Platinum Metals Rev., 1973, 17, (3), 89
Palladium Coating on Niobium
Chemical Deposition of Thin Films
The protection afforded to refractory metals by coating them with thin layers of platinum metals is well known. Platinised titanium electrodes are used extensively in industrial electrochemical processes and platinised niobium is equally useful for cathodic protection, particularly of submarine structures.
Russian scientists have been active in this field and there now comes a report of palladium films applied to niobium by a chemical method (Izv. Vyssh. Ucheb. Zaved., Khim. Khim. Tekhnol., 1972, 15, (9), 1419–1420). A. A. Ivanov and his associates at the Peoples Friendship University named for Lumumba, Moscow, deposited palladium films 1 to 1.5 μ thick on niobium by immersion at 70°C in a bath of palladium chloride dissolved in 25 per cent ammonia solution containing the disodium salt of EDTA and N2H4H2SO4. The niobium was first etched cathodically in caustic soda solution containing chlorine to remove oxide and was then annealed at 1200°C. Thicker films applied in one operation peeled off but 3 to 4 μ films were obtained in two stages by annealing the niobium in vacuum after the first palladium layer had been deposited.