Carbon-graphite material with ant nest hole structure and preparation method thereof

Abstract

The invention discloses a carbon-graphite material with an ant nest hole structure and a preparation method of the carbon-graphite material. The method comprises the following steps: crushing and screening one or more of calcined pitch coke, calcined petroleum coke, needle coke, foam carbon and carbon black to obtain aggregate of which the five-stage particle size is gradually reduced; mixing the primary aggregate with modified asphalt or a resin solution, uniformly stirring at 80-120 DEG C, and carbonizing at 400 DEG C to obtain modified primary aggregate; fully mixing 20-30 parts of modified first-stage aggregate, 10-20 parts of second-stage aggregate, 20-30 parts of third-stage aggregate, 10-20 parts of fourth-stage aggregate and 10-35 parts of fifth-stage aggregate to obtain mixed aggregate; carrying out dry mixing on the mixed aggregate at 120-160 DEG C to remove moisture, heating to 160-240 DEG C, adding 20-40 parts of molten modified coal pitch and 1-3 parts of a modifier, and carrying out uniform wet mixing to obtain a paste material; and placing the paste in a preheating mold for compression molding to obtain a green block, and then roasting to obtain the carbon-graphite material. The prepared carbon-graphite material is high in volume density and stable in resistivity, and has excellent mechanical properties, homogeneity and thermal stability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of carbon materials, and particularly relates to a carbon graphite material with ant nest pore structure and a preparation method thereof. BACKGROUND

[0002] The carbon graphite material is widely used in heat exchange equipment in the petroleum chemical industry, synthetic ammonia, phosphate fertilizer and other industries due to its excellent corrosion resistance, high thermal conductivity and low thermal expansion coefficient. However, with the increasing requirements of modern industry on the working temperature, pressure and reliability of the heat exchange equipment, more stringent requirements are put forward for the strength, density, homogeneity and thermal stability of the core material, i.e. graphite blank.

[0003] At present, the graphite materials used in the chemical industry mainly include metallurgical graphite and electrocarbon graphite. However, the metallurgical graphite has rough structure, low mechanical properties, and large and unevenly distributed holes in the blank, which leads to small effective heat transfer area, low material utilization rate and easy failure under high pressure working conditions. Although the electrocarbon graphite has relatively dense structure, a large amount of binder is needed due to the excessively fine aggregate particles, which leads to the concentration and large escape of volatile matters in the subsequent baking process, and thus easily causes the blank to bulge and crack, so that the production yield of finished products is low, the technology is difficult and the cost is high. SUMMARY

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present application is to provide a carbon graphite material with ant nest pore structure and a preparation method thereof. The carbon graphite material prepared by the present application has high bulk density, stable resistivity, excellent mechanical properties, homogeneity and thermal stability.

[0005] The technical scheme of the present application is as follows:

[0006] A preparation method of a carbon graphite material with ant nest pore structure, specifically comprising the following steps:

[0007] (1) crushing and sieving one or more of calcined pitch coke, calcined petroleum coke, needle coke (petroleum-based needle coke or coal-based needle coke), foamed carbon and carbon black to obtain five levels of aggregate, wherein the particle size of the first level of aggregate is [0.5mm, 0.9mm], the particle size of the second level of aggregate is [0.3mm, 0.5mm], the particle size of the third level of aggregate is [0.15mm, 0.3mm], the particle size of the fourth level of aggregate is [0.075mm, 0.15mm], and the particle size of the fifth level of aggregate is <0.075mm and D50 is 10-50um;

[0008] (2) mixing the first level of aggregate with a modified pitch or resin solution, stirring uniformly at 80-120℃, and then carbonizing at 400℃ to obtain modified first level of aggregate;

[0009] (3) mixing 15-30 parts of the modified primary aggregate, 10-20 parts of the secondary aggregate, 10-30 parts of the tertiary aggregate, 10-20 parts of the fourth aggregate and 10-40 parts of the fifth aggregate to obtain a mixed aggregate;

[0010] (4) drying the mixed aggregate at 120-160℃, then heating to 160-240℃, adding 20-40 parts of the molten binder and 1-3 parts of the modifier, and uniformly wet mixing to obtain a paste;

[0011] (5) placing the paste in a preheated mold for molding to obtain a green body, then burying it in a buried material and placing it in a calcining furnace for calcination to obtain the carbon graphite material.

