace and even sports equipment. “Liquidmetal offers great potential in particular for components subject to strong mechanical strain with high demands on component design and surface quality,”

in this issue

Published by Inovar

Understanding MIM in China Liquidmetal vs MIM PIM at the PM2014 World Congress Communications

Ltd

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onal.com

M verIM in China

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Industry News

Ruger’s in-house MIM operation increases speed to market for new firearms components

Arburg announces its Technology Days 2016 event

Sturm, Ruger & Company, Inc., commonly known as Ruger, is a leading US designer and manufacturer of firearms including rifles, pistols, revolvers and shotguns. In November 2014 the company purchased US MIM producer Megamet Solid Metals Inc., based in St Louis, Missouri.

The company has since stated that the acquisition of Megamet not only secured valuable in-house MIM production capacity, but also brought the significant advantage of improving the company’s speed to market for new products.

Michael Fifer, CEO of Sturm Ruger & Company Inc., stated at the company’s 2015 Annual Shareholder’s Meeting that the key benefits of having an in-house

Arburg GmbH & Co. KG, a leading manufacturer of injection moulding machines, has announced that its Technology Days 2016 event will be held at its headquarters in Lossburg, Germany, from March 16-19 2016.

Around 40 exhibits will demonstrate the current state-of-the-art processing technology. The main focus at this industry event will be on the topics of production efficiency and ‘Industry 4.0 – powered by Arburg’.

It is estimated that around 7,000 visitors from 50 countries will attend this annual event, which will feature the latest innovations relating to production efficiency and process solutions. The company’s PIM laboratory will also be open to visitors during the event. www.arburg.com

Jiangxi Yuean Superfine Metal Co., Ltd Tel: +86 797 8772 869 Fax: +86 797 8772 255 Xinhua Industrial Park, Dayu County, Jiangxi Province www.yueanmetal.com

18

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MIM operation was in new product development, where new parts can often benefit from minor modifications or improvements. With outsourced MIM part production, Fifer suggested that it can take twelve to sixteen weeks to change the tool and be able to produce new main parts. By bringing parts of this in-house, Ruger can take the decision to focus on the must-have components and prioritise them in the production schedule.

Whilst the primary purpose of Ruger’s MIM operation is for the development and production of MIM components for internal use, it has been reported that the company undertakes the limited production of MIM parts for external customers. www.ruger.com

YUELONG GmbH Tel: +49 6074 9147 933 b.li@yueanmetal.com

Powder Injection Moulding International

March 2016

US Distributor United States Metal Powders, Inc. Contact: Rhonda Kalser rhonda.kasler@usbronzepowders.com Tel: +1 908 782 5454

© 2016 Inovar Communications Ltd

Vol. 10 No. 1

Catalytic debinding systems for large scale production ShenZhen SinterZone Technology Co. Ltd,.

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Husky receives innovation award for valve-gate technology Husky Injection Molding Systems, a leading supplier of injection moulding equipment and services, based in Bolton, Ontario, Canada, has received the Ringer 2015 Technology Award for the development of its Ultra Helix™ valve-gate technology and its contribution to injection moulding efficiency and cost effectiveness. The award was presented to company representatives at the Ringer Technology Innovation Awards in Shanghai at the end of October 2015.

“We are pleased that Ultra Helix has been chosen to receive one of the industry’s most prestigious awards,” said Stefano Mirti, Husky’s President of Hot Runners and Controllers.

When developing Ultra Helix™, Husky conducted extensive research for a deeper understanding of the fundamentals of valve gate dynamics, wear and gate quality. As a result, Ultra Helix™ can direct-gate parts with gate vestige that is nearly unmeasurable, maintaining this level of quality for millions of cycles. The advantages claimed include:

EPMA PM Summer School 2016 The European Powder Metallurgy Association (EPMA) has announced that its 2016 PM Summer School will take place in Valencia, Spain, from June 27 to July 1, 2016. The five-day residential training course will be a mix of lectures, given by experts drawn from both industry and academia, laboratory work, group discussion, problem solving and a

factory tour. Topics to be covered include the manufacture of metal powders, MIM, modelling, sintering, HIP, magnetic materials and AM. The Summer School is designed for young graduate designers, engineers and scientists from disciplines such as materials science, design, engineering, manufacturing or metallurgy. Graduates under 35 and who have obtained their degree from a European institution are eligible to apply. www.epma.com

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Submitting your news...

To submit news to PIM International please contact Nick Williams: nick@inovarcommunications.com

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PM Tooling System The EROWA PM tooling system is the standard interface of the press tools between the toolshop and the powder press machine.

Its unrivalled resetting time also enables you to produce small series profitably. www.erowa.com

March 2016 Powder Injection Moulding International

21

Industry News

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ARC Group Worldwide reports second quarter fiscal year 2016 results ARC Group Worldwide, a leading global provider of advanced manufacturing and 3D printing solutions, has reported its second quarter fiscal year 2016 (ending December 27, 2015) results. ARC has significant Metal Injection Moulding operations in the US and Europe.

Second fiscal quarter 2016 revenue was $25.0 million, a 2.2% increase sequentially compared to the first fiscal quarter of 2016. It was stated that the increase was due to early stages of momentum in several key market segments served by the company, along with record metal 3D printing revenue. Adjusted EBITDA for the second fiscal quarter was $2.9 million, an 8.4% increase sequentially compared to the first fiscal quarter of 2016. Adjusted EBITDA margin increased to 11.5%, from 10.8% in the prior sequential

Cremer_1213_Anzeige_210x148_Gelb_V2

22

quarter, reflecting greater operational efficiencies.

It was also stated that ARC has launched a new initiative in Mexico, which is expected to begin operations in the coming months. It was stated that ARC Mexico should help the company be more competitive in winning new North American business and improving margins. The exact nature of the Mexico operations has not been disclosed.

Jason Young, Chairman and CEO, commented, “While we are encouraged by the positive sequential performance, we are still in the early stages of building momentum in sales. We remain focused on improving speed to market for our customers and helping them consolidate their supply chain with our holistic solution. Under our new sales leadership and focus, we

Powder Injection Moulding International

Mittwoch, 22. Januar 2014 14:32:56

March 2016

A 2015 MPIF award winning breech block made for Smith & Wesson by Advanced Forming Technology (AFT), an ARCMIM company believe we are making good progress educating our customers about our differentiated solution and expect to get continued traction over time. We are also encouraged by the growing demand for our metal 3D printing services, which we expect to be a major growth driver in the future.” www.arcmim.com

© 2016 Inovar Communications Ltd

Vol. 10 No. 1

-45 Micron to -325 Mesh

Stainless Steel Fine Powders for MIM & Other Specialty Applications More than 25 years ago, AMETEK developed a proprietary method of producing and processing fine metal powders for our customers’ exacting specifications. Today, our ongoing commitment to innovative and advanced metallurgical technology, and the ability to offer customized formulations, grades, and sizing (from -45 micron to -325 mesh), makes AMETEK your best choice.

Austenitic Stainless Steel 316L is used in applications which require good corrosion resistance, strength, and ductility. Also available in 304L, 310L, and 347L. Ferritic Stainless Steel 430L ferritic stainless steel combines good magnetic response with corrosion resistance. Also available in P410L, P434L, P409, and P420.

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MIM specialist Dynacast acquires Tek-Cast Inc Dynacast, the global manufacturer of precision die cast and Metal Injection Moulded components headquartered in Charlotte, North Carolina, USA, has signed an agreement to acquire Tek-Cast Inc./ MH Machining Group in Bensenville, Illinois, USA. The acquisition will further expand Dynacast’s multi-slide zinc, aluminium capacity and CNC machining depth in North America.

“Dynacast has a rich history of continuously refining our proprietary manufacturing technologies, in-house tooling expertise and innovative design processes. It means that, today, we can manufacture highly complex metal components in a fast, repeatable and precise manner.

We look forward to bringing added insight and capabilities to Tek-Cast’s customers,” stated Simon Newman,

Chairman and Chief Executive Officer of Dynacast. “Additionally, this acquisition is the first step of many more to come over the next year or two.”

With the support and investment from Partners Group, American Industrial Partners (AIP), Kenner and Company, and management, Dynacast added that it has the strategic insight and capital backing to achieve its global vision of growing to a $1.5 to $2 billion organisation over the next three to five years. www.dynacast.com

Jonathan Wroe, EPMA Executive Director, dies age 61

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The European Powder Metallurgy Association has reported that Jonathan Wroe, the association’s Executive Director, has died following a short illness. Wroe, who was 61, has been the EPMA’s Executive Director since 2001.

Under Wroe’s leadership the EPMA has seen its membership grow to record levels, new sectorial and working groups formed and many EU funded projects established and coordinated by the trade association. As well as broadening the scope of the popular series of Euro PM Conferences, Wroe was integral in the development of PM industry road maps, launch of the Global PM Property Database and the publication of a wide variety of free PM technology guides.

Jonathan Wroe will be missed by the PM community, not least by those at the EPMA secretariat, the association’s board and all who have worked with him over the years. www.epma.com

www.centorr.com/pi 24

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March 2016

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Praxair uses Ames Lab’s atomisation technology for MIM and AM Ti powders Ames Laboratory, the US Department of Energy Office of Science national laboratory operated by Iowa State University, has announced that titanium powder created with its gas atomisation technology is now available from Praxair Inc. The fine, spherical titanium powder is suited for both the Metal Injection Moulding and Additive Manufacturing of aerospace, medical and industrial parts. It marks the first time large-scale amounts of titanium powder are available to industry with a potential for low-cost, high-volume manufacturing, Ames stated.

“Titanium powder made with this technology has huge potential to save manufacturers materials and money,” stated Iver Anderson, a senior metallurgist at Ames.

“Creating titanium powder of high quality at great volumes was what we materials scientists called the Holy Grail of gas atomisation.”

Titanium’s strength, light weight, biocompatibility and resistance to corrosion make it ideal for use in parts ranging from aircraft wing structures to replacement knee joints and medical instruments. Using ultra-fine, high-purity spherical titanium powder to additively manufacture or mould these parts generates around ten times less metal waste than traditional casting of parts. However, ultra-fine titanium powder was nearly impossible to produce from the molten state because liquid titanium is readily contaminated by dissolved gases and can’t be contained by normal ceramic melting crucibles, which it can rapidly erode, to the point of spilling through, Ames stated.

“Our invention of an in-stream melt heating guide tube was critical to boost the melt temperature by at least 100˚C, allowing adaptation of water-cooled ‘clean’ melting technologies, normally used to melt and cast strong, reliable aerospace Ti parts,” stated Anderson.

“This new ‘hot nozzle’ made possible precise feeding of highly energetic close-coupled atomisers for efficient production of fine Ti powders.” Two members of Anderson’s research team, Joel Rieken and Andy Heidloff, created a spinoff company, Iowa Powder Atomization Technologies, and exclusively licensed Ames Laboratory’s titanium atomisation patents. IPAT worked to further optimise the titanium atomisation process and along the way won several business and technology awards for their efforts, including the Department of Energy’s Next Energy Innovator competition in 2012. In 2014, IPAT was acquired by Praxair, a Fortune 250 company and one of the world’s largest producers of gases and surface coatings.

“We talk regularly about the Department of Energy’s goal of transferring research from the scientist’s bench to the marketplace. This work is a strong example of how that goal can become reality. The ingenuity and

Vol. 10 No. 1 © 2016 Inovar Communications Ltd

A titanium bolt and the corresponding amount of titanium powder necessary to create it continued hard work and commitment by our scientists and our licensee to get the technology to market cannot be underestimated. They make my job of transferring technology developed at Ames Laboratory into the marketplace so much easier,” said Ames Laboratory Associate Director Debra Covey. Gas atomisation work at Ames Laboratory was supported by the Department of Energy’s Office of Science and Office of Fossil Energy and the specific work on titanium powder was supported by Iowa State University’s Research Foundation, the State of Iowa Regents Innovation Fund and the U.S. Army. www.ameslab.gov | www.praxair.com

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| contents page | news | events | advertisers’ index | email | MIM in the firearms industry

February this year Kalashnikov HIPone-day in the manufacture of Randall German to present Concern announced that it was MIM firearms components PIM considering tutorial atventure PMinChina 2016 a joint

fully dense part will have a significant positive impact on reliability, lowering field failures.”

In a drive to deliver parts with the India with a new plant capable of Poor noted, however, that there are greatest possible performance, manufacturing 50,000 weapons the tutorial a number of important considerations is custom designed Prof. Randall M German, a leading 50-60% of all firearms parts per year. It was suggested that any when considering the HIP of MIM for presentation in Shanghai. It is PIM industry expert and consultant manufactured in North America venture would involve the production parts, stating, “Many of the MIM planned that audience will have the based in San Diego, USA, will, at today areboth Hotin Isostatically Pressed of combat weaponry as well as tutorial material components used in the firearm English and the invitation of the PM China 2016 (HIPed) to full density in order to firearms for civilian use. “India isChinese a industry are small, thin walled, and for better understanding and Organising Committee, be giving a The PM China Expo is the largest PM improve toughness, ductility and very promising market, and the best have complex geometry making the communication. Topics to be covered one-day tutorial on Powder Injection exhibition in China fatigue strength.

The need for a way to enter it is to set up production part difficult if not impossible to include: Moulding during this year’s event.

HIP process depends largely on the• Unit straighten. there,” stated Alexei It is therefore extremely manufacturing cells PM China 2016 will take placeKrivoruchko, in • Powder and binder selection specific application and performance Chief Executive and part-owner of important for the HIP provider to Shanghai, China, from April 27-29.

• Plant layout options • Feedstock formulation and part. requirements of a MIM Kalashnikov Concern, in February consider matching the correct cycle The tutorial will be held on April 26.

• Process optimisation and characteristics Commenting on the reasons 2014.

“We will begin to set up temperature to the part material The one day seminar is set to be computer simulations behind the growing use of HIP in this year.” [8] and loading methods that reduce or • Tooling design an evenlyproduction balanced theory-practice • Identification of ideal applications the manufacture of MIM parts for eliminate distortion of parts. Diffusion • Processing and manufacturing seminar designed for engineers, the firearms industry, Dennis Poor, • Markets, applications and Other Asian countries bonding of parts loaded incorrectly decisions manufacturing personnel, educators President of Kittyhawk Inc, a leading economic parameters Japan, an early adopter of MIM must also be dealt with.

Firearm and students. It is ideal for new • Equipment options and merits PIM US provider of HIP services, told technology, is understood not to parts also include an interesting • Industry structure and standards employees of firms already involved in • Cost contributions, process yield, International, “The obvious answer• Emerging have any significant MIM firearms and serious challenge to the HIP markets metal and ceramic injection moulding, inspection is that HIP will provide the end user production, with its key markets service providers as some parts have business development managers, • Innovations and emerging trends • Component design with fully dense parts.

That said it being automotive, medical devices additional government regulations marketing and sales engineers, high profit targets forspecialised PIM • Materials, properties and that MIM can • Some should also be noted and industrial equipment.

Likewise, and controls requiring designers and users of MIM and issues provide parts at a reduced cost, in a morelicensing there is understood toand be little MIM performance for ‘any orMaggie all’ entities For information email the growing array of suppliers net or near net shape that eliminates firearms production in Singapore or handling the parts.”

• Testing techniques and options Song, pmexpochina@163.com equipment vendors. Previously or reduces machining costs and a www.cn-pmexpo.com Taiwan.

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Industry News

FCT Anlagenbau GmbH promote, design, manufacture and sell systems for the development and production of heavy-duty material.

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Innovative MIM device for medical cutting curette An innovative medical device for use in otorhinolaryngology (ear, nose and throat – ENT) has been developed using Metal Injection Moulding technology by researchers at the Tomas Bata University in Zlin, Czech Republic. They reported in a paper published in the Proceedings of the 8th International Conference on Materials Science, Rome, November 7-9, 2015, that the design of the current one-piece curette used for removal of the nose tonsils (adenoids) in a procedure called adenoidectomy, makes it impossible to change a damaged or worn cutting edge. It also requires sterilisation after each surgical procedure. They have therefore designed a type of curette, which has a disposable cutting edge

Fig. 1 Proposed design of cutting curette (From paper: ‘Innovative medical device for Otorhinolaryngology produced by Powder Injection Molding’, by H. Jakub, et al. Proceed. of 8th Int. Conf. on Materials Science, November 7-9, 2015, pp 135-138.) made by MIM of a sterile austenitic 316L stainless steel and which would not have the additional cost of sterilisation or sharpening. The cutting edge can of course also be produced from other PIM metals or ceramics.

The proposed design of the ENT

curette (Fig. 1) comprises three parts: holder, main body for the cutting edge and the disposable MIM stainless steel cutting edge. The holder also allows different geometries to be produced to suit the specific shape of the oral cavity of the patient. www.utb.cz

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Industry News

PSI Limited Advanced Process Solutions

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PIM process studied for production of nuclear fuel Nuclear fuel pellets used in current nuclear reactors are traditionally made by a Powder Metallurgy process involving the compacting of uranium dioxide (UO2) powder in a die and sintering. Deformations can occur during sintering because of density gradients in the green compacted pellets and this requires a post-sintering grinding operation in order to meet the strict fuel specification on the pellet diameter.

This must be ±12 µm in relation to a specified diameter of 8.192 mm. The post-sintering grinding operation is a very impacting process from a radiological viewpoint in the nuclear field and simplifying the current process but yet meeting dimensional tolerances would enhance productivity, as well as reducing the radiological impact. This will be particularly important in the prospective emergence of Generation IV nuclear reactors, where the current PM process may hinder nuclear fuel innovation.

The possibility of directly manufacturing net-shape UO2 nuclear fuel pellets without the need for a postsintering grinding step has been studied by a team of researchers at CEA - Cadarache in Saint Paul Lez Durance and the Universite de Franche-Comte, Besançon, with the focus on using the Powder Injection Moulding process. CEA - Cadarache is one of ten research centres of the French Alternative Energies and Atomic Energy Commission.

The researchers led by J. Bricout state in their report published in Powder Technology (Vol.279, 2015, pp 49-60) that the main objective of using the PIM process was to simplify the current PM process.

For example, introducing feedstock binders (forming aids) would make it possible, upstream, to restrict the powder preparation operations (crushing, mixing, etc.), and thereby eliminate the dispersal of contaminating and irradiating powder (reducing the radiological

Powder Injection Moulding International

March 2016

exposure of operators). The possibility of directly manufacturing net shaped PIM pellets would also mean that the post-sintering grinding step could be eliminated. The grinding step is a very impacting process from a radiological viewpoint in the nuclear field. The researchers also believe that the PIM process offers innovation possibilities in terms of the flexibility for new designs of nuclear fuel pellets for the new generation of nuclear reactors.

UO2 produced by a dry manufacturing process was selected as the powder for testing the interaction with the forming aids (binders) in the feedstock. This powder is depleted in isotope 235U (235U wt% = 0.3) so that the irradiating phenomena – especially those causing the radiolysis of organic matter – will not have a significant impact. UO2 powder generally consists of three compounds: • Crystallites: the smallest components (submicron size) which can be identified with an SEM, • Aggregates: clusters of presintered crystallites (strong bonds which are practically unbreakable) with a non-convex shape, • Agglomerates: groups of aggregate.

The morphological characteristics of the UO2 powders are very different from those of powders generally implemented in the PIM process.

The UO2 powder used for the study comprised deformed agglomerates of sizes varying from 10 to 200 μm, aggregates around a micrometre and crystallites with an average size of 0.3 μm.

