Carbon ceramic closing resistor and preparation method thereof

Abstract

The application discloses a carbon ceramic closing resistor and a preparation method thereof, relates to the technical field of closing resistors for super-high voltage circuits, and solves the technical problem of TCR non-linear drift of the existing carbon ceramic closing resistor. The carbon ceramic closing resistor comprises beta-SiC, alpha-Al2O3, nano-SiC coated carbon fiber, ZrB2, modified montmorillonite, Y2O3 and La2O3. The modified montmorillonite is obtained by carrying out intercalation treatment on montmorillonite by using hexadecyl trimethyl ammonium bromide. The nano-SiC coated carbon fiber is obtained by the following steps: carrying out plasma oxidation treatment on carbon fiber, then immersing the carbon fiber in a gamma-glycidyl ether oxygen propyl trimethoxysilane ethanol solution, drying, and then depositing trichloromethyl silane as a precursor on the surface of the carbon fiber by CVD. The application can be applied to super-high voltage circuits and meets the long-term operation requirement of high-voltage circuit breakers.

Description

Technical Field

[0001] This invention relates to the field of closing resistor technology for ultra-high voltage circuits, specifically to a carbon ceramic closing resistor and its preparation method. Background Technology

[0002] In the field of high-voltage circuit breakers, carbon-ceramic composite closing resistors are key functional components, playing a crucial role in limiting operational overvoltages and ensuring system safety. Their typical structure consists of a conductive phase and a ceramic matrix. Currently, research on this material system mainly focuses on macroscopic structural issues such as the uniformity of the conductive phase dispersion and the bonding strength at the two-phase interface, and various process optimization schemes have been developed. However, in the actual operation of UHV circuit breakers of 330kV and above, it has been found that the high temperature and high pressure conditions caused by frequent operation induce dynamic changes in carrier scattering behavior at the interface between the conductive and ceramic phases with temperature, leading to a significant nonlinear drift in the temperature coefficient of resistance (TCR), severely affecting the accuracy and reliability of equipment operation. When the resistor temperature rises from room temperature to 300℃, the TCR is in the negative coefficient range of -500 to -800ppm / ℃; however, when the temperature continues to rise to 300~500℃, the TCR sharply reverses to the positive coefficient range of +300~+500ppm / ℃. This abnormal nonlinear characteristic causes the control accuracy of circuit breaker overvoltage to decrease by 15% to 20%, and in extreme cases, it may even cause the protection system to malfunction, posing a threat to the stability of the power grid.

[0003] Essentially, the aforementioned TCR nonlinear drift phenomenon stems from the inherent limitations of the traditional carbon black conductive phase under multi-field coupling conditions such as high temperature, high pressure, and electric field. Specifically, numerous dangling bonds and lattice defects exist at the carbon black-ceramic interface, forming electron traps with a depth of approximately 0.2–0.5 eV. At low temperatures, these traps capture charge carriers, leading to increased resistance and exhibiting positive TCR characteristics. As the temperature rises, the charge carriers are thermally excited and escape the traps, causing a sharp decrease in resistivity, and the TCR changes from positive to negative. On the other hand, because the conductive pathways between carbon black particles rely on point contacts, there is a significant difference in the coefficient of thermal expansion between carbon black and common ceramic matrices (Δα≈8×10⁻⁶). -6 At high temperatures (°C), increased interfacial stress causes contact point separation, leading to degradation or even breakage of the conductive network and resulting in a jump in resistance. Furthermore, when the temperature exceeds 360°C, carbon black gradually undergoes oxidation, generating gases such as CO / CO2 and leaving micropores in the interfacial region. This further exacerbates carrier scattering, increasing the fluctuation range of the TCR curve by more than 30%, severely impairing the stability of the resistance.

[0004] To address the above issues, the industry has attempted to improve the situation using methods such as in-situ carbon structure generation and nano-coating modification. While these solutions can mitigate the impact of a single factor to some extent, they consistently fail to address the synergistic effects of thermal expansion mismatch, interface trapping effects, and high-temperature oxidation, thus failing to fundamentally resolve the TCR nonlinear drift problem. This has long constrained the large-scale application of carbon ceramic closing resistors in the ultra-high voltage field.

