Method for preparing porous graphite product with complex structure

Abstract

The invention provides a method for preparing a porous graphite product with a complex structure, and relates to the field of porous graphite products. The method for preparing the porous graphite product with the complex structure comprises the following steps of adhesive preparation, bonding treatment and sintering treatment. According to the method for preparing the porous graphite product with the complex structure, the porous graphite products with different complex structures can be effectively prepared by utilizing the existing production equipment and production process; meanwhile, the matching property of the porous graphite material and an adhesive is improved, and the shear strength of the prepared porous graphite product with the complex structure is effectively improved; the poor stability of a porous graphite product in a high-temperature environment is further improved, and good shear strength and corrosion resistance can be kept for a long time in the high-temperature environment.

Description

Technical Field

[0001] The present invention relates to the field of porous graphite products, in particular to a method for preparing porous graphite products with complex structures. Background Art

[0002] Graphite possesses numerous excellent properties, including electrical and thermal conductivity, high-temperature resistance, strong plasticity, and stable chemical properties, resulting in a wide range of applications. Early applications of graphite, primarily in the metallurgical industry, capitalized on its electrical conductivity and high-temperature resistance. As research into graphite materials continues to deepen, porous graphite products made from calcined coke have gained significant applications in aerospace, military, automotive, electronics, nuclear energy, and metallurgy due to their enhanced corrosion resistance, radiation resistance, self-lubrication, high and low temperature resistance, ease of processing, and lightweight properties.

[0003] However, as the application areas of porous graphite materials continue to expand, the problem of porous graphite products' limited application due to their simple structure has also been exposed. Under existing process conditions, due to the limitations of many factors such as the molding molds and production processes of porous graphite products, it is difficult to produce porous graphite products with complex structures that meet the predetermined requirements. How to use existing production equipment and production processes to effectively produce porous graphite products with different complex structures is a major technical problem that needs to be solved urgently.

[0004] During the development of complex porous graphite products using existing production equipment and processes, the inventors discovered that due to the unique high-porosity microporous structure of porous graphite, it is not well compatible with adhesives. This results in suboptimal shear strength and prevents effective optimization. Furthermore, this leads to poor stability in high-temperature environments, making it impossible to maintain good shear strength and corrosion resistance over the long term, hindering the further expansion of porous graphite products' applications. Summary of the Invention

[0005] In order to solve the technical problems existing in the prior art, the present invention provides a method for preparing porous graphite products with complex structures, which can utilize existing production equipment and production processes to effectively prepare porous graphite products with different complex structures; and at the same time improve the matching of porous graphite materials and adhesives, effectively improve the shear strength of the prepared porous graphite products with complex structures; and further improve the poor stability of porous graphite products in high-temperature environments, and can maintain good shear strength and corrosion resistance for a long time in high-temperature environments.

[0006] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows: A method for preparing a porous graphite product with a complex structure comprises the following steps: preparing an adhesive, bonding treatment, and sintering treatment; The method for preparing the adhesive comprises: uniformly mixing carbon powder, boron carbide, anhydrous ethanol, polyethylene glycol, stearic acid, polyvinyl pyrrolidone, and sodium lauryl sulfate to obtain a premix; spray-drying and heat-treating the premix to obtain a heat-treated material; adding the heat-treated material into an ethanol aqueous solution dispersed with γ-aminopropyltriethoxysilane, stirring and modifying the mixture to obtain a modified material; and uniformly mixing the modified material with a phenolic resin, a furan resin, and anhydrous ethanol to obtain an adhesive. The bonding treatment method comprises: applying a mixture of phenolic resin and epoxy resin to the bonding surface of the porous graphite block; applying an adhesive to the bonding surface of the porous graphite block after heat treatment; combining the bonding surfaces of two or more porous graphite blocks and applying pressure to fix them to obtain a fixed body; The fixed body is sintered to obtain a porous graphite product with a complex structure.

[0007] Preferably, in the preparation of the premix, the weight ratio of carbon powder to boron carbide is 3-7:3-7; The weight of anhydrous ethanol is 30-50% of the total weight of carbon powder and boron carbide; The weight of polyethylene glycol is 0.1-5% of the total weight of carbon powder and boron carbide; The weight of stearic acid is 0.1-3% of the total weight of carbon powder and boron carbide; The weight of polyvinyl pyrrolidone is 0.1-2% of the total weight of carbon powder and boron carbide; The weight of sodium lauryl sulfate is 0.1-2% of the total weight of the carbon powder and boron carbide.

[0008] Preferably, in the preparation of the adhesive, the inlet temperature of the spray drying is controlled to be 150-180°C, the outlet temperature is controlled to be 80-100°C, the spray pressure is controlled to be 0.1-1 MPa, and the feed rate is controlled to be 70-100 L / h.

[0009] Preferably, in the preparation of the adhesive, the heat treatment temperature is 100-400° C., and the heat treatment time is 10-20 hours.

[0010] Preferably, in the preparation of the adhesive, the weight of γ-aminopropyltriethoxysilane is 0.5-3% of the weight of the heat-treated material; The weight of the ethanol aqueous solution is 1.6-1.9 times the weight of the heat-treated material; The volume concentration of the ethanol aqueous solution is 90-95%.

[0011] Preferably, in the preparation of the adhesive, the solid content of the phenolic resin is 40-60wt%, and the solid content of the furan resin is 40-60wt%; The weight ratio of phenolic resin to furan resin is 1-3:1-3; The weight of the modified material is 10-50% of the total weight of the phenolic resin and furan resin; The weight of anhydrous ethanol is 2-10 times the total weight of the phenolic resin and the furan resin.

[0012] Furthermore, in the bonding process, before the phenolic resin and the epoxy resin are mixed and applied to the bonding surface of the porous graphite block, the porous graphite block is first ultrasonically cleaned with deionized water; The frequency of the ultrasonic cleaning is 40-60HKz, and the temperature of the ultrasonic cleaning is 40-70°C.

