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Öğe Boosting the performance of bolt-microtubular solid oxide fuel cells through surface pattern tuning(Elsevier Sci Ltd, 2024) Onbilgin, Sezer; Altan, Tolga; Timurkutluk, Cigdem; Timurkutluk, BoraA number of bolt-microtubular anode supports (BMASs) are manufactured by winding the corresponding thin tapes on threaded rods of different thread pitches and depths, followed by co-lamination using isostatic press. Bolt-microtubular cells (BMCs) are also constructed on BMASs to investigate the effects of the created surface patterns on the cell performance and microstructure. The bolt-microtubular cell, whose anode support is patterned by using a threaded rod with 0.8 mm thread pitch and 0.4 mm thread depth, exhibits similar to 92% higher maximum performance than that of the reference cell at 800 degrees C under 0.3 NL/min hydrogen flow and stagnant air. The almost doubled performance is mainly due to the increase in anode-electrolyte and cathode-electrolyte interfacial areas by the surface patterns created. The cell is also subjected to a 200-h life test at 800 degrees C and 0.7 V and demonstrates a stable performance.Öğe Crystalline-silicon heterojunction solar cells with graphene incorporation(Elsevier, 2021) Zan, Recep; Altuntepe, Ali; Altan, Tolga; Seyhan, AyseAmongst the silicon (Si)-based photovoltaics, heterojunction solar cells are the most promising solar cells due to their low thermal coefficient, high efficiency, and compatibility with newly emerged materials, such as graphene and perovskite. Studies on Si-based solar cells with graphene have increased dramatically in recent years. Thus far, high power conversion efficiency has been achieved up to 15 % by integrating graphene into graphene/Si Schottky junction solar cells since graphene has excellent electrical and optical properties. © 2021 Elsevier Inc.Öğe Design and optimization of functionally graded anode electrode with integrated functional layer for microtubular solid oxide fuel cells(Elsevier Sci Ltd, 2024) Timurkutluk, Cigdem; Altan, Tolga; Onbilgin, Sezer; Timurkutluk, BoraThis study investigates the influence of porosity-graded anode microstructures on the performance of microtubular solid oxide fuel cells (SOFCs). Fabricated using tape casting coupled with isostatic pressing, the anode microtubes consist of three layers with varying porosities. The porosity of each layer is regulated by the quantity of pore former added to the corresponding tape casting slurry. Homogeneous microtubular anode supports having different porosities are also fabricated similarly for comparison purposes. Microtubular cells are manufactured on both types of anodes by dip coating other cell layers, and test and characterization studies are carried out. Experimental results reveal that increasing the pore former content in the anode tape casting slurry leads to reduced triple phase boundary (TPB) density, primarily due to increased porosity and pore size, resulting in higher charge transfer resistance and decreased cell performance, despite an associated decrease in the gas transport resistance. However, optimization of the anode microstructure demonstrates that porosity gradients can enhance gas transport and overall cell performance. Additionally, the study explores the impact of anode thickness and the presence of transition layers on cell performance and structural integrity.Öğe Effect of surface roughness of the metallic interconnects on the bonding strength in solid oxide fuel cells(Pergamon-Elsevier Science Ltd, 2020) Altan, Tolga; Celik, SelahattinIn this study, the joint strengths of glass-ceramic sealant placed between two metallic interconnectors (Crofer (R) 22 APU) are experimentally investigated depending on the surface conditions of the metallic interconnector and electrolyte/electrode materials (YSZ and NiO). The surfaces of the interconnectors are sanded with sandpaper having five different grits (60, 120, 240, 320 and 2000 grits). Thus, roughened surfaces are obtained and the adhesion is examined for each case. Profilometer is used to inspect the surface roughness of the samples. The fracture strengths of 24 samples prepared for each case are determined via tensile tests. Similarly, different