Showing papers on "Titanium published in 2018"
TL;DR: This paper demonstrates an efficient fluoride-free etching method based on the anodic corrosion of titanium aluminium carbide in a binary aqueous electrolyte that paves a safe way to the scalable synthesis and application of MXene materials.
Abstract: Two-dimensional (2D) titanium carbide (Ti3 C2 ) is emerging as an important member of the MXene family. However, fluoride-based synthetic procedures remain an impediment to the practical applications of this promising class of materials. Here we demonstrate an efficient fluoride-free etching method based on the anodic corrosion of titanium aluminium carbide (Ti3 AlC2 ) in a binary aqueous electrolyte. The dissolution of aluminium followed by in situ intercalation of ammonium hydroxide results in the extraction of carbide flakes (Ti3 C2 Tx , T=O, OH) with sizes up to 18.6 μm and high yield (over 90 %) of mono- and bilayers. All-solid-state supercapacitor based on exfoliated sheets exhibits high areal and volumetric capacitances of 220 mF cm-2 and 439 F cm-3 , respectively, at a scan rate of 10 mV s-1 , superior to those of LiF/HCl-etched MXenes. Our strategy paves a safe way to the scalable synthesis and application of MXene materials.
362 citations
TL;DR: Powder metallurgy (PM) of titanium is a potentially cost-effective alternative to conventional wrought titanium as mentioned in this paper, which examines both traditional and emerging technologies, including the prod...,.
Abstract: Powder metallurgy (PM) of titanium is a potentially cost-effective alternative to conventional wrought titanium. This article examines both traditional and emerging technologies, including the prod...
336 citations
293 citations
TL;DR: Compared to homogeneous diamond porous scaffolds, FGPSs provide a wide range of mutative pore size and porosity, which are potential to be tailored to optimize the pore space for bone tissue growth.
Abstract: A significant requirement for a bone implant is to replicate the functional gradient across the bone to mimic the localization change in stiffness. In this work, continuous functionally graded porous scaffolds (FGPSs) based on the Schwartz diamond unit cell with a wide range of graded volume fraction were manufactured by selective laser melting (SLM). The micro-topology, strut dimension characterization and effect of graded volume fraction on the mechanical properties of SLM-processed FGPSs were systematically investigated. The micro-topology observations indicate that diamond FGPSs with a wide range of graded volume fraction from 7.97% to 19.99% were fabricated without any defects, showing a good geometric reproduction of the original designs. The dimensional characterization demonstrates the capability of SLM in manufacturing titanium diamond FGPSs with the strut size of 483-905µm. The elastic modulus and yield strength of the titanium diamond FGPSs can be tailored in the range of 0.28-0.59GPa and 3.79-17.75MPa respectively by adjusting the graded volume fraction, which are comparable to those of the cancellous bone. The mathematical relationship between the graded porosity and compression properties of a FGPS was revealed. Furthermore, two equations based on the Gibson and Ashby model have been established to predict the modulus and yield strength of SLM-processed diamond FGPSs. Compared to homogeneous diamond porous scaffolds, FGPSs provide a wide range of mutative pore size and porosity, which are potential to be tailored to optimize the pore space for bone tissue growth. The findings provide a basis of new methodologies to design and manufacture superior graded scaffolds for bone implant applications.
241 citations
TL;DR: Inorganic α-Ag2S semiconductor, which has preferential slip planes in the crystal structure and irregularly distributed bonds of silver atoms preventing cleavage, demonstrates metal-like ductility at room temperature.
Abstract: Ductility is common in metals and metal-based alloys, but is rarely observed in inorganic semiconductors and ceramic insulators. In particular, room-temperature ductile inorganic semiconductors were not known until now. Here, we report an inorganic α-Ag2S semiconductor that exhibits extraordinary metal-like ductility with high plastic deformation strains at room temperature. Analysis of the chemical bonding reveals systems of planes with relatively weak atomic interactions in the crystal structure. In combination with irregularly distributed silver–silver and sulfur–silver bonds due to the silver diffusion, they suppress the cleavage of the material, and thus result in unprecedented ductility. This work opens up the possibility of searching for ductile inorganic semiconductors/ceramics for flexible electronic devices.
