Phenolic resin-based silicon carbide-graphite composite sealing ring and preparation method thereof

Abstract

The invention discloses a phenolic resin-based silicon carbide-graphite composite sealing ring and a preparation method thereof. The phenolic resin-based silicon carbide-graphite composite sealing ring comprises the following components: 20-30 parts of phenolic resin and 40-60 parts of silicon carbide powder. 15 to 30 parts of graphite powder; and 0.05 to 0.1 part of a silane coupling agent. According to the invention, through component optimization of a ternary system, the prepared composite sealing ring realizes coordination of three functions of excellent wear resistance, self-lubricating performance and filtering performance, and overcomes the defect of single performance of a traditional material. Through process innovation, the low-temperature nitrogen sintering process is realized, energy consumption is reduced by about 60% compared with a traditional high-temperature process (1300 DEG C or above), meanwhile, nitrogen protection effectively inhibits graphite oxidation and excessive carbonization of resin, the lubricity and pore structure stability of the material are guaranteed, the process repeatability is good, and the method is suitable for large-scale production.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sealing materials, and particularly relates to a phenolic resin-based silicon carbide-graphite composite sealing ring and a preparation method thereof. BACKGROUND

[0002] At present, the material system of sealing rings in the industrial field mainly includes three categories: metal-based, ceramic-based and resin-based. The metal-based sealing ring is widely used in traditional equipment due to its high strength, but it is prone to accelerated wear under high-speed friction conditions. Although the single silicon carbide ceramic sealing ring has excellent wear resistance, it lacks self-lubricity and has high processing cost. The resin-based sealing ring takes phenolic resin as the matrix, and has low cost but insufficient high-temperature resistance and wear resistance. In addition, the existing sealing materials have single performance, and it is difficult to simultaneously meet the multiple functional requirements of wear resistance, lubrication and filtration, especially in occasions requiring fluid filtration, such as chemical medium conveying equipment. The porosity control and structural stability of traditional materials are particularly prominent.

[0003] In recent years, composite material sealing rings have attracted widespread attention due to their strong performance designability. Among them, silicon carbide-graphite composite materials exhibit good application prospects due to the high hardness of silicon carbide and the self-lubricity of graphite. However, the materials of this type in the prior art usually adopt high-temperature sintering processes (such as above 1300℃), which not only have high energy consumption, but also cause the oxidation of graphite at high temperatures, resulting in a decrease in lubrication performance. At the same time, traditional resin binders have the problems of incomplete curing or poor formability, and are prone to decomposition at high temperatures, making it difficult to form a stable porous structure and unable to meet the porosity requirements of filtration materials. SUMMARY

[0004] In order to overcome the deficiencies of the prior art, the purpose of the present application is to provide a phenolic resin-based silicon carbide-graphite composite sealing ring and a preparation method thereof, which has excellent wear resistance, self-lubricity and filtration performance.

[0005] The present application is achieved by the following technical solutions:

[0006] A phenolic resin-based silicon carbide-graphite composite sealing ring, by weight, comprises the following components:

[0007]

[0008] The phenolic resin is composed of phenolic resin powder and phenolic resin liquid, and the mass ratio of the phenolic resin powder to the phenolic resin liquid is 1:2-4.

[0009] The phenolic resin powder provides a rigid skeleton for the sealing ring and improves structural strength; the phenolic resin liquid improves the fluidity of the mixture, enhances the interface bonding with silicon carbide and graphite, promotes low-temperature curing, and reduces energy consumption. The two can solve the defects of single resin powder (poor forming and weak bonding) and single resin liquid (difficult to store and insufficient rigidity) in a synergistic manner, and finally realize the triple synergy of wear resistance, lubrication and filtration performance of the sealing ring.

[0010] The mass ratio of the phenolic resin powder and the phenolic resin liquid is controlled at 1:2-4, which can ensure that the bonding, curing and pore regulation are optimal. If the mass ratio is less than 1:2, the strength and porosity will decrease due to insufficient infiltration; if the mass ratio is higher than 1:4, the skeleton will be weak and the pores will be out of control.

[0011] The phenolic resin powder described in the application is a thermoplastic phenolic resin, and the average particle size is 50-100 μm, and the free phenol content is less than 0.5%.

