Method for reinforcing graphite sintering vessel by using carbon-carbon composite material

Abstract

The invention discloses a method for reinforcing a graphite sintering vessel by using a carbon-carbon composite material. The method comprises the following steps: firstly, preparing dipping slurry; when the graphite sintered vessel is subjected to enhancement treatment, firstly, a graphite sintered vessel green body is subjected to surface roughening treatment, then the treated green body is subjected to inner-layer impregnation operation and outer-layer impregnation operation in sequence twice by utilizing a vacuum pressurization impregnation process to obtain a secondary green body, and the secondary green body is subjected to sintering and graphitization treatment to obtain the graphite sintered vessel. And converting the organic binder into amorphous carbon and graphite to form a carbon-carbon composite structure so as to obtain a graphitized product of a secondary green body, and performing fettling and finish machining treatment on the graphitized product of the secondary green body so as to obtain the finished graphite sintered vessel. The carbon-carbon composite structure with the gradient function is formed in the internal pores and the surface of the graphite vessel, so that the bonding force between graphite layers is enhanced, the overall bending strength and toughness are improved, and the graphite sintering vessel is not prone to fracture or deformation when bearing external force.

Description

Technical Field

[0001] This invention relates to graphite sintering vessels in carbon materials technology, specifically a method for reinforcing graphite sintering vessels using carbon-carbon composite materials. Background Technology

[0002] Graphite sintering vessels, as core components of high-temperature thermal equipment, are widely used in high-end manufacturing fields such as semiconductor silicon crystal growth, photovoltaic polycrystalline silicon preparation, aerospace material sintering, and the synthesis of cathode materials for new energy batteries. Their core advantages lie in their excellent high-temperature resistance, superior thermal and electrical conductivity, strong chemical stability, and ease of processing and shaping, making them indispensable key materials in current high-temperature sintering processes. For example, in the semiconductor industry, graphite crucibles are used to support molten silicon during the single-crystal silicon pulling process, and their performance directly affects the purity and integrity of crystal growth; in the photovoltaic field, graphite hot zone components are core components of polycrystalline silicon ingot furnaces, determining the quality and energy efficiency of the ingot.

[0003] Despite the numerous advantages of sintered graphite vessels, the inherent properties of traditional graphite materials significantly limit their practical applications. Graphite's layered crystalline structure and weak interlayer bonding result in low flexural strength and poor toughness. During high-temperature sintering, frequent temperature fluctuations can easily lead to thermal stress concentration, causing cracking and deformation, severely impacting service life. Furthermore, graphite begins to oxidize in oxygen-rich environments above 400°C, generating CO / CO2 gases, leading to weight loss, dimensional changes, and performance degradation. Even in a protective atmosphere, trace amounts of oxygen can cause slow oxidation on the vessel surface, shortening its lifespan. These factors directly affect the mechanical strength, stability, and service life of sintered graphite vessels, making them prone to wear and flaking on the surface during long-term use, eventually leading to cracks. Mechanical impacts during loading / unloading can further amplify surface defects, ultimately causing overall failure.

[0004] To address the aforementioned defects in graphite sintering vessels, various enhancement methods have been attempted in the prior art, but all have significant shortcomings: The carbon fiber stub reinforcement method involves mixing chopped carbon fibers with graphite powder, pressing, and then sintering. This method can improve the strength to some extent, but the short fibers are randomly distributed and have weak interlayer bonding, resulting in limited reinforcement effect. Furthermore, fiber agglomeration is prone to occur, leading to uneven material properties.

[0005] The resin / asphalt impregnation method fills the pores of graphite to increase density by impregnating it with resin or asphalt and then carbonizing it a second time. However, after the resin is carbonized, it is easy to form a brittle carbon matrix and cannot form internal structural cross-links. As a result, the thermal shock resistance of the structured vessel is not effectively improved, and volatiles are easily generated at high temperatures, affecting the purity of the product.

[0006] Surface coating methods can delay oxidation by coating the graphite surface with anti-oxidation coatings such as SiC and ZrC. However, the coefficients of thermal expansion of the coating and the substrate do not match, and the coating is prone to peeling off after high-temperature cycling, which cannot fundamentally solve the problem of internal brittleness.

