AZ91镁合金在磷酸盐体系中微弧氧化的工艺研究

Micro-arc Oxidation of AZ91 Die Cast Magnesium Alloys in Phosphate Electrolyte

采用磷酸盐体系在AZ91压铸镁合金表面制备了一系列微弧氧化膜层,并通过中性盐雾试验、扫描电镜等方法研究了各种工艺条件下的微弧氧化膜层耐蚀性能及形貌特征。结果表明,经微弧氧化处理,AZ91压铸镁合金试样的耐腐蚀性能明显提高。在磷酸盐体系中进行微弧氧化处理的最佳工艺方案为:磷酸钠5g·L-1,氢氧化钠6g·L-1,电流密度3A·dm-2,氧化10min。

A series of micro-arc oxidation （MAO） layers were produced on AZ91 die cast magnesium alloys in phosphate electrolyte with different parameters. The effects of concentration of sodium phosphate and sodium hydroxide, current density and duration on MAO layers growth regularity were discussed. The surface features and corrosion resistance of the layers were investigated using scanning electron microscopy and neutral salt spray test, respectively. The results show that the corrosion resistance of AZ91 die cast magnesium alloy improved greatly after MAO treatment. The optimum technological condition was settled as follows： 5 g·l^-1 Na3PO4, 6 g·l^-1 NaOH, 3 A·dm^-2 current density and 10 min duration, in which the sample oxidized had a beneficial surface morphology and corrosion rate of 0.132 6 mm/a.