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@PHDTHESIS{He:840326,
      author       = {He, Wenting},
      title        = {{D}eposition {M}echanisms of {T}hermal {B}arrier{C}oatings
                      ({TBC}s) {M}anufactured by {P}lasma{S}pray-{P}hysical
                      {V}apor {D}eposition ({PS}-{PVD})},
      volume       = {398},
      school       = {Universität Bochum},
      type         = {Dissertation},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2017-07868},
      isbn         = {978-3-95806-275-7},
      series       = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
                      Umwelt / Energy $\&$ Environment},
      pages        = {ix, 162 S.},
      year         = {2017},
      note         = {Universität Bochum, Diss., 2017},
      abstract     = {Plasma spray-physical vapor deposition (PS-PVD) is a
                      promising technology to produce columnar structured ceramic
                      thermal barrier coatings with excellent performance at high
                      deposition rates. In the PS-PVD process, major fractions of
                      the feedstock powder can be evaporated so that coatings are
                      deposited mainly from the vapor phase similar to electron
                      beam-physical vapor deposition (EB-PVD). But, unlike
                      conventional PVD processes, the interaction between plasma
                      flow and vapor species incombination with the higher chamber
                      pressure makes non-line of sight deposition possible to
                      deposit coatings on shadowed parts of the substrate. The
                      different processing parameters can definitely affect the
                      coating growth mechanisms in PS-PVD. However, their
                      relations to deposition mechanisms which are significant for
                      coating development are still not very clear and relevant
                      reports are limited. In this work, the characteristics of
                      plasma jets generated in the PS-PVD process by standard
                      plasma gases, Ar, He and H$_{2}$, have been studied by
                      optical emission spectroscopy. Abel inversion was introduced
                      to reconstruct the spatial characteristics. In the central
                      area of the plasma jet, the ionization of Ar was found to be
                      one of the reasons for low emission of atomic Ar. The
                      excitation temperature of Ar was calculated by the Boltzmann
                      plot method. Its value decreased from the center to the edge
                      of the plasma jet. Applying the same method, a spurious high
                      excitation temperature of He was obtained, which could be
                      caused by the strong deviation from local thermal
                      equilibrium of He. The addition of H$_{2}$ into plasma gases
                      leads to a lower excitation temperature, however a higher
                      substrate temperature due to the high thermal conductivity
                      induced by the dissociation of H$_{2}$. A loading effect is
                      exerted by the feedstock powder on the plasma jet, which was
                      found to reduce the average excitation temperature
                      considerably by more than 700 K in the Ar/He jet. This
                      characterization of plasma jets under PS-PVD conditions was
                      an important basis for the following studies of the columnar
                      structured YSZ coatings. They were investigated with respect
                      to the powder feeding rate, the agglomeration of feedstock,
                      deposition rate, substrate surface temperature, vapor
                      incidence angle, and flow condition. With increasing powder
                      feeding rate, the efficiency of heat transfer from plasma to
                      the powder declined gradually followed by a lower
                      evaporation rate of the feedstock. Hence, a moderate powder
                      feeding rate and agglomeration of feedstock by organic
                      binder should be used in PS-PVD to achieve effective
                      feedstock evaporation and thus vapor deposition. The
                      observation on initial deposits indicates that faceted
                      crystals are deposited from vapor phase. Based on electron
                      backscatter diffraction [...]},
      cin          = {IEK-1},
      cid          = {I:(DE-Juel1)IEK-1-20101013},
      pnm          = {113 - Methods and Concepts for Material Development
                      (POF3-113) / HITEC - Helmholtz Interdisciplinary Doctoral
                      Training in Energy and Climate Research (HITEC)
                      (HITEC-20170406)},
      pid          = {G:(DE-HGF)POF3-113 / G:(DE-Juel1)HITEC-20170406},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      url          = {https://juser.fz-juelich.de/record/840326},
}