oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Effect of bending on anodized Ti6Al4V alloy: II. Behavior in vitro  [PDF]
E. Krasicka-Cydzik,A. Kierzkowska,I. Glazowska
Journal of Achievements in Materials and Manufacturing Engineering , 2006,
Abstract: Purpose: Evaluation of the influence of plastic deformation and characterization of the electrochemical behaviour of anodized implant rods made of the titanium alloy Ti6Al4V after immersion in air-saturated Ringer’s solution was presented in the paper.Design/methodology/approach: The specimens (dia 6 mm) were anodized and deformed by bending at angle 20o. The comparative characteristics of two zones: the max tensile (I) and the max. compressive stress (II) was based on the determination of electrochemical properties. Impedance spectra (EIS) and corrosion potential measurements were performed on 1, 6, 10 and 16th day after immersion in Ringer`s solution.Findings: Although bending caused an apparent decrease of the protective properties of the anodic layer, the characteristic two-layer anodic film and the values of corrosion potentials were restored due to immersion in Ringer’s solution. The regions of the compressive stresses show the much stronger tendency to restore.Research limitations/implications: The electrochemical tests in Ringer’s solution were performed only in static conditions. Fatigue tests in SBF are in progress.Practical implications: The explanation of the observed phenomena is proposed. Results of the work are of great importance for surgical practice in the pre-operative stage of spinal surgery procedures.Originality/value: Various stress zones formed on implant alloy during bending were described. The results of studies presented in the paper evidenced that changes noticed in the electrochemical behaviour in vitro in Ringer’s solution are advantageous with regard to the protective properties of the investigated alloy.
Influence of bone union electrostimulation on corrosion of Ti6Al4V ELI alloy implants  [PDF]
J. Szewczenko,K. Nowińska,M. Basiaga
Journal of Achievements in Materials and Manufacturing Engineering , 2008,
Abstract: Purpose: The aim of the work was determination of influence of the selected methods of bone union electrostimulation on corrosion of Ti6Al4V ELI alloy implants.Design/methodology/approach: In vitro tests were carried out with the use of different methods of electrostimulation – invasive, semi-invasive and non-invasive. The alternating current without constant component was applied. The influence of electrostimulation on corrosion of implants was evaluated on the basis of the mass measurements and surface observations.Findings: On the basis of the research no significant corrosion on the samples was observed. Only local surface etching was observed, however it didn’t cause measurable change of mass. The presence of metallic ions in the solution was revealed.Research limitations/implications: Lack of visible and measurable corrosion requires the change of the methodology. Further research should be focused on the amount of metallic ions dissolved from the implants. Furthermore, it should be emphasized that the absence of corrosion of the electrostimulated implants is only one of many criteria describing the usefulness of electrostimulation parameters. The basic criterion is the biological effect obtained as the result of the electrostimulation.Practical implications: The obtained results are the basis for selection of methods and current parameters of the bone union electrostimulation in further clinical research (for stabilizing elements made of titanium alloys). Positive results of the in vitro research confirmed in tests in animals can enable further clinical tests. Positive results of the clinical tests could enable the bone union electrostimulation applied in pathological fractures in patients allergic to Cr. Allergy to Cr and Ni limits a wide use of implants made of Cr-Ni-Mo steel.Originality/value: The paper is a continuation of the research on determining safe parameters of bone union electrostimulation of implants made of stainless steel coated with the passive and passive-carbon layers.
Effect of bending on anodized Ti6Al4V alloy: I. Surface layers characteristics  [PDF]
A. Kierzkowska,M. Malinowski,E. Krasicka-Cydzik
Journal of Achievements in Materials and Manufacturing Engineering , 2006,
Abstract: Purpose: The plastic deformation behaviour of the anodized binary titanium alloy Ti6Al4V was characterizedin mechanical and electrochemical tests.Design/methodology/approach: The effect of tensile and compressive stresses on properties of differentclinically relevant surfaces of the deformed by bending implant rods was investigated. The deformationbehaviour was characterized by FEM analysis. Relevant surfaces in tensile and compressive zones werecharacteristics by microhardness and roughness measurements, and electrochemical testing (Ecor, anodicpolarization, EIS) in oxygen-saturated Ringer’s solution.Findings: It was concluded that bending influenced mostly the properties of material in the tensile zone of thespecimen, whereas the properties of surface layer in the compressive zone and the properties of surface layer intensile zone after rebending are comparable and not so severe.Research limitations/implications: Studies were performed in static conditions, fatique studies are planned inthe future.Practical implications: Results are of great importance in for surgical practice in the in the evaluation of theinfluence of shaping process applied during pre-operative procedures on the performance of spinal implantsystems.Originality/value: In the paper a typical pre-operative procedure of shaping was applied to anodized titaniumimplants in order to evaluate its influence on the characteristics of the surface layer. Studies were focused onthe safety their application in vivo.
