Breakdown of passivity and localized corrosion: Theoretical concepts and fundamental experimental results

This review summarizes the different ideas to breakdown of passivity and localized corrosion. On the basis of experimental results a critical discussion of the main mechanisms is presented. The subdivision into different stages of growth of corrosion pits tries to reduce the controversial opinions and to avoid misunderstandings in the literature of the past. As the various systems are complex and in several aspects quite different not only one unique mechanism will be effective for all cases. However, there are some few basic processes which control localized corrosion of most passive metals.