Since the inception of micro-arc oxidation technique, the research on the mechanism of micro-arc oxidation has never stopped. During this period, the research on micro-arc oxidation process of breakdown phenomenon is in depth, and the breakdown model also has been established. Because the micro-arc oxidation process involves many complicated phenomena such as heat, light, electricity, there are a lot of difficulties to deal with. Therefore it has not the perfect qualitative and quantitative model to explain all the phenomena. This paper reviewed the research progress of the mechanism of micro-arc oxidation, observed and analyzed the phenomena and the possible reactions of micro-arc oxidation process at all stages. This paper also discussed plasma’s important role in the process of micro-arc oxidation.Since the inception of micro-arc oxidation technique, the research on the mechanism of micro-arc oxidation has never stopped. During this period, the research on micro-arc oxidation process of breakdown phenomenon is in depth, and the breakdown model also has been established. Because the micro-arc oxidation process involves many complicated phenomena such as heat, light, electricity, there are a lot of difficulties to deal with. Therefore it has not the perfect qualitative and quantitative model to explain all the phenomena. This paper reviewed the research progress of the mechanism of micro-arc oxidation, observed and analyzed the phenomena and the possible reactions of micro-arc oxidation process at all stages. This paper also discussed plasma’s important role in the process of micro-arc oxidation.

In this paper, the typical cold work die steel Cr12MoV was used as substrate material for vanadizing treatment. And the coating structure and bonding strength were studied. Moreover, comparison experiment of wear resistance between the coating and the substrate material was performed, and based on the experiment results, wear failure mechanism of vanadizing layer was analyzed. The results showed that vanadium carbide coating is dense, with fine grain structure and high bonding strength. These features help to improve the wear resistance of coatings. Comparision of wear performance between coating and substrate showed that vanadizing surface layer can significantly improve wear resistance of substrate material. Friction coefficient decreased from the 0.48 to 0.33 and wear weight loss decreased by 95%. Wear Failure analysis showed that the vanadium carbide layer of the wear mechanism is fatigue spalling wear.