A carbon / carbon composite material and preparation method thereof

Abstract

The invention discloses a carbon / carbon composite material and a preparation method thereof, belonging to the field of composite materials. The method comprises the following steps: S1, taking carbon felt, making blanks after pickling and first high-temperature purification, making powder after PIP process and first CVD process, and obtaining material A after second CVD process; S2, mixing material A, petroleum coke and graphite powder in a mass ratio of (30-60): (30-60): (5-10) to obtain material B; S3, taking carbon fiber, preparing a PyC interface layer on the surface of carbon fiber through a third CVD process; S4, mixing material B, carbon fiber, asphalt powder and additive in a mass ratio of (30-80): (1-20): (1-30): (1-3) to obtain material C; S5, preparing blank material through a molding process; S6, densifying and purifying the blank material. The invention has a short preparation cycle and low cost. The finished product has good mechanical properties and electrical conductivity, high density, low and uniform porosity, does not fall off or slag after long-term use, and has good corrosion resistance and aging resistance.

Description

Technical Field

[0001] The invention belongs to the field of composite materials, and in particular relates to a carbon / carbon composite material and a preparation method thereof. Background Art

[0002] Advanced carbon-based composite materials refer to composite materials that use fiber as reinforcement, carbon as matrix, and are formed by chemical vapor deposition or liquid phase impregnation. At present, advanced carbon-based composite materials are being used in photovoltaics, semiconductors, negative electrode materials, brakes and other fields.

[0003] In the traditional single crystal furnace thermal field system, carbon fiber is often used to weave a three-dimensional preform carbon-based material or graphite material. The carbon fiber preform carbon-based material needs to be preformed first, and needs to be repeatedly impregnated and carbonized to increase the fixed carbon content in the carbon matrix. The molding cycle is long and the price cost is high. In addition, some carbon fibers will be exposed during the production process. For example, Chinese patent CN100389094C discloses a method for preparing a composite material of carbon fiber and pyrolytic carbon matrix mesophase asphalt over-plating, which requires cutting and stacking 3K carbon cloth and piercing them together in the Z direction to make a carbon fiber preform, and then impregnating it; Chinese patent application CN115849930A discloses a method for preparing a low-cost and high-thermal conductivity carbon / carbon composite material, which requires mixing and combing low-modulus short-cut mesophase asphalt-based carbon fiber and PAN-based carbon fiber to make a mesh tire, axially needle-punching to obtain a needle-punched integral felt preform, and then the matrix blank obtained by chemical vapor deposition needs to be subjected to two-stage graphitization treatment. Graphite materials are often used in single crystal furnace thermal field systems due to their high resistivity and uniform density. However, as the use time increases, graphite materials will begin to shed powder, polluting the environment around the product and increasing the product cleaning procedures. Summary of the invention

[0004] The problem to be solved by the present invention is to provide a carbon / carbon composite material and a preparation method thereof, wherein the finished product has good mechanical properties and electrical conductivity, and has high density, uniform pores, a short preparation cycle and low cost.

[0005] The present invention includes a method for preparing a carbon / carbon composite material, comprising the following steps:

[0006] S1, take carbon felt, make blanks after pickling and first high-temperature purification, make powder after PIP process and first CVD process, and obtain material A after second CVD process;

[0007] S2. Material A, petroleum coke and graphite powder are fully mixed in a mass ratio of (30-60): (30-60): (5-10) to obtain material B;

[0008] S3, taking carbon fiber, and preparing a PyC interface layer on the surface of the carbon fiber through a third CVD process;

[0009] S4. Fully mix material B, carbon fiber, asphalt powder, and additives in a mass ratio of (30-80): (1-20): (1-30): (1-3) to obtain material C;

[0010] S5, after pressing or extruding material C, carbonization-high pressure impregnation-carbonization treatment is performed to obtain a green body material;

[0011] S6. Densification and purification are performed on the green body material to obtain a carbon / carbon composite material.

[0012] Furthermore, in S1, the carbon felt is a thermal field material or a heat-insulating material in a vacuum sintering furnace, a carbon deposition furnace or other high-temperature furnaces.

