Isostatic pressing graphite impregnation method capable of achieving uniform impregnation

Abstract

The invention discloses a uniformly-impregnated isostatic pressing graphite impregnation method, which comprises the following steps: pretreatment, vacuum impregnation, pressurized impregnation, curing treatment and post-treatment to finally obtain uniformly-impregnated isostatic pressing graphite. The impregnation uniformity of isostatic pressing graphite is effectively improved through vacuum pressurization impregnation, the erosion resistance and breaking strength of a graphite product can be improved after the graphite product is subjected to a subsequent curing process, and then the situation that local shrinkage of the isostatic pressing graphite is uneven due to rapid curing is avoided by adopting a staged heating curing process in a matched mode, so that the service life of the isostatic pressing graphite is prolonged. The risk of cracking or warping is effectively reduced; moreover, the resin can form an initial network structure through heat preservation and curing in the first stage, a more uniform substrate is provided for subsequent high-temperature curing, bubbles formed by violent escape of volatile components due to direct high temperature are reduced, the crosslinking density of the phenolic resin can be further improved through heat preservation and curing in the second stage, and complete curing of the resin is ensured; the breaking strength of a final product can be improved.

Description

Technical Field

[0001] The invention relates to the field of isostatic graphite technology, in particular to a method for impregnating isostatic graphite with uniform impregnation. Background Art

[0002] Isostatic graphite, a type of specialty graphite, boasts advantages such as high density, high purity, high hardness, chemical structure temperature, high temperature resistance, and excellent electrical and thermal conductivity. It is used not only in civilian applications such as continuous casting nozzles for metal casting, photovoltaic single crystal silicon growth furnaces, graphite electrodes for electrospark machining (EDM), and hot-bending glass, but also in the military sector as neutron moderators for nuclear reactors and rocket nozzles. Furthermore, with the rapid development of photovoltaics and EDM in China in recent years, the demand for isostatic graphite in China has been increasing year by year. However, due to the lack of international access to isostatic graphite technology and the long R&D cycle, the production quantity and quality of domestic isostatic graphite products have not been effectively improved.

[0003] Isostatic graphite has excellent physical and chemical properties, such as nearly flawless high purity, outstanding high strength, excellent high electrical conductivity and extremely low thermal expansion coefficient. However, when faced with special working conditions such as high-temperature operating environments and highly corrosive media, the performance of original isostatic graphite still has certain limitations, especially in terms of oxidation resistance and corrosion resistance, which need to be improved urgently. Impregnation treatment is a key technical link in improving the performance of isostatic graphite and is crucial to enhancing its environmental adaptability. However, traditional impregnation methods are difficult to meet the stringent requirements of high-end industries for high performance and high stability of isostatic graphite due to problems such as uneven impregnation, difficulty in penetrating the interior of the graphite, and possible damage to the internal structure of the graphite. Therefore, it is necessary to propose a new solution to solve the above problems. Summary of the Invention

[0004] In view of this, the present invention addresses the deficiencies in the prior art, and its main purpose is to provide an isostatic graphite impregnation method with uniform impregnation, which can effectively solve the problems of uneven impregnation in traditional impregnation methods, difficulty in penetrating the graphite interior, and possible damage to the internal structure of the graphite.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for impregnating isostatically pressed graphite with uniform impregnation comprises the following steps:

[0007] (1) Pretreatment

[0008] Select isostatically pressed graphite products of appropriate specifications, clean their surfaces to remove oil stains and impurities, and dry the cleaned isostatically pressed graphite products in a vacuum drying oven at a drying temperature of 80-120°C for 2-4 hours to obtain pretreated graphite products;

[0009] (2) Vacuum impregnation

[0010] The pretreated graphite product obtained in step (1) is placed in an impregnation container, which is sealed and connected to a vacuum system. The impregnation container is first evacuated to reduce the internal pressure to 10-100 Pa, and the vacuum state is maintained for 15-30 minutes to fully expose the internal pores of the graphite. Subsequently, the impregnation liquid is slowly injected until the impregnation liquid submerges the pretreated graphite product, and the product is impregnated in a vacuum environment for 1-3 hours. The vacuum negative pressure is used to promote the impregnant to penetrate deeply into the pores of the graphite to obtain a vacuum-impregnated graphite product;

