Carbon fiber-doped graphene oxide foam material, preparation method therefor and use thereof

Abstract

The present invention relates to the technical field of high thermal insulation carbon materials and provides a carbon fiber-doped graphene oxide foam material, a preparation method therefor, and a use thereof. In the present invention, graphene oxide and carbon fibers are composited in a hydrothermal synthesis manner, the resulting composite is processed into a composite aerogel in a freeze drying manner, and the composite aerogel is carbonized and graphitized to prepare the carbon fiber-doped graphene oxide foam material. The carbon fiber-doped graphene oxide foam material of the present invention can resist a high temperature of 2000-3000℃. The carbon fiber-doped graphene oxide foam material has a heat conductivity coefficient of 0.16-0.27 W / m·K and a porosity of 85-95%. The carbon fiber-doped graphene oxide foam material has excellent high-temperature resistance and stability, and maintains good mechanical properties and structural strength while improving the heat insulation performance.

Description

A carbon fiber-doped graphene oxide foam material, its preparation method and applications Technical Field

[0001] This invention relates to the field of high heat-resistant carbon materials technology, and in particular to a carbon fiber-doped graphene oxide foam material, its preparation method, and its applications. Background Technology

[0002] Temperature difference is the fundamental cause of heat transfer. When a temperature difference exists, the high-temperature device transfers heat to the low-temperature device, causing heat loss from the high-temperature device and resulting in poor product quality and low yield. Furthermore, the materials used in many low-temperature devices are not heat-resistant, leading to melting, combustion, or even explosion. To avoid these dangers and improve product quality and yield, it is necessary to block heat transfer between the high-temperature and low-temperature devices. Therefore, insulation materials are needed on the exterior of the high-temperature device to block heat. Currently, commonly used insulation materials in industry include graphite, ceramic fibers, and foam materials. Graphite can withstand temperatures up to approximately 450-500℃; above this temperature, it oxidizes and transforms into carbon dioxide. Therefore, pure graphite cannot be used as insulation material under ultra-high temperature conditions. Ceramic materials, on the other hand, are insulation materials made primarily from high-purity alumina, siloxanes, and zinc titanates, and can withstand temperatures up to 1600℃. Therefore, ceramic insulation materials have been widely adopted.

[0003] CN105110814A discloses a high-temperature resistant heat-insulating material and its preparation method. The high porosity and good heat-insulating effect of waste foam plastic as a pore-forming agent are used to prepare the high-temperature resistant heat-insulating material. The aggregate is a high-temperature resistant ceramic material to improve the heat resistance of the overall structure.

[0004] However, most ceramic materials can only withstand temperatures around 1600℃, making it difficult to achieve higher temperature resistance. Furthermore, ceramic materials are relatively brittle and lack flexibility, making them prone to breakage and powdering during practical use, hindering long-term stable operation. Their relatively heavy weight also makes them unsuitable for lightweight applications. Therefore, it is necessary to improve the flexibility and durability of thermal insulation materials while reducing their weight.

[0005] In the process of heat transfer, the modes of transfer typically include solid-to-gas heat transfer. Solid-to-gas heat transfer is faster, while gas-to-gas heat transfer has a very low thermal conductivity. Because it slows down the heat transfer rate, it can achieve a heat insulation effect. Therefore, selecting materials with high porosity and numerous pores as insulation materials can achieve effective heat insulation. Porous aerogel materials can utilize the pores in the aerogel material to change the direction of heat transfer, thus lengthening the overall heat transfer path and slowing down the heat transfer rate. By utilizing the heat insulation properties of aerogels, new high-efficiency aerogel composite materials can be produced for application in the field of energy-saving buildings, exhibiting excellent heat insulation, fire resistance, sound insulation, and light transmission properties.

[0006] CN104177062B discloses a high-temperature heat-insulating aerogel composite material, comprising SiO2 aerogel and a doped light-shielding agent. The light-shielding agent is distributed in 3-5 layers in the SiO2 aerogel from the outer surface inward. The light-shielding agent used in the first doped layer from the outermost surface of the SiO2 aerogel is carbon black, and the light-shielding agent used in the remaining doped layers is silicon carbide. From the second doped layer onward, the particle size of the silicon carbide doped in each layer decreases and the mass percentage of silicon carbide in the current doped layer increases.

