Modified carbon-carbon composite material with directionally arranged graphene and preparation method of modified carbon-carbon composite material

Abstract

The invention belongs to the technical field of carbon-carbon composite materials, and particularly relates to a modified carbon-carbon composite material with directionally arranged graphene and a preparation method of the modified carbon-carbon composite material. The method comprises the following steps: adding dopamine hydrochloride into a tris (hydroxymethyl) aminomethane-hydrochloric acid buffer solution to obtain a modified solution; then immersing a polyacrylonitrile-based carbon fiber felt, and stirring in an oil bath to prepare a polydopamine modified carbon fiber felt; the preparation method comprises the following steps: impregnating a graphene oxide dispersion liquid into a polydopamine modified carbon fiber felt, drying, performing high-pressure impregnation together with mesophase pitch, performing high-temperature heat treatment, and polishing to obtain a carbon-carbon composite material; repeating the high-pressure impregnation and high-temperature heat treatment processes of the mesophase pitch until the carbon-carbon composite material is difficult to compact, so as to prepare a high-density carbon-carbon composite material; a high-density carbon-carbon composite material is subjected to graphitization treatment, the modified carbon-carbon composite material with graphene arranged in an oriented mode is prepared, and the mechanical property and the heat-conducting property of the material are both improved.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon-carbon composite materials, and in particular to a modified carbon-carbon composite material with directional arrangement of graphene and a preparation method thereof. Background Art

[0002] Carbon fiber reinforced carbon-based carbon-carbon composites have attracted great attention due to their unique properties, including low density, high thermal conductivity, high specific strength and excellent ablation resistance. These properties make them ideal for high-temperature thermal management in extreme environments. With the miniaturization and integration of electronic devices, the heat generation per unit volume has increased rapidly, leading to an increase in the demand for efficient heat dissipation materials. Directional thermal conductive materials can effectively solve the problem of local overheating of electronic components and improve the stability and life of equipment. The rapid development of new energy vehicles has also driven the demand for thermal conductive materials. Power batteries generate a lot of heat during charging and discharging, and an efficient thermal management system is required to ensure the safety and performance of the battery. Directional thermal conductive materials can improve the heat dissipation efficiency of the battery and ensure its stability at high power output. The construction of 5G communication technology and data centers has put forward higher requirements for heat dissipation performance. Directional thermal conductive materials can effectively reduce the thermal resistance of the equipment, improve the heat dissipation efficiency, and ensure the reliability of the equipment under high load operation. Therefore, in order to improve the anisotropic thermal conductivity of carbon-carbon composites, it is very important, so we need to study relevant methods to design the anisotropic thermal conductivity of carbon-carbon composites. Summary of the invention

[0003] One of the purposes of the present invention is to provide a method for preparing a modified carbon-carbon composite material with directional arrangement of graphene, in which graphene oxide is coated on the carbon fibers of carbon fiber felt, and then the carbon-carbon composite material is prepared by impregnation with intermediate phase asphalt, carbonization and densification, and finally high-temperature graphitization. Due to the modified carbon-carbon composite material with directional arrangement of graphene oxide, the thermal conductivity in the plane, i.e., the XY plane, is improved without modification of graphene oxide, while the thermal conductivity between layers, i.e., the XZ plane, is slightly decreased, and the tensile strength and plasticity of the carbon-carbon composite material are improved.

[0004] To achieve the above object, the present invention adopts the following technical solution: a method for preparing a modified carbon-carbon composite material with directional arrangement of graphene, comprising the following steps:

[0005] Step A, adding dopamine hydrochloride to tris(hydroxymethylaminomethane)-hydrochloric acid buffer, stirring at a constant temperature until the mixture is uniformly mixed to obtain a polydopamine modified solution;

[0006] Adding polyacrylonitrile-based carbon fiber felt to the polydopamine modified solution, stirring and reacting in an oil bath environment, washing and drying, then washing with deionized water and anhydrous ethanol, and drying in an oven to obtain polydopamine modified carbon fiber felt;

[0007] Step B, adding graphene oxide to N,N-dimethylamide, mixing, stirring at room temperature and ultrasonically crushing to obtain a graphene oxide dispersion;

[0008] The graphene oxide dispersion is immersed in the polydopamine modified carbon fiber felt by vacuum filtration, and then dried and placed in a heat-insulated state to obtain the graphene oxide coated carbon fiber felt;

[0009] Step C, placing the carbon fiber felt in a high-pressure impregnation kettle, adding mesophase asphalt, first evacuating, then heating, and finally pressurizing and cooling, sampling and grinding, to obtain an asphalt composite material;

[0010] Step D, placing the asphalt composite material into a quartz tube furnace for high temperature heat treatment, and then grinding it to obtain a carbon-carbon composite material;

[0011] Step E, repeating steps C and D until the carbon-carbon composite material is dense, thereby obtaining a high-density carbon-carbon composite material;

[0012] Step F: placing the high-density carbon-carbon composite material into a high-temperature graphitization furnace for graphitization treatment, and polishing to obtain a modified carbon-carbon composite material with directional arrangement of graphene.

