Influence of NaAlO 2 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°. 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 R₃ (8.14 × 10⁴ Ω∙cm²), signifying better corrosion resistance. [ABSTRACT FROM AUTHOR]