Synergistic effect of "double pores" texture on tribological properties of AZ31 Mg alloy micro-arc oxide ceramic coatings

Micro-arc oxidation (MAO) technology for the generation of ceramic coatings on metal surfaces have been gradually used for protecting metal components from the severe wear and corrosion attack. In this study, laser texturing was applied to ameliorate the MAO ceramic coating. The scalability of ceramic coated samples by laser texturing technology was scrutinized in terms of microstructure, coefficient of friction (COF) and corrosion resistance. It turns out that the "Double pores" system generated by laser structuring of the substrate before MAO treatment has the capacity to enhance the tribological properties of the ceramic coating. After laser structuring, the proportion of magnesium oxide in the ceramic coating generated by the Mg alloy substrate increases, which is due to the oxidation of the magnesium substrate by the high temperature laser. At the same time, it also accounts for the increase in cracks on the surface of the coating. In addition, the presence of cracks has an impact on the corrosion resistance of the ceramic coating. Interestingly, the COF of the treated ceramic coating becomes lower and the heat from the texturing process has a "Quenching effect" on the substrate. In general, the COF of the ceramic coating on the surface of the laser texturing Mg substrate is reduced by 31 % compared to the original ceramic coating, at the expense of some corrosion resistance.