Ultra-high-strength carbon material and preparation method thereof

Abstract

The present invention discloses an ultra-high-strength carbon material and a preparation method thereof, which belongs to the field of carbon material technology. The preparation method comprises the following steps: reinforcing particles, acrylamide, water-soluble sugars, N,N'-methylenebisacrylamide, an initiator and a catalyst are added to deionized water and mixed evenly, and then dried, heat-treated, crushed and ball-milled in sequence to obtain a composite powder; the composite powder is molded and carbonized in sequence to obtain the ultra-high-strength carbon material. The present invention significantly simplifies the production process of graphite block carbon materials by adopting an innovative two-step preparation process, and effectively overcomes the problems of complex process, long production cycle, high raw material cost and difficult control of microstructure in the prior art. The strategy of combining sugar-polyacrylamide hydrogel technology with reinforcing particles is used to greatly improve the carbon yield and reduce the carbon loss caused by gas release during the carbonization process, thereby optimizing the microstructure of the material and improving its mechanical properties, including key indicators such as compressive and flexural strength.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon materials, and in particular relates to an ultra-high-strength carbon material and a preparation method thereof. Background Art

[0002] Carbon (graphite) materials occupy a vital position in industrial applications due to their exceptional electrical and thermal conductivity, high mechanical strength, low coefficient of thermal expansion, high-temperature resistance, and excellent thermal stability. These properties have led to the widespread application of isotropic graphite in fields such as metallurgy, chemical engineering, electronics, and the nuclear industry. It plays an irreplaceable role in high-tech fields such as high-end anti-friction materials, military industry, aerospace, semiconductor manufacturing, nuclear graphite for high-temperature gas-cooled reactors, and ultra-high power electrodes.

[0003] Existing isotropic graphite preparation methods mainly include traditional methods and self-sintering methods. The traditional method uses petroleum coke, pitch coke or anthracite as raw materials, grinds them into fine powder as aggregate, adds binders such as coal tar or artificial resin, and after isostatic pressing, obtains the finished product by high-temperature roasting, repeated impregnation and graphitization. Although this process is mature, it has the problems of long production cycle and complex process, and because the product structure is mostly heterogeneous structure, isotropy is poor, which limits the improvement of its mechanical properties. The self-sintering method uses powder with self-sintering properties (such as raw petroleum coke powder and mesophase pitch-based powder, etc.), does not use binders, and prepares graphite materials by high-temperature roasting and graphitization after compression molding. Although this method reduces the use of binders, it has high performance requirements for the raw material powder and usually needs to be modified, resulting in increased manufacturing costs. In addition, the self-sintering method is prone to problems such as excessive shrinkage and cracks in the finished product during the production process, resulting in a low yield rate and complex process operations.

[0004] Therefore, there is an urgent need to provide a new preparation method to prepare carbon materials with excellent mechanical properties. Summary of the Invention

[0005] In order to solve the problems of complex preparation process, long cycle, high cost, great difficulty in microstructure control and poor mechanical properties of existing graphite block materials. The present invention proposes an ultra-high-strength carbon material and its preparation method, that is, the use of sugar-polyacrylamide hydrogel technology and the introduction of reinforcing particles, combined with the process of high-temperature carbonization and graphitization after molding or isostatic pressing to prepare ultra-high-strength carbon materials, wherein the sugar-polyacrylamide hydrogel method can significantly improve the carbon yield and effectively reduce the carbon loss of sugar during the heat treatment process, while the addition of reinforcing particles helps to optimize the microstructure of the material and improve the mechanical properties of the material. This method not only significantly shortens the preparation cycle and reduces production costs, but also solves the bottleneck of traditional methods in microstructure design, successfully prepares high-strength and dense carbon (graphite) materials, and provides technical support for its further promotion in industrial applications. It is particularly suitable for the development of high-strength and low-cost carbon materials.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] One of the technical solutions of the present invention:

[0008] A method for preparing an ultra-high-strength carbon material comprises the following steps:

[0009] The reinforcing particles, acrylamide, water-soluble sugars, N,N'-methylenebisacrylamide, an initiator, and a catalyst are added to deionized water and mixed evenly, and then dried, heat-treated, crushed, and ball-milled in sequence to obtain a composite powder of the reinforcing particles coated with the sugar-polyacrylamide hydrogel (binder);

[0010] The composite powder is formed and then carbonized to prepare the ultra-high-strength carbon material.

