金属热还原K_2HfF_6制备铪粉的研究  

Preparation of Hafnium Power by Metallothermics of K_2HfF_6

作　　者：王芳[1] 黄永章[1] 王鑫[1] 张顺利[1] 王力军[1] 

机构地区：[1]北京有色金属研究总院矿物资源与冶金材料研究所,北京100088

出　　处：《稀有金属》2013年第2期272-276,共5页Chinese Journal of Rare Metals

基　　金：国家科技部高新技术产业发展项目(2008-2441)资助

摘　　要：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 hafnium powder was obtained by Mg, A1 metallothermics using K2 HfF6 powder as raw materials. The phase, morphol- ogy and impurity composition of the produced metal power was analyzed by X-ray diffraction （ XRD）, scanning electron microscope （SEM） and energy spectrum analysis（EDS） method respectively. The influence of molten salt system of NaC1-KC1 on morphology and impurity composition of the produced metal power was also studied. Investigation suggested that magnesium could reduce K2HfF6 at 900 ℃ after 3 h by using 120% magnesium as reductant, and there were a lot of MgF2 impurities in the hafnium power which could not be removed. The hafnium power with hafnium content of 98.75%, the size of about 3 μm with fewer impurities was prepared at 900 ℃ af- ter 3 h by using 120% aluminum as reductant. Extremely small amount of aluminum existed in the form of hafnium aluminum interme- tallic compound. Research showed that it could make hafnium and aluminum be more likely to form impurities of the complex fluorine compounds when adding NaC1-KC1 molten salt into the system of aluminum as reducing agent, which could result in the increase of im- purities. At the same time, due to adding moltens introduced a number of electronics, which was helpful for reduction, local electrical neutral in the homogeneous reaction process caused the size of hafnium powder to tend to reduce.

关 键 词：K2HfF6 金属热还原法 熔盐 NaCl-KCl 

分 类 号：TF841.4[冶金工程—有色金属冶金]