Growth kinetics of titanium carbide coating by molten salt synthesis process on graphite sheet surface

The synthesis of carbide coatings on graphite substrates using molten salt synthesis(MSS),has garnered significant interest due to its cost-effective nature.This study investigates the reaction process and growth kinetics involved in MSS,shedding light on key aspects of the process.The involvement of Ti powder through liquid-phase mass transfer is revealed,where the diffusion distance and quantity of Ti powder play a crucial role in determining the reaction rate by influencing the C content gradient on both sides of the carbide.Furthermore,the growth kinetics of the carbide coating are predominantly governed by the diffusion behavior of C within the carbide layer,rather than the chemical reaction rate.To analyze the kinetics,the thickness of the carbide layer is measured with respect to heat treatment time and temperature,unveiling a parabolic relationship within the temperature range of 700-1300℃.The estimated activation energy for the reaction is determined to be 179283 J·mol^(-1).These findings offer valuable insights into the synthesis of carbide coatings via MSS,facilitating their optimization and enhancing our understanding of their growth mechanisms and properties for various applications.

INVESTIGATION ON THE FORMATION MECHANISM OF TITANIUM CARBIDE PREPARED BY IN SITU REACTION IN MOLTEN ALUMINUM

A novel technique in which TiC particulate are prepared by an in situ reaction in molten aluminum was introduced for producing TiC/Al composite. In order to reveal the characteristics of the technique, the formation mechanism of TiC particulate prepared by this method was studied. Both theoretical and experimental results show that the TiC particulate is formed by a diffusion mechanism when the molar fraction of aluminum in the preforms is higher than 20.02%. On the contrary, the TiC particulate is formed by a solution-precipitation mechanism when the fraction of aluminum in the preforms is lower than 20.02%.

Synthesis of Titanium Carbide Particle in Laser Melted-pool in situ

The titanium carbide phase was synthesized in laser melted-pool in situ as the reinforced particles of nickel based composite coating on Ti-6Al-4V alloy surface using the nickel and graphite blending powder by laser cladding. The microstructure investigation showed that the petals-shaped particles and granular particles were two main morphology of titanium carbide particles. And a few spiral-shaped titanium carbide pattern and eutectic titanium carbide appeared on the cross-sections of the coating. The spiral-shaped titanium carbide pattern composed of some slender arc-shape titanium carbide particles and the eutectic titanium carbide was fine. The morphology and distribution of the spiral-shaped titanium carbide patterns and eutectic titanium carbide confirmed that their growth mechanism was the dissolution-precipitation mechanism and was affected by the convection behavior of the laser melted pool. The spiral-shaped titanium carbide pattern would precipitate out the high-temperature melts under high-speed convection. The eutectic titanium carbide would precipitate out when the melts stopped convection or dropped to eutectic temperature.

STUDY ON THE SURFACE OF TITANIUM CARBIDE PARTICLE PACKAGED NICKEL

Two kinds of packaged processes by nickel on the surface of titanium carbide particle are studied in this work. One is the chemical nickel-plating, the other is the organometallic compound decomposition. The composition, structure and morphology of the packaged powder were analyzed with XRD, DAT/TGA, SEM, EPMA etc. It has been shown that nickel was even dispersed on the surface of titanium carbide particle by the. two kinds of processes, deposited nickel exists as spherical particles of about 0.1 μm in diameter. The merits and demerits of the two kinds of processes have been compared, the organometallic copmound decomposition among them is a kind of hopeful method, which is not used by other researchers.

FATIGUE CRACK GROWTH FEATURE OF Fe-Cr-Ni MATRIX COMPOSITE REINFORCED BY TITANIUM CARBIDE PARTICULATE AT 1023K

The initiation and propagation of the short fatigue crack in a 10vol% titanium carbide particulate reichreed cast Fe-26Cr-14Ni mathe coopsite at 1023K were investigated.It is shown that the titanium carbide particulate may hinder the crack propagation and fatigue fracture of the composite. The relationships between fatigue crack propagation rate and stress intensity factor are da/dN=4.2×10-c(△K)4 for the matrix alloy and da/dN=1.4×10-19(△K)c for the composite. The fatigue thresholds of the composite and mathe alloy are 78 and 3.2MPa.m1/2, respectively. Microcracks initiate at the intedece between titanium carbide particulate and austenite and then propagate in carkide particles. The fracture sudece of the composite shows a distinct transition from wavy and serated cleavage near the threshold regime to striation-type splitting in the stable fatigue crack propagation stage and to a veined morphology characteristic in unstable rapid region.

