INVESTIGATION OF GAS TRANSMISSION CHARACTERISTICS OF THIN-FILM MEMBRANE MATERIALS BASED ON PALLADIUM ALLOYS

Abstract

All-metal thin-film membrane materials based on palladium alloys have been developed, namely Pd-40%Cu, Pd-23%Ag, Pd-25%Cu-5%Au. Thin films were obtained by melting in an electric arc furnace in an argon atmosphere, followed by cold rolling to a thickness of 20-30 microns. Alloying palladium with other metals in the creation of thin-film membrane materials allows solving the problem of hydrogen embrittlement, as well as reducing the cost of the final product. These developed thin-film materials were studied in the processes of obtaining high-purity oxygen as membranes. It was found that membranes based on the Pd-Ag alloy have the highest hydrogen flux density, which is presumably due to the ordering of the solid solution to form a β-phase with a less dense crystal lattice, compared with the HCC lattice of the α-phase. The numerical values of the flux density for Pd-23%Ag membranes are up to 24,8 mmol/(s·m2), which is up to 2,6 times higher than pure palladium. Samples made of Pd-40% Si alloy with at least a high flux density of 11,3 mmol/(s·m2). The alloy Pd-25%Cu-5%Au had the lowest values. The hydrogen flux density was 5,4 mmol/(s·m2). It has been established that palladium alloying with other metals leads not only to an improvement in the strength characteristics of thin-film membrane materials, but also significantly increases their gas transmission characteristics. These developed membrane materials will be able to become the basis for diffusion filters in steam reforming reactors of hydrocarbons.