Carbon graphite material, preparation method and application thereof

Abstract

The present application relates to the field of carbon materials, in particular to a kind of carbon graphite material and its preparation method and application.The present application provides a kind of preparation method of carbon graphite material, comprising the following steps: S1, carbon aggregate and first coupling agent are mixed and reacted, and then dried, to obtain modified aggregate;S2, modified aggregate, second coupling agent and binder are mixed and kneaded, to obtain paste;S3, after paste cooling, crushing, screening, pressing forming, roasting, obtain carbon graphite material.The present application is by "two-step chemical grafting" using borate coupling agent, between carbon aggregate and binder by chemical bond form chemical binding realizes boron element in situ fixation, without high temperature graphitization, after roasting boron element is formed B-C bond with carbon, stably exists in material, and good oxidation resistance.

Description

Technical Field

[0001] This invention relates to the field of carbon materials, specifically to a carbon graphite material, its preparation method, and its applications. Background Technology

[0002] Carbon graphite materials are widely used in sealing and friction applications due to their low coefficient of thermal expansion, excellent self-lubricating properties, superior chemical stability, and excellent thermal shock resistance. The increasing size of modern engineering machinery means that dynamic sealing components must withstand higher rotational speeds and higher end-face pressures, resulting in greater friction and wear. This necessitates that dynamic sealing materials possess better high-temperature oxidation resistance. However, carbon graphite materials are highly susceptible to oxidation in oxygen-containing high-temperature environments (>450℃). The weight loss due to graphite oxidation significantly reduces the material's mechanical properties, limiting its high-temperature performance. Therefore, improving the oxidation resistance of carbon graphite materials is a prerequisite for utilizing their superior properties. The main approaches to improving the oxidation resistance of carbon graphite materials fall into two categories: surface coating technology and internal matrix modification. Adding boron-containing oxidation inhibitors to enhance the oxidation resistance of carbon graphite materials is one of the commonly used methods. Boron reacts with oxygen before carbon graphite materials to form a glassy substance, boron trioxide, which constructs an antioxidant protective film on the surface of the carbonaceous aggregate.

[0003] Carbon-graphite materials are typical porous, multiphase, and multicomponent composite materials. Traditional processes use asphalt coke, petroleum coke, and graphite as the main aggregates, with asphalt as the binder, and are prepared through dry processes. Some studies have explored adding a certain amount of oxidation inhibitor hexagonal boron nitride (h-BN) and modifying it to effectively disperse its agglomerates, which is beneficial for improving the mechanical and oxidation resistance of carbon-graphite materials. However, this method uses physical methods to construct a modified layer on the surface of the oxidation inhibitor, making it difficult for the oxidation inhibitor to form chemical bonds with the carbonaceous aggregate and binder. The weak bonding between the modified layer and the oxidation inhibitor makes it easily destroyed during molding, forming cavities. During heat treatment, this can lead to sharp microcracks or interconnected pores, making it difficult for the material's oxidation resistance to meet the requirements of complex working conditions. Summary of the Invention

[0004] This invention provides a carbon graphite material, its preparation method, and its application to solve the above-mentioned problems.

[0005] In a first aspect, the present invention provides a method for preparing a carbon-graphite material, comprising the following steps:

[0006] S1, carbonaceous aggregate and the first coupling agent are mixed and reacted, then dried to obtain modified aggregate;

[0007] S2, the modified aggregate, the second coupling agent and the binder are mixed and kneaded to obtain a paste;

[0008] S3. After the paste cools, it is crushed, sieved, pressed into shape, and calcined to obtain carbon graphite material.

[0009] In one optional embodiment, the temperature of the mixing reaction is 40-90°C, optionally 60-80°C;

[0010] In one alternative embodiment, the mixing reaction takes 1-1.5 hours.

[0011] In one optional embodiment, the mass ratio of the carbonaceous aggregate to the total amount of the first coupling agent and the second coupling agent is (87-99):(1-13).

