Multifunctional micro-arc oxidation coatings on VW75 magnesium alloy: Synergistic enhancement of corrosion resistance and mold inhibition with Ta2O5@ATO hybrid nanostructures

Micro-arc oxidation (MAO) coatings were successfully developed on rare-earth magnesium alloys through the incorporation of tantalic oxide (Ta2O5) and varying concentrations of antimony-doped tin oxide (ATO) nanoparticles into the electrolyte. Comprehensive analyses were conducted to investigate the coatings' thickness, microstructure, and chemical composition. Furthermore, the coatings were subjected to extensive evaluations of their corrosion resistance, hydrothermal stability, and resistance to mold growth. The experimental findings demonstrated that the primary crystalline phases within the Ta2O5@ATO composite coatings were MgO and Ta2O5. The introduction of ATO nanoparticles into the electrolyte played a pivotal role in enhancing the coating's thickness and densification, which, in turn, led to marked improvements in hydrophobic stability. Among the various concentrations tested, a nanoparticle concentration of 3 g/L was identified as the optimal level for achieving superior corrosion resistance and hydrothermal stability in the Ta2O5@ATO composite coatings. Additionally, the composite coatings exhibited pronounced mold resistance properties, demonstrating significant resistance to mold growth under tested conditions. These results highlight the potential of Ta2O5@ATO composite coatings as a multifunctional surface modification strategy for rare-earth magnesium alloys in challenging environments.