Oxide Film Growth Kinetics on Metals and Alloys: I. Physical Model

Abstract

Oxide layers play a crucial role in the corrosion resistance of metals and alloys and the growth kinetics of these films is of major interest. To express the oxide growth kinetics, three main models are available: the Cabrera-Mott model, the Fehlner-Mott model and the Point Defect Model (PDM). These models are reviewed in the first part of the paper. Among these models, the PDM is the only one that takes into account the interfacial potential drops during the oxide growth. However, in this model: (i) no parameters relative to the substrate alloy are taken into account, and (ii) the growth is limited by the flow of oxygen vacancies through the film (transport via both cation interstitial and vacancy positions are not taken into account). Here we present a “generalized model” for the kinetics of oxide growth in which the evolution of the interfacial potential drops during oxide growth is included, as well as the variation of the electric field in the oxide during film growth. This new model allows us to describe the growth of oxide films on alloys under non-steady-state conditions. The link between oxide growth and cation release into the solution is also included.