A Green Conversion Coating on a Magnesium Alloy for Corrosion Protection

Abstract

A novel coating on the Mg1Mn alloy was produced by anodic polarization combined with hydrothermal treatment (AP + H) in 0.1 M Na 2 CO 3 solution. The microstructure and protection of the coating were evaluated. The coating consisted of MgCO 3 , Mg(OH) 2 and MgO, and provided satisfactory protection in 3.5 wt% NaCl with a corrosion rate of 0.07 mm y −1 in 72 h. However, after that period, the corrosion rate of the specimen increased due to the damage of the coating. The failure of the coating was strongly related to the second phase particles (e.g. Zr particles) or impurities in the matrix. The AP + H coating is supposed to be used as a primer coating for Mg applications in kitchen ware, biomedical areas or industry.