[0005] Therefore, there is an urgent need to develop a comprehensive technical solution that can simultaneously suppress interface traps, improve thermal matching, and enhance high-temperature oxidation resistance, starting from the design of material systems and the coupling mechanism of multiphysics fields, in order to break through this technical bottleneck that has plagued the industry for many years. Summary of the Invention

[0006] To address the TCR nonlinear drift problem in existing carbon ceramic closing resistors, this invention proposes a carbon ceramic closing resistor and its preparation method.

[0007] A carbon ceramic closing resistor, characterized in that it comprises the following components in parts by mass: β-SiC, 55-60 parts; α-Al2O3, 15-18 parts; nano-SiC-coated carbon fibers, 8-12 parts; ZrB2, 3-5 parts; modified montmorillonite, 3-4 parts; Y2O3, 1-1.5 parts; La2O3, 1-1.5 parts; The modified montmorillonite is obtained by intercalation of montmorillonite with hexadecyltrimethylammonium bromide (CTAB); The nano-SiC-coated carbon fibers are obtained through the following steps: S1. At room temperature, carbon fibers are subjected to plasma oxidation treatment at a power of 120~150W for 10min~15min in an oxygen-nitrogen mixed atmosphere with a volume ratio of 3:7. S2. Immerse in a 2.5wt%~3wt% γ-glycidyl etheroxypropyltrimethoxysilane (KH-560) ethanol solution at 65℃~70℃ for 35min~40min, and then dry at 80℃ for 2h. S3. Using trichloromethylsilane (CH3SiCl3) as a precursor, a SiC coating layer is formed on the surface of carbon fibers by CVD deposition at 1000℃~1100℃ and 500sccm argon atmosphere for 90min~120min.

[0008] Preferably, the β-SiC particle size D50 is 1.2μm~1.5μm; the α-Al2O3 particle size D50 is 0.8μm~1.0μm; the ZrB2 particle size D50 is 0.5μm~0.7μm; and the Y2O3 and La2O3 particle sizes D50 are both 0.3μm~0.5μm.

[0009] Preferably, the mass ratio of hexadecyltrimethylammonium bromide to montmorillonite is 0.2:1, the intercalation treatment temperature is 80°C, and the treatment time is 4 hours.

[0010] Preferably, the carbon fiber is PAN-based short-cut carbon fiber with a length of 5~20μm and a diameter of 0.2~2μm.

[0011] Preferably, the component comprises the following parts by mass: β-SiC, 58 parts; α-Al2O3, 16 parts; nano-SiC-coated carbon fiber, 10 parts; ZrB2, 4 parts; modified montmorillonite, 4 parts; Y2O3, 1.5 parts; La2O3, 1.5 parts.

[0012] The present invention also provides a method for preparing the above-mentioned carbon ceramic closing resistor, comprising the following steps: T1. Add β-SiC, α-Al2O3, ZrB2, modified montmorillonite, Y2O3 and La2O3 to a deionized water-ethanol mixed solvent, then add Triton X-100 and hydroxyethyl cellulose, and stir to form a uniform ceramic slurry. T2. Add nano-SiC-coated carbon fibers and stir evenly to obtain a conductive slurry; T3. Inject the conductive paste into the mold, hold the pressure and then release the pressure in stages to demold. T4. Using a vacuum sintering furnace, under a nitrogen atmosphere at 300 sccm, heat to 600℃ at a heating rate of 2℃ / min, and hold for 180 min; then under a 1:1 nitrogen-argon mixed atmosphere at 500 sccm, heat to 1450℃ at a heating rate of 5℃ / min, and hold for 240 min; then under an argon atmosphere at 800 sccm, heat to 1700℃ at a heating rate of 4℃ / min, and hold for 300 min; finally, cool to 1200℃ at a rate of 3℃ / min, and then cool to room temperature at a rate of 5℃ / min. T5. Grind the surface with a diamond grinding wheel and apply plasma spraying to the electrode to obtain a carbon ceramic closing resistor.

[0013] Preferably, the volume ratio of deionized water to ethanol in step T1 is 7:3.

