Structure Of Titanium Research Articles

Coarse-grained and ultrafine-grained titanium high-temperature creep

The publication describes the study of durability in tensile creep of VT1-0 commercial titanium in its two states-coarse-grained and ultrafine-grained. It is shown that the best temperature for log-term testing is 350°C. At this temperature, the ultrafine-grained titanium structure remains stable both during free annealing and durability testing. The obtained data enable retrieving the difference in fracture initiation energies for titanium in its coarse-grained and ultrafine-grained states.

Uranium detection by 3D-printed titanium structures: Towards decentralized nuclear forensic applications

Uranium can cause significant pollution of the ecosystem as well as it can have immense hazardous effect on human health due to its chemical and radioactive toxicity. Uranyl ions (UO22+) are considered as the most common and stable ionic form of uranium and additionally, UO22+ can spread easily through the environment owing to their high solubility and mobility in water. Hence, the development of appropriate sensors for UO22+ detection is very important for in time revelation of potentially dangerous sources of water or soil contamination. 3D-printing technology is now recognized as effective tool for designing and manufacturing objects of different sizes and shapes. Thus, it might also offer customized solution for design of electrodes to be applied in environmental sensing. In this work, 3D-printed titanium electrode was evaluated toward uranyl ions determination in aqueous samples. This electrode revealed good liner response within the wide concentration range, high stability as well as reproducibility. Good analytical performance of 3D-Ti electrode was further confirmed by low detection limit of 24.5 µg L−1 that also meets the requirement of Maximum Contaminant Level (MCL) for uranium in drinking water (30 µg L−1). The performance of 3D-Ti electrode was also evaluated for its capability of UO22+ determination in spiked tap and mineral water. All results presented in this work, encourage and highlight the exploitation of 3D-printing technology for electrochemical sensing applications since it has strong potential for environmental, nuclear forensic and security applications.

Molecular dynamics simulation of the crystal structure evolution of titanium under different Tdamp values and heating/cooling rates

Molecular dynamics (MD) was used to study the evolution of crystal structure of titanium (Ti) under different temperature damping parameter (Tdamp) values and heating/cooling rates. In the heating process, when the temperature reaches the melting point, the temperature of the system with lager Tdamp value decreases with the increase of average atomic potential energy. However, an increase in heating rate will cause the melting point to rise slightly. In the cooling process, a larger Tdamp value or a lower cooling rate is more conducive to the crystallization of Ti, which corresponding to the higher crystallization temperature.

Mechano-Biological Computer Model of Scaffold-Supported Bone Regeneration: Effect of Bone Graft and Scaffold Structure on Large Bone Defect Tissue Patterning

Large segmental bone defects represent a clinical challenge for which current treatment procedures have many drawbacks. 3D-printed scaffolds may help to support healing, but their design process relies mainly on trial and error due to a lack of understanding of which scaffold features support bone regeneration. The aim of this study was to investigate whether existing mechano-biological rules of bone regeneration can also explain scaffold-supported bone defect healing. In addition, we examined the distinct roles of bone grafting and scaffold structure on the regeneration process. To that end, scaffold-surface guided migration and tissue deposition as well as bone graft stimulatory effects were included in an in silico model and predictions were compared to in vivo data. We found graft osteoconductive properties and scaffold-surface guided extracellular matrix deposition to be essential features driving bone defect filling in a 3D-printed honeycomb titanium structure. This knowledge paves the way for the design of more effective 3D scaffold structures and their pre-clinical optimization, prior to their application in scaffold-based bone defect regeneration.

Physico-mechanical properties of VT6 titanium alloy after combined treatment

One of the directions in the technology is the use of thermal plasma for the production of new materials, as well as the modification of the surface of materials based on a titanium alloy using the action of a plasma jet. The use of pulsed high-speed jets today is one of the promising methods for producing new composite, high-alloy materials on the surface of products from structural materials. An analysis of the results shows that the most optimal is surface modification by high-intensity ion-beam treatment after plasma treatment with microfusion. This work was carried out as part of the state task of the Ministry of Science and Higher Education of the Russian Federation «The influence of magnetic fields and ion implantation on the structure, chemical composition and properties of titanium, aluminum alloys and elementary semiconductors».

