Effect of electrical parameters on the growth and properties of 7075 aluminum alloy film based on scanning micro-arc oxidation with mesh electrode

Abstract

The effect of electrical parameters on the properties of 7075 aluminum alloy films under scanning micro-arc oxidation was studied. The process of micro-arc oxidation is simulated in this paper. This method greatly reduces the experimental cost of micro-arc oxidation research and provides a new idea for the subsequent research of micro-arc oxidation. The micro-arc oxidation process was simulated by COMSOL Multiphysics. The film thickness, hardness and corrosion resistance are used as indexes, and forward voltage, positive duty cycle and pulse frequency are used as design factors to carry out orthogonal experiments with three factors and three indexes. Vega XMU scanning electron microscope is used to observe the surface and section morphology of the micro-arc oxidation film. VERSA STAT 3 F electrochemical workstation is used to detect the potentiodynamic polarization curve of the film and Tafel fitting is performed to obtain the self-corrosion potential (Ecorr). The thickness and hardness of the film are tested by Nix coating thickness tester and HV-1000 Vickers hardness tester. The results show that the film uniformity of the network electrode is better than that of the tube electrode under the condition of scanning micro-arc oxidation. The order of electrical parameters affecting film thickness and hardness is forward voltage > forward duty cycle > pulse frequency. The order of the electrical parameters affecting the corrosion resistance of the film is pulse frequency > forward voltage > forward duty cycle. The best combination of electrical parameters is: forward voltage 500 V, forward duty ratio 30%, pulse frequency 200 Hz.