[0013] Furthermore, in S1, the first high temperature purification process includes:

[0014] In the first high-temperature purification stage, the room temperature is raised to 1200°C for 8 to 12 hours;

[0015] The second high-temperature purification stage, the temperature is raised from 1200°C to 1800°C for 10 to 14 hours;

[0016] The third high-temperature purification stage, the temperature is raised from 1800°C to 2400-2600°C for 20-24 hours;

[0017] The fourth high-temperature purification stage is to keep the temperature at 2400-2600°C for 4-6 hours.

[0018] Furthermore, S1 includes 1 to 3 cycles of the PIP process and 1 to 2 cycles of the first CVD process.

[0019] Furthermore, in S2, the petroleum coke is low-sulfur calcined petroleum coke, the graphite powder is worm graphite, and the particle size of material B is 60-800 mesh.

[0020] Furthermore, in S3, the carbon fiber is subjected to a third CVD process after being debonded, and the heating temperature of the debonding treatment is 800-1000° C., and the heating time is 2-5 hours.

[0021] Furthermore, in S3, the carbon source of the third CVD process is one or more of natural gas, propane, and propylene, the carrier gas is nitrogen, the deposition temperature is 950° C., and the deposition time is 40 to 60 hours.

[0022] Furthermore, in S6, the densification treatment adopts the CVI process, the carbon source of the CVI process is any one or more of propane, propylene or natural gas, the carrier gas is an inert gas, the temperature is 980-1050°C, and the deposition time is 100-120h.

[0023] Furthermore, in S6, the purification process is a second high temperature purification, including:

[0024] In the first stage, the temperature is raised from room temperature to 600°C for 3 to 4 hours;

[0025] The second stage, heating from 600℃ to 1000℃, time 5 to 14h;

[0026] The third stage, heating from 1000℃ to 1600℃, time 10~14h;

[0027] The fourth stage, heating from 1600°C to 2200°C, time 20-24h;

[0028] The fifth stage is to keep warm at 2200℃ for 4 to 6 hours.

[0029] A carbon / carbon composite material, prepared by any of the above-mentioned methods for preparing a carbon / carbon composite material, comprising the following components by weight percentage:

[0030] Solid filling carbon: 50-70wt%;

[0031] Carbon fiber: 5-20wt%;

[0032] Pitch carbon: 5-15wt%;

[0033] Pyrolytic carbon: 10-25wt%; the sum of all components is 100wt%.

[0034] Beneficial effects of the present invention:

[0035] (1) The present invention uses recycled carbon felt as raw material. After the carbon felt is subjected to acid washing, first high-temperature purification, PIP process and first CVD process, a uniform, stable powder with a high fixed carbon content is obtained. A matrix with a high fixed carbon content is introduced during blank making, thereby eliminating the repeated impregnation-carbonization process in traditional preform molding, greatly saving the molding cycle. The carbon felt is first powdered and then blanked, thereby avoiding the phenomenon of exposed carbon fibers as in traditional carbon fiber preform matrix, and also avoiding the problem of powder shedding as in graphite materials. At the same time, the carbon felt used in the present invention has the characteristics of recycling and reuse, and can be recycled and processed scraps for remolding, thereby reducing waste and improving economic benefits.

[0036] (2) The present invention introduces graphite powder during blank making to fill the pores of the blank during blank forming, thereby strengthening the overall structure, avoiding the high density on the outside, low density between, and high porosity that are often seen in traditional carbon / carbon composite materials, and improving the product density.

[0037] (3) The carbon / carbon composite material prepared by the present invention has uniform material, low porosity, and good processing performance. Compared with the carbon / carbon composite material formed by the traditional preform, the mechanical properties are equivalent, and the defects of the traditional carbon / carbon composite material such as uneven density, high porosity, and surface sealing leading to difficulty in densification are compensated, and it has better electrical conductivity, corrosion resistance and high temperature stability; compared with graphite, the electrical conductivity is equivalent, and it has better bending, compression, tensile strength and processing performance, and has better integrity and surface performance, does not drop dust, does not leave marks, and will not crack and float under long-term use. The electrode prepared by the carbon / carbon composite material of the present invention compensates for the defects of differentiation and electrical performance degradation of the traditional carbon / carbon composite electrode during use, has low power consumption and long life during use, and can be fully applied to the field of heaters and electrodes.