[0012] In one optional embodiment, the mass ratio of the first coupling agent to the second coupling agent is (2-5):1.

[0013] It should be noted that the present invention can control the particle size of raw materials through grinding. The apparatus and equipment used are conventional in the field. For example, the present invention can use a Raymond mill to prepare natural graphite powder or artificial graphite powder with a particle size D50 of 5-9μm and calcined coke aggregate with a D50 of 3-8μm. The air and moisture in the surface and pores are removed by a vacuum drying system at 110-150℃.

[0014] The weight ratio of the first coupling agent to the second coupling agent is (2-5):1. Boron (B) has both catalytic and inhibitory effects on the mechanism of improving the antioxidant properties of carbon-graphite materials.

[0015] When the B content is low, it has a catalytic effect on the oxidation of carbon graphite materials. The B element replaces the C atoms at the edge of the graphite. Due to the strong electron-withdrawing property of B, the substitution of B can lower the Fermi level and promote the development of π electrons in the direction of weakening C-C bonds and strengthening CO bonds, thus exhibiting a catalytic effect on the oxidation of carbon graphite materials.

[0016] As the content of element B increases, element B occupies oxidation active sites and forms a boron oxide barrier layer, which inhibits the oxidation of carbon graphite materials.

[0017] When the content of element B further increases, the graphitization degree of the carbon-graphite material decreases, and the atomic weight of the edge activated carbon increases, thus reducing its antioxidant properties. In other words, the weight ratio of the carbonaceous aggregate to the borate coupling agent affects the product's antioxidant properties. Increasing the amount of borate coupling agent initially improves the antioxidant properties, but then decreases. Too little or too much borate coupling agent will negatively impact its performance; therefore, the amount of borate coupling agent used needs to be carefully controlled.

[0018] In the ratio of the first coupling agent to the second coupling agent, it is preferable to use a larger proportion of the first coupling agent to ensure the modification and dispersion effect on the carbonaceous aggregate. The second coupling agent is an auxiliary modifier, and its dosage can be relatively smaller.

[0019] In one alternative embodiment, the first coupling agent comprises a borate ester coupling agent with a trimeryl structure;

[0020] Optionally, the boronic acid ester coupling agent with the trimeryl structure has the structure shown in formula (1).

[0021] B(OR1)3 formula (1),

[0022] In formula (1), R1 is selected from C1-C4 alkyl or alkoxy groups.

[0023] In one alternative embodiment, the second coupling agent comprises a borate ester coupling agent with a diester group structure;

[0024] Optionally, the diester-structured borate ester coupling agent has the structure shown in formula (2).

[0025] (R2O)2B-R3 Equation (2).

[0026] In formula (2), R2 is selected from C1-C4 alkyl groups.

[0027] R3 is selected from C1-C4 alkylene groups.

[0028] This invention employs a two-stage grafting process using borate ester coupling agents, which facilitates a more uniform in-situ introduction of boron, resulting in superior oxidation resistance of the carbon-graphite material. Simultaneously, the two in-situ boron introduction processes also allow the coupling agent to function effectively, achieving multiple benefits in one step.

[0029] The first coupling agent is a borate ester coupling agent with a trimeryl structure. The three ester groups in the molecule are highly polar, requiring a polar solvent to weaken the intermolecular forces, stabilize its dispersion, and maintain its reactivity. Furthermore, its esterification reaction with the hydroxyl groups on the aggregate surface (forming -OC- bonds) requires a trace amount of solvent as a reaction medium to lower the reaction activation energy and ensure that full grafting is completed within the reaction time. Optionally, it can be a ZB-99 type borate ester coupling agent or an SBW-Ⅲ type borate ester coupling agent.

[0030] The second coupling agent is a borate ester coupling agent with a diester structure. It contains only two ester groups in its molecule and is less polar than the first coupling agent. As can be seen from the general structural formula mentioned earlier, R3 is a short-chain alkylene group (C1-C4). It can diffuse rapidly in the oily environment of molten asphalt and can react with the hydroxyl groups remaining on the surface of the modified aggregate and the aromatic groups in the asphalt without the need for solvents, thus achieving "secondary modification". Optionally, it is an LD-100P type borate ester coupling agent.

