DETECTION OF CORROSION BY ANALYSIS OF ELECTROCHEMICAL NOISE

Abstract

Stochastic fluctuations of the corrosion potential and the current generated by corrosion reactions are known as electrochemical noise. These fluctuations can be measured in freely corroding systems, therefore the characteristics of electrochemical noise are influenced only by the type and rate of corrosion. The classical spectral analysis of electrochemical noise in the frequency domain achieve good correlation to corrosion rate and type; however, the chaotic nature of corrosion processes requires different mathematical treatment. In this paper self-similarity and fractal dimensions of electrochemical noise are examined in order to explain its mechanism and improve the corrosion monitoring system. Capacity and correlation fractal dimensions of voltage and current-noise, measured on various metals, are calculated and compared to the results of the classical spectral analysis. Relations between different rates and types of corrosion (passivation, local, uniform) and the fractal characteristics of electrochemical noise are established. The analysis of spontaneous electrochemical voltage and current fluctuations is confirmed as a rich source of information in corrosion processes.