Structure Of Titanium Research Articles

Effect of hydrogen on the basal dissociation of 〈a〉-type screw dislocation core in titanium

The existence of basal dissociated screw dislocation core structure of titanium with different H concentrations is investigated by first-principles calculation. The calculation of stacking fault energy of the basal plane with H in different layers suggests that a high H concentration would be beneficial for basal dissociation. The direct calculation based on the dislocation core instead proved that a small amount of H cannot stabilize the basal dissociated core structure. When H concentration increases, the basal dissociated core configuration and some mixed cores with basal faults could be more stable than the pyramidal dissociated structure.

Effect of ruthenium microadditives on the structure and corrosion resistance of titanium α-, pseudo-α-alloys

The paper examines electrochemical studies of forgings made of α, pseudo-α titanium alloys of industrial compositions and with the addition of ruthenium. Comparative dependences of the current density on time were constructed at various potentials in 3.5% NaCl for titanium alloys of industrial composition and with the addition of ruthenium. The breakdown potential of the titanium alloys under study was determined. Microstructural studies of titanium alloys of various compositions were carried out after determining the breakdown potential.

Microemulsion Templating Synthesis of Hierarchical Porous Ag‐Doped SiO2‐TiO2 Composites for Efficient Degradation of Noxious Methylene Blue Dye: Effect of Calcination Environment

AbstractWe report herein a dual function mesoporous structure of titanium oxide based porous carbon with large surface‐to‐volume ratios for efficient degradation of noxious methylene blue dye (MB) from an aqueous environment. The mesoporous photocatalysts is fabricated via direct template synthesis of highly ordered silica‐titania monolith doped with Ag0/Ag2O starting from a quaternary microemulsion liquid crystalline phase. The produced monoliths are subjected in‐situ to doping by growing silver, in the cubic cavities, and on the silica/titania structure's domain. This study investigated the efficiency of novel composite materials, consisting of silver‐doped silica‐titania (SiO2/TiO2), which is synthesized using the microemulsion templating approach. The photocatalytic performance of the synthesized composite in the photodegradation of MB has been studied. The procedure of photodegradation was employed to achieve decolorization of the cationic MB dye using visible light. The catalyst effectively achieved the decolorization of the dyed solution through the processes of adsorption and photodegradation. The composite consisting of SiO2, TiO2, and Ag2O at a ratio of 1 : 1:0.5, which underwent calcination in an air environment (AgOST), exhibited a removal efficiency of 99 % compared to its calcined state under argon (AgSTC).

Experimental and Histological Validation of Nanostructured Products Use in Maxillofacial Surgery

The aim of the study is using experimental histological techniques to validate the beneficial potential of specific medical devices made of nanostructured titanium, and compare their effect with factorymade products currently applied in maxillofacial surgery. Material and methods. The study involved 50 sexually mature male Chinchilla rabbits. An open fracture of the lower jaw was simulated in the animals. In the 1st series of the experiment, the fragments were fixed using nanostructured miniplates and miniscrews made of Grade 4 titanium. In the 2nd series, they were fixed with standard miniplates and miniscrews from Konmet LLC. The material for the study was taken on the 7th, 14th, 21st, 28th and 40th days after the operation. In all series the object of the study was the extirpated lower jaw in the fracture area. The prepared histological sections were stained with Mayer's hematoxylin and eosin. The immunohistochemistry technique was used to identify cells with signs of proliferation (synthesizing the Ki67 protein), to assess the expression of the synthesis of proteins p53, caspasa 3 and the anti-apoptotic protein bcl-2. The surfaces of titanium structures were studied by scanning electron microscopy. The results were processed statistically. Results. The study investigated the effect of miniplates and miniscrews made of nanostructured and standard titanium on rabbits. The data obtained revealed the nature of the proliferative and apoptotic potentials of osteoblasts in the regenerate, and also indicated an increase in the ratio of the number of cambial cells and cells with an apoptotic dominant in the zone contacting with the nanostructured surface of the titanium screw compared to the titanium screw manufactured by Konmet LLC. Taken together, the obtained data indicate that the use of nanostructured titanium Grade 4 for the production of miniplates and miniscrews has an optimizing effect on reparative osteogenesis. The mechanism of this effect is determined by the presence of osseointegration properties of titanium. Conclusion. Nanostructured titanium is advisable to use for the production of implants, reconstructive titanium plates and other products for bone grafting.

