Crevice Corrosion Study on Alloy 22 by E

Ni-Cr-Mo alloys show a remarkable corrosion resistance in a wide variety of environments, making them suitable materials for engineered barriers in nuclear repositories. However, these alloys, particularly alloy 22, can be susceptible to crevice corrosion under aggressive conditions characterized by high chloride concentration, low pH, and elevated temperatures. This study aimed to assess the application of the electrochemical noise technique for investigating crevice corrosion in alloy 22. Potential and current noise data were collected from alloy 22 samples with and without crevice formers across various corrosive environments. The records were analyzed in both the time domain and through statistical parameters to derive reliable indicators for detecting crevice corrosion. Results demonstrated that during crevice corrosion, there was a distinct drop in potential augmented by a rise in current, while no significant changes were observed in instances without crevice corrosion. Furthermore, analysis of the current noise standard deviation evidenced high sensitivity to environmental corrosiveness, including temperature and solution composition, as well as crevice corrosion occurrence. Ultimately, this study identifies voltage drop and concurrent current increase as critical parameters gained through the electrochemical noise technique for monitoring alloy 22's crevice corrosion, complemented by standard deviation analysis of current records.