Characterization of Micro-arc Oxidation of ZL109 Cast Al-Si Alloy

The growth process of micro-arc oxidation films on ZL109 cast Al-Si alloy was investigated and the relation between current density and arc voltage, arc time and the growth rate of the films was discussed. Additionally, the morphology, element distribution and phase components of the films of the ZL109 higher-silicon cast aluminium alloys were analyzed. Results indicated that in the oxidation process, arc voltage was a constant under the condition of varied current densities; moreover, when current density increased, arc time shortened, film thickness increased, and the growth rate of films first increased and then decreased. The oxidation film was mainly composed of mullite (3Al₂O₃ • 2SiO₂), α-Al₂O₃ and γ-Al₂O₃ phase, among which, the content of mullite was the highest.