Liquid-phase sintered silicon carbide based ceramics with AIN-Ysub(2)Osub(3) and AiN-Lasub(2)Osub(3)

Abstract

Microstructure development and phase formation processes during sintering of silicon carbide based materials with 10 vol.% of AIN - Y2O;, or AIN - LazOz sintering additives were investigated. Densification of the materials occurred by liquid-phase sintering mechanism. Ratio of @- and B-SiC powders in the initial mixtures was a variable parameter. Shrinkage behavior during sintering was shown to strongly depend both on the combination of sintering additives and on the sintering atmosphere used. Kinetics of B-SiC to aSiC phase transformation under conditions of postsintering heat treatment at 1900-1950°C was studied, the degree of transformation determined by quantitative xray analysis. Evolution of microstructure resulting from B to a phase transformation was followed up by scanning electron microscopy. Transformationcontrolled grain growth mechanism similar to the one observed for silicon nitride based ceramics was established. Possibility of in-situ platelet reinforced dense SiC-based ceramics fabrication by means of sintering was Shown.