[0013] Further improvement of the preparation method of modified carbon-carbon composite material with oriented arrangement of graphene:

[0014] Preferably, the pH of the tris(hydroxymethylaminomethane)-hydrochloric acid buffer in step A is 8.5, the concentration of tris(hydroxymethylaminomethane) is 1-20 mmol / L, and the addition ratio of dopamine hydrochloride in the tris(hydroxymethylaminomethane)-hydrochloric acid buffer is (0.5-1) g:100 ml.

[0015] Preferably, in step A, the amount of polyacrylonitrile-based carbon fiber felt added to the polydopamine-modified solution is 5 to 20 g / 100 ml, and the reaction is stirred in an oil bath environment at 40 to 100° C. for 5 to 48 hours; after washing, it is placed in an oven at a temperature of 30 to 100° C. and dried for 1 to 12 hours to obtain polydopamine-modified carbon fiber felt.

[0016] Preferably, in step B, graphene oxide is added to N,N-dimethylamide and mixed, and the stirring time at room temperature and ultrasonic crushing time are 2 to 12 hours respectively, to obtain a graphene oxide dispersion with a concentration of 0.01 to 5 g / mL.

[0017] Preferably, in step B, the graphene oxide dispersion is immersed in the polydopamine modified carbon fiber felt by vacuum filtration through a Buchner funnel, with the filtration frequency on each side being 1 to 10 times, and then dried at 30 to 100° C. for 1 to 12 hours, and placed at a constant temperature of 40 to 100° C. for 2 to 12 hours to obtain the graphene oxide coated carbon fiber felt.

[0018] Preferably, in step C, the carbon fiber felt is placed in a high-pressure impregnation kettle and the mesophase asphalt is added. It is first evacuated to -40kPa to -200kPa, then heated to a temperature 10 to 100°C higher than the softening point of the mesophase asphalt, and finally filled with high-purity nitrogen to provide a pressurization pressure of 1.5MPa to 4.5MPa. After cooling, the sample is taken and polished to obtain an asphalt composite material.

[0019] Preferably, in step C, the ratio of carbon fiber felt to mesophase pitch is 1 cm 3 :(1~10)g.

[0020] Preferably, in step D, the asphalt composite material is placed in a quartz tube furnace, high-purity nitrogen is used as a protective gas, the temperature is increased from room temperature to 200°C at a rate of 1 to 5°C / min and kept warm for 5 to 30 minutes, then the temperature is increased to 600°C at a rate of 0.1 to 5°C / min, and then the temperature is increased to 900°C at a rate of 1 to 10°C / min and kept warm for 0.5-2h, and finally the temperature is naturally cooled to room temperature to obtain a carbon-carbon composite material.

[0021] Preferably, in step F, the specific process of placing the high-density carbon-carbon composite material into a high-temperature graphitization furnace for graphitization treatment is as follows: using high-purity argon as a protective gas, the high-temperature graphitization furnace is heated from room temperature to 1000°C at a rate of 1 to 10°C / min and kept warm for 5 to 30 minutes, then heated to 1800°C at a rate of 1 to 10°C / min and kept warm for 5 to 30 minutes, then heated to 2000°C at a heating rate of 1 to 10°C / min and kept warm for 5 to 30 minutes, then heated to 2500°C at a heating rate of 1 to 10°C / min and kept warm for 5 to 60 minutes, and finally cooled naturally to room temperature.

[0022] A second object of the present invention is to provide a modified carbon-carbon composite material with directional arrangement of graphene obtained by the preparation method of the modified carbon-carbon composite material with directional arrangement of graphene described in any one of the above items.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1) The present invention provides a method for preparing a modified carbon-carbon composite material with directional arrangement of graphene, and the specific process is as follows: graphene is first modified with polydopamine on the surface of smooth carbon fiber by suction filtration and impregnation, and excess impurities are washed off with deionized water and anhydrous ethanol and then dried so that the fiber surface is coated with a rough organic layer, and then graphene oxide is dispersed in N, N-dimethylamide solvent, and after stirring and ultrasonic crushing, the graphene oxide sheets are fully opened and evenly dispersed in the solvent. The dispersed graphene oxide is filtered and impregnated into the modified carbon fiber felt through a Buchner funnel, and the graphene oxide is fully entered into the interior of the carbon fiber felt after multiple suction filtration and impregnation on the upper and lower surfaces of the carbon fiber felt, and then the excess graphene oxide not coated on the carbon fiber is washed with N, N-dimethylamide solvent, and then the carbon fiber felt with graphene directional arrangement along the carbon fiber is obtained after drying. Finally, the intermediate phase pitch is impregnated by the liquid phase impregnation method, and a modified carbon-carbon composite material with directional arrangement of graphene is prepared by carbonization and densification, and finally graphitization. The effect on the anisotropic thermal conductivity of the carbon-carbon composite material is achieved, and the tensile mechanical properties and plasticity of the material are improved. The preparation method can be mass-produced in the field of material preparation, and the preparation process is simple, the reaction process is easy to control, the production cost is reduced, and the mechanical properties and thermal conductivity of the prepared graphene-modified carbon-carbon composite material are improved.

