Showing papers on "Titanium published in 2010"
TL;DR: It is found that the porous structures produced by the electron beam melting process present a promising rapid manufacturing process for the direct fabrication of customized titanium implants for enabling personalized medicine.
Abstract: Patient specific porous implants for the reconstruction of craniofacial defects have gained importance due to their better performance over their generic counterparts. The recent introduction of electron beam melting (EBM) for the processing of titanium has led to a one step fabrication of porous custom titanium implants with controlled porosity to meet the requirements of the anatomy and functions at the region of implantation. This paper discusses an image based micro-structural analysis and the mechanical characterization of porous Ti6Al4V structures fabricated using the EBM rapid manufacturing process. SEM studies have indicated the complete melting of the powder material with no evidence of poor inter-layer bonding. Micro-CT scan analysis of the samples indicate well formed titanium struts and fully interconnected pores with porosities varying from 49.75%-70.32%. Compression tests of the samples showed effective stiffness values ranging from 0.57(+/-0.05)-2.92(+/-0.17)GPa and compressive strength values of 7.28(+/-0.93)-163.02(+/-11.98)MPa. For nearly the same porosity values of 49.75% and 50.75%, with a variation in only the strut thickness in the sample sets, the compressive stiffness and strength decreased significantly from 2.92 GPa to 0.57 GPa (80.5% reduction) and 163.02 MPa to 7.28 MPa (93.54 % reduction) respectively. The grain density of the fabricated Ti6Al4V structures was found to be 4.423 g/cm(3) equivalent to that of dense Ti6Al4V parts fabricated using conventional methods. In conclusion, from a mechanical strength viewpoint, we have found that the porous structures produced by the electron beam melting process present a promising rapid manufacturing process for the direct fabrication of customized titanium implants for enabling personalized medicine.
659 citations
TL;DR: The effect of extreme grain refinement in the bulk of commercial purity titanium (CP, Grade-2) on bacterial attachment to the mechano-chemically polished surfaces of the material was discussed and it was found that the bacterial strains used in this study as adsorbates showed preference for surfaces of ECAP-processed titanium.
398 citations
TL;DR: In this paper, the photocatalytic activity of pure anatase nanoparticles, of anatase/brookite mixtures, and of pure brookite nanorods has been assessed by hydrogen evolution from aqueous methanol solution as well as by the degradation of dichloroacetic acid (DCA) in an in situ OH− source.
Abstract: High quality brookite TiO2 nanorods have been obtained by the thermal hydrolysis of commercially available aqueous solutions of titanium bis(ammonium lactate) dihydroxide in the presence of high concentrations of urea (≥6.0 M) as an in situ OH− source. Biphasial anatase/brookite mixtures are obtained at lower urea concentrations. The ratios between anatase and brookite can readily be tailored by the control of the urea concentration. The obtained powders have been characterized by X-ray diffraction, Raman spectroscopy, field emission-scanning electron microscopy, high-resolution transmission electron microscopy, UV−vis diffuse reflectance spectra, and nitrogen adsorption. The photocatalytic activity of pure anatase nanoparticles, of anatase/brookite mixtures, and of pure brookite nanorods has been assessed by hydrogen evolution from aqueous methanol solution as well as by the degradation of dichloroacetic acid (DCA) in aqueous solution. The results indicate that the photocatalytic hydrogen evolution activ...
393 citations
TL;DR: In this article, the formations of intrinsic n-type defects, that is, oxygen vacancies and titanium interstitials, in rutile and anatase TiO2 have been compared using GGA+U calculations.
Abstract: The formations of intrinsic n-type defects, that is, oxygen vacancies and titanium interstitials, in rutile and anatase TiO2 have been compared using GGA+U calculations. In both crystal structures, these defects give rise to states in the band gap, corresponding to electrons localized at Ti3+ centers. O vacancy formation in rutile results in two excess electrons occupying 3d orbitals on Ti atoms neighboring the vacancy. Similarly, for anatase, two Ti 3d orbitals are occupied by the excess electrons, with one of these Ti sites neighboring the vacancy, and the second at a next-nearest Ti position. This localization is accompanied by one oxygen moving toward the vacancy site to give a “split vacancy” geometry. A second fully localized solution is also found for anatase, with both occupied Ti sites neighboring the vacancy site. This minimum is 0.05 eV less stable than the split vacancy and is thus expected to be present in experimental samples. A partially delocalized solution corresponding to the split vacan...
