Design of Molten Salt Bath on the Basis of Acid-Base Cooperative Reaction Mechanism. Smooth Electrodeposition of Tungsten from KF-B₂O₃-WO₃ Molten Salt

抄録

This investigation was carried out to find a molten salt which enables a smooth electrodeposition of tungsten. The KF-B₂O₃-WO₃ molten salt was selected on the basis of the acid-base cooperative reaction theory. A composition of KF(67 mol %)-B₂O₃(26 mol %)-WO₃(7 mol %) was selected as the preferred bath composition. Using a tungsten anode, smooth electrodeposits were obtained at 1123 K and at a current density ranging from 250 Am⁻² to 550 Am⁻² on nickel, copper, stainless steel, and mild steel substrates. When a graphite anode was used, smooth electrodeposits accompanied by dendrites were obtained. The Vickers microhardness number of the electrodeposit was 422 (load 0.49 N). The smooth electrodeposit had tendencies to form the 111 fiber texture or a mixed texture of the 111, 211 and 321 fiber textures.