[0011] (3) Pressure impregnation

[0012] After the vacuum impregnation is completed, the vacuum system is turned off and inert gas is slowly introduced into the impregnation container to pressurize it, so that the pressure gradually increases to 5-20 MPa and the pressure is maintained for 2-6 hours. The external pressure further pushes the impregnant to fill the deep pores of the graphite to ensure uniform and sufficient impregnation, and obtains the graphite product after pressure impregnation;

[0013] (4) Curing treatment

[0014] The pressurized impregnated graphite product obtained in step (3) is placed in a curing furnace, first heated to 150-200°C at a heating rate of 3°C / min, and kept warm for 3 hours to achieve preliminary curing; then heated to 200-300°C at a heating rate of 3°C / min, and kept warm for 3 hours to achieve deep curing, and then cooled to room temperature with the furnace to complete the curing of the impregnation liquid in the graphite pores, enhance the performance of the graphite product, and obtain a cured graphite product.

[0015] As a preferred solution, in step (1), the surface of the isostatically pressed graphite product is cleaned by ultrasonic cleaning and chemical wiping.

[0016] As a preferred solution, in step (2), the solvent of the impregnation solution is an organic solvent, the solute of the impregnation solution includes any one of phenolic resin, furan resin, and metal organic compound, and the mass fraction of the solute of the impregnation solution is 30-60%.

[0017] As a preferred embodiment, in step (2), the solvent of the impregnation solution is ethanol or toluene.

[0018] As a preferred solution, in step (2), the solute of the impregnation solution further includes at least one of an antioxidant and a curing accelerator.

[0019] As a preferred embodiment, in step (3), the inert gas is nitrogen.

[0020] As a preferred solution, step (5) is also included. The process of step (5) is as follows:

[0021] (5) Post-processing

[0022] The surface of the solidified graphite product obtained in step (4) is cleaned to remove excess impregnation liquid residue to obtain a post-treated graphite product.

[0023] As a preferred solution, in step (5), the surface of the solidified graphite product is cleaned by grinding or chemical cleaning.

[0024] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, it can be seen from the above technical solution that:

[0025] Vacuum pressure impregnation effectively improves the impregnation uniformity of isostatic graphite, so that after the subsequent curing process, the corrosion resistance and flexural strength of the graphite products can be improved. Combined with the use of a staged temperature increase curing process, it avoids local shrinkage of the isostatic graphite due to rapid curing, effectively reducing the risk of cracks or warping; and the first stage of heat preservation curing can make the resin form a preliminary network structure, providing a more uniform base for subsequent high-temperature curing, reducing the violent escape of volatiles caused by direct high temperature to form bubbles. The second stage of heat preservation curing can further promote the cross-linking density of the phenolic resin, ensure that the resin is fully cured, and improve the flexural strength of the final product.

[0026] In order to more clearly illustrate the structural features and effects of the present invention, the present invention is described in detail below with reference to specific embodiments. DETAILED DESCRIPTION

[0027] The present invention discloses a method for impregnating isostatically pressed graphite uniformly, comprising the following steps:

[0028] (1) Pretreatment

[0029] Select isostatically pressed graphite products of appropriate specifications, clean the surface of the isostatically pressed graphite products by ultrasonic cleaning and chemical reagent wiping to remove oil stains and impurities, and place the cleaned isostatically pressed graphite products in a vacuum drying oven for drying at a temperature of 80-120°C for 2-4 hours to obtain pretreated graphite products.

[0030] (2) Vacuum impregnation

[0031] The pretreated graphite product obtained in step (1) is placed in an impregnation container, sealed and connected to a vacuum system, the impregnation container is first evacuated to reduce the internal pressure to 10-100 Pa, and the vacuum state is maintained for 15-30 minutes to fully expose the internal pores of the graphite. Subsequently, the impregnation liquid is slowly injected until the impregnation liquid submerges the pretreated graphite product, and the product is impregnated in a vacuum environment for 1-3 hours, and the vacuum negative pressure is used to promote the impregnant to penetrate deeply into the pores of the graphite to obtain a vacuum-impregnated graphite product; wherein the solvent of the impregnation liquid is an organic solvent, and the solvent of the impregnation liquid is ethanol or toluene; the solute of the impregnation liquid includes any one of phenolic resin, furan resin, and metal organic compound, and the solute mass fraction of the impregnation liquid is 30-60%, and the solute of the impregnation liquid also includes at least one of an antioxidant and a curing accelerator.

