Showing papers on "Titanium published in 2002"
TL;DR: In this article, the main metallic biomaterials are stainless steels, Co-based alloys, and titanium and its alloys and they are used for replacing failed hard tissue.
Abstract: Metallic biomaterials are mainly used for replacing failed hard tissue. The main metallic biomaterials are stainless steels, Co-based alloys, and titanium and its alloys. Recently, titanium alloys are getting much attention for biomaterials. The various kinds of new high strength α+β and low-modulus β-type titanium alloys composed of nontoxic elements, such as Nb, Ta, Zr, etc., are developed for biomedical applications because of the toxicity of alloying elements and lack of mechanical biocompatibility of conventional titanium alloys, such as Ti-6Al-4V. Recent research and development in other metallic alloys, such as stainless steels and Co-based alloys, also will be discussed.
1,215 citations
TL;DR: The surface properties of anodic oxides formed on commercially pure (c.p.) titanium screw implants as well as to study 'native' oxides on turned c.p. titanium implants are investigated to elucidate the influence of the oxide properties on the biological reaction.
486 citations
TL;DR: TiAl6V4 alloys have a good corrosion resistance as good as that of titanium in Fusayama Meyer saliva and acid salivary solution, except NiTi and NiTiCo alloys.
330 citations
TL;DR: In this article, the authors used X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) to evaluate the bioactivity of the modified Ti disks by incubating these disks in a physiological solution.
Abstract: Commercially pure titanium (cp Ti) is widely used in dental implantology. However, it is only passively integrated in bone and the resulting fixation in the bone, which is necessary for the function, is mainly mechanical in its nature. With the objective of increasing the chemical interaction between the implant and bone tissue, several phosphonic acids were synthesized and grafted onto titanium disks. The bare polished Ti disks (Ti P) and the grafting of three phosphonic acids (methylenediphosphonic acid (MDP), propane-1,1,3,3-tetraphosphonic acid (PTP), and ethane-1,1,2-triphosphonic acid (ETP)) on these disks were characterized with X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). These surface analytical techniques provided strong indications of the formation of a chemical link between the Ti implant and the phosphonic acid molecule. The bioactivity of the modified Ti disks was evaluated by incubating these disks in a physiological solution (Hank's ...
307 citations
TL;DR: In this paper, the thickness and structure of titania films produced under different conditions were determined by ellipsometry, infrared spectroscopy, and X-ray diffraction measurements, and the corrosion properties of these layers were investigated by current density-potential curves under physiological conditions.
Abstract: The excellent biocompatibility of titanium and its alloys used, for example, for medical devices, is associated with the properties of their surface oxide. For a better understanding of the tissue reaction in contact with the oxide layer, knowledge of the chemical and physical properties of this layer is of increasing interest. In this study, titania films were produced on cp-Ti and Ti6Al4V substrates by thermal oxidation, anodic oxidation, and by the sol-gel process. The thickness and structure of the films produced under different conditions were determined by ellipsometry, infrared spectroscopy, and X-ray diffraction measurements. The corrosion properties of these layers were investigated by current density–potential curves under physiological conditions. The oxide layers produced on cp-Ti and Ti6Al4V by thermal oxidation consist of TiO2 in the rutile structure. For the anodized samples the structure of TiO2 is a mixture of amorphous phase and anatase. The structure of the coatings produced by the sol-gel process for a constant annealing time depends on the annealing temperature, and with increasing temperature successively amorphous, anatase, and rutile structure is observed. Compared to the uncoated, polished substrate with a natural oxide layer, the corrosion resistance of cp-Ti and Ti6Al4V is increased for the samples with an oxide layer thickness of about 100 nm, independent of the oxidation procedure. © 2001 Wiley Periodicals, Inc. J Biomed Mater Res 59: 18–28, 2002
299 citations
TL;DR: In this paper, uniform hydroxyapatite (HA) coatings have been directly deposited on titanium at room temperature X-ray diffractometry (XRD) results demonstrated that dicalcium phosphate dihydrate (CaHPO4·2H2O, DCPD) was the main component of the coating.
