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- MakaleYalnız künye2026Scopus SJRQ1Exploring the photocatalytic potential of NbTiZrW-based high-entropy alloys with Hf/Mo/Ta additions: Influence of alloying elements on their structural and photocatalytic performance
Zakir, O.; Guler, O.; Idouhli, R.; Aklalouch, M.; Dikici, B.; Khadiri, M.E.; Abouelfida, A.; Selen, V.; Şimşek, T.
In this study, the photocatalytic performance of NbTiZrW-based high-entropy alloys (HEAs) with Hf, Mo, and Ta additions was investigated. The alloys were synthesized by mechanical alloying for 120 h under a high-purity Ar atmosphere to prevent oxidation. The photocatalytic activity of the samples was evaluated based on the degradation of methylene blue (MB) under UV irradiation. Structural and chemical characterizations were performed using energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The results showed that MB removal by adsorption reached 22.96 % for NbTiZrWHf, 21.90 % for NbTiZrWTa, and 47.01 % for NbTiZrWMo. The incorporation of Mo into the NbTiZrW alloy was found to enhance electrostatic interactions between MB molecules and the alloy surface. Upon UV irradiation, the degradation efficiency increased significantly, reaching 32.84 % for NbTiZrWHf, 82.02 % for NbTiZrWTa, and 46.13 % for NbTiZrWMo within 3 h. The improved performance of the NbTiZrWHf alloy was attributed to its low particle size, which provided a larger number of active sites for photocatalytic activity, as confirmed by SEM analysis.
AtıfScopus1OpenAlex1
İncele - MakaleYalnız künye2024Scopus SJRQ1Effect of oxidation on radiation shielding capacity of ZrNbTaMoW Refractory High Entropy Alloys (RHEA) for nuclear reactor applications: Experimental and theoretical assessment
Sakar, E.; Guler, O.; Alim, B.; Guler, S.H.; Dikici, B.; Lampke, T.
This study presents the production and comprehensive assessment of a Refractory High Entropy Alloy (RHEA) with a ZrNbTaMoW composition for possible usage nuclear reactor applications. The alloy was synthesized using the mechanical alloying (MA) method, and its radiation properties were examined. Elemental powders of Zr, Nb, Ta, Mo, and W were utilized in equimolar quantities during the 120-hour MA process, conducted under a high-purity Ar atmosphere to prevent oxidation. The obtained HEA was then subjected to a mechano-thermal process to transform it into Refractory High-Entropy Oxide (RHEO) for comparing their radiation-shielding performance under oxide conditions. The characterization of the produced alloys through X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron dispersive spectroscopy (EDS). The photon shielding parameters of the alloys were experimentally obtained for various energies emitted from a 133Ba radioactive source, employing a Canberra UltraLEGe semiconductor detector. Furthermore, theoretical calculations were performed to validate the experimental data and to evaluate the alloys' photon shielding capabilities comprehensively. For this purpose, Phy-X/PSD software was employed to determine mass attenuation coefficients, half-value layer, effective atomic number, and effective electron density. Fast neutron absorption capabilities were determined through the calculation of average absorption cross-sections in the 2–12 MeV energy range. The results showed that the oxidation process significantly diminished the photon absorption capacity of RHEA.
AtıfScopus34OpenAlex37İncele - MakaleYayıncıda açık erişim2024Scopus SJRQ1Investigation of in-vitro bioactivity, electrochemical corrosion, wettability and adhesion properties of bioglass-based coatings modified with Y2O3 and Zr on novel β-type Ti-30Zr-5Mo alloys
Dikici, B.; Say, Y.; Zhao, X.; Niinomi, M.; Szechyńska-Hebda, M.
In this study, the in-vitro bioactivity, electrochemical corrosion resistance, wettability, and adhesion properties of bioglass-based coatings modified with Y2O3 and ZrO2 on Ti-30Zr-5Mo alloy were investigated. The coatings were prepared using the sol-gel method and applied to the alloy substrates through dip-coating. The surface morphology and elemental composition of the coatings were analyzed using SEM/EDS and XRD techniques. Potentiodynamic polarization (PDS) and electrochemical impedance spectroscopy (EIS) were employed to assess the electrochemical behavior of the coatings under in-vitro conditions. Contact angle measurements were conducted to evaluate the wettability of the surfaces. Adhesion strength was measured using tensile testing in accordance with ISO 13779-2 standards. Bioactivity tests were performed by immersing the samples in simulated body fluid (SBF). The results demonstrate that the addition of Y2O3 and ZrO2 improves adhesion strength and corrosion potential, but introducing localized galvanic effects that increase the corrosion current density. Besides, the coatings maintained their structural integrity after the bioactivity tests, and promoted new apatite formation.
