Browsing by Author "Dikici, T"

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    Deposition of HA-GO on ASO modified Ti surface by EPD method and characterization of surface and biological properties of the coating
    Kirman, M; Dogan, H; Dikici, T
    In this study, the surfaces of titanium (grade 2) substrates were modified by different methods and then coated with a hydroxyapatite-graphene oxide (HA-GO) composite by electrophoretic deposition (EPD). The aim of the study is to improve the surface properties and increase the hydrophilicity of the surface of titanium by different surface treatments. The surface modification processes are as follows: sandblasting (S), acid etching (E), and finally anodic spark oxidation (ASO) on the etched surface. After the surface modification processes, the surface of titanium was coated with HA-GO suspensions (0, 2, 4, and 6 wt% GO) with a voltage value of 20 for 5 min by the EPD method. The surface morphology, elemental analysis, contact angle, phase composition, adhesion, biocompatibility, and bioactivity of the produced coatings were examined. Bioactivity analysis was performed in simulated body fluid (SBF) for 14 days. The MTT experiment was conducted with L929 (mouse fibroblast) cell cultures in accordance with the 70 % cell viability criterion. As a result of contact angle measurements, it was observed that all samples showed hydrophilic behavior due to the increased surface area after ASO treatment. The contact angle of the sanded surface was 71.03 degrees, whereas the contact angles of the ASO treatment and HA-GO coatings after the coating process were measured below 5 degrees. The bioactivity test results indicated that the surface modified with HA-GO (4 wt%) exhibited the best apatite nucleation outcome. As a result of the analysis with L929 cells, HA, HA-GO (2 wt%), HA-GO (4 wt%) composite coatings showed biocompatible behaviour with 102.17, 76.52, and 80.43 % cell viability, respectively. The best result in the adhesion test was reported for HAGO (4 wt%) coating with class 5B.
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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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    Investigation of surface-modified EBM printed Ti-6Al-4V alloys for biomedical applications
    Demirci, S; Dikici, T; Tünçay, MM; Dalmis, R; Kaya, N; Kanbur, K; Sargin, F; Güllüoglu, AN
    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.