Effect of Process Conditions on Micro-arc Oxidation Coating of ZL205A Aluminum Alloy

A micro-arc oxidation layer on ZL205A aluminum alloy was prepared in sodium silicate electrolyte system with different technologies. The effects of oxidation voltage and oxidation time on the properties of the film were investigated by means of thickness gauge, scanning electron microscope (SEM), X-ray diffractometer and so on. The results showed that the oxide film was mainly composed of α-Al₂O₃, Mullite (Al₆Si₂O₁₃), Al phase and amorphous phase. The pore size of the discharge channel of the oxide layer increased with the increase of oxidation voltage and time; as the oxidation voltage and time increased, the thickness of the oxide layer increased linearly. The hardness of the oxide film at a distance of 50 μm from the substrate (1 358 HV) was higher than that at 200 μm from the substrate (1 176 HV). The film structure and properties of the micro-arc oxidation layer of ZL205A aluminum alloy can be effectively improved by adjusting the process conditions.