ELECTROCHEMICAL AND XPS STUDIES ON LACQUER LOW TINPLATED STEEL ADHESION

In order to promote lacquer adhesion different surface treatments have been carried out on low tinplated steels (LTS). The surface chemical composition and semiconduction properties of these materials have been studied by means of a combined use of X-ray photo-electron spectroscopy (XPS), in high energy resolution, and electrochemical analytical techniques. Along with the adhesion measurements, this study has shown that lacquer adhesion is enhanced with increase in the extent of p-type semiconduction, achieved by increasing the amount of anodically grown Sn4+ oxide and by a passive film of Cr(III) oxide. It has been suggested that p-type oxides (acceptor sites) interact, during the lacquer curing with lacquer organic functional groups to form chemical and stable bonds. The effect on the lacquer adhesion of the oxide thickness and their hydration depth has been also discussed.