INNOVATIONS: PRESENT&FUTURE
S P E C I A L ALU MINIU M
Qualicoat & Qualanod: latest eco-friendly developments for aluminium pre-treatment Dr. Alberto Abad, Alvarez Schaer S.A. Paterna – Valencia (Span)
alsan@alsan.es
A
s with most metals, precise preparation
metal surface. Among these solutions, we
of the aluminium surface is essential
can find ECORINSE LD, a product for the
Qualicoat A-127. Anodic pre-treatment with guarantees
to ensure the adherence of the
improvement of the adhesion of the organic
It is well known that hexavalent
coatings applied subsequently, as well as their
coatings on the anodic layer and MEDSEAL®
chromium compounds are being under
durability and optimum protection against
and FRIOFIX®ECOLINE innovative and green
observation for years. Currently the
corrosion.
sealing products free of toxic metals.
European Commission is still deciding © Alsan
Anodizing, like all industrial surface treatment processes,
on CTAC (Chromium Trioxide Authorization
involves a series of stages to
Consortium) Application
ensure its technical features and
for authorization which
finishes quality and these stages
includes the aluminium
depend on the final purpose
coating sector.
of the anodic layer. Anodic
Chrome use is
layers of 10-25 μm are usually
maintained by means of
employed as a decorative finish
prorogations requested
for aluminium which provides
by various sectors under
excellent wear and corrosion
the fear of whether
resistance.
or not, “alternative
In order for the porous anodic
products to Chromium
film to be perfectly protected against corrosion, it is necessary to seal the anodic layer. In this way, the metal loses its absorbing power, and remains protected
1
Figure 1: Filiform corrosion results obtained in the project BRITE-EURAM at the Italian site (Venice) at different exposition times, with different pre-treatments and using polyester powder as coatings.
(VI)” are able to protect aluminium in the most hostile environments and prevent corrosion, especially filiform
from aggressive exposure
corrosion.
environments.
However, previous
Besides, thin anodic layers of 3-8 μm can also be used as a superior pre-treatment for organic coatings which improves corrosion protection, especially against filiform corrosion. Alsan offers a wide catalogue of products that allows covering each and every one of the pretreatment stages guaranteeing an excellent preparation of the
90
ECORINSE LD is a non-toxic product, which allows preparing the anodic layer for the application of organic coating (liquid and powder coatings). ECORINSE LD works at room temperature in only a few seconds, getting rid of the standard hot rinse and reducing energy costs while guarantees dry and wet adhesion. The use of Ecorinse LD as final rinse for PREOX, provides under the QUALICOAT guidelines, a solution to the problem of the wet adhesion of powder coating with PREOX.”
N. 53 - SEPTEMBER/OCTOBER 2018 - international PAINT&COATING magazine
studies have shown that both, alternative products and Chromium Trioxide, are not effective enough to prevent filiform corrosion when various factors combine, such as an industrial climate or marine environment that is strongly aggressive to aluminium.