Effect of Plasma Interface Treatment and Cathodic Electrophoretic Coating on Mg Alloys
In this study, plasma treatment using Ar and H2 and plasma polymerization with trimethylsilane (TMS), were carried out to create the interface film systems with a structure of Mg/plasma interlayer/cathodic electrophoretic coating (E-coat) for a magnesium (Mg) alloy AZ31B. The interface adhesion of the coating system was evaluated using N-methylpyrrolidinone (NMP) paint removal test and ASTM tape test conducted under dry and wet conditions. Plasma TMS film could stick the Mg substrate more strongly than E-coat.The surface of samples with different interlayer treatment after NMP test has been observed by SEM. The potentiodynamic study performed on the E-coated samples showed a noticeable reduction of corrosion current, three orders of magnitude less than bare Mg. Salt spray test also was done to confirm the resistance corrosion of E-coat. It was found that plasma interface treatment has the ability of increasing the adhesion of E-coat on Mg alloy more or less, thus restrict access to damaging species that exist in Cl- aqueous environments.
Zhong Wei Gu, Yafang Han, Fu Sheng Pan, Xitao Wang, Duan Weng and Shaoxiong Zhou
J. Zhang et al., "Effect of Plasma Interface Treatment and Cathodic Electrophoretic Coating on Mg Alloys ", Materials Science Forum, Vols. 610-613, pp. 984-990, 2009