Structure Of Titanium Carbide Research Articles

Electric arc synthesis of titanium carbide using carbon obtained from thermal conversion of waste from the power industry

The work presents for the first time the results of obtaining titanium carbide using a vacuum-free electric arc method using various types of biocarbon obtained by classical pyrolysis of biomass waste, such as tangerine peel, pomelo peel, banana peel, pine nut shells, walnut shells. Analysis of X-ray diffraction patterns of the synthesized materials showed the repeatability of the experiment with the receipt of diffraction maxima indicating the formation of a cubic structure of titanium carbide. An analysis of the thermal oxidation of the resulting powders showed that up to a thousand degrees the process proceeds quite slowly, but with increasing temperature the oxidation rate increases significantly. It has been established that during thermal heating in an oxidizing environment, the mass of the studied titanium carbide powders obtained using various types of carbon increases, which is confirmed by thermogravimetric analysis.

Synthesis of titanium carbide (TiC) using recycled precursor for potential scale-up of low-cost MXene

In this study, we report the low-cost synthesis of titanium carbide (TiC) from recycled precursors and further used to synthesize MAX phase material, Ti3AlC2. The recycled precursor, carbon extracted from the used tyres using a few processes is used to synthesize TiC with high purity. The use of tyre-derived carbon offers several environmental benefits such as facile synthesis, low cost, environment-friendly, etc. The as-synthesized TiC is further used as a precursor to synthesize low-cost Ti3AlC2. The structure of TiC and Ti3AlC2 are characterized by UV–visible spectroscopy and X-ray diffraction analysis. The microstructure and surface morphology of the samples are examined using scanning electron microscope imaging and energy-dispersive X-ray spectroscopy. The chemical bonding information is analyzed by Fourier transform infrared spectroscopy and the thermal behaviour of the samples are examined using thermogravimetric analysis. The successful cost-effective synthesis of TiC and Ti3AlC2 are confirmed from XRD analysis and the samples show high purity. TiC and Ti3AlC2 show excellent thermal stability which helps in their potential applications in the future. This study proclaims a new strategy to synthesize low-cost Ti3AlC2 MXene for the large-scale production using TiC precursor where the TiC precursor is synthesized using carbon precursor.

TF-Al/TiC highly reactive composite particle for application potential in solid propellants

Aluminum (Al) powder is widely used in solid propellants to improve specific impulse. But the dense alumina (Al2O3) on the surface of Al will reduce reactivity and heat release of Al. The phenomenon that Al2O3 and titanium carbide (TiC) react to generate gas and form pores has been found. Combined this phenomenon, thick flake Al/TiC (TF-Al/TiC) highly reactive composite particle was designed, which has the structure of TiC embedded in the TF-Al. Then TF-Al/3%TiC, TF-Al/4%TiC, TF-Al/5%TiC and TF-Al/6%TiC were successfully prepared by two-step ball milling. Samples were characterized by SEM and TG-DSC. The results indicated that TF-Al/TiC highly reactive composite particle was a finely dispersed powder sample and their DSC curves had exothermic peak before 1000 ℃. And when the TiC content was less than 5%, as the content of TiC added increases, the heat release increased. And TF-Al/5%TiC had the highest heat release (21419 J/g). Furthermore, the reaction process of TF-Al/5%TiC was studied by SEM, EDS, XRD, XPS and TG-MS. Characterization results shown that Al2O3 on the surface of TF-Al was decomposed by TiC in situ before 633 ℃, and the pores generated by the gaseous products would further increase the contact area between inside active Al and oxidant. So the reactivity and heat release of TF-Al/5%TiC had been improved. Those results indicated that TF-Al/TiC highly reactive composite particle has a promising application in solid propellants.

Intergranular passivation of the TiC coating for enhancing corrosion resistance and surface conductivity in stainless-steel bipolar plates

Stainless-steel bipolar plates (BPPs) are of great significance in low-cost, easily processable, lightweight proton exchange membrane fuel cells (PEMFCs) despite the challenge presented by corrosion in protective coatings. Localized corrosion along the grain boundaries in a crystal film is common, but few preventive measures have been developed so far. Thus, we propose a novel strategy using a tantalum (Ta) and carbon (C) co-modification to improve the chemical stability of titanium carbide (TiC)-based coatings (Cr/Ta/TiC/C). During the film growth, the subjacent Ta atoms were thermally diffused throughout the columnar structure of TiC and reacted with the C layer. The reaction product, i.e., TaC, acted as a chemical passivator to the grain boundary. Combined with the C capping layer, these functional layers synergistically suppressed any localized corrosion. Therefore, corrosion current densities within the United States Department of Energy’s technical recommendations were achieved in both potentiostatic and potentiodynamic polarization. Meanwhile, by controlling the Ta metal dispersion, the interfacial contact resistance between the multilayer structure and the carbon paper can be reduced to 7.1 mΩ·cm−2 at a compaction force of 140 N·cm−2. The substantial improvement in the corrosion resistance and conductivity of BPP places our work among the most efficient anticorrosion systems in PEMFC applications reported so far.

