High-strength metal / carbon ceramic composite resistor and method for manufacturing the same

Abstract

The application belongs to the technical field of high-voltage power electronic components, and discloses a high-strength metal / carbon ceramic composite resistor and a preparation method thereof. The high-strength metal / carbon ceramic composite resistor is formed by sequentially and closely connecting an electrically conductive layer, a functional layer and the electrically conductive layer from top to bottom. The functional layer is formed by sintering and compounding ceramic phase material, metal conductive phase material, carbon conductive phase material and additives in a mass ratio of (52-88):(7-43):(1-5):(1-6). The metal conductive phase material is one or more of titanium diboride, titanium aluminum carbide, zirconium diboride and niobium diboride. The carbon conductive phase material is graphene or the like. The additive is magnesium oxide or the like. The application provides a new way for a high-volume heat capacity and high-compressive strength resistor. The obtained high-strength metal / carbon ceramic composite resistor can be particularly applied in closing resistors (such as circuit breakers).

Description

Technical Field

[0001] This invention belongs to the field of high-voltage power electronic components technology, and more specifically, relates to a high-strength metal / carbon ceramic composite resistor and its preparation method. Background Technology

[0002] Ultra-high voltage (UHV) and extra-high voltage (UHV) power systems utilize long-distance, high-capacity power transmission technologies to promote energy pattern optimization and the integration of new energy sources. UHV and UHV switches play a crucial role in power systems by rapidly interrupting current and isolating faults.

[0003] To ensure the safe and stable operation of ultra-high voltage (UHV) transmission systems, extremely high requirements are placed on the performance of closing resistors in critical equipment. Closing resistors are key protective devices for UHV / EHV circuit breakers, used to limit closing overvoltage and inrush current, ensuring the safety of power grid equipment. Morgan Company in the UK has studied the composition design, preparation technology, and service behavior of carbon ceramic resistors, developing HVR-type carbon ceramic resistors with high volumetric heat capacity and high compressive strength, which can be used in circuit breakers. In recent years, institutions such as the Shanghai Institute of Ceramics, Xi'an Jiaotong University, and Xi'an University of Architecture and Technology have studied the preparation technology of carbon ceramic materials with carbon black / graphite as the single conductive phase and clay / alumina as the matrix, as well as methods for controlling their thermal, mechanical, and electrical properties. However, the carbon black / graphite single conductive phase has low conductivity and mechanical strength, poor interfacial compatibility with the ceramic matrix, and high porosity. While increasing its content can improve conductivity, it significantly reduces mechanical strength, making it difficult to simultaneously achieve the high specific heat capacity and high mechanical properties of carbon ceramic resistors.

[0004] Furthermore, the traditional preparation process of ceramic resistors mainly includes three basic steps: mechanical mixing of ceramic phase materials and conductive phase materials, molding the mixed powder into a green body, and high-temperature sintering to achieve densification. While the preparation method seems simple, the details of the process are key technical bottlenecks limiting the performance and product yield of ceramic resistors. These bottlenecks are mainly reflected in the following aspects: First, the resistivity deviation of different batches of samples obtained using the same preparation method is large, resulting in a low yield (even using the same batch of raw materials, repeated preparations often result in resistivity deviations exceeding ±10% from the nominal resistance, leading to sample failure); second, the agglomeration of the conductive phase during the powder mixing stage leads to dispersed resistivity distribution and uneven densification; and third, the material formulation cannot achieve the expected thermal and mechanical properties, making long-term use difficult.

[0005] Therefore, there is an urgent need to develop ceramic resistors with high volumetric heat capacity and high mechanical strength to promote the application of high-performance closing resistors. Summary of the Invention

[0006] In view of the above-mentioned defects or improvement needs of the prior art, the purpose of this invention is to provide a high-strength metal / carbon ceramic composite resistor and its preparation method, which provides a new approach for resistors with high volumetric heat capacity and high compressive strength. The obtained high-strength metal / carbon ceramic composite resistor can be used in closing resistors (e.g., circuit breakers).

[0007] To achieve the above objectives, according to a first aspect of the present invention, a high-strength metal / carbon ceramic composite resistor is provided, which is formed by three layers—a conductive layer, a functional layer, and a conductive layer—connected tightly from top to bottom. The functional layer is formed by sintering a uniformly mixed ceramic phase material, a metal conductive phase material, a carbon conductive phase material, and additives in a mass ratio of (52-88):(7-43):(1-5):(1-6). The metal conductive phase material is one or more of titanium diboride, titanium aluminum carbon, zirconium diboride, and niobium diboride. The carbon conductive phase material is one or more of graphene, graphene oxide, fibrous graphite, flake graphite, and carbon black. The additives are one or more of magnesium oxide, titanium oxide, zirconium oxide, boron nitride, aluminum nitride, basalt fiber, carbon nanotubes, carbon fibers, potassium carbonate, and calcium carbonate.

[0008] According to a second aspect of the present invention, a method for preparing the above-mentioned high-strength metal / carbon ceramic composite resistor is provided, comprising the following steps: (1) The ceramic phase material, the metallic conductive phase material, the carbon conductive phase material, and the additives are pre-dried to obtain dried raw materials; (2) The dried raw materials of ceramic phase material, metal conductive phase material, carbon conductive phase material and additive are mixed together with the dispersant, and then ball-milled to obtain a mixed system; (3) The mixture obtained in step (2) is cold-pressed to obtain a preformed green body; (4) The preform obtained in step (3) is subjected to cold isostatic pressing to obtain a green blank; (5) The green body obtained in step (4) is subjected to debinding treatment in a non-oxidizing protective gas atmosphere, followed by carbon embedding sintering to obtain a high-strength metal / carbon ceramic sample. (6) After polishing the sample obtained in step (5), a conductive layer is coated and heated to cure, and a high-strength metal / carbon ceramic composite resistor can be obtained.

[0009] According to a third aspect of the present invention, a method for preparing the above-mentioned high-strength metal / carbon ceramic composite resistor is provided, comprising the following steps: S1: The ceramic phase material, the metallic conductive phase material, the carbon conductive phase material, and the additives are pre-dried to obtain dried raw materials; S2: The dried raw materials of ceramic phase material, metallic conductive phase material, carbon conductive phase material and additive are mixed together with the dispersant, and then ball-milled to obtain a mixed system. S3: The mixed system obtained in step S2 is subjected to discharge plasma sintering or hot pressing sintering in a non-oxidizing protective gas atmosphere to obtain a high-strength metal / carbon ceramic sample. S4: After polishing the sample obtained in step S3, coat it with a conductive layer and heat it to cure, and a high-strength metal / carbon ceramic composite resistor can be obtained.

[0010] As a further preferred embodiment of the present invention, in step (1) or step S1, the ceramic phase material is one or more of alumina, kaolin, silicon dioxide, mullite, pyrophyllite, muscovite, halloysite, illite, and porcelain stone. The dispersant is one or more of the following: anhydrous ethanol, oleic acid, polyvinyl alcohol, triethanolamine, sodium hexametaphosphate, stearic acid, talc, deionized water, anhydrous methanol, acetone, and kerosene.

[0011] As a further preferred embodiment of the present invention, in step (1) or step S1, the drying temperature is 90-150℃ and the drying time is 1-4h. In step (2) or step S2, the mass of the dispersant is 1-8% of the total mass of the ceramic phase material, the metallic conductive phase material, the carbon conductive phase material, and the additive; The ball milling process involves a mixing time of 4-12 hours and a milling speed of 200-400 rpm.

[0012] As a further preferred embodiment of the present invention, in step (3), the molding pressure used for cold pressing is 50-250 MPa, and the molding time is 1-5 min; In step (4), the molding pressure of cold isostatic pressing is 50-250 MPa, and the molding time is 5-15 min.

[0013] As a further preferred embodiment of the present invention, the carbon embedding sintering in step (5) is carried out in a non-oxidizing protective gas atmosphere. First, the temperature is heated to 500-600℃ and held for 1-3 hours for debinding treatment, then heated to 1150-1400℃ and held for 0.5-3 hours, then cooled to 600-800℃ and held for 4-12 hours for annealing treatment, and finally cooled down.

[0014] As a further preferred embodiment of the present invention, step (5) specifically involves first heating to 500-600°C at a heating rate of 5-10°C / min and holding at that temperature for 1-3 hours for debinding; then heating to 1150-1400°C at a heating rate of 1-5°C / min and holding at that temperature for 0.5-3 hours; followed by cooling to 600-800°C at a cooling rate of 1-3°C / min and holding at that temperature for 4-12 hours for annealing. The cooling process involves first cooling the furnace to 200°C at a rate of 1-5°C / min, and then cooling it to room temperature along with the furnace.