AtıfScopus9İncele - MakaleAçık Erişim2024Scopus SJRQ1Enhanced photocatalytic abilities of innovative NbTaZrMoW high-entropy alloys (HEAs): a comparative analysis with its high entropy oxide (HEO) counterpart
Zakir, O.; Guler, O.; Idouhli, R.; Nayad, A.; Khadiri, M.E.; Guler, S.H.; Abouelfida, A.; Dikici, B.
The photocatalytic performance of high entropy alloy (HEA) and its oxide form (high entropy oxide, HEO) have been evaluated in this study. The HEA, composed of Nb, Ta, Zr, Mo, and W powders, was synthesized through a mechanical alloying process for 120 h. This process was carried out under a high-purity Ar atmosphere to prevent oxidation. Subsequently, the HEA was converted into HEO via a mechano-thermal oxidation method 900 °C for 12 h. The photocatalytic activity of both oxidized and non-oxidized samples was systematically evaluated by degradation of methyl blue (MB) under UV irradiation. Electron dispersive spectroscopy (EDS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) were used to investigate the structural and chemical features of the alloys. Furthermore, BET surface area analysis and Zeta potential measurements were conducted to understand the alloys’ surface properties and stability in aqueous solutions. The results showed that the HEA has a remarkable photodegradation performance of around 58.77% which is two times higher than that observed with the HEO. Graphical abstract: (Figure presented.)
AtıfScopus31WoS30OpenAlex28İncele - MakaleYalnız künye2023Scopus SJRQ1In-vitro corrosion and surface properties of PVD-coated β-type TNTZ alloys for potential usage as biomaterials: Investigating the hardness, adhesion, and antibacterial properties of TiN, ZrN, and CrN film
Ali, L.A.; Dikici, B.; Aslan, N.; Yilmazer, Y.; Sen, A.; Yilmazer, H.; Niinomi, M.
In this study, the corrosion and surface properties of non-toxic and non-allergenic β-type Ti–29Nb–13Ta–4.6Zr alloys (TNTZ) coated with TiN, ZrN, and CrN layers using the PVD technique were investigated under in-vitro conditions. The coatings' hardness, adhesion resistance, and antibacterial properties were also studied, with a focus on their potential usage as biomaterials. The corrosion tests were conducted using potentiodynamic polarization, the hardness tests were conducted using the Knoop method, and the adhesion tests were conducted using pull-off tests. The wetting properties of the coatings were examined through contact angle and 3D morphological analysis. The coatings were characterized using SEM-EDS and XRD. The results showed that the adhesion resistance of all coatings was significantly higher than the expected adhesion strength for biomaterial coatings, while their corrosion resistance was higher compared to the uncoated alloy. Besides, the study demonstrates the potential of TiN, ZrN, and CrN coatings on β-type TNTZ for use as a biomaterial with desirable surface and antibacterial properties.
AtıfScopus29OpenAlex27İncele - MakaleAçık Erişim2022Scopus SJRQ1Graphene reinforced hybrid-bioceramic coatings on porous-Ti6Al4V for biomedical applications: morphology, corrosion resistance, and cell viability
Aslan, N.; Aksakal, B.; Dikici, B.; Sinirlioglu, Z.A.
The effect of Hydroxyapatite (HA)-based coatings reinforced with reduced graphene oxide (rGO) on porous-Ti6Al4V (P-Ti6Al4V) alloys in terms of electrochemical corrosion and cell viability for potential biomedical applications was investigated in this study. The scaffold-porous surfaces of P-Ti6Al4V were coated by the biocomposite structure of HA and reduced graphene oxide (rGO) at various porosity rates (40, 50, and 60%) by using the sol–gel dip-coating method. The results of 0.5, 1.0, and 1.5 wt% rGO-HA coatings were compared to coatings that contained only HA (free-rGO). Raman spectroscopy, X-ray diffractometer, and scanning electron microscopy were used for structural and morphological characterizations. The coatings in vitro corrosion susceptibilities were tested in simulated body fluid at 37 °C. Compared to free-rGO coatings, the results showed that rGO reinforcements phases reduced the corrosion rate of the scaffolds. The corrosion rate increased as the porosity content of the scaffolds increased. In vitro cell viability tests revealed that samples of 0.5 and 1.0 wt% rGO-HA coating groups performed better than the control and 1.5 wt% rGO-HA samples. Graphical abstract: [Figure not available: see fulltext.]
AtıfScopus8WoS7OpenAlex6İncele - DüzeltmeAçık Erişim2022Scopus SJRQ2Correction to: Boron-Doped Hydroxyapatite Coatings on NiTi Alloys Using the Electrophoretic Deposition Method: Enhanced Corrosion and Adhesion Performances (Journal of Materials Engineering and Performance, (2021), 30, 10, (7365-7375), 10.1007/s11665-021-05968-x)
Aksoy, M.E.; Aksakal, B.; Aslan, N.; Dikici, B.
