Preparation method of reduced graphene oxide modified carbon / carbon composite material

Abstract

The application discloses a preparation method of reduced graphene oxide modified carbon / carbon composite material and relates to the technical field of carbon-based composite materials. The method comprises the following steps: adding a curing agent into a mixed solution of GO and resin, uniformly mixing, and obtaining a mixed solution containing GO, resin and the curing agent; immersing a carbon fiber preform into the mixed solution containing GO, resin and the curing agent, performing vacuum curing, and performing heat treatment, so as to obtain a carbon fiber preform containing rGO; and placing the carbon fiber preform containing rGO into a mold, performing densification treatment, and obtaining the reduced graphene oxide modified carbon / carbon composite material. The application is based on the uniform dispersion of rGO in the preform after high-temperature reduction, so that the toughening effect of rGO on the pyrolytic carbon matrix is fully exerted, and the mechanical properties of the C / C composite material are improved. The method has simple process and wide preparation conditions.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of carbon-based composite materials, in particular to a preparation method of reduced graphene oxide modified carbon / carbon composite materials. BACKGROUND

[0002] Carbon / carbon (C / C) composite material, i.e. carbon fiber reinforced carbon matrix composite material, is composed of carbon fibers and carbon matrix. The C / C composite material has a series of excellent performances which cannot be compared with other materials, such as low density, high specific strength, high specific modulus, ablation resistance and the like, and is widely applied to the fields of missile nose cones, aircraft brakes, throat liners of solid rocket nozzles, nozzles, expansion sections, wing leading edges and the like. In recent years, with the rapid development of China's aerospace and national defense science and technology, increasingly stringent requirements are put forward for the structure and performance of the C / C composite material. However, the mechanical properties of the traditional C / C composite material have some defects, because the action range of the micron-level carbon fibers is limited to the pyrolytic carbon matrix in the vicinity of the carbon fibers, and the matrix between the fiber bundles and the matrix between the single filaments in the fiber bundles is not effectively reinforced. The insufficient local reinforcement effect leads to the generation of structural defects such as pyrolytic carbon ring cracking, carbon fiber / pyrolytic carbon matrix interface weakening and even debonding, so that when the C / C composite material is mechanically processed into thin-walled, sharp and the like components, the mechanical properties are sharply reduced due to the shortening of the fibers and the destruction of the organizational continuity.

[0003] In order to solve the above problems, at present, the pyrolytic carbon is modified by introducing a reinforcing body into the pyrolytic carbon matrix to achieve the reinforcement of the pyrolytic carbon. The introduction of nanomaterials into the composite material can effectively improve the mechanical properties such as strength and fracture toughness. Graphene is a two-dimensional honeycomb material composed of single-layer carbon atoms, and is also the thinnest material in the world, and has excellent mechanical, thermal and electrical properties, and has a wide application prospect as a nanometer reinforcing phase.

[0004] In the prior art, when the oxidized carbon fibers are continuously immersed in a graphene oxide (GO) aqueous dispersion, a composite material with deposited GO is prepared by using an ultrasonic-assisted electrophoretic deposition method, and the interfacial shear performance of the composite material is improved to a certain extent. However, for the composite material prepared by electrophoretic deposition, on the one hand, the GO is simply physically attached to the carbon fibers, which leads to the easy falling off of the GO from the fiber surface and is not conducive to the effective reinforcement of the GO to the fiber matrix interface. On the other hand, the GO is only distributed on the surface of the carbon fibers and does not stretch into the pores between the fiber bundles, and the matrix between the fiber bundles cannot be effectively reinforced.

[0005] The prior art also grafts GO onto a functionalized carbon fiber preform through ultrasonic and heat treatment, and then densifies the preform by chemical vapor infiltration to obtain a high-performance C / C composite material. The flexural strength and interlaminar shear strength of the C / C composite material prepared by the method are improved to a certain extent. The composite material prepared by the chemical grafting process has strong binding force between GO and carbon fibers, but the introduced GO mainly exists on the surface of the carbon fiber preform and cannot be uniformly dispersed in the preform, which limits the effect of GO on the strengthening of the pyrocarbon matrix of the C / C composite material.

