Complementary Methods for the Characterization of Corrosion Products on a Plant-Exposed Superheater Tube

Sunday Chukwudi Okoro, Frank Nießen, Matteo Villa, Daniel Apel, Melanie Montgomery, Flemming Jappe Frandsen, Karen Pantleon

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Abstract

In this work, complex corrosion products on a superheater tube exposed to biomass firing were characterized by the complementary use of energy-dispersive synchrotron diffraction, electron microscopy, and energy-dispersive X-ray spectroscopy. Non-destructive synchrotron diffraction in transmission geometry measuring with a small gauge volume from the sample surface through the corrosion product allowed depth-resolved phase identification and revealed the presence of (Fe,Cr)2O3 and FeCr2O4. This was supplemented by microstructural and elemental analysis correlating the additional presence of a Ni-rich austenite phase to selective removal of Fe and Cr from the alloy, via a KCl-induced corrosion mechanism. Compositional variations were related to diffraction results and revealed a qualitative influence of the spinel cation concentration on the observed diffraction lines.
Original languageEnglish
JournalMetallography, Microstructure, and Analysis
Volume6
Issue number1
Pages (from-to)22–35
Number of pages14
ISSN2192-9262
DOIs
Publication statusPublished - 2017

Keywords

  • Stainless steel
  • (Synchrotron) X-ray diffraction
  • SEM
  • High-temperature corrosion
  • Chlorination
  • Spinel

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