Effect of operating condition on micro-arc oxidation of magnesium alloys

AZ31B magnesium alloys were treated by micro-arc oxidation at constant current in electrolyte containing Na₂SiO₃, NaF, glycerol and KOH. The effect of constituents and concentration of electrolyte, current density and treatment time on MAO process and coating property was investigated respectively. With the increasing of concentration of electrolyte, the ignition time and breakdown voltage decreased, and the coating thickness increased. With the increasing of NaF content, the spark phenomenon was restrained, and the coating thickness decreased with the increasing of glycerol which can stabilize the electrolyte. No direct relationship was established between applied current density and breakdown voltage. The coating thickness increased with the prolonging of MAO process.