Effect of fluoride ions on Ti6Al4V alloy passivation in lactated Ringer's serum
Schmidt, Anelise M.;Azambuja, Denise S.;
Materials Research , 2003, DOI: 10.1590/S1516-14392003000200018
Abstract: the corrosive behavior of ti and its alloys in fluoride media is well known. based on electrochemical studies, this paper describes the effect of fluoride ions on the passive behavior of ti6al4v alloy in lactated ringer's serum. the open circuit potential of the alloy in the serum, which lies in the passive region of tio2, shifts to more negative values as fluoride ions are added. the voltammogram obtained in the serum presents an active-passive behavior close to -0.2 v (sce) that changes with the presence of fluoride ions, evidencing higher anodic currents. electrochemical impedance spectroscopy plots obtained at ocp after varying immersion times in the serum display an almost capacitive behavior and the polarization resistance becomes enhanced after 7 days. with the addition of fluoride ions, the film's resistance decreases, but a stable protective layer develops after 7 days of immersion time, indicating the film's repair.
Effect of fluoride ions on Ti6Al4V alloy passivation in lactated Ringer's serum
Schmidt Anelise M.,Azambuja Denise S.
Materials Research , 2003,
Abstract: The corrosive behavior of Ti and its alloys in fluoride media is well known. Based on electrochemical studies, this paper describes the effect of fluoride ions on the passive behavior of Ti6Al4V alloy in lactated Ringer's serum. The open circuit potential of the alloy in the serum, which lies in the passive region of TiO2, shifts to more negative values as fluoride ions are added. The voltammogram obtained in the serum presents an active-passive behavior close to -0.2 V (SCE) that changes with the presence of fluoride ions, evidencing higher anodic currents. Electrochemical impedance spectroscopy plots obtained at OCP after varying immersion times in the serum display an almost capacitive behavior and the polarization resistance becomes enhanced after 7 days. With the addition of fluoride ions, the film's resistance decreases, but a stable protective layer develops after 7 days of immersion time, indicating the film's repair.
Development and Characterization of Nanostructured Ti6Al4V Alloy  [cached]
Karimzadeh F.,Salehikahrizsangi P.,Enayati M.-H.,Abbasi M.-H.
Proceedings of the International Conference Nanomaterials : Applications and Properties , 2012,
Abstract: Nanostructured Ti6Al4V alloy was successfully formed through mechanical alloying of a stoichiometric mixture of Ti, Al and V powders. Phase evolutions of the milled powders were investigated by XRD. The Ti(Al,V) solid solution formed after 10 h milling. Prolongation of the milling process up to 20 h lead to a structure consisting of the B-Ti phase in th a-Ti(Al) matrix. The nanostructured Ti6Al4V alloy had a grain size and hardness of about 20 nm and 600 Hv respectively. Thermal stability of the alloyed powder was good and it's hardness increased to about 950 Hv after 5 h heat treatment at 1100 C.
Tribocorros?o da liga TI6AL4V em solu??o salina tamponada com fosfato
Manhabosco, Taíse M.;Muller, Iduvirges L.;Santos, Claudia B. dos;
Química Nova , 2009, DOI: 10.1590/S0100-40422009000900004
Abstract: the tribocorrosion behavior of ti6al4v alloy was investigated in a phosphate buffered saline (pbs) solution by a reciprocating wear, using alumina ball as the counterface material, at different normal forces and sliding velocities. dry wear experiments were performed in order to compare with the tribocorrosion experiments at open circuit potential and under anodic polarization. dry wear induced a superior damage on the counterface, forming larger and shallower wear tracks compared with those experiments performed in pbs solution. the anodic current was increased by wear; however the volume of oxidized metal in tribocorrosion experiments correspond to a relative low percentage of the wear track volume.
Obtención de recubrimientos de fosfatos de calcio sobre TI6AL4V ELI mediante electrodeposición catódica  [cached]
Enelfo Millan Castro,Hugo Armando Estupi?án,Darío Yesid Pe?a B.