[0013] Preferably, in the bonding process, the solid content of the phenolic resin is 40-60wt%, and the solid content of the epoxy resin is 50-60wt%; The weight ratio of phenolic resin to epoxy resin is 5-7:3-5; The coating thickness of the resin on the bonding surface of the porous graphite block is 0.5-1mm; The coating thickness of the adhesive on the bonding surface of the porous graphite block is 0.5-2 mm.

[0014] Preferably, in the bonding process, the heat treatment temperature is 300-700°C and the heat treatment time is 5-100h; The fixed applied pressure is 5-10 MPa.

[0015] Furthermore, the sintering method is as follows: the fixed body is heated from room temperature to 200°C at a heating rate of 1-5°C / min in a vacuum environment of 5-100 Pa, and then sintered at this temperature for 30-200 minutes; the temperature is further heated from 200°C to 500°C, and then sintered at this temperature for 30-300 minutes; the temperature is further heated from 500°C to 800-1200°C, and then sintered at this temperature for 60-300 minutes to complete the sintering treatment.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) The method for preparing a porous graphite product with a complex structure of the present invention comprises the following steps: firstly, carbon powder, boron carbide, polyethylene glycol, stearic acid, polyvinyl pyrrolidone and sodium lauryl sulfate are mixed to prepare a premix, which is then spray-dried and heat-treated to obtain a heat-treated material; the heat-treated material is modified by γ-aminopropyltriethoxysilane to obtain a modified material; the modified material is uniformly mixed with phenolic resin, furan resin and anhydrous ethanol to obtain an adhesive; then, a mixture of phenolic resin and epoxy resin and an adhesive are sequentially coated on the bonding surface of the porous graphite block, and the porous graphite product with a complex structure is obtained by sintering; the aforementioned technical means cooperate with each other and work synergistically, and can effectively prepare porous graphite products with different complex structures using existing production equipment and production processes; and at the same time, the matching of the porous graphite material and the adhesive is improved, thereby effectively improving the shear strength of the prepared porous graphite product with a complex structure; and further improving the poor stability of the porous graphite product in a high temperature environment, so that the porous graphite product can maintain good shear strength and corrosion resistance for a long time in a high temperature environment.

[0017] (2) The method for preparing a porous graphite product with a complex structure according to the present invention can achieve a shear strength of 30 MPa at the bonding point of the prepared porous graphite product. Furthermore, after the porous graphite product is placed in a temperature environment of 1000°C for 1000 hours, the shear strength of the bonding point can still be maintained at 15 MPa.

[0018] (3) The method of preparing porous graphite products with complex structures of the present invention has easy-to-obtain raw materials, a simple process, and a safe and controllable operation process, and is suitable for large-scale industrial production. DETAILED DESCRIPTION

[0019] In order to provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention are now described. It should be noted that the following detailed description is illustrative and is intended to further illustrate the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0020] It should be noted that the terms used herein are intended only to describe specific embodiments and are not intended to limit the exemplary embodiments of the present invention. As used herein, "first," "second," and the like are used to distinguish similar objects and are not used to describe a specific order or precedence. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0021] In order to solve the aforementioned technical problems of the present invention, an embodiment of the present invention provides a method for preparing a porous graphite product with a complex structure, comprising the following steps: preparing an adhesive, bonding treatment, and sintering treatment; The method for preparing the adhesive comprises: uniformly mixing carbon powder, boron carbide, anhydrous ethanol, polyethylene glycol, stearic acid, polyvinyl pyrrolidone, and sodium lauryl sulfate to obtain a premix; spray-drying and heat-treating the premix to obtain a heat-treated material; adding the heat-treated material into an ethanol aqueous solution dispersed with γ-aminopropyltriethoxysilane, stirring and modifying the mixture to obtain a modified material; and uniformly mixing the modified material with a phenolic resin, a furan resin, and anhydrous ethanol to obtain an adhesive. The bonding treatment method comprises: applying a mixture of phenolic resin and epoxy resin to the bonding surface of the porous graphite block; applying an adhesive to the bonding surface of the porous graphite block after heat treatment; combining the bonding surfaces of two or more porous graphite blocks and applying pressure to fix them to obtain a fixed body; The fixed body is sintered to obtain a porous graphite product with a complex structure.

[0022] The present invention first mixes carbon powder, boron carbide, polyethylene glycol, stearic acid, polyvinyl pyrrolidone, and sodium lauryl sulfate to form a premix, which is then spray-dried and heat-treated to obtain a heat-treated material. The heat-treated material is modified with γ-aminopropyltriethoxysilane to obtain a modified material. The modified material is then uniformly mixed with a phenolic resin, a furan resin, and anhydrous ethanol to obtain an adhesive. The bonding surface of the porous graphite block is then coated with a mixture of phenolic resin and epoxy resin and the adhesive in sequence, followed by sintering to produce a porous graphite product with a complex structure. The aforementioned treatment methods (such as spray drying, heat treatment, coating, and sintering) can all be implemented using existing production equipment and processes. The porous graphite product with a complex structure can be divided into multiple bondable porous graphite blocks, which are then bonded together to form the desired complex structure in a building block-like manner using a specific adhesive and process. This effectively overcomes the limitations of traditional mold forming and its processes, and allows for the flexible production of porous graphite products with various complex structures according to demand.

[0023] At the same time, in order to improve the matching of porous graphite materials and adhesives, carbon powder, boron carbide, phenolic resin and furan resin that are highly compatible with the porous graphite matrix are specifically selected to reduce the internal stress at the bonding interface of the porous graphite and improve the matching; and the heat-treated material is modified with γ-aminopropyltriethoxysilane to improve the interface bonding between the modified material and the phenolic resin and furan resin, ensuring that it is converted into a high-strength glassy carbon phase / reinforced particle combination during subsequent sintering, thereby greatly improving the shear strength of the bonding point of the porous graphite block.

