Browsing by Author "Zeybek M.S."
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Item Cement mixes containing colemanite from concentrator wastes(Elsevier Ltd, 1998) Erdoǧan Y.; Zeybek M.S.; Demirbas A.In this article, colemanite ore wastes of particle size <25 mm and sludge from concentrator were dried by hot air flow and then were mixed with Portland and trass cements. The effects on the setting and mechanical properties of the colemanite ore wastes mixed with Portland and trass cements were investigated. It was found that some colemanite wastes can be used as cement additives. © 1998 Elsevier Science Ltd.Item Extending experimental data to investigate phosphogypsume use in light brick by Artificial Neural Networks(2007) Yurdusev M.A.; Kumanlioǧlu A.A.; Abali Y.; Zeybek M.S.; Canpolat F.In this study, usability of wastes produced in phosphoric acid plants in structural brick manufacture has been investigated. A series of experiments for three different material combinations namely original waste plus normal brick clay, washed waste plus normal brick clay and normal brick clay with no additive were carried out to achieve this end. The results have shown that the industrial wastes considered improve the performance of the bricks. However, the results have also shown that further investigations are needed to explore the effects of interim or outer values on the performance of the bricks. To active that end, a neural experimental study is adopted. The outcome of these artificial tests have provided the appropriate values for the waste addition rate, firing speed and firing temperature. © 2007 Taylor & Francis Group, London.Item Using phosphogypsume and boron concentrator wastes in light brick production(2007) Abali Y.; Yurdusev M.A.; Zeybek M.S.; Kumanlioǧlu A.A.In this study, use of wastes produced in phosphoric acid plants and boron concentrators in producing structural brick has been investigated. There are several parameters involved in using these wastes in brick production namely the rate of added waste, firing speed and firing temperature. The performance of these parameters can be measured by several criteria such as natural drying shortening, water absorption and weight loss. Therefore, so many experiments are needed to investigate the effects of these parameters on the bricks produced with these wastes. To this end, around 220 experiments for three different material combinations namely original waste plus normal brick clay, washed waste plus normal brick clay and normal brick clay with no additive were carried out. The results have shown that the industrial wastes produced by phosphoric acid plants can improve the performance of the bricks in terms of drying shortening, weight loss and water absorption. © 2005 Elsevier Ltd. All rights reserved.Item Neural extension of experimental data to investigate using phosphogypsume in light brick production(2009) Yurdusev M.A.; Kumanlioǧlu A.A.; Abali Y.; Zeybek M.S.In this study, usability of wastes produced in phosphoric acid plants in structural brick manufacture has been investigated. There are several parameters involved in using these wastes in brick production namely the rate of added waste, firing speed and firing temperature. The performance of these parameters can be measured by several criteria such as natural drying shortening, water absorption and weight loss. Therefore, so many experiments are needed to investigate the effects of these parameters on the bricks produced with these wastes. The result of a series of experiments were utilized to achieve this end. The results have shown that the industrial wastes considered improve the performance of the bricks in terms of the criteria mentioned above. However, the results have also shown that further investigations are needed to explore the effects of interim values on the performance of the bricks. To achieve that end, a neural experimental study is adopted. For this purpose, the results of the experiments conducted were used to construct an artificial neural network. The trained and tested network was then used to check the effects of 280 different combinations for each type of material mixtures mentioned. The outcome of these artificial tests have provided the optimal values for the waste addition rate, firing speed and firing temperature based on the four criteria mentioned previously. © 2008 Elsevier Ltd. All rights reserved.Item Effect of carbonitriding on corrosion resistance of steel 30MnB5 in two acidic environments(Springer New York LLC, 2017) Yazici A.; Zeybek M.S.; Güler H.; Koç M.; Pekıtkan F.G.Corrosion resistance of steel 30MnB5 is studied after carbonitriding, after conventional quenching, and without treatment. Corrosion tests are performed for from 24 to 168 h in two acidic environments (in a hydrochloric acid solution with 10% mole fraction and in fertilizer-containing soil). It is shown that the rate of corrosion of the steel in both environments after carbonitriding is lower than after quenching). © 2017 Springer Science + Business Media New York.Item Effect of gamma irradiation on the thermal and mechanical behaviour of polypropylene and polyethylene blends(Elsevier Ltd, 2022) Sirin M.; Zeybek M.S.; Sirin K.; Abali Y.This study investigates the effect of radiation over polypropylene and polyethylene blends samples with different weight ratios. 