A titanium carbonitride-based composite ceramic material, a preparation method thereof, and an application thereof in a mold core for precision glass molding

Abstract

The present invention discloses a titanium carbonitride-based composite ceramic material, a preparation method thereof, and an application thereof in a mold core for precision glass molding. The titanium carbonitride-based composite ceramic material is composed of a ceramic layer coating a hard alloy core; wherein, the hard alloy is a WC-based hard alloy with a low binder phase, and the ceramic layer is a titanium carbonitride-based solid solution. This composite ceramic material has excellent oxidation resistance and chemical stability, and also has properties such as high density, good consistency after polishing, low roughness, and a thermal expansion coefficient matching that of glass, and is particularly suitable for preparing a mold core for precision molding of aspherical and curved glass.

Description

Technical Field

[0001] The present invention relates to a titanium carbonitride-based composite ceramic material, specifically to a titanium carbonitride-based composite ceramic material for aspherical and curved glass molding, and also relates to its preparation method and application in the mold core for precision glass molding, belonging to the technical field of cermet materials. Background Art

[0002] The complex and delicate shape structure of aspherical and curved glass endows the glass with special application functions and can provide more accurate imaging effects. Therefore, its application scope is becoming wider and wider in the fields of security, monitoring, and automotive autonomous driving. Aspherical and curved glass is mainly prepared by precision molding technology, which has a short process flow and high production efficiency. However, compared with cold processing, the precision molding technology is more difficult and requires precise control of the temperature, force transmission system, and components during the process. During the precision molding process, the complex and precise aspherical glass is hot-pressed at high temperature through the mold core material and is pressed into the shape processed by the mold core material. Therefore, the dimensional accuracy and roughness of the mold core itself will be transcribed onto the high-temperature glass, which is a key link in glass molding.

[0003] In industrial production, the mold core material for aspherical and curved glass molding often uses a WC-based cemented carbide material without a binder phase with a binder phase mass percentage lower than 0.5%, and a diamond-like carbon coating or a noble metal coating is deposited on the surface. The necessity of the coating is attributed to the poor oxidation resistance of the WC-based cemented carbide, which will cause yellow tungsten oxide powder to fall off during use, affecting the glass imaging quality. At the same time, the low binder phase content will lead to differences in the polishing degree between the hard phase and the metal phase, resulting in a lower processing roughness. However, the presence of the coating also limits the service life of the mold core. During multiple heating and cooling cycles, it will wear and fall off, restricting the production quality and production efficiency of precision molding.

[0004] The oxidation process of the WC-based cemented carbide without a binder phase is accompanied by the volume expansion of the porous oxidation product, so its oxidation resistance is poor and it is easy to react with glass. Therefore, a surface coating must be carried out. Compared with WC, titanium carbonitride has excellent oxidation resistance and high-temperature hardness, and can maintain high stability during long-term use. Its chemical stability is excellent, which can avoid reacting with glass. However, there are great difficulties in preparing the WC-free pure titanium carbonitride ceramic, and its thermal expansion coefficient is smaller than that of common glass, which may cause problems such as glass breakage during precision molding. To sum up, the precision molding industry currently urgently needs to develop a mold core material that can maintain high precision, high oxidation resistance, high chemical stability, and long service life for a long time. Summary of the Invention

[0005] Aiming at the defects existing in the prior art, the first object of the present invention is to provide a titanium carbonitride-based composite ceramic material, which has excellent oxidation resistance and chemical stability, and also has properties such as high density, good consistency after polishing, low roughness and a thermal expansion coefficient matching that of glass, and is suitable for preparing a mold core for precision molding of aspherical and curved glass.

[0006] The second object of the present invention is to provide a preparation method of a titanium carbonitride-based composite ceramic material, which has simple operation and low cost, and is conducive to large-scale production.

[0007] The third object of the present invention is to provide an application of a titanium carbonitride-based composite ceramic material, which has excellent oxidation resistance and chemical stability, and also has properties such as high density, good consistency after polishing, low roughness and a thermal expansion coefficient matching that of glass. Processing it into a mold core for precision molding of aspherical and curved glass can be used for a long time without a coating, saving coating time and cost while improving the service life of the mold core, which is conducive to stable production and reduction of production costs.