[0024] Furthermore, during the bonding process, phenolic resin and epoxy resin are used as a primer to fully infiltrate and penetrate into the tiny pores on the surface of the porous graphite. After heat treatment and curing, a transition layer that is well bonded to the porous graphite matrix is ​​formed, thereby increasing the effective bonding surface area. Then, an adhesive is applied to ensure that the adhesive is efficiently bonded to the porous graphite surface. Finally, the fixed body is sintered, and the material at the bonding surface is completely carbonized to form a glassy carbon network composited with carbon powder and boron carbide reinforcing components, thereby further enhancing the interface bonding, improving the shear strength of the material, and effectively overcoming the poor stability of porous graphite products in high temperature environments, thereby improving their long-term stability in high temperature environments.

[0025] In order to better promote the coordinated cooperation of carbon powder, boron carbide and other technical means, in the embodiment of the present invention, the weight ratio of carbon powder and boron carbide is 3-7:3-7; the weight of anhydrous ethanol is 30-50% of the total weight of carbon powder and boron carbide; the weight of polyethylene glycol is 0.1-5% of the total weight of carbon powder and boron carbide; the weight of stearic acid is 0.1-3% of the total weight of carbon powder and boron carbide; the weight of polyvinyl pyrrolidone is 0.1-2% of the total weight of carbon powder and boron carbide; and the weight of sodium lauryl sulfate is 0.1-2% of the total weight of carbon powder and boron carbide.

[0026] According to the characteristics of the premix, in the embodiment of the present invention, the inlet temperature of the spray drying is controlled to be 150-180°C, the outlet temperature is 80-100°C, the spray pressure is 0.1-1Mpa, and the feed rate is 70-100L / h; the heat treatment temperature is 100-400°C, and the heat treatment time is 10-20h.

[0027] In order to better improve the modification effect of γ-aminopropyltriethoxysilane on the heat-treated material, in the embodiment of the present invention, the weight of γ-aminopropyltriethoxysilane is 0.5-3% of the weight of the heat-treated material; the weight of the ethanol aqueous solution is 1.6-1.9 times the weight of the heat-treated material; and the volume concentration of the ethanol aqueous solution is 90-95%.

[0028] To better improve the compatibility of the raw materials, in the embodiment of the present invention, the solid content of the phenolic resin is 40-60wt%, and the solid content of the furan resin is 40-60wt%; the weight ratio of the phenolic resin to the furan resin is 1-3:1-3; the weight of the modified material is 10-50% of the total weight of the phenolic resin and the furan resin; and the weight of the anhydrous ethanol is 2-10 times the total weight of the phenolic resin and the furan resin.

[0029] In order to facilitate the coating of phenolic resin and adhesive during the bonding process, ensure the coating effect, and avoid interference from impurities, in an embodiment of the present invention, before the phenolic resin and epoxy resin are mixed and coated on the bonding surface of the porous graphite block, the porous graphite block is first ultrasonically cleaned with deionized water; the frequency of the ultrasonic cleaning is 40-60HKz, and the temperature of the ultrasonic cleaning is 40-70°C.

[0030] In order to improve the coordination between the transition layer and the adhesive layer at the bonding surface of the porous graphite, in the embodiment of the present invention, the solid content of the phenolic resin is 40-60wt%, and the solid content of the epoxy resin is 50-60wt%; the weight ratio of the phenolic resin to the epoxy resin is 5-7:3-5; the coating thickness of the resin on the bonding surface of the porous graphite block is 0.5-1mm; and the coating thickness of the adhesive on the bonding surface of the porous graphite block is 0.5-2mm.

[0031] To achieve a better bonding effect, in the embodiment of the present invention, the heat treatment temperature is 300-700° C., the heat treatment time is 5-100 h, and the fixed applied pressure is 5-10 MPa.

[0032] Furthermore, in an embodiment of the present invention, the composite of the raw materials at the bonding surface is further promoted by curved temperature rising sintering, the interface bonding is further enhanced, and the shear strength of the material is improved. The sintering method is as follows: the fixed body is heated from room temperature to 200°C at a heating rate of 1-5°C / min in a vacuum environment of 5-100 Pa, and then sintered for 30-200 minutes; the temperature is further raised from 200°C to 500°C, and then sintered for 30-300 minutes; the temperature is further raised from 500°C to 800-1200°C, and then sintered for 60-300 minutes to complete the sintering process.

[0033] Specifically, an embodiment of the present invention provides a method for preparing a porous graphite product with a complex structure, comprising the following steps: preparing an adhesive, bonding treatment, and sintering treatment.

[0034] The preparation of the adhesive comprises the following steps: raw material preparation, raw material mixing, spray drying, heat treatment, modification treatment, and preparation.

[0035] The method for preparing raw materials is to prepare the following raw materials according to subsequent production requirements: phenolic resin (solid content 40-60wt%), furan resin (solid content 40-60wt%), epoxy resin (solid content 50-60wt%), carbon powder (particle size 200-500 mesh), boron carbide (particle size 200-800 mesh), anhydrous ethanol, polyethylene glycol (PEG1000-1500), stearic acid, polyvinyl pyrrolidone PVP, sodium lauryl sulfate SDS, and set aside.

[0036] The raw material mixing method comprises the following steps: uniformly mixing carbon powder, boron carbide, anhydrous ethanol, polyethylene glycol, stearic acid, polyvinyl pyrrolidone (PVP), and sodium lauryl sulfate (SDS) according to a predetermined weight ratio to obtain a premix; the specific mixing order is as follows: weighing carbon powder and boron carbide in a weight ratio of 3-7:3-7 and uniformly mixing to obtain a composite powder; then mixing the composite auxiliary material with anhydrous ethanol, polyethylene glycol, stearic acid, polyvinyl pyrrolidone (PVP), and sodium lauryl sulfate (SDS); and performing a mixing process using ultrasonic dispersion and mechanical stirring, controlling the ultrasonic frequency to be 20-60 kHz and the stirring rate to be 1000-3000 rpm, and performing a mixing process for 30-60 minutes to obtain a premix.

[0037] In the embodiment of the present invention, preferably, the weight ratio of carbon powder to boron carbide is 4-6:4-6.

[0038] In the embodiment of the present invention, preferably, the added amount of anhydrous ethanol is 30-50% by weight of the composite powder; more preferably 40-45%.

[0039] In the embodiment of the present invention, preferably, the amount of polyethylene glycol added is 0.1-5% by weight of the composite powder; more preferably 3.3-3.9%.