Investigation of the effect of the treatment of the surface of VT6 alloy on the penetration depth of implantable ions

The article presents studies on the combined treatment of VT6 titanium alloy, including preimplantation treatment of the titanium alloy surface with a laser or plasma and subsequent modification with highly efficient energy flows using a copper and iron cathode. The beneficial effect of preliminary surface laser and plasma treatments of VT6 alloy parts as an operation of preparing the surface for implantation on the mechanical and tribological properties, as well as the penetration depth of the implanted ions in the surface of the VT6 titanium alloy, is shown. This work was carried out as part of the state task of the Ministry of Science and Higher Education of the Russian Federation «The influence of magnetic fields and ion implantation on the structure, chemical composition and properties of titanium, aluminum alloys and elementary semiconductors».

Investigation of the effect of ion implantation on the structure of the surface layer of VT20 titanium alloy

The effect of ion implantation of VT20 titanium alloys on their structural and substructural characteristics is studied. A significant change in structural characteristics has been established, which contributes to an increase in the strength properties of alloys with satisfactory ductility and heat resistance. This work was carried out as part of the state task of the Ministry of Science and Higher Education of the Russian Federation «The influence of magnetic fields and ion implantation on the structure, chemical composition and properties of titanium, aluminum alloys and elementary semiconductors».

Additively manufactured mesh-type titanium structures for cranial implants: E-PBF vs. L-PBF

A patient-specific titanium-reinforced calcium phosphate (CaP–Ti) cranial implant has recently shown promising clinical results. Currently, its mesh-type titanium structure is additively manufactured using laser beam powder bed fusion (L-PBF). Nevertheless, an electron-beam (E-PBF) process could potentially be more time efficient. This study aimed to compare the geometrical accuracy and mechanical response of thin titanium structures manufactured by L-PBF (HIPed) and E-PBF (as-printed). Tensile test (ø = 1.2 mm) and implant specimens were manufactured. Measurements by μCT revealed a deviation in cross-sectional area as compared to the designed geometry: 13–35% for E-PBF and below 2% for L-PBF. A superior mechanical strength was obtained for the L-PBF specimens, both in the tensile test and the implant compression tests. The global peak load in the implant test was 457 ± 9 N and 846 ± 40 N for E-PBF and L-PBF, respectively. Numerical simulations demonstrated that geometrical deviation was the main factor in implant performance and enabled quantification of this effect: 34–39% reduction in initial peak force based on geometry, and only 11–16% reduction based on the material input. In summary, the study reveals an uncertainty in accuracy when structures of sizes relevant to mesh-type cranial implants are printed by the E-PBF method.

The effect of laser irradiation of the surface of VT6 titanium alloy on its microstructure, roughness and friction coefficient

The article discusses the technology of laser processing of VT6 titanium alloy as a technological operation to improve properties and structure. A promising direction for reducing roughness during laser hardening with reflow can be the development of a process using additives that reduce the surface tension of the melt and increase the wettability of the surface. It was revealed that phase hardening and martensitic transformation β → α are the causes of hardening of titanium during laser processing. This is confirmed by a change in the width of the x-ray lines. It was found that during laser processing with a speed of 3.7 mm/s and higher, a fine-grained structure is achieved.The results show that, at a sufficiently high cooling rate of the substrate, the grain sizes remain practically unchanged. Russian Federation “The influence of magnetic fields and ion implantation on the electrical structure and properties of titanium, aluminum alloys and elementary semiconductors”

Evaluation of annealed titanium oxide nanotubes on titanium: From surface characterization to in vivo assays.

The entire route from anodic oxidation and surface characterization, including in vitro experiments and finally in vivo osseointegration assays were performed with the aim to evaluate nanotubular and crystalline annealed titanium oxides as a suitable surface for grade 2 titanium permanent implants. Polished titanium (T0) was compared with anodized surfaces obtained in acidic media with fluoride, leading to an ordered nanotubular structure of titanium oxide on the metal surface, characterized by tube diameter of 89 ± 24 nm (Tnts). Samples were thermally treated in air (TntsTT) to increase the anatase crystalline phase on nanotubes, with minor alteration of the structure. Corrosion tests were performed to evaluate the electrochemical response after 1, 14, and 28 days of immersion in simulated body fluid. Based on the in vitro results, heat-treated titanium nanotubes (TntsTT) were selected as a promissory candidate to continue with the osseointegration in vivo assays. The in vivo results showed no major improvement in the osseointegration process when compared with untreated Ti after 30 days of implantation and there also was a lower increase in the development of new osseous tissue.

