Morphology and sinterability of thermally treated carbothermally synthesized silicon nitride powders

Carbothermally produced alpha-Si3N4 powder is thermally treated (1400 degre es-1500 degrees C for 4-12 h) in nitrogen-gas to determine the impact of th ermal treatment on powder composition, particle size, morphology, and sinte rability. Thermal treatment reduces residual carbon and oxygen content and reduces internal porosity (lower surface area), which results in a rounding of the particles. The lower oxygen content of the heat-treated, carbotherm ally produced alpha-Si3N4 powder allows Y2O3-Al2O2-SiO2 sintering formulati on to be adjusted so that an improvement in the early stage of densificatio n can be achieved.