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@PHDTHESIS{Michalik:58936,
      author       = {Michalik, Marek and Hänsel, Michael and Quadakkers, Willem
                      J.},
      title        = {{E}ffect of water vapour on growth and adherence of chromia
                      scales on pure chromium},
      volume       = {67},
      school       = {RWTH Aachen},
      type         = {Dr. (Univ.)},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {PreJuSER-58936},
      isbn         = {978-3-89336-486-2},
      series       = {Schriften des Forschungszentrums Jülich. Reihe
                      Energietechnik / Energy Technology},
      year         = {2007},
      note         = {Record converted from VDB: 12.11.2012; RWTH Aachen, Diss.,
                      2007},
      abstract     = {The oxidation behaviour of chromium was studied in the
                      temperature range 950 to 1050$^{\circ}$C. A number of
                      atmospheres such as Ar-O$_{2}$, Ar-H$_{2}$-H$_{2}$O, and
                      more complex N$_{2}$-O$_{2}$-H$_{2}$O and
                      N$_{2}$-H$_{2}$-H$_{2}$O were used, to allow the effects of
                      oxygen and water vapour partial pressures to be determined.
                      It was shown that the oxide scale formed in Ar-O$_{2}$
                      environments was dependent on the oxygen partial pressure.
                      Decreasing the pO$_{2}$ in such gas mixtures lowered the
                      oxidation rate and improved scale adherence. Different
                      behaviour was found in Ar-H$_{2}$-H$_{2}$O. Scale adherence
                      remained good in all low pO$_{2}$ gases and decreasing the
                      pO$_{2}$ in the gas (this was done by using gases of higher
                      H$_{2}$/H$_{2}$O ratio) led to an increase in the oxidation
                      rate. The main finding of the work was that the oxide scale
                      formed on chromium in Ar-H$_{2}$O and Ar-H$_{2}$- H$_{2}$O
                      gases significantly differs from that formed in Ar-O$_{2}$.
                      It appeared that oxide grains were much smaller in low
                      pO$_{2}$ gases containing water vapour than in dry high
                      pO$_{2}$ gases. It is believed that this effect of water
                      vapour on the oxide morphology development is due to the
                      faster adsorption and dissociation of H$_{2}$O at the outer
                      surface compared with O$_{2}$, which enhance the inward
                      transport of oxygen ions to the metal/oxide interface. It is
                      proposed that increased oxygen grain boundary diffusion is
                      the dominant process but molecular transport of H$_{2}$ and
                      H$_{2}$O through the scale could also operate and contribute
                      to the inner scale growth. The tracer study combined with
                      SNMS techniques showed that in low pO$_{2}$ gases a
                      significant amount of the scale was formed at the
                      metal/oxide interface and this supports the observations
                      that smaller oxide grains promote inward oxygen transport.
                      It was also found that the extent of inward growth was
                      higher in Ar-H$_{2}$-H$_{2}$O than in Ar-H$_{2}$O gas. This
                      may indicate that the oxygen partial pressure of the gas or
                      the hydrogen partial pressure were also factors determining
                      the oxidation behaviour in low pO$_{2}$ gases. [...]},
      cin          = {IEF-2},
      ddc          = {620},
      cid          = {I:(DE-Juel1)VDB810},
      pnm          = {Rationelle Energieumwandlung},
      pid          = {G:(DE-Juel1)FUEK402},
      typ          = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
      url          = {https://juser.fz-juelich.de/record/58936},
}