CN117164359A - Method for preparing carbon graphite material by in-situ densification - Google Patents

Abstract

The invention discloses a method for preparing a carbon graphite material by in-situ densification, which comprises the following steps: and pressing and forming the raw materials containing volatile matters for preparing the carbon graphite material to obtain a green body, then placing the green body in a closed container for roasting treatment, volatilizing the volatile matters of the raw materials and raising the internal pressure of the closed container, and obtaining the carbon graphite material after the roasting treatment is finished. The method for preparing the high-performance carbon graphite material by in-situ densification can effectively reduce useless volatile matters and convert part of the useless volatile matters into beneficial volatile matters, and the prepared carbon graphite material has higher density and excellent mechanical property.

Description

A method for preparing carbon graphite materials through in-situ densification

Technical field

The invention belongs to the field of carbon materials, and in particular relates to a method for preparing carbon graphite materials.

Background technique

Carbon materials, also known as carbon materials, include materials produced with carbon and graphite as raw materials. Carbon graphite materials have attracted great attention from various industries around the world due to their properties such as high temperature resistance, high conductivity, low density, high strength, corrosion resistance, self-lubrication and superior electronic properties, and are widely used in nuclear power, automobiles, aviation Aerospace, metallurgy, chemical industry, machinery, medical, electronics and other industries have become an indispensable non-metallic material in modern industrial technology. It is known as "black gold" and is recognized as the new industry with the most potential for development in the 21st century. One of the materials, it is of great significance to the progress of my country's science and technology and the development of the national economy.

The preparation of carbon graphite materials usually includes traditional processes and self-sintering processes. The traditional process uses calcined petroleum coke, pitch coke, graphite, carbon black, anthracite, metallurgical carbon, charcoal, etc. as solid raw materials, and coal pitch, coal tar, and anthracene oil. , resin, etc. are used as binders, and carbon graphite materials are prepared through batching, kneading, shaping, roasting, graphitization and other processes. In order to achieve the density and performance that can meet practical applications, multiple repeated impregnations and roastings are required, which inevitably leads to an increase in production costs and a prolongation of production time. What's even worse is that a large amount of useless volatilization in the binder will produce large thermal stress, leading to phase separation and poor bonding force at the interface between the aggregate and the binder, resulting in most carbon graphite. Materials often exhibit poor performance. Another type of self-sintering process uses raw materials with bonding functions. It only needs to select suitable molding raw materials and does not require binders, thereby eliminating the need for mixing and repeated impregnation/roasting processes, and the production cycle and cost will be significantly improved. of reduction. However, the raw materials used in the self-sintering process often have too high volatile content (10%-20%) and large volume shrinkage, which disrupts the further orderly rearrangement of the molecular structure to a certain extent, resulting in the block being prone to cracks or even cracking. phenomenon, greatly reducing the yield and mechanical properties of the product.

Therefore, whether carbon graphite materials are prepared by traditional processes or self-sintering processes, reasonable volatile components are the key to preparing high-performance carbon graphite materials. This is because during the heat treatment process, some beneficial volatile components serve as binding components to form a bonding network. The particles are tightly connected together, giving them a certain mechanical strength. The other part of useless volatile matter is due to chemical reactions such as chain scission and polycondensation of a large number of polymer chains on the surface of the particles, which release a large amount of H ₂ O, CO, CO ₂ , H ₂ , CH ₄ and other gases, creating a large number of pores inside the material. and micro-cracks, which affect the performance of the product and even cause the product to crack.

At present, methods for removing useless volatiles mainly include solvent pretreatment (such as patent CN113387701A) and oxidation heat treatment. However, the above methods all have practical problems such as cumbersome preparation processes and difficulty in industrialization. Therefore, how to reduce useless volatile matter or even partially convert it into beneficial volatile matter to remain in the product, promote in-situ welding between particles, increase volume shrinkage while reducing mass loss, thereby achieving in-situ densification. A major challenge in preparing high-performance carbon graphite materials.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the shortcomings and defects mentioned in the above background technology and provide a method for preparing carbon graphite materials by in-situ densification. This method can effectively reduce useless volatile matter and convert part of it into useful Volatile matter, the prepared carbon graphite material has high density and excellent mechanical properties. In order to solve the above technical problems, the technical solutions proposed by the present invention are:

A method for preparing carbon graphite materials by in-situ densification, including the following steps: pressing raw materials containing volatile matter for preparing carbon graphite materials to obtain a green body, and then placing the green body in a closed container for roasting treatment, The volatile components of the raw materials are volatilized and the internal pressure of the sealed container is increased. After the roasting process is completed, the carbon graphite material is obtained.

In the present invention, the atmosphere inside the sealed container does not need to be controlled and air can be used, and other processes such as vacuuming or nitrogen filling and pressurization are not required.

In the above method for preparing carbon graphite materials by in-situ densification, preferably, the raw material includes raw coke powder, and the raw coke powder includes one of raw petroleum coke, raw pitch coke, raw needle coke and mesophase carbon microspheres. One or more kinds; the particle size D50 of the green coke powder is 1-20 μm, and the mass content of volatile matter of the green coke powder is 10-20%.

In the above-mentioned method for preparing carbon graphite materials by in-situ densification, preferably, the raw material includes pressed powder, and the pressed powder is aggregate and binder after a processing process including batching, kneading, molding, and crushing processes. The obtained powder has a particle size D50 of 1-20 μm and a volatile mass content of 10-20%.

In the above method for preparing carbon graphite materials by in-situ densification, preferably, the aggregate includes one or more of calcined petroleum coke, pitch coke, graphite, carbon black, anthracite, metallurgical carbon and charcoal; the adhesive Binders include medium-temperature asphalt or high-temperature asphalt.

In the above-mentioned method for preparing carbon graphite materials through in-situ densification, preferably, the sealed container is a cylindrical container made of graphite, which is filled with embedding material, and other spaces after placing the green body are filled with the embedding material. The above-mentioned buried burning materials can be made of existing conventional products, such as a mixture of river sand and metallurgical coke.

In the above method for preparing carbon graphite materials by in-situ densification, preferably, the pressure in the sealed container is 0.1-5MPa. The present invention uses the volatile components of the green body itself as the source of in-situ densification to increase the pressure inside the closed container.

In the above-mentioned method for preparing carbon graphite materials by in-situ densification, preferably, the compression molding includes pre-molding and isostatic pressing. First, pre-molding is performed on a flat vulcanizer, and then isostatic pressing is performed through a cooling press, and then slowly unloaded. The green body is obtained by pressing.

In the above-mentioned in-situ densification method for preparing carbon graphite materials, it is preferred to first use a flat vulcanizer to hold the pressure at a pressure of 1-5MPa for 10-30s for pre-molding, and then use a cooling press to hold the pressure at a pressure of 150-250MPa. 5-10min, and then slowly release the pressure to obtain a green body.

In the above-mentioned method for preparing carbon graphite materials by in-situ densification, preferably, the roasting treatment is to raise the temperature to 1050°C for 2-6 hours under the protection of an inert gas at a heating rate of 0.1-4°C/min, and then slowly cool to room temperature.

The technical principle of the present invention is that during the roasting process of the green body, a large number of polymer chains undergo chemical reactions such as chain scission and polycondensation, releasing a large amount of H ₂ O, CO, CO ₂ , H ₂ , CH ₄ and other gases. The method of preparing carbon graphite materials through in-situ densification can allow part of the useless volatile matter that escapes during heat treatment to fill the restricted space (i.e., inside the closed container) as a source of increased external pressure. At the same time, this process is accompanied by an increase in the volume of the green body. The expansion of the container causes the internal pressure of the container to increase due to multiple factors acting at the same time. According to Le Chatelier's principle, in a reversible reaction involving gas participation or generation, when the pressure is increased, the equilibrium always moves in the direction of decreasing pressure. Therefore, the green body begins to reach an equilibrium state in the direction of volume reduction (reduction of environmental pressure), and at the same time, the original decomposition reaction also moves in the direction of polymerization (polymerization energy decompression). Specifically, the green body will undergo significant volume expansion at 200-600°C. At this time, the roasted green body is in a softened plastic state. This process mainly involves the severe thermal decomposition and polymerization of the binder, that is, the green body undergoes high-temperature cracking, Reactions such as polycondensation produce low molecular compounds and volatile components such as CO ₂ , H ₂ O, CO, light oil, etc., resulting in an increase in external environmental pressure. Most of the low molecular compounds decomposed from the binder are in a liquid state due to their high vapor pressure, further penetrating into tiny pores and tiny cracks, breaking unstable chemical bonds to generate free radicals, dehydrogenation and polycondensation, and repolymerization proceed simultaneously. The blank is further densified to reduce mass loss and increase volume shrinkage, that is, conversion of useless volatile matter into beneficial volatile matter. In this way, 100% of the volatile components can play a role, thus playing the role of in-situ densification. However, the conventional self-sintering process or traditional process fails to exert a pressurizing effect at the stage where volatile components are generated in large quantities (200-600°C). The volatile components escape directly, and the external environment of the block is basically at normal pressure, and the escape of low molecular compounds The extrusion process is accompanied by the expansion of pores and micro-cracks, and at this time, the stress within the block is greater than the external environmental pressure, which ultimately causes cracks or even cracking of the product.

The in-situ densification method of preparing carbon graphite materials of the present invention does not require vacuuming. The purpose is to retain a part of the air (filled between the buried sinter particles or adsorbed on the surface of the buried sinter), so that the green body can be preheated at an early temperature of 400°C. Oxidation increases the coking amount, and a small amount of CO ₂ , CO, H ₂ O, etc. in the air can be used as small molecule volatiles to promote polycondensation and polymerization reactions. In addition, the in-situ densification method for preparing carbon graphite materials of the present invention does not perform pressure relief operations during the preparation process, and uses volatile components such as low molecular compounds to increase the pressure in the container and promote polycondensation and polymerization reactions. The temperature range where a large amount of volatile matter escapes during the roasting process is 200-600°C. This is the stage where a large number of reactions occur in the product. At this time, the air pressure in the closed container can be greater than 2.5MPa (for example, coal pitch decomposes and reacts at 300-450°C. The polymerization reaction proceeds simultaneously and reaches equilibrium), and reaches equilibrium at a certain temperature and pressure. If the pressure relief operation is performed, the reaction balance will be imbalanced, causing the green body to further decompose a part of the gas. It will be difficult to return to the reaction equilibrium if the pressure is subsequently increased. , it is difficult to better realize the in-situ densification effect emphasized by the present invention.

The in-situ densification method of preparing high-performance carbon graphite materials of the present invention can effectively reduce useless volatile matter and convert part of it into beneficial volatile matter, and the prepared carbon graphite material has higher density and excellent mechanical properties. More importantly, this method is universal and is also suitable for preparing roasted products from other carbon graphite materials.

Compared with the prior art, the advantages of the present invention are:

1. The in-situ densification method of preparing high-performance carbon graphite materials of the present invention only requires placing the green body in a closed container and then roasting it. The volatile matter is used to increase the pressure in the closed container without any additional Processing is simple, convenient and efficient.

2. The in-situ densification method of preparing high-performance carbon graphite materials of the present invention converts a part of useless volatile matter into beneficial volatile matter, thereby reducing the mass loss of the sample while increasing the volume shrinkage of the sample, increasing the performance of the product, and None of the samples cracked, the yield could reach 100%, and the densification effect was good.

3. The in-situ densification method of preparing high-performance carbon graphite materials of the present invention can ensure that the bulk product does not crack when the volume shrinks to a greater extent, and the bulk product has greater density and more excellent mechanical properties.

4. The in-situ densification method of the present invention for preparing high-performance carbon graphite materials is not only useful for preparing carbon graphite materials through the self-sintering process of raw coke, mesophase carbon microspheres, etc., but is also useful for the kneading and shaping of aggregates/binders. Traditional techniques such as roasting and roasting can also play a similar role in promoting food quality.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are: For some embodiments of the present invention, those of ordinary skill in the art can also obtain other drawings based on these drawings without exerting creative efforts.

Figure 1 is a physical diagram of the carbon graphite material prepared in Example 1, Comparative Example 1, Example 2, and Example 3; wherein (a) is the in-situ densified carbon graphite material roasted product ZM prepared in Example 1 -12SJ's front view, (b) is the front view of the carbon graphite material roasted product 12SJ prepared in Comparative Example 1; (c) is the in-situ densified carbon graphite material roasted product ZM-12SJ-1 prepared in Example 2 (d) is a front view of the carbon graphite material roasted product ZM-12SJ-5 prepared in Example 3.

Figure 2 is a physical diagram of the carbon graphite material prepared in Example 4, Comparative Example 2, Example 5, and Comparative Example 3; wherein (a) is the in-situ densified carbon graphite material roasted product ZM prepared in Example 4 - The front view of 6SJ, (b) is the front view of the carbon graphite material roasted product 6SJ prepared in Comparative Example 2; (c) is the front view of the in-situ densified carbon graphite material roasted product ZM-ZZJ prepared in Example 5 Figure (d) is a front view of the carbon graphite material roasted product ZZJ prepared in Comparative Example 3.

