AbstractIn order to evaluate the localized corrosion susceptibility of carbon steel in water containing bentonite, the critical pH for depassivation, pHd, the critical potential for crevice corrosion, ERCREV, and the free corrosion potential, Esp, were determined in simulated aqueous solutions of 1 to 100 mmol/L [HCO3- - CO32−], 1 to 1000 mmo!/L [NaCI], and pH of 7 to 12. The Following results were obtained; 1)ER, CREV. increases with increasing [HCO3− CO32−] concentration. The relationship can be described as a function of the ratio of [CI-I HCO3−- CO32−], 2)The Esp increases with increasing pH in the passive region, and 3)ThepHd shows [HCO3− - CO32−] concentration dependency. This paper also discusses the relationship between critical initiation potential for crevice corrosion of carbon steel, [CI-], and [HCO3− CO32−] anion. The crevice corrosion that occurs on passivated metals and alloys is characterized by determinable critical initiation potential that can be induced in a potential range nobler than its critical potential.
Passive films, surface structure and stress corrosion and crevice corrosion susceptibility