[0012] Further, the modified asphalt is low-temperature coal tar pitch; and the mass ratio of the first aggregate to the modified asphalt is (15-25):(1-10).

[0013] Further, the resin solution is a phenolic resin solution, and the concentration of the phenolic resin is 30%-60%; and the mass ratio of the first aggregate to the resin solution is (15-25):(1-10).

[0014] Further, step (3) further contains 1-20 parts of active factor carbon; the volatile content of the active factor carbon is 3-10%.

[0015] Further, the preparation method of the active factor carbon is as follows: one or more of mesophase coal pitch, anthracene oil and coal tar are placed in a tube furnace, then pyrolyzed at 300-450℃ for 2-10h under inert protective atmosphere; then the solid particles are collected, then crushed, sieved and ground to D50 of 8-15um.

[0016] Further, in step (4), the modifier is one or more of coal tar, oleic acid and anthracene oil.

[0017] Further, in step (4), the binder is modified coal pitch.

[0018] Further, in step (5), the molding temperature is 100-200℃, and the pressure is 1-10MPa.

[0019] Further, in step (5), the green body is buried in the buried material before calcination, and then is placed in the calcination furnace for calcination, and the gradient is uniformly raised and lowered during calcination, specifically: the temperature in the furnace is raised from room temperature to 100 DEG C for 3-4h, then is raised to 200 DEG C for 4-6h, and is sequentially raised to 350 DEG C for 6-9h, is slowly raised to 450 DEG C for 16-20h, is slowly raised to 550 DEG C for 18-24h, is raised to 700 DEG C for 5-8h, is raised to 800 DEG C for 6-10h, is raised to 900 DEG C for 4-6h, is raised to 1050 DEG C for 2-5h, then is kept at 1050 DEG C for 4-6h, finally is uniformly lowered to 200 DEG C for 25-30h, and then is naturally cooled to room temperature.

[0020] The application further provides the carbon graphite material with the ant nest hole structure, which is prepared by the preparation method of the carbon graphite material with the ant nest hole structure.

[0021] Compared with the prior art, the application has the following beneficial effects:

[0022] 1、The application carries out screening and grading on aggregate particles, obtains five levels of aggregate with particle sizes of [0.5mm, 0.9mm], [0.3mm, 0.5mm], [0.15mm, 0.3mm], [0.075mm, 0.15mm] and particle size <0.075mm, and modifies the coarse aggregate with the particle size of [0.5mm, 0.9mm] by using modified asphalt or a resin solution, so that a firm bonding layer is formed on the surface of the coarse aggregate, the interface bonding force between the coarse aggregate and the binder can be enhanced when the aggregate and the binder are kneaded subsequently, the coarse aggregate cannot occupy the binder due to the small specific surface area, the binder cannot fully spread and infiltrate all the aggregate, the problem of interface cracks is avoided, and the mechanical properties of the carbon graphite material are improved.

[0023] Further, the active factor carbon is added when the aggregate with different particle sizes and the binder are kneaded, the active factor carbon has small particle size and contains appropriate volatile matter, the active factor carbon can fully fill in the fine pores of the aggregate particles during the kneading process, the homogeneity of the carbon graphite material is improved, meanwhile, the volatile matter can promote the formation of sintering necks and induce local volume shrinkage during the calcination process, the addition of the active factor carbon is equivalent to constructing a large number of active points on the surface of the aggregate particles, the overall densification process of the carbon graphite material is promoted, and the bulk density and the mechanical properties of the carbon graphite material are improved.

[0024] In this way, the carbon graphite material prepared by the application has uniform pore distribution, forms a three-dimensional interconnected structure similar to the ant nest hole, no sharp angle cracks and large destructive cracks are generated, heat stress can be dispersed and released, the thermal stability of the carbon graphite material is improved, uniform and stable channels can be provided for electron transmission, and the efficiency and stability of the electric heating conversion are ensured.

[0025] 2、The present application uses modified coal pitch as a binder, which has a high coking value, can effectively improve the strength of carbon graphite material, and the modified coal pitch is modified by a modifier, which can effectively improve the wettability of the modified coal pitch, further improve the binding force of the binder and aggregate, and improve the mechanical properties of the carbon graphite material.

