Curtin University PRRE1003 Resources, Processes & Materials Engineering Workshop P5: Non-Metals and

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PRRE1003 Resources, Processes & Materials Engineering

Workshop P5: Non-Metals and Manufacturing LEARNING OUTCOMES • •

Understand and iden+fy the structures and behaviours of various non-metals Understand the ini+al concepts of materials manufacturing

Ac0vity 1: Ceramics and Glasses (40 minutes) a) On the sketch below of specific volume vs temperature, the cooling paths of a crystalline solid and an amorphous solid have been drawn. Use your mouse to move the list of labels to the correct posi+ons and fill in the Table below.

Amorphous solid

Crystalline solid Supercooled liquid

Glasstransi+on temperature, Tg

Mel+ng temperature, Tm

Amorphous solid

Crystalline solid

It does not crystallise due to the different volume sizes of the atoms will not reach the form of a solid.

Amorphous reaches a certain temperature where it acts like a solid; allowing it to bear a load.

Crystalline liquid starts to contract when cooling. When the liquid reaches a certain temperature point it crystallises coming s solid. Reducing the volume, shown with the rapid decrease of line 1

Change in specific Volume gradually decreases due to volume lowing of temperature, but will not reach a solid form. The structure remains disordered due to the different par+cles in an amorphous solid, and will not be able to reargue themselves to form a solid, because of this the volume is larger than a crystallised solid

Reducing the volume, shown with the rapid decrease of line 1. This reduce in volume is due to crystalline solid’s par+cles able to arrange themselves in an order. This results in a solid formed.

Structure upon cooling

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Change in viscosity

Higher viscosity is reached when the temperature is lower, but will not reach a solid form, but will get to a temperature where it will act as a solid.

A sudden change in viscosity is shown in the drop of line 1. Due to the par+cles ordering themselves as they are the same size to create a solid form.

b) Using your sketch in part (a) to explain why glass may be drawn into fibres, whereas crystalline alumina may not.

Glass has the properties of high viscosity and change in specific volume at low temperatures. Glass reaches a sweet spot at a range of temperature where it can be stretched without cracking, due to the range of viscosity stretching the glass to form fibres

c) Borosilicate glasses and fused silica exhibit higher resistance to thermal shock, to some of the more day-to-day glasses and ceramics. Why is this so?

Day-to-day glasses and ceramics produce strain when thermal shock happens, due to this the stress on the glass causes. Thermal coefficient of expansion is higher in day to day glasses, this causes more strain, strain in related to stress, if the stress exceeds the fracture strength for the material the material will break. Borosilicate glass and Fused silica has a reduced thermal coefficient of thermal expansion, the stress experience in rapid change of temperature is lower than the fraction strength making it more resistant to thermal shock.

d) Watch the first minute of this video: hXps://www.youtube.com/watch?v=7EgAUhsiRQs For a car windscreen made from tempered glass, explain why the windscreen suffers no significant damage when it undergoes a light impact force, but it will suffer catastrophic failure producing fragments of a par+cular, yet safer geometry, when the windscreen undergoes a more substan,al impact force. (Hint: A comprehensive answer to this ques+on should include reference to the manufacturing process of the tempered glass).

Heat treated or tempered glass, creates no significant damage when it undergoes light impacts forms and failure producing large fragments able to causes greater safety. This is due to the production of the glass causing the glass to have low heat conductivity. Tempered glass uses a thermal tempering process where glass has an extreme temperature change of heating the glass to high temperatures before rapid cooling, this causes the outside to contract, creating an extremely tough outer surface with a tensioned glass core. This causes the glass to have layers of compression, smaller cracks and safer geometry when the windscreen undergoes 2 a more substantial impact force. Propagation of the crack perpendicular the glass.

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Ac0vity 2: Composite Materials (15 minutes) A con+nuous and aligned fibre-reinforced composite material is to be produced consis+ng of 39 vol% glass fibres and 61 vol% of an epoxy matrix. The mechanical characteris+cs of these two materials are as follows: Material

Modulus of elas+city (GPa)

Fracture strength (MPa)

Glass Fibre

76

2512

Epoxy

3.3

59

For this composite material, state the law that applies and use it to calculate the following: i. the longitudinal tensile strength 𝜎𝑐, ii. the longitudinal modulus of elas+city 𝐸𝑐 Law:

EC = EF VF + EM VM 𝜎𝑐= Vf(𝜎f) + VM(𝜎M)

Working: Ec = (76)(0.39) + (3.3)(0.61) = 29.63 + 2.013 = 31.65 GPa

𝜎𝑐 = (2512)(0.39) + (59)(0.61) =979.68 + 35.99 = 1015.67 Mpa

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Ac0vity 3: Forming Processes (20 minutes) Watch the following videos, and use them to match the forming processes of wire drawing and conven,onal extrusion, with respect to the listed parameters below.

A.

Wire Drawing: hXps://youtu.be/Qbk45lL7czQ and hXps://youtu.be/VVewNWWBVjs

B.

Conven0onal Extrusion: hXps://youtu.be/Y75IQksBb0M and hXps://youtu.be/1WALD1ZJwho

Process Speed

Temperature

Con0nuity

Reduc0on in Area

Possible materials

Product size ranges

Low speeds, due to large amount of deforma+on that occurs

B

High speeds, due to large surface area and small volumes

A

High temperatures

B

Mainly room temperature

A

Con+nuous – par+cularly if various segments can be buX welded

A

Non con+nuous, due to finite size of work piece

B

Massive reduc+ons possible – up to 400 to 1, due to hot working opera+on

B

Limited reduc+ons due to work hardening of material in process. Generally typical reduc+ons between 20% and 50%

A

Almost all duc+le materials

A

For most ferrous and nonferrous materials hotwork) and a limited range for coldwork

B

100 mm diameter to 1 mm

B

5 mm diameter down to 0.025 mm

A

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Ac0vity 4: Manufacturing Processes (20 minutes) Work with your group to select an appropriate manufacturing method (primary and secondary processes), for the following products 1-5. Each group will provide a summary.

Primary

Sand cas+ng

Die cas+ng

Forging

Extrusion

Secondary

Welding

Bending

Blanking

Machining

Rolling

Drawing

Then work individually to do the same for products 6 and 7, giving a reason for your choices.

#

Ongoing produc0on of:

Primary process(es)

Secondary process(es)

1

an automo bile cranksh ap

Die forging

Machining

2

a bronze ship propeller

Sand casting

Machining

3

an aluminiu m window frame

Extruded

Welding

4

a heavy gauge helical spring

Drawing

Bending

5

a steel bicycle frame

Extrusion

Bending

The following 2 products will be marked, and you need to give a reason: #

Ongoing produc0on of:

Primary process(es)

Secondary process(es)

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Reason

6

a base plate for a household steam iron

Rolling

Machining

Rolling- used to flatten base plate Machiningdrilling out the wholes on the base plate

7

monetary coins

Rolling

Blanking

Rolling- to create a flattened base plate Blanking- used to create the geometric shape of the coin

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