Synthesis of Titanium Carbide by Means of Pressureless Sintering (original) (raw)
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Pressureless sintering of submicron titanium carbide powders
Ceramics International, 2017
Utilizing laboratory-synthesized submicron powders, monolithic titanium carbide (TiC) was sintered to a relative density of~95.7% through pressureless sintering (PS) at a temperature of 1700°C, which is at least~400°C lower than any other reported sintering temperatures. By comparing with commercial micron grade TiC, results indicate that the utilization of submicron carbide powders can enhance the sintering driving force, inhibit the grain and pore growth, and consequently accelerate the densification. The sample sintered at 1700°C has a relative density of~95.7%, fine microstructures with a grain size of~5.5 ± 0.7 µm, a moderate Vickers hardness of~20.3 ± 1.3 GPa, and a high flexural strength of~383.5 ± 20.5 MPa.
Titanium Carbide (TiC) Production by Mechanical Alloying
Powder Technology, 2018
This chapter presents the process for obtaining titanium carbides (TiC) from elemental powders of titanium dioxide, aluminum, and graphite by means of the mechanical alloying technique, using a semi-industrial attritor mill. Three grindings were performing: a wet, a dry, and a vacuum grinding. The mass relations between grinding elements and powders used were 20:1 to wet grinding and 40:1 to dry and vacuum grinding. Each grinding took 36 h with a control stop at 18 h. The samples were analyzed using X-ray diffraction analysis and the characteristics peak were detected on 2θ = 41, 60, 72, and 76°. Targets of TiC were produced using compaction and sintering processes. The particle size (between 200 nm and 1 μm) was measure using a scanning electron microscopy (SEM). After the milling process, the particle size showed a huge distribution. However, after the sintered process, the particle size (lower than 5 μm) distribution had a low dispersion and their shape trends to be spherical. It is necessary to highlight that the precursors used were low cost compared to the high cost and purity powders used for this purpose; so this method is an excellent alternative to implement as a low-cost industrial process.
Reactive processing of titanium carbide with titanium
Journal of Materials Science, 1984
The reactive sintering of titanium carbide with titanium metal was studied using mechanical mixtures of fine-grained powders heated in vacuum above the TiC-Ti eutectic temperature. Mixtures with bulk compositions of TiCo.94 to TIC0.63 yielded nonstoichiometric carbide with less than 0.5 wt % residual titanium metal after sintering, while residual metal was observed at higher titanium concentrations. The effects of time, temperature, and composition on Mohs hardness, final porosity and final grain-size were determined using a Box-Wilson experimental design. The experimental ranges studied were sintering times of 10 to 100 min, sintering temperatures of 1650 to 1850 ~ C, and compositions from TIC0.94 to TiCo.s8. Over these experimental ranges, the effects of time and temperature were small compared with those of composition. The Mobs hardness increased approximately linearly from two to nine with increasing percentage of titanium metal in the starting powder. The average grain size ranged from 15 to 70/~m, increasing with increasing time and temperature. For bulk compositions TiCo.94 to TiCo.7o grain growth was largely due to the conversion of titanium to substoichiometric carbide which grows epitaxially on the carbide grains. Substantial grain growth occurred for higher metal concentrations. The open porosity decreased from 28% to 16% as the amount of titanium metal in the starting powders was increased. Both the grain growth and the densification during reactive sintering of titanium-titanium-carbide mixtures were analysed in terms of a sintering model adapted from Kuczynski. A factor which empirically describes the behaviour of the system over a range of compositions was incorporated into the equations proposed by Kuczynski. Microstructural evidence and the activation energies for grain growth and densification all indicate that the rapid reaction between titanium metal and titanium carbide to form substoichiometric carbide occurs via shortcircuit diffusion of carbon out of the carbide grains along Ti2C platelets. Low sintered densities are attributed to the rapid formation of a solid titanium-carbide skeleton which prevents significant particle rearrangement in the eutectic liquid. Solution-precipitation processes do not appear to contribute significantly to the densification in this system.
Synthesis and Sintering of Tungsten and Titanium Carbide: A Parametric Study
Metals
The three primary steps in the production of tungsten carbide WC and titanium carbide TiC powders are the preparation of the green mixture, carbidization by furnace annealing, and ball milling of the annealed products. This work performed a comprehensive parametric investigation of these three steps. The impact of several factors was examined including the carbon precursor, the mass and diameter of the milling bodies (balls), the milling time and speed, the temperature and length of the annealing process, the height of the powder in the furnace boats, and the rate at which the furnace boats move. Regression models for every stage of the process were verified by 10-fold validation and used to optimize the synthesis sequence, resulting in high-quality WC and TiC with a grain size below 2 microns and a content of free carbon below 0.1%. Additionally, solid solution (W,Ti)C was fabricated by mechanochemical synthesis from the elemental mixtures; however, further modification of this tec...