366 citations
TL;DR: In this paper, a simple aqueous precipitation method based on a low-cost titanium oxysulfate precursor was used to obtain anatase, rutile, and brookite.
Abstract: Using a simple aqueous precipitation method based on a low-cost titanium oxysulfate precursor, we have prepared three TiO2 polymorphs: anatase, rutile, and brookite. Although the anatase form can be directly obtained from the thermolysis reaction of an oxysulfate solution, the rutile and the brookite have been prepared by the addition of oxalate species. Depending on the concentration, the oxalate anions have been shown to act either as a ligand with the stabilization of a titanium oxalate hydrate, Ti2O3(H2O)2(C2O4)·H2O, or as a chelating agent with the isolation of the rutile phase. The brookite form was obtained by thermal decomposition of the oxalate hydrate at a temperature as low as 300 °C. The resulting solid consisted of nanodomains of TiO2 brookite embedded in large micrometer-size particles and exhibited a high specific surface area of 255 m2/g because of the mesoporosity arising from the removal of water from the oxalate species. This type of morphology is of interest for lithium-ion batteries b...
333 citations
01 Apr 2010
305 citations
TL;DR: Titanium alloy is one of the materials extensively used in the aerospace industry due to its excellent properties of high specific strength and corrosion resistance, but it also presents problems wherein it is an extremely difficult material to machine as discussed by the authors.
Abstract: Titanium alloy (Ti–6Al–4V) is one of the materials extensively used in the aerospace industry due to its excellent properties of high specific strength and corrosion resistance, but it also presents problems wherein it is an extremely difficult material to machine. The cost associated with titanium machining is also high due to lower cutting speeds (
293 citations
TL;DR: Findings indicate that there is no significant penetration of TiO(2) nanoparticles through the intact normal epidermis of minipigs treated with sunscreens containing TiO (2).
282 citations
TL;DR: In this paper, Magneli phase titanium sub-oxides were identified (via x-ray diffraction) in the 1950s as a distinct series of electrically conducting compounds having the general formula TinO2n-1 where 3 < n < 10.
277 citations
TL;DR: Systematic studies have revealed that the TiO(2)@TiO(x)N(y)/TiN-GS nanocomposites with graphene nanosheets covered with the Ti olympus nanospindles on both sides provide a promising solution to the problems of poor electron transport and severe aggregation of TiO (2) nanoparticles by enhancing both electron transport through the conductive matrix and Li-ion accessibility to the active material from the liquid electrolyte.
Abstract: This paper embarks upon three levels of undertaking ranging from nanomaterials synthesis to assembly and functionalization. First, we have prepared size-tunable anatase TiO2 nanospindles via a hydrothermal process by using tubular titanates as self-sacrificing precursors. Second, we have densely dispersed the TiO2 nanospindles onto functional graphene oxides (GO) via a spontaneous self-assembly process. After annealing of the TiO2/GO hybrid nanocomposite in an NH3 gas flow, the TiO2 surface was effectively nitridated and the GO was reduced to graphene sheets (GS) in order to further fortify the electronic functionality of the nanocomposite. Third, the anatase@oxynitride/titanium nitride-GS (TiO2@TiOxNy/TiN−GS) hybrid nanocomposite was studied as an anode material for lithium-ion batteries (LIBs), showing excellent rate capability and cycling performance compared to the pure TiO2 nanospindles. Our systematic studies have revealed that the TiO2@TiOxNy/TiN−GS nanocomposites with graphene nanosheets covered w...
263 citations
TL;DR: Gold nanoparticle loading has led to a drastic enhancement of TiO(2)-photocatalized generation of H(2)O( 2) from O(2), with a unique inversed volcano-type relation between the activity and Au particle size.
Abstract: Gold nanoparticle loading has led to a drastic enhancement of TiO2-photocatalized generation of H2O2 from O2 with a unique inversed volcano-type relation between the activity and Au particle size.