[0012] The phenolic resin powder described in the application can be obtained by market purchase, or can be prepared by condensation reaction of phenol and formaldehyde under the action of an acidic catalyst, drying and crushing process. As a preferred embodiment, the phenolic resin powder of the application can be prepared by the following method:

[0013] Phenol 80-100 parts, 37% formaldehyde aqueous solution 120-150 parts, and oxalic acid (acidic catalyst) 0.5-1.2 parts are put into a reaction kettle with stirring device and reflux condenser. After stirring uniformly, the temperature is raised to 85-95℃, and the condensation reaction is carried out under insulation. During the reaction, the reaction degree is controlled by sampling and detecting the viscosity. When the resin viscosity reaches 250-300 cps (25℃), the heating is stopped; then the reaction product is transferred to a spray drying tower, and dried under the conditions of inlet air temperature 180-200℃ and outlet air temperature 80-90℃, to obtain fluffy resin particles. The dried particles are sent to an air jet pulverizer, crushed under a crushing pressure of 0.6-0.8 MPa, sieved, and then mixed uniformly with a curing agent (such as hexamethylenetetramine), to obtain the product.

[0014] The phenolic resin liquid described in the application is a thermosetting phenolic resin, and the solid content is 50-70%, and the viscosity at 25℃ is 300-1200 mPa·s.

[0015] The phenolic resin liquid described in the application can be obtained by market purchase, or can be prepared by condensation reaction of phenol and formaldehyde under the action of an acidic catalyst (such as sodium hydroxide) to generate resole. As a preferred embodiment, the phenolic resin liquid of the application can be prepared by the following method:

[0016] Add 45-55 parts of 37% formaldehyde aqueous solution and 1-2 parts of water into a reaction kettle according to the proportion, adjust the pH to 7.5-10.5 with triethylamine; add 20-25 parts of phenol, heat to 65°C for 10-30 minutes; add 5-10 parts of melamine, add triethylamine to increase the temperature to 80°C, and keep the temperature until the appearance of the cloud point; add 15-20 parts of urea and the remaining water and triethylamine, heat to 85°C until the viscosity reaches 50 cps (25°C); cool to below 35°C to discharge the material, and obtain a phenolic resin liquid with a solid content of 50-70%, a pH value of 8.0-9.0, and a storage stability of ≥3 months (no stratification under the condition of 25°C).

[0017] The phenolic resin powder of the present application is a dry solid powder with an average particle size of 50-100 μm, and poor self-flowability. When mixed with silicon carbide, graphite and other particles, if lacking liquid medium assistance, it is easy to form agglomeration due to excessive inter-particle friction, resulting in decreased mixing uniformity, and it is also difficult to tightly fill the mold during cold pressing, and problems such as loose green body and lack of material at the corners are prone to occur. The phenolic resin liquid is a viscous liquid, and the viscosity can be flexibly controlled by adjusting the solid content, and it can quickly penetrate into the gap between silicon carbide and graphite particles, and play a "bridge" role during the mixing process, so that the solid particles are uniformly dispersed, and during cold pressing, it can flow and fill the gaps with pressure, ensuring uniform green body density and reducing forming defects.

[0018] Preferably, the average particle size of the silicon carbide is 100-200 μm, and the purity is ≥98%. Silicon carbide is an ultra-hard material with a hardness only second to diamond (Vickers hardness 28 GPa), and the rigid skeleton formed can effectively resist abrasive wear and adhesive wear. At the same time, the carbon matrix formed by carbonization of phenolic resin is firmly bonded to the silicon carbide particles through silane coupling agent, improving the overall strength and fracture resistance of the material.

[0019] The content of silicon carbide powder is controlled in the present application to be in the range of 40-60 wt%, which can form a hard skeleton structure with a Vickers hardness of 26-28 GPa and a wear rate as low as 1.2×10 -7 mm 3 / (N·m), which is much lower than that of traditional metal sealing rings.

[0020] Preferably, the average particle size of the graphite powder is 10-50 μm, and the carbon content is ≥99%. The self-lubricating property of graphite is derived from its hexagonal layered crystal structure, and the interlayer is combined by van der Waals force with a binding energy of only about 0.1 eV and a shear strength as low as 0.02 GPa. When the material is subjected to frictional stress, the graphite layers are prone to slip, forming a continuous lubricating film, thereby reducing the friction coefficient.

[0021] In the present application, the content of graphite powder is controlled to be in the range of 15-30 wt%, which not only ensures the continuity of the lubricating film, but also avoids the strength reduction caused by excessive content.

[0022] Preferably, the silane coupling agent is selected from at least one of γ-glycidoxypropyltrimethoxysilane or γ-methacryloyloxypropyltrimethoxysilane.

