Improved Method for Measuring Corrosion Rate with Dual Electrodes

Abstract

General equations for dual electrode polarisation have been derived in this work. The equations suggest an improved method for measuring the corrosion rate giving less error than previous methods. In the proposed method, forward and reverse currents are applied to obtain the same increment and decrement of potential, respectively. The average of the forward and reverse currents is used to obtain the mean corrosion current of the two electrodes. The errors corresponding to forward and reverse currents compensate one another, and the corrosion rate calculated from the average of the two has less net error than that calculated by Barnartt's method in which only the forward current is used. The proposed method gives relatively low error independent of the corrosion potential difference between the two electrodes and overcomes the inherent weakness of Marsh's method in which errors vary with the corrosion potential difference.