Texture formation in Al203 substrates after green forming and sintering was studied. The results can be well represented in a texture formation diagram in terms of the green texture and a sintering factor. The sintering factor is related to grain growth. It can be quantified in terms of sintering time and temperatur with a growth rate factor depending on boundary energy and mobility. Two different regions of sintering temperatures can be distinguished of which the high-temperature one is related to liquid phase sintering. Mechanical properties of the substrates were also studied, particularly thermal cycling fatigue of copper plated substrates as well as thermal shock resistence and bending fracture strength. These properties are influenced in different ways by the texture. The properties can be understood taking also the misorientation distribution of the grain boundaries into account.

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Gd 2 O 3 -doped ceria (GCO) is irreplaceable as interface/buffer layer between a mixed conducting cathode such as La0.58Sr0.4Co0.2Fe0.8O3-δ (LSCF) and an 8 mol %Y2O3 stabilized ZrO2 (8YSZ) thin film electrolyte. To meet the demands of high performance, indispensable characteristics of this interface (LSCF/GCO/8YSZ) are (i) no reaction of GCO with LSCF or YSZ and (ii) a GCO layer that is defect-free (closed porosity, no cracks). It is well known that state-of-the-art screen printed and sintered GCO buffer layers are imperfect and ultimately reduce the overall performance. This study concentrates on the evaluation of nanoscaled GCO thin films integrated into anode supported cells (ASC). GCO thin films were deposited on 8YSZ electrolyte by a low temperature metal organic deposition (MOD) process. MOD is preferable because it is a versatile technique for large scale and low cost fabrication for various material compositions. The authors investigated the influence of preparation parameters with respect to chemical homogeneity and film quality (pores, cracks) of GCO thin films with a constant film thickness between 50 nm and 100 nm. Electrochemical performance of anode supported cells employing MOD derived GCO thin films will be presented in terms of ohmic resistance (ASRΩ) and will be evaluated in contrast to screen printed and sintered GCO thick films. Nanoscale MOD derived thin films with low processing temperatures and dense film qualities were vastly superior to state-of-the-art GCO and beneficial to the overall cell performance.

Due to their direct conversion of electrochemical into electrical energy solid oxide fuel cells (SOFCs) have great potential for a future additional energy supply. Even in the last two years numerous developers of SOFCs, both industry and research institutions, have demonstrated long-term stable operation of stacks of various dimensions (ranging from 1 to 125 kWel, with durations of up to 25000 hours of operation). Besides technical proof, single component availability (cells, bipolar plates, sealing…), stable and low-aging operation, as well as cost efficient manufacturing of the components is becoming more and more evident in preparation for a market launch. Close cooperation between SOFC stack developers, SOFC users and manufacturers of powders, semifinished parts or stack components is a prerequisite for success. Within a collaboration project funded by the German Federal Ministry of Economics and Labor (BMWA) the development of an SOFC as an auxiliary power unit (APU) is being promoted. The industrial users are BMW for automotive applications and Liebherr for use in construction vehicles or aircraft. The content of this presentation will be the transfer of the manufacturing knowledge developed at Research Center Jülich to CeramTec; including on the one hand the problems and limitations and, on the other hand the successes and positive perceptions. In detail, the transfer of, for example tape casting and screen printing will be addressed, powder characteristics concerning paste or slip formulation and special tests with reference to SOFCs are presented, and single cell tests of various cells manufactured with different powders or fabrication processes are described. Additionally, some remarks will concern different priorities in either R&D or industry (e.g. R&D: high power density; industry: reproducibility), process windows for manufacturing and the search for alternative fabrication methods.