【摘要】 采用双极性阶梯降流方法,研究了硅酸盐系和磷酸盐系电解液中AZ91D镁合金的成膜过程及膜层之间的异同。结果发现,AZ91D镁合金在两种电解液中微弧氧化处理后形成25μm~40μm膜层,膜层的显微硬度为290HV~520HV。在相同工艺条件下,两种电解液所形成的膜层表面都有许多微孔,同时还存在大量交错的微裂纹。由于硅酸盐系电解液中电压上升速率较快,所形成的膜层致密性较好。硅酸盐系所形成膜层由MgO、SiO2 和MgF组成,磷酸盐系所形成的膜层由MgF、Mg(PO ) 组成。更多还原

【Abstract】 Film formation process and the differences between film layers of Mg-based AZ91D alloy in silicate and phosphate electrolytes were studied by step-down current method.The results showed that 25μm～40μm anodic films on AZ91D alloy are formed in two electrolytes after microarc oxidation,and microhardness of the films is ranged between 290HV and 520HV.Under the same processing conditions,there are a lot of micropores and microcracks on the films formed in the two electrolytes.The increasing rate of voltage is larger in silicate solution than that in phosphate solution,consequently the films formed in silicate solution has better compactibility.The oxide film formed in silicate solution is composed of MgO、SiO₂ and MgF₂,while the oxide film formed in phosphate solution is composed of MgF₂ and Mg₃ （PO₄）₂.更多还原