Figure 3 is a flexural and compressive curve of the calcined blocks prepared in Examples 1-5 and Comparative Examples 1-3, where (a) and (d) are ZM-12SJ prepared in Example 1 and Comparative Example 1 respectively. Comparison chart of bending resistance curve and compression resistance curve of 12SJ. (b) and (e) are the bending resistance curve comparison chart and the compression resistance curve comparison chart of ZM-6SJ and 6SJ prepared in Example 4 and Comparative Example 2 respectively. (c) and (f) are the bending resistance curve comparison chart and the compression resistance curve comparison chart of ZM-ZZJ and ZZJ prepared in Example 5 and Comparative Example 3 respectively.

Figure 4 is a surface morphology diagram of the roasted product prepared in Example 1 and Comparative Example 1. (a1) and (a2) are respectively the SEM image and the corresponding back surface of ZM-12SJ prepared in Example 1. Scattering SEM images; (b1) and (b2) are respectively the SEM images of 12SJ prepared in Comparative Example 1 and their corresponding backscattered SEM images.

Figure 5 is a surface morphology diagram of the roasted product prepared in Example 4 and Comparative Example 2, in which (a1) and (a2) are respectively the SEM image and the corresponding back surface of ZM-6SJ prepared in Example 4. Scattering SEM images; (b1) and (b2) are respectively the SEM images of 6SJ prepared in Comparative Example 2 and their corresponding backscattering SEM images.

Figure 6 is a surface morphology diagram of the roasted product prepared in Example 5 and Comparative Example 3. (a1) and (a2) are respectively the SEM image and the corresponding back surface of ZM-ZZJ prepared in Example 5. Scattering SEM images; (b1) and (b2) are the SEM images of ZZJ prepared in Comparative Example 3 and their corresponding backscattered SEM images respectively.

Figure 7 is a morphology diagram of the anti-breakage surface of the baked product prepared in Example 1 and Comparative Example 1, in which (a1) and (a2) are respectively SEM images of the anti-breakage surface of ZM-12SJ prepared in Example 1. and its corresponding backscattered SEM image; (b1) and (b2) are respectively the SEM image of the anti-bending section of 12SJ prepared in Comparative Example 1 and its corresponding backscattered SEM image.

Figure 8 is a morphology diagram of the anti-breakage surface of the baked product produced in Example 4 and Comparative Example 2, in which (a1) and (a2) are respectively SEM images of the anti-fracture surface of ZM-6SJ produced in Example 4. and its corresponding backscattered SEM image; (b1) and (b2) are respectively the SEM image of the anti-bending section of 6SJ prepared in Comparative Example 2 and its corresponding backscattered SEM image.

Figure 9 is a morphology diagram of the anti-breakage surface of the baked products prepared in Example 5 and Comparative Example 3, in which (a1) and (a2) are respectively SEM images of the anti-breakage surface of ZM-ZZJ prepared in Example 5. and its corresponding backscattered SEM image; (b1) and (b2) are respectively the SEM image of the anti-bending section of the ZZJ prepared in Comparative Example 3 and its corresponding backscattered SEM image.

Detailed ways

In order to facilitate understanding of the present invention, the present invention will be described more comprehensively and in detail below with reference to the accompanying drawings and preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments.

Unless otherwise defined, all technical terms used below have the same meanings as commonly understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of the present invention.

Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased in the market or prepared by existing methods.

Example 1:

A method for preparing high-performance carbon graphite materials by in-situ densification, using a self-sintering method to sinter the carbon graphite materials during the roasting process, including the following steps:

(1) Shape green coke powder with a particle size of 12 μm (D50 is about 11.50 μm) under a flat vulcanizer. The pressure used is 3MPa, and then pressurized at 200MPa for 10 minutes. Leave it aside for more than 12 hours to obtain a green body.

(2) Place the green body obtained in step (1) into a cylindrical container made of graphite in a restricted space that will not allow volatile components to escape. The remaining parts are buried with a sintered material (a mixture of river sand and metallurgical coke, below). Same as) filling.

(3) Place the graphite cylindrical container installed in step (2) in a thermal field, and under argon protection, raise it to 1050°C at a heating rate of 0.2°C/min, keep it warm for 4 hours, and then heat it to 1050°C at a heating rate of 0.2°C/min. The cooling rate of ℃/min is reduced to below 200℃, and then naturally cooled to room temperature, and the in-situ densified carbon graphite material roasting product is obtained, named ZM-12SJ.

