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Öğe Development of ceramic fiber reinforced glass ceramic sealants for microtubular solid oxide fuel cells(Elsevier Sci Ltd, 2022) Timurkutluk, Cigdem; Toruntay, Furkan; Onbilgin, Sezer; Atalmis, Gamze; Timurkutluk, BoraCeramic fibers in various forms with different fiber sizes are tested to improve the sealing performance of glass ceramic seals for micmtubular solid oxide fuel cell applications. In this regard, several sealing pastes are prepared by mixing each ceramic fibers type with glass ceramics at 1.25 wt %. Five layered micmtubular anode supported cells are also fabricated by extrusion and dip coating methods to evaluate the sealing performance of the composite sealants. The pastes are applied between the cells and gas manifolds made of Crofer22 APU. The electrochemical and sealing performances at an operating temperature of 800 degrees C under hydrogen are investigated after the glass forming process. Microstructures of the sealants are also examined by a scanning electron microscope. Experimental investigations reveal that the cells sealed by the pastes with ceramic bulk fiber and ceramic fiber rope gasket show acceptable open circuit potentials close to the theoretical one. These cells can be also pressurized up to around 150 kPa back pressure in the sealing performance tests. On the other hand, the pastes without any filler, with ceramic rope and with ceramic blanket exhibit poor sealing performance due to gas leakage originated from flowing of the main glass ceramic matrix from the joints. Therefore, ceramic bulk fiber and ceramic fiber rope gasket are found to behave as a stopper and can be used to prevent glass ceramics from flowing for microtubular solid oxide fuel cells or similar applications.Öğe Effect of reduced graphene oxide addition on cathode functional layer performance in solid oxide fuel cells(Pergamon-Elsevier Science Ltd, 2023) Timurkutluk, Cigdem; Zan, Recep; Timurkutluk, Bora; Toruntay, Furkan; Onbilgin, Sezer; Hasret, Onur; Altuntepe, AliSolid oxide fuel cells (SOFCs) operating at high temperatures are highly efficient electrochemical devices since they convert the chemical energy of a fuel directly into heat and electrical energy. The electrochemical performance of an SOFC is significantly influenced by the materials and microstructure of the electrodes since the electrochemical reactions in SOFCs take place at three/triple phase boundaries (TPBs) within the electrodes. In this study, graphene in the form of reduced graphene oxide (rGO) is added to cathode functional layer (CFL) to improve the cell performance by utilizing the high electrical properties of graphene. Various cells are prepared by varying the rGO content in CFL slurry (1-5 wt %), the number of screen printing (1-3) and the cathode sintering temperature (900-1100 degrees C). The electrochemical behavior of the cells is evaluated by electrochemical performance and impedance tests. It is observed that there is a similar to 26% increase in the peak performance of the cell coated with single layer CFL having 1 wt % graphene and 1050 degrees C sintering temperature, compared to that of the reference cell. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Öğe Fabrication and optimization of LSM infiltrated cathode electrode for anode supported microtubular solid oxide fuel cells(Pergamon-Elsevier Science Ltd, 2023) Timurkutluk, Cigdem; Yildirim, Fuat; Toruntay, Furkan; Onbilgin, Sezer; Yagiz, Mikail; Timurkutluk, BoraIn this study, anode supported microtubular solid oxide fuel cells (SOFCs) with LSM (lanthanum strontium manganite) catalyst infiltrated LSM-YSZ (yttria stabilized zirconia) cathodes are developed to increase the density of triple/three phase boundaries (TPBs) in the cathode, thereby to improve the cell performance. For this purpose, two different porous YSZ layers are formed on the dense YSZ electrolyte, i.e., one is with co-sintering while the other one is not. Incorporation of LSM into these porous YSZ layers is achieved via dip coating of a sol-gel based infiltration solution. The effects of the fabrication method for porous YSZ, LSM solution dwelling time and the thickness of the porous YSZ layer on the cell performance are experimentally investigated and optimized in the given order. A reference cell having a conventional dip coated cathode prepared by mixing the commercial LSM and YSZ powders is also fabricated for comparison. The results show that among the cases considered, the highest peak power density of 0.828 W/cm(2) can be obtained from the cell, whose single dip coated porous electrolyte layer co-sintered with the dense electrolyte is impregnated with LSM for a dwelling time of 45 min. On the other hand, the peak power density of the reference cell is measured as only 0.558 W/cm(2). These results reveal that similar to 50% increase in the maximum cell performance compared to that of the reference cell can be achieved by LSM infiltration after the optimizations. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Öğe Fabrication of glass ceramic sealants with ceramic fiber filler for solid oxide fuel cells(Elsevier Sci Ltd, 2022) Toruntay, Furkan; Atalmis, Gamze; Timurkutluk, Cigdem; Timurkutluk, BoraIn this study, ceramic fibers are used as a filler material for glass ceramic sealant in solid oxide fuel cells to improve the thermal cycle behavior. Beside the bare glass ceramic sealant for comparison, multilayered sealants with different ceramic fiber contents are fabricated to investigate the effect of ceramic fiber quantity also. The mechanical performances of the samples are measured via tensile tests by placing them between two metallic interconnector plates after the glass formation process as well as after 1, 5 and 10 thermal cycles. The results show that the mechanical strength in general tends to decrease with increasing the ceramic filler content, which can be attributed to poor adhesion due to reduced glass ceramic composition. On the other hand, thermal cycle behavior of the samples with ceramic fibers is found to be improved at some extend. This may be due to the behavior of ceramic filler network and relatively slow crystallization with increasing the amount of the filler as proven by microstructural observations. Especially for the sample including 4 ceramic fiber interlayers each having 0.030 g ceramic fibers, the mechanical strength shows an increasing trend with the number of thermal cycles.Öğe Katı oksit yakıt pilleri için seramik elyaf takviyeli cam seramik sızdırmazlık malzemesi geliştirilmesi(Niğde Ömer Halisdemir Üniversitesi, 2024) Toruntay, Furkan; Timurkutluk, BoraKatı oksit yakıt hücrelerinde yüksek çalışma sıcaklıkları, yüksek verim ve reaksiyon kinetiği gibi avantajları beraberinde getirmesinin yanında malzeme seçimini de oldukça sınırlandırmaktadır. Bu nedenle yakıt olarak kullanılan hidrojenin atomik yapısı gereği sızdırmazlık malzemesi ise üzerinde çalışılması gereken önemli elemanlardan birisi olarak öne çıkmaktadır. Bu tezde, katı oksit yakıt pilleri için seramik elyaf takviyeli cam seramik sızdırmazlık malzemesi geliştirilmesi üzerine çalışmalar yapılmıştır. Bu kapsamda, şerit döküm yöntemi ile imal edilen cam seramik sızdırmazlık malzemelerine seramik elyaf takviyesi yapılarak termal döngü dayanımının iyileştirilmesi amaçlanmıştır. Diğer sızdırmazlık elemanları ile kıyaslandığında iyi bir termal döngü performansına sahip olan cam seramik sızdırmazlık malzemesinin seramik elyaf katkısı ile daha uzun ömür ve daha iyi mekanik mukavemet sunduğu yapılan termal döngü ve çekme testleri ile doğrulanmış ve elde edilen sonuçlar değerlendirilmiştir.
