Carbon ceramic closing resistor for high-voltage circuit breaker and preparation method thereof

Abstract

The invention discloses a carbon ceramic closing resistor for a high-voltage circuit breaker and a preparation method of the carbon ceramic closing resistor, and belongs to the technical field of power elements. The problems of poor resistor compactness, non-uniform performance, insufficient mechanical property and the like caused by high pressing and sintering difficulty, process instability and high and non-uniform resistor porosity of the carbon ceramic resistor are solved. The preparation process of the resistor comprises the following steps: by taking aluminum oxide and quartz as ceramic phases, presintered kaolin, mullite and potassium feldspar as clay phases and carbon black or graphite as conductive phases, pre-coating the ceramic phases with the clay phases, carrying out vacuum calcination on pre-coated powder, mixing the pre-coated powder with the secondarily added clay phases and the conductive phases, carrying out spray granulation, pressing a green body, sintering and spraying. And obtaining the carbon ceramic closing resistor. According to the invention, the kaolin is pre-sintered, and the clay phase is pre-coated with the ceramic phase, so that the subsequent blank pressing uniformity and density are increased, the structural defects of the carbon ceramic resistor are reduced, and in combination with the spark plasma sintering technology, the batch rapid production of the resistor can be realized.

Description

Technical Field

[0001] This invention relates to the field of power component technology, and in particular to a carbon ceramic closing resistor for high-voltage circuit breakers and its preparation method. Background Technology

[0002] In power systems, operational overvoltages generated during the switching of unloaded lines are a key factor affecting the safe and stable operation of the power grid. The closing resistor of a high-voltage circuit breaker is a crucial device used to limit operational overvoltages during power system closing, primarily applied in 500kV and above ultra-high-voltage systems. This device is briefly connected to the circuit during circuit breaker closing, utilizing the damping effect of the resistor to reduce the voltage amplitude, release grid energy, thereby protecting electrical equipment, ensuring stable power system operation, and enhancing power system safety. The closing resistor performs both control and protection functions. The control function is achieved by putting some electrical equipment and lines into or out of operation, while the protection function quickly disconnects the faulty part when a fault occurs in the electrical equipment or line, ensuring the normal operation of the fault-free parts of the power system. Typically, a 350-600Ω closing resistor is used in a 500kV system, and a 400-600Ω closing resistor is used in a 750kV system. The closing resistor element is mostly a circular annular ceramic disc with a conductive coating on the flat surface and an insulating coating on the sides, improving the high-voltage resistance of the side surface and inner surface. Carbon ceramic resistors are one of the main categories and the most widely used resistors.

[0003] Chinese patent CN119977587A addresses the problems of poor thermal shock resistance and difficulty in reducing resistivity in traditional composite alumina ceramic linear resistors. It employs a traditional pressureless process, replacing the traditional phases with silicon carbide as both the framework and conductive phase, bentonite as a sintering aid, and nano-carbon black as a conductive filler. Leveraging the low coefficient of thermal expansion and excellent thermal conductivity of silicon carbide, the thermal shock resistance of the resistor is improved. The resulting carbon composite ceramic linear resistors exhibit a porosity of 26.6%-31.4% and a thermal conductivity of 6.86-11.73 W·m. -1 ·K -1 The critical thermal shock temperature difference is 349.71-405.61℃, and the resistivity is 0.54-10.48Ω·cm. However, due to the poor sintering performance between silicon carbide and bentonite, the high porosity of the resistor sheet leads to insufficient overall mechanical properties and increases the failure rate. Chinese patent CN118580058A proposes that the existing pressureless sintering method for preparing carbon ceramic resistors is difficult to press and sinter, and there is a large room for improvement in product performance. It proposes to replace it with a hot pressing sintering method to prepare carbon ceramic resistor sheets. By completing the forming and sintering in one step, the stability and densification of the sintered body are improved, and the porosity is as low as 0.21%-0.35%, with a thermal diffusivity of 1.977~2.085mm. 2 / S, with a bending strength of 115~120MPa, significantly improves density, thermal diffusivity and bending strength compared to pressureless sintering. However, hot pressing sintering has problems such as long production cycle, high production cost and inability to mass-produce, making it unsuitable for industrial production. Furthermore, the sintered resistor sheet is difficult to process, which can easily cause product damage and reduce product quality. Summary of the Invention