[0023] The open porosity of the phenolic resin-based silicon carbide-graphite composite sealing ring of the present application is 8-12%, and the permeability is 10 -13 to 10 14 m 2 , while having excellent wear resistance and self-lubricating properties, while taking into account better filtering performance.

[0024] The present application also provides a preparation method of the above-mentioned phenolic resin-based silicon carbide-graphite composite sealing ring, comprising the following steps:

[0025] (1) Raw material mixing: hydrolyze the silane coupling agent and add it to the phenolic resin liquid to mix evenly, obtaining the pretreated phenolic resin liquid; dry mix the phenolic resin powder, silicon carbide powder and graphite powder for 5-10 minutes, then add the pretreated phenolic resin liquid and continue mixing for 10-15 minutes, obtaining a uniform mixture;

[0026] (2) Cold pressing forming: load the mixture into a mold and cold press form under a pressure of 10-20 MPa, obtaining a sealing ring blank;

[0027] (3) Nitrogen sintering: place the blank in a nitrogen protection furnace, heat to 400-500℃ at a heating rate of 3-5℃ / min, keep warm for 2-3 hours, then cool to room temperature with the furnace, obtaining the phenolic resin-based silicon carbide-graphite composite sealing ring.

[0028] The present application adopts a sintering process at 400-500℃ in a nitrogen atmosphere, on the one hand, nitrogen as an inert gas, isolates oxygen, prevents graphite from oxidizing and failing at high temperature; on the other hand, nitrogen inhibits the excessive carbonization of phenolic resin, by controlling the carbonization degree of phenolic resin, 10-50μm connected pores are formed in the material, the open porosity is 8-12%, and the permeability reaches 10 13 orders of magnitude, which can effectively filter solid particles in the medium, while maintaining a certain fluid permeability, meeting the basic requirements of the filtering material, while avoiding the strength reduction caused by shrinkage and cracking of the material.

[0029] Preferably, in step (3), the nitrogen purity in the nitrogen protection furnace is ≥99.9%, and the pressure in the furnace during sintering is kept at 0.1-0.5MPa.

[0030] Compared with the prior art, the present application has the following beneficial effects:

[0031] The phenolic resin powder and the liquid are used in combination, the two synergistically enhance the infiltration and adhesion of silicon carbide and graphite, the interface bonding strength is improved, the curing process is optimized, the energy consumption is reduced and the curing uniformity is ensured, the open porosity of 8-12% is accurately controlled, the filtration and structural strength are considered, meanwhile, the rigidity and toughness of the material are balanced, the wear resistance, lubrication and filtration performance are better, and the problems of poor forming and unbalanced performance of single resin form are solved.

[0032] The composition of the ternary system of phenolic resin, silicon carbide and graphite powder is optimized, and the prepared composite sealing ring realizes the triple function synergy of excellent wear resistance, self-lubricating performance and filtration performance, and overcomes the defects of single performance of traditional materials.

[0033] The low-temperature nitrogen sintering process is realized through process innovation, the energy consumption is reduced by about 60% compared with the traditional high-temperature process (above 1300 DEG C), meanwhile, the graphite oxidation and excessive carbonization of the resin are effectively inhibited under the nitrogen protection, the lubricity and porosity structure stability of the material are ensured, the process repeatability is good, and the process is suitable for large-scale production. DETAILED DESCRIPTION

[0034] The application will be further described through specific embodiments, and the following examples are preferred embodiments of the application, but the embodiments of the application are not limited by the following examples.

[0035] The raw materials used in the application are as follows:

[0036] Silicon carbide powder: particle size 150 μm, purity ≥98%, commercially available.

[0037] Graphite powder: particle size 35 μm, carbon content ≥99%, commercially available.

[0038] Silane coupling agent: gamma-glycidyl ether propyl trimethoxysilane, commercially available;

[0039] Curing agent: hexamethylenetetramine, commercially available;

[0040] The preparation method of the phenolic resin powder and the phenolic resin liquid used in the examples and comparative examples of the application is as follows:

[0041] Preparation of phenolic resin powder:

[0042] According to the weight fraction, 90 parts of phenol and 135 parts of 37% formaldehyde aqueous solution are weighed and put into a reaction kettle with a stirring device and a reflux condenser. 0.8 parts of oxalic acid (acidic catalyst) is added, and after uniform stirring, the temperature is raised to 85-95 DEG C, and the condensation reaction is carried out under insulation. During the reaction, the reaction degree is controlled by sampling detection of viscosity, when the resin viscosity reaches 280 cps (25 DEG C), the heating is stopped;

