A carbon-carbon composite material, its preparation method and use

Abstract

The present application belongs to the technical field of carbon materials, and particularly relates to a carbon-carbon composite material, a preparation method and application thereof. The carbon fiber preform is repeatedly subjected to chemical vapor deposition carbon densification, the obtained densified carbon-carbon material blank is subjected to graphitization heat treatment under a protective atmosphere to obtain a graphitized carbon-carbon material; the graphitized carbon-carbon material is subjected to finishing, and the obtained finished graphitized carbon-carbon material is subjected to purification treatment under a purification gas and a protective gas to obtain a purified carbon-carbon material; and the purified carbon-carbon material is subjected to heat treatment to obtain a carbon-carbon composite material. The carbon-carbon composite material with high density and high air permeability is prepared through a chemical vapor deposition process and a purification process, the air permeable ring prepared from the carbon-carbon composite material meets the use requirements of a photovoltaic thermal field, the thermal field mechanical property is higher, the service life is longer, and the energy consumption is lower, the production cost of enterprises can be reduced, and the increasing demand for photovoltaic thermal field accessories can be met.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of carbon materials, and particularly relates to a carbon-carbon composite material and a preparation method and application thereof. BACKGROUND

[0002] With the continuous development of science and technology, the carbon industry is also progressing, and the demand for special carbon materials is also increasing. Porous carbon materials have rich pore structures and are widely used in various fields. In the field of carrier chip manufacturing, such as the high-temperature furnace used in the growth process of single crystal materials, the porous gas permeable plate inside needs to regulate the temperature field and adjust the air flow. It not only needs to have a certain high-temperature strength, but also needs to have a suitable pore size distribution and air permeability. However, the current porous carbon materials (such as activated carbon) are mostly in powder form. On the one hand, the porous material in powder form does not have self-supporting properties and cannot be used in a stacked state. On the other hand, the air permeability of the stacked powder is poor, and it may cause dust pollution, so it cannot be applied in these fields.

[0003] At present, the gas permeable ring for single crystal silicon drawing furnace generally uses graphite gas permeable ring, but graphite material is brittle, easy to be knocked and deformed during transportation, and has poor high-temperature mechanical properties, short service life and high replacement frequency, which greatly increases the production cost of enterprises. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a carbon-carbon composite material and a preparation method and application thereof. The carbon-carbon composite material prepared by the present application has high density, high air permeability and excellent high-temperature mechanical properties, and has a long service life. The gas permeable ring prepared by the present application is more suitable for application in the photovoltaic thermal field.

[0005] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0006] The present application provides a preparation method of a carbon-carbon composite material, comprising the following steps:

[0007] The carbon fiber preform is repeatedly densified by chemical vapor deposition carbon, and the obtained densified carbon-carbon material blank is subjected to graphitization heat treatment under a protective atmosphere to obtain a graphitized carbon-carbon material;

[0008] The graphitized carbon-carbon material is subjected to finishing, and the obtained finished graphitized carbon-carbon material is subjected to purification treatment in a mixed atmosphere of a purification gas and a protective gas to obtain a purified carbon-carbon material;

[0009] The purified carbon-carbon material is subjected to heat treatment to obtain a carbon-carbon composite material.

[0010] Preferably, the density of the carbon fiber preform is 0.2-0.4 g / cm 3 .

[0011] Preferably, the chemical vapor deposition carbon densification conditions include: the carbon source gas used for deposition is methane or propylene, the flow rate of the carbon source gas is 1-20 m 3 / h, the deposition temperature is 1000-1200℃, the deposition pressure is 2.0-10.0 kPa, the number of repetitions is 2-3, and the deposition time of each repetition is 100-300 h.

[0012] Preferably, the graphitization heat treatment temperature is 1800-2300℃, the holding time is 1-4 h, the temperature rising rate to the graphitization heat treatment temperature is 80-120℃ / h, and the protective atmosphere is argon.

[0013] Preferably, the purification gas is freon, the protective gas is argon, and the purification treatment temperature is 2000-2500℃.

[0014] Preferably, the heat treatment temperature is 1800-2300℃, the holding time is 8-12 h, the temperature rising rate to the heat treatment temperature is 80-120℃ / h, the heat treatment is carried out in a protective atmosphere, and the protective atmosphere is argon.

[0015] Preferably, the finishing is polishing.

