Properties Of TiC Research Articles

Pressure-induced effects on elastic and mechanical properties of TiC and TiN: A DFT study

Pressure-induced effects on elastic, structural phase transition and mechanical properties of TiC and TiN are studied under high pressures from first-principle calculations. Calculated lattice parameters, elastic constants and theoretical Vickers hardness are in excellent agreement with available experimental and theoretical results. The transition pressure from NaCl to CsCl phase is determined with values of 5.695 Mbar for TiC and 3.482 Mbar for TiN. Pressure-induced effects on mechanical properties of NaCl-type TiC and TiN show that the Vickers hardness increases first, to a maximum value 43.65 and 27.48 GPa at the pressure of 2.1 and 0.9 Mbar for NaCl-type TiC and TiN, respectively, and then decreases with increasing pressure.

First-Principles Study of TiC(111) Surface

The structural and electronic properties of TiC(111) surfaces are calculated using the first-principles total-energy plane-wave pseudopotential method based on density functional theory. As a polar surface, (111) surface shows large charge depletion in the upper part of the atoms, while charge accumulation happens in the inferior part of the atoms, interlayer Ti-C chemical bonds are reinforced and the outermost interlayer distances are largely reduced. Meanwhile, the charge accumulation and depletion for Ti-terminated surface is more than that for C-terminated surface on the same position of the two slabs after full relaxation. The surface energy of C-terminated surface is in the range from 7.61 to 9.83 J/m2, much larger than that of Ti-terminated surface from 3.13 to 1.35 J/m2, and the Ti-terminated surface is thermodynamically more favorable over all of the range of (chemical potential of TiC slab). This present work makes a beneficial attempt at exploring TiC surface as an ab initio method for studying possible nucleation mechanism of Aluminum on it.

Effects of Process Parameters on Microstructure and Properties of TiC Reinforced Cu-Matrix Composites

TiC/Cu composites were prepared by means of high-energy ball mill and cold-press sintering. Confirming the better process parameters, the effects of the milling time and sintered temperature on microstructure, mechanical properties and electric conductivity of TiC/Cu composites was discussed. The shape of the composite grains changed from laminar to spherical and lattice distortion increased with the milling time increasing. The increase of the sintering temperature and TiC contents help to decrease porosity and density of the composites. With increasing of TiC mass fraction the bend strength increased first and then decreased，the peaks both appear in 10wt. %. The increasing of the sintering temperature is beneficial to improve the bend strength. Ball milled 15h the electric conductivity performs at optimum level. When the milling reached 24h, fine particles appear agglomeration and it shows a low level of the electric conductivity.

Microstructure transformation and mechanical properties of TiC–TiB2 ceramics prepared by combustion synthesis in high gravity field

By conducting combustion synthesis in high-gravity field, the solidified TiC–TiB2 with a series of TiB2 mole content were prepared through adjusting the mole ratio of C and B elements in combustion system. XRD, FESEM and EDS results showed that with increasing TiB2 mole content, the matrix of TiC–TiB2 composite ceramics transformed a number of fine TiB2 platelets from the TiC spherical grains, and fine-grained even ultrafine-grained microstructures were achieved in solidified TiC–50%TiB2 due to the coupled quasi-eutectic growth under rapid solidification of the ceramic. Properties showed that relative density, Vickers hardness and flexural strength of TiC–50%TiB2 simultaneously reached the maximum values of 98.7%, 21.5±1.5GPa and 860±35 MPa, whereas the maximum fracture toughness of 13.5±1.5MPam0.5 was achieved in TiC–66.7%TiB2. FESEM fractography analyses of the solidified ceramics indicated that the highest flexural strength achieved in TiC–50%TiB2 benefits from not only the lowest content of Al2O3 inclusions and Cr–W–Ti borides, but also the achievements of fine-grained microstructure in the near-full-density ceramic and high fracture toughness contributed from a intensive coupled mechanism of crack deflection, crack-bridging and pull-out by a large number of fine TiB2 platelets.

In Situ Synthesis, Microstructure, and Properties of TiC and (Ti,W)C-Reinforced Fe-Mn-Al Austenitic Steel Matrix Composites

In situ synthesis, microstructures, and properties of 10 vol.% TiC and (Ti,W)C-reinforced Fe-Mn-Al austenitic steel matrix composites have been reported in this paper. The microstructure of the prepared samples has been characterized by using scanning electron microscopy and X-ray diffraction technique. The abrasion wear resistance and mechanical properties such as hardness and impact energy of both the composites as well as the unreinforced Fe-Mn-Al austenitic steel have been evaluated. The (Ti,W)C-reinforced composite has higher impact energy and slightly lower hardness values compared to that of TiC-reinforced composite. The TiC-reinforced composite exhibits the best abrasive wear resistance of all the materials tested.