[0025] 2) Carbon fiber felt is a three-dimensional carbon fiber braid. Introducing graphene oxide into this structure has high technical difficulty. The present invention introduces graphene oxide into a three-dimensional carbon fiber braid, and then impregnates the intermediate phase asphalt by liquid phase impregnation to prepare a layered carbon-carbon composite material, thereby realizing the introduction of graphene oxide into a three-dimensional interwoven carbon fiber mesh structure. The thermal conductivity is improved in the XY plane, slightly decreased in the XZ plane, and the tensile properties and plasticity of the material are enhanced. The overall mechanical properties of the composite material prepared will be better than those of carbon-carbon composite materials stacked with carbon fibers and carbon cloth, and different special-shaped parts can be constructed according to the application scenarios to meet the structural requirements of different application scenario areas. In the modified carbon-carbon composite material with directional arrangement of graphene prepared by the present invention, graphene oxide is distributed in a directional manner. Compared with unmodified carbon-carbon composite materials, the modified carbon-carbon composite material with directional arrangement of graphene prepared in this application has higher anisotropic thermal conductivity, and its production cost is low, which provides a new idea for the design of high thermal conductivity carbon-carbon composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solution of the embodiment of the present invention, the following is a brief introduction to the drawings required for the description of the embodiment. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In order to more clearly show the technical solution provided by the present invention and the technical effects produced, the method for modifying the carbon-carbon composite material with oriented arrangement of graphene oxide provided by the embodiment of the present invention is described in detail below with a specific embodiment.

[0027] Figure 1 The scanning electron microscope photographs are taken at a magnification of 10k to detect the morphology of the surface of the carbon fiber felt used before preparing the carbon-carbon composite materials in Examples 1 to 3 of the present invention and Comparative Example 1 using a scanning electron microscope.

[0028] Figure 2 The Raman spectra of the carbon-carbon composite materials prepared in Examples 1 to 3 and Comparative Example 1 are in two directions, wherein a is the Raman spectrum in the XY direction, and b is the Raman spectrum in the XZ direction.

[0029] Figure 3 The X-ray diffraction patterns of the matrix carbon of the carbon-carbon composite materials prepared in Examples 1 to 3 and Comparative Example 1 are shown.

[0030] Figure 4 This is a graph showing the thermal conductivity data of the carbon-carbon composite materials prepared in Examples 1 to 3 and Comparative Example 1.

[0031] Figure 5 This is a mechanical property test of the carbon-carbon composite material prepared in Examples 1 to 3 and Comparative Example 1, wherein a is a tensile stress curve and b is a tensile mechanical property diagram. DETAILED DESCRIPTION

[0032] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present invention.

[0033] The following is a detailed description of the method for preparing a modified carbon-carbon composite material with oriented graphene oxide provided by the present invention. The contents not described in detail in the embodiments of the present invention belong to the prior art known to professionals in the field.

[0034] Example 1

[0035] This embodiment provides a method for preparing a modified carbon-carbon composite material with oriented graphene oxide, which specifically comprises the following steps:

[0036] Step a, weigh 0.12g of tris(hydroxymethylaminomethane) and 0.1mL of hydrochloric acid, put them into a beaker containing 100mL of deionized water, stir them evenly at room temperature with a magnetic stirrer, the pH value is 8.5, and the concentration of tris(hydroxymethylaminomethane) is 10mmol / L, to prepare tris(hydroxymethylaminomethane)-hydrochloric acid buffer solution;

[0037] Then, 0.5 g of dopamine hydrochloride was added to the tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution and stirred evenly at room temperature using a magnetic stirrer to obtain a polydopamine modified solution;

[0038] 6.4 g of polyacrylonitrile-based carbon fiber felt was immersed in the polydopamine modified solution, magnetically stirred at an oil bath temperature of 60° C. for 12 h, then taken out and washed with deionized water and anhydrous ethanol in sequence, and then placed in an oven at 60° C. for 4 h to obtain a polydopamine modified carbon fiber felt;

[0039] Step b, adding graphene oxide to N,N-dimethylamide at a concentration of 0.4 g / mL, stirring at room temperature and ultrasonically crushing for 4 hours each, to obtain a graphene oxide dispersion;

[0040] The graphene oxide dispersion was impregnated into the polydopamine modified carbon fiber felt using a Buchner funnel by vacuum filtration, and each surface was repeatedly impregnated 3 times. The carbon fiber felt was then filtered and rinsed with N,N-dimethylamide solvent, and then placed in an oven at 60°C for 6 hours and placed at a constant temperature of 80°C for 10 hours to obtain a graphene oxide-coated carbon fiber felt.