[0043] The reaction product is then transferred to a spray drying tower and dried at an inlet temperature of 190°C and an outlet temperature of 85°C to obtain fluffy resin particles. The dried particles are fed into an air jet pulverizer and pulverized at a pulverizing pressure of 0.7 MPa, and then sieved through a 180-mesh screen to obtain resin powder with an average particle size of 80 μm. 3 parts of hexamethylenetetramine is added to the resin powder and mixed uniformly to obtain the phenolic resin powder. The free phenol content of the resin powder is less than 0.5%, the moisture content is less than 1.0%, and the softening point is 90°C, which satisfies the requirements for mixing and dispersion with inorganic fibers in a dry process.

[0044] Preparation of the phenolic resin solution:

[0045] According to the proportions, 50 parts of 37% formaldehyde aqueous solution, 1-2 parts of water are added to a reaction kettle, and the pH is adjusted to 9.0 with triethylamine. 22 parts of phenol is added, and the temperature is raised to 65°C for 20 minutes. 8 parts of melamine is added, and the temperature is raised to 80°C by adding triethylamine. The temperature is maintained until the turbidity point appears. 18 parts of urea and the remaining water and triethylamine are added, and the temperature is raised to 85°C until the viscosity reaches 50 cps (25°C). The temperature is lowered to below 35°C to discharge the material, and a phenolic resin solution with a solid content of 50% is obtained, with a viscosity of 400 cps (25°C), a pH of 8.5, and a storage stability of ≥3 months (no stratification at 25°C).

[0046] Example 1:

[0047] (1) Hydrolyze 0.06 parts of silane coupling agent and add to 6 parts of phenolic resin solution to mix uniformly to obtain pretreated phenolic resin solution. Dry mix 19 parts of phenolic resin powder, 60 parts of silicon carbide powder, and 15 parts of graphite powder in a mixer for 8 minutes, then add the pretreated phenolic resin solution and continue mixing for 12 minutes;

[0048] (2) Load the mixture into a mold and cold press at a pressure of 15 MPa;

[0049] (3) Place the green body into a nitrogen protection furnace, raise the temperature to 450°C at a rate of 5°C / min, maintain for 2.5 hours, and cool to room temperature with the furnace to obtain a phenolic resin-based silicon carbide-graphite composite sealing ring.

[0050] Example 2:

[0051] (1) Hydrolyze 0.05 parts of silane coupling agent and add to 5 parts of phenolic resin solution to mix uniformly to obtain pretreated phenolic resin solution. Dry mix 15 parts of phenolic resin powder, 40 parts of silicon carbide powder, and 30 parts of graphite powder in a mixer for 10 minutes, then add the pretreated phenolic resin solution and continue mixing for 15 minutes;

[0052] (2) Load the mixture into a mold and cold press at a pressure of 20 MPa;

[0053] (3) Put the green body into a nitrogen-protected furnace, and heat it to 500°C at a rate of 5°C / min, keep it for 2 hours, and cool it to room temperature with the furnace, to obtain a phenolic resin-based silicon carbide-graphite composite seal ring.

[0054] Example 3:

[0055] (1) Hydrolyze 0.07 parts of silane coupling agent, and add it to 7 parts of phenolic resin liquid to mix evenly, to obtain pretreated phenolic resin liquid; dry mix 23 parts of phenolic resin powder, 50 parts of silicon carbide powder, and 20 parts of graphite powder in a mixer for 5 minutes, and then add the pretreated phenolic resin liquid and continue to mix for 10 minutes;

[0056] (2) Put the mixture into a mold, and cold-press it into shape under a pressure of 10 MPa;

[0057] (3) Put the green body into a nitrogen-protected furnace, and heat it to 400°C at a rate of 5°C / min, keep it for 3 hours, and cool it to room temperature with the furnace, to obtain a phenolic resin-based silicon carbide-graphite composite seal ring.

[0058] The composite seal ring prepared in this example has a typical ternary structure of "skeleton-lubrication-matrix": the silicon carbide particles are jointed with each other to form a continuous rigid skeleton, the graphite layers are uniformly dispersed in the gaps of the skeleton, the carbon matrix formed after carbonization of the phenolic resin fills in the particle interfaces, and a large number of nano- to micro-sized pores are formed. This structure design makes the graphite layers be able to form a lubricating film through directional sliding when the material is subjected to friction, the silicon carbide skeleton provides support against wear, and the pore structure of the carbon matrix realizes the filtering function.