[0007] Carbon-carbon (C / C) composites are a novel type of composite material with carbon fiber and its fabrics as reinforcement and carbon as the matrix. They possess characteristics such as low density, high strength, high modulus, excellent thermal shock resistance, and resistance to high-temperature oxidation, allowing for long-term use in an aerobic environment at 1800℃. These properties perfectly compensate for the shortcomings of traditional graphite, making them an ideal reinforcing material. However, currently, there is no mature industrial method for the sintering of graphite vessels reinforced with C / C composites, resulting in high costs and difficulties in achieving large-scale production. Summary of the Invention

[0008] The technical problem solved by the present invention is to provide a method for reinforcing graphite sintering vessels with carbon-carbon composite materials, so as to overcome the shortcomings in the above-mentioned background art.

[0009] The technical problem solved by this invention is achieved by the following technical solution: A method for reinforcing graphite sintering vessels using carbon-carbon composite materials, used to structurally enhance and optimize newly formed graphite sintering vessels, includes the following steps: S1 Impregnation Slurry Formulation: The impregnation slurry includes a first impregnation slurry for molding the inner reinforcing layer and a second impregnation slurry for molding the outer protective layer; The first impregnation slurry comprises the following raw material components in parts by weight: 65-75 parts graphite powder, 28-31 parts carbon fiber powder, 38-43 parts phenolic resin, and 3-5 parts silicon carbide powder II; the second impregnation slurry comprises the following raw material components in parts by weight: 75-85 parts graphite powder, 18-22 parts silicon carbide powder I, 44-48 parts phenolic resin, 7-8 parts zirconium boride powder, and 3-5 parts silicon carbide powder II; wherein the silicon carbide powder I has a particle size of micron-sized silicon carbide powder, and the silicon carbide powder II has a particle size of nano-sized silicon carbide powder. S2 Preparation of impregnation slurry: Graphite powder, carbon fiber powder and silicon carbide powder I are dried in a drying oven to remove moisture and volatile impurities while preheating the powder surface. The preheated graphite powder and carbon fiber powder are grouped together, and the preheated graphite powder and silicon carbide powder I are grouped together. They are poured into a high-speed mixer according to the proportions of the first impregnation slurry and the second impregnation slurry, respectively. S3 starts the high-speed mixer for a first dry mixing. After the first dry mixing is completed, silicon carbide powder II is added to the high-speed mixer of the first impregnation slurry in proportion, and zirconium boride powder and silicon carbide powder II are added to the high-speed mixer of the second impregnation slurry in proportion, and the second dry mixing is continued. S4. The phenolic resins corresponding to the first impregnation slurry and the second impregnation slurry are added to different heating kettles, heated to 80~90℃, and stirred until they have good fluidity. The heated binder is slowly added to the corresponding high-speed mixer, and the temperature of the mixing chamber of the high-speed mixer is controlled at 60~70℃ until a uniform and lump-free paste slurry is formed. S5 roughens the surface of the green body of the graphite sintering vessel to be treated until the surface roughness Ra is between 3.2 and 6.3 μm; S6 will use a vacuum pressure impregnation process to perform the inner layer impregnation and outer layer impregnation operations on the green body processed in step S5 in two separate steps: During the inner layer impregnation process, first apply a vacuum to -0.095~-0.075MPa and maintain it for 10~15min, then pressurize to 0.1~0.3MPa and impregnate for 12~18h. After the inner layer impregnation process is completed, place it in an inert atmosphere drying oven for drying and curing to obtain a primary green body. When performing outer layer impregnation on the primary green body after drying and curing, first apply a vacuum to -0.095~-0.075MPa and maintain it for 10~15min, then pressurize to 0.3~0.5MPa and impregnate for 32~45h; after the outer layer impregnation is completed, send it to an inert atmosphere drying oven for drying and curing to obtain a secondary green body. S7 performs sintering and graphitization on the secondary green body, converting the organic binder into amorphous carbon and graphite to form a carbon-carbon composite structure, thus obtaining the graphitized product of the secondary green body. The graphitized product of the secondary green body is then trimmed and finished to obtain the finished graphite sintered vessel.

[0010] As a further limitation, in step S1, the particle size of graphite powder and silicon carbide powder I used as raw materials is 200-300 mesh; the particle size of zirconium boride powder and silicon carbide powder II is 800-1200 mesh; and the length of carbon fiber powder is 50-70 μm.