[0026] 3、The present application can produce high-performance carbon graphite material without multiple impregnation and calcination, can significantly shorten the production cycle, reduce energy consumption and production cost, and has high yield, and is suitable for large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 - the bending and compressive resistance curve of the calcined block prepared in Example 1.

[0028] Figure 2 - the surface and section micro-morphology diagram of the calcined block prepared in Example 1.

[0029] Figure 3 - the actual photos of the calcined block prepared in Example 1.

[0030] Figure 4 - the bending and compressive resistance curve of the calcined block prepared in Example 1.

[0031] Figure 5 - the surface and section micro-morphology diagram of the calcined block prepared in Example 1.

[0032] Figure 6 - the surface micro-morphology diagram of the calcined block prepared in Comparative Example 7 and Comparative Example 8.

[0033] Figure 7 - the surface micro-morphology diagram of the calcined block prepared in Comparative Example 9.

[0034] Figure 8 - the mercury injection data diagram of the calcined block prepared in Example 1, Comparative Example 9 and Comparative Example 4. DETAILED DESCRIPTION

[0035] The present application will be further described in detail below in combination with the drawings and specific embodiments.

[0036] Example 1

[0037] A preparation method of a carbon graphite material with ant nest hole structure, specifically comprising the following steps:

[0038] (1) The calcined petroleum coke is broken and sieved to obtain five kinds of aggregates with particle sizes of [0.5mm, 0.9mm], [0.3mm, 0.5mm] mm, [0.15mm, 0.3mm] mm, [0.075mm, 0.15mm], and <0.075mm. Among them, the powder D50 of <0.075mm is controlled to be 30μm.

[0039] (2) 20 parts of the coarse aggregate with a particle size of [0.5mm, 0.9mm] in step (1) are taken and mixed with 5 parts of a phenolic resin solution (the concentration of phenolic resin is 40%) dissolved in toluene. The aggregate surface is uniformly coated at 100℃ for 60 minutes, then solidified at 120℃ for 1 hour, and then calcined at 400℃ for 4 hours to obtain coated coarse aggregate with a dense resin bonding layer on the surface.

[0040] (3) The coal tar is placed in a tube furnace, argon is introduced, and pyrolysis is carried out at 450℃ for 5 hours. The collected solid is broken and sieved through a 200 mesh screen to obtain undersize material. The undersize material is crushed in a Raymond mill to obtain active factor carbon with a D50 of 8μm. The volatile content in the active factor carbon is 5%.

[0041] (4) The coated coarse aggregate prepared in step (2) is accurately weighed as 24.4 parts, the calcined petroleum coke with a particle size of [0.3mm, 0.5mm] in step (1) is accurately weighed as 11.9 parts, the calcined petroleum coke with a particle size of [0.15mm, 0.3mm] is accurately weighed as 21.8 parts, the calcined petroleum coke with a particle size of [0.075mm, 0.15mm] is accurately weighed as 12.5 parts, the calcined petroleum coke with a particle size of <0.075mm is accurately weighed as 29.4 parts, and the active factor carbon prepared in step (3) is accurately weighed as 5 parts. The five kinds of aggregate and active factor carbon with different particle sizes are mixed in a powder mixing machine for 30 minutes to obtain a mixed aggregate.

[0042] (5) The modified coal pitch is accurately weighed as 21 parts, and the coal tar is accurately weighed as 3 parts.

[0043] (6) The mixing temperature is set to 100℃, the rotation speed is adjusted to 3r / min, the cover is opened and reversed; when the mixing temperature reaches the predetermined temperature, the mixed aggregate obtained in step (4) is slowly put into the mixing kettle, and dry mixing is carried out at 160℃ for 40 minutes. The rotation speed is adjusted to 10r / min, the cover is opened and rotated in the positive direction, which aims to completely remove the water; when the temperature of the mixed powder reaches the specified temperature, the rotation speed is adjusted to 30r / min, the cover is closed and reversed, the mixing temperature is set to 190℃, and the modified coal pitch in step (5) is heated. The temperature is measured while heating, and when the temperature reaches 80℃ above the softening point, it is put into the mixing kettle, and the coal tar modifier is added at the same time. The rotation speed is adjusted to 50r / min, the cover is closed, and wet mixing is carried out for 1 hour with alternating positive and reverse rotation. After mixing, a paste is obtained.

