Cellular automaton modeling on the corrosion/oxidation mechanism of steel in liquid metal environment

Abstract

Corrosion and oxidation of structure material in liquid lead alloys, which have been strongly associated with the nuclear industry, are specific but important areas of corrosion in liquid environments. In high temperature liquid metal environment, the corrosion rate of stainless steels is controlled by the solid diffusion of iron along grain boundaries in the oxide layer and a duplex oxide layer is formed with the inner layer growing by infiltration of corrosive solution along oxide micropores and the outer layer growing by the diffusion of metal ions. To interpret the role of diffusion and reaction process in the process of oxidation, a cellular automaton model, which combines the surface growth and internal oxidation, was created to explain the oxidation mechanism of steels in high temperature corrosive liquid metal environment. In this model, three main processes, which include the corrosion of the substrate, the diffusion of iron species across the oxide layer and precipitation of iron on the oxide layer, are simulated. The diffusion process is simulated by random walk model. Mapping between present model and experimental data has been created. The gross features concerning the evolution of the involved process were explored.