期刊
RARE METALS
卷 32, 期 4, 页码 408-413出版社
NONFERROUS METALS SOC CHINA
DOI: 10.1007/s12598-013-0069-2
关键词
Reaction mechanism; Magnesiothermic reduction; Zirconium boride; Self-propagating synthesis
资金
- National Natural Science Foundation of China [91016014]
Fine zirconium diboride (ZrB2) powders with high purity were successfully prepared by combustion synthesis through magnesiothermic reduction process in Mg-B2O3-ZrO2 system. The reaction mechanism was investigated by differential thermal analysis and quenching experiment. The results show that the whole magnesiothermic reduction process includes three stages: first, molten B2O3 and Mg formed above the temperature of 650 A degrees C, and glassy B2O3 and solid ZrO2 particles were coated on the surface of the molten Mg; thus, the hollow balls can be formed when the molten Mg was exuded under capillary function. Second, ZrO2 particles reacted with molten Mg to form Zr and MgO with dissolution-precipitation mechanism, which released a large amount of heat to induce the diffusion reaction between B2O3 and Mg to form B and MgO. Last, Zr reacted with B to form ZrB2 grains. The preparation of ZrB2 by self-propagating synthesis in Mg-B2O3-ZrO2 system is a solid-liquid-liquid reaction.
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