Browsing by Author "Yurddaskal M."
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Item Fabrication and characterization of nanostructured anatase TiO2 films prepared by electrochemical anodization and their photocatalytic properties(Elsevier Ltd, 2015) Yurddaskal M.; Dikici T.; Yildirim S.; Yurddaskal M.; Toparli M.; Celik E.In this study, nanostructured anatase titanium dioxide (TiO2) films were fabricated by electrochemical anodization of titanium first, and then annealed at 500 °C for 2 h. Effect of electrolyte concentration, anodization time and electrolyte temperature on the surface morphology of the resulting TiO2 thin films were investigated. The phase structures, surface morphology and chemical composition were analyzed using X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity tests of the samples were evaluated by the degradation of aqueous methylene blue (MB) solutions under UV light illumination for different periods of time. The results showed that the structure of nanostructured TiO2 films depended strongly on the anodization parameters. It was found that there were micro-scale pores (<10 μm) and nano-scale pores (diameter in the range from 40 to 70 nm) on the anodized titanium surfaces. This study indicated that structures, surface morphology, and surface area of the nanostructured anatase TiO2 films played an important role on their photocatalytic performance. The results clearly proved that nanostructured anatase TiO2 film prepared with optimum process parameters resulted in enhancement of the photocatalytic activity. © 2015 Elsevier B.V.Item Synthesis and characterization of Ag doped TiO 2 heterojunction films and their photocatalytic performances(Elsevier B.V., 2016) Demirci S.; Dikici T.; Yurddaskal M.; Gultekin S.; Toparli M.; Celik E.In this study, undoped and silver (Ag) doped titanium dioxide (TiO 2 ) films were successfully synthesized by sol-gel spin coating technique on the Si substrates. Photocatalytic activities of the TiO 2 films with different Ag content were investigated for the degradation of methylene blue (MB) under UV light irradiation. The crystal phase structure, surface morphology, chemical and optical properties of Ag-doped TiO 2 films were characterized using an X-ray diffractometer (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV–vis spectrophotometer, and FTIR spectrophotometer. The results showed that the Ag-doped TiO 2 films calcined at 500 °C had the crystalline anatase phases and the surface morphologies with some cracks. Ag substitution into TiO 2 matrix enhanced the photocatalytic activity of TiO 2 films under UV light irradiation as compared to the undoped TiO 2 film. Furthermore, the results indicated that the 0.7% Ag doped TiO 2 film exhibited a superior photocatalytic activity than that of undoped and other Ag-doped TiO 2 films. This study demonstrated the potential of an application of Ag doped films to efficiently treat dissolved organic contaminants in water. © 2016 Elsevier B.V.Item The effect of curvature on the impact response of foam-based sandwich composite panels(Techno Press, 2016) Yurddaskal M.; Baba B.O.The aim of this study is to investigate the impact behavior and impact-induced damage of sandwich composites made of E-glass/epoxy face sheets and PVC foam. The studies were carried out on square flat and curved sandwich panels with two different radius of curvatures. Impact tests were performed under impact energies of 10 J, 25 J and 80 J using an instrumented drop-weight machine. Contact force and displacement versus time and contact force-displacement graphs of sandwich panels were presented to determine the panel response. Through these graphs, the energy absorbing capacity of the sandwich panels was determined. The impact responses and failure modes of flat and curved sandwich panels were compared and the effect of curvature on sandwich composite panel was demonstrated. Testing has shown that the maximum contact force decrease while displacement increases with increasing of panel curvature and curved panels exhibits mixed failure mode, with cylindrical and cone cracking. Copyright © 2016 Techno-Press, Ltd.Item Enhanced photocatalytic properties of Sn-doped ZnO nanoparticles by flame spray pyrolysis under UV light irradiation(Turkish Chemical Society, 2018) Yurddaskal M.; Yildirim S.; Dikici T.; Yurddaskal M.; Erol M.; Aritman I.; Celik E.Zinc oxide (ZnO) is widely used in different areas thanks to its unique photocatalytic, optic and electrical properties. Sn doped ZnO nanoparticles were synthesized through flame spray pyrolysis (FSP) technique. The Sn dopant concentrations were 1, 3, 5, 7 and 9 at. % in produced ZnO nanoparticles. The structural analysis of the produced powders was