[0006] The skilled person introduces graphene into a carbon fiber preform by vacuum impregnation, and then densifies the carbon fiber preform by isothermal chemical vapor infiltration to obtain a graphene modified C / C composite material. In the method, graphene and carbon fibers fail to form a strong chemical bond, and a large amount of graphene is distributed on the surface of the carbon felt. In addition, due to the small pore size of the carbon felt, only a small amount of graphene can penetrate into the internal pores of the carbon felt, resulting in uneven distribution of graphene on the carbon fiber preform. The uneven distribution of this nano-reinforcing phase affects the interfacial bonding strength between carbon fibers and the pyrocarbon matrix, is not conducive to stress transfer, aggravates crack propagation and interfacial debonding, and thus limits the further improvement of the mechanical properties of the C / C composite material.

[0007] Therefore, it is necessary to solve the problem of the difficulty of uniform dispersion of graphene in the carbon fiber preform, realize the effective improvement of the fiber-matrix interface of the composite material by graphene, and further improve the mechanical properties of the C / C composite material. SUMMARY

[0008] In view of the deficiencies in the above background art, the present application provides a method for preparing a reduced graphene oxide modified carbon / carbon composite material. Since the initial dispersion state of GO determines the final distribution of rGO after high temperature reduction, this method solves the problem of the difficulty of uniform dispersion of the initial GO in the carbon fiber preform, ensures the uniform dispersion of rGO in the preform after high temperature reduction, fully utilizes the toughening effect of rGO on the pyrocarbon matrix, and thus improves the mechanical properties of the C / C composite material. The method is simple in process and wide in preparation conditions.

[0009] The first object of the present application is to provide a method for preparing a reduced graphene oxide modified carbon / carbon composite material, comprising the following steps:

[0010] Preparation of a GO suspension;

[0011] A certain amount of resin is added to the GO suspension, and a mixed solution of GO and resin is obtained after uniform mixing;

[0012] The curing agent is added to the mixed solution of GO and resin, and after mixing, a mixed solution containing GO, resin and curing agent is obtained;

[0013] The carbon fiber preform is immersed in the mixed solution containing GO, resin and curing agent, and after vacuum curing, the cured carbon fiber preform is wrapped with graphite paper, and then heat treated at 600-1100℃ for 2-4h to obtain a carbon fiber preform containing rGO.

[0014] The carbon fiber preform containing rGO is placed in a mold for densification treatment to obtain a reduced graphene oxide modified carbon / carbon composite material.

[0015] Preferably, the resin comprises a resin with a grade of E-54 or HS-170;

[0016] The mass ratio of the resin to GO in the GO suspension is 20-100:1.

[0017] Preferably, the curing agent is one or more of HS-180MB, H-316-MTHPA, 4,4'-diamino diphenyl sulfone, and 4,4'-diamino diphenyl methane;

[0018] The mass ratio of the curing agent to GO in the GO suspension is 20-300:1.

[0019] Preferably, when the mixed solution of GO and resin is obtained, the mixing process includes stirring and ultrasonic dispersion in sequence; wherein the stirring temperature is set to 55℃, the stirring time is 20-40 min, and the stirring speed is 300-500 rpm; the ultrasonic dispersion process is set to a frequency of 50 kHz, a power of 100 W, a temperature of 55℃, and a time of 40-60 min.

[0020] Preferably, when the mixed solution containing GO, resin and curing agent is obtained, the mixing process includes magnetic stirring at a speed of 300-500 rpm for 20-40 min at a temperature of 55℃.

[0021] Preferably, the vacuum curing process includes treatment in a vacuum drying box at a temperature of 60℃ and a vacuum degree of -0.1 MPa for 2-4 h.

[0022] During heat treatment, the sample is placed in a tube furnace with argon flowing, and heat treated at 600-1100℃ for 2-4h.

[0023] Preferably, the GO suspension is prepared according to the following steps:

[0024] A certain amount of GO is added to anhydrous ethanol, magnetic stirring speed is 300-500 rpm, stirring time is 20-30 min, then the mixed solution is placed in an ultrasonic dispersion device, ultrasonic treatment is carried out at 100 W, 50 kHz for 30-60 min, and a GO suspension is obtained.

