A model of passivated metal interactions with electrolyte solutions

A model of processes at the interface between an electrolyte and a passivating oxide layer on a metal exposed to anodic dissolution is considered. The consideration is based on the well-known mechanism of passivating layer stability suggested by Vetter. The fundamental character of this mechanism is analyzed in comparison with other models. Equations for determining the potentials of equilibrium exchange of metal and oxygen ions between the layer and the electrolyte are derived, the relation between the corresponding exchange currents is found, and the conditions for thermodynamic equilibrium are formulated. The obtained anodic dissolution current dependences on solution pH, water concentration, anode potential, and other parameters closely agree with experiment.