295 citations
TL;DR: Titania gel layers obtained in the present study exhibited in vitro apatite deposition ability after the gel layers exceeded a minimum thickness and was subsequently heated in a proper temperature range (400-600 degrees C).
263 citations
TL;DR: Results demonstrate that oxygen-rich siloxide complexes of titanium are useful as precursors to supported epoxidation catalysts of high activity and selectivity.
Abstract: A molecular precursor approach involving simple grafting procedures was used to produce site-isolated titanium-supported epoxidation catalysts of high activity and selectivity. The tris(tert-butoxy)siloxy titanium complexes Ti[OSi(O(t)Bu)(3)](4) (TiSi4), ((i)PrO)Ti[OSi(O(t)Bu)(3)](3) (TiSi3), and ((t)BuO)(3)TiOSi(O(t)Bu)(3) (TiSi) react with the hydroxyl groups of amorphous Aerosil, mesoporous MCM-41, and SBA-15 via loss of HO(t)Bu and/or HOSi(O(t)Bu)(3) and introduction of titanium species onto the silica surface. Powder X-ray diffraction, nitrogen adsorption/desorption, infrared, and diffuse reflectance ultraviolet spectroscopies were used to investigate the structures and chemical natures of the surface-bound titanium species. The titanium species exist mainly in isolated, tetrahedral coordination environments. Increasing the number of siloxide ligands in the molecular precursor decreases the amount of titanium that can be introduced this way, but also enhances the catalytic activity and selectivity for the epoxidation of cyclohexene with cumene hydroperoxide as oxidant. In addition, the high surface area mesoporous silicas (MCM-41 and SBA-15) are more effective than amorphous silica as supports for these catalysts. Supporting TiSi3 on the SBA-15 affords highly active cyclohexene epoxidation catalysts (0.25-1.77 wt % Ti loading) that provide turnover frequencies (TOFs) of 500-1500 h(-1) after 1 h (TOFs are reduced by about half after calcination). These results demonstrate that oxygen-rich siloxide complexes of titanium are useful as precursors to supported epoxidation catalysts.
251 citations
TL;DR: Open-cellular titanium foams, with the pore size of 200–500 μm are expected to be a very promising biomaterial candidates for bone implants because its porous structure permits the ingrowths of new-bone tissues and the transport of body fluids.
Abstract: Pure titanium and some of its alloys are currently considered as the most attractive metallic materials for biomedical applications due to their excellent mechanical properties, corrosion resistance, and biocompatibility. It has been demonstrated that titanium and titanium alloys are well accepted by human tissues as compared to other metals such as SUS316L stainless steel and Co–Cr–Mo type alloy. In the present study, highly porous titanium foams with porosities ≤80% are produced by using a novel powder metallurgical process, which includes the adding of the selected spacers into the starting powders. The optimal process parameters are investigated. The porous titanium foams are characterized by using optical microscopy and scanning electron microscopy. The distribution of the pore size is measured by quantitative image analyses. The mechanical properties are investigated by compressive tests. This open-cellular titanium foams, with the pore size of 200–500 μm are expected to be a very promising biomaterial candidates for bone implants because its porous structure permits the ingrowths of new-bone tissues and the transport of body fluids.
251 citations
TL;DR: The experimental findings are believed to make a contribution to a better understanding of the interplay between industrial fabrication procedure and physico-chemical implant surface properties.
Abstract: The surfaces of five commercially available titanium implants (Branemark Nobel Biocare, 3i ICE, 3i OSSEOTITE, ITI-TPS, and ITI-SLA) were compared by scanning electron microscopy, X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectroscopy All five implant types were screw-shaped and fabricated from commercially pure (cp) titanium, but their surface properties differed both as regards surface morphology and surface chemical composition The macro- and microstructure of the implant surfaces were investigated by scanning electron microscopy The surfaces chemical composition was determined using the surface-sensitive analytical techniques of X-ray photoelectron spectroscopy and time-of-flight secondary ion spectrometry Surface topographies were found to reflect the type of mechanical/chemical fabrication procedures applied by the manufacturers The titanium oxide (passive) layer thickness was similar (5-6 nm) and typical for oxide films grown at or near room temperature A variety of elements and chemical compounds not related to the metal composition were found on some implant types They ranged from inorganic material such as sodium chloride to specific organic compounds believed to be due to contamination during fabrication or storage The experimental findings are believed to make a contribution to a better understanding of the interplay between industrial fabrication procedure and physico-chemical implant surface properties
231 citations
TL;DR: A novel CVD film of titanium(IV) oxide has been prepared on glass, via the reaction of titanium (IV) chloride and ethyl acetate, using a CVD technique as mentioned in this paper.
