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TÜNÇAY, MEHMET MASUM

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TÜNÇAY

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MEHMET MASUM

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Start date: 2020 × Has files: true ×

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Now showing 1 - 3 of 3
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    PublicationOpen Access
    An investigation of 3D printing parameters on tensile strength of PLA using response surface method
    (2023-01-01) TÜNÇAY, MEHMET MASUM; TÜNÇAY M. M.
    Additive manufacturing has many techniques and has been frequently used and studied recently. The fused deposition modeling (FDM) method, which is one of these techniques, is a widely used three-dimensional (3D) printing method that works with the extrusion principle. The parameters used during printing affect the properties of the final product. This study investigated the effect of print angle, infill density, and perimeter count parameters on the tensile strength characteristics of FDM-printed PLA samples by the response surface method (RSM), an experimental design method. The tensile strengths of the samples produced according to the test lists obtained using the Box–Behnken design were determined. A model equation showing the effect of the relevant parameters was created. From the experiments, the compatibility of the model equation with the experimental results has been demonstrated. The highest tensile strength values were achieved in cases where the print angle was 90°, the infill density was 100%, and the number of walls was 5-6.
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    PublicationOpen Access
    Investigation of surface-modified EBM printed Ti-6Al-4V alloys for biomedical applications
    (2022-11-01) DEMİRCİ, SELİM; TÜNÇAY, MEHMET MASUM; GÜLLÜOĞLU, ARİF NİHAT; DEMİRCİ S., DİKİCİ T., TÜNÇAY M. M. , DALMIŞ R., KAYA N., Kanbur K., Sargin F., GÜLLÜOĞLU A. N.
    This work aimed to comprehensively assess the influence of various surface modifications on the formation of apatite ability for EBM Ti-6Al-4V alloy. Sandblasting (S), acid-etching (E), sandblasting and acid-etching (SE), anodization (NA), micro-arc oxidations in 1 M H2SO4 solution (SM) and 1 M H3PO4 solution (PM) methods were applied to modify electron beam melted (EBM) Ti-6Al-4V surface. The alpha/alpha\"-Ti structures and TiO2 phases were detected by XRD. The surface roughness (Ra) values ranged from 0.25 mu m and 2.86 mu m. The wettability of samples was between around 25 degrees and 104 degrees The SM sample possessed the lowest contact angle. In vitro tests were employed in the simulated body fluid (SBF) solution for 28 days. The samples with different surface textures demonstrated bioactive behaviors. In vitro test results showed that apatite layers formed on the surfaces. The SM sample exhibited good apatite formation ability when the Ca/P ratios were considered. The apatite formation for the SM sample might derive from high roughness, low contact angle value, the existence of Ti-OH groups, and anatase and rutile phases. The SM can be implemented to boost bioactivity on EBM Ti-6Al-4V alloys.
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    PublicationOpen Access
    A study of heating rate effect on the photocatalytic performances of ZnO powders prepared by sol-gel route: Their kinetic and thermodynamic studies
    (ELSEVIER, 2020-03) TÜNÇAY, MEHMET MASUM; Demirci, Selim; Dikici, Tuncay; Tuncay, Mehmet Masum; Kaya, Nusret
    In this work, ZnO particles were fabricated by sol-gel method at different heating rate at 500 degrees C for 2 h. The ZnO powders were analysed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy and photoluminescence, respectively. The effect of heating rate on photocatalytic activities of ZnO particles was evaluated by degradation of methylene blue (MB). The non-isothermal kinetics and thermodynamic properties were also estimated. The XRD results showed that ZnO had hexagonal wurtzite structure. The different heating rate didn't influence the surface morphology of ZnO powders. It was observed that the heating rate had a profound effect on reduction of band gap and photocatalytic performances. The band gap of the ZnO particles varied from 3.10 to 3.17. The ZnO sample prepared at 1 degrees C/min exhibited the highest photocatalytic activity. Its relative photocatalytic degradation rate and kinetic constant were 92.7% and 1.069x10(-2) min(-1), respectively. The results might be ascribed to low bulk vacancies, high surface oxygen vacancies and narrow band gap energy. Also, ZnO photocatalysts showed good stability after four sequence tests. This study provides a new strategy to improve the photocatalytic performances of ZnO photocatalyst for the degradation of organic contaminant.