Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleAçık Erişim2017Influence of Duplex Treatment on Structural and Tribological Properties of Commercially Pure Titanium
Çelik, Ilhan
Titanium and its alloys are widely used in many fields, including aerospace and the chemical and biomedical industries. This is due to their mechanical properties, excellent corrosion resistance, and biocompatibility although they do have poor wear resistance. In this study, a duplex layer was successfully formed on the commercially pure titanium surface by duplex treatments (plasma nitriding and physical vapor deposition (PVD)). In the initial treatment, plasma nitriding was performed on the pure titanium samples and in the second treatment, the nitrided samples were coated with CrN by PVD. The friction and wear properties of the duplex-treated samples were investigated for tribological applications. Surface morphology and microstructure of the duplex-treated samples were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). In addition, the tribological properties were investigated using pin-on-disc tribometer. A compound layer composed of ϵ-Ti2N and δ-TiN phases and a diffusion layer formed under the compound layer were obtained on the surface of pure titanium after the nitriding treatments. CrN coated on the nitrided surface provided an increase in the surface hardness and in the wear resistance.
- MakaleYalnız künye2016Influence of CrN Coating on Electrochemical Behavior of Plasma Nitrided Pure Titanium in Bio-simulated Environment
Çelik, Ilhan
Titanium and its alloys are widely used as materials for bio-medical applications, such as implants. However, ions of the alloy can release to the body region and spread into the blood circulation. In this study, plasma nitriding and CrN coating techniques are used in order to overcome the problem of ion release. The objective of this study was to investigate the effects of plasma nitrided pure titanium on the structural properties and corrosion behaviors before and after CrN coating in Ringer's solution at 37 °C. The structural properties were investigated using Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD). A diffusion layer and a compound layer composed of δ-TiN and ε-Ti2N phases were observed on the surface of nitrided pure titanium. Corrosion tests were made for the determination of electrochemical properties with the help of Potentiostat/Galvanostat device. The results show that corrosion behaviors of untreated and treated samples have similar characteristic.
- MakaleYalnız künye2016Effect of plasma nitriding treatment on structural, tribological and electrochemical properties of commercially pure titanium
Çelik, Ilhan; Karakan, Mehmet
In this study, plasma nitriding treatment was applied to commercially pure titanium (Grade 2). Structural properties, electrochemical and tribological behaviours of the nitrided pure titanium specimens were comparatively investigated. Microstructure and morphology of the plasma nitrided specimens were analysed by X-ray diffraction and scanning electron microscopy. Furthermore, corrosion tests were conducted in Ringer's solution, which represents a human body environment, to determine electrochemical properties. Then, tribological and frictional properties were investigated using pin-on-disc tribometer, and a micro-hardness tester was used to measure the hardness of the coatings. The results showed that plasma nitrided specimens exhibited higher surface hardness than the untreated specimens did. In addition, the plasma nitrided specimens at 700 °C presented significantly better performance than the other plasma nitrided specimens (at 500 °C and 600 °C) under dry wear conditions. Moreover, corrosion test results showed that corrosion behaviours of untreated and nitrided samples had similar characteristic.
- MakaleYalnız künye2016Investigation of structural and tribological properties of electroless Ni-B coated pure titanium
Çelik, Ilhan; Karakan, Mehmet; Bülbül, Ferhat
In the present study, the surface of commercial pure (Grade 2) titanium was coated with electroless Ni-B and, then, it was subjected to heat treatment for an hour at 400°. The surface morphology, microstructure and phase identification were analysed by X-ray diffraction and scanning electron microscope. Wear behaviour characterisation was carried out using a ball-on-disc tribometer. The results of the analyses showed that the electroless Ni-B coating had a significantly amorphous structure in the as-deposited condition. It was also determined that the coating structure crystallised after the heat treatment and wear resistance of pure titanium increased after electroless Ni-B coating. Particularly, upon the heat treatment, it was observed that wear resistance and surface hardness of pure titanium considerably increased.
- MakaleYalnız künye2014EFFECT OF HEAT TREATMENT ON STRUCTURE OF ELECTROLESS Ni-B COATED PURE TITANIUM
Bülbül, Ferhat; Çelik, Ilhan
Pure titanium has a very large potential for use industrially due to its low weight, however, its usage continues to be limited because it possesses some disadvantages such as low hardness and wear resistance, weak corrosion resistance in high temperatures and high cost. In order to strengthen these weaknesses of pure titanium, electroless Ni-B deposition process, may be an alternative solution. In this study, the Ni-B coatings were deposited on pure titanium and annealed at the temperatures of 450 degrees C, 650 degrees C and 850 degrees C. The non-heat treated and heat treated coatings were structurally characterized via SEM (scanning electron microscope) and XRD (x ray diffraction). These coatings transformed from amorphous structure to a pronounced crystalline structure depending on heat treatment.
- MakaleYalnız künye2014Effect of different surface oxidation treatments on structural, mechanical and tribological properties of ultrafine-grained titanium
Çelik, Ilhan; Alsaran, Akgün; Purcek, Gencaga
Four different surface oxidation treatments, so-called, anodizing oxidation (AO), micro-arc oxidation (MAO), plasma oxidation (PO) and thermal oxidation (TO), were applied to ultrafine-grained (UFG) pure titanium produced by equal-channel angular extrusion/pressing (ECAE/P). Before and after all treatments, mechanical, structural and tribological properties were investigated. The strength of pure titanium increased substantially after ECAE process. TiO2 phases included the anatase and/or the rutile formed on the surface of UFG Ti depending on oxidation treatments. High strength of UFG Ti was deteriorated by TO and PO treatments because of the recrystallization occurred at high-temperature, while applications of MAO and AO did not cause a significant decrease in its strength due to the prevention of recrystallization of UFG Ti. All oxidation treatments brought about a remarkable increase in wear resistance of UFG Ti because of the formation of adhered and hard TiO2 film developed on the surface. It was concluded that the AO and MAO treatments could be applied to the UFG Ti without any deteriorations in bulk mechanical and wear properties to obtain biocompatible pure titanium with high strength and excellent wear resistance.