TL;DR: In this article, a novel iron titanate catalyst prepared by conventional co-precipitation method showed excellent activity, N-2 selectivity and H2O/SO2 durability in the selective catalytic reduction (SCR) of NO with NH3.
Abstract: A novel iron titanate catalyst prepared by conventional co-precipitation method showed excellent activity, N-2 selectivity and H2O/SO2 durability in the selective catalytic reduction (SCR) of NO with NH3. The influence of precursors and preparation methods on the catalyst structure and activity was comprehensively investigated. Iron titanate catalyst prepared using titanium sulfate as Ti precursor was favorable for the high activity and selectivity, comparing with that using titanium tetrachloride as precursor and Fe2O3/TiO2 loaded type catalyst. Especially, the best iron titanate catalyst showed good activity in a temperature window of 200-350 degrees C with the NOx conversion above 90% in the absence of H2O, which was 50-150 degrees C lower than those of other known Fe-based catalysts. Iron titanate crystallite with specific Fe-O-Ti structure was found to be the main active phase. The interaction between iron and titanium species in atomic scale led to an enhancement of oxidative ability of Fe3+, which was beneficial to the SCR reaction. (C) 2010 Elsevier B.V. All rights reserved.
TL;DR: The development of high-porous titanium material shows high potential to be modern material for creating a 3D structure for bone regeneration and implant fixation and was low resistant to corrosion.
Abstract: For many years, the solid metals and their alloys have been widely used for fabrication of the implants replacing hard human tissues or their functions. To improve fixation of solid implants to the surrounding bone tissues, the materials with porous structures have been introduced. By tissue ingrowing into a porous structure of metallic implant, the bonding between the implant and the bone has been obtained. Substantial pore interconnectivity, in metallic implants, allows extensive body fluid transport through the porous implant. This can provoke bone tissue ingrowth, consequently, leading to the development of highly porous metallic implants, which could be used as scaffolds in bone tissue engineering. The goal of this study was to develop and then investigate properties of highly porous titanium structures received from powder metallurgy process. The properties of porous titanium samples, such as microstructure, porosity, Young's modulus, strength, together with permeability and corrosion resistance were investigated. Porous titanium scaffolds with nonhomogeneous distribution of interconnected pores with pore size in the range up to 600 μm in diameter and a total porosity in the range up to 75% were developed. The relatively high permeability was observed for samples with highest values of porosity. Comparing to cast titanium, the porous titanium was low resistant to corrosion. The mechanical parameters of the investigated samples were similar to those for cancellous bone. The development of high-porous titanium material shows high potential to be modern material for creating a 3D structure for bone regeneration and implant fixation.
TL;DR: In this paper, the cytotoxicity of titanium and titanium alloying elements in both forms of powder and bulk, using osteoblast-like SaOS(2) cells was assessed.
Abstract: It is commonly accepted that titanium and the titanium alloying elements of tantalum, niobium, zirconium, molybdenum, tin, and silicon are biocompatible. However, our research in the development of new titanium alloys for biomedical applications indicated that some titanium alloys containing molybdenum, niobium, and silicon produced by powder metallurgy show a certain degree of cytotoxicity. We hypothesized that the cytotoxicity is linked to the ion release from the metals. To prove this hypothesis, we assessed the cytotoxicity of titanium and titanium alloying elements in both forms of powder and bulk, using osteoblast-like SaOS(2) cells. Results indicated that the metal powders of titanium, niobium, molybdenum, and silicon are cytotoxic, and the bulk metals of silicon and molybdenum also showed cytotoxicity. Meanwhile, we established that the safe ion concentrations (below which the ion concentration is non-toxic) are 8.5, 15.5, 172.0, and 37,000.0 microg/L for molybdenum, titanium, niobium, and silicon, respectively.
TL;DR: In this article, the impact of rounded cutting edges on active force components including ploughing forces and tool face friction is analyzed in orthogonal turning tests on Ti-6Al-4V with different cutting edge radii and changing cutting speeds and feeds.
