EFFECTS OF DEOXIDIZER ADDITION ON THE HYDROGEN PERMEATION CHARACTERISTICS OF V-NI ALLOY MEMBRANES

The effects of solute oxygen atoms on the hydrogen permeability and diffusivity in V-15 at%Ni alloy membranes have been investigated. In order to remove the solute oxygen atoms, a suitable amount of the deoxidizer such as Y, Ti, or Zr was added during arc-melting the alloy. The hydrogen permeability and diffusivity of the alloy samples plated with Pd were determined using the gas permeation and time-lag methods in the temperature range 373 to 673 K. The samples added a suitable amount of Y, Ti or Zr showed higher hydrogen permeabilities and diffusivities above 473 K, than a sample without the deoxidizer. Below about 473 K, however, these samples showed a hydrogen trapping phenomenon, just like a sample without the deoxidizer. It is considered that solute oxygen atoms in the alloy decrease the effective area for hydrogen permeation. The hydrogen trapping phenomenon observed below about 473 K is considered to be caused mainly by surface effects.