Synthesis methods and powder quality of titanium monocarbide

Titanium monocarbide(TiC),which is the most stable titanium-based carbide,has attracted considerable interest in the fields of energy,catalysis,and structural materials due to its excellent properties.Synthesis of high-quality TiC powders with low cost and high efficiency is crucial for industrial applications;however major challenges face its realization.Herein,the methods for synthesizing TiC powders based on a reaction system are reviewed.This analysis is focused on the underlying mechanisms by which synthesis methods affect the quality of powders.Notably,strategies for improving the synthesis of highquality powders are analyzed from the perspective of enhancing heat and mass transfer processes.Furthermore,the critical issues,challenges,and development trends of the synthesis technology and application of high-quality TiC powder are discussed.

Ballistic performance of titanium-based layered composites made using blended elemental powder metallurgy and hot isostatic pressing

Metal matrix composites tiles based on Ti-6Al-4V(Ti64)alloy,reinforced with 10,20,and 40(vol%)of either TiC or TiB particles were made using press-and-sinter blended elemental powder metallurgy(BEPM)and then bonded together into 3-layer laminated plates using hot isostatic pressing(HIP).The laminates were ballistically tested and demonstrated superior performance.The microstructure and properties of the laminates were analyzed to determine the effect of the BEPM and HIP processing on the ballistic properties of the layered plates.The effect of porosity in sintered composites on further diffusion bonding of the plates during HIP is analyzed to understand the bonding features at the interfaces between different adjacent layers in the laminate.Exceptional ballistic performance of fabricated structures was explained by a significant reduction in the residual porosity of the BEPM products by their additional processing using HIP,which provides an unprecedented increase in the hardness of the layered composites.It is argued that the combination of the used two technologies,BEPM and HIP is principally complimentary for the materials in question with the abilities to solve the essential problems of each used individually.

A polyoxometalate-functionalized two-dimensional titanium carbide composite MXene for effective cancer theranostics

As a new family of two-dimensional （2D） nanomaterials, MXenes have recently attracted much attention because of high performance in versatile applications including energy storage and electrochemistry, but their specific application to biomedicine has been rarely reported, especially for theranostic nanomedicine, i.e., concurrent diagnostic imaging and therapy. This study shows for the first time surface engineering and functionalization of 2D Ti3C2 MXene nanosheets by the integration of GdWl0-based polyoxometalates （POMs）. These multifunctional GdWlo@Ti3C2 composite nanosheets provide hypertherrnal treatment with magnetic resonance （MR） and/or computed tomography （CT） imaging guidance toward tumor cells or xenografts. A tumor was effectively eradicated without further reoccurrence during the observation period. GdW10 nanoclusters that were integrated onto the surface of Ti3C2 nanosheets were demonstrated to serve as a contrast agent for contrast-enhanced CT and MR imaging based on their unique composition, thus showing the potential for diagnostic-imaging guidance and monitoring for tumor hyperthermia nanotherapy. The high in vivo biocompatibility of GdW10@TiaC2 composite nanosheets was demonstrated to guarantee their subsequent translation into a medical treatment. This study provides a novel strategy for broadening the biomedical applications of MXenes by surface engineering and multifunctionalization, which is expected to promote further exploration of biomedical applications of MXenes in nanotheranostics.

Two-dimensional titanium carbide MXenes as efficient non-noble metal electrocatalysts for oxygen reduction reaction

MXenes, a new family of multifunctional two dimensional(2D) solid crystals integrating high electroconductivity and rich surface chemistries, are promising candidates for electrolysis, which, however, have rarely been reported. Herein, free-standing ultrathin 2D MXene nanosheets were successfully fabricated from bulky and rigid MAX phase ceramics by liquid exfoliation with HF etching(delamination) and TPAOH intercalation(disintegration).The high oxygen reduction reaction(ORR) performance has been obtained, due to the extremely small thickness of the asfabricated Ti3C2 around 0.5–2.0 nm, equivalent to the dimensions of single-layer or double-layer Ti3C2 nanosheets in thickness. The ORR performance of the obtained Ti3C2 MXene-based catalyst exhibits desirable activity and stability in alkaline media. This study demonstrates the potential of earth-abundant 2D MXenes for constructing high-performance and cost-effective electrocatalysts.