Elastic and thermo-physical properties of TiC, TiN, and their intermediate composition alloys using ab initio calculations

The equilibrium lattice parameters, elastic properties, material brittleness, heat capacities, and thermal expansion coefficients of TiC, TiN, and their intermediate composition alloys (Ti(C1−xNx), x=0.25, 0.5, and 0.75) were calculated using ab initio density functional theory (DFT) methods. We employed the Debye–Gruneisen model to calculate a finite temperature heat capacity and thermal expansion coefficient. The calculated elastic moduli and thermal expansion coefficients agreed well with the experimental data and with other DFT calculations. Accurate heat capacities of TiC, TiN, and their intermediate composition alloys were obtained by calculating not only the phonon contributions but also the electron contributions to the heat capacity. Our calculations indicated that the heat capacity differences between each composition originated mainly from the electronic contributions.

First-principle calculations of elastic, electronic and thermodynamic properties of TiC under high pressure

First-principle investigations of the elastic, electronic and thermodynamic properties of TiC in NaCl structure under high pressure are conducted by using the plane-wave pseudopotential method and quasi-harmonic Debye model. The obtained lattice parameters, elastic constants and moduli at p=0 GPa and T=0 K are in very good agreement with the available experimental data and other theoretical results. According to the analysis of the density of states, the Ti-C bond becomes stronger with pressure increasing. The values of bulk modulus, thermal expansion coefficient, Debye temperature, entropy, Grüneisen parameter and heat capacity (CV) at different pressures and temperatures are obtained successfully by using the quasi-harmonic Debye model. The influence of pressure on bulk modulus, thermal expansion parameter and Debye temperature is greater than that of temperature. The CV decreases with the increase of pressure under the same temperature and tends to the Dulong-Petit limit at high temperature.

First-principles study of TiC(110) surface

The structural and electronic properties of TiC(110) surfaces are calculated using the first-principles total-energy plane-wave pseudopotential method based on density functional theory. The calculated results of structural relaxation and surface energy for TiC(110) slab indicate that slab with 7 layers shows bulk-like characteristic interiors, and the changes of slab occur on the outmost three layers, which shows that the relaxation only influences the top three layers. Meanwhile, the strong Ti-C covalent bonding can be found in the distribution of charge density on the (100) plane. The interlayer Ti-C chemical bonds are reinforced and the outermost interlayer distance is reduced as a result of the charge depletion in the vacuum and the charge accumulations in the interlayer region between the first and second layers. The surface energy of TiC(110) is calculated to be 3.53 J/m2.

Enhancement of Ti-containing hydrogenated carbon (Ti[sbnd]C:H) films by high-power plasma-sputtering

Ti-containing amorphous hydrogenated carbon (TiC:H) thin films were deposited on stainless steel SS304 substrates by high-power pulsed magnetron sputtering (HPPMS) in an atmosphere of mixed Ar and C2H2 gases using titanium metal as the cathodic material. The multilayer structure of the deposited film had a TiTiCDLC gradient to improve adhesion and reduce residual stress. This study investigates the effects of substrate bias and target-to-substrate distance on the mechanical properties of TiC:H films. Film properties, including composition, morphology, microstructure, mechanical, and tribology, were examined by glow discharge spectroscopy (GDS), scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, and a nanoindenter and a pin-on-disk tribometer. Experiments revealed impressive results.

Influence of Zr and O on the structure and properties of TiC(N) coatings deposited by magnetron sputtering of composite TiC 0.5 + ZrO 2 and (Ti, Zr)C 0.5 + ZrO 2 targets

