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@PHDTHESIS{Pintsuk:38424,
      author       = {Pintsuk, Gerald},
      title        = {{E}ntwicklung eines neuen {D}esign-{K}onzeptes für
                      {D}ivertorkomponenten-{I}ntegration eines funktionell
                      gradierten {W}/{C}u-Überganges. 4148},
      volume       = {4148},
      issn         = {0944-2952},
      school       = {Techn. Hochsch. Aachen},
      type         = {Dr. (FH)},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {PreJuSER-38424, Juel-4148},
      series       = {Berichte des Forschungszentrums Jülich},
      pages        = {getr. Pag.},
      year         = {2004},
      note         = {Record converted from JUWEL: 18.07.2013; Aachen, Techn.
                      Hochsch., Diss., 2004},
      abstract     = {One of the most difficult topics in the design and
                      development of future fusion devices, e.g. ITER (Latin for
                      “the way”) is the field of plasma facing components for
                      the divertor. In steady-state mode these will be exposed to
                      heat fluxes up to 20 MW/m$^{2}$. The favored design-option
                      is a component made out of tungsten and copper-alloys. Since
                      these materials differ in their thermal expansion
                      coefficient and their elastic modulus a temperature gradient
                      within the component, caused by thermal loads, results in
                      stresses at the interface. An alternative design-option for
                      divertor-components deals with the insertion of a
                      functionally graded material (FGM) between tungsten and
                      copper. This establishes a continuous change of material
                      properties and therefore minimize the stresses and optimize
                      the thermal behavior of the component. Low pressure
                      plasma-spraying and direct laser-sintering are introduced as
                      possible production-methods of graded W/Cu-composites. Based
                      on preliminary investigations both are used for fabricating
                      W/Cu-composite materials with different mixing ratios.
                      Thermo-mechanical and thermo-physical material properties
                      will be determined on these composites and extrapolated to
                      all mixing ratios. For laser-sintering these are limited to
                      Cu-contents of ~20 to 100 Vol\%. Therefore the
                      plasma-spraying process is favored. In
                      finite-element-analyses the graded material and its material
                      properties will be implemented into a 2-D simulation-model
                      of a divertor component. The composition and the design of
                      the graded W/Cu-composite will be optimized. Best results
                      are obtained by high contents of tungsten within the graded
                      layer, which are still improved by a macro-brush design with
                      dimensions of 4.5 x 4.5 mm$^{2}$. This results in a transfer
                      of critical stresses from the mechanical bonded interface
                      between the plasma facing and the graded material to the
                      diffusion bonded interface between the graded material and
                      copper. The joining of tungsten, a plasma-sprayed graded
                      W/Cu-interlayer, OFHC-Cu (Oxygen Free High Conductivity) and
                      CuCrZr will be done by Hot Isostatic Pressing. Parameters
                      are a temperature of 550°C an a pressure of 195 MPa.
                      Electrochemical deposited copper and nickel are added.
                      Copper is used as surface layer of the graded W/Cu-composite
                      and nickel for the strengthening of the diffusion bonding.
                      Ultra-sonic-testing revealed narrow areas with inhomogeneous
                      bonding at the interface, mainly nearby the outer surface of
                      the module. The module containing the macro-brush has been
                      tested at the electron-beam test facility JUDITH. It
                      survived power loads at steady state operation of 23.8
                      MW/m$^{2}$ and 150 cycles at 20 MW/m$^{2}$ during thermal
                      fatigue experiments. These results verify, that the
                      insertion of a graded W/Cu-interlayer increases the
                      resistance against thermal loads. Especially in the
                      combination with the castellated structure.},
      cin          = {IWV-2},
      cid          = {I:(DE-Juel1)VDB2},
      pnm          = {Kernfusion und Plasmaforschung},
      pid          = {G:(DE-Juel1)FUEK250},
      typ          = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
      url          = {https://juser.fz-juelich.de/record/38424},
}