[0011] Preferably, based on the sum of the weight percentages of the acrylamide, water-soluble sugar, N,N'-methylenebisacrylamide and deionized water as 100%, the acrylamide: water-soluble sugar: N,N'-methylenebisacrylamide = 1-30%: 5-60%: 0.05-3%, with the remainder being water.

[0012] Preferably, the added amount of the reinforcing particles is 20% to 300% of the total weight of the acrylamide, water-soluble sugar, N,N'-methylenebisacrylamide and deionized water.

[0013] Preferably, the preparation process of the reinforced particles is:

[0014] acrylamide, water-soluble sugars and N,N'-methylenebisacrylamide are mixed and dissolved in deionized water, and stirred to form a uniform solution; the solution is then gelled at 50-200°C and dried to obtain a hydrogel;

[0015] heat-treating the hydrogel in a muffle furnace to obtain a pretreated product;

[0016] Carrying out carbonization treatment on the pretreated product under inert atmosphere (vacuum, argon or nitrogen) to obtain a carbonized product;

[0017] The carbonized product is pulverized and then ball-milled in a ball mill to obtain carbonized powder (reinforced particles).

[0018] More preferably, based on weight percentage, the acrylamide: water-soluble sugar: N,N'-methylenebisacrylamide = (1-30%): (5-60%): (0.05-3%), and the balance is deionized water.

[0019] More preferably, based on weight percentage, the ratio of acrylamide: water-soluble sugar: N,N'-methylenebisacrylamide is 7.39%: 24.65%: 0.18%.

[0020] More preferably, the water-soluble sugars include one or more of glucose, fructose, galactose, maltose, sucrose, lactose or oligofructose.

[0021] More preferably, the conditions during the heat treatment are:

[0022] The temperature is raised to 140-350°C at a heating rate of 0.1-20°C / min, and then kept at this temperature for 0.5-30h; wherein the heating mode is direct heating or step-by-step heating.

[0023] More preferably, the conditions during the carbonization process are:

[0024] The temperature is raised to 500-1600°C at a heating rate of 1-20°C / min, and then kept at this temperature for 0.5-30h; wherein the heating mode is direct heating or step-by-step heating.

[0025] More preferably, the conditions during the ball milling process are:

[0026] The ball-to-material ratio is 1-20:1, the ball mill speed is 100-600r / min, and the ball milling time is 6-48h.

[0027] Preferably, the initiator is a 10% by mass aqueous solution of ammonium persulfate, and the amount thereof added is 0.5% to 3% of the total mass of acrylamide, water-soluble sugars, N,N'-methylenebisacrylamide and deionized water; and / or

[0028] The catalyst is a triethanolamine aqueous solution with a mass fraction of 10%, and the added amount thereof is 0.5%-3% of the total mass of acrylamide, water-soluble sugars, N,N'-methylenebisacrylamide and deionized water.

[0029] Preferably, the forming is performed by molding or isostatic pressing.

[0030] Preferably, the conditions during the molding process are:

[0031] The process is carried out under conditions of a pressure of 10-600 MPa and a temperature of 120-900° C. and is kept warm for 0.5-6 hours to obtain a block-shaped green body.

[0032] Preferably, the conditions of the carbonization process are:

[0033] In an inert atmosphere, the temperature is increased to 1000-3000°C at a heating rate of 1-20°C / min, and then kept at this temperature for 0.5-24 hours; the heating mode is direct heating or step-by-step heating.

[0034] More preferably, during the carbonization process:

[0035] When the temperature is raised to 1000-1600°C, a high-strength isotropic nanocrystalline / amorphous carbon bulk carbon material is obtained;

[0036] When the temperature is raised to 1800-2400°C, a high-strength isotropic three-dimensional network graphene / amorphous carbon block carbon material is obtained;

[0037] When the temperature is raised to 2600-3000℃, a high-strength isotropic graphite material is obtained.

[0038] The second technical solution of the present invention:

[0039] The ultra-high-strength carbon material prepared by the above preparation method.

