Hydrogen permeation through palladium after hydrogen-thermal treatment and exposure to a plasma of glow discharge in hydrogen, helium and argon

Abstract

Hydrogen permeability of palladium membranes was investigated before and after their exposure of to a glow-discharge plasma. A preliminary treatment of activated (subjected to a long-time annealing in vacuum at about 1000 K) palladium by a glow-discharge plasma does not cause any changes in permeability. The results of plasma treatment of a partially activated (heated for 1 h in vacuum) palladium much depend on irradiation conditions. For treatment in the cathode regime (Pd-membrane serves as a cathode) the rates of permeability surface processes increase. As opposed to hydrogen-heat treatment, the time for reaching the permeability characteristics corresponding to the activated state is essentially reduced. Experiments on irradiating Pd-membranes with different mass ions (H +, He +, Ar +) and the determination of the degree of surface decarburization from the methane yield during annealing of irradiated samples in the hydrogen atmosphere indicated that the permeability activation effect is caused by decarburization phenomena due to irradiation. The treatment in the anode regime causes a decrease in the rate of hydrogen permeation through Pd. This is due to the occurrence of thin films deposited from the sputtered chamber wall on the Pd-membrane surface.