Impedance studies of the inhibitive effect of benzotriazole on the corrosion of copper in sodium chloride medium

Impedance studies of a copper electrode in chloride medium with or without benzotriazole (BTA) were made over a wide frequency range (10^?2?10²KHz). The impedance characteristics of the Cu-BTA surface film were established under various experimental conditions. The results indicate that the film was of a dielectric nature having a dielectric constant of ca. 20. It was found that the film thickness increased and the corrosion rate decreased by increasing the BTA-concentration or with ageing. It was assumed that, at the stationary state, the rate of dissolution of Cu-BTA film blanced that of the slow transport of Cu ions through the film. Good support for these results was obtained from the data of potentiostatic polarization and weight loss measurements.