Self-healing Performance and Corrosion Resistance of a Bilayer Calcium Carbonate Coating on Microarc-Oxidized Magnesium Alloy

A CaCO3 coating with good anticorrosion and self-healing performance was fabricated on the as-prepared MAO coating on the surface of AZ41 Mg alloy via ultrasound-assisted chemical conversion, a DCPD(CaHPO4·H2O) coating was also fabricated on the MAO coating as a comparison. Surface characterizations were carried out to obtain the morphology and composition of CaCO3 coating formed and electrochemical methods were adopted to assess the corrosion resistance of Mg alloy embedded in PC paste. The self-healing property of MAO/CaCO3 coating was ascribed to the formation of extra calcite. This coating may become a potential target for surface modification of magnesium alloy formwork.