Hydrogen diffusion in α-iron studied using an electrochemical permeation transfer function

Transfer function analysis of hydrogen permeation through a metallic membrane in a Devanathan cell

“…Few experiments were also achieved in the presence of a thicker Pd back coating (1.4 lm), and it was verified that the permeation current as well as the permeation transients were not significantly affected. In agreement with Bruzzoni et al, it can be said that the thin palladium layer avoids formation of an iron oxide film without introducing significant additional delays in the diffusion process [10,11]. It is interesting to note that the presence of the Pd back layer has also an influence on the entry side.…”

“…It has been shown that it is possible to get additional information on the permeation mechanism in a Devanathan cell by performing a small AC signal analysis, by measuring simultaneously the electrochemical impedance DV 1 /DI 1 at the entry side and the permeation transfer function (PTF) H(x) = DI 2 /DI 1 relating the AC output current to the AC input current fluctuations [10][11][12]. In the first part of this paper, a general model of the permeation transfer function was derived for the stationary condition, and few characteristic cases were developed for limiting values of the main parameters [12].…”

Transfer function analysis of hydrogen permeation through a metallic membrane in a Devanathan cell. I. Theory

“…which is the expression already published in the literature [24,27] as surface processes have not been considered in these publications.…”

“…It was applied in the case of iron [21,[23][24][25], steel [26] or palladium [27][28][29][30]. The theoretical impedance analysis of the hydrogen absorption reaction for the above two models of hydrogen entry was carried out by Lim and Pyun in the case of palladium [29,30].…”

“…Zoltowski [34,36] has proposed a model for the transfer functions under selfstress conditions. Bruzzoni et al [24] have reported an analytical expression of transfer functions in a theoretical model taking into account the bulk diffusion in iron but without considering surface processes. Gabrielli et al [28] have demonstrated the potentialities of permeation transfer function techniques for studying hydrogen transport into a palladium membrane and the significant role of the surface phenomena in the kinetics of hydrogen permeation process.…”