Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 10Citation - Scopus: 10The Influence of Plasma-Based Nitriding and Oxidizing Treatments on the Mechanical and Corrosion Properties of Cocrmo Biomedical Alloy(Springer Verlag, 2018) Noli, Fotini; Öztürk, Orhan; Öztürk, Orhan; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyPlasma-based nitriding and/or oxidizing treatments were applied to CoCrMo alloy to improve its surface mechanical properties and corrosion resistance for biomedical applications. Three treatments were performed. A set of CoCrMo samples has been subjected to nitriding at moderate temperatures (~ 400 °C). A second set of CoCrMo samples was oxidized at 395 °C in pure O2. The last set of CoCrMo samples was nitrided and subsequently oxidized under the experimental conditions of previous sets (double treatment). The microstructure and morphology of the layers formed on the CoCrMo alloy were investigated by X-ray diffraction, Atomic Force Microscopy, and Scanning Electron Microscopy. In addition, nitrogen and oxygen profiles were determined by Glow Discharge Optical Emission Spectroscopy, Rutherford Backscattering Spectroscopy, Energy-Dispersive X-ray, and Nuclear Reaction Analysis. Significant improvement of the Vickers hardness of the CoCrMo samples after plasma nitriding was observed due to the supersaturated nitrogen solution and the formation of an expanded FCC γN phase and CrN precipitates. In the case of the oxidized samples, Vickers hardness improvement was minimal. The corrosion behavior of the samples was investigated in simulated body fluid (0.9 pct NaCl solution at 37 °C) using electrochemical techniques (potentiodynamic polarization and cyclic voltammetry). The concentration of metal ions released from the CoCrMo surfaces was determined by Instrumental Neutron Activation Analysis. The experimental results clearly indicate that the CoCrMo surface subjected to the double surface treatment consisting in plasma nitriding and plasma oxidizing exhibited lower deterioration and better resistance to corrosion compared to the nitrided, oxidized, and untreated samples. This enhancement is believed to be due to the formation of a thicker and more stable layer.Other Corrigendum To ‘‘the Effect of Surface Treatment on Cap Deposition of Ti6al4v Open Cell Foams in Sbf Solution.’’ [ceram. Int. 39 (2010) 1805–1816](Elsevier Ltd., 2011) Türkan, Uğur; Güden, Mustafa; Güden, Mustafa; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe authors regret that they accidentally omitted to refer to Prof. A.C. Tas, who originally found the SBF solution used in the experiments. The corrections to the affected sentences are listed below. ‘‘The SBF solution for in vitro tests was prepared by dissolving the following analytical reagents in 1 L of deionized water: 6.547 g of NaCl, 2.268 g of NaHCO3, 0.372 g of KCl, 0.124 g of Na2HPO4, 0.305 g of MgCl2 6H2O, 0.368 g of CaCl2 2H2O, 0.071 g of Na2SO4 and 6.057 g of trishydoxmethylaminomethane (A.C. Tas)’’. A.C. Tas, Synthesis of biomimetic Ca-hydroxyapatite powders at 37 8C in synthetic body fluids, Biomaterials 21 (14) (2000) 1429–1438.Article Citation - WoS: 16Citation - Scopus: 16The Effect of Surface Treatment on Cap Deposition of Ti6al4v Open Cell Foams in Sbf Solution(Elsevier Ltd., 2010) Türkan, Uğur; Güden, Mustafa; Güden, Mustafa; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe effects of alkali and nitric acid surface treatment and acid etching on the CaP deposition of an open cell Ti6Al4V foam (60% porous and 300–500 μm in pore size) developed for biomedical applications were investigated in a simulated body fluid (SBF) solution for 14-day. The surface roughness of the foam specimens ground flat surfaces was measured in nano-metric scale before and after SBF immersion using an atomic force microscope (AFM). A significant increase in the surface roughness of alkali treated foam specimen after SBF immersion indicated a smaller crystal size CaP deposition, which was also confirmed by the AFM micrographs. The microscopic evaluation clearly showed that alkali treatment and nitric acid treatment induced a continuous, uniform CaP deposition on the cell wall surfaces of the foam (interior of cells). While in untreated foam specimen the cells are filled with CaP precipitates and acid etching did not produce a continuous coating layer on particles interior of the cells. The coating layer thickness was ∼3 μm in alkali treated foam specimens after 14-day of SBF immersion, while nitric acid treatment induced relatively thinner coating layer, 0.6 μm.