[0004] This invention addresses the problems in existing technologies, such as the difficulty in pressing and sintering large-size carbon ceramic resistors, poor process stability, difficulty in uniformly dispersing the conductive phase of carbon ceramic resistors, high porosity of carbon ceramic resistors and differences in different regions of the resistor, which lead to poor compactness, non-uniform performance and insufficient mechanical properties of carbon ceramic resistors. It provides a carbon ceramic closing resistor for high-voltage circuit breakers and its preparation method.

[0005] The technical solution of the present invention is as follows: One objective of this invention is to provide a method for preparing a carbon ceramic closing resistor for a high-voltage circuit breaker, the method comprising the following steps: (1) Using alumina and quartz as ceramic phases, pre-calcined kaolin, mullite and potassium feldspar as clay phases, and carbon black or graphite as conductive phases, the ceramic phase and clay phase are sand-milled in the presence of surfactant and binder to obtain a pre-coated slurry of clay phase pre-coated ceramic phase. The pre-coated slurry is spray-granulated and vacuum calcined to obtain pre-coated agglomerates. (2) The pressure aid, pre-coated agglomerate, secondary clay phase and conductive phase are mixed by wet ball milling to obtain ball mill slurry; (3) The slurry from the grinding tank is spray-granulated, sieved, and aged to obtain pre-pressed powder; (4) The pre-pressed powder is loaded into the mold and pre-pressed to obtain the pressed blank; (5) The pressed blank is sintered by spark plasma to obtain a sintered body; (6) The sintered body is cut and sprayed to make a closing resistor.

[0006] Further defining, (1) the ceramic phase, clay phase and conductive phase are composed of inorganic raw materials.

[0007] Furthermore, the inorganic raw materials include the following components by weight percentage: 20-40% alumina, 8-15% quartz, 30-60% pre-calcined kaolin, 5-10% mullite, 1-2% potassium feldspar, and 1-4.5% carbon black or graphite.

[0008] Further specified, (1) both alumina and quartz have a purity of 99.5% or higher, the alumina particle size distribution is 30-50μm, and the quartz particle size distribution is 30-50μm.

[0009] Further specified, (1) the purity of kaolin, mullite and potassium feldspar is greater than 90%, the particle size distribution of kaolin is 20-60μm, the particle size distribution of mullite is 20-60μm and the particle size distribution of potassium feldspar is 20-60μm.

[0010] Further restrictions are imposed: (1) the pre-fired kaolin is pre-fired at 900°C for 2 hours.

[0011] Further specifying, (1) the carbon black is a spherical agglomerate with a primary particle size of 600-800 nm, and the graphite is flake-like with an equivalent diameter of 10-30 μm; Further specifying, in (1), the surfactant is a mixture of alkylbenzene sulfate and alkylphenol polyethylene ether, and the binder is a mixture of polyvinyl alcohol and polyethylene glycol.

[0012] Further specifying, (1) the specific process of sand milling is as follows: add water, surfactant and binder to the milling tank, stir evenly and then add clay phase for sand milling. When the average particle size of pre-fired kaolin, mullite and potassium feldspar in the clay phase is less than 500nm, add ceramic phase and continue sand milling for 0.5-2h to obtain pre-coated slurry.

[0013] Further, in (1), the vacuum calcination temperature is 700-800℃ and the time is 2-4h.

[0014] Further, the particle size distribution of the pre-coated aggregates in (1) is 50-80 μm.

[0015] Further specifying, the secondary clay phase added in (2) includes unburned kaolin.

[0016] Further specifying, the pressure aid in (2) is magnesium stearate.

[0017] Further, (2) the solid content of the slurry in the intermediate grinding tank is 45-50%, and the ball milling time is 8-12h.

[0018] Further specifying, the mass ratio of the clay phase added in (2) to the clay phase in (1) is 1:1.

[0019] Further, (3) the sieve size during sieving is 70 mesh and the aging time is 30-45 min.

[0020] Further specifying, (4) the pre-pressing method is compression molding, and the mold is a stainless steel mold with a diameter of 165mm.

