Liquid phase sintered SiC. Processing and transformation controlled microstructure tailoring

Materials Research

V.a. Izhevskyi¹  L.a. Genova¹  A.h.a. Bressiani¹  J.c. Bressiani¹ 

[1] ,Instituto de Pesquisas Energéticas e NuclearesSão Paulo SP ,Brazil

关键词: silicon carbide;    ceramics;    sintering;    phase formation;    microstructure;    phase transformation;    in-situ reinforcement;   

DOI  :  10.1590/S1516-14392000000400007

来源: SciELO

【 摘 要 】

Microstructure development and phase formation processes during sintering of silicon carbide based materials with AlN-Y2O3, AlN-Yb2O3, and AlN-La2O3 sintering additives were investigated. Densification of the materials occurred by liquid-phase sintering mechanism. Proportion of alpha- and beta-SiC powders in the initial mixtures was a variable parameter, while the molar ratio of AlN/RE2O3, and the total amount of additives (10 vol. %) were kept constant. Shrinkage behavior during sintering in interrelation with the starting composition of the material and the sintering atmosphere was investigated by high temperature dilatometry. Kinetics of b-SiC to a-SiC phase transformation during post-sintering heat treatment at temperatures 1900-1950 °C was studied, the degree of phase transformation being determined by quantitative x-ray analysis using internal standard technique. Evolution of microstructure resulting from beta-SiC to alpha-SiC transformation was followed up by scanning electron microscopy on polished and chemically etched samples. Transformation-controlled 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 with improved mechanical properties by means of sintering was shown.

【 授权许可】

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