[0038] (4) The present invention adopts pressing or extrusion molding, and can prepare a blank of corresponding shape and size according to product requirements, and has great compatibility with products of different sizes. The thickness of the pressed product can reach 150mm, and the product density can reach 1.7g / cm 3 , the pores are uniform. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Attached Figure 1 A flow chart of a method for preparing a carbon / carbon composite material according to an embodiment of the present invention;

[0040] Attached Figure 2 is a bending stress-strain curve diagram of the carbon / carbon composite material in Example 1 of the present invention;

[0041] Attached Figure 3 is a bending stress-strain curve diagram of the carbon / carbon composite material in Example 2 of the present invention;

[0042] Attached Figure 4 This is a bending stress-strain curve of the carbon / carbon composite material in Example 3 of the present invention. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific implementation methods. It should be understood that the specific implementation methods described herein are only used to explain the present invention and are not intended to limit the present invention.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items. In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0045] As attached Figure 1 As shown, an embodiment of the present invention provides a method for preparing a carbon / carbon composite material, comprising the following steps:

[0046] S1. Raw material processing: take carbon felt, remove impurities by pickling, make blanks after the first high-temperature purification, and then make powder after the PIP process and the first CVD process. After the second CVD process, the pyrolytic carbon is fully coated on the powder to obtain material A;

[0047] S2. Matrix configuration: Material A, petroleum coke and graphite powder are fully mixed in a mass ratio of (30-60): (30-60): (5-10) to obtain material B;

[0048] S3, fiber treatment: taking carbon fiber precursor, and preparing a PyC interface layer on the surface of the carbon fiber for protecting the carbon fiber by a third CVD process;

[0049] S4, blank preparation: fully mix material B, carbon fiber, asphalt powder, and additives in a mass ratio of (30-80): (1-20): (1-30): (1-3) to obtain material C;

[0050] S5, green body forming: putting material C into a forming mold for pressing or extrusion forming, and then performing carbonization-high pressure impregnation-carbonization treatment to obtain a green body material;

[0051] S6. Densification and purification treatment: After the green body material is densified by the CVI process and purified at high temperature for the second time, a high-density carbon fiber reinforced carbon-based composite material is obtained.

[0052] The present invention can use carbon felt as a raw material, and introduce a matrix with a relatively high fixed carbon content during blank making. After the carbon felt is subjected to pickling and impurity removal, the first high-temperature purification, the PIP process and the first CVD process, a uniform, stable powder with a high fixed carbon content is obtained, which eliminates the repeated impregnation-carbonization process in the traditional preform molding, greatly saving the molding cycle. The carbon felt is first powdered and then blanked, which avoids the phenomenon of carbon fiber exposure as in the traditional carbon fiber preform matrix, and also avoids the problem of powder loss as in the graphite material. By introducing graphite during blank making, the pores of the blank can be filled during blank molding, and the overall structure can be enhanced, avoiding the phenomenon of high outer density, low density between, and high porosity that often occur in traditional carbon / carbon composite materials. Pressing or extrusion molding is used to increase the density of the product, and blanks of corresponding shapes and sizes can be prepared according to product requirements. It has greater compatibility with products of different sizes, and the thickness of the pressed product can reach 150 mm, and the product density can reach 1.7 g / cm 3 .

[0053] The carbon / carbon composite material prepared by the present invention has uniform material, low porosity and good processing performance. Compared with the carbon / carbon composite material formed by traditional preforms, the mechanical properties are equivalent, and the defects of uneven density, high porosity and difficult densification caused by surface sealing of traditional carbon / carbon composite materials are compensated, and the material has better electrical conductivity, corrosion resistance and high-temperature stability; compared with graphite, the electrical conductivity is equivalent, and the material has better bending, compression and tensile strength and processing performance, and has better integrity and surface performance, does not shed dust or leave marks, and will not crack or float under long-term use; the electrode prepared by using the carbon / carbon composite material of the present invention compensates for the defects of differentiation and electrical performance degradation of traditional carbon / carbon composite electrodes during use, has low power consumption and long service life during use, and can be fully applied to the fields of heaters and electrodes.

