Adhesion and corrosion studies of electrophoretic paint on AZ31 Mg alloy pretreated in cerium solution with and without addition of ethanol

In this study, the adhesion and corrosion resistance of electrophoretic paint (E-paint) were studied on AZ31 Mg alloy pretreated in cerium conversion coating (CeCC) solutions with and without addition of ethanol. It was found that the addition of ethanol to CeCC solution can decrease the formation of Mg(OH)2/MgO and increase the formation of nano-crystalline cerium oxides on AZ31. The E-paint on AZ31 pretreated in Ce-water-ethanol solution showed strong adhesion with no detachment after water immersion test for 500 h at 40 °C, and no blisters were observed on the surface and scratched lines after 1000 h salt-spray test. In contrast, the E-paint on AZ31 pretreated in Ce-water solution showed large blisters and weak adhesion with some flakes detachment along the intersections of cuts. Moreover, the E-paint on AZ31 pretreated in Ce-water solution showed that blisters are formed adjacent to the scratched lines after 500 h salt-spray test.