中文摘要：

利用二次微弧氧化法,通过在磷酸盐体系的电解液中添加柠檬酸铁,在AZ40M镁合金基底表面成功制备了黑色的微弧氧化膜层。并利用扫描电子显微镜（SEM）、能谱仪（EDS）、X射线衍射（XRD）和X射线光电子能谱（XPS）分别对黑色膜层的形貌和成分组成进行了表征,探讨了黑色微弧氧化膜层的形成过程及机理。结果显示,黑色膜层的主要成分为氧化镁,同时伴随着一定量的铁氧化物,包括四氧化三铁、氧化亚铁和单质铁。因此镁基底表面黑色膜层的形成可归因于柠檬酸铁中的铁离子在成膜过程中参与反应形成了黑色的四氧化三铁、氧化亚铁和单质铁混合物,并均匀地沉积在氧化膜中。

英文摘要：

Black micro-arc oxide film layers were prepared on AZ40M magnesium alloy substrates by twostep micro-arc oxidation in a phosphate electrolyte with ferric citrate. The morphologies and compositions of these films were characterized by scanning electron microscopy （SEM）, energy-dispersive spectroscopy （EDS）, X-ray diffraction （XRD）, and X-ray photoelectron spectroscopy （XPS） to provide details regarding the film formation mechanism. The results showed that the main component of the oxide films was magnesium oxide, with various iron compounds also being present, including ferroferric oxide, ferrous oxide, and metallic iron. These results indicate that the formation of black film can be attributed to the precipitation of these species during the oxidation of iron ions by ferric citrate in the electrolyte.