Synthesis of highly purified and crystallized h-BN using calcium-assisted carbothermal reduction nitridation |
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Authors: | Shota Daiki Toshihiro Ishikawa |
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Affiliation: | 1. Tokuyama Corporation, Shunan, Yamaguchi, Japan;2. Tokyo University of Science, Yamaguchi, Sanyo-Onoda City University, Sanyo-Onoda, Yamaguchi, Japan |
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Abstract: | Highly purified and crystallized hexagonal boron nitride (h-BN) powder is suitable as thermally conductive filler in resins. To obtain h-BN powder with large particle size, as well as high purity and crystallinity, high-temperature heat treatment over 1800°C in a N2 gas atmosphere is effective. The carbothermal reduction nitridation (CRN) involves the carbothermic reduction of boric oxide in a N2 gas atmosphere. In CRN using a CaO promoter, h-BN particles with high crystallinity can be obtained by a simple heat treatment process. CaO prevents the evaporation of boron oxide and aids in h-BN particle growth at high temperatures. However, CaB6 is formed as byproduct or impurity when CRN using the CaO promoter is performed at temperatures higher than 1800°C. In this study, the relationship between the products and the reaction temperature was clarified via thermodynamic considerations and experimentation. The results clarified the ideal reaction process of CRN using a CaO promoter to obtain highly purified and crystallized h-BN powder. |
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Keywords: | boron nitride calcium oxide impurities particles |
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