Preparation method for micro-arc oxidation coating layer on surface of cast aluminum alloy

The invention relates to the field of micro-arc oxidation surface protection, in particular to a preparation method for a micro-arc oxidation coating layer on the surface of cast aluminum alloy. According to the preparation method, on the basis of common anodizing, arc discharge is used for enhancing and activating a reaction generated at an anode, so that high-quality reinforced ceramic film is formed on the surface of the cast aluminum alloy (ZL205A) material. A bipolar positive constant current and constant voltage and negative constant current and constant voltage method is mainly adopted. That is to say, the ratio of a positive constant current value to a negative constant current value is (1-1.5):1, and the ratio of a positive constant voltage value to a negative constant voltage value is (8-9):1. Micro-arc oxidation treatment is conducted on a part made of the cast aluminum alloy (ZL205A) material in an alkalescent electrolyte to obtain the micro-arc oxidation coating being stable in film layer quality