Browsing by Author "Oztarhan A."

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    Investigation on the tribology of Zr ion implanted tool steel
    (2002) Akbas N.; Oztarhan A.; Monteiro O.R.; Brown I.G.
    AISI D3 tool steel was ion implanted with zirconium and the improvement in surface tribological properties investigated. The Zr ion implantation was done using a metal vapor vacuum arc (Mevva) broad-beam ion source, with a mean ion energy of 130 keV and at doses of 3.6 × 1016, 5 × 1016 and 1 × 1017 ions/cm2. Wear, friction and hardness of the implanted samples were measured and compared to the performance of unimplanted steel. The wear resistance was increased by about a factor of two, the friction remained about the same or was possibly increased by a small amount and the near-surface hardness was improved by a factor of five or more by the ion implantation. We also investigated the effect on the Zr implantation profile of the multi-component energy distribution of the ion beam. © 2002 Elsevier Science B.V. All rights reserved.
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    Comparative study of wear mechanism of surface treated AISI 316L stainless steel
    (Emerald Group Publishing Ltd., 2003) Dogan H.; Findik F.; Oztarhan A.
    Coating is a technique employed for the surface of materials to have thermal insulation, hot corrosion and oxidation resistance. Ion implantation forms modifications in surface composition or morphology of solids which yield to a change of physical and especially mechanical properties such as hardness and modulus of elasticity. The objective of this investigation is to concentrate on the friction and wear behaviour of TiN, N2 and Zr implanted and TiN and Tinalox PVD coated 316L stainless steel and compare with a substrate, Mainly stainless steels were of attraction, because they frequently demonstrate a poor tribological behaviour, which can be enhanced when they are hardened by incorporating N2, TiN Tinalox and Zr and forming a hardened surface zone.
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    Tribological studies of ZrO2-implanted on stainless steel substrate
    (2004) Dogan H.; Findik F.; Oztarhan A.
    The tribological properties such as surface hardness, friction and wear have been studied for AISI 316L stainless steel substrates which were co-ion implanted with zirconium and oxygen ions. It is found that the wear resistance for AISI 316L stainless steel substrates implanted with zirconium and oxygen ions increased quite a lot. It is concluded that the increase in surface microhardness and the decrease in friction coefficient of AISI 316L stainless steel substrates play an important role in improving the wear resistance, and the relationship between relative wear volume and microhardness is correlated for zirconium and oxygen co-ion implantation. © Emerald Group Publishing Limited.
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    A study of the mechanical properties of TiN coating of Cr-Ni alloy
    (2005) Tek Z.; Gügör M.A.; Çal E.; Sonugelen M.; Artunç C.; Oztarhan A.
    Cr-Ni (Wirolloy) alloy is a material that is commonly used in dentistry for many reasons. The aim of this study is to investigate the mechanical properties of TiN-coated Cr-Ni alloy. Using PVD magnetron-sputtering technique coated samples. Coefficient of friction of PVD TiN-coated samples decreased from 0.59 to 0.52 compared to the uncoated ones. Coefficient of friction was measured and CSEM Tribotester obtained wear tracks. Wear volumes were measured by using MAHR Perthometer and it was found that the wear volume of TiN-coated sample was less than the uncoated one by a factor of 4. The surface hardness values of samples were measured by using CSEM nanohardness tester and it was found that the surface hardness of TiN-coated sample increased by a factor of 7.7 compared to the uncoated one. © 2004 Elsevier B.V. All rights reserved.
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    Thermal characterization of Ag and Ag + N ion implanted ultra-high molecular weight polyethylene (UHMWPE)
    (2007) Sokullu Urkac E.; Oztarhan A.; Tihminlioglu F.; Kaya N.; Ila D.; Muntele C.; Budak S.; Oks E.; Nikolaev A.; Ezdesir A.; Tek Z.
    Most of total hip joints are composed of ultra-high molecular weight polyethylene (UHMWPE ). However, as ultra-high molecular weight polyethylene is too stable in a body, wear debris may accumulate and cause biological response such as bone absorption and loosening of prosthesis. In this study, ultra-high molecular weight polyethylene samples were Ag and Ag + N hybrid ion implanted by using MEVVA ion implantation technique to improve its surface properties. Samples were implanted with a fluence of 1017 ion/cm2 and extraction voltage of 30 kV. Implanted and unimplanted samples were investigated by thermo-gravimetry analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), optical microscopy (OM) and contact Angle measurement. Thermal characterization results showed that the ion bombardment induced an increase in the % crystallinity, onset and termination degradation temperatures of UHMWPE. © 2007 Elsevier B.V. All rights reserved.
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    Modification of surface morphology of UHMWPE for biomedical implants
    (Materials Research Society, 2007) Oztarhan A.; Urkac E.S.; Kaya N.; Yenigul M.; Tihminlioglu F.; Ezdesir A.; Zimmerman R.; Budak S.; Muntele C.; Chhay B.; Ila D.; Oks E.; Nikolaev A.; Tek Z.; Eltem R.
    Ultra High Molecular Weight Polyethylene (UHMWPE) samples were implanted with metal and metal-gas hybrid ions (Ag, Ag+N, C+H, C+H+Ar, Ti+O) by using improved MEVVA Ion implantation technique [1,2]. An extraction voltage of 30 kV and influence of 1017 ions/cm2 were attempted in this experiment, to change their surface morphologies in order to understand the effect of ion implantation on the surface properties of UHMWPEs. Characterizations of the implanted samples with RBS , ATR - FTIR, spectra were compared with the un-implanted ones . Implanted and unimplanted samples were also thermally characterized by TGA and DSC. It was generally observed that C-H bond concentration seemed to be decreasing with ion implantation and the results indicated that the chain structure of UHMWPE were changed and crosslink density and polymer crystallinity were increased compared to unimplanted ones resulting in increased hardness. It was also observed that nano size cracks (approx.10nm) were significantly disappeared after Ag implantation, which also has an improved antibacterial effect. Contact angle measurements showed that wettability of samples increased with ion implantation. Results showed that metal and metal+gas hybrid ion implantation could be an effective way to improve the surface properties of UHMWPE to be used in hip and knee prosthesis. © 2007 Materials Research Society.
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    Neural cell attachment on metal ion implanted glass surfaces
    (2012) Sokullu-Urkac E.; Oztarhan A.; Deliloglu-Gurhan I.; Gulce-Iz S.; Feyzan O.-K.; Brown I.G.
    We have explored the application of ion implantation as a tool for the enhancement of neural cell growth on glass surfaces. Glass substrates were ion implanted with gold and with carbon using a metal vapor vacuum arc (MEVVA) ion source-based implantation system at Ege University Surface Modification Laboratory. The implantation dose was varied over the range 10 14-1017 ions/cm2 and the ion energy spanned the range 20-80 keV. B35 neural cells were seeded and incubated on the implanted substrates for 48h at 37°C. After 2-days in culture the cell attachment behavior was characterized using phase contrast microscopy. The adhesion and direct contact of neural cells on these ion implanted glass surfaces were observed. © 2011 Materials Research Society.