The authors stated that selecting the forming aids (binder) for UO2 nuclear fuel pellets is critical to the success of the PIM process and they used thermoplastic systems containing polyolefins and wax. Six forming aids were chosen for their suitability with actinide powders with their characteristics from the formu-

© 2016 Inovar Communications Ltd

Vol. 10 No. 1

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Name

Molar mass (g/ mol)

Density

Polypropylene

PP1

12,000

0.9

Polypropylene

PP2

190,000

0.9

Polymer

Low density polyethylene

LDPE

0.93

Polymethyl methacrylate

PMMA

120,000

1.18

Polystyrene

PS2

192,000

1.06

Polystyrene

PS1

35,000

1.06

Paraffin wax

PW

Stearic acid

SA

0.9 284.84

0.94

Table 1 Characteristics of forming aids (binders) selected to prepare PIM feedstock formulations (From paper: ‘Evaluation of the feasibility of the PIM process for the fabrication of nuclear fuel and comparison of several formulations’, by J. Bricout et al, Powder Technology (Vol. 279, 2015, pp 49-60))

Surfactant

Proportion vol.%

PW

SA

40:55:5

PP1

PW

SA

40:5:5

Fc

LDPE

PP2

SA

40:55:5

Fd

PS2

PW

SA

40:55:5

Fe

LDPE

PW

PS

SA

31.6:43.4:20:5

Ff

LDPE

PW

PMMA

SA

31.6:43.4:20:5

Binder

Plasticizer

Fa

LDPE

Fb

Radiolysis addition

Table 2 Six forming aids (binders) assessed in the study (From paper: ‘Evaluation of the feasibility of the PIM process for the fabrication of nuclear fuel and comparison of several formulations’, by J. Bricout et al, Powder Technology (Vol. 279, 2015, pp 49-60)) lations in Table 1. The six forming aid systems chosen are shown in Table 2.

Based on the thermal and rheological data, PP2, PS2 and LDPE were chosen to ensure the bonding properties of the system; PP1 and PW were chosen as the plasticisers to make the polymer system more viscoelastic by modifying its plasticity.

Stearic acid was chosen as the surfactant. UO2 powder loading in the feedstock was 50 vol.%.

Because of the lack of an injection moulding machine, the PIM process was simulated through the use of hot pressing to produce the nuclear fuel pellets. The feedstock was hot pressed at 220°C and pressure of 76 MPa to simulate high pressure PIM to produce pellets having good homogeneity of density leading to homogeneous shrinkage during sintering.

Vol. 10 No. 1 © 2016 Inovar Communications Ltd

However, the hot pressing process can lead to shape or surface defects during ejection from the mould, but such defects are not expected to exist when using the PIM process itself.

The hot press was used to make pellets with a diameter of 10 mm and a length between 5 and 20 mm.

The authors state the choice of formulation at the beginning of the process makes it possible to control the final microstructure of the sintered pellets which reached a theoretical density of 96%. However, the contribution of each mechanism studied needs to be explored further in-depth in order to be able to accurately control the properties of the final pellet through the microstructure.

The maximum residual carbon content specified in the fuel pellets

Fig. 1 Nuclear fuel pellet produced

by PIM process (From paper: ‘Evaluation of the feasibility of the PIM process for the fabrication of nuclear fuel and comparison of several formulations’, by J. Bricout et al, Powder Technology (Vol. 279, 2015, pp 49-60))

is 100 ppm. The carbon residue after debinding was between 2500 and 4000 ppm but this was reduced to between 100 and 150 ppm after sintering. This was considered to be adequate as the debinding and sintering conditions were not optimised.

In terms of metrology the fuel specification on the nuclear fuel pellet diameter is very strict, ±12 μm min to specified diameter of 8.192 mm.

The researchers state that their research confirms that PIM is capable of directly producing net-shape fuel pellets after sintering without requiring post sintering grinding.

Fig. 1 shows a pellet fabricated with a feedstock initially loaded with 56 vol.% of UO2 (use of the Fb formulation).

They also stated the formulations of the forming aids studied are theoretically resistant to radiolysis phenomena due to the benzene rings of the polystyrene. These advantages and positive results will be consolidated with studies involving both UO2 and PuO2, especially to quantify radiolysis effects.

March 2016 Powder Injection Moulding International

31

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Iver Anderson named a Fellow of the National Academy of Inventors The US Department of Energy’s Ames Laboratory has announced that Iver Anderson has been named a Fellow of the National Academy of Inventors (NAI). The NAI Fellows Selection Committee credited Anderson for demonstrating a highly prolific spirit of innovation in creating or facilitating outstanding inventions that have made tangible impact on quality of life, economic development and welfare of society.

Anderson is widely known for his co-invention of lead-free solder, an alloy of tin, silver and copper, used globally as a replacement for lead-based solders that can pollute soil and groundwater. The lead-free solder patent is the top-earning patent for Ames Laboratory, Iowa State University (Ames Laboratory’s contractor) and Sandia National

Laboratory. It has generated approximately $60 million in royalty income throughout the life of the patent, which expired in 2013. At its peak, more than 50 companies in 13 countries licensed the invention.

In addition to lead-free solder, Anderson has used gas atomisation technology he and his colleagues developed to produce fine, spherical titanium powder for the Additive Manufacturing and Metal Injection Moulding of aerospace, medical, and industrial parts. A spinoff company, Iowa Powder Atomization Technologies, was created in 2012 to exclusively license Ames Laboratory’s titanium atomisation patents. In 2014, IPAT was acquired by Praxair, a Fortune 250 company and one of the world’s largest producers of gases and powder-based surface coatings.

“I am honoured to have been recognised as an NAI Fellow,” stated Anderson, “This award is an outstanding endorsement of contributions academic inventors like me make to research and, in particular, research that can make a lasting impact on society.”

Anderson will join the NAI Fellows named in 2015 for an induction ceremony on April 15, 2016, at the US Patent and Trademark Office. The induction ceremony will be part of the Fifth Annual Conference of the National Academy of Inventors in Washington, D.C. “Iver has dedicated his career to conducting outstanding research and his commitment to excellence has paid off through the awarding of this Fellow recognition,” stated Ames Laboratory Director Adam Schwartz.

“He has accomplished much and we fully expect his list of inventions to grow further in the years ahead.” www.ameslab.gov

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Herbert Danninger and Alberto Molinari receive honorary doctorates from Spain’s Universidad Carlos III de Madrid Spain’s Universidad Carlos III de Madrid (UC3M) has awarded honorary doctorates to Professor Herbert Danninger, TU Wien, Austria, and Professor Alberto Molinari, University of Trento, Italy. The award is the university’s highest academic distinction and is given to an individual for their academic, scientific or artistic endeavours.

Both Danninger and Molinari are international experts in the field of materials science and engineering. “They are two exemplary figures in their field of knowledge,” stated Professor Mónica Campos during the ceremony. Campos is a professor in the UC3M Department of Materials Science and Engineering and Chemical Engineering. This

department and the Álvaro Alonso Barba Technological Institute of Chemistry and Materials promoted the investiture of the new doctors’ honoris causa.

In his acceptance speech, Danninger stated that it was a great honour to receive this degree from a university he has collaborated with for many years as a result of a shared interest in Powder Metallurgy. Professor Molinari, who also participated in joint research projects and teaching under the auspices of the Höganäs Chair, was deeply moved by the new honorary doctorate award. In his speech, he defended teaching and research as complementary and basic paths at university. In addition, both mentioned the collaboration

with UC3M Full Professor José Manuel Torralba, who was also attending the event as the regional government’s head of the Directorate General for Universities and Research.

Both academics are linked to the prestigious Höganäs Chair in Powder Metallurgy, in which the UC3M participates. They have made many contributions through this association, such as participating in doctoral courses and other educational sessions, the exchange of doctoral students, the creation of joint science publications, etc.

With more than 400 scientific publications in renowned journals, Danninger and Molinari have taught for more than a quarter of a century and held important posts at their universities. “Both have known how to maintain continuous relations with companies from the sector, allowing and facilitating an effective transmission of knowledge to companies,” added Campos. www.uc3m.es

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PTECH 2015: A window on PIM developments in Brazil Despite the slowdown in the growth of Brazil’s economy in recent years, with the automotive industry in particular struggling, there is continuing optimism for the future of the country’s relatively young Powder Metallurgy community, both in academia and industry. This was the message from the 10th Latin American Conference on Powder Technology, PTECH 2015, which took place in Mangaratiba, some 120 km from Rio De Janiero, November 8-11, 2015.

The bi-annual PTECH conference celebrated 20 years of bringing together academics, PM production and industry suppliers to share their latest research and advances in PM production and applications. It also gave around 250 delegates from Latin America’s Powder Metallurgy and associated sectors the opportunity to network with a number of overseas participants and exhibitors representing powder, feedstock and equipment suppliers.

Dr Bodo Fink, Managing Director of GMC Feedstocks, and one of PTECH 2015 sponsors, told PIM International, “The PTECH conference is a fruitful platform to get in contact with metalworking industry and universities in Brazil.

Face-to-face contact is essential in the MIM business, and

Brazil shows a lot of new opportunities in the engineering, automotive, aerospace and medical sectors.”

Around 240 technical papers were presented at PTECH 2015, either in oral or poster sessions covering the following areas: • Synthesis: Mechanical alloying, Metal Matrix Composites, Nanomaterials, • Processing: PM compacting, MIM and Additive Manufacturing, Plasma Assisted Sintering and heat treatment • Properties: Corrosion and mechanical properties, • Applications: Wear resistant, biomaterials, magnetic materials.

Ana Cristina Marcucci and Dr Fink gave the plenary talk on feedstocks for high-tech ceramic and metal applications. Marcucci stated that MIM and CIM had not only become large scale and viable production processes over the past decade, but that in recent years PIM had also targeted other novel applications which required PIM feedstocks based on materials different from the well-established iron-nickel and stainless steels that are now commonplace.

They described the development of several CIM and MIM components in medical, automotive and machinery applications, giving details of materials processing and properties obtained. Various examples showing the benefits of PIM versus established shaping processes such as investment casting were shown.

MIM of rare earth alloys L U Lopes and P A Wendhausen presented their research into the use of MIM for reactive metals such as rare earth based alloys. They stated that MIM is much less common as a manufacturing process in this area due to the challenges of preventing oxidation during the manufacturing process and contamination with binder residues. The authors reported on a literature review of the techniques developed to circumvent such issues, mostly focused on the fabrication of rare-earth based magnets, as well as the remaining technological challenges. These are mostly related to dimensional stability and anisotropic shrinkage that takes place in magnets with the presence of crystallographic texture.

Similarities between gelcasting and MIM An interesting presentation on the gelcasting process was given by F S Ortega and L F Oliveira, who also compared the process with MIM. They describe the gelcasting process as a consolidation technique that consists of filling a mould with a highly loaded aqueous suspension followed by gelation due to the polymerisation of watersoluble monomers. Although this process has been widely used for shaping ceramic parts using colloidal suspensions, its application with metal powders is less well known due to rapid settling of larger and denser metallic particles. In their research HK-30 stainless steel powders with different grades (10F and 20F) were gelcast

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Fig. 1 Views of the PTECH 2015 poster displays, conference sessions and exhibition. Around 240 technical papers were presented at PTECH 2015.

Fig. 2 Prof. Dr. Ing. Henning Zoz (left), who gave the opening keynote presentation on “Innovation in Materials and Processes - how to change a good idea into a good product” and Dr. Ing. Nério Vicente Junior (right), the Organizing Committee Manager

into cylindrical moulds (90 mm high) with the help of a suspending agent. The gelled bodies were dried, vacuum sintered and sliced across the settling direction in order to assess the effect of the suspending agent on particles settling. Both the sintered density and the microstructure were homogeneous along the cylinder axis, showing that any effect associated to particles settling could be avoided.

Final density was close to the theoretical value, although the samples produced with 10F grade powder showed a small residual porosity. The microstructures were similar to those reported for this powder processed by MIM.

The PTECH 2015 conference proceedings will be in Materials Science Forum by Trans Tech Publications. The next conference in the series, PTECH 2017, will be held in Natal, Rio Grande do Norte, Brazil, in November 2017.

Many thanks to Ana Cristina Marcucci for contributing material and images used in this review.

Self-lubricating steel composites Tatiana Bendo and colleagues from the Universdade Federal de Santa Catarina presented a paper on selflubricating composites containing second phase particles incorporated into the volume of the material. This appears to be a promising solution for controlling friction and wear in mechanical systems. The aim of this work was the development of steels with low friction coefficient through a precursor (SiC) that generates nanostructured carbon nodules in a ferrous matrix. The samples were processed by conventional PM route, namely single pressing using the fine powders also typically used in PIM, after granulating them. The purpose of producing granulates was to obtain a better distribution of the carbon nodules.

The alloy composition studied was Fe-0.6C-3SiC using 2 wt.% of EVA as binder for the granulate. The influence of the fine sizes of iron and silicon carbide particles on the microstructure, mechanical and tribological properties were evaluated. The powders were homogenised in a "Y" type mixer, drum granulated, pressed and then plasma sintered in a single cycle combining binder extraction and sintering of the constituent components. The alloys have achieved results close to alloys with same composition produced via PIM but with processing time and cost closer to that of conventional PM.

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Powder Technology (Vol.279, 2015, 196-202), have shown that using a bimodal micro-nanopowder PIM feedstock allowed improved control of the sintering behaviour of 316L microPIM parts achieving high density and a fine microstructure.

The researchers had previously There is increasing interest in the for mass production of complex reported on the successful use development of microsystems and net-shape microcomponents. of bimodal mixtures of 25 vol.% related products for sectors such Research results by Joon-Phil Choi nano- and 75 vol.% micropowders as medical instruments, electronic and colleagues at Hanyang Unversity, based on iron powders to increase devices and automotive components Korea Institute of Materials Science powder loading in PIM feedstock and Powder Injection Moulding is (KIMS), and Korea Institute of Indusup to 71%, with 66% being optimal. seen as one of the key technologies trial Technology, recently published in The bimodal powder feedstock exhibited superior flow behaviour during injection moulding at a relatively low temperature (70°C) and pressure (4 MPa). The nanopowders also helped to develop network formation between the micropowders, thereby improving green strength after debinding, and played a decisive role in the entire sintering process by enhancing densification but suppressing grain growth.

The success with the bimodal iron powder led the researchers to focus on bimodal 316L stainless steel, one of the most widely used materials in PIM. The 316L micronanopowder mixture of wassintered producedparts Linde is the leading supplier of industrial gases and innovative Carbon content using micropowder produced by technologies for the powder metallurgy industry. With SINTERFLEX® Epson Atmix Japan, having CarbonCorp, content without SINTERFLEX Linde has pioneered a real-time solution to monitor and dynamically averageCarbon particle size ofwith 4 µm, content SINTERFLEX and a nanopowder of 100 nm adjust your furnace atmosphere.

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by Nano Tech Inc., Korea. These in % Uniform carbon content were mixed in a ratio of 75/25 by Linde is the leading supplier of industrial gases and innovative Carbon content of sintered parts over an 8-hour period Linde is the leading supplier of industrial gases and innovative technologies for the powder SINTERFLEX® real-time carbon control system. technologies for theleading powder metallurgy industry.

With SINTERFLEX® Linde is the supplier of industrial gases and Carbon innovative Carbon content of sintered parts over an and 8-hour periodmixed with SINTERFLEX enables real-time monitoring for uniform carbon potential further content without SINTERFLEX Allowed carbon content ® and innovative SINTERFLEX® real-time carbon control system.

Linde the leading supplier oftoSINTERFLEX industrial Carbon content of sintered parts over an 8-hourvolume% period 0.6 metallurgy industry.

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With SINTERFLEX® paraffin wax/stearic binder to Carbon content without SINTERFLEX Allowed carbonacid content throughout sintering resulting in less in part Carbon and dynamically your adjust your furnace furnace, atmosphere.

Carbonvariability content without SINTERFLEX Allowed carbon content contentand dynamically Linde haspioneered pioneered a real-time solution to monitor Linde has a real-time solution to monitor and dynamically Carbon content with SINTERFLEXproduce 0.5the feedstock. The optimal Carbon content with SINTERFLEX in % Uniform carbon content quality. adjust your furnace atmosphere. adjust furnace atmosphere.

SINTERFLEX enables real-time monitoring for uniform carbon potential Linde Linde is the isleading supplier of your industrial gases and innovative Carbon content of sintered parts overover an 8-hour period 0.6 Carbon Carbon the leading supplier of industrial gases and innovative Carbon content of sintered parts an 8-hour period powder loading of 66% found with Uniform content throughout yourcarbon sintering furnace, resulting in less variability in part content technologies for the metallurgy industry.

With SINTERFLEX® content 0.5 0.4 technologies forpowder the powder metallurgy industry.

With SINTERFLEX® Carbon content without SINTERFLEX Allowed carbon content quality. in % Allowed Carbon content without SINTERFLEX Uniform carbon content SINTERFLEX enables real-time bimodal iron mixtures was used.

Linde Linde has pioneered a real-time solution to monitor and dynamically in % carbon content Uniform carbon content Carbon content with SINTERFLEX 0.4 has pioneered a real-time solution to monitor and dynamically Carbon content with SINTERFLEX SINTERFLEX enables real-timecarbon monitoring for uniform carbon potential adjustadjust your furnace atmosphere.

0.6 Cost efficiencies monitoring for uniform potential Cost efficiencies your furnace atmosphere.

The feedstock was then injection 0.3 carbon potential Carbon SINTERFLEX enables real-time monitoring for uniform 0.3 Carbon 0.6 SINTERFLEX reduces sintering costs furnace, by dramatically increasing throughout your sintering resulting in the less variability in part content content 0.2 throughout your sintering furnace, 0.5 throughout your sintering furnace, resulting in less variability in part number of parts within your specification and reducing the need moulded into a double gear cavity in % in % by dramatically Uniform carbon content SINTERFLEX reduces sintering costs increasing the quality.

Uniform carbon content 0.5 0.1 for post-processing. resulting in less in potential partpotential quality.

SINTERFLEX enables real-time monitoring for variability uniform carbon 0.4 0.2 0.6 0.6 SINTERFLEX enables real-time monitoring for uniform carbon on a screw-type injection moulding number of parts within your specification and reducing the need throughout your sintering furnace, resulting in less variability in part 0.4 quality. throughout your sintering furnace, resulting in less variability in part Cost efficiencies 1 2 30.3 4 5 6 7 8 Hours 0.5 0.5 machine at 70°C under the pressure quality. quality.

SINTERFLEX reduces sintering costs by dramatically increasing the Cost 0.1 for efficiencies post-processing.

0.3 0.2 0.4 0.4 of 4 MPa. Pressure was maintained number of parts within your specification and reducing the need SINTERFLEX reduces sintering costs by dramatically increasing the efficiencies Cost efficiencies info-heattreatment@linde.com, www.linde-gas.com/heattreatment Cost efficiencies Cost 0.3 0.3 0.1 for post-processing.

0.2 at 3 MPa to prevent moulding SINTERFLEX reduces sintering costsof by parts dramatically increasing the number within your specification and reducing the need SINTERFLEX reduces sintering costs by dramatically increasing theby SINTERFLEX reduces sintering costs 0.2 0.2 defects such as insufficient filling, number of parts withinwithin your specification and reducing the need number of parts your specification and reducing the need 0.1 for post-processing. dramatically increasing the number 2 3 1 2 3 4 5 6 7 8 Hours 1 0.1 0.1 for post-processing. for post-processing. voids or cracks. of parts within your specification and Following 4 5 debinding 6 7 the brown 8 Hours reducing the need for post-processing.

Hours 1 1 2 2 3 3 4 4 5 5 6 6 7 71 8 8 2 Hours 3 parts were found to have a uniform info-heattreatment@linde.com, www.linde-gas.com/heattreatment SINTERFLEX® is a registered trademark of The Linde Group. structure without defects such as info-heattreatment@linde.com, www.linde-gas.com/heattreatment info-heattreatment@linde.com, www.linde-gas.com/heattreatment info-heattreatment@linde.com, www.linde-gas.com/heattreatment distortion, cracks, or warpage. info-heattreatment@linde.com, www.linde-gas.com/heattreatment SINTERFLEX® is a registered of The Linde Group.