[0054] In a preferred embodiment, the solidified carbon felt recycled and reused in S1 can preferably be selected from the thermal field material or thermal insulation material in a vacuum sintering furnace, a carbon deposition furnace or a gas pressure high temperature furnace. The fixed carbon felt has a relatively high fixed carbon content. The recycled carbon felt is used as the raw material for the preparation of the matrix. The matrix with a relatively high fixed carbon content is introduced during the blank making, which saves the long densification cycle in the traditional preform molding. At the same time, the carbon felt used in the present invention has the characteristics of recycling and reuse, and the processing scraps can be recycled and re-molded, which reduces waste, greatly saves the cost of raw materials, and improves economic benefits.

[0055] In a preferred embodiment, in S1, the first high temperature purification comprises:

[0056] In the first high-temperature purification stage, the room temperature is raised to 1200°C for 8 to 12 hours;

[0057] The second high-temperature purification stage, the temperature is raised from 1200°C to 1800°C for 10 to 14 hours;

[0058] The third high-temperature purification stage, the temperature is raised from 1800°C to 2400-2600°C for 20-24 hours;

[0059] The fourth high-temperature purification stage is to keep the temperature at 2400-2600°C for 4-6 hours.

[0060] After high-temperature purification, the properties of carbon felt are close to those of graphite, and it can be fully used as the matrix of carbon / carbon composite materials, eliminating the multiple infiltration processes of carbon / carbon composite materials in traditional preform molding, overcoming the shortcomings of long molding cycle and high porosity. The prepared green body has low porosity and uniform material.

[0061] Preferably, the pickling and impurity removal is carried out at a temperature below room temperature to further ensure the purity and fixed carbon content of the carbon felt.

[0062] In a preferred embodiment, S1 includes 1 to 3 cycles of PIP process and 1 to 2 cycles of the first CVD process to avoid problems such as uneven performance, uncontrollable particle size or uneven specific gravity in each powder making. The PIP process can quickly increase the specific gravity of carbon to harden the powder, and the first CVD process can ensure the uniformity and completeness of the powder making.

[0063] In a preferred embodiment, to obtain a high-density carbon / carbon composite material, in S2, the mass ratio of material A, petroleum coke, and graphite powder is 58:35:7, and the mass ratio of material B, carbon fiber, asphalt powder, and additive is 58:15:25:2.

[0064] In a preferred embodiment, to obtain a high-density carbon / carbon composite material, in S2, the mass ratio of material A, petroleum coke, and graphite powder is 55:37:8, and the mass ratio of material B, carbon fiber, asphalt powder, and additive is 62:15:20:3.

[0065] In a preferred embodiment, to obtain a high-density carbon / carbon composite material, in S2, the mass ratio of material A, petroleum coke, and graphite powder is 50:40:10, and the mass ratio of material B, carbon fiber, asphalt powder, and additive is 57:20:20:3.

[0066] In a preferred embodiment, in S2, the petroleum coke is low-sulfur calcined petroleum coke, and the graphite powder is worm graphite. The impurity content of petroleum coke can be reduced after calcination, and the low-sulfur calcined petroleum coke can be used as a carburizer. When the prepared carbon / carbon composite material is used as an electrode material, the high-temperature strength and electrical conductivity of the electrode can be improved. Worm graphite has the characteristics of being difficult to decompose, deform, and age, and has stable electrical conductivity, thermal conductivity, and chemical properties, and good lubricity. It can fully fill the pores of the blank in the blank making stage, improve the density and uniformity of the product, improve the overall structure of the blank, make the cross-sectional gap of the product smaller, and its state remains unchanged after the blank is treated at high temperature. Preferably, the particle size of material B is 60 to 800 mesh to ensure the uniformity of the blank.