performed by X-Ray Diffraction (XRD) methods. The surface morphology and particle size distribution of the nanoparticles were identified using scanning electron microscopy (SEM), and dynamic light scattering (DLS) techniques. In addition to this, produced photocatalysts were evaluated for degradation of aqueous methylene blue (MB) solutions under UV light irradiation. Sn-doped nanoparticles have superior photocatalytic activity compared to un-doped ZnO. © 2018, Turkish Chemical Society. All rights reserved.Item Effects of Zn-doping on the photocatalytic activity and microstructures of nanocrystalline SnO2 powders(Turkish Chemical Society, 2018) Yurddaskal M.; Yildirim S.; Dikici T.; Yurddaskal M.; Erol M.; Aritman I.; Uygun H.D.E.; Celik E.In this study, undoped and Zn-doped SnO2 nanoparticles in different concentrations were synthesized by flame spray pyrolysis (FSP) technique. The produced particles were post-annealed after FSP process at 600 °C in order to obtain a crystalline structure. The structural analysis of the produced powders was performed by X-Ray Diffraction (XRD) methods. The surface morphology of the nanoparticles was identified using scanning electron microscopy (SEM). In addition, photocatalytic degradation of aqueous methylene blue (MB) solutions were evaluated using undoped and Zn-doped SnO2 nanoparticles under UV light illumination. Photocatalytic degradation of the MB solutions followed the pseudo-first-order-kinetics and the effect of the Zn doping amount on the photocatalytic reaction was investigated. © 2018, Turkish Chemical Society. All rights reserved.Item The effect of foam properties on vibration response of curved sandwich composite panels(Elsevier Ltd, 2018) Yurddaskal M.; Ozmen U.; Kir M.; Okutan Baba B.In this study, a numerical and experimental study was carried out to determine the effects of variables such as curvature and foam properties on the natural frequencies of the sandwich panels. Sandwich panels consist of laminated E/glass epoxy face sheets with [0°/90°/−45°/+45°] stacking sequences and PVC foam cores with AIREX C70.55, C70.90, C70.200 and C70.250. A group of sandwich panels with radii of curvature ranging from 90 to 200 mm were analysed by ANSYS software. Vibration characteristics were obtained for clamped square sandwich panels. The results indicate that the natural frequencies increase with the increasing curvature and foam density. However, the increment in the natural frequency due to an increase in the magnitude of curvature decreases with increasing foam density. The highest increase in natural frequency due to increasing foam properties is seen in the flat panels. Also, it is found that in values beyond a specific curvature; increasing of the foam properties causes reduction in the natural frequencies. © 2017 Elsevier LtdItem Effect of annealing temperatures on the crystallization and photocatalytic activity of micro-nanoporous TiO2 films produced by electrochemical anodization(Turkish Chemical Society, 2018) Yurddaskal M.; Yurddaskal M.; Dikici T.; Durmus H.In this study, micro-nanoporous TiO2 films were prepared by electrochemical anodization of titanium (Gr-2) in an aqueous solution containing 0.5 wt. % HF solution at a constant potential of 30 V and then annealed in ambient air at 500, 600, 700 and 800 °C for 2 h to obtain crystalline structures. The crystalline phase and surface morphology of the samples were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The photocatalytic performances of the samples were evaluated by the photocatalytic degradation of aqueous methylene blue (MB) solutions under UV light illumination for different periods. XRD results indicated that at annealing temperatures higher than 600°C, anatase started to transform into rutile. Increasing annealing temperatures resulted in reduced micro-nanopores diameter and increased wall thickness. At 800°C, the structure completely disappeared. The results demonstrated that changes in both the crystalline structure and surface morphology have a strong influence on the photoactivity of the nanostructured TiO2 films. © 2018, Turkish Chemical Society. All rights reserved.Item Experimental and numerical analysis of vibration frequency in sandwich composites with different radii of curvature(SAGE Publications Ltd, 2019) Yurddaskal M.; Okutan Baba B.In this study, free vibration responses of sandwich composite panels with different radius of curvature were presented numerically. The studies were carried out on square flat and curved sandwich panels made of E-glass/epoxy face sheets and polyvinyl chloride foam with three different radii of curvature. Experimental studies were used to verify the numerical results. Vibration tests were performed on flat