Materials Research Bulletin, Vol.35, No.6, 945-954, 2000
Characteristics of Al2O3-SiC composite powder prepared by the self-propagating high-temperature synthesis process and its sintering behavior
Al2O3-SiC composite powder was prepared by the self-propagating high-temperature synthesis (SHS) process, using SiO2, Al, and C powders as raw materials. The effects of keeping the SiO2:Al molar ratio fixed at 3:4 while varying the relative carbon amount, compaction pressure, initial temperature of reactants, and combustion process on the products were studied. SHS of the SIO2/Al/C system required preheating above 400 degrees C, because of the low combustion temperature. It was found that, as a result of the combustion reaction, the purity of the final product was better than that of the reactants. The optimum molar ratio of SIO,:AI:C in the system was found to be 3.4:6. The free carbon was removed by roasting at 650 degrees C for 30 min. Pressureless sintering was found to be very effective in hindering the disintegration of the specimen with a Al2O3SiC powder bed and obtaining a dense sintered body at 1700 degrees C. The sintered body produced by hot-pressing was about 98% of the relative density.