[0041] Step c: Move the graphene oxide coated carbon fiber felt into a high pressure impregnation kettle, and add 1.2 kg of mesophase pitch at the same time. The ratio of carbon fiber felt to mesophase pitch is 1 cm 3 :5g; first evacuate to -100kPa, then heat to a temperature 50°C higher than the softening point of the mesophase asphalt, and finally fill with high-purity nitrogen (N2≥99.999%) to provide a pressure of 2.4MPa for pressurization and cooling, sample and grind to obtain an asphalt composite material;

[0042] Step d, placing the asphalt composite material in a quartz tube furnace with high-purity nitrogen (N2≥99.999%) as a protective gas, heating from room temperature to 200°C at a rate of 5°C / min and keeping warm for 20min, then heating to 600°C at a rate of 0.2°C / min, and then heating to 900°C at a rate of 5°C / min and keeping warm for 1h, finally naturally cooling to room temperature, and then grinding to obtain a carbon-carbon composite material;

[0043] Step e, immersing the carbon-carbon composite material into the mesophase pitch, repeating steps c1 and d1 until the carbon-carbon composite material is difficult to be dense, thereby obtaining a high-density carbon-carbon composite material;

[0044] Step f, using high-purity argon (Ar≥99.999%) as a protective gas, placing the high-density carbon-carbon composite material into a high-temperature graphitization furnace, heating the high-temperature graphitization furnace from room temperature to 1000°C at a rate of 10°C / min and keeping it warm for 30min, then heating it to 1800°C at a rate of 10°C / min and keeping it warm for 30min, then heating it to 2000°C at a heating rate of 5°C / min and keeping it warm for 30min, then heating it to 2500°C at a heating rate of 5°C / min and keeping it warm for 30min, finally cooling it naturally to room temperature for polishing, and obtaining a modified carbon-carbon composite material with directional arrangement of graphene, recorded as GO1-C / C.

[0045] Example 2

[0046] This embodiment provides a method for preparing a modified carbon-carbon composite material with oriented graphene oxide. The specific steps are as described in Example 1, except that in step b1, graphene oxide is added to N,N-dimethylamide at a concentration of 0.6 g / mL. Finally, a modified carbon-carbon composite material with oriented graphene is obtained, which is recorded as GO2-C / C.

[0047] Example 3

[0048] This embodiment provides a method for preparing a modified carbon-carbon composite material with oriented graphene oxide. The specific steps are referred to Example 1, except that in step b1, graphene oxide is added to N,N-dimethylamide at a concentration of 1.0 g / mL. Finally, a modified carbon-carbon composite material with oriented graphene is obtained, which is recorded as GO3-C / C.

[0049] Example 4

[0050] This embodiment provides a method for preparing a modified carbon-carbon composite material with oriented graphene oxide, which specifically comprises the following steps:

[0051] Step a, weigh 0.12g of tris(hydroxymethylaminomethane) and 0.1mL of hydrochloric acid, put them into a beaker containing 100mL of deionized water, stir them evenly at room temperature with a magnetic stirrer, the pH value is 8.5, and the concentration of tris(hydroxymethylaminomethane) is 1mmol / L, to prepare tris(hydroxymethylaminomethane)-hydrochloric acid buffer solution;

[0052] Then, 0.8 g of dopamine hydrochloride was added to the tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution and stirred evenly at room temperature using a magnetic stirrer to obtain a polydopamine modified solution;

[0053] 5 g of polyacrylonitrile-based carbon fiber felt was immersed in the polydopamine modified solution, magnetically stirred at an oil bath temperature of 40° C. for 48 h, then taken out and washed with deionized water and anhydrous ethanol in sequence, and then placed in an oven at 30° C. for 12 h to obtain a polydopamine modified carbon fiber felt;

[0054] Step b, adding graphene oxide to N,N-dimethylamide at a concentration of 0.01 g / mL, stirring at room temperature for 2 h and ultrasonically crushing for 12 h to obtain a graphene oxide dispersion;

[0055] The graphene oxide dispersion was impregnated into the polydopamine modified carbon fiber felt using a Buchner funnel by vacuum filtration, and each surface was repeatedly impregnated once, and then the carbon fiber felt was filtered and rinsed with N, N-dimethylamide solvent, and then placed in an oven at 60°C for 6 hours, and placed at a constant temperature of 40°C for 12 hours to obtain a graphene oxide-coated carbon fiber felt;

[0056] Step c: Move the graphene oxide coated carbon fiber felt into a high pressure impregnation kettle, and add 1.2 kg of mesophase pitch at the same time. The ratio of carbon fiber felt to mesophase pitch is 1 cm 3 :10g; first evacuate to -200kPa, then heat to a temperature 100°C higher than the softening point of the mesophase asphalt, and finally fill with high-purity nitrogen (N2≥99.999%) to provide a pressure of 4.5MPa for pressurization and cooling, sample and grind to obtain an asphalt composite material;