Comparative example 1:

A method for carbon graphite materials, including the following steps:

(1) Shape green coke powder with a particle size of 12 μm (D50 is about 11.50 μm) under a flat vulcanizer. The pressure used is 3MPa, and then pressurized at 200MPa for 10 minutes. Leave it aside for more than 12 hours to obtain a green body.

(2) The green body obtained in step (1) is placed in a graphite cylindrical container with an open space where volatile matter can diffuse arbitrarily, and the remaining part is filled with buried sinter material.

(3) Place the graphite cylindrical container installed in step (2) in a thermal field, and under argon protection, raise it to 1050°C at a heating rate of 0.2°C/min, keep it warm for 4 hours, and then heat it to 0.2°C /min cooling rate to below 200°C, and then naturally cooled to room temperature to obtain a roasted carbon graphite material, named 12SJ.

Example 2:

A method for preparing high-performance carbon graphite materials by in-situ densification, using a self-sintering method to sinter the carbon graphite materials during the roasting process, including the following steps:

(1) Shape green coke powder with a particle size of 12 μm (D50 is about 11.50 μm) under a flat vulcanizer. The pressure used is 1MPa, and then pressurized at 200MPa for 10 minutes. Leave it aside for more than 12 hours to obtain a green body.

(2) Place the green body obtained in step (1) into a cylindrical container made of graphite in a restricted space that does not allow volatile components to escape, and fill the remaining portion with buried sinter.

(3) Place the graphite cylindrical container installed in step (2) in a thermal field, and under argon protection, raise it to 1050°C at a heating rate of 0.2°C/min, keep it warm for 4 hours, and then heat it to 1050°C at a heating rate of 0.2°C/min. The cooling rate of ℃/min is reduced to below 200℃, and then naturally cooled to room temperature, and the in-situ densified carbon graphite material roasting product is obtained, named ZM-12SJ-1.

Example 3:

A method for preparing high-performance carbon graphite materials by in-situ densification, using a self-sintering method to sinter the carbon graphite materials during the roasting process, including the following steps:

(1) Shape green coke powder with a particle size of 12 μm (D50 is about 11.50 μm) under a flat vulcanizer. The pressure used is 5MPa, and then pressurized at 200MPa for 10 minutes. Leave it aside for more than 12 hours to obtain a green body.

(2) Place the green body obtained in step (1) into a cylindrical container made of graphite in a restricted space that does not allow volatile components to escape, and fill the remaining portion with buried sinter.

(3) Place the graphite cylindrical container installed in step (2) in a thermal field, and under argon protection, raise it to 1050°C at a heating rate of 0.2°C/min, keep it warm for 4 hours, and then heat it to 1050°C at a heating rate of 0.2°C/min. The cooling rate of ℃/min is reduced to below 200℃, and then naturally cooled to room temperature, and the in-situ densified carbon graphite material roasting product is obtained, named ZM-12SJ-5.

Example 4:

A method for preparing high-performance carbon graphite materials by in-situ densification, using a self-sintering method to sinter the carbon graphite materials during the roasting process, including the following steps:

(1) Shape green coke powder with a particle size of 6 μm (D50 is about 5.87 μm) under a flat vulcanizer. The pressure used is 3MPa, and then pressurized at 200MPa for 10 minutes. Leave it aside for more than 12 hours to obtain a green body.

(2) Place the green body obtained in step (1) into a cylindrical container made of graphite in a restricted space that does not allow volatile components to escape, and fill the remaining portion with buried sinter.

(3) Place the graphite cylindrical container installed in step (2) in a thermal field, and under argon protection, raise it to 1050°C at a heating rate of 0.2°C/min, keep it warm for 4 hours, and then heat it to 1050°C at a heating rate of 0.2°C/min. The cooling rate of ℃/min is reduced to below 200℃, and then naturally cooled to room temperature, and the in-situ densified carbon graphite material roasting product is obtained, named ZM-6SJ.

Comparative example 2:

A method for carbon graphite materials, including the following steps:

(1) Shape green coke powder with a particle size of 6 μm (D50 is about 5.87 μm) under a flat vulcanizer. The pressure used is 3MPa, and then pressurized at 200MPa for 10 minutes. Leave it aside for more than 12 hours to obtain a green body.

(2) The green body obtained in step (1) is placed in a graphite cylindrical container with an open space where volatile matter can diffuse arbitrarily, and the remaining part is filled with buried sinter material.