[0044] (7) The paste prepared in step (6) is molded into a green body under a pressure of 5 MPa. First, the mold is placed on the molding machine and heated, and the temperature of the mold is controlled at 180°C. The molding temperature is set at 140°C, and the pressure is maintained for 60 s. After demolding, a green body with a density of 1.75 g / cm 3 is obtained.

[0045] (8) The green body prepared in step (7) is placed in a crucible filled with a buried material, and the green body is ensured to be in the center of the buried material. The crucible is placed in a sintering furnace. The sintering program is set, and the temperature gradient is set to uniformly rise and fall within each gradient range. The temperature in the furnace is raised from room temperature to 100°C for 3 h, then raised to 200°C for 5 h, and then raised to 350°C for 8 h, slowly raised to 450°C for 18 h, slowly raised to 550°C for 20 h, raised to 700°C for 6 h, raised to 800°C for 8 h, raised to 900°C for 5 h, rapidly raised to 1050°C for 3 h, then maintained at 1050°C for 5 h, and finally uniformly cooled to 200°C for 1700 min, and then naturally cooled to room temperature, to obtain a sintered body.

[0046] Example 2

[0047] A preparation method of a carbon graphite material with a nest hole structure, specifically comprising the following steps:

[0048] (1) The calcined petroleum coke is crushed and sieved to obtain five kinds of aggregates with particle sizes of [0.5 mm, 0.9 mm], [0.3 mm, 0.5 mm] mm, [0.15 mm, 0.3 mm] mm, [0.075 mm, 0.15 mm], and <0.075 mm. The D50 of the powder <0.075 mm is controlled to be 40 μm.

[0049] (2) 20 parts of the coarse aggregate with a particle size of [0.5 mm, 0.9 mm] in step (1) are mixed with 5 parts of low-temperature coal tar pitch, stirred at 100°C for 60 minutes to uniformly coat the surface of the aggregate, and then calcined at 400°C for 4 h to obtain coated coarse aggregate with a semi-coke layer having a certain activity on the surface.

[0050] (3) The mesophase coal tar pitch is placed in a tube furnace, argon is introduced, and pyrolysis is performed at 350°C for 5 hours. The collected solid is crushed and sieved through a 200-mesh screen to obtain undersize material, which is crushed in a Raymond mill to a D50 of 12 μm to obtain active factor carbon. The volatile content in the active factor carbon is 5%.

[0051] (4) Accurately weigh 24 parts of coated coarse aggregate prepared in step (2), 12 parts of calcined petroleum coke with particle size of [0.3mm, 0.5mm] prepared in step (1), 20 parts of calcined petroleum coke with particle size of [0.15mm, 0.3mm], 13 parts of calcined petroleum coke with particle size of [0.075mm, 0.15mm], 31 parts of calcined petroleum coke with particle size <0.075mm, and 6 parts of active factor carbon prepared in step (3), and mix the five kinds of aggregate and active factor carbon with a powder mixer for 30 minutes to obtain mixed aggregate.

[0052] (5) Accurately weigh 21 parts of modified coal pitch and 3 parts of coal tar.

[0053] (6) Set the mixing temperature to 100°C and the rotation speed to 3r / min, open the cover and reverse the direction. When the mixing temperature reaches the predetermined temperature, slowly pour the mixed aggregate obtained in step (4) into the mixing pot and dry mix at 160°C for 40 minutes. Adjust the rotation speed to 10r / min, open the cover and rotate in the normal direction, which is to completely remove the water; when the temperature of the mixed powder reaches the specified temperature, adjust the rotation speed to 30r / min, close the cover and reverse the direction. Set the mixing temperature to 190°C and melt the modified coal pitch in step (5). Measure the temperature while heating, and pour it into the mixing pot when the temperature reaches 80°C above the softening point. At the same time, add the coal tar modifier, adjust the rotation speed to 50r / min, close the cover, and wet mix for 1 hour with alternating normal and reverse rotation. After mixing, the paste is obtained.