[0014] Preferably, the amount of Triton X-100 added is 0.6wt% to 0.8wt% of the total amount of β-SiC, α-Al2O3, ZrB2, modified montmorillonite, Y2O3 and La2O3, and the amount of hydroxyethyl cellulose added is 0.2wt% to 0.3wt% of the total amount of β-SiC, α-Al2O3, ZrB2, modified montmorillonite, Y2O3 and La2O3.

[0015] Preferably, the stirring speed in steps T1 and T2 is 2000 r / min to 2500 r / min, and the stirring time is 20 min to 30 min.

[0016] Preferably, the temperature for pressure holding and molding in step T3 is 55℃~60℃, the pressure is 45MPa~50MPa, and the molding time is 80s~90s.

[0017] This invention solves the technical problem of nonlinear drift in existing carbon ceramic closing resistors (TCRs), and its specific beneficial effects are as follows: This invention achieves precise control over the particle size of each ceramic phase, with carbon fiber and β-SiC respectively serving as... Conductive In addition to the core structure, α-Al₂O₃ and ZrB₂ fill the gaps to reduce porosity, while ultrafine Y₂O₃ / La₂O₃ is uniformly distributed at the grain boundaries to inhibit abnormal grain growth. This design not only improves the product's density but also effectively narrows the full-temperature range TCR fluctuation, fundamentally alleviating the TCR nonlinear drift problem. Replacing graphite with carbon fiber transforms the conductive network from point contact to line / surface contact. Using a material with a moderate coefficient of thermal expansion to fill the pores reduces the impact of thermal expansion mismatch caused by temperature changes.

[0018] This invention employs nano-SiC-coated modified PAN-based short-cut carbon fibers to prevent direct reaction between the fibers and the matrix, thus avoiding the formation of brittle phases. Simultaneously, plasma oxidation and KH-560 silane modification enhance interfacial bonding. The short-cut length ensures uniform dispersion of the fibers within the matrix, forming a continuous conductive network, significantly improving interfacial bonding strength, with a flexural strength ≥260 MPa. Furthermore, the coated and modified carbon fibers form a multi-layered continuous transition interface of C-SiC-SiO2 with the matrix, filling dangling bonds and lattice defects, and resolving the trapping effect of traditional C-oxide interfaces.

[0019] This invention employs a multi-atmosphere segmented sintering process, which thoroughly removes organic components to avoid interference from residual carbon, inhibits carbon fiber oxidation, and promotes interfacial reactions to generate a low-melting-point glassy phase. The high atomic weight of argon gas suppresses SiC volatilization, densification is achieved through solid-state diffusion, and the oxidation resistance of SiC solves the problem of high-temperature oxidation. Ultimately, this ensures that the sintered product is free of oxidation and volatilization defects, has high phase purity, and exhibits tight interlayer bonding, meeting the long-term operational requirements of high-voltage circuit breakers. Attached Figure Description

[0020] Figure 1 This is a scanning electron microscope image of the carbon fibers coated with nano-SiC in Example 1; Figure 2 The image shows the XRD pattern of the modified montmorillonite in Example 2. Figure 3 This is a scanning electron microscope image of the carbon ceramic closing resistor substrate in Example 3. Detailed Implementation

[0021] To make the technical solutions of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that the following embodiments are only used to better understand the technical solutions of the present invention and should not be construed as limiting the present invention.

[0022] Example 1. This embodiment prepares a nano-SiC-coated carbon fiber, and the specific preparation process is as follows: S1. At room temperature, PAN-based short-cut carbon fibers with a length of 50~100μm and a diameter of 7~10μm were subjected to plasma oxidation treatment at a power of 140W for 12min in an oxygen-nitrogen mixed atmosphere with a volume ratio of 3:7. S2. Immerse in a 2.6wt% γ-glycidyl etheroxypropyltrimethoxysilane (KH-560) ethanol solution, soak at 70℃ for 38 min, and then dry at 80℃ for 2 h. S3. Using trichloromethylsilane (CH3SiCl3) as a precursor, deposition was carried out by CVD at 1050℃ and 500 sccm argon atmosphere for 100 min.

[0023] S4. Characterize the treated carbon fibers, such as... Figure 1 As shown.