[0016] Preferably, the density of the graphitized carbon carbon material is 1.6-1.8 g / cm 3 .

[0017] The present application also provides a carbon carbon composite material prepared by the preparation method described in the above technical solution, wherein the density of the carbon carbon composite material is 1.6-1.8 g / cm 3 , the air permeability is 5.5×10 -4 -8.5×10 -4 cm 3 / (m 2 ·d·Pa), the thermal expansion coefficient is 7.5×10 -6 -8.5×10 -6 / K, and the thermal conductivity is 40-50 W / mK.

[0018] The present application also provides an application of the carbon carbon composite material described in the above technical solution in preparing a gas permeable ring.

[0019] The application provides a preparation method of carbon-carbon composite material, comprising the following steps: repeatedly performing chemical vapor deposition carbon densification on a carbon fiber preform, performing graphitization heat treatment on the obtained densified carbon-carbon material blank in a protective atmosphere to obtain a graphitized carbon-carbon material; performing finishing on the graphitized carbon-carbon material, and performing purification treatment on the obtained finished graphitized carbon-carbon material in a mixed atmosphere of a purification gas and a protective gas to obtain a purified carbon-carbon material; and performing heat treatment on the purified carbon-carbon material to obtain a carbon-carbon composite material. Through the chemical vapor deposition process and the purification process, the carbon-carbon composite material with high density and high air permeability is prepared, the air permeable ring prepared from the carbon-carbon composite material meets the use requirements of a photovoltaic thermal field, the thermal field mechanical property is higher, the service life is longer, the energy consumption is lower, the production cost of enterprises can be reduced, and the increasing demand for photovoltaic thermal field accessories can be met.

[0020] The carbon-carbon composite material air permeable ring for the photovoltaic thermal field is prepared by combining the chemical vapor deposition process and the purification process, has the advantages of simple process, convenient operation, short preparation period, low production cost, excellent high-temperature mechanical property, long service life and the like, and provides a practical and effective method for large-scale industrial production. DETAILED DESCRIPTION

[0021] The application provides a preparation method of carbon-carbon composite material, comprising the following steps:

[0022] The carbon fiber preform is repeatedly subjected to chemical vapor deposition carbon densification, and the obtained densified carbon-carbon material blank is subjected to graphitization heat treatment in a protective atmosphere to obtain a graphitized carbon-carbon material.

[0023] The graphitized carbon-carbon material is subjected to finishing, and the obtained finished graphitized carbon-carbon material is subjected to purification treatment in a mixed atmosphere of a purification gas and a protective gas to obtain a purified carbon-carbon material.

[0024] The purified carbon-carbon material is subjected to heat treatment to obtain a carbon-carbon composite material.

[0025] Unless otherwise specified, the application does not have special requirements for the source of the used preparation raw materials, and commercially available goods known to those skilled in the art can be used.

[0026] The carbon fiber preform is repeatedly subjected to chemical vapor deposition carbon densification to obtain a densified carbon-carbon material blank.

[0027] In the application, the preparation method of the carbon fiber preform is preferably weaving with carbon fibers to form a shape to obtain the carbon fiber preform.

[0028] In the application, the structure of the weaving is preferably a needle punching structure, and the weaving forming is preferably alternately stacking and needle punching of no-woven fabric and ultra-thin net tire and using Z-direction carbon fibers to penetrate in two directions.

[0029] In the present application, the density of the carbon fiber preform is preferably 0.2-0.4 g / cm 3 , more preferably 0.25-0.35 g / cm 3 .

[0030] In the present application, the conditions of the chemical vapor deposition carbon densification include: the carbon source gas used for deposition is preferably methane or propylene, more preferably methane, the flow rate of the carbon source gas is preferably 1-20 m 3 / h, more preferably 5-15 m 3 / h; the deposition temperature increasing rate is preferably 40-80 ℃ / h, more preferably 50-70 ℃ / h, the deposition temperature is preferably 1000-1200 ℃, more preferably 1050-1150 ℃, the deposition pressure is preferably 2.0-10.0 kPa, more preferably 5-8 kPa; the number of repetitions is preferably 2-3 times, more preferably 3 times, and the time for each deposition is preferably 100-300 h, more preferably 150-250 h.