[0067] In a preferred embodiment, S3 further includes performing a degumming treatment on the carbon fiber precursor before the third CVD process, specifically vacuum heating degumming, slowly heating to 800-1000°C, and keeping warm for 2-5 hours under vacuum to remove the sizing agent on the surface of the carbon fiber precursor to expose the carbon fiber. Preferably, the carbon fiber can be further cut into chopped carbon fiber according to the product size requirements.

[0068] In a preferred embodiment, in S3, the third CVD process is specifically as follows: the carbon fibers after the debonding treatment are placed in an orderly interval, suspended in a CVD deposition furnace, and the carbon source gas is introduced into the furnace under the protection of a carrier gas, wherein the carbon source is one or more of natural gas, propane, and propylene, the carrier gas is nitrogen, the deposition temperature is 950°C, and the deposition time is 40 to 60 hours. The PyC interface is prepared on the surface of the carbon fiber through the third CVD process, and the pyrolytic carbon can effectively protect the carbon fiber and improve the strength and aging resistance of the carbon fiber.

[0069] In a preferred embodiment, in S4, the additives include particulate reinforcement, lubricant (such as flake graphite), curing agent and stabilizer, etc., wherein the curing agent includes resin for enhancing the structural stability of the blank, which is converted into a carbon matrix after carbonization or high temperature.

[0070] In a preferred embodiment, in S6, the densification treatment adopts a CVI process, the carbon source of the CVI process is any one or more of propane, propylene or natural gas, the carrier gas is an inert gas, the temperature is 980-1050° C., and the deposition time is 100-120 hours. The CVI process densifies the green body material, enhances the bonding force of the base member, improves the anti-oxidation ability, and enhances the product strength.

[0071] In a preferred embodiment, in S6, the purification process is specifically to improve the high temperature purity and high temperature performance of the product by a second high temperature purification, and the second high temperature purification includes:

[0072] In the first stage, the temperature is raised from room temperature to 600°C for 3 to 4 hours;

[0073] The second stage, heating from 600℃ to 1000℃, time 5 to 14h;

[0074] The third stage, heating from 1000℃ to 1600℃, time 10~14h;

[0075] The fourth stage, heating from 1600°C to 2200°C, time 20-24h;

[0076] The fifth stage is to keep warm at 2200℃ for 4 to 6 hours.

[0077] The present invention also provides a carbon / carbon composite material, which is prepared by the method for preparing the carbon / carbon composite material in any of the above embodiments and consists of the following components by weight percentage:

[0078] Solid filling carbon: 50-70wt%;

[0079] Carbon fiber: 5-20wt%;

[0080] Pitch carbon: 5-15wt%;

[0081] Pyrolytic carbon: 10-25wt%; the sum of all components is 100%.

[0082] In the carbon fiber reinforced carbon-based composite material prepared in the embodiment of the present invention, asphalt powder is added during the preparation of the matrix. The asphalt powder has good fluidity after softening, and the crystallization of the asphalt powder helps the green body to be formed. After high-temperature pressure treatment, the asphalt powder is converted into asphalt carbon. The pyrolytic carbon can enhance the binding force inside the matrix, improve the antioxidant capacity of the product, improve the stability of the raw materials, control the particle size and specific gravity, and the asphalt carbon and pyrolytic carbon fill the pores of the matrix, so that the prepared carbon / carbon composite material has high density and uniform pores.

[0083] Example 1

[0084] This embodiment provides a method for preparing a carbon / carbon composite material, comprising the following steps:

[0085] S1. Raw material processing: select the insulation hard felt recovered from the high-temperature purification furnace, remove impurities by pickling at a temperature below room temperature, make blanks after the first high-temperature purification, make powder after the PIP process and the first CVD process, and process the obtained powder by the second CVD process so that the pyrolytic carbon fully covers the powder to obtain material A;

[0086] The first high-temperature purification is as follows: in the first high-temperature purification stage, the temperature is raised from room temperature to 1200°C for 9 hours; in the second high-temperature purification stage, the temperature is raised from 1200°C to 1800°C for 12 hours; in the third high-temperature purification stage, the temperature is raised from 1800°C to 2600°C for 20 hours; in the fourth high-temperature purification stage, the temperature is kept at 2600°C for 4 hours;

