Repassivation kinetics of AISI 304 stainless steel in 50℃, 0.1 M NaCl solution was examined by the scratching electrode method, and the high field ion conduction model was modified to explain more clearly the repassivation kinetics. Also the effects of Cr on the repassivation kinetics was investigated.
The high field ion conduction model failed to explain the initial stage of repassivation. A modified high field ion conduction model, which was derived with the assumption that the potential drops in the passive film and the film-electrolyte interface are both variables, successfuly explained the overall repassivation behavior.
The latter part of the current transient curve of modified high field ion conduction model was used, which is more effective in comparing the repassivation kinetics of Fe-18Cr and Fe-25Cr alloys.
For the same current density, Fe-25Cr had lower value of Q than that of Fe-18Cr alloy, which means that the passive film of the Fe-25Cr alloy is thinner and more stable than that of Fe-18Cr alloy.