[0008] To achieve the above technical objects, the present invention provides a titanium carbonitride-based composite ceramic material, which is composed of a ceramic layer coating a cemented carbide core; the cemented carbide is a low-binder-phase WC-based cemented carbide; the ceramic layer is a titanium carbonitride-based solid solution.

[0009] For the titanium carbonitride-based composite ceramic material provided by the present invention, its core is a low-binder-phase WC-based cemented carbide, which can endow the composite ceramic material with excellent mechanical strength and low thermal expansion coefficient. The low thermal expansion coefficient can reduce the thermal expansion difference between it and glass, which is conducive to its use as a mold core material for precision molding of aspherical and curved glass. And the titanium carbonitride-based solid solution on its surface can endow the composite ceramic material with high chemical stability and oxidation resistance, so there is no need to prepare an oxidation-resistant coating on its surface, and new technical problems such as easy coating peeling in the prior art are also avoided.

[0010] As a preferred solution, the thickness of the ceramic layer is 300 - 500 μm. If the thickness of the ceramic layer is too thick, it will hinder the heat transfer and cause an increase in the thermal expansion coefficient, which is not matched with the thermal expansion coefficient of the glass to be molded; if the thickness is too low, it will lead to insufficient diffusion reaction between the ceramic layer and the cemented carbide matrix, and the FCC Ti(C,N) crystal form cannot be maintained, but becomes the HCP WC type, losing excellent oxidation resistance and chemical stability.

[0011] As a preferred solution, the ceramic layer is obtained by sintering and surface pre-oxidation from raw materials including Ti powder, W powder, Mo powder, Ta powder, Zr powder, V powder and carbon black.

[0012] As a more preferred solution, the metal elements in the raw materials include the following mass percentage contents: W 5-10%, Mo 2-5%, Ta 1-3%, Zr 0.5-2%, V 0.2-0.5%, and the rest is Ti powder; the atomic number of the carbon black is 50-55% of the total atomic number of the metal elements. Traditional binderless cemented carbides cannot be sintered by gas pressure sintering. In the technical solution of the present invention, the cemented carbide does not directly contact the glass, so a higher binder content ratio can be adopted, reducing the difficulty of material preparation and forming. The preferred raw materials can be used to prepare a titanium carbonitride-based solid solution ceramic with high chemical stability and oxidation resistance.

[0013] As a preferred solution, the cemented carbide is obtained by sintering raw materials including WC, Cr 3 C 2 , VC, TaC, Co and carbon black.

[0014] As a more preferred solution, the raw materials include the following mass percentage components: Cr 3 C 2 0.1-0.5%, VC 0.1-0.5%, TaC 0.2-0.5%, Co 0.5-1.0%, carbon black 0.3-0.4%, and the rest is WC. The preferred raw materials can be used to prepare a low-binder WC-based cemented carbide with high thermal shock resistance and low thermal expansion coefficient.

[0015] The present invention also provides a preparation method of a titanium carbonitride-based composite ceramic material, which includes the following steps:

[0016] 1) After mixing the raw materials including WC, Cr 3 C 2 , VC, TaC, Co and carbon black by ball milling, sintering I is carried out to obtain a cemented carbide block;

[0017] 2) The raw materials including Ti powder, W powder, Mo powder, Ta powder, Zr powder, V powder and carbon black are subjected to high-energy ball milling in a nitrogen atmosphere to obtain a solid solution powder;

[0018] 3) After embedding the cemented carbide block in the center of the solid solution powder, sintering II and surface pre-oxidation treatment are carried out to obtain the titanium carbonitride-based ceramic material.

[0019] Existing tungsten carbide ceramics have high thermal shock resistance and low thermal expansion coefficient, but poor chemical stability and oxidation resistance. Titanium carbonitride-based ceramic materials have excellent chemical stability and oxidation resistance and can be used without coating during the glass molding process. However, the preparation of their full sintered density is difficult, their thermal shock resistance is poor, cracks are easily induced during long-term use, and the thermal expansion coefficient is quite different from that of glass, which limits their application possibilities. The present invention uses titanium carbonitride-based solid solution powder to bury a low-bonding-phase WC-based hard alloy block and prepares a titanium carbonitride-based composite ceramic material through a diffusion technique. Its inner layer is a tungsten carbide-based hard alloy with high strength and low thermal expansion coefficient, while the surface is a titanium carbonitride-based solid solution layer with good chemical stability and oxidation resistance. In particular, the interface between the internal low-bonding-phase WC-based hard alloy core and the external titanium carbonitride-based solid solution ceramic layer is metallurgically bonded to form a tungsten-rich solid solution with strong bonding force, greatly improving the stability of the composite ceramic material.