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Fig. 1a shows11.02.16 the brown PIM part 21673_TI_MG_Powder_Injection_Ad_RZ.indd 1 13:57

Bimodal 316L stainless steel micronanopowder offers improved sintering for microPIM parts

Raising the bar for sintering quality.

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21673_TI_MG_Powder_Injection_Ad_RZ.indd 1

11.02.16 13:57

SINTERFLEX® is a registered of The Linde Group.

SINTERFLEX® is a registered trademarktrademark of The Linde Group.

21673_TI_MG_Powder_Injection_Ad_RZ.indd 1 1673_TI_MG_Powder_Injection_Ad_RZ.indd 1

21673_TI_MG_Powder_Injection_Ad_RZ.indd 1

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Vol. 10 No. 1

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Fig. 1 SEM micrographs of (a) brown PIM part and (b) its fractured surface (From paper: ‘Sintering behaviour of 316L stainless steel micro-nanopowder compact fabricated by powder injection molding’, by J-P Choi, et al. Powder Technology Vol 279, 2015, pp 196-202)

1500

Temperature (°C)

Debinding

Sintering

100°C, 20 min (10°C/min) 200°C, 45 min (1°C/min) 500°C, 45 min (5°C/min) +Wicking (Al2O3)

1200 900

heat-up sintering tp 1300°C isothermal sintering at 110°C (10°C/min)

600 300 0

0.5h

0

100

200

300

1h

3h

400

Time (min)

5h

500

600

Microstructural observation

Fig. 2 Debinding and sintering regime used for PIM 316L micro-nanopowder samples (From paper: ‘Sintering behaviour of 316L stainless steel micronanopowder compact fabricated by powder injection molding’, by J-P Choi, et al. Powder Technology Vol 279, 2015, pp 196-202)

(b) 15 Shrinkage rate (%)

and Fig. 1b shows the homogeneous distribution of micropowders, nanopowders, and pores. The nanopowders are uniformly distributed among micropowders, which effectively increased the packing density and necking strength in the feedstock. The debound 316L stainless steel microPIM parts were sintered in hydrogen by (a) heating from 500°C to 1300°C and (b) isothermal sintering at 1100°C for 0.5 to 5 hr. The debinding and sintering regime is shown in Fig. 2.

The addition of nanopowders was found to significantly increase grain boundaries and micropores in the micro–nanopowder samples, which in turn enhances sintering activity and leads to limited grain growth during the entire sintering process as compared to that of the micropowder reference samples.

After heat-up sintering at 1300°C, the sintered density of the micro– nano and micropowder reference samples were measured to be about 90% TD and 85% TD, respectively.

At this point, the average grain size in the micro–nanosamples was evaluated as ~7 μm, which was much smaller than that of the micropowder sample (>15 μm). This nanopowder effect was also maintained at isothermal sintering conditions of 1100°C. After sintering at 1100°C for 5 h, the micro–nanopowder sample reached near full density of 98% TD with an average grain size of <10 μm, whereas the micropowder sample was composed of drastically coarsened grains at >20 μm. The sintered samples of micro–nanopowder also exhibited homogeneous shrinkage of 12% indicating adequate geometrical properties (Fig. 3).

The researchers conclude that the use of bimodal 316L stainless steel micro–nanopowder could open up new sintering techniques for manufacturing net-shape products with near full density and a fine microstructure.

10 D

C

5 B

0

A

B

C

A

D

Fig. 3 (a) SEM micrograph of sintered microPIM 316L gear and (b) linear shrinkage of the sintered part after sintering at 1100°C for 5 hr. (From paper: ‘Sintering behaviour of 316L stainless steel micro-nanopowder compact fabricated by powder injection molding’, by J-P Choi, et al. Powder Technology Vol 279, 2015, pp 196-202)

March 2016 Powder Injection Moulding International

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High porosity MIM titanium implants use new space holder removal method There are numerous applications for highly porous titanium structural components such as filters, sound and energy absorbers, sandwich cores for aerospace and submarines, electrochemical devices, etc. Highly porous titanium is also a promising material for bone implants due its good biocompatibility. With an appropriate level of porosity an elastic modulus similar to that of human

bone (4-30 MPa) can be achieved and using titanium thus reduces the risk of the stress-shielding effect.

The desired porosity level of course varies depending on the implant application. For spinal implants the most suitable porosity range is said to be 60-65% and pore sizes of 50 to 400 µm are reported for safe implant fixation and for high rate of bone ingrowth.

Powder load Sample code

To achieve the high levels of porosity required in titanium for implants, the space holder technique has become the most widely used method. Here the space holder material such as sodium chloride (NaCl) or potassium chloride (KCl) is mixed with the appropriate titanium powder and the mixture can be cold compacted to produce a preform from which the space holder material must be removed. This can be done by thermal decomposition, solvent dissolution, evaporation sublimation, etc., leaving pores of a predefined shape and size.

Binder

Powder load

Binder content

Ti

KCl

Paraffin

PE

SA

Sample shape

MIM 72

72

28

30

70

60

35

5

Cylindrical

MIM 75

75

25

30

70

60

35

5

Semi-cylindrical

MIM 80

80

20

30

70

60

35

5

Conical

Table 1 Feedstock compositions used to produce the MIM samples. (From paper ‘Increased shape stability and porosity of highly porous injection moulded titanium parts’ Advanced Engineering Materials Vol.17, No.11, 2015, pp 1579-1587)

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The removal of the space holder, for example sodium chloride (NaCl), takes place in a lengthy desalination step which can take 24 hrs for small parts and significantly longer for larger parts. The resulting porous preforms are then vacuum sintered.

Metal Injection Moulding is a potential manufacturing route for shaping relatively complex porous parts such as those used in small spinal implants and Professor A. Laptev and colleagues at Forschungszentrum Jülich GmbH, Germany, have investigated the use of MIM and the replacement of the lengthy dissolution in warm water to remove the space holder material in MIM preforms with an improved process involving sublimation. As reported in a paper published in Advanced Engineering Materials (Vol.17, 2015, pp 1579-1587) the sublimation process can remove the chloride-based space holder material during solid state sintering. This eliminates the lengthy water leaching step and speeds up the manufacturing process significantly.

The researchers used a fine, gas atomised powder produced by TLS Technik GmbH, Bitterfeld, Germany, mixed with an irregular shaped potassium chloride (KCl) powder which had been fractionised to 355-500 µm.

Three feedstock compositions having Ti powder loading of 72, 75, and 80 vol.% with a fixed space holder content of 70 vol.% were mixed with a binder comprising 60 vol.% paraffin wax, 35 vol.% high density polyethylene and 5 vol.% stearic acid as surfactant (Table 1). The resulting feedstocks were injection moulded at 150°C with a pressure of 90 MPa to produce samples of different geometries depending on powder loading. MIM 72 was used to produce cylindrical parts, MIM 75 semi-cylindrical and MIM 80 conical.

All the the samples were immersed in an n-hexane bath for 24 h at 50°C to remove the paraffin wax and stearic acid and then dried and weighed to ensure complete removal of these components. One sample from each series was used as a reference and treated using the standard processing. All samples subsequently underwent thermal debinding and sintering in a vacuum furnace. Debinding was done at 500°C in argon for 2 hr to remove residual binder (mainly polyethylene). Sintering was done in vacuum (<10-3 Pa) at different temperatures to investigate space holder behaviour and optimise the sintering cycle.

The reference samples processed by desalination in water were found to have collapsed during the second furnace debinding step as can be seen in Fig. 1 (a) to (c) centre, due to inadequate green strength of the spherical titanium particle shape and low injection moulding pressure. In contrast all of the samples processed by the new method were stable and retained their shape.

The KCl space holder was extracted during sintering by sublimation at 750°C followed by final sintering at 1200°C. The final sintered porosities were stated to be: 59.0 ±0.4% for MIM 72, 61.6 ±1.5% for MIM 75, and 55.7 ±0.5% for MIM 80. The authors report that these porosity levels are close to the recommended value required for porous

Vol. 10 No. 1 © 2016 Inovar Communications Ltd

a

b

c

d

Fig. 1 Geometry of MIM samples: (a) – (c) before sintering (left), after sintering with previous desalination (centre), after sintering with space holder (right); (d) left to right – 1st debinding step in hexane, 2nd debinding step (500°C, Ar), space holder sublimation step (750°C) and final sintering at 1200°C. (From paper ‘Increased shape stability and porosity of highly porous injection moulded titanium parts’ Advanced Engineering Materials Vol.17, No.11, 2015, pp 1579-1587) spinal titanium implants. Oxygen content of the MIM Ti porous samples was said to correspond to ASTM Grade 4 and, whilst carbon content is still high, it is much lower than if a PMMA space holder is used.

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Fatigue design of Metal Injection Moulded high strength 100Cr6 steels The fatigue behaviour of widely used high strength steels such as 100Cr6 (SAE 52100) produced under conventional manufacturing conditions is well known, with fracture occurring beyond 107 cycles in the very high cycle fatigue regime (VHCF). In such high strength steels, which are used where strength, hardness and wear resistance are of greatest concern, fatigue cracks are initiated at material defects such as non-metallic inclusions or surface grinding marks. However, very little is known about the fatigue

potential of metal injection moulded high strength steels. With MIM being a Powder Metallurgy related manufacturing process it is thought that PM process related defects such as pores or similar imperfections would be the initiator for fatigue cracks in MIM components.

A research project was therefore carried out by Hendrik Lindel and colleagues at the Robert Bosch GmbH Corporate Sector Research and Engineering Laboratories, Stuttgart, Germany, the Steinbeis Transferzentrum BWF, Esslingen,

Cr

C

Fe

Si

Mn

S

Mo

Al

O

Batch 1

1.48

1.1

Rest

0.32

0.37

0.01

-

0.002

0.198

Batch 2

1.74

0.99

Rest

0.82

0.44

0.007

0.009

0.008

0.003

Table 1 Chemical composition of 100Cr6 MIM (From paper:’ A Fatigue Design Concept for Metal Injection Molded Components of 100Cr6’ by H. Lindel, et al. in Materialwissenschaft und Werkstofftechnik (Vol. 46 Issue 2, 2015) Density in g/cm3

Rm in MPa

E in GPa

Α in %

HV10

HV0.1 edge

HV0.1 chore

Batch 1

7.40

-*

-*

-*

618

709

711

Batch 2

7.67

2386

202

<0.5

725

771

772

* not measured for batch 1

Table 2 Mechanical properties of 100Cr6 MIM in martensitic condition (From paper: ‘A Fatigue Design Concept for Metal Injection Molded Components of 100Cr6’ by H. Lindel, et al. in Materialwissenschaft und Werkstofftechnik (Vol 46 Issue 2, 2015)

(a)

(b)

mold 2

mold 1 burr

round specimen

mold 1

burr

mold 2 burr

flat specimen

3D

Fig. 1 (a) Mould and notched, round specimens with burr in the notch root due to mould parting (b) MIM specimen with burr outside the notches (From paper: ‘A Fatigue Design Concept for Metal Injection Molded Components of 100Cr6’

by H. Lindel, et al. in Materialwissenschaft und Werkstofftechnik (Vol 46 Issue 2, 2015)

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Germany and the Institute of Materials Science and Engineering at University of Kaiserslautern, Germany. The aim was to ascertain the role of pores or similar defects and how to evaluate their influence on fatigue strength of 100Cr6 steels made by MIM tested at N = 106 cycles. The results of the project were published in Materialwissenschaft und Werkstofftechnik (Vol. 46 Issue 2, 2015).

The researchers used two 100Cr6 compositions (Table 1).

Batch 1 was sintered to 95.2% relative density and Batch 2 was sintered to 98.7% relative density using a different sintering furnace which combined a first sintering step with a second sintering under gas pressure. The feedstock for Batch 2 was found to contain a small number of Al and Ti inclusions with a mean size of about 28 μm and a mean number of 0.1 inclusions per mm2. These were thought to have been accidentally added to the feedstock during the mixing process and are seen as representative contamination in the MIM process. Such inclusions are said to be typical of the type of difficulties which can be encountered when producing MIM components.

Prior to hardening, the sintered specimens were tempered to form spherical carbides and to reduce the grain size. The specimens were then heat treated to the martensitic condition (austenitising at 860°C, cooling in nitrogen-gas, deep freezing to -85°C, tempering at 240°C for 90 min). The retained austenite is below 2%. The mechanical properties, mainly for Batch 2, are shown in Table 2.

Fatigue testing Metal injection moulded components usually contain unavoidable burrs at the mould parting due to tool tolerances.

In order to avoid burrs a non-conventional MIM specific specimen shape was designed to perform fatigue experiments on notched and unmachined

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MIM specimens. This allowed the researchers to assess the behaviour of the ‘as-MIM’ material with notches as well as highly stressed surface regions. The MIM-specific shape was designed with the burrs outside the notches (Fig. 1b). The notches were not situated opposite to each other in order to facilitate a good mould filling during injection moulding.

Fatigue testing was done under axial loading with a constant amplitude, a sinusoidal load and a load ratio of R = 0.1 performed on a resonance pulsator with a maximum load of 50 kN. The termination criterion for the fatigue tests was either fracture of the specimens or the survival of 107 cycles. The specimens surviving 107 cycles were named ‘run-out specimens’.

Contrary to expectations that the pores within the MIM test pieces would be the main fatigue crack initiator, the researchers reported

that fatigue cracks were mostly initiated at existing surface flaws of the MIM part. They stated that the detected surface flaws had the following characteristics: • Pores open to the component surface, • Locally melted surface areas, • Surface roughness, • Interconnected pores, • Inclusions.

The experimental S-N data generated showed that, for Batch 1, failure in the finite-life regime already occurred before the specimens reached 105 cycles with early fracture at surface flaws.

The S-N data for the specimens sintered under pressure to 98.7% relative density (Batch 2) showed considerably higher fatigue strength. Here non-metallic inclusions found at the microsections partly initiated the fatigue cracks. Surface roughness also initiated fatigue cracks and it was

found that larger flaws led to earlier fracture than smaller ones. In comparison to Batch 1 the sizes of the crack initiating flaws of Batch 2 are smaller. This underlines the assumption that the fatigue strength at N = 107 cycles of 100Cr6 MIM in the present condition is linked to the crack initiating flaws by fracture mechanics as is the case for conventional high-strength steels.

The authors concluded that the fatigue behaviour of the notched MIM specimens in the pressure sintered condition can be proven with high accuracy by the use of Murakami’s material model. The proposed fatigue design concept developed by the authors therefore allows the evaluation of the fatigue potential of a MIM component made from a high-strength steel at an early stage of the product conception and the estimation of material or process changes on the resulting fatigue strength of complex MIM-components.

C

M

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CM

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CMY

K

Vol. 10 No. 1 © 2016 Inovar Communications Ltd

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Industry News

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Fe3P addition improves magnetic properties of Metal Injection Moulded iron soft magnets Metal Injection Moulding and die pressing/sintering are already used to produce soft magnetic iron parts for a range of applications, but compared with pure wrought iron their magnetic properties are degraded due to their lower sintered densities. Better magnetic properties can be attained by increasing sintered density in conventional PM parts by the addition of phosphorus (P) to iron powder and using high temperature sintering in the presence of a liquid phase. However, very little work has been reported on the addition of P to iron powders for MIM soft magnet applications.

Jidong Ma and co-researchers at the University of Science & Technology Beijing, Xiamen University of Technology, China, and the University of Science & Technology Bannu, Pakistan, recently reported on their work to study the effect of adding Fe3P on the magnetic

properties and microstructure of MIM Fe-P soft magnets in the Journal of Magnetics and Magnetic Materials (Vol.397, 2016, pp240-246). They used carbonyl iron powder having particle size 3-5 µm mixed with Fe3P where the P content was 17.98%. Seven types of Fe-x%P formulations were produced each having an incremental increase of 0.2% in the P content up to a maximum 1.2%. A wax-based binder was used, comprising 60 wt.% paraffin, 15 wt.% high density polyethylene, 10 wt.% polypropylene, 10 wt.% polystyrene and 5wt.% stearic acid, and the powder loading in the MIM feedstock was 58 vol.%.

The solvent and thermally debound samples were subsequently sintered in hydrogen in the temperature range 11001450°C for up to 10 hr. It was found that sintering time of the MIM Fe-P

parts has a significant effect on the density and magnetic properties in the time range of 0.5-2 h. During this time frame, the relative density for a Fe-0.8 wt% P MIM alloy reached 99% with optimum magnetic properties. B6000 and maximum permeability of the sintered Fe-0.8%P samples were found to increase sharply on sintering at 1200°C at which temperature all the P is dissolved in the matrix through liquid sintering, while the coercive force decreases sharply with prolonging sintering time. Also prolonging the sintering time to 10 hrs did not result in increased density and only minor changes were found in magnetic properties. The effect of sintering time on the density and magnetic properties of Fe-0.8% at different sintering temperatures (1200°C and 1420°C) are shown in Fig. 1.

The effect of sintering temperature on magnetic induction (B6000) and maximum permeability µm of sintered MIM samples containing the varying levels of P in the iron powder are shown in Fig. 2 and Fig. 3.

Fig. 1 Effect of sintering time on the density and magnetic properties of Fe-0.85P at 1200°C (left) and 1420°C (right).

From paper: ‘Effect of Fe3P addition on magnetic properties and microstructure of injection molded iron’ by J Ma et al, Journal of Magnetism and Magnetic Materials Vol 397, 2016, 240-246.)

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Fig. 2 Effect of sintering temperature on (B6000 ) of MIM samples containing different amounts of P in Fe. ‘Effect of Fe3P addition on magnetic properties and microstructure of injection molded iron’ by J Ma et al, Journal of Magnetism and Magnetic Materials Vol 397, 2016, 240-246.)

The mean grain size in the sintered microstructure of F-0.8wt% P was found to about 59 µm when sintered at 1200°C for 2hr. However, increasing sintering temperature pim international 2015-12.pdf

Fig. 3 Effect of sintering temperature on maximum permeability of MIM samples containing different amounts of P in Fe. ‘Effect of Fe3P addition on magnetic properties and microstructure of injection molded iron’ by J Ma et al, Journal of Magnetism and Magnetic Materials Vol 397, 2016, 240-246.)

to 1420°C led to a coarsening of the grains to 350 µm. For the Fe-0.8 wt% alloy the optimum density of 7.84 g/cm3 (relative density 99%) was obtained in the MIM parts sintered at 1

1420°C which resulted in magnetic induction (B6000) 1.77T and maximum permeability 17,100, whilst coercive force was 21 A/m.

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CMY

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Company visit: Indo-MIM

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Indo-MIM: A giant in Metal Injection Moulding expands to build on strong international growth It is just under twenty years since Indo-US MIM Tec Pvt. Ltd., better known by its abbreviated name Indo-MIM, was established in Bangalore, India. Within this short period of time the company has evolved into one of the world’s largest MIM producers. Dr Georg Schlieper visited Indo-MIM for PIM International to discover the secret behind this remarkable expansion and the company’s plans for maintaining this rapid growth in the future.

Indo-MIM was established in 1997 in Bangalore, Karnataka, Southern India. The company’s first plant was established on the Hoskote Industrial Estate on the outskirts of the city and this site continues to this day as the headquarters of Indo-MIM. A second plant, located in Doddaballapur, is a thirty minute drive from Hoskote. Bangalore, officially known as Bengaluru since 2014, has a population of eight million people and is commonly referred to as the Silicon Valley of India.

Many leading global IT companies have operations here, however the existence of a metalworking company in this environment is rather unusual.

Despite many early challenges the company prospered and grew to become one of the world’s largest MIM operations.

The sheer size of Indo-MIM is impressive. Hoskote and Doddaballapur together employ 2,500 people. Efficient tool shops equipped with the latest machine tools produce the tooling for the thirty or more new parts that are

Vol. 10 No. 1 © 2016 Inovar Communications Ltd

developed each month, as well as the repair and replacement of existing tools. Around 100 injection moulding machines are in service and numerous sintering furnaces, both batch and continuous, are installed. A huge variety of secondary operations is also performed at the

two sites, including superfinishing.

