Evaluation of Corrosion Inhibitors by Electrochemical Noise Analysis

The corrosion potential fluctuations of aluminum alloy AA 6351 electrodes in 0.5 M chloride solutions were recorded both in the absence and in the presence of the following inhibitors: 2‐mercaptopyrimidine, sodium molybdate, and sodium nitrate. The corresponding spectral density plots, calculated over a wide frequency range, are discussed in order to evaluate the possibility of finding the mechanism of action of the additives, by analyzing the electrochemical noise. As a reference, the polarization curves of the alloy in the various solutions are reported.