Improved thermal conductivity of sintered reaction-bonded silicon nitride using a BN/graphite powder bed |
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| Affiliation: | 1. Engineering Ceramics Research Group, Korea Institute of Materials Science, Changwon, Gyeongnam 51508, Republic of Korea;2. State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050, People’s Republic of China;1. Engineering Ceramics Research Group, Korea Institute of Materials Science, Changwon, Gyeongnam 642-831, Republic of Korea;2. Metallurgical and Materials Engineering Department, National Institute of Technology Warangal, Andhra Pradesh 506004, India;1. Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK;2. Engineering Laboratory of Advanced Energy Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, 1219 Zhongguan West Road, Ningbo 315201, Zhejiang, China;3. Department of Industrial Engineering, University of Padua, 35135 Padua, Italy;4. Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, UK;1. Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141 Republic of Korea;2. Advanced Materials R&D Department, KCC Corporation, 19 Wanjusandan 4-ro, Wanju-gun, Jeonbuk-do, 55321 Republic of Korea;1. Yokohama Oils & Fats Industry Co., Ltd., 1-1 Minamisengencho, Nishi-ku, Yokohama 220-0074, Japan;2. Materials Processing Unit, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan;3. Advanced Manufacturing Research Institute, National Institute of Advanced Industrial Science and Technology, 2266-98 Anagahora, Shimo-Shidami, Moriyama-ku, Nagoya 463-8560, Japan;4. Department of Materials and Life Sciences, Sophia University, Chiyoda Ku, Tokyo 1028554, Japan |
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| Abstract: | Sintered reaction-bonded silicon nitride (SRBSN) with improved thermal conductivity was achieved after the green compact of submicron Si powder containing 4.22 wt% impurity oxygen and Y2O3-MgO additives was nitrided at 1400 °C for 6 h and then post-sintered at 1900 °C for 12 h using a BN/graphite powder bed. During nitridation, the BN/10 wt% C powder bed altered the chemistry of secondary phase by promoting the removal of SiO2, which led to the formation of larger, purer and more elongated Si3N4 grains in RBSN sample. Moreover, it also enhanced the elimination of SiO2 and residual Y2Si3O3N4 secondary phase during post-sintering, and thus induced larger elongated grains, decreased lattice oxygen content and increased Si3N4-Si3N4 contiguity in final SRBSN product. These characteristics enabled SRBSN to obtain significant increase (～40.7%) in thermal conductivity from 86 to 121 W ? m?1 ? K?1 without obvious decrease in electrical resistivity after the use of BN/graphite instead of BN as powder bed. |
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| Keywords: | Silicon nitride BN/graphite powder bed Microstructure Thermal conductivity Lattice oxygen |
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