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@PHDTHESIS{Mllenhoff:51105,
      author       = {Möllenhoff, Marc},
      title        = {{G}rundlegende {U}ntersuchungen zur {K}orrosion von
                      {A}l$_{2}${O}$_{3}$ durch {M}etallhalogenidschmelzen und zur
                      {T}hermochemie korrespondierender {K}orrosionsphasen},
      volume       = {4214},
      issn         = {0944-2952},
      school       = {Techn. Hochsch. Aachen},
      type         = {Dr. (FH)},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {PreJuSER-51105, Juel-4214},
      series       = {Berichte des Forschungszentrums Jülich},
      pages        = {145 p.},
      year         = {2006},
      note         = {Record converted from VDB: 12.11.2012; Aachen, Techn.
                      Hochsch., Diss., 2005},
      abstract     = {Ceramic discharge vessels in metal halide lamps made of
                      polycrystalline alumina (PCA) instead of quartz glass find
                      application at higher temperatures and this results in
                      increased efficiency of the lamps. Discharge vessels contain
                      a mixture of various metal halides like NaI, DyI$_{3}$,
                      CeI$_{3}$, which influence the spectral properties of the
                      lamps. Under operating conditions, these metal halides form,
                      apart from the gas phase, a liquid phase also. In particular
                      the liquid phase reacts with the wall material PCA resulting
                      in the formation of rare-earth-aluminates. Furthermore, a
                      transport of aluminum oxide, along a temperature gradient
                      parallel to the vessel wall, takes place. This transport
                      results in reduction of wall thickness and finally causes a
                      leakage in the vessel wall. The corrosion of the wall
                      material is the most frequent reason for the failure of the
                      lamps. The aim of the investigations presented in this work
                      is to elucidate the particular influence of the liquid phase
                      in the corrosion and the chemical transport of
                      Al$_{2}O_{3}$. For this purpose, solubility data of
                      Al$_{2}O_{3}$ in lamp-relevant salt systems were determined
                      by isothermal annealing experiments. The observed corrosion
                      phenomena were described and interpreted with respect to the
                      temperature distribution inside the burner vessels and the
                      compositions of the halides. Additionally annealing
                      experiments in a temperature gradient were conducted.
                      Furthermore thermodynamic data for the corrosion phases
                      $Dy_{3}Al_{5}O_{12}$, DyAlO$_{3}$ and $Dy_{4}Al_{2}O_{9}$
                      were determined by the method of Knudsen Effusion Mass
                      Spectrometry. The present work shall contribute to model the
                      observed corrosion processes in order to increase the
                      lifetime of the lamps by selective means.},
      cin          = {IWV-2},
      cid          = {I:(DE-Juel1)VDB2},
      pnm          = {Rationelle Energieumwandlung},
      pid          = {G:(DE-Juel1)FUEK402},
      typ          = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
      url          = {https://juser.fz-juelich.de/record/51105},
}