Compact coating of tantalum on tungsten prepared by molten salt electrodeposition

Attempts to prepare tantalum coating on tungsten have been performed in 55mol%LiF-35mol%NaF-10mol%CaF2 melt containing K2TaF7. Electrolytic deposition of tantalum was carried out by galvanostatic polarization. A conproportionation reaction also occurred that interfered with the electrodeposition and resulted in decrease in current efficiency. However, the product of this reaction was soluble, which diffused away from the electrode without contaminating the deposit. Hence, a compact electrodeposited tantalum coating was obtained on tungsten substrate. An excellent interface was possible when coating was performed in the melt containing 2mol% K2TaF7. (author)