Enhanced graphite material and preparation method and application thereof

Abstract

The application discloses an enhanced graphite material and a preparation method and application thereof, and relates to the technical field of surface modification of carbon materials. The preparation method of the enhanced graphite material comprises the following steps: S1. substrate pretreatment; S2. coating deposition: placing the pretreated porous graphite substrate in a high-temperature vacuum deposition device, and introducing mixed reaction gas composed of hydrogen, argon and hydrocarbon, so as to deposit a graphite coating layer on the inner pore surface of the porous graphite substrate in situ; the volume flow ratio of the hydrogen, the argon and the hydrocarbon is (5-10):(5-10):(1-2); and S3. after the deposition is completed, cooling is carried out in a protective atmosphere, so that the enhanced graphite material is obtained. The application provides an enhanced graphite material and a preparation method and application thereof, and the enhanced graphite material has the advantages of significantly improved corrosion resistance, maintained excellent gas distribution performance, high purity and strong adaptability.

Description

Technical Field

[0001] This invention relates to the field of carbon material surface modification technology, and in particular to an enhanced graphite material, its preparation method and application. Background Technology

[0002] Currently, in fields such as carbon fiber reinforced carbon matrix composites (C / C materials), the technology of using natural gas as a carbon source and depositing pyrolytic carbon at high temperatures in a vacuum furnace has been extensively studied and widely applied. This technology, by filling the pores of C / C materials with pyrolytic carbon, can significantly improve the density and overall strength of the material.

[0003] In the field of semiconductor crystal growth, especially in the growth of crystals such as silicon carbide (SiC), the furnace often contains a corrosive atmosphere containing silicon vapor or silicon carbide vapor. Porous graphite, due to its complex and interconnected pore structure, can act as a gas distributor to achieve uniform gas flow, making it an ideal furnace lining material. However, traditional porous graphite materials are highly susceptible to corrosion under high-temperature silicon vapor atmospheres, leading to pore structure damage and uneven gas distribution, thereby affecting the quality and stability of crystal growth and shortening the material's lifespan.

[0004] Therefore, developing a technology that can form a protective coating on the surface and internal pores of porous graphite, maintaining its excellent gas distribution characteristics and significantly improving its resistance to silicon vapor erosion, has important industrial application value. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an enhanced graphite material, its preparation method, and its applications.

[0006] Specifically, the following technical solutions are included: In a first aspect, a method for preparing an enhanced graphite material is provided, comprising the following steps: S1. Matrix pretreatment: Clean the porous graphite matrix to remove impurities from the surface and pores; S2. Coating deposition: The pretreated porous graphite substrate is placed in a high-temperature vacuum deposition equipment, and a mixed reactive gas composed of hydrogen, argon and hydrocarbons is introduced to deposit a graphite coating in situ on the surface of the internal pores of the porous graphite substrate; the hydrocarbons are at least one of methane, ethane and propane; the volume flow rate ratio of hydrogen, argon and hydrocarbons is (5-10):(5-10):(1-2); S3. After deposition, the material is cooled under a protective atmosphere to obtain the reinforced graphite material.

[0007] Wherein, the volumetric flow rate ratio is the volumetric flow rate ratio under standard conditions.

[0008] Preferably, in step S2, the high-temperature vacuum deposition equipment is a chemical vapor deposition furnace.

[0009] Furthermore, in step S2, the deposition temperature is 1800-2300℃.

[0010] Furthermore, in step S2, the system pressure for deposition is 50-120 mbar.

[0011] Furthermore, in step S2, the thickness of the graphite coating deposition is 10-30 μm.

[0012] Furthermore, the hydrogen, argon, and hydrocarbons used in step S2 are all of electronic grade purity.

[0013] Furthermore, in step S3, the protective atmosphere is hydrogen and / or argon.

[0014] Furthermore, in step S1, the cleaning involves ultrasonic cleaning with anhydrous ethanol for 30 minutes followed by drying.

[0015] Furthermore, in step S1, the average pore size of the porous graphite matrix is ​​55 μm, and the porosity is 40%.

[0016] In a second aspect, an enhanced graphite material is provided, which is prepared by the method for preparing the enhanced graphite material described in the first aspect.

[0017] Thirdly, the application of an enhanced graphite material prepared by the method described in the first aspect in the preparation of lining components, gas distributors, or high-temperature corrosion-resistant load-bearing components for silicon carbide steam generators is provided.