[0054] (7) The paste prepared in step (6) is molded into a green body by molding under a pressure of 5MPa. First, place the mold on the molding machine and control the mold temperature at 180°C. Set the molding temperature to 140°C and maintain the pressure for 60s. After demolding, the initial blank density of the green body is 1.75g / cm 3

[0055] 1) (8) Put the green body prepared in step (7) into a crucible filled with buried burning material, make sure that the green body is in the center of the buried burning material, and place the crucible in the calcination furnace. Set the individual calcination program and set the temperature gradient, and uniformly raise and lower the temperature in each gradient range. The temperature in the furnace is raised from room temperature to 100°C for 3h, then to 200°C for 5h, then to 350°C for 8h, then slowly to 450°C for 18h, then slowly to 550°C for 20h, then to 700°C for 6h, then to 800°C for 8h, then to 900°C for 5h, then quickly to 1050°C for 3h, then maintain at 1050°C for 5h, and finally uniformly cool to 200°C for 1700min, and then naturally cool to room temperature to obtain a calcined body.

[0056] Example 3

[0057] ​The present example is the same as example 1, except that in step (4) of the present example, 15 parts of coated coarse aggregate, 20 parts of calcined petroleum coke having a particle size of [0.3mm, 0.5mm] in step (1), 10 parts of calcined petroleum coke having a particle size of [0.15mm, 0.3mm], 15 parts of calcined petroleum coke having a particle size of [0.075mm, 0.15mm], and 40 parts of calcined petroleum coke having a particle size of <0.075mm in step (1), and 5 parts of active factor carbon prepared in step (3) are used.

[0058] Example 4

[0059] The present example is the same as example 1, except that in step (4) of the present example, 10 parts of active factor carbon are used.

[0060] Example 5

[0061] The present example is the same as example 1, except that in step (4) of the present example, 15 parts of active factor carbon are used.

[0062] Comparative Example 1

[0063] A method for preparing a carbon graphite material, specifically comprising the following steps:

[0064] (1) Crush and sieve calcined petroleum coke to obtain five kinds of aggregate having particle sizes of [0.5mm, 0.9mm], [0.3mm, 0.5mm], [0.15mm, 0.3mm], [0.075mm, 0.15mm], and <0.075mm, respectively. The D50 of the powder having a particle size of <0.075mm is controlled to be 40μm.

[0065] (2) Accurately weigh 24.4 parts of [0.5mm, 0.9mm] aggregate in step (1), 11.9 parts of calcined petroleum coke having a particle size of [0.3mm, 0.5mm] in step (1), 21.8 parts of calcined petroleum coke having a particle size of [0.15mm, 0.3mm], 12.5 parts of calcined petroleum coke having a particle size of [0.075mm, 0.15mm], and 29.4 parts of calcined petroleum coke having a particle size of <0.075mm.

[0066] (3) Accurately weigh 20 parts of modified coal pitch.

[0067] (4) Set the kneading temperature to 100℃, and adjust the rotating speed to 3r / min, open the cover, and reverse the rotation. When the kneading temperature reaches the predetermined temperature, slowly put the mixed aggregate obtained in step 2) into the kneading pot, and dry mix at 160℃ for 40min, adjust the rotating speed to 10r / min, open the cover, and rotate forward, so as to completely remove the water; when the temperature of the mixed micropowder reaches the set temperature, adjust the rotating speed to 30r / min, close the cover, and reverse the rotation, set the kneading temperature to 200℃, and melt the modified coal pitch obtained in step 3), and then put it into the mixed micropowder after it is melted, adjust the rotating speed to 50r / min, close the cover, and wet mix for 1.5h, and rotate forward and reverse alternately. After the kneading is completed, the green paste is obtained.

[0068] (5) The paste prepared in step 4) is subjected to die pressing to prepare a green body. The mold is preheated to 150℃, the forming temperature is set to 170℃, and the pressure is maintained for 60s. After demolding, the green body with a density of 1.75g / cm 3 is obtained after standing for 12h.

[0069] (6) The green body prepared in step 5) is put into a crucible filled with the calcined material, and the green body is ensured to be in the center of the calcined material, and the crucible is placed in a calcining furnace. The program is controlled, and the temperature gradient is set, and the temperature is uniformly raised and lowered in each gradient range. The temperature in the furnace is raised from room temperature to 100℃ for 3h, then raised to 200℃ for 5h, then raised to 350℃ for 8h, then slowly raised to 450℃ for 18h, then slowly raised to 550℃ for 20h, then raised to 700℃ for 6h, then raised to 800℃ for 8h, then raised to 900℃ for 5h, then rapidly raised to 1050℃ for 3h, then maintained at 1050℃ for 5h, and finally uniformly cooled to 200℃ for 1700min, and then naturally cooled to room temperature, to obtain a calcined body.

