INFLUENCE OF POWDER CHARACTERISTICS ON LIQUID-PHASE SINTERING OF SILICON-CARBIDE

The sintering behavior of four SiC powders was investigated by a dilatometry in argon at 1800 to 2000 degrees C. The sinterability of powders was compared and discussed in relation to the powder characteristics. The sintering behavior of SiC with oxide additives below 1900 degrees C was affected mainly by SiO2 content and particle size of starting powders, while the sintering behavior above 1900 degrees C was affected by chemical reactions between SiC, free carbon, SiO2 and oxide additives. High SiO2 contents led to a higher sinterabilities below 1900 degrees C and high carbon contents led to a low sintered densities above 1900 degrees C. The SiC ceramics sintered at 1950 degrees C showed a homogeneous microstructure although significant beta --> alpha transformation occurred during sintering.