[0021] Further specified, (5) the temperature of discharge plasma sintering is 1150-1400℃, the holding time is 10-15min, the sintering time of a single furnace of discharge plasma sintering includes three stages: heating, holding and cooling, with a total duration of 60-90min.

[0022] Further specifying, the cutting method in (6) is: using a comprehensive cutting machine to open a hole in the core of the sintered body to form an internal hole that runs through the top and bottom, with a hole diameter of 32-35mm.

[0023] Further specifying, the spraying method in (6) is as follows: using thermal spraying, silver electrodes, aluminum electrodes or copper-aluminum alloy electrodes are sprayed on the upper and lower surfaces of the sintered body after cutting and processing, and insulating high-resistance material is sprayed on the side surface and inner hole sidewall of the sintered body after cutting and processing, and then dried after spraying.

[0024] A second objective of this invention is to provide a carbon ceramic closing resistor for a high-voltage circuit breaker prepared by the above method.

[0025] Beneficial effects of the present invention The carbon ceramic closing resistor for high-voltage circuit breakers of this invention simultaneously meets the requirements of high voltage resistance, impact resistance, and high energy absorption, making it suitable for power transmission, electric traction, and high-voltage pulse circuits. This invention homogenizes the pre-coated agglomerates through a process involving kaolin pre-firing, clay phase pre-coating of the ceramic phase, and clay particle grading (particle grading refers to the particle gradation between spherical pre-coated agglomerates and the secondary addition of clay and conductive phases, with the spherical pre-coated agglomerates serving as the structural framework). By combining binders and pressure-enhancing agents, the uniformity of large-size ceramic blank pressing and sintering stability are ensured. Combined with spark plasma sintering technology, rapid mass production of sintered bodies is achieved, resulting in carbon ceramic resistors free of structural defects, with uniform performance, and product performance meeting practical application requirements. Finally, a mass production process route for carbon ceramic closing resistors has been developed. Compared with existing technologies, this invention also has the following advantages: (1) In this invention, the clay phase kaolin sand mill is pre-dehydrated in a vacuum environment at 900℃ for 2 hours before use, which alleviates the cracking of the green body caused by the rapid volatilization of the crystal water of the clay phase kaolin during the sintering process, increases the sintering stability of the green body, and solves the process problems of large-size carbon ceramic resistors being prone to sintering defects and insufficient sintering stability.

[0026] (2) The present invention grinds the clay phase into nanoparticles and coats them to increase the effective bonding interface between the clay phase and the ceramic phase. Under the coupling effect of nano-size effect and increased effective bonding interface, the sintering reaction activity is improved and the interface reaction process is accelerated, which helps to achieve rapid sintering.

[0027] (3) The clay and ceramic phases are irregular and have poor fluidity, which easily leads to porosity defects when directly pressed, resulting in quality defects such as low body density and insufficient strength. By using a pre-coating process, spherical pre-coated agglomerates with regular morphology and good fluidity are obtained, which improves the particle packing density and pressing uniformity in the pressing process. Using the spherical pre-coated agglomerates as the skeleton phase, the conductive phase and the secondary added clay phase fill the packing voids of the pre-coated agglomerates or are distributed on the surface of the pre-coated agglomerates to form a particle size distribution system, which further improves the particle packing density of the body. By preparing spherical pre-coated agglomerates and adjusting the particle size distribution of the material system, the technical problems of difficult molding of large-size carbon ceramic resistance pressing and low body density in traditional molding processes, as well as the quality problems of high porosity and insufficient mechanical properties of sintered bodies, are solved. The final pressed body density reaches 2.2 g / cm³. 3 The density of the carbon ceramic resistor sheet reaches 2.4 g / cm³. 3 The bending strength reaches 100~125MPa.

[0028] (4) The uniformity of the conductive phase dispersion directly affects the densification of the green body during sintering and the stability of its electrical properties. In this invention, spherical pre-coated agglomerates are used as the particle size distribution framework to increase the fluidity and uniformity of the material system. This helps the conductive phase particles to move and disperse during material mixing, increases the uniformity of material mixing, forms a continuous and uniform conductive path, and obtains a carbon ceramic resistor sheet (closing resistor) with stable resistivity.