[0015] As a further preferred embodiment of the present invention, when spark plasma sintering is used in step S3, the spark plasma sintering is carried out in a non-oxidizing protective gas atmosphere, the sintering temperature is 900-1100℃, the pressure is 30-50MPa, the holding time is 5-10min, and the furnace is cooled to room temperature after sintering. When hot pressing sintering is used in step S3, the hot pressing sintering is carried out in a non-oxidizing protective gas atmosphere, the sintering temperature is 1100-1400℃, the pressure is 10-30MPa, the holding time is 0.5-2h, and the furnace is cooled to room temperature after sintering.

[0016] As a further preferred embodiment of the present invention, the non-oxidizing protective gas atmosphere is pure argon or an argon-hydrogen mixture.

[0017] As a further preferred embodiment of the present invention, in step (6) or step S4, the conductive layer is silver paste, and the coating thickness of each layer of silver paste is 8-12 μm; the heating temperature used for the heat curing is 150-300℃, and the heat preservation time is 1-4h.

[0018] According to a fourth aspect of the present invention, the present invention provides the application of the above-mentioned high-strength metal / carbon ceramic composite resistor in closing resistors.

[0019] Compared with existing technologies, the technical solution conceived in this invention uses ceramic phase materials, metallic conductive phase materials, carbon conductive phase materials, and additives as raw materials. Each raw material is pre-dried, and a dispersant is used. A composite process design of ball milling-forming-sintering is employed (forming and sintering can be completed in the same process) to form a metallic / carbon composite conductive phase, creating a three-dimensional isotropic network structure without orientation dependence, improving mechanical properties, and obtaining a high-strength metallic / carbon ceramic composite resistor. The metallic / carbon composite conductive phase material obtained by this invention possesses both high conductivity and high thermal conductivity. Compared with traditional single carbon conductive phases, the composite conductive phase has better wettability with the matrix, optimizing interface defects. The thermal expansion coefficient of the composite conductive phase is closer to that of the matrix, promoting sintering densification and increasing the overall density of the sample. The composite conductive phase combined with the process can form a uniform three-dimensional conductive network, avoiding performance anisotropy caused by raw material morphology and agglomeration. The formation of the composite conductive phase also makes the conductive phase more stable, less prone to decomposition reactions, and improves the yield rate.

[0020] This invention can particularly utilize alumina, kaolin, and silicon dioxide as ceramic phase materials; titanium diboride, titanium aluminum carbon, zirconium diboride, and niobium diboride as metallic conductive phase materials; graphene, graphene oxide, fibrous graphite, flake graphite, and carbon black as carbon conductive phase materials; and magnesium oxide, titanium oxide, zirconium oxide, boron nitride, aluminum nitride, basalt fiber, carbon nanotubes, carbon fiber, potassium carbonate, and calcium carbonate as additives (these all have the characteristics of lowering sintering temperature, promoting liquid-phase sintering, reducing process difficulty, improving repeatability, and contributing to sintering densification; these additives, such as magnesium oxide, titanium oxide, potassium carbonate, and calcium carbonate, also react with the matrix). The process involves various additives to optimize the phase structure through bio-reactions. Boron nitride and aluminum nitride dominate heat transfer, regulate thermal conductivity / thermal diffusivity, and improve thermodynamic properties. Basalt fibers and carbon fibers address ceramic brittleness and enhance strength and toughness through fiber pull-out and crack bridging / deflection mechanisms. Carbon nanotubes and carbon fibers can also construct continuous conductive pathways, precisely regulate resistivity and temperature coefficient, and optimize thermal expansion and heat storage characteristics. Zirconia and titanium oxide alter the average thermal expansion coefficient of the system, alleviate interphase thermal mismatch, reduce residual internal stress, and improve dimensional stability. This process yields high-strength metal / carbon ceramic composite resistors. Pre-drying ensures stable bound water / free water content in the raw materials. Meanwhile, the present invention preferably controls the mass ratio of ceramic phase material, metal conductive phase material, carbon conductive phase material and additives in the total mass of these four components to be (52-88%): (7-43%): (1-5%): (1-6%). Titanium diboride, titanium aluminum carbon, zirconium diboride, niobium diboride, graphene, graphene oxide, fibrous graphite, flake graphite and carbon black, as metal / carbon composite conductive phase materials, can form a dense composite phase with the ceramic matrix to effectively improve the thermal and mechanical properties of the material.

[0021] This invention utilizes a combination of metallic conductive phase materials and carbon conductive phase materials with ceramic phase materials and additives. The mass ratio of these four materials is controlled at (52-88):(7-43):(1-5):(1-6). The metallic conductive phase material provides a continuous granular conductive substrate, while the carbon conductive phase material fills the gaps across multiple scales over a long distance. Thus, a small amount of carbon conductive phase material is sufficient to form a continuous conductive network. Furthermore, the temperature effects of the two conductive phase materials, metallic and carbon conductive phase materials, compensate for each other, effectively reducing the overall temperature coefficient of resistance and achieving stable resistance at low temperatures. The metallic conductive phase material has a relatively high coefficient of thermal expansion, while the various carbon conductive phase materials have weak interlayer bonding and extremely low axial / in-plane thermal expansion. After the two phases are mixed, the low-expansion carbon phase is uniformly dispersed within the matrix, constraining the high-temperature deformation of the metallic conductive phase. This results in a lower coefficient of thermal expansion for the overall composite material, alleviating residual internal stress caused by thermal mismatch between different phases and improving the material's thermal shock resistance. Meanwhile, the metallic conductive phase dispersed in the matrix produces grain boundary pinning and grain toughening, which improves hardness and compressive strength. The carbon conductive phase relies on multiple toughening mechanisms such as lamellar slip, fiber pull-out, and crack deflection to passivate crack tips, inhibit rapid crack propagation, and make up for the high brittleness of the metallic conductive phase, thus achieving a balance of "high strength + high toughness".

[0022] Furthermore, this invention preferably uses titanium diboride, titanium aluminum carbon, zirconium diboride, and niobium diboride as conductive phase materials, which possess antioxidant and decomposition-resistant properties, facilitating long-term use. These conductive phase materials also have ceramic reinforcing effects, forming a dense composite phase with the ceramic matrix to prevent cracking. Moreover, these conductive phase materials exhibit strong chemical inertness and good electrical resistance stability.

[0023] The high-strength metal / carbon ceramic composite resistor obtained by the method of this invention has the characteristics of high strength, with a compressive strength of not less than 282.2 MPa and a flexural strength of not less than 88.0 MPa; and a volumetric specific heat capacity higher than 2.04 J / (cm³). 3 It has the characteristics of high volumetric heat capacity and high mechanical properties. Attached Figure Description

[0024] Figure 1 This is a flowchart of the process for preparing a high-strength metal / carbon ceramic composite resistor according to the present invention.

[0025] Figure 2 This is the SEM image of Comparative Example 1 of this invention.

[0026] Figure 3 These are SEM images of the products from Examples 1-4 of this invention, wherein... Figure 3 (a) in the text corresponds to the product of Example 1. Figure 3(b) in the text corresponds to the product of Example 2. Figure 3 (c) in the text corresponds to the product of Example 3. Figure 3 (d) in the example corresponds to the product of Example 4. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0028] The ceramic phase materials (such as alumina, kaolin, silicon dioxide, mullite, pyrophyllite, muscovite, halloysite, illite, and porcelain stone) used in the following examples have a purity of not less than 95%; the metallic conductive phase materials (such as titanium diboride, titanium aluminum carbon, zirconium diboride, and niobium diboride), carbon conductive phase materials (such as graphene, graphene oxide, fibrous graphite, flake graphite, and carbon black), additives (such as magnesium oxide, titanium oxide, zirconium oxide, boron nitride, aluminum nitride, basalt fiber, carbon nanotubes, carbon fiber, potassium carbonate, and calcium carbonate), and dispersants (such as anhydrous ethanol, oleic acid, polyvinyl alcohol, triethanolamine, sodium hexametaphosphate, stearic acid, talc, deionized water, anhydrous methanol, acetone, and kerosene) all have a purity of not less than 99.9% and are all commercially available.

[0029] Example 1 (1) The raw materials such as kaolin, alumina, titanium diboride, titanium aluminum carbon, fiber graphite, magnesium oxide, titanium oxide, zirconium oxide, and boron nitride are pre-dried in a special oven for 1 hour at a drying temperature of 150℃.

