Electrochemically Assisted Formation of Fine Niobium Powder in Molten Salt

The electrochemically assisted formation of niobium powder in a molten salt was investigated in order to develop a process for producing fine metal powder for use in electronic devices. A niobium rod (anode) was immersed in NaCl-KCl-MgCl2-DyCl2 molten salt at 1000 K, and it was anodically polarized and dissolved in this salt. The electrochemically dissolved niobium ions (Nbn+) were subsequently reduced in situ by dysprosium divalent ions (Dy2+) present in the molten salt; this resulted in the production of niobium powder. The reductant, Dy2+, in the molten salt was regenerated either by electrochemical reactions at the cathode or by magnesiothermic reduction. Fine niobium powder with a narrow particle size distribution (D10 = 0.3 mum, D50 = 0.5 mum, D90 = 0.9 mum) was successfully obtained under a specific condition. Further, it was found that the particle size of the niobium powder can be effectively controlled by varying the Dy2+ concentration in the molten salt.