Void Formation in Growing Oxide Scales with Schottky Defects and p-type conduction

A quantitative elucidation of the void formation in a growing scale with Schottky defects and p-type conductior during high temperature oxidation of metals. The evaluation or the divergence of ionic fluxes indicates that (1) Voids form in the scale preferentially in the vicinity of the metal/scale interface, (2) The volume of voids increases in a parabolic manner, (3) The volume fraction of voids and the scale is independent of time. The comparison between the calculation and the experimentally observed scale microstructure of NiO and CoO confirmed well the validity of the prediction.