[0007] CN114133210B discloses an aerogel thermal insulation material and its preparation method. This invention involves uniformly mixing a silicon source aqueous solution and a cellulose solution, then adding carbon fibers, and reacting the mixture with heat to obtain a composite wet gel. This gel is then aged, modified to be hydrophobic, and finally dried at normal pressure to obtain the aerogel thermal insulation material. This technical solution adds carbon fibers to the cellulose-silica composite aerogel, further improving the mechanical properties of the composite aerogel and exhibiting superior stability when used as a thermal insulation material.

[0008] Compared to other materials, SiO2 aerogel modified materials are relatively inexpensive. Research has shown that doping SiO2 aerogel with fiber structures has become a key research focus, with carbon fiber doping being an important method for modifying aerogels. Simultaneously, carbon aerogel is also a porous thermal insulation material. It has low density, large surface area, and excellent thermal insulation performance. Its porous structure gives it extremely low thermal conductivity, effectively preventing heat conduction and transfer, thus achieving a thermal insulation effect.

[0009] CN115959856A discloses a carbon fiber@GO aerogel, its preparation method, and its applications. The carbon fiber@GO aerogel is obtained by directional freezing and drying of a mixed solution of carbon fibers, a binder, and graphene oxide. This invention combines hollow carbon fibers and graphene oxide using directional freezing technology, resulting in an aerogel that is lightweight and has good thermal insulation properties, making it an excellent thermal insulation material. The directional freezing preparation of aerogels often involves freezing a uniformly dispersed aqueous dispersion to prepare ice crystals for guided molding. However, graphene has poor dispersibility, therefore a uniformly dispersed graphene oxide dispersion is required for freezing.

[0010] CN110156432B discloses a carbon fiber composite graphene aerogel, its preparation method, and its application. The preparation method includes: (1) mixing carbon fibers, surfactants, graphene oxide, a reducing agent, and water to form a mixed dispersion; (2) stirring and foaming the mixed dispersion to obtain a mixed foam; (3) reacting the mixed foam at 65-100℃ for 2-12 hours, then cooling it to 15-35℃ to obtain a carbon fiber composite graphene hydrogel; (4) freezing the carbon fiber composite graphene hydrogel at -10 to -60℃, then drying it under normal pressure, and finally annealing it at 450-1000℃ to obtain a carbon fiber composite graphene aerogel. The pure graphene aerogel in this technical solution has poor mechanical and thermal insulation properties and is easily damaged. Furthermore, the existing preparation method is complex and costly, greatly limiting its industrial application.

[0011] In summary, carbon aerogel has become the first choice for thermal insulation materials due to its excellent high-temperature resistance and stability. However, most industries and working environments are ultra-high temperature environments, which place extremely high demands on the thermal insulation performance of thermal insulation materials. Therefore, improving the thermal insulation performance of carbon aerogel while maintaining good mechanical properties and structural strength is also a technical problem that urgently needs to be solved.

[0012] Summary of the Invention

[0013] To address the above problems, this invention provides a carbon fiber-doped graphene oxide foam material, its preparation method, and its applications. The foam material has high porosity, low thermal conductivity, and low density, thus reducing its weight. Furthermore, the foam material exhibits excellent thermal insulation performance in high-temperature environments, while also possessing high mechanical properties and good stability.

[0014] This invention provides a carbon fiber-doped graphene oxide foam material, which is made by carbonizing a composite aerogel and then graphitizing it. The foam material can withstand high temperatures of 2000-3000℃, has a thermal conductivity of 0.16-0.27 W / m·K, and a density of 0.1-0.15 g / cm³. 3The compressive strength is 150-200 kPa, the in-plane shear strength is 40-50 kPa, and the specific strength is 1.3-2 MPa·cm. 3 / g, with a porosity of 85-95%; the composite aerogel is prepared by hydrothermal and freeze-drying a mixture of graphene oxide, deionized water, carbon fiber, polyvinyl butyral resin (PVB) and hydrazine hydrate to obtain a solid aerogel, and then graphite paper is attached to the surface of the solid aerogel.

