Mechanical Engineering / Makina Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4129
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Article Citation - WoS: 25Citation - Scopus: 26Lowering the Sintering Temperature of Solid Oxide Fuel Cell Electrolytes by Infiltration(Elsevier Ltd., 2019) Sındıraç, Can; Çakırlar, Seda; Büyükaksoy, Aligül; Akkurt, SedatA dense electrolyte with a relative density of over 95% is vital to prevent gas leakage and thus the achievement of high open circuit voltage in solid oxide fuel cells (SOFCs). The densification process of ceria based electrolyte requires high temperatures heat treatment (i.e. 1400-1500 degrees C). Thus, the minimum co-sintering temperatures of the anode-electrode bilayers are fixed at these values, resulting in coarse anode microstructures and consequently poor performance. The main purpose of this study is to densify gadolinia doped ceria (GDC), a common SOFC electrolyte, at temperatures lower than 1400 degrees C. By this aim, an approach involving the infiltration of polymeric precursors into porous electrolyte scaffolds, a method commonly used for composite SOFC electrodes, is proposed. By infiltrating polymeric precursors of GDC into porous GDC scaffolds, a reduction in the sintering temperature by at least 200 degrees C is achieved with no additives that might affect the electrical properties. Energy dispersive x-ray spectroscopy line scan analyses performed on porous GDC scaffolds infiltrated by a marker solution (polymeric FeOx precursor in this case) reveals a homogeneous infiltrated phase distribution, demonstrating the effectiveness of polymeric precursors.Article Citation - WoS: 9Citation - Scopus: 10Microstructural Investigation of the Effect of Electrospraying Parameters on Lscf Films(Elsevier Ltd., 2020) Sındıraç, Can; Akkurt, SedatIntermediate temperature solid oxide fuel cells (IT-SOFC) require an effectively functioning cathode layer whose performance depends largely on their microstructures. Improved electrochemical performance of the cathode layer can be possible by tailoring the microstructure to ensure that both the oxygen reduction reaction (ORR) occurs fast along the triple-phase boundaries (TPB) and the diffusion pathway is short enough for fast ion diffusion through the cathode layer. Electro spray deposition (ESD) method is a low-cost deposition method which allows the optimization of microstructure by changing the spraying parameters. In this study, gadolinium doped ceria (GDC) electrolyte layer is deposited with La1-xSrxCo1-yFeyO3-? (LSCF) derived from polymeric precursor salts, symmetrically. As a solvent couple, 2-butoxyethanol and ethylene glycol are used instead of the conventional solvent couples frequently employed in the literature. The use of the new type of solvents in the precursor solution leads to promising results on modifying the microstructure of the deposited layer. The effect of electrospraying parameters on the cell performance was also studied. Promising results were obtained as measured by impedance spectroscopy when this new solvent couple was employed. © 2020 Hydrogen Energy Publications LLCArticle Citation - WoS: 9Citation - Scopus: 10Formation of La1-Xsrxco1 Cathode Materials From Precursor Salts by Heating in Contact With Cgo Electrolyte(Elsevier Ltd., 2016) Sındıraç, Can; Akkurt, SedatThe purpose of this study is to determine the solid state reactions leading to the formation of La0.6Sr0.4Co0.8Fe0.2O3 and La0.6Sr0.4Co0.2Fe0.8O3 which are widely used as cathode material in solid oxide fuel cells (SOFC) from precursor salts. Interactions between the cathode and the electrolyte layers are also investigated while the cathode layer formed upon heating in contact with the surface of cerium-gadolinium oxide (CGO) electrolyte substrates. Almost all combinations of precursor salt mixtures were tested to see if all solid state reactions are completed and what phases eventually formed. Most of the transformation was complete after 1050 °C heat treatment to yield different mixed oxides. The cathode layer was usually in porous form but was found to spread well over the substrate. Uneven diffusion of La, Sr, Co or Fe into the substrate influenced the stoichiometry of the resulting cathode layer in varying degrees. Fe was found to diffuse into the substrate.