Laser surface treatment of pure titanium: Microstructural analysis, wear properties, and corrosion behavior of titanium carbide coatings in Hank's physiological solution

Titanium exhibits poor mechanical features such as low hardness and wear resistance. In this research, we considerably enhance the hardness and wear resistance of Ti by a simple laser surface treatment method. Titanium carbide (TiC) structure was successfully generated on Ti samples by means of laser. Vickers hardness indenter, wear test, impedance spectroscopy, and polarization analyses were carried out to scrutinize the mechanical and corrosion properties of samples. Adhesion between Ti and the formed TiC structure is favorite aspect of this method. The results confirmed that the TiC layer improved the mechanical hardness of the Ti. Additionally, the friction coefficient values of laser-treated Ti samples dramatically decreased. The surface roughness of laser-treated Ti declined to its minimum value with increase in laser-treatment time. Although, laser-surface treatment of Ti did not make an evident change in the corrosion resistance of Ti in Hank's physiological solution compared to reference Ti, the escalation of Ti hardness with laser-treatment time is a favorable aspect of this method.

Effect of Ni addition on the densification of TiC: A comparative study of conventional and microwave sintering

This study deals with the effect of conventional sintering and microwave sintering on the densification kinetics of Titanium Carbide (TiC) in the presence of Ni (1, 1.5, 2 wt%). TiC compacts were obtained after uniaxial pressing of powders synthesised by ball milling of Titanium and Carbon and sintering was done in the presence of Nickel. The samples prepared were subjected to conventional as well as microwave sintering. The XRD and SEM analysis were used for a study of the reaction of Ti and C powders upon addition of Ni, which reduced the sintering temperature to 1200 °C. The densification of TiC powders was due to the Ti-Ni eutectic system, the liquid phase formed at this temperature assisting the sintering process. The SEM images revealed the flake like structure of TiC in which the carbon diffused into Ti upon the addition of Ni, thereby supporting enhanced mass transfer. The XRD pattern showed the presence of Titanium Oxide (TiO2) along with TiC which resulted in non-uniform distribution of hardness. Maximum hardness was achieved in the conventional sintered compacts which gradually increased with increase in Ni addition. The presence of the oxide phase and the formation of micro cracks resulted in non-uniform hardness for microwave sintered compacts. The maximum hardness of conventional sintered compact (375 HLD) was nearly 1.5 times more than the maximum hardness of the microwave sintered compact (250 HLD). The density of the microwave sintered compact was found to be higher by 8% than with the conventionally sintered compact.

Phase Composition and Structure of Titanium Carbide/Nickel Binder Synthesis Products

We have studied the phase composition and structure of titanium carbide with a nickel binder prepared by self-propagating high-temperature synthesis in a cocurrent inert or reactive gas stream using granulated mixtures containing different grades of titanium. The results demonstrate that, unlike in the case of powder mixtures with a loose bulk density, the products of combustion of a granulated Ti + C + 25% Ni mixture in flowing nitrogen or without it retain their structure and granule size and can readily be ground into powder. In the case of the powder mixture both in a flowing gas and without it and in the case of the granulated mixture in flowing argon, the combustion products have the form of unbreakable sinter cakes, independent of the grade of titanium. Microstructural analysis of the combustion products points to spontaneous dispersion of the titanium particles surrounded by the nickel binder, independent of the starting mixture (granules or powder with a loose bulk density). Moreover, the phase composition of the synthesis products depends on the size and morphology of the titanium particles. In the case of PTM titanium, the final synthesis product consists of titanium carbide and nickel phases. After the combustion of mixtures based on PTM-1 titanium powder or a 50% PTM + 50% PTM-1 mixture, the final product consists of TiC, Ni, and TixNiy intermetallic phases. Synthesis in flowing nitrogen has been shown to change the phase composition of the combustion products of the mixtures based on PTM-1 titanium powder and a 50% PTM + 50% PTM-1 mixture, causing the intermetallic phases to disappear. To account for the combustion behavior of the mixtures, we have proposed a two-step mechanism of interaction in the Ti + C + 25% Ni system.