Investigation on preparation porous titanium through calciothermic reduction of porous TiO precursors

A route is present for preparing porous titanium scaffolds with open and interconnected pore morphology through calcium thermal in-situ reduction of TiO precursor. Titanium and dioxide titanium powders, with ammonium carbonate as the space holder, were used to prepare porous precursor whose main phase is TiO by a sintering process. Then calcium vapor was conduced to reduce the precursor and CaO was removed by leaching to obtain porous titanium structures. The morphology, pore structure, phase analysis of porous titanium precursor and porous titanium scaffolds were investigated by means of XRD, SEM and EDS. The porosity was observed by Archimedes method. By this route, the porous titanium with multi-gradient pore sizes ranging from a few microns to several hundred microns was formed. The porous titanium is of multi-gradient pore size distribution of 100 μm bigger, 10 μm∼100 μm and 10 μm smaller. The micro-pores on the pore walls increases connectivity between the macro-pores throughout the porous titanium interior. The porous titanium obtained by this method has a porosity of 50–65% and a titanium content more than 99%.

Improvement in the chemical structure and biological activity of surface titanium after exposure to UVC light.

Ultraviolet (UV) irradiation has been proposed as a method to reverse the aging process of titanium. However, the intensity, exposure time and wavelength that provide the best results have not yet been determined. The objective of this study was to evaluate the effects of photocatalysis by ultraviolet C light on the time-dependent aging of titanium and to analyze the irradiated titanium for changes in structure and in vitro biological activity, with regard to different exposure times. A titanium photofunctionalization device was developed with characteristics different from those on the market. The sample was composed of titanium disks irradiated for different times of exposure to ultraviolet C light (0, 15, 30 and 60min). The disks were tested for surface wettability (water contact angle), topography (scanning electron microscopy-SEM) and chemical composition (X-ray photoelectron spectroscopy), and effects on cell adhesion (cell culture and SEM) and cell viability by sulforhodamine B (SRB). Ultraviolet C treatment caused changes in titanium surface characteristics, such as increased wettability and removal of hydrocarbons from the surface after 15min of exposure in the chamber developed. The biological characteristics of the material also appear to have changed, with improved cell adhesion and viability. Photofunctionalization of titanium proved to be effective for the treatment of aged surfaces, with significant modifications in the surface chemical structure and biological activity of the material.

Effect of Synthesis Conditions of Nitrogen and Platinum Co-Doped Titania Films on the Photocatalytic Performance under Simulated Solar Light

Platinum and nitrogen co-doped titania films of different surface morphologies obtained via a sol-gel process have been tested for tetracycline hydrochloride photocatalytic decomposition under simulated solar light. Titania crystallization to anatase is shown by XRD for all films. A shift of the bandgap edge toward the visible region in absorption spectra and, consequently, a narrowing of the bandgap is observed for some films doped with nitrogen and/or exposed to UV pretreatment. The surface peculiarities of the samples are presented by an SEM and TEM investigation. The surface saturation by Pt and N with a homogeneous distribution of Pt ions on the surface as well as bulk as established by XPS and EDS data can be achieved with a certain synthesis procedure. The influence of the platinum content and of the pretreatment procedure on the state and atomic surface concentration of incorporated nitrogen and platinum is studied by XPS analysis: substitutional and interstitial nitrogen, non-metal containing fragments, Pt0, Pt2+ and Pt4+ ions. The photocatalytic activity of the films is ruled by the presence of Pt2+ ions and N rather than Pt0. The formation of the polycrystalline titania structure and Pt0 nanoparticles (NPs) is confirmed by TEM and electron diffraction images. The mechanism of primary photocatalytic processes is proposed.

