Fine Tungsten Powder

The high quality and high purity fine tungsten powders are typically greater than 99.95% tungsten purity with average particle sizes up to 10 microns. These powders are used in powder metallurgy applications such as electrical contacts, heavy metal alloys, electronic heat sinks, mining tools and fabricated tungsten rod/bar.
Direct electrochemical reduction of solid CaWO4 to fine W powder in molten CaCl2-NaCl was studied by cyclic voltammetric measurement and potentiostatic/constant-voltage electrolysis. The effect of electrolysis conditions such as electrolysis time, temperature and voltage on the quality of the product (the residual amount of CaWO4) was systematically investigated. Based on the solubility tests of CaWO4 in the melt in a wide temperature range, an unprecedented strategy on electrolytic extraction of pure tungsten powder was proposed and confirmed, which involves low-temperature and short-duration electrolysis of solid CaWO4 in molten CaCl2-NaCl eutectic salt (1023 K, 10-hour electrolysis) followed by a simple washing process in the same melt at a higher temperature (1123 K, 1-hour washing). The particle size of the as-prepared W powder is less than 200 nm. This process exhibits a high yield and increased energy efficiency for production of fine W powder from CaWO4.