Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
The effect of polarisation on the electrochemical behavior of Ti-13Nb-13Zr alloy
Assis, Sérgio Luiz de;Costa, Isolda;
Materials Research , 2007, DOI: 10.1590/S1516-14392007000300014
Abstract: the effect of potentiostatic polarisation on the electrochemical behavior of the ti-13nb-13zr alloy was investigated by electrochemical impedance spectroscopy (eis) and potentiodynamic polarisation curves in hanks' solution at 37 °c. potentiodynamic polarisation curves show a passive behavior with a slight current increase as potentials around 1300 mv(sce). based on these curves, different potentials were chosen to perform potentiostatic eis experiments. eis experimental data were interpreted using different equivalent circuits associated with the duplex nature of the oxide layer. the fitting procedure evidenced the thickening of a defective oxide layer with the applied potentials, corresponding to key points in the potentiodynamic polarisation curves.
Electrochemical behavior of Ni-Ti alloy after surface modification  [PDF]
M. Kaczmarek,W. Simka,A. Baron,J. Szewczenko
Journal of Achievements in Materials and Manufacturing Engineering , 2006,
Abstract: Purpose: The shape memory effect and superelasticity make the nickel-titanium alloy an interesting material formedical applications. But the biocompatibility has been questioned due to conflicting results in the literature.The latest research has shown that this situation may be caused by a variation in NiTi surface treatment.The appropriate surface treatment increases the corrosion resistance. The paper presents the electrochemicalbehavior of NiTi alloy after surface modification with the use of various techniques.Design/methodology/approach: The evaluation of the electrochemical behavior of NiTi alloy was realizedboth by recording of anodic polarization curves with the use of the potentiodynamic method and by anelectrochemical impedance spectroscopy technique (EIS).Findings: Surface condition of metallic biomaterial determines its corrosion resistance. In the course of thework it was observed that the lowest values of corrosion current were recorded for the sterilized and thethermally passivated samples. The highest values of corrosion current were recorded for the ground samples.These samples obviously had also the highest corrosion rate.Research limitations/implications: The obtained results are the basis for the optimization of physicochemicalproperties of the metallic biomaterial. The future research should be focused on selected specific implantsspecially with respect to their application features.Practical implications: On the basis of the obtained results it can be stated that the suggested surface treatmentcan be applicable for medical implants due to the increase of the corrosion resistance and in consequence theincrease of biocompatibility.Originality/value: The paper presents the influence of various methods of the surface treatment on corrosionresistance of the NiTi alloy. The suggested methods can be applied in treatment of the material intended formedical applications especially in cases where the surface roughness plays important role.
Structure and Electrochemical Characteristics of Ti―V―based Solid Solution/AB5―type La―Mg―based Alloy Composite Hydrogen Storage Material
WANG Yan-Zhi, ZHAO Min-Shou
无机材料学报 , 2012, DOI: 10.3724/sp.j.1077.2012.00463
Abstract: Composite hydrogen storage alloy Ti0.10Zr0.15V0.35Cr0.10Ni0.30 + 5wt% La0.85Mg0.25Ni4.5Co0.35Al0.15 was prepared by two―step arc melting. X―ray diffractometry (XRD) and scanning electron microscope―energy dispersive spectroscopy (SEM―EDS) show that the main phase of the composite alloy consists of V―based solid solution phase with BCC structure and C14 Laves phase with hexagonal structure, while secondary phase also exists in the composite alloy. Electrochemical studies show that distinct synergetic effect appears during the composite process. The real maximum discharge capacity of the composite alloy electrode is 361.8 mAh/g at 303 K, and the low temperature dischargeability (LTD) of the composite alloy electrode is 4.05 times as high as that of the matrix alloy electrode at 233 K. The high rate dischargeability (HRD), the charge–transfer resistance (Rct) and the exchange current density (I0) of the composite alloy electrode are 26.87 % bigger, 37.25 mΩ lower and 115.45 mA/g higher than that of the matrix alloy electrode, respectively. The hydrogen diffusion coefficient (D) in the bulk of the composite alloy is 6.13×10―10 cm2/s bigger than that of the matrix alloy.
Corrosive-Wear Behavior of Mo Modified Ti6Al4V Alloy by Wear-Electrochemical Noise Method

ZHANG Min,MA Yong,ZHANG Xiang-yu,FAN Ai-lan,TANG Bin,

摩擦学学报 , 2012,
Abstract: The Mo surface modified layer on Ti6Al4V substrate is obtained by plasma surface alloying. The structure and composition of the Mo surface modified layer are investigated by X-ray diffraction (XRD) and glow discharge optical emission spectroscopy. The duplex Mo modified layer contains a pure Mo coating on subsurface and diffusion layers between the subsurface and substrate. XRD analysis of the Mo modified layer reveals that a Mo phase exists in the modified layer with <110> and <211> orientations in the subsurface. Corrosion-wear behaviors of Ti6Al4V substrate and Mo modified Ti6Al4V alloy sliding against corundum are investigated with the wear-electrochemical noise technique in a 0.5mol/L NaCl solution. Results indicate that the Mo modified layer improves the antiwear and friction reduction properties of Ti6Al4V. Moreover, the Mo modified layer improves self-corroding electric potentials and decrease the current of Ti6Al4V. The Mo modified layer can improve the corrosion-wear behavior of Ti6Al4V.
