Hydrogen permeability of the Pd–Pb system foil of various composition

Abstract

The purpose of the study was identification of the role of the chemical composition of Pd, Pb-alloys based of palladium in the processes of injection and extraction of atomic hydrogen. The objects of study were Pd-Pb alloy foils with a lead content of 3, 5, 7, 9, and 11 at. %, representing the b-phase of the solid solution. Samples with a thickness of 40 to 62 µm were obtained by cold rolling. Hydrogen permeability was studied by cyclic voltammetry and two-stage cathode-anode chronoamperometry in deaerated solutions of 0.1 M H2SO4. The obtained results were processed according to a mathematical model developed for electrodes of semi-infinite thickness. The dependence of the hydrogen permeability coefficient, as well as the rate constants of the processes of injection and extraction of atomic hydrogen, on the chemical composition of the alloy has been revealed. It was found that the Pd–Pb alloy with a lead content of 5 at.% demonstrates the highest values of hydrogen permeability compared with samples of the same crystal structure, since the rate constant of atomic hydrogen injection is very sensitive to the alloy structure. The latter confirms that the phase-limiting transition of atomic hydrogen into the alloy is the rate-determining stage, at least in the initial period of time.

Keywords

• solid solution of pd-pb systems
• atomic hydrogen
• phase boundary transition
• alloy structure
• hydrogen permeability
• cathode injection
• anode extraction