Accordion-like titanium carbide(MXene) with high crystallinity as fast intercalative anode for high-rate lithium-ion capacitors

Two-dimensional transition-metal carbide materials,or MXenes,have attracted great attention in energy-related fields due to their excellent electrical conductivity,and large interlayer spacing.In this work,a simple method involving combustion synthesis and acid treatment to prepare accordion-like Ti3C2Tx MXene with open structure and high crystallinity,which is employed as anode materials in lithium-ion capacitors.Due to the improved ion diffusion and electron transportation of Ti3C2Tx anode,the mismatched electrode kinetics can be largely alleviated to acquire an enhanced power perfo rmance.The assembled Ti3C2Tx-based lithium-ion capacitors provides a maximum energy density of 106 Wh/kg and still exhibits a superior energy density of 79 Wh/kg even at a higher power density of 5.2 kW/kg,which provides a new platform for MXene materials with porous and crystalline features toward both high energy and power densities.

2D-titanium carbide(MXene)based selective electrochemical sensor for simultaneous detection of ascorbic acid,dopamine and uric acid

Two-dimensional(2 D)titanium carbide(MXene)nanosheets exhibited excellent conductivity,flexibility,high volumetric capacity,hydrophilic surface,thermal stability,etc.So,it has been exploited in various applications.Herein,we report synthesis of mixed phase 2 D MXene as a catalytic material for simultaneous detection of important biomolecules such as ascorbic acid(AA),dopamine(DA)and uric acid(UA).Crystalline structure,surface morphology and elemental composition of mixed phase titanium carbide(Ti-C-T_(x))MXene(T_(x)=-F,-OH,or-O)nanosheets were confirmed by X-ray diffraction(XRD),Raman spectroscopy,high-resolution transmission electron microscopy(HR-TEM),high-re solution scanning electron microscopy(HR-SEM)and Energy-dispersive X-ray spectroscopy(EDS)mapping analysis.Furthermore,Ti-C-T_(x) modified glassy carbon electrode(GCE)was prepared and its electrochemical properties are studied by cyclic voltammetry(CV)and diffe rential pulse voltammetry(DPV).It was found that Ti-C-T_(x) modified GCE(Ti-C-T_(x)/GCE)showed excellent electrocatalytic activity and separated oxidation peaks of important biomolecules such as AA(at 0.01 V),DA(at 0.21 V)and UA(at 0.33 V).Also,Ti-C-T_(x)/GCE sensor is enabled their simultaneous detection in physiological pH from 100 to 1000μM for AA,0.5-50μM for DA and 0.5-4μM&100-1500μM for UA.The limit of detection’s(LOD)was estimated as 4.6μM,0.06μM and 0.075μM for AA,DA and UA,respectively.Moreover,real sample analysis indicated that spiked AA,DA and UA can be determined accurately by Ti-C-T_(x)/GCE with the recovery ratio in the range between 100.5%-103%in human urine samples.The proposed Ti-C-T_(x) modified electrode exhibited good stability,selectivity and reproducibility as an electrochemical sensor for the detection of AA,DA and UA molecules.

Fabrication of porous titanium carbide ceramics by gelcasting process

Titanium carbide ceramics with high porosity were fabricated by gelcasting process with methacrylamide as a chain forming monomer,methylenebisacrylamide as a cross-linker monomer and tetramethylammonium hydroxide as a dispersant.The stability of suspension,mechanical properties,phase composition and micro structure were investigated by zeta potential,bending and compressive strengths,X-ray diffraction and scanning electron microscopy(TEM) analyses,respectively.The results show that the optimal concentration of dispersant for the best homogeneous unagglomerated microstructures is 0.4 wt%at pH 9.The highest green strength of 33 MPa is obtained from the suspension with 40 vol% solid loading and25 wt% monomer.The porosity increases with the increase in monomer content and the decrease in solid loading.Also,the strength of porous TiC ceramic decreases with the content of pores increasing in the sintered ceramics.