[0029] (5) Rapid sintering process: The present invention adopts the rapid sintering process of spark plasma sintering, with a single furnace sintering time of 60-90 min, short sintering cycle, high production efficiency, and suitable for industrial mass production.

[0030] (6) The pre-coating of raw materials in this invention increases the effective bonding interface between the ceramic phase and the clay phase, accelerates the reaction process and helps to quickly sinter and densify; the pre-coating combines particle size distribution, increases the density of the pressed green body, thereby reducing the sintering shrinkage rate, avoiding the generation of defects in large-size carbon ceramic resistors during rapid sintering, and realizing efficient and stable production of carbon ceramic resistor sheets. Attached Figure Description

[0031] Figure 1 This is a flowchart illustrating the preparation process of the carbon ceramic closing resistor for the high-voltage circuit breaker of the present invention. Figure 2 SEM image of the pre-coated aggregates in Example 1; Figure 3 This is a macroscopic morphology diagram of the pressed billet in Example 1; Figure 4 This is a macroscopic morphology diagram of the sintered body of Example 1; Figure 5 XRD pattern of the sintered body of Example 1; Figure 6 SEM image of the sintered body of Example 1; Figure 7 This is a macroscopic morphology diagram of the sintered body of Comparative Example 2; Figure 8 The image shown is a SEM image of the sintered body of Comparative Example 2. Detailed Implementation

[0032] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0033] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0034] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0035] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0036] Example 1 (1) Add 2 kg of deionized water, 120 g of surfactant obtained by mixing alkylbenzene sulfate and alkylphenol polyethylene ether at a mass ratio of 1:1.5, and 2 kg of 5 wt% binder aqueous solution to the sand mill in sequence. The binder aqueous solution is a mixture of polyvinyl alcohol and polyethylene glycol at a mass ratio of 1:1 dissolved in water. After stirring the water, surfactant and binder aqueous solution evenly, add 1.6 kg of pre-fired kaolin (pre-fired temperature 900℃, time 2h), 0.2 kg of mullite and 50 g of potassium feldspar. Sand mill for 1.5h. At this time, the average concentration of kaolin, mullite and potassium feldspar is 100 g. The particles, all with a diameter less than 500 nm, were mixed with 2 kg of alumina and 0.75 kg of quartz and pre-coated. The mixture was then further milled for 0.5 h to obtain a pre-coated slurry of clay phase pre-coated ceramic phase. This pre-coated slurry was dried and spheroidized using a spray granulation tower to obtain spheroidized particles (pre-coated precursors) with a particle size distribution of 50-80 μm. These particles were then pre-calcined in a vacuum sintering furnace at 800℃ for 2 h to obtain pre-coated agglomerates with a particle size distribution of 50-80 μm. The spray granulation tower had an inlet air temperature of 200℃, an outlet air temperature of 95℃, and an atomizer speed of 12000 r / min. The microstructure of the pre-coated agglomerates is shown below. Figure 2 As shown; (2) Put 3 kg of 12 mm grinding balls and 15 kg of 20 mm grinding balls into a 15 L ball mill jar. Then add 6.5 kg of deionized water and 35 g of magnesium stearate into the ball mill jar. After stirring evenly, add 4.75 kg of pre-coated agglomerates, 1.6 kg of unburned kaolin and 170 g of carbon black. After ball milling at a speed of 200-240 r / min for 12 h, the precursor slurry is obtained. After spray granulation, the inlet air temperature of the spray granulation tower is 200℃, the outlet air temperature is 95℃, and the atomizer speed is 12000 r / min. Spherical particles with a particle size of 50-80 μm (granulated material) are obtained. (3) The granulated material is sieved through a 70-mesh sieve. After sieving, the powder is aged for 30 minutes to obtain pre-pressed powder for later use. 1.3 kg of pre-pressed powder is placed into a stainless steel mold with a diameter of 165 mm. The pressure is set at 15 MPa and held for 5 minutes. After pressing, the pre-pressed blank is demolded to obtain a pre-pressed blank with the shape shown in the figure. Figure 3 As shown; (4) The pressed green body is placed in a spark plasma sintering furnace. The heating rate is set to 100℃ / min, the sintering temperature to 1350℃, the sintering pressure to 15MPa, and the temperature and pressure are held for 10min to obtain the sintered body. Its macroscopic morphology is as follows: Figure 4 As shown, the XRD pattern is as follows Figure 5 As shown, the microstructure is as follows Figure 6As shown, the core of the sintered body is opened by a comprehensive cutting machine with a hole diameter of 35mm. Pure aluminum powder (purity ≥99%) is sprayed on the upper and lower surfaces of the sintered body by thermal spraying to form a conductive coating. The sides and inner hole sidewalls are sprayed with insulating high-resistance material: high thermal conductivity epoxy resin (purchased from Shanghai Xiongrun Resin Co., Ltd., model HW-3987A). After spraying and drying, the carbon ceramic closing ceramic resistor (the closing resistor is in the form of a resistor sheet) is prepared. The overall diameter of the resistor sheet is 165mm and the diameter of the internal circular hole is 35mm.

