Influence of NaAlO₂ Concentration on the Characteristics of Micro-Arc Oxidation Coating Fabricated on a ZK60 Magnesium Alloy

This study investigated the impact of NaAlO2 concentration in electrolytic solutions on micro-arc oxidation (MAO) coatings, focusing on their surface quality enhancement and corrosion resistance improvement. The surface morphology and microstructure of these coatings were assessed using scanning electron microscopy. Mechanical properties, such as hardness and wear resistance of MAO coatings, were tested. The hardness of the 6 g/L group was 411.2 HV. X-ray photoelectron spectroscopy examinations showed that MgAl2O4, CaMgP2O7, and MgSiO4 were the phases in the MAO coating. Antibacterial assessments were performed to evaluate the influence of NaAlO2 concentration, and the antibacterial rate of the 6 g/L group reached 97.08%. The hydrophilicity of the coatings was determined using water contact angle measurements, wherein the water contact angle of the 6 g/L was the lowest, at 58.25 degrees. Corrosion resistance was evaluated with an electrochemical workstation. The findings revealed that the MAO coatings prepared with a NaAlO2 concentration of 6 g/L exhibited superior uniformity with fewer defects, enhanced corrosion resistance, and increased adhesive strength compared to other concentration groups. The 6 g/L NaAlO2 concentration MAO coating demonstrated the highest fitting coating resistance R-3 (8.14 x 10(4) Omega center dot cm(2)), signifying better corrosion resistance.