[0040] In the embodiment of the present invention, preferably, the added amount of stearic acid is 0.1-3% by weight of the composite powder; more preferably 1.8-2.5%.

[0041] In the embodiment of the present invention, preferably, the added amount of polyvinylpyrrolidone (PVP) is 0.1-2% by weight of the composite powder; more preferably 0.9-1.3%.

[0042] In the embodiment of the present invention, preferably, the added amount of sodium lauryl sulfate (SDS) is 0.1-2% by weight of the composite powder; more preferably 0.9-1.3%.

[0043] The spray drying method comprises controlling the spray drying inlet temperature to 150-180° C., the outlet temperature to 80-100° C., the spray pressure to 0.1-1 MPa, and the feed rate to 70-100 L / h, spray drying the premix to obtain a spray-dried material.

[0044] In the embodiment of the present invention, preferably, the inlet temperature of the spray drying is controlled to be 160-180°C, the outlet temperature is 80-100°C, the spray pressure is 0.4-0.8 MPa, and the feed rate is 80-95 L / h. The premix is ​​spray dried to obtain a spray-dried material.

[0045] The heat treatment method comprises placing the spray-dried material in a heat treatment device, heating it to 100-400° C., heat-treating it for 10-20 hours, and cooling it to obtain the heat-treated material.

[0046] In the embodiment of the present invention, preferably, the spray-dried material is placed in a heat treatment device, heated to 240-300° C., heat-treated for 12-16 hours, and then cooled to obtain a heat-treated material.

[0047] The modification method comprises adding γ-aminopropyltriethoxysilane to an ethanol aqueous solution with a volume concentration of 90-95%, stirring for 0.5-2 hours, and then adding the heat-treated material and stirring for 1-4 hours to obtain the modified material.

[0048] In the embodiment of the present invention, preferably, the added weight of γ-aminopropyltriethoxysilane is 0.5-3% of the weight of the heat-treated material; more preferably, 2.5-3%.

[0049] In the embodiment of the present invention, preferably, the weight of the ethanol aqueous solution is 1.6-1.9 times the weight of the heat-treated material.

[0050] The preparation method comprises the following steps: adding phenolic resin and furan resin to anhydrous ethanol and stirring evenly, controlling the weight ratio of the phenolic resin to the furan resin to be 1-3:1-3, and the weight of the anhydrous ethanol to be 2-10 times the total weight of the phenolic resin and the furan resin; then continuously adding the modified material, stirring and mixing for 1-5 hours, and obtaining the adhesive.

[0051] In the embodiment of the present invention, preferably, the weight of anhydrous ethanol is 4-6 times the total weight of the phenolic resin and the furan resin; and the stirring and mixing time after adding the modified material is 2-3 hours.

[0052] In the embodiment of the present invention, preferably, the weight of the modified material is 10-50% of the total weight of the phenolic resin and the furan resin; more preferably 35-42%.

[0053] The bonding process consists of the following steps: pretreatment, coating and fixing.

[0054] The pretreatment method comprises the following steps: cutting the porous graphite into porous graphite blocks of predetermined sizes according to the structural requirements of the porous graphite product, wherein the porous graphite blocks can be spliced ​​together to form a porous graphite product with a complex structure; and then ultrasonically cleaning the porous graphite blocks with deionized water, controlling the ultrasonic frequency to be 40-60HKz, the ultrasonic cleaning temperature to be 40-70°C, and the ultrasonic cleaning time to be 5-20min.

[0055] The coating and fixing method comprises the following steps: after ultrasonic cleaning, uniformly coating the mixed phenolic resin and epoxy resin on the bonding surface of the porous graphite block, controlling the coating thickness to be 0.5-1 mm; and after coating, heat treating the mixed phenolic resin at 300-700° C. for 5-10 hours; and uniformly coating the adhesive on the bonding surface of the porous graphite block, controlling the coating thickness to be 0.5-2 mm. After coating, splicing the porous graphite blocks according to the structural requirements of the porous graphite product (i.e., respectively combining the bonding surfaces of the two porous graphite blocks), and applying a pressure of 5-10 MPa for fixing to obtain a fixed body.

[0056] In the embodiment of the present invention, preferably, the solid content of the phenolic resin is 40-60 wt %, and the solid content of the epoxy resin is 50-60 wt %.

[0057] In the embodiment of the present invention, preferably, the weight ratio of the phenolic resin to the epoxy resin is 5-7:3-5.

[0058] In the embodiment of the present invention, preferably, the heat treatment temperature after the resin coating is completed is 400-550° C., and the heat treatment time is 6-8 hours.

[0059] In the embodiment of the present invention, preferably, the fixed applied pressure is 5-8 MPa.

[0060] The sintering method comprises the following steps: placing a fixed body in a vacuum sintering furnace, controlling the vacuum degree to be 5-100 Pa, heating the furnace from room temperature to 200° C. at a heating rate of 1-5° C. / min, and then sintering at 200° C. for 30-200 minutes; heating the furnace from 200° C. to 500° C. at a heating rate of 1-5° C. / min, and then sintering at 500° C. for 30-300 minutes; heating the furnace from 500° C. to 800-1200° C. at a heating rate of 1-5° C. / min, and then sintering at this temperature for 60-300 minutes, followed by cooling, thereby obtaining a porous graphite product with a complex structure.

[0061] In an embodiment of the present invention, preferably, the fixed body is placed in a vacuum sintering furnace, the vacuum degree is controlled to be 50-100 Pa, the temperature is increased from room temperature to 200 ° C at a heating rate of 2-4 ° C / min, and then sintered at 200 ° C for 90-130 minutes; the temperature is increased from 200 ° C to 500 ° C at a heating rate of 2-4 ° C / min, and then sintered at 500 ° C for 180-240 minutes; the temperature is increased from 500 ° C to 950-1150 ° C at a heating rate of 2-4 ° C / min, and then sintered at 120-200 minutes. After cooling, a porous graphite product with a complex structure is obtained.

[0062] The present invention will be further described below with reference to some specific embodiments.