The effect of Zr and O incorporation on the structure and properties of TiC(N) coatings deposited by DC magnetron sputtering of composite TiC 0.5 + xZrO 2 ( x = 10 and 20 wt.%) and (Ti,Zr)C 0.5 + 10%ZrO 2 targets in an argon atmosphere or reactively in a gaseous mixture of Ar + N 2 is presented. The structure, elemental and phase composition of the coatings were studied by means of X-ray diffraction, scanning electron microscopy, and glow discharge optical emission spectroscopy. The coatings were characterized in terms of their hardness, elastic modulus, and elastic recovery using the load–depth-sensing nanoindentation method. Tribological properties were investigated using ball-on-disk tests against cemented carbide at 25 °C and alumina in the temperature range of 25–500 °C. To evaluate the oxidation resistance, the coatings were annealed in air at 400, 550, and 600 °C for 1 h. The obtained results show that the TiZrCO(N) coatings exhibit a peak hardness versus nitrogen partial pressure. The coatings with maximum hardness tested at room temperature against WC + Co and Al 2O 3 counterparts showed low friction coefficients below 0.25. At higher temperatures 300–500 °C, the friction coefficient against an Al 2O 3 ball was recorded to be 0.6. The tribological tests of the coatings demonstrated their high wear resistance at moderate temperatures 25–300 °C (wear rate, k ~ 10 − 6 mm 3N − 1 m − 1 ). Moreover, the coatings with high Zr content were the most wear resistant. The oxidation resistance of the Zr-doped TiCON coatings was not as high as expected and restricted by 600 °C. The combination of high hardness about 40 GPa with low friction coefficient and superior wear resistance makes the TiZrCON coatings promising candidates for various dry tribological applications.

Improved tribological properties of TiC with porous nanostructured TiO 2 intermediate layer

The mismatch in the thermal expansion coefficients between TiC coatings and steel substrates and residual stress in the TiC degrade the tribological properties. In this work, a porous nanostructured TiO 2 coating is deposited as an intermediate layer on hot-work steel (H 11) before final deposition of the TiC film. This intermediate layer is expected to reduce the interfacial energy, decreases the thermal mismatch between TiC and steel, and improves the tribological properties. Grazing incidence X-ray diffraction (GIXRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and pin-on-disk are used to study the structure as well as tribological properties such as friction, wear, and hardness. Our results reveal that the porous TiO 2 interlayer improves the friction, wear, hardness, and elastic modulus of the system.

Effect of SPS process sintering on the microstructure and mechanical properties of nanocrystalline TiC for tools application

The most important spark plasma sintering (SPS) parameters (Temperature, holding time and pressure), have been reviewed to assess their effect on the densification, grain growth kinetics and mechanical properties of nanocrystalline TiC synthesized by mechanical alloying. Experiments were performed in the 1350–1800 °C temperature range with holding time from 1 to 10 min under various pressure values of 50, 80 and 100 MPa. The results of experiments revealed that the mechanical properties of the material were improved with raising the sintering temperature and extending the sintering time. However, a hardness decrease was observed as a result of abnormal grain growth under higher sintering temperatures. The optimized process parameters for SPS process are identified as a sintering temperature of 1650 °C, a pressure 100 MPa and a sintering time of 5 min. The resulting mechanical properties are: a relative density of 97.9%, a micro-hardness of 2570 Hv, a nano-hardness of 28 GPa, a fracture toughness of 4.9 MPa·m 1/2 and a compressive strength of about 2210 MPa.

Electronic structure and elastic constants of TiC xN 1− x, Zr xNb 1− xC and HfC xN 1− x alloys: A first-principles study

The structural, electronic and elastic properties of TiC x N 1− x , Zr x Nb 1− x C and HfC x N 1− x alloys have been investigated by using the plane-wave pseudopotential method within the density-functional theory. The calculations indicate that the variations of the equilibrium lattice constants and bulk modulus with the composition are found to be linear. The calculated elastic constants C 44 and shear constants as a function of alloy concentration reveal the anisotropic hardness of these compounds. The partial and total density of states (DOS) for the binary and ternary compounds had been obtained, and the metallic behavior of these alloys had been confirmed by the analysis of DOS.

An atomistic study of thermal conductance across a metal-graphene nanoribbon interface

This paper presents an atomistic Green’s function study of phonon transport through a heterogeneous interface between bulk TiC substrates and graphene nanoribbons (GNRs). The force constants that govern the lattice dynamical equations are obtained from first-principles density functional theory (DFT) calculations and then optimized for the Green’s function formulation. Phonon vibrational properties of TiC and GNRs are investigated by lattice dynamics calculations with optimized force constants that correlate well to direct DFT results. Thermal conductances of TiC-GNR-TiC systems are studied together with TiC-GNR structures. The conductances of TiC-GNR interfaces are normalized by ribbon width and are found to converge. The converged value is used to estimate the interface resistance of multiwalled carbon nanotubes (MWCNTs) grown on metal catalyst support substrates and is found to be consistent in an order of magnitude sense with experimental results on MWCNT arrays. The results reveal that covalent bonds may be formed during CNT synthesis and quantify the resulting thermal impedance caused by phonon mismatch.