[0057] Step d, placing the asphalt composite material in a quartz tube furnace with high-purity nitrogen (N2≥99.999%) as a protective gas, heating from room temperature to 200°C at a rate of 1°C / min and keeping warm for 5 minutes, then heating to 600°C at a rate of 0.1°C / min, and then heating to 900°C at a rate of 1°C / min and keeping warm for 2 hours, finally naturally cooling to room temperature, and then grinding to obtain a carbon-carbon composite material;

[0058] Step e, immersing the carbon-carbon composite material into the mesophase pitch, repeating steps c2 and d2 until the carbon-carbon composite material is difficult to be dense, thereby obtaining a high-density carbon-carbon composite material;

[0059] Step f, using high-purity argon (Ar≥99.999%) as a protective gas, placing the high-density carbon-carbon composite material into a high-temperature graphitization furnace, heating the high-temperature graphitization furnace from room temperature to 1000°C at a rate of 1°C / min and keeping it for 5 minutes, then heating it to 1800°C at a rate of 1°C / min and keeping it for 5 minutes, then heating it to 2000°C at a heating rate of 1°C / min and keeping it for 5 minutes, then heating it to 2500°C at a heating rate of 1°C / min and keeping it for 5 minutes, finally cooling it naturally to room temperature for polishing to obtain a modified carbon-carbon composite material with directional arrangement of graphene, recorded as GO4-C / C.

[0060] Example 5

[0061] This embodiment provides a method for preparing a modified carbon-carbon composite material with oriented graphene oxide, which specifically comprises the following steps:

[0062] Step a, weigh 0.12g of tris(hydroxymethylaminomethane) and 0.1mL of hydrochloric acid, put them into a beaker containing 100mL of deionized water, stir them evenly at room temperature with a magnetic stirrer, the pH value is 8.5, and the concentration of tris(hydroxymethylaminomethane) is 20mmol / L, to prepare tris(hydroxymethylaminomethane)-hydrochloric acid buffer solution;

[0063] Then, 1 g of dopamine hydrochloride was added to the tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution and stirred evenly at room temperature using a magnetic stirrer to obtain a polydopamine modified solution;

[0064] 20 g of polyacrylonitrile-based carbon fiber felt was immersed in the polydopamine modified solution, magnetically stirred at an oil bath temperature of 100° C. for 5 h, then taken out and washed with deionized water and anhydrous ethanol in sequence, and then placed in an oven at 100° C. for 1 h to obtain a polydopamine modified carbon fiber felt;

[0065] Step b, adding graphene oxide to N,N-dimethylamide at a concentration of 5 g / mL, stirring at room temperature for 12 h and ultrasonically crushing for 2 h to obtain a graphene oxide dispersion;

[0066] The graphene oxide dispersion was impregnated into the polydopamine modified carbon fiber felt using a Buchner funnel by vacuum filtration, and each surface was repeatedly impregnated 10 times. The carbon fiber felt was then filtered and rinsed with an N,N-dimethylamide solvent, and then placed in an oven at 100°C for 1 hour and placed at a constant temperature of 100°C for 2 hours to obtain a graphene oxide-coated carbon fiber felt.

[0067] Step c: Move the graphene oxide coated carbon fiber felt into a high pressure impregnation kettle, and add 1.2 kg of mesophase pitch at the same time. The ratio of carbon fiber felt to mesophase pitch is 1 cm 3:1g; first evacuate to -40kPa, then heat to a temperature 10°C higher than the softening point of the mesophase asphalt, and finally fill with high-purity nitrogen (N2≥99.999%) to provide a pressure of 1.5MPa for pressurization and cooling, sample and grind to obtain an asphalt composite material;

[0068] Step d, placing the asphalt composite material in a quartz tube furnace with high-purity nitrogen (N2≥99.999%) as a protective gas, heating from room temperature to 200°C at a rate of 5°C / min and keeping warm for 30 minutes, then heating to 600°C at a rate of 5°C / min, and then heating to 900°C at a rate of 10°C / min and keeping warm for 0.5h, finally cooling naturally to room temperature, and then grinding to obtain a carbon-carbon composite material;

[0069] Step e, immersing the carbon-carbon composite material into the mesophase pitch, repeating steps c3 and d3 until the carbon-carbon composite material is difficult to be dense, thereby obtaining a high-density carbon-carbon composite material;

[0070] Step f, using high-purity argon (Ar≥99.999%) as a protective gas, placing the high-density carbon-carbon composite material into a high-temperature graphitization furnace, heating the high-temperature graphitization furnace from room temperature to 1000°C at a rate of 10°C / min and keeping it warm for 30min, then heating it to 1800°C at a rate of 10°C / min and keeping it warm for 30min, then heating it to 2000°C at a heating rate of 10°C / min and keeping it warm for 30min, then heating it to 2500°C at a heating rate of 10°C / min and keeping it warm for 60min, finally cooling it naturally to room temperature for polishing, and obtaining a modified carbon-carbon composite material with directional arrangement of graphene, recorded as GO5-C / C.