[0031] It is worth noting that the trimeryl borate coupling agent is suitable for wet grafting reaction systems, while the diesteryl borate coupling agent is suitable for dry grafting reaction systems. Based on the requirements of the borate coupling agent's mechanism of action according to this invention, different borate coupling agents are selected in S1 and S2 respectively. The two in-situ introduction processes of boron require the appropriate selection of different types of borate coupling agents. For example, if a diesteryl borate coupling agent is selected in S1, the requirements for the solvent will be higher, and it will be difficult to guarantee the grafting degree and uniformity. If S1 is replaced with a dry process, the aggregate surface cannot be modified, and in-situ uniform fixation of boron cannot be achieved, affecting the antioxidant properties. If S2 is replaced with a wet process, it will affect the subsequent molding and calcination process, especially since rapid solvent evaporation during calcination can cause internal cracks, affecting the yield.

[0032] In one alternative embodiment, the carbonaceous aggregate comprises graphite powder and calcined coke aggregate;

[0033] Optionally, the mass ratio of the graphite powder to the calcined coke aggregate is (60-70):(30-40).

[0034] Optionally, the D50 of the graphite powder is 5-9 μm;

[0035] Optionally, the D50 of the calcined coke aggregate is 3-8 μm.

[0036] In one optional embodiment, the kneading temperature is 180-190℃, the pressure is 1.5-2.5MPa, and the time is 1-2h;

[0037] In one optional embodiment, the calcination temperature is 1000-1100℃ and the time is 3-6 hours.

[0038] In an optional embodiment, step S1 further includes dispersing the first coupling agent in an alcohol solvent;

[0039] Optionally, the mass ratio of the first coupling agent to the anhydrous solvent is (1-11):(2-32);

[0040] Optionally, the alcohol solvent includes at least one of anhydrous ethanol and anhydrous methanol;

[0041] In one optional embodiment, in step S2, the mixing process further includes first dry mixing the modified aggregates.

[0042] Optionally, the dry mixing temperature is 110-120℃ and the time is 1-2 hours;

[0043] In one optional embodiment, in step S2, the roasting process further includes setting aside the pressed green body.

[0044] Optionally, the resting time is 8-10 hours.

[0045] It should be noted that during the kneading process, the modified aggregate is first placed in a kneading pot and dry-mixed at 110-120℃ for 1-2 hours to remove moisture. Then, the temperature inside the kneading pot is raised to 140-160℃, the second coupling agent and molten asphalt are added, and the kneading temperature is maintained at 185±5℃, the kneading pressure is maintained at 2±0.5MPa, and kneading is continued for 1-2 hours. The introduction of a pressurization process during kneading facilitates the spreading and wetting of the binder on the aggregate surface, changes the interfacial state, achieves synchronous shrinkage during the calcination stage, reduces the risk of cracking, and improves the mechanical properties of the carbon-graphite material.

[0046] The crushing and sieving process to obtain pressed powder involves cooling the paste, crushing it, and then passing it through a 160-325 mesh sieve to obtain pressed powder.

[0047] During the pressing process, the powder is first molded at 1-3 MPa, then vacuumed in a vacuum bag and placed in an isostatic pressing cylinder for isostatic pressing at 160-180 MPa.

[0048] During the roasting process, the pressed green body is left to stand for 8-10 hours, then placed in an atmosphere resistance furnace for burial, heated to 1000-1100℃, and held for 3-6 hours.

