Thermodynamic analysis for the combustion synthesis of SiC-B{sub 4}C composites
- NYMA, Inc., Cleveland, OH (United States). Lewis Research Center Group
A significant amount of attention has been focused recently on the development of new structural materials for aerospace, nuclear, armor and energy related applications. These materials should have high melting points, low density, good strength and toughness, and good oxidation and thermal shock resistance. Schwetz et al. have indicated that SiC-B{sub 4}C composite materials would have a combination of desirable mechanical and thermal properties. These include the strength, oxidation and thermal shock resistance of silicon carbide combined with the low density, hardness and wear resistance of boron carbide. Self-propagating high-temperature synthesis (SHS) or combustion synthesis (CS) has been used to produce a variety of refractory borides, carbides, nitrides, and silicides containing ceramics and composite materials. The underlying basis for this synthesis is the ability of highly exothermic reactions to sustain themselves in the form of a reaction or combustion wave. The rate of combustion wave propagation can be very rapid ({approximately}25 cm/s) and can reach temperatures as high as 5,000 K. In the CS process, reactions with extremely large thermal gradients ({approximately}10{sup 5} K/cm) can be obtained under adiabatic conditions. There are two basic modes of reaction used in combustion synthesis. One spreads mainly by propagation of combustion waves through the reactants which are heated at one end by thermal or laser energy and the reaction self-propagates. Another approach involves the heating of the entire specimen to a temperature at which the reaction becomes spontaneous and takes place simultaneously in the whole specimen.
- OSTI ID:
- 215369
- Journal Information:
- Scripta Materialia, Vol. 34, Issue 6; Other Information: PBD: 15 Mar 1996
- Country of Publication:
- United States
- Language:
- English
Similar Records
Preparation of MoSi[sub 2]/SiC composites from elemental powders by reactive co-synthesis
Novel manufacturing processing route for forming high-density ceramic armor materials: Phase 1 -- SBIR. Final report, 25 April 1991--11 December 1991