[0071] Comparative Example 1

[0072] This comparative example provides a method for preparing a graphene oxide oriented carbon-carbon composite material, which specifically comprises the following steps:

[0073] Step a1, transfer 6.4g of untreated carbon fiber felt into a high-pressure impregnation kettle, add 1.2kg of mesophase asphalt, first evacuate to -100kPa, then heat to a temperature 50°C higher than the softening point of the mesophase asphalt, and finally fill with high-purity nitrogen (N2≥99.999%) to provide a pressure of 2.4MPa for pressurization and cooling, take samples and grind, and obtain an asphalt composite material;

[0074] Step b1, placing the asphalt composite material in a quartz tube furnace with high-purity nitrogen (N2≥99.999%) as a protective gas, heating from room temperature to 200°C at a rate of 5°C / min and keeping warm for 20min, then heating to 600°C at a rate of 0.2°C / min, and then heating to 900°C at a rate of 5°C / min and keeping warm for 1h, finally cooling naturally to room temperature, and then grinding to obtain a carbon-carbon composite material;

[0075] Step c1, immersing the carbon-carbon composite material into the mesophase pitch, repeating steps a1 and b1 until the carbon-carbon composite material is difficult to be dense, thereby obtaining a high-density carbon-carbon composite material;

[0076] Step d1, using high-purity argon (Ar≥99.999%) as a protective gas, placing a high-density carbon-carbon composite material into a high-temperature graphitization furnace, heating the high-temperature graphitization furnace from room temperature to 1000°C at a rate of 10°C / min and keeping it warm for 30 minutes, then heating it to 1800°C at a rate of 10°C / min and keeping it warm for 30 minutes, then heating it to 2000°C at a heating rate of 5°C / min and keeping it warm for 30 minutes, then heating it to 2500°C at a heating rate of 5°C / min and keeping it warm for 30 minutes, finally cooling it naturally to room temperature for polishing to obtain a modified carbon-carbon composite material with directional arrangement of graphene, recorded as C / C.

[0077] Morphology observation and performance testing

[0078] The carbon-carbon composites prepared in Examples 1 to 3 of the present invention and Comparative Example 1 were subjected to morphological observation and performance testing, and the following results were obtained:

[0079] (1) The fiber surface of the carbon fiber felt used in Examples 1 to 3 of the present invention and Comparative Example 1 was tested by scanning electron microscopy to obtain the following: Figure 1 The scanning electron microscope photo shown. Figure 1 Figure a is a FESEM photo of the graphene-coated carbon fiber prepared in Example 1 of the present invention; Figure 1 b is a FESEM photo of the graphene-coated carbon fiber prepared in Example 2 of the present invention; Figure 1 Figure c is a FESEM photo of the graphene-coated carbon fiber prepared in Example 3 of the present invention; Figure 1 d is a FESEM photo of the comparative example 1 of the present invention without any treatment. Examples 1 to 3 are impregnated with graphene oxide at concentrations of 0.4 g / mL, 0.6 g / mL, and 1.0 g / mL, respectively, while the comparative example is not impregnated with graphene oxide. Figure 1It can be seen that as the concentration of the impregnated graphene oxide solution increases, more graphene oxide is coated on the surface of the carbon fiber, and the dispersion becomes denser. When the concentration of the graphene oxide solution reaches 1g / mL, the distribution of graphene oxide on the carbon fiber begins to agglomerate. Among them, the dispersion effect of graphene oxide in Example 2 is the best; there is no graphene oxide in Comparative Example 1.

[0080] (2) The graphite spectrum was collected using a confocal Raman system with an excitation wavelength of 532 nm. Figure 2 The Raman spectrum shown in Figure 2. Figure 2 A and Figure 2 b is the Raman spectrum of the carbon-carbon composite material prepared in Examples 1 to 3 of the present invention and Comparative Example 1 on the XY and XZ planes of the matrix graphite; Figure 2 It can be seen that the GO2-C / C of Example 2 of the present invention has an I D / I G The ratio of GO3-C / C in Example 3 is the smallest, so the graphite defects are the least. D / I G The ratio is the largest, that is, the graphite defects are the most. On the XZ plane, the comparative example has the least defects, while the GO3-C / C of Example 3 has the most defects. This shows that as the content of graphene oxide increases, the defects of graphite on the XY plane of the composite material decrease and then increase, while on the XZ plane, the defects increase in a group. That is, graphene oxide can reduce the graphite defects on the XY plane of the composite material within a certain range, but it will also increase the graphite defects on the XZ plane.