[0030] (2) Take out the dried sample from step (1), accurately weigh 29 wt.% kaolin, 23 wt.% alumina, 20 wt.% titanium diboride, 23 wt.% titanium aluminum carbon, 1 wt.% fiber graphite, 1 wt.% magnesium oxide, 1 wt.% titanium oxide, 1 wt.% zirconium oxide, and 1 wt.% boron nitride, add 1 wt.% stearic acid of total mass and mix and ball mill (ball-to-material mass ratio is 15:1, the same below). The ball mill speed is 400 rpm. The ball mill is reversed every 60 min during the ball milling process, with an interval of 30 min. The mixing time (excluding the intermediate interval time; the same below) is 4 h.

[0031] (3) Grind the uniformly mixed system from step (2), and after the process is complete, put it into a mold and cold press it into a preform. Apply pressure of 50 MPa and hold for 5 minutes. After demolding, quickly seal and store the preform.

[0032] (4) The preform obtained in step (3) is placed into the oil cavity for cold isostatic pressing to obtain the preform. The pressure is applied at 250 MPa and the holding time is 15 min. After the preform is demolded, it is quickly sealed and stored.

[0033] (5) The green body obtained in step (4) is buried in a corundum crucible containing carbon black at room temperature so that the carbon black completely covers the green body for subsequent carbon embedding sintering (the carbon embedding sintering used in the following examples all adopt similar operations). The crucible is then placed in a tube furnace to prepare for carbon embedding sintering. The sintering is heated to 500°C at a heating rate of 5°C / min and held for 3 hours for debinding treatment. Then, it is heated to 1400°C at a heating rate of 5°C / min and held for 0.5 hours. Then, it is cooled to 800°C at a cooling rate of 1°C / min and held for 4 hours for annealing treatment. Finally, it is cooled to 200°C at a cooling rate of 5°C / min and then cooled with the furnace. Argon gas is introduced throughout the process as a protective gas to obtain the sample.

[0034] (6) Take the sample obtained in step (5) out of the corundum crucible, polish the surface with 200, 400, 600 and 1200 grit sandpaper, coat the upper and lower surfaces with conductive silver paste, each layer of silver paste is 8 μm thick, and keep it at 150°C for 4 h in a box furnace to obtain a high-strength metal / carbon ceramic composite resistor.

[0035] Example 2 (1) The raw materials such as kaolin, silicon dioxide, zirconium diboride, graphene, and aluminum nitride are pre-dried in a special oven for 4 hours at a drying temperature of 90℃.

[0036] (2) Take out the dried sample from step (1), accurately weigh 49wt.% kaolin, 39wt.% silicon dioxide, 6wt.% zirconium diboride, 5wt.% graphene, and 1wt.% aluminum nitride, add 8wt.% anhydrous ethanol and mix and ball mill. The ball mill speed is 200rpm. The direction is reversed every 60min during the ball milling process, with an interval of 0min (i.e., no interval). The mixing time is 12h.

[0037] (3) Grind the mixture from step (2) until it is uniformly mixed. After the mixture is processed, put it into a mold and press it into a preform. Apply pressure of 250 MPa and hold for 1 minute. After the preform is demolded, quickly seal it for preservation.

[0038] (4) The preform obtained in step (3) is placed into the oil cavity for cold isostatic pressing to obtain the preform. The pressure is applied at 250 MPa and the holding time is 5 min. After the preform is demolded, it is quickly sealed and stored.

[0039] (5) The green blank obtained in step (4) is buried in a corundum crucible, and then the crucible is placed in a tube furnace to prepare for carbon sintering. The sintering is heated to 600°C at a heating rate of 5°C / min and held for 1 hour for debinding. Then it is heated to 1150°C at a heating rate of 5°C / min and held for 3 hours. Then it is cooled to 600°C at a cooling rate of 1°C / min and held for 12 hours for annealing. Finally, it is cooled to 200°C at a cooling rate of 5°C / min and then cooled with the furnace. Argon gas is introduced throughout the process as a protective gas to obtain the sample.

[0040] (6) Take the sample obtained in step (5) out of the corundum crucible, polish the surface with 200, 400, 600 and 1200 grit sandpaper, coat the upper and lower surfaces with conductive silver paste, each layer of silver paste is 8 μm thick and keep it at 300℃ for 1 h in a box furnace to obtain a high-strength metal / carbon ceramic composite resistor.

[0041] Example 3 (1) The raw materials such as mullite, kaolin, niobium diboride, graphene, carbon nanotubes, carbon fibers, magnesium oxide, and titanium oxide are pre-dried in a special oven for 3 hours at a drying temperature of 110℃.

[0042] (2) Take out the dried sample from step (1), accurately weigh 50wt.% mullite, 34wt.% kaolin, 7wt.% niobium diboride, 5wt.% graphene, 1wt.% carbon nanotubes, 1wt.% carbon fiber, 1wt.% magnesium oxide, and 1wt.% titanium oxide, add 2wt.% deionized water and mix and ball mill. The ball mill speed is 300rpm. The direction is changed every 60min during the ball milling process, with an interval of 5min. The mixing time is 8h.

[0043] (3) Grind the uniformly mixed system from step (2), and after the process is complete, put it into a mold and cold press it into a preform. Apply pressure of 50 MPa and hold for 5 minutes. After demolding, quickly seal and store the preform.

[0044] (4) The preform obtained in step (3) is placed into the oil cavity for cold isostatic pressing to obtain the preform. The pressure is applied at 50 MPa and the holding time is 15 min. After the preform is demolded, it is quickly sealed and stored.

[0045] (5) The green blank obtained in step (4) is buried in a corundum crucible, and then the crucible is placed in a tube furnace to prepare for carbon sintering. The sintering is heated to 600°C at a heating rate of 5°C / min and held for 1 hour for debinding. Then it is heated to 1250°C at a heating rate of 5°C / min and held for 3 hours. Then it is cooled to 600°C at a cooling rate of 1°C / min and held for 12 hours for annealing. Finally, it is cooled to 200°C at a cooling rate of 5°C / min and then cooled with the furnace. Argon-hydrogen mixture is introduced as a protective gas throughout the process (the volume ratio of Ar to H2 is 95:5; the same below) to obtain the sample.

[0046] (6) Take the sample obtained in step (5) out of the corundum crucible, polish the surface with 200, 400, 600 and 1200 grit sandpaper, coat the upper and lower surfaces with conductive silver paste, each layer of silver paste is 8 μm thick and keep it at 300℃ for 1 h in a box furnace to obtain a high-strength metal / carbon ceramic composite resistor.

[0047] Example 4 (1) Pyrophyllite, muscovite, titanium diboride, titanium aluminum carbon, graphene oxide, magnesium oxide, titanium oxide, carbon nanotubes, carbon fiber, potassium carbonate, calcium carbonate and other raw materials are pre-dried in a special oven for 2 hours at a drying temperature of 110℃.

[0048] (2) Take out the dried sample from step (1), accurately weigh 20 wt.% pyrophyllite, 35 wt.% muscovite, 17 wt.% titanium diboride, 17 wt.% titanium aluminum carbon, 5 wt.% graphene oxide, 1 wt.% magnesium oxide, 1 wt.% titanium oxide, 1 wt.% carbon nanotubes, 1 wt.% carbon fiber, 1 wt.% potassium carbonate, and 1 wt.% calcium carbonate, add 5 wt.% kerosene by total mass and mix and ball mill. The ball mill speed is 300 rpm. The direction is changed once every 60 min during the ball milling process, with an interval of 5 min. The mixing time is 6 h.

[0049] (3) Grind the mixture system from step (2) until it is uniformly mixed. After the process is complete, put it into a mold and press it into a preform. Apply pressure of 150 MPa and hold for 5 minutes. After demolding, quickly seal and store the preform.

[0050] (4) The preform obtained in step (3) is placed into the oil cavity for cold isostatic pressing to obtain the preform. The pressure is applied at 150 MPa and the holding time is 10 min. After the preform is demolded, it is quickly sealed and stored.

[0051] (5) The green blank obtained in step (4) is buried in a corundum crucible, and then the crucible is placed in a tube furnace to prepare for carbon sintering. The sintering is heated to 600°C at a heating rate of 10°C / min and held for 1 hour for debinding. Then it is heated to 1200°C at a heating rate of 1°C / min and held for 2 hours. Then it is cooled to 800°C at a cooling rate of 3°C / min and held for 6 hours for annealing. Finally, it is cooled to 200°C at a cooling rate of 1°C / min and then cooled with the furnace. Argon gas is introduced throughout the process as a protective gas to obtain the sample.

[0052] (6) Take the sample obtained in step (5) out of the corundum crucible, polish the surface with 200, 400, 600 and 1200 grit sandpaper, coat the upper and lower surfaces with conductive silver paste, each layer of silver paste is 12 μm thick, and keep it at 250℃ for 2 hours in a box furnace to obtain a high-strength metal / carbon ceramic composite resistor.