[0031] In the present application, the chemical vapor deposition carbon densification is preferably performed by using a graphite sleeve to build a tooling for the carbon fiber preform and then performing chemical vapor deposition carbon densification in a CVD gas phase deposition furnace.

[0032] After obtaining the densified carbon-carbon material blank, the present application performs graphitization heat treatment on the densified carbon-carbon material blank under a protective atmosphere to obtain a graphitized carbon-carbon material.

[0033] In the present application, the temperature of the graphitization heat treatment is preferably 1800-2300 ℃, more preferably 2000-2200 ℃, the holding time is preferably 1-4 h, more preferably 2-3 h; the temperature increasing rate for increasing the temperature to the graphitization heat treatment temperature is preferably 80-120 ℃ / h, more preferably 90-110 ℃ / h; the protective atmosphere is preferably argon; the purity of the argon is preferably ≥99.9%, more preferably ≥99.99%.

[0034] In the present application, the density of the graphitized carbon-carbon material is preferably 1.6-1.8 g / cm 3 , more preferably 1.65-1.75 g / cm 3 .

[0035] The present application realizes the ordered conversion from a turbostratic structure to a graphite crystal structure of the thermodynamically unstable carbon atoms in the densified carbon-carbon material blank by using thermal energy in the graphitization treatment, effectively improving the thermal field mechanical properties of the carbon-carbon material.

[0036] After obtaining the graphitized carbon-carbon material, the present application performs finishing on the graphitized carbon-carbon material to obtain a finished graphitized carbon-carbon material.

[0037] In the present application, the finishing is preferably polishing.

[0038] The present application does not have special limitation to the polishing, and the graphitized carbon carbon material is polished to be smooth and even without slag according to the drawing requirement by using the polishing method well known in the art. The present application exposes the internal pore of the graphitized carbon carbon material to the inner and outer surface by the finishing, which is beneficial to the next process.

[0039] After obtaining the finished graphitized carbon carbon material, the present application carries out purification treatment on the finished graphitized carbon carbon material in the mixed atmosphere of the purification gas and the protective gas to obtain the purified carbon carbon material.

[0040] In the present application, the temperature of the purification treatment is preferably 2000-2500℃, and more preferably 2100-2400℃; the purification gas is preferably freon; the protective gas is preferably argon; the purity of the argon is preferably ≥99.9%, and more preferably ≥99.99%; the volume ratio of the purification gas and the protective gas is preferably (1-2):1, and more preferably 2:1; the number of cycles is preferably 50-70, and more preferably 55-65.

[0041] In the present application, the process of the purification treatment is preferably as follows: the purification furnace is heated to the temperature of the purification treatment, and the furnace is vacuumized to the limit vacuum, then the purification gas and the protective gas are introduced, and the gas supply is stopped and the pressure is maintained for purification. In the present application, the limit vacuum is preferably 2-10kPa, and more preferably 5-8kPa; the flow rate of the purification gas is preferably 1-20m 3 / h, and more preferably 5-15m 3 / h; the flow rate of the protective gas is preferably 1-20m 3 / h, and more preferably 5-15m 3 / h; the time of introducing the purification gas and the protective gas each time is preferably 3-10min, and more preferably 5-7min; the time of maintaining the pressure each time is preferably 5-10min, and more preferably 5-7min.

[0042] After the purification treatment is completed, the present application preferably stops the furnace and cools down. The present application does not have special limitation to the process of stopping the furnace and cooling down, and the process well known in the art can be used.

[0043] The present application can improve the purity and air permeability of the carbon carbon composite material by the purification treatment.

[0044] After obtaining the purified carbon carbon material, the present application carries out heat treatment on the purified carbon carbon material to obtain the carbon carbon composite material.

[0045] In this invention, the heat treatment temperature is preferably 1800–2300°C, more preferably 2000–2200°C, and the holding time is preferably 8–12 h, more preferably 9–11 h; the heating rate to the heat treatment temperature is preferably 80–120°C / h, more preferably 90–110°C / h; the heat treatment is preferably carried out under a protective atmosphere; the protective atmosphere is preferably argon; the purity of the argon is preferably ≥99.9%, more preferably ≥99.99%.

[0046] This invention opens the pores of carbon-carbon materials through heat treatment, improving the air permeability of carbon-carbon composite materials. At the same time, it can remove ash and metal impurities from the materials, further improving their purity and enabling them to meet the core requirement of high air permeability.