[0049] It should be noted that this invention disperses carbonaceous aggregate in a solvent containing a first coupling agent, which can prevent the agglomeration of ultrafine carbonaceous aggregate and achieve chemical modification of the carbonaceous aggregate. Simultaneously, the organic-loving groups in the first coupling agent molecule enhance the adhesion between the carbonaceous aggregate and the binder. During pressurized kneading, the addition of a second coupling agent facilitates the uniform mixing of the binder and modified aggregate, and also achieves further surface modification. Furthermore, pressurized kneading improves the spreading and interfacial state of the binder on the surface of the carbonaceous aggregate, reduces inherent structural defects caused by inconsistent thermal expansion and contraction between the aggregate and binder, promotes synchronous shrinkage to form a tightly bonded structure, and achieves synchronous shrinkage during the calcination stage, reducing the risk of cracking. This enables primary interfacial structure regulation and strengthening of the graphite sealing material, improving its density. More importantly, boron is introduced in situ as an oxidation inhibitor. The uniform distribution of boron in the carbon-graphite material solves the problem of uneven dispersion of antioxidant inhibitors, improving the antioxidant performance of the carbon-graphite material.

[0050] In one alternative embodiment, the binder has a mass fraction of 39-42% of the paste.

[0051] Optionally, the adhesive includes bitumen.

[0052] Secondly, the present invention provides a carbon graphite material prepared by the above-described preparation method.

[0053] Thirdly, the present invention provides an application of the above-mentioned carbon graphite material in the field of sealing or lubrication.

[0054] This invention mainly addresses the problems of uneven dispersion of different types of fine-particle raw materials during the kneading process and poor bonding between different phase interfaces after the introduction of additives by modifying the raw materials themselves and improving the preparation process, and prepares a graphite sealing material with excellent antioxidant properties.

[0055] The technical solution of this invention has the following advantages:

[0056] 1. This invention provides a method for preparing carbon-graphite material, comprising the following steps: S1, mixing and reacting carbonaceous aggregate with a first coupling agent, followed by drying to obtain modified aggregate; S2, kneading the modified aggregate, a second coupling agent, and pitch to obtain a paste; S3, after the paste cools, crushing, sieving, pressing, and finally calcining to obtain carbon-graphite material. This invention disperses carbonaceous aggregate in a solvent containing a first coupling agent, which can prevent the agglomeration of ultrafine carbonaceous aggregate and achieve chemical modification of the carbonaceous aggregate. Simultaneously, it utilizes the organophilic groups in the first coupling agent molecule to enhance the adhesion between the carbonaceous aggregate and the binder. Adding a second coupling agent during pressurized kneading facilitates uniform mixing of the binder and modified aggregate and also enables further surface modification. Meanwhile, pressurized kneading improves the spreading and interface state of the binder on the surface of carbonaceous aggregate, reduces the inherent structural defects caused by inconsistent thermal expansion and contraction between aggregate and binder, promotes synchronous shrinkage to form a tightly bonded structure, realizes synchronous shrinkage during the calcination stage, reduces the risk of cracking, achieves one-time interface structure regulation and strengthening of graphite sealing material, and improves the material density.

[0057] This invention utilizes a borate ester coupling agent through a "two-step chemical grafting" process to achieve in-situ fixation of boron element by forming chemical bonds between carbonaceous aggregate and binder, eliminating the need for high-temperature graphitization. After calcination, boron element forms BC bonds with carbon, stably existing in the material and exhibiting good oxidation resistance. The borate ester coupling agent introduced in this invention, with its unique chemical structure, allows its functionalized groups to combine with the carbonaceous aggregate, chemically modifying the surface of the carbonaceous aggregate. This improves the compatibility of the components in the system, achieving synchronous shrinkage during the calcination stage, reducing the risk of cracking. Furthermore, this invention, during the kneading process... The process involves introducing a second coupling agent for secondary grafting, achieving in-situ introduction of boron. This solves the problem of uneven dispersion of borate ester coupling agents as antioxidant inhibitors. Under high-temperature oxidation conditions, boron combines with oxygen to form a B2O3 glass film, which covers the surface of the carbon material and plays a role in preventing oxidation. Moreover, no additional operations are required, making the overall process simpler. The carbon-graphite material preparation method provided by this invention offers ideas and theoretical basis for improving the preparation and processes of other composite materials with poor raw material powder dispersibility and interfacial bonding problems, while also expanding the application range of coupling agents.

