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Research paper : Challenge for the development of micro SOFC manufacturing technology (Y. Fujishiro et al.)−50−Synthesiology - English edition Vol.4 No.1 (2011) ceramic base material, the control technology for forming the dense electrolyte at single m thickness was realized for the tubular cell using the dip-coating method[11]. In ordinary dip-coating method, the film formation on the exterior of the base material such as the tube was possible. However, when the electrochemical functional layer had to be formed on the interior wall of the microspace, application of an even coating on the whole surface was difficult, as the slurry would not penetrate deeply due to the balance of viscosity resistance and capillary force. The space could be filled with the slurry by flooding the interior by slurry aspiration method and then spewed out, but the film on the interior wall became thick and uneven, and the coat volume could not be controlled as the number of pinholes increased. To solve these coating process issues, a unique coating process called the slurry injection method was newly developed, where the external force that counteracted the capillary force was added to the coating paste, and the coating volume was controlled by forcefully moving the paste material[13]. With this new top-down manufacturing technology, it became possible to use the microspace in the honeycomb structures with regular 3D pinhole arrays of sub-millimeter diameter, and to form the even multilayer film with controlled film thickness. This method was important for the fabrication of the integrated module structure and for cost reduction by reducing the number of members. In the developed process, the even film coating could be formed on the substrate under the same control condition even in corner areas where the liquid tended to collect during the coating process. The controlled functional layer could be formed in the micropore with sub-millimeter diameter on the ceramics base material, using a simple coating process regardless of the shape of the pore. This developed process technology was adapted to the multilayer coating of the ceramic electrochemical structure of the electrolyte and electrode layers. By utilizing this process for the cell formation in the regular array structure with sub-millimeter diameter, the top-down manufacturing method allowed the fabrication of the electrode unit with regular array of pores in the sub-millimeter space by using the honeycomb extrusion technology, and then later forming the multilayer cell structure such as the dense electrolyte film and porous electrode by combining the coating technology. Using this technology, the dense electrolyte with thickness 10 m and the electrode with tens of m thickness on the bulk body (40 cm2/cm3, relative surface area per volume about 20 times the conventional flat SOFC) where there were hundreds of spaces at 0.5-1.0 mm diameter were successfully formed, and the new honeycomb micro SOFC was developed[13].The design-to-manufacturing process technology that was important for the integration of the micro SOFC module was built as the top-down and bottom-up manufacturing technologies, and the new manufacturing technology was presented for the 3D integrated structure in the ceramic electrochemical device manufacture.4 Realization of the new low-temperature operable micro SOFC manufacturing technology through revolutionary ceramics manufacturing technology ~ Conversion to full-fledged integrated moduleWe could now fabricate an original unprecedented micro SOFC, based on the new high-performance micro SOFC design and manufacturing technology. As a result, high performance of the micro SOFC technology was achieved in the technical indices such as size, power, temperature reduction, short startup time, and others, as shown in Table 2[14].To increase generation performance at the low temperature in micro SOFC, the reduction of the structural resistance factors such as the reaction dispersal and ohmic resistance of the cell and integrated module was essential. Much attention was devoted to the film forming technology of the electrolyte layer involved in the reduction of the resistance factors, the analysis of material contraction behaviors in the aforementioned slurry dip coating Fig. 7 Wet ceramic coating technologyDeveloped technologyInjectionVertical movementSuction by pumpSampleSlurry injectionSlurry aspirationDip coatingSlurryTable 2 Technological indices for the developed micro SOFC technologyScSZ : 10 mol% Scandia-stabilized zirconia, YSZ : 8 mol% Yttria-stabilized zirconia, GDC : 10 mol% Gadolinia doped ceria2000.3850YSZExterior diameter:2.0Adelan Ltd.(U.K.)200.45750YSZExterior diameter:10.0Korea Instituteof EnergyResearch(Korea)65 - 217**0.5 - 0.8* @ 650 ℃550 - 650ScSZ, GDCExterior diameter:0.8‐2.0(Interior diameter 0.4‐1.6)Developedmicro SOFCtechnologyStart-up speed(℃/min)Power density(W/cm2)at 0.7 VStart-uptemperature(℃)ElectrolytematerialCell diameter(mmφ)Reference) Data updated based on V. Lawlor, S. Griesser, G. Buchinger, A. G. Olabi, S. Cordiner, D. Meissner: Review of the micro-tubular solid oxide fuel cell, Part I. Stack design issues and research activities, Journal of Power Sources, 193, 387‒399 (2009).* Data for 2.0 mmφ ScSZ electrolyte micro-tubular SOFC** Demonstration data for honeycomb SOFC

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