Microstructure and corrosion resistance of micro arc oxidation plus electrostatic powder spraying composite coating on magnesium alloy

Based on the morphological characteristics of the microporous micro arc oxidation (MAO) ceramic coating, a double layer composite coating system was applied on the surface of AZ31 magnesium alloy by MAO plus electrostatic powder spraying (EPS) technique. The Mg sample coated with MAO plus EPS (MAO + EPS) was compared with Mg sample coated by MAO coating or EPS monolayer. The results indicated that the corrosion resistance of AZ31 Mg alloy was significantly improved by MAO + EPS composite coating with the exellent binding force. Furthermore, the corrosion mechanism of three coated Mg alloy was discussed.