[0058] 2. In the preparation method of carbon graphite material provided by the present invention, in step S1, the temperature of the mixing reaction is 40-90℃, optionally 60-80℃, and the time is 1-1.5h. Only at the above temperature can the first coupling agent be fully coupled with the surface of the composite aggregate powder. Attached Figure Description

[0059] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0060] Figure 1 These are the Raman spectra of carbon-graphite materials obtained by the preparation methods provided in Example 2 and Comparative Example 1 of this invention;

[0061] Figure 2 These are physical images of carbon graphite materials obtained by the preparation methods provided in Embodiment 1 (Figure a), Embodiment 2 (Figure b), Embodiment 3 (Figure c), and Comparative Example 1 (Figure d) of the present invention. Detailed Implementation

[0062] The following embodiments are provided to better understand the present invention, but the following embodiments do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

[0063] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having” and any variations thereof in the text of this application are intended to cover non-exclusive inclusion.

[0064] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0065] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers from a to b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed herein, and "0-5" is merely a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥ 2, it is equivalent to disclosing that the parameter can be, for example, integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0066] In the description of the embodiments of this application, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0067] In the description of the embodiments of this application, the term "at least one" refers to one or more (including two).

[0068] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0069] Unless otherwise specified, all experimental steps or conditions in the examples were performed according to conventional experimental procedures and conditions in the art. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0070] The asphalt used is molten asphalt;

[0071] The first coupling agent used includes at least one of ZB-99 type borate ester coupling agent and SBW-Ⅲ type borate ester coupling agent;

[0072] The second coupling agent used includes LD-100P type borate ester coupling agent;

[0073] The triethanolamine borate ester used was purchased from Jinan Shuangying Chemical Co., Ltd.

[0074] The phthalate coupling agent TC-201 used was purchased from Dongguan Sany Plastics Co., Ltd.

[0075] The triisopropyl borate T819120 used was purchased from Shanghai McLean Biochemical Technology Co., Ltd.

[0076] Example 1

[0077] This embodiment provides a method for preparing carbon-graphite materials, with the specific steps and parameter settings as follows:

[0078] S1. Natural graphite powder with a particle size D50 of 7 μm and calcined petroleum coke with a D50 of 5 μm were prepared using a Raymond mill. Part of the air and moisture in the surface and pores were removed using a vacuum drying system at 110°C to obtain graphite powder and calcined coke aggregate. 67 parts by weight of the prepared graphite powder and 33 parts by weight of the calcined coke aggregate were added to a mixer and mixed for 30 min to obtain the carbonaceous aggregate. The carbonaceous aggregate and a first coupling agent solution were ultrasonically stirred at 60°C for 1.5 h. After ultrasonic stirring, the mixture was placed in an oven and dried at 80°C for 24 h to obtain the modified aggregate. The preparation method of the first coupling agent solution included dissolving the first coupling agent in anhydrous ethanol and ultrasonically stirring at 60°C for 0.5 h. The mass ratio of the first coupling agent (SBW-III type borate ester coupling agent) to anhydrous ethanol was 1:30.

[0079] S2, the modified aggregate is added to a mixing pot and dry-mixed at 110 ℃ for 1 hour to remove moisture. Then the temperature inside the pot is raised to 140 ℃, asphalt and the second coupling agent—LD-100P type borate ester coupling agent—are added. The mixing temperature is maintained at 185 ℃ and the mixing pressure is maintained at 2 MPa. After mixing for 1.5 hours, the mixture is removed from the pot to obtain a paste. The amount of asphalt added accounts for 41% of the mass fraction of the paste. The mass ratio of the carbonaceous aggregate to the total amount of the first coupling agent and the second coupling agent is 99:1. The mass ratio of the first coupling agent to the second coupling agent is 3:1.

