Hydrogen transport in and through niobium

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1982

OSTI ID:6768788

Sherman, R

Two separate experiments were performed in order to understand the roles of bulk diffusion and surface processes in hydrogen transport in and through niobium. Bulk hydrogen and deuterium diffusivities and permeabilities were measured at high temperatures (700-1400 K) using diffusion controlled permeation methods. At lower temperatures, surface controlled permiation was used to investigate the role of the surface in hydrogen absorption and desorption. In the high temperature hydrogen permeation experiments, diffusivities and permeabilities were measured from 700 K to about 1400 K at hydrogen pressures ranging from 4.26 Pa to about 0.013 Pa. The measured diffusivities are in agreement with values extrapolated from the low temperature surface independent measurements. In contrast to low temperature measurements, a trend indicating a classical isotope effect is observed for hydrogen and deuterium diffusivities in niobium at the higher temperatures. The surface controlled permeation experiments were in two parts, the adsorption experiments and the desorption experiments. In these experiments, the experimental conditions were arranged so that the reaction at the desired surface is the rate controlling step. A method was developed to electrochemically form Pd-black on Nb surfaces to insure barrier-free entrance and exit for H in Nb. The results for as-prepared clean surfaces and with O/sub 2/, N/sub 2/, Cl, CO, SO/sub 2/ and H/sub 2/S input gases adsorbed on the surface will be discussed to investigate the effect of adsorbed species on surface permeation processes.

• OSTI ID: 6768788
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
DIFFUSION
ELEMENTS
HYDROGEN
METALS
NIOBIUM
NONMETALS
PERMEABILITY
PHYSICAL PROPERTIES
PRESSURE DEPENDENCE
TEMPERATURE DEPENDENCE
THERMAL DIFFUSION
THERMAL DIFFUSIVITY
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENTS