Silicon carbide enhanced perfluoroether rubber high-temperature-resistant heat-conducting sealing composite material and preparation process thereof

Abstract

The invention relates to the field of material science and engineering, and particularly discloses a silicon carbide enhanced perfluoroether rubber high-temperature-resistant heat-conducting sealing composite material and a preparation process thereof. The composite material takes perfluoroether rubber as a matrix and comprises silicon carbide filler with specific surface hydroxyl density, the surface hydroxyl density is 1.2-2.5 per square nanometer, and a double-particle-size grading structure is adopted. The preparation method mainly comprises a specific power consumption control mixing process, a specific ratio crosslinking system, vulcanization molding and a post-treatment process comprising secondary vulcanization, temperature programming and surface passivation. According to the composition disclosed by the invention, by optimizing the characteristics and the structure of the filler, the heat-conducting property and the filler-matrix interface bonding strength are remarkably improved; meanwhile, excellent high temperature resistance, chemical stability and sealing performance are achieved. According to the preparation method, by accurately controlling process parameters, the consistency and reliability of the material are improved, the production cost is reduced, and the production efficiency is improved.

Description

Technical Field

[0001] This application relates to the field of materials science and engineering, and more specifically, to silicon carbide reinforced perfluoroether rubber high-temperature thermally conductive sealing composite materials and their preparation process. Background Technology

[0002] In modern industry, particularly in aerospace, automotive manufacturing, and electronics, the demand for thermally conductive sealing materials capable of stable operation in high-temperature environments is increasing. These materials must not only possess good thermal conductivity for rapid heat transfer but also excellent high-temperature resistance and sealing performance to ensure reliability under extreme conditions. Perfluoroelastomer rubber (PFPE) is widely researched and applied due to its outstanding high-temperature resistance and chemical stability. However, the thermal conductivity of pure PFPE is not ideal, limiting its application in high-performance thermally conductive sealing fields.

[0003] To improve the thermal conductivity of PFPE, researchers have attempted to enhance its thermal conductivity by adding thermally conductive fillers such as silicon carbide. Silicon carbide is an ideal filler choice due to its high thermal conductivity and good chemical stability. However, traditional silicon carbide fillers have low surface hydroxyl density and insufficient interfacial bonding strength with the PFPE matrix, resulting in limited improvement in the thermal conductivity of the composite material. Furthermore, interfacial delamination is prone to occur at high temperatures, affecting the long-term stability and reliability of the material.

[0004] The interfacial bonding between traditional silicon carbide fillers and PFPE matrix mainly relies on physical adsorption and lacks strong chemical bonding, resulting in insufficient interfacial bonding strength. Silicon carbide fillers with a single particle size are difficult to form an efficient thermally conductive network in PFPE matrix, which limits the improvement of the thermal conductivity of composite materials. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this application provides a silicon carbide-reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material and its preparation process, which solves the problems of insufficient interfacial bonding strength, low thermal conductivity path density, and poor high-temperature stability of silicon carbide-reinforced perfluoroether rubber composite materials in existing technologies.

[0006] To achieve the above objectives, this application provides the following technical solution: Firstly, this application provides a silicon carbide-reinforced perfluoroether rubber high-temperature resistant and thermally conductive sealing composite material, comprising, by weight percentage: Perfluoroether rubber matrix: 52.0%–57.0%; The surface-modified silicon carbide filler comprises 36.0% to 39.7%, wherein the surface-modified silicon carbide filler comprises a combination of lamellar silicon carbide and fibrous silicon carbide, wherein the lamellar silicon carbide is a β phase with a diameter-to-thickness ratio of 8:1 to 15:1, and the fibrous silicon carbide is a β phase with a length-to-diameter ratio of 20:1 to 50:1. Crosslinking agent 1.8%–2.5%, selected from bis(25) peroxide or bisphenol AF; Crosslinking agent 0.8%–1.2%, selected from triallyl isocyanurate or benzyltriphenylphosphine chloride; Heat stabilizer 3.5%–4.00%, composed of any of the following formulations: Magnesium oxide and cerium oxide are compounded in a weight ratio of 3:1 to 5:1 and have an average particle size ≤5μm; N,N'-Bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,6-hexanediamine; The thermal conductive agent is 0.80% to 2.20%, which is nano-zinc oxide with a particle size of 20 to 100 nm.

[0007] By adopting the above technical solutions, a sealing material that maintains stable performance under extreme temperature and chemical environments is obtained due to the use of a perfluoroether rubber matrix of 52.0%–58.0%, which possesses excellent high-temperature resistance and chemical stability. Furthermore, the use of surface-modified silicon carbide filler of 36.0%–42.0%, comprising a combination of sheet-like and fibrous silicon carbide, yields a composite material with excellent thermal conductivity while maintaining mechanical strength due to the high thermal conductivity and optimized aspect ratio of sheet-like and fibrous silicon carbide. Finally, the use of 1.8%–2.5% crosslinking agent and 0.8%–1.2% co-crosslinking agent promotes effective crosslinking of the rubber matrix. Therefore, a vulcanized network with good mechanical and heat resistance is obtained. Because 3.5%–4.00% heat stabilizer is used, composed of a mixture of magnesium oxide and cerium oxide or N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,6-hexanediamine, these heat stabilizers can improve the thermal stability and oxidation resistance of the material, thus obtaining a sealing material that is not easily aged during long-term use at high temperatures. Because 0.80%–2.20% thermal conductivity aid is used, which is nano-zinc oxide with a particle size of 20–100 nm, the high specific surface area and high thermal conductivity of nano-zinc oxide further enhance the thermal conductivity of the composite material. The surface-modified silicon carbide filler has a surface hydroxyl density of 1.2–2.5 hydroxyl groups / nm. 2 The introduction of surface hydroxyl groups enhances the interfacial bonding between the filler and the rubber matrix, thus obtaining a composite material with better dispersibility and interfacial bonding strength.

[0008] Preferably, the surface-modified silicon carbide filler is obtained by treatment with a silane coupling agent, and its surface hydroxyl density is 1.2–2.5 hydroxyl groups / nm. 2 .

[0009] By employing the above technical solution, silicon carbide is impregnated in an ethanol solution containing 3-aminopropyltriethoxysilane and perfluorooctyltriethoxysilane. Since these two silane coupling agents can provide functional groups compatible with both the silicon carbide surface and the rubber matrix, surface-modified silicon carbide filler is obtained, possessing active groups on its surface that enhance bonding with the rubber matrix. Furthermore, by controlling the liquid-to-solid ratio to 5:1–8:1, this ratio range ensures that the silicon carbide particles are fully coated by the silane coupling agent solution, thus achieving a uniform surface modification effect. Enhance the interfacial bonding between the filler and the matrix; ultrasonically treat at 70℃~85℃ for 30~90min. Since ultrasonic treatment can promote the uniform distribution and penetration of silane coupling agent on the silicon carbide surface, a more uniform surface modified layer is obtained, improving the dispersibility and interfacial bonding strength of the filler; after drying, heat treat at 300℃~380℃ for 1.5~2.5h under nitrogen atmosphere. Since heat treatment can promote the curing and cross-linking of silane coupling agent on the silicon carbide surface, a stable surface modified layer is obtained, improving the thermal stability and heat resistance of the filler.

[0010] Preferably, the mass ratio of the sheet-like silicon carbide to the fibrous silicon carbide is 1.8:1 to 3.5:1; the average particle size of the sheet-like silicon carbide is 15 to 45 μm; and the length of the fibrous silicon carbide is 50 to 150 μm.

[0011] By adopting the above technical solution, the mass ratio of sheet-like silicon carbide to fibrous silicon carbide is controlled at 1.8:1 to 3.5:1. This ratio balances the synergistic effect of the two forms of silicon carbide, thus achieving an optimized construction of the thermal conductivity network in the composite material. The high aspect ratio of the sheet-like silicon carbide enhances in-plane thermal conductivity, while the high aspect ratio of the fibrous silicon carbide improves thermal conductivity through the thickness direction. The average particle size of the sheet-like silicon carbide is 15–45 μm. This particle size range ensures good dispersion of the sheet-like silicon carbide in the rubber matrix while maintaining sufficient mechanical strength and thermal conductivity, thus achieving a balance between mechanical and thermal properties in the composite material. The length of the fibrous silicon carbide is 50–150 μm. This length range ensures that the fibrous silicon carbide forms an effective thermal conductivity path in the composite material while avoiding agglomeration due to excessive length, thus improving the thermal conductivity and optimizing the processing performance of the composite material.

[0012] Preferably, in the surface-modified silicon carbide filler, both the lamellar silicon carbide and the fibrous silicon carbide contain a dual particle size distribution structure: particles with a diameter of 50-100 nm account for 40 wt% to 60 wt% of the total amount of the single-form filler; particles with a diameter of 200-300 nm account for 40 wt% to 60 wt% of the total amount of the single-form filler; and the particle size is the maximum projected dimension of the filler particles.

[0013] By adopting the above technical solution, sheet-like silicon carbide and fibrous silicon carbide contain particles with diameters of 50-100 nm and 200-300 nm. This dual-size distribution structure provides a wider contact area and denser packing, resulting in a more efficient heat conduction path and better stress dispersion. The 50-100 nm particles account for 40 wt% to 60 wt% of the total filler volume, and the 200-300 nm particles account for the same 40 wt% to 60 wt%. This particle size distribution balances the filling efficiency and dispersibility of the filler, thus optimizing the thermal conductivity and processing performance of the composite material. The particle size refers to the maximum projected dimension of the filler particles. This measurement method more accurately reflects the actual packing and contact of the filler in the composite material, resulting in a more precise thermal network construction and mechanical property control.

[0014] Secondly, this application provides a preparation process for a silicon carbide-reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material, employing the following technical solution: The preparation process of silicon carbide reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material includes the following steps: S1. Pretreatment: The perfluoroether rubber matrix is ​​plasticized at 25℃~30℃ for 8~12min with a roller gap of 0.5~1.0mm; S2, First stage mixing: Add surface-modified silicon carbide filler, thermally conductive agent and heat-resistant stabilizer, and mix in stages at 40℃~70℃ and roller gap 1.0~3.0mm, controlling the rotor speed to 45~60rpm; S3, Two-stage mixing: Add crosslinking agent and co-crosslinking agent, and mix at 50℃~70℃ and vacuum degree -0.08MPa to -0.098MPa for 10~30min; S4. Vulcanization molding: Place the rubber compound in a mold and vulcanize it under a pressure of 15-25 MPa.

[0015] By adopting the above technical solution, and through precisely controlled pretreatment, segmented mixing, two-stage mixing, and vulcanization molding steps, a silicon carbide-reinforced perfluoroether rubber high-temperature resistant thermally conductive sealing composite material is obtained. This material exhibits excellent thermal conductivity, high-temperature resistance, and sealing performance, making it suitable for sealing applications in high-temperature environments. Furthermore, precise process control helps improve material consistency and reliability, reduce production costs, and increase production efficiency.

[0016] Preferably, the segmented operation of the mixing process includes: First stage: Roller temperature 40℃~50℃, roller gap 2.0~3.0mm, mixing for 15~20min; Second stage: Heat to 60℃~70℃, roll gap 1.0~1.5mm, mix for 25~35min; Add filler in stages: First add 50wt% filler and mix for 10-20 minutes, then add the remaining filler and mix for 10-20 minutes.

[0017] By adopting the above technical solution, a silicon carbide reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material is obtained by using precise control of temperature, roller gap and filler addition method. This material has excellent thermal conductivity, high temperature resistance and sealing performance, as well as better processing performance and more uniform filler distribution.

[0018] Preferably, after the two-stage mixing step, a vacuum degassing step is further included, wherein the conditions for the vacuum degassing step are as follows: Temperature 85℃~95℃, vacuum degree -0.096~-0.098MPa, time 20~35min; After vacuum degassing, the Mooney viscosity ML(1+4) at 125℃ is 48-68.

[0019] By employing the above technical solution and precisely controlling the temperature, vacuum level, and time, a silicon carbide-reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material is obtained. This material exhibits excellent processability and stability after degassing. This composite material can meet the sealing and thermal conductivity requirements under high-temperature environments, while having fewer air bubbles and a more uniform structure, thus improving the material's reliability and service life.

[0020] Preferably, the S4 vulcanization molding includes: Pre-curing stage: Curing at 160℃~175℃ and 18~25MPa pressure for 5~8min; Main vulcanization stage: vulcanize at 185℃~190℃ and 22~25MPa pressure for 10~15min; During the main vulcanization stage, a gas protection operation is implemented: when the temperature is ≥180℃, nitrogen gas is introduced at a flow rate of 2-4 L / min.

[0021] By adopting the above technical solution, and through precise control of pre-curing and main curing temperatures and pressures, as well as gas protection operations, a silicon carbide-reinforced perfluoroether rubber high-temperature resistant, thermally conductive, and sealing composite material is obtained. This material exhibits excellent high-temperature resistance, thermal conductivity, and sealing performance. Simultaneously, precise curing process control helps improve material consistency and reliability, reduce production costs, and increase production efficiency. Gas protection operations further ensure the material's stability during high-temperature curing, preventing oxidation and thermal degradation, and improving the material's service life and performance.

[0022] Preferably, post-treatment is also included after vulcanization molding: Secondary vulcanization: Increase the temperature to 280℃~310℃ at a rate of 3℃ / min~5℃ / min and hold for 3~6 hours; Programmed temperature rise: Increase to 280℃~300℃ at a rate of 1℃ / min~3℃ / min and hold for 1 hour; Surface passivation: In an inert gas containing 0.8% to 1.2% hexafluoropropylene oxide, treat at 125°C to 135°C for 0.5 to 1.5 hours.

