Titanium Carbonitride Powders Research Articles

Selection of inoculant additives for modifying nickel alloys

Heat-resistant nickel alloys are widely used in the production of castings for aircraft and industrial gas turbine engines. Structural factors are the main determinants of the performance properties of cast nickel alloys. The main disadvantage of castings obtained from these alloys is the coarse-crystalline structure, uneven grain size and columnar crystals in the cross-section. Therefore, the creation of an optimal alloy structure is an important condition for obtaining high properties and ensuring the increased operability of cast parts. Obtaining a fine-grained structure has a beneficial effect on the level of mechanical and operational properties of cast metal. The most promising way to create such a structure is to introduce a small number of additives into the melt that cause heterogeneous formation of crystal nuclei, i.e. modification of the melt with dispersed particles of refractory elements and inocular compounds. To select the type of inocular particles required to initiate crystallization of a particular phase, it is necessary to have a set of data that allows one to form a theoretical understanding of the principles of such a choice. The paper provides a rationale for the selection of the type of particles of inoculators capable of causing the process of artificial changes in the structure of cast metal. For a heat-resistant nickel alloy, the use of refractory particles of ultra-dispersed titanium carbo nitride powder as inoculators are the most effective. When introduced into the melt 0.025 wt. % of such particles, a fine-grained structure of the alloy is obtained, and its ductility in comparison with the unmodified one is more than doubled.

In-situ synthesis and purification of high grade titanium carbonitride powder via carbonitrothermic reduction of low grade titanium ore

This study reports the production of pure titanium carbonitride powder via carbonitrothermic reduction of low grade titanium ore. High temperature reduction of the as-milled samples in a nitrogen-containing atmosphere at 1400 °C for 20 min was maintained for the synthesis of the Fe – TiCN composite. An acid solution of 10% concentration, which contains HCl acid, was used to purify the Fe – TiCN composite, for the purpose of obtaining a high purity TiCN powder. The obtained TiCN powder was characterized using field emission scanning electron microscopy (FESEM), X-ray diffraction spectrometer (XRD), particle size analyser (PSA), LECO non – metal analyser, Raman spectroscopy, and high resolution transmission electron microscope (HRTEM) was used to study the powder lattice orientation and particle distribution. The overall results of these analyses confirm the formation of high grade TiCN powder, as the synthesized powder was free of iron and other impurities, and its mean particle size was found to be 4.687 μm.

Development of technology for modification of heat-resistant nickel alloy ЖС3ДК-ВІ with titanium carbonitride ultrafine powders

Purpose. To study the effect of modification by the titanium carbonitride Ti(C, N) ultrafine particles additives in the form of powder and briquettes on the structure and physical-mechanical properties of the ЖС3ДК-ВІ alloy used for the manufacture of aircraft engine turbines cast rotor blades.
 Research methods. Preliminary high-temperature treatment of the melt was carried out on a VIP-10 installation.
 On the UPPF-3M installation with the alkaline melting pot, the ЖС3ДК-ВІ alloy was modified with ultrafine particles of titanium carbonitride Ti(C,N) in an amount of 60...80 g in the form of briquettes or powder wrapped in nickel foil.
 The samples were subjected to homogenization at a temperature of 1210 °C with a holding time of 3.5 hours and air cooling.
 The chemical composition of investigated alloys was determined. The macrostructure was studied on plates ~ 4 mm thick after chemical etching. The microstructure was evaluated on microsections before and after etching in the Marble reagent.
 Microhardness, ultimate strength, elongation and contraction, impact strength were determined at room temperature. Long-term strength tests were carried out at 850 °C under a load of 350 MPa. The bending test of the blades was carried out on a manual screw press in accordance with GOST 14019-80.
 Results. The microstructure of Ti+TiCN briquettes has been studied by optical and electron microscopy. X-ray microanalysis of specimen fractures confirmed a fairly uniform distribution of titanium carbonitride in the volume of briquettes.
 The chemical composition, macro- and microstructure of the experimental alloy have been studied. A fracto-graphic study of the samples fracture structure was carried out.
 The modifying effect of titanium carbonitride ultrafine particles on the dendritic structure, distribution and change in the morphology of primary carbides, the number and distribution of carbonitride particles has been established.
 A comparative analysis of the mechanical and heat-resistant properties of the ЖС3ДК-ВІ alloy of standard composition and modified with ultradispersed Ti(C,N) particles has been carried out. Bending tests of turbine rotor blades were carried out.
 Scientific novelty. It is shown that the use of ultrafine titanium carbonitride powders for bulk modification of the heat-resistant nickel alloy ЖС3ДК-ВІ makes it possible to increase the mechanical and heat-resistant properties of the material. Increasing the amount of modifier promotes grain refinement.
 More stable properties and favorable structure are provided by melt modification with ultrafine Ti(C,N) particles in the form of briquettes. It was found that modification with powdered Ti(C,N) leads to a decrease in the impact toughness values due to the formation of boundary microporosity.
 Practical value. The technology of the heat-resistant nickel alloy ЖС3ДК-ВІ, used for the manufacture of cast rotor blades of gas turbine engines, modification with additives of titanium carbonitride Ti(C,N) ultrafine particles, providing an increased level of performance properties of finished products, has been developed.

