Chinese name: titanium carbonitride
English name: Titanium carbonitride
Molecular formula: TiCN
Molecular weight: 121.75
Melting point: 2900 ℃
Density: 5.08 g/mL at 25 ° C (lit.)
Hardness (HV): 34GPaI density is 4.52
Properties: gray or gray-black powder with hexagonal crystal structure, low internal stress, high toughness, good lubricity, high hardness, wear resistance and other characteristics, suitable for occasions requiring low friction coefficient and high hardness.
1. The cermet made of titanium carbonitride has the following characteristics: the hardness (HRA) is as high as 91-95, which can reach the hardness level of non-metallic ceramic tools; It has good wear resistance and ideal resistance to crescent pit wear. The wear rate is very low when high-speed cutting steel, and its wear resistance is 3-4 times higher than that of WC-based cemented carbide; It has high heat resistance, high temperature hardness, high temperature strength and high temperature wear resistance. It can be cut at 1100-1300 ℃. Generally, the cutting speed is 2-3 times higher than that of WC-based cemented carbide; It has good chemical stability and high antioxidant capacity; Compared with cemented carbide, titanium carbonitride cermets have high wear resistance, lower oxidation degree, better thermal shock resistance, and are suitable for use as high-speed cutting tool materials, which can well control the geometric accuracy and tolerance of the workpiece, high finish, and high feed speed; Good results can be obtained when processing carbon steel, stainless steel, microalloyed steel and nodular cast iron.
2. Titanium carbonitride is a glossy black powder, which is a zero-dimensional ternary solid solution. TiC and TiN are the basis of titanium carbonitride, which have the NaCl type structure of face-centered cubic lattice, and can also form a solid solution with various transition metal carbides such as TaC and NbC. Titanium carbonitride is a compound compound formed in a single TiC lattice where nitrogen atoms (N) occupy the position of the original carbon atoms (C) in the lattice. There are two ideal modes for the proportion of carbon and nitrogen atoms in TiCxNy, namely, TiC0.5N0.5 and TiC0.3N0.7. Because TiCN has the comprehensive properties of TiC and TiN, and its hardness is higher than TiC and TiN, it is an ideal tool coating material. The coating can not only improve the bonding strength with the substrate, but also have the comprehensive properties of various materials.
Purpose: 1) Wear resistance, acid and alkali resistance, strong conductivity and thermal conductivity, small coefficient of thermal expansion, excellent chemical stability and heat resistance. It is widely used in cutting tools, powder metallurgy and cermet products.
2) Coating: TiCN has lower friction coefficient and higher hardness than TiN. The tool coated with titanium nitride carbide is more suitable for cutting hard materials such as stainless steel, titanium alloy and nickel alloy. It has more wear resistance and high temperature stability, and can significantly improve the tool life. Titanium nitride coating (TiN) is a general-purpose PVD coating with a thickness of 2300HV. It is a hard coating material with mature technology and widespread application. Features: high hardness, high wear resistance and oxidation resistance. Purpose: Suitable for most cutting tools and high-speed steel cutting tools or forming tools to improve their machining performance. It is also suitable for most forming dies and anti-wear parts. Titanium nitride carbide coating (TiCN), in which carbon element is added, can improve tool hardness and obtain better surface lubricity to reduce friction coefficient. It is an ideal coating for high-speed steel tools. The thickness of the coating is 2800HV, which prevents crack propagation and reduces edge collapse.
3) It combines the advantages of TiC and TiN. In addition to being very suitable for high-end precision machining and near-net forming processing, it has significantly improved the brittleness of TiC due to the introduction of N on the basis of maintaining the characteristics of TiC. With the increase of N content, its hardness decreases and its toughness increases. It is precisely because of its excellent comprehensive properties that titanium carbonitride based ceramics have been widely used in the fields of cutting, high-temperature resistant materials, measuring tools, petroleum and chemical industry, watch and clock appearance, etc.
4) Refractory materials, non-oxide added to refractory materials, will bring some excellent properties. Some studies have shown that the existence of titanium carbonitride can significantly improve the service performance of refractories.
1. High temperature solid solution method
High-temperature solid solution method is a traditional method for preparing Ti (C, N) powder, which is usually formed by mixing a certain amount of TiN and TiC powder uniformly and hot pressing solid solution at 1700~1800 ℃, or by solid solution at higher temperature in Ar or N2 atmosphere. In order to inhibit grain growth and improve powder activity and sintering performance, the solution temperature can also be appropriately reduced. Even if the solution temperature is reduced, the high temperature solution method also has the disadvantages of high reaction temperature, high energy consumption, difficulty in obtaining high-purity powder, and difficulty in accurately controlling the N/C ratio.