Understanding the correlation between the electronic structure and catalytic behavior of TiC(001) and TiN(001) surfaces: DFT study

Spin-unrestricted density functional theory (DFT) calculations are performed to explore the electronic structure and water-gas shift (WGS) behavior for the non-polar (001) surface of both titanium carbide (TiC) and titanium nitride (TiN). Previous researches have suggested that the unique electronic structures of these materials can effectively explain their surface adsorption and reactivity. Herein, our DFT calculations demonstrate that TiC(001) surface with occupied nonmetal C-2p states strongly binds CO molecule to the carbon site, and subsequently mediates the WGS along an associative mechanism. In contrast, TiN(001) surface dominated by metal Ti-3d states prefers to adsorb CO molecule at the titanium site, and then mediates WGS reaction through a redox mechanism. This indicates that the surface behavior of TiC(001) and TiN(001) is strongly dependent on their own electronic structure as expected. Therefore, the present studies provide an interesting perspective to understand the correlation between the electronic structure and catalytic behavior of such materials.

Formation of titanium carbide on the titanium surface using laser ablation in n-heptane and investigating its corrosion resistance

Laser ablation of titanium in liquid (LAL) using a fiber laser was studied. Firstly, LAL was carried out in toluene, n-hexane, n-heptane, and acetone as liquid media at the same irradiation conditions. Samples were characterized by different diagnostic techniques X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray spectroscopy (EDS). It was found that titanium carbide (TiC) structure has been generated on the surface of laser ablated samples in toluene, n-hexane, and n-heptane. Also, titanium dioxide was formed on the surface of laser ablated sample in acetone along with TiC. After that, n-heptane was chosen as the adequate liquid medium. LAL process was repeated in n-heptane for different ablation process times at the same irradiation conditions. Samples were investigated by XRD, Raman spectroscopy, EDS, nuclear reaction analysis (NRA), and cross sectional FESEM. It was concluded that the ablation process time of about 30 s is threshold time to form detectable TiC structure by XRD. Additionally, it was deduced that the amount of the carbon (in two forms of amorphous and carbidic) on the surface of the irradiated titanium for about 2 min (S8 sample) is more than the other samples. The corrosion behavior of samples was studied by electrochemical impedance spectrometry (EIS) tests. The EIS plots obtained after 24, 48, 72, and 96 h immersion time showed the corrosion resistance of S8 sample enhancement in Ringer's solution compared with the other samples, and the corrosion resistance of this sample increased by rising the immersion time up to 96 h.

Ab Initio Modeling of Boron Impurities Influence on the Electronic and Atomic Structure of Titanium Carbide

Ab Initio Modeling of Boron Impurities Influence on the Electronic and Atomic Structure of Titanium Carbide

Evaluation of Titanium Carbide Thin Film Coatings on Surface Microstructure Controlled WC-Co

Chemical vapor deposited (CVD) or physical vapor deposited (PVD) hard coating technique is widely used the cemented-tungsten carbide (WC-Co) for molds and cutting tools, which plays an important role in a lot of manufacturing industry. For example, titanium carbide (TiC), titanium nitride (TiN) and titanium carbonitride (TiCN) is one of the candidates to control surface properties in order to increase lifetime or to decrease friction coefficient of molds, tools and so on. The film prepared by thermal CVD carried out around 1000°C has good uniformity and mechanical properties, which restricts substrates having low melting points, and also causes deformation of substrates. High temperature sometimes results in decarbonization of WC-Co surface which causes a significant decrease in toughness and transverse rupture strength. Plasma enhanced chemical vapor deposition (PECVD) or PVD has some merits as lower deposition temperature (< 500°C) than thermal CVD and high through-put, however, the film usually has low adhesion strength. Then, life of molds and cutting tools obtained PVD are sometimes shorter than that with CVD. In this study, Several surface pretreatment methods were investigated to remove Co from the WC-Co surface and to increase surface roughness to enhance adhesion strength. The procedure include, Dry etching by CF4 plasma for 15 to 120min in the substrate temperature range from R.T. to 500°C. Chemical treatment with aqua regia (3HCl:HNO3) for 5 min at 25 to 60°C. After pretreatment, TiC coatings were formed by sputtering with TiC target or by PECVD from TiCl4/CH4. Surface roughness was evaluated by AFM. Crystallographic structure of WC-Co and TiC was evaluated by XRD. Hardness was evaluated by dynamic nanoindenter. Atomic concentration was determined by XPS. Figure 1 shows maximum height roughness (Rz) and arithmetic average roughness (Ra) of WC-Co substrates after pretreatment. Rz and Ra got larger as increasing temperature of treatment conditions. In particular, substrate surface with aqua regia treatment at 60°C disappear Co peak. Scratch test for PVD TiC coating on pretreated substrate revealed that critical load was larger than that with the film on non-pretreated substrate. When Ra was 150 nm, critical load was over 30N. The pretreated substrates surface by CF4 plasma and aqua regia have similar Ra value as 150 nm, however, the film with CF4 plasma exhibited no delamination and the film aqua regia exhibited delamination. The opposite trend could be due to the micro-level morphologies. The differences between PVD and CVD films will be discussed. Figure 1