225 citations
184 citations
11 Sep 2018
173 citations
TL;DR: In this paper, the authors provide a review of FSW of similar and dissimilar titanium alloys focusing on surface, and subsurface properties, such as microstructural and mechanical properties, texture evolution, current challenges summarizing a possible remedy, encompassing the recent development and research in the field.
157 citations
TL;DR: The present investigations reveal a promising solidification and cooling path for α formation not yet exploited, in which α does not inherit the usual crystallographic orientation relationship with the parent β phase, and the associated decrease in anisotropy represents a step forward toward a next generation of titanium alloys for AM.
Abstract: Metal-based additive manufacturing (AM) permits layer-by-layer fabrication of near net-shaped metallic components with complex geometries not achievable using the design constraints of traditional manufacturing. Production savings of titanium-based components by AM are estimated up to 50% owing to the current exorbitant loss of material during machining. Nowadays, most of the titanium alloys for AM are based on conventional compositions still tailored to conventional manufacturing not considering the directional thermal gradient that provokes epitaxial growth during AM. This results in severely textured microstructures associated with anisotropic structural properties usually remaining upon post-AM processing. The present investigations reveal a promising solidification and cooling path for α formation not yet exploited, in which α does not inherit the usual crystallographic orientation relationship with the parent β phase. The associated decrease in anisotropy, accompanied by the formation of equiaxed microstructures represents a step forward toward a next generation of titanium alloys for AM.
156 citations
TL;DR: Experimental measurements and theoretical calculations show that the homojunction of oxygen and titanium vacancies changes the charge density of TiO2, and a strong EPR signal caused by oxygen vacancies and an unreported strong titanium vacancies signal of 2D 1 H TQ-SQ MAS NMR are present.
Abstract: The homojunction of oxygen/metal vacancies and its interfacial n-p effect on the physiochemical properties are rarely reported. Interfacial n-p homojunctions of TiO2 are fabricated by directly decorating interfacial p-type titanium-defected TiO2 around n-type oxygen-defected TiO2 nanocrystals in amorphous-anatase homogeneous nanostructures. Experimental measurements and theoretical calculations on the cell lattice parameters show that the homojunction of oxygen and titanium vacancies changes the charge density of TiO2 ; a strong EPR signal caused by oxygen vacancies and an unreported strong titanium vacancies signal of 2D 1 H TQ-SQ MAS NMR are present. Amorphous-anatase TiO2 shows significant performance regarding the photogeneration current, photocatalysis, and energy storage, owing to interfacial n-type to p-type conductivity with high charge mobility and less structural confinement of amorphous clusters. A new "homojunction of oxygen and titanium vacancies" concept, characteristics, and mechanism are proposed at an atomic-/nanoscale to clarify the generation of oxygen vacancies and titanium vacancies as well as the interface electron transfer.
TL;DR: There is an association between biocorrosion, presence of titanium particles, and biological implant complications, but there is insufficient evidence to prove a unidirectional causal relationship.
Abstract: Objectives To compile the current evidence regarding the association between the release of titanium particles and biologic complications of dental implants. Material and methods This is a critical review. We searched the literature using the terms "corrosion," "allergy," "hypersensitivity," or "particles" together with "titanium," "Ti," "TiO2. " The bibliographies of identified publications and previously published review articles were scanned to find additional related articles. We included clinical studies, in vivo and in vitro experiments. Results Titanium particles and degradation products of titanium have been detected in oral and nonoral tissues. Particles are released from surfaces of dental implants because of material degradation in a process called tribocorrosion. It involves mechanical wear and environmental factors, notably contact to chemical agents and interaction with substances produced by adherent biofilm and inflammatory cells. In vitro, titanium particles can interfere with cell function and promote inflammation. A temporal association between exposure to titanium and occurrence of tissue reactions suggested hypersensitivity in a limited number of cases. However, there is poor specificity as the observed reactions could be initiated by other factors associated with the placement of implants. Titanium particles are commonly detected in healthy and diseased peri-implant mucosa alike, at low levels even in gingiva of individuals without titanium implants. Rather than being the trigger of disease, higher concentrations of titanium in peri-implantitis lesions could be the consequence of the presence of biofilms and inflammation. Conclusion There is an association between biocorrosion, presence of titanium particles, and biological implant complications, but there is insufficient evidence to prove a unidirectional causal relationship.