[0081] (3) Using X-ray diffraction spectroscopy to collect spectra of the matrix graphite of the carbon-carbon composite material, the following is obtained: Figure 3 The XRD spectrum shown in the figure shows the information peak of the matrix carbon XRD of the carbon-carbon composite material prepared in Examples 1 to 3 of the present invention and Comparative Example 1. By calculating the graphitization degree, it can be found that the graphitization degree of GO2-C / C of Example 2 is the highest, while the graphitization degree of C / C of the comparative example is the lowest. And the graphitization degree is improved with the introduction of graphene. It shows that the appropriate introduction of graphene oxide can indeed improve the graphitization degree of the matrix carbon of the carbon-carbon composite material.

[0082] (4) The thermal conductivity of carbon-carbon composite materials on the XY plane and XZ plane was tested using a laser thermal conductivity meter, and the following Figure 4The thermal conductivity data shown. The figure shows the thermal conductivity of the carbon-carbon composite materials prepared in Examples 1 to 3 of the present invention and Comparative Example 1. It can be found that the thermal conductivity of GO2-C / C in Example 2 is the highest in the XY plane, while the lowest is GO3-C / C in Example 3. The thermal conductivity in the XZ plane is the highest in the comparative example, and the lowest is still in Example 3. It can be explained that the introduction of an appropriate amount of graphene oxide can indeed improve the thermal conductivity of the carbon-carbon composite material in the XY plane, and the introduction of graphene oxide will reduce the thermal conductivity of the carbon-carbon composite material in the XZ plane within a certain range.

[0083] (5) The mechanical properties of carbon-carbon composite materials were tested using an electronic universal testing machine, and the following Figure 5 The mechanical properties data shown. Figure 5 In a, there is a tensile stress curve of the carbon-carbon composite materials prepared in Examples 1 to 3 of the present invention and Comparative Example 1. It can be seen that the tensile strength of GO2-C / C of Example 2 is the largest, and the tensile elongation at break is also the largest. Figure 5 b is the tensile modulus and tensile strength obtained after calculation. It can be found that the tensile modulus of GO2-C / C in Example 2 is the smallest. It can be explained that the appropriate introduction of graphene can improve the tensile strength of the carbon-carbon composite material. At the same time, the plasticity of the material is also improved.

[0084] In Example 4 and Example 5, respectively, polydopamine-modified carbon fiber felt was impregnated with graphene oxide at a concentration of 0.01 g / mL and 5 g / mL. After testing, the performance test data of GO4-C / C prepared in Example 4 is that the thermal conductivity is 186 and 123 W / (m·K) in the XY plane and XZ plane, respectively, which is almost the same as the thermal conductivity of the carbon-carbon composite material without graphene. In terms of mechanical properties, there is almost no difference from the carbon-carbon composite material without graphene, and the tensile strength is 12.76 Mpa. The performance test data of GO5-C / C prepared in Example 5 is that the thermal conductivity is 163 and 101 W / (m·K) in the XY plane and XZ plane, respectively, which is not much different from the thermal conductivity of Example 3. It also has the same effect as Example 3 in terms of mechanical properties, and the tensile strength is 12.71 Mpa. It can be clearly found that the introduction of too little and too much graphene for the performance of carbon-carbon composite materials is presented within the range of Example 1-Example 3.

[0085] In summary, it can be seen that the embodiment of the present invention not only has a simple preparation process, an easy-to-control reaction process, and reduces production costs, but also improves the mechanical properties and thermal conductivity of the prepared graphene-modified carbon-carbon composite material. At the same time, the content of graphene can adjust the directional thermal conductivity of the carbon-carbon composite material, which also provides ideas for designing a method for directional thermal conductivity carbon / carbon composite materials.

[0086] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

[0087] Those skilled in the art should understand that the above are only some specific embodiments of the present invention, rather than all embodiments. It should be noted that for those of ordinary skill in the art, many modifications and improvements can be made, and all modifications or improvements that do not exceed the scope of protection of the present invention should be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a modified carbon-carbon composite material with oriented graphene, characterized in that: The following steps are involved: Step A, adding dopamine hydrochloride to tris(hydroxymethylaminomethane)-hydrochloric acid buffer, stirring at a constant temperature until the mixture is uniformly mixed to obtain a polydopamine modified solution; Adding polyacrylonitrile-based carbon fiber felt to the polydopamine modified solution, stirring and reacting in an oil bath environment, washing and drying, then washing with deionized water and anhydrous ethanol, and drying in an oven to obtain polydopamine modified carbon fiber felt; Step B, adding graphene oxide to N,N-dimethylamide, mixing, stirring at room temperature and ultrasonically crushing to obtain a graphene oxide dispersion; The graphene oxide dispersion is immersed in the polydopamine modified carbon fiber felt by vacuum filtration, and then dried and placed in a heat-insulated state to obtain the graphene oxide coated carbon fiber felt; Step C, placing the carbon fiber felt in a high-pressure impregnation kettle, adding mesophase asphalt, first evacuating, then heating, and finally pressurizing and cooling, sampling and grinding, to obtain an asphalt composite material; Step D, placing the asphalt composite material into a quartz tube furnace for high temperature heat treatment, and then grinding it to obtain a carbon-carbon composite material; Step E, repeating steps C and D until the carbon-carbon composite material is dense, thereby obtaining a high-density carbon-carbon composite material; Step F: placing the high-density carbon-carbon composite material into a high-temperature graphitization furnace for graphitization treatment, and polishing to obtain a modified carbon-carbon composite material with directional arrangement of graphene.