(3) Place the graphite cylindrical container installed in step (2) in a thermal field, and under argon protection, raise it to 1050°C at a heating rate of 0.2°C/min, keep it warm for 4 hours, and then heat it to 0.2°C /min to below 200°C, and then naturally cooled to room temperature to obtain a roasted carbon graphite material, named 6SJ.

Example 5:

A method for preparing high-performance carbon graphite materials by in-situ densification, using traditional processes to obtain carbon graphite materials by sintering during the roasting process, including the following steps:

(1) Weigh 160g of needle-shaped coke powder with a particle size of 10 μm (D50 is about 10.01 μm), place it in a mixing pot at room temperature and premix it to 200°C, pour in 80g of liquid asphalt, and boil it to 190°C (softening point 109 ℃). Close the lid and knead for 1 hour. After the kneading is completed, the needle-shaped coke powder is obtained by slicing, crushing and grinding.

(2) Shape the needle coke pressed powder obtained in step (1) under a flat vulcanizer. The pressure used is 3MPa, and then pressurized at 200MPa for 10 minutes. Leave it aside for more than 12 hours to obtain a green body.

(3) Place the green body obtained in step (2) into a cylindrical container made of graphite in a restricted space that does not allow volatile components to escape, and fill the remaining portion with buried sinter.

(4) Place the graphite cylindrical container installed in step (3) in a thermal field, and under argon protection, raise it to 1050°C at a heating rate of 0.1°C/min, keep it warm for 4 hours, and then heat it to 0.1°C /min cooling rate to below 200°C, and then naturally cooled to room temperature, the in-situ densified carbon graphite material roasting product was obtained, named ZM-ZZJ.

Comparative example 3:

A method for carbon graphite materials, including the following steps:

(1) Weigh 160g of needle-shaped coke powder with a particle size of 10 μm (D50 is about 10.01 μm), place it in a mixing pot at room temperature and premix it to 200°C, pour in 80g of liquid asphalt, and boil it to 190°C (softening point 109 ℃). Close the lid and knead for 1 hour. After the kneading is completed, the needle-shaped coke powder is obtained by slicing, crushing and grinding.

(2) Shape the needle coke pressed powder obtained in step (1) under a flat vulcanizer. The pressure used is 3MPa, and then pressurized at 200MPa for 10 minutes. Leave it aside for more than 12 hours to obtain a green body.

(3) The green body obtained in step (2) is placed in a graphite cylindrical container with an open space where volatile matter can diffuse arbitrarily, and the remaining part is filled with buried sinter material.

(4) Place the graphite cylindrical container installed in step (3) in a thermal field, and under argon protection, raise it to 1050°C at a heating rate of 0.1°C/min, keep it warm for 4 hours, and then heat it to 0.1°C /min cooling rate to below 200°C, and then naturally cooled to room temperature to obtain a roasted carbon graphite material, named ZZJ.

The above-mentioned roasted products were measured for bulk density, Shore hardness, resistivity, mass loss rate, volume shrinkage, and open porosity. The samples were then made into standard samples, and the flexural strength and compressive strength were measured. Test data As shown in Table 1 and Table 2 below. The testing standards for each performance data are as follows: Volume density test: JB/T 8133.14-2013; Shore hardness test: JB/T 8133.4-2013; Resistivity test: GB/T 24525-2009; Flexural strength test: JB /T 8133.7-2013; Compressive strength test: JB/T8133.8-2013; Open porosity test: GB/T 24529-2009; The roasting mass loss rate and roasting volume shrinkage rate are the mass/volume loss ratio of the sample after roasting . Raw coke powder or pressed powder volatile matter: GB/T 212-2008, volatile matter conversion rate is the percentage of reduced mass loss in volatile matter, as shown in Table 1 and Table 2 below.

Table 1: Basic performance parameters of the roasted products in Examples 1-3 and Comparative Example 1

Table 2: Basic performance parameters of the roasted products in Examples 4-5 and Comparative Examples 2-3

Performance parameters ZM-6SJ 6SJ ZM-ZZJ ZZJ Green density (g/cm ³ ) 1.22 1.21 1.48 1.50 Density after roasting (g/cm ³ ) 1.59 1.39 1.42 1.22 Roasting mass loss rate (%) 13.93 14.39 8.04 10.11 Raw coke powder or pressed powder volatile matter (%) 14.90 14.90 11.22 11.22 Volatile matter conversion rate (%) 6.51 3.42 28.34 9.89 Baking volume shrinkage (%) 34.05 25.24 4.27 -10.22 Shore Hardness (HSD) 95.5 74.67 79.2 58 Open porosity (%) 18.62 26.04 27.77 41.68 Resistivity (μΩ·m) 57.65 68.02 60.26 96.96 Compressive strength (MPa) 171.64 59.73 136.21 65.71 Flexural strength (MPa) 67.26 21.49 49.82 25.52