[0037] Example 2 The difference between this embodiment and embodiment 1 is that (2) carbon black is replaced with graphite, and the remaining process steps and parameter settings are the same as in embodiment 1.

[0038] Example 3 The difference between this embodiment and embodiment 1 is that (2) the amount of carbon black used is 85g, and the remaining process steps and parameter settings are the same as in embodiment 2.

[0039] Example 4 The difference between this embodiment and embodiment 1 is that (1) the pre-coating mixing time is 1.0h, and the other process steps and parameter settings are the same as in embodiment 1.

[0040] Example 5 The difference between this embodiment and embodiment 1 is that (1) the pre-coating mixing time is 1.5h, and the remaining process steps and parameter settings are the same as in embodiment 1.

[0041] Example 6 The difference between this embodiment and embodiment 1 is that (1) the pre-coating mixing time is 2.0h, and the remaining process steps and parameter settings are the same as in embodiment 1.

[0042] Example 7 The difference between this embodiment and embodiment 5 is that (4) the sintering temperature is 1300℃ and the sintering pressure is 10MPa. The remaining process steps and parameter settings are the same as in embodiment 5.

[0043] Example 8 The difference between this embodiment and embodiment 5 is that (2) the sintering temperature is 1400℃ and the sintering pressure is 20MPa. The remaining process steps and parameter settings are the same as in embodiment 5.

[0044] Comparative Example 1 The difference between this embodiment and embodiment 5 is that (1) 1.6 kg of pre-burned kaolin is replaced with 1.75 kg of undehydrated kaolin, and the remaining process steps and parameter settings are the same as in embodiment 5.

[0045] Comparative Example 2 (1) Add 4 kg of deionized water, 120 g of surfactant obtained by mixing alkylbenzene sulfate and alkylphenol polyethylene ether at a mass ratio of 1:1.5, 2 kg of binder aqueous solution and 35 g of magnesium stearate to the sand mill in sequence. The binder aqueous solution is a mixture of polyvinyl alcohol and polyethylene glycol at a mass ratio of 1:1 dissolved in water. After stirring the water, surfactant, binder aqueous solution and magnesium stearate evenly, add 1.6 kg of pre-calcined kaolin and 1.6 kg of unpre-calcined kaolin, totaling 3.2 kg, as well as 0.2 kg of mullite, 50 g of potassium feldspar, 2 kg of alumina, 0.75 kg of quartz and 170 g of carbon black. Sand mill for 2 hours to obtain the sand milled material. (2) The sand-milled material is dried and spheroidized through a spray granulation tower to obtain granulated material; (3) The process is the same as (3) in Example 5; (4) is the same as (4) in Example 5.

[0046] The sintered body obtained in this comparative example is as follows: Figure 7 As shown in the figure, a large number of sintering shrinkage cracks appear on the surface of the resistor sheet. The microstructure is shown in the figure below. Figure 8 As shown, the microstructure reveals that the density and structural uniformity of the sample are lower than those of the resistor sheet in Example 1.

