Local electrochemical impedance spectroscopy investigation of corrosion inhibitor films on copper

Abstract

In this work, the applicability of localized electrochemical impedance spectroscopy (LEIS) to characterize metal-corrosion inhibitor systems has been investigated. Copper corrosion inhibition by benzotriazole (BTA) and 2-mercaptobenzimidazole (MBI) has been studied, and compared to the electrochemical behaviour of the non inhibited metal. A rather wide frequency range of the AC potential signal was employed, namely 50 mHz ≤ f ≤ 65 kHz. The measurements were conducted for different probe-substrate distances in order to explore the effect of the different component of the localized impedance. Nyquist diagrams exhibit inductive loops in the high frequency range, and capacitive semicircles at intermediate and low frequencies for all the systems investigated, though they were affected in a different extent by the variation of the probe-substrate distance depending on the surface condition of the metal samples, this effect being more notorious for distances smaller than the dimensions of the bi-electrode probe.