Abstract: A novel CVD film of titanium(IV) oxide has been prepared on glass, via the reaction of titanium(IV) chloride and ethyl acetate, using a CVD technique. The film is clear, very robust mechanically and comprised of a thin (24 nm) layer of nanocrystalline anatase titania that absorbs light of λ
TL;DR: In this article, a systematic characterization study has been carried out on different materials such as commercial purity titanium, Ti-6Al-4V, 316L stainless steel, and a cobalt-based alloy under simulated body fluid conditions at 37 °C.
TL;DR: The bis(beta-diketonato)titanium(IV) and titanocene derivatives appear to offer a different alternative for cancer chemotherapy which do not follow the rationale and mechanism of action of the platinum complexes.
Abstract: A series of complexes containing titanium, Ti, as a metal center has shown to possess a wide spectrum of antitumor properties. This series belongs to the non-platinum metal antitumor agents which has been developed mainly in the past 20 years. The bis(β-diketonato)titanium(IV) and titanocene derivatives appear to offer a different alternative for cancer chemotherapy which do not follow the rationale and mechanism of action of the platinum complexes. The hydrolysis of these complexes in aqueous and pseudo aqueous solutions is discussed and the interaction studies of titanium complexes with biomolecules are also presented to unravel the mechanism of action at molecular levels.
TL;DR: The results suggested that the pre-deposition of HA onto these functionalized SAM surfaces might be an effective and fast way to prepare biomimetic apatite coatings on surgical implants.
TL;DR: In this article, the surface adsorption of the substrates, as well as X-ray diffraction (XRD) and Brunauer−Emmet−Teller (BET) surface area measurements, were characterized by analysis of surface adhesions.
Abstract: Nanocrystalline anatase titanium(IV) oxide (TiO2) particles were synthesized by hydrothermal crystallization in organic media (HyCOM) followed by calcination at various temperatures up to 1273 K, and they were characterized by analysis of surface adsorption of the substrates, as well as by X-ray diffraction (XRD) and Brunauer−Emmet−Teller (BET) surface area measurements. These HyCOM TiO2 samples were used for three kinds of photocatalytic reactions: mineralization of acetic acid (AcOH) in aerated aqueous suspensions, dehydrogenation of 2-propanol (2-PrOH) by in situ platinized powders, and silver-metal deposition from silver ions (Ag+) in deaerated aqueous suspensions of bare TiO2 samples. Dependence of the photocatalytic activities on calcination temperature (Tc) and on the amount of adsorbed substrates in each reaction and correlations with the physical properties of HyCOM TiO2 were examined. In the case of mineralization of AcOH, the activitiy of each sample was almost proportional to the amount of su...
TL;DR: In this article, X-ray photoelectron spectroscopy (XPS) was used to construct self-assembled monolayers on smooth titanium oxide and titanium metal coated glass and silicon substrates, as well as on rough titanium metal implant surfaces.
Abstract: Dodecyl phosphate and hydroxy-terminated dodecyl phosphate are shown to spontaneously assemble on smooth titanium oxide and titanium metal coated glass and silicon substrates, as well as on rough titanium metal implant surfaces. The surfaces were dipped in aqueous solutions of the corresponding ammonium salts for 48 h. The molecules are shown by X-ray photoelectron spectroscopy (XPS) to form densely packed, self-assembled monolayers (SAMs) on all surfaces investigated. The phosphate headgroups are believed to attach to the titanium (oxide) surface with the terminal end group (either methyl or hydroxy) pointing toward the ambient environment (air, vacuum, or water). Mixed SAMs are shown to be formed from mixed aqueous solutions of the two amphiphiles, with the hydroxy-terminated dodecyl phosphate adsorbing more favorably than the methyl-terminated molecule. The advancing water contact angles can be easily tailored via the composition of the self-assembly solution in the range of 110° (pure methyl) to 55° (...
