CaWO_4-NaCl-CaCl_2体系熔盐电解制备钨粉的表征与电化学分析

Characterization and electrochemical analysis of tungsten powder prepared by molten salt electrolysis in CaWO_4-CaCl_2-NaCl system

通过熔盐电解法从CaWO4-NaCl-CaCl2体系制备出金属钨粉,采用X射线衍射仪(XRD)、电子扫描显微镜(SEM)和能谱分析仪(EDS)对钨粉的形貌和相组成进行表征。在试验数据的基础上计算电流效率,通过分析电解过程中形成的中间产物,讨论电解过程中的电极反应,采用循环伏安法和方波伏安法分析体系的基本热力学性质。结果表明:在750℃、槽电压2.5 V下经5 h以上电解可制备出纯度达到99%、平均粒度低于2μm的金属钨粉,实验中的电流效率可达到80%;电解过程的电极反应不可逆,浓差极化是体系电解速率的主要阻力。

Tungsten powders were prepared by molten salt electrolysis in CaWO4-CaCl2-NaCl system and its morphologies and phases composition were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and electron spectroscopy （EDS）, respectively. The electrolytic efficiency was calculated based on experimental data. The electrode reactions during electrolysis were discussed by analyzing intermediate products formed in the electrolysis process. The thermodynamic properties of electrolysis process were studied by cyclic voltammetry and square wave voltammetry. The results show that tungsten powders can be prepared by electrochemical electrolysis under 750℃ with a cell voltage of 2.5 V for 5 h, which have a purity of 99% and particle sizes less than 2μm, the current efficiency reaches 80%. The electrode reactions in the stable electrolysis region is irreversible and the concentration polarization process of cathode is an important factor of restricting electrolysis rate