Incorporation of AlO and ZrO ceramics to AZ31 magnesium alloys composite coating using micro-arc oxidation method.

In this research, a composite coating with AlO and ZrO particles have been applied on AZ31 magnesium alloy by micro-arc oxidation (MAO) technique. The alkaline electrolyte included a constant based composition and different composition of the AlO and ZrO additives. Microstructure observations reveal that the surface pores of composite coating reduced during addition of ZrO and AlO ceramic particles. The hardness of coating increased from about 380 for non-added to 620 MPa for AlO+ZrO added coating and wear rate reduced about 8 times. Wettability of the coating increased by incorporation of AlO and/or ZrO particles while, AlO is more effective than ZrO. Addition of the ceramic particles enhanced the hydrophilicity properties of surface in wettability test and a contact angle of 43° was obtained for coating including AlO+ZrO. The antibacterial properties of MAO coatings showed that S. aureus bacterium is more sensitive to the zirconia and alumina particle than S. typhimurium bacterium after 24 h of incubation.