In Europe, 2.5 - 4 micron Zn-pigmented corrosion protection primers (CPP) are being used by the automotive industry. A short introduction describing the development steps leading up to the state of the art is given and also the reasons for using it in practice. For some applications it became necessary to try to achieve a significantly higher level of corrosion resistance than this 'first generation' type coating can offer. It was also important to lower the curing temperature of the paint considerably in order to be able to supply bake-hardening grade steels. This type of corrosion protection primer is now called the 'second generation'. The Opel-production of the Astra-family started using 2nd generation CPP (4 - 6 micron) on chromate-free pre-treatment and EG for hood and crash box in 2004. One development path of 2nd generation CPP with iron phosphide pigmented coatings and a higher coating thickness showed very promising properties. On the other hand - due to the fact that these pigments are very hard - abrasion tests on a pilot scale and also experience in the press shop showed it would need coated tools to minimize tool wear. New second generation systems based only on Zn-pigments do not have this restriction. The newest developments show high potential to lower the coating thickness even further and thus make cost savings possible. The development process is still ongoing and for effective progress, a good mutual basis for laboratory evaluation of properties is of valuable support. In a Steel Institute VDEh working group (Arcelor, Corus, Salzgitter, ThyssenKrupp, voestalpine), test procedures are being generated in order to be able to correctly assess properties such as corrosion resistance, adhesion, peeling-off behavior, etc. An overview of the procedures is given together with correlations between laboratory results and reality. To round up the paper, corrosion protection primers have a number of potentials which can be utilized by the automotive industry to justify the additional cost. Examples highlighted with results giving evidence of these potentials are shown.
Status of corrosions protection primers for the automotive industry
Stand der Entwicklung von Korrosionsschutzprimern für die Autoindustrie
2005
8 Seiten, 7 Bilder, 3 Quellen
Aufsatz (Konferenz)
Englisch
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