Characteristics of high-performance anti-corrosion/anti-wear ceramic coatings on magnesium-lithium alloy by plasma electrolytic oxidation surface engineering

摘要

High-performance anti-corrosion/anti-wear coatings on superlight magnesium-lithium (Mg-Li) alloy with exceptional durability are of great interest for fundamental research and practical applications. In the present study, oxide coatings are produced on Mg-Li alloy by electrochemical surface engineering-plasma electrolytic oxidation in an alkaline silicate electrolyte with addition of cerium salt. To understand the nature of coatings, we investigate their surface and cross-sectional morphologies, wettability (35 +/- 3 degrees vs 78 +/- 2 degrees), phase and chemical compositions, corrosion and tribological behaviors. Our findings show that the oxide coating prepared with cerium salt has a more compact structure with fewer defects (18 mu m in thickness). Importantly, it substantially enhances the corrosion resistance of Mg-Li alloy by three orders of magnitude and significantly retards the occurrence of localized corrosion (150 h), along with notably improved anti-wear performance (friction coefficient of 0.19).