[0020] As a preferred embodiment, the conditions for ball milling and mixing are as follows: the ball-to-material ratio is (3 - 5):1, the ball milling speed is 200 - 250 rpm, and the ball milling time is 24 - 48 h. Ball milling and mixing is a conventional physical mixing process, which is beneficial to the uniform mixing of raw material powders.

[0021] As a preferred embodiment, the conditions for high-energy ball milling are as follows: the nitrogen pressure is 1.2 - 1.5 atmospheres, the ball milling speed is 300 - 400 rpm, the ball-to-material ratio is (10 - 14):1, and the ball milling time is 4 - 6 h. By adopting the high-energy ball milling method, the metal elemental powder reaches an instantaneous high temperature during the high-speed ball milling process. Eventually, while the various alloy element powders are mixed evenly, they will react with carbon black and nitrogen during the high-energy ball milling process to complete the carbonitriding into a single-phase solid solution.

[0022] As a preferred embodiment, Sintering I adopts spark plasma sintering, hot isostatic pressing sintering or gas pressure sintering methods, the sintering temperature is 1700°C - 1900°C, and the sintering time is different for different sintering methods. When using spark plasma sintering, the time is 10 min - 20 min, and when using hot isostatic pressing and hot pressing sintering, the time is 1 h - 2 h.

[0023] As a preferred embodiment, Sintering II adopts hot isostatic pressing sintering, hot pressing sintering or spark plasma sintering methods. When using hot isostatic pressing sintering or hot pressing sintering, the sintering temperature is 1900°C - 2000°C and the time is 1 h - 2 h; when using spark plasma sintering, the sintering temperature is 1700°C - 1900°C and the time is 10 - 20 min.

[0024] As a preferred solution, the conditions for the surface pre-oxidation treatment are as follows: the temperature is 600°C to 800°C, the atmosphere is an oxygen / nitrogen mixed atmosphere, the volume content of oxygen is 5 to 10%, and the time is 30 min to 90 min. Under the preferred conditions, the pre-oxidation treatment can generate a dense oxide film passivation layer on the surface of the titanium carbonitride-based solid solution, which can resist oxidation under working conditions while maintaining high chemical stability with the glass.

[0025] The present invention also provides an application of the titanium carbonitride-based composite ceramic material, which is applied to prepare a mold core for precision glass molding.

[0026] While the titanium carbonitride-based composite ceramic material of the present invention has excellent oxidation resistance and chemical stability, it also has properties such as high density, good consistency after polishing, low roughness, and a thermal expansion coefficient matching that of glass. When it is processed into a mold core for precision molding of aspherical and curved glass, it can be used for a long time without a coating, saving coating time and costs while increasing the service life of the mold core, which is beneficial to stable production and cost reduction.

[0027] The present invention provides a method for preparing a titanium carbonitride-based composite ceramic material for precision molding of aspherical and curved glass, comprising the following steps:

[0028] (1) Preparation of low-binder-phase cemented carbide: Weigh raw materials such as WC, Cr 3 C 2 , VC, TaC, Co, carbon black, etc. for ball milling and mixing. The inner lining of the ball milling tank is cemented carbide, the ball-to-material ratio is (3 - 5):1, the ball milling rate is 200 - 250 rpm, the ball milling time is 24 - 48 h. After ball milling and mixing, sintering is carried out by methods such as spark plasma sintering, hot isostatic pressing sintering or gas pressure sintering. The sintering temperature is 1700°C to 1900°C. Different sintering methods have different sintering times. The spark plasma sintering time is 10 - 20 min, and the hot isostatic pressing and hot pressing sintering times are 1 - 2 h to prepare a low-binder-phase cemented carbide block. According to the mass percentage of the raw material powder, Cr 3 C 2 accounts for 0.1 - 0.5%, VC accounts for 0.1 - 0.5%, TaC accounts for 0.2 - 0.5%, Co accounts for 0.5 - 1.0%, carbon black accounts for 0.3 - 0.4%, and the rest is WC.