TL;DR: In this article, a balanced solution for the stress shielding and the poor osseointegration in titanium implants is proposed, with a porosity of 100-200μm of pore size employing space-holder technique (50-vol% NH4HCO3, 800-MPa at 1250°C during 2h under high vacuum conditions), obtaining a good equilibrium between stiffness and mechanical resistance.
Abstract: The stress shielding and the poor osseointegration in titanium implants are still problems to be resolved. In this context, this work proposes a balanced solution. Titanium samples were fabricated, with a porosity of 100–200 μm of pore size employing space-holder technique (50 vol% NH4HCO3, 800 MPa at 1250 °C during 2 h under high vacuum conditions), obtaining a good equilibrium between stiffness and mechanical resistance. The porous titanium substrates were coated with hydroxyapatite, obtained by sol-gel technique: immersion, dried at 80 °C and heat treatment at 450 °C during 5 h under vacuum conditions. Phases, surface morphology and interfacial microstructure of the transverse section were analyzed by Micro-Computed Tomography, SEM and confocal laser, as well as the infiltration capability of the coating into the metallic substrate pores. The FTIR and XRD showed the crystallinity of the phases and the chemical composition homogeneity of the coating. The size and interconnected pores obtained allow the infiltration of hydroxyapatite (HA), possible bone ingrowth and osseointegration. The scratch resistance of the coating corroborated a good adherence to the porous metallic substrate. The coated titanium samples have a biomechanical and biofunctional equilibrium, as well as a potential use in biomedical applications (partial substitution of bone tissue).
TL;DR: Nano-sized hierarchical titanosilicate TS-1 without extra-framework anatase TiO2 has been successfully synthesized by using Triton X-100 as a mesoporous template under rotational crystallization conditions as discussed by the authors.
Abstract: Nano-sized hierarchical titanosilicate TS-1 without extra-framework anatase TiO2 has been successfully synthesized by using Triton X-100 as a mesoporous template under rotational crystallization conditions. The resultant material contains a large external surface area and uniform mesopores (2–4 nm). Notably, the titanium ions are fully incorporated into the framework of TS-1 and no extra anatase TiO2 exists. Triton X-100 and rotational crystallization conditions play an important role in eliminating anatase TiO2. The addition of Triton X-100 slows down the crystallization rate of TS-1, while the rota-crystallization accelerates the incorporation rate of Ti, so that the insertion rate of titanium into the framework matches well with that of silicon. As such, the generation of extra-framework anatase TiO2 can be inhibited. Furthermore, in comparison with nano-sized hierarchical TS-1 prepared under static conditions, nano-sized hierarchical TS-1 prepared under rotational conditions exhibits excellent catalytic activity and high stability in alkene epoxidation, especially in bulky alkene epoxidation. The facile synthetic strategy for nano-sized hierarchical TS-1 without extra-framework anatase TiO2 may open new perspectives for its potential application in selective oxidation reactions involving large molecules.
TL;DR: In this article, the formation mechanism of Ti3AlC2 MAX phase, synthesized using elemental titanium, aluminum, and carbon (graphite) powders via wave propagation and thermal explosion techniques, was investigated.
TL;DR: In this paper, a nanostructured titanium peroxide was facilely synthesized via an oxidation coupled with precipitation process in order to remove thallium(I) from water.
TL;DR: The Ti8(μ2-O)8( μ2-OH)4 node of the Ti-BDC MOF (MIL-125) provides a single-site model of the classical TiO2 support to enable CoII-hydride-catalyzed arene hydrogenation, definitively proving the pivotal role of TiIII in the performance of the supported catalyst.