The following acknowledgment was inadvertently omitted from the originally published article: This work was supported by Yildiz Technical University, C¸ AP (Grant No. FCD-2019-3511).
AtıfScopus1WoS1OpenAlex1İncele - MakaleYalnız künye2021Scopus SJRQ3Enhanced Adhesion and Corrosion Properties of Boron Doped Bioceramic Coated 316L Implants
Aksoy, M.E.; Aksakal, B.; Aslan, N.; Dikici, B.
Abstract: In order to provide an effective prevention to 316L implants, a synthesized bioceramic was coated by using electrophoretic deposition (EPD). The effect of boron addition into hydroxyapatite (HA) on surface morphology, adhesion and corrosion resistance of the implant has been examined. Boron doped HA (B–HA) was synthesized by a simple chemical acid-base method with 5, 10, and 15 wt % boron additions to coat on 316L implants. The synthesized B-HA was coated on the substrates and the coated surfaces with and without B additions. Sintering took place at different temperatures and sintering rates. The coatings were characterized by X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FT–IR) and scanning electron microscope (SEM). Furthermore, adhesion and in vitro corrosion tests were conducted. The influence of boron additons on adhesion and corrosion resistance of 316L have been revealed for the coated substrates at different B additions. It was shown that boron addition increased the adhesion and corrosion resistance of the bioceramic coatings. Furthermore, the sintering effect on adhesion was also evaluated and the highest adhesion as 25.8 MPa has been reached at 750°C for 90 s and 5°C min–1 sintering conditions. It was found that using iodine as EPD dispersant has increased the charging ability of the B–HA powders in the suspension and hence eased deposition rate. The study revealed that boron-containing hydroxyapatite coatings can provide crack-free surfaces that providing high adhesion and hence increase the corrosion resistance of metallic implants. Through the results, it was also shown that the network between powders was improved and hence adhesion was increased with increasing B addition.
AtıfScopus10WoS9OpenAlex12İncele - MakaleYalnız künye2021Scopus SJRQ2Boron-Doped Hydroxyapatite Coatings on NiTi Alloys Using the Electrophoretic Deposition Method: Enhanced Corrosion and Adhesion Performances
Aksoy, M.E.; Aksakal, B.; Aslan, N.; Dikici, B.
Metallic implants are functionalized with coatings due to the need to protect against biological corrosion in the body. Hydroxyapatite (HAp) has desirable biocompatibility and structural properties, but poor mechanical properties limit its use as a standalone coating. In this study, boron-doped hydroxyapatite (B-HAp) biocomposites containing 5, 10, and 15% boron by weight were synthesized by the sol-gel method and applied as a coating to NiTi using electrophoretic deposition (EPD). The deposition was carried out for 60, 90, and 120 s, and sintering at 750 °C for 75 minutes under vacuum. The coated substrates were then characterized by XRD, SEM, and FT-IR, and their adhesion strengths and in-vitro corrosion behaviors in simulated body fluid were compared with uncoated samples. The results showed that the microporous powders formed well-bonded structures, which positively affect adhesion strength. The highest adhesion strength (30 MPa) and corrosion resistance were achieved with 15 wt.% B-HAP coating at 120 s deposition time and 76.5 μm coating thickness.
AtıfScopus18WoS16OpenAlex19İncele - MakaleYalnız künye2018Scopus SJRQ3Synthesis and Characterization of Hydroxyapatite/TiO2 Coatings on the β-Type Titanium Alloys with Different Sintering Parameters using Sol-Gel Method
Dikici, B.; Niinomi, M.; Topuz, M.; Say, Y.; Aksakal, B.; Yilmazer, H.; Nakai, M.
In this study, hydroxyapatite (HA) based composite films were successfully syntheses on the β-type Ti29Nb13Ta4.6Zr (TNTZ). The solutionized TNTZ substrates coated with HA and HA/Titania (TiO2) bioactive composite coatings by sol-gel method under various sintering parameters related to sintering temperatures and heating ramp rates. Microstructural observations of the coatings revealed that apatite was formed on the substrates. The hardness values of the coatings increase with increasing both the sintering temperature and the TiO2 concentration in the coatings layer. However, it was found that the heating ramp rate of the sintering was not affecting the hardness values so much. Also, the hardness values of the HA/TiO2 composite coatings at all sintering temperatures were higher than only HA coated TNTZ samples due to the existence TiO2 phases in the HA matrix. Results indicating that the doping of HA with TiO2, improve the physical consistency between the coating layer and the substrates and provide a better inter-particle bonding due to the existence TiO2 phases in the HA.
AtıfScopus42OpenAlex43İncele