Electrochemical noise analysis: detection of electrode asymmetry

Abstract One major application of electrochemical noise (EN) analysis for corrosion studies is the estimation of corrosion rate via impedance measurement. The measurement involves coupling two electrodes, whereupon the associated EN is measured and the noise resistance and the spectral noise impedance are computed. However, the two electrodes are required to be “nominally identical” (i.e. symmetrical) for the noise resistance and spectral impedance techniques to be valid. This paper proposes that the correlation between the measured potential and the current noise can be used to detect an asymmetric electrode pair and thus provides a necessary but not sufficient test for electrode symmetry. The potential/current coefficient of correlation is derived based on an equivalent circuit to demonstrate the concept and experimental data is presented to support the theory.