Effect of molybdenum on interfacial properties of titanium carbide reinforced Fe composite

This study shows that the mechanical strength of the composite of Fe matrix and titanium carbide(Ti C)ceramic particles is significantly enhanced with addition of molybdenum(Mo) atoms. Ti C reinforced Fe(Fe-0.2C-7Mn) composites with and without Mo were fabricated by a liquid pressing infiltration(LPI)process and the effect of Mo on interfacial properties of TiC–Fe composite was investigated using atomic probe tomography(APT) analysis, molecular dynamics(MD) simulations, first-principle density functional theory(DFT), and thermodynamic calculations. First, DFT calculations showed that total energies of the Mo-doped Ti C–Fe superlattices strongly depend on the position of Mo defects, and are minimized when the Mo atom is located at the TiC/Fe interface, supporting the probable formation of MoC-like interphase at the TiC/Fe interface region. Then, APT analysis confirmed the DFT predictions by finding that about6.5 wt.% Mo is incorporated in the Ti C–Fe(Mo) composite and that sub-micrometer thick(Ti,Mo)C interphase is indeed formed near the interface. The MD simulations show that Mo atoms migrate to the Mo-free TiC–Fe interface at elevated temperatures and the mechanical strength of the interface is considerably enhanced, which is in good agreement with experimental observations.

Co-construction of advanced sulfur host by implanting titanium carbide into Aspergillus niger spore carbon

It is of great importance to directionally construct advanced carbon host to achieve high-performance carbon/sulfur cathodes for lithium sulfur batteries(LSBs).Herein,we report a unique hollow pumpkinlike carbon with notable rich-wrinkle microstructure and intrinsically dual doping with N&P elements via a facile annealing process of Aspergillus niger spore.Furthermore,highly conductive polar absorbents,Ti C nanoparticles,are in situ implanted into the above Aspergillus niger spore carbon(ANSC)by carbothermal reaction,accordingly forming high-performance ANSC/TiC composite host for sulfur.Impressively,TiC nanoparticles play dual roles of not only pore formation in ANSC matrix but also enhancement of chemical absorption with polysulfides.With the positive synergistic effect between N&P co-doped ANSC matrix and Ti C polar absorbent,the designed ANSC/Ti C-S cathodes show unique advantages including larger accommodation space for sulfur,higher surface area,enhanced conductivity and better chemical absorption with soluble polysulfide intermediates.Consequently,the ANSC/Ti C-S cathodes are endowed with good rate performance(496 mAh/g at 0.5 C)and enhanced long-term cycling stability(736 mAh/g with a capacity retention of 78.8%at 0.1 C after 100 cycles).Our research opens a new door to controllably design advanced composite cathodes from microorganisms for application in lithium sulfur batteries.

Temperature Fluctuation Synthesis/Simultaneous Densification and Microstructure Control of Titanium Silicon Carbide (Ti_3SiC_2) Ceramics

A novel temperature fluctuation synthesis/simultaneous densification process was developed for the preparation of Ti3SiC2 bulk ceramics. In this process. Si is used as an in-situ liquid forming phase and it is favorable for both the solid-liquid synthesis and the densification of Ti3SiC2 rainies. The present work demonstrated that the temperature fluctuation synthesis/simultaneous densification process is one of the most effective and simple methods for the preparation of Ti3SiC2 bulk materials providing relatively low synthesis temperature. short reaction time; and simultaneous synthesis and densification. This work also showed the capability to control the microstructure, e.g., the preferred orientation, of the bulk Ti3SiC2 materials simply by applying the hot pressing pressure at different Stages of the temperature fluctuation process. And textured Ti3SiC2 bulk materials with {002} faces of laminated Ti3SiC2 grains normal to the hot pressing axis were prepared.