[0025] Preferably, the densification treatment process comprises the following steps:

[0026] The carbon fiber preform is placed in a mold of a chemical vapor deposition furnace, argon is introduced to make the furnace in a slightly positive pressure, then the temperature is raised to 1000-1100 DEG C at a temperature raising rate of 10 DEG C / min, and the temperature is kept constant, while the argon flow is adjusted to 1.0-2.0 L / min, and the CH4 flow is adjusted to 0.3-0.5 L / min, after the pyrolytic carbon deposition is completed, the heating is immediately stopped, the CH4 is closed, the argon flow is adjusted to 0.3-0.5 L / min, the sample is placed in an argon atmosphere, and after the temperature of the deposition furnace is reduced to room temperature, the argon is closed, and the sample is taken out, which is the reduced graphene oxide modified carbon / carbon composite material.

[0027] The second object of the present application is to provide a reduced graphene oxide modified carbon / carbon composite material.

[0028] The third object of the present application is to provide an application of the reduced graphene oxide modified carbon / carbon composite material in high-strength structural parts.

[0029] Compared with the prior art, the present application has the following beneficial effects:

[0030] The present application provides a preparation method of a reduced graphene oxide modified carbon / carbon composite material, and the GO is uniformly dispersed in the 2D needled carbon felt by using a resin carrier. The GO is uniformly dispersed in the carbon fiber preform by using the strong chemical bonding effect between the polar groups in the resin molecular chain and the oxygen-containing functional groups on the surface of the GO layer, combining the fluidity of the resin, and through vacuum impregnation, then the carbon fiber preform with uniformly distributed rGO is formed by high-temperature carbonization and reduction treatment, and finally the densification treatment is carried out by a chemical vapor deposition process, so that the C / C composite material with high thermal conductivity and high toughness is obtained. The method can effectively inhibit the agglomeration of GO in the carbon fiber preform, and can solve the difference in performance of each part of the composite material caused by the non-uniform structure of the preform, and further improve the performance stability of the material. The present application scheme is simple, the process is controllable, and has a wide application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 A cross-sectional scanning electron micrograph of the rGO modified carbon fiber preform prepared in Example 1;

[0032] Figure 2A cross-sectional scanning electron micrograph of the rGO modified carbon fiber preform prepared in Example 2;

[0033] Figure 3 A cross-sectional scanning electron micrograph of the rGO modified carbon fiber preform prepared in Example 3;

[0034] Figure 4 A cross-sectional scanning electron micrograph of the rGO modified carbon fiber preform prepared in Comparative Example 1;

[0035] Figure 5 A comparison of the compressive strength of the composite materials prepared in Examples and Comparative Examples with that of pure C / C composite material. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the technical solutions of the present application and to implement them, the present application will be further described below in conjunction with specific embodiments and drawings, but the embodiments are not limiting on the present application.

[0037] The purpose of the present application is to provide a preparation method of reduced graphene oxide (rGO) reinforced C / C composite material, so the method focuses on solving the problem of uniform dispersion of initial GO in the carbon fiber preform, ensuring uniform dispersion of rGO in the preform after high temperature reduction, fully exerting the toughening effect of rGO on the pyrolytic carbon matrix, and thus improving the mechanical properties of C / C composite material. The method is simple in process and wide in preparation conditions.

[0038] In order to achieve the above purpose, the first aspect of the present application provides a preparation method of reduced graphene oxide modified carbon / carbon composite material, comprising the following steps:

[0039] Preparation of GO suspension;

[0040] A certain amount of resin is added to the GO suspension, and a mixed solution of GO and resin is obtained after uniform mixing;

[0041] A curing agent is added to the mixed solution of GO and resin, and a mixed solution containing GO, resin and curing agent is obtained after uniform mixing;

[0042] The carbon fiber preform is immersed in the mixed solution containing GO, resin and curing agent, and after vacuum curing, the carbon fiber preform after curing is wrapped with graphite paper, and then heat treated at 600-1100℃ for 2 ~4h to obtain a carbon fiber preform containing rGO;

[0043] The carbon fiber preform containing rGO is placed in a mold for densification treatment, and a reduced graphene oxide modified carbon / carbon composite material is obtained.

[0044] The carbon fiber preform is a 2D needled carbon fiber bulk felt; the resin comprises a resin with a grade of E-54 or HS-170; the mass ratio of the resin to the GO in the GO suspension is 20:1-100:1.

[0045] The curing agent is one or more of HS-180MB, H-316-MTHPA, 4,4'-diamino diphenyl sulfone, 4,4'-diamino diphenyl methane;

[0046] The mass ratio of the curing agent to the GO in the GO suspension is 20:1-300:1

[0047] When the mixed solution of GO and resin is obtained, the mixing process includes stirring and ultrasonic dispersion in sequence; wherein the stirring temperature is set to 55℃, the stirring time is 20-40 min, and the stirring speed is 300-500 rpm; the ultrasonic dispersion process is set to a frequency of 50 kHz, a power of 100 W, a temperature of 55℃, and a time of 40-60 min.