[0032] (3) Pressure impregnation

[0033] After the vacuum impregnation is completed, the vacuum system is turned off and nitrogen is slowly introduced into the impregnation container to pressurize it, so that the pressure gradually increases to 5-20MPa and the pressure is maintained for 2-6 hours. The external pressure further pushes the impregnant to fill the deep pores of the graphite to ensure uniform and sufficient impregnation, and obtains the graphite product after pressure impregnation.

[0034] (4) Curing treatment

[0035] The pressurized impregnated graphite product obtained in step (3) is placed in a curing furnace, first heated to 150-200°C at a heating rate of 3°C / min, and kept warm for 3 hours to achieve preliminary curing; then heated to 200-300°C at a heating rate of 3°C / min, and kept warm for 3 hours to achieve deep curing, and then cooled to room temperature with the furnace to complete the curing of the impregnation liquid in the graphite pores, enhance the performance of the graphite product, and obtain a cured graphite product.

[0036] (5) Post-processing

[0037] The surface of the solidified graphite product obtained in step (4) is cleaned by grinding or chemical cleaning to remove excess impregnation liquid residue, thereby obtaining a post-treated graphite product.

[0038] The following describes it in detail with reference to specific embodiments.

[0039] Example 1

[0040] (1) Pretreatment: Select isostatically pressed graphite products of appropriate specifications, clean the surface of the isostatically pressed graphite products with ethanol by ultrasonic cleaning, and place the cleaned isostatically pressed graphite products in a vacuum drying oven for drying at a temperature of 100°C for 3 hours to obtain pretreated graphite products.

[0041] (2) Vacuum impregnation

[0042] The pretreated graphite product obtained in step (1) is placed in an impregnation container, which is sealed and connected to a vacuum system. The impregnation container is first evacuated to reduce the internal pressure to 50 Pa and maintained in a vacuum state for 20 minutes. Subsequently, an impregnation liquid is slowly injected until the impregnation liquid submerges the pretreated graphite product, and the product is impregnated in a vacuum environment for 2 hours to obtain a vacuum-impregnated graphite product; wherein the solvent of the impregnation liquid is an organic solvent, and the solvent of the impregnation liquid is ethanol; the solutes of the impregnation liquid are phenolic resin and an antioxidant, the mass fraction of the phenolic resin is 40%, and the mass fraction of the antioxidant is 2%.

[0043] (3) Pressure impregnation

[0044] After the vacuum impregnation is completed, the vacuum system is turned off, and nitrogen is slowly introduced into the impregnation container to pressurize it, so that the pressure gradually increases to 10 MPa, and the pressure is maintained for 4 hours to obtain the graphite product after pressure impregnation.

[0045] (4) Curing treatment

[0046] The pressurized impregnated graphite product obtained in step (3) is placed in a curing furnace, first heated to 180°C at a heating rate of 3°C / min, kept warm for 3 hours, then heated to 280°C at a heating rate of 3°C / min, kept warm for 3 hours, to obtain a cured graphite product.

[0047] (5) Post-processing

[0048] The surface of the solidified graphite product obtained in step (4) is cleaned by grinding to obtain a post-treated graphite product.

[0049] Example 2

[0050] (1) Pretreatment: Select isostatically pressed graphite products of appropriate specifications, clean the surface of the isostatically pressed graphite products by wiping with alkaline cleaning solution, and place the cleaned isostatically pressed graphite products in a vacuum drying oven for drying at a temperature of 120°C for 2 hours to obtain pretreated graphite products.

[0051] (2) Vacuum impregnation

[0052] The pretreated graphite product obtained in step (1) is placed in an impregnation container, sealed and connected to a vacuum system, the impregnation container is first evacuated to reduce the internal pressure to 80 Pa, and the vacuum state is maintained for 30 minutes, and then the impregnation liquid is slowly injected until the impregnation liquid submerges the pretreated graphite product, and the product is impregnated in a vacuum environment for 1.5 hours to obtain a vacuum-impregnated graphite product; wherein the solvent of the impregnation liquid is an organic solvent, and the solvent of the impregnation liquid is toluene; the solute of the impregnation liquid includes a boron metal organic compound, and the mass fraction of the boron metal organic compound is 50%.

