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Anisotropic Hydrogen Permeation in Nano Poly Crystalline-Nickel ...

[b][size=5]Anisotropic Hydrogen Permeation in Nano/Poly Crystalline-Nickel Membranes[/size][/b]0]{JOFb2v
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Y. Cao, H. Li, J.A. Szpunar, and W.T. Shmayda']G\{Q6c"k GzD'~G0@
Lab for Laser Energetics , University of Rochester  United States
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[b]Abstract[/b]
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G~^$c;P'F(w"X Bilayer nickel membranes have been prepared using electrodeposition to grow polycrystalline nickel on a nanocrystalline nickel substrate. When hydrogen is charged from the nano-Ni side of the nano-Ni and poly-Ni composite membrane, the permeation current increases rapidly, then the membrane releases hydrogen faster during decay. When hydrogen is charged from the poly-Ni side of the same composite membrane, the permeation current rises gradually and takes a longer time to reach steady state. Also the permeability of nano-poly-Ni membrane is eight times higher than that of poly-nano-Ni membrane. The diffusivity for the nano-Ni side charging in a nano-poly-Ni membrane is two times higher than that of poly-Ni side charging of the same membrane. The diffusivity and permeability of nano-poly-Ni membranes are smaller than those for nano-Ni membranes, but larger than those for poly-Ni membranes. Using this anisotropic behavior, one can manipulate hydrogen permeation through composite membranes. A hydrogen permeation model for bilayer membranes is proposed to simulate diffusion in a nano-Ni and poly-Ni bilayer membrane in two-directions of charging. The experimental data is in good qualitative agreement with the model.

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