[0023] By employing the above technical solution, and through precisely controlled secondary vulcanization, programmed heating, and surface passivation treatment, a silicon carbide-reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material is obtained. This material not only possesses excellent high-temperature resistance, thermal conductivity, and sealing performance, but also exhibits better chemical corrosion resistance and oxidation resistance. These post-treatment steps help improve the overall performance and reliability of the material, making it more suitable for applications in high-temperature, high-pressure, and chemically corrosive environments.

[0024] Preferably, the peak power consumption during the S2 mixing process is 18-25 kW·h / ton; the weight ratio of the crosslinking agent to the co-crosslinking agent is 2.5:1 to 4:1.

[0025] By adopting the above technical solution and precisely controlling the power consumption and vulcanization system ratio during the mixing process, this technical solution can prepare high-performance silicon carbide reinforced perfluoroether rubber high-temperature thermally conductive sealing composite materials, meeting the sealing and thermal conductivity application requirements in high-temperature environments.

[0026] This application provides a silicon carbide-reinforced perfluoroether rubber high-temperature resistant thermally conductive sealing composite material and its preparation process. It possesses the following beneficial effects: 1. This application achieves the technical effect of improved thermal conductivity and interfacial bonding strength by using silicon carbide filler with a surface hydroxyl density of 1.2 to 2.5 per square nanometer and a dual-particle size distribution structure. Due to the enhanced chemical bonding of the filler-matrix interface by the surface hydroxyl and the optimized thermal conduction path density of the dual-particle size system, the application achieves the technical effect of enhanced thermal conductivity and interfacial bonding strength.

[0027] 2. This application uses a composite filler of sheet-like and fibrous silicon carbide with a mass ratio of 1.8:1 to 3.5:1. Since the sheet-like filler constructs a layered thermally conductive network and the fibrous filler forms a three-dimensional mechanical support skeleton, the technical effect of enhanced high-temperature resistance to compressive deformation and thermal cycling durability is achieved.

[0028] 3. The method of this application adopts a combination of segmented mixing, roller gap gradient control and gradient vulcanization temperature program. Since the segmented process eliminates filler aggregation defects and the gradient temperature rise releases interfacial thermal stress, the technical effect of optimizing material thermal stability and mechanical retention rate after high-temperature aging is achieved. Attached Figure Description

[0029] Figure 1 This is a flowchart of the preparation process of the silicon carbide reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material provided in this application. Detailed Implementation

[0030] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] Technical concept: Under extreme conditions such as high temperature and high pressure, traditional sealing materials often suffer from insufficient performance. Perfluoroelastomers (PFEs) are widely used in sealing applications due to their excellent high-temperature resistance and chemical stability. However, their insufficient thermal conductivity limits their application in scenarios requiring efficient heat transfer. Furthermore, existing manufacturing processes present difficulties in uniformly dispersing reinforcing materials into the rubber matrix, leading to inconsistent material properties.

[0032] Perfluoroether rubber has a low thermal conductivity, which makes it difficult to meet the thermal conductivity requirements in some high-temperature environments, resulting in insufficient thermal conductivity. Traditional mixing processes make it difficult to uniformly disperse silicon carbide in the rubber matrix, resulting in inconsistent material properties and affecting the sealing effect. Under extreme high-temperature conditions, the performance of traditional sealing materials may degrade, affecting the stable operation of equipment.

[0033] This application aims to solve the above-mentioned problems by optimizing the preparation process, and to provide a silicon carbide-reinforced perfluoroether rubber high-temperature resistant, thermally conductive, and sealing composite material. Specific technical means include: 1. Optimize the mixing process: Segmented mixing: A segmented mixing process combining low-temperature large-roll gap pre-dispersion and high-temperature small-roll gap enhanced dispersion is adopted to ensure uniform dispersion of silicon carbide in the rubber matrix.

[0034] Gradual dispersion strategy: Silicon carbide filler is added in stages to reduce local accumulation and improve dispersion efficiency and material performance consistency.

[0035] 2. Vacuum degassing treatment: Vacuum degassing is performed after mixing to eliminate air bubbles and pores in the rubber compound, thereby improving the material's density and thermal conductivity.

[0036] 3. Vulcanization molding process: Pre-vulcanization stage: Initiate the cross-linking reaction at lower temperatures and pressures to avoid early over-vulcanization and optimize the initial structure of the vulcanization network.

[0037] Main vulcanization stage: Accelerates the cross-linking reaction under higher temperature and pressure, improving the compactness and cross-linking density of the vulcanization network.

[0038] Gas protection operation: Nitrogen gas is introduced during the main vulcanization stage to inhibit oxidative degradation, protect the integrity of the vulcanization network, and extend the service life of the material.

[0039] 4. Post-processing techniques: Secondary vulcanization: High-temperature heat treatment is used to eliminate residual cross-linking byproducts and optimize the integrity of the vulcanization network.

[0040] Programmed heating: Finely regulates the vulcanization network structure, reduces thermal stress, and improves the consistency of material properties.

[0041] Surface passivation: Surface treatment is performed in an inert gas to form a dense passivation layer, which improves corrosion resistance and extends the service life of the material.

[0042] High-temperature insulation treatment eliminates residual cross-linking byproducts and optimizes the integrity of the vulcanization network; fine control of the vulcanization network structure reduces thermal stress and improves the consistency of material performance; surface treatment in an inert gas forms a dense passivation layer, improving corrosion resistance and extending the service life of the material.

[0043] In this application, the silicon carbide filler is selected from high-purity silicon carbide powder with uniform particle size to ensure its good dispersion in the rubber matrix; the perfluoroether rubber is made from a commercially available perfluoroether rubber matrix to ensure its high temperature resistance and chemical stability; and the crosslinking agent and co-crosslinking agent are selected appropriately, the vulcanization process is optimized, and the mechanical properties and thermal stability of the material are improved.

[0044] The preparation process of this application is as follows: 1. Raw material preparation: Mix silicon carbide filler and perfluoroether rubber in a certain proportion, and prepare other additives.

[0045] 2. Segmented mixing: Low-temperature large-roll gap pre-dispersion and high-temperature small-roll gap enhanced dispersion, with fillers added gradually to ensure uniform dispersion.

[0046] 3. Vacuum degassing: Eliminate air bubbles and pores in the rubber compound under high temperature and high vacuum conditions.

[0047] 4. Vulcanization molding: Combining pre-vulcanization and main vulcanization optimizes the vulcanization network structure and improves material performance.

[0048] 5. Post-treatment: secondary vulcanization, programmed temperature rise, and surface passivation further optimize material properties and extend service life.

[0049] This application provides a silicon carbide-reinforced perfluoroether rubber high-temperature resistant thermally conductive sealing composite material and its preparation process. The following details the silicon carbide-reinforced perfluoroether rubber high-temperature resistant thermally conductive sealing composite material and its preparation process provided in the embodiments of this application.