[0040] Compared with the prior art, the present invention has the following advantages and technical effects:

[0041] The present invention significantly simplifies the production process of graphite block carbon materials by adopting an innovative two-step preparation process, effectively overcoming the problems existing in the prior art such as complex process, long production cycle, high raw material cost and difficult to control microstructure. By utilizing the strategy of combining sugar-polyacrylamide hydrogel technology with reinforcing particles, the carbon yield is greatly improved, the carbon loss caused by gas release during the carbonization process is reduced, thereby optimizing the microstructure of the material and improving its key indicators such as flexural strength. At the same time, the simplified process of the method significantly reduces production cost and time cost, and improves the feasibility and economic benefits of industrial production. The prepared high-strength carbon material shows significant application prospects in high-tech fields such as aerospace, electronics, and metallurgy, which not only promotes the technological development of graphite-based materials, but also provides a practical solution for the development of a new generation of high-performance carbon materials. Therefore, the preparation method of an ultra-high-strength carbon material provided by the present invention will bring obvious social benefits and meet the growing market demand for high-strength, low-cost carbon materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of this application. The exemplary embodiments and descriptions of this application are intended to explain this application and do not constitute an improper limitation on this application. In the accompanying drawings:

[0043] Figure 1 This is a microstructure diagram of the nanocrystalline / amorphous carbon bulk carbon material obtained in Example 1;

[0044] Figure 2 3D network graphene / amorphous carbon composite material microstructure diagram obtained in Example 2;

[0045] Figure 3 This is a microstructure diagram of the graphite bulk carbon material obtained in Example 3;

[0046] Figure 4 This is a graph showing the bending strength of the carbon materials prepared in Examples 1-3. DETAILED DESCRIPTION

[0047] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0048] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0049] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0050] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0051] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0052] The present invention selects acrylamide and water-soluble sugar substances as starting materials and adopts a two-step method to prepare ultra-high-strength carbon (graphite) materials. The first step is to prepare reinforcing particles; the second step uses the reinforcing particles as aggregate and sugar-polyacrylamide hydrogel as a binder to prepare ultra-high-strength carbon (graphite) materials. The preparation process of ultra-high-strength carbon materials is as follows:

[0053] Step 1: Preparation of reinforced particles:

[0054] Acrylamide, a water-soluble sugar, and N,N'-methylenebisacrylamide are weighed in weight proportions of 1-30%, 5-60%, and 0.05-3%, respectively, and deionized water is added as the remainder. The amount of deionized water can be adjusted according to specific needs to control the relative proportions of the other raw materials in the system.

[0055] The sample preparation process is as follows: First, acrylamide, a water-soluble sugar, and N,N'-methylenebisacrylamide are mixed and dissolved in deionized water and stirred to form a homogeneous solution. This solution is then gelled and dried at 50-200°C to obtain a hydrogel. The hydrogel is then heat-treated in a muffle furnace at 140-350°C at a heating rate of 0.1-20°C / min, using either direct or step-wise heating. After reaching the target temperature, the temperature is maintained for 0.5-30 hours to obtain a pretreated product. The pretreated product is further carbonized under vacuum / argon / nitrogen conditions at a heating rate of 1-20°C / min, using either direct or step-wise heating. After reaching the target temperature of 500-1600°C, the temperature is maintained for 0.5-30 hours to obtain a carbonized product. The carbonized product is crushed and then ball-milled in a ball mill with a ball-to-material ratio of 1 to 20:1, a ball-milling speed of 100 to 600 r / min, and a ball-milling time of 6 to 48 hours. Carbonized powder is obtained after ball milling, and the carbonized powder is used as the reinforcing particles in the second step.

[0056] The second step is to prepare ultra-high-strength carbon (graphite) materials using reinforced particles as aggregate and sugar-polyacrylamide hydrogel as binder:

[0057] First, prepare a sufficient amount of initiator (a 10% ammonium persulfate aqueous solution) and catalyst (a 10% triethanolamine aqueous solution) for use. Then, weigh acrylamide, a water-soluble sugar, and N,N'-methylenebisacrylamide in weight proportions of 1-30%, 5-60%, and 0.05-3%, respectively, and add deionized water to make up the total to 100%. The amount of deionized water can be adjusted according to specific needs to control the relative proportions of other raw materials in the system. The amount of reinforcing particles added accounts for 20% to 300% of the mass of the above solution.

[0058] Next, acrylamide, a water-soluble sugar, N,N'-methylenebisacrylamide, and reinforcing phase particles are mixed in deionized water. An initiator (0.5% to 3% by weight) is added dropwise, and the mixture is stirred to form a uniformly dispersed solution. A catalyst (0.5% to 3% by weight) is then added dropwise to rapidly gel the solution.

