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Reaction Synthesis of MoSi2-Al2O3 Composite Using MoO3, Al and Si Powders

Published online by Cambridge University Press:  15 February 2011

Seetharama C. Deevi  and
Sarojini Deevi
Seetharama C. Deevi
Affiliation:
Research Center, Philip Morris, USA, Richmond, VA 23234
Sarojini Deevi
Affiliation:
CeraMat Technologies, Oak Ridge, TN 37830
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Abstract

In-situ synthesis of a composite of MoSi2-Al2O3 was carried out by reacting a thermite mixture consisting of MoO3, Al, and Si powders. The reaction was found to be extremely fast and violent, and a diluent was required to moderate the reaction. Thermal behavior of the thermite mixture was studied using DTA at different heating rates, and DTA was interrupted at different temperatures to determine the reaction mechanism. X-ray characterization of the products obtained at different temperatures reveals that the mechanism consists of a reduction of MoO3 by Al to MoO2 followed by a simultaneous oxidation of Al to Al2O3 and synthesis reaction between reduced Mo and Si to form MoSi2. The rate determining step is found to be reduction of MoO2 by Al and oxidation of Al to Al2O3. The thermite reaction was moderated by adding Mo and Si to the mixture of MoO3, Al, and Si such that the ratio of MoSi2 to the thermite was in the range of 60:40 to 90:10.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 365: Symposium M – Ceramic Matrix Composites–Advanced High-Temperature Structural Materials , 1994 , 73
Copyright
Copyright © Materials Research Society 1995

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