[0024] from Figure 1 It can be clearly observed that the carbon fiber surface is coated with a continuous and dense nano-SiC coating with uniform thickness, no obvious exposed carbon fiber matrix areas, and no defects such as coating agglomeration or localized peeling. This provides a structural basis for subsequent construction of C-SiC-ceramic matrix multilayer transition interfaces, improvement of the interphase interface bonding state, and suppression of interfacial carrier trapping effects.

[0025] Example 2. This embodiment prepares a modified montmorillonite, and the specific preparation process is as follows: The intercalation treatment temperature is 80℃, and the treatment time is 4 hours; S1. Slowly add the dried sodium montmorillonite powder to 60°C deionized water and stir at 800 rpm for at least 2 hours to fully open its layered structure. S2. Weigh the corresponding mass of CTAB according to the mass ratio of 0.2:1 and dissolve it in deionized water at 60°C. S3. The CTAB solution was slowly added dropwise to the pre-dispersed montmorillonite suspension under vigorous stirring at 1000 rpm. The mixture was heated to 80°C in an oil bath and kept at a constant temperature for 4 hours. S4. Cool the mixture naturally to room temperature, then filter it to collect the modified montmorillonite filter cake, wash it repeatedly with deionized water, dry it to constant weight in a vacuum drying oven, grind it, and pass it through a 200-mesh sieve to obtain modified montmorillonite.

[0026] S5. Characterize the modified montmorillonite using X-ray diffraction, such as... Figure 2 As shown in the figure, the intercalated montmorillonite retains the characteristic diffraction peaks of its layered structure, and these peaks are significantly shifted towards smaller angles compared to native sodium-based montmorillonite, corresponding to a significant increase in the interlamellar spacing. This indicates that the hexadecyltrimethylammonium bromide cation has been successfully inserted between the lamellar structures of montmorillonite, achieving organic intercalation modification and verifying the effectiveness of the intercalation process parameters in this embodiment. The modified montmorillonite can better fulfill its filling, densification, and grain boundary regulation functions in the ceramic matrix.

[0027] Example 3. This embodiment provides a carbon ceramic closing resistor, and the specific preparation process is as follows: S1. All raw materials were wet-milled to the following particle sizes: β-SiC particle size D50 is 1.2μm~1.5μm, α-Al2O3 particle size D50 is 0.8μm~1.0μm, ZrB2 particle size D50 is 0.5μm~0.7μm, and Y2O3 and La2O3 particle size D50 is 0.3μm~0.5μm. S2. Weigh β-SiC, α-Al2O3, the nano-SiC-coated carbon fiber prepared in Example 1, ZrB2, the modified montmorillonite prepared in Example 2, Y2O3, and La2O3 in a mass ratio of 58:16:10:4:4:1.5:1.5. S3. Add β-SiC, α-Al2O3, ZrB2, modified montmorillonite, Y2O3 and La2O3 to a deionized water-ethanol mixed solvent with a volume ratio of 7:3, add 0.7wt% Triton X-100 and 0.3wt% hydroxyethyl cellulose, and stir at 2000 r / min for 20 min to form a uniform ceramic slurry. S4. Add nano-SiC-coated carbon fibers and stir at 2500 r / min for 30 min to obtain conductive slurry; S5. Inject the conductive paste into the mold, hold the pressure at 60℃ and 50MPa for 90s to form, and then release the pressure in stages to demold. S6. Using a vacuum sintering furnace, under a nitrogen atmosphere at 300 sccm, heat to 600℃ at a heating rate of 2℃ / min, and hold for 180 min; then under a 1:1 nitrogen-argon mixed atmosphere at 500 sccm, heat to 1450℃ at a heating rate of 5℃ / min, and hold for 240 min; then under an argon atmosphere at 800 sccm, heat to 1700℃ at a heating rate of 4℃ / min, and hold for 300 min; finally, cool to 1200℃ at a rate of 3℃ / min, and then cool to room temperature at a rate of 5℃ / min. S7. Characterize the surface of the prepared carbon ceramic closing resistor substrate, such as... Figure 3 As shown, the ceramic matrix exhibits a dense overall structure with uniform phase distribution and no obvious macroscopic defects such as large pores or cracks. The matrix grains are uniformly sized, with no abnormal grain growth observed. The carbon fibers are uniformly dispersed within the ceramic matrix, exhibiting good bonding with the matrix without obvious interface gaps or separation. This demonstrates that the multi-component gradation design combined with the multi-atmosphere segmented sintering process of this invention can achieve excellent densification and uniform dispersion of the carbon ceramic matrix, providing microstructural assurance for constructing a stable and continuous conductive network and improving the material's mechanical properties and overall resistance temperature stability.

