On the interpretation of the electrochemical noise data for coatings

Comparison between various methods of the data analysis used in the electro chemical noise measurements on coated electrodes, as well as the correlatio n of the noise data with results of impedance measurements, were pursued in this work. For the analysis of the noise data, the following methods were applied: stochastic analysis, maximum entropy method, fast Fourier transfor mation, and special analysis of the autocorrelation function as well as the calculation of the Hurst and Lyapunov exponents. It was shown that the sto chastic analysis suffices for the determination of the noise resistance and that the calculation of the Hurst and Lyapunov exponents allows the extrac tion of the mechanistic information about the corrosion and protection proc esses in such systems. In addition, a trend correlation, but not the numeri cal correlation, was found between the noise resistance and the polarizatio n resistance from the impedance measurements. (C) 2000 Elsevier Science S.A . All rights reserved.