Comparison In Vitro Study on the Interface between Skin and Bone Cell Cultures and Microporous Titanium Samples Manufactured with 3D Printing Technology Versus Sintered Samples.

Percutaneous implants osseointegrated into the residuum of a person with limb amputation need to provide mechanical stability and protection against infections. Although significant progress has been made in the biointegration of percutaneous implants, the problem of forming a reliable natural barrier at the level of the surface of the implant and the skin and bone tissues remains unresolved. The use of a microporous implant structure incorporated into the Skin and Bone Integrated Pylon (SBIP) should address the issue by allowing soft and bone tissues to grow directly into the implant structure itself, which, in turn, should form a reliable barrier to infections and support strong osseointegration. To evaluate biological interactions between dermal fibroblasts and MC3T3-E1 osteoblasts in vitro, small titanium discs (with varying pore sizes and volume fractions to achieve deep porosity) were fabricated via 3D printing and sintering. The cell viability MTT assay demonstrated low cytotoxicity for cells co-cultured in the pores of the 3D-printed and sintered Ti samples during the 14-day follow-up period. A subsequent Quantitative Real-Time Polymerase Chain Reaction (RT-PCR) analysis of the relative gene expression of biomarkers that are associated with cell adhesion (α2, α5, αV, and β1 integrins) and extracellular matrix components (fibronectin, vitronectin, type I collagen) demonstrated that micropore sizes ranging from 200 to 500 µm of the 3D printed and sintered Ti discs were favorable for dermal fibroblast adhesion. For example, for representative 3D-printed Ti sample S6 at 72 h the values were 4.71 ± 0.08 (α2 integrin), 4.96 ± 0.08 (α5 integrin), 4.71 ± 0.08 (αV integrin), and 1.87 ± 0.12 (β1 integrin). In contrast, Ti discs with pore sizes ranging from 400 to 800 µm demonstrated the best results (in terms of marker expression related to osteogenic differentiation, including osteopontin, osteonectin, osteocalcin, TGF-β1, and SMAD4) for MC3T3-E1 cells. For example, for the representative 3D sample S4 on day 14, the marker levels were 11.19 ± 0.77 (osteopontin), 7.15 ± 0.29 (osteonectin), and 6.08 ± 0.12 (osteocalcin), while for sintered samples the levels of markers constituted 5.85 ± 0.4 (osteopontin), 4.45 ± 0.36 (osteonectin), and 4.46 ± 0.3 (osteocalcin). In conclusion, the data obtained show the high biointegrative properties of porous titanium structures, while the ability to implement several pore options in one structure using 3D printing makes it possible to create personalized implants for the best one-time integration with both skin and bone tissues.

Electron Concept of Hydrogen Embrittlement and Hydrogen-Increased Plasticity of Metals

Based on theoretical and experimental studies of hydrogen effect on the electron structure of iron, nickel and titanium, an electron concept is proposed for hydrogen embrittlement as well as for hydrogen-improved plasticity of engineering metallic materials. This concept implies a hydrogen-caused redistribution of valence electrons across their energy levels and an increase in the density of electron states at the Fermi level, causing a softening of the crystal lattice and, thereby, leading to a decrease in the specific energy of dislocations with consequent increase in their mobility. Innate phenomena in metallic solid solutions, namely, short-range atomic order in its two versions, short-range ordering and decomposition, are shown to be a precondition for the localization of plastic deformation. Hydrogen enhances merely this effect resulting in pseudo-brittle fracture. The role of hydrogen-induced superabundant vacancies in hydrogen-caused localization of plastic deformation and grain-boundary fracture in pure metals is discussed. Using the temperature- and strain-dependent internal friction, the enthalpies of hydrogen diffusion and hydrogen–dislocation binding are studied, and their controlling effect on the temperature- and strain-rate-dependent hydrogen embrittlement is demonstrated. Finally, a physical rationale is proposed for using hydrogen as a temporary alloying element in the technological processing of titanium alloys, and for a positive hydrogen effect on the fatigue life and plasticity of austenitic steels.