It can be seen from Tables 1 and 2 that the carbon graphite material roasted blocks prepared by the in-situ densification process have obvious performance advantages. Specifically, Table 1 shows four types of roasted blocks. Among them, the green blocks ZM-12SJ and 12SJ were also formed under a pressure of 3MPa. The density of the roasted product ZM-12SJ prepared by the in-situ densification process is as high as 1.49g/cm. ³ , while the density of roasted products prepared by common methods is only 1.34g/cm ³ . Compared with 12SJ, ZM-12SJ has a density increase of 0.15g/cm ³ , an opening porosity decrease of 5.86%, a resistivity decrease of 60.35Ω, and a hardness increase of 8.25%. The HSD and flexural compressive strength increased by 134.25% and 179.06% respectively, the volatile matter conversion rate increased by 9.88%, and the volume shrinkage rate increased by 4.09%.

Table 2 shows four types of calcined blocks, among which ZM-6SJ and 6SJ are formed under the same pressure of 3MPa. The density of the calcined product ZM-6SJ obtained by the in-situ densification process can reach 1.59g/cm ³ , while the density of the calcined product ZM-6SJ obtained by the common method The density of the prepared baked product is only 1.39g/cm ³ . Compared with 6SJ, ZM-6SJ has a density increase of 0.2g/cm ³ , an opening porosity decrease of 7.42%, a resistivity decrease of 10.37Ω, a hardness increase of 20.83HSD, and a bending resistance The compressive strength increased by 212.98% and 187.36% respectively, the volatile matter conversion rate increased by 3.09%, and the volume shrinkage rate increased by 8.81%.

ZM-ZZJ and ZZJ are produced using the traditional process of using calcined needle coke as aggregate and asphalt as binder. They are also formed under a pressure of 3MPa and the roasted product ZM-ZZJ is obtained using an in-situ densification process. The density of ZM-12SJ can reach 1.42g/cm ³ , while the density of roasted products prepared by common methods is only 1.22g/cm ³ . Compared with 12SJ, ZM-12SJ has a density increase of 0.2g/cm ³ , a decrease in open porosity of 13.91%, and a resistance of The rate is reduced by 36.7Ω, the hardness is increased by 21.2HSD, the flexural and compressive strength are increased by 95.22% and 107.29% respectively, the volatile matter conversion rate is increased by 18.45%, and the volume shrinkage rate is increased by 14.49%.

Figure 1 shows the front view of the roasted carbon graphite material prepared in Example 1-3 and Comparative Example 1. Figure 2 shows the roasted carbon graphite material prepared in Example 4-5 and Comparative Example 2-3. From the front view of the sample, it can be clearly seen that compared with the carbon graphite material roasted products 12SJ (b in Figure 1), 6SJ (b in Figure 2), and ZZJ (d in Figure 2) prepared by the general process, the The carbon graphite material roasted products ZM-12SJ (a in Figure 1), ZM-6SJ (a in Figure 2) and ZM-ZZJ (c in Figure 2) prepared by the in-situ densification process have smaller lateral dimensions, which is Because the in-situ densification process improves density and product performance by reducing the mass loss of the sample and increasing the volume shrinkage of the sample. The size of the roasted carbon graphite material prepared by the general method (b in Figure 1, b in Figure 2, d in Figure 2) is larger, shrinks less, and has obvious uneven volume shrinkage and even cracking. There is obvious cracking in the lower right corner of block ZZJ shown in d in Figure 2.

Figure 3 is a flexural and compressive curve of the calcined blocks prepared in Examples 1-5 and Comparative Examples 1-3. It can be clearly seen that samples ZM-12SJ, ZM-6SJ and ZM prepared through the in-situ densification process -ZZJ has obvious mechanical performance advantages.

Figures 4, 5 and 6 show ZM-12SJ (a in Figure 4) and 12SJ (a in Figure 4) prepared in Example 1 and Comparative Example 1, Example 4 and Comparative Example 2, Example 5 and Comparative Example 3. b), ZM-6SJ (a in Fig. 5) and 6SJ (b in Fig. 5), ZM-ZZJ (a in Fig. 6) and ZZJ (b in Fig. 6) surface morphology (a ₁ , b ₁ ) and the corresponding backscattering patterns (a ₂ , b ₂ ). It can be clearly seen that ZM-12SJ, ZM-6SJ, and ZM-ZZJ prepared by the in-situ densification process have a denser structure than 12SJ, 6SJ, and ZZJ prepared by the general method, which proves from a microscopic perspective that the in-situ The densification process can promote the volume shrinkage of the roasted sample and increase the density of the roasted sample.