[0053] Example 5 (1) Dry the raw materials such as halloysite, illite, titanium diboride, titanium aluminum carbon, fiber graphite, magnesium oxide, and basalt fiber in a special oven for 2 hours at a drying temperature of 110℃.

[0054] (2) Take out the dried sample from step (1), accurately weigh 28 wt.% halloysite, 35 wt.% illite, 27 wt.% titanium diboride, 3 wt.% titanium aluminum carbon, 5 wt.% fiber graphite, 1 wt.% magnesium oxide, and 1 wt.% basalt fiber, add 3 wt.% oleic acid of total mass and mix and ball mill. The ball mill speed is 250 rpm. The direction is changed once every 60 min during the ball milling process, with an interval of 10 min. The mixing time is 8 h.

[0055] (3) Grind the mixture system from step (2) until it is uniformly mixed. After the process is complete, put it into a mold and press it into a preform. Apply pressure of 200 MPa and hold for 3 minutes. After demolding, quickly seal and store the preform.

[0056] (4) The preform obtained in step (3) is placed into the oil cavity for cold isostatic pressing to obtain the preform. The pressure is applied at 200 MPa and the holding time is 5 min. After the preform is demolded, it is quickly sealed and stored.

[0057] (5) The green blank obtained in step (4) is buried in a corundum crucible, and then the crucible is placed in a tube furnace to prepare for carbon sintering. The sintering is heated to 600°C at a heating rate of 10°C / min and held for 2 hours for debinding. Then it is heated to 1250°C at a heating rate of 5°C / min and held for 2 hours. Then it is cooled to 800°C at a cooling rate of 3°C / min and held for 6 hours for annealing. Finally, it is cooled to 200°C at a cooling rate of 5°C / min and then cooled with the furnace. Argon gas is introduced throughout the process as a protective gas to obtain the sample.

[0058] (6) Take the sample obtained in step (5) out of the corundum crucible, polish the surface with 200, 400, 600 and 1200 grit sandpaper, coat the upper and lower surfaces with conductive silver paste, each layer of silver paste is 12 μm thick and keep it at 200℃ for 3 h in a box furnace to obtain a high-strength metal / carbon ceramic composite resistor.

[0059] Example 6 (1) The raw materials such as porcelain stone, kaolin, titanium diboride, titanium aluminum carbon, fiber graphite, magnesium oxide, and basalt fiber are pre-dried in a special oven for 2 hours at a drying temperature of 120℃.

[0060] (2) Take out the dried sample from step (1), accurately weigh 30 wt.% porcelain stone, 30 wt.% kaolin, 27 wt.% titanium diboride, 6 wt.% titanium aluminum carbon, 5 wt.% fiber graphite, 1 wt.% magnesium oxide, and 1 wt.% basalt fiber, add a total mass of 4 wt.% ethanol-water mixed solution (the volume ratio of ethanol to water in the ethanol-water mixed solution is 1:1), and then mix and ball mill. The ball mill speed is 350 rpm. During the ball milling process, the direction is changed once every 60 min, with an interval of 15 min. The mixing time is 6 h.

[0061] (3) Grind the mixture system from step (2) until it is uniformly mixed. After the process is complete, put it into a mold and press it into a preform. Apply pressure of 200 MPa and hold for 5 minutes. After demolding, quickly seal and store the preform.

[0062] (4) The preform obtained in step (3) is placed into the oil cavity for cold isostatic pressing to obtain the preform. The pressure is applied at 200 MPa and the holding time is 8 minutes. After the preform is demolded, it is quickly sealed and stored.

[0063] (5) The green blank obtained in step (4) is buried in a corundum crucible, and then the crucible is placed in a tube furnace to prepare for carbon sintering. The sintering is heated to 600°C at a heating rate of 8°C / min and held for 2 hours for debinding. Then it is heated to 1350°C at a heating rate of 3°C / min and held for 1 hour. Then it is cooled to 700°C at a cooling rate of 2°C / min and held for 8 hours for annealing. Finally, it is cooled to 200°C at a cooling rate of 3°C / min and then cooled with the furnace. Argon-hydrogen mixture is introduced as a protective gas throughout the process to obtain the sample.

[0064] (6) Take the sample obtained in step (5) out of the corundum crucible, polish the surface with 200, 400, 600 and 1200 grit sandpaper, coat the upper and lower surfaces with conductive silver paste, each layer of silver paste is 12 μm thick, and keep it at 300℃ for 2 hours in a box furnace to obtain a high-strength metal / carbon ceramic composite resistor.

[0065] Example 7 (1) The raw materials such as alumina, kaolin, titanium aluminum carbon, fiber graphite, magnesium oxide, and carbon nanotubes are pre-dried in a special oven for 2 hours at a drying temperature of 120℃.

[0066] (2) Take out the dried sample from step (1), accurately weigh 25wt.% alumina, 28wt.% kaolin, 40wt.% titanium aluminum carbon, 5wt.% fiber graphite, 1wt.% magnesium oxide, and 1wt.% carbon nanotubes, add 6wt.% anhydrous methanol and mix and ball mill. The ball mill speed is 400rpm. The direction is changed every 60min during the ball milling process, with an interval of 25min. The mixing time is 4h.

[0067] (3) Grind the uniformly mixed system from step (2), and after the process is complete, put it into a mold and cold press it into a preform. Apply pressure of 250 MPa and hold for 3 minutes. After the preform is demolded, quickly seal it for preservation.

[0068] (4) The preform obtained in step (3) is placed into the oil cavity for cold isostatic pressing to obtain the preform. The pressure is applied at 250 MPa and the holding time is 7 minutes. After the preform is demolded, it is quickly sealed and stored.

[0069] (5) The green blank obtained in step (4) is buried in a corundum crucible, and then the crucible is placed in a tube furnace to prepare for carbon sintering. The sintering is heated to 500°C at a heating rate of 6°C / min and held for 2 hours for debinding. Then it is heated to 1300°C at a heating rate of 3°C / min and held for 2.5 hours. Then it is cooled to 800°C at a cooling rate of 2°C / min and held for 4 hours for annealing. Finally, it is cooled to 200°C at a cooling rate of 2°C / min and then cooled with the furnace. Argon gas is introduced throughout the process as a protective gas to obtain the sample.

[0070] (6) Take the sample obtained in step (5) out of the corundum crucible, polish the surface with 200, 400, 600 and 1200 grit sandpaper, coat the upper and lower surfaces with conductive silver paste, each layer of silver paste is 10 μm thick, and keep it at 200℃ for 3 h in a box furnace to obtain a high-strength metal / carbon ceramic composite resistor.

[0071] Example 8 (1) The raw materials such as silicon dioxide, muscovite, titanium diboride, niobium diboride, fiber graphite, titanium dioxide, and potassium carbonate are pre-dried in a special oven for 2 hours at a drying temperature of 120℃.

[0072] (2) Take out the dried sample from step (1), accurately weigh 25 wt.% silicon dioxide, 28 wt.% muscovite, 35 wt.% titanium diboride, 5 wt.% niobium diboride, 5 wt.% fibrous graphite, 1 wt.% titanium dioxide, and 1 wt.% potassium carbonate, add 2 wt.% talc powder of total mass and mix and ball mill. The ball mill speed is 250 rpm. The direction is changed once every 60 min during the ball milling process, with an interval of 10 min. The mixing time is 12 h.

[0073] (3) Grind the mixture system from step (2) until it is uniformly mixed. After the process is complete, put it into a mold and press it into a preform. Apply pressure of 170 MPa and hold for 5 minutes. After demolding, quickly seal and store the preform.

[0074] (4) The preform obtained in step (3) is placed into the oil cavity for cold isostatic pressing to obtain the preform. The pressure is applied at 180 MPa and the holding time is 8 minutes. After the preform is demolded, it is quickly sealed and stored.

[0075] (5) The green blank obtained in step (4) is buried in a corundum crucible, and then the crucible is placed in a tube furnace to prepare for carbon sintering. The sintering is heated to 500°C at a heating rate of 5°C / min and held for 3 hours for debinding. Then it is heated to 1300°C at a heating rate of 5°C / min and held for 2 hours. Then it is cooled to 600°C at a cooling rate of 3°C / min and held for 8 hours for annealing. Finally, it is cooled to 200°C at a cooling rate of 5°C / min and then cooled with the furnace. Argon gas is introduced throughout the process as a protective gas to obtain the sample.

