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Magnesia-spinel microcomposites

A model system of fully dense high purity MgO, incorporating micron size spinel, was prepared by hot-pressing. Spinel powder was obtained from two sources: (i) 0.5 micron alumina powder was incorporated into MgO by in-situ reaction, and (ii) preformed 3 micron spinel powder. The thermal expansion mi...

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Bibliographic Details
Published in:Journal of the European Ceramic Society 2004-09, Vol.24 (10-11), p.3119-3128
Main Authors: AKSEL, Cemail, WARREN, Paul D, RILEY, Frank L
Format: Article
Language:English
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Summary:A model system of fully dense high purity MgO, incorporating micron size spinel, was prepared by hot-pressing. Spinel powder was obtained from two sources: (i) 0.5 micron alumina powder was incorporated into MgO by in-situ reaction, and (ii) preformed 3 micron spinel powder. The thermal expansion mismatch between MgO and spinel particles led to the intergranular and intragranular crack development, with consequent loss of strength and Young's modulus. The extent of interlinking of the microcracking was determined to be a function of spinel particle size and volume fraction; the reasons for this were examined. The mechanical properties and R"" parameter values of the microcomposites are reported. The thermal shock resistance of in-situ formed 20% 0.5 micron and preformed 30% 3 micron spinel composites, in terms of the R"" parameter, was predicted to be 4 to about 5 times better than that of pure MgO, respectively. 60 refs.
ISSN:0955-2219
1873-619X
DOI:10.1016/j.jeurceramsoc.2003.10.036