[0050] According to a first aspect of this application, this application provides a silicon carbide-reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material, comprising, by weight percentage: Perfluoroether rubber matrix: 52.0%–57.0%; The surface-modified silicon carbide filler is 36.0% to 39.7%, which includes a combination of lamellar silicon carbide and fibrous silicon carbide. The lamellar silicon carbide is the β phase with an aspect ratio of 8:1 to 15:1, and the fibrous silicon carbide is the β phase with an aspect ratio of 20:1 to 50:1. Crosslinking agent 1.8%–2.5%, selected from bis(25) peroxide or bisphenol AF; Crosslinking agent 0.8%–1.2%, selected from triallyl isocyanurate or benzyltriphenylphosphine chloride; Heat stabilizer 3.5%–4.00%, composed of any of the following formulations: Magnesium oxide and cerium oxide are compounded in a weight ratio of 3:1 to 5:1 and have an average particle size ≤5μm; N,N'-Bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,6-hexanediamine; The thermal conductive agent is 0.80% to 2.20%, which is nano-zinc oxide with a particle size of 20 to 100 nm.

[0051] Specifically, the composite of perfluoroether rubber matrix and surface-modified silicon carbide filler plays a role in constructing a thermally conductive network and enhancing mechanical properties, thereby improving the thermal conductivity and interfacial bonding strength of the material. The synergistic effect of crosslinking agent and co-crosslinking agent plays a role in regulating the density of the vulcanization network and the crosslinking efficiency, thereby optimizing the thermal stability and mechanical properties of the material. The composite of heat-resistant stabilizer and thermally conductive additive plays a role in inhibiting thermal oxidative degradation and optimizing the thermal conduction path, thereby improving the thermal durability and thermal conductivity of the material.

[0052] Please see the appendix Figure 1 The surface-modified silicon carbide filler was obtained by treatment with a silane coupling agent, and its surface hydroxyl density was 1.2–2.5 hydroxyl groups / nm. 2 .

[0053] Specifically, the preparation of surface-modified silicon carbide filler includes: impregnating silicon carbide in an ethanol solution containing 3.5% (w / w) of 3-aminopropyltriethoxysilane and 1.5% (w / w) of perfluorooctyltriethoxysilane, with a liquid-to-solid ratio of 6.5:1; ultrasonically treating at 75°C for 60 min; drying and then heat-treating at 350°C for 2.0 h under a nitrogen atmosphere; the synergistic modification by 3-aminopropyltriethoxysilane and perfluorooctyltriethoxysilane introduces amino active groups and low surface energy fluorine segments, thereby improving the dispersibility and interfacial bonding strength of the filler; the synergistic process of ultrasonic treatment and nitrogen atmosphere heat treatment removes surface impurities and forms a stable chemically modified layer, thereby improving the durability of the modification effect and the thermal stability of the material; and the optimized control of the liquid-to-solid ratio of 5:1 to 8:1 balances the consumption of modifier and the uniformity of filler surface coating, thereby improving modification efficiency and reducing costs.

[0054] Please see the appendix Figure 1 The mass ratio of sheet-like silicon carbide to fibrous silicon carbide is 1.8:1 to 3.5:1; the average particle size of the sheet-like silicon carbide is 15 to 45 μm; and the length of the fibrous silicon carbide is 50 to 150 μm.

[0055] Specifically, by optimizing the mass ratio of sheet-like silicon carbide to fibrous silicon carbide from 1.8:1 to 3.5:1, a balance is achieved between the construction of the thermal conductivity network and the strengthening of mechanical support, thereby improving the thermal conductivity and mechanical strength of the material. By optimizing the morphological parameters of the sheet-like silicon carbide with a particle size of 15–45 μm and the fibrous silicon carbide with a length of 50–150 μm, the processability of the rubber matrix and the dispersibility of the filler are matched, thereby improving the density and performance stability of the material. The synergistic effect of the β-phase crystal structure of the sheet-like and fibrous silicon carbide enhances the thermal conductivity and mechanical stability, thereby improving the high-temperature performance and lifespan of the material.

[0056] Please see the appendix Figure 1 In the surface-modified silicon carbide filler, both the lamellar silicon carbide and the fibrous silicon carbide contain a dual particle size distribution structure: particles with a diameter of 50-100nm account for 40wt% to 60wt% of the total amount of the single-form filler; particles with a diameter of 200-300nm account for 40wt% to 60wt% of the total amount of the single-form filler; and the particle size is the maximum projected dimension of the filler particles.

[0057] Specifically, the synergistic gradation of 50-100nm and 200-300nm particles in sheet-like and fibrous silicon carbide fills pores and optimizes the heat conduction path, thereby improving the material's density and thermal conductivity. The simultaneous application of the dual-particle-size gradation structure in sheet-like and fibrous silicon carbide enhances the filler-matrix interface bonding and mechanical properties, thus improving the material's mechanical strength and thermal cycling durability. Furthermore, by defining the particle size in the dual-particle-size gradation structure as the maximum projected dimension of the particles, it precisely controls the filler packing density and heat conduction path, thereby improving the material's performance consistency and repeatability.

[0058] According to the second aspect of this application, this application provides a preparation process for a silicon carbide-reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material, which adopts the following technical solution: See appendix Figure 1 The preparation process of silicon carbide reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material includes the following steps: S1. Pretreatment: The perfluoroether rubber matrix is ​​plasticized at 25℃~30℃ for 8~12min with a roller gap of 0.5~1.0mm; S2, First stage mixing: Add surface-modified silicon carbide filler, thermally conductive agent and heat-resistant stabilizer, and mix in stages at 40℃~70℃ and roller gap 1.0~3.0mm, controlling the rotor speed to 45~60rpm; S3, Two-stage mixing: Add crosslinking agent and co-crosslinking agent, and mix at 50℃~70℃ and vacuum degree -0.08MPa to -0.098MPa for 10~30min; S4. Vulcanization molding: Place the rubber compound in a mold and vulcanize it under a pressure of 15-25 MPa.

[0059] Specifically, the low-temperature plasticizing of the perfluoroether rubber matrix reduces matrix viscosity and improves plasticity, thereby optimizing filler dispersibility and processability. The staged addition and temperature control of surface-modified silicon carbide filler, thermally conductive agent, and heat-resistant stabilizer during the first-stage mixing process eliminates filler aggregation and optimizes the thermally conductive network, thus improving the material's thermal conductivity and thermal stability. The vacuum mixing of crosslinking agents and co-crosslinking agents during the second-stage mixing process eliminates air bubbles and optimizes the vulcanization network, thereby improving the material's density and mechanical properties. Finally, high-pressure vulcanization during vulcanization molding promotes crosslinking reactions and optimizes the filler-matrix interface bonding, thereby improving the material's sealing performance and thermomechanical properties.

[0060] Please see the appendix Figure 1 A segmented mixing process includes: First stage: Roller temperature 40℃~50℃, roller gap 2.0~3.0mm, mixing for 15~20min; Second stage: Heat to 60℃~70℃, roll gap 1.0~1.5mm, mix for 25~35min; Add filler in stages: First add 50wt% filler and mix for 10-20 minutes, then add the remaining filler and mix for 10-20 minutes.

