Protective coatings have been successfully prepared on a high strength aluminum-copper alloy ZL205 using a micro-arc oxidation (MAO) method. The influence of the oxidation time and current density on the thickness and corrosion resistance of MAO coatings has been studied. The thickness of MAO coating increases linearly with an increase of oxidation time. When the oxidation time is shorter than 20 minutes, the coating improves the corrosion resistance of ZL205 alloy quickly with an increase of oxidation time, which is confirmed by 5% salt spray test. When the oxidation time is longer than 20 minutes, the corrosion resistance of the MAO coating increases slowly with an increase of oxidation time. For a fixed oxidation time, the thickness of the MAO coating increases with an increase of current density and the corrosion resistance can also be improved. SEM and XRD analysis show that the surface morphology and phase of the MAO coating change with an increase of the oxidation time, which results in different corrosion resistance of the MAO coating.

Keywords: micro-arc oxidation; casting aluminum-copper alloy; ceramic coating; corrosion resistance