Room-Temperature Creep Deformation of a Pressure-Resistant Cylindrical Structure Made of Dissimilar Titanium Alloys

The long-term safety of pressure-resistant structures used in deep-sea equipment may be threatened by creep deformation. The creep deformation behavior of a pressure-resistant structure made of different titanium alloys, Ti-6Al-4V and Ti-4Al-2V, at room temperature is investigated in this research. The kinetics and mechanisms underlying creep deformation in these materials is explained by proposing an improved constitutive model considering the effects of stress level, loading rate and environmental temperature field, offering crucial information for optimizing design parameters and guaranteeing the lifespan of the structure. Model parameters are determined for the two types of titanium alloys based on tensile creep testing results and validated through a simulation of the experimental process. In this study, a material creep model was used to predict the long-term deformation of large pressure-resistant titanium structures to ensure safe long-term operation. The safety factor used in the model is 1.5. Finite element analyses are conducted for the creep behavior of the pressure-resistant structure under real operating circumstances based on the creep constitutive model. The simulation predicts stress distribution, strain evolution, and deformation size over long periods of time by integrating complicated geometries, boundary conditions, and material characteristics. The present research can provide basic information for the local impacts of creep deformation on the inside of facilities, which helps refine design strategies to reduce possible damage risks.

Investigating the influence of Al2O3 doping on TiO2 optoelectronic properties and charge separation efficiency

In this study, Aluminum oxide (Al2O3) was utilized as a dopant in the crystal structure of titanium dioxide (TiO2) to enhance the photovoltaic efficiency of n-i-p type organic solar cells. These solar cells were fabricated using a thin film of TiO2 doped with Al2O3, serving as the electron transport layer. TiO2 thin films were synthesized using different Al2O3 concentrations (0 %, 0.25 %, 0.5 %, and 1 % w/V) through the spin-coating technique. A blend of poly(3-hexylthiophene) and phenyl C61-butyric acid methyl ester (P3HT:PC61BM) was spin-cast at 600 rpm for 30 s, forming the solar cells active layer. Organic solar cells with an n-i-p structure were constructed, following the configuration FTO/TiO2:Al2O3/P3HT:PC61BM/MoO3/Ag. Investigations have been conducted to examine how varying concentrations of Al2O3 doping affect the photovoltaic performance of the solar cells. The power conversion efficiency (PCE) of the produced solar cells showed an increase from 2.74 % to 3.53 % at a 0.5 % Al2O3 doping concentration. The solar cells performance has been improved by adjusting the concentration of Al2O3. The findings show that the addition of Al2O3 to TiO2 films improves power conversion efficiency.

Novel Chemical Treatment of Porous Titanium Structures for Nanotextured Surface and Bioactive Behavior

Macroporous titanium structures are of interest in bone reconstruction because of their reduced modulus of elasticity (compared to bulk titanium), possibility of being colonized by cells, and biocompatibility. However, they are not bioactive and are not able to actively facilitate bone ingrowth or reduce bacterial adhesion. In the present research, work porous titanium scaffolds with different features (porosity 30–60 vol% and pore size 100–200 or 355–500 μm) are obtained by the space holder technique. Samples are characterized using optical microscopy, computed tomography, scanning electron microscopy (SEM), and X‐ray diffraction. Moreover, the theoretical elastic modulus and yield strength are calculated. A patented chemical treatment, able to produce a bioactive nanotextured oxide layer, has been optimized and successfully applied, for the first time, to structures with 50 vol% porosity and 100–200 μm pore size (as the most promising for bone substitution due to the biomechanical and biofunctional balance). Bare and modified samples are characterized using field emission SEM, zeta potential measurements, and in vitro bioactivity tests (soaking in simulated body solution) to evaluate the effectiveness of the surface chemical treatment.

Influence of Al doping on crystal structure, magnetic and optical properties of TiO2 compound

Recently, an attempt to search for the novel material which can be applicable for spintronics devices, has become a highly debated and intensively investigated field of study. Within the scope of this investigation, Ti1−xAlxO2 (0≤x≤0.12) polycrystalline samples were produced using the traditional solid-state reaction method, and their crystal structure, magnetic, and optical characteristics were investigated. Single rutile phase with tetragonal crystal structure of titanium oxide is seen from the X-ray diffraction patterns study. The variation in the lattice parameter elucidate that Al3+ ions successfully substitute the Ti4+ ions. The analyses of the optical characteristics reveals that the incorporation of Al into the TiO2 matrix leads to a reduction in the optical band gap. Investigation on magnetic characteristics showed that all Ti1−xAlxO2 compounds displayed room temperature ferromagnetic nature with 81Oe≤Hc≤930Oe. Hall effect measurements show that all doped samples display p-type conductivity while un-doped TiO2 exhibits n-type conductivity and with increasing Al-doping concentration, the hole carrier density rises.