and curved sandwich panels under free–free boundary conditions. The experimental data were then compared with finite element simulation, which was conducted by ANSYS finite element software and it was shown that the numerical analysis results agree well with the experimental ones. Effect of the curvature on natural frequencies under different boundary conditions (all edge free, simply supported, and fully clamped) was investigated numerically. Results indicated that the natural frequencies and corresponding mode shapes were affected by boundary conditions and curvature of the panel. For all boundary conditions, the variation of curvature had smaller effect on the natural frequency of the first mode than those of the other modes. © The Author(s) 2017.Item Thermoelectric Films for Electricity Generation(wiley, 2021) Yurddaskal M.; Yurddaskal M.; Yilmaz O.; Gultekin S.It is evident that revolutionary advances have been made in the field of electronics of the developing world, and advanced technological materials are of course very important in this technological progress. With this study, thermoelectric thin films have given us the opportunity to examine why they are preferred in this technological period, as well as their importance and their theoretical background. Among the advantages of this technology comes when compared to others, thermal evaporation (TE) is more silent and reliable, since no movement is involved in the process; they are simple, compact, and safe; it is a green technology since it does not include heat or gas, or no chemical disposals are produced during the process; and it is convenient since others are inconvenient when it comes to working in remote outer areas. The purpose of this study is to inform about thin film thermoelectric materials. This chapter includes studies on how thin film thermoelectric materials are classified, the application areas, production techniques, and future trends of this process. While explaining the importance of all these materials, it realizes by considering the classification of thin film thermoelectric materials and the mechanisms behind them are extremely important in terms of illuminating the production conditions of these materials in line with theoretical knowledge. In order to realize this aim, a method starting from general information to detailed technical contents has been determined. Concepts such as the Seebeck coefficient, the Peltier effect, and the Thomson effect were discussed with technical points. In addition, materials such as inorganic, such as Bi-Te-based superlattices, cobalt oxide-based thin films, Zn-based thin films, Cu-based thin films, and a combination of these with composite materials were mentioned. Then, it gives information about the usage areas of these materials such as thermoelectric cooling, thermoelectric power generation, organic inverter circuit, organic light emitting diode (OLED), organic radio frequency identification tags, and organic DNA sensors. Sputtering, molecular beam epitaxy (MBE), metal organic chemical vapor deposition (MOCVD), electrochemical deposition (ECD), flash evaporation (FE), TE, and pulsed laser deposition (PLD) methods were presented in detail. We hope that all this work succeeds to be a part of this technological progress and can support new studies as a source of information and inspiration. © 2021 WILEY-VCH GmbH. Published 2021 by WILEY-VCH GmbH.Item Tribological properties and studies in SBF of Ta2O5/TiN/TiO2 monolayer and bilayer coatings on biomedical Ti6Al4V alloy(Korean Society of Mechanical Engineers, 2022) Yurddaskal M.; Durmuş H.In this study, Ta2O5, TiN, and TiO2 are coated with magnetron sputtering method as monolayer and bilayer on Ti6Al4V alloy used in biomedical applications. The deposited coatings are characterized, and their mechanical properties are determined by nanoindentation tests. As a result of the pin-on disc wear test performed in dry environment and room temperature, in vitro corrosion test was applied to the samples with high wear resistance, and the information about the tribological properties was obtained. Experimental results show that the existence of the intermediate layer has also significant effect on the corrosion resistance of the coatings. The biocompatibility of the Ta2O5/TiO2 coating was examined by keeping it in simulated body fluid (SBF) due to its noticeable wear and corrosion resistance properties, the growth of apatite, which is described as an indicator of biocompatibility, occurred on the sample surface after 7 day. © 2022, The Korean Society of Mechanical Engineers and Springer-Verlag GmbH Germany, part of Springer Nature.Item Effect of solutionizing and quenching treatment on Ti6Al4V alloy: a study on