TL;DR: In the present work, a biocomposite was successfully fabricated from hydroxyapatite and titanium powders by powder metallurgy method and it is found that Ti2O has the ability to induce the formation of bone-like apatite in the SBF.
TL;DR: In this article, the effect of total pressure and the oxygen partial pressure on the deposition rate, the phase composition, the crystallinity, the surface morphology and the resulting photocatalytic properties was investigated.
Abstract: Crystalline titanium dioxide, TiO2, photocatalytic films were deposited by reactive r.f. magnetron sputtering on glass substrates without additional external heating. A pure metallic titanium target was sputtered in a mixture of argon and oxygen. The effect of the total pressure and the oxygen partial pressure on the deposition rate, the phase composition, the crystallinity, the surface morphology and the resulting photocatalytic properties was investigated. The films were characterized by X-ray diffraction, scanning electron microscopy and scanning probe microscopy. The photocatalytic activity was evaluated by the measurement of the decomposition of methylene blue under UV irradiation. The results showed that the crystalline anatase, anatase/rutile or rutile films can be successfully deposited on unheated substrate and their formation is dependent on the total pressure and the oxygen partial pressure. A schematic phase diagram was constructed. The surface morphology is strongly influenced by the total pressure and the anatase TiO2 films with a more open surface, a higher surface roughness and a larger surface area are formed at higher total pressures. The anatase films with such surface morphology deposited in the reactive sputtering mode exhibit the best photocatalytic activity.
TL;DR: In this article, a mesoporous titania with a surface area over 1200 m2/g-1 was synthesized by primary amine templating, which showed high thermal stability.
Abstract: Mesoporous titania with BET surface area over 1200 m2/g-1 was synthesized by primary amine templating. Dodecyl-, tetradecyl-, and hexadecylamines gave intense XRD patterns with narrow pore-size distributions in which the most probable diameter changed according to the carbon chain length. Thermal treatment was necessary for the formation of a stable structure, which strongly depends on the vapor pressure during the process. No diffraction patterns were observed above 2θ = 10°, suggesting the amorphous nature of the mesoporous titania. UV−vis and XANES spectroscopies demonstrated that the local structure of titanium was mainly 5-coordinated and Oh (6-coordinated) Ti. Chemical vapor deposition (CVD) of titanium isopropoxide followed by its decomposition with water vapor was carried out to improve the thermal stability of template-extracted titania. Although this CVD treatment resulted in a decrease in the BET surface area by 20%, the treated TiO2 showed high thermal stability; surface areas higher than 500 ...
TL;DR: The present study illustrates the feasibility of using the titanium foams as implant materials in bone tissue engineering applications, highlighting their excellent biomechanical properties and bioactivity.
Abstract: Titanium foams fabricated by a new powder metallurgical process have bimodal pore distribution architecture (i.e., macropores and micropores), mimicking natural bone. The mechanical properties of the titanium foam with low relative densities of approximately 0.20-0.30 are close to those of human cancellous bone. Also, mechanical properties of the titanium foams with high relative densities of approximately 0.50-0.65 are close to those of human cortical bone. Furthermore, titanium foams exhibit good ability to form a bonelike apatite layer throughout the foams after pretreatment with a simple thermochemical process and then immersion in a simulated body fluid. The present study illustrates the feasibility of using the titanium foams as implant materials in bone tissue engineering applications, highlighting their excellent biomechanical properties and bioactivity.
TL;DR: In this article, the authors investigated whether oxide properties of titanium implants influenced bone tissue responses after an in vivo implantation time of six weeks, and they concluded that oxide properties, which include oxide thickness, micropore configurations and crystal structures, greatly influence the bone tissue response in the evaluation of removal torque values.