[0070] Comparative Example 2

[0071] This example is the same as Example 1, except that steps (2) and (3) are not included in this example, and the calcined petroleum coke with a particle size of [0.5mm, 0.9mm] is used to replace the coated coarse aggregate in step (4), and no active factor carbon is added.

[0072] Comparative Example 3

[0073] This example is the same as Example 1, except that step (2) is not included in this example, and the calcined petroleum coke with a particle size of [0.5mm, 0.9mm] is used to replace the coated coarse aggregate in step (4).

[0074] Comparative Example 4

[0075] This example is the same as Example 1, except that step (3) is not included in this example, and no active factor carbon is added in step (4).

[0076] Comparative Example 5

[0077] This example is the same as Example 1, except that in this example, no coal tar is added in step (6).

[0078] Comparative Example 6

[0079] This example is the same as Example 1, except that in this example, medium temperature coal tar pitch is used instead of modified coal tar pitch in step (6).

[0080] Comparative Example 7

[0081] This example is the same as Example 1, except that in this example, the active factor carbon D50 prepared in step (3) is 70 um.

[0082] Comparative Example 8

[0083] This example is the same as Example 1, except that in this example, the volatile content of the active factor carbon prepared in step (3) is 30%.

[0084] Comparative Example 9

[0085] This example is the same as Example 1, except that in this example, no calcined petroleum coke with a particle size of [0.15 mm, 0.3 mm] is added in step (4).

[0086] 1. The performance of the roasted blocks obtained in Examples 1-5 and Comparative Examples 1-9 was tested, and the performance parameters are shown in the following table:

[0087]

[0088] As can be seen from the above table, (1) as can be seen from Examples 1-5, the carbon graphite material prepared by the present application has high bulk density, stable resistivity, excellent mechanical properties, homogeneity and thermal stability. After the roasted blocks prepared by the present application are impregnated and graphitized, the resistivity can be stably controlled in the range of 5-10 μΩ·m.

[0089] (2) As can be seen from the comparison of Example 1 with Comparative Examples 2, 3 and 4, the coating of coarse aggregate, the addition of active factor carbon and the complete aggregate gradation are the key to improving the performance of carbon graphite material. Among them, Comparative Example 2 (without coating and active factor carbon) has the worst performance, and the performance of Comparative Examples 3 (without coating) and 4 (without active factor carbon) is significantly lower than that of Example 1, which shows that both coating and active factor contribute to improving density and strength, and they have a synergistic effect.

[0090] (3) From the comparison of Example 1 and Comparative Example 5, it can be seen that the addition of the modifier (coal tar) can effectively improve the wettability of the binder, thereby enhancing the binding force between the aggregate and the binder. Comparative Example 5, which does not add the modifier, has a significantly decreased bulk density and mechanical properties.

[0091] (4) From the comparison of Example 1 and Comparative Example 6, it can be seen that the modified coal pitch can provide a stronger binding network due to its high coking value, and the use of medium-temperature coal pitch (Comparative Example 6) can result in a significant decrease in material strength.

[0092] (5) From the comparison of Example 1 and Comparative Examples 7 and 8, it can be seen that the particle size and volatile content of the active factor carbon have a significant impact on the material properties. Comparative Example 7 (particle size 70 μm) has poor filling effect due to the excessively large particle size, and Comparative Example 8 (volatile content 30%) has a loose material structure and a sharp decrease in performance due to the excessive volatile content, which generates excessive gas during calcination.

[0093] (6) From the comparison of Example 1 and Comparative Example 9, it can be seen that the continuity of the aggregate gradation is the key to ensuring the homogeneity of the material structure. The lack of intermediate particle size aggregate (0.15-0.3 mm) can result in non-dense particle accumulation, increased porosity, and overall performance degradation.

[0094] (7) From Example 1, Example 4, and Example 5, it can be seen that there is an optimal addition amount of active factor carbon. From a technical perspective, the active factor carbon plays a dual role of sintering aid and fine filler. The active factor carbon has an extremely fine particle size (D50 of 8-15 μm), which can effectively fill into smaller pores formed by the accumulation of aggregates of different sizes, achieving denser particle accumulation. The volatile content in the active factor carbon slowly escapes in a controlled manner during calcination, promoting material transfer and diffusion between adjacent carbon particles at the microscale, thereby more effectively promoting the formation and growth of "sintering necks", inducing local shrinkage, and driving the overall material to develop towards higher density. However, excessive addition of the active factor carbon can result in excessive internal stress due to excessive volatile content, or can affect the rheological properties of the glue system due to excessive fine particles, thereby degrading the performance.