[0087] Among them, the fixed carbon content of the hard felt was measured to be 98%;

[0088] S2. Matrix configuration: Material A, low-sulfur calcined petroleum coke and vermicular graphite are fully mixed in a mass ratio of 58:35:7 to obtain material B, wherein the particle sizes of material A, low-sulfur calcined petroleum coke and vermicular graphite are all 250 meshes;

[0089] S3, fiber treatment: take the carbon fiber precursor and slowly heat it to 1000℃, keep it warm for 3h in a vacuum environment, place the carbon fibers in an orderly interval, suspend them in a CVD furnace, pass the carbon source gas into the furnace under the protection of carrier gas, so that the pyrolytic carbon is fully attached to the surface of the carbon fiber, wherein the carbon source gas is propylene, the deposition temperature is 1000℃, the deposition time is 40h, and the treated carbon fiber is cut into 7mm short carbon fiber;

[0090] S4, blank preparation: material B, chopped carbon fiber, asphalt powder, and additives are fully mixed in a mass ratio of 58:15:25:2 to obtain material C;

[0091] S5, green body forming: putting material C into a forming mold for pressing or extrusion forming, and then performing carbonization-high pressure impregnation-carbonization treatment to obtain a green body material;

[0092] S6, densification and purification treatment: After the green body material is densified by the CVI process and purified at high temperature for the second time, a high-density carbon fiber reinforced carbon-based composite material is obtained;

[0093] The CVI process uses propylene as the carrier gas, 980°C for 120 h, and nitrogen as the inert gas;

[0094] Among them, the second high-temperature purification is specifically as follows: in the first stage, the room temperature is heated to 600°C for 3 hours; in the second stage, the temperature is heated from 600°C to 1000°C for 5 hours; in the third stage, the temperature is heated from 1000°C to 1600°C for 11 hours; in the fourth stage, the temperature is heated from 1600°C to 2200°C for 23 hours; in the fifth stage, the temperature is kept at 2200°C for 6 hours.

[0095] The carbon / carbon composite material prepared in this embodiment is composed of the following components in weight percentage: 57wt% solid filled carbon, 15wt% carbon fiber, 13.5wt% pitch carbon, and 14.5wt% pyrolytic carbon, and the sum of each component is 100%.

[0096] Example 2

[0097] This embodiment provides a method for preparing a carbon / carbon composite material. In S2, the mass ratio of material A, low-sulfur calcined petroleum coke, and worm graphite is 55:37:8. In S4, the mass ratio of material B, chopped carbon fiber, asphalt powder, and additives is 62:15:20:3. Other steps and parameter settings are the same as those in Example 1.

[0098] The carbon / carbon composite material prepared in this embodiment is composed of the following components in weight percentage: 60.9wt% solid filling carbon, 20wt% carbon fiber, 10.8wt% pitch carbon, and 8.3wt% pyrolytic carbon, and the sum of the components is 100%.

[0099] Example 3

[0100] The present embodiment provides a method for preparing a carbon / carbon composite material. In S2, the mass ratio of material A, low-sulfur calcined petroleum coke, and worm graphite is 50:40:10. In S4, the mass ratio of material B, chopped carbon fiber, asphalt powder, and additive is 57:20:20:3. Other steps and parameter settings are the same as those in Example 1.

[0101] The carbon / carbon composite material prepared in this embodiment is composed of the following components in weight percentage: 56wt% solid filled carbon, 10wt% carbon fiber, 15wt% pitch carbon, and 19wt% pyrolytic carbon, and the sum of the components is 100%.

[0102] Based on the above examples 1-3, the density, tensile strength, flexural strength and resistivity of the prepared carbon / carbon composite materials were measured. The measurement results are shown in the attached Figure 2-4 And as shown in Table 1.