Abstract: The present experimental study was designed to address two issues. The first was to investigate whether oxide properties of titanium implants influenced bone tissue responses after an in vivo implantation time of six weeks. If such a result was found, the second aim was to investigate which oxide properties are involved in such bone tissue responses. Screw-shaped implants with a wide range of oxide properties were prepared by electrochemical oxidation methods, where the oxide thickness varied in the range of 200 nm to 1000 nm. The surface morphology was prepared in two substantially different ways, i.e. barrier and porous oxide film structures. The micropore structure revealed pore sizes of 8 μm in diameter, with a range in opening area from 1.27 μm2 to 2.1 μm2. Porosity ranged from 12.7% to 24.4%. The crystal structures of the titanium oxide were amorphous, anatase and a mixture of anatase and rutile type. The chemical compositions consisted mainly of TiO2. Surface roughness ranged from 0.96 μm to 1.03 μm (Sa). Each group of test samples showed its own, defined status with respect to these various parameters. The oxide properties of turned commercially pure titanium implants were used in the control group, which was characterized by an oxide thickness of 17.4 ± 6.2 nm, amorphous type in crystallinity, TiO2 in chemical composition, and a surface roughness of 0.83 μm (Sa). Bone tissue responses were evaluated by resonance frequency measurements and removal torque tests that were undertaken six weeks after implant insertion in rabbit tibia. Implants that had an oxide thickness of approximately 600, 800 and 1000 nm demonstrated significantly stronger bone responses in the evaluation of removal torque values than did implants that had an oxide thickness of approximately 17 and 200 nm (P < 0.05). However, there were no difference between implants with oxide thicknesses of 17 and 200 nm (P = 0.99). It was concluded that oxide properties of titanium implants, which include oxide thickness, micropore configurations and crystal structures, greatly influence the bone tissue response in the evaluation of removal torque values. However, it is not fully understood whether these oxide properties influence the bone tissue response separately or synergistically.
TL;DR: Computational studies show that the pentaphosphacyclopentadienyl unit, P5, functions as an unusually effective acceptor ligand, and this results in substantial stabilization of 1.
Abstract: Reactions of highly reduced titanium complexes with white phosphorus, P4, at or below 25°C yielded brown to deep red-brown salts of the first entirely inorganic metallocene, [(η5-P5)2Ti]2−(1). Like ferrocene and other carbon-based metallocenes, the structure of1 has parallel and planar five-membered rings symmetrically positioned about the central metal atom. Despite its electron-deficient (16 electron) and formally zerovalent titanium character, salts of1 are highly stable toward heat and air, both in solution and in the solid state. Computational studies show that the pentaphosphacyclopentadienyl unit, P5, functions as an unusually effective acceptor ligand, and this results in substantial stabilization of 1.
TL;DR: In this paper, the effect of titanium as reinforcement and its increasing amounts with the microstructural, physical and tensile properties of magnesium was investigated and the results showed that the presence of titanium reinforcement led to an improvement in yield strength and ductility while the UTS was adversely affected.
TL;DR: In this paper, the crystal phase of TiO2 films was essentially determined by the initial pH value and the Ti concentration of the precursor solutions, which was not dominant in this system.
Abstract: Crystalline titanium dioxide (TiO2) was directly grown on a substrate via heterogeneous nucleation in aqueous solutions with titanyl sulfate at near room temperature. The crystal phase of TiO2 films was essentially determined by the initial pH value and the Ti concentration of the precursor solutions. The rutile and anatase phases were produced in the solutions around their thermodynamic equilibrium conditions between Ti(IV) ionic species and the solid phases. The effect of the deposition rate on the crystal phases was not dominant in this system. On the other hand, the morphology of the TiO2 products was influenced by the reaction rate controlled with the properties of anions as a ligand for titanium cations. Homogeneous rutile and anatase films consisting of highly oriented needlelike crystals were obtained with a relatively slow deposition rate.
TL;DR: In this article, the color variation in zirconium and titanium nitrides was investigated with respect to the atomic ratio between nitrogen and transition metals and with oxygen as the contaminant.
TL;DR: The results indicated that heat-treatment uniformly roughened the titanium surface and increased surface energy, endowed titanium with bioactivity by increasing the amount of surface hydroxyl groups on titanium and its surface energy.