Figures 7, 8 and 9 show ZM-12SJ (a in Figure 7) and 12SJ (a in Figure 7) prepared in Example 1 and Comparative Example 1, Example 4 and Comparative Example 2, Example 5 and Comparative Example 3 (b), ZM-6SJ (a in Figure 8) and 6SJ (b in Figure 8), ZM-ZZJ (a in Figure 9) and ZZJ (b in Figure 9) sintered products (a) ₁ , b ₁ ) and the corresponding backscattering pattern (a ₂ , b ₂ ). It can be clearly seen that the ZM-12SJ, ZM-6SJ, and ZM-ZZJ sections prepared by the in-situ densification process have fewer crack defects than the 12SJ, 6SJ, and ZZJ sections prepared by the general method, which proves that The excellent mechanical properties of the calcined samples prepared by the in-situ densification process are attributed to their dense structure and fewer internal crack defects.

The above descriptions all show that the in-situ densification process can greatly improve the density and mechanical properties of carbon graphite materials. This is mainly due to making full use of the supercharging effect caused by the escape of volatile matter, increasing the volume shrinkage of the sample while reducing mass loss, promoting the formation of a bonding network between particles, inhibiting the formation of micro-cracks, and greatly increasing the density and quality of the product. strength.

Claims (9)

1. A method for preparing carbon graphite materials by in-situ densification, which is characterized in that it includes the following steps: pressing raw materials containing volatile matter for preparing carbon graphite materials to obtain a green body, and then placing the green body in a sealed state. The roasting process is carried out in the container to volatilize the volatile components of the raw materials and increase the internal pressure of the sealed container. After the roasting process is completed, the carbon graphite material is obtained. 2. The method for preparing carbon graphite materials by in-situ densification according to claim 1, characterized in that the raw materials include raw coke powder, and the raw coke powder includes raw petroleum coke, raw pitch coke, and raw needle coke. and one or more mesophase carbon microspheres; the particle size D50 of the green coke powder is 1-20 μm, and the mass content of volatile matter of the green coke powder is 10-20%. 3. The method for preparing carbon graphite materials by in-situ densification according to claim 1, characterized in that the raw materials include pressed powder, and the pressed powder is aggregate and binder through ingredients, kneading, molding, The powder obtained after a treatment process including a crushing process; the particle size D50 of the pressed powder is 1-20 μm, and the mass content of volatile matter in the pressed powder is 10-20%. 4. The method for preparing carbon graphite materials by in-situ densification according to claim 3, characterized in that the aggregate includes a mixture of calcined petroleum coke, pitch coke, graphite, carbon black, anthracite, metallurgical carbon and charcoal. One or more kinds; the binder includes medium-temperature asphalt or high-temperature asphalt. 5. The method for preparing carbon graphite materials by in-situ densification according to claim 1, characterized in that the sealed container is a cylindrical container made of graphite, which is filled with a buried burnt material, and the buried burnt material is used to fill and place the raw material. other spaces after the blank. 6. The method for preparing carbon graphite materials by in-situ densification according to claim 1, characterized in that the pressure in the closed container is 0.1-5MPa. 7. The method for preparing carbon graphite materials by in-situ densification according to any one of claims 1 to 6, characterized in that the compression molding includes pre-molding and isostatic pressing, and the pre-molding is first carried out on a flat vulcanizing machine. , then perform isostatic pressing through a cooling press, and then slowly release the pressure to obtain a green body. 8. The method for preparing carbon graphite materials by in-situ densification according to claim 7, characterized in that first, the pressure of 1-5MPa is maintained on a flat vulcanizer for 10-30s for pre-molding, and then the cold press is used to press the carbon graphite material. Maintain the pressure at 150-250MPa for 5-10 minutes, and then slowly release the pressure to obtain a green body. 9. The method for preparing carbon graphite materials by in-situ densification according to any one of claims 1-6, characterized in that the roasting treatment is a temperature rise of 0.1-4°C/min under the protection of an inert gas. The temperature is increased to 900-1200°C and kept for 2-6 hours, then slowly cooled to room temperature.