Corrosion Rate Measurement under Cathodic Polarization by Faradaic Rectification

Abstract

Cathodic polarization in corroding electrodes introduces the possibility of the electrode potential being close to the Nernst reversible potential (emr) of the metal dissolution/deposition reaction. While applying electrochemical techniques to measure corrosion rates for electrodes under cathodic polarization one needs to be cognizant of this and cannot make the usual assumption that the corrosion potential (Ecor) is far from EMr. We propose here a technique based on faradaic rectification for instantaneous corrosion rate measurements of electrodes under cathodic polarization. Theory based on the first principles of electrode kinetics is explained. Corrosion rates of cathodically polarized steel in 0.5M sulfuric acid and 0.5M sodium sulfate are computed using the derived theoretical expression. © 1991, The Electrochemical Society, Inc. All rights reserved.