[0018] Preferably, the silicon carbide steam generator comprises a furnace top cover, a furnace cylinder, and a furnace bottom plate arranged sequentially. The furnace top cover is located at the top of the furnace cylinder, and the furnace bottom plate is located at the bottom of the furnace cylinder. A carbon-carbon barrel is provided inside the furnace cylinder, and an insulation layer is provided between the furnace cylinder and the carbon-carbon barrel, the insulation layer surrounding the carbon-carbon barrel. A crucible, a perforated plate, and a perforated container are arranged sequentially from bottom to top inside the carbon-carbon barrel. A seed crystal is provided inside the perforated container. A heater is also provided inside the carbon-carbon barrel. Electrodes are provided on the furnace bottom plate.

[0019] The beneficial effects of this invention are as follows: 1. Significantly improves corrosion resistance: The deposited dense graphite coating effectively seals or modifies the pore surface inside the porous graphite, forming a physical barrier that greatly enhances the material's durability in corrosive atmospheres such as those containing silicon carbide vapor.

[0020] 2. Maintain excellent gas distribution performance: Through precise control of coating thickness and structure, it is possible to enhance protection while maintaining the original porous graphite pore structure that is suitable for uniform gas distribution, resulting in a more uniform and controllable pore size distribution.

[0021] 3. High purity and strong adaptability: The use of electronic-grade gas source and vacuum high-temperature process ensures the high purity of the coating and avoids introducing impurities that could contaminate the crystal growth environment. This formulation system has universality and a superior process window for the deposition of porous carbon substrates. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a physical image of the enhanced graphite material of Embodiment 3 of the present invention; Figure 2 This is a physical image of the enhanced graphite material of Embodiment 4 of the present invention; Figure 3 This is a schematic diagram of the silicon carbide steam generator used in the enhanced graphite material of this invention. Explanation of the markings in the image: 1-Furnace top cover; 2-Furnace cylinder; 3-Furnace bottom plate; 4-Carbon barrel; 5-Insulation layer; 6-Crucible; 7-Perforated plate; 8-Perforated barrel; 9-Seed crystal; 10-Heater; 11-Electrode. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0026] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0027] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0028] To better understand the technical content of the present invention, the technical solution of the present invention will be further introduced and explained below with reference to specific embodiments.

[0029] The hydrogen, argon, and hydrocarbons used in step S2 of the embodiments / comparative examples of this invention are all of electronic grade purity.

[0030] The porous graphite matrix parameters used in the embodiments / comparative examples of this invention are shown in Table 1 below: Table 1 Parameters of porous graphite matrix Example 1 An enhanced graphite material (enhanced graphite disc) is prepared by the method for preparing the enhanced graphite material.

[0031] The preparation method of the enhanced graphite material includes the following steps: S1. Matrix pretreatment: Take a porous graphite matrix with an average pore size of 55μm and a porosity of 40% (specifically a circular plate with a size of Φ50mm×10mm), ultrasonically clean the porous graphite matrix with anhydrous ethanol for 30 minutes and dry it to remove impurities on the surface and in the pores. S2. Coating Deposition: The pretreated porous graphite substrate was placed in a chemical vapor deposition furnace, and the vacuum was reduced to below 10 Pa. A mixed reaction gas consisting of hydrogen, argon, and methane was introduced (H2 gas flow rate: 100 L / min, Ar gas flow rate: 100 L / min, CH4 gas flow rate: 20 L / min). The furnace temperature was raised to 1800℃, and the system pressure was adjusted and stabilized at 50 mbar. Deposition was carried out under the above conditions for 50 min, and a graphite coating was deposited in situ on the surface of the internal pores of the porous graphite substrate. The thickness of the graphite coating was 16 μm, and it was a black matte pyrolytic carbon coating, which was identified as an anisotropic graphite coating. S3. After deposition, CH4 is shut off, and the furnace is cooled to below 200°C under a protective atmosphere of H2 and Ar to obtain the reinforced graphite material.

[0032] Example 2 An enhanced graphite material (enhanced graphite porous cylinder) is prepared by the method for preparing the enhanced graphite material.