In Vitro Corrosion Studies of Surface Modified NiTi Alloy for Biomedical Applications  [PDF]
Manju Chembath,J. N. Balaraju,M. Sujata
Advances in Biomaterials , 2014, DOI: 10.1155/2014/697491
Abstract: Electropolishing was conducted on NiTi alloy of composition 49.1 Ti-50.9 Ni at.% under potentiostatic regime at ambient temperature using perchloric acid based electrolyte for 30?sec followed by passivation treatment in an inorganic electrolyte. The corrosion resistance and biocompatibility of the electropolished and passivated alloys were evaluated and compared with mechanically polished alloy. Various characterization techniques like scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy were employed to analyze the properties of surface modified and mechanically polished alloys. Water contact angle measurements made on the passivated alloy after electropolishing showed a contact angle of 35.6°, which was about 58% lower compared to mechanically polished sample, implying more hydrophilicity. The electrochemical impedance studies showed that, for the passivated alloy, threefold increase in the barrier layer resistance was obtained when compared to electropolished alloy due to the formation of compact titanium oxide. The oxide layer thickness of the passivated samples was almost 18 times higher than electropolished samples. After 14 days immersion in Hanks’ solution, the amount of nickel released was 315?ppb which was nearly half of that obtained for mechanically polished NiTi alloy, confirming better stability of the passive layer. 1. Introduction Binary NiTi alloys containing 50-51?at.% Ni are widely used for biomedical applications owing to their unique shape memory as well as superelastic properties and are preferred over conventional implant materials like Co-Cr-Mo alloys and stainless steel for specific applications [1]. These alloys are reported to exhibit surface passivity due to the presence of native titanium oxide layer which prevents the alloy from corrosion under the influence of body fluids and hence they possess superior biocompatibility compared to stainless steel [2, 3]. In spite of its remarkable properties, nickel elution is still a major issue of concern in using NiTi alloys, as high nickel content creates serious health hazards when implanted into human body. Human physiological environment is complex and the biocompatibility of the material needs to be established prior to use as an implant device. Nickel elution on immersion of NiTi in simulated body fluids (SBF) has been studied by various researchers [4–6]. Since nickel elution produces severe allergic issues, many of the research works on NiTi alloys were focused on improving the biocompatibility and corrosion resistance by suitable surface
Electrochemical Evaluation of Wrought Titanium -15 Molybdenum Alloy for Dental Implant Applications in Phosphate Buffer Saline
Bhola,Rahul; Bhola,Shaily M.; Mishra,Brajendra; Olson,David L.;
Portugaliae Electrochimica Acta , 2010,
Abstract: ti-15mo alloy has been evaluated for its electrochemical behavior in phosphate buffer saline solution at the physiological temperature of 37 oc. a two time constant model of a duplex oxide layer has been used to assess the corrosion behavior of the ti-15mo alloy-solution interface using electrochemical impedance spectroscopy (eis). interfacial characteristics of the inner barrier layer and the outer porous layer have been studied to understand the role of the alloy as an implant. ti-15mo alloy shows a very high barrier layer resistance and a tendency to resist localized corrosion.
Electrochemical Evaluation of Wrought Titanium -15 Molybdenum Alloy for Dental Implant Applications in Phosphate Buffer Saline  [cached]
Rahul Bhola,Shaily M. Bhola,Brajendra Mishra,David L. Olson
Portugaliae Electrochimica Acta , 2010,
Abstract: Ti-15Mo alloy has been evaluated for its electrochemical behavior in phosphate buffer saline solution at the physiological temperature of 37 oC. A two time constant model of a duplex oxide layer has been used to assess the corrosion behavior of the Ti-15Mo alloy-solution interface using electrochemical impedance spectroscopy (EIS). Interfacial characteristics of the inner barrier layer and the outer porous layer have been studied to understand the role of the alloy as an implant. Ti-15Mo alloy shows a very high barrier layer resistance and a tendency to resist localized corrosion.