[0061] Specifically, the first stage of pre-dispersion treatment at a low temperature of 40℃~50℃ and a large roller gap of 2.0~3.0mm protects the filler modification layer and achieves initial dispersion, thereby preventing filler agglomeration and damage to the interface modification layer. The second stage of enhanced dispersion treatment at a high temperature of 60℃~70℃ and a small roller gap of 1.0~1.5mm promotes chemical bonding at the filler-matrix interface and optimizes the thermal conductivity network, thereby improving the material's thermal conductivity and thermal stability. The stepwise dispersion strategy of adding filler in stages, first 50wt% and then the remaining 50wt%, reduces local filler accumulation and optimizes dispersion efficiency, thereby improving the consistency of material performance and process controllability. The synergistic optimization of roller gap, temperature, and time in the first and second stages matches the filler morphology and matrix characteristics, thereby improving the overall performance of the material.

[0062] Please see the appendix Figure 1 The process includes a vacuum degassing step after the two-stage mixing step. The conditions for the vacuum degassing step are as follows: Temperature 85℃~95℃, vacuum degree -0.096~-0.098MPa, time 20~35min; After vacuum degassing, the Mooney viscosity ML(1+4) at 125℃ is 48-68.

[0063] Specifically, the synergistic treatment of high temperature (80℃~90℃) and high vacuum (-0.095~-0.098MPa) effectively eliminates air bubbles and pores in the rubber compound, thereby improving the material's density and thermal conductivity. After vacuum degassing, the Mooney viscosity ML(1+4) at 125℃ is controlled at 45~65, optimizing the rubber compound's processability and vulcanization performance, thus improving the material's molding quality and performance consistency. Furthermore, the synergistic optimization of temperature, vacuum degree, and time during vacuum degassing matches the rubber compound's characteristics with process requirements, thereby enhancing the material's overall performance and industrial feasibility. Please see the appendix Figure 1 S4 vulcanization molding includes: Pre-curing stage: Curing at 160℃~175℃ and 18~25MPa pressure for 5~8min; Main vulcanization stage: vulcanize at 185℃~190℃ and 22~25MPa pressure for 10~15min; During the main vulcanization stage, a gas protection operation is implemented: when the temperature is ≥180℃, nitrogen gas is introduced at a flow rate of 2-4 L / min.

[0064] Specifically, the low-temperature and low-pressure treatment in the pre-vulcanization stage promotes the initiation of the cross-linking reaction and avoids early over-vulcanization, thereby optimizing the initial structure of the vulcanized network. The high-temperature and high-pressure treatment in the main vulcanization stage accelerates the cross-linking reaction and optimizes the density of the vulcanized network, thereby improving the mechanical properties and thermal stability of the material. The nitrogen gas protection operation at ≥180℃ in the main vulcanization stage inhibits oxidative degradation and improves the purity of the vulcanized network, thereby extending the service life of the material and improving performance stability. The synergistic optimization of temperature, pressure, and time in the pre-vulcanization and main vulcanization stages, as well as the gas protection operation in the main vulcanization stage, matches the characteristics of the rubber compound with the process requirements, thereby improving the overall performance and industrial feasibility of the material.

[0065] Please see the appendix Figure 1 Post-treatment is also included after vulcanization molding: Secondary vulcanization: Increase the temperature to 280℃~310℃ at a rate of 3℃ / min~5℃ / min and hold for 3~6 hours; Programmed temperature rise: Increase to 280℃~300℃ at a rate of 1℃ / min~3℃ / min and hold for 1 hour; Surface passivation: In an inert gas containing 0.8% to 1.2% hexafluoropropylene oxide, treat at 125°C to 135°C for 0.5 to 1.5 hours.

[0066] Specifically, the high-temperature secondary vulcanization process eliminates residual cross-linking byproducts and optimizes the integrity of the vulcanization network, thereby improving the material's thermal stability and mechanical properties. The gradient temperature-programmed treatment finely controls the vulcanization network structure and reduces thermal stress, thus enhancing the material's performance consistency and reliability. The chemical surface passivation treatment forms a dense passivation layer on the material surface and improves corrosion resistance, extending the material's service life and improving sealing reliability. The synergistic post-treatment of secondary vulcanization, temperature-programmed treatment, and surface passivation comprehensively enhances the material's thermal stability, mechanical properties, corrosion resistance, and sealing reliability, ultimately meeting the long-term sealing requirements under extreme operating conditions.

[0067] Please see the appendix Figure 1 During the S2 mixing process, the peak power consumption is 18-25 kW·h / ton; the weight ratio of crosslinking agent to co-crosslinking agent is 2.5:1 to 4:1.

[0068] Specifically, by controlling the peak power consumption during a mixing process to 18–25 kW·h / ton, the mixing efficiency is optimized and the energy consumption of equipment is reduced, thereby improving the economic efficiency of the process and reducing production costs. By controlling the weight ratio of crosslinking agent to co-crosslinking agent to 2.5:1–4:1, the vulcanization reaction rate is regulated and the vulcanization network structure is optimized, thereby improving the mechanical properties and thermal stability of the material.

[0069] To better understand the above technical solutions, the technical solutions of this application will be clearly and completely described below in conjunction with the embodiments.

[0070] Unless otherwise specified, all experimental methods used below are conventional methods. All materials, reagents, methods, and instruments used, unless otherwise specified, are conventional materials, reagents, methods, and instruments in this field, which can be obtained commercially or prepared according to literature methods by those skilled in the art.

[0071] Example 1 This application provides a silicon carbide-reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material, comprising, by weight percentage: Perfluoroether rubber matrix: 52.0%; The surface-modified silicon carbide filler comprises 39.70%, which includes a combination of lamellar silicon carbide and fibrous silicon carbide. The lamellar silicon carbide is a β phase with an aspect ratio of 8:1, and the fibrous silicon carbide is a β phase with an aspect ratio of 20:1. The particle size distribution is as follows: 50nm particles account for 60wt% and 200nm particles account for 40wt%. The mass ratio of lamellar silicon carbide to fibrous silicon carbide is 1.8:1. Crosslinking agent 1.8%, selected from bis-25 peroxide; 0.8% co-crosslinking agent, selected from triallyl isocyanurate; The heat stabilizer is 3.5%, which is composed of magnesium oxide and cerium oxide in a weight ratio of 3:1, and has an average particle size of 5μm. The thermally conductive agent is 2.2%, which is nano-zinc oxide with a particle size of 100nm; The surface hydroxyl density of the surface-modified silicon carbide filler is 1.2 hydroxyl groups / nm. 2 .

[0072] The preparation process of the above-mentioned silicon carbide reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material includes the following steps: S1. Pretreatment: The perfluoroether rubber matrix is ​​plasticized at 25°C for 12 min with a roll gap of 1.0 mm; S2, First stage mixing: Add surface-modified silicon carbide filler, thermally conductive agent and heat-resistant stabilizer, rotor speed 45rpm, peak power 18.0kW·h / ton; First stage: Roller temperature 40℃, roll gap 3.0mm, mixing for 15min; Second stage: Heat to 60℃, roll gap 1.5mm, mix for 25 minutes.

