Person: DEMİRCİ, SELİM
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DEMİRCİ
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SELİM
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Publication Open Access Production of Zn-doped TiO2 film with enhanced photocatalytic activity(2022-12-01) DEMİRCİ, SELİM; DİKİCİ T., YILMAZ O., Akalin A., DEMİRCİ S., GÜLTEKİN S., YILDIRIM S., YURDDAŞKAL M.In this study, zinc (Zn)-doped titanium dioxide (TiO2) films were prepared using the two steps: anodic oxidation method and heat treatment process. The crystal structure, morphology and elemental composition of the Zn-doped TiO2 films were investigated. These films were characterized by scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results indicated that the TiO2 films with clear, uniform and short nanopores had a high surface area and high degree of crystallinity. The results showed that the asanodized TiO2 film was successfully obtained as anatase phase at 450 degrees C. The results of XPS analysis confirmed the presence of Zn in the lattice of TiO2 as dopant, and thermal diffusion technique was successfully done as doping method. The photocatalytic performances of the Zn-doped TiO2 films were evaluated in terms of their photodegradation rate of methylene blue (MB) in an aqueous solution under UV light irradiation. The results revealed that the Zn-doped TiO2 film had a higher photocatalytic activity in comparison with the undoped sample. This study inspired that Zn-doped TiO2 films are a great potential material to treat wastewater in industrial field.Publication Open 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.Publication Metadata only Nanoindentation and Corrosion Behavior of Additively Manufactured Ti-6Al-4V Alloy for Biomaterial Applications(2023-01-01) DEMİRCİ, SELİM; DEMİRCİ S., DİKİCİ T., DALMIŞ R.In this study, the effect of different laser beam power on the nanoindentation and corrosion properties of Ti-6Al-4V alloys fabricated direct metal laser sintering (DMLS) method was investigated. Ti-6Al-4V samples were fabricated by DMLS method with three 34.72 J/mm3, 64.81 J/mm3 and 83.33 J/mm3 energy densities named as sample 1, sample 2 and sample 3, respectively. The microstructure and crystalline phase of Ti-6Al-4V samples were analyzed by optical microscope, SEM and XRD devices. Microstructural examinations showed that microstructure of Ti-6Al-4V samples consisted of the prior columnar β grains and α/α´ phases. The β phase proportion soared with rising laser beam power. Nanoindentation results illustrated that the order of reduced elastic modulus (Er) values was sample 1 > sample 2 > sample 3. The order of hardness (H) values followed sample 1 > sample 2 > sample 3. The H/ Er ratios were found to be 0.0338, 0.0333, and 0.032 for samples 1, 2, and 3, respectively. The H3/Er2 ratios were estimated to be 0.00734 GPa, 0.00633 GPa, and 0.00513 GPa for samples 1, 2, and 3, respectively. The presence of high values means better anti-wear capacity and good resistance to deformation for samples based on nanoindentaion findings. Moreover, electrochemical measurements depicted that the value of corrosion current density (icor) of the samples ordered as sample 3 > sample 2 > sample 1. The sample 1 exhibited better corrosion resistance than other samples. The findings showed that as the laser power is low, DMLS Ti-6Al-4V samples potentially have better mechanical and corrosion performance due to low β content and high α´ phases in the microstructure.