Repassivated

Repassivated refers to a metal surface that has regained its passive, protective film after being disrupted. In corrosion science, many metals such as stainless steels, titanium, and aluminum rely on a thin oxide layer to reduce further dissolution in oxidizing environments. When this passive film is damaged by mechanical wear, fretting, pitting, or other corrosive processes, the exposed metal can corrode locally until the film reforms. Repassivation is the process by which the protective film re-forms, restoring passivity and slowing ongoing corrosion. The rate and extent of repassivation depend on alloy composition and microstructure, temperature, pH, and the chemical milieu, particularly the presence of oxidants and aggressive ions such as chlorides.

In electrochemical terms, repassivation can be described by the repassivation potential and the repassivation current, which characterize how readily the film re-forms after breakdown. If repassivation is slow or inhibited, pits or crevices may advance; if repassivation is rapid, the corrosion process is more effectively halted. Surface roughness, contamination, and prior heat-treatment can also influence repassivation behavior.

Practically, repassivation can be promoted by surface treatments that enhance the oxide film or remove inhibitory contaminants. Passivation processes for stainless steels often use oxidizing solutions to increase the protective chromium-rich oxide content. Materials selection and environmental control aim to favor reliable repassivation, reducing the risk of localized corrosion in service.