[0028] S8. Grind the surface with a diamond grinding wheel and apply Ag electrode by plasma spraying to obtain a carbon ceramic closing resistor sample.

[0029] Example 4. This embodiment provides a carbon ceramic closing resistor, and the specific preparation process is as follows: S1. All raw materials were wet-milled to the following particle sizes: β-SiC particle size D50 is 1.2μm~1.5μm, α-Al2O3 particle size D50 is 0.8μm~1.0μm, ZrB2 particle size D50 is 0.5μm~0.7μm, and Y2O3 and La2O3 particle size D50 is 0.3μm~0.5μm. S2. Weigh β-SiC, α-Al2O3, the nano-SiC-coated carbon fiber prepared in Example 1, ZrB2, the modified montmorillonite prepared in Example 2, Y2O3, and La2O3 in a mass ratio of 56:15:8:3:3:1:1. S3. Add β-SiC, α-Al2O3, ZrB2, modified montmorillonite, Y2O3 and La2O3 to a deionized water-ethanol mixed solvent with a volume ratio of 7:3, add 0.7wt% Triton X-100 and 0.3wt% hydroxyethyl cellulose, and stir at 2000 r / min for 20 min to form a uniform ceramic slurry. S4. Add nano-SiC-coated carbon fibers and stir at 2500 r / min for 30 min to obtain conductive slurry; S5. Inject the conductive paste into the mold, hold the pressure at 60℃ and 50MPa for 90s to form, and then release the pressure in stages to demold. S6. Using a vacuum sintering furnace, under a nitrogen atmosphere at 300 sccm, heat to 600℃ at a heating rate of 2℃ / min, and hold for 180 min; then under a 1:1 nitrogen-argon mixed atmosphere at 500 sccm, heat to 1450℃ at a heating rate of 5℃ / min, and hold for 240 min; then under an argon atmosphere at 800 sccm, heat to 1700℃ at a heating rate of 4℃ / min, and hold for 300 min; finally, cool to 1200℃ at a rate of 3℃ / min, and then cool to room temperature at a rate of 5℃ / min. S7. Grind the surface with a diamond grinding wheel and apply Ag electrode by plasma spraying to obtain a carbon ceramic closing resistor sample.

[0030] Example 5. This embodiment provides a carbon ceramic closing resistor, and the specific preparation process is as follows: S1. All raw materials were wet-milled to the following particle sizes: β-SiC particle size D50 is 1.2μm~1.5μm, α-Al2O3 particle size D50 is 0.8μm~1.0μm, ZrB2 particle size D50 is 0.5μm~0.7μm, and Y2O3 and La2O3 particle size D50 is 0.3μm~0.5μm. S2. Weigh β-SiC, α-Al2O3, the nano-SiC-coated carbon fiber prepared in Example 1, ZrB2, the modified montmorillonite prepared in Example 2, Y2O3, and La2O3 in a mass ratio of 60:17:11:5:5:1:1. S3. Add β-SiC, α-Al2O3, ZrB2, modified montmorillonite, Y2O3 and La2O3 to a deionized water-ethanol mixed solvent with a volume ratio of 7:3, add 0.7wt% Triton X-100 and 0.3wt% hydroxyethyl cellulose, and stir at 2000 r / min for 20 min to form a uniform ceramic slurry. S4. Add nano-SiC-coated carbon fibers and stir at 2500 r / min for 30 min to obtain conductive slurry; S5. Inject the conductive paste into the mold, hold the pressure at 60℃ and 50MPa for 90s to form, and then release the pressure in stages to demold. S6. Using a vacuum sintering furnace, under a nitrogen atmosphere at 300 sccm, heat to 600℃ at a heating rate of 2℃ / min, and hold for 180 min; then under a 1:1 nitrogen-argon mixed atmosphere at 500 sccm, heat to 1450℃ at a heating rate of 5℃ / min, and hold for 240 min; then under an argon atmosphere at 800 sccm, heat to 1700℃ at a heating rate of 4℃ / min, and hold for 300 min; finally, cool to 1200℃ at a rate of 3℃ / min, and then cool to room temperature at a rate of 5℃ / min. S7. Grind the surface with a diamond grinding wheel and apply Ag electrode by plasma spraying to obtain a carbon ceramic closing resistor sample.

