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Partial Reduction of NiAl2O4 - Mechanism and the Influence of Doping

Published online by Cambridge University Press:  21 February 2011

Z. Zhang ,
E. Üstündag  and
S.L. Sass
Z. Zhang
Affiliation:
Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853
E. Üstündag
Affiliation:
Los Alamos National Lab., Ceramic Sci. & Tech. Group, M.S. K762, Los Alamos, NM 87545
S.L. Sass
Affiliation:
Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853
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Abstract

Metal-ceramic microstructures were formed in situ by partial reduction of the spinel compound NiAl2O4. At 1300°C the reduction reaction passed through an intermediate stage involving the formation of Ni and metastable “defect spinel” phases, before the appearance of the equilibrium phases, Ni + α-Al2O3. At 1100°C, depending on the reduction time, the products of the reduction reaction were Ni and the metastable “defect spinel” for less than 24 hours; Ni + θ-Αl2Ο3 for 24-48 hours; and Ni + GI-AI2O3 for 144-168 hours. The effects of dopants, such as Cr2O3, MgO, TiO2 and Y2O3, on the reduction mechanism and kinetics were examined and shown, in the case of TiO2, to have a controlling influence. A reduction reaction mechanism is proposed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 398: Symposium C – Thermodynamics and Kinetics of Phase Transformations , 1995 , 489
Copyright
Copyright © Materials Research Society 1998

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References

REFERENCES

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