2. High temperature nitridation of TiN and C powder
The high-temperature nitridation method usually takes TiN powder and C powder as raw materials, and then carries out long-term carbonitriding treatment under high temperature and N2 or Ar atmosphere after mixing, so as to obtain Ti (C, N) powder. Frederic et al. synthesized Ti (C, N) powder with nano-sized TiN powder+10wt% carbon black in Ar gas stream at 1430 ℃ for 3h, and showed regular shape submicron particles. Similarly, the high-temperature nitriding process has the disadvantages of high reaction temperature, low production efficiency, high energy consumption and high production cost.
3. High temperature self-propagating reaction method
High-temperature self-propagating reaction method is to mix Ti powder and C powder evenly, pre-press and form the compacts, and then "ignite" the reaction at high temperature in the device containing N2, so as to obtain bulk products. Ti (C, N) powder can be obtained by crushing and refining.
4. Self-propagating synthesis induced by high-energy ball milling
As a powder processing method, high-energy ball milling can not only uniformly mix and activate the powder to reduce the sintering reaction temperature and promote alloying, but also induce the self-propagating reaction to synthesize nano-Ti (C, N) powder at room temperature. The technology of Ti (C, N) synthesis induced by high-energy ball milling and self-propagation combines powder mixing and reaction, overcomes the traditional high temperature conditions, and can directly obtain Ti (C, N) powder.
5. TiO2 carbothermal reduction nitridation method
The carbothermal reduction nitridation process is a process of synthesizing Ti (C, N) powder by reduction of TiO2 and C powder in N2 at high temperature. The size and morphology of the products of the carbothermal reduction method can be controlled by process parameters, and is widely used in industrial large-scale production.
The ammonolysis process usually involves dissolving TiCl4 into appropriate solvent and adding additives at normal temperature, mixing them evenly and reacting with NH3 to produce a uniformly mixed intermediate of Ti amine compounds and additives, then mixing the intermediate with NH4Cl solution to precipitate and remove the amine in the intermediate, and then pyrolysis in vacuum or Ar atmosphere at 1200~1600 ℃ to obtain Ti (C, N) powder. The characteristic of ammonolysis is that the preparation temperature is lower than the traditional preparation method (high temperature solid solution method, 1800 ℃). The Ti (C, N) powder obtained has the advantages of high specific surface area, small particle size, concentrated particle size distribution and high purity, but the cost is high and the process is complex.
Precautions for storage: Store in a cool, dry and well-ventilated special warehouse with sealed packaging.
Preparation of titanium carbonitride powder
1. High temperature solution method
Ti(C, N) powders are prepared by high temperature solid solution method, which is usually formed by a certain amount of TiN and TiC powders mixed uniformly at 1700 ~ 1800℃, or by solid solution in Ar or N2 atmosphere at higher temperature. In order to restrain grain growth and improve powder activity and sintering performance, the solution temperature can be appropriately reduced. Even if the solution temperature is reduced, the high temperature solution method has some disadvantages, such as high reaction temperature, high energy consumption, difficult to obtain high purity powder, and difficult to accurately control the N/C ratio.
2. High temperature nitriding of TiN and C powder
High temperature nitriding method is usually based on TiN powder and C powder as raw materials, mixed in high temperature and N2 or Ar atmosphere for a long time to get Ti(C, N) powder. Frederic et al. used nano-sized TiN powder +10wt% carbon black to hold for 3h at 1430℃ in Ar air flow, and formed Ti(C, N) powder with solid phase, exhibiting regular shape sub-micron particles. Similarly, high temperature nitriding has the disadvantages of high reaction temperature, low production efficiency, high energy consumption and high production cost.
3. TiO2 carbon thermal reduction nitriding
Carbon thermal reduction nitride is a process of synthesis of Ti(C, N) powder by high temperature reduction in N2 with TiO2 and C powder as raw materials. The size and morphology of the product of carbon thermal reduction can be controlled by process parameters, which is widely used in industrial large-scale production.
4. Sol-gel method
The sol-gel method is to use TiO(OH)2 sol as Ti source, mix and disperse carbon black in liquid phase, and get Ti(C, N) powder by high temperature heat treatment under N2 after a series of reactions. Some researchers obtained Ti(Cx, N1-X) from the gel formed by mixing TiO(OH)2 sol with nano carbon black after drying and reacting at 1400 ~ 1600℃ under N2 atmosphere, in which 1-x=0.2 ~ 0.7, the average particle size of Ti(Cx, N1-x) ultrafine powder was less than 100nm. The x value can be improved by increasing the C/Ti ratio of raw materials, increasing the reaction temperature, prolonging the holding time and reducing the nitrogen flow rate.
