Effect of TiO 2 addition on the corrosion resistance of micro-arc oxidation coatings on 6061 aluminum alloy

Micro-arc oxidation (MAO) technology was employed to fabricate composite ceramic coatings on a 6061 aluminum alloy substrate. TiO2 nanoparticles were introduced into a silicate-based electrolyte to investigate their effects on the microstructure and properties of the MAO coatings. The results revealed that the TiO2-containing coating exhibited a smoother and denser surface with reduced pore size, as well as increased thickness and significantly improved corrosion resistance compared with the additive-free MAO coating and the 6061 aluminum alloy substrate. Furthermore, the corrosion current density of the MAO/TiO2 coating decreased by three orders of magnitude, while the corrosion potential shifted in the positive direction by 0.94 V. The impedance arc radius was also considerably larger than that of the 6061 aluminum alloy. In addition, salt spray testing revealed no visible signs of corrosion after 720 h of exposure, demonstrating the excellent corrosion resistance of the MAO/TiO2 coating. These findings provide insights into the formation and corrosion protection mechanisms of TiO2-doped ceramic coatings, extending the potential application of MAO technology to a broader range of metallic materials and providing a theoretical foundation and technical support for improving the surface protection of metallic alloys in industrial corrosion protection applications.