Fabrication and degradation behavior of micro-arc oxidized biomedical magnesium alloy wires

A composite ceramic coating containing zirconium is prepared by micro-arc oxidation (MAO) of magnesium alloy wires in a silicate–phosphate composite electrolyte modified with zirconium salts and sodium hydroxide. The effects of the NaOH content in the electrolyte on the microstructure and corrosion resistance of the composite ceramic coating are determined and the degradation behavior is investigated in both simulated body fluid (SBF) and simulated intestinal fluid (SIF). By adding an appropriate amount of NaOH to the composite electrolyte with K2ZrF6, the arcing voltage can be reduced and the surface flatness, pore size, and surface coating thickness can be effectively regulated to improve the corrosion resistance. The composite ceramic coating composed of MgO, MgSiO3, and a small amount of ZrO2 retards surface degradation in both the SBF and SIF environments at different pH values.