Abstract: Titania (TiO2) is widely used in the chemical industry as an efficacious catalyst support, benefiting from its unique strong metal–support interaction. Many proposals have been made to rationalize this effect at the macroscopic level, yet the underlying molecular mechanism is not understood due to the presence of multiple catalytic species on the TiO2 surface. This challenge can be addressed with metal–organic frameworks (MOFs) featuring well-defined metal oxo/hydroxo clusters for supporting single-site catalysts. Herein we report that the Ti8(μ2-O)8(μ2-OH)4 node of the Ti-BDC MOF (MIL-125) provides a single-site model of the classical TiO2 support to enable CoII-hydride-catalyzed arene hydrogenation. The catalytic activity of the supported CoII-hydride is strongly dependent on the reduction of the Ti-oxo cluster, definitively proving the pivotal role of TiIII in the performance of the supported catalyst. This work thus provides a molecularly precise model of Ti-oxo clusters for understating the strong me...
TL;DR: In this article, an iridium-based porous transport layer (PTL) was used to protect the titanium PTL from passivation by sputtering very thin layers of iridium onto commercially available PTLs.
TL;DR: A simple hydrothermal approach has been successfully applied for a large scale synthesis of anatase titanium dioxide nanoparticles (TiO 2 NPs) using titanium glycolate precursors and is utilized for the fabrication of low-cost high performance acetone (CH 3 COCH 3 ) gas sensors after corroborating the crystallinity, phase-purity, and surface morphology investigations.
Abstract: In the present study, a simple hydrothermal approach has been successfully applied for a large scale synthesis of anatase titanium dioxide nanoparticles (TiO 2 NPs) using titanium glycolate precursors and is utilized for the fabrication of low-cost high performance acetone (CH 3 COCH 3 ) gas sensors after corroborating the crystallinity, phase-purity, and surface morphology investigations. Several randomly distributed TiO 2 aggregates, composed of NPs, are noticed from morphology analysis. Chemiresistive properties of as-fabricated TiO 2 sensors attempted towards host of oxidizing and reducing gases, reveal a superior selectivity to CH 3 COCH 3 with a maximum response of 15.24 (1000 ppm) @270 °C compared to other target gases. One of the key features of as-fabricated TiO 2 sensor is the lowest detection limit of 500 ppb to CH 3 COCH 3 with rapid response and recovery times, signifying commercial potential of the developed sensor materials. The effect of operating temperature along with various concentrations of CH 3 COCH 3 on the gas sensing properties of TiO 2 sensor has thoroughly been investigated and reported. Finally, the interaction mechanism between the CH 3 COCH 3 molecules and the TiO 2 NPs sensor was elaborated in depth for a thorough understanding sensor performance experimentally and supposedly.
TL;DR: In this paper, the experimental and theoretical studies on EDM that aimed to improve the process performance, including material removal rate, surface quality, and tool wear rate, among others.
Abstract: Electric discharge machining (EDM) is one of the leading edge machining processes successfully used to machine hard-to-cut materials in wide range of industrial applications. It is a non-conventional material removal process that can machine a complex shapes and geometries with high accuracy. The principle of the EDM technique is to use thermoelectric energy to erode conductive components by rapidly recurring sparks between the non-contacted electrode and workpiece. To improve EDM performance, the machine’s operating parameters need to be optimized. Studies related to the EDM have shown that the appropriate selection of the process, material, and operating parameters had considerably improved the process performance. This paper made a comprehensive review about the research studies on the EDM of different grades of titanium and its alloys. This review presents the experimental and theoretical studies on EDM that aimed to improve the process performance, including material removal rate, surface quality, and tool wear rate, among others. This paper also examines evaluation models and techniques used to determine the EDM process conditions. Moreover, the paper discusses the recent developments in EDM and outlines the progression for future research.
TL;DR: The development and pre-clinical evaluation of nano-texturised, biomimetic, surfaces of titanium (Ti) implants treated with titanium dioxide (TiO2) nanotube arrays is reviewed and the properties of Ti implant surfaces enhanced with TiO2 nanotubes show great promise.