Scientia Et Technica , 2007,
Abstract: En este estudio se obtuvo recubrimientos de fosfatos de calcio sobre sustratos de Ti6Al4V ELI ASTM F-136, los cuales fueron previamente tratados a partir de una mezcla de ácidos HCl: H2SO4: H2O (1:1:1), con el fin de obtener una mayor rugosidad y así mejorar la adherencia del depósito. Las variables estudiadas fueron agitación (600 y 800 rpm), temperatura (25 y 60°C) y voltaje (-9 y -15 V). Los depósitos obtenidos se caracterizaron por SEM-EDS y TF-IR. se pudo concluir que a temperatura ambiente no hay precipitación de fosfatos, y a 60°C se obtuvieron relaciones Ca/P entre 1.35 y 2.3.
Breakdown and Pitting Formation of Anodic Film Aluminum Alloy (3003)  [cached]
Sami A. Ajeel,Nahidh W. Kasser,M.Sc. Basheer A. Abdul-Hussein
Modern Applied Science , 2010, DOI: 10.5539/mas.v4n5p87
Abstract: Aluminum alloy (3003) has been anodized using sulfuric acid solution. To study the characteristic of the anodic film of aluminum alloy (3003); four variables are examined in term of anodic film thickness, these are current density ranging between 1.5- 3.5 A/dm2, electrolyte concentration ranging between 10- 20 Vol.%, electrolyte temperature between 10- 30oC and anodizing time between 10- 50 min. The study shows that the time of anodizing and current density has positive dependence of great significance on the anodic film thickness of aluminum alloy (3003) while the other two studied variables (i.e. concentration and temperature of electrolyte) show little dependence on the film thickness. When conditional Hookes and Jeeves optimization method is used, optimum conditions of aluminum alloy (3003) in terms of maximum thickness are found equal to: Current density (A /dm2) 3.5 Acid concentration (Vol. %) 10 Electrolyte temperature (oC) 19 Time of anodizing (min.) 50 Aluminum alloy (3003) specimens at optimum conditions are anodized and comparison studies between anodized and un-anodized specimens are carried out in terms of: 1) the roughness and hardness of anodic film. 2) the corrosion rates in 3.5% NaCl solution by: a) immersion test. b) polarization curves. 3) examining microstructure before and after anodizing of both types and their corrosion specimens by optical microscope and X-ray diffraction. In general, it is found that the surface roughness and hardness values for the anodized specimens are greater than that of un-anodized specimens because of the very much thicker oxide coating compare with the natural oxide (atmospheric oxide) whose improved physical and chemical properties. Also, the corrosion rates for anodized specimens are lower than that for un-anodized ones. The polarization behavior for anodizing alloy shows that the breakdown potentials are shifted to more noble direction than bare metals due to anodizing. The study also shows that the Breakdown of passive film and pitting formation occurred at (-661mV) for un-anodized alloy, while (-410 V) for anodized alloy. The observed pits are clearly not deep and small in size in large numbers compared with the unanodized specimens.
Diode laser surface modification of Ti6Al4V alloy to improve erosion wear resistance  [PDF]
A. Lisiecki,A. Klimpel
Archives of Materials Science and Engineering , 2008,
Abstract: Purpose: Purpose of this paper : The purpose of the study was to develop new laser alloying technologyproviding high erosion wear resistance of the working surfaces of blades made of titanium alloy Ti6Al4V.Design/methodology/approach: High power diode laser HPDL with a rectangular laser beam spot ofmultimode and uniform intensity of laser radiation was applied in the process of laser surface modification of thetitanium alloy Ti6Al4V. During the laser surface remelting and alloying of the titanium alloy in argon and nitrogenatmospheres, surface layers of high hardness and significantly higher erosion wear resistant, compared with thebase material of titanium alloy Ti6Al4V, were produced.Findings: The surface layers are composites of titanium nitrides participations in the titanium alloy matrix.Hardness of the surface layers and erosion wear resistance depends strongly on parameters of laser processing andon the partial pressure of nitrogen in the gas mixture of nitrogen-argon atmosphere.Research limitations/implications: The most critical parameter of the functional quality of titanium alloyblades of turbofan engine and steam turbines is the fatigue strength, therefore further investigations are required todetermine the fatigue strength and also internal stresses in the nitrided surface layers.Practical implications: The novel technology of high power diode laser surface modification of the titaniumalloy Ti6Al4V can be applied to produce erosion wear resistant and long lifetime surface layers of turbofan engineblades and steam turbine blades.Originality/value: The laser surface modification of titanium alloy by the high power diode laser with therectangular laser beam spot of multimode and uniform intensity of laser radiation is very profitable in a case oflaser surface remelting and alloying because the treated surface is heated uniformly, so uniform penetration depthand uniform thickness of the surface layer can be achieved, as opposed from circular laser beams of solid statesYAG and gas lasers.
Page 1 /100
Display every page Item


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