Chemical composition and semiconducting behaviour of stainless steel passive films in contact with artificial seawater

Passive films formed on AISI 316L stainless steer in nitric acid solution and placed in contact with artificial seawater were investigated by Auger and XPS analyses, capacitance measurements and photoelectrochemical measurements. The evolution of the corrosion potential is explained based on the electronic behaviour of the inner and outer layers of the film above and below the flatband potential. The correlation between the electronic structure of the film and the tendency to localised corrosion is also discussed, suggesting that the film breakdown involves the ionization of localized states and/or surface states situated deep in the bandgap. (C) 1998 Elsevier Science Ltd. All rights reserved.