[0059] The resulting gel is transferred to a forced-air oven and dried at 60-200°C for 12-48 hours to remove free water. The hydrogel is then heat-treated in a muffle furnace at 120-350°C at a heating rate of 0.1-20°C / min, either directly or in a step-wise, soaking mode. After reaching the target temperature, the temperature is maintained for 0.5-30 hours to obtain a pretreated product. The pretreated product is then pulverized and ball-milled in a ball mill at a ball-to-material ratio of 1-20:1, a speed of 100-600 rpm, and a milling time of 6-48 hours to obtain a composite powder containing binder-encapsulated reinforcing particles.

[0060] The composite powder is kept warm at a pressure of 10 to 600 MPa and a temperature of 120 to 900° C. for 0.5 to 6 hours to obtain a block-shaped green body.

[0061] The green body obtained above is subjected to carbonization treatment under protective atmosphere conditions such as vacuum / N2 / Ar, with a heating rate of 1-20°C / min, a heating mode of direct heating or step-by-step heating, a target temperature of 1000-1600°C, and a holding time of 0.5-6h to obtain a high-strength isotropic nanocrystalline / amorphous carbon bulk carbon material; and / or

[0062] The green body obtained above is subjected to carbonization treatment under protective atmosphere conditions such as vacuum / N2 / Ar, with a heating rate of 1-20°C / min, a heating mode of direct heating or step-by-step heating, a target temperature of 1800-2400°C, and a holding time of 0.5-6h to obtain a high-strength isotropic three-dimensional network graphene / amorphous carbon block carbon material; and / or

[0063] The green body obtained above is carbonized under protective atmosphere conditions such as vacuum / N2 / Ar, with a heating rate of 1 to 20°C / min, a heating mode of direct heating or step-by-step heating, a target temperature of 2600 to 3000°C, and a holding time of 0.5 to 6h to obtain a high-strength isotropic graphite material.

[0064] In some preferred embodiments, the water-soluble sugars include one or more of glucose, fructose, galactose, maltose, sucrose, and lactose.

[0065] In some preferred embodiments, in the first step, acrylamide, water-soluble sugar, and N,N'-methylenebisacrylamide are respectively 7.39%, 24.65%, and 0.18% by weight; the balance is deionized water.

[0066] In some preferred embodiments, the preparation process of the ultra-high strength carbon material is as follows:

[0067] The first step is to prepare the reinforced particles:

[0068] Acrylamide, water-soluble sugars, and N,N'-methylenebisacrylamide were weighed in proportions of 7.39%, 24.65%, and 0.18% by weight, respectively, and deionized water was added as the remainder, resulting in a weight ratio of 67.78%. The amount of deionized water can be adjusted according to specific needs to control the relative proportions of other raw materials in the system. The sample preparation process is as follows: First, acrylamide, water-soluble sugars, and N,N'-methylenebisacrylamide were mixed and dissolved in deionized water and stirred to form a uniform solution. The solution was then gelled and dried at 80°C to obtain a hydrogel. The hydrogel was then heat-treated in a muffle furnace at 220°C with a heating rate of 0.5°C / min. The heating mode was either direct heating or step-by-step heating. After reaching the target temperature, the temperature was maintained for 2 hours, and the pretreated product was obtained, which was recorded as PG-220. PG-220 samples were further carbonized under vacuum / argon / nitrogen conditions at a heating rate of 4°C / min, either directly or in a step-wise, soaking mode. After reaching the target temperature of 1100°C, the temperature was maintained for 2 hours. The resulting carbonized product, designated PG-1100, was crushed and then milled in a ball mill with a ball-to-material ratio of 3:1, a speed of 200 rpm, and a milling time of 16 hours. This carbonized powder was used as the reinforcement particles in the second step.

[0069] The second step is to prepare ultra-high-strength carbon (graphite) materials using reinforced particles as aggregate and sugar-polyacrylamide hydrogel as binder:

[0070] First, sufficient amounts of an initiator (a 10% by mass aqueous solution of ammonium persulfate) and a catalyst (a 10% by mass aqueous solution of triethanolamine) were prepared for use.

[0071] Acrylamide, a water-soluble sugar, and N,N'-methylenebisacrylamide were weighed in proportions of 7.39%, 24.65%, and 0.18% by weight, respectively, with deionized water added as the remainder. The amount of deionized water can be adjusted to control the relative proportions of the other raw materials in the system. The reinforcing particles were added in an amount that accounted for 50% of the mass of the solution.

