Fabrication of Hydrogen Permeation Membranes for Direct Internal Recycling of Tritium*

This study describes the fabrication process and selective hydrogen permeation properties of thin-metallic Nb and Nb/W films deposited on top of nanoporous membranes made of anodic aluminum oxide. The thin films are made using pulsed DC sputtering deposition and the nanoporous membranes are synthesized using electrochemical methods at General Atomics (GA). The membranes provide a mechanical support to the thin films. Together, the porous membrane-thin film system is used as a gas permeation device. By varying the composition of the films, this system provides a fast way to test the gas permeation properties of different materials. The hydrogen permeation performances are tested in a home-built differential pressure test system under various inlet pressure loads and gas mixtures by monitoring the outlet pressures with a residual gas analyzer. Different W inclusion concentrations are studied and the effect of W inclusions on the hydrogen permeation and embrittlement resistance of Nb thin films at various thicknesses are tested.