[0095] 2. The flexural and compressive stress curves of the calcined block prepared in Example 1 are shown in Figure 1 , and the micrographs of the surface and cross-section are shown in Figure 2 , wherein Figure 2 (a) is the micrograph of the surface at different magnifications, Figure 2 (b) is the micrograph of the cross-section at different magnifications. The actual photo of the calcined block prepared in Example 1 is shown in Figure 3 , and the specifications are 400 mm x 400 mm x 2000 mm.

[0096] From Figure 1It can be seen that the bending strength and compressive strength of Example 1 are 15.5 MPa and 55 MPa, respectively, and the bending and compressive curves of Example 1 show a smooth upward trend before reaching the peak value, without obvious mutation or sharp drop, indicating that the material deforms uniformly during the stress process, with few internal defects, showing good plasticity and toughness. The high peak strength (compressive strength 55 MPa, bending strength 15.5 MPa) and the gentle curve descending segment further prove that the material has excellent anti-fracture ability and energy absorption characteristics.

[0097] By Figure 2 It can be seen that the surface and cross section of the material show a three-dimensional interconnected pore structure similar to "ant nest". The pores are uniform in size, round in shape, without sharp angle cracks or large size destructive cracks. The pores are interconnected to form a network. The advantages of this structure are: 1) uniformly distributed pores can effectively disperse and release thermal stress, greatly improving performance; 2) interconnected pores provide a stable and uniform path for electron transport, thus making the resistivity stable and controllable; 3) the round pore wall avoids stress concentration, improving the mechanical reliability.

[0098] 3, the bending and compressive curves of the calcined block prepared in Comparative Example 1 are shown in Figure 4 , and the micro-morphology of the surface and cross section is shown in Figure 5 , wherein Figure 5 (a) is the micro-morphology of the surface at different magnifications, Figure 5 (b) is the micro-morphology of the cross section at different magnifications.

[0099] By Figure 4 It can be seen that the bending strength and compressive strength of Comparative Example 1 are 12 MPa and 32 MPa, respectively.

[0100] By Figure 5 It can be seen that the surface of the calcined block has many large pores, many sharp angle cracks and large cracks with strong destructive, and the pores are unevenly distributed; the existence of sharp angle cracks is prone to cause stress concentration, causing the calcined block to break. At the same time, it can be seen from the cross section morphology that the cracks of the calcined block are deep and large, and the structure is loose. Figure 6 , wherein Figure 6 The left graph corresponds to Comparative Example 7, and the right graph corresponds to Comparative Example 8. It can be seen from the graph that when the active factor carbon with suitable size lacks volatile content, the pore filling effect between coarse particle graphite is poor, causing uneven and large cracks to exist, which greatly deteriorates the performance.

[0101] 4, the surface micro-morphology of the calcined block prepared in Comparative Example 9 is shown in Figure 7As shown in the figure, when the calcined petroleum coke with particle size of [0.15mm, 0.3mm] is absent, the sintered block is uneven and has larger cracks, which indicates that the continuous gradation between coarse particle graphite particles is the key to ensure the uniform structure.

[0102] 5, the mercury intrusion data of the material prepared in example 1, comparative example 4 and comparative example 9 are shown in the figure Figure 8 As shown in the figure, the porosity of comparative example 9 is the largest, and the pore size is the largest, which further supports the above argument.

[0103] Finally, it should be pointed out that the above embodiments of the present application are only examples for illustrating the present application, and are not a limitation on the embodiments of the present application. For those skilled in the art, on the basis of the above description, other different forms of changes and variations can also be made. Here, all the embodiments cannot be exhausted. Any obvious changes or variations derived from the technical solutions of the present application still fall within the protection scope of the present application.