[0072] The sample preparation process is as follows: First, acrylamide, water-soluble sugars, N,N'-methylenebisacrylamide, and reinforcing phase particles are mixed and dissolved in deionized water. An initiator (a 10% ammonium persulfate aqueous solution) is added dropwise at a concentration of 1% of the total weight of the solution and stirred to form a uniformly dispersed solution. Then, a catalyst (a 10% triethanolamine aqueous solution) is added dropwise at a concentration of 1% of the total weight of the solution, causing the solution to gel rapidly.

[0073] The resulting gel was transferred to a forced-air oven and dried at 120°C for 24 hours to remove free water. The hydrogel was then heat-treated in a muffle furnace at 220°C at a heating rate of 0.5°C / min, either directly or in a step-wise, heat-maintained manner. After reaching the target temperature, the temperature was maintained for 2 hours. The resulting pretreated product, designated PG-220, was then crushed and milled in a ball mill with a ball-to-material ratio of 3:1, a speed of 200 r / min, and a milling time of 16 hours. This resulted in a composite powder containing binder-encapsulated reinforcing particles.

[0074] The composite powder was kept at a pressure of 200 MPa and a temperature of 500° C. for 2 hours to obtain a block-shaped green body.

[0075] 1. The green body obtained above was carbonized under vacuum / N2 / Ar protective atmosphere conditions, with a heating rate of 4°C / min, a heating mode of direct heating or step-by-step heating, a target temperature of 1100°C, and a holding time of 2h to obtain a high-strength isotropic nanocrystalline / amorphous carbon bulk carbon material.

[0076] 2. The green body obtained above is carbonized under protective atmosphere conditions such as vacuum / N2 / Ar, with a heating rate of 4°C / min, a heating mode of direct heating or step-by-step heating, a target temperature of 2400°C, and a holding time of 2h to obtain a high-strength isotropic three-dimensional network graphene / amorphous carbon block carbon material.

[0077] 3. The green body obtained above is carbonized under protective atmosphere conditions such as vacuum / N2 / Ar, with a heating rate of 4°C / min, a heating mode of direct heating or step-by-step heating, a target temperature of 2800°C, and a holding time of 2h to obtain a high-strength isotropic graphite material.

[0078] Unless otherwise specified, the "room temperature" in the present invention refers to 20-30°C.

[0079] The "parts" described in the present invention, unless otherwise specified, refer to parts by mass.

[0080] The raw materials used in the present invention are all purchased from the market.

[0081] The technical solution of the present invention is further illustrated by the following examples.

[0082] Example 1

[0083] Ultra-high strength carbon (graphite) materials are prepared using a two-step method. The specific process is as follows:

[0084] (1) Preparation of reinforced particles:

[0085] Take 73.9g of acrylamide, 246.5g of glucose and 1.8g of N,N'-methylenebisacrylamide, and 677.8mL of deionized water. Dissolve all raw materials in deionized water and stir until a uniform and transparent solution is obtained. The solution is gelled at 80°C and dried for 24 hours to obtain a hydrogel. Subsequently, the hydrogel is heated to 220°C in a muffle furnace at a heating rate of 0.5°C / min and kept warm for 2 hours to obtain the pretreated product PG-220. The PG-220 sample is heated to 1100°C at 4°C / min in an argon environment and kept warm for 2 hours to obtain the carbonized product PG-1100. The PG-1100 sample is crushed and ball milled in a ball mill at a ball-to-material ratio of 3:1 and a speed of 200r / min for 16 hours to obtain reinforced particle carbonized powder.

[0086] (2) Preparation of ultra-high strength carbon (graphite) materials:

[0087] Prepare sufficient amounts of initiator (10% ammonium persulfate solution) and catalyst (10% triethanolamine solution). Dissolve 6g acrylamide, 20g glucose, 0.15g N,N'-methylenebisacrylamide, 1.5mL initiator, 41g reinforcing particles, and 55mL deionized water in deionized water. Stir until a homogeneous solution forms.

[0088] After 3 mL of the catalyst was added dropwise to the mixed solution, the solution quickly gelled. The resulting gel was dried at 120°C for 24 hours. The sample was then transferred to a muffle furnace and heated to 220°C at a rate of 0.5°C / min for 2 hours to obtain a pretreated sample. The pretreated sample was then pulverized and ball milled in a ball mill at a speed of 200 rpm for 16 hours at a 3:1 ball-to-material ratio to obtain a composite powder containing binder-encapsulated reinforcing particles.

[0089] The composite powder was poured into a mold, a pressure of 200 MPa was applied, and the mold was kept at 500 ° C for 2 hours for hot pressing to obtain a bulk green body. The green body was heated to 1100 ° C in an argon environment at a heating rate of 4 ° C / min and kept at this temperature for 2 hours to obtain a high-strength isotropic nanocrystalline / amorphous carbon bulk carbon material. Transmission electron microscopy images are shown in Figure 1 ; Its flexural strength is 133MPa, see Figure 4 Middle 1#.

[0090] Example 2

[0091] Ultra-high strength carbon (graphite) materials are prepared using a two-step method. The specific process is as follows:

[0092] (1) Preparation of reinforced particles:

[0093] Take 73.9g of acrylamide, 246.5g of fructose, 1.8g of N,N'-methylenebisacrylamide, and 677.8mL of deionized water. Dissolve all raw materials in deionized water and stir until a uniform, transparent solution is obtained. The solution is gelled at 80°C and dried for 24 hours to obtain a hydrogel. Subsequently, the hydrogel is heated to 220°C in a muffle furnace at a heating rate of 0.5°C / min and kept warm for 2 hours to obtain the pretreated product PG-220. The PG-220 sample is heated to 900°C at a rate of 4°C / min in an argon environment and kept warm for 2 hours to obtain the carbonized product PG-900. The PG-900 sample is crushed and ball milled in a ball mill at a ball-to-material ratio of 3:1 and a speed of 200r / min for 16 hours to obtain a reinforced particle carbonized powder.

[0094] (2) Preparation of ultra-high strength carbon (graphite) materials:

[0095] Prepare sufficient amounts of initiator (a 10% ammonium persulfate aqueous solution) and catalyst (a 10% triethanolamine aqueous solution) for use. Dissolve 6g acrylamide, 20g fructose, 0.15g N,N'-methylenebisacrylamide, 1.5mL of initiator, 41g of reinforcing particles, and 55mL of deionized water in deionized water and stir until a homogeneous solution forms.

[0096] After 3 mL of the catalyst was added dropwise to the mixed solution, the solution quickly gelled. The resulting gel was dried at 120°C for 24 hours. The sample was then transferred to a muffle furnace and heated to 220°C at a rate of 0.5°C / min for 2 hours to obtain a pretreated sample. The pretreated sample was then pulverized and ball milled in a ball mill at a speed of 200 rpm for 16 hours at a 3:1 ball-to-material ratio to obtain a composite powder containing binder-encapsulated reinforcing particles.

[0097] The composite powder was poured into a mold, a pressure of 100 MPa was applied, and the mold was kept at 400°C for 2 hours for hot pressing to obtain a block green body. The green body was heated to 2400°C in an argon environment at a heating rate of 2°C / min and kept at this temperature for 3 hours to obtain a high-strength three-dimensional network graphene / amorphous carbon composite material. Transmission electron microscopy images are shown in Figure 2 ; flexural strength is 111MPa, see Figure 4 Middle 2#.

[0098] Example 3

[0099] The present invention adopts a two-step method to prepare ultra-high strength carbon (graphite) material, and the specific process is as follows:

[0100] (1) Preparation of reinforced particles:

[0101] Take 73.9g of acrylamide, 246.5g of sucrose, 1.8g of N,N'-methylenebisacrylamide, and 677.8mL of deionized water. Dissolve all raw materials in deionized water and stir until a uniform, transparent solution is obtained. The solution is gelled at 80°C and dried for 24 hours to obtain a hydrogel. Subsequently, the hydrogel is heated to 220°C in a muffle furnace at a heating rate of 0.5°C / min and kept warm for 2 hours to obtain the pretreated product PG-220. The PG-220 sample is heated to 1400°C at a rate of 4°C / min in an argon environment and kept warm for 2 hours to obtain the carbonized product PG-1400. The PG-1400 sample is crushed and ball milled in a ball mill at a ball-to-material ratio of 3:1 and a speed of 200r / min for 16 hours to obtain a reinforced particle carbonized powder.

[0102] (2) Preparation of ultra-high strength carbon (graphite) materials:

[0103] Prepare sufficient amounts of initiator (a 10% ammonium persulfate aqueous solution) and catalyst (a 10% triethanolamine aqueous solution) for use. Dissolve 6g acrylamide, 20g sucrose, 0.15g N,N'-methylenebisacrylamide, 1.5mL of initiator, 41g of reinforcing particles, and 55mL of deionized water in deionized water and stir until a homogeneous solution forms.