[0063] Example 1 This embodiment provides a method for preparing a porous graphite product with a complex structure, and the specific steps are as follows: 1. Prepare adhesive 1) Raw material preparation Prepare the following raw materials according to subsequent production requirements: phenolic resin (solid content 50wt%), furan resin (solid content 50wt%), epoxy resin (solid content 60wt%), carbon powder (particle size 350 mesh), boron carbide (particle size 500 mesh), anhydrous ethanol, polyethylene glycol (PEG-1000), stearic acid, polyvinylpyrrolidone PVP, sodium lauryl sulfate SDS, and set aside.

[0064] 2) Raw material mixing Carbon powder, boron carbide, anhydrous ethanol, polyethylene glycol, stearic acid, polyvinyl pyrrolidone (PVP), and sodium lauryl sulfate (SDS) are uniformly mixed according to a predetermined weight ratio to obtain a premix. The specific mixing order is as follows: carbon powder and boron carbide are weighed and uniformly mixed in a weight ratio of 4:6 to obtain a composite powder; the composite excipients are then mixed with anhydrous ethanol, polyethylene glycol, stearic acid, polyvinyl pyrrolidone (PVP), and sodium lauryl sulfate (SDS), and the mixture is mixed using ultrasonic dispersion and mechanical stirring, with the ultrasonic frequency controlled at 30 kHz and the stirring rate at 2500 rpm, and the mixing process is performed for 30 minutes to obtain a premix.

[0065] The added amount of anhydrous ethanol is 40% of the weight of the composite powder.

[0066] The added amount of polyethylene glycol is 3.3% of the weight of the composite powder.

[0067] The added amount of stearic acid is 1.8% by weight of the composite powder.

[0068] The added amount of polyvinylpyrrolidone (PVP) is 0.9% of the weight of the composite powder.

[0069] The addition amount of sodium lauryl sulfate SDS is 0.9% of the weight of the composite powder.

[0070] 3) Spray drying The inlet temperature of the spray dryer was controlled to be 160° C., the outlet temperature was controlled to be 80° C., the spray pressure was controlled to be 0.4 MPa, and the feed rate was controlled to be 80 L / h. The premix was spray dried to obtain a spray-dried material.

[0071] 4) Heat treatment The spray-dried material was placed in a heat treatment device, heated to 240° C., heat-treated for 16 hours, and then cooled to obtain a heat-treated material.

[0072] 5) Modification treatment γ-Aminopropyltriethoxysilane was added to an ethanol aqueous solution with a volume concentration of 95%, and after stirring for 1.2 hours, the heat-treated material was continued to be added, and after stirring for 2 hours, a modified material was obtained.

[0073] The added weight of γ-aminopropyltriethoxysilane is 2.5% of the weight of the heat-treated material.

[0074] The weight of the ethanol aqueous solution is 1.9 times the weight of the heat-treated material.

[0075] 6) Preparation Phenolic resin and furan resin are added to anhydrous ethanol and stirred evenly, and the weight ratio of phenolic resin and furan resin is controlled to be 1:3, and the weight of anhydrous ethanol is 4 times the total weight of phenolic resin and furan resin; then, the modified material is added and stirred for 2 hours to obtain an adhesive.

[0076] The weight of the modified material is 35% of the total weight of the phenolic resin and the furan resin.

[0077] 2. Bonding treatment 1) Preprocessing According to the structural requirements of the porous graphite product, the porous graphite is cut into porous graphite blocks of predetermined sizes, and each of the porous graphite blocks can be spliced ​​to form a porous graphite product with a complex structure; then, the porous graphite blocks are ultrasonically cleaned with deionized water, with the ultrasonic frequency controlled at 40HKz, the ultrasonic cleaning temperature at 50°C, and the ultrasonic cleaning time at 20min.

[0078] 2) Coating and fixing After ultrasonic cleaning, the phenolic resin and epoxy resin were mixed and evenly coated on the bonding surface of the porous graphite block, and the coating thickness was controlled to be 0.8 mm. After coating, heat treatment was performed at 400°C for 6 hours. Then, the adhesive was evenly coated on the bonding surface of the porous graphite block, and the coating thickness was controlled to be 1.3 mm. After coating, the porous graphite blocks were spliced ​​according to the structural requirements of the porous graphite products (i.e., the bonding surfaces of adjacent porous graphite blocks were combined respectively), and a pressure of 5 MPa was applied to fix them to obtain a fixed body.

[0079] The weight ratio of the phenolic resin to the epoxy resin is 6:4.

[0080] 3. Sintering treatment The fixed body is placed in a vacuum sintering furnace, the vacuum degree is controlled at 50 Pa, the temperature is increased from room temperature to 200 ° C at a heating rate of 2 ° C / min, and then sintered at 200 ° C for 90 minutes; the temperature is increased from 200 ° C to 500 ° C at a heating rate of 2 ° C / min, and then sintered at 500 ° C for 180 minutes; the temperature is increased from 500 ° C to 950 ° C at a heating rate of 2 ° C / min, and then sintered for 120 minutes. After cooling, a porous graphite product with a complex structure is obtained.

[0081] Example 2 This embodiment provides a method for preparing a porous graphite product with a complex structure, and the specific steps are as follows: 1. Prepare adhesive 1) Raw material preparation Prepare the following raw materials according to subsequent production requirements: phenolic resin (solid content 50wt%), furan resin (solid content 50wt%), epoxy resin (solid content 60wt%), carbon powder (particle size 350 mesh), boron carbide (particle size 500 mesh), anhydrous ethanol, polyethylene glycol (PEG-1000), stearic acid, polyvinylpyrrolidone PVP, sodium lauryl sulfate SDS, and set aside.

