The hydrogen-enhanced effects of chloride ions on the passivity of type 304 stainless steel
By Yang, Q & Luo, J.L
Published in Electrochimica Acta
2000
Abstract
The effects of the presence of hydrogen in type 304 stainless steel and chloride ions in a solution on the anodic current density and breakdown potential were investigated. It is found that both hydrogen and chloride ions increase the anodic current density of the stainless steel in the passive range. The effect is not simply arithmetically additive; instead there is a synergistic effect of hydrogen and chloride ions on the anodic current density. Hydrogen also has an enhanced effect of chloride ions on a decrease in breakdown potential. The critical chloride concentration for film breakdown decreases with hydrogen-charging current density and the critical hydrogen-charging current density for the film breakdown decreases with chloride ion concentration. The passive films on both uncharged and charged specimens exhibit n-type semiconductivity. Hydrogen increases the donor concentration while chloride ions have no such effect. The effects of hydrogen and chloride ions on the passivity are explained with an electronic model.