[0104] After 3 mL of the catalyst was added dropwise to the mixed solution, the solution quickly gelled. The resulting gel was dried at 120°C for 24 hours. The sample was then transferred to a muffle furnace and heated to 220°C at a rate of 0.5°C / min for 2 hours to obtain a pretreated sample. The pretreated sample was then pulverized and ball milled in a ball mill at a speed of 200 rpm for 16 hours at a 3:1 ball-to-material ratio to obtain a composite powder containing binder-encapsulated reinforcing particles.

[0105] The composite powder was poured into a mold, a pressure of 60 MPa was applied, and the temperature was kept at 600 ° C for 2 hours for hot pressing to obtain a block green body. The green body was heated to 2800 ° C in an argon environment at a heating rate of 2 ° C / min and kept at this temperature for 3 hours to obtain a high-strength isotropic graphite material. Transmission electron microscopy is shown in Figure 3 ; flexural strength is 71MPa, see Figure 4 Middle 3#.

[0106] Comparative Example 1

[0107] This comparative example adopts the preparation process of CN 115849362A to prepare carbon material, and the specific steps are:

[0108] (1) Step 1: Preparation of mixed solution, initiation of gelation and preliminary dehydration:

[0109] 1.2 g of analytically pure N,N'-methylenebisacrylamide was weighed and placed in a beaker. 90 g of deionized water was added and stirred thoroughly to dissolve and clarify. 180 g of analytically pure glucose monohydrate was slowly added while stirring in a 60°C water bath. After dissolving until clear, the mixture was naturally cooled to 40°C, and 36 g of analytically pure acrylamide was slowly added. Stirring was continued until the solution was clear to obtain a mixed solution. 0.6 g of a 10 wt% aqueous ascorbic acid solution and a 5 wt% aqueous hydrogen peroxide solution were dropwise added to the mixed solution. The mixture was quickly stirred and poured into a mold and allowed to stand for gelation. After the gel exotherm ended, the mixture was removed to obtain a hydrogel block, which was cut into pieces and placed in a 100°C oven for drying and dehydration for 48 hours to obtain a xerogel.

[0110] (2) Step 2: Gel heat treatment and powder preparation:

[0111] A large amount of dry gel with free water removed was placed in the inner lining of the reactor, and analytical pure acetone was poured in to make the liquid level reach 2 / 3 of the volume. The lid was tightly covered and sealed in the outer lining. The sealed reactor was placed in an oven and programmed to keep warm at 200°C for 8 hours. After the insulation was completed, it was cooled to room temperature. The block material in the reactor was taken out and the surface liquid was dried. The taken out block material was mechanically crushed to screen out particles below 20 mesh, and the particles were divided into two parts and poured into two 1L planetary ball mills respectively, with a material-ball ratio of 1:1. Zirconia ball milling beads occupy 1 / 3 of the volume, and the ball milling media are zirconia beads with particle sizes of 5mm, 10mm and 15mm. The mass ratio of 5mm, 10mm and 15mm zirconia beads is 5:3:2; the parameters of the planetary ball mill are set as follows: first run at a speed of 500r / min for 10 minutes, then adjust to 360r / min and continue to run for 6 hours before shutting down. The ground powder is passed through a 100-mesh sieve and sealed to prevent moisture. Finally, about 76g of powder raw materials can be screened out from each jar.

[0112] (3) Step 3: Warm pressing, carbonization and graphitization:

[0113] 32 g of the prepared raw material powder was weighed and loaded into a Φ50 mm graphite mold for warm pressing. Uniaxial pressurization was performed while slowly loading and heating at a rate of 3°C / min. The temperature was kept at 180°C, 220°C, 260°C and the highest temperature of 300°C for 30 minutes respectively, and then the temperature was reduced to 220°C at a rate of 2°C / min and naturally cooled to room temperature to obtain a prefabricated green body; the pressure reached a peak of 8 tons before keeping at 260°C, and slowly dropped to 6 tons before keeping at 300°C. No additional loading was required during the cooling stage, and the temperature was unloaded when it dropped to below 200°C. After cooling to room temperature, the pressed green body was taken out, and the mass of the green body was about 27 g.

[0114] The pressed body was placed in an argon atmosphere tubular furnace at 1000°C for 1 hour to obtain a carbonized block, with a heating rate of 3°C / min and a cooling rate of 2°C / min. After cooling to 400°C, it was allowed to cool naturally. The carbonized block was then graphitized at 3000°C for 10 hours and finally cooled to room temperature to obtain a graphitized block, from a pressed block to a graphitized block.