Interconnected microstructure and flexural behavior of Ti_(2)C-Ti composites with superior Young’s modulus

To enhance the Young’s modulus(E)and strength of titanium alloys,we designed titanium matrix composites with intercon-nected microstructure based on the Hashin-Shtrikman theory.According to the results,the in-situ reaction yielded an interconnected microstructure composed of Ti_(2)C particles when the Ti_(2)C content reached 50vol%.With widths of 10 and 230 nm,the intraparticle Ti lamellae in the prepared composite exhibited a bimodal size distribution due to precipitation and the unreacted Ti phase within the grown Ti_(2)C particles.The composites with interconnected microstructure attained superior properties,including E of 174.3 GPa and ultimate flexural strength of 1014 GPa.Compared with that of pure Ti,the E of the composite was increased by 55% due to the high Ti_(2)C content and interconnected microstructure.The outstanding strength resulted from the strong interfacial bonding,load-bearing capacity of interconnected Ti_(2)C particles,and bimodal intraparticle Ti lamellae,which minimized the average crack driving force.Interrupted flexural tests revealed preferential crack initiation along the{001}cleavage plane and grain boundary of Ti_(2)C in the region with the highest tensile stress.In addition,the propagation can be efficiently inhibited by interparticle Ti grains,which prevented the brittle fracture of the composites.

Microstructure and mechanical properties characterization of AA6061/TiC aluminum matrix composites synthesized by in situ reaction of silicon carbide and potassium fluotitanate

Aluminum alloys AA6061 reinforced with various amounts （0, 2.5% and 5%, mass fraction） of TiC particles were synthesized by the in situ reaction of inorganic salt K2TiF6 and ceramic particle SiC with molten aluminum. The casting was carried out at an elevated temperature and held for a longer duration to decompose SiC to release carbon atoms. X-ray diffraction patterns of the prepared AMCs clearly revealed the formation of TiC particles without the occurrence of any other intermetallic compounds. The microstructure of the prepared AA6061/TiC AMCs was studied using field emission scanning electron microscope （FESEM） and electron backscatter diffraction （EBSD）. The in situ formed TiC particles were characterized with homogeneous distribution, clear interface, good bonding and various shapes such as cubic, spherical and hexagonal. EBSD maps showed the grain refinement action of TiC particles on the produced composites. The formation of TiC particles boosted the microhardness and ultimate tensile strength （UTS） of the AMCs.

Synthesis of TiC Powder by Mechanical Alloying of Titanium and Asphalt

Abstract TiC powder was synthesized by mechanical alloying of titanium and asphalt in this paper. Deoiled asphalt as a carbon source not only provided element C in the fabrication of TiC but also cracked itself by the mechanical alloying process. The results of X-ray diffraction demonstrated the synthesis of cubic TiC. Gas phase chromatography showed that the discharged gas was composed of low molecular weight hydrocarbons, including H2, CH4 and C2H6. The formation mechanism of titanium carbide by mechanical alloying, and the thermodynamic and kinetics were discussed. These results showed that mechanical alloying is a promising method to prepare TiC and to crack asphalt with some light fraction byproducts.

Low Temperature Preparation of Carbide Coated Carbon for Refractory Castable Applications

Titanium carbide （ TiC ） coated graphite flakes （GF） and carbon black （CB） powders were prepared at relatively low temperatures （ 750 - 950 ℃ ） using a no- vel molten salt synthesis technique. The in-situ formed TiC coatings were homogeneous and crack-free and their thicknesses could be readily controlled/tailored by simply adjusting the Ti/C ratio. Compared to their uncoated counterparts, as prepared TiC coated GF and CB showed much improved water-wettability/dispersivity and rheological properties, and thus could be potentially used to prepare carbon-containing refractory castables.

Effect of Titanium Content on Microstructure and Wear Resistance of Hardfacing Alloy

The hardfacing alloys with different concentrations of titanium were deposited on carbon steel substrates by shielded metal arc welding, and the effect of titanium content on the microstructure characteristics of the hardfacing alloys was investigated. The wear resistance test of the hardfacing alloys was carried out by using a slurry rubber wheel abrasion test machine, and the wear behaviour was also studied. The results indicate that the addition of titanium can effectively promote the precipitation of the complex carbides of Nb and Ti due to the prior precipitation of titanium carbide which acts as nucleation sites for complex carbides. With the increase of titanium content, the wear resistance of the hardfacing alloys is increased gradually resulting from the refinement of microstructure and dispersive distribution of fine carbide precipitates. And the wear mechanism is mainly minimum plastic deformation with interrupted grooves due to the strengthening and protecting effects of carbide precipitates.