[0053] (3) Pressure impregnation

[0054] After the vacuum impregnation is completed, the vacuum system is turned off, and nitrogen is slowly introduced into the impregnation container to pressurize it, so that the pressure gradually increases to 15 MPa, and the pressure is maintained for 3 hours to obtain the graphite product after pressure impregnation.

[0055] (4) Curing treatment

[0056] The pressurized impregnated graphite product obtained in step (3) is placed in a curing furnace, first heated to 180°C at a heating rate of 3°C / min, kept warm for 3 hours, then heated to 280°C at a heating rate of 3°C / min, kept warm for 3 hours, to obtain a cured graphite product.

[0057] (5) Post-processing

[0058] The surface of the solidified graphite product obtained in step (4) is cleaned by grinding to obtain a post-treated graphite product.

[0059] Example 3

[0060] (1) Pretreatment: Select isostatically pressed graphite products of appropriate specifications, clean the surface of the isostatically pressed graphite products with ethanol by ultrasonic cleaning, and place the cleaned isostatically pressed graphite products in a vacuum drying oven for drying at a temperature of 80°C for 4 hours to obtain pretreated graphite products.

[0061] (2) Vacuum impregnation

[0062] The pretreated graphite product obtained in step (1) is placed in an impregnation container, which is sealed and connected to a vacuum system. The impregnation container is first evacuated to reduce the internal pressure to 10 Pa and maintained in a vacuum state for 20 minutes. Subsequently, an impregnation liquid is slowly injected until the impregnation liquid submerges the pretreated graphite product, and the product is impregnated in a vacuum environment for 3 hours to obtain a vacuum-impregnated graphite product; wherein the solvent of the impregnation liquid is an organic solvent, and the solvent of the impregnation liquid is ethanol or toluene; the solute of the impregnation liquid includes a furan resin and a curing accelerator, and the mass fraction of the furan resin is 27%, and the mass fraction of the curing accelerator is 3%.

[0063] (3) Pressure impregnation

[0064] After the vacuum impregnation is completed, the vacuum system is turned off, and nitrogen is slowly introduced into the impregnation container to pressurize it, so that the pressure gradually increases to 20 MPa, and the pressure is maintained for 2 hours to obtain the graphite product after pressure impregnation.

[0065] (4) Curing treatment

[0066] The pressure-impregnated graphite product obtained in step (3) is placed in a curing furnace, first heated to 150°C at a heating rate of 3°C / min, kept warm for 3 hours, then heated to 300°C at a heating rate of 3°C / min, kept warm for 3 hours, to obtain a cured graphite product.

[0067] (5) Post-processing

[0068] The surface of the solidified graphite product obtained in step (4) is cleaned by grinding to obtain a post-treated graphite product.

[0069] Example 4

[0070] (1) Pretreatment: Select isostatically pressed graphite products of appropriate specifications, clean the surface of the isostatically pressed graphite products by wiping with alkaline cleaning solution, and place the cleaned isostatically pressed graphite products in a vacuum drying oven for drying at a temperature of 100°C for 3 hours to obtain pretreated graphite products.

[0071] (2) Vacuum impregnation

[0072] The pretreated graphite product obtained in step (1) is placed in an impregnation container, which is sealed and connected to a vacuum system. The impregnation container is first evacuated to reduce the internal pressure to 100 Pa and maintained in a vacuum state for 15 minutes. Subsequently, an impregnation liquid is slowly injected until the impregnation liquid submerges the pretreated graphite product, and the product is impregnated in a vacuum environment for 1 hour to obtain a vacuum-impregnated graphite product; wherein the solvent of the impregnation liquid is an organic solvent, and the solvent of the impregnation liquid is ethanol; the solute of the impregnation liquid includes a phenolic resin, and the solute mass fraction of the phenolic resin is 50%.

[0073] (3) Pressure impregnation

[0074] After the vacuum impregnation is completed, the vacuum system is turned off, and nitrogen is slowly introduced into the impregnation container to pressurize it, so that the pressure gradually increases to 5 MPa, and the pressure is maintained for 5 hours to obtain the graphite product after pressure impregnation.

