Electrochemical properties of passivation film formed on 316L stainless steel in acetic acid

The electrochemical properties of passivation film on 316L stainless steel were investigated by electrochemical impedance spectroscopy (EIS), Mott-Schottky analysis and cyclic voltammetry graph under the corresponding conditions. The result shows that passivation film on 316L stainless steel is steady in 60% acetic acid solution from 25℃ to 85℃, the polarization resistance decreased but the interface capacitance increased with increasing temperature. There is no obvious relation between temperature and semiconductor intrinsic properties. The passivation film represents the n-semiconductor characteristic in the potential interval of -0.5-0.1 V, the p-semiconductor characteristic in the potential interval of 0.1-0.9 V, and the n-semiconductor characteristic in the potential interval of 0.9-1.1 V. The graph of cyclic voltammetry shows that when the temperature is lower than 55℃ the passivation film's structure is more steady, when the temperature is 55℃ its stability tends to worsen and when the temperature exceed 55℃ its stability declines.