Effect of Energy Density on Microstructure and Properties of Al2O3 Plasma Electrolysis Oxidation Film

The effect of exported energy density on the plasma electrolysis oxidation (PEO) process was studied under transient self-feedback control (TSFC) mode. Properties of the Al2O3 PEO films were characterized by scanning electron microscopy (SEM), Vickers hardness test and electrochemical impedance spectroscopy (EIS). Experimental results indicated that a hard and compact PEO film was obtained at a correct energy density due to the uniform action of the high-frequency square voltage waveform (HFSVW). On the contrary, the high energy density greatly weakened the uniform action of the HFSVW which resulted in large pores and microcracks in the PEO films.