Oxygen exchange and transport properties of yttria-stabilized zirconia coated with LaCrO3

Abstract

The oxygen permeation flux through YSZ (Yttria-Stabilized Zirconia) in reducing Po (2) is mostly controlled by the surface-exchange kinetics in spite of very high temperature [1]. In order to study the kinetics, the YSZ surface was coated with LaCrO3 on feed side, permeate side, or two sides, and the oxygen fluxes were measured under controlled Po (2) gradient generated by different CO/CO2 mixtures (permeate side: similar to 3 x 10(-12) atm, feed side: 2 x 10(-10)similar to 2 x 10(-8) atm) at 1600 degrees C. The oxygen flux was determined by measuring the change in CO2 content of the permeate-side gas. When both feed and permeate surfaces were coated, the oxygen flux increased by similar to 6 times. For either permeate- or feed-side coating, the increases were similar to 4 times and similar to 1.5 times, respectively. A model was proposed in order to estimate the surface-exchange coefficient ((K) over bar) of feed and permeate side with or without coating.