10, 30, 50, 70, and 100 kGy doses of radiation were applied from the 60Co source on the polymer blends obtained by mixing polypropylene (PP) and polyethylene (LDPE) samples with different molecular weights in different ratios by weight. Melting flow rates (MFI), hardness, tensile strength at yield, tensile strength at break, elongation at break, differential scanning calorimetry (DSC), and thermogravimetric analysis (TG) of the samples were examined. When melting flow index of the samples was examined, it was determined that there was a significant increase in the speed of melting flow in connection with increasing radiation doses. When the mechanical analyses of the samples were examined, there was a significant decrease in tensile strength at yield, tensile strength at break, and elongation at break values. Particularly, as the samples with 100 kGy dose had deformation, there was no reading for these values. When DSC analysis of the samples was examined, depending on the increasing radiation dose, there was a decrease in melting temperature Tm, crystallization temperature Tc, melting enthalpy ΔHf, crystallization enthalpy ΔHc and the rate of crystallization Xc values. It was observed that there was a mass loss against heat in TG analysis of samples. © 2022Item Effect of different corrosive media on the corrosion resistance and mechanical properties of armor steel(Walter de Gruyter GmbH, 2023) Yazlcl A.; Zeybek M.S.; Kahraman F.Armor steel samples were exposed to corrosion for 24, 72, 168, and 720 h in two different corrosive media. The corrosion rate was determined using mass loss, measurement of the concentration of components in the corrosive medium solution, and Tafel extrapolation methods. Before and after corrosion experiments, the tensile properties, surface characteristics, and phase structures of the samples were examined. The surface analyses were performed using the SEM technique combined with EDX analyses, and the phase analyses were performed by X-ray diffraction. The corrosion rate determined by the mass loss method was 0.02 ± 0.01 mm year-1 for the 3.5 wt% NaCl medium and 2.66 ± 0.16 mm year-1 for the 1 M HCl medium. The corrosion rate values determined by the Tafel extrapolation method were 0.02 ± 0.01 mm year-1 in the 3.5 wt% NaCl medium and 1.21 ± 0.01 mm year-1 in the 1 M HCl medium. There was a decrease in the tensile, yield strengths, and elongation to fracture values of the corroded samples compared to the non-corroded samples. While intergranular ductile fracture occurred in samples exposed to 3.5 wt% NaCl medium, there were features reminiscent of the brittle fracture in samples exposed to the 1 M HCl/168 h medium. © 2023 Walter de Gruyter GmbH, Berlin/Boston.Item Investigation of the Effect of High-Frequency Induction Sintering on Phase Structure and Microstructure of SiC Reinforced Aluminum Matrix Composites(Sakarya University, 2024) Koç M.; Zeybek M.S.In this study, SiC-reinforced aluminum matrix composites were powder metallurgically (PM) prepared and sintered using high-frequency induction system (HFIS). The samples with different ratios of SiC (wt.%10, 20 and 40) added to the aluminum matrix were sintered at 660, 800, and 1000 °C. In addition, Al/SiC composites were compared by sintering with the conventional sintering (CS) method under similar sintering conditions. The heating rate for the sintering process using HFIS was 500 °C/min, while the CS method used a heating rate of 10 °C/min. The effect of the temperature and SiC ratio on the density, hardness, phase structure, and microstructure of composites was investigated. The optimum sintering temperature was determined according to the SiC additive amount. When 10%, 20%, and 40% SiC by weight were added to the aluminum matrix in the sintering process with HFIS, the required sintering temperatures were determined as 660, 800, and 1000 °C, respectively. While new phases were not formed as a result of short-term HFIS sintering, a high-temperature Al4C3 phase was detected in CS sintering. HFIS sintered Al/SiC composite samples were obtained in Al and SiC phases with high density and hardness ranging from 43-118 HV. In the high-temperature sintering process with HFIS, the formation of Al4C3 was prevented and its physical and mechanical properties were improved. © 2024, Sakarya University. All rights reserved.Item Chemistry of plant extracts directs the silver nanostructures’ crystal structure into hexagonally close-packed: a comparative study using elecampane and blueberry extracts(Canadian Science Publishing, 2024) Tepe M.; Zeybek M.S.In this study, silver nanostructures (AgNSs) were obtained using aqueous extracts of elecampane (Inula viscosa) andblue berry (Vaccinium arctostaphylos L.). The synthesized AgNSs were characterized using UV–visible spectrophotometers, Fourier-transformed infrared spectroscopy, scanning electron microscopy-energy dispersive X-ray analysis, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. The optimization studies revealed that pH and the extract/AgNO3 ratio played significant roles in the morphology and size of the AgNSs, while temperature did not show any significant role. Both the blueberry and elecampane extracts resulted in a mixture of spherical and aspherical silver nanoparticles (AgNPs). In contrast, utilization of a relatively high extract/AgNO3 ratio accompanied by an extended incubation period (i.e., 10 days) caused the formation of larger spherical (e.g., up to micron-sized) and large 1D AgNPs for the blueberry and elecampane extracts, respectively. The major difference related to the crystal structures was obtained, as the blueberry extracts resulted in face-centric cubic crystals, and the elecampane extracts allowed the formation of hexagonally close-packed (hcp) crystalline structures. The AgNPs were tested for their antibacterial activities using gram (−) andgram(+) bacterial species, where the elecampane-synthesized AgNPs possessed higher antibacterial activity that can be attributed to the hcp crystalline structure of the AgNPs. © 2024 The Author(s).