Combustion Synthesis of Silicon Carbide for Advanced Ceramics

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Fine, ultrapure particles are desirable starting materials for production of high-performance advanced ceramic products. AeroChem has previously demonstrated the combustion synthesis of silicon nitride products from the reactants silane and hydrazine. In this program, combustion synthesis of silicon carbide will be investigated. The flav-flame burner to be used is the same as used in conventional hydrocarbon-air flame studies, and the flame appearance is quite similar. Two major differences are that no oxygen is used in the flame synthesis of silicon carbide (or nitride) and the major product is a powder which must be separated from the coflowing product gases. In the current study, AeroChem will investigate the preparation of silicon carbide via reaction of silane with acetylene on this flat-flame burner. The major issue here is the formation of a pure silicon carbide product without the presence of either silicon or carbon contaminants. Thermodynamic calculations indicate that this can be achieved by operation in a narrow reactant ratio range near stoichiometric, where the yield of silicon carbide is calculated to be 100% based on the silane feed. Experiments and further theoretical analysis will be pursued to confirm that a high-purity SiC product can indeed be produced at close to 100% yield. High quality silicon carbide powders have a large potential market in the preparation of advanced ceramic materials via sintering or hot pressing. Present progress in production of advanced ceramics is currently limited by the unavailability of a US-made high quality powder. In addition, the technology and understanding of combustion synthesis which will be developed in this program will be applicable to combustion synthesis of a wide variety of other desirable materials.