Claims

1. A method for preparing a carbon graphite material with an ant nest porous structure, characterized in that, Specifically comprising the following steps: (1) crushing and screening one or more of calcined pitch coke, calcined petroleum coke, needle coke, foamed carbon and carbon black to obtain five levels of aggregates, wherein the particle size of the first level of aggregate is [0.5mm, 0.9mm], the particle size of the second level of aggregate is [0.3mm, 0.5mm], the particle size of the third level of aggregate is [0.15mm, 0.3mm], the particle size of the fourth level of aggregate is [0.075mm, 0.15mm], and the particle size of the fifth level of aggregate is <0.075mm and D50 is 10-50um; (2) mixing the first level of aggregate with modified asphalt or resin solution, stirring uniformly at 80-120℃, and then carbonizing at 400℃ to obtain modified first level of aggregate; (3) mixing 15-30 parts of modified first level of aggregate, 10-20 parts of second level of aggregate, 10-30 parts of third level of aggregate, 10-20 parts of fourth level of aggregate and 10-40 parts of fifth level of aggregate to obtain mixed aggregate; (4) after drying the mixed aggregate at 120-160℃, heating to 160-240℃, adding 20-40 parts of molten binder and 1-3 parts of modifier, and uniformly wet mixing to obtain paste; (5) placing the paste in a preheated mold for molding to obtain a green body, then burying it in a buried burning material and placing it in a calcining furnace to obtain the carbon graphite material.

2. The method of claim 1, wherein the carbon graphite material having the ant nest hole structure is prepared by the steps of: The modified asphalt is low-temperature coal tar pitch; and the mass ratio of the first level of aggregate to the modified asphalt is (15-25):(1-10). ​ 3. The method of claim 1, wherein the carbon graphite material having the ant nest hole structure is prepared by the steps of: preparing a mixture of a carbon source and a graphite source; and sintering the mixture to form the carbon graphite material having the ant nest hole structure. The resin solution is a phenolic resin solution, and the concentration of the phenolic resin is 30%-60%; and the mass ratio of the first level of aggregate to the resin solution is (15-25):(1-10).

4. The method of producing a carbon graphite material having a nest hole structure according to claim 1, 2 or 3, characterized by, In step (3), 1-20 parts of active factor carbon are also contained; the volatile content of the active factor carbon is 3-10%.

5. The method of claim 4, wherein the carbon graphite material having the ant nest hole structure is prepared by the steps of: preparing a mixture of a carbon source and a graphite source; and sintering the mixture to form the carbon graphite material having the ant nest hole structure. The preparation method of the active factor carbon is as follows: one or more of mesophase coal pitch, anthracene oil and coal tar is placed in a tube furnace, then pyrolyzed at 300-450℃ for 2-10h under inert protective atmosphere; then the solid particles are collected, and then crushed, sieved and ground to D50 of 8-15um.

6. The method of claim 1, wherein the carbon graphite material having the ant nest hole structure is prepared by the steps of: In step (4), the modifier is one or more of coal tar, oleic acid and anthracene oil. ​ 7. The method of claim 1 or 6, wherein the carbon graphite material having the ant nest hole structure is prepared by the steps of: In step (4), the binder is modified coal pitch. ​ 8. The method of claim 1, wherein the carbon graphite material having the ant nest hole structure is prepared by the steps of: preparing a mixture of a carbon source and a graphite source; and sintering the mixture to form the carbon graphite material having the ant nest hole structure. In step (5), the molding temperature is 100-200℃, and the pressure is 1-10MPa.

9. The method of claim 1, wherein the carbon graphite material having the ant nest hole structure is prepared by the steps of: preparing a mixture of a carbon source and a graphite source; and sintering the mixture to form the carbon graphite material having the ant nest hole structure. In step (5), the green body is buried in the buried material before being baked, and then is placed in a baking furnace for baking. The temperature gradient is uniformly raised and lowered during baking. Specifically, the temperature in the furnace is raised from room temperature to 100 DEG C in 3-4 h, then to 200 DEG C in 4-6 h, and then to 350 DEG C in 6-9 h, to 450 DEG C in 16-20 h, to 550 DEG C in 18-24 h, to 700 DEG C in 5-8 h, to 800 DEG C in 6-10 h, to 900 DEG C in 4-6 h, to 1050 DEG C in 2-5 h, then kept at 1050 DEG C for 4-6 h, and finally lowered to 200 DEG C at a constant speed in 25-30 h, and then naturally cooled to room temperature.

10. A carbon graphite material having a nest of holes structure, characterized by, The carbon graphite material with ant nest hole structure is prepared by the method of any one of claims 1-9.

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