[0082] 2) Raw material mixing Carbon powder, boron carbide, anhydrous ethanol, polyethylene glycol, stearic acid, polyvinyl pyrrolidone (PVP), and sodium lauryl sulfate (SDS) are uniformly mixed according to a predetermined weight ratio to obtain a premix. The specific mixing order is as follows: carbon powder and boron carbide are weighed and uniformly mixed in a weight ratio of 5:5 to obtain a composite powder; the composite excipients are then mixed with anhydrous ethanol, polyethylene glycol, stearic acid, polyvinyl pyrrolidone (PVP), and sodium lauryl sulfate (SDS), and the mixture is mixed using ultrasonic dispersion and mechanical stirring, with the ultrasonic frequency controlled at 34 kHz and the stirring rate at 2000 rpm, and the mixing process is performed for 45 minutes to obtain a premix.

[0083] Among them, the added amount of anhydrous ethanol is 43% of the weight of the composite powder.

[0084] The added amount of polyethylene glycol is 3.7% of the weight of the composite powder.

[0085] The added amount of stearic acid is 2.2% by weight of the composite powder.

[0086] The added amount of polyvinyl pyrrolidone (PVP) is 1.1% of the weight of the composite powder.

[0087] The addition amount of sodium lauryl sulfate SDS is 1.1% of the weight of the composite powder.

[0088] 3) Spray drying The inlet temperature of the spray dryer was controlled to be 170° C., the outlet temperature was controlled to be 90° C., the spray pressure was controlled to be 0.6 MPa, and the feed rate was controlled to be 88 L / h. The premix was spray dried to obtain a spray-dried material.

[0089] 4) Heat treatment The spray-dried material was placed in a heat treatment device, heated to 280° C., heat-treated for 14 hours, and then cooled to obtain a heat-treated material.

[0090] 5) Modification treatment γ-Aminopropyltriethoxysilane was added to an ethanol aqueous solution with a volume concentration of 95%, and after stirring for 1.75 hours, the heat-treated material was continued to be added, and after stirring for 2.5 hours, a modified material was obtained.

[0091] The added weight of γ-aminopropyltriethoxysilane is 2.8% of the weight of the heat-treated material.

[0092] The weight of the ethanol aqueous solution is 1.7 times the weight of the heat-treated material.

[0093] 6) Preparation Phenolic resin and furan resin were added to anhydrous ethanol and stirred evenly, and the weight ratio of phenolic resin and furan resin was controlled to be 2:2, and the weight of anhydrous ethanol was 5 times the total weight of phenolic resin and furan resin; then, the modified material was added and stirred for 2.5 hours to obtain an adhesive.

[0094] The weight of the modified material is 39% of the total weight of the phenolic resin and the furan resin.

[0095] 2. Bonding treatment 1) Preprocessing According to the structural requirements of the porous graphite product, the porous graphite is cut into porous graphite blocks of predetermined sizes, and each of the porous graphite blocks can be spliced ​​to form a porous graphite product with a complex structure; then, the porous graphite blocks are ultrasonically cleaned with deionized water, with the ultrasonic frequency controlled at 50HKz, the ultrasonic cleaning temperature at 60°C, and the ultrasonic cleaning time at 15 minutes.

[0096] 2) Coating and fixing After ultrasonic cleaning, the phenolic resin and epoxy resin were mixed and evenly coated on the bonding surface of the porous graphite block, and the coating thickness was controlled to be 0.8 mm. After coating, heat treatment was performed at 500°C for 7 hours. Then, the adhesive was evenly coated on the bonding surface of the porous graphite block, and the coating thickness was controlled to be 1.3 mm. After coating, the porous graphite blocks were spliced ​​according to the structural requirements of the porous graphite products (i.e., the bonding surfaces of adjacent porous graphite blocks were combined respectively), and a pressure of 6.5 MPa was applied to fix them to obtain a fixed body.

[0097] The weight ratio of the phenolic resin to the epoxy resin is 6:4.

[0098] 3. Sintering treatment The fixed body is placed in a vacuum sintering furnace, the vacuum degree is controlled at 70 Pa, the temperature is raised from room temperature to 200 ° C at a heating rate of 3 ° C / min, and then sintered at 200 ° C for 110 minutes; the temperature is raised from 200 ° C to 500 ° C at a heating rate of 3 ° C / min, and then sintered at 500 ° C for 200 minutes; the temperature is raised from 500 ° C to 1050 ° C at a heating rate of 3 ° C / min, and then sintered for 160 minutes. After cooling, a porous graphite product with a complex structure is obtained.

[0099] Example 3 This embodiment provides a method for preparing a porous graphite product with a complex structure, and the specific steps are as follows: 1. Prepare adhesive 1) Raw material preparation Prepare the following raw materials according to subsequent production requirements: phenolic resin (solid content 50wt%), furan resin (solid content 50wt%), epoxy resin (solid content 60wt%), carbon powder (particle size 350 mesh), boron carbide (particle size 500 mesh), anhydrous ethanol, polyethylene glycol (PEG-1000), stearic acid, polyvinylpyrrolidone PVP, sodium lauryl sulfate SDS, and set aside.

[0100] 2) Raw material mixing Carbon powder, boron carbide, anhydrous ethanol, polyethylene glycol, stearic acid, polyvinyl pyrrolidone (PVP), and sodium lauryl sulfate (SDS) are uniformly mixed according to a predetermined weight ratio to obtain a premix. The specific mixing order is as follows: carbon powder and boron carbide are weighed and uniformly mixed in a weight ratio of 6:4 to obtain a composite powder; the composite auxiliary material is then mixed with anhydrous ethanol, polyethylene glycol, stearic acid, polyvinyl pyrrolidone (PVP), and sodium lauryl sulfate (SDS), and then mixed using ultrasonic dispersion and mechanical stirring, with the ultrasonic frequency controlled at 50 kHz and the stirring rate at 2500 rpm, and the mixing process is carried out for 30 minutes to obtain a premix.

[0101] The added amount of anhydrous ethanol is 45% of the weight of the composite powder.

[0102] The added amount of polyethylene glycol is 3.9% of the weight of the composite powder.

[0103] The added amount of stearic acid is 2.5% of the weight of the composite powder.

[0104] The added amount of polyvinylpyrrolidone (PVP) is 1.3% of the weight of the composite powder.

[0105] The addition amount of sodium lauryl sulfate SDS is 1.3% of the weight of the composite powder.