[0075] (4) Curing treatment

[0076] The pressure-impregnated graphite product obtained in step (3) is placed in a curing furnace, first heated to 150-200°C at a heating rate of 3°C / min, kept warm for 3 hours, then heated to 200-300°C at a heating rate of 3°C / min, kept warm for 3 hours, to obtain a cured graphite product.

[0077] (5) Post-processing

[0078] The surface of the solidified graphite product obtained in step (4) is cleaned by grinding to obtain a post-treated graphite product.

[0079] Example 5

[0080] (1) Pretreatment: Select isostatically pressed graphite products of appropriate specifications, clean the surface of the isostatically pressed graphite products with ethanol by ultrasonic cleaning, and place the cleaned isostatically pressed graphite products in a vacuum drying oven for drying at a temperature of 90°C for 2 hours to obtain pretreated graphite products.

[0081] (2) Vacuum impregnation

[0082] The pretreated graphite product obtained in step (1) is placed in an impregnation container, which is sealed and connected to a vacuum system. The impregnation container is first evacuated to reduce the internal pressure to 20 Pa and maintained in a vacuum state for 20 minutes. Subsequently, an impregnation liquid is slowly injected until the impregnation liquid submerges the pretreated graphite product, and the product is impregnated in a vacuum environment for 3 hours to obtain a vacuum-impregnated graphite product; wherein the solvent of the impregnation liquid is an organic solvent, and the solvent of the impregnation liquid is toluene; the solute of the impregnation liquid includes a phenolic resin and an antioxidant, and the mass fraction of the phenolic resin is 58%, and the mass fraction of the antioxidant is 2%.

[0083] (3) Pressure impregnation

[0084] After the vacuum impregnation is completed, the vacuum system is turned off, and nitrogen is slowly introduced into the impregnation container to pressurize it, so that the pressure gradually increases to 15 MPa, and the pressure is maintained for 6 hours to obtain the graphite product after pressure impregnation.

[0085] (4) Curing treatment

[0086] The pressurized impregnated graphite product obtained in step (3) is placed in a curing furnace, first heated to 200°C at a heating rate of 3°C / min, kept warm for 3 hours, then heated to 280°C at a heating rate of 3°C / min, kept warm for 3 hours, to obtain a cured graphite product.

[0087] (5) Post-processing

[0088] The surface of the solidified graphite product obtained in step (4) is cleaned by grinding to obtain a post-treated graphite product.

[0089] Example 6

[0090] (1) Pretreatment: Select isostatically pressed graphite products of appropriate specifications, clean the surface of the isostatically pressed graphite products by wiping with alkaline cleaning solution, and place the cleaned isostatically pressed graphite products in a vacuum drying oven for drying at a temperature of 90°C for 4 hours to obtain pretreated graphite products.

[0091] (2) Vacuum impregnation

[0092] The pretreated graphite product obtained in step (1) is placed in an impregnation container, which is sealed and connected to a vacuum system. The impregnation container is first evacuated to reduce the internal pressure to 30 Pa and maintained in a vacuum state for 15 minutes. Subsequently, an impregnation liquid is slowly injected until the impregnation liquid submerges the pretreated graphite product, and the product is impregnated in a vacuum environment for 3 hours to obtain a vacuum-impregnated graphite product; wherein the solvent of the impregnation liquid is an organic solvent, and the solvent of the impregnation liquid is ethanol or toluene; the solute of the impregnation liquid includes a phenolic resin, and the mass fraction of the phenolic resin is 40%.

[0093] (3) Pressure impregnation

[0094] After the vacuum impregnation is completed, the vacuum system is turned off, and nitrogen is slowly introduced into the impregnation container to pressurize it, so that the pressure gradually increases to 20 MPa, and the pressure is maintained for 6 hours to obtain the graphite product after pressure impregnation.

[0095] (4) Curing treatment

[0096] The pressure-impregnated graphite product obtained in step (3) is placed in a curing furnace, first heated to 150°C at a heating rate of 3°C / min, kept warm for 3 hours, then heated to 300°C at a heating rate of 3°C / min, kept warm for 3 hours, to obtain a cured graphite product.

[0097] (5) Post-processing

[0098] The surface of the solidified graphite product obtained in step (4) is cleaned by grinding to obtain a post-treated graphite product.