[0080] S3. After the paste cools to room temperature, it is crushed and passed through a 250-mesh sieve to obtain pressed powder. After molding at 3 MPa, it is vacuumed in a vacuum bag and placed in an isostatic pressing cylinder. It is then isostatically pressed at 180 MPa to obtain a carbon graphite material green body. After the green body is left to stand for 10 hours, it is placed in an atmosphere resistance furnace for filling. The temperature is raised to 1000℃ according to the program, held for 4 hours, and then cooled to room temperature according to the program to obtain the carbon graphite material.

[0081] Example 2

[0082] This embodiment provides a method for preparing carbon-graphite materials, with the specific steps and parameter settings as follows:

[0083] The only difference between this embodiment and Example 1 is that, in S1, the carbonaceous aggregate and the first coupling agent solution are ultrasonically stirred at 70°C for 1.2 hours; the mass ratio of the first coupling agent (ZB-99 borate ester coupling agent) to anhydrous ethanol is 1:8.

[0084] In S2, the mass ratio of the carbonaceous aggregate to the total amount of the first coupling agent and the second coupling agent is 95:5; the mass ratio of the first coupling agent to the second coupling agent is 4:1.

[0085] Example 3

[0086] This embodiment provides a method for preparing carbon-graphite materials, with the specific steps and parameter settings as follows:

[0087] The only difference between this embodiment and Embodiment 1 is that, in S1, the carbonaceous aggregate and the first coupling agent solution are ultrasonically stirred at 75°C for 1 hour; the mass ratio of the first coupling agent to anhydrous ethanol is 3:13.

[0088] In S2, the mass ratio of the carbonaceous aggregate to the total amount of the first coupling agent and the second coupling agent is 92:8; the mass ratio of the first coupling agent to the second coupling agent is 7:1.

[0089] Example 4

[0090] This embodiment provides a method for preparing carbon-graphite materials, with the specific steps and parameter settings as follows:

[0091] The only difference between this embodiment and Example 1 is that, in S1, the carbonaceous aggregate and the first coupling agent solution are ultrasonically stirred at 80°C for 1 hour; the mass ratio of the first coupling agent (ZB-99 borate ester coupling agent to SBW-Ⅲ borate ester coupling agent is 1:1) to anhydrous ethanol is 11:32.

[0092] In S2, the mass ratio of the carbonaceous aggregate to the total amount of the first coupling agent and the second coupling agent is 89:11; the mass ratio of the first coupling agent to the second coupling agent is 10:1.

[0093] Example 5

[0094] This embodiment provides a method for preparing carbon-graphite materials, with the specific steps and parameter settings as follows:

[0095] The only difference between this embodiment and Embodiment 1 is that, in S2, the mass ratio of the carbonaceous aggregate to the total amount of the first coupling agent and the second coupling agent is 87:13; and the mass ratio of the first coupling agent to the second coupling agent is 2:1.

[0096] Example 6

[0097] This embodiment provides a method for preparing carbon-graphite materials, with the specific steps and parameter settings as follows:

[0098] The only difference between this embodiment and Embodiment 1 is that, in S2, the mass ratio of the carbonaceous aggregate to the total amount of the first coupling agent and the second coupling agent is 99:1; and the mass ratio of the first coupling agent to the second coupling agent is 5:1.

[0099] Example 7

[0100] This embodiment provides a method for preparing carbon-graphite materials, with the specific steps and parameter settings as follows:

[0101] The only difference between this embodiment and Embodiment 1 is that, in S1, the mass ratio of the first coupling agent (ZB-99 borate ester coupling agent) to anhydrous ethanol is 1:30.

[0102] Example 8

[0103] This embodiment provides a method for preparing carbon-graphite materials, with the specific steps and parameter settings as follows:

[0104] The only difference between this embodiment and Embodiment 1 is that, in S1, the mass ratio of the first coupling agent (ZB-99 borate coupling agent and SBW-Ⅲ borate coupling agent is 1:1) to anhydrous ethanol is 1:30.

