Preparation and characterization of tungsten powder through molten salt electrolysis in a CaWO_4-CaCl_2-NaCl system

摘要

In the present study, preparation of tungsten powder from a CaWO_4-CaCl_2-NaCl system using a molten salt electrolysis method was investigated. Analytical techniques, such as scanning electron microscopy equipped with EDS and XRD, were respectively used to study the microstructure and phase evolution of the resulting powder. AES and the Fisher method were used to analyze the purity and particle size of the samples, respectively. The current efficiency during electrolysis was studied based on the experimental data. Thermodynamic properties of electrolysis process were studied using cyclic voltammetry. The results showed that tungsten powder could be prepared at a temperature of 750 °C and a cell voltage of 2.5 V for 250 min. The electrode reactions occurring in the stable electrolysis region were irreversible, and kinetic obstruction of electrolysis could be derived from the low solubility of calcium tungstate in the CaCl_2-NaCl melt