5. ammonia solution
In ammonolysis, TiCl4 is usually dissolved in an appropriate solvent and added with additives at room temperature. After being mixed evenly, TiCl4 reacts with NH3 to generate a evenly mixed intermediate of Ti's amine group compound and additives. Then the intermediate is mixed with NH4Cl solution to precipitate and remove the amine in the intermediate. Ti(C, N) powders were prepared by pyrolysis at 1200 ~ 1600℃ in vacuum or Ar atmosphere. The characteristic of ammoniation method is that the preparation temperature is lower than the traditional preparation method (high temperature solution method, 1800℃). The Ti(C, N) powder obtained has the advantages of high specific surface area, small particle size, concentrated particle size distribution and high purity, but the cost is high and the process is complicated.
6. High temperature self-propagating reaction
The high temperature self-propagating reaction method is to evenly mix Ti powder and C powder, prepress forming to get the blank, and then in the device containing N2 "ignite" reaction at high temperature, so as to get the bulk product, through the fragmentation refinement can get Ti(C, N) powder.
7. Plasma chemical vapor deposition
Ti(C, N) plasma chemical vapor deposition is usually used to activate TiCl4 reaction gas by plasma to promote its chemical reaction on the surface of the substrate or near the surface space to generate Ti(C, N) solid film. Later, in order to avoid TiCl4 corrosion of the reaction vessel and pollution to the environment, chlorine free Ti organic matter is often used to replace TiCl4. This type of Ti - containing organic compounds mainly include tetramethyl titanate, tetraethyl titanate, tetraisopropyl titanium, tetrabutyl titanate and titanium amine, etc.
8. High energy ball milling-induced self-propagating synthesis
As a powder processing method, high-energy ball milling can not only uniformly mix and activate powder to reduce sintering reaction temperature and promote alloying, but also induce self-propagating reaction to synthesize nano Ti(C, N) powder at room temperature. The technique of high energy ball milling induced self-propagating synthesis of Ti(C, N) integrates powder mixing and reaction, overcomes the traditional high temperature conditions, and can directly obtain Ti(C, N) powder.
Application of titanium carbonitride
1. Ti(C, N) base ceramic cutting tools
Ti (C, N) fund of ceramic is a kind of very important structural materials, with its, compared to the preparation of the cutting tool with WC cemented carbide processing in develop high red hardness, similar intensity, low corrosion resistance, thermal conductivity and coefficient of friction, has the high life or in the life the same situation can use high cutting speed, The machined workpiece has a good surface finish. It is understood that Japan's Ti(C, N) fund ceramic tool materials have accounted for more than 30% of the market share of all tool materials.
2. Ti(C, N) fund ceramic coating
Ti(C, N) base ceramics can be made into wear-resistant coatings and die materials. Ti(C, N) coating has excellent mechanical and tribological properties. As a hard wear resistant coating, Ti(C, N) coating has been widely used in cutting tools, drills and molds, and has broad application prospects. Its preparation technology mainly includes plasma chemical vapor deposition, medium temperature chemical vapor deposition, traditional CVD method and so on. Ti(C, N) fund ceramics as mold materials, compared with die steel, has no phase change, high temperature resistance, low friction coefficient and good adhesion resistance, and has a certain strength and toughness, is a potential mold materials.
3. Multiphase ceramic materials
Ti(C, N) can be combined with other ceramics to form composite materials, such as Ti(C, N)/Al2O3, Ti(C, N)/SiC, Ti(C, N)/Si3N4, Ti(C, N)/TiB2 and other multiphase ceramic materials. As reinforcement, Ti(C, N) can improve the strength and fracture toughness of materials. It can also improve electrical conductivity.
4. Refractory materials
The addition of non - oxides to refractories will bring some excellent properties. Some studies show that the existence of titanium carbonitride can obviously improve the performance of refractory.
5. Synthesis of Ti(C, N) whiskers
As early as 2011, The 2d titanium carbide material was first prepared by Drexel University, and it was found that this material has many special properties, including high strength, high conductivity and molecular filtration ability. The property of titanium carbide was that it could block and absorb electromagnetic interference more effectively than any known material at the time, including the foil used in most electronic devices today.
When Drexel went on to examine other members of the family, they found that titanium nitride had even more excellent properties, making it a more promising candidate for shielding electromagnetic interference. This also means that titanium nitride can be used to individually coat components inside devices to contain their electromagnetic radiation, even when they are placed close together. Companies like Apple have been trying this containment strategy for years, but the success rate is limited by the thickness of the copper foil. This strategy is likely to become the new standard as device designers strive to make devices ubiquitous by making them smaller, less visible and more integrated.