[0076] (6) Take the sample obtained in step (5) out of the corundum crucible, polish the surface with 200, 400, 600 and 1200 grit sandpaper, coat the upper and lower surfaces with conductive silver paste, each layer of silver paste is 10 μm thick, and keep it at 300℃ for 2 hours in a box furnace to obtain a high-strength metal / carbon ceramic composite resistor.

[0077] Example 9 (1) The raw materials such as silicon dioxide, muscovite, titanium diboride, titanium aluminum carbon, fiber graphite, titanium dioxide, and potassium carbonate are pre-dried in a special oven for 3 hours at a drying temperature of 100℃.

[0078] (2) Take out the dried sample from step (1), accurately weigh 25 wt.% silicon dioxide, 28 wt.% muscovite, 35 wt.% titanium diboride, 5 wt.% titanium aluminum carbon, 5 wt.% fiber graphite, 1 wt.% titanium dioxide, and 1 wt.% potassium carbonate, add 1 wt.% triethanolamine of total mass and mix and ball mill. The ball mill speed is 250 rpm. The direction is changed once every 60 min during the ball milling process, with an interval of 10 min. The mixing time is 12 h.

[0079] (3) Grind the mixture system from step (2) until it is uniformly mixed. After the process is complete, put it into a mold and press it into a preform. Apply pressure of 170 MPa and hold for 5 minutes. After demolding, quickly seal and store the preform.

[0080] (4) The preform obtained in step (3) is placed into the oil cavity for cold isostatic pressing to obtain the preform. The pressure is applied at 180 MPa and the holding time is 8 minutes. After the preform is demolded, it is quickly sealed and stored.

[0081] (5) The green blank obtained in step (4) is buried in a corundum crucible, and then the crucible is placed in a tube furnace to prepare for carbon sintering. The sintering is heated to 500°C at a heating rate of 5°C / min and held for 3 hours for debinding. Then it is heated to 1300°C at a heating rate of 5°C / min and held for 2 hours. Then it is cooled to 600°C at a cooling rate of 3°C / min and held for 8 hours for annealing. Finally, it is cooled to 200°C at a cooling rate of 5°C / min and then cooled with the furnace. Argon gas is introduced throughout the process as a protective gas to obtain the sample.

[0082] (6) Take the sample obtained in step (5) out of the corundum crucible, polish the surface with 200, 400, 600 and 1200 grit sandpaper, coat the upper and lower surfaces with conductive silver paste, each layer of silver paste is 10 μm thick, and keep it at 300℃ for 2 hours in a box furnace to obtain a high-strength metal / carbon ceramic composite resistor.

[0083] Example 10 (1) The raw materials such as kaolin, muscovite, titanium aluminum carbon, flake graphite, titanium oxide, potassium carbonate, and magnesium oxide are pre-dried in a special oven for 2 hours at a drying temperature of 120℃.

[0084] (2) Take out the dried sample from step (1), accurately weigh 25wt.% kaolin, 30wt.% muscovite, 40wt.% titanium aluminum carbon, 2wt.% flake graphite, 1wt.% titanium oxide, 1wt.% potassium carbonate, and 1wt.% magnesium oxide, add 3wt.% polyvinyl alcohol of total mass and mix and ball mill. The ball mill speed is 300rpm. The direction is changed once every 60min during the ball milling process, with an interval of 15min. The mixing time is 8h.

[0085] (3) Grind the mixture system from step (2) until it is uniformly mixed. After the process is complete, put it into a mold and press it into a preform. Apply pressure of 150 MPa and hold for 5 minutes. After demolding, quickly seal and store the preform.

[0086] (4) The preform obtained in step (3) is placed into the oil cavity for cold isostatic pressing to obtain the preform. The pressure is applied at 250 MPa and the holding time is 5 min. After the preform is demolded, it is quickly sealed and stored.

[0087] (5) The green blank obtained in step (4) is buried in a corundum crucible, and then the crucible is placed in a tube furnace to prepare for carbon sintering. The sintering is heated to 500°C at a heating rate of 5°C / min and held for 2 hours for debinding. Then it is heated to 1275°C at a heating rate of 5°C / min and held for 1 hour. Then it is cooled to 800°C at a cooling rate of 1°C / min and held for 6 hours for annealing. Finally, it is cooled to 200°C at a cooling rate of 5°C / min and then cooled with the furnace. Argon gas is introduced throughout the process as a protective gas to obtain the sample.

[0088] (6) Take the sample obtained in step (5) out of the corundum crucible, polish the surface with 200, 400, 600 and 1200 grit sandpaper, coat the upper and lower surfaces with conductive silver paste, each layer of silver paste is 10 μm thick, and keep it at 230℃ for 2 hours in a box furnace to obtain a high-strength metal / carbon ceramic composite resistor.

[0089] Example 11 (1) The raw materials such as mullite, muscovite, zirconium diboride, carbon black, calcium carbonate, basalt fiber, and potassium carbonate are pre-dried in a special oven for 3 hours at a drying temperature of 130℃.

[0090] (2) Take out the dried sample from step (1), accurately weigh 32wt.% mullite, 30wt.% muscovite, 30wt.% zirconium diboride, 5wt.% carbon black, 1wt.% calcium carbonate, 1wt.% basalt fiber, and 1wt.% potassium carbonate, add 2wt.% acetone of total mass and mix and ball mill. The ball mill speed is 350rpm. The direction is changed once every 60min during the ball milling process, with an interval of 20min. The mixing time is 6h.

[0091] (3) Grind the mixed system from step (2) until it is uniform. After the process is complete, put it into a mold and press it into a preform. Apply 100 MPa pressure and hold for 5 minutes. After the preform is demolded, quickly seal it in plastic.

[0092] (4) The preform obtained in step (3) is placed into the oil cavity for cold isostatic pressing to obtain the preform. The pressure is increased to 200 MPa and the holding time is 10 min. After the preform is demolded, it is quickly sealed and stored.

[0093] (5) The green blank obtained in step (4) is buried in a corundum crucible, and then the crucible is placed in a tube furnace to prepare for carbon sintering. The sintering is heated to 600°C at a heating rate of 10°C / min and held for 3 hours for debinding treatment. Then it is heated to 1325°C at a heating rate of 1°C / min and held for 1.5 hours. Then it is cooled to 600°C at a cooling rate of 3°C / min and held for 10 hours for annealing treatment. Finally, it is cooled to 200°C at a cooling rate of 1°C / min and then cooled with the furnace. Argon gas is introduced as a protective gas throughout the process to obtain the sample.

[0094] (6) Take the sample obtained in step (5) out of the corundum crucible, polish the surface with 200, 400, 600 and 1200 grit sandpaper, coat the upper and lower surfaces with conductive silver paste, each layer of silver paste is 12 μm thick, and keep it at 250℃ for 3 h in a box furnace to obtain a high-strength metal / carbon ceramic composite resistor.

[0095] Example 12 (1) Pyrophyllite, porcelain stone, niobium diboride, fiber graphite, titanium dioxide, carbon nanotubes, aluminum nitride, zirconium oxide and other raw materials are pre-dried in a special oven for 2 hours at a drying temperature of 140℃.

[0096] (2) Take out the dried sample from step (1), accurately weigh 36 wt.% pyrophyllite, 30 wt.% porcelain stone, 25 wt.% niobium diboride, 5 wt.% fibrous graphite, 1 wt.% titanium dioxide, 1 wt.% carbon nanotubes, 1 wt.% aluminum nitride, and 1 wt.% zirconium oxide, add 2 wt.% sodium hexametaphosphate and mix and ball mill. The ball mill speed is 400 rpm. The direction is changed every 60 min during the ball milling process, with an interval of 25 min. The mixing time is 4 h.

[0097] (3) Grind the mixture system from step (2) until it is uniformly mixed. After the process is complete, put it into a mold and press it into a preform. Apply pressure of 150 MPa and hold for 5 minutes. After demolding, quickly seal and store the preform.

[0098] (4) The preform obtained in step (3) is placed into the oil cavity for cold isostatic pressing to obtain the preform. The pressure is applied at 150 MPa and the holding time is 10 min. After the preform is demolded, it is quickly sealed and stored.

[0099] (5) The green blank obtained in step (4) is buried in a corundum crucible, and then the crucible is placed in a tube furnace to prepare for carbon sintering. The sintering is heated to 600°C at a heating rate of 10°C / min and held for 3 hours for debinding. Then it is heated to 1375°C at a heating rate of 1°C / min and held for 0.5 hours. Then it is cooled to 800°C at a cooling rate of 1°C / min and held for 6 hours for annealing. Finally, it is cooled to 200°C at a cooling rate of 5°C / min and then cooled with the furnace. Argon gas is introduced throughout the process as a protective gas to obtain the sample.