[0011] As a further limitation, in step S2, when the graphite powder, carbon fiber powder, and silicon carbide powder I are dried in a drying oven, it is preferable to dry them at a temperature of 110~120°C for 60~90 minutes.

[0012] As a further limitation, when dry mixing is performed in step S2, the speed of the high-speed mixer is set to 300~500 rpm, the duration of the first dry mixing is controlled to be 20~30 min, and the duration of the second dry mixing is 10~15 min; when wet mixing is performed in step S4, the speed of the high-speed mixer is set to 300~500 rpm, and the wet mixing time is controlled to be 25~35 min.

[0013] As a further limitation, when roughening the surface of the green body of the graphite sintering vessel to be treated, it is preferable to use sandblasting. During the treatment, 80-100 mesh diamond abrasive is used for surface sandblasting, the sandblasting pressure is controlled at 0.4-0.6 MPa, the nozzle distance is 15-20 cm, and the treatment is carried out on one side for 2-3 minutes. After treatment, the residual abrasive on the surface is blown away with compressed air, then cleaned with anhydrous ethanol, and dried for later use.

[0014] As a further limitation, in step S6, when drying and curing the green body after the inner layer impregnation operation is completed, the drying temperature in the drying oven is controlled at 100~150℃ and the drying time is 9~12h; when drying and curing the green body sent into the inert atmosphere after the outer layer impregnation operation is completed, the drying temperature in the drying oven is controlled at 120~150℃ and the drying time is 12~15h.

[0015] As a further limitation, in step S7, the secondary green blank is sintered in a pusher-type inert atmosphere sintering furnace. In an inert gas environment, the sintering furnace is heated to 1200-1400°C at a heating rate of 5-8°C / min, held for 2-3 hours, and then cooled to room temperature with the furnace. After holding for 5-6 hours, it is taken out.

[0016] As a further limitation, in step S7, the graphitization treatment of the secondary green billet is carried out in an Atchison graphitization furnace, in an inert gas environment, heated to 2800~3000℃ at a heating rate of 10~15℃ / min, held at that temperature for 45~60min, and then cooled to room temperature with the furnace.

[0017] Beneficial Effects: This invention relates to a method for reinforcing graphite sintered vessels using carbon-carbon composite materials. Through a "double-layer impregnation carbon-carbon composite reinforcement" technique, a gradient functional carbon-carbon composite structure is formed within the pores and on the surface of the graphite vessel. The inner layer is impregnated with a carbon-based slurry containing carbon fibers, utilizing the high tensile strength (≥3000MPa) of the carbon fibers to enhance the interlayer bonding force of the graphite, thereby improving the overall flexural strength and toughness. The outer layer is impregnated with a carbon-based slurry containing a high proportion of antioxidants, forming a dense antioxidant layer on the surface to inhibit oxygen diffusion and oxidation reactions. Simultaneously, the impregnated slurry, after sintering and graphitization, transforms into a carbon-carbon composite material, forming chemical bonds with the graphite matrix to ensure the long-lasting reinforcement effect, effectively improving the stability and durability of the graphite sintered vessel. Detailed Implementation

[0018] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific embodiments.

[0019] In the following embodiments, those skilled in the art will understand that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have a meaning consistent with their meaning in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein.

[0020] The steps for preparing graphite sintering vessels using carbon-carbon composite materials to reinforce them are as follows: Example 1 is used to prepare a reinforced graphite crucible: First, the impregnation slurry formulations were prepared. The first impregnation slurry consisted of 65 parts graphite powder, 28 parts carbon fiber powder, 38 parts phenolic resin, and 3 parts silicon carbide powder II. The second impregnation slurry consisted of 75 parts graphite powder, 18 parts silicon carbide powder I, 44 parts phenolic resin, 7 parts zirconium boride powder, and 3 parts silicon carbide powder II. The silicon carbide powder I had a particle size in the micrometer range, while the silicon carbide powder II had a particle size in the nanometer range. The particle size of the graphite powder and silicon carbide powder I was 200 mesh, the particle size of the zirconium boride powder and silicon carbide powder II was 800 mesh, and the length of the carbon fiber powder was 50 μm.