[0073] S3, Two-stage mixing: Add crosslinking agent and co-crosslinking agent in a weight ratio of 2.5:1, and mix for 30 minutes at 50℃ and vacuum degree -0.08MPa; Following the two-stage mixing step, a vacuum degassing process is also included. The conditions for the vacuum degassing process are as follows: Temperature 90℃, vacuum degree -0.098MPa, time 25min; After vacuum degassing, the Mooney viscosity ML(1+4) of the rubber compound at 125°C is 48. S4. Vulcanization Molding: The rubber compound is placed in a mold and vulcanized under a pressure of 15-25 MPa; including: Pre-curing stage: Curing at 160℃ and 20MPa pressure for 5 minutes; Main vulcanization stage: vulcanize at 190℃ and 25MPa pressure for 12 minutes; During the main vulcanization stage, a gas protection operation is implemented: when the temperature is ≥180℃, nitrogen gas is introduced at a flow rate of 3L / min. Post-treatment is also included after vulcanization molding: Secondary vulcanization: Heat to 280℃ at 3℃ / min and hold for 6 hours; Programmed temperature rise: Increase to 280℃ at a rate of 1℃ / min and hold for 1 hour; Surface passivation: In an inert gas containing 1.0% hexafluoropropylene oxide, the surface was treated at 125°C for 1.5 h.

[0074] The technical effect verification of Example 1 is shown in Table 1.

[0075] Table 1: Performance indicators Test Results Test Standards Thermal conductivity (25℃) 0.88 W / (m·K) ASTM E1461 Compression set at 300℃ (72h) 18.5% GB / T7759.1 Thermal decomposition onset temperature 308℃ TGA, N2 atmosphere Tensile strength after aging at 280℃ for 500 hours 15.7MPa ISO37 Interface bonding strength 6.8MPa GB / T10424 Helium leakage rate (300℃ / 10MPa) <![CDATA[3.2×10~9Pa·m 3 / s]]> ASTM G143 Example 2 This application provides a silicon carbide-reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material, comprising, by weight percentage: Perfluoroether rubber matrix 55.0%; The surface-modified silicon carbide filler comprises 36.30%, wherein the surface-modified silicon carbide filler includes a combination of lamellar silicon carbide and fibrous silicon carbide, wherein the lamellar silicon carbide is a β phase with an aspect ratio of 12:1; the fibrous silicon carbide is a β phase with an aspect ratio of 35:1; the particle size distribution is as follows: 80nm particles account for 50wt% and 250nm particles account for 50wt%; the mass ratio of lamellar silicon carbide to fibrous silicon carbide is 2.5:1. Crosslinking agent 2.0%, selected from bisphenol AF; 1.0% crosslinking agent, selected from BTPPC; The heat stabilizer is 4.0%, a hexamethylenediamine derivative, with an average particle size of 2.5 μm; The thermal conductivity aid is 1.70%, which is nano-zinc oxide with a particle size of 60nm; The surface hydroxyl density of the surface-modified silicon carbide filler is 1.8 hydroxyl groups / nm. 2 .

[0076] The preparation process of the above-mentioned silicon carbide reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material includes the following steps: S1. Pretreatment: The perfluoroether rubber matrix is ​​plasticized at 30°C for 8 minutes with a roll gap of 0.8 mm; S2, First stage mixing: Add surface-modified silicon carbide filler, thermally conductive agent and heat-resistant stabilizer, rotor speed 55rpm, peak power 21.0kW·h / ton; First stage: Roller temperature 45℃, roller gap 2.5mm, mixing for 18min; Second stage: Heat to 65℃, roll gap 1.2mm, mix for 28 minutes.

[0077] S3, Two-stage mixing: Add crosslinking agent and co-crosslinking agent at a weight ratio of 3.0:1, and mix for 20 minutes at 60℃ and vacuum degree -0.095MPa; Following the two-stage mixing step, a vacuum degassing process is also included. The conditions for the vacuum degassing process are as follows: Temperature 85℃, vacuum degree -0.096MPa, time 35min; After vacuum degassing, the Mooney viscosity ML(1+4) of the rubber compound at 125°C is 58. S4. Vulcanization Molding: The rubber compound is placed in a mold and vulcanized under a pressure of 15-25 MPa; including: Pre-curing stage: Curing at 165℃ and 18MPa pressure for 8 minutes; Main vulcanization stage: vulcanize at 185℃ and 22MPa pressure for 15 minutes; During the main vulcanization stage, a gas protection operation is implemented: when the temperature is ≥180℃, argon gas is introduced at a flow rate of 2L / min. Post-treatment is also included after vulcanization molding: Secondary vulcanization: Heat to 295℃ at a rate of 4℃ / min and hold for 4.5 hours; Programmed temperature rise: Increase to 300℃ at 2℃ / min and hold for 1 hour; Surface passivation: In an inert gas containing 0.8% hexafluoropropylene oxide, the surface was treated at 130°C for 1.0 h.

[0078] The technical effect verification of Example 2 is shown in Table 2.

[0079] Table 2: Performance indicators Test Results Test Standards Thermal conductivity (25℃) 1.41 W / (m·K) ASTM E1461 Compression set at 300℃ (72h) 12.3% GB / T7759.1 Thermal decomposition onset temperature 326℃ TGA, N2 atmosphere Elongation at break after aging at 280℃ for 500 hours 230% ISO37 Interface bonding strength 12.4MPa GB / T10424 2000 cycles of thermal cycling (-65-300℃) Zero failures ECSS-Q-70~21A Example 3 This application provides a silicon carbide-reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material, comprising, by weight percentage: Perfluoroether rubber matrix: 57.0%; The surface-modified silicon carbide filler comprises 36.00%, wherein the surface-modified silicon carbide filler includes a combination of lamellar silicon carbide and fibrous silicon carbide, wherein the lamellar silicon carbide is a β phase with an aspect ratio of 15:1; the fibrous silicon carbide is a β phase with an aspect ratio of 50:1; the particle size distribution is: 100nm particles account for 40wt% and 300nm particles account for 60wt%; the mass ratio of lamellar silicon carbide to fibrous silicon carbide is 3.5:1; Crosslinking agent 2.5%, selected from bisphenol AF; 1.2% crosslinking agent, selected from BTPPC; The heat stabilizer is 3.50%, composed of magnesium oxide and cerium oxide in a weight ratio of 5:1, with an average particle size of 1.2μm. The thermal conductivity additive is 0.80%, which is nano-zinc oxide with a particle size of 20nm; The surface hydroxyl density of the surface-modified silicon carbide filler is 2.50 hydroxyl groups / nm. 2 .

[0080] The preparation process of the above-mentioned silicon carbide reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material includes the following steps: S1. Pretreatment: The perfluoroether rubber matrix is ​​plasticized at 28℃ for 10 min with a roller gap of 0.5 mm; S2, First stage mixing: Add surface-modified silicon carbide filler, thermally conductive agent and heat-resistant stabilizer, rotor speed 60rpm, peak power 25.0kW·h / ton; First stage: Roller temperature 50℃, roller gap 2.0mm, mixing for 20min; Second stage: Heat to 70℃, roll gap 1.0mm, mix for 35 minutes.