[0029] (2) Preparation of solid solution powder: Weigh Ti powder, W powder, Mo powder, Ta powder, Zr powder, V powder and carbon black according to a certain weight percentage. Among the alloying elements, by mass percentage: W accounts for 5 - 10%, Mo accounts for 2 - 5%, Ta accounts for 1 - 3%, Zr accounts for 0.5 - 2%, V accounts for 0.2 - 0.5%, and the rest is Ti powder. The atomic number of carbon black is 50 - 55% of the total number of alloying element atoms. High-energy ball milling is carried out in a nitrogen atmosphere. High-energy ball milling uses dry ball milling. The inner lining of the ball milling tank is cemented carbide. The ball milling speed is 300 - 400 rpm, the ball-to-material ratio is (10 - 14):1, and the ball milling time is 4 - 6 h. Before ball milling, the atmosphere in the ball milling tank is replaced by vacuum pumping and gas filling, filled with positive-pressure nitrogen, and the pressure is 1.2 - 1.5 atmospheres. After high-energy ball milling, solid solution powder is synthesized.

[0030] (3) Sintering preparation and pre-oxidation treatment: Place the solid solution powder prepared in step (2) in a mold or a sheath, and bury the low-bonding-phase cemented carbide block prepared in step (1) in the center of the solid solution powder. When the solid solution powder is in a room-temperature compaction state, the unilateral filling thickness is 500 - 800 μm, and then sintering is carried out. The sintering method is hot isostatic pressing sintering method, hot pressing sintering method or spark plasma sintering method. When using the hot isostatic pressing sintering method or the hot pressing sintering method, the sintering temperature is 1900°C - 2000°C, and the time is 1 - 2 hours; when using the spark plasma sintering method, the sintering temperature is 1700°C - 1900°C, and the time is 10 - 20 min. After sintering, pre-oxidation treatment is carried out. The pre-oxidation treatment temperature is 600°C - 800°C, the atmosphere is an oxygen / nitrogen mixed atmosphere, the volume content of oxygen is 5 - 10%, and the time is 30 min - 90 min, to obtain a titanium carbonitride-based composite ceramic material for aspherical and curved glass molding.

[0031] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0032] 1. For the titanium carbonitride-based composite ceramic material for aspherical and curved glass molding provided by the present invention, its core is made of low-carbon tungsten-based cemented carbide material, which expands the range of its bonding phase content, reduces the requirements for production equipment and processes during its preparation, and is more simple and low-cost.

[0033] 2. For the titanium carbonitride-based composite ceramic material for aspherical and curved glass molding provided by the present invention, its outer layer is a pre-solid solution titanium carbonitride-based solid solution. A large number of studies show that compared with pure titanium carbonitride ceramics, the titanium carbonitride-based solid solution can, on the one hand, maintain high sintering activity, have lower sintering difficulty, and obtain a dense surface with high density and no pores. On the other hand, it can have higher oxidation resistance and chemical stability through the crystal form optimization of oxides below 700°C, which is exactly the working temperature of the mold core material.

[0034] 3. The preparation method of the titanium carbonitride-based composite ceramic material for aspherical glass molding provided by the present invention is designed with different inner and outer layer materials that are easily diffusible and solid-soluble. The inner and outer layers are prone to diffusion at high temperatures, so the bonding strength is very high. The internal cemented carbide ensures high strength, thermal shock resistance of the mold core material and low thermal expansion coefficient difference with glass, which cannot be achieved by pure titanium carbonitride ceramics. Moreover, the titanium carbonitride-based solid solution on its surface can endow the composite ceramic material with high chemical stability and oxidation resistance. Therefore, there is no need to prepare an oxidation-resistant coating on its surface, and new technical problems such as easy coating peeling in the prior art are also avoided. Detailed implementation mode

[0035] The following specific examples are intended to further illustrate the content of the present invention, rather than limiting the protection scope of the claims.

[0036] The performance test methods and standards involved in the following examples: Rockwell hardness GB / T 3849.1-2015.

[0037] Oxidation weight gain per unit area at 800 °C within 10 h: According to the standard GB / T 13303-1991.

[0038] The metal carbide raw materials, metal raw material powders and carbon black involved in the following examples are all conventional commercially available raw materials.

