Hydrogen permeability and erosion behavior of W-Pd bimetallic systems

摘要

The erosion behavior of W-Pd bimetallic systems has been investigated for both hydrogen-saturated (H/Pd～0.65) and unsaturated states during impact of a steady-state nitrogen plasma from a mirror Penning discharge. An essential decrease by factors of about 2-5 in the erosion rate of W was observed for hydrogen-saturated W-Pd samples in the nitrogen ion energy range from 0.8 to 1.6keV. Possible reasons for this erosion behavior are discussed. Isotherms and isobars of hydrogen permeability through W-Pd systems were measured in the temperature range of 573-973 K and hydrogen pressure range of 1.33 x 10~2 to 10~5 Pa. It is shown that the limiting stage of permeation process is, most likely, the diffusion in the W film. The activation energy of hydrogen permeability was determined to be ～12 kJ/mol, this being much lower than the literature data for bulk tungsten at molecular hydrogen-driven permeation. Possible mechanisms are suggested and analyzed to explain the observed decrease in the activation energy of hydrogen penetration through W-Pd systems.