[0059] Comparative Example 1:

[0060] (1) Hydrolyze 0.07 parts of silane coupling agent, and add it to 7 parts of phenolic resin liquid to mix evenly, to obtain pretreated phenolic resin liquid; dry mix 23 parts of phenolic resin powder, 50 parts of silicon carbide powder, and 20 parts of graphite powder in a mixer for 5 minutes, and then add the pretreated phenolic resin liquid and continue to mix for 10 minutes;

[0061] (2) Put the mixture into a mold, and cold-press it into shape under a pressure of 10 MPa;

[0062] (3) Put the green body into a nitrogen-protected furnace, and heat it to 600°C at a rate of 5°C / min, keep it for 3 hours, and cool it to room temperature with the furnace, to obtain a phenolic resin-based silicon carbide-graphite composite seal ring.

[0063] The seal ring prepared in Comparative Example 1 has graphite particles broken into debris, and honeycomb-shaped oxidation pits on the surface, and cannot form a continuous lubricating film.

[0064] Comparative Example 2:

[0065] (1) 30 parts of phenolic resin powder, 50 parts of silicon carbide powder and 20 parts of graphite powder were dry mixed in a mixer for 5 minutes;

[0066] (2) The mixture was loaded into a mold and cold-pressed into shape under a pressure of 10 MPa;

[0067] (3) The green body was placed in a nitrogen protection furnace, heated to 400°C at a rate of 5°C / min, and kept for 3 hours, and then cooled to room temperature with the furnace, to obtain a phenolic resin-based silicon carbide-graphite composite sealing ring.

[0068] Comparative Example 3:

[0069] Phenolic resin powder was 15 parts, phenolic resin liquid was 15 parts, and the rest was the same as in Example 3.

[0070] Comparative Example 4:

[0071] Phenolic resin powder was 5 parts, phenolic resin liquid was 25 parts, and the rest was the same as in Example 3.

[0072] Performance test methods:

[0073] Wear rate: According to GB / T 3960-2016 "Plastics sliding friction and wear test method", a pin-on-disc friction and wear tester was used for testing. The sealing ring sample was processed into a pin with a diameter of 5 mm and a height of 10 mm, and a 45# steel disc with a hardness of HRC 40-45 was selected as the counterpart. The test conditions were set as follows: load 50 N, sliding speed 0.5 m / s, and wear time 60 min. After the test, the mass difference before and after wear of the sample was weighed by an electronic balance with a precision of 0.1 mg, and the wear rate was calculated according to the wear mass, density, load and sliding distance, according to the calculation formula in the standard.

[0074] Friction coefficient: In the above wear rate test process, the tester recorded the friction force synchronously, and the friction coefficient was calculated according to the ratio of friction force to normal pressure, according to the conventional friction coefficient calculation method, and the calculation principle conformed to the basic theory of tribology.

[0075] Porosity: According to GB / T 1936.1-2009 "Fiber-reinforced plastics water absorption test method", Archimedes drainage method was used for testing. First, the mass of the sample in air (m1) was measured, then the sample was completely immersed in distilled water, vacuumed for 30 min under a vacuum degree of ≤0.095 MPa, then the mass of the sample in water (m2) was measured, and finally the wet mass of the sample after wiping (m3) was measured. According to the open porosity calculation formula given in the standard: open porosity = (m3-m1) / (m3-m2) x 100%, the porosity value was obtained.

[0076] Permeability: The liquid permeation test device was independently built and met the relevant theory of fluid permeation test. Deionized water was used as the medium to measure the water volume permeating through the sample per unit time under 0.1 MPa pressure. The permeability was calculated according to Darcy's law, and the formula was: permeability = (flow rate x sample thickness) / (medium viscosity x area x pressure difference), wherein the medium viscosity was the viscosity of water at 20 DEG C (1.002 mPa s).

[0077] Hardness: According to GB / T 4340.1-2009 "Metallic Materials Vickers Hardness Test Part 1: Test Method", the test was carried out using a Vickers hardness tester. The test conditions were: load 100 g, pressure holding time 15 s, 5 points were tested on different positions on the surface of the sample, and the average value of the hardness values of the 5 test points was taken as the final hardness value of the sample. The operation process followed the standard specification.

