Theoretical and experimental analyses of relationship between processing and thermal conductivity of SiC with oxide additives

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• 作者：Yoshihiro Hirata ; ^{hirata@cen.kagoshima-u.ac.jp" class="auth_mail" title="E-mail the corresponding author} ; Hideyuki Shirai ; Ryo Ando ; Yukako Matsumoto ; Taro Shimonosono
• 关键词：A. Hot pressing ; B. Porosity ; C. Thermal conductivity ; D. SiC
• 刊名：Ceramics International
• 出版年：2016
• 出版时间：September 2016
• 年：2016
• 卷：42
• 期：12
• 页码：13612-13624
• 全文大小：4765 K

文摘

This paper analyzes theoretically and experimentally the thermal conductivity of the SiC-oxide additive-pore system. In the developed 6 model structures, the thermal conductivity of an SiC compact (κ_b) with oxide was calculated as functions of the volume fractions of SiC, oxide additive and pores. The calculated κ_b decreases in the order of a continuous phase where the other two particulate phases are dispersed: SiC>oxide additive>pores. The measured κ_b values of SiC compacts hot-pressed with 4–50 mass% oxide additive (mixture of 33.3 mass% Al₂O₃-33.3 mass% Y₂O₃-33.3 mass% SiO₂) were well explained by the calculated κ_b in two types of oxide continuous phase models. The thermal conductivities for only SiC grains in SiC compacts hot-pressed with 4 mass% Al₂O₃, Y₂O₃, SiO₂, Al₂O₃-Y₂O₃, Y₂O₃-SiO₂ and Al₂O₃-Y₂O₃-SiO₂ at 1950 °C were also estimated theoretically in the developed two model structures using the measured κ_b (oxide continuous phase model and SiC continuous phase model). Based on the calculated results, the following key factors are identified to achieve a high κ_b: (1) high sintered density, (2) a small amount of oxide additive with a high thermal conductivity, (3) no dissolution of foreign atoms from a liquid phase into SiC grains during solidification process.