Examination of carbon inclusions in sintered silicon carbide

Abstract Particles of excess carbon are a general feature in the microstructure of sintered SiC. This phenomenon was studied by high resolution Auger electron spectroscopy on UHV-exposed fracture surfaces of (B, C)- and (Al, C)-doped materials. Normally the inclusions are about 1–2 μm in diameter, but particles of about 10–20 μm are also observed. The inclusions contain free carbon or carbon together with significant accompanying elements and phases, which were found to be characteristic for each particular material. The analytical results are briefly discussed with respect to processing and their impact on materials properties.