[0048] When the mixed solution containing GO, resin and curing agent is obtained, the mixing process includes magnetic stirring, the stirring speed is 300-500 rpm, the stirring time is 20-40 min, and the stirring temperature is 55℃.

[0049] The vacuum curing process includes processing in a vacuum drying box with a temperature of 60℃ and a vacuum degree of -0.1 MPa for 2-4 h;

[0050] The heat treatment is to place the sample in a tube furnace with argon, and heat treat at 600-1100℃ for 2-4 h.

[0051] The GO suspension is prepared according to the following steps:

[0052] A certain amount of GO is added to anhydrous ethanol, and the magnetic stirring speed is 300-500 rpm, the stirring time is 20-30 min, then the mixed solution is placed in an ultrasonic dispersion device, and ultrasonic treatment is carried out under the condition of 100 W, 50 kHz for 30-60 min to obtain the GO suspension.

[0053] The densification treatment process includes the following steps:

[0054] The carbon fiber preform is placed in a mold of a chemical vapor deposition furnace, argon is introduced to make the furnace in a slightly positive pressure, then heated to 1000-1100℃ at a heating rate of 10℃ / min, and at the same time, the argon flow is adjusted to 1.0-2.0 L / min, after the pyrolytic carbon deposition is completed, the heating is immediately stopped, the CH4 is closed, and the argon flow is adjusted to 0.3-0.5 L / min to make the sample in an argon atmosphere, after the deposition furnace temperature is reduced to room temperature, the argon is closed, and the sample is taken out, which is the reduced graphene oxide modified carbon / carbon composite material.

[0055] Exemplarily, a preparation method of a reduced graphene oxide modified carbon / carbon composite material comprises the following steps:

[0056] Step 1: a certain amount of GO is added to a solvent, stirred and ultrasonicated to obtain a GO suspension;

[0057] The preparation of the GO suspension in step 1 comprises: a certain amount of GO is added to anhydrous ethanol, the mass ratio of GO to anhydrous ethanol is 0.1-0.5 g: 20-80 ml, the magnetic stirring speed is 300-500 rpm, and the stirring time is 20-30 min, then the mixed solution is placed in an ultrasonic dispersion device, ultrasonically treated at 100 W, 50 kHz for 30-60 min to obtain a GO suspension.

[0058] Step 2: a certain amount of resin is added to the GO suspension obtained in step 1, the mass ratio of resin to GO in the GO suspension is 20-100:1, and the ethanol solvent is removed after stirring and ultrasonication at a certain temperature;

[0059] The stirring and ultrasonication in step 2 comprise: the stirring temperature is set to 55℃ during stirring, the stirring time is 20-40 min, and the stirring speed is 300-500 rpm; the ultrasonic dispersion process is set to a frequency of 50 kHz, a power of 100 W, a temperature of 55℃, and a time of 40-60 min.

[0060] The resin in step 2 comprises a resin with a brand of E-54 or HS-170.

[0061] Step 3: a curing agent is added to the mixed solution obtained in step 2, the mass ratio of the curing agent to GO in the GO suspension is 20-300:1, and a mixed solution containing GO, resin and curing agent is obtained after stirring; a 2D needled carbon felt is immersed in the mixed solution and vacuum cured;

[0062] After the curing agent is added in step 3, magnetic stirring is performed at a speed of 300-500 rpm for 20-40 min, and the stirring temperature is 55℃.

[0063] The curing agent in step 3 includes one or more of HS-180MB, H-316-MTHPA, 4,4'-diaminodiphenyl sulfone, and 4,4'-diaminodiphenyl methane.

[0064] The vacuum curing in step 3 includes: processing in a vacuum drying box with a temperature of 60 DEG C and a vacuum degree of -0.1 MPa for 2-4 h.

[0065] Step 4: wrapping the carbon fiber preform with graphite paper, and then performing high-temperature heat treatment, the purpose of the heat treatment is to carbonize the resin and reduce GO at the same time, to obtain a carbon fiber preform containing rGO;

[0066] The high-temperature heat treatment in step 4 includes: placing the sample into a tube furnace with argon flowing, and heat treating at 600-1100 DEG C for 2 h, and cooling to room temperature.

