Electrochemical response of ZrO2-incorporated oxide layer on AZ91 Mg alloy processed by plasma electrolytic oxidation

ZrO2 nanoparticles well dispersed in an electrolyte were effectively incorporated in an oxidized surface passivation layer on AZ91 Mg alloy by a plasma electrolytic oxidation (PEO) process. The electrophoretic reaction and mechanical mixing in molten magnesium oxide were the main factors leading to incorporation of ZrO2 nanoparticles in the magnesium oxide layer. Incorporated ZrO2 nanoparticles were mainly located in pores that were generated during the PEO process. The results of a potentiostatic polarization analysis and a salt spray test clearly indicated that the corrosion resistance of the PEO treated layer was significantly improved by the incorporation of ZrO2 nanoparticles.