[0039] Example 1

[0040] The metal elements in the solid solution powder raw materials include the following mass percentage contents: W accounts for 5%, Mo accounts for 5%, Ta accounts for 1%, Zr accounts for 0.5%, V accounts for 0.5%, and the rest is Ti powder, measured by the total mass of metal elements of 100%; the atomic number of carbon black is 50% of the total atomic number of metal elements.

[0041] The low-bonding-phase cemented carbide raw materials include the following mass percentage components: Cr 3 C 2 accounts for 0.1%, VC accounts for 0.5%, TaC accounts for 0.5%, Co accounts for 0.5%, carbon black accounts for 0.3%, and the rest is WC, measured by the total mass of 100%.

[0042] The above raw material ratios are used to prepare the titanium carbonitride-based composite ceramic material according to the following method:

[0043] (1) Preparation of low-bonding-phase cemented carbide: Weigh WC, Cr 3 C 2, raw materials such as VC, TaC, Co, and carbon black are ball-milled and mixed. The inner lining of the ball-milling tank is made of cemented carbide, the ball-to-material ratio is 3:1, the ball-milling rate is 200 rpm, the ball-milling time is 24 h, and after ball-milling and mixing, it is sintered by hot isostatic pressing. The sintering temperature is 1700 °C and the time is 1 h to prepare a low-binder-phase cemented carbide block;

[0044] (2) Preparation of solid solution powder: Weigh Ti powder, W powder, Mo powder, Ta powder, Zr powder, V powder and carbon black according to a certain weight percentage, and perform high-energy ball milling in a nitrogen atmosphere. High-energy ball milling adopts dry ball milling. The inner lining of the ball-milling tank is made of cemented carbide, the ball-milling speed is 300 rpm, the ball-to-material ratio is 10:1, and the ball-milling time is 6 h. Before ball milling, the atmosphere in the ball-milling tank is replaced by vacuum pumping and gas filling, filled with positive-pressure nitrogen, and the pressure is 1.2 atmospheres. After high-energy ball milling, solid solution powder is synthesized.

[0045] (3) Sintering preparation and pre-oxidation treatment: Place the solid solution powder prepared in step (2) in a mold, bury the low-binder-phase cemented carbide block prepared in step (1) in the center of the solid solution powder. When the solid solution powder is in a room-temperature compaction state, the unilateral filling thickness is 500 μm, and then sintering is carried out. The sintering method is hot isostatic pressing sintering, the sintering temperature is 2000 °C, and the time is 1 h; after sintering, pre-oxidation treatment is carried out. The pre-oxidation treatment temperature is 600 °C, the time is 30 min, the atmosphere is an oxygen / nitrogen mixed atmosphere, and the volume content of oxygen is 5%, to obtain a titanium carbonitride-based composite ceramic material for aspherical and curved glass molding.

[0046] Performance test results of the titanium carbonitride-based composite ceramic material: hardness HV2000, thermal expansion coefficient 5.5×10 -8 / °C, thermal conductivity 50 W / m·K, oxidation weight gain per unit area at 800 °C is 10×10 -4 mg / mm 2 .

[0047] Example 2

[0048] The metal elements in the solid solution powder raw materials include the following mass percentage contents: W accounts for 10%, Mo accounts for 2%, Ta accounts for 3%, Zr accounts for 2%, V accounts for 0.3%, and the rest is Ti powder, measured based on the total mass of metal elements being 100%; the atomic number of carbon black is 55% of the total atomic number of metal elements.

[0049] The low-binder-phase cemented carbide raw materials include the following mass percentage components: Cr 3 C 2 accounts for 0.5%, VC accounts for 0.2%, TaC accounts for 0.2%, Co accounts for 1.0%, carbon black accounts for 0.4%, and the rest is WC, measured based on the total mass being 100%.

