Browsing by Author "Yurddaskal, M"

Now showing 1 - 12 of 12
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    Quenching and tempering of 51CrV4 (SAE-AISI 6150) steel via medium and low frequency induction
    Civi, C; Yurddaskal, M; Atik, E; Celik, E
    Mechanical and microstructural properties of quenched steel are directly related to tempering time and temperature. In many applications, conventionally quenched and tempered steel is widely used for acquiring high strength and toughness. The present study was carried out to investigate the variation in mechanical properties, observation of diminished energy consumption and evaluation of the microstructural properties in SAE-AISI 6150 steel components by induction heating, compared with those of steel tempered by conventional method. Induction quenched and tempered steel provides a shorter process time, less energy consumption and improved mechanical properties through the inhibition of grain growth. In this study, quenching and tempering processes were carried out on medium and low frequency induction units and by using a conventional electrical resistance furnace for the sake of comparison. It was observed that cementite particles began changing their shape from spherical to fine-grained in the induction tempered samples. The sample tempered by low frequency induction manifests superior mechanical properties and offers a potential advantage for significant cost savings.
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    Production of zinc oxide (ZnO) doped biodegradable film and investigation of its photocatalytic/antimicrobial properties
    Karabas, E; Yurddaskal, M; Bozatli, SB; Yilmaz, 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 x 10-4 and 81.3 x 104h- 1 (33.06 x 10-2 and 48.78 x 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.
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    Fe-Cr-C-V hardfacing coatings with molybdenum addition: Wear, corrosion, and cavitation performances
    Çömez, N; Yurddaskal, M; Gül, C; Durmus, 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.
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    Synthesis and characterization of Ag doped TiO2 heterojunction films and their photocatalytic performances
    Demirci, S; Dikici, T; Yurddaskal, M; Gultekin, S; Toparli, M; Celik, E
    In this study, undoped and silver (Ag) doped titanium dioxide (TiO2) films were successfully synthesized by sol-gel spin coating technique on the Si substrates. Photocatalytic activities of the TiO2 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 TiO2 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 TiO2 films calcined at 500 degrees C had the crystalline anatase phases and the surface morphologies with some cracks. Ag substitution into TiO2 matrix enhanced the photocatalytic activity of TiO2 films under UV light irradiation as compared to the undoped TiO2 film. Furthermore, the results indicated that the 0.7% Ag doped TiO2 film exhibited a superior photocatalytic activity than that of undoped and other Ag-doped TiO2 films. This study demonstrated the potential of an application of Ag doped films to efficiently treat dissolved organic contaminants in water. (C) 2016 Elsevier B.V. All rights reserved.
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    Fabrication and characterization of nanostructured anatase TiO2 films prepared by electrochemical anodization and their photocatalytic properties
    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 degrees 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 mu m) 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. (C) 2015 Elsevier B.V. All rights reserved.
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    Wear performance of Fe-Cr-C-B hardfacing coatings: Dry sand/rubber wheel test and ball-on-disc test
    Durmus, H; Çömez, N; Gül, C; Yurddaskal, M; Yurddaskal, M
    Minimizing wear would ensure reduced loss of material, labor and time for numerous branches of industry. Hardfacing coating method is a promising application to overcome this loss. The purpose of the the hardfacing application is to support, repair or improve the surface that is susceptible to abrasion by forming hard phases. The present study was aimed to investigate the wear resistance of iron-based hardfacing coatings which were produced with Fe-Cr-C-B and Fe-Cr-C based filler wires, according to ball-on-disc and dry sand rubber wheel wear tests. During the open arc welding process powder compositions of 100% FeB and 40% FeB + 60% FeCr were transferred to the weld pool, in order to enrich the coating with boron and chromium. Increased FeB content ensured the formation of boride phases such as Fe2B, CrB2, B6Fe23, Cr5B3. Minimum wear loss was obtained in a sample which was coated with Fe-Cr-C-B based filler wire reinforced with 40% FeB + 60% FeCr powder. Formation of massive carbide/boride phases and a tough matrix protected by the high amount of secondary carbides increased the wear resistance. The outcomes showed that the wear resistance is not only correlated with hardness but also affected by the morphology of microstructural constituents.
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    Effect of solutionizing and quenching treatment on Ti6Al4V alloy: a study on wear, cavitation erosion and corrosion resistance
    Çömez, N; Yurddaskal, M; Durmus, 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 degrees C containing the beta-transus and beta + alpha 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 degrees C for 1 h and quenched. However, maximum cavitation resistance was observed in the specimen, which was heat treated at 960 degrees 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 9 10(-3) mm/year for non-heat treated, 960 and 1050 degrees C heat treated + quenched specimens, respectively. It has been determined that heat treatment reduces the corrosion rate 3-4 times.
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    The effect of foam properties on vibration response of curved sandwich composite panels
    Yurddaskal, M; Ozmen, U; Kir, M; Baba, BO
    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 degrees/90 degrees/-45 degrees/+45 degrees] 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. (C) 2017 Elsevier Ltd. All rights reserved.
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    Experimental and numerical analysis of vibration frequency in sandwich composites with different radii of curvature
    Yurddaskal, M; Baba, BO
    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.
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    Tribological properties and studies in SBF of Ta2O5/TiN/TiO2 monolayer and bilayer coatings on biomedical Ti6Al4V alloy
    Yurddaskal, M; Durmus, 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.
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    An investigation into the wear behavior of aged Alumix321/SiC composites fabricated by hot pressing
    Durmus, H; Gül, C; Çömez, N; Yurddaskal, M
    Aerospace or automobile industries need materials that have a combination of several features such as lightness, high strength, corrosion and wear resistance. With ceramic particulates reinforcement, the properties of aluminum alloys can be greatly improved. The aim of this study is to investigate the effect of precipitation age hardening and the mass percentage of SiC particles on hardness and wear resistance of the 6061 aluminum matrix composites produced by hot pressing. Composites were solution treated at 530 degrees C for 1.5 h and then artificially aged at 160 degrees C for 18 h. The ball-on-disc wear test was carried out under 2N load using an alumina ball as the counterpart. The density of the composites was calculated according to Archimedes principle. Porosity tended to increase with increasing SiC reinforcement. Hardness and wear resistance of composites were improved by SiC particles and aging. Maximum hardness and minimum wear loss was obtained heat treated sample that contains 20 wt.% SiC reinforcement.
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    The effect of curvature on the impact response of foam-based sandwich composite panels
    Yurddaskal, M; Baba, BO
    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.