Composite membranes of Pd60Cu40/V-15Ni were prepared by direct-current co-sputtering method, and the effect of the Pd60Cu40 overlayer thickness upon the H permeability of the Pd60Cu40/V–15Ni composite membrane was studied at 423 to 673K. The deposition rate of the overlayer was about 3.5nm/s when the sputtering voltage of the Cu target and Pd target were set at 395 and 340V, respectively. Four membranes with overlayer thicknesses that corresponded to deposition durations of 30, 60, 90 and 120s were studied in a pure H atmosphere. The composite membrane with an overlayer thickness that corresponded to 60s deposition duration, exhibited the highest H permeability as compared to the others, and its maximum H permeability, 3.72 x 10-8molH2/msPa½, was obtained at 573K. The H permeation kinetics of the membranes was limited mainly by bulk diffusion above 473K. Below 473K, the H permeation flux saturated at high up-stream H2 pressures. The flux saturation at low temperatures was attributed to  surface-related reactions.

Effect of Overlayer Thickness on Hydrogen Permeation of Pd60Cu40/V-15Ni Composite Membranes. J.Y.Yang, M.Komaki, C.Nishimura: International Journal of Hydrogen Energy, 2007, 32[12], 1820-4