Influence of a Vinyl-Silane Pretreatmenton the Adhesion Strength of Epoxy Acrylic-Urethane Clear Coatings onAA 1050 Aluminium Alloy

摘要

The influence of a vinyl-silane pretreatment on the performance of epoxy and acrylicurethanernclear coatings on an AA 1050 aluminium alloy has been studied andrncompared with that of a chromate/phosphate conversion coating treatment. Thernsurface free energy of the silane treated Aluminium samples was calculated usingrnstatic contact angle measurements. The chemical interactions between the silanerncompound and the aluminium surface was examined using FTIR-ATRrnSpectroscopy.Adhesion strength of the pretreated coated samples were evaluatedrnusing pull-off test method in the dry, wet and recovery conditions.rnThe contact angle measurements indicated a relative increase in the surface freernenergy of the treated aluminium substrate. FTIR results revealed two modes ofrninteraction; one is between silane and Al3+ (Si-O-Al), and the other is indicative of arnsiloxane network (Si-O-Si). Direct pull-off adhesion measurements test results ofrnacrylic-urethane coated samples showed the relatively improvement in initial bondrnstrength compared to epoxy coated silane treated aluminium substrates. Thisrnimprovement was maintained after exposure to accelerated test condition. Allrnevidences revealed a relatively better performance of acrylic-urethane coated silanernpretreated samples.