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Hot corrosion of alumina

Published online by Cambridge University Press:  31 January 2011

M.G. Lawson ,
F.S. Pettit  and
J.R. Blachere
M.G. Lawson
Affiliation:
Department of Materials Science and Engineering, University of Pittsburgh, 848 Benedum Hall, Pittsburgh, Pennsylvania 15261
F.S. Pettit
Affiliation:
Department of Materials Science and Engineering, University of Pittsburgh, 848 Benedum Hall, Pittsburgh, Pennsylvania 15261
J.R. Blachere
Affiliation:
Department of Materials Science and Engineering, University of Pittsburgh, 848 Benedum Hall, Pittsburgh, Pennsylvania 15261
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Abstract

The hot corrosion of single crystal and polycrystalline aluminas has been investigated in SO2–SO3–O2 environments and in the presence of molten Na2SO4-based deposits at temperatures of 700 and 1000 °C. The effect of microstructure and impurities on the corrosion has been emphasized. Weight changes and wetting angles were determined, and the evolution of the morphology of the exposed substrates and the reaction products was investigated in detail. The corrosion was small under the conditions of this study and generally increased with the impurity content of the polycrystalline aluminas. Based on the experimental results, particularly those obtained by electron microscopy and microanalysis using the SEM/EPMA (scanning electron microscope–electron probe microanalyzer), mechanisms are proposed for the corrosion of polycrystalline aluminas which emphasize the role of the silicate impurities and the synergy of their corrosion with that of the alumina grains. As a result, the alumina grains were dissolved by acidic fluxing under the acidic and the basic experimental conditions.

Type
Articles
Information
Journal of Materials Research , Volume 8 , Issue 8 , August 1993 , pp. 1964 - 1971
Copyright
Copyright © Materials Research Society 1993

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References

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