The facilities operate day and night in three shifts, seven days a week, fifty weeks a year, generating annual sales of more than US$100 million.

Indo-MIM’s breathtaking rise is based on the coincidence of several factors. To start with, the company

Fig. 1 Indo-MIM employees with Krishna Chivukula Sr., centre left, and Krishna Chivukula Jr, centre right, in an injection moulding hall at Indo-MIM

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Fig. 2 Indo-MIM’s CEO Krishna Chivukula Jr.

Fig. 3 A selection of metal injection moulded parts manufactured by Indo-MIM, showing the size range of parts processed

Fig. 4 Further examples of MIM parts manufactured for the international market by Indo-MIM

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was certainly established at the right time and in the right place. The time was right because MIM technology was booming in the late 1990s, reflecting its growing reputation as a viable manufacturing technology.

A joint venture with Precision Castparts Corp – Advanced Forming Technologies (PCC-AFT) gave the young company a sound technology base and access to the crucial US market.

Krishna Chivukula Sr., the first President of Indo-MIM, took over complete ownership from PCC-AFT in 2001. He encouraged his core team to bring the technology and sales figures forward and gave them freedom to implement their own ideas. Most of this core team is still in office, although Krishna Chivukula Sr. has long since handed leadership over to his son Krishna Jr., a smart, sociable businessman with a US education who is known by everybody as KJ (Fig. 2).

Indo-MIM is a truly global company. Being originally a joint venture with a US business, Indo-MIM had strong links with the North American MIM market from the start. Soon after the Chivukla family took control of the company, a sales office was opened in Princeton, New Jersey. Over the years further sales offices staffed with company employees have been opened in Stuttgart, Taiwan and Shanghai.

Indo-MIM recently announced that a US manufacturing operation will be established in San Antonio, Texas, later this year. This move is put down to the growth of the US market, which Indo-MIM believes justifies a new domestic operation. When the new plant opens, US customers will have two independent Indo-MIM supply sources, a domestic supplier and a supplier from overseas. Engineering and toolmaking will, however, remain in India. Various different locations for the new plant were examined over an eighteen month period before San Antonio was selected. It is anticipated that the the factory will employ 300 people within five years.

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Indo-MIM’s business strategy Besides the strong technological foundation and the necessary financial resources for investments, Indo-MIM’s business strategy is a major factor behind its soaring success. Indo-MIM has adopted a policy of being a total solution provider to its customers. This is accomplished by an Innovation and Value unit. “We liaise closely with the customer and help their engineers learn how to design for MIM,” KJ told PIM International. “The customer’s problems are analysed and, in close cooperation with them, the best MIM design solutions are found.”

From the final drawings a 3D model is generated, then prototypes are manufactured and tested before the tooling for mass production is made. A fast reaction to customer enquiries and short timescales for the manufacturing of prototypes and tooling are considered to be of prime importance for a strong position in the MIM market.

The corporate culture of Indo-MIM is built on mutual trust among the management team and the entire workforce. All employees give the impression of being highly motivated and dedicated to the prosperity of the company. This is also expressed by the fact that the members of the management team have served the company for many years, most of them since it was founded.

The Sales and Marketing department is not involved with repeat orders, but only handles new customers and new enquiries. The team follows up with new projects, observes the market and educates potential new customers about the reasons for converting products to MIM. When a market segment has been analysed and viable MIM parts have been identified, Indo-MIM’s Sales & Marketing agents actively approach potential new customers.

They visit these companies, look at the parts they are using and make suggestions for conversion to MIM. Often the design engineers in these companies openly discuss applica-

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Fig. 5 Batch sintering furnaces at Indo-MIM’s Hoskote plant

Fig. 6 Large solvent debinding furnaces. All feedstocks at Indo-MIM are designed for solvent debinding

tions where they have problems, perhaps with the strength of a component, with dimensional tolerances, or with manufacturing costs.

Once this stage has been reached, the basis has been laid for a mutually beneficial business relationship.

Engineering support is provided through a generously equipped R&D laboratory that includes chemical analysis, metallographic and tensile testing equipment. Powder chemistry matters, injection moulding problems, the redesign of binder compositions and materials development are all handled by the R&D department.

Whenever there is a problem with a new part or any question related to

materials science, the R&D department is contacted to provide support in finding a solution. Mould flow analysis and the prevention of flaws in the green state is of particular importance and multiple micro focus X-ray units are available to analyse green compacts for defects.

Education and training Another backbone of Indo-MIM’s business strategy is education and training of the engineering workforce.

The education system in India is generally good, but there is little special training in relation to Powder

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Fig. 7 Continuous sintering furnaces in operation at Indo-MIM’s Doddaballapur plant

Fig. 8 A continuous sintering furnace at Indo-MIM’s Doddaballapur plant

Metallurgy. Indo-MIM has therefore developed professional training programmes for young engineers.

“The first three years in the company are fairly structured for young engineers,” KJ explained. “In the first year they rotate through all manufacturing departments. They work in the tool room, on the moulding machines, the debinding ovens and the sintering furnaces, just like ordinary workers, and learn every step of the technology in detail. They also go through classroom training programmes and learn the basics of metallurgy and statistical process control. In the second and third years, most of them

50

can already take over supervising functions in the manufacturing departments. In parallel they continue classroom training externally.” At the end of the training period they have gained enough experience for their further careers in the company. Some engineers even go back to university after the training period to earn a higher degree of education.

A particular focus in training programmes is on Six Sigma methodology. The trainers take their students through the entire process, from the basic project scoping through to good data collection techniques and the use of inductive statistics to process

Powder Injection Moulding International

March 2016

optimisation techniques such as the Taguchi design of experiments. The highest level of Six Sigma training, the black belt, is held by the leaders of Six Sigma projects. Lower ranks in the quality team go to the green or yellow belt level. Indo-MIM’s management team is convinced that the implementation of Six Sigma in all sectors is what distinguishes the company from the majority of its competitors and is the basis for the rapid growth of their business. It is also the reason why Indo-MIM has been able to maintain high product quality during a period of rapid expansion and diversification.

Six Sigma was introduced by KJ around five years ago and the management team actively supports the strategy, recognising that it has changed the entire company’s culture. Six Sigma enables the characterisation of the stability of each process by a Cpk value. With this, it is possible to compare the most diverse processes with respect to their effect on product quality. Hillson Raj, General Manager Operations, commented, “We are a technologyoriented company. The reliability and efficiency of our process technology is of primary interest to the management team and the output of high quality products is merely a consequence of reliable and stable processes.”

Today, systematic continuous improvement procedures are in place throughout all departments.

Engineers are guided through each step of their range of tasks by checklists that they have to follow, helping to avoid serious mistakes.

When mistakes occur in spite of the defined procedures, the reasons are immediately analysed and improved procedures are implemented. Every quarter there are operational reviews in all departments in which the continuous improvement processes are analysed and the costs of each department evaluated. Although continuous improvement brings only small steps forward at a time, the success becomes apparent when one looks at it over a longer period of time.

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Production at Indo-MIM The Production Planning and Control (PPC) department at IndoMIM receives repeat orders from customers and organises the entire production process, from feedstock preparation through injection moulding, debinding, sintering and secondary operations to product shipment. Each member of the PPC staff is responsible for approximately ten customers, keeping track of their orders and representing their interests internally.

All Indo-MIM feedstocks are designed for solvent debinding and feedstock preparation is done in-house. This puts Indo-MIM in a position to be able to tailor feedstock properties according to the moulding requirements. Parts with thin walls and long flow paths, for example, require a lower feedstock viscosity than more compact products. There is even an option to modify the alloy composition in order to obtain a wider temperature range for sintering, or to achieve better material properties.

Of course, the alloy composition must still be within the specifications.

Feedstock preparation starts with mixing the powder and binder constituents in a cold mixer. The blend is then heated in a kneader until a homogeneous mass has formed. When cool, the block of feedstock is removed from the kneader and cut to pieces that can be fed into a granulator. The final feedstock is in the form of granules that are suitable for the injection moulding machine.

Various sizes of mixers and kneaders, from laboratory to production scale, are available for different batch sizes.

Injection moulding machines stand in long rows in the moulding departments. The Doddaballapur plant handles the high volume orders, mainly from the automotive industry, and the Hoskote plant produces all the low to medium volume parts, as well as parts manufactured from special materials.

After moulding, the green compacts are treated in solvent debinding units and subsequently sintered. The Hoskote plant operates

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Fig. 9 The visual inspection of MIM parts at the Doddaballapur plant. Quality management and process control are at the heart of Indo-MIMâ&#x20AC;&#x2122;s operations

Fig. 10 Part of the visual inspection area for medical parts at the Hoskote plant

a wide variety of batch type furnaces of different sizes for vacuum and atmosphere sintering, whilst the Doddaballapur plant has continuous furnaces with a high sintering capacity.

Secondary operations follow after sintering as and when required.

These operations can include sizing, fine machining or surface treatments.

The surface treatment shop at Doddaballapur offers electropolishing and many types of electroplated coatings. The high emphasis that is laid on quality control is apparent in the inspection and testing workshops (Figs 9 & 10). Thanks to low labour

costs there is little motivation to install costly process automation and only occasionally can one see automatic testers such as the optical inspection devices used for turbocharger vanes.

Marketing strategies by market segments For each market segment Indo-MIM has appointed a Product Engineer, a Manufacturing Engineer and a Quality Engineer. Each market has special requirements in terms of product design, material choice, dimensional

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tolerances, heat treatment, surface treatment and so on, so Indo-MIM believes that it is more efficient to have specialists in each segment.

Indo-MIM produces parts from fractions of a gram to approximately 250 g. The relatively high raw material costs are still the main limiting factor for the size of MIM components. For parts below 30 g the powder price can usually be tolerated, but above that the competitiveness of MIM against competing processes decreases, particularly for high performance materials and in market segments which are already under a high price pressure such as automotive applications. KJ commented, “Much work was required to leverage our manpower to exploit what could be done with MIM materials that would be impossible or unaffordable using conventional forming technology.”

Recent R&D efforts have been directed at process modelling and process flow design. The intention behind this task was to strive for zero defect manufacturing. Producing millions of parts without any defects requires a complete understanding of the processes and process variations have to be kept so small that each final product is within the specified tolerances.

Fig. 11 Machining operations at Indo-MIM

Firearms Parts for firearms and defence products, primarily for the North American market, have been a strong pillar of Indo-MIM’s business since the beginning and continue to be an important sector of the product portfolio. The new factory in San Antonio will further strengthen this market segment.

Fig. 12 Machining operations at Indo-MIM

Fig. 13 Complex MIM tooling in the in-house toolshop (Photo Georg Schlieper)

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Automotive The automotive industry was a relatively early adopter of MIM technology. Although there is still much work to be done to increase the awareness and penetration of MIM in the automotive market, the most important applications in cars are widely known and include turbocharger parts, powertrain applications, sensors and parts for fuel injection systems. Indo-MIM has worked

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hard on its quality management systems and implemented quality manuals and good Advanced Product Quality Planning (APQP) practices in order to develop a leading position in the global automotive market.

Consumer electronics Parts for consumer electronics often combine demanding aesthetic requirements with advanced technical specifications. Dedicated engineering teams are in place for aesthetic and functional surface technologies such as polishing and electroplating, however the basic processing steps of injection moulding and sintering are integrated with the high volume manufacturing of automotive products and are subject to the same quality management procedures.

Indo-MIM believes that there is a growing number of MIM parts in the consumer electronics sector.

Hardware and appliances Whilst products for consumer electronics often have relatively short life cycles and require extremely fast action to bring them from the drawing board to high volume production, there are other consumer products with very long life cycles, for example parts for power tools. These parts are often produced for many years without any change in the design or material.

They are the ‘cash cows’ that fill the gap when the demand for other products is weak.

Aerospace The way in which Indo-MIM approached the aerospace industry serves as a good example of its successful and innovative marketing strategy. Indo-MIM first accessed the aerospace market by offering components machined from Inconel 718 alloy. The required quality systems were installed and the confidence of their customers in the reliability and deliverability of supplies was gained. Once customer relations had been established, they introduced MIM technology and began to actively convert parts.

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Fig. 14 Injection moulding in the medical parts facility at Indo-MIM

Fig. 15 Medical product assembly and packaging in a clean room environment

Ceramics Indo-MIM has also acquired expertise in ceramics technology. This began with the ceramic plates and supports that were required as setters for MIM parts. The management decided to manufacture these consumables in-house and installed the necessary machinery and sintering furnaces.

Over time, experience with the processing of ceramic powders increased and it was just a small step to shape components by CIM. IndoMIM states that recently there have been enquiries for CIM parts from the dental industry and it is only a matter of time until the company operates as a CIM manufacturer.

Medical products: the factory in a factory The medical technology market was still widely undiscovered by MIM when Indo-MIM was formed in 1997. In 2010 the company entered the medical sector and since then many surgical instruments and consumables have been converted to MIM. Today most of its customers design for MIM from the very start of a project. As many parts in the medical sector are extremely small, weighing only fractions of a gram, the manufacturing technology required can in many instances be regarded as micro MIM. The medical market is

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A strong track record for award winning MIM parts Indo-MIM has a strong winning record in the Metal Powder Industries Federation’s PM Design Excellence Awards competition and in 2015 the company claimed a record five awards, as featured below.

Fig. 16 Four MIM components used in proportional valves found in hydraulic circuits of off-highway and farm equipment. Manufacured for Danfoss, Denmark, using 17-4 PH stainless steel and 4605 low-alloy steel

Fig. 17 MIM 17-4 PH lock parts made for Rutherford Controls Inc. and used in industrial locks

Fig. 18 A MIM 4605 low-alloy steel top plate made for Multimatic Inmet, Canada

undergoing radical changes thanks to the development of ever more single use devices. Where highly complex small metal parts are required, MIM is usually the best-suited technology, and in some cases the only technology, to manufacture many of these parts. Such developments, however, also pose new challenges on MIM suppliers. Medical products usually have to be sterile and free from dust, therefore clean room production is required.

Initially there were different ideas in the company’s management of how to handle the quality requirements for the medical sector. Outlining how the decision was made, KJ explained, “After internal discussions we came to the conclusion that, even though we produced in India, we wanted to demonstrate that we have a mind-set that is conducive to meet the quality expectations of our US customers. To meet this challenge we had to install new methods for quality assurance.”

The decision was taken to establish a ‘factory within a factory’ for medical products, with separate dedicated engineering teams, production managers, quality engineers and inspectors. Everything from raw materials to the dispatch of finished products is now controlled in a manufacturing line that is separated from the rest of the company. Clean rooms are installed throughout the department and some products are overmoulded with plastics, whilst others are assembled into functional units or a kit and packaged.

Materials In line with its position as a market leading company, Indo-MIM provides a comprehensive range of MIM materials. The only MIM materials that are not available from Indo-MIM are copper and aluminium. The list of MIM materials includes: • Low alloy steels based on carbonyl iron powder (CIP) Fe2Ni, Fe7Ni suitable for case hardening

Fig. 19 A MIM 4605 low-alloy steel bolt used in a Keystone Sporting Arms, LLC rifle

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Fig. 20 MIM 17-4 PH stainless steel connectors made for Amphenol Air LB, France

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• Low alloy steels based on carbonyl iron powder (CIP) Fe2Ni, Fe7Ni or prealloyed

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powders with an elevated carbon content (typically 0.3 – 0.6% C) for quench-and-temper heat treatment • Stainless steels 316L, 304, 440C, 420, 17-4PH • Common tool steel M2 and unique tool steel S7 (shock resisting) • Soft magnetic materials Fe3Si, Fe49Co2V • Nickel base alloys Inconel 718 and Nimonic 90 for high temperature aerospace applications • Co-Cr-Mo alloy for dental technology • Tungsten heavy alloys W3Ni0.75Fe, W3.5Ni • Titanium CP-Ti Grade 2 and Ti-6Al-4V Most of these alloys and their properties are well-known in the MIM community, with the exception being the tool steel S7 which is a proprietary development by Indo-MIM. This Fe-SiCr-Mo-C alloy combines exceptionally high tensile strength of min 1850 MPa and a high impact strength when heat treated to 55-60 HRC. The majority of applications can be found in defence products, where the durability of parts that are subject to high mechanical shock has been remarkably improved.

An austenitic stainless steel called XEV alloy has been developed on the basis of a Russian publication of 1960 which is mainly used for automotive applications at elevated temperatures. It has high contents of manganese, chromium and nickel.

Indo-MIM has two MIM titanium grades in production at the moment, CP-Ti Grade 2 (ASTM F2885) and Ti-6Al-4V (ASTM F2989). KJ told PIM International, “Several years ago, Indo-MIM made a conscious decision to develop multiple grades of titanium with the intention of developing the MIM market for this material. While we did not see any immediate revenue stream, intuitively we believed the market potential for MIM titanium was under-developed due to overemphasis on powder costs by MIM fabricators, which is only one cost factor in the decision to use MIM. It

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Fig. 21 Construction underway at the Doddaballapur plant to expand the MIM facilities (Photo Georg Schlieper) did not take long before the first few programmes in titanium were won. In many potential applications the high powder price is definitely an impediment to the conversion to MIM, but programmes are out there if you look for them. You need to find the sweet spot between material properties, part complexity and operation elimination – compared to the conventional forming technology – to score with titanium, but it is 100% possible to do.”

Work is undertaken at Indo-MIM on material properties and the development of different grades of MIM-Ti and the company has had several programs under development for the past two years which are scheduled to enter production in 2016.

“We expect more business in this material to come in the future. We are also continuing our R&D efforts to improve material properties to further increase the scope of programmes that can be done in Ti,” added KJ. Indo-MIM has experienced metallurgists for materials development. With its engineering resources and a broad portfolio of MIM materials Indo-MIM is able to develop highly customised solutions for each individual application. The materials list that is published on the Indo-MIM website includes only the most common alloys. Many more alloys have been developed in the past and can be ‘taken from the drawer’ if appropriate.

Outlook Indo-MIM has clearly demonstrated how far a company can get with a dedicated management, a welltrained workforce and hard work.

However, the Indo-MIM story is not finished. Whilst Hoskote has no space for further growth, Doddaballapur has been under permanent expansion over the last five years and currently more construction work is in progress (Fig. 21). Indo-MIM’s management team is determined to continue its marketing strategy and lead MIM technology to new horizons.

Contact Krishna Chivukula Jr. Indo-US MIM Tec Pvt. Ltd. #45[P], KIADB Industrial Area Hoskote Bengaluru 562114 India Tel: +91 80 2204 8800 Email: Krishna.jr@indo-mim.com

Author Dr. Georg Schlieper Alleestr. 101 42853 Remscheid Germany Tel: +49 2195 6889274 www.gammatec.com email: info@gammatec.com

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Additive Manufacturing with Powder Metallurgy June 5–7, 2016 • Boston, MA

Focusing on metal additive manufacturing with powder metallurgy (PM), this conference will feature worldwide industry experts presenting the latest technology developments in this fast-growing field.

Perspectives from: • metal powder producers • toll providers • end users • equipment manufacturers • R&D from academia and consortia Topics will cover: • materials • applications • technical barriers • process economics • new developments Exhibition: • trade show featuring leading AMPM suppliers

Held in conjunction with:

CONFERENCE CHAIRMEN: David K. Leigh, Stratasys Direct Manufacturing Christopher T. Schade, Hoeganaes Corporation For program and further information contact the conference sponsor: Metal Powder Industries Federation 105 College Road East, Princeton, NJ 08540 or visit AMPM2016.org

PIM particulate composites

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Opportunities in the Powder Injection Moulding of Particulate Composites At the first PIM Symposium in 1990, the Marketing Manager for a leading MIM facility outlined where and how MIM would grow. His analysis was based on the conversion of small investment castings to MIM. Although his predictions took a while, MIM did reach those sales predictions. Now MIM is seeking the next big thing. One opportunity for differentiation comes from mixed powder composites.

