Effects of Surface Pretreatment on Deposition and Adhesion of Electrophoretic Paint on AZ31 Mg Alloy

Abstract

In this work, electrophoretic paint (E-paint) was deposited on AZ31 Mg alloy after four different surface pretreatments: knife abrading, SiC paper abrading, deionized (DI) water immersion and NaOH immersion. The deposition process of E-paint was studied by analyses of voltage-time and current-time curves, amount of deposited paint, current efficiency and surface oxide film resistance and the adhesion of E-paint was examined by tape test before and after immersion in DI water for 500 h at 40 o C. It was found that the induction time for the deposition, the amount of deposited paint and the current efficiency are inversely proportional to the resistances of surface films prepared by different surface pretreatment methods. The electrophoretic painting showed longer inductance time, larger amount of deposited paint and higher current efficiency on the highly conducting surfaces, such as knife-abraded and SiC-abraded surfaces than on the less conducting surfaces, such as DI water-immersed and NaOH-immersed samples. Excellent adhesion was observed on the E-paintings deposited onto knife-abraded and SiC-abraded AZ31 Mg alloy samples.

Preparation of a hydrophobic cerium oxide nanoparticle coating with polymer binder via a facile solution route

“…Spray-coated thin films generally have poor adhesion with the substrate due to weak van der Waals forces between the NPs and the substrate [18]. Pretreatments that intentionally roughen the surface of the substrate to improve adhesion have been widely used, but are not appropriate for sensitive and fragile substrates where physical damage to the substrate may occur [19,20]. Alternative approaches to improving adhesion have been reported, wherein the incorporation of polymeric materials was found to improve adhesion between metal oxide powders used in the electrodes of lithium-ion batteries [21][22][23][24][25][26][27].…”