V–W alloy membranes for hydrogen purification

Abstract

The alloying effects of tungsten on the hydrogen solubility and the hydrogen permeability are investigated for V-based hydrogen permeable membranes. The hydrogen solubility is found to decrease by the addition of tungsten into vanadium or by increasing the temperature. It is shown that the ductile fracture occurs for V–5 mol%W alloy even in the hydrogen pressures of 0.3 MPa at 773 K. It is also found that the mechanical properties (i.e., strength and ductility) of V-based alloy are better than that of Nb-based alloy in hydrogen atmosphere at high temperature. It is demonstrated that the V–5 mol%W alloy possess excellent hydrogen permeability without showing any hydrogen embrittlement when used under appropriate permeation conditions, i.e., temperature and hydrogen pressures.