[0047] The present invention also provides a carbon-carbon composite material prepared by the preparation method described in the above technical solution.

[0048] In this invention, the density of the carbon-carbon composite material is 1.6–1.8 g / cm³. 3 The preferred value is 1.65–1.75 g / cm³. 3 The air permeability is 5.5×10⁻⁶. -4 ~8.5×10 -4 cm 3 / (m 2 ·d·Pa), preferably 6×10 -4 ~8×10 -4 cm 3 / (m 2 The coefficient of thermal expansion is 7.5 × 10⁻⁶ (·d·Pa). -6 ~8.5×10 -6 / K, preferably 7.8~8.2×10 -6 / K, with a thermal conductivity of 40-50 W / mK, preferably 42-48 W / mK.

[0049] The present invention also provides the application of the carbon-carbon composite material described in the above technical solution in the preparation of breathable rings.

[0050] The present invention utilizes a permeable ring made of carbon-carbon composite material, which can meet the requirements of the core structural part of the carbon-carbon permeable ring for photovoltaic thermal field monocrystalline silicon Czochralski furnace.

[0051] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0052] Example 1

[0053] The fabric was needle-punched by alternating layers of non-woven fabric and ultra-thin mesh, and then woven using Z-axis carbon fiber through bidirectional weaving, resulting in a density of 0.37 g / cm³.3 Carbon fiber permeable ring preforms were constructed using a graphite kit. Chemical vapor deposition (CVD) was then performed on the preforms to densify them. The CVD carbon densification conditions were as follows: methane was used as the carbon source gas, and the methane flow rate was 10 m³ / s. 3 The deposition process was carried out at a deposition rate of 60℃ / h, a deposition temperature of 1200℃, a deposition time of 100h, and a deposition pressure of 5kPa, to obtain a densified carbon-carbon material permeable ring blank. The permeable ring blank was then placed in a high-temperature furnace and subjected to graphitization heat treatment for 4h at a rate of 100℃ / h to 2000℃ under the protection of 99.99% high-purity argon gas, resulting in a graphitized carbon-carbon material permeable ring. The graphitized carbon-carbon material permeable ring was then polished according to the drawings until its outer surface was smooth and free of slag. After removing the surface residue, the refined graphitized carbon-carbon material permeable ring was placed in a purification furnace. The purification furnace was heated to 2300℃ and evacuated to a limit vacuum of 5kPa. Simultaneously, Freon and argon (99.99% purity) were introduced at a volume ratio of 2:1 and a Freon flow rate of 10m / h. 3 / h, the argon flow rate is 5m 3 The purification process is carried out in cycles of 100℃ / h. The specific purification process is as follows: after 3 minutes of gas supply, gas supply is stopped, and the pressure is maintained for 5 minutes for purification. After 55 cycles of purification, the furnace is stopped and the temperature is cooled down to obtain a purified carbon-carbon material permeable ring. The purified carbon-carbon material permeable ring is placed in a high-temperature furnace and heat-treated for 12 hours at 2000℃ under the protection of high-purity argon gas with a purity of 99.99% at a rate of 100℃ / h to obtain a carbon-carbon composite material permeable ring.

[0054] Example 2

[0055] The fabric was needle-punched by alternating layers of non-woven fabric and ultra-thin mesh, and then woven using Z-axis carbon fiber through bidirectional weaving, resulting in a density of 0.37 g / cm³. 3 Carbon fiber permeable ring preforms were constructed using a graphite kit. Chemical vapor deposition (CVD) was then performed on the preforms to densify them. The CVD carbon densification conditions were as follows: methane was used as the carbon source gas, and the methane flow rate was 10 m³ / s. 3The deposition process was carried out at a deposition rate of 60℃ / h, a deposition temperature of 1200℃, a deposition time of 100h, and a deposition pressure of 5kPa, to obtain a densified carbon-carbon material permeable ring blank. The permeable ring blank was then placed in a high-temperature furnace and subjected to graphitization heat treatment for 4h at a rate of 100℃ / h to 2000℃ under the protection of 99.99% high-purity argon gas, resulting in a graphitized carbon-carbon material permeable ring. The graphitized carbon-carbon material permeable ring was then polished according to the drawings until its outer surface was smooth and free of slag. After removing the surface residue, the refined graphitized carbon-carbon material permeable ring was placed in a purification furnace. The purification furnace was heated to 2300℃ and evacuated to a limit vacuum of 5kPa. Simultaneously, Freon and argon (99.99% purity) were introduced at a volume ratio of 2:1 and a Freon flow rate of 10m / h. 3 / h, the argon flow rate is 5m 3 The purification process is carried out in cycles of 100℃ / h. The specific purification process is as follows: after 3 minutes of gas supply, gas supply is stopped, and the pressure is maintained for 5 minutes for purification. After 65 cycles of purification, the furnace is stopped and the temperature is cooled down to obtain a purified carbon-carbon material permeable ring. The purified carbon-carbon material permeable ring is placed in a high-temperature furnace and heat-treated for 12 hours at 2000℃ under the protection of high-purity argon gas with a purity of 99.99% at a rate of 100℃ / h to obtain a carbon-carbon composite material permeable ring.

