This title appears in the Scientific Report : 2013 

Entwicklung und Herstellung von metallgestützten Festelektrolyt-Brennstoffzellen (MSC-SOFC) mit einem Sol-Gel-Elektrolyten
Vieweger, Sebastian Dieter (Corresponding author)
Werkstoffsynthese und Herstellungsverfahren; IEK-1
Jülich Forschungszentrum Jülich GmbH, Zentralbibliothek, Verlag 2013
176 S.
Dissertation, Universität Bochum, 2013
Dissertation / PhD Thesis
Fuel Cells
Schriften des Forschungszentrums Jülich Reihe Energie & Umwelt / Energy & Environment 189
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Fuel Cells are giving the opportunity to convert electric energy from fuels like hydrogen or natural gas with high efficiency. The Forschungszentrum Jülich GmbH and in particular the Institute for Energy and Climate Research, Materials Synthesis and Processing (IEK-1) have been working in the field of fuel cells for the last twenty years. A focus of the recent studies is the expansion of the fuel cell deployability to new market segments from stationary to mobile applications like auxiliary power units. In case of mobile application metal-supported solid oxide fuel cells are promising a high potential in comparison to anode supported ceramic fuel cells. Metal-supported solid oxide fuel cells are showing a higher stability against vibration, mechanical loads and rapid thermal cycling, which are boundary conditions to mobile applications. Metal-supported solid oxide fuel cells put high requirements on methods engineering and materials used during the processing steps such as thermal treatments in reducing atmosphere to protect the substrate and the anode against oxidation. Moreover such cells have also a rougher surface with large defects inside in comparison toanode supported ceramic fuel cells. This makes the deposition of thin layers a challenge and innovative solutions must be found to deal with it. The present work is concerned with the manufacturing of electrolyte layers in the range of a few micrometers on top of a metal-supported cell. The metallic support used in this work, made of a ferritic ODS (oxide dispersion strengthened) Fe-Cr alloy (ITM: Fe-26Cr-(Mo, Ti, Y2O3)), has a low shrinkage below 1 % at 1380 °C in reducing atmosphere, which inhibitsthe densification of the electrolyte. For that reason a sol-gel-electrolyte layer system, which showed first good results with anode supported systems was transferred to the metallic supported system. By modifying the setup of the layer system and the methods engineering, a graded electrolyte in the range of ~ 2 $\mu$m could be reproducibly established on top of the anode layer. The characterized densities of the electrolytes were by a factor of 2-4 times lower compared to the postulated density. Two different kinds of fabrication routes, using a graded screen printed anode layer system and a tape cast anode layer were investigated in order to deposit an anode layer on top of the porous metallic support. It could be shown that on both systems a sol gel electrolyte could be deposited in combination with a screen printed or vacuum slip casted 8YSZ adaptation layer. Further investigations including roughness parameters and a non-destructive measurement method are done and evaluated to characterize the subsurface, on which the electrolyte was deposited. With the non-contact and non-destructive measurement method it is possible to identify and characterize defects like pores and especially the boundaries of the defects in a subsurface. By using analysis-software the detected boundaries and defects could bequantified and analyzed in terms of their geometry and their surface in proportion to the scan surface. The non-destructive characterization method could be transferred and evaluated to different surfaces which are important to the anode supported ceramic fuel cell and metalsupported solid oxide fuel cell technology. The main focus of this work is the coating of thin and gas tight 8YSZ electrolyte layers by sol-gel technology on coarse porous metallic substrates and the developing and evaluating ofa non-destructive method to characterize defects and especially the boundaries of defects in the subsurface, which has to be coated.