[0050] The above raw material ratio is used to prepare a titanium carbonitride-based composite ceramic material according to the following method:

[0051] (1) Preparation of low-binder-phase cemented carbide: Weigh raw materials such as WC, Cr 3 C 2 , VC, TaC, Co, carbon black, etc., and carry out ball milling and mixing. The inner lining of the ball milling tank is cemented carbide, the ball-to-material ratio is 5:1, the ball milling rate is 250 rpm, the ball milling time is 48 h. After ball milling and mixing, it is sintered by hot isostatic pressing. The sintering temperature is 1900 °C and the time is 2 h to prepare a low-binder-phase cemented carbide block;

[0052] (2) Preparation of solid solution powder: Weigh Ti powder, W powder, Mo powder, Ta powder, Zr powder, V powder and carbon black according to a certain weight percentage, and carry out high-energy ball milling in a nitrogen atmosphere. High-energy ball milling adopts dry ball milling. The inner lining of the ball milling tank is cemented carbide, the ball milling speed is 400 rpm, the ball-to-material ratio is 14:1, and the ball milling time is 4 h. Before ball milling, the atmosphere in the ball milling tank is replaced by vacuum pumping and gas filling, and filled with positive pressure nitrogen with a pressure of 1.5 atmospheres. After high-energy ball milling, a solid solution powder is synthesized.

[0053] (3) Sintering preparation and pre-oxidation treatment: Place the solid solution powder prepared in step (2) in a mold, and bury the low-binder-phase cemented carbide block prepared in step (1) in the center of the solid solution powder. When the solid solution powder is in a room-temperature compaction state, the unilateral filling thickness is 800 μm, and then sintering is carried out. The sintering method is hot isostatic pressing sintering, the sintering temperature is 1900 °C, and the time is 2 hours; after sintering, pre-oxidation treatment is carried out. The pre-oxidation treatment temperature is 800 °C, the time is 90 min, and the atmosphere is an oxygen / nitrogen mixed atmosphere with an oxygen volume content of 10% to obtain a titanium carbonitride-based composite ceramic material for aspherical and curved glass molding.

[0054] Performance test results of the titanium carbonitride-based composite ceramic material: Hardness HV2180, thermal expansion coefficient 5.1×10 -8 / °C, thermal conductivity 54 W / m·K, oxidation weight gain per unit area at 800 °C is 8.5×10 -4 mg / mm 2 .

[0055] Example 3

[0056] The metal elements in the solid solution powder raw materials include the following mass percentage contents: W accounts for 7%, Mo accounts for 3%, Ta accounts for 2%, Zr accounts for 1.5%, V accounts for 0.4%, and the rest is Ti powder, measured based on the total mass of metal elements being 100%; the atomic number of carbon black is 53% of the total atomic number of metal elements.

[0057] The low-binder-phase cemented carbide raw materials include the following mass percentage components: Cr3 C 2 accounts for 0.3%, VC accounts for 0.4%, TaC accounts for 0.4%, Co accounts for 0.8%, carbon black accounts for 0.4%, and the rest is WC, measured based on the total mass of 100%.

[0058] The above raw material ratio is used to prepare the titanium carbonitride-based composite ceramic material according to the following method:

[0059] (1) Preparation of low-binder-phase cemented carbide: Weigh raw materials such as WC, Cr 3 C 2 , VC, TaC, Co, and carbon black, and carry out ball milling and mixing. The inner lining of the ball milling tank is cemented carbide, the ball-to-material ratio is 4:1, the ball milling rate is 220 rpm, the ball milling time is 30 h. After ball milling and mixing, it is sintered by hot isostatic pressing. The sintering temperature is 1800 °C and the time is 1.5 h to prepare a low-binder-phase cemented carbide block;

[0060] (2) Preparation of solid solution powder: Weigh Ti powder, W powder, Mo powder, Ta powder, Zr powder, V powder, and carbon black according to a certain weight percentage, and carry out high-energy ball milling in a nitrogen atmosphere. The high-energy ball milling uses dry ball milling. The inner lining of the ball milling tank is cemented carbide, the ball milling speed is 350 rpm, the ball-to-material ratio is 13:1, and the ball milling time is 5 h. Before ball milling, the atmosphere in the ball milling tank is replaced by vacuum pumping and gas filling, filled with positive pressure nitrogen, and the pressure is 1.3 atmospheres. After high-energy ball milling, a solid solution powder is synthesized.

[0061] (3) Sintering preparation and pre-oxidation treatment: Place the solid solution powder prepared in step (2) in a mold, bury the low-binder-phase cemented carbide block prepared in step (1) in the center of the solid solution powder. When the solid solution powder is in a room temperature compaction state, the unilateral filling thickness is 600 μm, and then sintering is carried out. The sintering method is hot isostatic pressing sintering method, the sintering temperature is 1950 °C, and the time is 1.5; after sintering, pre-oxidation treatment is carried out. The pre-oxidation treatment temperature is 700 °C, the time is 60 min, and the atmosphere is an oxygen / nitrogen mixed atmosphere, and the oxygen volume content is 7%, to obtain a titanium carbonitride-based composite ceramic material for aspherical and curved glass molding.