[0105] Example 9

[0106] This embodiment provides a method for preparing carbon-graphite materials, with the specific steps and parameter settings as follows:

[0107] The only difference between this embodiment and Embodiment 1 is that, in S1, the carbonaceous aggregate and the first coupling agent solution are ultrasonically stirred at 40°C for 1.5 hours.

[0108] Example 10

[0109] This embodiment provides a method for preparing carbon-graphite materials, with the specific steps and parameter settings as follows:

[0110] The only difference between this comparative example and Example 1 is that, in S1, the carbonaceous aggregate and the first coupling agent solution are ultrasonically stirred at 90°C for 1.5 hours.

[0111] Comparative Example 1

[0112] This comparative example provides a method for preparing carbon-graphite materials, with the specific steps and parameter settings as follows:

[0113] The only difference between this comparative example and Example 1 is that the first coupling agent and the second coupling agent are not added.

[0114] Comparative Example 2

[0115] This comparative example provides a method for preparing carbon-graphite materials, with the specific steps and parameter settings as follows:

[0116] The only difference between this comparative example and Example 2 is that the second coupling agent is added together with the first coupling agent in S1.

[0117] Comparative Example 3

[0118] This comparative example provides a method for preparing carbon-graphite materials, with the specific steps and parameter settings as follows:

[0119] The only difference between this comparative example and Example 1 is that the first coupling agent is added together with the second coupling agent in S2.

[0120] Comparative Example 4

[0121] This comparative example provides a method for preparing carbon-graphite materials, with the specific steps and parameter settings as follows:

[0122] The only difference between this comparative example and Example 1 is that, in S1, the first coupling agent is replaced with an equal mass of triethanolamine borate.

[0123] In S2, the second coupling agent is replaced with an equal mass of phthalate coupling agent TC-201.

[0124] Comparative Example 5

[0125] This comparative example provides a method for preparing carbon-graphite materials, with the specific steps and parameter settings as follows:

[0126] The only difference between this comparative example and Example 1 is that, in S2, the second coupling agent is replaced with an equal mass of triisopropyl borate T819120.

[0127] Experimental Example 1

[0128] The carbon-graphite materials prepared in each embodiment and comparative example were subjected to performance tests. The specific test methods are as follows:

[0129] The antioxidant performance was tested according to HB 5367.4-1986 "Determination of thermal oxidation weight loss of carbon-graphite sealing materials". The specific test results are shown in Table 1.

[0130] Table 1 Antioxidant performance test data

[0131]

[0132] This patent significantly improves the high-temperature oxidation resistance of carbon-graphite materials through a two-step borate ester coupling agent grafting process. The oxidation weight loss rate of Examples 1-10 is much lower than that of Comparative Example 1 without coupling agent and that using traditional coupling agents. Among them, Example 2 is the best, with a reduction of 73.1% compared to Comparative Example 1, proving that boron is uniformly fixed in situ through chemical bonds, which can effectively form a B2O3 antioxidant protective film. Secondly, the microstructure and macroscopic integrity are significantly optimized. Raman spectroscopy shows that the intensity ratio of the defect peak to the graphitization peak (ID / IG=0.23) of Example 2 is much lower than that of Comparative Example 1 (0.65), and the micro-defects are reduced by 64.6%. This proves that the "stepwise grafting + process adaptation" design can solve the core problems of "uneven dispersion and poor interface bonding" in traditional processes, laying the foundation for the application of materials in the fields of sealing and lubrication.

[0133] Figure 1The images show the Raman spectra of carbon graphite materials obtained by the preparation methods provided in Example 2 and Comparative Example 1 of this invention. The D and G peaks in the figures are typical peaks of carbon graphite materials. By calculation, the ID / IG ratio of Comparative Example 1 is 0.65, and the ID / IG ratio of Example 2 is 0.23. The higher the ratio, the more defects there are. Example 2 reduces the number of defects and the number of active sites of the reaction by adding the first and second coupling agents, resulting in better antioxidant performance.

