Surface modification of magnesium alloy by micro-arc oxidation

In this study, AM60 magnesium alloy was oxidized in an alkali solution for 30 min. on a 30 kW AC micro-arc oxidation equipment. Characterization of the oxidized surfaces was made by microstructural analysis, roughness measurements, hardness measurements, and reciprocating wear tests. Microstructural investigations were performed on the surfaces and cross sections of the samples by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffractometry (XRD) analysis. Microscopic examinations revealed that a porous oxide coating which was mainly consisted of MgO and MgAl2O4, was formed. Formation of the oxide coating by micro-arc oxidation on AM60 magnesium alloy resulted in considerable surface hardening and surface roughing. Reciprocating wear tests revealed that micro-arc oxidation caused remarkable improvement in wear resistance when compared to unoxidized state.