First-principles investigations of Ni3Al(111) and NiAl(110) surfaces at metal dusting conditions

Souheil Saadi, Berit Hinnemann, Charlotte C. Appel, Stig Helveg, Frank Abild-Pedersen, Jens Kehlet Nørskov

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

We investigate the structure and surface composition of the γ′-Ni3Al(111) and β-NiAl(110) alloy surfaces at conditions relevant for metal dusting corrosion related to catalytic steam reforming of natural gas. In regular service as protective coatings, nickel–aluminum alloys are protected by an oxide scale, but in case of oxide scale spallation, the alloy surface may be directly exposed to the reactive gas environment and vulnerable to metal dusting. By means of density functional theory and thermochemical calculations for both the Ni3Al and NiAl surfaces, the conditions under which CO and OH adsorption is to be expected and under which it is inhibited, are mapped out. Because CO and OH are regarded as precursors for nucleating graphite or oxide on the surfaces, phase diagrams for the surfaces provide a simple description of their stability. Specifically, this study shows how the CO and OH coverages depend on the steam to carbon ratio (S/C) in the gas and thereby provide a ranking of the carbon limits on the different surface phases.
Original languageEnglish
JournalSurface Science
Volume605
Issue number5-6
Pages (from-to)582-592
ISSN0039-6028
DOIs
Publication statusPublished - 2011

Keywords

  • Carbon
  • Ni3Al
  • Ni alloys
  • Metal dusting
  • Density functional theory
  • Steam reforming
  • NiAl
  • Oxide scale

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