Papers by Keyword: Chemical Potential Distribution

Abstract: Voids are frequently generated and dispersed in oxide scales formed in high temperature oxidation of metals. The divergence of ionic flux may play an important role in the void formation in a growing scale. Kinetic equations were derived for describing chemical potential distribution, ionic fluxes and their divergence in the scale. The divergence was found to be the measure of void formation. Defect chemistry in scales is directly related to the sign of divergence and gives an indication of the void formation behavior. The quantitative estimation on the void formation was successfully applied to a growing magnetite scale in high temperature oxidation of iron at 823 K.

Abstract: Estimation of void formation in oxide scale is important for predicting exfoliation of the oxide scale. Void formation in magnetite scale formed on iron at 823 K has been elucidated by chemical potential distribution, flux of oxide ion and its divergence. This calculation also estimates a effective diffusion coefficient, which includes both lattice diffusion and grain boundary diffusion in magnetite scale. The resulting effective diffusion coefficients give the quantitative elucidation of the morphology of the magnetite scale. The divergence of oxide ion explains well a position and an amount of void in magnetite scale.