Evaluation of corrosion rates by the faradaic rectification method

Abstract

Accurate evaluation of corrosion currents from polarization data has been the aim of many workers in the recent past. This, however, requires both polarization resistance and Tafel slope measurements. Although many accurate methods have been developed for polarization resistance measurements a certain amount of ambiguity still exists regarding the measurement and the validity of Tafel slopes at corrosion potential. A method for evaluation of corrosion currents is presented in this paper based on the faradaic rectification technique. According to this method the corrosion current ( ICorr is given by ▪ where R p is the polarization resistance and ( δE/ V 2) ω→ O and ( δE/ V 2) ω→∞ are the rectification ratios at low and high frequency a.c. signals. The method does not require Tafel slope measurements, hence the controversy generated as to the validity of Tafel slopes at E Corr is completely eliminated.