[0100] (6) Take the sample obtained in step (5) out of the corundum crucible, polish the surface with 200, 400, 600 and 1200 grit sandpaper, coat the upper and lower surfaces with conductive silver paste, each layer of silver paste is 8 μm thick and keep it at 210℃ for 2 h in a box furnace to obtain a high-strength metal / carbon ceramic composite resistor.

[0101] Example 13 (1) Pyrophyllite, porcelain stone, niobium diboride, fiber graphite, titanium dioxide, carbon nanotubes, aluminum nitride, zirconium oxide and other raw materials are pre-dried in a special oven for 2 hours at a drying temperature of 140℃.

[0102] (2) Take out the dried sample from step (1), accurately weigh 36 wt.% pyrophyllite, 30 wt.% porcelain stone, 25 wt.% niobium diboride, 5 wt.% fibrous graphite, 1 wt.% titanium dioxide, 1 wt.% carbon nanotubes, 1 wt.% aluminum nitride, and 1 wt.% zirconium oxide, add 2 wt.% sodium hexametaphosphate and mix and ball mill. The ball mill speed is 400 rpm. The direction is changed every 60 min during the ball milling process, with an interval of 25 min. The mixing time is 4 h.

[0103] (3) Grind the mixture system from step (2) until it is uniformly mixed. After the process is complete, put it into a mold and press it into a preform. Apply pressure of 150 MPa and hold for 5 minutes. After demolding, quickly seal and store the preform.

[0104] (4) The preform obtained in step (3) is placed into the oil cavity for cold isostatic pressing to obtain the preform. The pressure is applied at 150 MPa and the holding time is 10 min. After the preform is demolded, it is quickly sealed and stored.

[0105] (5) The green blank obtained in step (4) is buried in a corundum crucible, and then the crucible is placed in a tube furnace to prepare for carbon sintering. The sintering is heated to 600°C at a heating rate of 10°C / min and held for 3 hours for debinding. Then it is heated to 1375°C at a heating rate of 1°C / min and held for 0.5 hours. Then it is cooled to 800°C at a cooling rate of 1°C / min and held for 6 hours for annealing. Finally, it is cooled to 200°C at a cooling rate of 5°C / min and then cooled with the furnace. Argon gas is introduced throughout the process as a protective gas to obtain the sample.

[0106] (6) Take the sample obtained in step (5) out of the corundum crucible, polish the surface with 200, 400, 600 and 1200 grit sandpaper, coat the upper and lower surfaces with conductive silver paste, each layer of silver paste is 8 μm thick and keep it at 210℃ for 2 h in a box furnace to obtain a high-strength metal / carbon ceramic composite resistor.

[0107] Example 14 (1) The raw materials such as kaolin, alumina, titanium diboride, titanium aluminum carbon, fiber graphite, magnesium oxide, titanium oxide, zirconium oxide, and boron nitride are pre-dried in a special oven for 1 hour at a drying temperature of 150℃.

[0108] (2) Take out the dried sample from step (1), accurately weigh 29 wt.% kaolin, 23 wt.% alumina, 20 wt.% titanium diboride, 23 wt.% titanium aluminum carbon, 1 wt.% fiber graphite, 1 wt.% magnesium oxide, 1 wt.% titanium oxide, 1 wt.% zirconium oxide, and 1 wt.% boron nitride, add 1 wt.% stearic acid of total mass and mix and ball mill. The ball mill speed is 400 rpm. The direction is changed once every 60 min during the ball milling process, with an interval of 30 min. The mixing time is 4 h.

[0109] (3) The mixed system from step (2) is subjected to discharge plasma sintering in an argon-hydrogen mixed atmosphere. The sintering temperature is increased to 900℃ at a rate of 100℃ / min and held for 5 minutes. The pressure is 30MPa. After sintering, the system is cooled to room temperature in the furnace.

[0110] (4) Take the sample obtained in step (3) out of the corundum crucible, polish the surface with 200, 400, 600 and 1200 grit sandpaper, coat the upper and lower surfaces with conductive silver paste, each layer of silver paste is 8 μm thick and kept at 150°C for 4 h in a box furnace to obtain a high-strength metal / carbon ceramic composite resistor.

[0111] Example 15 (1) The raw materials such as kaolin, silicon dioxide, zirconium diboride, graphene, and aluminum nitride are pre-dried in a special oven for 4 hours at a drying temperature of 90℃.

[0112] (2) Take out the dried sample from step (1), accurately weigh 49wt.% kaolin, 39wt.% silicon dioxide, 6wt.% zirconium diboride, 5wt.% graphene, and 1wt.% aluminum nitride, add 8wt.% anhydrous ethanol and mix and ball mill. The ball mill speed is 200rpm. The direction is reversed every 60min during the ball milling process, with an interval of 0min (i.e., no interval). The mixing time is 12h.

[0113] (3) The mixed system from step (2) is subjected to discharge plasma sintering in an argon-hydrogen mixed atmosphere. The sintering temperature is increased to 1100℃ at a rate of 300℃ / min and held for 10 min at a pressure of 50MPa. After sintering, the system is cooled to room temperature in the furnace.

[0114] (4) Take the sample obtained in step (3) out of the corundum crucible, polish the surface with 200, 400, 600 and 1200 grit sandpaper, coat the upper and lower surfaces with conductive silver paste, each layer of silver paste is 8 μm thick and keep it at 300℃ for 1 h in a box furnace to obtain a high-strength metal / carbon ceramic composite resistor.

[0115] Example 16 (1) The raw materials such as mullite, kaolin, niobium diboride, graphene, carbon nanotubes, carbon fibers, magnesium oxide, and titanium oxide are pre-dried in a special oven for 3 hours at a drying temperature of 110℃.

[0116] (2) Take out the dried sample from step (1), accurately weigh 50wt.% mullite, 34wt.% kaolin, 7wt.% niobium diboride, 5wt.% graphene, 1wt.% carbon nanotubes, 1wt.% carbon fiber, 1wt.% magnesium oxide, and 1wt.% titanium oxide, add 2wt.% deionized water and mix and ball mill. The ball mill speed is 300rpm. The direction is changed every 60min during the ball milling process, with an interval of 5min. The mixing time is 8h.

[0117] (3) The mixed system from step (2) is subjected to discharge plasma sintering in an argon-hydrogen mixed atmosphere. The sintering temperature is increased to 1100℃ at a rate of 200℃ / min and held for 10 min at a pressure of 50MPa. After sintering, the system is cooled to room temperature in the furnace.

[0118] (4) Take the sample obtained in step (3) out of the corundum crucible, polish the surface with 200, 400, 600 and 1200 grit sandpaper, coat the upper and lower surfaces with conductive silver paste, each layer of silver paste is 8 μm thick and keep it at 300℃ for 1 h in a box furnace to obtain a high-strength metal / carbon ceramic composite resistor.

[0119] Example 17 (1) Pyrophyllite, muscovite, titanium diboride, titanium aluminum carbon, graphene oxide, magnesium oxide, titanium oxide, carbon nanotubes, carbon fiber, potassium carbonate, calcium carbonate and other raw materials are pre-dried in a special oven for 2 hours at a drying temperature of 110℃.

[0120] (2) Take out the dried sample from step (1), accurately weigh 20 wt.% pyrophyllite, 35 wt.% muscovite, 17 wt.% titanium diboride, 17 wt.% titanium aluminum carbon, 5 wt.% graphene oxide, 1 wt.% magnesium oxide, 1 wt.% titanium oxide, 1 wt.% carbon nanotubes, 1 wt.% carbon fiber, 1 wt.% potassium carbonate, and 1 wt.% calcium carbonate. Add 5 wt.% kerosene by total mass and mix and ball mill. The ball mill speed is 300 rpm. The direction is reversed every 60 min during the ball milling process, with an interval of 5 min. The mixing time is 6 h.

[0121] (3) The mixed system from step (2) is hot-pressed and sintered in an argon-hydrogen mixed atmosphere. The sintering temperature is increased to 1100℃ at a rate of 5℃ / min and held for 2 hours. The pressure is 30MPa. After sintering, the system is cooled to room temperature in the furnace.

[0122] (4) Take the sample obtained in step (3) out of the corundum crucible, polish the surface with 200, 400, 600 and 1200 grit sandpaper, coat the upper and lower surfaces with conductive silver paste, each layer of silver paste is 12 μm thick and keep it at 250℃ for 2 h in a box furnace to obtain a high-strength metal / carbon ceramic composite resistor.

[0123] Example 18 (1) Dry the raw materials such as halloysite, illite, titanium diboride, titanium aluminum carbon, fiber graphite, magnesium oxide, and basalt fiber in a special oven for 2 hours at a drying temperature of 110℃.