Structural, elastic and electronic properties of transition metal carbides TMC (TM=Ti, Zr, Hf and Ta) from first-principles calculations

The structural, elastic and electronic properties of TiC, ZrC, HfC and TaC have been investigated by first-principles calculations using the plane-wave pseudopotential method. Different exchange–correlation functionals regarding the local density approximation and the PBE, RPBE and PW91 forms of generalized gradient approximation are taken into account. The NaCl-type cubic structures of TMC (TM=Ti, Zr, Hf and Ta) are optimized and confirmed to be mechanically stable. The elastic properties such as the elastic constants, bulk modulus, shear modulus, Young’s modulus and Poisson’s ratio of TMC are investigated, and the performances of LDA and GGA are discussed. The electronic density of state, electron charge density and Mulliken population analysis have been explored to discuss the electronic properties and bonding behaviors of TMC. The present calculation results compare satisfactorily with the experimental data and previous theoretical calculations.

Consolidation of Binderless Nanostructured TiC by Pulsed Current Activated Sintering and Its Mechanical Properties

A dense nanostructured TiC with a relative density of up to 98% was produced with simultaneous application of 80 MPa pressure and pulsed current of 2800 A using the nanopowder of TiC. The effect of the ball milling times on the sintering behavior, grain size and mechanical properties of binderless TiC was investigated.

First-principles study of the structural, vibrational, phonon and thermodynamic properties of transition metal carbides TMC ( [formula omitted], Zr and Hf)

The structural, vibrational, phonon and thermodynamic properties of TiC, ZrC and HfC have been investigated by first-principles calculations using the plane-wave pseudopotential method. The NaCl-type FCC structures are optimized and confirmed to be dynamically stable for these compounds. The vibrational modes at the Γ point are analyzed using group theory for the studied carbides. The lattice dynamical results regarding the phonon dispersion curves, phonon density of states and thermodynamic properties are reported within the framework of density functional perturbation theory. It is shown that these compounds exhibit similar but slightly different behaviors for the phonon related properties, which is expected because the transition metal atoms are in the same IV b group. The present calculation results compare satisfactorily to experimental and existing literature results.

High temperature behaviour of TiC particulate reinforced 304 stainless steel by in situ reaction and electroslag remelting

The microstructure, creep and oxidation properties of TiC particulate reinforced 304 stainless steels prepared using a new developed technology have been investigated. Experimental results show that small amounts of TiC addition to 304 stainless steel results in an increase in yield and tensile strength but a decrease in ductility over the temperature range 600–800°C. A reduction in strength occurs when excessive TiC is introduced. Creep properties of TiC reinforced steels are significantly higher than that of 304 stainless steel without TiC addition at temperatures between 700 and 800°C and under an applied stress of 55 MPa. Addition of TiC particles results in no breakaway oxidation, and a low oxidation rate is maintained in air at 850°C for 96 h oxidation, but oxidation resistance will significantly decrease if excessive TiC is added. In addition, adding TiC causes excellent spalling resistance.

Consolidation of binderless nanostructured titanium carbide by high-frequency induction heated sintering

The rapid sintering of nanostructured TiC hard materials in a short time was investigated with High-Frequency Induction Heating Sintering process. The advantage of this process is that it allows very quick densification to near theoretical density and prohibition of grain growth in nanostructured materials. A dense nanostructured TiC hard material with a relative density of up to 99% was produced with simultaneous application of 80 MPa pressure and induced current of output of total power capacity (15 kW) within 4 min. The effect of the ball milling times on the sintering behavior, grain size and mechanical properties of binderless TiC was investigated.

Comparison of mechanical and tribological properties of TiC–NiTi and TiC–[formula omitted]–NiTi coatings

NiTi can be used as a metallic matrix of a cermet (a composite of ceramic and metallic materials) to increase its durability and resistance. On the other hand, the TiC and TiB2 are hard ceramic materials that can be used to increase the wear resistance of the composite to which they belong. This study compares the mechanical adherence, tribological and corrosion properties of a cermet that has TiC or TiC–TiB2 and NiTi as a matrix. The friction coefficient and the mass loss as a function of time were obtained from the tribological tests and compared for the two types of coatings. The coatings were produced by thermal spraying onto a steel substrate. The coatings containing TiB2 showed lower adhesion and higher wear rates than the TiC coatings. This pattern may be attributable to the degradation of the TiB2 during the thermal spray process.