INOCULATION OF HIGH MANGANESE STEEL CASTINGS USING TITANIUM CARBONITRIDE

The article is devoted to study of the process of mold inoculation of high manganese steel castings using titanium carbonitride. Introduction considers basic principles, alloying and inoculation of casting alloys. Review of the papers on this topic made by native and foreign researchers was given. Conclusions were made on the materials presented in the studied papers, goals and tasks for studies were formed. Besides, in this part of the article relevance of the conducted researches was substantiated as well as practical significance for casters. The second part of the article describes routine of experiments. Materials involved when conducting experimental works were considered in details: charge materials, treatment agent, materials for foundry molds. Besides, there are also described the way to receive experimental cast products, methodology to determine thermal conditions for forming experimental models in foundry mold and regimen of thermal treatment. Herewith, methodology for conducting metallographical test was considered. The third part of the article mentions the results received during carrying out experimental works on mold inoculation using fine titanium carbonitride powder of high manganese steel castings. Influence of inoculation on the level of performance properties expressed via coefficients of abrasive wear and wear striking resistance was considered as well as change of the indicated peculiarities in relation to not inoculated alloy was evaluated. Besides, results of metallographical tests were given which allowed to substantiate change of the performance properties level of high manganese steel. Influence of thermal conditions of forming cast products was also evaluated, in particular speed of alloy cooling in foundry mold on the level of performance properties of inoculated high manganese steel. In final part of the article conclusions on the results of conducted researches were made as well as manufacturing recommendations were given for practical implementation of the work results to increase the level of performance properties of high manganese steel. Besides, recommendations on the most reasonable expenditure of titanium carbonitride powder ensuring receipt of the necessary characteristics of microstructure and as a consequence, increase of the level of performance properties were given.

Azide SHS of highly dispersed powder of titanium carbonitride with intermediate partial nitriding or partial carburizing titanium powder

It is noted that the powder of titanium carbonitride (TiC0.5N0.5) is the basis of the TiC1−xNx/Ni–Mo system cermets, which are considered as the most promising tool materials for the replacement of classical hard alloys based on tungsten carbide of the WC–Co system. The properties of these cermets are the higher the finer is the titanium carbonitride powder from which they are sintered. First, a simple energy-saving process of self-propagating high-temperature synthesis (SHS) was applied for the intermediate partial nitriding of the initial metal powder of titanium to the composition of TiN0.2 or partial carburizing to TiC0.3 composition in order to ensure fire safety and efficiency of the grinding process in the planetary ball mill to obtain superfine powders of partially nitrided or carburized titanium with ultrafine structure. Further, these powders were used in the azide SHS process for complete nitriding and carburizing to produce titanium carbonitride powder which was composed of superfine agglomerates of ultrafine and nano-particles of TiC0.5N0.5.

Modification of High-Manganese Steel Castings with Titanium Carbonitride

Modification of high-manganese steel castings in the mold by titanium carbonitride is investigated. First, the basic principles of alloying and modification of cast alloys are outlined, and the relevant literature is reviewed. That provides the basis for formulating the research goals. The practical significance of the research for casting enterprises is confirmed. Next, the materials employed are considered in detail: the batch components, the modifier, the materials used in the casting molds. Likewise, the experimental methods are described: in particular, the methods used in producing experimental castings and in determining the thermal conditions in the mold and the optimal heat treatment. In addition, the metallographic techniques employed are noted. The experimental results regarding the modification of the steel casting by fine titanium-carbonitride powder in the mold are presented. The influence of such modification on the performance of the high-manganese steel is considered, in terms of improved abrasive and impact–abrasive wear resistance. Metallographic data explain the basis for the improved performance of the high-manganese steel. The influence of the thermal conditions in the mold is considered: in particular, the influence of the rate of alloy cooling in the mold on the performance of the modified high-manganese steel. Finally, on the basis of the research findings, recommendations are made for improving the performance of cast high-manganese steel products. In addition, recommendations are made regarding the optimal consumption of titanium-carbonitride powder so as to obtain the required microstructure and properties of the high-manganese steel.

