A spatiotemporal model of interactions among metastable pits and the transition to pitting corrosion

A spatiotemporal model of metastable pitting at a homogeneous metal surface under potentiostatic conditions is presented. The model accounts for local changes adjacent to metastable pits and their effect on the nucleation of subsequent events. The local changes considered include concentration, potential drop and oxide film damage. The interactions among events can lead to the formation of clusters of metastable pits and to an explosive growth in the total number of pits. Effects of metastable pit generation rate, convective mass transport (e.g., solution stirring), solution conductivity and ohmic potential drop in solution on formation of corrosion patterns at the surface are presented. The effect of the presence of a stable pit is also considered.