TL;DR: In this article, the authors show that the temperature of calcination is critical in determining the structure and crystallinity of the titania, and that the appropriate annealing temperature allows the structure to be made up of defined proportions of anatase and rutile with a reduced contamination of species from the electrolyte or organic solvents.
Abstract: Titanium oxide (TiO2) nanotubes prepared by electrolytic anodisation of a titanium electrode have been systematically heat treated to control the conversion of the as-prepared amorphous structure to nanocrystalline anatase and rutile. Raman spectroscopy revealed that the temperature of calcination is critical in determining the structure and crystallinity of the titania. X-ray Photoelectron Spectroscopy analysis shows the as-prepared film to consist mainly of oxide, although a small amount of fluoride contamination remains from the electrolyte. Organic components from post-anodising cleaning treatments were also present. Fluorine ions are gradually ejected from the anodic layer during annealing and the fluorine concentration is negligible in samples that are heat treated above 400 °C. Choosing the appropriate annealing temperature allows the structure to be made up of defined proportions of anatase and rutile with a reduced contamination of species from the electrolyte or organic solvents. Copyright © 2010 John Wiley & Sons, Ltd.
TL;DR: Investigation of the dynamic evolution of the Ti thin film topographic parameters indicated that three commonly used parameters, R(a), R(q), and R(max), were insufficient to effectively characterize the nanoscale rough/smooth surfaces.
Abstract: Two human pathogenic bacteria, Staphylococcus aureus CIP 68.5 and Pseudomonas aeruginosa ATCC 9025, were adsorbed onto surfaces containing Ti thin films of varying thickness to determine the extent to which nanoscale surface roughness influences the extent of bacterial attachment. A magnetron sputter thin film system was used to deposit titanium films with thicknesses of 3, 12, and 150 nm on glass substrata with corresponding surface roughness parameters of Rq 1.6, 1.2, and 0.7 nm (on a 4 μm × 4 μm scanning area). The chemical composition, wettability, and surface architecture of titanium thin films were characterized using X-ray photoelectron spectroscopy, contact angle measurements, atomic force microscopy, three-dimensional interactive visualization, and statistical approximation of the topographic profiles. Investigation of the dynamic evolution of the Ti thin film topographic parameters indicated that three commonly used parameters, Ra, Rq, and Rmax, were insufficient to effectively characterize the ...
TL;DR: In this paper, two types of the charge injection mechanisms may be distinguished, in the first, charge is transferred from the excited state of the sensitizer molecule to the conduction or valence band while the second mechanism involves a direct molecule-to-band charge transfer (MBCT).
TL;DR: In this article, a set of eight concretes and plasters is enriched with TiO2 photocatalyst by dip-coating and/or sol-gel methods.
TL;DR: An electrostatic property of UV-treated titanium surfaces playing a regulatory role in determining their bioactivity is identified, superseding the effect of the hydrophilic nature of these surfaces.
TL;DR: The data suggest that silver nanoparticle-modified titanium is a promising material with an antibacterial property that may be used as an implantable biomaterial.
Abstract: Microbial colonization on implanted devices and biofilm formation is a recurrent complication in implant surgery and may result in loss of implants. The aim of this study was to deposit silver nanoparticles on a titanium surface to obtain antibacterial properties. In the present study, we prepared a silver nanoparticle-modified titanium (Ti-nAg) surface using silanization method. The morphology and chemical components of the Ti-nAg surface were characterized by scanning electron microscopy (SEM) equipped with energy-dispersive spectroscopy (EDS). Two species of bacteria, Staphylococcus aureus and Escherichia coli, were utilized to test the antibacterial effect of the Ti-nAg treated surface. The SEM examination revealed that a small quantity of silver nanoparticles was sparsely deposited on the titanium surface. The diameter of these nanoparticles ranged from ten to several hundred nm. EDS analyses revealed that there was 4.26% of Ag present on the surface. After a 24-hour incubation, 94% of Staphylococcus aureus and over 95% of Escherichia coli had been killed on the Ti-nAg surface, and the SEM examination of anti-adhesive efficacy test showed that there were less bacteria attached to Ti-nAg surface than to a control surface of untreated Titanium. These data suggest that silver nanoparticle-modified titanium is a promising material with an antibacterial property that may be used as an implantable biomaterial.