electrolyte/electrode materials with modified surfaces are sandwiched between two glass ceramic layers and their mechanical performances are also measured. The results reveal that the joining strength tends to increase with the amount of surface roughness. It is also found that NiO adheres better to glass-ceramic material than YSZ. The microstructures of the adhesion interface of some cases are also investigated by a scanning electron microscopy. The images showed that good adhesion is achieved without any delamination or cracks at the interfaces. Chemical formation between the glass-ceramic sealants, interconnects and SOFC components is further investigated by XRD analyses. (c) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Öğe Effects of tape thickness on the fabrication and performance of microtubular solid oxide fuel cells manufactured by tape casting(Pergamon-Elsevier Science Ltd, 2024) Altan, Tolga; Onbilgin, Sezer; Timurkutluk, Cigdem; Timurkutluk, BoraThe role of tape thickness in the fabrication of microtubular anode supports for solid oxide fuel cells (SOFCs) by tape casting and isostatic pressing is investigated in this study. The anode support slurry of the same formulation is tape cast by varying the doctor blade gap (DBG) from 100 mu m to 700 mu m and the obtained tapes are wrapped at different lengths on a metal pin of 5 mm in diameter, while the appropriate tape length for each DBG is decided by considering anode support microtubes with a similar geometry for a reasonable comparison. The analyses reveal that the microstructure of the anode support microtube varies depending on DBG and in general delamination and crack formations occur in the supports at high DBGs. The resultant porosity and pore/grain sizes are also found to be different depending on DBG. Therefore, the supports and the cells with these supports show different mechanical and electrochemical performances. In this regard, DBG of 300 mu m provides microtubular anode supports without any microstructural problems. The microtubular cell built on this support also exhibits the highest peak performance of 0.313 Wcm(-2) at an operating temperature of 800 degrees C under 300 sccm hydrogen flow and open cathode condition.Öğe Engineering solid oxide fuel cell electrode microstructure by a micro-modeling tool based on estimation of TPB length(Pergamon-Elsevier Science Ltd, 2021) Timurkutluk, Bora; Altan, Tolga; Toros, Serkan; Genc, Omer; Celik, Selahattin; Korkmaz, Habip GokayIn this study, a typical solid oxide fuel cell (SOFC) electrode microstructure is numerically optimized in terms of the volume fraction of the catalyst, electrolyte and pore phases via a novel tool based on Dream.3D for the synthetic microstructure reconstruction and COM-SOL Multiphysics (R) Modeling for visualizing and computing three/triple phase boundaries (TPBs). First, the properties of the representative volume element are studied by a parameter independence analysis based on the average particle size. The results indicate that the size of the representative volume element should be at least 10 times greater than the largest average particle size in the microstructure, while the number of mesh elements should be selected such that the smallest average particle size in the system is divided into at least 5. The method is then validated with the available studies in the literature and seems to agree well. Therefore, numerical reconstruction of SOFC electrodes by the pro-posed method is found to be a very useful tool in the viewpoints of accuracy, flexibility and cost. Finally, SOFC electrode microstructures having the same particle size distribution of an average particle size of 0.5 mm for each phase but with various phase volume fractions are generated and the resultant TPBs are computed similarly. It is found out that the volume fraction of each phase should be close to each other as much as possible to maximize the active TPB density and among the cases considered, the highest active TPB density of 9.53 mm/mm(3) is achieved for an SOFC electrode including 35 vol% catalyst, 35 vol % electrolyte and 30 vol% porosity. The active TPB density is also found to be around 93% of the total TPB density. