The rate of H permeation through a Pd membrane was determined for incident molecules (0.0001 to 0.001Pa) and neutral atoms (1016 to 1019Ho/m2s) at temperatures of between 300 and 570K. The pressure dependence of H2-driven permeation was used to identify those regimes within which the permeation was diffusion-limited or surface-limited. The dependence of the Ho-driven permeation rate upon the permeation direction was used to separate the contributions which each surface made to the overall surface-limited permeation rate. One of the membrane surfaces was coated with between 3 and 25nm of Cu from a hot source. It was found that the thin Cu coatings led to a decrease in the H2-driven permeation rate. The permeation rate was found to increase in the case of Ho atoms which were incident upon the Cu-coated surface. This was explained in terms of a barrier to H2 dissociation and H recombination at the Cu/vacuum interface.

Hydrogen Permeation through Copper-Coated Palladium. P.L.Andrew, A.A.Haasz: Journal of Applied Physics, 1991, 70[7], 3600-4