TL;DR: Au nanoparticle surface plasmon resonance-induced photocatalytic chemoselective oxidation of alcohols to carbonyl compounds and the heterosupramolecular system consisting of Au nanoparticle-loaded titanium(IV) dioxide and surfactant molecular assembly dramatically enhances the reaction.
Abstract: Au nanoparticle surface plasmon resonance-induced photocatalytic chemoselective oxidation of alcohols to carbonyl compounds has been investigated. The heterosupramolecular system consisting of Au nanoparticle-loaded titanium(IV) dioxide and surfactant molecular assembly dramatically enhances the reaction. This system should evolve the photocatalyst to intelligent nanodevices.
TL;DR: Incubated in a simulated body fluid, bone-like apatite was completely formed on the surface of E20 after 2 days, thus evidencing preferable bioactivity and indicating superior mechanical properties without harmful alloying elements.
15 Oct 2010
TL;DR: A simple and efficient method is described to modify Ti/TiO(2) surfaces with citrate-capped AgNPs, which exhibits a good resistance to colonization by Pseudomonas aeruginosa, a model system for biofilm formation.
Abstract: Titanium is a corrosion-resistant and biocompatible material widely used in medical and dental implants. Titanium surfaces, however, are prone to bacterial colonization that could lead to infection, inflammation, and finally to implant failure. Silver nanoparticles (AgNPs) have demonstrated an excellent performance as biocides, and thus their integration to titanium surfaces is an attractive strategy to decrease the risk of implant failure. In this work a simple and efficient method is described to modify Ti/TiO2 surfaces with citrate-capped AgNPs. These nanoparticles spontaneously adsorb on Ti/TiO2, forming nanometer-sized aggregates consisting of individual AgNPs that homogeneously cover the surface. The modified AgNP–Ti/TiO2 surface exhibits a good resistance to colonization by Pseudomonas aeruginosa, a model system for biofilm formation.
TL;DR: The thermoelectric properties of Magneli phase titanium oxides have been investigated in this paper, paying special attention to how the performance can be altered by changing the microstructure.
Abstract: The thermoelectric properties of Magneli phase titanium oxides TinO2n−1 (n=2,3,…) have been investigated, paying special attention to how the thermoelectric performance can be altered by changing the microstructure. Dense polycrystalline specimens with nominal composition of TiO2−x (x=0.05, 0.10, 0.15, and 0.20) prepared by conventional hot-pressing are all identified to be one of the Magneli phases, in which crystallographic shear planes are regularly introduced according to the oxygen deficiency. Electrical conduction is n-type for all specimens and the carrier concentration increases with the increase in the oxygen deficiency. The values of lattice thermal conductivity, on the other hand, decrease with the increase in the oxygen deficiency, which can be attributed to phonon scattering at the crystallographic shear plane. The largest value of thermoelectric figure of merit Z, 1.6×10−4 K−1 was obtained at 773 K for the hot-pressed specimen of TiO1.90.
01 May 2010
TL;DR: In this paper, surface degradation of light alloys: Corrosion behaviour of magnesium alloys and protection techniques Wear properties of aluminium-based alloys Tribological properties of titanium alloys.
Abstract: Part 1 Surface degradation of light alloys: Corrosion behaviour of magnesium alloys and protection techniques Wear properties of aluminium-based alloys Tribological properties of titanium alloys. Part 2 Surface engineering technologies for light alloys: Anodising of light alloys Plasma electrolytic oxidation treatment of aluminium and titanium alloys Plasma electrolytic oxidation treatments of magnesium alloys Thermal spraying of light alloys Cold spraying of light alloys Physical vapour deposition of magnesium alloys Plasma assisted surface treatment of aluminium alloys to combat wear Plasma immersion ion implantation (PIII) of light alloys Laser surface modification of titanium alloys Laser surface modification of aluminium and magnesium alloys Ceramic conversion treatment of titanium-based materials Duplex surface treatments of light alloys. Part 3 Applications for surface engineered light alloys: Surface engineered light alloys for sports equipment Surface engineered titanium alloys for biomedical devices Plasma electrolytic oxidation and anodised aluminium alloys for spacecraft applications.