Preparation and mechanical performance analysis of porous Ti6Al4V scaffold fabricated by direct ink writing

In order to mitigate the stress-shielding effect resulting from the stiffness disparity between titanium alloy and bone, the use of additive manufacturing to create porous Ti6Al4V components shows promise for orthopedic implant applications. In this study, a novel hot-melt–quick-frozen polyvinyl alcohol hydrogel was developed for direct ink writing to create porous titanium structures using Ti6Al4V powders with an irregular morphology. The rheological and sintering properties of inks with varying solid phase contents were examined to assess their molding quality. Furthermore, the effect of porosity on the morphology, shrinkage, and mechanical properties of the scaffolds was thoroughly investigated. The results of the experiments show that inks loaded with 65 vol. % Ti6Al4V particles exhibit the highest printing performance. Furthermore, the analysis revealed a positive correlation between the total porosity of the scaffold and its mechanical performance. In particular, the strength of the scaffold with a porosity of 54.8% exceeded that of human bone, and it also exhibited matched stiffness. Upon analyzing the final microstructure and mechanical properties, it is evident that these scaffolds meet the necessary criteria for use as orthopedic implants.

Synthesis of platinum-nickel nanoparticles supported by carbon and titanium oxide structures for efficient and enhanced formic acid oxidation

In this study, Platinum Nickel (PtNi) nanoparticles was synthesized using the chemical reduction method and functionalized multi-walled carbon nanotube (f-MWCNT) was synthesized by handling multi-walled carbon nanotube (MWCNT) with weak acid using the arc discharge method. To be evaluated in formic acid oxidation, f-MWCNT supported by PtNi (PtNi@f-MWCNT) and titanium oxide (TiO2) supported by PtNi (PtNi@TiO2) catalysts were synthesized using chemical reduction method. The comparison of PtNi, PtNi@f-MWCNT, and PtNi@TiO2 catalysts obtained in the study for formic acid oxidation is presented and their characterizations were carried out by X-ray Diffraction (XRD), Transmission Electron Microscope (TEM), and Fourier Transform Infrared Spectrometer (FTIR). According to TEM results; PtNi, PtNi@f-MWCNT, and PtNi@TiO2 particle sizes were found to be 12.00 nm, 7.37 nm, and 5.38 nm, respectively. According to the CV results obtained for formic acid oxidation, the anodic peak peaks for PtNi, PtNi@f-MWCNT, and PtNi@TiO2 were 61.20 mA.cm−2, 80.17 mA.cm−2 and 65.07 mA.cm−2, respectively. These results showed that the addition of f-MWCNT and TiO2 support exhibited 1.30 and 1.06 times higher electrocatalytic activity for formic acid oxidation and higher resistance to CO poisoning with If/Ib ratios of 0.97 and 1.48, respectively. With the long-term stability tests obtained, it was observed that the f-MWCNT-supported catalyst showed approximately 9 times more current at the end of 5000 s and provided faster charge transfer with EIS. These findings demonstrated that a more cost-effective catalyst with high electrocatalytic activity was synthesized by obtaining f-MWCNTs from MWCNTs using the arc discharge method. It has also been revealed that TiO2 and f-MWCNT supports exhibit very high potential for fuel cell applications.

New tetragonal phases of titanium under shock loading - Predicted by molecular dynamics and ab initio calculations

Based on molecular dynamics simulations of the long-term evolution of polycrystalline titanium structures under shock waves, a novel phase (ζ) has been identified to emerge at shock pressures of approximately 20 GPa. This phase originates from the initial HCP phase and the disordered structure induced by the shock. The energy change characteristics during this phase transition are explained based on the Helmholtz free energy under volume constraints. The ζ phase comprises framework atoms (F-atoms) with fixed positions and unfixed interstitial atoms (I-atoms), exhibiting incomplete symmetry. Validation of this phase structure using ab initio simulations and machine learning potentials supports its existence as a metastable structure. The transformation from the initial α phase to ζ phase is diffusional transformation, while the reverse transformation is multistage displacive transformation.

