Low-Temperature Synthesis of ZrC Powder by Cyclic Reaction of Mg in ZrO2–Mg–CH4 |
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Authors: | Hidehiko Kobayashi Kenichi Shimosaka Miki Saitoh Takashi Mitamura |
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Affiliation: | Department of Applied Chemistry, Faculty of Engineering, Saitama University, Urawa, Japan 338 |
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Abstract: | We investigated the conditions for low-temperature synthesis of ZrC fine powder from ZrO2–Mg–CH4. The synthesis utilizes a thermite-type reaction, with Mg as the reducing agent, and a reaction between Mg and CH4 gas as a carbon source. The Mg/ZrO2 molar ratio as well as the heating rate were varied. Because C can be continuously fed into the reaction group by the cyclic reaction of Mg through the formation and decomposition of Mg2C3 (2Mg + 3CH4→ Mg2C3+ 6H2→ 2Mg + 3C), a molar ratio of 2.2 for Mg/ZrO2 was sufficient for the synthesis of single-phase ZrC. ZrC powders were synthesized under the following conditions: Mg/ZrO2 molar ratio = 2.2, heating rate = 20°C/min, and temperature maintained at 750°C for 30 min. The amount of reaction heat produced in the reduction reaction of ZrO2 by Mg depended on the Mg/ZrO2 molar ratio, specifically, the amount of ZrO2 contained. Moreover, the cyclic reaction of Mg-Mg2C3–Mg was influenced by the amount of reaction heat described above and by the heating rate. The ZrC fine powder showed little aggregation and high dispersibility. |
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