[0115] The flexural strength of the carbon material prepared in Comparative Example 1 is 57 MPa.

[0116] By comparison, it can be clearly seen that the bending strength of the carbon material prepared in Comparative Example 1 is much lower than that in Example 1.

[0117] The above are merely preferred embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for preparing an ultra-high-strength carbon material, characterized in that: The following steps are involved: The reinforcing particles, acrylamide, water-soluble sugar, N,N'-methylenebisacrylamide, initiator and catalyst are added into deionized water and mixed evenly, and then dried, heat-treated, crushed and ball-milled in sequence to obtain composite powder; The composite powder is sequentially molded and carbonized to obtain the ultra-high-strength carbon material; The preparation process of the reinforced particles is as follows: acrylamide, water-soluble sugars and N,N'-methylenebisacrylamide are mixed and dissolved in deionized water, stirred to form a uniform solution; and then dried to obtain a hydrogel; The hydrogel is further subjected to heat treatment to obtain a pretreated product; Carrying out carbonization treatment on the pretreated product under an inert atmosphere to obtain a carbonized product; The carbonized product is crushed and ball-milled to obtain reinforced particles; The water-soluble sugars include one or more of glucose, fructose, galactose, maltose, sucrose, lactose or oligofructose.

2. The method for preparing an ultra-high-strength carbon material according to claim 1, characterized in that: Taking the sum of the weight percentages of the acrylamide, water-soluble sugar, N,N'-methylenebisacrylamide and deionized water as 100%, The mass fractions of the acrylamide, water-soluble sugar and N,N'-methylenebisacrylamide are 1-30%, 5-60% and 0.05-3% respectively, and the balance is deionized water.

3. The method for preparing an ultra-high-strength carbon material according to claim 1, characterized in that: The amount of the reinforcing particles added is 20% to 300% of the sum of the weight of the acrylamide, water-soluble sugars, N,N'-methylenebisacrylamide and deionized water; and / or The initiator is an aqueous solution of ammonium persulfate with a mass concentration of 10%, and the amount of the initiator added is 0.5%-3% of the total mass of the acrylamide, water-soluble sugar, N,N'-methylenebisacrylamide and deionized water; and / or The catalyst is a triethanolamine aqueous solution with a mass concentration of 10%, and the added amount thereof is 0.5%-3% of the total mass of the acrylamide, water-soluble sugar, N,N'-methylenebisacrylamide and deionized water.

4. The method for preparing an ultra-high-strength carbon material according to claim 1, characterized in that: In the process of preparing the reinforced particles and preparing the composite powder, the heat treatment conditions are: heating to 140-350°C at a heating rate of 0.1-20°C / min, and then keeping at this temperature for 0.5-30h; and / or During the preparation of the reinforced particles, the carbonization treatment conditions are: heating to 500-1600°C at a heating rate of 1-20°C / min, and then maintaining at this temperature for 0.5-30h; and / or In the process of preparing the reinforced particles and the composite powder, the ball milling conditions are: ball-to-material ratio 1-20:1, ball milling speed 100-600 r / min, and ball milling time 6-48 h.

5. The method for preparing an ultra-high-strength carbon material according to claim 1, characterized in that: The conditions during the molding process are: Keep warm for 0.5-6h at a pressure of 10-600MPa and a temperature of 120-900℃.

6. The method for preparing an ultra-high-strength carbon material according to claim 1, characterized in that: In the process of preparing the ultra-high strength carbon material using the composite powder, the conditions of the carbonization treatment are: In an inert atmosphere, the temperature is raised to 1000-3000°C at a heating rate of 1-20°C / min, and then kept at this temperature for 0.5-24 hours.

7. The method for preparing an ultra-high-strength carbon material according to claim 6, characterized in that: In the process of preparing ultra-high-strength carbon materials using the composite powder, when the carbonization temperature is raised to 1000-1600° C., a high-strength isotropic nanocrystalline / amorphous carbon bulk carbon material is obtained; When the temperature is raised to 1800-2400°C, a high-strength isotropic three-dimensional network graphene / amorphous carbon block carbon material is obtained; When the temperature is raised to 2600-3000℃, a high-strength isotropic graphite material is obtained.

8. An ultra-high-strength carbon material, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 7.

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