CHAOTIC ANALYSIS OF ELECTROCHEMICAL NOISE MEASURED ON STAINLESS-STEEL

Corrosion reactions spontaneously generate fluctuations of the corrosion potential and corrosion current, known as electrochemical noise. In certain cases good correlation between electrochemical noise and corrosion rates and types can be achieved by means of spectral analysis. However, due to the chaotic nature of corrosion procsses, a special kind of mathematical treatment may be needed. In this paper, the correlation dimension and the maximum Lyapunov exponent of electrochemical noise measured on stainless steel have been examined in order to characterize the mechanism of this noise. The relationship between the different types of corrosion and the chaotic characteristics of electrochemical noise have been also established. It has been shown that the general corrosion rate has no influence on the fractal dimensions of the noise. It is concluded that localized corrosion is generated by a deterministic chaotic process, whereas uniform corrosion is a random process.