A new method of fabrication of TiC by employing pyrolytic carbon black and titanium

A new method to synthesize titanium carbide (TiC) from polysiloxanes and titanium (Ti) by employing an in situ reaction is presented. The factors, such as, the annealing temperature and Ti particle size, were found to play a significant effect on the phase composition, structure, thermal behavior, and textural morphology of as-prepared TiC. Moreover, the relative intensity ratio (RIR) method was applied to evaluate the phase purity of TiC. Results demonstrated that the phase purity of the TiC prepared at 1400°C for 2h under the argon atmosphere is approximately up to 100%, confirming the feasibility of the presented new method.

Physical Properties of (TiC/Polypropylene) Conductive Composites in Relation to Their Particle-filled Structures

Titanium carbide (TiC) ⁄ acid-modified polypropylene (m-PP) composite is one of the candidate as the PTC resistor stable in relatively high temperatures, which is utilized for a self-recoverable element protecting from over currents in many kinds of electrical circuits. In the present study, the m-PP-based composites containing various volume fraction (φ2) of TiC have been prepared; then, their viscoelastic characteristics were investigated in comparison with their electric conductivity as a function of temperature. Melting behaviors of the samples were also examined and discussed in terms of their morphological features. Alternatively, the changes in the storage moduli at room temperature with various φ2 values of the samples could be expressed by a modified Kerner equation with the maximum φ2 value of 0.69. When the value of φ2 exceeded up to be 0.36, the resistivities of the sample decreased steeply with increasing φ2 values. The filling structure of TiC⁄m-PP Composites is expected to be in random packing systems.

High temperature plasticity of titanium carbide in the low area of homogeneity

This paper deals with the study of structural and mechanical properties of a ceramic material which is composed on the basis of nonstoichiometric titanium carbide in the low area of homogeneity. Material for the investigation was produced by means of self-propagating high temperature synthesis (SHS) with subsequent high effort compaction. It was established that under tensile and compression straining the material had unusually high plasticity at temperatures above the toughbrittle transition (TBT) temperature. The strain rate and stress pattern strongly affect the TBT temperature. Optical and scanning electron microscopy as well as x-ray structural and energy dispersion analysis helped to establish the regularities of titanium carbide structure evolution under various conditions of sample deformation.

Band structure of titanium carbide containing nitrogen and oxygen impurities

Abstract Using the Green's function method the band structure of titanium carbide containing isolated nitrogen and oxygen impurity atoms has been calculated in the ASA-KKR approximation. The dependence of the local electronic distributions of impurity centres on the nature of the latter and on the band structure of the matrix is discussed. The results are compared with X-ray emission spectra of titanium carbonitrides and oxycarbides.

Predicting irradiation-induced changes in the electrophysical properties and zonal structure of titanium carbide

Predicting irradiation-induced changes in the electrophysical properties and zonal structure of titanium carbide

Valence-band structure of TiC and TiN

The valence-band structure of single crystals of titanium carbide (TiC) and titanium nitride (TiN) have been studied with angle-integrated photoelectron spectroscopy using ${\mathrm{He}}_{\mathrm{I}}$, ${\mathrm{He}}_{\mathrm{II}}$, and synchrotron radiation for excitation. The results are compared with the partial densities of states derived from an augmented-plane-wave band-structure calculation. Peak positions and widths agree fairly well, but the observed intensity modulations with photon energy cannot be interpreted by such a comparison.

Use of X-rays to study the atomic scattering factors of the components of titanium carbide and the defect concentration of its structure

1. It is found that, for sin θ/λ≤0.6, the atomic scattering factors of Ti and C in titanium carbide differ from the corresponding quantities for neutral atoms. These deviations are apparently due to changes in the state of the Ti and C atoms, accompanying the formation of the titanium carbide structure. 2. The defect concentration of the TiC structure, calculated from experimental data measured with sin θ/λ ≥0.65, agrees with the chemical analysis results.