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Öğe Estimation of microscale redox tolerance for Ni-based solid oxide fuel cell anodes via three-dimensional finite element modeling(Pergamon-Elsevier Science Ltd, 2023) Altan, Tolga; Celik, Selahattin; Toros, Serkan; Korkmaz, Habip Gokay; Timurkutluk, BoraReduction-oxidation (redox) cycles of Ni-based anodes in solid oxide fuel cells (SOFCs) directly affect the cell performance due to breaking anode three/triple phase boundary (TPB) networks at microscale. Furthermore, these microcracks accumulate with the number of redox cycles leading to mechanical damage in the cell as a result of continuous volumetric changes during the inevitable cyclic reduction and oxidation of the nickel oxide and nickel, threatening the service life of SOFC systems. Therefore, the redox process needs to be investigated as a phenomenon at microscale to understand and minimize its effects. In this regard, we suggest a microscale approach for the redox process of Ni-based SOFC anodes in this study. For this purpose, SOFC anode microstructures with different compositions and porosities are synthetically generated by Dream.3D software and me-chanical damages due to the redox cycle are investigated via element deletion through LS-DYNA for the first time in the literature. The anodes are characterized by computing the redox tolerance based on the resultant damage and the anode composition showing the highest redox tolerance is determined among the cases considered.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Öğe Evaluation of anode support microstructure in solid oxide fuel cells using virtual 3D reconstruction: A simulation study(Pergamon-Elsevier Science Ltd, 2024) Timurkutluk, Bora; Ari, Ali; Altan, Tolga; Genc, OmerIn this study, the impact of microstructural properties of the anode support layer (ASL) composed of catalyst, electrolyte and pore phases on the performance of solid oxide fuel cell (SOFC) is investigated. Synthetic SOFC anode microstructures, comprising two layers including the anode functional layer (AFL), where electrochemical reactions take place, are generated using an open-source software. Different configurations of the anode support layer with various particle sizes and volume fractions of the catalyst and electrolyte phases for different porosities are combined with a consistent AFL to isolate the effect of ASL microstructural parameters. The triple phase boundary (TPB) density, chosen as a useful metric monitoring the anode performance, is then quantitively determined for each anode layer and entire anode in all reconstructed microstructures. The results demonstrate that the microstructure of ASL significantly influences the anode and thus cell performance by impacting reactant gas supply and current collection, emphasizing the necessity for meticulous design. Specifically, ASL microstructures with low volume fractions of Ni and the pore phase, and/or substantial differences between the volume fractions of the phases, are observed to result in discontinuous phase networks, which deactivate TPBs in AFL.Öğe Experimental investigation on the effect of anode functional layer on the performance of anode supported micro-tubular SOFCs(Pergamon-Elsevier Science Ltd, 2022) Timurkutluk, Cigdem; Bilgil, Keremhan; Celen, Ali; Onbilgin, Sezer; Altan, Tolga; Aydin, UgurIn this study, anode supported micro-tubular solid oxide fuel cells (SOFCs) are fabricated by extrusion method and the effects of powder size, thickness and sintering temperature of the anode functional layer (AFL) on the electrochemical performance is experimentally investigated. For this purpose, four different commercial NiO powders are tested as initial powder for the fabrication of the anode functional layer. The thickness of AFL is also considered by varying the number of coatings. After deciding the optimum initial NiO powder size used in AFL and AFL thickness, the effect of pre-sintering temperature is examined. The performance tests are performed at an operating temperature of 800 degrees C under hydrogen and air. The microstructures of the samples are also investigated by a scanning electron microscope. The best peak power density is obtained as similar to 0.5 W/cm(2) from the cell having a single layer anode functional layer pre-sintered at 1250 degrees C prepared by NiO powders with 4 m(2)/g surface area. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Öğe GÜÇLENDİRİLMİŞ İYON BOMBARDIMANI ve TARAMALI ELEKTRON MİKROSKOBU ile KATI OKSİT YAKIT PİLİNİN ÜÇ BOYUTLU ANOT MİKRO YAPISININ OLUŞTURULMASI(2020) Çelik, Selahattin; Altan, TolgaKatı oksit yakıt pillerinde (KOYP) hücre performansının düşmesinin en önemli nedenlerinden biri anot elektrotununbozulmasıdır. Anot mikro yapısının iyileştirilmesi için çok uzun süreçli deneyler yapılması gerektiğinin yanı sıra sayısal model geliştirerek sonuçların tahmin edilmesi de mümkün olabilmektedir. Fakat sayısal modeller genelde makro ölçekte yapıldığı için mikro yapıyı tam olarak temsil edememektedir. Yeni bir teknik olan Güçlendirilmiş İyon Bombardımanı ve Taramalı Elektron Mikroskobunun (GİB-SEM) birlikte kullanılması ile KOYP anot mikro yapısının üç-boyutlu görüntüsü elde edilebilmektedir.Böylece gerçek mikroyapı üzerindeki sayısal çalışmaların yapılması mümkün hale gelmektedir. Bu çalışmada GİB-SEM tekniği kullanarak laboratuvar ölçeğinde imal edilmiş bir KOYP hücresinin anot elektrotunun üç-boyutlu mikro yapısının elde ediliş basamakları gösterilmiştirÖğe Impact of lamination conditions on microtubular solid oxide fuel cells fabricated by tape casting coupled with isostatic pressing(Elsevier, 2022) Altan, Tolga; Timurkutluk, Cigdem; Timurkutluk, BoraAnode support microtubes are fabricated by tape casting and isostatic pressing as an alternative method to conventional extrusion for microtubular solid oxide fuel cells (SOFCs). Continuous NiO (nickel oxide)-YSZ (yttria stabilized zirconia) strip manufactured by tape casting is rolled around a metal pin followed by isostatic pressing, which makes the isostatic pressing step significant. Therefore, isostatic pressing process parameters yielding high performance microtubular anode supports in the structural, mechanical and electrochemical points of view are experimentally determined. For this purpose, different support microtubes are fabricated by varying the pressure, temperature and duration for the isostatic pressing. The microstructural and mechanical properties of the microtubes are determined by a scanning electron microscope and three point bending test, respectively, whereas different microtubular cells are manufactured based on these supports to measure their electrochemical performance. The results show that the optimum pressure, temperature and duration for the isostatic pressing should be at least 70 MPa, 60 C and 4 min, respectively, to obtain robust supports without any structural defects. The cells based on these supports also exhibit similar performances at all temperatures studied. Therefore, the suggested method is considered appropriate to fabricate support tubes/microtubes for SOFCs regarding the mechanical and electrochemical performance.Öğe Improving the electrochemical performance of solid oxide fuel cells by surface patterning of the electrolyte(Elsevier, 2021) Timurkutluk, Cigdem; Altan, Tolga; Yildirim, Fuat; Onbilgin, Sezer; Yagiz, Mikail; Timurkutluk, BoraThe effect of electrolyte surface patterning on the cell performance is investigated. The patterning process is accomplished by isostatically pressing the electrolyte together with a metal mesh placed on one surface of the electrolyte. In this respect, various electrolyte supports with different surface patterns are fabricated by altering the lamination conditions. Surface analyzes reveal that it is possible to modify the electrolyte surface with consistent patterns by the method suggested and some patterns are also formed on the untreated surface of the electrolyte. Electrolyte supported cells are also built on the patterned electrolyte and tested. Among the cases studied, the highest peak performance of 0.44 Wcm (-2) at 800 degrees C is reached from the cell with an electrolyte support subjected to isostatic pressing with a mesh under 50 MPa pressure and 70 degrees C temperature for 4 min after uniaxially pressing under 20 MPa for 4 min. This electrolyte also shows the lowest average roughness and average depth of the patterns formed. The reference cell with a flat electrolyte, on the other hand, provides 0.32 Wcm(-2) peak power density under the same testing conditions, indicating similar to 38% performance enhancement with the simple method recommended. Impedance measurements are also taken and discussed.