2. The method for preparing the modified carbon-carbon composite material with oriented graphene arrangement according to claim 1, characterized in that: The pH of the tris(hydroxymethylaminomethane)-hydrochloric acid buffer in step A is 8.5, the concentration of tris(hydroxymethylaminomethane) is 1-20mmol / L, and the addition ratio of dopamine hydrochloride in the tris(hydroxymethylaminomethane)-hydrochloric acid buffer is (0.5-1)g:100ml.

3. The method for preparing the modified carbon-carbon composite material with oriented graphene arrangement according to claim 1, characterized in that: In step A, the amount of polyacrylonitrile-based carbon fiber felt added to the polydopamine modified solution is 5 to 20 g / 100 ml, and the mixture is stirred and reacted in an oil bath environment at 40 to 100° C. for 5 to 48 hours. After washing, the mixture is placed in an oven at a temperature of 30 to 100° C. and dried for 1 to 12 hours to obtain polydopamine modified carbon fiber felt.

4. The method for preparing the modified carbon-carbon composite material with oriented graphene arrangement according to claim 1, characterized in that: In step B, graphene oxide is added to N,N-dimethylamide and mixed, and the stirring time at room temperature and ultrasonic crushing time are 2 to 12 hours respectively, to prepare a graphene oxide dispersion with a concentration of 0.01 to 5 g / mL.

5. The method for preparing the modified carbon-carbon composite material with oriented graphene arrangement according to claim 1 or 4, characterized in that: In step B, the graphene oxide dispersion is immersed in the polydopamine modified carbon fiber felt by vacuum filtration through a Buchner funnel, with each side being filtered 1 to 10 times, and then dried at 30 to 100° C. for 1 to 12 hours, and placed at a constant temperature of 40 to 100° C. for 2 to 12 hours to obtain the graphene oxide coated carbon fiber felt.

6. The method for preparing the modified carbon-carbon composite material with oriented graphene arrangement according to claim 1, characterized in that: In step C, the carbon fiber felt is placed in a high-pressure impregnation kettle and the mesophase asphalt is added. The kettle is first evacuated to -40 kPa to -200 kPa, then heated to a temperature 10 to 100 °C higher than the softening point of the mesophase asphalt, and finally filled with high-purity nitrogen to provide a pressurization pressure of 1.5 MPa to 4.5 MPa. After cooling, the kettle is sampled and polished to obtain an asphalt composite material.

7. The method for preparing the modified carbon-carbon composite material with oriented graphene arrangement according to claim 1 or 6, characterized in that: In step C, the ratio of carbon fiber felt to mesophase pitch is 1 cm 3 :(1~10)g.

8. The method for preparing the modified carbon-carbon composite material with oriented graphene arrangement according to claim 1, characterized in that: In step D, the asphalt composite material is placed in a quartz tube furnace, high-purity nitrogen is used as a protective gas, and the temperature is increased from room temperature to 200°C at a rate of 1 to 5°C / min and kept at this temperature for 5 to 30 minutes, then increased to 600°C at a rate of 0.1 to 5°C / min, and then increased to 900°C at a rate of 1 to 10°C / min and kept at this temperature for 0.5 to 2 hours, and finally naturally cooled to room temperature to obtain a carbon-carbon composite material.

9. The method for preparing the modified carbon-carbon composite material with oriented graphene arrangement according to claim 1, characterized in that: In step F, the specific process of placing the high-density carbon-carbon composite material into a high-temperature graphitization furnace for graphitization treatment is as follows: using high-purity argon as a protective gas, the high-temperature graphitization furnace is heated from room temperature to 1000°C at a rate of 1 to 10°C / min and kept warm for 5 to 30 minutes, then heated to 1800°C at a rate of 1 to 10°C / min and kept warm for 5 to 30 minutes, then heated to 2000°C at a rate of 1 to 10°C / min and kept warm for 5 to 30 minutes, then heated to 2500°C at a rate of 1 to 10°C / min and kept warm for 5 to 60 minutes, and finally cooled naturally to room temperature.

10. A modified carbon-carbon composite material with oriented graphene obtained by the method for preparing a modified carbon-carbon composite material with oriented graphene according to any one of claims 1 to 9.

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