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°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 SiO2:Al:C in the system was found to be 3:4:6. The free carbon was removed by roasting at 650°C for 30 min. Pressureless sintering was found to be very effective in hindering the disintegration of the specimen with a Al2O3–SiC powder bed and obtaining a dense sintered body at 1700°C. The sintered body produced by hot-pressing was about 98% of the relative density.