[0021] Next, impregnation slurries were prepared. Graphite powder, carbon fiber powder, and silicon carbide powder I were dried in a drying oven at 110°C for 60 minutes to remove moisture and volatile impurities while preheating the powder surface. The preheated graphite powder and carbon fiber powder were grouped together, and the preheated graphite powder and silicon carbide powder I were grouped together. These were then poured into a high-speed mixer according to the proportions of the first and second impregnation slurries, respectively. The high-speed mixer was set to 300 rpm and a first dry-mixing was performed for 20 minutes. After the first dry-mixing, silicon carbide powder II was added to the high-speed mixer of the first impregnation slurry in proportion, and zirconium boride powder and silicon carbide powder II were added to the high-speed mixer of the second impregnation slurry in proportion, for a second dry-mixing of 10 minutes. The corresponding phenolic resins for the first and second impregnation slurries were then added to separate heating kettles, heated to 80°C, and stirred until good fluidity was achieved. Slowly add the heated binder into the corresponding high-speed mixer, control the temperature of the mixing chamber of the high-speed mixer at 60℃, set the speed of the high-speed mixer to 300 rpm, and control the wet mixing time to 25 minutes, until a uniform, lump-free paste is formed.

[0022] Then, the surface of the green graphite crucible to be treated was roughened by sandblasting. 80-mesh diamond abrasive was used for surface sandblasting, with the sandblasting pressure controlled at 0.4 MPa and the nozzle distance at 15 cm. One side was treated for 2 minutes. After treatment, the residual abrasive on the surface was blown away with compressed air, and then cleaned with anhydrous ethanol and dried for later use. The surface roughness Ra was 3.2 μm.

[0023] The green body treated above is then subjected to a vacuum pressure impregnation process, with two separate inner and outer layer impregnation operations. For the inner layer impregnation, a vacuum is first applied to -0.095 MPa and maintained for 10 minutes, then pressure is increased to 0.1 MPa, and the impregnation process lasts for 12 hours. After the inner layer impregnation, the green body is placed in an inert atmosphere drying oven for drying and curing, with the drying temperature controlled at 100°C and the drying time at 9 hours, resulting in the primary green body. For the outer layer impregnation, the primary green body is first applied to a vacuum of -0.095 MPa and maintained for 10 minutes, then pressure is increased to 0.3 MPa, and the impregnation process lasts for 32 hours. After the outer layer impregnation, the green body is placed in an inert atmosphere drying oven for drying and curing, with the drying temperature controlled at 120°C and the drying time at 12 hours, resulting in the secondary green body.

[0024] Finally, the secondary green blanks undergo sintering and graphitization. Sintering is performed in a pusher-type inert atmosphere sintering furnace. In an inert gas environment, the furnace is heated to 1200℃ at a heating rate of 5℃ / min and held for 2 hours. Then, the furnace is cooled to room temperature and held for 5 hours before being removed. Graphitization is performed in an Atchison graphitization furnace. In an inert gas environment, the furnace is heated to 2800℃ at a heating rate of 10℃ / min and held for 45 minutes. Then, the furnace is cooled to room temperature, forming a carbon-carbon composite structure, thus obtaining the graphitized secondary green blank. The graphitized secondary green blank is then trimmed and finished to obtain the finished reinforced graphite crucible.

[0025] The performance indicators of the reinforced graphite crucible prepared by the method in Example 1 are compared with those of the conventional graphite crucible as follows: Performance indicators Traditional graphite crucible Example 1 Increase Flexural strength (MPa) 22±2 36±3 63.6% <![CDATA[Fracture toughness (MPa·m 1 / 2 )]]> 0.8±0.1 1.5±0.2 87.5% Antioxidant weight loss rate (800℃, 10h) 16.2±1.5% 4.2±0.8% Reduced by 74.1% Service life (monocrystalline silicon pulling furnace) 30±5 times 85±10 times Extended by 183.3% Example 2: Used to prepare reinforced graphite saggers: First, the impregnation slurry formulations were prepared. The first impregnation slurry consisted of 75 parts graphite powder, 31 parts carbon fiber powder, 43 parts phenolic resin, and 5 parts silicon carbide powder II. The second impregnation slurry consisted of 85 parts graphite powder, 22 parts silicon carbide powder I, 48 parts phenolic resin, 8 parts zirconium boride powder, and 5 parts silicon carbide powder II. The silicon carbide powder I had a particle size in the micrometer range, while the silicon carbide powder II had a particle size in the nanometer range. The particle size of the graphite powder and silicon carbide powder I was 300 mesh, the particle size of the zirconium boride powder and silicon carbide powder II was 1200 mesh, and the length of the carbon fiber powder was 70 μm.