Comparisons of immersion and electrochemical properties of highly biocompatible Ti–15Zr–4Nb–4Ta alloy and other implantable metals for orthopedic implants  [cached]
Yoshimitsu Okazaki,Hiroyuki Nagata
Science and Technology of Advanced Materials , 2012,
Abstract: Metal release from implantable metals and the properties of oxide films formed on alloy surfaces were analyzed, focusing on the highly biocompatible Ti–15Zr–4Nb–4Ta alloy. The thickness and electrical resistance (Rp) of the oxide film on such an alloy were compared with those of other implantable metals. The quantity of metal released during a 1-week immersion test was considerably smaller for the Ti–15Zr–4Nb–4Ta than the Ti–6Al–4V alloy. The potential (E10) indicating a current density of 10 μA cm 2 estimated from the anodic polarization curve was significantly higher for the Ti–15Zr–4Nb–4Ta than the Ti–6Al–4V alloy and other metals. Moreover, the oxide film (4–7 nm thickness) formed on the Ti–15Zr–4Nb–4Ta surface is electrochemically robust. The oxide film mainly consisted of TiO2 with small amounts of ZrO2, Nb2O5 and Ta2O5 that made the film electrochemically stable. The Rp of Ti–15Zr–4Nb–4Ta was higher than that of Ti–6Al–4V, i.e. 0.9 Ω cm2 in 0.9% NaCl and 1.3 Ω cm2 in Eagle's medium. This Rp was approximately five-fold higher than that of stainless steel, which has a history of more than 40 years of clinical use in the human body. Ti–15Zr–4Nb–4Ta is a potential implant material for long-term clinical use. Moreover, E10 and Rp were found to be useful parameters for assessing biological safety.
Electrochemical behavior of Ti and Ti6Al4V in aqueous solutions of citric acid containing halides
Schmidt, Anelise Marlene;Azambuja, Denise Schermann;
Materials Research , 2006, DOI: 10.1590/S1516-14392006000400008
Abstract: this paper reports on an investigation of the electrochemical behavior of ti grade 2 and ti6al4v alloy in aqueous citric acid solutions with ph 2.0 containing halide ions. voltammetric studies of ti and the alloy in citric acid, with and without chloride ions, indicate that the ti and ti alloy presented a passive behavior in the test solutions used. pitting was observed at 3.0 and 2.5 v/sce for ti and ti6al4v, respectively, when bromide ions were added to the solution. in solutions containing fluoride ions, dissolution of the film occurred at potentials close to - 1.0 v/sce in both electrodes. the iodide ions oxidized on the passive oxide film at potentials close to 1.0 v/sce. eis results of the materials in citric acid solutions containing chloride ions revealed that the film's resistance increased as the applied potential rose from 0 to 1.0 v. in bromide-containing solutions, breakdown of the film was confirmed at potentials above 2.0 v/sce in both electrodes. these results suggest film reformation for ti and the alloy in solutions containing fluoride at potentials within the passive region.
Influence of proteins from physiological solutions on the electrochemical behaviour of the Ti-6Al-4V alloy: reproducibility and time-frequency dependence. ---- Influence de la teneur en protéines de solutions physiologiques sur le comportement électrochimique du Ti-6Al-4V : reproductibilité et représentation temps-fréquence  [PDF]
Jean Geringer,Laurent Navarro,Bernard Forest
Quantitative Biology , 2010, DOI: 10.1051/mattech/2010020
Abstract: The electrochemical behaviour of the biomedical and metallic alloys, especially in the orthopaedic implants fields, raises many questions. This study is dedicated for studying the Ti-6Al-4V alloy, by electrochemical impedance spectroscopy, EIS, in various physiological media,: Ringer solution, phosphate buffered solution (PBS), PBS solution and albumin, PBS solution with calf serum and PBS solution with calf serum and an antioxidant (sodium azide). Moreover, the desionised water was considered as the reference solution. The tests reproducibility was investigated. The time-frequency-Module graphs highlighted that the desionised water is the most protective for the Ti-6Al-4V alloy. This biomedical alloy is the less protected in the solution constituted by PBS and albumin. The time-frequency graph allows pointing out the graphic signatures of adsorption for organic and inorganic species (differences between the modules means in studied solution and the modules mean in the reference solution). --- Le comportement \'electrochimique des alliages m\'etalliques biom\'edicaux, notamment dans le domaine des implants orthop\'ediques, pose encore de nombreuses questions. Ce travail propose d'\'etudier l'alliage de titane Ti-6Al-4V, par spectroscopie d'imp\'edance \'electrochimique, SIE, dans diff\'erents milieux physiologiques : solution de Ringer, solution \`a base d'un tampon phosphate (PBS), solution PBS avec de l'albumine, solution PBS avec du s\'erum bovin et une solution PBS avec du s\'erum bovin et un antioxydant (azoture de sodium). De plus, une solution d'eau ultra-pure servira de r\'ef\'erence. La reproductibilit\'e des tests a \'et\'e \'etudi\'ee. Les repr\'esentations temps-fr\'equence des modules ont mis en \'evidence que l'eau d\'esionis\'ee est la solution qui pr\'esente le caract\`ere le plus protecteur pour le Ti-6Al-4V. Cet alliage de titane est le moins prot\'eg\'e dans la solution de PBS contenant de l'albumine. Cette repr\'esentation permet de mettre en \'evidence des signatures graphiques d'adsorption des esp\`eces inorganiques et organiques (diff\'erences entre les moyennes des modules dans les solutions \'etudi\'ees et la moyenne des modules dans la solution de r\'ef\'erence).
Page 1 /100
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.