[0015] Furthermore, based on the total mass of all components in the solid aerogel, the components and their contents in the solid aerogel are as follows:

[0016] Graphene oxide: 2-5 wt%;

[0017] Deionized water: 80-90 wt%;

[0018] Carbon fiber: 3-5 wt%;

[0019] Polyvinyl butyral resin: 4-6 wt%;

[0020] Hydrazine hydrate: 1-2 wt%.

[0021] The present invention also provides a method for preparing the carbon fiber doped graphene oxide foam material, wherein the components are prepared according to the specified proportions, and the preparation method includes the following steps:

[0022] Step 1: Prepare an aqueous solution of graphene oxide by mixing graphene oxide with deionized water. Add carbon fiber and polyvinyl butyral resin to the aqueous solution of graphene oxide and stir to obtain a viscous mixed solution.

[0023] Step 2: Add hydrazine hydrate dropwise to the first mixed solution and stir to carry out a hydrothermal reaction to obtain the second mixed solution; cool the second mixed solution to room temperature and freeze-dry to obtain a solid aerogel;

[0024] Step 3: Stir and mix phenolic resin and graphene to prepare an adhesive;

[0025] Step 4: Apply the adhesive to the surface of the solid aerogel and attach graphite paper to the surface of the solid aerogel after applying the adhesive to obtain a composite aerogel; after drying the composite aerogel, carbonize it and then graphitize it to obtain the carbon fiber doped graphene oxide foam material.

[0026] Furthermore, the graphene oxide in step 1 has a particle size of 30-40 μm.

[0027] Furthermore, the carbon fiber in step 1 has a diameter of 10-30 μm and a length of 5-6 mm.

[0028] Further, in step 1, the mass ratio of graphene oxide, deionized water, carbon fiber and polyvinyl butyral resin is (2-5):(80-90):(3-5):(4-6).

[0029] Furthermore, the stirring speed in step 1 is 300-500 r / min, and the stirring time is 10-30 min.

[0030] Furthermore, the carbon fiber surface described in step 1 is stable and difficult to react with other substances. By adding polyvinyl butyral resin as a surfactant, the reactivity of the carbon fiber surface is improved.

[0031] Furthermore, in step 2, the mass ratio of hydrazine hydrate to graphene oxide is (1-2):(2-5).

[0032] Furthermore, the dripping rate in step 2 is 0.5-1 drops / s.

[0033] Furthermore, the stirring speed in step 2 is 300-500 r / min.

[0034] Furthermore, the temperature of the hydrothermal reaction in step 2 is 150-250℃, and the reaction time is 24-48h.

[0035] Furthermore, in step 2, the freeze-drying temperature is -50 to -10°C, the freeze-drying time is 24-48 hours, and the vacuum degree of the freeze-drying is 0.1 MPa.

[0036] Furthermore, in step 2, the hydrazine hydrate reduces the carbonyl and carboxyl groups on the surface of the graphene oxide to hydroxyl groups, and simultaneously forms hydrogen bonds with the oxygen atoms on the surface of the graphene oxide, thereby improving the stability of the foam material.

[0037] Furthermore, the graphene oxide reduced during the hydrothermal process in step 2 has a two-dimensional sheet structure, which can encapsulate carbon fibers and chemically bond with them, thereby improving the stability of the foam material. The hydrothermal process also provides the foam material with more porous structures, thus increasing the porosity of the foam material.

[0038] Furthermore, the hydrothermal process in step 2 creates a high-temperature and high-pressure environment for the reaction system, which reduces the activation energy of the reaction and promotes the chemical reaction between groups. In addition, the high-temperature and high-pressure hydrothermal environment can vaporize the liquid water inside the system, which can play a role in replenishing gas and foaming. Therefore, it is beneficial to form uniform and stable pores in the aerogel and form a uniform foam material as a whole.

[0039] Furthermore, in step 2, the system is in an ultra-low temperature state during the freeze-drying process, and vacuum drying is performed in the ultra-low temperature state. The water in the system sublimates and evaporates, which prevents the foam material structure from collapsing and maintains the stable porous structure and properties of the foam material.

[0040] Further, in step 3, the mass ratio of the phenolic resin to the graphene is (10:1)-(30:1).

[0041] Furthermore, the graphene in step 3 has a size of 20-40 μm and an oxygen content of 30-36%.

