Effects of Electrolyte Composition on Corrosion Resistance of Micro-arc Oxidation Film on AZ80 Magnesium Alloy

In order to improve the corrosion resistance of AZ80 magnesium alloy, the oxide film was grown in-situ on the surface of magnesium alloy by micro-arc oxidation(MAO).Effects of Na₂SiO₃ and NaOH on the corrosion resistance of MAO film were systematically investigated.The chemical composition of oxide film was characterized by X-ray diffraction (XRD) and energy spectroscopy (EDS).The microstructure of oxide film was characterized by scanning electron microscopy(SEM).the corrosion resistance was studied by neutral salt spray test.The results indicate the corrosion resistance of MAO film increases first and then decreases with the increase of Na₂SiO₃ concentration, and increases with the increase of NaOH concentration.The MAO film fabricated under optimal ratio exhibits excellent corrosion resistance without pit corrosion after neural salt spray test for 96 h, which is attributed to Na₂SiO₄ phase generated on the surface and self-sealing microstructure.