[0106] 3) Spray drying The inlet temperature of the spray dryer was controlled to be 180° C., the outlet temperature was controlled to be 100° C., the spray pressure was controlled to be 0.8 MPa, and the feed rate was controlled to be 95 L / h. The premix was spray dried to obtain a spray-dried material.

[0107] 4) Heat treatment The spray-dried material was placed in a heat treatment device, heated to 30° C., kept heat-treated for 12 h, and then cooled to obtain a heat-treated material.

[0108] 5) Modification treatment γ-Aminopropyltriethoxysilane was added to an ethanol aqueous solution with a volume concentration of 95%, and after stirring for 2 hours, the heat-treated material was continued to be added, and after stirring for 3 hours, a modified material was obtained.

[0109] The added weight of γ-aminopropyltriethoxysilane is 3% of the weight of the heat-treated material.

[0110] The weight of the ethanol aqueous solution is 1.9 times the weight of the heat-treated material.

[0111] 6) Preparation Phenolic resin and furan resin are added to anhydrous ethanol and stirred evenly, and the weight ratio of phenolic resin and furan resin is controlled to be 3:1, and the weight of anhydrous ethanol is 6 times the total weight of phenolic resin and furan resin; then, the modified material is added and stirred for 3 hours to obtain an adhesive.

[0112] The weight of the modified material is 42% of the total weight of the phenolic resin and the furan resin.

[0113] 2. Bonding treatment 1) Preprocessing According to the structural requirements of the porous graphite product, the porous graphite is cut into porous graphite blocks of predetermined sizes, and each of the porous graphite blocks can be spliced ​​to form a porous graphite product with a complex structure; then, the porous graphite blocks are ultrasonically cleaned with deionized water, with the ultrasonic frequency controlled at 55HKz, the ultrasonic cleaning temperature at 65°C, and the ultrasonic cleaning time being 10 minutes.

[0114] 2) Coating and fixing After ultrasonic cleaning, the phenolic resin and epoxy resin were mixed and evenly coated on the bonding surface of the porous graphite block, and the coating thickness was controlled to be 0.8 mm. After coating, heat treatment was performed at 550°C for 8 hours. Then, the adhesive was evenly coated on the bonding surface of the porous graphite block, and the coating thickness was controlled to be 1.3 mm. After coating, the porous graphite blocks were spliced ​​according to the structural requirements of the porous graphite products (i.e., the bonding surfaces of adjacent porous graphite blocks were combined respectively), and a pressure of 8 MPa was applied to fix them to obtain a fixed body.

[0115] The weight ratio of the phenolic resin to the epoxy resin is 6:4.

[0116] 3. Sintering treatment The fixed body is placed in a vacuum sintering furnace, the vacuum degree is controlled at 100 Pa, the temperature is raised from room temperature to 200 ° C at a heating rate of 4 ° C / min, and then sintered at 200 ° C for 130 minutes; the temperature is raised from 200 ° C to 500 ° C at a heating rate of 4 ° C / min, and then sintered at 500 ° C for 240 minutes; the temperature is raised from 500 ° C to 1150 ° C at a heating rate of 4 ° C / min, and then sintered for 200 minutes. After cooling, a porous graphite product with a complex structure is obtained.

[0117] Comparative Example 1 The method for preparing porous graphite products with complex structures in Comparative Example 1 adopts the technical solution of Example 2, except that: in the step of preparing the adhesive, the raw material mixing, spray drying, heat treatment, and modification treatment are omitted, and carbon powder and boron carbide with a weight ratio of 1:1 are directly used in the preparation to replace the modified material, and are evenly mixed with phenolic resin and furan resin to prepare the adhesive.

[0118] The total weight of the carbon powder and the boron carbide is 15% of the total weight of the phenolic resin and the furan resin.

[0119] Comparative Example 2 The method for preparing a porous graphite product with a complex structure in Comparative Example 2 adopts the technical solution of Example 2, except that: 1) in the step of preparing the adhesive, the addition of γ-aminopropyltriethoxysilane is omitted during the modification process; 2) in the bonding process step, the coating of phenolic resin and epoxy resin is omitted during the coating and fixing process, and the adhesive is directly applied to the bonding surface of the porous graphite block and then fixed.

[0120] Comparative Example 3 The method for preparing a porous graphite product with a complex structure in Comparative Example 3 adopts the technical solution of Example 2, except that: in the sintering treatment step, the temperature is directly raised to 1100°C at a heating rate of 3°C / min, and then sintered at 1100°C for 300 minutes and cooled to obtain a porous graphite product with a complex structure.

[0121] The shear strength of the bonding joints of the porous graphite products prepared using the methods of Examples 1-3 and Comparative Examples 1-3 was tested. Furthermore, each porous graphite product was placed in an aerobic environment at 1000°C for 1000 hours (simulating a long-term high-temperature aerobic corrosion environment), and then the shear strength of the bonding joints of each porous graphite product was tested. The specific results are shown in the following table:

[0122] It can be seen that the method for preparing a porous graphite product with a complex structure of the present invention comprises the following steps: firstly, carbon powder, boron carbide, polyethylene glycol, stearic acid, polyvinyl pyrrolidone and sodium lauryl sulfate are mixed to prepare a premix, and then the premix is ​​spray-dried and heat-treated to obtain a heat-treated material; the heat-treated material is modified with γ-aminopropyltriethoxysilane to obtain a modified material; the modified material is uniformly mixed with phenolic resin, furan resin and anhydrous ethanol to obtain an adhesive; and then, the bonding surface of the porous graphite block is coated with a mixture of phenolic resin and epoxy resin and the adhesive in sequence, and then the premix is ​​sintered. The porous graphite products with complex structures are produced by the above-mentioned various treatment methods (such as spray drying, heat treatment, coating, sintering, etc.) can be realized by using existing production equipment and production processes. The porous graphite products with complex structures can be divided into multiple porous graphite blocks that can be bonded together in a building block manner with specific adhesives and process methods to form the final required complex structure. This can effectively break through the limitations of traditional mold forming and its process. Porous graphite products with various complex structures can be flexibly prepared according to demand.