[0042] Furthermore, in step 3, the stirring speed is 300-500 r / min, and the stirring time is 10-30 min.

[0043] Further, in step 4, the ratio of the coating mass of the adhesive to the mass of the solid aerogel is (1:20) to (1:10).

[0044] Furthermore, the size of the graphite paper in step 4 is determined based on the size of the solid aerogel, and the thickness of the graphite paper is 100-300μm with a purity of 99.9%.

[0045] Furthermore, the drying temperature in step 4 is 50-100℃, and the drying time is 10-30 minutes.

[0046] Furthermore, the carbonization temperature in step 4 is 300-500℃, and the carbonization time is 1-2 hours.

[0047] Furthermore, inert gas is used for protection during the carbonization process in step 4.

[0048] Furthermore, the flow rate of the inert gas is 5-10 mL / min.

[0049] Furthermore, the inert gas is either argon or nitrogen.

[0050] Furthermore, the graphitization temperature in step 4 is 1500-2000℃, and the time is 1-3h.

[0051] Furthermore, inert gas is used for protection during the graphitization process in step 4.

[0052] Furthermore, the flow rate of the inert gas is 5-10 mL / min.

[0053] Furthermore, the inert gas is either argon or nitrogen.

[0054] Furthermore, the layered structure of the graphite paper in step 4 can adapt well to any surface, conduct heat uniformly on the layered structure, so that the foam material is heated evenly and will not cause local overheating of the foam material. Moreover, the microstructure of the graphite paper is similar to that of the graphene, which can form a π-π stacked structure, thereby improving the in-plane shear strength.

[0055] Furthermore, after the composite aerogel in step 4 is carbonized, its porosity increases, thereby improving the thermal insulation performance of the foam material.

[0056] The present invention also provides a thermal insulation material comprising the carbon fiber doped graphene oxide foam material, the thermal insulation material being used in a high-temperature environment of 2000-3000℃, the thermal insulation material being made of the carbon fiber doped graphene oxide foam material.

[0057] Furthermore, the thermal insulation material made from the carbon fiber-doped graphene oxide foam has high porosity and low thermal conductivity, resulting in a reduced heat transfer rate in high-temperature environments, thereby providing thermal insulation.

[0058] The beneficial effects of this invention are:

[0059] 1. The carbon fiber described in this invention has very stable surface chemical properties and is not easily combined with the graphene oxide. The surface reactivity of the carbon fiber can be improved by using the polyvinyl butyral resin as a surfactant material, thereby improving the stability of the foam material.

[0060] 2. The foam material prepared in this invention has high porosity and low thermal conductivity, which can effectively block the transfer of heat in high-temperature environments. In addition, the foam material has low density and is lightweight for the same volume, so it will not affect or hinder the heat insulation components during application.

[0061] 3. In this invention, a mixture of phenolic resin and graphene is used as a binder, which improves the adhesion between the graphite paper and the solid aerogel, increases the planar shear strength of the foam material, and makes the structure of the foam material more compact.

[0062] 4. The present invention employs a hydrothermal synthesis process, which carries out the reaction under high temperature and high pressure, thereby reducing the activation energy of the reaction, promoting the chemical reaction between groups, and making the groups firmly connected; and in the high temperature and high pressure hydrothermal environment, the liquid water in the reaction vaporizes, which plays a role in supplementing gas and foaming in the system, which is conducive to forming uniform and stable pores and provides uniform pore conditions for the foam material.

[0063] 5. This invention uses freeze-drying technology to fix and shape the material. During the freezing process, the reaction system is in an ultra-low temperature state, and vacuum drying is carried out during the freezing process to directly sublimate the water inside the material. This can maintain the original structure of the material, prevent collapse, and maintain the stable porous structure and original properties of the material.

[0064] 6. The raw materials used in this invention are relatively inexpensive, the preparation process is simple, the operation is easy, and it is easy to scale up production. Attached Figure Description

[0065] Figure 1 is a scanning electron microscope image of the cross-section of the carbon fiber doped graphene oxide foam material described in Example 1, magnified 200 times.

[0066] Figure 2 is a scanning electron microscope image of the cross-section of the carbon fiber doped graphene oxide foam material described in Example 1, magnified 5000 times.