[0033] The preparation method of the enhanced graphite material includes the following steps: S1. Matrix pretreatment: Take a porous graphite matrix with an average pore size of 55μm and a porosity of 40% (specifically a porous cylinder with a diameter of 50mm and a diameter of 10mm). Clean the porous graphite matrix with anhydrous ethanol for 30 minutes and dry it to remove impurities from the surface and pores. S2. Coating Deposition: The pretreated porous graphite substrate was placed in a chemical vapor deposition furnace, and the vacuum was reduced to below 10 Pa. A mixed reaction gas consisting of hydrogen, argon, and methane was introduced (H2 gas flow rate: 100 L / min, Ar gas flow rate: 100 L / min, CH4 gas flow rate: 20 L / min). The furnace temperature was raised to 1800℃, and the system pressure was adjusted and stabilized at 50 mbar. Deposition was carried out under the above conditions for 50 min, and a graphite coating was deposited in situ on the surface of the internal pores of the porous graphite substrate. The thickness of the graphite coating was 16 μm, and it was a black matte pyrolytic carbon coating, which was identified as an anisotropic graphite coating. S3. After deposition, CH4 is shut off, and the furnace is cooled to below 200°C under a protective atmosphere of H2 and Ar to obtain the reinforced graphite material.

[0034] Example 3 An enhanced graphite material (enhanced graphite disc) is prepared by the method for preparing the enhanced graphite material.

[0035] The preparation method of the enhanced graphite material includes the following steps: S1. Matrix pretreatment: Take a porous graphite matrix with an average pore size of 55μm and a porosity of 40% (specifically a circular plate with a size of Φ50mm×10mm), ultrasonically clean the porous graphite matrix with anhydrous ethanol for 30 minutes and dry it to remove impurities on the surface and in the pores. S2. Coating Deposition: The pretreated porous graphite substrate was placed in a chemical vapor deposition furnace, and the vacuum was reduced to below 10 Pa. A mixed reaction gas consisting of hydrogen, argon, and methane was introduced (H2 gas flow rate: 100 L / min, Ar gas flow rate: 100 L / min, CH4 gas flow rate: 20 L / min). The furnace temperature was raised to 2200℃, and the system pressure was adjusted and stabilized at 100 mbar. Deposition was carried out for 120 min under the above conditions. A graphite coating was deposited in situ on the surface of the internal pores of the porous graphite substrate. The thickness of the graphite coating was 30 μm. It was a bright silver-gray pyrolytic carbon coating and was identified as an isotropic graphite coating. S3. After deposition, the CH4 valve is shut off, and the furnace is cooled to below 200°C under a protective atmosphere of H2 and Ar before being unloaded to obtain the reinforced graphite material. Example 3: A physical image of the reinforced graphite material is shown below. Figure 1 As shown.

[0036] Example 4 An enhanced graphite material (enhanced graphite porous cylinder) is prepared by the method for preparing the enhanced graphite material.

[0037] The preparation method of the enhanced graphite material includes the following steps: S1. Matrix pretreatment: Take a porous graphite matrix with an average pore size of 55μm and a porosity of 40% (specifically a porous cylinder with a diameter of 50mm and a diameter of 10mm). Clean the porous graphite matrix with anhydrous ethanol for 30 minutes and dry it to remove impurities from the surface and pores. S2. Coating Deposition: The pretreated porous graphite substrate was placed in a chemical vapor deposition furnace, and the vacuum was reduced to below 10 Pa. A mixed reaction gas consisting of hydrogen, argon, and methane was introduced (H2 gas flow rate: 100 L / min, Ar gas flow rate: 100 L / min, CH4 gas flow rate: 20 L / min). The furnace temperature was raised to 2200℃, and the system pressure was adjusted and stabilized at 100 mbar. Deposition was carried out for 120 min under the above conditions. A graphite coating was deposited in situ on the surface of the internal pores of the porous graphite substrate. The thickness of the graphite coating was 30 μm. It was a bright silver-gray pyrolytic carbon coating and was identified as an isotropic graphite coating. S3. After deposition, the CH4 valve is shut off, and the furnace is cooled to below 200°C under a protective atmosphere of H2 and Ar before being unloaded to obtain the reinforced graphite material. Example 4: A physical image of the reinforced graphite material is shown below. Figure 2 As shown.

[0038] Comparative Example 1 An enhanced graphite material (enhanced graphite disc) is prepared by the method for preparing the enhanced graphite material.