Öğe Manufacturability of bolt-microtubular anode supports for solid oxide fuel cells(Elsevier, 2024) Timurkutluk, Bora; Onbilgin, Sezer; Altan, Tolga; Timurkutluk, CigdemThe effects of anode support tape length on the manufacturability and level of surface patterning in bolt-microtubular anode supports (BMASs) for solid oxide fuel cells (SOFCs) are investigated in this study. Continuous anode support tapes of similar to 5-25 cm are wrapped on a threaded rod for this purpose and five-layered boltmicrotubular cells (BMCs) are manufactured on these supports. Similarly, microtubular anode supports (MASs) by using a pin and corresponding microtubular cells (MCs) are also fabricated and examined for comparison. The tape lengths <= 9.9 cm yield mechanically unstable BMASs or BMSs due to fractures that occur during sintering in the anode supports or during testing in the cells. The electrochemical performance tests show that all BMCs exhibit relatively higher performances compared to those of MCs for a certain tape length. The highest maximum power density of 0.479 Wcm(-2) at 800 degrees C operating temperature is obtained from BMC prepared with 12 cm long anode support tape, whereas that of MC fabricated with the same anode support length is measured as 0.313 Wcm(-2) under the same testing conditions. The impedance measurements reveal that the improvement in the cell performances is due to reduced electrode polarization resistance achieved by the bolt-like microtube design.Öğe Mesh patterned electrolyte supports for high-performance solid oxide fuel cells(Wiley, 2022) Timurkutluk, Cigdem; Altan, Tolga; Onbilgin, Sezer; Yildirim, Fuat; Yagiz, Mikail; Timurkutluk, BoraIn this study, the surface of solid oxide fuel cell electrolyte is decorated with different patterns by mesh pressing to improve the cell performance by increasing the surface area of electrolyte-electrode interfaces. Six various woven and unwoven metal meshes with different mesh gaps are considered in this respect. The patterned electrolyte surfaces are scanned by a profilometer to obtain the surface properties created by each mesh. Electrolyte supported cells are fabricated and tested to investigate the effects of electrolyte surface patterning on the cell performance. A cell with a flat electrolyte support is also manufactured and tested as a reference case. Impedance analyses are performed for a detailed examination beside microstructural observations via a scanning electron microscope. Under the same lamination conditions, woven meshes provide surface patterns with relatively higher average roughness values. Among the cases studied, the cell treated with a woven mesh having 0.57-mm wire diameter and 2-mm mesh gap on a side exhibits the highest maximum performance of 0.626 W cm(-2) at 800 degrees C, whereas that of the reference cell is only 0.320 W cm(-2), indicating that the performance of the reference cell can be almost doubled by the simple method suggested in this study. The impedance results show that the improvement in the cell performances is due to reduced electrode polarizations and ohmic resistance via mesh pressing, resulted from increased surface area of electrode-electrolyte interfaces and partially reduced electrolyte thickness as confirmed by microstructural observations, respectively.Öğe Microstructural design of solid oxide fuel cell electrodes by micro-modeling coupled with artificial neural network(Elsevier, 2023) Timurkutluk, Bora; Ciflik, Yelda; Sonugur, Guray; Altan, Tolga; Genc, Omer; Colak, Andac BaturArtificial neural network (ANN) is used to model active three/triple phase boundaries (TPBs) in solid oxide fuel cell (SOFC) electrodes composed of phases with various particle sizes for the first time in the literature. Electrode microstructures comprising catalyst, electrolyte and pore phases with the same volume fraction, but various mean particle sizes are synthetically generated via Dream.3D software and the active TPB densities are measured by COMSOL software to obtain input data for training the ANN models as well as to validate the network results. In this