Mechanical properties of ultrafine graphite –Ti (C0.9, N0.1) solid solutions fabricated via spark plasma sintering.

Abstract Spark plasma sintering technique was used to consolidate solid solution of graphite–Ti (C0.9, N0.1) using ultrafine size of graphite and titanium carbonitride powder with carbon to nitrogen composition of 90:10 at 2000 oC for 5 mins. The densification of the sintered graphite (0-1 wt. %) –Ti (C0.9, N0.1) was 98-99% at 2000 oC in the matrix. The carbide rich and Ti rich were the two distinct solid solution phases observed, although Graphite –Ti (C0.9, N0.1) solid solution as a solitary phase was attained at 2000 oC. This could be attributed to changes in the parameters with in the lattice site due to excess heat and causing the solid solutions phases to favour the carbide and titanium phases, respectively. The graphite–Ti (C0.9, N0.1) solid solution upon the application of different load the value of the hardness decreases as the load increases for unreinforced and reinforced Ti (C0.9, N0.1). Furthermore, the fracture toughness (KIC ) was within the range of (1.04 – 7.99) in MPa m1/2.

Preparation of the highly dispersed powder of titanium carbonitride by SHS azide technology with previous partial nitriding

It is shown that the powder of very hard refractory titanium carbonitride (TiC0.5N0.5) is the basis of tungsten-free hard alloys which are prospective for application as inexpensive cutting tools. The finer the powder of titanium carbonitrideis, the moreenhanced properties of hard alloys, sintered from the powder, are. An opportunity to reduce the particle size of the titanium carbonitride powder obtained by energy-saving azide technology of self-propagating high-temperature synthesis at the cost of reducing the particle size of the initial titanium powderwas investigated. To ensure the safety of the grinding process of the initial metal titanium powder, it was offered to nitride a Ti powder partially into a TiN0.2 compound. Such partial nitriding was performed by the azidetechnology with lack of sodium azide (NaN3) as a nitriding reagent. After intensive grinding in the planetary ball mill, the TiN0.2 powder turned into a superfine powder with an ultrafine structure. This powder was capable of nitriding and carburizing in the azide technology with formation of superfine pure powder agglomerates which are composed of ultrafine and nano-particles of TiC0.5N0.5.

Investigation of the main influencing parameters on the degassing behavior of titanium carbonitrides using mass spectrometry

It is well known that titanium carbonitrides (Ti(C,N)) release carbon monoxide (CO) and nitrogen (N2) upon heat treatment, which can influence further processing such as sintering. Thus a deeper understanding concerning the driving forces of the degassing behavior could facilitate the development of further processing steps. Therefore, the focus of this study was put on determining the main influencing factors of the degassing behavior of titanium carbonitrides during heat treatment. For this purpose, an application-oriented characterization method by modifying an evolving gas analysis device (EGA) was developed. Quadrupol mass spectrometry (MS) was applied to monitor the gas evolution as a function of temperature under vacuum. The evolving CO and N2 were transported to the mass spectrometer using a helium carrier gas flow. Thermogravimetric analysis was deployed to complement the mass spectrometry data and to further elaborate on the outgassing behavior of the different sample species.Titanium carbonitride powders with different C/N/O ratios, grain size as well as free carbon content blended with typical binder metals (Co, Ni and Co+Ni) were investigated regarding their degassing behavior. The different C/N/O ratios influenced decisively the CO as well as the N2 outgassing in terms of quantity and temperature range. Consequently, a unique outgassing pattern, a “finger print”, was identified for each titanium carbonitride powder type. An altered grain size on the other hand, did not lead to a changed gas evolution. However, the content of free carbon was influencing the CO and the N2 outgassing significantly. The binder type, by contrast, was influencing the N2 evolution to a higher degree than the CO evolution.

Mechanical properties of stainless steel composites with titanium carbonitride consolidated by spark plasma sintering

In this paper, stainless steel–titanium carbonitride-based composites were fabricated and analyzed to utilize for bipolar plate in fuel cells. In order to study the size effect of titanium carbonitride on the mechanical and corrosion resistance properties of the composites, micro and nanosize titanium carbonitride powders were used. Stainless steel–carbonitride composites were prepared by spark plasma sintering and subsequently annealed at different temperatures up to 1100℃ to improve the morphological and mechanical properties. Various properties of the obtained samples were compared before and after annealing. It was shown that after heat treatment, the mechanical properties of the stainless steel–carbonitride composites improved due to the diffusion of titanium carbonitride particles into stainless steel. Addition of microsized titanium carbonitride powders was found to be effective to improve the mechanical properties, such as microhardness and compressive strength, of the composite. However, addition of nanosized titanium carbonitride powders led to an increase of corrosion resistivity of the composite. Physical properties, such as thermal and chemical stability of the obtained composite samples were investigated by microhardness tester, potentiostat, field emission-scanning electron microscope, EDX and X-ray diffraction.