[0056] Example 3

[0057] The fabric was needle-punched by alternating layers of non-woven fabric and ultra-thin mesh, and then woven using Z-axis carbon fiber through bidirectional weaving, resulting in a density of 0.37 g / cm³. 3 Carbon fiber permeable ring preforms were constructed using a graphite kit. Chemical vapor deposition (CVD) was then performed on the preforms to densify them. The CVD carbon densification conditions were as follows: methane was used as the carbon source gas, and the methane flow rate was 10 m³ / s. 3 The deposition process was carried out at a deposition rate of 60℃ / h, a deposition temperature of 1200℃, a deposition time of 300h, and a deposition pressure of 5kPa, to obtain a densified carbon-carbon material permeable ring blank. The permeable ring blank was then placed in a high-temperature furnace and subjected to graphitization heat treatment for 4h at a rate of 100℃ / h to 2000℃ under the protection of 99.99% high-purity argon gas, resulting in a graphitized carbon-carbon material permeable ring. The graphitized carbon-carbon material permeable ring was then polished according to the drawings until its outer surface was smooth and free of slag. After removing the surface residue, the refined graphitized carbon-carbon material permeable ring was placed in a purification furnace. The purification furnace was heated to 2300℃ and evacuated to a limit vacuum of 5kPa. Simultaneously, Freon and argon (99.99% purity) were introduced at a volume ratio of 2:1 and a Freon flow rate of 10m / h. 3 / h, the argon flow rate is 5m 3The purification process is carried out in cycles of 100℃ / h. The specific purification process is as follows: after venting for 3 minutes, the venting is stopped, and the pressure is maintained for 5 minutes for purification. After 70 cycles of purification, the furnace is stopped and the temperature is cooled down to obtain a purified carbon-carbon material permeable ring. The purified carbon-carbon material permeable ring is placed in a high-temperature furnace and heat-treated for 12 hours at 2000℃ under the protection of high-purity argon gas with a purity of 99.99% at a rate of 100℃ / h to obtain a carbon-carbon composite material permeable ring.

[0058] Comparative Example 1

[0059] Commercially available graphite breathable rings (referred to as graphite breathable rings).

[0060] Performance testing

[0061] (1) The density and air permeability of the graphite air permeable ring of Comparative Example 1 and the carbon-carbon composite air permeable rings prepared in Examples 1 to 3 were tested. The results are shown in Table 1. The air permeability was determined by the gas permeability test-pressure difference method.

[0062] Table 1 shows the density and permeability of the graphite breathable ring in Comparative Example 1 and the carbon-carbon composite breathable rings prepared in Examples 1-3.

[0063]

[0064] As shown in Table 1, the carbon-carbon composite gas-permeable ring prepared by this invention has significantly improved density and air permeability compared with conventionally used graphite gas-permeable rings. Furthermore, the air permeability of the carbon-carbon composite gas-permeable ring can be further improved by adjusting the process parameters.

[0065] (2) Mechanical property testing

[0066] The mechanical properties of the carbon-carbon composite breathable rings prepared in Examples 1-3 and the commercially available graphite breathable rings in Comparative Example 1 were tested. The results are shown in Table 2. The compressive strength and flexural strength were tested using the three-point bending method.

[0067] Table 2. Mechanical properties of the carbon-carbon composite gas-permeable rings prepared in Examples 1-3 and the graphite gas-permeable ring in Comparative Example 1.