[0039] The preparation method of the enhanced graphite material includes the following steps: S1. Matrix pretreatment: Take a porous graphite matrix with an average pore size of 55μm and a porosity of 40% (specifically a circular plate with a size of Φ50mm×10mm), ultrasonically clean the porous graphite matrix with anhydrous ethanol for 30 minutes and dry it to remove impurities on the surface and in the pores. S2. Coating Deposition: The pretreated porous graphite substrate was placed in a chemical vapor deposition furnace, and the vacuum was reduced to below 10 Pa. A mixed reaction gas consisting of hydrogen, argon, and methane was introduced (H2 gas flow rate: 80 L / min, Ar gas flow rate: 80 L / min, CH4 gas flow rate: 5 L / min). The furnace temperature was raised to 1600℃, and the system pressure was adjusted and stabilized at 50 mbar. Deposition was carried out under the above conditions for 50 min, and a graphite coating was deposited in situ on the surface of the internal pores of the porous graphite substrate. The thickness of the graphite coating was 9 μm, and it was a black matte pyrolytic carbon coating, which was identified as an anisotropic graphite coating. S3. After deposition, CH4 is shut off, and the furnace is cooled to below 200°C under a protective atmosphere of H2 and Ar to obtain the reinforced graphite material.

[0040] Comparative Example 2 An enhanced graphite material (enhanced graphite porous cylinder) is prepared by the method for preparing the enhanced graphite material.

[0041] The preparation method of the enhanced graphite material includes the following steps: S1. Matrix pretreatment: Take a porous graphite matrix with an average pore size of 55μm and a porosity of 40% (specifically a porous cylinder with a diameter of 50mm and a diameter of 10mm). Clean the porous graphite matrix with anhydrous ethanol for 30 minutes and dry it to remove impurities from the surface and pores. S2. Coating Deposition: The pretreated porous graphite substrate was placed in a chemical vapor deposition furnace, and the vacuum was reduced to below 10 Pa. A mixed reaction gas consisting of hydrogen, argon, and methane was introduced (H2 gas flow rate: 80 L / min, Ar gas flow rate: 80 L / min, CH4 gas flow rate: 5 L / min). The furnace temperature was raised to 1600℃, and the system pressure was adjusted and stabilized at 50 mbar. Deposition was carried out under the above conditions for 50 min, and a graphite coating was deposited in situ on the surface of the internal pores of the porous graphite substrate. The thickness of the graphite coating was 9 μm, and it was a black matte pyrolytic carbon coating, which was identified as an anisotropic graphite coating. S3. After deposition, CH4 is shut off, and the furnace is cooled to below 200°C under a protective atmosphere of H2 and Ar to obtain the reinforced graphite material.

[0042] Performance Testing – Deposition Weight Test The test results of the enhanced graphite materials of Examples 1-4 and Comparative Examples 1-2 are shown in Table 2 below: Table 2 Deposition test results of Examples 1-4 and Comparative Examples 1-2 Performance Testing – Resistance to Silicon Vapor Attack Test Using reinforced graphite discs and reinforced graphite porous cylinders as a set of test examples, the reinforced graphite materials of the embodiments / comparative examples were used to replace the porous plates and porous cylinders in a DN500*600 silicon carbide steam generator for testing. A schematic diagram of the silicon carbide steam generator using the reinforced graphite material of this invention is shown below. Figure 3 As shown.

[0043] A schematic diagram of the silicon carbide steam generator used in this invention, which incorporates the enhanced graphite material, is shown below. Figure 3 As shown.

[0044] The silicon carbide steam generator comprises a furnace top cover 1, a furnace cylinder 2, and a furnace bottom plate 3 arranged sequentially. The furnace top cover 1 is located at the top of the furnace cylinder 2, and the furnace bottom plate 3 is located at the bottom of the furnace cylinder 2. A carbon-carbon barrel 4 is installed inside the furnace cylinder 2, and a heat insulation layer 5 is provided between the furnace cylinder 2 and the carbon-carbon barrel 4, the heat insulation layer 5 surrounding the carbon-carbon barrel 4. A crucible 6, a perforated plate 7, and a perforated barrel 8 are arranged sequentially from bottom to top inside the carbon-carbon barrel 4. A seed crystal 9 is provided inside the perforated barrel 8. A heater 10 is also provided inside the carbon-carbon barrel 4. An electrode 11 is provided on the furnace bottom plate 3.

[0045] During the test, silicon carbide powder was placed in a crucible and heated to 2300°C in a silicon carbide vapor generator. The silicon carbide vapor diffused through a porous graphite disc (porous plate) and was collected at the silicon carbide seed crystal in the low-temperature porous container. After three consecutive runs, the sample was removed and observed to complete the silicon vapor erosion resistance test.

