Design and Development of Nb-W-Mo Alloy Membrane for Hydrogen Separation and Purification

摘要

The concept for alloy design of Nb-based hydrogen permeable membrane is applied to Nb-W-Mo ternary system. The alloying effects of tungsten and molybdenum on the solubility of hydrogen, the resistance to hydrogen embrittlement, the hydrogen permeability and diffusivity are investigated in a fundamental manner. It is found that the addition of tungsten and molybdenum into niobium decreases the hydrogen solubility. As a result, the resistance to hydrogen embrittlement improves and higher hydrogen pressures can be applied to the Nb-W-Mo alloy membrane. It is shown that the designed Nb-5mol%W-5mol%Mo alloy membrane with single solid solution phase exhibits excellent hydrogen permeability together with strong resistance to hydrogen embrittlement. In addition, it is found that the alloying of tungsten and molybdenum with niobium enhances the hydrogen diffusivity. In fact, the activation energy for hydrogen diffusion decreases in the order, pure Nb > Nb-5mol%W > Nb-5mol%W-5mol%Mo.