微波镁热还原法制备ZrB2粉体及表征

以二氧化锆、硼酸和镁粉为原料，利用微波镁热还原法合成了纳米级的ZrB₂粉体。研究了镁粉含量与合成工艺对ZrB₂粉体的影响，通过TG-DTA分析了物相在不同温度下的反应过程，利用XRD、EDS和TEM考察了产物的组成和形貌。实验结果表明：采用微波镁热法，加热时间为20min就可得到ZrB₂粉体，杂相Zr₂O和Mg₃B₂O₆等为镁热反应中副反应生成的产物；当原料配比为n(Zr₂O)∶n(H₃BO₃)∶n(Mg)=1∶3∶4时，合成产物中ZrB₂的相对含量最高；合成的ZrB₂粉体为球状，平均粒径为80nm左右；加入NaCl有助于降低ZrB₂颗粒尺寸。

Microwave magnesiothermal synthesis of ZrB2 powders and their characterization

ZrB2 nanopowders have been prepared from ZrO2,H3BO3 and magnesium metal by microwave magnesiothermic reduction.The effects of varying the magnesium content and the synthesis methodology on the ZrB2 powders were studied.The reaction of the ZrO2-H3BO3-Mg system at different temperatures was followed by TG-DTA.The phase compositions,particle size and morphology of the as-synthesized powders were analyzed by XRD,TEM and EDS.The experimental results showed that ZrB2 powders were obtained within 20 minutes.The impurity phases Zr2O and Mg3B2O6 inevitably appeared,produced by side reactions in the magnesiothermic reaction.When the ratio of raw materials n(ZrO2)∶n(H3BO3)∶n(Mg) was 1∶3∶4,the relative content of ZrB2 reached a maximum.TEM measurements showed that the ZrB2 powder existed as spherical particles with an average diameter of 80 nm.The particle size of ZrB2 was found to decrease when NaCl was added to the synthesis mixture.