[0067] Step 5: placing the carbon fiber preform containing rGO into a mold, and densifying it by a chemical vapor deposition method to obtain a modified C / C composite material.

[0068] The densification process in step 5 is a chemical vapor deposition process, and the gaseous precursor entering the carbon fiber preform is converted into pyrolytic carbon by high-temperature cracking, filling the internal pores of the preform, enhancing the combination of fibers and matrix, and improving the densification and overall performance of the material.

[0069] The densification process includes the following steps:

[0070] a. placing the carbon fiber preform into a mold in a chemical vapor deposition furnace, and before starting the deposition, the deposition furnace needs to be checked for air tightness, and the specific operation is: first vacuumizing the deposition furnace, then washing the deposition furnace with argon for multiple times, and then introducing argon to make the furnace in a slightly positive pressure.

[0071] b. heating the furnace to 1000-1100 DEG C at a heating rate of 10 DEG C / min, and at the same time, adjusting the argon flow to 1.0-2.0 L / min and the CH4 flow to 0.3-0.5 L / min, after the pyrolytic carbon deposition is completed, immediately stop heating, close the CH4, and at the same time, adjust the argon flow to 0.3 L / min, so that the sample is placed in an argon atmosphere to prevent oxidation of the sample, and after the temperature of the deposition furnace decreases to room temperature, the argon is turned off, and the sample is taken out, which is a reduced graphene oxide modified carbon / carbon composite material.

[0072] The second aspect of the present application provides a reduced graphene oxide modified carbon / carbon composite material.

[0073] The third aspect of the present application provides an application of the reduced graphene oxide modified carbon / carbon composite material in high-strength structural parts.

[0074] It should be noted that the experimental methods used in the present application are conventional methods unless otherwise specified; the reagents and materials used, unless otherwise specified, are commercially available.

[0075] Example 1

[0076] Step 1: Take 0.15 g of GO and dissolve it in 30 mL of anhydrous ethanol, with a magnetic stirring speed of 300 rpm for 30 min, then place the mixed solution in an ultrasonic dispersion device, and ultrasonic treat it at 100 W, 50 kHz for 50 min to obtain a GO suspension.

[0077] Step 2: Take 15 g of resin with the E-54 brand, and add the weighed epoxy resin E-54 to the GO suspension, with a stirring temperature of 55°C, a stirring time of 60 min, and a stirring speed of 300 rpm during magnetic stirring; then place it in an ultrasonic dispersion device, and ultrasonic treat it at 55°C, 100 W, 50 kHz for 40 min.

[0078] Step 3: Add 4.95 g of curing agent 4,4'-diaminodiphenyl sulfone to the mixed solution, with a magnetic stirring speed of 300-500 rpm, a stirring time of 30 min, and a stirring temperature of 55°C, to obtain a mixed solution containing GO, resin, and curing agent; immerse the 2D needled carbon felt in the mixed solution, and treat it in a vacuum drying box at a temperature of 60°C and a vacuum degree of -0.1 MPa for 3 h.

[0079] Step 4: Wrap the carbon fiber preform described above with graphite paper, and then perform high-temperature carbonization treatment, i.e., place the sample in a tube furnace with argon flowing, and heat treat it at 950°C for 2 h, to obtain a carbon fiber preform containing rGO after cooling to room temperature.

[0080] Step 5: Place the carbon fiber preform containing rGO into a mold, and densify it by chemical vapor deposition method to obtain a modified C / C composite material. The densification process steps are as follows:

[0081] a. Place the carbon fiber preform containing rGO in the mold of the chemical vapor deposition furnace, and perform airtightness check on the deposition furnace before starting deposition, the specific operation is: first vacuumize the deposition furnace to 2 kPa, then perform 3 times of gas washing treatment on the deposition furnace with argon, and then introduce argon to make the furnace in a slightly positive pressure.

[0082] b. After the furnace is heated to 1080°C at a heating rate of 10°C / min, the temperature is kept constant, the argon flow rate is adjusted to 2.0 L / min, and the CH4flow rate is adjusted to 0.3 L / min. The pyrolytic carbon deposition time is 100 h. After the pyrolytic carbon deposition is completed, the heating is stopped immediately, the CH4is turned off, the argon flow rate is adjusted to 0.3 L / min, and the argon is turned off after the deposition furnace temperature drops to room temperature. The sample is removed.