Synthesis of Titanium Carbonitride Powders by Reactive Ball Milling of Titanium, Graphite and Urea

Titanium carbonitride (TiCN) nanocrystaline powders were syntheiszed by reactive ball milling of titanium, graphite and urea. GN-2 ball milling was used and the rotation speed was 600rpm. The ratio of ball to material was 30:1, the milling time was from 10 hours to 50 hours. The powders milled for different time were analyzed by X-ray diffraction. The results show that TiCN powders can be synthesized by milling 10 hours, although some raw materials remained. After milled for 50 hours, the raw materials can reactive completely to form TiCN and the grain size of the TiCN powder was about 7 nm.

Effect of Annealing Temperature on Electrochemical and Mechanical Properties of STS with Titanium Carbonitride Composites Synthesized By Spark Plasma Sintering

Stainless steel-titanium carbonitride based composites were fabricated and analyzed to utilize for bipolar plate in fuel cells. In order to study the size effect of the titanium carbonitride on mechanical and corrosion resistance properties of the composites, micro and nanosize titanium carbonitride powders were used. Stainless steel-carbonitride composites were prepared by spark plasma sintering and subsequently annealed at different temperatures up to 1100 °C to improve the morphological and mechanical properties. Various properties of the obtained samples were compared before and after annealing. It was shown that after the heat treatment, mechanical properties of the stainless steel-carbonitride composites were improved due to the diffusion of titanium carbonitride particles into stainless steel. Addition of microsized titanium carbonitride powders was found to be effective to improve the mechanical properties of the composite such as microhardness and compressive strength. However, addition of nanosized titanium carbonitride powders led to increasing of corrosion resistivity of the composite. Physical properties, such as thermal and chemical stability of the obtained composite samples were investigated by microhardness tester, potentiostat, field emission-scanning electron microscope, EDX and X-ray diffraction.

Oxygen reduction reaction activity of nitrogen-doped titanium oxide in acid media

For the first time, nitrogen atoms have been doped into partially oxidized titanium carbonitride powder to improve its oxygen reduction reaction (ORR) activity in acid media. The catalysts were synthesized using two heat-treatment steps, the first using a mixed gas containing H2, O2, and N2 under fixed conditions, and the second using NH3 gas at various temperatures and times. Field-emission transmission electron microscopy images, X-ray diffraction patterns, Raman spectra, X-ray photoelectron spectra, and cyclic voltammograms were analyzed. Carbon-coated tetragonal rutile-TiO2 plates were produced by the first heat-treatment. The ORR activity in 0.1moldm−3 H2SO4 increased with increasing temperature in the second heat-treatment at temperatures up to 1073K when the number of oxygen defects in the rutile-TiO2 lattice was increased by nitrogen doping. However, it decreased with further increases in temperature when the crystal structure was completely converted to cubic TiN. Heat-treatments were performed on four types of commercial TiO2 powders under NH3 gas at the optimum temperature, 1073K, but they all showed activity at potentials more than 0.4V lower than those with the titanium-carbonitride-derived catalysts, in which ORR currents were observed at above 0.8V versus a reversible hydrogen electrode. It was found that carbon species in the titanium carbonitride precursor powders, which produced graphitic layers during the first heat-treatment, were necessary for improving the ORR activity by the second heat-treatment under NH3 gas. A nitrogen-doped rutile-TiO2 lattice with oxygen defects was suggested to be responsible for the ORR.

Spark plasma sintering of TiCN nanopowders in non-linear heating and loading regimes

Consolidation of commercially available nanostructured titanium carbonitride (TiCN) powder has been performed by Spark Plasma Sintering (SPS) in the temperature range from 1300 to 1600°C. The effect of non-linear heating and loading regimes on consolidation of high melting point nanocomposites has been investigated. SPS consolidated TiCN material has demonstrated near fully dense and fine homogeneous microstructure with average grains size about 150nm. Nanohardness and fracture toughness of the TiCN nanocomposite have been measured as 33±0.9GPa and 3.2MPam1/2 respectively.

