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Effect of Surface Concentration of Lu on Oxygen Permeation of Polycrystalline Alumina at High Temperatures
Author(s) -
Wada Masashi,
Matsudaira Tsuneaki,
Kato Takeharu,
Kitaoka Satoshi
Publication year - 2013
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.12316
Subject(s) - permeation , oxygen , oxygen permeability , diffusion , coating , chemistry , crystallite , materials science , aluminium , limiting oxygen concentration , chemical engineering , permeability (electromagnetism) , wafer , analytical chemistry (journal) , membrane , chromatography , metallurgy , nanotechnology , thermodynamics , organic chemistry , biochemistry , physics , engineering
The effect of Lu surface concentration on oxygen permeation in polycrystalline α‐alumina wafers was determined at 1773 K under limited oxygen potential gradients (ΔPO 2), where the two surfaces of the wafer were deliberately subjected to different oxygen partial pressures [PO 2(I) ≪ PO 2(II)]. When oxygen permeation occurred mainly by oxygen GB diffusion under a ΔPO 2generated by a combination of lowPO 2values, the Lu‐coating on thePO 2(I) [PO 2(II)] surface decreased [increased] the oxygen permeability constants. When ΔPO 2was the result of a combination of highPO 2values, where oxygen permeation proceeded mainly by aluminum GB diffusion, the oxygen permeability constants were decreased only by the Lu‐coating on thePO 2(I) surface. The analysis of mass transfer parameters, such as the chemical potentials, GB diffusion coefficients, and fluxes of aluminum and oxygen in the wafers, suggested that ambient oxygen molecules were effectively attracted toward Lu‐coated surfaces exposed to low‐PO 2environments, leading to a change in oxygen permeability.