[0031] Comparative Example 1. β-SiC, α-Al₂O₃, unmodified carbon fiber, ZrB₂, kaolin, Y₂O₃, and La₂O₃ were weighed in a mass ratio of 58:16:10:4:4:1.5:1.5 and added to a deionized water-ethanol mixed solvent with a volume ratio of 7:3. 0.7wt% Triton X-100 and 0.3wt% hydroxyethyl cellulose were added and stirred until homogeneous. The slurry was poured into a mold and molded under pressure at 60℃ and 50MPa for 90s, followed by step-down demolding. The sintering was then carried out in a vacuum sintering furnace under a nitrogen atmosphere of 300sccm at a pressure of 2... The temperature was increased to 600℃ at a heating rate of ℃ / min and then held for 180 min. Then, in a 1:1 nitrogen-argon mixed atmosphere at 500 sccm, the temperature was increased to 1450℃ at a heating rate of 5℃ / min and held for 240 min. Then, in an argon atmosphere at 800 sccm, the temperature was increased to 1700℃ at a heating rate of 4℃ / min and held for 300 min. Finally, the temperature was decreased to 1200℃ at a heating rate of 3℃ / min and then decreased to room temperature at a heating rate of 5℃ / min. The surface was ground with a diamond wheel and an Ag electrode was plasma-sprayed to obtain a carbon ceramic closing resistor.

[0032] Comparative Example 2. The sintering process in step S6 is as follows: using a vacuum sintering furnace, under a nitrogen atmosphere of 500 sccm, the temperature is raised to 600℃ at a heating rate of 2℃ / min, and then held for 180 min; then the temperature is raised to 1700℃ at a heating rate of 5℃ / min, and held for 300 min; finally, the temperature is lowered to room temperature at a rate of 5℃ / min.

[0033] The remaining steps are the same as in Example 3.

[0034] Example of an effect 1. The resistance samples from Examples 3-5 and Comparative Examples 1-2 were placed in a high and low temperature test chamber, the temperature was set to 25℃, and after being kept at the temperature for 60 minutes, the resistance value was measured using a four-probe tester. The measurement was repeated 5 times, and the average value was taken as the reference resistance R.

[0035] Perform temperature cycling tests according to the following procedure: The temperature was lowered to -60℃ at a rate of 2℃ / min, and the resistance value was measured after holding at that temperature for 30 minutes. The resistance value was measured after heating to 25℃ at a rate of 3℃ / min and holding at that temperature for 30min. Continue to raise the temperature sequentially to 100℃, 200℃, 300℃, 400℃, 500℃, and 600℃ at a rate of 3℃ / min. After holding at each temperature for 30 minutes, measure the corresponding resistance value.

[0036] Calculate the TCR value for each temperature range using the formula: TCR = (R2- R1) / (R1× (T2- T1)), Where R1 and R2 are the resistance values ​​at the two endpoints of the temperature range, and T1 and T2 are the corresponding temperature values.

[0037] Next, calculate the average TCR value across the entire temperature range, and then calculate the deviation rate between the TCR value and the average TCR value for each temperature range. The maximum value of the deviation rate is taken as the TCR nonlinear drift index of the sample.

[0038]

[0039] Example of effect 2. The sample was cut into strips of 3mm×4mm×30mm and the surface was polished with a diamond wheel. The three-point bending method was used, with a span of 20mm, and the sample was loaded at a displacement rate of 0.5mm / min until it fractured. The fracture load was recorded and the bending strength was calculated.