[0062] Performance test results of the titanium carbonitride-based composite ceramic material: hardness HV2300, thermal expansion coefficient 4.8×10 -8 / °C, thermal conductivity 63 W / m·K, oxidation weight gain per unit area at 800 °C is 2×10 -4 mg / mm 2 .

[0063] Example 4

[0064] The metal elements in the solid solution powder raw material include the following mass percentage contents: W accounts for 6%, Mo accounts for 4%, Ta accounts for 2%, Zr accounts for 1.0%, V accounts for 0.3%, and the rest is Ti powder, measured based on the total mass of the metal elements being 100%; the atomic number of carbon black is 53% of the total atomic number of the metal elements.

[0065] The low-binder-phase cemented carbide raw material includes the following mass percentage components: Cr 3 C 2 accounts for 0.3%, VC accounts for 0.3%, TaC accounts for 0.3%, Co accounts for 0.7%, carbon black accounts for 0.3%, and the rest is WC, measured based on the total mass being 100%.

[0066] The above raw material ratios are used to prepare the titanium carbonitride-based composite ceramic material according to the following method:

[0067] (1) Preparation of the low-binder-phase cemented carbide: Weigh WC, Cr 3 C 2 , VC, TaC, Co, carbon black and other raw materials according to the component ratios, and carry out ball milling and mixing. The inner lining of the ball milling tank is cemented carbide, the ball-to-material ratio is 4:1, the ball milling rate is 220 rpm, the ball milling time is 28 h. After ball milling and mixing, it is sintered by hot isostatic pressing. The sintering temperature is 1850 °C and the time is 1.5 h to prepare a low-binder-phase cemented carbide block.

[0068] (2) Preparation of the solid solution powder: Weigh Ti powder, W powder, Mo powder, Ta powder, Zr powder, V powder and carbon black according to a certain weight percentage, and carry out high-energy ball milling in a nitrogen atmosphere. The high-energy ball milling uses dry ball milling. The inner lining of the ball milling tank is cemented carbide, the ball milling speed is 350 rpm, the ball-to-material ratio is 12:1, and the ball milling time is 5 h. Before ball milling, the atmosphere in the ball milling tank is replaced by vacuum pumping and gas filling, and filled with positive pressure nitrogen with a pressure of 1.4 atmospheres. After high-energy ball milling, a solid solution powder is synthesized.

[0069] (3) Sintering preparation and pre-oxidation treatment: Place the solid solution powder prepared in step (2) in a mold, bury the low-binder-phase cemented carbide block prepared in step (1) in the center of the solid solution powder. When the solid solution powder is in a room-temperature compaction state, the unilateral filling thickness is 700 μm, and then sintering is carried out. The sintering method is hot isostatic pressing sintering, the sintering temperature is 1950 °C, and the time is 1.5 h; after sintering, pre-oxidation treatment is carried out. The pre-oxidation treatment temperature is 700 °C, the time is 50 min, and the atmosphere is an oxygen / nitrogen mixed atmosphere with an oxygen volume content of 8% to obtain a titanium carbonitride-based composite ceramic material for aspherical and curved glass molding.

[0070] Performance test results of the titanium carbonitride-based composite ceramic material: Hardness HV2280, coefficient of thermal expansion 4.6×10 -8 / °C, thermal conductivity 60 W / m·K, oxidation weight gain per unit area at 800°C is 4×10 -4 mg / mm 2 .

[0071] Comparative Example 1

[0072] The heat sink was directly prepared using the solid solution composition of Example 4.

[0073] Hardness HV2280, coefficient of thermal expansion 6.8×10 -8 / °C, thermal conductivity 27 W / m·K, oxidation weight gain per unit area at 800°C is 6×10 -2 mg / mm 2 .

[0074] Comparative Example 2

[0075] Compared with Example 4, the only difference is that the low-binder-phase cemented carbide block prepared in step (1) was buried in the center of the solid solution powder. When the solid solution powder was in a room-temperature compacted state, the unilateral filling thickness was 300 μm.

