Effects of Pulse Duty Cycles on Microarc Oxidation Formed on Al

In order to reveal the effects of positive-pulse duty cycle of a AC pulse power on mricoarc oxidation,a constant current density(75mA·cm~(-2)) and a series of positive-pulse duty cycles which ranged from 2% to 18% were applied.The formed oxide film are mainly composed of α-Al_2O_3 and γ-Al_2O_3.As the duty cycle increases,α-Al_2O_3 becomes the predominant phase,and the surface of the oxide film gets coarser.The oxide film formed at the duty cycle of 10% has a maximum thickness and best section morphology.