Abstract: Biological properties of titanium implant depend on its surface oxide film. In the present study, the surface oxide films on titanium were characterized and the relationship between the characterization and bioactivity of titanium was studied. The surface oxide films on titanium were obtained by heat-treatment in different oxidation atmospheres, such as air, oxygen and water vapor. The bioactivity of heat-treated titanium plates was investigated by immersion test in a supersaturated calcium phosphate solution. The surface roughness, energy morphology, chemical composition and crystal structure were used to characterize the titanium surfaces. The characterization was performed using profilometer, scanning electronic microscopy, ssesile drop method, X-ray photoelectron spectroscopy, common Bragg X-ray diffraction and sample tilting X-ray diffraction. Percentage of surface hydroxyl groups was determined by X-ray photoelectron spectroscopy analysis for titanium plates and density of surface hydroxyl groups was measured by chemical method for titanium powders. The results indicated that heat-treatment uniformly roughened the titanium surface and increased surface energy. After heat-treatment the surface titanium oxide was predominantly rutile TiO2, and crystal planes in the rutile films preferentially orientated in (1 1 0) plane with the highest density of titanium ions. Heat-treatment increased the amount of surface hydroxyl groups on titanium. The different oxidation atmospheres resulted in different percentages of oxygen species in TiO2, in physisorbed water and acidic hydroxyl groups, and in basic hydroxyl groups on the titanium surfaces. The immersion test in the supersaturated calcium phosphate solution showed that apatite spontaneously formed on to the rutile films. This revealed that rutile could be bioactivated. The analyses for the apatite coatings confirmed that the surface characterization of titanium has strong effect on bioactivity of titanium. The bioactivity of the rutile films on titanium was related not only to their surface basic hydroxyl groups, but also to acidic hydroxyl groups, and surface energy. Heat-treatment endowed titanium with bioactivity by increasing the amount of surface hydroxyl groups on titanium and its surface energy.
TL;DR: In this article, a model that entails substitution of sodium cations by variable valence transition metal cations and the creation of Na+ vacancies in the bulk hydride lattice was proposed.
TL;DR: The method has allowed the preparation of crystalline TiO(2) nanoparticles that are monodispersed in the same way as they are initially produced in the microemulsion, and effects of the fluid properties on the crystallization of nanoparticles are discussed.
Abstract: Titanium dioxide (TiO(2)) nanoparticles were synthesized by controlled hydrolysis of titanium alkoxide in reverse micelles in a hydrocarbon solvent. Upon annealing in situ in the presence of the micelles at temperatures considerably lower than those required for the traditional calcination treatment in the solid state, the TiO(2) nanoparticles became highly crystalline but still maintained the same physical parameters and remained in a stable suspension. Thus, the method has allowed the preparation of crystalline TiO(2) nanoparticles that are monodispersed in the same way as they are initially produced in the microemulsion. Effects of the fluid properties on the crystallization of nanoparticles are discussed.
TL;DR: End-group analysis of polypropylene formed using the phenoxyimine-based titanium catalysts revealed a reversal in the regioselectivity of insertion for this class of catalysts.
Abstract: A highly regioselective secondary enchainment of propylene in a group IV catalyst system is reported. End-group analysis of polypropylene formed using the phenoxyimine-based titanium catalysts revealed a reversal in the regioselectivity of insertion for this class of catalysts. To the best of our knowledge, bis(phenoxyimine)-based titanium complexes are the only known group IV catalysts that insert propylene with exclusive 2,1-regiochemistry. Insertion of propylene into the initiating titanium hydride occurs with high 1,2-regiochemistry. Subsequent insertions into primary titanium alkyls are regiorandom, while insertions into secondary titanium alkyls proceed with high 2,1-regioselectivity. Cyclopolymerization and ethylene/propylene copolymerization strategies are employed to support this proposal.
TL;DR: In this paper, a copper matrix composite reinforced by in situ TiB2 nanoparticle was prepared by reactions of B2O3, carbon and titanium in copper-titanium melt.