Production of porous titanium structures by combining hot isostatic pressing and solid-state foaming

The Hot Isostatic Pressing (HIP) process is based on the combined action of high levels of pressure and temperature. In general, such a process is used for reducing or eliminating microporosities in the component, especially when it is produced by additive manufacturing (AM) or casting. In the present work HIP is used for compacting TI6Al4V-ELI powders by means of a pressurized Argon gas acting at high temperature on a sealed can under vacuum in which Argon is previously inflated; thus, a subsequent Solid-State Foaming (SSF) heat treatment allows to produce a Titanium foam without any melting by exploiting gas entrapment. Samples extracted from billets produced setting different HIP parameters (size of Titanium particles and pressures) have been investigated in this work by means of heat treatments in furnace for the SSF: the temperature was kept constant (1020 °C), but the duration was varied in the range 1 - 6 h; the samples were finally analysed by Light Microscopy. Finally, the Response Surface Method (RSM) was used to determine the conditions able to increase both the size and the percentage area of the pores in order to fully control both the involved processes (HIP and SSF). Experimental results revealed that the porosity determined by the SSF is strongly affected by HIP parameters and by the SSF duration: the highest dimension of Ti particles and the highest level of Argon pressure determined the largest values of porosity, in terms of both percentage and pore dimension. The investigated process for producing porous titanium structures can be properly and efficiently combined with manufacturing processes able to create highly customised parts, not only in terms of geometry but also in terms of porosity.

Highly Porous Titanium Cups Frequently Presenting with Radiolucent Lines in Cementless Primary Total Hip Arthroplasty: A Retrospective Cohort Study.

Background/Objectives: A highly porous titanium cup with a three-dimensional metal interface was recently introduced to improve biological fixation and survival. However, radiography has revealed concerns regarding these cups, despite their excellent short- and mid-term clinical outcomes. This study compared the clinical and radiographic results of a highly porous titanium cup with those of a hydroxyapatite-coated porous titanium cup after primary total hip arthroplasty (THA). Methods: Fifty-one primary THAs were investigated. A highly porous titanium cup was used in 17 hips, and a hydroxyapatite-coated porous titanium cup was used in 34 hips. No significant differences in preoperative patient demographic characteristics were observed between the two groups. The 2-year postoperative clinical and radiographic results were compared. Results: Radiolucent lines were observed in 13 (76%) of 17 hips with highly porous titanium cups and in none (0%) of 34 hips with hydroxyapatite-coated porous titanium cups (p < 0.001). In the highly porous titanium cup group, radiolucent lines were observed in five hips (29%) in one zone, two hips (11%) in two zones, and six hips (35%) in three zones. No cup loosening was observed in either group. Conclusions: Radiolucent lines were significantly more frequent in highly porous titanium cups. This study suggests that, compared to the three-dimensional structure of porous titanium, the hydroxyapatite coating of porous titanium had a greater influence on bone ingrowth in the short term. The meaning of these findings in the long-term is unclear yet.

Synthesis of titanium silicalite-1 supported zinc catalysts for efficient and clean epoxidation of 1-hexene and methyl oleate

To improve the catalytic epoxidation activity of conventional TS-1 zeolite under acid-free conditions, a series of TS-1-supported zinc (xZn/TS-1) catalysts were prepared and evaluated in the epoxidation of 1-hexene and methyl oleate (MO) with H2O2 oxidant. The microstructure of xZn/TS-1 was investigated using various characterization techniques, and the results showed that the introduction of Zn species was not only well dispersed on the surface of TS-1 but also did not disrupt the crystal structure of TS-1 and tetrahedral framework titanium. Furthermore, the Ti-O-Zn structure can be formed between Zn and Ti species through O-atomic coordination, which improves the vulnerability of the Ti-O bond to attack the H2O2 molecule, and ultimately facilitates the epoxidation reaction between 1-hexene and MO. In addition, the 2% Zn/TS-1 catalysts showed optimal conversions of 45.7 % and 75.41 % for 1-hexene and MO, respectively, and exhibited good catalytic stability and regeneration during the epoxidation process.