[0076] Hardness HV2200, coefficient of thermal expansion 4.2×10 -8 / °C, thermal conductivity 62 W / m·K, oxidation weight gain per unit area at 800°C is 7×10 -1 mg / mm 2 .

[0077] Comparative Example 3

[0078] Compared with Example 4, the only difference is the raw material composition of the solid solution powder: the metal elements in the solid solution powder raw material include the following mass percentage contents: W accounts for 2%, Mo accounts for 2%, Ta accounts for 2%, Zr accounts for 1.0%, V accounts for 0.3%, and the rest is Ti powder, measured based on the total mass of the metal elements being 100%; the atomic number of carbon black is 20% of the total atomic number of the metal elements.

[0079] Hardness HV1470, coefficient of thermal expansion 4.7×10 -8 / °C, thermal conductivity 58 W / m·K, oxidation weight gain per unit area at 800°C is 3×10 -1 mg / mm 2 .

Claims

1. A titanium carbonitride-based composite ceramic material, characterized in that: it is composed of a ceramic layer coating a cemented carbide core; the cemented carbide is a low binder phase WC-based cemented carbide; the ceramic layer is a titanium carbonitride-based solid solution; the ceramic layer is obtained by sintering and surface pre-oxidation from raw materials including Ti powder, W powder, Mo powder, Ta powder, Zr powder, V powder and carbon black; the metal elements in the raw materials include the following mass percentage contents: W 5-10%, Mo 2-5%, Ta 1-3%, Zr 0.5-2%, V 0.2-0.5%, and the rest is Ti powder; the atomic number of the carbon black is 50-55% of the total atomic number of the metal elements; The cemented carbide is obtained by sintering raw materials including WC, Cr 3 C 2 , VC, TaC, Co and carbon black; The raw materials include the following components by mass percentage: Cr 3 C 2 0.1 - 0.5%, VC 0.1 - 0.5%, TaC 0.2 - 0.5%, Co 0.5 - 1.0%, carbon black 0.3 - 0.4%, and the balance is WC.

2. A titanium carbonitride-based composite ceramic material according to claim 1, characterized in that: the thickness of the ceramic layer is 300-500 μm.

3. A preparation method of a titanium carbonitride-based composite ceramic material according to any one of claims 1-2, characterized in that: it includes the following steps: 1) After mixing raw materials including WC, Cr 3 C 2 , VC, TaC, Co and carbon black by ball milling, sintering I is carried out to obtain a cemented carbide block; 2) High-energy ball milling the raw materials including Ti powder, W powder, Mo powder, Ta powder, Zr powder, V powder and carbon black in a nitrogen atmosphere to obtain a solid solution powder; 3) After embedding the cemented carbide block in the center of the solid solution powder, carry out sintering II and surface pre-oxidation treatment to obtain the titanium carbonitride-based ceramic material.

4. A preparation method of a titanium carbonitride-based composite ceramic material according to claim 3, characterized in that: the conditions for ball milling and mixing are: the ball-to-material ratio is (3-5):1, the ball milling speed is 200-250 rpm, and the ball milling time is 24-48 h; the conditions for high-energy ball milling are: the nitrogen pressure is 1.2-1.5 atmospheres, the ball milling speed is 300-400 rpm, the ball-to-material ratio is (10-14):1, and the ball milling time is 4-6 h.

5. A preparation method of a titanium carbonitride-based composite ceramic material according to claim 3, characterized in that: sintering I adopts spark plasma sintering, hot isostatic pressing sintering or gas pressure sintering, and the sintering temperature is 1700°C-1900°C; sintering II adopts hot isostatic pressing sintering, hot pressing sintering or spark plasma sintering. When adopting hot isostatic pressing sintering or hot pressing sintering, the sintering temperature is 1900°C-2000°C and the time is 1 h-2 h; when adopting spark plasma sintering, the sintering temperature is 1700°C-1900°C and the time is 10 min-20 min; the conditions for the surface pre-oxidation treatment are: the temperature is 600°C-800°C, the time is 30 min-90 min, the atmosphere is an oxygen / nitrogen mixed atmosphere, and the volume content of oxygen is 5-10%.

6. An application of a titanium carbonitride-based composite ceramic material according to any one of claims 1-2, characterized in that: it is applied to the preparation of a mold core for precision glass molding.