Physics / Fizik

Permanent URI for this collectionhttps://hdl.handle.net/11147/6

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Department: search.filters.department.İzmir Institute of Technology. ChemistryWoS Q: search.filters.wosQuartile.Q1

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  • Article
    Citation - WoS: 67
    Citation - Scopus: 80
    Metal Ion Release From Tin Coated Cocrmo Orthopedic Implant Material
    (Elsevier Ltd., 2006) Türkan, Uğur; Öztürk, Orhan; Eroğlu, Ahmet Emin
    In this study, a medical grade CoCrMo alloy was coated with TiN by means of physical vapor deposition (PVD) technique at 550 °C for 6 h. The TiN layer microstructure and thickness were studied by X-ray diffraction (XRD) and cross-sectional scanning electron microscopy (SEM). The adhesive strength of the TiN coatings on the CoCrMo substrate was studied by a commercially available Scanning Scratch Tester. Static immersion test was conducted to investigate the effectiveness of TiN coating in preventing the dissolution of metal ions into the simulated body fluid (SBF) from the substrate by atomic absorption spectrometry (AAS) and inductively coupled plasma optical emission spectrometry (ICP-OES). The XRD results showed that the PVD coated TiN films exhibited (111) preferred orientation, while the SEM analysis indicated quite uniform and highly dense TiN coated layer (about 3 μm thick) with a columnar growth mode reaching from substrate to coating surface. The scratch test results showed that the adhesive strength between the TiN film and the CoCrMo substrate was adequate. The AAS and ICP-OES results showed that the presence of the TiN coating prevented the release of cobalt and chromium metal ions from the substrate CoCrMo alloy whereas cobalt was preferentially dissolved from the as-polished material. Calcium phosphate precipitation was observed on the surface of the as-polished material, indicating a degree of bioactivity of the as-polished surface which is absent in the TiN coated substrate alloy.
  • Article
    Citation - WoS: 82
    Citation - Scopus: 92
    Metal Ion Release From Nitrogen Ion Implanted Cocrmo Orthopedic Implant Material
    (Elsevier Ltd., 2006) Öztürk, Orhan; Türkan, Uğur; Eroğlu, Ahmet Emin
    CoCrMo alloys are used as orthopedic implant materials because of their excellent mechanical and corrosion properties. However, when placed in vivo, these alloys release Co, Cr, Mo ions to host tissues, which may give rise to significant health concerns over time. Nitrogen ion implantation can be used to form protective layers on the surface of CoCrMo orthopedic alloys by modifying the near surface layers of these materials. In this study, medical grade CoCrMo alloy (IS0 5832-12) was ion implanted with 60 keV nitrogen ions to a high dose of 1.9 × 10 18 ions/cm 2 at substrate temperatures of 100, 200 and 400 °C. The N implanted layer microstructures, implanted layer phases, and thicknesses were studied by a combination of Bragg-Brentano (θ/2θ) and grazing incidence (Seeman-Bohlin) X-ray diffraction (XRD and GIXRD) and cross-sectional scanning electron microscopy (SEM). Atomic force microscopy (AFM) was used for roughness analysis of N implanted as well as as-polished surfaces. Static immersion tests were performed to investigate metal ion release into simulated body fluid (SBF) by electrothermal atomic absorption spectrometry (ETAAS) and inductively coupled plasma optical emission spectrometry (ICP-OES). XRD and SEM analyses indicated that the N implanted layers were ∼ 150-450 nm thick and composed of the (Co,Cr,Mo) 2+xN nitride phase and a high N concentration Co-based FCC phase, γ N depending on the substrate temperature. ETAAS analysis results showed that in vitro exposure of the N implanted surfaces resulted in higher levels of cobalt ion release into the simulated body fluid compared to the untreated, polished alloy. The higher Co release from the N implanted specimens is attributed to the nature of the implanted layer phases as well as to the rougher surfaces associated with the N implanted specimens compared to the relatively smooth surface of the untreated material. SEM analysis of N implanted and untreated specimens after immersion tests clearly indicated calcium phosphate formation on the as-polished CoCrMo alloy, indicating a degree of bioactivity of the untreated metal surface which is absent in the N implanted specimens.