Testing of dense Pd-Ag tubes: Effect of pressure and membrane thickness on the hydrogen permeability

This dependence has been discussed by investigating the impact of two effects on the considered process: the relationship between the hydrogen diffusivity from the H/Pd ratio and the surface reactions. The analysis reported in this work shows that Sieverts' law does not account for these two effects. In fact, when applying Sieverts law at the experimental data, a specific pattern is observed in the activation energy (Ea) of the hydrogen permeability. This fact is in contrast with the definition of permeability which is an intrinsic property of the material.