Effect of Potential on Crevice Corrosion Kinetics of Alloy 22

Abstract Alloy 22 (UNS N06022) is a Ni-Cr-Mo alloy, highly resistant to localized corrosion. It has a wide range of industrial applications. Because of its versatility, Alloy 22 has been proposed as a corrosion-resistant barrier for high-level nuclear waste containers. Crevice corrosion is expected to occur in hot chloride solutions if the corrosion potential is equal to or greater than the crevice corrosion repassivation potential. For less-aggressive environments, transpassive dissolution limits the alloy performance at high potentials. The goal of the present work was to establish the effect of potential on the kinetics of chloride-induced crevice corrosion of Alloy 22 at 90°C. Electrochemical tests carried out included cyclic potentiody-namic polarization (CPP) curves, polarizations at constant applied potentials followed by repassivation, and electrochemical impedance spectroscopy (EIS) measurements at anodic applied potentials. The attack profiles were measured using a roughness checker. Crevice cor...