wear, cavitation erosion and corrosion resistance(Springer, 2023) Çömez N.; Yurddaskal M.; Durmuş H.Titanium alloys are preferred in many engineering applications due to their high specific strength and superior corrosion resistance. However, its abrasion resistance is not very high and it limits the use of titanium alloys. The aim of this study is to examine the effect of solutionizing temperature on microstructure, hardness, wear, cavitation resistance and corrosion behavior of the Ti6Al4V alloy. For this purpose, quenching in water (WQ) was carried out by solutionizing the Ti6Al4V alloy at the temperatures 1050 and 960 °C containing the β-transus and β + α regions, respectively. The hardness of Ti6Al4V alloy increased with increasing heat treatment (HT) temperature. Depending on the increased hardness value, the highest wear resistance was observed in the specimen, which was heat treated at 1050 °C for 1 h and quenched. However, maximum cavitation resistance was observed in the specimen, which was heat treated at 960 °C for 1 h and quenched. The non-heat treated specimen exhibited the minimum cavitation resistance. Corrosion rate values were determined as 1.85, 0.66 and 0.46 × 10–3 mm/year for non-heat treated, 960 and 1050 °C heat treated + quenched specimens, respectively. It has been determined that heat treatment reduces the corrosion rate 3–4 times. Graphical abstract: [Figure not available: see fulltext.]. © 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Item Fe-Cr-C-V hardfacing coatings with molybdenum addition: Wear, corrosion, and cavitation performances(Elsevier B.V., 2024) Çömez N.; Yurddaskal M.; Gül C.; Durmuş H.; Albayrak S.The purpose of this study was to determine how molybdenum content affected the hardfacing coatings made of Fe-Cr-C-V that resist wear, corrosion, and cavitation. The hardfacing process was applied on the S235JR steel by the metal arc welding method. Apart from the chromium-rich M23C6 and M7C3 (M: Cr, Fe) carbides, the presence of molybdenum led to the development of M2C (M: Mo, Fe, Cr) carbides. As molybdenum and carbon concentration decreased, the size and volume fraction of M23C6 and M7C3 carbides tended to reduce. While molybdenum did not significantly alter hardness or wear resistance, it was found to be advantageous in terms of cavitation and corrosion. The coating, including 3 wt% FeMo, demonstrated a 20-fold increase in cavitation resistance compared to the coating devoid of molybdenum. The hardfacing coatings' resistance to corrosion was increased by up to 4.5 times with the addition of molybdenum. © 2024 Elsevier B.V.Item Production of zinc oxide (ZnO) doped biodegradable film and investigation of its photocatalytic/antimicrobial properties(Elsevier B.V., 2025) Karabaş E.; Yurddaskal M.; Bozatlı S.B.; Yılmaz T.In this study, photocatalytically active packaging materials incorporating zinc oxide (ZnO) nanoparticles were developed and characterized. Initially, a purity analysis of the ZnO nanoparticles was conducted, followed by determining their minimum inhibition concentration (MIC) against Escherichia coli O157:H7 and Aspergillus niger under both UV–visible light and dark conditions. Then films were prepared using chosen concentrations of ZnO and chitosan, and their physical and chemical properties, including thickness, colour, moisture content, moisture absorption capacity, hydrophobicity, were investigated. The film with optimal properties, containing 0.2 % ZnO and 1.5 % chitosan, was selected for further analysis considering desirability function for optimizing film composition. Additionally, films containing 0.1 % ZnO and 0.3 % ZnO were investigated. The largest inhibition diameter for A. niger was observed in films containing 0.3 % ZnO in incubation under light. E. coli O157:H7 did not grow on contact surface of the films. This film exhibited successful degradation of methylene blue solution, decreased water solubility with increasing ZnO concentration, and effective antimicrobial activity against both E. coli O157:H7 and A. niger. X-ray diffraction (XRD) patterns indicated the presence of ZnO nanoparticles in the films, while Fourier-transform infrared (FT-IR) spectra confirmed the organic bond structure of the films. In the photocatalytic experiment, the produced films, including ZnO nanoparticles between 1 % and 3 %, exhibit strong photo-degradation activity of 87.94 % and with a reaction rate constant (k) between 55.1 × 10-4 and 81.3 × 10-4h−1 (33.06 × 10-2 and 48.78 × 10–2 min−1). Overall, the results suggest that these photocatalytic active packaging materials could be promising for various applications, particularly in food packaging, due to their antimicrobial and photocatalytic properties. © 2024 Elsevier B.V.