[0134] Figure 2 These are physical images of carbon-graphite materials obtained by the preparation methods provided in Embodiment 1 (Figure a), Embodiment 2 (Figure b), Embodiment 3 (Figure c), and Comparative Example 1 (Figure d) of the present invention. It can be seen that cracks appeared on the surface of the carbon-graphite material in Comparative Example 1.

[0135] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a carbon-graphite material, characterized in that, Includes the following steps: S1, the carbonaceous aggregate and the first coupling agent are mixed and reacted, and then dried to obtain the modified aggregate; The first coupling agent includes a borate ester coupling agent with a trimeryl structure; S2, the modified aggregate, the second coupling agent and the binder are mixed and kneaded to obtain a paste; The second coupling agent includes a borate ester coupling agent with a diester group structure; The mass ratio of the carbonaceous aggregate to the total amount of the first coupling agent and the second coupling agent is (87-99):(1-13). S3. After the paste cools, it is crushed, sieved, pressed into shape, and calcined to obtain carbon graphite material.

2. The method for preparing carbon-graphite material according to claim 1, characterized in that, The temperature of the mixing reaction is 40-90℃; And / or, the mixing reaction time is 1-1.5 h.

3. The method for preparing carbon-graphite material according to claim 2, characterized in that, The temperature of the mixing reaction is 60-80℃.

4. The method for preparing the carbon-graphite material according to any one of claims 1-3, characterized in that, The mass ratio of the first coupling agent to the second coupling agent is (2-5):

1.

5. The method for preparing the carbon-graphite material according to any one of claims 1-4, characterized in that, The borate ester coupling agent with the trimeryl group structure has the structure shown in formula (1). B(OR1)3 formula (1), In formula (1), R1 is selected from C1-C4 alkyl or alkoxy groups.

6. The method for preparing the carbon-graphite material according to any one of claims 1-5, characterized in that, The borate ester coupling agent with the diester group structure has the structure shown in formula (2). (R2O)2B-R3 Equation (2). In formula (2), R2 is selected from C1-C4 alkyl groups. R3 is selected from C1-C4 alkylene groups.

7. The method for preparing the carbon-graphite material according to any one of claims 1-6, characterized in that, The carbonaceous aggregate includes graphite powder and calcined coke aggregate.

8. The method for preparing the carbon-graphite material according to claim 7, characterized in that, The mass ratio of the graphite powder to the calcined coke aggregate is (60-70):(30-40). And / or, the D50 of the graphite powder is 5-9 μm; And / or, the D50 of the calcined coke aggregate is 3-8 μm.

9. The method for preparing the carbon-graphite material according to any one of claims 1-8, characterized in that, The mixing temperature is 180-190℃, the pressure is 1.5-2.5MPa, and the time is 1-2h; And / or, the calcination temperature is 1000-1100℃, and the time is 3-6h.

10. The method for preparing the carbon-graphite material according to any one of claims 1-9, characterized in that, S1 further includes dispersing the first coupling agent in an alcohol solvent; And / or, in S2, the mixing process further includes first dry mixing the modified aggregate; And / or, in S2, the roasting process also includes setting aside the pressed green body; And / or, based on the mass of the paste, the binder has a mass fraction of 39-42% of the paste.

11. The method for preparing the carbon-graphite material according to claim 10, characterized in that, The mass ratio of the first coupling agent to the alcohol solvent is (1-11):(2-32); And / or, the alcohol solvent includes at least one of anhydrous ethanol and anhydrous methanol; And / or, the dry mixing temperature is 110-120℃ and the time is 1-2h; And / or, the resting time is 8-10 hours; And / or, the adhesive includes bitumen.

12. A carbon graphite material, characterized in that, It is prepared by the preparation method described in any one of claims 1-11.

13. The application of the carbon graphite material of claim 12 in the field of sealing or lubrication.

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