[0067] Figure 3 is a side cross-sectional view of the carbon fiber doped graphene oxide foam material described in Example 1. Detailed Implementation

[0068] The invention will be described in detail below with reference to the embodiments:

[0069] This invention provides a carbon fiber doped graphene oxide foam material, its preparation method, and its uses. A solid aerogel is prepared by hydrothermal synthesis, and the solid aerogel is carbonized to obtain the foam material, which greatly improves the porosity and thermal insulation performance of the material.

[0070] Example 1

[0071] This embodiment provides a carbon fiber-doped graphene oxide foam material. The foam material is made by carbonizing composite aerogel and then graphitizing it. The foam material can withstand a high temperature of 3000℃, has a thermal conductivity of 0.27 W / m·K, and a density of 0.13 g / cm³. 3 The compressive strength is 180 kPa, the in-plane shear strength is 48 kPa, and the specific strength is 1.4 MPa·cm. 3 / g, with a porosity of 91%; the composite aerogel is prepared by hydrothermal and freeze-drying a mixture of graphene oxide, deionized water, carbon fiber, polyvinyl butyral resin and hydrazine hydrate to obtain a solid aerogel, and then graphite paper is attached to the surface of the solid aerogel.

[0072] This embodiment also provides a method for preparing the carbon fiber doped graphene oxide foam material, wherein the components are prepared according to the specified proportions, and the preparation method includes the following steps:

[0073] Step 1: Prepare an aqueous solution of graphene oxide by mixing graphene oxide with deionized water. Add carbon fiber and polyvinyl butyral resin to the aqueous solution of graphene oxide and stir and mix at 500 r / min for 20 min to obtain a viscous mixed solution.

[0074] Step 2: Add hydrazine hydrate dropwise to the first mixed solution at a rate of 0.5 drops / s, and perform a hydrothermal reaction at 200°C for 24 hours with a stirring speed of 500 r / min to obtain the second mixed solution; cool the second mixed solution to room temperature and freeze-dry it at -50°C for 24 hours with a vacuum degree of 0.1 MPa to obtain a solid aerogel.

[0075] Step 3: Stir the phenolic resin and graphene at 500 r / min for 20 min to prepare an adhesive;

[0076] Step 4: Coat the surface of the solid aerogel with the adhesive and attach graphite paper to the surface of the solid aerogel after coating with the adhesive to obtain a composite aerogel; dry the composite aerogel at 80°C for 30 min, then carbonize it at 450°C for 1 h under nitrogen protection at a flow rate of 10 mL / min, and then graphitize it at 1500°C under nitrogen protection at a flow rate of 10 mL / min for 3 h to obtain the carbon fiber doped graphene oxide foam material.

[0077] In this embodiment, based on the total mass of each component in the solid aerogel, the components and contents of the solid aerogel are as follows: graphene oxide: 5 wt%, deionized water: 85 wt%, carbon fiber: 3 wt%, polyvinyl butyral resin: 5 wt%, hydrazine hydrate: 2 wt%; the mass ratio of phenolic resin to graphene in the binder is 10:1; the mass ratio of the binder to the solid aerogel is 1:10.

[0078] Figure 1 is a scanning electron microscope image of the cross-section of the carbon fiber doped graphene oxide foam material described in Example 1, magnified 200 times. As can be seen from the figure, the morphology of the carbon fiber doped graphene oxide foam material is characterized by an irregular porous distribution with uniform pore size.

[0079] Figure 2 is a scanning electron microscope image of the cross-section of the carbon fiber doped graphene oxide foam material described in Example 1, magnified 5000 times. As can be seen from the figure, the pore structure of the carbon fiber doped graphene oxide foam material is relatively deep.

[0080] In this embodiment, the graphene oxide has a particle size of 40 μm and an atomic layer structure of 2-3 atomic layers.

[0081] In this embodiment, the carbon fiber has a diameter of 20 μm and a length of 5 mm.

[0082] In this embodiment, the graphene has a particle size of 40 μm and an oxygen content of 36%.

[0083] In this embodiment, the graphite paper has a thickness of 100 μm and a purity of 99.9%.

