It was recalled that there was no general agreement as to the experimental conditions which were to be used in the H electrochemical permeation method. In particular, the need for a Pd coating on steel was not generally recognized. In order to clarify some points concerning boundary conditions, experiments were performed on pure Fe and low-alloy steels with no Pd coating. It was clearly shown that, in this case, surface phenomena were uncontrolled. The passivation layer on the exit side was especially prone to produce variations, in the H concentration on this side, as a function of time. Consequently, no quantitative evaluation of the diffusion parameters could be made if the mathematical model was based upon stationary boundary conditions.

P.Manolatos, M.Jerome, C.Duret-Thual, J.Le Coze: Corrosion Science, 1995, 37[11], 1773-83