[0068] Item Graphite vent ring Example 1 Example 2 Example 3 Compressive strength / MPa 50～80 325 342 366 Flexural strength / MPa 30～50 178 203 232

[0069] As shown in Table 2, the mechanical properties of the carbon-carbon composite gas-permeable ring prepared by this invention are much higher than those of the graphite gas-permeable ring. Furthermore, the coefficient of thermal expansion of the carbon-carbon composite gas-permeable ring of this invention is tested to be 7.5 × 10⁻⁶. -6 ~8.5×10 -6 / K, with a thermal conductivity of 40-50 W / mK, while the porous graphite breathable ring used in photovoltaic thermal fields has a thermal expansion coefficient of 150 × 10⁻⁶ W / mK. -6 ~30×10 -6With a thermal conductivity of 10-20 W / mK, the carbon-carbon composite breathable ring exhibits low thermal deformation, superior thermal conductivity, energy savings, and a longer service life.

[0070] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a carbon-carbon composite material, characterized in that, Includes the following steps: The carbon fiber preform is repeatedly subjected to chemical vapor deposition for carbon densification. The resulting densified carbon-carbon material preform is then subjected to graphitization heat treatment under a protective atmosphere to obtain graphitized carbon-carbon material. The graphitized carbon material is refined, and the refined graphitized carbon material is purified by circulating it in a mixed atmosphere of purifying gas and protective gas to obtain purified carbon material. The purified carbon-carbon material was subjected to heat treatment to obtain a carbon-carbon composite material; The conditions for carbon densification by chemical vapor deposition include: the carbon source gas used for deposition is methane or propylene, and the flow rate of the carbon source gas is 1–20 m³ / s. 3 / h; The deposition heating rate is 40–80℃ / h, the deposition temperature is 1000–1200℃, and the deposition pressure is 2.0–10.0 kPa; the number of repetitions is 2–3, and the deposition time for each repetition is 100–300 h; The purified gas is Freon; the protective gas is argon; the volume ratio of the purified gas to the protective gas is (1-2):1; the number of cycles is 50-70. The purification process is as follows: the purification furnace is heated to the purification temperature and the furnace is evacuated to the ultimate vacuum. Then, the purifying gas and the protective gas are introduced simultaneously. After the gas supply is stopped, the pressure is maintained for purification. The ultimate vacuum is 2-10 kPa. The time for introducing the purifying gas and the protective gas each time is 3-10 min. The pressure maintenance time each time is 5-10 min. The air permeability of the carbon-carbon composite material is 5.5 × 10⁻⁶. -4 ~8.5×10 -4 cm 3 / (m 2 The coefficient of thermal expansion is 7.5 × 10⁻⁶ (·d·Pa). -6 ~8.5×10 -6 / K, with a thermal conductivity of 40~50W / mK.

2. The preparation method according to claim 1, characterized in that, The density of the carbon fiber preform is 0.2–0.4 g / cm³. 3 .

3. The preparation method according to claim 1, characterized in that, The graphitization heat treatment temperature is 1800–2300℃, and the holding time is 1–4h; the heating rate to the graphitization heat treatment temperature is 80–120℃ / h; the protective atmosphere is argon.

4. The preparation method according to claim 1, characterized in that, The purification process is carried out at a temperature of 2000–2500 °C.

5. The preparation method according to claim 1, characterized in that, The heat treatment temperature is 1800–2300℃, and the holding time is 8–12 h; the heating rate to the heat treatment temperature is 80–120℃ / h; the heat treatment is carried out under a protective atmosphere, which is argon.

6. The preparation method according to claim 1, characterized in that, The finishing process is polishing.

7. The preparation method according to claim 1, characterized in that, The density of the graphitized carbon material is 1.6–1.8 g / cm³. 3 .

8. The carbon-carbon composite material prepared by the preparation method according to any one of claims 1 to 7, characterized in that, The density of the carbon-carbon composite material is 1.6–1.8 g / cm³. 3 The air permeability is 5.5×10⁻⁶. -4 ~8.5×10 -4 cm 3 / (m 2 The coefficient of thermal expansion is 7.5 × 10⁻⁶ (·d·Pa). -6 ~8.5×10 -6 / K, with a thermal conductivity of 40~50W / mK.

9. The application of the carbon-carbon composite material of claim 8 in the preparation of breathable rings.

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