[0083] Example 2

[0084] Step 1: 0.1 g of GO is weighed and dissolved in 50 mL of anhydrous ethanol. The magnetic stirring speed is 300 rpm, and the stirring time is 40 min. Then the mixed solution is placed in an ultrasonic dispersion device and ultrasonically treated at 100 W and 50 kHz for 60 min to obtain a GO suspension.

[0085] Step 2: 10 g of resin with the E-54 brand is weighed and added to the GO suspension. The stirring temperature during magnetic stirring is 55°C, the stirring time is 40 min, and the stirring speed is 300 rpm. Then it is placed in an ultrasonic dispersion device and ultrasonically treated at 55°C, 100 W, and 50 kHz for 30 min.

[0086] Step 3: 4.95 g of curing agent 4,4'-diaminodiphenyl sulfone is added to the mixed solution. The magnetic stirring speed is 300-500 rpm, the stirring time is 40 min, and the stirring temperature is 55°C. A mixed solution containing GO, resin, and curing agent is obtained. The 2D needled carbon felt is immersed in the mixed solution and treated in a vacuum drying box at a temperature of 60°C and a vacuum degree of -0.1 MPa for 4 h.

[0087] Step 4: The carbon fiber preform is wrapped with graphite paper and then subjected to high-temperature carbonization treatment. The sample is placed in a tube furnace with argon flowing at 950°C for 2 h. After cooling to room temperature, a carbon fiber preform containing rGO is obtained.

[0088] Step 5: The carbon fiber preform containing rGO is placed in a mold and densified by chemical vapor deposition to obtain a modified C / C composite material. The densification process steps are as follows:

[0089] a. The carbon fiber preform containing rGO is placed in the mold of the chemical vapor deposition furnace. Before deposition, the deposition furnace needs to be checked for air tightness. The specific operation is as follows: first, the deposition furnace is evacuated to 2 kPa, then the deposition furnace is washed with argon for 3 times, and then argon is introduced to make the furnace in a slight positive pressure.

[0090] b. After the furnace is heated to 1080°C at a heating rate of 10°C / min, the temperature is kept constant, the argon flow rate is adjusted to 2.5 L / min, and the CH4flow rate is adjusted to 0.3 L / min. The pyrolytic carbon deposition time is 100 h. After the pyrolytic carbon deposition is completed, the heating is stopped immediately, the CH4is turned off, the argon flow rate is adjusted to 0.3 L / min, and the argon is turned off after the deposition furnace temperature drops to room temperature. The sample is removed.

[0091] Example 3

[0092] Step 1: 0.25 g of GO is weighed and dissolved in 40 mL of anhydrous ethanol. The magnetic stirring speed is 300 rpm, and the stirring time is 40 min. Then the mixed solution is placed in an ultrasonic dispersion device and ultrasonically treated at 100 W and 50 kHz for 60 min to obtain a GO suspension.

[0093] Step 2: 10 g of resin with the HS-170 brand is weighed and added to the GO suspension. The stirring temperature during magnetic stirring is 55°C, the stirring time is 40 min, and the stirring speed is 300 rpm. Then it is placed in an ultrasonic dispersion device and ultrasonically treated at 55°C, 100 W, and 50 kHz for 30 min.

[0094] Step 3: 10 g of curing agent HS-180MB is added to the mixed solution. The magnetic stirring speed is 300-500 rpm, the stirring time is 40 min, and the stirring temperature is 55°C. A mixed solution containing GO, resin, and curing agent is obtained. The 2D needled carbon felt is immersed in the mixed solution and treated in a vacuum drying box at a temperature of 60°C and a vacuum degree of -0.1 MPa for 2 h.

[0095] Step 4: The carbon fiber preform is wrapped with graphite paper and then subjected to high-temperature carbonization treatment. The sample is placed in a tube furnace with argon flowing at 950°C for 2 h. After cooling to room temperature, a carbon fiber preform containing rGO is obtained.

[0096] Step 5: The carbon fiber preform containing rGO is placed in a mold and densified by chemical vapor deposition to obtain a modified C / C composite material. The densification process steps are as follows:

[0097] a. The carbon fiber preform containing rGO is placed in the mold of the chemical vapor deposition furnace. Before deposition, the deposition furnace needs to be checked for air tightness. The specific operation is as follows: first, the deposition furnace is evacuated to 2 kPa, then the deposition furnace is washed with argon for 3 times, and then argon is introduced to make the furnace in a slight positive pressure.

