Point defect model for the corrosion of steels in supercritical water: Part I, film growth kinetics

A Point Defect Model has been developed to describe theoretically the corrosion of metals and alloys in supercritical aqueous systems. The model, SCW_PDM, accounts for the kinetics of growth of the barrier layer and the total scale thickness and for the oft-reported growth of the barrier layer with the barrier/outer layer interface remaining at the location of the original metal surface. The barrier layer grows into the metal via the production of oxygen vacancies at the metal/barrier layer interface and their annihilation at the barrier layer/outer layer interface. The proposed atomic-level rate laws for the scale growth and oxidation weight gains, not only can act as deterministic equations for extracting values of some fundamental parameters in SCW_PDM, but also can be employed to describe the oxidation kinetics of steels directly and successfully.