[0081] S3, Two-stage mixing: Add crosslinking agent and co-crosslinking agent at a weight ratio of 4.0:1, and mix for 10 minutes at 70℃ and vacuum degree -0.098MPa; Following the two-stage mixing step, a vacuum degassing process is also included. The conditions for the vacuum degassing process are as follows: Temperature 95℃, vacuum degree -0.098MPa, time 20min; After vacuum degassing, the Mooney viscosity ML(1+4) of the rubber compound at 125°C is 68. S4. Vulcanization Molding: The rubber compound is placed in a mold and vulcanized under a pressure of 15-25 MPa; including: Pre-curing stage: Curing at 175℃ and 25MPa pressure for 5 minutes; Main vulcanization stage: vulcanize at 190℃ and 25MPa pressure for 10 minutes; During the main vulcanization stage, a gas protection operation is implemented: when the temperature is ≥180℃, argon gas is introduced at a flow rate of 4L / min. Post-treatment is also included after vulcanization molding: Secondary vulcanization: Increase the temperature to 310℃ at a rate of 5℃ / min and hold for 3 hours; Programmed temperature rise: Increase to 300℃ at 3℃ / min and hold for 1 hour; Surface passivation: In an inert gas containing 1.2% hexafluoropropylene oxide, the surface was treated at 135°C for 0.5 h.

[0082] The technical effect verification of Example 3 is shown in Table 3.

[0083] Table 3: Performance indicators Test Results Test Standards Thermal conductivity (25℃) 1.23 W / (m·K) ASTM E1461 Compression set at 300℃ (72h) 15.7% GB / T7759.1 Thermal decomposition onset temperature 318℃ TGA, N2 atmosphere Chemical resistance +1.2% volume change ASTM D471 Continuous service life (300℃) >8000h ISO11346 Table 4 shows a summary table comparing the key performance of Examples 1-3.

[0084] Table 4: Performance indicators Example 1 Example 2 Example 3 Thermal conductivity W / (m·K) 0.88 1.41 1.23 Compression set (300℃ / 72h) 18.5% 12.3% 15.7% Elongation retention rate after heat aging 92% 95% 93% Interface strength MPa 6.8 12.4 9.2 Thermal decomposition temperature (°C) 308 326 318 In summary, Example 2 outperforms Examples 1 and 3 in all five core indicators: thermal conductivity, compression deformation control, aging performance, interfacial strength, and thermal stability; this formulation achieves a balanced improvement in performance.

[0085] Comparative Example 1 This comparative example provides a silicon carbide-reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material, comprising, by weight percentage: Silicon carbide filler: 36.30%, of which the surface state is unmodified, with a surface hydroxyl density of 0.8 hydroxyl groups / nm. 2 ; The other components and proportions are the same as in Example 2.

[0086] The preparation process of the above-mentioned composite material includes the following steps: S1. Pretreatment: Same as in Example 2; S2, First stage of mixing: Add surface hydroxyl groups at a density of 0.8 per nm. 2 Unmodified silicon carbide filler, thermally conductive agent and heat-resistant stabilizer; rotor speed 55 rpm, same as in Example 2; Phase 1: Same as Example 2; Second stage: Same as Example 2; S3, Two-stage mixing: Same as Example 2; Add crosslinking agent and co-crosslinking agent, and mix for 20 minutes at 60°C and vacuum degree -0.095MPa.

[0087] Vacuum degassing treatment: temperature 85℃, vacuum degree -0.096MPa, time 35min.

[0088] Mooney viscosity of the rubber compound ML (1+4) at 125℃: 51; S4. Vulcanization molding: The rubber compound is placed in a mold and vulcanized under a pressure of 20MPa. Pre-curing stage: Curing at 165℃ and 18MPa pressure for 10 minutes; Main vulcanization stage: Same as in Example 2; Gas protection operation: Same as in Example 2; Post-treatment after vulcanization molding: Same as in Example 2.

[0089] Comparative Example 2 This comparative example provides a silicon carbide-reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material, comprising, by weight percentage: Particle size adjustment: The dual-size gradation was removed, and a single-size 165nm particle was adopted; The other components and proportions are the same as in Example 2.

[0090] The preparation process of the above-mentioned composite material includes the following steps: S1. Pretreatment: Same as in Example 2; S2, First stage of mixing: Same as Example 2; Phase 1: Same as Example 2; Second stage: Temperature rise to 65℃, second stage roller gap 0.8mm; peak rotor power: 28.7kW·h / ton.

[0091] S3, Two-stage mixing: Same as Example 2; S4. Vulcanization molding: The rubber compound is placed in a mold and vulcanized under a pressure of 20MPa. Pre-curing stage: Curing at 155℃ and 18MPa pressure for 12 minutes; Main vulcanization stage: Same as in Example 2; Gas protection operation: Same as in Example 2; Post-vulcanization molding processing: Secondary vulcanization: Heat to 290℃ at 2.5℃ / min and hold for 4.5h.

[0092] The temperature ramp-up and surface passivation are the same as in Example 2.

[0093] Comparative Example 3 This comparative example provides a silicon carbide-reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material, with all components the same as in Example 2.

[0094] The preparation process of the above-mentioned composite material includes the following steps: S1-S3: Same as in Example 2; S4. Vulcanization molding: Pre-vulcanization stage: vulcanization at 165℃ and 18MPa pressure for 8 minutes, same as in Example 2.

[0095] Changes to the main vulcanization stage: Temperature gradient control has been removed; constant temperature vulcanization is now performed: 185℃ constant temperature for 15 minutes, with a pressure of 22MPa. Post-processing adjustments: Secondary vulcanization: The temperature was increased to 295℃ at a rate of 4℃ / min and held for 4.5 hours, as in Example 2; Cancel the heating step in the program; Surface passivation: In an inert gas containing 0.5% hexafluoropropylene oxide, the surface was treated at 120°C for 1.0 h.

[0096] The performance comparison test is shown in Table 5.

[0097] Table 5: Performance indicators Test Standards Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Thermal conductivity (25℃) ASTM E1461 1.41 0.85 0.98 1.32 Compression set at 300℃ (72h) GB / T7759.1 12.3% 24.1% 18.7% 16.9% Thermal decomposition onset temperature <![CDATA[TGA (in N2 atmosphere, 10 °C / min)]]> 326℃ 308℃ 315℃ 319℃ Elongation at break after aging at 280℃ for 500 hours ISO37 230% 182% 198% 210% Interface bonding strength GB / T10424 12.4MPa 4.5MPa 7.2MPa 9.8MPa Number of thermal cycling failures (-65-300℃) ECSS-Q-70~21A >2000 times 431 times 892 times 1357 times Combining Example 2 and Comparative Example 1, and referring to Table 5, it can be seen that the surface hydroxyl density of silicon carbide filler has a significant impact on the thermal conductivity and interfacial strength of the material. Specifically, from Comparative Example 1, 0.8 hydroxyl / nm 2 Up to 1.8 units / nm in Example 2 2 The increase in surface hydroxyl density, from 0.85 W / (m·K) to 1.41 W / (m·K), significantly improved the thermal conductivity and interfacial strength, with the interfacial strength increasing from 4.5 MPa to 12.4 MPa. This phenomenon indicates that the increase in surface hydroxyl content promotes chemical bonding between the filler and the matrix, enhances interfacial adhesion, and thus improves the thermal conductivity and mechanical properties of the material.

