ELECTROCHEMICAL NOISE FOR THE QUANTIFICATION OF STAINLESS STEEL RESISTANCES TO PITTING CORROSION

摘要

This study aims at setting up a reliable test to quantify stainless steel resistances to pitting corrosion with electrochemical noise measurements. Free potentials of a 304 stainless steel electrode immersed in NaCl + FeCl_3 solutions of two different concentrations were recorded for 24 hours. The number of pits observed after immersion was correlated to that of transients on potential signals. Since criterion to transient selection was open to criticism, other mathematical parameters (some of which were defined for the characterisation of chaotic systems) were then investigated. It was found that the decreasing slope of the autocorrelation function of the potential signals was also correlated to transient frequency and both followed a decreasing exponential law versus immersion time during the first 13 hours of test.