为了降低ZrB2粉体的合成温度,并在此基础上合成粒径细小、纯度高的ZrB2粉体,以ZrO2及B4C为原料,以Mg粉为还原剂,以NaCl-KCl为熔盐介质,研究熔盐镁热还原法低温合成ZrB2超细粉体的工艺.探讨了反应温度、B/Zr物质的量比及Mg粉用量对合成ZrB2超细粉体的影响,并对粉体的物相组成及显微结构进行了表征.结果表明合成ZrB2的起始温度为1 173 K, 最佳合成温度为1 473 K.合成纯相的ZrB2粉体最佳工艺条件为:B/Zr物质的量比为2.2,Mg过量50%(质量分数),1 473 K反应3 h.所合成ZrB2粉体的晶粒尺寸为30~300 nm.
Phase pure ZrB2 ultrafine powders were prepared via molten-salt-mediated magnesiothermic reduction in NaCl-KCl salt-medium using zirconium dioxide and boron carbide as raw materials, and magnesium powders as reducing agent.The influences of firing temperature, molar ratio of B/Zr and dosage of Mg powders on the synthesis of ZrB2 were discussed, respectively.In addition, the phase composition and microstructure of the as-prepared ZrB2 powders were characterized.The results showed that ZrB2 could be formed at a temperature as low as 1 173 K, and the optimum synthesis temperature was 1 473 K.ZrB2 ultrafine powders with a crystalline size range of 30-300 nm can be synthesized under the condition of 1 473 K/3 h reaction, B/Zr molar ratio of 2.2, and excessive Mg amount of 50 wt%.
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