Effect of current density on the morphology and electrochemical properties of nanotubular TiO2 for implant applications

This study focuses on investigating the influence of current density (i) (A/dm2) at values of 0.5 A dm−2, 1.0 A dm−2 1.5 A dm−2, and 2.0 A/dm2 on the surface structure of nanotubular titanium dioxide (TiO2) in an ethylene glycol solvent containing a certain amount of fluoride salt and water. The surface structure observed via FESEM images reveals that different current densities yield different nanotubular TiO2 structures, predominantly in the form of anatase TiO2 crystals. EIS and CV measurements indicate that at a current density of i = 1.5 A dm−2, the nanotubular TiO2 layer exhibits corrosion resistance performance up to 90.06% compared to the bare titanium (Ti) samples. Confocal laser scanning microscopy (CLSM) demonstrates enhanced attachment of BHK cells on anodized titanium surfaces compared to unmodified controls. These findings suggest that nanotubular TiO2 presents a biocompatible material with promising potential for biomedical implant applications.

A systematic DFT study of structure and electronic properties of titanium dioxide.

DFT functionals are of paramount importance for an accurate electronic and structural description of transition metal systems. In this work, a systematic analysis using some well-known and commonly used DFT functionals is performed. A comparison of the structural and energetic parameters calculated with the available experimental data is made in order to find the adequate functional for an accurate description of the TiO2 bulk and surface of both anatase and rutile structures. In the absence of experimental data on the surface energy, the theoretical predictions obtained using the high-accuracy HSE06 functional were used as a reference to compare against the surface energy values calculated with the other DFT functionals. A clear improvement in the electronic description of both anatase and rutile was observed by introducing the Hubbard U correction term to PBE, PW91, and OptPBE functionals. The OptPBE-U4 functional was found to offer a good compromise between accurately describing the structural and electronic properties of titania.

Tailoring room-temperature ferroelectric, magnetic and magnetoelectric properties in La and Se co-doped BiFeO3 embedded Ti3C2Tx MXene free-standing ceramics film

The ever-growing need for advancement in data storage technology demands materials that can be controlled by as many degrees as possible. In this regard, multiferroic materials that show response both in electric and magnetic dimensions are of great interest especially when being investigated in two-dimensional materials that have their potential applications. In this study, we have incorporated Lanthanum (La) doped Bismuth Ferrite (BLFO), and La and Selenium (Se) co-doped BFO (BLFSO) with two-dimensional layered titanium carbide (Ti3C2Tx) from the class of MXene as hybrid composites. The structural, optical and morphological investigation validated the successful etching of MXene from MAX, successful hybrid formation with conserved crystal structure and new phases of titanium dioxide (TiO2) detected when the samples underwent heat treatment. This heat treatment was performed in order to enhance the multiferroic properties owing to the presence of TiO2. Our results showed that the heated BLFSO-embedded Ti3C2Tx hybrid composite showed maximum remnant polarization and higher dielectric response when measured with respect to the varying electric field and at different frequencies. The prepared samples also exhibited tunable polarization response at an applied static magnetic field, unveiling their magnetoelectric properties.

Role of Cr addition in Ni-based interlayer on strengthening titanium and steel dissimilar bimetallic structures enabled by directed energy deposition with laser beam

For searching alternative strategies to improve reliability of titanium and steel dissimilar bimetallic joints manufactured by directed energy deposition with laser beam (DED-LB), pure titanium was considered as cladding deposited on carbon steel substrate with Ni-based alloy interlayers in this work. Effect of different interlayer modification methods on the microstructure evolution and mechanical properties of joints was analyzed systematically. The distribution of intermetallic compounds (IMCs) such as β-Ti, Ti2Ni, TiNiFe0.2, Ti2Ni3Si and TiB2 in joints was revealed. The results showed that original deposition cracks caused by residual stress during processing could be alleviated by substrate preheating treatment while suppressed by the modified interlayer with Cr completely. Notably, additional Cr could reduce reaction activity between Ti and Ni atoms by raising laser molten pool liquidus, leading to fewer IMCs in joints. As a result, both bonding strength and toughness of joints were remarkably improved. The findings emphasize more significance of optimizing Ni-based interlayer composition with Cr than preheating method to improve the mechanical performance of DED-LB joints.