[0026] Next, impregnation slurries were prepared. Graphite powder, carbon fiber powder, and silicon carbide powder I were dried in a drying oven at 120°C for 90 minutes to remove moisture and volatile impurities while preheating the powder surface. The preheated graphite powder and carbon fiber powder were grouped together, and the preheated graphite powder and silicon carbide powder I were grouped together. These were then poured into a high-speed mixer according to the proportions of the first and second impregnation slurries, respectively. The high-speed mixer was set to 500 rpm and a first dry-mixing was performed for 30 minutes. After the first dry-mixing, silicon carbide powder II was added to the high-speed mixer of the first impregnation slurry in proportion, and zirconium boride powder and silicon carbide powder II were added to the high-speed mixer of the second impregnation slurry in proportion, for a second dry-mixing of 15 minutes. The corresponding phenolic resins for the first and second impregnation slurries were then added to separate heating kettles, heated to 90°C, and stirred until good fluidity was achieved. Slowly add the heated binder into the corresponding high-speed mixer, control the temperature of the mixing chamber of the high-speed mixer at 70℃, set the speed of the high-speed mixer to 500 rpm, and control the wet mixing time to 35 minutes, until a uniform, lump-free paste is formed.

[0027] The surface of the green graphite sagger to be treated is then roughened by sandblasting. 100-mesh diamond abrasive is used for surface sandblasting, with the sandblasting pressure controlled at 0.6 MPa and the nozzle distance at 20 cm. The treatment is carried out on one side for 3 min. After treatment, the residual abrasive on the surface is blown away with compressed air, and then it is cleaned with anhydrous ethanol and dried for later use. The surface roughness Ra is 6.3 μm.

[0028] The green body treated above is then subjected to a vacuum pressure impregnation process, with two separate inner and outer layer impregnation operations. For the inner layer impregnation, a vacuum is first applied to -0.075 MPa and maintained for 15 minutes, then pressurized to 0.3 MPa, and impregnated for 18 hours. After the inner layer impregnation, it is placed in an inert atmosphere drying oven for drying and curing, with the drying temperature controlled at 150°C and the drying time at 12 hours, yielding the first green body. For the outer layer impregnation, after drying and curing, a vacuum is first applied to -0.075 MPa and maintained for 15 minutes, then pressurized to 0.5 MPa, and impregnated for 45 hours. After the outer layer impregnation, it is placed in an inert atmosphere drying oven for drying and curing, with the drying temperature controlled at 150°C and the drying time at 15 hours, yielding the second green body.

[0029] Finally, the secondary green blanks undergo sintering and graphitization. Sintering is performed in a pusher-type inert atmosphere sintering furnace. In an inert gas environment, the furnace is heated to 1400℃ at a rate of 8℃ / min and held for 3 hours. Then, the furnace is cooled to room temperature and held for 6 hours before being removed. Graphitization is performed in an Atchison graphitization furnace. In an inert gas environment, the furnace is heated to 3000℃ at a rate of 15℃ / min and held for 60 minutes. Then, the furnace is cooled to room temperature, forming a carbon-carbon composite structure, thus obtaining the graphitized secondary green blank. The graphitized secondary green blank is then trimmed and finished to obtain the finished graphite sagger.

