Acta Phys. -Chim. Sin. ›› 2016, Vol. 32 ›› Issue (9): 2271-2279.doi: 10.3866/PKU.WHXB201606071

• ARTICLE • Previous Articles     Next Articles

Preparation and Characterization of Black Micro-Arc Oxidation Films

Jing-Ying BAI1,*(),Si-Zhen LI1,Da-Jiang ZHENG3,Li-Gong ZHANG1,Li FENG1,Qing-Xin CUI1,Jing-Run WANG1,Wen-Wu JIANG1,Chang-Jian LIN2,*()   

  1. 1 Beijing Spacecrafts, China Academy of Space Technology, Beijing 100190, P. R. China
    2 College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian Province, P. R. China
    3 College of Materials, Xiamen University, Xiamen 361005, Fujian Province, P. R. China
  • Received:2016-04-05 Published:2016-09-08
  • Contact: Jing-Ying BAI,Chang-Jian LIN;
  • Supported by:
    National Natural Science Foundation of China(21321062)


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.

Key words: Micro-arc oxidation, Phosphate, Magnesium alloy, Formation mechanism, Black oxidation film