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Synthese und Charakterisierung keramischer Schichten aus (La,Sr)(Ga,Mg)O3-x [article]

Thorsten Maldener, Universität Stuttgart, Universität Stuttgart
Aim of this thesis was the synthesis of layers of (La,Sr)(Ga,Mg)O3-x (LSGM) via a tape casting and a plasma spraying process. Thus special attention was paid to the microstructure and to a potential evaporation of components of LSGM during the manufacturing processes. As a first step the powder of LSGM starting material was prepared via mixed oxide method of oxides and SrCO3, respectively. In this study the potential evaporation of components of an LSGM solid electrolyte has been investigated
more » ... been investigated for the first time under relevant conditions of an operating SOFC. Thus annealing experiments were done. Sintered pellets of LSGM were annealed in humidified forming gas and in air at 750°C. According to the accuracy of measurement of ICP-OES-analyses there could be no change detected in the content of cations of LSGM. In this study the development of an LSGM-containing slurry has been documented for the first time. Experiments reveal that water can be used as a dispersant. PVA and PEG can be used as binder and plasticizer, respectively, as there are no interfering reactions between these chemicals and the LSGM-powder. Tape casted layers, that have been dried in air at room temperature can be removed from the plastic transparency easily and don't have any cracks. Geenlayers of LSGM-15-10-002-M show a loss of 35 weight% after drying at room temperature and furthermore a loss of 3 weight% after the burnout of the chemicals and the following sintering process. During the tape casting process there is no formation of any new secondary phases. Sintered layers are dense and don't show any cracks. There are only a few (closed) pores. Systematic sintering experiments of tape casted geenlayers of LSGM-15-10-004-G show that sintering for 6 h at temperatures of about 1525°C leads to dense microstructures with only a few pores. Usually these pores have diameters less than 20 µm. Increasing the temperature of the sintering process leads to bigger pores and to an increase of total porosity. ICP-OES-analyses of tape casted and sintered lay [...]
doi:10.18419/opus-6601 fatcat:l54tlkfs75cy3djcnk7kdk5hte