Parameters affecting longterm performance of painted galvanised steels

The aim of this work was to investigate which parameters affect the longterm performance of coil coated galvanised steel sheet. Therefore, the paint adhesion and corrosion resistance of selected painted pretreated galvanised steel substrates were studied. The systems investigated included chromatefree pretreatments and primers. The polymer coated panels were tested by using Tbend, combined cross cut and adhesion, prohesion and QUVA tests. The surface energy of the painted panels was determined by contact angle measurements and outdoor testing of the panels was also initiated. The test results showed that the primer was the most important parameter for painted metal alloy coated steel, but the longterm performance of the system also depends on the compatibility of all four layers, i.e. substrate, pretreatment, primer and topcoat.