[0124] (2) Take out the dried sample from step (1), accurately weigh 28 wt.% halloysite, 35 wt.% illite, 27 wt.% titanium diboride, 3 wt.% titanium aluminum carbon, 5 wt.% fiber graphite, 1 wt.% magnesium oxide, and 1 wt.% basalt fiber, add 3 wt.% oleic acid of total mass and mix and ball mill. The ball mill speed is 250 rpm. The direction is changed once every 60 min during the ball milling process, with an interval of 10 min. The mixing time is 8 h.

[0125] (3) The mixed system from step (2) is hot-pressed and sintered in an argon-hydrogen mixed atmosphere. The sintering temperature is increased to 1400℃ at a rate of 20℃ / min and held for 0.5h. The pressure is 10MPa. After sintering, the system is cooled to room temperature in the furnace.

[0126] (4) Take the sample obtained in step (3) out of the corundum crucible, polish the surface with 200, 400, 600 and 1200 grit sandpaper, coat the upper and lower surfaces with conductive silver paste, each layer of silver paste is 12 μm thick, and keep it at 200℃ for 3 hours in a box furnace to obtain a high-strength metal / carbon ceramic composite resistor.

[0127] Comparative Example 1 The sample AB410 M006C from Morgan Company in the UK is a commercial material containing only a carbon conductive phase and no metallic conductive phase.

[0128] After grinding away the self-contained electrode layer on the sample, SEM analysis was performed, and the results are as follows. Figure 2 As shown in the figure (the carbon black particles marked in the figure have a particle size of 22.99 nm, and there are obvious gaps between the carbon black particles and the ceramic matrix).

[0129] Comparative Example 2 It is largely the same as Example 5, except that after step (3), the cold isostatic pressing direct sintering of step (4) is not performed, and step (5) is performed directly.

[0130] Comparative Example 3 The process is largely the same as in Example 1, except that titanium diboride, titanium aluminum carbon and fiber graphite materials in step (2) are removed. Instead, the following materials are used: 29 parts by mass of kaolin, 23 parts by mass of alumina, 1 part by mass of magnesium oxide, 1 part by mass of titanium oxide, 1 part by mass of zirconium oxide, 1 part by mass of boron nitride, and 1 wt.% stearic acid is added and then the mixture is ball-milled.

[0131] Comparative Example 4 The process is largely the same as in Example 1, except that the magnesium oxide, titanium oxide, zirconium oxide and boron nitride materials in step (2) are removed. Instead, the following materials are used: 29 parts by mass of kaolin, 23 parts by mass of alumina, 20 parts by mass of titanium diboride, 23 parts by mass of titanium aluminum carbon, 1 part by mass of fiber graphite, and then 1 wt.% of stearic acid is added and the mixture is ball-milled.

[0132] Comparative Example 5 It is largely the same as Example 1, except that the stearic acid material in step (2) is removed (i.e., ball milling is performed without the use of a dispersant).

[0133] Comparative Example 6 It is largely the same as Example 1, except that only the kaolin and alumina materials in step (2) are retained, while the stearic acid material in step (2) is removed. That is, 29 parts by mass of kaolin and 23 parts by mass of alumina are used and ball milling is performed without the use of a dispersant.

[0134] Comparative Example 7 The process is largely the same as in Example 1, except that fiber graphite is not used in step (2) (i.e., no carbon conductive phase material is used). Specifically, the following materials are used: 29 parts by mass of kaolin, 23 parts by mass of alumina, 20 parts by mass of titanium diboride, 23 parts by mass of titanium aluminum carbon, 1 part by mass of magnesium oxide, 1 part by mass of titanium oxide, 1 part by mass of zirconium oxide, 1 part by mass of boron nitride, and then 1 wt.% of stearic acid is added and the mixture is ball-milled.

[0135] Comparative Example 8 The process is largely the same as in Example 2, except that zirconium diboride is not used in step (2) (i.e., no metallic conductive phase material is used). Specifically, the following materials are used: 49 parts by mass of kaolin, 39 parts by mass of silicon dioxide, 5 parts by mass of graphene, 1 part by mass of aluminum nitride, and 8 wt.% of anhydrous ethanol are added and then the mixture is ball-milled.

[0136] Examples 1-13 employ a pre-drying-ball milling-pre-forming-forming-carburized sintering process; Examples 14-16 employ a pre-drying-ball milling-spark plasma sintering process; and Examples 17-18 employ a pre-drying-ball milling-hot pressing sintering process. Furthermore, we conducted repeated experiments on the high-strength metal / carbon ceramic composite resistors prepared in Examples 1-18. Four samples were ultimately prepared for each example. The resistivity of each sample was tested according to GB / T 351-2019, and the average measured resistivity of these four samples was recorded as their nominal resistance. The measured resistivity results for each sample in each example are shown in Table 1.

[0137] Table 1: Resistivity of high-strength metal / carbon ceramic composite resistors obtained from repeated experiments in Examples 1-18

[0138] Table 1 shows the repeated experimental results of the high-strength metal / carbon ceramic composite resistors prepared in Examples 1 to 18. As can be seen from the table, the formulations of the present invention passed multiple repeated experiments. The resistivity deviation of each sample obtained from each formulation was within ±5%, indicating that the product qualification rate of the method of the present invention is high (if the nominal resistance deviation of a single resistor can be controlled within ±10%, the sample is qualified; otherwise, the sample is unqualified). Furthermore, the present invention can obtain high-strength metal / carbon ceramic composite resistors with different resistivity levels, making it suitable for application scenarios with different resistivity requirements.

[0139] The high-strength metal / carbon ceramic composite resistor samples prepared in Examples 1 to 18, as well as the samples in Comparative Examples 1 to 6, were subjected to performance tests. Among them: a) The resistivity of the complete samples of each embodiment and the complete samples of each comparative example was measured according to GB / T 351-2019 and the average value was taken.

[0140] b) After grinding away the conductive silver layer on the upper and lower surfaces of the complete samples of each embodiment and Comparative Examples 2 to 6, and after grinding away the surface electrode layer of the sample in Comparative Example 1, the bulk density was measured according to GB / T 2997-2015, the compressive strength and flexural strength were measured according to GB / T 4740-2024, the coefficient of thermal expansion was measured according to GB / T 16535-2008, the volumetric specific heat capacity was measured according to GB / T 22588-2008, the temperature coefficient of resistance was measured according to GB / T 6148-2025, and the porosity was measured according to GB / T 25995-2010, and the average values ​​were taken respectively.

[0141] The test performance results are shown in Table 2.

[0142] Table 2: Performance Comparison of High-Strength Metal / Carbon Ceramic Composite Resistors Prepared in Each Comparative Example and Each Embodiment

[0143] Table 2 compares the performance of the high-strength metal / carbon ceramic composite resistors prepared in Examples 1-18 with those in Comparative Examples 1-6. As can be seen from the table, the ceramic resistors prepared in Examples 1-18 of this invention, after sampling inspection, all meet the performance requirements of industry standards (e.g., the "Type Test Specification for Carbon Ceramic Closing Resistor Sheets for 800kV and Below Circuit Breakers (Trial Implementation)") for novel carbon ceramic closing resistors, i.e., a bulk density ≥ 2.3 g / cm³. 3 Compressive strength ≥120MPa, coefficient of thermal expansion ≤7.0×10 -6 / ℃, specific heat capacity ≥2J / (cm³) 3 The temperature coefficient of resistance (T / K) is between -0.05 and 0.1% / ℃. The mechanical and thermal properties of the ceramic resistor prepared in Comparative Example 1 are far lower than those of the ceramic resistors prepared in Examples 1-18 of this invention. (A key reason why the mechanical properties of the Comparative Example 1 sample are inferior to those of the other examples is that the Comparative Example 1 sample...) Figure 2The obvious voids in the microstructure lead to a decrease in material strength. Furthermore, although the resistivity of the resistors obtained in Examples 7 and 9 is lower than that of the sample in Comparative Example 1, and the resistivity of the resistor obtained in Example 12 is also slightly lower than that of the sample in Comparative Example 1, in practical applications, high and low resistivity do not necessarily correspond to superiority or inferiority. Technicians can use different ranges of resistivity as needed. Moreover, as can be seen from Examples 1-18 above, based on the method of this invention, the resistivity of the obtained resistors can be controlled by minute adjustments of the composition, covering application scenarios with different resistivity requirements. Comparative Example 2 only used the traditional uniaxial cold pressing method. Comparing it with Example 5, it can be seen that after adopting the molding-sintering process of this invention, the density and mechanical properties of the sample were improved. Comparative Example 3 removed all conductive phase material. Comparing it with Example 1, it can be seen that after adopting the composite conductive phase of this invention, the thermal and mechanical properties of the sample were improved. Comparative Example 4, without the additive material, compared with Example 1, shows that the addition of the additive improved the thermal and mechanical properties of the sample in Example 1. Furthermore, combined with Comparative Example 3, it is clear that the additive is superior to the additive alone for optimizing the performance of the ceramic-composite conductive phase system (i.e., the sample in Example 1). Comparative Example 5, without the dispersant material, compared with Example 1, shows that the addition of the dispersant during ball milling improved the thermal, electrical, and mechanical properties of the sample. Comparative Example 6, retaining only the ceramic phase material, resulted in a sample with poor sintering density, high porosity, and a large coefficient of thermal expansion. Comparative Example 7, without the carbon conductive phase material, resulted in a sample with a large coefficient of thermal expansion, low volumetric specific heat capacity, and a large temperature coefficient of electrical resistance. Comparative Example 8, without the metallic conductive phase material, resulted in a sample with lower density and mechanical strength, and high porosity.