[0047] Comparative Example 3 The difference between this embodiment and embodiment 5 is as follows: (4) The process is to place the pressed blank in a graphite tray and sinter the blank at high temperature using a vacuum sintering furnace. The sintering mode is vacuum sintering, the heating rate is set to 15℃ / min, the sintering temperature is 1350℃, the holding time is 4h, and the remaining process steps and parameter settings are the same as in embodiment 5, so as to obtain ceramic resistance sheet.

[0048] Comparative Example 4 The difference between this embodiment and embodiment 5 is that (4) the pressed blank is placed in a graphite tray and the blank is sintered at high temperature in an atmosphere sintering furnace. The sintering atmosphere is argon atmosphere, the heating rate is set to 5℃ / min, the sintering temperature is 1350℃, the holding time is 4h, and the other process steps and parameter settings are the same as in embodiment 5. The ceramic resistor sheet is obtained, and the resistor sheet is severely cracked.

[0049] Table 1. Performance test results of resistors in Examples 1-8 and Comparative Examples 1-4

[0050] As can be seen from the performance data in Table 1, the porosity of carbon ceramic resistor materials treated with the pre-coating process can reach below 12%. The reduction in material porosity helps to improve mechanical and thermal properties, so that the bending strength, thermal diffusivity and thermal conductivity of the resistor sheet meet the performance standards.

[0051] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a carbon ceramic closing resistor for a high-voltage circuit breaker, characterized in that, The method includes the following steps: (1) Using alumina and quartz as ceramic phases, pre-calcined kaolin, mullite and potassium feldspar as clay phases, and carbon black or graphite as conductive phases, the ceramic phase and clay phase are sand-milled in the presence of surfactant and binder to obtain a pre-coated slurry of clay phase pre-coated ceramic phase. The pre-coated slurry is spray-granulated and vacuum calcined to obtain pre-coated agglomerates. (2) The pressure aid, pre-coated agglomerate, secondary clay phase and conductive phase are mixed by wet ball milling to obtain ball mill slurry; (3) The slurry from the grinding tank is spray-granulated, sieved, and aged to obtain pre-pressed powder; (4) The pre-pressed powder is loaded into the mold and pre-pressed to obtain the pressed blank; (5) The pressed blank is sintered by spark plasma to obtain a sintered body; (6) The sintered body is cut and sprayed to make a closing resistor. The ceramic phase, clay phase and conductive phase in (1) constitute inorganic raw materials.

2. The preparation method according to claim 1, characterized in that, The inorganic raw materials include the following components by weight percentage: 20-40% alumina, 8-15% quartz, 30-60% pre-calcined kaolin, 5-10% mullite, 1-2% potassium feldspar, and 1-4.5% carbon black or graphite.

3. The preparation method according to claim 1, characterized in that, (1) The surfactant is a mixture of alkylbenzene sulfate and alkylphenol polyethylene ether, and the binder is a mixture of polyvinyl alcohol and polyethylene glycol.

4. The preparation method according to claim 1, characterized in that, (1) The specific process of medium sand milling is as follows: add water, surfactant and binder to the milling tank, stir evenly and then add clay phase for sand milling. When the average particle size of pre-fired kaolin, mullite and potassium feldspar in the clay phase is less than 500nm, add ceramic phase and continue sand milling for 0.5-2h to obtain pre-coated slurry.

5. The preparation method according to claim 1, characterized in that, (1) The vacuum calcination temperature is 700-800℃ and the time is 2-4h. The particle size distribution of the pre-coated agglomerates is 50-80μm.

6. The preparation method according to claim 1, characterized in that, (2) The secondary addition of clay phase includes unburned kaolin, and the pressure aid is magnesium stearate.

7. The preparation method according to claim 1, characterized in that, (2) The solid content of the slurry in the intermediate tank is 45-50%, and the ball milling time is 8-12h.

8. The preparation method according to claim 1, characterized in that, The mass ratio of the clay phase added in (2) to the clay phase in (1) is 1:1, and the aging time is 30-45 min.

9. The preparation method according to claim 1, characterized in that, (5) The temperature of the discharge plasma sintering is 1150-1400℃ and the holding time is 10-15min.

10. A carbon ceramic closing resistor for a high-voltage circuit breaker, characterized in that, It is prepared by the method described in any one of claims 1-9.

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