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Formation of silicide/spinel ceramic composites via Al- and Mg-based thermitic combustion synthesis

Formation of silicide/spinel ceramic composites via Al- and Mg-based thermitic combustion synthesis Formation of MoSi2–spinel (MgAl2O4) composites with a wide composition range of MoSi2/MgAl2O4 = 1.0–5.0 was studied by thermitic combustion synthesis in the mode of self-propagating high-temperature synthesis (SHS). Two combustion systems conducted contained not only Mo and Si powders, but also different thermite reagents of 7/12 MoO3 + Mg + 1/2 Al and MoO3 + 2 Al in the presence of Al2O3 and MgO, respectively. In agreement with the calculated adiabatic reaction temperatures, measured combustion temperature and flame-front velocity decreased with increasing MoSi2/MgAl2O4 ratio. The XRD analysis indicated that MoSi2 was formed in α and/or β phases and that β-MoSi2 dominated as the combustion temperature above 1550 °C but α-MoSi2 prevailed as the temperature below 1350 °C. Spinel MgAl2O4 was produced through the dissolution of thermite-produced Al2O3 and MgO into pre-added MgO and Al2O3, respectively. The fracture surface morphology of the products exhibited that granular MoSi2 particles were distributed over or embedded partially into the dense and connecting substrate formed by MgAl2O4. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of the Australian Ceramic Society Springer Journals

Formation of silicide/spinel ceramic composites via Al- and Mg-based thermitic combustion synthesis

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Publisher
Springer Journals
Copyright
Copyright © The Author(s) under exclusive licence to Australian Ceramic Society 2022
ISSN
2510-1560
eISSN
2510-1579
DOI
10.1007/s41779-022-00738-x
Publisher site
See Article on Publisher Site

Abstract

Formation of MoSi2–spinel (MgAl2O4) composites with a wide composition range of MoSi2/MgAl2O4 = 1.0–5.0 was studied by thermitic combustion synthesis in the mode of self-propagating high-temperature synthesis (SHS). Two combustion systems conducted contained not only Mo and Si powders, but also different thermite reagents of 7/12 MoO3 + Mg + 1/2 Al and MoO3 + 2 Al in the presence of Al2O3 and MgO, respectively. In agreement with the calculated adiabatic reaction temperatures, measured combustion temperature and flame-front velocity decreased with increasing MoSi2/MgAl2O4 ratio. The XRD analysis indicated that MoSi2 was formed in α and/or β phases and that β-MoSi2 dominated as the combustion temperature above 1550 °C but α-MoSi2 prevailed as the temperature below 1350 °C. Spinel MgAl2O4 was produced through the dissolution of thermite-produced Al2O3 and MgO into pre-added MgO and Al2O3, respectively. The fracture surface morphology of the products exhibited that granular MoSi2 particles were distributed over or embedded partially into the dense and connecting substrate formed by MgAl2O4.

Journal

Journal of the Australian Ceramic SocietySpringer Journals

Published: Apr 12, 2022

Keywords: Molybdenum disilicide MoSi2; Spinel MgAl2O4; Composite materials; Thermitic combustion synthesis; Metallothermic reduction

References