[0144] Furthermore, the porosity of the samples in each embodiment is lower than that of the sample in Comparative Example 1, indicating that the materials and processes used in this invention enhance the interfacial compatibility of different materials. The conductive phase material and the pre-drying-ball milling-forming-sintering process (of course, for spark plasma sintering or hot pressing sintering processes, forming and sintering are completed simultaneously) employed in this invention improve the wettability between the ceramic phase and the metallic conductive phase, allowing the matrix to fully spread and penetrate into the micro-cracks in the early stages of forming, squeezing out trapped air and preventing the formation of interfacial porosity from the source. The good interfacial compatibility ensures that the particles of each component are uniformly dispersed, preventing the formation of dense agglomerates and avoiding air bubbles trapped within the clusters. Simultaneously, the strong interfacial bonding force resists curing shrinkage and thermal stress, preventing the interface from debonding and forming microcracks during cooling or curing.

[0145] In addition, after grinding away the conductive silver layer on the upper and lower surfaces of the nominal resistance samples of the high-strength metal / carbon ceramic composite resistors prepared in Examples 1 to 4, SEM analysis was performed, and the results are as follows. Figure 3 As shown.

[0146] The above embodiments are merely examples. For different ceramic matrices, by comprehensively adjusting additives, metallic conductive phases, carbon conductive phases, ball milling parameters (e.g., ball milling mixing time, interval time, ball milling speed), molding processes, and sintering temperature curves, high-strength metal / carbon ceramic composite resistors that meet different resistivity requirements can be obtained according to needs.

[0147] The above embodiments are merely examples. For instance, in addition to Ar, other non-oxidizing protective gases (such as a mixture of H2 and Ar) can be used in the sintering atmosphere.

[0148] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-strength metal / carbon ceramic composite resistor, characterized in that, It is composed of a conductive layer, a functional layer, and a conductive layer connected tightly from top to bottom. The functional layer is a composite material formed by uniformly mixing and sintering ceramic phase material, metallic conductive phase material, carbon conductive phase material, and additives. The mass ratio of the ceramic phase material, metallic conductive phase material, carbon conductive phase material, and additives in the total mass of these four components is (52-88%):(7-43%):(1-5%):(1-6%). The ceramic phase material is one or more of alumina, kaolin, silicon dioxide, mullite, pyrophyllite, muscovite, halloysite, illite, and porcelain stone. The metallic conductive phase material is one or more of titanium diboride, titanium aluminum carbon, zirconium diboride, and niobium diboride. The carbon conductive phase material is one or more of graphene, graphene oxide, fibrous graphite, flake graphite, and carbon black. The additives are one or more of magnesium oxide, titanium oxide, zirconium oxide, boron nitride, aluminum nitride, basalt fiber, carbon nanotubes, carbon fiber, potassium carbonate, and calcium carbonate. The compressive strength of the functional layer is not less than 282.2 MPa, and the flexural strength is not less than 88.0 MPa.

2. The method for preparing the high-strength metal / carbon ceramic composite resistor as described in claim 1, characterized in that, Includes the following steps: (1) The ceramic phase material, the metallic conductive phase material, the carbon conductive phase material, and the additives are pre-dried to obtain dried raw materials; (2) The dried raw materials of ceramic phase material, metal conductive phase material, carbon conductive phase material and additive are mixed together with the dispersant, and then ball-milled to obtain a mixed system; (3) The mixture obtained in step (2) is cold-pressed to obtain a preformed green body; (4) The preform obtained in step (3) is subjected to cold isostatic pressing to obtain a green blank; (5) The green body obtained in step (4) is subjected to debinding treatment in a non-oxidizing protective gas atmosphere, followed by carbon embedding sintering to obtain a high-strength metal / carbon ceramic sample. (6) After polishing the sample obtained in step (5), a conductive layer is coated and heated to cure, and a high-strength metal / carbon ceramic composite resistor can be obtained.

3. The method for preparing the high-strength metal / carbon ceramic composite resistor as described in claim 1, characterized in that, Includes the following steps: S1: The ceramic phase material, the metallic conductive phase material, the carbon conductive phase material, and the additives are pre-dried to obtain dried raw materials; S2: The dried raw materials of ceramic phase material, metallic conductive phase material, carbon conductive phase material and additive are mixed together with the dispersant, and then ball-milled to obtain a mixed system. S3: The mixed system obtained in step S2 is subjected to discharge plasma sintering or hot pressing sintering in a non-oxidizing protective gas atmosphere to obtain a high-strength metal / carbon ceramic sample. S4: After polishing the sample obtained in step S3, coat it with a conductive layer and heat it to cure, and a high-strength metal / carbon ceramic composite resistor can be obtained.

4. The preparation method according to claim 2 or 3, characterized in that, In step (1) or step S1, the dispersant is one or more of anhydrous ethanol, oleic acid, polyvinyl alcohol, triethanolamine, sodium hexametaphosphate, stearic acid, talc, deionized water, anhydrous methanol, acetone, and kerosene.

5. The preparation method according to claim 2 or 3, characterized in that, In step (1) or step S1, the drying temperature is 90-150℃ and the drying time is 1-4h. In step (2) or step S2, the mass of the dispersant is 1-8% of the total mass of the ceramic phase material, the metallic conductive phase material, the carbon conductive phase material, and the additive; The ball milling process involves a mixing time of 4-12 hours and a milling speed of 200-400 rpm.

6. The preparation method according to claim 2, characterized in that, In step (3), the molding pressure used for cold pressing is 50-250 MPa, and the molding time is 1-5 min; In step (4), the molding pressure of cold isostatic pressing is 50-250 MPa, and the molding time is 5-15 min.

7. The preparation method according to claim 2, characterized in that, In step (5), the carbon sintering process involves heating the material to 500-600℃ and holding it for 1-3 hours in a non-oxidizing protective gas atmosphere to remove the binder, then heating it to 1150-1400℃ and holding it for 0.5-3 hours, followed by cooling it down to 600-800℃ and holding it for 4-12 hours for annealing, and finally cooling it down.

8. The preparation method according to claim 7, characterized in that, The specific step (5) is to first heat the material to 500-600℃ at a heating rate of 5-10℃ / min and hold it for 1-3 hours for debinding; then heat the material to 1150-1400℃ at a heating rate of 1-5℃ / min and hold it for 0.5-3 hours; then cool the material to 600-800℃ at a cooling rate of 1-3℃ / min and hold it for 4-12 hours for annealing. The cooling process involves first cooling the furnace to 200°C at a rate of 1-5°C / min, and then cooling it to room temperature along with the furnace.

9. The preparation method according to claim 3, characterized in that, When step S3 uses spark plasma sintering, the spark plasma sintering is carried out in a non-oxidizing protective gas atmosphere, the sintering temperature is 900-1100℃, the pressure is 30-50MPa, the holding time is 5-10min, and the furnace is cooled to room temperature after sintering. When hot pressing sintering is used in step S3, the hot pressing sintering is carried out in a non-oxidizing protective gas atmosphere, the sintering temperature is 1100-1400℃, the pressure is 10-30MPa, the holding time is 0.5-2h, and the furnace is cooled to room temperature after sintering.

10. The preparation method according to claim 8 or 9, characterized in that, The non-oxidizing protective gas atmosphere is pure argon or an argon-hydrogen mixture.

11. The preparation method according to claim 2 or 3, characterized in that, In step (6) or step S4, the conductive layer is silver paste, and the coating thickness of each layer of silver paste is 8-12μm; the heating temperature used for the heat curing is 150-300℃, and the heat preservation time is 1-4h.

12. The application of the high-strength metal / carbon ceramic composite resistor as described in claim 1 in the closing resistor.

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