Abstract:The 7075 aluminum alloys with 0%, 0.2% and 0.4% Er were subjected to micro-arc oxidation under the same parameters. The surface morphology and the phases of the oxide coating were analyzed using SEM and XRD. The micro-hardness, thickness and corrosion resistance of the oxide coating were also studied. The results show that the micro-arc oxidation coating of 7075 aluminum alloy with different Er contents is composed of gamma- Al2O3 phase. With the increase of Er content, the peak of gamma- Al2O3 phase is enhanced. Er enters the oxide coating with the form of Al17Er2, which is an unbalanced phase after micro-arc action. With the increase of Er content, the surface roughness of oxide coating decreases firstly and then increases. When Er content is 0.2%, the surface deposit is fine and uniform, the diameter of pore is small, and the roughness is the lowest. As the Er content increases from 0% to 0.4%, the micro-hardness and thickness of the oxide coating also increases, and then the corrosion resistance increases significantly. Consequently, the self-corrosion current density decreases from 4.280×10^-6A/cm² to 2.405×10^-9A/cm².