J. Korean Ceram. Soc. > Volume 36(10); 1999 > Article
 Journal of the Korean Ceramic Society 1999;36(10): 1094.
 여러 가지 크기의 $SiC_{platelet}$ Seed를 함유한 SiC 세라믹스의 미세구조 및 기계적 특성 최명제, 박찬, 박동수1, 김해두1 부경대학교 재료공학과1한국기계연구원 요업재료그룹 Microstructures and Mechanical Properties of SiC Containing $SiC_{platelet}$ Seeds of Various Size ABSTRACT Liquid phase sintered silicon carbides were obtained by sintering of $alpha$-SiC and $beta$-SiC powders as starting materials at 2173K and 2273K respectively. The SiCplatelet seeds of different sizes were obtained by a repeated ball milling and sedimentation. Their mean size (d50) were 2.217 ${mu}{textrm}{m}$ 13.67 ${mu}{textrm}{m}$, 22.17${mu}{textrm}{m}$ respectively 6wt%Al2O3-4 wt% Y2O3 was used as the sintering additives for the liquid phase sintering. The two silicon carbides had a bimodal microstructure consisting of small matrix grains and large platelike grains when the SiCplatelet seeds were added. In the case of the $beta$-SiC the appreciable phase transformation occurred as sintering temperature increased from 2173K to 2273K and resulted in matrix shape change from equiaxed into platelike grains. In contrast there was no shape change for the $alpha$-SiC. The size of large grains in the $alpha$-SiC of large grains in the $alpha$-SiC was larger than that of the large grains in the $beta$-SiC These results suggested that the growth of the $alpha$-SiCplatelet in the $alpha$-SiC matrix was more favored than that of the $alpha$-SiCplatelet in the $beta$-SiC matix. The three point flexural strength decreased as the added seed size increased. Fracture toughness values of samples sintered at 2273K were higher than those of samples sintered at 2173K. Key words: silicon Carbide, Sedimentation, Microstructure, Strength, Fracture toughness
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