[0040]

[0041] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A carbon ceramic closing resistor, characterized in that, The components include the following parts by mass: β-SiC, 55-60 parts; α-Al2O3, 15-18 parts; nano-SiC-coated carbon fibers, 8-12 parts; ZrB2, 3-5 parts; modified montmorillonite, 3-4 parts; Y2O3, 1-1.5 parts; La2O3, 1-1.5 parts; The modified montmorillonite is obtained by intercalation of montmorillonite with hexadecyltrimethylammonium bromide; The nano-SiC-coated carbon fibers are obtained through the following steps: S1. At room temperature, carbon fibers are subjected to plasma oxidation treatment at a power of 120~150W for 10min~15min in an oxygen-nitrogen mixed atmosphere with a volume ratio of 3:

7. S2. Soak in a 2.5wt%~3wt% γ-glycidyl etheroxypropyltrimethoxysilane ethanol solution, then dry. S3. Using trichloromethylsilane as a precursor, a SiC coating layer is formed on the surface of carbon fiber by CVD deposition at 1000℃~1100℃ and 500sccm argon atmosphere.

2. The carbon ceramic closing resistor according to claim 1, characterized in that, The β-SiC particle size D50 is 1.2 μm to 1.5 μm; the α-Al₂O₃ particle size D50 is 0.8 μm to 1.0 μm; the ZrB₂ particle size D50 is 0.5 μm to 0.7 μm; and the Y₂O₃ and La₂O₃ particle sizes D50 are both 0.3 μm to 0.5 μm.

3. The carbon ceramic closing resistor according to claim 1, characterized in that, The mass ratio of hexadecyltrimethylammonium bromide to montmorillonite is 0.2:1, the intercalation treatment temperature is 80℃, and the treatment time is 4h.

4. The carbon ceramic closing resistor according to claim 1, characterized in that, The carbon fiber is PAN-based short-cut carbon fiber with a length of 5~20μm and a diameter of 0.2~2μm.

5. The carbon ceramic closing resistor according to claim 1, characterized in that, The components include the following parts by mass: β-SiC, 58 parts; α-Al2O3, 16 parts; nano-SiC-coated carbon fiber, 10 parts; ZrB2, 4 parts; modified montmorillonite, 4 parts; Y2O3, 1.5 parts; La2O3, 1.5 parts.

6. A method for preparing a carbon ceramic closing resistor as described in claims 1-5, characterized in that, Includes the following steps: T1. Add β-SiC, α-Al2O3, ZrB2, modified montmorillonite, Y2O3 and La2O3 to a deionized water-ethanol mixed solvent, then add Triton X-100 and hydroxyethyl cellulose, and stir to form a uniform ceramic slurry. T2. Add nano-SiC-coated carbon fibers and stir evenly to obtain a conductive slurry; T3. Inject the conductive paste into the mold, hold the pressure and then release the pressure in stages to demold. T4. Using a vacuum sintering furnace, under a nitrogen atmosphere at 300 sccm, heat to 600℃ at a heating rate of 2℃ / min, and hold for 180 min; then under a 1:1 nitrogen-argon mixed atmosphere at 500 sccm, heat to 1450℃ at a heating rate of 5℃ / min, and hold for 240 min; then under an argon atmosphere at 800 sccm, heat to 1700℃ at a heating rate of 4℃ / min, and hold for 300 min; finally, cool to 1200℃ at a rate of 3℃ / min, and then cool to room temperature at a rate of 5℃ / min. T5. Grind the surface with a diamond grinding wheel and apply plasma spraying to the electrode to obtain a carbon ceramic closing resistor.

7. The method for preparing the carbon ceramic closing resistor according to claim 6, characterized in that, The volume ratio of deionized water to ethanol in step T1 is 7:

3.

8. The method for preparing the carbon ceramic closing resistor according to claim 6, characterized in that, The amount of Triton X-100 added is 0.6wt%~0.8wt% of the total amount of β-SiC, α-Al2O3, ZrB2, modified montmorillonite, Y2O3 and La2O3, and the amount of hydroxyethyl cellulose added is 0.2wt%~0.3wt% of the total amount of β-SiC, α-Al2O3, ZrB2, modified montmorillonite, Y2O3 and La2O3.

9. The method for preparing the carbon ceramic closing resistor according to claim 6, characterized in that, The stirring speed in steps T1 and T2 is 2000 r / min to 2500 r / min, and the stirring time is 20 min to 30 min.

10. The method for preparing the carbon ceramic closing resistor according to claim 6, characterized in that, The temperature for pressure holding and molding in step T3 is 55℃~60℃, the pressure is 45MPa~50MPa, and the molding time is 80s~90s.

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