[0103] Table 1 Performance test data of carbon / carbon composite materials prepared in Examples 1-3

[0104] Example Thickness(mm) <![CDATA[Density (g / cm 3 )]]> Bending strength(MPa) Resistivity (Ω·m) 1 100 1.7 98 20-25 2 8 1.75 106 20-25 3 35 1.7 81 15-18

[0105] Compared with the traditional carbon fiber preform carbon-based material, the carbon / carbon composite material prepared in the embodiment of the present invention overcomes the problem of fiber exposure, has uniform density and stable structure; the density of commercially available graphite products is 1.75-1.85 g / cm 3 The bending strength is about 40 MPa, and the resistivity ranges from 8 to 15 Ω·m. Compared with the graphite material, the carbon / carbon composite material prepared in the embodiment of the present invention makes up for its defects in strength and corrosion resistance, and does not have the phenomenon of powder falling.

[0106] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0107] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

[0108] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. A method for preparing a carbon / carbon composite material, Features: The following steps are involved: S1, take carbon felt, make blanks after pickling and first high-temperature purification, make powder after PIP process and first CVD process, and obtain material A after second CVD process; S2. Material A, petroleum coke and graphite powder are fully mixed in a mass ratio of (30-60): (30-60): (5-10) to obtain material B; S3, taking carbon fiber, and preparing a PyC interface layer on the surface of the carbon fiber through a third CVD process; S4, fully mixing the material B, the carbon fiber, the asphalt powder, and the additive in a mass ratio of (30-80): (1-20): (1-30): (1-3) to obtain a material C; S5, after pressing or extruding the material C, performing carbonization-high pressure impregnation-carbonization treatment to obtain a green body material; S6. Densification and purification are performed on the green body material to obtain a carbon / carbon composite material.

2. A method for preparing a carbon / carbon composite material according to claim 1, Features: In S1, the carbon felt is a thermal field material or a heat-insulating material in a vacuum sintering furnace, a carbon deposition furnace or other high-temperature furnaces.

3. A method for preparing a carbon / carbon composite material according to claim 1, Features: In S1, the first high temperature purification process includes: In the first high-temperature purification stage, the room temperature is raised to 1200°C for 8 to 12 hours; The second high-temperature purification stage, the temperature is raised from 1200°C to 1800°C, the time is 10~14h; The third high-temperature purification stage, the temperature is raised from 1800°C to 2400~2600°C for 20~24h; The fourth high-temperature purification stage is to keep the temperature at 2400-2600°C for 4-6 hours.

4. The method for preparing a carbon / carbon composite material according to claim 1, Features: The S1 includes 1 to 3 cycles of the PIP process and 1 to 2 cycles of the first CVD process.

5. The method for preparing a carbon / carbon composite material according to claim 1, Features: In S2, the petroleum coke is low-sulfur calcined petroleum coke, the graphite powder is worm graphite, and the particle size of the material B is 60-800 mesh.

6. A method for preparing a carbon / carbon composite material according to claim 1, Features: In S3, the carbon fiber is subjected to the third CVD process after being subjected to the degumming treatment, and the heating temperature of the degumming treatment is 800-1000° C. and the heating time is 2-5 hours.

7. A method for preparing a carbon / carbon composite material according to claim 1, Features: In S3, the carbon source of the third CVD process is one or more of natural gas, propane, and propylene, the carrier gas is nitrogen, the deposition temperature is 950° C., and the deposition time is 40 to 60 hours.

8. The method for preparing a carbon / carbon composite material according to claim 1, Features: In S6, the densification treatment adopts CVI process, the carbon source of the CVI process is any one or more of propane, propylene or natural gas, the carrier gas is inert gas, the temperature is 980-1050° C., and the deposition time is 100-120 hours.

9. The method for preparing a carbon / carbon composite material according to claim 1, Features: In S6, the purification process is a second high-temperature purification, including: In the first stage, the temperature is raised from room temperature to 600°C for 3 to 4 hours; The second stage, heating from 600℃ to 1000℃, time 5~14h; The third stage, heating from 1000℃ to 1600℃, time 10~14h; The fourth stage, heating from 1600℃ to 2200℃, time 20~24h; The fifth stage: keep warm at 2200℃ for 4~6h.

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