[0098] b. After the furnace is heated to 1050°C at a heating rate of 10°C / min, the temperature is kept constant, the argon flow is adjusted to 2.5 L / min, the CH4 flow is adjusted to 0.3 L / min, and the pyrolytic carbon deposition time is 100 h. After the pyrolytic carbon deposition is completed, the heating is immediately stopped, the CH4 is turned off, the argon flow is adjusted to 0.3 L / min, and the sample is taken out after the deposition furnace temperature drops to room temperature.

[0099] Comparative Example 1

[0100] Step 1: 0.1 g of GO is weighed and dissolved in 40 mL of anhydrous ethanol, the magnetic stirring speed is 300 rpm, and the stirring time is 40 min. Then the mixed solution is placed in an ultrasonic dispersion device and ultrasonically treated at 100 W and 50 kHz for 60 min to obtain a GO suspension.

[0101] Step 2: The 2D needled carbon felt is immersed in the mixed solution and treated in a vacuum drying box at a temperature of 60°C and a vacuum degree of -0.1 MPa for 3 h.

[0102] Step 4: The carbon fiber preform is wrapped with graphite paper, and then high-temperature carbonization treatment is performed, i.e., the sample is placed in a tube furnace with argon flowing, and heat treated at 950°C for 2 h. After cooling to room temperature, a carbon fiber preform containing rGO is obtained.

[0103] Step 5: The carbon fiber preform containing rGO is placed in a mold and densified by chemical vapor deposition to obtain a modified C / C composite material. The densification process steps are as follows:

[0104] a. The carbon fiber preform containing rGO is placed in the mold of the chemical vapor deposition furnace. Before deposition, the deposition furnace needs to be checked for air tightness. The specific operation is: first, the deposition furnace is evacuated to 2 kPa, then the deposition furnace is washed with argon for 3 times, and then argon is introduced to make the furnace in a slight positive pressure.

[0105] b. After the furnace is heated to 1050°C at a heating rate of 10°C / min, the temperature is kept constant, the argon flow is adjusted to 2.5 L / min, the CH4 flow is adjusted to 0.3 L / min, and the pyrolytic carbon deposition time is 100 h. After the pyrolytic carbon deposition is completed, the heating is immediately stopped, the CH4 is turned off, the argon flow is adjusted to 0.3 L / min, and the sample is taken out after the deposition furnace temperature drops to room temperature.

[0106] In order to illustrate the uniform dispersion of the initial GO inside the carbon fiber preform, it is described in combination with the drawings.

[0107] Figure 1The cross-section SEM photo of the rGO modified carbon fiber preform prepared in Example 1 can be observed that the rGO sheets uniformly coat the surface of the carbon fibers inside the carbon felt, forming a structure similar to "fish scale", which makes the combination of rGO and carbon fiber more firm, and is beneficial to increase the interface performance of the carbon fiber composite material.

[0108] Figure 2 The cross-section SEM photo of the rGO modified carbon fiber preform prepared in Example 2 can be observed that the rGO sheets are tightly coated on the surface of the carbon fibers inside the carbon felt, increasing the roughness of the carbon fibers, providing more deposition sites for the subsequent pyrolytic carbon deposition, and increasing the mechanical interlocking and cross-sectional area of the fibers and the matrix.

[0109] Figure 3 The cross-section SEM photo of the rGO modified carbon fiber preform prepared in Example 3 can be observed that the rGO sheets attached to the surface of the carbon fibers inside the carbon felt are obviously more, and the area covered by the rGO sheets on the carbon fibers is also larger, and the distribution on the carbon fibers is relatively uniform.

[0110] Figure 4 The cross-section SEM photo of the rGO modified carbon fiber preform prepared in Comparative Example 1 can be observed that the content of the rGO sheets attached to the surface of the carbon fibers inside the carbon felt is less, indicating that the initial GO enters the inside of the carbon fiber preform with less content, uneven distribution and weak combination.