The field of particulate composites is poorly organised and poorly recognised by suppliers, yet the products have significant added value since there are few competitive processes for complex shaped composites. Prof Randall German reviews emerging opportunities and introduces promising compositions and processing options and applications.

A sense of the growth in MIM comes from recounting statistics presented at the first Powder Injection Molding Symposium held in 1990 at Rensselaer Polytechnic Institute, Troy, New York State. The Marketing Manager for Advanced Forming Technology projected US MIM would reach $350 million in annual sales, largely through the conversion of investment casting designs, especially stainless steels. This projection arose from the examination of designs where the customer would see lower cost with superior quality. At that time, global PIM sales were $91 million, of which 63% came from the metals segment, dominated by the US MIM industry at $45 million. This means that US MIM was only at about 13% of the projected plateau. Accordingly, attention went into marketing MIM to designers frustrated with investment casting; early successes were in orthodontic brackets, surgical tools, watch components, firearm components and computer hard drive parts.

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Years later, ferrous MIM in the US is approaching the projected $350 million plateau (not correcting for inflation), while global MIM sales (largely stainless steel) exceed about $1.2 billion. On the other hand,

iron

cordierite

worldwide metal casting is a $37 billion industry. The MIM effort is focused on small, complicated parts and higher temperature materials, mostly ferrous alloys. On the other hand, the casting industry goes

porosity

100 μm

Fig. 1 Cross-sectional micrograph of a sintered iron-cordierite composite with intertwined phases (Courtesy L. Shaw)

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beyond ferrous alloys to include a diverse range of metals such as aluminium, titanium, nickel-alloys, copper-alloys, magnesium, zinc and lead. Several of these metals are not widely embraced by MIM, simply due to high costs.

It is appropriate to consider where the next wave of growth might arise.

The easy projects are past, so further growth will require something beyond design conversions. New materials are widely discussed, such as titanium, aluminium and superalloys. These have baseline cost structures set by casting technologies where MIM struggles due to powder cost. Thus, significant growth requires something more, such as a combination of new materials and new properties. One such opportunity is in particulate composites, many of which cannot be processed by casting yet are naturally aligned with injection moulding and sintering.

oxide compound (2MgO-2Al2O35SiO2) that is hard, non-conductive, non-magnetic and stiff, with low thermal expansion coefficient. The two phases are essentially insoluble in one another, so the composite is magnetic, conductive, low in thermal expansion, yet can be brazed to silicon. This combination of properties is desirable for use as an electronic diode substrate, enabling automated assembly.

Novel property combinations are key to success with particulate composites. In any composite, there are four options: 1. Properties are dominated by one

phase, 2. Properties are intermediate

between that of the two phases, 3. Properties are advanced over

that attainable with either phase alone, 4. Properties are degraded below

that of both phases.

Background to particulate composites

Using hardness, Table 1 compiles examples for each of the four situations. Compositions are given in percent, so WC-8Co implies 92 wt.% tungsten carbide. In that first case of WC-8Co, the composite hardness is nearly the same as that of the harder tungsten carbide phase. In the second case of W-30Ag, the composite hardness is intermediate between that of the two constituent phases.

In this system, hardness is almost a straight line function of the volume percent tungsten. In the third case, corresponding to alumina (Al2O3) with 20% silicon nitride (Si3N4), the composite hardness is higher than either constituent. In the last case,

A composite is a mixture of two or more phases, where each phase is distinguishable based on differences in atomic structure or composition.

An example is illustrated in Fig. 1, a magnified image from a sintered iron-cordierite composite. This cross-sectional microstructure image contrasts phases using differences in reflectivity. The two phases form interlaced three-dimensional networks, with a little residual porosity. In terms of properties, the iron is soft, conductive, magnetic and ductile, while cordierite is an

Composition wt.%

Hard phase

Soft phase

Composite

Dominated by one phase

WC-8Co

WC1850

Co 180

1800

Intermediate between phases

W-30Ag

W 343

Ag 25

280

Advanced over both phases

Al2O3-20Si3N4

Al2O3 1800

Si3N4 1800

2400

Degraded below both phases

Al2O3-10ZrO2

Al2O3 1800

ZrO2 1300

700

Property level

Table 1 Hardness (HV) for particulate composites (composition in wt.%)

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Fig. 2 Microstructure of a sintered Ni-Fe-P composite created from electrolytic coated carbonyl iron powder (Courtesy G. Cui) corresponding to alumina-zirconia, the composite hardness is inferior to either constituent. This happens in systems optimised for one property while a separate property is sacrificed. In the case of the aluminazirconia composite, the facture toughness is optimised with a sacrifice of hardness. There are applications where inferior properties are desired.

Practice ammunition is an example.

The idea is to replace lead with a bullet similar in mass and aerodynamics. Practice bullets desirably shatter on striking the target to avoid ricochets. A copper-tin composite is designed to shatter on target impact, where the tin is intentionally used to form a brittle intermetallic phase to cause disintegration on striking a target.

Particulate composites synthesise new property combinations. Many notable combinations are encountered, such as the following: • High hardness and toughness: diamond – cemented carbide, • High wear resistance and electrical conductivity: tungsten – copper, • Soft magnetic response in a non-conductive structure: iron – cellulose, • High thermal conductivity and low thermal expansion: aluminium nitride – copper,

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Fig. 3 Tungsten heavy alloy composite microstructure where the dark grains are tungsten and the matrix is an alloy of nickel-iron-tungsten

• High toughness and high density tungsten – nickel + iron, • High stiffness and low density aluminium – silicon carbide.

Unique microstructures Synergistic property combinations, outside the range possible in traditional materials, are important attributes for particulate composites.

In particulate composites, there is much property manipulation possible via changes to the microstructure.

Early experiments using conductive and nonconductive phases demonstrated over a trillion-fold change in electrical conductivity with a minor change in composition. Depending on the starting particle sizes, composition, and consolidation cycle, the microstructure might have one phase dispersed in the other, or both phases connected. The change occurs over relatively small composition shift. In other words, large property changes might be possible with small changes in particle characteristics, composition or processing. Best wear properties in tool steels are associated with dispersed carbides, while best thermal properties in coppertungsten composites are associated with interconnected phases.

An example dispersed phase structure is shown in Fig. 2, the

microstructure of a sintered magnetic composite formed using carbonyl iron powder coated with nickel phosphate.

The composition is Ni-43Fe-4P. After sintering in vacuum at 1025°C for 60 min, the composite has a density of 7.55 g/cm3 and magnetic properties equivalent to MIM Fe-50Ni, but the hardness is over 350 HV. The compressive strength is 1100 MPa with 19% strain to fracture.

As an example of continuous phases, Fig. 3 shows the microstructure of a W-5Ni-2Fe alloy sintered to produce large connected tungsten grains in a continuous alloy phase.

The phases are intertwined in three dimensions. While tungsten is brittle at room temperature, the composite exhibits 30% fracture elongation.

This is a case of high density and high toughness. The composite has a density of 17.7 g/cm3, tensile strength of 930 MPa, with a hardness of 280 HV. The tough alloy phase between the tungsten grains (nominally 53% Ni, 23% Fe, 24% W) offsets the brittleness expected with such a high tungsten content. The composite is a favourite in radiation containment, inertial devices, self-winding watches, golf clubs, gyroscope components, fishing weights, ammunition and eccentric vibrators. Many of these are large applications, reaching production levels of hundreds of million parts per year.

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Fig. 4 The idea of a percolated microstructure is mapped using the example of a mixture of conductive and non-conductive phases. The composite is conductive above the line defined by the composition and size ratio of the two phases. This plot assumes full density.

Importance of percolation The idea of connected versus dispersed structures is treated by percolation concepts. To illustrate, assume a structure consisting of randomly mixed conductive and non-conductive phases. If the conductor is connected in three dimensions, the structure is conductive. Start with a structure entirely consisting of insulator phase.

Randomly substitute conductors phase for the insulator phases,

and nominally at about 20 vol.% conductor the structure becomes conductive. This assumes the grain size is the same for both phases.

That transition from non-conductor to conductor also depends on the grain size ratio, as plotted in Fig. 4.

The logarithm of the size ratio, non-conductor to conductor phase, is on the horizontal axis and the vol.% of conductor phase is on the vertical axis. For 100% dense structures, the experimental transition is shown, giving the switch to conductive

composite at 20 vol.% conductor for equal grain sizes. From about 20 to 80 vol.%, the composite consists of interconnected and intertwined phases. This concept applies to many other properties and helps explain dramatic shifts in ductility, magnetic response, fracture toughness and strength with small changes in composition. Coated powders are one means to alter the behaviour, a significant advance in recent years.

Unlike normal composition specifications, relying on weight percent, percolation concepts are based on volume percent. The transform from weight percent to volume percent relies on the theoretical density of each phase.

For example, WC-10Co implies 10 wt.% cobalt, corresponding to 16.3 vol.% cobalt. Static properties, such as hardness, density and elastic modulus, are often linear functions of the volume fraction, but not weight fraction, of each phase.

One means to include higher concentrations of a phase without inducing percolation is via coated powders. Typically, up to 50 vol.% or more is possible if each core particle is coated with the second phase. Once consolidated, the structure is an idealised dispersion such as evident in Fig. 5. A benefit from such a microstructure arises with wear. A hard particle, such as silicon carbide, diamond or alumina,

5 μm

15 μm

Fig. 5 A dispersed microstructure of alumina with cemented carbide (WC-10Co) as the matrix phase, formed using coated particles (Courtesy J. Keane)

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Fig. 6 An example fracture path in a composite formed from alumina dispersed in WC-10Co (Courtesy J. Keane)

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a)

b)

50 μm

5 μm

Fig. 7 This novel Al-14Cu-1Mg-4SiC composite powder is formed using rotating electrode techniques, a) large particle, and b) the silicon carbide dispersion (Courtesy R. Yamanoglu) is captured in a tough matrix with no contacts between the hard grains. Thus, fracture must pass through the tough phase while wear attributes are dominated by the hard phase. The result is excellent wear resistance in a fracture resistant material. Fig. 6 is a micrograph illustrating desirable crack propagation through the matrix for a sintered composite of alumina dispersed in cemented carbide (WC-10Co). If toughness is the parameter of concern, then the brittle phase should be disconnected. On the other hand, if thermal expansion is of concern, then the low thermal expansion phase should be connected. It is this adjustability in properties via microstructure that allows significant performance manipulation.

Composite powders for injection moulding are new, but potentially provide a significant means to adjust properties. A few of the novel powders are shown in Figs. 7 to 9. The first is an Al-14Cu-1Mg-4SiC particle formed by the rotating electrode methods. The low magnification view in Fig. 7a shows the spherical shape and the high magnification view in Fig. 7b resolves the approximately 1 µm SiC clusters dispersed between the dendrites and grains. The powder shown in Fig. 8 is a ferrous two phase alloy powder generated by gas atomisation. The third powder, shown in Fig. 9, is cubic boron nitride before and after coating with tungsten carbide.

20 μm

100 μm Fig. 8 A two phase stainless steel powder fabricated by gas atomisation (Courtesy A. Bothate) The first frame shows the raw powder, the second frame shows the coated powder and the third frame is focused on the coating in cross section. Other coating options rely on electroless plating for copper or nickel coatings and binder-assisted agglomeration of small particles dusted on larger particles using mechanical fusion. Several coated composite particles are available commercially, such as Cu on W, Ni on SiC, ZrO2 on Fe, Cu on Si3N4, Co on graphite, Ni on TiC, Cu on Mo and WC-10Co on diamond.

20 μm

20 μm

Fig. 9 Three micrographs illustrating coating on cubic boron nitride; the first frame shows the powder, the second frame shows the powder after coating and the third frame is a cross-section to illustrate the coating (Courtesy J. Keane)

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Some example systems

Fig. 10 A picture of cemented carbide wear composites formed using Powder Injection Moulding

Sintering and infiltration options The idea of mixing powders to form a composite microstructure was combined with injection moulding in the 1980s. Early successes were W-Cu, Al-SiC and WC-Co. The W-Cu was targeted at electronic heat spreaders. Mixed powders were formed into feedstock using traditional mixing. The feedstock was injection moulded and sintered.

In contrast, the Al-SiC relied on injection moulded silicon carbide to give a preform that was sintered and infiltrated with molten aluminium.

The WC-Co composites relied on

existing attritor milled powders and sintering cycles, simply increasing the binder phase to a point that enabled injection moulding. Fundamentally, the two important routes were sintering and infiltration.

Related developments gave molybdenum-copper, invar-silver, aluminium-aluminium nitride, copper-graphite, iron-neodymiumboron and titanium-titanium carbide composites. Densification was the critical step, since injection moulding was simply a technique for producing complex shapes. Properties are derived from the constituents and optimised by manipulation of the microstructure.

Fig. 11 A drill tip formed from cemented carbide by injection moulding (Courtesy J. Thomas)

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The most important particulate composite is tungsten carbide (WC) mixed with a metallic matrix phase, usually cobalt. That system contributes commercial products valued at more than $15 billion per year worldwide. Depending on geometry, some of the products are fabricated by injection moulding. The high stiffness, high hardness and excellent wear resistance combine with good fracture toughness and high strength for a wide range of applications.

Common uses for injection moulded carbides are in metal cutting, oil well drilling, abrasive nozzles, wear components, twist drills and jewellery, such as watch cases, wedding rings and watch bands. Fig. 10 is a picture of injection moulded carbide wear components, illustrating shape complexity. That same idea is evident in machining tools, such as the drill tip and cutter shown in Figs. 11 and 12. Net-shaping is important since coining and machining are not options for correcting dimensions.

The fabrication of cemented carbides by PIM was introduced in the 1980s in the LECO Process. It relied on paraffin wax as the binder, low moulding pressures and inexpensive tooling. That technology propagated into several PIM operations where lower moulding pressures helped alleviate tool wear in moulding hard phases, such as in zirconia, alumina, silicon nitride and silicon carbide.

Other hard composites formed by

Fig. 12 A rotary wood cutter formed by injection moulding (Courtesy Y. S. Kwon)

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Fig. 13 A prototype design for a copper-graphite heat spreader for cooling power semiconductors in a hybrid automobile control system (Courtesy L. K. Tan) injection moulding include titanium carbide, titanium boride, boron carbide, diamond and alumina as the hard phase, with titanium, iron, stainless steel or cobalt as the matrix phase.

Another particulate composite formed by PIM is Al-SiC. Early demonstrations targeted automotive applications, such as connecting rods.

Quarter-scale units were fabricated

by General Motors and tested for fatigue life. Meanwhile, similar compositions were penetrating into sporting equipment and thermal management applications, as well as power electronics, lighting and heat pipes. In parallel, the W-Cu composites were taken up for computer heat spreaders and shape charge liners.

A rash of competitive MIM thermal management solutions followed, such as molybdenum-copper, silver-invar and copper-tungsten carbide. An early application was in military radar. The large opportunity was, however, in home computers, cellular and microwave base stations and internet servers. The home computer opportunity for MIM was estimated at $200 million per year and reportedly is even larger today. But the need for lightweight compositions dulled interest in W-Cu. Extruded aluminium induced thermal fatigue failures, but

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its low price won the competition.

Today, high reliability electronic systems rely on aluminium nitride, diamond and silicon carbide mixed with copper or aluminium. Newer applications are in hybrid vehicles where heat dissipation is required around the power semiconductors, leading to injection moulded designs such as pictured in Fig. 13. Options used in Japan rely on AlN and SiC ceramic phases. One demonstration used carbon nanotubes mixed with copper to deliver high thermal conductivity. The competitive solution, used by some hybrid vehicles is to equip the automobile with a radiator just for the power semiconductor, allowing use of pure copper with an internal cooling channel (also made by MIM). However, long-term reliability is a concern.

Some early MIM tungsten composites were based on W-Ni-Fe or W-Ni-Cu compositions formed using elemental powders.

Applications include golf club weights, bowling ball weights, cell telephone vibrators, frangible munition, birdshot, gyroscope and watch weights, radiation barriers and fishing weights. Fig. 14 shows a collection of injection moulded fishing weights.

Normally, tungsten is brittle at room temperature, but when alloyed with

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Fig. 14 Tungsten composite fishing weights of various sizes and designs fabricated using metal powder injection moulding (Courtesy J. Sery) Ni, Cu, and Fe there is surprising ductility in the composites. Depending on composition, elastic modulus is from 320 to 380 GPa and density ranges from 15 to 19 g/cm3. Since the density is considerably higher than lead, the tungsten composites provide excellent containment to radioactive materials emitting high energy X-rays and gamma rays without toxicity issues. Fig. 15 is an injection moulded syringe shield used to protect

Fig. 15 A tungsten composite syringe radiation shield fabricated using metal injection moulding

medical personnel from radiation.

Considerable property adjustment is possible in tungsten composites through alloying. Inertial applications emphasise the high density, so mechanical properties are not a concern. On the other hand, military applications are focused on high strain rate mechanical properties, usually in W-Ni-Fe-Co compositions.

The discovery of iron-neodymiumboron permanent magnets led

Fig. 16 This cross section micrograph shows the iron-neodymium-boron composite after sintering with desirable oxide films between the grains

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to injection moulding in the early 1990s. In 2015, the market in these permanent magnets is about $10 billion, mostly based on simple shapes, but some complex shapes are injection moulded. Two injection moulding variants are in production.

One variant mixes the powder with a polymer, such as polyphenylene sulfide, and moulds the feedstock into a bonded magnet. The solids loading reaches about 65 vol.%.

The polymer glues the structure together to avoid sintering. The binder is selected to withstand engine compartment temperatures for automotive applications. The second injection moulding approach relies on the Fe14Nd2B compound with about 5 wt.% Nd, Dy, Pr, or Tb. By selected proper atmosphere conditions, that excess rare earth is oxidised to form films at the grain bonds. A sintered microstructure is shown in Fig. 16 where rare earth oxide has desirably formed on the grain boundaries to disrupt electrical conductivity.

New options are arising in particulate composites that provide significant property improvements.

Nanoscale composites deliver extraordinary strength and hardness.

A historical difficulty is loss of the nanoscale grain size during sintering.

New formulations are avoiding this difficulty, allowing traditional sintering cycles without grain growth.

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This is achieved by using seeded microstructures where a 1 to 2 µm core particle is coated with nanoscale second phase. The core particle hinders coarsening of the nanoscale shell during consolidation, retaining a small grain size in the final structure.

In one implementation, 2 µm diamond particles are coated with nanoscale WC-10Co and sintered to full density at 1300°C for 1 h. The product delivers six-fold longer life as a machine tool versus pure carbide.

Future developments We are on the cusp of several new PIM composite products. The current evolution in injection moulded particulate composites includes the following compositions and applications: • Tungsten-nickel-iron and tungsten-nickel-copper for military projectiles, fishing weights, self-winding watch weights, eccentric vibrators and

Major phase

Minor phase

Aluminium

Alumina

Bronze, brass

Aluminium nitride

Cobalt, cobalt alloys

Boron nitride

Copper

Diamond

Iron and steel

Molybdenum

Molybdenum

Silicon carbide

Nickel, nickel alloys

Titanium carbide

Silver

Tungsten

Stainless steel

Tungsten carbide

Titanium, titanium alloy

Zirconia

Table 2 Some of the common phases used in particulate composites

sporting equipment weights,

wear components, high temperature bearings and hot working tools,

• Tungsten carbide-cobalt for metal cutting tools, end mills, wear resistant components, drilling tips, nozzles, jewellery and bearings,

• Tool steel-copper for valve seats, lock components and pump components,

• Tool steel-titanium carbide for wear resistant tooling, cutters,

• Tungsten carbide-diamondcopper for stone cutting tools, oil

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H.C. Starck offers a wide variety of special gas and water atomized high-alloyed metal powders, such as Fe-, Ni- and Co-based alloys, as well as customized solutions.

