Surface Reactions of Steel in Dilute Cr[sup 51]O[sub 4][sup −−] Solutions: Applications to Passivity

Abstract

Interactions between a steel surface and anions containing chromium‐ VI were studied by radiotracer methods supplemented by contact potential measurements. In chromate solutions of high enough concentration, the behavior of steel is analogous to that of chromium, i.e., it is passive and is found to remove a definite number of chromate ions from solution. The relationships among solution composition, radioactivity retained on the passive surface, and contact potential indicate that at least a portion of the activity is present as adsorbed chromate ion. In dilute solutions, where corrosion occurs, radioactive chromium in excess of that associated with a passive surface appears on both anodic and cathodic areas.