Article ID Journal Published Year Pages File Type
7723212 International Journal of Hydrogen Energy 2013 11 Pages PDF
Abstract
To provide insights into the interface structure of hydrogen permeation barrier of α-Al2O3/FeAl and its effect on stability and diffusion of hydrogen isotopes, the thermodynamics and kinetics of H diffusion in α-Al2O3 (001)/FeAl (111) slab with Al/O and Al/Fe/O interfaces have been studied by the density functional theory. Hexagonal alumina layers above the FeAl plane in interface region are predicted. The interfacial binding involves cation-anion and metal-metal interactions. H-surface interaction on the α-Al2O3/FeAl slab resembles that on pure α-Al2O3 (001) slab, and the H interstitials in the α-Al2O3 part of the slab with the Al/O interface are significantly less stable than in bulk of α-Al2O3 slab, whereas that with the Al/Fe/O interface are slightly more stable. H diffusion into the α-Al2O3 part of both slabs must overcome a larger barrier of about 1.66-2.02 eV at surface-to-subsurface step, as pure α-Al2O3 case. For the bulk path, the migration of H atom can occur more readily in the α-Al2O3 part of the slab with the Al/O interface compared to that with the Al/Fe/O interface. Thus α-Al2O3/FeAl barrier with interface region of the Al, Fe mix-oxide is predicted to be much effective at protection against H permeation of the underlying steel.
Related Topics
Physical Sciences and Engineering Chemistry Electrochemistry
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