Carbothermal synthesis of titanium carbide using ultrafine titania powders
Journal of Materials Science - J MATER SCI, 1997
The synthesis of titanium carbide (TiC) by the carbothermal reduction of carbon coated titanium dioxide (TiO2), a novel synthesis process, and titanium dioxide (TiO2) mixed with carbon black was investigated. A high surface area (64 m2g-1) TiO2 powder consisting of anatase and rutile phases was used for starting powders. The carbon coated method is a two-step process that utilizes a precursor derived from decomposing propylene (C3H6) and depositing carbon on the TiO2 particles. TiO2 powders were also mechanically mixed with carbon black for comparison. Both starting precursors and mixtures were reacted in a tube furnace for 2 and 4 h at temperatures of 1100°C to 1550°C under 1 l min-1 flowing argon. The TiC powders were characterized using thermogravimetric analysis (TGA), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analyser, chemical analysis (oxygen and carbon) and transmission electron microscopy (TEM). The carbon coating process provides high contact area ...
Titanium carbonitride (TiCN) based cermet has received extensive attention as important components substantially utilized in cutting tools, milling operations and in sliding bearings. Recently, conventional WC-Co based hard alloys are being replaced with TiCN based cermets accompanied with the trend of high speed machining. These materials are considered potential candidate for a variety of tribological applications. In this study, the effects of graphite additions on titanium carbonitride (TiCN) based cermet were investigated. This involved consolidation of TiC0.7TiN0.3 composition of pure TiCN based cermet and/with 0.5, 1.0 and 1.5 wt % graphite using spark plasma sintering (SPS). The comparative studies on the tribological behaviours of the TiCN based cermets with graphite additions were performed using ball on disc set up at ambient temperature. Results show that the presence of different composition of graphite influences the microstructures of TiCN. In addition, a change in wear response of the sintered compacts was observed. 1. Introduction Metal cutting industries persistently require materials with high temperature and good wear properties for high performance at extreme temperatures, in order to maximize productivity and reliability of the equipment. Titanium carbonitride (TiCN) based cermet as a ceramic-metal composite, gained enormous attention owing to its unique combination of properties such as high hardness, chemical inertness, low coefficient of friction, high temperature resistance and better wear resistance [1-10]. Compared to the performance of conventional cemented carbide (WC-Co) cutting tools, TiCN based cermet grant improved surface finishing, excellent chip/ tolerance control and allow geometrical accuracy of the work piece. Furthermore, TiCN based cermet, compares favourably to WC-Co in terms of performance and price. All these phenomenal mechanical properties are attributes of the hard phase composed within the cermet system [5-7].
A simple method of synthesis and surface purification of titanium carbide powder
International Journal of Refractory Metals and Hard Materials, 2013
A non-agglomerated submicron-sized titanium carbide powder has been synthesised in a simple combustion process with titanium tetrachloride and hexachloroethane as reactants, and with magnesium as a reducing agent. X-ray analysis of the purified product revealed that only the cubic titanium carbide phase is present. High-resolution transmission electron microscopy showed that TiC particles are coated with low-ordered carbon film on the surface. To remove free carbon, a melting process with calcium metal was used.
Sintering diagram of titanium carbide powders
Nanotechnologies in Russia, 2012
Sintering diagrams, which determine the dominating mechanism of powder sintering at a given temperature, the size of powder grains, and the neck between the grains, may be used to explain the experi ments on sintering and solve some practical problems concerning the sintering of metals and ceramics. In this work we have built sintering diagrams for titanium carbide powders of various dispersities. Using such dia grams, we have established that the dominating mechanisms of sintering titanium carbide micro and nanop owders are the surface and grain boundary diffusion of substance to the neck between the particles. It is found that the contribution of sintering basic mechanisms in the case of titanium carbide does not depend on the dispersity of powders.
Mechanochemical synthesis of nanostructured titanium carbide from industrial Fe–Ti
Carbides of Ti have been synthesized directly from industrial ferrotitanium (Fe-Ti) for the first time through high energy mechanical milling and heat treatment. Powders of Fe-Ti mixed with graphite were milled in a planetary ball mill for varying durations between 10 and 40 h. The milled mixtures were subsequently heat treated at 1000 • C for 15 min. The as-milled and heat treated powders were characterized by using SEM-EDX and XRD techniques. With SEM images agglomeration of the particles was noticed with prolonged milling. Formation of carbides of Ti was detected by XRD even in as-milled powders at the early stage of milling. The crystallite size of the carbides gradually decreased with progress in milling. It was demonstrated that nanostructured TiC could be successfully synthesized under suitable processing conditions using industrial grade Fe-Ti as a readily available and cheap raw material.