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@INPROCEEDINGS{Grnwald:836421,
      author       = {Grünwald, Nikolas and Menzler, Norbert H. and Guillon,
                      Olivier and Vassen, Robert},
      title        = {{MICROSTRUCTURAL} {AND} {PHASE} {EVOLUTION} {OF}
                      {ATMOSPHERIC} {PLASMA} {SPRAYED} {MANGANESE} {COBALT} {IRON}
                      {OXIDE} {PROTECTION} {LAYERS} {IN} {SOLID} {OXIDE} {FUEL}
                      {CELLS}},
      reportid     = {FZJ-2017-05542},
      year         = {2017},
      abstract     = {Chromium containing steels are widely used as interconnects
                      in solid oxide fuel cell stacks (SOFCs) because of their
                      advantageous mechanical and electrical properties. The major
                      drawback of this material is the evaporation of chromium
                      containing species at the high SOFC operation temperatures,
                      which lead to a strong degradation of commonly used cathode
                      materials. Covering the interconnect’s surface with a
                      protection layer enables a strong reduction of the chromium
                      related degradation. The use of dense layers of
                      atmospherically plasma sprayed (APS) Mn1,0Co1,9Fe0,1O4 (MCF)
                      showed remarkably low degradation rates within operated
                      stacks in Jülich. Although the stacks show good
                      performance, the APS-MCF layers undergo strong changes that
                      are just partially described in literature [1,2], but not
                      fully understood yet. This study analyses the
                      microstructural evolution and phase changes of APS-MCF
                      layers within samples tested for annealing times of up to
                      10.000 hours and also within components of test stacks
                      operated at JÜLICH. A crack healing effect is observed by
                      annealing in air at low temperature of 500°C. Measurements
                      with X-ray diffraction, wet chemical analyses and thermo
                      gravimetry support a theory describing this effect by a
                      volume expansion that is induced by an oxidation process of
                      the plasma sprayed MCF. Air leakage measurements reveal a
                      strong increase of gas-tightness providing increased
                      chromium retention. Annealing at higher temperatures of
                      700°C to 850°C leads to a segregation and a phase
                      separation observed in electron microscopic images.
                      Oxidation driven diffusion of Cobalt ions to the layer’s
                      surface build up a dense Co3O4 layer in a spinel crystal
                      structure. This layer decelerates further oxidation of the
                      coatings bulk. Combining these results with the performed
                      long-term annealing tests can provide lifetime predictions
                      of APS-MCF protective layers. Thereby a reduction of the
                      cathode related degradation can be achieved.References[1] R.
                      Vaßen, N. Grünwald, D. Marcano, N.H. Menzler, R. Mücke,
                      D. Sebold, Y.J. Sohn, O. Guillon, Aging of atmospherically
                      plasma sprayed chromium evaporation barriers, Surface and
                      Coatings Technology 291 (2016) 115–122.[2] J. Puranen, M.
                      Pihlatie, J. Lagerbom, G. Bolelli, J. Laakso, L. Hyvärinen,
                      M. Kylmälahti, O. Himanen, J. Kiviaho, L. Lusvarghi, P.
                      Vuoristo, Post-mortem evaluation of oxidized atmospheric
                      plasma sprayed Mn–Co–Fe oxide spinel coatings on SOFC
                      interconnectors, International Journal of Hydrogen Energy 39
                      (2014) 17284–17294.},
      month         = {Jul},
      date          = {2017-07-09},
      organization  = {15th Conference $\&$ Exhibition of the
                       European Ceramic Society, Budapest
                       (Hungary), 9 Jul 2017 - 13 Jul 2017},
      subtyp        = {After Call},
      cin          = {IEK-1 / JARA-ENERGY},
      cid          = {I:(DE-Juel1)IEK-1-20101013 / $I:(DE-82)080011_20140620$},
      pnm          = {135 - Fuel Cells (POF3-135) / SOFC - Solid Oxide Fuel Cell
                      (SOFC-20140602) / HITEC - Helmholtz Interdisciplinary
                      Doctoral Training in Energy and Climate Research (HITEC)
                      (HITEC-20170406)},
      pid          = {G:(DE-HGF)POF3-135 / G:(DE-Juel1)SOFC-20140602 /
                      G:(DE-Juel1)HITEC-20170406},
      typ          = {PUB:(DE-HGF)6},
      url          = {https://juser.fz-juelich.de/record/836421},
}