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

The sintering behavior of four SiC powders was investigated by a dilat ometry in argon at 1800 to 2000 degrees C. The sinterability of powder s was compared and discussed in relation to the powder characteristics . The sintering behavior of SiC with oxide additives below 1900 degree s C was affected mainly by SiO2 content and particle size of starting powders, while the sintering behavior above 1900 degrees C was affecte d by chemical reactions between SiC, free carbon, SiO2 and oxide addit ives. High SiO2 contents led to a higher sinterabilities below 1900 de grees 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 transfo rmation occurred during sintering.