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研究了分别以Mg,Al为还原剂,还原K2HfF6制备金属铪粉的可能性。利用X射线衍射(XRD)、扫描电镜(SEM)、能谱分析(EDS)等测试方法分析了产品的物相、形貌,研究了NaCl-KCl熔盐体系对铪粉形貌和杂质含量的影响。实验结果表明:Mg(过量20%)为还原剂,反应温度900℃、时间3 h可以还原铪氟酸钾得到金属铪粉,但产物中含有大量的无法除去的杂质MgF2;Al(过量20%)为还原剂,反应温度900℃、时间3 h制备的铪粉纯度达到98.75%,粒径为3μm左右,杂质含量较低,其中极少量的铝是以铪铝金属间化合物的形式存在的。研究表明,在以铝为还原剂的还原体系中添加NaCl-KCl熔盐由于添加的熔盐使铪和铝更易和杂质形成以氟络盐的形态存在的复杂化合物,导致铪粉中杂质的含量增加,同时由于添加熔盐使体系引入相当数量的电子,有利于铪氟酸钾的还原,在均相反应过程中呈现局部的电中性,使得制取的铪粉尺寸倾向于降低。
The possibility of preparing metal hafnium powder by reducing K2HfF6 with Mg and Al as reducing agents respectively was studied. The phase and morphology of the product were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The effects of NaCl-KCl molten salt on the morphology and impurity content influences. The experimental results show that Mg (20% excess) is used as the reductant, the reaction temperature is 900 ℃ and the time is 3 h, the hafnium hydrofluoride can be reduced to obtain the metal hafnium powder, but the product contains a large amount of impurities MgF2 which can not be removed; ) As reductant. The purity of hafnium powder prepared at 900 ℃ for 3 h was 98.75%, the particle size was about 3μm, and the impurity content was low. A very small amount of aluminum was present in the form of hafnium-aluminum intermetallic compound. It has been found that the addition of NaCl-KCl molten salt to the reduction system using aluminum as the reducing agent makes it easier for the hafnium and aluminum to form impurities as complex compounds with the form of fluoro complex salt due to the added molten salt, resulting in the content of impurities in the hafnium powder , And at the same time the introduction of a considerable amount of electrons into the system due to the addition of molten salt is advantageous for the reduction of potassium hafnium difluoride and local electroneutrality in the homogeneous reaction so that the hafnium powder size tends to decrease.