Formation of MgO-B{sub 4}C composite via a thermite-based combustion reaction
- Univ. of California, Davis, CA (United States). Dept. of Chemical Engineering and Materials Science
The combustion synthesis of MgO-B{sub 4}C composites was investigated by coupling a highly exothermic Mg-B{sub 2}O{sub 3} thermite reaction with a weakly exothermic B{sub 4}C formation reaction. Unlike the case of using Al as the reducing agent, the interaction between Mg and B{sub 2}O{sub 3} depends on the surrounding inert gas pressure due to the high vapor pressure of Mg. The interaction changes from one involving predominantly gaseous Mg and liquid B{sub 2}O{sub 3} to one involving liquid Mg and liquid B{sub 2}O{sub 3} as the pressure increases. At low inert gas pressure, the initiation temperature is found to be just below the melting point of Mg (650 C). As the inert gas pressure increases, the vaporization loss of reactants is reduced, and this in turn increases the combustion temperature, which promotes greater grain growth of the product phases, MgO and B{sub 4}C. The particle size of B{sub 4}C increased from about 0.2 to 5 {mu}m as the pressure changed from 1 to 30 atm.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 79789
- Journal Information:
- Journal of the American Ceramic Society, Journal Name: Journal of the American Ceramic Society Journal Issue: 3 Vol. 78; ISSN 0002-7820; ISSN JACTAW
- Country of Publication:
- United States
- Language:
- English
Similar Records
Self-propagating high-temperature synthesis of oxide-B sub 4 C composites
The feasibility of synthesis of B[sub 4]C fiber-MgO composites by combustion