Abstract
The Permeation response of hydrogen through palladium coated iron specimens by an electrochemical oscillating method was studied to elucidate the behavior of hydrogen at the Pd-Fe interface. The Frequency dependence of the phase lag between the osicillating cathodic current and the oscillating anodic current was measured: the cathodic current means the rate of the hydrogen charging, and the anodic current the rate of the hydrogen permeation.
The phase lag of the Pd-coated Fe specimen was larger than that of the non-coated Fe specimen. This excess of the phase lag was due to the diffusion of hydrogen through Pd film and to the reaction at the Pd-Fe interface.
The boundary conditions at the Pd-Fe interface were proposed as
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oindentwhere JPd and JFe mean the hydrogen fluxes in the Pd and Fe phases, respectively, and CPd and CFe are the concentrations of hydrogen in both phases, h and k being the kinetic parameters. The frequency dependence of the phase lag measured was explained reasonably under these boundary conditions.
