Progress towards a unified model of corrosion with porous oxides

Abstract

The oxide that develops on the surface of the metals like zinc is usually porous. Any further oxidation of the metal can happen only if the electrolyte percolates through the oxide and comes in contact with the metal and also if there is a provision for the cathodic reaction to happen elsewhere. The oxide layer thus changes the conditions of corrosion of a metal surface. Three different electrochemical models for atmospheric corrosion of a metal under an aerosol solution are described. The models described are part of the holistic approach to model corrosion where multiple scales of time and space occur due to the various physical phenomena. When coupled with the macroscopic holistic model of production, transport, and deposition of aerosols these models are expected to comprehensively predict the corrosion rates and state of surfaces over a wide range of conditions. Some representative results of the models are presented and important assumptions underlying the models are stated. Also conditions leading to passivation are identified by all the three models. Show more