[0078] Table 1: Components (parts by weight) and test results

[0079]

[0080] From the above results, it can be seen that the composite sealing ring prepared in Examples 1-3 has a high hardness (26-28 GPa) while the wear rate is as low as 1.2 x 10 -7 mm 3 / (N m), the friction coefficient is stable at 0.15-0.18 under dry friction conditions, no additional lubrication is required, the open porosity is 8-12%, the permeability reaches 10 -13 orders of magnitude, and the wear resistance, lubrication and filtration performance are balanced.

[0081] In Comparative Example 1, sintering was carried out at 600 DEG C without a nitrogen atmosphere, graphite was oxidized, and the resin was excessively carbonized. The friction coefficient increased to 0.35, the porosity was 5.2%, the permeability was 2.1 x 10 -15 m 2 , the wear rate was 2.8 x 10 -7 mm 3 / (N m), and the performance was completely deteriorated;

[0082] In Comparative Example 2, only phenolic resin powder was used, the interface between the phenolic resin powder and the silicon carbide and graphite was weak, the wear rate was 3.5 x 10 -7 mm 3 / (N m), the friction coefficient was 0.32, and the structure was loose.

[0083] In Comparative Example 3, the mass ratio of phenolic resin powder to phenolic resin liquid was 1:1, and the infiltration was insufficient. The wear rate was 2.1 x 10 -7 mm 3 / (N m), the porosity was 6.8%, and the performance was not up to standard;

[0084] The mass ratio of phenolic resin powder to phenolic resin liquid in Comparative Example 4 was 1:5. Because the resin liquid was excessive, the skeleton rigidity was insufficient, and the wear rate was 2.5 x 10 -7 mm 3 / (N·m), and the porosity was 14.2%, and the structure was loose.

Claims

1. A phenolic resin-based silicon carbide-graphite composite sealing ring, characterized in that, By weight, it includes the following components: 20-30 parts of phenolic resin, 40-60 parts of silicon carbide powder; 15-30 parts graphite powder; 0.05-0.1 parts of silane coupling agent; The phenolic resin is composed of phenolic resin powder and phenolic resin liquid, wherein the phenolic resin powder and phenolic resin liquid... The mass ratio is 1:2-4.

2. The phenolic resin-based silicon carbide-graphite composite sealing ring according to claim 1, characterized in that, The phenolic resin powder is a thermoplastic phenolic resin with an average particle size of 50-100 μm and a free phenol content of <0.5%; the phenolic resin liquid is a thermosetting phenolic resin with a solid content of 50-70% and a viscosity of 300-1200 mPa·s at 25°C.

3. The phenolic resin-based silicon carbide-graphite composite sealing ring according to claim 1, characterized in that, The silicon carbide powder has a particle size of 100-200 μm and a purity of ≥98%.

4. The phenolic resin-based silicon carbide-graphite composite sealing ring according to claim 1, characterized in that, The graphite powder has a particle size of 10-50 μm and a carbon content of ≥99%.

5. The phenolic resin-based silicon carbide-graphite composite sealing ring according to claim 1, characterized in that, The silane coupling agent is selected from at least one of γ-glycidoxypropyltrimethoxysilane or γ-methacryloxypropyltrimethoxysilane.

6. The phenolic resin-based silicon carbide-graphite composite sealing ring according to claim 1, characterized in that, The phenolic resin-based silicon carbide-graphite composite sealing ring has an open porosity of 8-12% and a permeability of 10. -13 Up to 10 -14 m 2 .

7. The method for preparing the phenolic resin-based silicon carbide-graphite composite sealing ring according to any one of claims 1-6, characterized in that, Includes the following steps: (1) Raw material mixing: Hydrolyze the silane coupling agent and add it to the phenolic resin liquid and mix well to obtain the pretreated phenolic resin liquid; Dry mix the phenolic resin powder with silicon carbide powder and graphite powder for 5-10 minutes, then add the pretreated phenolic resin liquid and continue mixing for 10-15 minutes to obtain a uniform mixture. (2) Cold pressing: The mixture is put into the mold and cold pressed under a pressure of 10-20MPa to obtain the sealing ring blank; (3) Nitrogen sintering: The billet is placed in a nitrogen-protected furnace and heated to 400-500℃ at a heating rate of 3-5℃ / min. It is held for 2-3 hours and then cooled to room temperature with the furnace to obtain a phenolic resin-based silicon carbide-graphite composite sealing ring.

8. The method for preparing the phenolic resin-based silicon carbide-graphite composite sealing ring according to claim 7, characterized in that, In step (3), the nitrogen purity in the nitrogen protection furnace is ≥99.9%, and the furnace pressure is maintained at 0.1-0.5MPa during the sintering process.

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