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@TECHREPORT{Siebert:136168,
      author       = {Siebert, Bernhard},
      title        = {{R}eproduzierbare {H}erstellung und {C}harakterisierung von
                      plasmagespritzten {W}ärmedämmschichtsystemen auf
                      {Z}r{O}2-{B}asis},
      volume       = {3669},
      number       = {Juel-3669},
      address      = {Jülich},
      publisher    = {Forschungszentrum, Zentralbibliothek},
      reportid     = {PreJuSER-136168, Juel-3669},
      series       = {Berichte des Forschungszentrums Jülich},
      pages        = {VII, 122 S.},
      year         = {1999},
      note         = {Record converted from JUWEL: 18.07.2013; Zugl.: Bochum,
                      Univ., Diss., 1999},
      abstract     = {The present state-of-the-art enables the deposition of
                      plasma-sprayed thermal barrier coating systems, especially
                      in turbine construction, with the aim of improving the
                      efficiency of turbines by higher inlet temperatures and thus
                      increasing profitability and reducing pollutant emissions
                      and (electricity generation) costs. To achieve this
                      improvement, a two-layer system is used, consisting of a
                      metallic, vacuum-plasma-sprayed NiCoCrAIY bond coat for
                      oxidation protection and a ceramic 7-8 $wt\%$ - Y203 Zr02
                      thermal barrier coating produced by atmospheric plasma
                      spraying and serving as a heat shield. The studies described
                      in this thesis concern, on the one hand, the production of
                      coatings using the F4 plasma torch with an established
                      history in the industry as well as the new Triplex torch
                      technology. Parameter variations and parameter studies for
                      the bond coats were carried out exclusively with the F4
                      torch. The top coat studies were performed with both the F4
                      and triplex torches. For characterization, on the other
                      hand, extensive studies were carried out using mercury
                      analysis, image analysis, microindenter Young's Modulus and
                      hardness measurement, thermal cycling, Raman microscopy,
                      roughness measurements, dilatometry, SEM and optical
                      microscopy. The factor test scheme presented here is a
                      procedure which unambiguously defines the spraying distance
                      as the most important factor influencing porosity and spray
                      efficiency with the Triplex torch. For both torches,
                      increasing wear (in particular of the cathods) is detected
                      on the basis of different layer porosities. The Triplex
                      torch was subjected to much stronger wear than the F4 torch.
                      Wear reducing measures, such as using lower electrical
                      power, contribute to very good reproducibilities for coating
                      production. However, parameter sets cannot be directly
                      transferred from flat specimens to cylindrical specimens or
                      specimens of different shapes. The suitability and
                      reproducibility of the individual investigation methods for
                      the characterization of ceramic thermal barrier coatings is
                      also dealt with in more detail. Thus, for example, mercury
                      porosity measurements document a bimodal pore distribution
                      of the ceramic which cannot be identified by image analysis
                      with realistic magnifications and experimental effort. For
                      the precise characterization of stress measurements of a
                      TBC, the Raman investigations carried out proved to be too
                      imprecise. The measurement of the Young's modulus is not
                      trivial either, since the value depends, for example, on the
                      coating load, the measuring method and the pore shape. In
                      general, those methods of measuring the Young's modulus
                      where the greatest possible portion of the microstructure
                      has an influence on the measuring result are preferable to
                      locally greatly restricted measurement techniques like the
                      microindenter. In summary, it may be stated that coating
                      production by plasma spraying requires constant control and
                      verification due to the great complexity and the multitude
                      of influential factors. The reproducibility of the coating
                      morphologies and coating properties was ensured and further
                      developed by improving spraying operations. In spite of the
                      wear problems the Triplex torch has proved to be extremely
                      reliable and enables homogeneous and reproducible coating
                      production. The choice of the characterization method and
                      its interpretation must be critically geared. That goes
                      expecially for the porous ceramic material to be
                      investigated which shows a high density of inhomogenities.},
      cin          = {IEF-1},
      cid          = {I:(DE-Juel1)VDB809},
      shelfmark    = {FPU - Corrosion protection, surface coating},
      typ          = {PUB:(DE-HGF)29},
      url          = {https://juser.fz-juelich.de/record/136168},
}