Determination of the effect of surface treatment on the physicomechanical properties of a titanium alloy

The article presents studies of the effect of ion implantation on the physicomechanical properties of VT6 titanium alloy. The positive effect of ion implantation on the wear resistance and mechanical properties of a titanium alloy is shown.This work was carried out as part of the state task of the Ministry of Science and Higher Education of the Russian Federation “The influence of magnetic fields and ion implantation on the structure, chemical composition and properties of titanium, aluminum alloys and elementary semiconductors”.

63. Three-dimensional printing of titanium without bone graft outperforms PEEK + autologous iliac crest bone graft in sheep interbody fusion model

BACKGROUND CONTEXT There have been significant advancements in three-dimensional titanium printing and implant surface technology. Interbody implants using three-dimensional printed titanium (3D-Ti) and surface technology mimic trabecular bone structure, roughness/porosity, and modulus of elasticity. In addition to providing biomechanical support and scaffolding, interbody implants may have osteoinductive properties similar to bone graft by inciting cellular response and resulting in enhanced fusion. However, the actual ability of these structural improvements to affect the in vivo fusion cascade has not been clearly defined. PURPOSE To evaluate fusion of 3D-Ti without bone graft compare to PEEK and autologous iliac crest bone graft (ICBG) in a sheep interbody model. STUDY DESIGN/SETTING Randomized in vivo sheep interbody fusion animal trial. PATIENT SAMPLE Not applicable. OUTCOME MEASURES Fusion as assessed by histology, microCT, and traditional CT. METHODS Eight PEEK and eight 3D-Ti implants were randomized to anterior lumbar interbody fusions at L2-3 or L4-5 in a sheep model. The PEEK cages were implanted with autologous ICBG. CT scans were performed at 4 weeks. CT, microCT and histology were performed at sacrifice (8 weeks). The robustness of fusion was graded A-D, where A is no fusion, B is fusion spot-welding to the cage, C is fusion through the cage, and D is fusion outside of the cage. RESULTS At both 4 and 8 weeks, there was no CT evidence of fusion (type A) in PEEK + ICBG implants (0%). Histologic analysis at sacrifice revealed substantial osteolysis and cellular delamination surrounding the PEEK cage with unincorporated/floating ICBG fragments. At 4 weeks in the 3D-Ti group without graft, there were 6/8 (75%) type B fusions and 2/8 (25%) robust fusions (type D). On CT and microCT at 8 weeks, the entire 3D-Ti group (100%) showed evidence of through and outside of the cage (type D). Histologic analysis showed extensive lamellar and mature bone formation on the trabecular structure of the titanium. CONCLUSIONS In an in vivo sheep interbody fusion model, implants created with 3D-Ti and surface technology without bone graft outperform PEEK + autologous ICBG with regard to radiographic and histologic fusion. The three-dimensional titanium technology with biomechanically similar characteristics to trabecular bone allows for more rapid, robust fusion in an animal model and may minimize the need for bone grafting and osteoinductive compounds. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Titanium Scaffolds by Direct Ink Writing: Fabrication and Functionalization to Guide Osteoblast Behavior

Titanium (Ti) and Ti alloys have been used for decades for bone prostheses due to its mechanical reliability and good biocompatibility. However, the high stiffness of Ti implants and the lack of bioactivity are pending issues that should be improved to minimize implant failure. The stress shielding effect, a result of the stiffness mismatch between titanium and bone, can be reduced by introducing a tailored structural porosity in the implant. In this work, porous titanium structures were produced by direct ink writing (DIW), using a new Ti ink formulation containing a thermosensitive hydrogel. A thermal treatment was optimized to ensure the complete elimination of the binder before the sintering process, in order to avoid contamination of the titanium structures. The samples were sintered in argon atmosphere at 1200 °C, 1300 °C or 1400 °C, resulting in total porosities ranging between 72.3% and 77.7%. A correlation was found between the total porosity and the elastic modulus of the scaffolds. The stiffness and yield strength were similar to those of cancellous bone. The functionalization of the scaffold surface with a cell adhesion fibronectin recombinant fragment resulted in enhanced adhesion and spreading of osteoblastic-like cells, together with increased alkaline phosphatase expression and mineralization.