[0046] Experimental Example 1 The enhanced graphite disc sheet of Example 1 was used instead of the perforated plate, and the enhanced graphite perforated cylinder of Example 2 was used instead of the perforated barrel for testing.

[0047] Experimental Example 2 The enhanced graphite disc sheet of Example 3 was used instead of the perforated plate, and the enhanced graphite perforated cylinder of Example 4 was used instead of the perforated barrel for testing.

[0048] Experimental Example 3 Comparative Example 1 uses an enhanced graphite disc instead of a porous plate, and Comparative Example 2 uses an enhanced graphite porous cylinder instead of a porous barrel for testing.

[0049] The test results of resistance to silicon vapor attack in Examples 1-3 are as follows: After the test in Example 1 was completed, the reinforced graphite discs of Example 1 and the reinforced graphite porous cylinders of Example 2 showed pitting, but the coating was still present. This is because the raw material ratios of the reinforced graphite discs of Example 1 and the reinforced graphite porous cylinders of Example 2 were appropriate during coating deposition, but the deposition temperature was relatively low, resulting in mostly anisotropic carbon deposition and slightly poor density. However, since the coating thickness met the requirements, the pitting characteristic appeared after being etched by silicon carbide gas.

[0050] After the testing of Example 2 was completed, the reinforced graphite disc of Example 3 and the reinforced graphite porous cylinder of Example 4 had a small number of pits. Apart from silicon carbide crystal points adhering to the surface, they were generally intact. This is because the deposition temperature of the reinforced graphite disc of Example 3 and the reinforced graphite porous cylinder of Example 4 was increased during coating deposition, and the positive pressure atmosphere of deposition was also increased, resulting in a dense and isotropic pyrolytic graphite coating. After being etched by silicon carbide gas, apart from silicon carbide vapor point crystals, the overall performance was good.

[0051] After the test in Example 3 was completed, the porous graphite matrix was exposed in several places in the reinforced graphite disc of Comparative Example 1 and the reinforced graphite porous cylinder of Comparative Example 2. This is because the gas flow rate of the mixed reactive gas was changed during the coating deposition of the reinforced graphite disc of Comparative Example 1 and the reinforced graphite porous cylinder of Comparative Example 2, resulting in a significant shortage of carbon source and insufficient deposition thickness. They could not withstand the erosion of silicon carbide gas and directly exposed the porous graphite matrix.

[0052] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing an enhanced graphite material, characterized in that, Includes the following steps: S1. Matrix pretreatment: Clean the porous graphite matrix to remove impurities from the surface and pores; S2. Coating deposition: The pretreated porous graphite substrate is placed in a high-temperature vacuum deposition equipment, and a mixed reactive gas composed of hydrogen, argon and hydrocarbons is introduced to deposit a graphite coating in situ on the surface of the internal pores of the porous graphite substrate; the hydrocarbons are at least one of methane, ethane and propane; the volume flow rate ratio of hydrogen, argon and hydrocarbons is (5-10):(5-10):(1-2); S3. After deposition, the material is cooled under a protective atmosphere to obtain the reinforced graphite material.

2. The method for preparing the reinforced graphite material according to claim 1, characterized in that, In step S2, the deposition temperature is 1800-2300℃.

3. The method for preparing the reinforced graphite material according to claim 1, characterized in that, In step S2, the system pressure for deposition is 50-120 mbar.

4. The method for preparing the reinforced graphite material according to claim 1, characterized in that, In step S2, the thickness of the graphite coating deposition is 10-30 μm.

5. The method for preparing the reinforced graphite material according to claim 1, characterized in that, The hydrogen, argon, and hydrocarbons used in step S2 are all of electronic grade purity.

6. The method for preparing the reinforced graphite material according to claim 1, characterized in that, In step S3, the protective atmosphere is hydrogen and / or argon.

7. The method for preparing the reinforced graphite material according to claim 1, characterized in that, In step S1, the cleaning process involves ultrasonic cleaning with anhydrous ethanol for 30 minutes followed by drying.

8. The method for preparing the reinforced graphite material according to claim 1, characterized in that, In step S1, the average pore size of the porous graphite matrix is ​​55 μm and the porosity is 40%.

9. A reinforced graphite material, characterized in that, It is prepared by the method for preparing the reinforced graphite material according to any one of claims 1-8.

10. The application of an enhanced graphite material prepared by any one of claims 1-8 in the preparation of lining components, gas distributors, or high-temperature corrosion-resistant load-bearing components for silicon carbide steam generators.

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