Effects of oxidation time on micro-arc oxidation coating of MB8 magnesium alloy

The effects of oxidation time on the density, thickness and corrosion resistance of the micro-arc oxidation coatings of MB8 magnesium alloy were investigated. The changes of the micro-topography, component and structure of the coatings with different oxidizing periods were analyzed. The results show that the coating thickness increases with the prolonged oxidation time, but the coating surface gets rough. The corrosion rate of the coating is lowest when the appropriate oxidation time is 10 min. Initially the content of the micro-arc oxidation coating is mainly composed of cubic structure MgO, with the oxidation time prolonged, both Mg2(SiO4) with orthorhombic crystal structure and Mg(PO3)2 with monoclinic crystal structure increase gradually in the coating.