Colossal dielectric properties in (TaxSm1-x)0.04Ti0·96O2

In this study, (TaxSm1-x)0.04Ti0·96O2 (x = 0, 0.1, 0.4, 0.5, 0.6, 1.0; TSTO) were prepared via a standard solid state reaction method. The ceramics with x = 0.5 show the tetragonal rutile titanium dioxide structure, while ceramics with other components present the impurity phase. Notably, compared with x = 0.5 sample, the co-doped ceramics with more Sm3+ or Ta5+ show higher dielectric constant and lower dielectric loss at room temperature, which could be attributed to the formation of grain-boundary segregation. Moreover, the optimum ceramic, (Ta0.1Sm0.9)0.04Ti0·96O2, has the dielectric constant of 1.8 × 105 with relative low dielectric loss and of 0.03 at room temperature and 1 kHz. The excessive doping of Ta5+ or Sm3+ can both improve the dielectric properties, which has developed a new idea for the research of giant dielectric ceramics. The colossal dielectric properties could be explained by the internal barrier layer capacitance (IBLC) model.

Structure and atomic transport of liquid titanium from a pair potential model

We report structural and atomic transport properties of liquid Ti, which are poorly understood at high temperatures. The studies were performed using molecular dynamics (MD) simulation based on a potential model that accounts for the role of $d$ electrons. The interactions between ions are described by a pair potential built within the pseudopotential formalism obtained by an inverse scattering approach that consists of a repulsive core and long-range Friedel oscillations. The parameters determining the $s$- and $d$- electron contributions to the potential are deduced from the knowledge of liquid structure and diffusion coefficient at the melting temperature. The clear connection between local order and atomic transport in liquids emerges from the molecular dynamics simulation. The calculated pair correlation function and structure factor show very good agreement with recently available ab-initio molecular dynamics (AIMD) and experimental results, respectively. By comparing the temperature dependence of diffusion coefficient and viscosity, the effective pair potential based on the pseudopotential method provides a significantly important portion of the high temperature properties of liquid Ti and strongly validates the accuracy of the method. The activation energy of the liquid metals is obtained by fitting the Arrhenius formula. The approach presented herein gives a broader and deeper insight into the transition metal liquid state.

Biological Cell Investigation of Structured Nitinol Surfaces for the Functionalization of Implants.

Expandable implants including shape memory alloy (SMA) elements have great potential to minimize the risk of implant loosening and to increase the primary stability of bone anchoring. Surface structuring of such elements may further improve these properties and support osteointegration and bone healing. In this given study, SMA sheets were processed by deploying additive and removal manufacturing technologies for 3D-printed surgical implants. The additive technology was realized by applying a new laser beam melting technology to print titanium structures on the SMA sheets. The removal step was realized as a standard process with an ultrashort-pulse laser. The morphology, metabolic activity, and mineralization patterns of human bone marrow stromal cells were examined to evaluate the biocompatibility of the new surface structures. It was shown that both surface structures support cell adhesion and the formation of a cytoskeleton. The examination of the metabolic activity of the marrow stromal cells on the samples showed that the number of cells on the laser-structured samples was lower when compared to the 3D-printed ones. The calcium phosphate accumulation, which was used to examine the mineralization of marrow stromal cells, was higher in the laser-structured samples than in the 3D-printed ones. These results indicate that the additive- and laser-structured SAM sheets seem biocompatible and that the macrostructure surface and manufacturing technology may have positive influences on the behavior of the bone formation. The use of the new additive technique and the resulting macrostructures seems to be a promising approach to combine increased anchorage stability with simultaneously enhanced osteointegration.

Phonon structure of titanium under shear deformation along {101¯2} twinning mode

We investigated phonon behavior of hexagonal close packed titanium under homogeneous shear deformation corresponding to the $\{10\bar{1}2\}$ twinning mode using first-principles calculation and phonon calculation. By this deformation, we found that a phonon mode located at a point on Brillouin zone boundary is drastically soften increasing the shear and finally it triggers a spontaneous structural transition by breaking the crystal symmetry toward twin from parent.