regard, three learning methods of Bayesian regulation (BR), Levenberg-Marquardt (LM) and Scaled conjugate gradient (SCG) with various hidden layer and neuron numbers are examined. Among ANN models with three inputs and one output, the model with BR including one hidden layer and five neurons performs the best. This model revealing an average relative error of only 0.036 is then employed to simulate SOFC electrodes microstructures with new particle sizes not introduced in the learning process. The active TPB densities estimated by ANN are found to agree well with the computed ones. Therefore, ANN modeling is considered as a useful tool for the prediction of active TPB density in SOFC electrodes after a careful selection of backpropagation method and network structure.Öğe Nikel temelli katı oksit yakıt pili anotlarındaki redoks davranışının mikroyapısal incelenmesi(Niğde Ömer Halisdemir Üniversitesi, 2023) Altan, Tolga; Çelik, SelahattinKOYP anotlarında performans ve redoks toleransı açısından optimum kompozisyon oranlarının belirlenmesi için sayısal çalışmalar gerçekleştirilmiş ve bu kapsamda 3B sentetik mikroyapı üretimi önerilmiştir. Dream.3D programı ile üretilen sentetik mikroyapıların mikro ölçekli performans analizi COMSOL programı ile gerçekleştirilmiş olup redoks analizlerinde ise LS-DYNA programı kullanılmıştır. En yüksek aktif TPB yoğunluğunu %30 Gözenek, %35 Ni ve %35 YSZ kompozisyon oranlarında; en yüksek redoks toleransı ise %50 Gözenek, %15 Ni ve %35 YSZ durumunda elde edilmiştir. Anot mikroyapısının incelenebilmesi ve redoks sürecinin TPB üzerindeki etkilerinin deneysel olarak analiz edilebilmesi için ise üretilen hücreler 30 redoks döngüsüne maruz bırakılmış ve her redoks adımı sonrası hücre performans testleri gerçekleştirilmiştir. Ardından seçilen belirli redoks adımları sonrasında mikroyapısal analizlerin gerçekleştirileceği 2B görüntüler düşük voltaj FE-SEM tekniği ile elde edilmiştir. Görüntü işleme sonrasında elde edilen hacimsel oran ve partikül boyutu/dağılımı verileri sayesinde 3B mikroyapılar sentetik olarak üretilmiş ve TPB ölçümleri gerçekleştirilmiştir. Bu sayede redoks sürecinin mikroyapısal performansa etkisi incelenmiş ve hücre performansı ile TPB yoğunluğu arasındaki ilişkinin deneysel olarak gözlemlenmesi amaçlanmıştır.Öğe Novel concept of bolt-microtubular geometry for solid oxide fuel cells(Elsevier, 2023) Altan, Tolga; Timurkutluk, Cigdem; Onbilgin, Sezer; Timurkutluk, BoraThis study introduces a proof of concept for a novel solid oxide fuel cell geometry called bolt-microtubular. Bolt-microtubular anode supports are formed by winding tape cast anode support strip on a threaded rod followed by isostatic pressing. Bolt-microtubular cells are built by dip coating other cell layers on these supports. Conventional microtubular anode supports and cells are also fabricated similarly for comparison and, microstructural, mechanical and electrochemical investigations are carried out. Different anode current collection strategies are also examined. The results indicate that with the proposed methods thread patterns can be successfully created on the anode supports and bolt-microtubular anode supports without any structural damages can be obtained after sintering. Although three point bending tests show similar to 27% decrease in the fracture strength of the anode supports with bolt-microtubular design for the wall thickness studied, bolt-microtubular cells outperform microtubular ones due to enhanced electrolyte-electrode interfaces and effective current collection. The highest peak electrochemical performance of 0.293 Wcm(-2) at 800 degrees C is obtained from the bolt-microtubular cell with external current collection, whereas the maximum power density of classical microtubular cell under the same operating conditions is 0.227 Wcm(-2). The overall results reveal that bolt-microtubular design is promising and deserves further investigations.