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.

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.

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.

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 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.

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.

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.

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.

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.

Preparation of TiC powders by carbothermal reduction method in vacuum

The preparation of fine TiC powders by carbothermal reduction of TiO2 in vacuum was investigated by XRD,SEM,XRF and laser particle sizer.Thermodynamic analysis indicates that it is easy to prepare TiC in vacuum and the formation sequence of products are Ti4O7（Magneli phase）,Ti3O5,Ti2O3,TiCxO1-x and TiC with the increase of reaction temperature.Experimental results demonstrate that TiC powders with single phase are obtained with molar ratio of TiO2 to C ranging from 1：3.2 to 1：6 at 1 550 ℃ for 4 h when the system pressure is 50 Pa,and TiC1.0 is gained when the molar ratio of TiO2 to C is 1：4 and 1：5.In addition,fine TiC1.0 powders（D50 equals 3.04 μm） with single phase and low impurities are obtained when the molar ratio of TiO2 to C is 1：4.SEM observation shows that uniform shape,low agglomeration,and loose structure are observed on the surface of block product.

Effects of TiC addition on properties of laser particle deposited WC-Co-Cr and WC-Ni coatings

The mechanisms by which titanium carbide （TiC） improves the properties of tungsten carbide （WC） coatings deposited on duplex stainless steels using laser particle injection technique were investigated. The relationships between laser process parameters and the synthesized composite were studied. The morphologies and microstructures of the feedstock powders and composite coatings were characterized using scanning electron microscopy （SEM） and energy dispersive X-ray spectroscopy （EDX） techniques. Surface hardness of the composite layers was determined using the Vickers microhardness tester while its corrosion behaviour in 3.5%NaCl solution was investigated by potentiodynamic polarization curve measurement method. As a result of the laser treatment, microstructures characterized by hard ceramic particles with strong bonding to substrate were formed on the surface layer of the steels. The addition of TiC to WC resulted in microstructures free from cracks, pores and intermetallics which could be detrimental to the properties of the composites. High microhardness was observed and most of the coatings shifted the corrosion potential to more noble values with the pseudo-passive curve.

MOF-derived molybdenum selenide on Ti_(3)C_(2)T_(x) with superior capacitive performance for lithium-ion capacitors

Two-dimensional Ti_(3)C_(2)T_(x) exhibits outstanding rate property and cycle performance in lithium-ion capacitors(LICs)due to its unique layered structure,excellent electronic conductivity,and high specific surface area.However,like graphene,Ti_(3)C_(2)T_(x) restacks during electrochemical cycling due to hydrogen bonding or van der Waals forces,leading to a decrease in the specific surface area and an increase in the diffusion distance of electrolyte ions between the interlayer of the material.Here,a transition metal selenide MoSe_(2) with a special three-stacked atomic layered structure,derived from metal-organic framework(MOF),is introduced into the Ti_(3)C_(2)T_(x) structure through a solvo-thermal method.The synergic effects of rapid Li+diffusion and pillaring effect from the MoSe_(2) and excellent conductivity from the Ti_(3)C_(2)T_(x) sheets endow the material with excellent electrochemical reaction kinetics and capacity.The composite Ti_(3)C_(2)T_(x)@MoSe_(2) material exhibits a high capacity over 300 mAh·g^(-1) at 150 mA·g^(-1) and excellent rate property with a specific capacity of 150 mAh·g^(-1) at 1500 mA·g^(-1).Addition-ally,the material shows a superior capacitive contribution of 86.0%at 2.0 mV·s^(-1) due to the fast electrochemical reactions.A Ti_(3)C_(2)T_(x)@MoSe_(2)//AC LIC device is also fabricated and exhibits stable cycle performance.

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.

Analysis of in situ Reaction and Pressureless Infiltration Process in Fabricating TiC/Mg Composites

An innovative processing route, in situ reaction combined with pressureless infiltration, was adopted to fabricate magnesium matrix composites, where the reinforcement TiC formed in situ from elemental Ti and C powders and molten Mg spontaneously infiltrated the preform of Ti and C. The influences of primarily elemental particle sizes, synthesizing temperature, holding time etc on in situ reactive infiltration for Mg-Ti-C system were systematically investigated in order to explore the mechanism of this process. In fabricating TiC/Mg composites, Mg can not only spontaneously infiltrate the preform of reinforcement and thus densify the as fabricated composites as matrix metal, but also it can accelerate the in situ reaction process and lower the synthesizing temperature of Ti and C as well. In situ reaction of Ti and C and Mg infiltration processes are essentially overlapping and interacting during fabrication of TiC/Mg composites. The mechanism proposed in this paper can be used to explain the formation and morphologies of the reinforcement phase TiC.

Kinetic study on carbothermic reduction of ilmenite with activated carbon

The carbothermic reduction of Panzhihua ilmenite with various additions of activated carbon was investigated byisothermal experiments over the temperature range of1373to1773K in the argon atmosphere.According to the reaction kineticsrecorded by the infrared gas analyzer,it was found that the amount of carbon addition had little influence on the reaction rates atvarious temperatures except1473K.When the reaction temperature was above the eutectic temperature of1427K of Fe?C binarysystem,part of carbon would dissolve into Fe to form a liquid phase,which made the liquid Fe as a diffusion channel of carbon todiffuse to the reaction interface.The carbothermic reduction above1573K obeyed the shrinking-core model.The mass fraction ofTiC could be determined by the standard addition technique.

Fabrication of AlN-TiC/Al composites by gas injection processing

The fabrication of AlN-TiC/Al composites by carbon- and nitrogen-containing gas injection into Al-Mg-Ti melts was studied. It was shown that AlN and TiC particles could be formed by the in situ reaction of mixture gas （N2 ＋ C2H2 ＋ NH3） with Al-Mg-Ti melts. The condition for the formation of AlN was that the treatment temperature must be higher than 1373 K, and the amounts of AlN and TiC increased with the increase of the treatment temperature and the gas injection time It was considered that AlN was formed by the direct reaction of Al with nitrogen-containing gas at the interface of the gas bubble and the melt. However, the mechanism of TiC formation is a combination mechanism of solution-precipitation and solid-liquid reaction.

MICROSTRUCTURE AND TENSILE PROPERTIES OF Fe_3Al-BASED ALLOYS WITH VC AND TiC ADDITIONS

Microstructure and tensile properties of Fe3 Al-based alloys with the additions of TiC and VC particles have been investigated. Results show that the formation of TiC particles results in the refinement of the macrostructure of as-cast ingots. Although the addition of VC particles does not cause any significant change of the as-cast microstructure, the microstructure of the alloy after hot-working and recrystallization has been found to be refined. The formation of both VC and TiC particles results in the increase of yield strength, especially at the high temperature of 600°C.

Synthesis of Ti_3SiC_2/TiB_2 Composite by In-situ Hot Pressing (HP) Method

Ti3SiC2/TiB2 composite was successfully obtained by hot pressing Ti/TiC/Si/B4C power mixtures.Volume fraction of TiB2 in Ti3SiC2/TiB2 composite can not exceed 10%.Incorporation of excessive TiB2 will affect the reactions process.TiC and Ti5Si3 were two important intermediate phases during the whole reactions.The microstructure characteristics of the Ti3SiC2/TiB2 composites were analyzed using scanning electron microscopy （SEM） and transmission electron microscopy （TEM）.The experimental results show that the grains of Ti3SiC2/TiB2 composite are structured in a layered form,and the formation of TiB2 particles as reinforcements with elongated or equiaxed shape distributes in Ti3SiC2 matrix.