Evaluation of Niobium and Tantalum-Based Materials of the Hydrogen-Permeability Membranes for the Degree of Deformation and the Optimal Temperature Range of Exploitation
Alexander Panichkin, Axaule Mamayeva, Aidar Kenzhegulov, Balzhan Kshibekova, Zhanar Karboz
The data are presented for the dilatation of 10 Î¼m Nb and 80 Î¼m Ta foil samples with a double-sided 0.15 Î¼m Pd catalytic coating in a hydrogen atmosphere at d temperature of 400-900C and a pressure of 100-1000 kPa. These results were obtained with the help of direct measuring the extension of the foil strips under isothermal exposure at a given hydrogen pressure. Based on the data obtained on dilatation and previously published data on the concentration of hydrogen in the -solid solution at 400C, the values of the dilatation coefficient. were calculated. Using the results of dilatation measurements and dilatation coefficients, the isobars of temperature dependence of hydrogen concentration in Nb and Ta were calculated and constructed. These data made it possible to estimate the limiting change in concentration and linear dimensions over the cross section of a hydrogen permeable membrane of Nb and Ta at various temperatures and operating pressures at the inlet and outlet of the membrane. According to Fick's 1st law and previously published data on the hydrogen concentration value at which solid solutions of Group V metals turn into a brittle state, based on the results obtained, it was concluded that operating conditions of the composite membranes based on Nb and Ta, when used for the release of ultrapure hydrogen, are optimal.