Öğe Quantitative estimation of triple phase boundaries in solid oxide fuel cell electrodes via artificial neural network(Elsevier Sci Ltd, 2024) Timurkutluk, Bora; Ciflik, Yelda; Sonugur, Guray; Altan, Tolga; Genc, OmerVirtual solid oxide fuel cell (SOFC) electrode microstructures composed of pore, electrolyte and catalyst phases with various particle sizes and volume fractions are reconstructed to design high-performance electrodes by investigating the role of microstructural properties on the electrodes and thereby the cell performance. The active TPB (triple phase boundary) densities in these microstructures are numerically measured and the data are used to train numerous artificial neural networks established with different model parameters and learning methods. Based on the results of 10,000 trainings of each model, the network that employs a backpropagation method of Bayesian regulation and has 2 hidden layers with 15 neurons is found to be the best one. It is then used to simulate new cases, whose parameters are in the range of those used in training. Further validation of the best network is also performed by considering a few randomly selected cases. The simulation results providing active TPB densities quantitatively are discussed regarding the microstructural properties. The overall results reveal that active TPBs can be increased by reducing the particle size of the phases and volume fraction of any phase should be selected according to the particle size to improve the number of active TPBs.Öğe Silisyum hetero-eklem güneş hücrelerinde ön yüz metalizasyon optimizasyonu ve alternatif ön yüz metalizasyon yöntemi(Niğde Ömer Halisdemir Üniversitesi / Fen Bilimleri Enstitüsü, 2018) Altan, Tolga; Alkan, Mahmut; Seyhan, AyşeGüneş hücre teknolojileri alanında maliyeti düşürmek ve verimliliği artırmak başlıca çalışma konuları arasındadır. Bu tezde, güneş hücresi üretiminde alttaştan sonra en etkili maliyet unsuru olan metalizasyon işlemi üzerine çalışmalar yapılmıştır. Bu kapsamda, güneş hücrelerinin ön yüz metalizasyon tasarımının optimize edilmesi ile yüksek verimli ve maliyet etkin a-Si:H/c-Si heteroeklem güneş hücrelerinin üretilmesi amaçlanmıştır. Hâlihazırda yüksek verimli olan bu güneş hücrelerine optimizasyonu yapılmış ön yüz metalizasyon tasarımları uygulanmış ve elde edilen verim değerleri karşılaştırılmıştır. Ayrıca ön yüz metalizasyon yöntemleri içerisinde en yaygın kullanılan serigrafik baskı yöntemine alternatif olarak fiziksel buhar kaplama (PVD) yöntemi maske yardımı ile gerçekleştirilmiş ve elde edilen sonuçlar yorumlanmıştır. Anahtar Sözcükler: Güneş hücresi, HIT, metalizasyon, ön yüz metalizasyon, ince akım toplayıcı, kalın akım toplayıcı, Serigrafik baskı, PVDÖğe Synthetical designing of solid oxide fuel cell electrodes: Effect of particle size and volume fraction(Pergamon-Elsevier Science Ltd, 2022) Timurkutluk, Bora; Ciflik, Yelda; Altan, Tolga; Genc, OmerSolid oxide fuel cell (SOFC) electrode microstructures composed of catalyst, electrolyte and pore phases with various microstructural features are synthetically generated and the effects of the mean particle size and volume fraction of each phase on three/triple phase boundaries (TPBs) are computed. For mono-sized particles with an equal volume fraction, the active and total TPB density are found to decrease with increasing the mean particle size due to decreased surface area. However, both are found to be inversely related to the square of the mean particle size. Active TPB densities of 37.62 mu m mu m(-3), 9.27 mu m mu m(-3) and 4.11 mu m mu m(-3) are obtained from the electrode microstructures with mono-sized particles of 0.25 0.50 mu m and 0.75 mu m mean particle size, respectively. Moreover, similar to 94% of the total TPB density is determined to be active regardless of the mean particle size. TPBs for the polydisperse particles with the same volume fraction also show a decreasing trend with the mean particle size in general. However, no significant change is observed in inactive TPB formations even for the largest particle size investigated, revealing almost fully percolated phases can be achieved when the volume fraction of each phase is equal (similar to 33.3%). On the other, when the volume fractions are also varied, the active TPB is shown to be strongly depended on the volume fraction of the phase having the highest mean particle size. In this regard, among the related cases studied, the lowest active TPB density is computed as 0.25 mu m whereas the highest one is measured as 26.64 mu m. (C) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