[0030] The performance indicators of the reinforced graphite sagger prepared by the method of Example 2 are compared with those of the traditional graphite sagger as follows: Performance indicators Traditional graphite saggars Example 2 Increase Flexural strength (MPa) 20±2 34±3 70% <![CDATA[Fracture toughness (MPa·m 1 / 2 ).]]> 0.7±0.1 1.4±0.2 100% Antioxidant weight loss rate (800℃, 10h) 15.5±1.3% 3.8±0.7% Reduced by 75.5% Service life (monocrystalline silicon pulling furnace) 25±4 times 80±9 times Extended by 220% The comparison of the above performance indicators shows that the reinforced graphite crucible prepared by the method of Example 1 and the graphite sagger prepared by the method of Example 2 have significantly improved in terms of bending strength, fracture toughness, oxidation weight loss rate, and service life. Specifically, The flexural strength of the enhanced graphite crucible prepared in Example 1 increased from 22±2 MPa of the traditional graphite crucible to 36±3 MPa, an increase of 63.6%. This indicates that it can withstand greater external forces without fracture and exhibits better stability when subjected to heavy loads or impacts. The fracture toughness increased from 0.8±0.1 MPa·m. 1 / 2 Increased to 1.5±0.2MPa·m 1 / 2The improvement of performance by 87.5% means that when cracks appear, the reinforced graphite crucible can better prevent crack propagation, thus extending its service life. The oxidation weight loss rate decreased from 16.2±1.5% to 4.2±0.8% at 800℃ for 10 hours, a reduction of 74.1%, indicating a significant enhancement in its oxidation resistance at high temperatures, reducing quality loss caused by oxidation. The service life in a single-crystal silicon pulling furnace increased from 30±5 cycles to 85±10 cycles, an extension of 183.3%, greatly reducing replacement frequency and lowering operating costs.

[0031] The flexural strength of the reinforced graphite sagger prepared in Example 2 was increased from 20±2 MPa of the traditional graphite sagger to 34±3 MPa, an increase of 70%, thus enhancing its structural stability when bearing loads. The fracture toughness increased from 0.7±0.1 MPa·m. 1 / 2 Increased to 1.4 ± 0.2 MPa·m 1 / 2 The improvement is 100%, offering a greater advantage in dealing with potential cracks. The oxidation weight loss rate decreased from 15.5±1.3% to 3.8±0.7% after 10 hours at 800℃, a reduction of 75.5%, demonstrating a significant improvement in oxidation resistance. The service life in a single-crystal silicon pulling furnace increased from 25±4 cycles to 80±9 cycles, an extension of 220%, effectively enhancing its durability in high-temperature operating environments.

[0032] In summary, the method of using carbon-carbon composite materials to reinforce graphite sintering vessels, whether for preparing reinforced graphite crucibles or reinforced graphite saggers, can significantly improve the various performance indicators of the products, and has broad application prospects and important practical value in industrial production.

[0033] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for reinforcing graphite sintered vessels using carbon-carbon composite materials, used to strengthen and optimize the structure of newly formed graphite sintered vessels, characterized in that... The following steps are included: S1 Impregnation Slurry Formulation: The impregnation slurry includes a first impregnation slurry for molding the inner reinforcing layer and a second impregnation slurry for molding the outer protective layer; The first impregnation slurry comprises the following raw material components in parts by weight: 65-75 parts graphite powder, 28-31 parts carbon fiber powder, 38-43 parts phenolic resin, and 3-5 parts silicon carbide powder II; the second impregnation slurry comprises the following raw material components in parts by weight: 75-85 parts graphite powder, 18-22 parts silicon carbide powder I, 44-48 parts phenolic resin, 7-8 parts zirconium boride powder, and 3-5 parts silicon carbide powder II; wherein the silicon carbide powder I has a particle size of micron-sized silicon carbide powder, and the silicon carbide powder II has a particle size of nano-sized silicon carbide powder. S2 Preparation of impregnation slurry: Graphite powder, carbon fiber powder and silicon carbide powder I are dried in a drying oven to remove moisture and volatile impurities while preheating the powder surface. The preheated graphite powder and carbon fiber powder are grouped together, and the preheated graphite powder and silicon carbide powder I are grouped together. They are poured into a high-speed mixer according to the proportions of the first impregnation slurry and the second impregnation slurry, respectively. S3 starts the high-speed mixer for a first dry mixing. After the first dry mixing is completed, silicon carbide powder II is added to the high-speed mixer of the first impregnation slurry in proportion, and zirconium boride powder and silicon carbide powder II are added to the high-speed mixer of the second impregnation slurry in proportion, and the second dry mixing is continued. S4. The phenolic resins corresponding to the first impregnation slurry and the second impregnation slurry are added to different heating kettles, heated to 80~90℃, and stirred until they have good fluidity. The heated binder is slowly added to the corresponding high-speed mixer, and the temperature of the mixing chamber of the high-speed mixer is controlled at 60~70℃ until a uniform and lump-free paste slurry is formed. S5 roughens the surface of the green body of the graphite sintering vessel to be treated until the surface roughness Ra is between 3.2 and 6.3 μm; S6 will use a vacuum pressure impregnation process to perform the inner layer impregnation and outer layer impregnation operations on the green body processed in step S5 in two separate steps: During the inner layer impregnation process, first apply a vacuum to -0.095~-0.075MPa and maintain it for 10~15min, then pressurize to 0.1~0.3MPa and impregnate for 12~18h. After the inner layer impregnation process is completed, place it in an inert atmosphere drying oven for drying and curing to obtain a primary green body. When performing outer layer impregnation on the primary green body after drying and curing, first apply a vacuum to -0.095~-0.075MPa and maintain it for 10~15min, then pressurize to 0.3~0.5MPa and impregnate for 32~45h; after the outer layer impregnation is completed, send it to an inert atmosphere drying oven for drying and curing to obtain a secondary green body. S7 performs sintering and graphitization on the secondary green body, converting the organic binder into amorphous carbon and graphite to form a carbon-carbon composite structure, thus obtaining the graphitized product of the secondary green body. The graphitized product of the secondary green body is then trimmed and finished to obtain the finished graphite sintered vessel.

