Measures for the detection of localized corrosion with electrochemical noise

A simulation of electrochemical noise data has been produced using a shot noise model, and this has been used to examine the properties of several of the parameters that have been proposed as indicative of the type of corrosion. The model produces an electrochemical noise impedance that is the same as the expected impedance, despite that fact that the model does not incorporate a charge transfer resistance term, supporting the observed and predicted equivalence between noise impedance and conventional electrochemical impedance. Of the various parameters that have been examined, the characteristic charge and characteristic frequency are proposed as useful general indicators of the nature of the corrosion process. Skew and kurtosis statistics may be indicative of the localized corrosion, but the results will be system dependent, particularly with respect to whether uni- or bidirectional transients are observed, and whether the current measuring electrodes are symmetrical or asymmetrical. (C) 2001 Elsevier Science Ltd. All rights reserved.