TL;DR: The results indicate that corrosion occurred readily in stainless steel and variations in breakdown potential of nickel titanium alloy wires differed across vendors' wires.
Abstract: Orthodontic wires containing nickel have been implicated in allergic reactions. The potential for orthodontic wires to cause allergic reactions is related to the pattern and mode of corrosion with subsequent release of metal ions, such as nickel, into the oral cavity. The purpose of this study was to determine if there is a significant difference in the corrosive potential of stainless steel, nickel titanium, nitride-coated nickel titanium, epoxy-coated nickel titanium, and titanium orthodontic wires. At least two specimens of each wire were subjected to potentiostatic anodic dissolution in 0.9% NaCl solution with neutral pH at room temperature. Using a Wenking MP 95 potentiostat and an electrochemical corrosion cell, the breakdown potential of each wire was determined. Photographs were taken of the wire speci mens using a scanning electron microscope, and surface changes were qualitatively evaluated. The breakdown potentials of stainless steel, two nickel titanium wires, nitride-coated nickel titanium, epoxy-coated nickel titanium, and titanium were 400 mV, 300 mV, 750 mV, 300 mV, 1800 mV, and >2000 mV, respectively. SEM photographs revealed that some nickel titanium and stainless steel wires were susceptible to pitting and localized corrosion. The results indicate that corrosion occurred readily in stainless steel. Variability in breakdown potential of nickel titanium alloy wires differed across vendors' wires. The nitride coating did not affect the corrosion of the alloy, but epoxy coating decreased corrosion. Titanium wires and epoxy-coated nickel titanium wires exhibited the least corrosive potential. For patients allergic to nickel, the use of titanium or epoxy-coated wires during orthodontic treatment is recommended.
TL;DR: It was concluded that EPD was an effective and efficient technique to prepare chitosan/gelatin coatings on the titanium surface and that CS/G coatings with higher gelatin content were promising candidates for further loading of functional agents.
TL;DR: In this article, a one-step synthesis method was proposed for the first time using hollow sphere structures of Titanium cations as structure-directing agents in the synthesis process, and the assembly of the hollow spheres was carried out at the beginning of the process.
Abstract: Titanium containing γ-MnO 2 octahedral molecular sieves having hollow sphere structures are successfully prepared for the first time using a one-step synthesis method. Titanium cations are used as structure-directing agents in the synthesis process. The assembly of the hollow spheres is carried out at the beginning of the process. Various techniques including XRD, N 2 adsorption, SEM, EDX, RAMAN, TEM, XPS, and TGA are employed for the materials characterization. Ti is incorporated into the MnO 2 framework in isolated sites, and TiO 2 phases (anatase and rutile) are not observed. When introduced in medium-sized lithium-air batteries, the materials give very high specific capacity (up to 2.3 A h g ―1 ). These materials are also catalytically tested in the oxidation of toluene with molecular oxygen at atmospheric pressure, showing significant oxidative catalytic activities in this difficult chemical reaction.
Journal Article•
TL;DR: The conventional cold compaction-and-sinter powder metallurgy (PM) approach offers an efficient solution to the near-net shape or preform fabrication of titanium and its alloys for cost reduction and improved chemical homogeneity and refined microstructures as discussed by the authors.
Abstract: The conventional cold-compaction-and-sinter powder metallurgy (PM) approach offers an efficient solution to the near-net shape or preform fabrication of titanium and its alloys for cost reduction and improved chemical homogeneity and refined microstructures. The methods for compacting titanium powder are similar to those used for other ductile powders. The high-purity titanium in the most ductile state is similar to annealed copper in terms of elastic modulus, hardness, elongation, and ultimate tensile strength. The properties of titanium are sensitive to the impurity level, in particular to nitrogen, oxygen, carbon, and iron. Hardness is a convenient measure of the quality of a titanium sponge product. Dilatometric studies of the sintering of titanium-nickel alloys show similar observations and confirm that oxide films on titanium powder surfaces do not need to be reduced by the atmosphere or disrupted by a chemical additive.