Growth characteristics and corrosion resistance of micro-arc oxidation coating on pure magnesium for biomedical applications

Protective micro-arc oxidation (MAO) coating was prepared on pure magnesium in aqueous solution without toxic components under a constant current density. The whole anodizing process can be divided into four stages based on the differences in voltage, sparking behaviour and oxygen evolution. SEM micrographs show that a thick and dense coating can be obtained after anodizing for adequate time. The corrosion resistance of the samples with anodic coatings was evaluated by drop experiments and potentiodynamic polarization tests. The results confirm that the thick and dense coating can efficiently protect the magnesium substrate from corrosion in aggressive environments.