Hydrogen permeable membranes based on niobium foils coated with layer of tungsten and molybdenum in niobium solid solution characteristics research.

摘要

Paper presents the results of measuring the hydrogen permeability of 40 μm niobium foil membranes, on one side coated with a layer of a solid solution of tungsten in niobium or molybdenum in niobium. The measurements were carried out in a hydrogen atmosphere of technical purity with a smooth temperature decrease followed by isothermal aging and under conditions of cyclic temperature variation. It is shown that the degree of purity of argon used for magnetron sputtering has the greatest influence on the hydrogen permeability of composite niobium membranes. As a result of 1 μm thick molybdenum in niobium (Nb - 15 wt% Mo) and tungsten in niobium (Nb-10 wt% W) solid solution deposition on the surface of a niobium membrane, the average value of their hydrogen permeability decreases, while a number of samples demonstrated a significant increase of durability. When the Nb - 15 mass% Mo layer is deposited in purified argon, the hydrogen permeability of the membranes increases by 15-20 times compared to pure niobium and up to 30 times in comparison with the membranes deposited in technical purity argon and reaches 68 mol/s*m*Pa~(0.5), however, lifetime of membranes before destruction is dramatically reduced and ranges from 13 to 280 s., with a rapid decrease in hydrogen permeability due to their oxidation. In case of Nb - 10 wt.% W films deposition using additionally purified argon, the hydrogen permeability of membranes rises more than 20-times and reaches a level of 30 mol/s*m*Pa~(0.5), however, the membrane operation time is shortened to 25-320 s. The hydrogen "superconductivity" effect found in niobium composition membranes requires further studies. The use of films of solid solutions of molybdenum or tungsten in niobium, as buffer layers between the membrane and palladium layer, is proposed.