[0111] Figure 5 It is shown that the increase of the content of GO can improve the compressive strength of the pure C / C composite material, and the compressive strength of the composite material in Comparative Example 1 is improved by 17% compared with the pure C / C composite material. However, the compressive strength of the composite material in the examples is higher than that in the comparative examples, and the compressive strength of the composite material in Example 1 is improved by 41% compared with the pure C / C composite material. With the continuous increase of the content of GO, the compressive strength of the composite material is reduced. Therefore, the filling of the appropriate amount of GO in the composite material can effectively improve the compressive strength of the composite material.

[0112] The present application describes preferred embodiments and their effects. However, those skilled in the art can make further changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0113] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made thereto without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for preparing reduced graphene oxide-modified carbon / carbon composite material, characterized in that, Includes the following steps: Preparation of GO suspension; A certain amount of resin was added to the GO suspension and mixed evenly to obtain a mixed solution of GO and resin. Add a curing agent to the mixed solution of GO and resin, and mix thoroughly to obtain a mixed solution containing GO, resin and curing agent; The carbon fiber preform is impregnated in a mixed solution containing GO, resin and curing agent, and then vacuum cured. The cured carbon fiber preform is then wrapped with graphite paper and heat-treated at 600-1100℃ for 2-4 hours to obtain a carbon fiber preform containing rGO. A carbon fiber preform containing rGO is placed in a mold and densified to obtain a carbon / carbon composite material modified with reduced graphene oxide. The resin includes resins with the designation E-54 or HS-170; The mass ratio of the resin to the GO in the GO suspension is 20~100:1; The curing agent is one or more of HS-180MB, H-316-MTHPA, 4,4'-diaminodiphenyl sulfone, and 4,4'-diaminodiphenylmethane; The mass ratio of the curing agent to the GO in the GO suspension is 20~300:

1.

2. The method for preparing reduced graphene oxide-modified carbon / carbon composite material according to claim 1, characterized in that, When obtaining the mixed solution of GO and resin, the process of uniform mixing includes stirring and sonication in sequence; wherein, during the stirring process, the stirring temperature is set to 55℃, the stirring time is 20-40 min, and the rotation speed is 300-500 rpm; during the ultrasonic dispersion process, the frequency is set to 50 kHz, the power is 100 W, the temperature is 55℃, and the time is 40-60 min.

3. The method for preparing reduced graphene oxide-modified carbon / carbon composite material according to claim 1, characterized in that, When a mixed solution containing GO, resin and curing agent is obtained, the process of uniform mixing includes magnetic stirring at a speed of 300-500 rpm for 20-40 min at a stirring temperature of 55℃.

4. The method for preparing reduced graphene oxide-modified carbon / carbon composite material according to claim 1, characterized in that, The vacuum curing process includes treatment in a vacuum drying oven at a temperature of 60℃ and a vacuum degree of -0.1 MPa for 2-4 hours; During heat treatment, the sample is placed in a tube furnace filled with argon gas and heat-treated at 600-1100℃ for 2-4 hours.

5. The method for preparing reduced graphene oxide-modified carbon / carbon composite material according to claim 1, characterized in that, The GO suspension was prepared according to the following steps: A certain amount of GO was added to anhydrous ethanol, and the magnetic stirring speed was 300-500 rpm for 20-30 min. Then the mixed solution was placed in an ultrasonic dispersion device and ultrasonically treated at 100 W and 50 kHz for 30-60 min to obtain a GO suspension.

6. The method for preparing reduced graphene oxide-modified carbon / carbon composite material according to claim 1, characterized in that, The densification process includes the following steps: The carbon fiber preform was placed in a mold of a chemical vapor deposition furnace, and argon gas was introduced to create a slightly positive pressure inside the furnace. The temperature was then increased to 1000-1100℃ at a rate of 10℃ / min and held at that temperature. At the same time, the argon gas flow rate was adjusted to 1.0-2.0 L / min and the CH4 gas flow rate was adjusted to 0.3-0.5 L / min. After the pyrolysis carbon deposition was completed, heating was immediately stopped, the CH4 gas was turned off, and the argon gas flow rate was adjusted to 0.3-0.5 L / min to place the sample in an argon atmosphere. After the deposition furnace temperature dropped to room temperature, the argon gas was turned off, and the sample was removed. This sample is the reduced graphene oxide modified carbon / carbon composite material.

7. A reduced graphene oxide modified carbon / carbon composite material prepared by the method of any one of claims 1 to 6.

8. The application of the reduced graphene oxide modified carbon / carbon composite material according to claim 7 in high-strength structural components.

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