Micro-arc oxidation of Al alloys: mechanism, microstructure, surface properties, and fatigue damage behavior

Preparation of coatings with excellent properties is an effective way to address poor wear and corrosion resistance of aluminum (Al) alloys. Micro-arc oxidation (MAO) coatings exhibited high hardness, good adhesion, excellent corrosion and wear resistance. Unfortunately, defects such as micropores, cracks, overgrowth regions, and rough surface, as well as residual stress in MAO coatings are unavoidable. This entails that surface properties associated with corrosion resistance, wear resistance, and adhesion, as well as fatigue performance (SPAFP) of the MAO coated samples were more difficult to be controlled. In response to this issue, defects and residual stress control of MAO coating aiming at SPAFP optimization were studied. In this paper, the formation mechanism of MAO coating–effects of parameters on defects and residual stress–effects of defects and residual stress on the SPAFP of the MAO coated Al alloys were reviewed. Furthermore, an optimized control strategy for SPAFP was summarized. Coupling effect of micropores, cracks, rough surface, overgrowth regions, and residual stress on the SPAFP of MAO coated Al alloys was focused on. Aiming at the fatigue damage behavior, the anti-fatigue design method for the MAO coated Al alloys was proposed.