Program to Develop Thermite Reactions to Produce Refractory Borides and Carbides

摘要

The objective of this research program is to determine the potential of the thermite reaction for producing high density refractory boride shapes by melt casting. Emphasis is being placed on developing experimental compositions, processing procedures and ignition conditions which will maximize the temperature obtained from the thermite reaction and affect the melting and separation of the reaction products. Phase I of the research effort evaluated the effects of three process parameters: particle size, powder compaction and temperature of reactants at ignition. The products of ignition were characterized using electron microscopy and X-ray diffraction to determine the extent of the reaction towards completion and the compounds produced by the ignition. Three systems were investigated: TiO2 + Al; B2O3 + Al; and TiO2 + B2O3 + Al. A TiB2 + alpha Al2O3 product was obtained by using the thermite reaction to reduce TiO2 + B2O3. Samples containing small particle size aluminum in a loose powder ignited at a lower temperature than compacted samples containing coarse aluminum. Samples ignited in a preheated furnace showed a more complete reaction than those ignited at room temperature.