[0099] Performance tests were conducted on the above multiple embodiments, and the test results are shown in Table 1.

[0100]

[0101]

[0102] Table 1

[0103] It can be clearly concluded from the above data that the density of the isostatic graphite obtained by the impregnation method of the present invention can reach 2.0g / cm 3It solves the problem of uneven impregnation in traditional impregnation methods, making it difficult for the impregnant to penetrate deep into the graphite, thus preventing damage to the internal structure of the isostatic graphite. In addition, a staged temperature increase curing process is adopted. The first stage of heat preservation and curing can enable the resin to form a preliminary network structure, and the second stage of heat preservation and curing can further promote the cross-linking density of the phenolic resin, ensuring that the resin is fully cured, and can improve the flexural strength of the isostatic graphite, up to 70MPa.

[0104] The above description is merely a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any minor modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for impregnating isostatically pressed graphite with uniform impregnation, characterized in that: The following steps are included: (1) Pretreatment Select isostatically pressed graphite products of appropriate specifications, clean their surfaces to remove oil stains and impurities, and dry the cleaned isostatically pressed graphite products in a vacuum drying oven at a drying temperature of 80-120°C for 2-4 hours to obtain pretreated graphite products; (2) Vacuum impregnation The pretreated graphite product obtained in step (1) is placed in an impregnation container, which is sealed and connected to a vacuum system. The impregnation container is first evacuated to reduce the internal pressure to 10-100 Pa, and the vacuum state is maintained for 15-30 minutes to fully expose the internal pores of the graphite. Subsequently, the impregnation liquid is slowly injected until the impregnation liquid submerges the pretreated graphite product, and the product is impregnated in a vacuum environment for 1-3 hours. The vacuum negative pressure is used to promote the impregnant to penetrate deeply into the pores of the graphite to obtain a vacuum-impregnated graphite product; (3) Pressure impregnation After the vacuum impregnation is completed, the vacuum system is turned off and inert gas is slowly introduced into the impregnation container to pressurize it, so that the pressure gradually increases to 5-20 MPa and the pressure is maintained for 2-6 hours. The external pressure further pushes the impregnant to fill the deep pores of the graphite to ensure uniform and sufficient impregnation, and obtains the graphite product after pressure impregnation; (4) Curing treatment The pressurized impregnated graphite product obtained in step (3) is placed in a curing furnace, first heated to 150-200°C at a heating rate of 3°C / min, and kept warm for 3 hours to achieve preliminary curing; then heated to 200-300°C at a heating rate of 3°C / min, and kept warm for 3 hours to achieve deep curing, and then cooled to room temperature with the furnace to complete the curing of the impregnation liquid in the graphite pores, enhance the performance of the graphite product, and obtain a cured graphite product.

2. The method for impregnating isostatically pressed graphite with uniform impregnation according to claim 1, wherein: In the step (1), the surface of the isostatically pressed graphite product is cleaned by ultrasonic cleaning and chemical wiping.

3. The method for impregnating isostatically pressed graphite with uniform impregnation according to claim 1, wherein: In the step (2), the solvent of the impregnation solution is an organic solvent, the solute of the impregnation solution includes any one of phenolic resin, furan resin, and metal organic compound, and the mass fraction of the solute of the impregnation solution is 30-60%.

4. The method for impregnating isostatically pressed graphite with uniform impregnation according to claim 3, wherein: In the step (2), the solvent of the impregnation solution is ethanol or toluene.

5. The method for impregnating isostatically pressed graphite with uniform impregnation according to claim 3, wherein: In the step (2), the solute of the impregnation solution further includes at least one of an antioxidant and a curing accelerator.

6. The method for impregnating isostatically pressed graphite with uniform impregnation according to claim 1, wherein: In the step (3), the inert gas is nitrogen.

7. The method for impregnating isostatically pressed graphite with uniform impregnation according to claim 1, wherein: The method further includes step (5), and the process of step (5) is as follows: (5) Post-processing The surface of the solidified graphite product obtained in step (4) is cleaned to remove excess impregnation liquid residue to obtain a post-treated graphite product.

8. The method for impregnating isostatically pressed graphite with uniform impregnation according to claim 7, wherein: In the step (5), the surface of the solidified graphite product is cleaned by grinding or chemical cleaning.

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