Growth of oxide films on metal surfaces: transition from parabolic to linear kinetics

The transition from the parabolic to linear regime of the oxide-film growth is connected with formation of cracks or pores in the oxide. We present two simple phenomenological kinetic models illustrating an interplay between oxidation, creation of cracks, and structure properties of the metal. If formation of cracks is connected with grains (model 1), the transition from the parabolic to linear kinetics is shown to be smooth provided that the grain-size distribution is wide. For narrow distributions, the kinetics exhibits a few successive transitions on the way to the linear regime. If formation of cracks is connected with ‘active centres’ (model 2), the transition from the parabolic to linear growth is smooth as well. The oxidation kinetics in this case is very close to that predicted by the well-known Haycock model.