A thermokinetic model for H diffusion across a metallic tube was established. It included the enthalpy change of metal–H reaction, heat loss, dependence of reaction rate and H diffusion coefficient upon temperature, and self-stress effects. The super-fast diffusion of H before up-hill diffusion, and Fickian diffusion during H-gas charging processes, which had been observed experimentally for 35 years, were reproduced by this model.

Effects of Reaction Heat and Self-Stress on the Transport of Hydrogen through Metallic Tubes under Conditions Far from Equilibrium. W.S.Zhang, M.Q.Hou, H.Y.Wang, Y.B.Fu: Acta Materialia, 2004, 52[20], 5805-13