Effects of Textures on Hydrogen Diffusion in Nickel

Abstract

Polycrystalline Ni membranes have been prepared using electrodeposition. Plating current density has a strong influence on texture development of nickel deposits. The texture of deposits can be easily manipulated by controlling plating conditions. At low current density, the left angle 100 right angle fiber texture is the main component. At high current density; the left angle 110 right angle fiber texture dominates. After annealing at 800 C for 1 h deposits with left angle 100 right angle the (111) texture has been observed. For (001), (011) and (111), the three basic planes in FCC nickel, absorption energies decrease as one moves from (001) to (011) and then (111). Hydrogen diffusion in single crystal metals is anisotropic. When polycrystalline metals have texture, the preferential orientation of metals will affect hydrogen absorption and diffusion. Hydrogen permeation results show that there are significant differences among (001), (011) and (111) textured nickel membranes. Diffusion coefficients are in increasing order for (001), (011) and (111) texture samples. The diffusion coefficient of sample without a dominant texture is smaller than those values obtained for (001), (100) and (111) textured samples. The diffusion coefficients of (001) and (011) texture membranes are higher than (001) and (011) single crystal membranes, but have the same trends. Texture in nickel samples plays an important role in hydrogen permeation. (orig.)