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@PHDTHESIS{Vayyala:875391,
      author       = {Vayyala, Ashok},
      title        = {{N}anoscale investigation of high temperature oxidation
                      mechanisms of high-{C}r ferritic steels},
      volume       = {491},
      school       = {RWTH Aachen University},
      type         = {Dissertation},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2020-02000},
      isbn         = {978-3-95806-467-6},
      series       = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
                      Umwelt / Energy $\&$ Environment},
      pages        = {xix, 105},
      year         = {2020},
      note         = {Dissertation, RWTH Aachen University, 2020},
      abstract     = {Fe–22 Cr–0.5Mn based ferritic steels are being used as
                      construction materials for interconnectsin solid oxide cells
                      (SOCs). Oxidation resistance of these steels is critical for
                      their performance and was investigated in the present work
                      under conditions relevant for the interconnect operation. A
                      set of ferritic steels of a Crofer family, including the
                      commercial steel Crofer 22 H,were oxidized at 800 °C in
                      Ar–O$_{2}$, Ar–H$_{2}$ –H$_{2}$O and
                      Ar–CO–CO$_{2}$ model gases simulatingair and fuel sides
                      of the fuel cells. The key factors controlling the high
                      temperature oxidation behavior are addressed in the work,
                      namely i) the effect of gas composition and ii) the role of
                      alloying elements in the steels, especially minor additives.
                      A set of analytical techniques was employed to characterize
                      the oxidation process as well as the related structural
                      changes in the steels. TG data were correlated with the
                      results of the elemental analysis from GD–OES, phase
                      analysis by XRD or Raman spectroscopy and
                      microstructuralanalysis using SEM. A special focus in the
                      work was put on high–resolution characterization methods
                      such as TEM and APT, which enable to reveal the
                      microstructure of the oxide scale and the elemental
                      distribution at the nanoscale level and thereby investigate
                      the mass transport processes through the oxide. APT was
                      extensively used for obtaining atomic scale insight into the
                      microstructure, particularly at grain boundaries, and the
                      obtained information was employed to shed light on the
                      oxidation mechanisms. The oxidation rate of these ferritic
                      steels strongly depends on the oxygen partial pressure as
                      well as on the alloy chemistry, even on small compositional
                      changes. All studied alloys form a duplex oxide scale
                      consisting of MnCr$_{2}$O$_{4}$ spinel on top of
                      Cr$_{2}$O$_{3}$ in all atmospheres. Addition of Nb resulted
                      in Nb–rich rutile–type oxide layer formation at the
                      chromia–alloy interface. Subsequent addition of Si to
                      Nb–containing alloy leads to disappearance of Nb–rich
                      oxide layer and formation of a mesh–like SiO$_{2}$ layer
                      at this interface. Ti addition promotes formation of the
                      internal oxidation zone. [...]},
      cin          = {ZEA-3 / ER-C-2},
      cid          = {I:(DE-Juel1)ZEA-3-20090406 / I:(DE-Juel1)ER-C-2-20170209},
      pnm          = {899 - ohne Topic (POF3-899)},
      pid          = {G:(DE-HGF)POF3-899},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      urn          = {urn:nbn:de:0001-2020060509},
      url          = {https://juser.fz-juelich.de/record/875391},
}