Spark Plasma Sintering of Ultrafine TiCxN1−x Powders Synthesized by a Mechanically Induced Self‐Sustaining Reaction

High‐purity, nanometer‐sized titanium carbonitride powders, TiCxN1−x, were obtained with a mechanically induced self‐sustaining reaction (MSR) in a high‐energy planetary ball mill from a mixture of titanium and different carbon precursors under a nitrogen atmosphere. A promising method for developing dense TiCxN1−x materials is the coupling of MSR with the spark plasma sintering (SPS) technique. The powders were sintered at different temperatures to provide a completely dense monolithic ceramic (>99% theoretical density). In this work, the influence of the carbon precursor and SPS treatment on the material microstructures were studied, and the main mechanical properties of the end material were evaluated.

Preparation of an Advanced Al<sub>2</sub>O<sub>3</sub> Based Nanocomposite Ceramic Die Material

Through the incorporation of nano sized Titanium Carbonitride powders into the Al2O3 matrix, an advanced Al2O3/Ti(C7N3) nanocomposite ceramic die material was fabricated by vacuum hot pressing technique. Effects of the content of nano Ti(C7N3) on the microstructure and mechanical properties of the nanocomposite ceramic die material were investigated. It indicates that both flexural strength and fracture toughness were increased noticeably compared with the pure micrometer sized alumina ceramic. Toughening mechanisms of the ceramic composite were also analyzed. It reveals that the intragranular/intergranular microstructures and the resulted transgranular/intergranular fracture modes are the main causes for the reinforcing and toughening of the nanocomposite ceramic die material.

Advanced WC–Co cermet composites with reinforcement of TiCN prepared by extended thermal plasma route

The synthesis of titanium carbonitride (TiCN) powders by thermal plasma using extended arc thermal plasma reactor and the effect of TiCN reinforcement for the development of advanced WC–Co cermets has been studied with respect to hardness and fracture toughness. These classes of materials are being investigated for future application in wear-resistant seals, cutting tools, etc. Metallurgical reactions and microstructural developments during sintering of cermets and functionally graded cemented carbonitrides are being investigated by analytical methods such as differential thermal analysis/thermo-gravimetric analysis, X-ray diffraction and analytical Scanning electron microscopy with energy dispersive X-ray spectroscopy. By an in-depth understanding of the complex phase reactions and the mechanisms that govern the sintering process and metallurgical reactions, new cermets and different types of functionally graded cemented carbonitrides with desired microstructures and properties have been attempted to develop. The significant improvement of micro-hardness was observed with optimal concentration of TiCN reinforcement addition in WC–Co system without sacrificing much fracture toughness value of the composite cermets.

Synthesis of nanocrystalline titanium carbonitride during milling of titanium and carbon in nitrogen atmosphere

Mixtures of elemental titanium and carbon with Ti/C atomic ratio of 1:0, 1:0.125, 1:0.25, 1:0.5 and 1:0.75 were milled in nitrogen atmosphere using a high-energy ball mill, Spex8000. Nanocrystalline titanium carbonitride powders have been synthesized when milling the mixtures with Ti/C atomic ratio not less than 0.25. The formation of the titanium carbonitride phase has been found to undergo an abrupt reaction. It is suggested that this reaction appears to be a self-propagating high-temperature synthesis (SHS) process. During the incubation duration of the SHS reaction, small amount of titanium carbonitride phase has been detected by X-ray diffraction (XRD). The composition and lattice parameter of the synthesized titanium carbonitride phase can be adjusted by changing the composition of the starting mixture of elemental titanium and carbon.

Combustion Synthesis of Ti(C,N) Powder

Titanium carbonitride powders were synthesized directly by a combustion synthesis process between titanium and carbon in a nitrogen atmosphere. The relationships between properties of the final product and the combustion reaction parameters were systematically investigated. Especially, the effects of nitrogen pressure on the phase formation and microstructure of the as-synthesized products were experimentally investigated. The reaction mechanism of Ti(C,N) was proposed through quench experiment, the variation of combustion temperature on time and thermodynamics analysis.

Synthesis of Titanium Carbonitride Phases by Reactive Milling of the Elemental Mixed Powders

Titanium carbonitride (TiCxN1−x) powders were obtained by high‐energy ball milling of elemental titanium and carbon (activated carbon or graphite) in a nitrogen atmosphere. The formation of the carbonitride phase was controlled by adequately choosing the experimental conditions of the milling process. The stoichiometry of TiCxN1−x powders was modified by adjusting the titanium‐to‐carbon molar ratio. The composition and cell parameters of the carbonitride phases were determined. Microstructural characterization of these phases showed a nanocrystalline nature.