[0123] At the same time, in order to improve the matching of porous graphite materials and adhesives, carbon powder, boron carbide, phenolic resin and furan resin that are highly compatible with the porous graphite matrix are specifically selected to reduce the internal stress at the bonding interface of the porous graphite and improve the matching; and the heat-treated material is modified with γ-aminopropyltriethoxysilane to improve the interface bonding between the modified material and the phenolic resin and furan resin, ensuring that it is converted into a high-strength glassy carbon phase / reinforced particle combination during subsequent sintering, thereby greatly improving the shear strength of the bonding point of the porous graphite block.

[0124] Furthermore, during the bonding process, phenolic resin and epoxy resin are used as a primer to fully infiltrate and penetrate into the tiny pores on the surface of the porous graphite. After heat treatment and curing, a transition layer is formed that is well bonded to the porous graphite matrix, thereby increasing the effective bonding surface area. Then, an adhesive is applied to ensure that the adhesive is efficiently bonded to the porous graphite surface. Finally, the fixed body is sintered, and the material at the bonding surface is completely carbonized to form a glassy carbon network composited with carbon powder and boron carbide reinforcing components, thereby further enhancing the interface bonding, improving the shear strength of the material, and effectively improving the long-term stability and corrosion resistance of the porous graphite products in high-temperature aerobic environments.

[0125] Unless otherwise specified, all percentages used in the present invention are by weight.

[0126] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing a porous graphite product with a complex structure, characterized in that: The method comprises the following steps: preparing an adhesive, bonding treatment, and sintering treatment; The method for preparing the adhesive comprises: uniformly mixing carbon powder, boron carbide, anhydrous ethanol, polyethylene glycol, stearic acid, polyvinyl pyrrolidone, and sodium lauryl sulfate to obtain a premix; spray-drying and heat-treating the premix to obtain a heat-treated material; adding the heat-treated material into an ethanol aqueous solution dispersed with γ-aminopropyltriethoxysilane, stirring and modifying the mixture to obtain a modified material; and uniformly mixing the modified material with a phenolic resin, a furan resin, and anhydrous ethanol to obtain an adhesive. The bonding treatment method comprises: applying a mixture of phenolic resin and epoxy resin to the bonding surface of the porous graphite block; applying an adhesive to the bonding surface of the porous graphite block after heat treatment; combining the bonding surfaces of two or more porous graphite blocks and applying pressure to fix them to obtain a fixed body; The fixed body is sintered to obtain a porous graphite product with a complex structure.

2. The method for preparing a porous graphite product with a complex structure according to claim 1, wherein: In the preparation of the premix, the weight ratio of carbon powder to boron carbide is 3-7:3-7; The weight of anhydrous ethanol is 30-50% of the total weight of carbon powder and boron carbide; The weight of polyethylene glycol is 0.1-5% of the total weight of carbon powder and boron carbide; The weight of stearic acid is 0.1-3% of the total weight of carbon powder and boron carbide; The weight of polyvinyl pyrrolidone is 0.1-2% of the total weight of carbon powder and boron carbide; The weight of sodium lauryl sulfate is 0.1-2% of the total weight of the carbon powder and boron carbide.

3. The method for preparing a porous graphite product with a complex structure according to claim 1, wherein: In the preparation of the adhesive, the inlet temperature of the spray drying is controlled to be 150-180° C., the outlet temperature is controlled to be 80-100° C., the spray pressure is controlled to be 0.1-1 MPa, and the feed rate is controlled to be 70-100 L / h.

4. The method for preparing a porous graphite product with a complex structure according to claim 1, wherein: In the preparation of the adhesive, the heat treatment temperature is 100-400° C., and the heat treatment time is 10-20 hours.

5. The method for preparing a porous graphite product with a complex structure according to claim 1, wherein: In the preparation of the adhesive, the weight of γ-aminopropyltriethoxysilane is 0.5-3% of the weight of the heat-treated material; The weight of the ethanol aqueous solution is 1.6-1.9 times the weight of the heat-treated material; The volume concentration of the ethanol aqueous solution is 90-95%.

6. The method for preparing a porous graphite product with a complex structure according to claim 1, wherein: In the preparation of the adhesive, the solid content of the phenolic resin is 40-60wt%, and the solid content of the furan resin is 40-60wt%; The weight ratio of phenolic resin to furan resin is 1-3:1-3; The weight of the modified material is 10-50% of the total weight of the phenolic resin and furan resin; The weight of anhydrous ethanol is 2-10 times the total weight of the phenolic resin and the furan resin.

7. The method for preparing a porous graphite product with a complex structure according to claim 1, wherein: In the bonding process, before the phenolic resin and the epoxy resin are mixed and applied to the bonding surface of the porous graphite block, the porous graphite block is first ultrasonically cleaned with deionized water; The frequency of the ultrasonic cleaning is 40-60HKz, and the temperature of the ultrasonic cleaning is 40-70°C.

8. The method for preparing a porous graphite product with a complex structure according to claim 1, wherein: In the bonding process, the solid content of the phenolic resin is 40-60wt%, and the solid content of the epoxy resin is 50-60wt%; The weight ratio of phenolic resin to epoxy resin is 5-7:3-5; The coating thickness of the resin on the bonding surface of the porous graphite block is 0.5-1mm; The coating thickness of the adhesive on the bonding surface of the porous graphite block is 0.5-2 mm.

9. The method for preparing a porous graphite product with a complex structure according to claim 1, wherein: In the bonding process, the heat treatment temperature is 300-700°C and the heat treatment time is 5-100h; The fixed applied pressure is 5-10 MPa.

10. The method for preparing a porous graphite product with a complex structure according to claim 1, wherein: The sintering method is as follows: the fixed body is heated from room temperature to 200°C at a heating rate of 1-5°C / min in a vacuum environment of 5-100 Pa, and then sintered at this temperature for 30-200 minutes; the temperature is further heated from 200°C to 500°C, and then sintered at this temperature for 30-300 minutes; the temperature is further heated from 500°C to 800-1200°C, and then sintered at this temperature for 60-300 minutes to complete the sintering process.

Images