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- MakaleYalnız künye2025Scopus SJRQ2Investigation of structural and adhesion properties of ZnO and h-BN doped TiO2 coatings on Cp–Ti alloy
Belet, Ali Kadir; Şüküroğlu, Süleyman; Şüküroğlu, Ebru Emine
Titanium and its alloys are widely used in aircraft, automotive, chemistry, marine, and military industries owing to their superior properties such as specific strength, very low density, high melting point, high corrosion resistance, good fatigue strength and toughness, low elastic modules, and excellent biocompatibility. However, insufficient tribological properties such as high and unstable friction coefficient, low scraping wear resistance and strong adhesion tendency, and poor corrosion resistance in some aggressive corrosive environments such as severe chloride solution limits the use of titanium and its alloys in some engineering applications. For this reason, it has become quite common to change and/or improve the surface properties of titanium and its alloys. In this study, the structural properties of TiO2 coatings with zinc oxide (ZnO) added TiO2 and hexagonal boron nitride (h-BN) added TiO2 grown composite coatings, respectively, on Cp–Ti substrates by micro-arc oxidation method and the adhesion behavior between the base material and coatings were investigated.
AtıfScopus1WoS1OpenAlex1İncele - MakaleYalnız künye2023Scopus SJRQ1Enhanced wear resistance and surface properties of oxide film coating on biocompatible Ti45Nb alloy by anodization method
Şenaslan, Fatih; Taşdemir, Muharrem; Çelik, Ayhan; Bozkurt, Yusuf Burak
β-Titanium alloys have become increasingly popular as biomaterials because of their low modulus of elasticity and superior corrosion properties in recent years. β-titanium alloy containing niobium is also a biocompatible and non-toxic material. Among β-Ti alloys, Ti45Nb is one of the most remarkable alloys for its superior properties as a biomaterial. This alloy has superior properties due to low elasticity modulus and non-toxic elements, but its surface properties are inadequate for biomaterial applications. Therefore, various surface treatments are applied to improve the surface properties of these alloys. In this study, an oxide film layer was formed on the Ti45Nb surface under different potential conditions by the anodizing method. The effects of these factors on friction, wear, and contact angle measurements were investigated. The structural properties of the oxide film coated samples were analyzed with XRD and their surfaces and cross-sectional images were observed by SEM. Also, the surface roughness and nanoindentation tests were performed. In this regard, it was determined that oxide film thickness, surface roughness and hardness increased with the increase of anodization potential. The contact angle of the samples decreased with the increase in the anodization potential and the surface tension of the materials increased. The highest nanohardness of about 4.19 GPa was obtained from 150 TA samples. The elasticity modulus of the untreated sample was about 63 GPa, while the anodized samples ranged from an average of 31 to 83 GPa. The wear results revealed that the anodization process improved the wear resistance of the Ti45Nb alloy. As a result, the sample anodized at 200 V for 30 min exhibited optimum surface roughness, morphology and high wear resistance.
AtıfScopus33WoS32OpenAlex32İncele - MakaleYalnız künye2019Scopus SJRQ1Circuit implementation of nano-scale TiO2 memristor using only metal-oxide-semiconductor transistors
Gul, Fatih
A metal-oxide-semiconductor (MOS)-based circuit model that emulates a TiO2 memristor is proposed in this study. First, a TiO2 (10-nm active layer thickness)-based memristor device was fabricated. The structural properties of the device were confirmed via energy dispersive X-ray spectroscopy. The memristive characteristics of the device were resolved by applying a time-dependent voltage. The typical pinched hysteresis memristive loops of the current-voltage curves were obtained. After physical implementation and characterization of the device, a circuit model was implemented using only four MOS transistors to emulate the fabricated TiO2 memristor. In addition to emulating the fabricated memristor, the proposed circuit model is suitable for use in general memristor-based applications. No active element or circuit blocks were used in the circuit to achieve memristive characteristics. The simulation and experimental results are in good agreement; moreover, the circuit is very simple compared to those presented in previous studies in the literature and it was able to emulate the fabricated memristor. All simulations were completed using 180 nm TSMC CMOS process parameters.
AtıfScopus38WoS35OpenAlex40İncele - MakaleAçık Erişim2018Scopus SJRQ2Entropy generation of nanofluid flow in a microchannel heat sink
Manay, Eyuphan; Akyürek, Eda Feyza; Sahin, Bayram
Present study aims to investigate the effects of the presence of nano sized TiO2 particles in the base fluid on entropy generation rate in a microchannel heat sink. Pure water was chosen as base fluid, and TiO2 particles were suspended into the pure water in five different particle volume fractions of 0.25%, 0.5%, 1.0%, 1.5% and 2.0%. Under laminar, steady state flow and constant heat flux boundary conditions, thermal, frictional, total entropy generation rates and entropy generation number ratios of nanofluids were experimentally analyzed in microchannel flow for different channel heights of 200 mm, 300 mm, 400 mm and 500 mm. It was observed that frictional and total entropy generation rates increased as thermal entropy generation rate were decreasing with an increase in particle volume fraction. In microchannel flows, thermal entropy generation could be neglected due to its too low rate smaller than 1.10e-07 in total entropy generation. Higher channel heights caused higher thermal entropy generation rates, and increasing channel height yielded an increase from 30% to 52% in thermal entropy generation. When channel height decreased, an increase of 66%-98% in frictional entropy generation was obtained. Adding TiO2 nanoparticles into the base fluid caused thermal entropy generation to decrease about 1.8%-32.4%, frictional entropy generation to increase about 3.3%-21.6%. (C) 2018 The Authors. Published by Elsevier B.V.
AtıfWoS93OpenAlex96İncele - MakaleYalnız künye2018Scopus SJRQ1Carrier transport mechanism and bipolar resistive switching behavior of a nano-scale thin film TiO2 memristor
Gul, Fatih
A titanium dioxide (TiO2) based memristor device having an active layer thickness of 10 nm was fabricated using radio frequency (RF) reactive sputtering and its resistive switching characteristics and carrier transport mechanisms were investigated. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used to confirm the structural properties of the device. Measurement of the time-dependent current-voltage (I-V-t) was used to characterize resistive switching and memristive behavior. The characteristic pinched hysteresis I-V loops of the memristor were apparent. Bipolar and homogeneous resistive switching characteristics and a forming voltage of 2 V were detected in the device. The retention time exceeded 103 s and the endurance test was reasonably acceptable. In addition, the carrier transport mechanism of the device was revealed. The linear region of the low electric field demonstrated ohmic behavior, whereas the non-linear high electric field region was dominated by a Schottky emission carrier transport mechanism. A Poole-Frenkel emission mechanism acted as a secondary conduction mechanism. It was proposed that the Poole-Frenkel and Schottky emission mechanisms were associated with oxygen vacancies in the TiO2.
AtıfScopus69WoS69OpenAlex77İncele