Ampersint@hcstarck.com www.hcstarck.com

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PIM particulate composites

Fig. 17 An example of a composite used in forming a composite. In this case, one phase is steel with dispersed carbides and it is used with another copper alloy phase infiltrated into the sintered structure (Courtesy W. Li)

drilling tips and wear resistant components, • Titanium-titanium carbide for medical affixation, corrosion resistant wear components, • Alumina-zirconia for artificial hips and replacement human body parts, • Titanium-hydroxyapatite, usually in a porous form for biomedical implants and tissue affixation, • Iron-hydroxyapatite for bioabsorbable tendon anchors, • Copper-graphite for high thermal conductivity applications in automotive hybrid vehicles.

In teaching courses in engineering design, PIM and particulate composites, students generate ideas on novel designs, materials and fabrication routes. Some recent projects identified ideas such as titaniumaluminium for marine applications, stainless steel-titanium carbide for wear components, copper-graphene for electrical systems, diamondcobalt for cutting edges and steeltitanium boride gun components.

Conceptually, the invention phase is relatively easy. The lingering difficulty is in the details, especially the long

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qualification process that impedes development efforts.

Many powders are available for composites. In spite of many options, most composites build from a few ingredients, especially those with extreme properties such as high hardness, strength or conductivity.

Some of the common choices are listed alphabetically in Table 2. Often the major phase is metallic and the minor phase is ceramic, but there are many exceptions. Certain combinations are attractive from both a performance and cost viewpoint to fill gaps in existing material properties.

For example, a durable knife blade is possible using stainless steel with added zirconia. After moulding and sintering the two-phase microstructure has the corrosion resistance of stainless steel and the hardness and sharpness of zirconia.

Other ideas follow along these lines and recent demonstrations include steel-titanium boride, stainless steelchromium boride, copper-chromium and titanium-titanium carbide.

Another idea is to use composite granules to form a composite within a composite. Fig. 17 is a microstructure consisting of tool steel, a composite of steel and carbides and an infiltrated copper alloy. Such ideas of building composites using a composite as one phase were first demonstrated using Al-SiC, where sintered Al-SiC granules were infiltrated with aluminium.

For WC-Co, spray dry WC-Co agglomerates are sintered and then formed with injection moulding grade stainless steel and final pores are infiltrated with bronze. When sintered, this composite delivers extremely high wear resistance.

Indeed, just a few volume percent of hard phase significantly improves wear resistance.

An important development is tissue scaffolds for implants.

Titanium is formed to 40% density to match human bone in elastic modulus and strength. The porosity is generated using salt in the feedstock to form large residual pores. After moulding, the salt is dissolved and the part sintered. Finally, the

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implant is treated with hydroxyapatite (calcium phosphate) to induce bone growth to serve as an anchor for implants such as artificial teeth.

Such developments can lead to some exciting new applications for PIM beyond the conversion of investment cast stainless steels.

Author Randall M. German Professor of Mechanical Engineering San Diego State University San Diego California, USA Email: randgerman@gmail.com

Resources This alphabetical listing of articles provide a glimpse of the developments in injection moulding of particulate composites, but it is by no means comprehensive.

D. Auzene, T. Jacquemin, J. L. Duval, C. Egles, J. M. Popot, “Biological characterization of materials produced by powder injection moulding for dental applications,” Powder Metallurgy, 2015, vol. 58, pp.

16-19.

D. Belnap, A. Griffo, “Homogeneous and Structured PCD WC-Co Materials for Drilling,” Diamond and Related Materials, 2004, vol 13, pp. 1914-1922.

A. Bose, “Alloying and Powder Injection Molding of Tungsten Heavy Alloys: A Review,” Tungsten and Refractory Metals, A. Bose and R. Dowding (eds.), Metal Powder Industries Federation, Princeton, NJ, 1995, pp. 21-33.

S. Y. Chang, J H. Lin, S. J. Lin. T. Z. Kattamis, “Processing Copper and Silver Matrix Composites by Electroless Plating and Hot Pressing,” Metallurgical and Materials Transactions, 1999, vol. 30A, pp. 1119-1136.

P. Divya, A. Singhal, D. K. Pattanayak, T. R. R. Mohan, “Injection Moulding of Titanium Metal and AW-PMMA Composite Powders,” Trends in Biomaterials and Artificial Organs, 2005, vol. 18, pp. 247-253.

© 2016 Inovar Communications Ltd

Vol. 10 No. 1

PIM particulate composites

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P. Ettmayer, “Hardmetals and Cermets,” Annual Reviews in Materials Science, 1989, vol. 19, pp.

145-164.

F. Findik, H. Uzun, “Silver-based refractory contact materials,” Materials and Design, 2003, vol. 24, pp. 489-492.

R. M. German, K. F. Hens, J. L. Johnson, “Powder Metallurgy Processing of Thermal Management Materials for Microelectronic Applications,” International Journal of Powder Metallurgy, 1994, vol. 30, pp.

205-215.

J. L. Johnson, “Opportunities for PM Processing of Metal Matrix Composites,” International Journal of Powder Metallurgy, 2011, vol. 47, no 2, pp. 19-28.

V. Josef, L. K. Tan, “Thermal Performance of MIM Thermal Management Device,” Powder Injection Moulding International, 2007, vol. 1, pp. 59-62.

K. Kageyama, Y. Harada, H. Kato, “Preparation and Mechanical Properties of Alumina-Zirconia Composites with Agglomerated Structures Using Presintered Powder,” Materials Transactions, 2003, vol. 44, pp.

1571-1576.

J. Konstanty, Powder Metallurgy Diamond Tools, Elsevier, Amsterdam, Netherlands, 2005.

M. S. Kumar, P. Chandrasekar, P. Chandramohan, M. Mohanraj, “Characterisation of Titanium Titanium Boride Composites Process

by Powder Metallurgy Techniques,” Materials Characterization, 2012, vol.

73, pp. 43-51.

X. Liu, Y. Li, F. Lou, M. Li, “Al/SiC Composites with High Reinforcement Content Prepared by PIM/Pressure Infiltration,” Powder Injection Moulding International, 2007, vol. 1, no. 4, pp. 53-55.

Z. Y. Liu, D. Kent, G. B. Schaffer, “Powder Injection Molding of an Al-AlN Metal Matrix Composite,” Materials Science and Engineering, 2009, vol. A513, pp. 352-356.

Z. Y. Liu, D. Kent, G. B. Schaffer, “Powder Injection Molding of Al-(Steel and Magnet) Hybrid Components,” Metallurgical and Materials Transac-

Vol. 10 No. 1 © 2016 Inovar Communications Ltd

tions, 2009, vol. 40, pp. 2785-2788.

N. H. Loh, S. B. Tor, K. A. Khor, “Production of Metal Matrix Composite Part by Powder Injection Molding,” Journal of Materials Processing Technology, 2001, vol.

108, pp. 398-407.

S. Luyckx, “The Hardness of Tungsten Carbide - Cobalt Hardmetal,” Handbook of Ceramic Hard Materials, vol. 2, R. Riedel (ed.), Wiley-VCH, Weinheim, Germany, 2000, pp.

946-964.

B. M. Ma, J. W. Herchenroeder, B. Smith, M. Suda, D. N. Brown, Z. Chen, “Recent development in bonded NdFeB magnets,” Journal of Magnetism and Magnetic Materials, 2002, vol. 239, pp. 418-423.

A. Maleki, M. Meratian, B. Niroumand, M. Gupta, “Synthesis of In Situ Aluminum Matrix Composite Using a New Activated Powder Injection Molding Method,” Metallurgical and Materials Transactions, 2008, vol.

39A, pp. 3034-3039.

H. Moriguchi, K. Tsuduki, A. Ikegaya, Y. Miyomoto, Y. Morisada, “Sintering Behavior and Properties of Diamond / Cemented Carbides,” International Journal of Refractory Metals and Hard Materials, 2007, vol. 25, pp.

237-243.

W. Nakayama, “Thermal Management of Electronic Equipment: A Review of Technology and Research Topics,” Applied Mechanics Reviews, 1986, vol.

39, pp. 1847-1868.

J. Ormerod, S. Constantinides, “Bonded permanent magnets: Current status and future opportunities,” Journal of Applied Physics, 1997, vol. 81, pp. 4816-4820.

G. Popescu, M. Zsigmond, P. Moldovan, “Processing of a Composite Material Like AlSi/SiCp Through Powder Metallurgy,” Journal of Advanced Materials, 2003, vol. 35, pp. 16-19.

B. H. Rabin, R. M. German, “Microstructure Effects on Tensile Properties of Tungsten-Nickel-Iron Composites,” Metallurgical Transactions, 1988, vol. 19A, pp. 1523-1532.

properties of mechanically alloyed and solid-state sintered tungsten heavy alloys,” Materials Science and Engineering, 2000, vol. 291A, pp.

91-96.

T. Schubert, A. Brendel, K. Schmid, T. Koeck, L. Ciupinski, W. Zielinski, T. Weissgarber, B. Kieback, “Interfacial design of Cu / SiC composites prepared by powder metallurgy for heat sink applications,” Composites Part A, 2007, vol. 38, pp. 2398-2403.

P. Slade (ed.), Electrical Contacts: Principles and Applications, second edition, CRC Press, Boca Raton, FL, 2013.

J. E. Spowart, D. B. Miracle, “The influence of reinforcement morphology on the tensile response of 6061/SiC/25p discontinuouslyreinforced aluminum,” Materials Science and Engineering, 2003, vol.

A357, pp. 111-123.

E. S. Thian, N. H. Loh, K. A. Khor, S. B. Tor, “Ti-6Al-4V/HA Composite Feedstock for Injection Molding,” Materials Letters, 2002, vol. 56, pp.

522-532.

S. Tiller, “Soft Magnetic Composites in the development of a new compact transversal flux electric motor,” Powder Metallurgy Review, 2013, no.

3, pp. 75-77.

J. Wang, R. Stevens, “Review Zirconia-toughened alumina (ZTA) ceramics,” Journal of Materials Science, 1987, vol. 24, pp. 3421-3440.

X. Wang, H. Yang, M. Chen, J. Zou, S. Liang, “Fabrication and arc erosion behaviors of Ag-TiB2 contact materials,” Powder Technology, 2014, vol.

256, pp. 20-24.

N. Williams, “MIMITALIA Transforms the Production of Diamond Beads Using MIM Processing,” Powder Injection Moulding International, 2010, vol. 4, no. 3, pp. 38-40.

C. Zweben, “Advances in High Performance Thermal Management Materials: A Review,” Journal of Advanced Materials, 2007, vol. 39, pp.

3-10.

H. J. Ryu, S. H. Hong, W. H. Baek, “Microstructure and mechanical

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etallurgy

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Euro PM2015: Innovative materials offer growth opportunities for PIM The Euro PM2015 Congress & Exhibition, Reims, France, October 4-7 2015, proved to be an essential destination for those looking to understand the latest technical and commercial advances in Powder Injection Moulding. In the second part of his review for PIM International, Dr David Whittaker reports on a series of papers that cover the processing of a range of materials that all offer potential for future growth, including Fe-Si for soft magnetic applications, titanium, nickel-based superalloy CM247LC, aluminium and silicon carbide.

Feedstock optimisation for the MIM of Fe-Si soft magnetic materials A paper from Alicia Páez Pavón, Antonia Jiménez-Morales and José Manuel Torralba (Universidad Carlos III de Madrid, Spain) considered feedstock optimisation for MIM of Fe-Si soft magnetic materials [1].

Soft magnetic materials are frequently used in electromagnetic devices in which high magnetic induction, low coercivity and high permeability are required. Among the available soft magnetic materials, iron-silicon based alloys are widely used because of their good combination of magnetic properties, low hysteresis losses and low cost.

Soft magnetic components are usually made from wrought products or by conventional Powder Metallurgy routes. However, alloys with silicon content above 3.5% become hard and brittle, resulting in processing difficulties. Metal Injection

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Moulding enables the production of soft magnetic components with no limitations on silicon content and, moreover, it is possible to produce final components without secondary operations.

The objective of the work presented was to determine the

optimum powder loading of a non-industrialised feedstock for MIM of Fe-Si based soft magnetic alloys, with optimum magnetic and mechanical properties.

In the study, a gas atomised pre-alloyed Fe-3.8%Si powder was used. To determine the critical

Fig. 1 Delegates at EuroPM 2015 in Reims, France (Courtesy EPMA)

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65

70 75 Powder loading (vol.%)

80

| contents page | news | events | advertisers’ index | email | Fig 19

7 Density (g/cm3)

Torque (N·m)

1.2 0.9 0.6 0.3 0

65

70 75 Powder loading (vol.%)

Experimental density

6.6

Theoretical density

6.2 5.8 5.4 5

80

65

70

75 80 Powder loading (vol.%)

85

Fig. 2 Torque value at the end of the mixing process as Fig a 20 Fig. 3 Experimental density of the feedstocks compared function of the powder loading in the feedstocks [1] with the theoretical density [1]

Fig 19

7 loading, feedstocks with powder density different powderExperimental contents were 6.6 produced. In allTheoretical cases, thedensity binder 6.2 consisted of 48 vol.% system polypropylene, 48 vol.% polyethylene 5.8 and 4 vol.% paraffin wax.

Torque values during mixing are 5.4 indicative of feedstock homogenisaDensity (g/cm3)

tion. When torque reaches a constant value, the feedstock can be considered homogeneous. As the powder loading increases, the distance between powder particles of the feedstock decreases. This phenomenon causes a reduction of the fluidity of the mixture, which results in higher

5

Fig 20

65

70

75 80 Powder loading (vol.%)

85

This work

Press-Sinter [2]

MIM[3]

99.6

93.4

99.0

Relative density (%)

Table 1 Relative density of the Fe-3.8Si alloy compared with press-sinter and MIM alloys [1] This work

Fe-4Si P/S [4]

Fe-3Si MIM [3]

Hardness HRB

89

75

80

Ultimate tensile stength (MPa)

603

410

530

Table 2 Mechanical properties of the Fe-3.8Si alloy compared with a Press/ Sinter and a MIM alloy [1]

98.0 97.5

Density (%)

97.0 96.5 96.0 95.5 95.0 94.5 94.0 0.0

0.5

1.0

1.5

2.0

2.5

3.0

%Graphite

Fig. 4 Density of sintered test bars [5]

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3.5

torque values. Final torque value also increases with the powder loading, as shown in Fig. 2. Above 72.5 vol.%, it can be seen that the increase of the final value of the torque is greater than at lower loadings.

Fig. 3 shows the density values of the feedstock compared with the theoretical density obtained using the rule of mixtures. The experimental density values are lower than the theoretical ones. An abrupt change of density for the feedstock corresponding to 75 vol.% of powder loading can also be observed. At this loading, the binder system is not sufficient to cover all the powder particles and this causes the appearance of voids between them.

These results indicate that the critical powder loading in the feedstock corresponds to 72.5 vol.%.

Therefore, 72.5 vol.% of powder loading has been established as the critical powder loading and 69.5 vol.% as the optimum powder loading.

The feedstock containing 69.5 vol.% powder loading was injected and then solvent and thermal debinding were carried out. Finally, brown parts were sintered in hydrogen at 1350°C for 4 hours.

Table 1 shows the relative density of the sintered samples. This value has been compared with values from the literature for a Fe-3Si alloy processed by pressing and sintering and a Fe-3Si alloy processed by MIM. The densification obtained in the reported study is higher than these values from the literature. This higher density results in higher hardness and tensile strength values (Table 2).

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The values obtained in this work have been compared with the Fe-3Si MIM alloy and a Fe-4Si Press/Sinter alloy.

The measured properties are higher than the values from the literature, as expected because of the higher degree of densification achieved and the higher silicon content, in the case of the MIM alloy, but the properties are even higher than the Press/Sinter alloy with a higher silicon content.

Fig. 5 Microstructure of Ti 6-4, 0-45 μm. Carbon addition 0% left, 1% right [5]

New titanium feedstock for high performance MIM Toby Tingskog and Frederic Larouche (AP&C, Canada) and Louis-Philippe Lefebvre (National Research Council, Canada) described the development of a new titanium powder feedstock for high performance MIM [5].

Metal Injection Moulding is being increasingly used for CP Ti, Ti 6-4 and other Ti alloys. MIM works well for titanium, but the cost is high relative to other alloy systems, such as stainless steel and FeNi. Processing requires excellent vacuum furnaces to achieve high density and low oxygen and carbon levels. Material properties can also be compromised by microstructural changes, primarily grain growth during the high temperature sintering cycle.

The as-sintered density of titanium can be increased with finer powder particle size. However, fine titanium powder is not widely available and possesses a higher oxygen content because of the larger surface area.

For these reasons, 0-45 μm powder is generally preferred for MIM parts.

AP&C produces CP Ti and Ti 6-4 in several particle sizes: 0-45, 0-25 and 0-20 μm. The 0-45 grade is easier to manufacture and is available at lower cost and larger quantities than the finer Particle Size Distribution (PSD) grades. AP&C manufactures titanium powder with a proprietary plasma atomisation process. The powder is near-perfectly spherical with very low oxygen levels. AP&C and NRC decided to initiate a study to see if there was a possibility to improve sintering and mechanical properties of titanium MIM.

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Fig. 6 Microstructure of Ti 6-4 0-25 μm with carbon addition 0% left and 1% right [5] Based on previous research, the addition of carbon to the MIM feedstock was evaluated. A graphite addition has the potential to lower processing cost by sintering in a vacuum furnace with a graphite hot zone. The study included CP Ti and Ti 6-4 powder with PSDs of 0-45 and 0-25 μm. Carbon was added to NRC’s proprietary binder in concentrations of 0.5, 1, 2, 3 and 5%. The graphite was added to the binder and components prior to high shear mixing. Tensile and impact test bars were moulded at NRC and

were solvent debound followed by a thermal debind at 800 and 900°C before sintering. Parts were sintered in vacuum at 1250°C for 8 hours.

The tensile bars were tested for density. As can be seen in Fig. 4, the optimum graphite addition for densification was 1% and this generated a sintered density increase of around 2%. The effect of a 1% carbon addition on the microstructure of Ti 6-4 is shown in Figs. 5 and 6.

Carbon precipitates as TiC in the alloy matrix during sintering and the TiC pins grain boundaries and prevents

Yield Strength MPa

UTS MPa

Elongation %

Hardness HRC

Ti 6-4 -25 μm

709

932

12.8

27

As sintered average

Ti 6-4 +1%C -25 μm

761

1055

14.4

31

As sintered average

Ti 6-4 ASTM

680

780

10 min

As sintered

ASTM F2885

830

900

10 min

HIP

ASTM F2885

Alloy

Table 3 Average mechanical properties compared with ASTM F2885 values [5]

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Ni

Co

Cr

W

Al

Ta

Hf

Ti

Mo

B

C

Si

S

Zr

Bal.

9.25

8.20

9.52

5.50

3.16

1.34

0.80

0.53

0.013

0.06

< 0.01

0.0017

0.015

Table 4 Chemical composition of the CM247LC powder in wt% [6]

Fig. 7 DSC curve of the CM247LC powder used for feedstock preparation [6]

DSC ThermoCalc

γ’-Solvus

Solidus

Liquidus

not detected

≈ 1330°C

1385°C

1218°C

1306°C

1371°C

Table 5 γ’-solvus, solidus and liquidus temperatures from the DSC measurement and ThermoCalc simulations [6] grain growth in the MIM part.

The average measured mechanical properties are given in Table 3. For comparison, the values according to ASTM F2885, Standard Specification for Metal Injection Moulded Titanium-6Aluminum4Vanadium Components for Surgical Implant Applications are listed.

It can be seen that the TiC has a positive effect on YS, UTS and Elongation. Hardness and wear resistance is improved with 5% TiC precipitates in a Ti alloy matrix.

