Passivity and localized corrosion

Abstract

In many circumstances, alloys are covered by a thin layer of insoluble (or relatively insoluble) oxide or other corrosion product, which isolates the metal from the corrosive environment and hence reduces the rate of corrosion. In this state, the metal is described as being passive. Unfortunately, this protective passive film may be susceptible to damage and breakdown as a result of aggressive species in the solution coupled with the local pH changes in the solution. This can then lead to the phenomenon of localized corrosion, which can cause rapid local attack. © 2010 Copyright © 2010 Elsevier B.V. All rights reserved.