Abstract: The development and pre-clinical evaluation of nano-texturised, biomimetic, surfaces of titanium (Ti) implants treated with titanium dioxide (TiO2) nanotube arrays is reviewed. In vitro and in vivo evaluations show that TiO2 nanotubes on Ti surfaces positively affect the osseointegration, cell differentiation, mineralisation, and anti-microbial properties. This surface treatment can be superimposed onto existing macro and micro porous Ti implants creating a surface texture that also interacts with cells at the nano level. Histology and mechanical pull-out testing of specimens in rabbits indicate that TiO2 nanotubes improves bone bonding nine-fold (p = 0.008). The rate of mineralisation associated with TiO2 nanotube surfaces is about three times that of non-treated Ti surfaces. In addition to improved osseointegration properties, TiO2 nanotubes reduce the initial adhesion and colonisation of Staphylococcus epidermidis Collectively, the properties of Ti implant surfaces enhanced with TiO2 nanotubes show great promise. Cite this article: Bone Joint J 2018;100-B(1 Supple A):9-16.
TL;DR: The first case of successfully synthesising amorphous TiO2@NH2-MIL-125(Ti) MOF-encapsulated heterostructures by a facile process is provided.
TL;DR: In this article, the general corrosion behavior of AISI 316 stainless steel and pure titanium (pure Ti) in H2SO4 solutions containing fluoride (F−) and chloride (Cl−) ions was evaluated quantitatively using potentiodynamic polarization tests.
TL;DR: In this article, the microstructure evolution and mechanical properties of spark plasma sintered commercially pure titanium were studied, which was performed at a temperature range of 750-1350°C for a dwell time of 5min under an external pressure of 50MPa in vacuum.
TL;DR: In this paper, the laser beam welding of similar and dissimilar titanium alloys is reviewed, focusing on the influence of the processing parameters, microstructure-property relationship, metallurgical defects, and possible remedies.
Abstract: In recent years, there is an increased in used of titanium alloys for some parts of mass-produced automobiles and aerospace. However, titanium alloys are characterized by difficult machinability, high melting temperature, high strength, low thermal conductivity, and high reactivity to oxygen, which overshadowed conventional manufacturing processes. To this end, there is a pressing need for more efficient technologies for the manufacture of low-cost titanium structures. Over the years, several joining techniques have been considered for fabrication of titanium alloys. Nevertheless, laser beam welding presents a viable option for welding of titanium due its versatility, high specific heat input, and flexibility. To date, under optimum processing conditions, the strength of the laser-welded titanium alloys can be close to the original material; however, there are still some processing problems such as lower elongation and corrosion resistance coupled with inferior fatigue properties. In this document, the laser beam welding of similar and dissimilar titanium alloys is reviewed, focusing on the influence of the processing parameters, microstructure-property relationship, metallurgical defects, and possible remedies.
TL;DR: In this paper, a thorough review of current non-metal doping methods of TiO2 to improve photocatalyst activation under visible light is presented, and the resultant characteristics of the chemical structure, physical structure, and optical properties of the doped photocatalysts are discussed.
Abstract: Titanium dioxide (TiO2) is an efficient photocatalyst for removing organics in photocatalytic wastewater treatment, but its low photoactivity limits its practical applications in a visible-light-driven chemical reaction. Many efforts have been made in the activation of the visible light absorption property on TiO2 photocatalyst. In this paper, a thorough review of current non-metal doping methods of TiO2 to improve photocatalyst activation under visible light is presented. The focus of this study is on doping non-metals onto TiO2 by several methods to enhance its visible light photoactivity. Besides, the resultant characteristics of the chemical structure, physical structure, and optical properties of the doped photocatalysts are discussed. This review enables a better understanding of current advantages and disadvantages that can arise during the production of non-metal-doped TiO2 and its applications. The annealing and hydrothermal methods are found to be more efficient in preparing doped photocatalysts with respect to time and costs. When choosing between these two approaches, the hydrothermal method can be applied using a variety of precursors, whereas the annealing methods are restricted only to solid form precursors. Thus, the hydrothermal method is a more favorable method of non-metal doping of TiO2. However, studies should focus on the effects of different factors involved in each synthesis/preparation method to determine optimal preparation conditions.
TL;DR: In this article, the influence of sulfides on the passivation behavior of titanium alloy TA2 in simulated seawater environments was studied by electrochemical methods, surface topology and X-ray photoelectron spectroscopy (XPS).