The authors concluded that MIM titanium feedstock with a 1% carbon addition has the potential to improve many parts and enable increased use of titanium in small, complex components. Application areas may include consumer electronics, automotive, industrial and medical instruments. AP&C and NRC have

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applied for a patent on the carbon addition technology for MIM.

MIM of nickel-based superalloy CM247LC Andreas Meyer and Robert Singer (Joint Institute of Advanced Materials and Processes, ZMP, Germany), Enrico Daenicke, Katharina Horke and Maria Moor (Rolls-Royce Deutschland Ltd. & Co KG, Germany) and Sieglinde Muller and Ingolf Langer (Schunk Sintermetalltechnik, Germany) presented a paper on MIM of the nickel-based superalloy CM247LC [6].

Nickel-based superalloys offer excellent creep resistance, fatigue strength and corrosion and oxidation resistance and are, therefore, widely used for aerospace, power generation

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and automotive high-temperature applications. Nickel-based CM247LC is a superalloy derived from the MAR-M-247 composition, specifically designed for directionally solidified (DS) blade and vane applications.

It is a γ’ precipitation hardenable superalloy with high aluminium and high refractory element (Ta, W, Mo) contents, which demonstrates exceptional creep strength along with high oxidation resistance. The low carbon content improves the carbide microstructure, carbide stability and ductility.

The production of complex parts made from nickel-based superalloys requires extensive machining and is very costly and time-consuming due to the typically poor workability.

Therefore, the near-net-shape process of MIM is a promising alternative. However, to-date, no work has been published on Metal Injection Moulding of CM247LC superalloy.

CM247LC poses a serious challenge for MIM processing. Because of its high aluminium content, the strength potential is very high, but the sintering capability is severely restricted.

Over the last decade, MIM capability of several nickel-based superalloys, such as Inconel 625, Inconel 713, Inconel 718, Nimonic 90, Udimet 720 and MAR-M-247, has been investigated. These studies have shown promising results, namely good mechanical properties at high temperatures as well as good high temperature oxidation behaviour having been reported. In the work presented in this paper, the feasibility of manufacturing parts from CM247LC by MIM was investigated, with the particular aim of determining an optimum sintering temperature range. A pre-alloyed, gas atomised powder, with the composition quoted in Table 4, was used.

In order to find a suitable sintering temperature range, thermal characterisation of the powder

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was carried out using Differential Scanning Calorimetry (DSC) measurements. Also, ThermoCalc simulations of phase transition temperatures were performed using the Thermotech Ni-based Superalloys Database 8.0 (TTNi8), and dilatometry measurements were carried out on cylindrical brown parts.

The results of the DSC measurements on the CM247LC powder are shown in Fig. 7. Peaks for γ’ dissolution and carbide dissolution could not be observed.

The endothermic peak is assigned to melting, indicating a solidus temperature in the range from 1320°C to 1340°C and a liquidus temperature of 1385°C. In Table 5, the transition temperatures from the DSC measurements are compared to those from the ThermoCalc calculations for the nominal chemical composition as given in Table 4.

Solidus and liquidus temperatures are both slightly higher for the DSC results, although they are basically in good agreement.

As reported in the literature, the sintering temperature of metal injection moulded nickel-based superalloys needs to be close to or even slightly above the solidus temperature of the particular alloy. For this reason, dilatometry measurements were performed in a temperature range of 1270°C to 1325°C to investigate the sintering behaviour of MIM brown parts and to find suitable sintering temperatures.

On the basis of the length change of MIM brown parts in dilatometry, sintering begins at about 1200°C and takes place very rapidly in the first 30 minutes at maximum temperature.

After this initial strong sintering, only limited further length change can be observed. The shrinkage after a 3 hour dwell time increases with increasing temperature, as shown in Fig. 8. After 3 hours at 1270°C, the shrinkage is only 3.4%, while the shrinkage for temperatures above 1315°C is higher than 12%. This seems to be the maximum attainable shrinkage as there is no further decrease in length for temperatures above 1320°C.

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Fig. 8 Shrinkage of MIM brown parts after 3h hours dwell time at maximum temperature [6]

Porosity from image analysis (%) Density from Archimedes method (g/cm³)

1295°C

1305°C

1315°C

1325°C

1.21 ± 0.13

0.80 ± 0.12

1.69 ± 0.37

1.64 ± 0.32

8.526

8.526

8.517

8.510

Table 6 Porosity and density of the samples sintered at 1295°C, 1305°C, 1315°C and 1325°C [6]

Fig. 9 Optical images showing the grain size at the edge of the samples sintered at a) 1295°C, b) 1305°C, c) 1315°C and d) 1325°C [6] On the basis of the results of the DSC measurements, ThermoCalc simulations and dilatometry measurements, temperatures of 1295°C, 1305°C, 1315°C and 1325°C were selected as sintering temperatures

for further experiments. Sintering at these temperatures leads to a residual porosity of about 1 % (Table 6).

The microstructure and, in particular, the grains at the edge of

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Fig. 10 SEM image of the microstructure of a tensile bar sintered at 1315°C, showing the γ-γ’-microstructure [6] Carbon (ppm)

Nitrogen (ppm)

Oxygen (ppm)

CM247LC powder

651

≈0

294

1295°C

1020

37

584

1305°C

1089

45

536

1315°C

1246

43

499

1325°C

1063

33

572

Table 7 Carbon, nitrogen and oxygen contents of the CM247LC powder and the samples sintered at 1295°C, 1305°C, 1315°C and 1325°C [6]

Fig. 11 Room temperature tensile properties of MIM CM247LC sintered at different temperatures. The values were normalised to the values from the literature for strength and ductility of cast and HIPed CM247LC [6]

the samples sintered at different temperatures can be seen in Fig. 9.

The grains of the samples sintered at 1325°C are much coarser than the respective grains of the samples sintered at lower temperatures.

Thus, sintering or heat treating

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at very high temperatures seems to induce grain growth. The γ-γ’-microstructure is depicted in Fig. 10. The γ’-precipitates have a size of about 0.5 μm to 1 μm and most of them are cubic with rounded corners.

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Manufacturing by MIM always gives rise to a pick-up of impurities, such as carbon, nitrogen and oxygen. These impurities can form brittle carbides, nitrides and oxides, which might be detrimental to mechanical properties. The impurity contents of the CM247LC powder and of the sintered samples are listed in Table 7. The carbon content of the sintered samples is in the range from 1000 ppm to 1100 ppm, which corresponds to a carbon pick-up of about 400 ppm.

There is almost no nitrogen in the powder and the nitrogen pick-up is minimal. The oxygen content of the sintered samples is in the range from 500 ppm to 600 ppm, which corresponds to an oxygen pick-up of about 200 ppm to 300 ppm.

These pick-up levels are rated as being acceptable, but should ideally be reduced by further optimisation of thermal processes.

The fine grain size of the MIM samples contributes to good mechanical properties at room temperature. The normalised mechanical property results are shown in Fig. 11. These values were normalised with respect to the values from the literature for cast and HIPed CM247LC. Yield strength (YS), ultimate tensile strength (UTS) and elongation for all sintering temperatures are higher than those for the cast and HIPed material. While yield strength and ultimate tensile strength of the MIM material are about 7% to 34% higher, elongation is almost twice as high. The best results, with regard to strength and ductility, could be achieved by sintering at 1305°C. This is in accordance with the lowest porosity (i.e. highest sintered density), measured for this sintering temperature (see Table 6). This may be because of the fine grain size of the MIM samples. A fine grain size naturally improves room temperature mechanical properties, as grain boundaries act as pinning points for dislocations and thus impede dislocation movement (Hall-Petch strengthening).

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However, for high temperature applications, where creep strength is the major issue, concepts for grain growth need to be developed.

Interstitial effects during the sintering of injection moulded Al base alloys Julijana Kuzmanović, Herbert Danninger, Christian Gierl-Mayer and Andreas Nenning (Technische Universität Wien) and Armineh Avakemian (voestalpine Stahl GmbH) reported on interstitial effects during the sintering of injection moulded aluminium-based alloys [7].

The main difficulty in sintering of aluminium alloys is the presence of a thin (5-15 nm) but thermodynamically very stable oxide layer on the powder surface which cannot be removed through conventional reduction technologies. To generate a metal-metal contact, it is necessary to overcome this oxide barrier. Due to the lack of powder deformation during the injection moulding process, the sintering of MIM parts can be compared to gravity sintering.

In aluminium MIM, the sintering process can be promoted in two main ways. The first possibility is an addition of magnesium with high chemical activity (e.g. elemental Mg or an AlMg50 master alloy). Because of its high vapour pressure as well as the high free energy of its oxide (MgO), magnesium can partially reduce the Al2O3 surface, forming a spinel. This leaves the metallic layer below the surface locally uncovered, leading to the formation of sintering contacts between the metal particles. The other component that promotes the sintering process is nitrogen, in the form of a N2 sintering atmosphere.

Especially in combination with magnesium, nitrogen leads to the formation of nitrides, subsequently causing cracks in the Al2O3-oxide layer. The nitriding is an exothermic reaction, which increases the temperature locally and leads to the formation of a liquid phase that promotes sintering.

Without these two effects, it would be impossible to sinter the parts.

Vol. 10 No. 1 © 2016 Inovar Communications Ltd

Fig. 12 Interstitial contents of MIM Al-3%Mg samples, debound in different atmospheres, sintered in N2 [7]

Fig. 13 Correlation of the interstitial element content and sintered density of Al-3%Mg-samples [7] The reported work has shown that, for an Al-3%Mg alloy, aluminium metal injection moulding is possible. The process depends on many parameters, which must be monitored carefully. The control of interstitials is essential: these do not only include oxygen, which forms the sinter-inhibiting oxide layer on powder particles, but also nitrogen, as well as carbon, which is always present in the MIM production chain in the form of organic binder materials. The parameters of thermal debinding, as well as the cooling process after sintering, play a key role in the successful control of the

sintering mechanisms.

In the study, preliminary tests of the sintering behaviour were performed by gravity sintering of pure metallic powders, without any organic binder added. These tests showed the best sintering quality and densification in a pure N2 atmosphere at a sintering temperature in a range where a persistent liquid phase is formed. These successful gravity sintering experiments showed that the oxide by itself is not the reason for lack of densification. The assumption is that poor sintering behaviour is related to the carbon residues that result from incomplete debinding.

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Density [g/cm3]

Hardness HV5

Tensile strength [MPa]

Elongation [%]

O-cont. [%]

C-cont. [%]

N-cont. [%]

2.57

60

180

4.5

0.27

0.07

0.12

Table 8 Mechanical and chemical properties of MIM samples Al-3%Mg. Thermal debinding in O2, sintering in N2-atmosphere [7] 7000

AlN / Al2O3 β-Phase: Al3Mg2

Intensität [counts]

6000 5000 4000 3000 2000 1000 0

5

25

45

65 Position [2θ]

85

105

Fig. 14 GI-XR – Diffractogram of the surface region [7]

10000

Al AlN / Al2O3 β-Phase: Al3Mg2

9000 8000

Intensität [counts]

7000 6000 5000 4000 3000 2000 1000 0 20

30

40

50

60

70

80

90

100

110

120

Position [2θ]

Fig. 15 XR - Diffractogram of the bulk material [7] In order to evaluate this assumption, Al-3%Mg MIM-parts were moulded from a feedstock containing a mixture of Al powder and AlMg50 master alloy with a Catamold binder, catalytically debound and then, before sintering in pure N2 atmosphere, thermally debound in three different atmospheres. The best sintering

76

results were attained by using a pure oxygen debinding atmosphere (Fig. 12), resulting in the lowest contents of the three interstitial elements, especially carbon.

In Fig. 13, a clear correlation between the residual carbon content and the densification of Al-MIM parts can be observed. While the poorly

Powder Injection Moulding International

March 2016

sintered specimens show erratic C, O and N-contents, the specimens sintered to a high density contain low levels of C as well as relatively low contents of N and O. This confirms the significance of the interstitial elements in the successful sintering of Al-MIM parts.

The mechanical strength of Al-MIM parts (Table 8) lies in the expected range for equivalent wrought alloys of the 5xxx-type (e.g. AA 5052). The elongation values, however, are below those of the comparable alloys and this can be expected for sintered Al-parts considering the residual surface oxides.

Metallographic examination of sintered Al-MIM samples showed that, near the surface, a 10-50 μm thick rim region was formed. Etching of this region revealed dark, dendritic precipitates, with a microhardness of 100 ± 10 HV0.05. GI-XRD analysis showed that this region consisted mainly of a mixture of AlN and Al2O3, as well as some magnesium rich ß-Phase (Fig. 14).

The high AlN content on the sample surface and its low amount in the bulk material (Table 8) are an effect of the fast material densification during Al-MIM sintering. While the extent of bulk nitriding remains low, the surface area, remaining in contact with the N2 atmosphere for a longer period of time, is the subject of a significantly higher nitriding effect (compare Figs. 14 and 15). The AlN/Al2O3-rich surface region was observed in all samples and did not have any significant influence on the mechanical properties of the bulk material.

During the development of the sintering process, the samples were cooled down after the sintering at different cooling rates. Depending on the cooling period or the atmosphere (containing oxygen (O2:N2 of 1:59) or pure nitrogen), the specimens exhibited different surface colours.

Samples cooled slowly (5 K/min) in the temperature range between 600 and 400°C in the N2 atmosphere revealed a dark, almost black surface colour; the slower the cooling, the

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O 1s

Mg KLL

N 1s C 1s

counts arb. u.

thicker the discoloured surface and the darker the colour (from brownish, to brown, up to black). Samples cooled down to room temperature more rapidly (10 K/min) did not show any discolouration effects. Cooling in the atmosphere containing oxygen did not lead to any discolouration at any given cooling rate.

Since GI-XRD at lower incident angles did not reveal any additional phases on the surface of the material, it is assumed that the discolouration effect occurs because of differences in the AlN-to- Al2O3 ratio in the upper surface region of the samples. This marginal composition change does not have any effect on the mechanical properties, but is a cosmetic feature that is undesirable in industrial production.

In the next step of the study, an XPS-analysis of the material surface was performed (Fig. 16). Both a black and a metallic sample surface were found to consist mainly of MgO. This was expected since magnesium has a very high oxygen affinity and is therefore concentrated on the material surface where it is primarily oxidised, forming an upper MgOlayer. Additionally to the Mg- and Osignals, Al, N, and C were detected.

Table 9 shows the measured XPSsignal quantities in relation to each other. This comparison between the samples shows a higher N-, as well as C-content, in the black sample. In the case of carbon, the signal is found in the range of a carbonate-bond, indicating residual binder amounts on the sample surface.

In order to determine whether the higher carbon content is the reason for discolouration, the metallic powder alone, without any organic binder, was gravity sintered and cooled down under the same conditions as the Al-MIM samples.

The specimens produced this way exhibited the same surface colour as their MIM equivalents. Since, in such gravity sintering experiments of metallic powders, no carbon is present in the starting material, a discolouration effect due to the carbon content on the surface can be excluded. The discolouration is indeed

Mg 2s Mg 2p Al 2s Al 2p

500

400

300

200

100

0

binding energy [eV]

Fig. 16 XPS-analyses of the black (black trace) and metallic (green trace) sample surfaces [7]

ratio of detected at % black/metallic

Al 2s

C 1s

Mg 2s

N 1s

O 1s

0.792

1.229

1.003

1.749

0.791

Table 9 Results of XPS-analysis of samples with different surface colour [7] caused by incorporation of nitrogen. It was already shown that the discoloration occurs in a temperature range between 600 and 400°C. The elevated N-content on the surface of black samples can be explained by the fact that these samples remain in the critical temperature window for a significantly longer time than the fast cooled, not discoloured sample.

To activate the nitriding process, it is necessary firstly to generate some reactive Al-surface, which, in this case, is achieved by heating the sample to a temperature at which a liquid phase is generated and/or a magnesiothermic reduction can take place (above 600°C). This is why the discolouration effects only occur in the cooling period and not during the sample heating.

In the case of a cooling process in an O2-containing atmosphere, the discolouration does not occur, since the oxidation processes hinder nitriding and therefore alter the oxide-to-nitride ratio on the material surface.

The authors drew the general conclusion that sintering of dense,

metallic Al-MIM parts requires a precise temperature control and, most of all, an exact atmosphere control during the whole sintering process.

Sintering aids for SiC PIM The final contribution to this session was from Richard Chinn (Oregon State University, USA), Ravi Enneti (Global Tungsten and Powder Corporation, USA), T S Sudarshan (Materials Modification Inc., USA) and Sundar Atre (University of Louisville, USA) and addressed sintering aids for SiC PIM [8].

Silicon carbide (SiC) is a versatile ceramic for many high performance applications, such as armour, abrasives, mechanical seals, pump bearings, aerospace optics, mineral processing, electric furnace elements, thin films, microelectronics, nuclear fuel cladding, textiles, metal-matrix composites, solar inverters, molten metal processing and refractories.

SiC is reported to be the most used non-oxide ceramic in the world.

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PIM at Euro PM2015, Part 2

Paper

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Year

Additives

Remarks

1985

Al, B and C

High-temperature strength

Lee and Kim [10]

1994

Al2O3 and Y2O3

Toughness vs. grain size

S.K. Lee et al [11]

1995

B4C, C, Al2O3 and Y2O3

R-curve toughness

1998

AlN and Y2O3

High-temperature strength

1999

Al2O3, Y2O3 and MgO

Volatilization of additives

She and Ueno [14,15]

1999

Al2O3 and Y2O3

Strength and toughness

Rixecker et al [16]

2000

AlN and Y2O3

Strength and toughness

Datta et al [17]

2002

B4C and C

Sintering mechanisms and nano-SiC

2002

C, Al2O3 and Y2O3

Microwave sintering

Sigl [19]

2003

Y3Al5O12 and AlN

Thermal conductivity

Y.I. Lee et al [20]

2003

Al2O3, Y2O3 and CaO

Two-step sintering

Zawrah and Shaw [21]

2004

Al2O3, Y2O3 and CaO

Elastic modulus, hardness and toughness

Can et al

2006

Al2O3 and Y2O3

Elastic modulus

2007

B, C, Al2O3, Y2O3

Corrosion of SiC

2007

Al2O3, Y2O3 and MgO

Strength, hardness and toughness

2007

MgO

SiC particle organic coating

2009

Al3BC3 and Al8B4C7

Elastic modulus, hardness and toughness

Onbattuvelli et al [27]

2012

AlN and Y2O3

Injection molding

Ortiz et al [28]

2012

Al2O3 and Y2O3

Sol gel

Tanaka et al

[9]

Keppeler et al [12] Foster and Thompson

Goldstein et al

[18]

[22]

Andrews et al [23] Gubernat et al [24] Tatli and Thompson S.H. Lee et al

[26]

[25]

[13]

Table 10 Papers cited and the sintering additives examined [8] Of particular significance are the strength and hardness of SiC, even at elevated temperatures; oxidation resistance; abrasion resistance; low neutron absorption; reflectance; wide bandgap and high thermal conductivity. However, fabricating components from SiC is challenging, limiting its use in many potential applications, especially when translating these useful properties into complex shapes. Several shaping techniques such as powder injection molding (PIM), additive manufacturing and microfabrication have begun receiving attention for fabricating SiC components in conjunction with pressureless sintering.

The purpose of the paper presented was to provide an assessment of useful compositions, sintering conditions and sintered properties to expand the design window for SiC components for complex shapes using pressureless sintering.

78

Sintering additives have been useful in mitigating the difficulties involved in fabricating components using SiC. The additives enhance densification of SiC at lower sintering temperatures or times, enabling the use of various fabrication techniques and also improving the properties of SiC. However, use of improper types or amounts of additives can result in deterioration of properties of sintered SiC. This study has addressed a gap in the literature by compiling, summarising and critically evaluating the many sintering additives that have been investigated since the 1980s to sinter densify SiC without pressure assistance. The selection and processing of additives to facilitate the densification of a ceramic is an important aspect of grain boundary engineering. In addition to densification, the effect of additives on sintered properties, such as bending strength, fracture toughness, hardness, thermal

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conductivity and corrosion resistance, were analysed. A list of the papers analysed is given in Table 10.

