(华中科技大学 材料成形与模具技术国家重点实验室，武汉 430074)
摘 要:
关键字: AZ91D镁合金；微弧氧化；(NaPO3)6；耐蚀性
（State Key Laboratory of Material Processing and Die & Mould Technology, Huazhong University of Science and Technology, Wuhan 430074, China）
Abstract:(NaPO3)6 with various concentrations was added to Na2SiO3-KOH electrolyte system, the ceramic coatings that were composed of MgO, Mg2SiO4, MgAl2O4 and amorphous phase were prepared by micro-arc oxidation (MAO) technique on AZ91D magnesium alloy. Effects of (NaPO3)6 concentration on chemical composition, microstructure and corrosion resistance of the MAO ceramic coatings were studied by using environmental scanning electron microscopy (ESEM), X-ray diffractometer (XRD), energy dispersive analysis of X-rays (EDAX) and electrochemical method. The results show that with the increase of (NaPO3)6 concentrations, the thickness and surface roughness of coatings appropriately linearly increase; the microstructures of the coatings change a lot; the contents of MgO and Mg2SiO4 increase at first and then decrease, while MgAl2O4 content gradually decreases. When the dosage of (NaPO3)6 is 5 g/L, the coating obtained has the best corrosion resistance, whose corrosion current density is reduced by over 3 orders of magnitudes compared with the substrate and the corrosion potential increases 233.7 mV in positive direction. However, the corrosion resistance of the MAO coatings decreases with (NaPO3)6 concentrations further increasing.
Key words: AZ91D magnesium alloy; micro-arc oxidation; (NaPO3)6; corrosion resistance