2. The method for reinforcing graphite sintering vessels with carbon-carbon composite materials according to claim 1, characterized in that, In step S1, the graphite powder and silicon carbide powder I used as raw materials have a particle size of 200-300 mesh; the zirconium boride powder and silicon carbide powder II have a particle size of 800-1200 mesh; and the carbon fiber powder has a length of 50-70 μm.

3. The method for reinforcing graphite sintering vessels with carbon-carbon composite materials according to claim 1, characterized in that, In step S2, when the graphite powder, carbon fiber powder, and silicon carbide powder I are dried in a drying oven, the drying process is carried out at a temperature of 110~120℃ for 60~90 minutes.

4. The method for reinforcing graphite sintering vessels with carbon-carbon composite materials according to claim 1, characterized in that, When dry mixing is performed in step S2, the high-speed mixer is set to a speed of 300-500 rpm, and the duration of the first dry mixing is controlled to be 20-30 min, and the duration of the second dry mixing is 10-15 min. When wet mixing is performed in step S4, the high-speed mixer is set to a speed of 300-500 rpm, and the wet mixing time is controlled to be 25-35 min.

5. The method for reinforcing graphite sintering vessels with carbon-carbon composite materials according to claim 1, characterized in that, When roughening the surface of the green body of the graphite sintering vessel to be treated, the surface treatment is carried out by sandblasting. During the treatment, diamond abrasive with a particle size of 80~100 mesh is used for surface sandblasting. The sandblasting pressure is controlled at 0.4~0.6MPa, the nozzle distance is 15~20cm, and the treatment is carried out on one side for 2~3min. After treatment, the residual abrasive on the surface is blown away with compressed air, and then cleaned with anhydrous ethanol and dried for later use.

6. The method for reinforcing graphite sintering vessels with carbon-carbon composite materials according to claim 1, characterized in that, In step S6, when drying and curing the green body after the inner impregnation operation is completed, the drying temperature in the drying oven is controlled at 100~150℃ and the drying time is 9~12h; when drying and curing the green body sent into the inert atmosphere after the outer impregnation operation is completed, the drying temperature in the drying oven is controlled at 120~150℃ and the drying time is 12~15h.

7. The method for reinforcing graphite sintering vessels with carbon-carbon composite materials according to claim 1, characterized in that, In step S7, the secondary green blank is sintered in a pusher-type inert atmosphere sintering furnace. In an inert gas environment, the sintering furnace is heated to 1200-1400°C at a heating rate of 5-8°C / min, held for 2-3 hours, and then cooled to room temperature with the furnace. After holding for 5-6 hours, it is taken out.

8. The method for reinforcing graphite sintering vessels with carbon-carbon composite materials according to claim 1, characterized in that, In step S7, the graphitization of the secondary green billet is carried out in an Atchison graphitization furnace in an inert gas environment, heated to 2800-3000°C at a heating rate of 10-15°C / min, held for 45-60 min, and then cooled to room temperature with the furnace.