The experimental data from the studies in Table 10 were organised and analysed under three main classes of additive type; carbide additives, oxide additives and nitride additives. Over 100 data points, showing the variation in achieved sintered densities with temperature for various additives, are included in Fig. 17. A sintering temperature of 1950°C was a reliable reference point for high densification of SiC with all classes of additives.

There were several exceptions to the rule. Oxide additives yielded >95% densities at sintering temperatures as low as 1550°C when MgO was dispersed as an organometallic precursor. However, sintered density of <70% was observed when MgO was admixed as powders even above 1750°C in the same study.

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R.E. Chinn

Figure 1b

110

110

100

100

Relative Density [% ideal]

Relative Density [% ideal]

Figure 1a

90

80 Oxide Nitride

70

Carbide

R.E. Chinn

90

80

70

Oxide Nitride

60

50 1200

Carbide

60

1400

2000

1800

1600

2200

50

0

5

Sintering Temperature [°C] Euro PM2015 – Advanced Materials and Applications 2

10

15

20

25

30

Additive Fraction [mass%]

Oregon State University

Oregon State University

Sintering Aids for SiC PIM

Fig. 17 Map of relative density v/s sintering temperature (left) and additive fraction (right) [8]

Nitride additives generally required at least 1950°C for densification, but yielded consistently >95% densification.

The presence of Ar overpressure was found to be useful in obtaining 99+% density in these systems.

The carbide additives typically resulted in >95% density at higher temperatures (>2000°C) in the presence of B and metal additives.

Reports of sintered densities below 70% were routinely observed when

Objective

Density

Strength [MPa]

Value

Vickers hardness [GPa]

500 MPa strength at 1500°C, 4-MPa m0.5 toughness, 22-GPa hardness, 80-W m-1 K-1 thermal conductivity or high corrosion resistance in SiC were achievable by multiple methods of pressureless sintering. Selected examples of the upper end of property data for pressureless-sintered SiC are shown in Table 11.

Additives

Process

End Note

1.0% or more B4C + 1% C

2050°C, 15 min, vacuum

Datta[17]

6% Al2O3 + 4% Y2O3

2000°C, 1 hr

S.K. Lee[10]

10 vol% (60 mol% AlN + 40 mol% Y2O3)

GPS in 10-MPa N2, 2010°C, 60 min, anneal

Rixecker[16]

631

0.29% Al, 0.1% B, 2.48% C, 0.43% SiO2, 0.035% Fe

2100°C, 1 hr, Ar

Tanaka[9]

640

5% (62.5 mass% Al2O3 : 37.5% Y2O3)

1950°C, 1 hr, Ar

She[15]

10 vol% (3 AlN : 2 Y2O3)

GPS in 0.3-MPa N2, 1980°C, 30 min

Keppeler[12]

10 vol% (60 mol% AlN + 40 mol% Y2O3)

GPS in 10-MPa N2, 1950°C, 60 min

Rixecker[16]

4.1

7.5% Al3BC3

2050°C, 2 hr, Ar

S.H. Lee[26]

8.3

6% Al2O3 + 4% Y2O3

2000°C, 5 hr

S.K. Lee[10]

6.5

10 vol% (60 mol% AlN + 40 mol% Y2O3)

GPS in 10-MPa N2, 1980°C, 60 min

Rixecker[16]

22.0

7.5% Al3BC3

2000°C, 2 hr, Ar

S.H. Lee[26]

26

10% (42 Al2O3 : 44 Y2O3 : 14 MgO)

1950°C, 2 hr, Ar, SiC mould powder

Gubernat[19]

15.1

5% AlN + 5% Y2O3

1950°C, 2 hr, Ar

Onbattuvelli[27]

>99%

564

Fracture toughness [MPa m0.5]

the B amount was below 0.25 wt.%.

Higher temperatures can be detrimental to density, as additives may evaporate with increasing temperature. The weight loss can be accompanied with grain growth, resulting in a reduction in mechanical properties.

Additives of any type exceeding about 10% resulted in minor advantages for the densification of SiC. Sintered density greater than 99% , 600 MPa bending strength,

Table 11 Selected SiC compositions and process conditions and associated properties from Table 10 [8]

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PIM at Euro PM2015, Part 2

Author

Science Letters, 4,315-317 (1985).

Ceramic Society 23,1115-1122 (2003).

Dr David Whittaker 231 Coalway Road Wolverhampton WV3 7NG, UK Tel: 01902 338498 Email: whittakerd4@gmail.com

[10] S.K. Lee, C.H. Kim, Effects Of α-SiC Versus β-SiC Starting Powders on Microstructure and Fracture Toughness of SiC Sintered with Al2O3-Y2O3 Additives, Journal of American Ceramic Society., 77,6, 1655-58 (1994).

[20] Y.-I. Lee, Y.-W. Kim, M. Mitomo, D.-Y. Kim, Fabrication of Dense Nanostructured Silicon Carbide Ceramics Through Two-Step Sintering, Journal of American Ceramic Society, 86, 1803–805 (2003).

References [1] Feedstock Optimization for Metal Injection Moulding (MIM) of Fe-Si Soft Magnetic Materials, A.Páez-Pavón et al, as presented at the Euro PM2015 Congress & Exhibition, Reims, France, 4-7 October 2015.

[2] C. Lall, “Soft magnetism: fundamentals for powder metallurgy and metal injection moulding”.

Princeton: Metal Powder Industries Federation, 1992.

[11] S.K. Lee, D.K. Kim, C.H. Kim, Flaw-Tolerance and R-Curve Behavior of Liquid-Phase-Sintered Silicon Carbides with Different Microstructures, Journal of American Ceramic Society 78,1,65-70 (1995).

[12] M. Keppeler, H.-G. Reichert, J. M. Broadley, G. Thurn, I. Wiedmann, F. Aldinger, High Temperature Mechanical Behaviour of Liquid Phase Sintered Silicon Carbide, Journal of the European Ceramic Society 18,521526 (1998).

[21] M.F. Zawrah, L. Shaw, LiquidPhase Sintering Of SiC In Presence Of CaO, Ceramics International, 30,721-725 (2004).

[22] A. Can, M. Herrmann, D.S. McLachlan, I. Sigalas,J. Adler, Densification Of Liquid Phase Sintered Silicon Carbide, Journal of the European Ceramic Society 26, 1707-1713(2006).

[13] D. Foster, D.P. Thompson, The Use Of MgO As A Densification Aid For α–Sic, Journal of the European Ceramic Society 19,2823-2831 (1999).

[23] A. Andrews, M. Herrmann, M. Sephton, Chr. Machio, A. Michaelis, Electrochemical Corrosion Of Solid And Liquid Phase Sintered Silicon Carbide In Acidic And Alkaline Environments, Journal of the European Ceramic Society 27, 2127-2135(2007).

[14] J.H. She, K. Ueno, Densification Behavior And Mechanical Properties Of Pressureless-Sintered Silicon Carbide Ceramics With Alumina And Yttria Additions, Materials Chemistry and Physics 59,139-142 (1999).

[24] A. Gubernat, L. Stobierski, P. Labaj, Microstructure And Mechanical Properties Of Silicon Carbide Pressureless Sintered With Oxide Additives, Journal of the European Ceramic Society 27,781-789 (2007).

[15] J.H. She, K. Ueno, Effect of Additive Content on Liquid-Phase Sintering on Silicon Carbide Ceramics, Materials Research Bulletin, 34, 10/11,1629–1636, (1999).

[25] Z. Tatli,D.P. Thompson, The Use Of MgO-Coated SiC Powders As Low Temperature Densification Materials, Journal of the European Ceramic Society 27, 1313-1317(2007).

[6] Metal Injection Moulding of NickelBased Superalloy CM247LC, Andreas Meyer et al, as presented at the Euro PM2015 Congress & Exhibition, Reims, France, 4-7 October 2015.

[16] G. Rixecker, K. Biswas, I. Wiedmann, F. Aldinger, LiquidPhase Sintered SiC Ceramics With Oxynitride Additives, Journal of Ceramic Processing Research, 1,1, 12~19 (2000).

[26] S.-H. Lee, H. Tanaka, Y. Kagawa, Spark Plasma Sintering And Pressureless Sintering Of SiC Using Aluminum Borocarbide Additives,” Journal of the European Ceramic Society 29, 2087-2095(2009).

[7] Interstitial Effects during Sintering of Injection Moulded Al Base Alloys, Julijana Kuzmanovic et al, as presented at the Euro PM2015 Congress & Exhibition, Reims, France, 4-7 October 2015.

[17] M.S. Datta, A.K. Bandyopadhyay, B. Chaudhuri, Sintering Of Nano Crystalline A-Silicon Carbide By Doping With Boron Carbide, Bulletin of Material Science.,25, 3,181189(2002).

[27] V.P. Onbattuvelli, R.K. Enneti, S.V. Atre, The Effects Of Nanoparticle Addition On The Densification And Properties Of SiC,” Ceramics International 38, 5393-5399 (2012).

[8] Sintering Aids for SiC PIM, Richard E. Chinn et al, as presented at the Euro PM2015 Congress & Exhibition, Reims, France, 4-7 October 2015.

[18] A. Goldstein, W.D. Kaplan, A. Singurindi, Liquid Assisted Sintering Of SiC Powders By MW (2.45 GHz) Heating, Journal of the European Ceramic Society 22,1891-1896 (2002).

[3] MPIF, “MPIF Standard 35: Soft Magnetic Alloys.” 2007.

[4] G. Jangg, M. Drozda, H. Danninger, H. Wibbeler, W. Schatt, “Sintering behavior, mechanical and magnetic properties of sintered Fe-Si materials”. The International Journal of Powder Metallurgy & Powder Technology, 1984, vol. 20, no 4, pp 287-300 [5] New Titanium Powder Feedstock for High Performance MIM, Toby Tingskog et al, as presented at the Euro PM2015 Congress & Exhibition, Reims, France, 4-7 October 2015.

[9] H. Tanaka, Y. Inomata, K. Hara,H. Hasegawa, Normal Sintering Of Al-Doped β-Sic, Journal of Materials

80

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[19] L.S. Sigl, Thermal Conductivity Of Liquid Phase Sintered Silicon Carbide, Journal of the European

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[28] A.L. Ortiz, O. Borrero-López, M.Z. Quadir, F. Guiberteau, A Route For The Pressureless Liquid-Phase Sintering Of SiC With Low Additive Content For Improved Sliding-Wear Resistance, Journal of the European Ceramic Society 32 965-973(2012).

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POWDERMET 2016 POWDERMET2016 JUNE 5–8

MPIF/APMI

B O S T O N

2016 INTERNATIONAL CONFERENCE ON POWDER METALLURGY & PARTICULATE MATERIALS June 5–8, 2016 Sheraton Boston • Boston, MA TECHNICAL PROGRAM Over 200 worldwide industry experts will present the latest in powder metallurgy and particulate materials.

TRADE EXHIBITION Over 100 companies showcasing leading suppliers of powder metallurgy and particulate materials processing equipment, powders, and products.

SPECIAL CONFERENCE EVENTS Including special guest speakers, awards luncheons, and evening networking events.

Visit POWDERMET2016.org to submit an abstract, to reserve an exhibit booth or for program details.

Held in conjunction with:

June 5–7, 2016

BOSTON

METAL POWDER INDUSTRIES FEDERATION APMI INTERNATIONAL

6

International Conference on Injection Molding of Metals, Ceramics and Carbides MARCH 7–9 • HOTEL IRVINE IRVINE, CA

Make plans to attend the only international metal and powder injection molding event of the year!

MIM2016 CONFERENCE (March 7–9) A two-day event featuring presentations, plant tour and a keynote luncheon • Innovative Processes & Materials • Dimensional Accuracy and Consistency • Advances in Component Uniformity • Part Selection—Best Practices • Leading Process Trends • Tabletop Exhibition & Networking Reception with Representatives from Many of the Leading Companies in the Field ...and Much More!

Optional One-Day Powder Injection Molding Tutorial Precedes Conference (March 7) Taught by Randall M. German, FAPMI world-renowned PIM expert An ideal way to acquire a solid grounding in powder injection molding technology in a short period of time • Introduction to the manufacturing process • Definition of what is a viable PIM or MIM component • Materials selection and expectations • Review of the economic advantages of the process

This conference is sponsored by the Metal Injection Molding Association, a trade association of the Metal Powder Industries Federation

Visit mim2016.org or mimaweb.org for complete program details and registration information

Measuring feedstock viscosity

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High Pressure Capillary Rheometer, a simple way to measure the viscosity of MIM feedstocks?

Process simulation is a widely used tool in the development phase of injection moulded parts. The key variable describing the deformation behaviour of melted polymers is the viscosity and the most common method to calculate the viscosity of plastics is the High Pressure Capillary Rheometer. As Timo Gebauer and Vanessa Schwittay from SIGMA Engineering GmbH explain, several virtual experiments have been performed to understand the limits of this method and establish how it can be used for MIM feedstocks.

SIGMASOFT® Virtual Molding is a well-established tool for the evaluation and optimisation of the Metal Injection Moulding processes. One of the key values describing the rheology of a pseudo plastic fluid is shear viscosity. For any process simulation, the characterisation of a polymer by viscosity using shear rate and temperature is essential to deliver reliable results. What is critical to understand, however, is how these values are measured.

Unfortunately there is no machine available to directly measure viscosity. Its values are always calculated indirectly. A specific deformation of the material at a certain temperature requires a definite force. This force (pressure / momentum) can be measured. Based on several assumptions, corrections and theoretical models, the viscosity at different shear rates is calculated from these measurements.

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There are different techniques available to measure the deformation force. The most common way to obtain the viscosity for polymers at high shear rates is the High Pressure Capillary Rheometer (HCR). While the material is pushed through a capillary with different velocities, the

pressure is measured. Based on the assumption that the Newtonian and the shear thinning viscosity are equal at a specific position in the capillary, the viscosity is calculated. In doing so several corrections (Bagley, Mooney or Weisenberg Rabinowitsch) are applied to take into account certain

Fig. 1 Profiles of velocity and shear rates in the capillary

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Measuring feedstock viscosity

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1 E+06

Fig. 2 Temperature distribution in the capillary for low andviscosity high speed of the isotherm piston original viscosity

Viscosity [Pas] Viscosity [Pas]

1 E+05 1 E+04 E+06

viscosity isotherm original viscosity

1 E+03 E+05 1 E+02 E+04 1 E+01 E+03 1 E+00 E+02 1 E-01

1 E+00

1 E+01

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1 E+04

1 E+05

1 E+00

1 E+01

1 E+02 1 E+03 Shear rate [1/s]

1 E+04

1 E+05

1 E+01 1 E+00 1 E-01

Fig. 3 Original viscosity and calculated viscosity for an isothermal material behaviour

1 E+06

calculated viscosity original viscosity

Viscosity [Pas] Viscosity [Pas]

1 E+05 1 1 E+04 E+06

calculated viscosity original viscosity

1 1 E+03 E+05 1 1 E+02 E+04 1 1 E+01 E+03 1 1 E+00 E+02 1 E-01

1 E+00

1 E+01

1 E+02 1 E+03 Shear rate [1/s]

1 E+04

1 E+05

1 E+01

Fig. 4 Original viscosity and calculated viscosity for a normal material behaviour 1 E+00 1 E-01

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1 E+00

1 E+01

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effects such as elasticity, wall slip or a non-Newtonian velocity profile.

Other effects such as the temperature increase are neglected. The assumption justifying the neglected temperature increase is a simple energy balance. It is low enough to be neglected when heat capacity, pressure and velocity are taken into account. Looking at the known shear field in the capillary (Fig. 1) it becomes obvious that the shear energy is concentrated in certain areas. When the speed of the piston in the HCR increases, this effect becomes even bigger.

To measure the viscosity for shear rates typically occurring during the injection molding process, one has to measure at high speed. Fig. 2 shows the temperature increase for both low and high speed piston operations. At low speed the temperature increase only appears at the end of the capillary and is rather low (ΔT = 4°C).

However, for higher velocities the temperature increase not only becomes noticeable much earlier in the capillary, but also is much higher with a difference of up to 14°C. Thus, it can have a significant influence on these shear rate regions.

Fig. 3 shows a virtual experiment in which a material with a certain viscosity (original viscosity) is used to simulate a High Pressure Capillary Rheometer. The simulated pressure is used to calculate the viscosity as it is done in the real experiment. The second curve (viscosity isotherm) shows the calculated viscosity based on this experiment. The material used for the viscosity generation in the simulation was modified in a way that the temperature could not increase.

The two viscosity curves match pretty well and show that the simulation of the capillary works very accurately and correctly predicts the pressure.

After this proof of concept a second simulation was performed.

In this simulation the material was allowed to change temperature due to shear heating. Again the viscosity was calculated. Fig. 4 shows the original viscosity (green curve) and the calculated viscosity (red curve) for this material. In the lower shear

1 E+05

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rate range the two curves are very consistent. In this range, the shear heating is rather low so the material does not heat up too much. For higher shear rates, the discrepancy between the two curves becomes bigger. At the shear rate of 1000/s, the difference between the two curves is approximately a factor of two.

This simple experiment shows the dramatic impact the temperature increase has on the viscosity measurement. To predict the pressure loss inside a MIM mould, it is necessary to consider this behaviour in the corrections as well.

Another singularity of MIM feedstocks requires a unique characterisation approach. MIM feedstocks are usually a mixture of metal powder and a polymer matrix.

Thus, their rheological behaviour is usually even more complex than for regular polymers because of the characteristic shear field that leads to the rotation of particles inside the feedstock. Due to this rotation the particles leave areas with high shear gradients. As a consequence, separate areas with higher and lower particle concentration emerge. This segregation effect result is shown in Fig. 5. Particle segregation cannot only lead to defects in the final part, but it also has a huge influence on the viscosity measurement.

As viscosity is a function of the powder concentration, the separation leads to huge differences in the local deformation behaviour and, by association, in the local viscosity (Fig. 6). For most feedstocks the binder viscosity is very low compared to that of the mixture. Thus, the material builds up a lubricating film and the feedstock slides through the capillary without big deformations.

The assumption of a regular shear thinning flow, and with it the Weisenberg Rabinowitsch correction, is most likely no longer valid.

This circumstance makes it impossible to calculate the viscosity of the feedstock with just one HCR experiment. One way to find the right viscosity for a MIM feedstock is to measure the feedstock with different particle concentrations.

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Fig. 5 Particle separation due to shear gradients

Fig. 6 Viscosity over concentration leads to different viscosities in the feedstock Once the viscosities dependent on the concentration are known, the correct viscosity of the whole feedstock can be calculated with the help of SIGMASOFT® Virtual Molding.

References

Authors

[2] Berginc, B; Brezocnik, M; Kampus, Z; Sustarsic, B: A Numerical Simulation of Metall Injection Moulding Materials and technology 43 (2009) 1, 43-48

Dipl.-Ing. Timo Gebauer, Executive Manager/CTO and Vanessa Schwittay B.Sc., Marketing Manager & Engineering SIGMA Engineering GmbH Kackertstr. 11 52072 Aachen Germany Tel: +49 241 89495 0 Fax: +49 241 89495 20 Email: v.schwittay@sigmasoft.de www.sigmasoft.de

[1] Chen, X; Tan, K W; Lam, Y C; Chai, J C: The transverse particle migration of highly filled polymer fluid flow in a pipe.

[3] Menges, G.; Haberstroh, W.: Michaeli, W.; Schmachtenberg, E.: Werkstoffkunde der Kunststoffe, München, Wien: Carl Hanser Verlag, 2002

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