[0098] Combining Example 2 and Comparative Example 2, and referring to Table 5, it can be seen that the particle size distribution of silicon carbide filler has a significant impact on the thermal conductivity and compressive deformation properties of the material. Example 2 uses a dual-particle-size distribution, while Comparative Example 2 uses a single-particle-size filler. The results show that the thermal conductivity of Example 2 is significantly higher than that of Comparative Example 2, while the compressive deformation is significantly lower. This indicates that the dual-particle-size distribution enhances the heat conduction path by optimizing the packing density and porosity of the filler, while reducing the deformation of the material at high temperatures.

[0099] Combining Example 2 and Comparative Example 3, and referring to Table 5, it can be seen that the gradient temperature rise in the vulcanization process has a significant impact on the thermal decomposition temperature and interfacial strength of the material. Example 2 used a gradient temperature rise process, while Comparative Example 3 used an isothermal vulcanization process. The results show that the thermal decomposition temperature of Example 2 is significantly higher than that of Comparative Example 3, and the interfacial strength is also significantly higher in Example 2. This indicates that the gradient temperature rise process gradually releases thermal stress, avoiding stress concentration within the material, thereby improving the thermal stability and mechanical strength of the material.

[0100] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A silicon carbide-reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material, characterized in that: Included by weight percentage: Perfluoroether rubber matrix: 52.0%–57.0%; The surface-modified silicon carbide filler comprises 36.0% to 39.7%, wherein the surface-modified silicon carbide filler comprises a combination of lamellar silicon carbide and fibrous silicon carbide, wherein the lamellar silicon carbide is a β phase with a diameter-to-thickness ratio of 8:1 to 15:1, and the fibrous silicon carbide is a β phase with a length-to-diameter ratio of 20:1 to 50:

1. Crosslinking agent 1.8%–2.5%, selected from bis(25) peroxide or bisphenol AF; Crosslinking agent 0.8%–1.2%, selected from triallyl isocyanurate or benzyltriphenylphosphine chloride; Heat stabilizer 3.5%–4.00%, composed of any of the following formulations: Magnesium oxide and cerium oxide are compounded in a weight ratio of 3:1 to 5:1 and have an average particle size ≤5μm; N,N'-Bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,6-hexanediamine; The thermal conductive agent is 0.80% to 2.20%, which is nano-zinc oxide with a particle size of 20 to 100 nm.

2. The silicon carbide-reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material according to claim 1, characterized in that: The surface-modified silicon carbide filler was obtained by treatment with a silane coupling agent, and its surface hydroxyl density was 1.2–2.5 hydroxyl groups / nm. 2 .

3. The silicon carbide-reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material according to claim 1, characterized in that: The mass ratio of the sheet-like silicon carbide to the fibrous silicon carbide is 1.8:1 to 3.5:1; the average particle size of the sheet-like silicon carbide is 15 to 45 μm; and the length of the fibrous silicon carbide is 50 to 150 μm.

4. The silicon carbide-reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material according to claim 1, characterized in that: In the surface-modified silicon carbide filler, both the lamellar silicon carbide and the fibrous silicon carbide contain a dual particle size distribution structure: particles with a diameter of 50-100 nm account for 40 wt% to 60 wt% of the total amount of the single-form filler; particles with a diameter of 200-300 nm account for 40 wt% to 60 wt% of the total amount of the single-form filler; and the particle size is the maximum projected dimension of the filler particles.

5. A preparation process for a silicon carbide-reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material, characterized in that, The silicon carbide-reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material according to any one of claims 1-4 includes the following steps: S1. Pretreatment: The perfluoroether rubber matrix is ​​plasticized at 25℃~30℃ for 8~12min with a roller gap of 0.5~1.0mm; S2, First stage mixing: Add surface-modified silicon carbide filler, thermally conductive agent and heat-resistant stabilizer, and mix in stages at 40℃~70℃ and roller gap 1.0~3.0mm, controlling the rotor speed to 45~60rpm; S3, Two-stage mixing: Add crosslinking agent and co-crosslinking agent, and mix at 50℃~70℃ and vacuum degree -0.08MPa to -0.098MPa for 10~30min; S4. Vulcanization molding: Place the rubber compound in a mold and vulcanize it under a pressure of 15-25 MPa.

6. The preparation process of the silicon carbide-reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material according to claim 5, characterized in that: The segmented operation of the mixing process includes: First stage: Roller temperature 40℃~50℃, roller gap 2.0~3.0mm, mixing for 15~20min; Second stage: Heat to 60℃~70℃, roll gap 1.0~1.5mm, mix for 25~35min; Add filler in stages: First add 50wt% filler and mix for 10-20 minutes, then add the remaining filler and mix for 10-20 minutes.

7. The preparation process of the silicon carbide-reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material according to claim 5, characterized in that: The process includes a vacuum degassing step following the two-stage mixing step, wherein the conditions for the vacuum degassing step are as follows: Temperature 85℃~95℃, vacuum degree -0.096~-0.098MPa, time 20~35min; After vacuum degassing, the Mooney viscosity ML(1+4)125℃ of the rubber compound is 48~68.

8. The preparation process of the silicon carbide-reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material according to claim 5, characterized in that: The S4 vulcanization molding includes: Pre-curing stage: Curing at 160℃~175℃ and 18~25MPa pressure for 5~8 minutes; Main vulcanization stage: vulcanize at 185℃~190℃ and 22~25MPa pressure for 10~15min; During the main vulcanization stage, a gas protection operation is implemented: when the temperature is ≥180℃, nitrogen gas is introduced at a flow rate of 2~4L / min.

9. The preparation process of the silicon carbide-reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material according to claim 5, characterized in that: Post-treatment is also included after vulcanization molding: Secondary vulcanization: Increase the temperature to 280℃~310℃ at a rate of 3℃ / min~5℃ / min and hold for 3~6 hours; Programmed temperature rise: Increase to 280℃~300℃ at a rate of 1℃ / min~3℃ / min and hold for 1 hour; Surface passivation: In an inert gas containing 0.8% to 1.2% hexafluoropropylene oxide, treat at 125°C to 135°C for 0.5 to 1.5 hours.

10. The preparation process of the silicon carbide-reinforced perfluoroether rubber high-temperature thermally conductive sealing composite material according to claim 5, characterized in that: The peak power consumption during the S2 mixing process is 18-25 kW·h / ton; the weight ratio of the crosslinking agent to the co-crosslinking agent is 2.5:1 to 4:1.

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