[0084] Example 2

[0085] This embodiment provides a carbon fiber-doped graphene oxide foam material. The foam material is made by carbonizing composite aerogel and then graphitizing it. The foam material can withstand a high temperature of 3000℃, has a thermal conductivity of 0.16 W / m·K, and a density of 0.1 g / cm³. 3 The compressive strength is 200 kPa, the in-plane shear strength is 40 kPa, and the specific strength is 2 MPa·cm. 3 / g, with a porosity of 95%; the composite aerogel is prepared by hydrothermal and freeze-drying a mixture of graphene oxide, deionized water, carbon fiber, polyvinyl butyral resin and hydrazine hydrate to obtain a solid aerogel, and then graphite paper is attached to the surface of the solid aerogel.

[0086] This embodiment also provides a method for preparing the carbon fiber doped graphene oxide foam material, wherein the components are prepared according to the specified proportions, and the preparation method includes the following steps:

[0087] Step 1: Prepare an aqueous solution of graphene oxide by mixing graphene oxide with deionized water. Add carbon fiber and polyvinyl butyral resin to the aqueous solution of graphene oxide and stir and mix at 300 r / min for 30 min to obtain a viscous mixed solution.

[0088] Step 2: Add hydrazine hydrate dropwise to the first mixed solution at a rate of 1 drop / s, and perform a hydrothermal reaction at 250°C for 48 hours with a stirring speed of 300 r / min to obtain the second mixed solution; cool the second mixed solution to room temperature and freeze-dry it at -10°C for 48 hours with a vacuum degree of 0.1 MPa to obtain a solid aerogel.

[0089] Step 3: Stir the phenolic resin and graphene at 300 r / min for 30 min to prepare an adhesive;

[0090] Step 4: Coat the surface of the solid aerogel with the adhesive and attach graphite paper to the surface of the solid aerogel after coating with the adhesive to obtain a composite aerogel; dry the composite aerogel at 100°C for 20 min, then carbonize it at 500°C for 1 h under nitrogen protection at a flow rate of 5 mL / min, and then graphitize it at 2000°C under nitrogen protection at a flow rate of 5 mL / min for 3 h to obtain the carbon fiber doped graphene oxide foam material.

[0091] In this embodiment, based on the total mass of each component in the solid aerogel, the components and contents of the solid aerogel are as follows: graphene oxide: 2 wt%, deionized water: 88 wt%, carbon fiber: 5 wt%, polyvinyl butyral resin: 4 wt%, hydrazine hydrate: 1 wt%; the mass ratio of phenolic resin to graphene in the binder is 10:1; the mass ratio of the binder to the solid aerogel is 1:10.

[0092] In this embodiment, the graphene oxide has a particle size of 40 μm and an atomic layer structure of 1-3 atomic layers.

[0093] In this embodiment, the carbon fiber has a diameter of 25 μm and a length of 3 mm.

[0094] In this embodiment, the graphene has a particle size of 40 μm and an oxygen content of 30%.

[0095] In this embodiment, the graphite paper has a thickness of 200 μm and a purity of 99.9%.

[0096] Example 3

[0097] This embodiment provides a carbon fiber-doped graphene oxide foam material. The foam material is made by carbonizing composite aerogel and then graphitizing it. The foam material can withstand a high temperature of 3000℃, and has a thermal conductivity of 0.2 W / m·K and a density of 0.12 g / cm³. 3 The compressive strength is 170 kPa, the in-plane shear strength is 45 kPa, and the specific strength is 1.4 MPa·cm. 3 / g, with a porosity of 90%; the composite aerogel is prepared by hydrothermal and freeze-drying a mixture of graphene oxide, deionized water, carbon fiber, polyvinyl butyral resin and hydrazine hydrate to obtain a solid aerogel, and then graphite paper is attached to the surface of the solid aerogel.

[0098] This embodiment also provides a method for preparing the carbon fiber doped graphene oxide foam material, wherein the components are prepared according to the specified proportions, and the preparation method includes the following steps:

[0099] Step 1: Prepare an aqueous solution of graphene oxide by mixing graphene oxide with deionized water. Add carbon fiber and polyvinyl butyral resin to the aqueous solution of graphene oxide and stir and mix at 500 r / min for 10 min to obtain a viscous mixed solution.

[0100] Step 2: Add hydrazine hydrate dropwise to the first mixed solution at a rate of 1 drop / s, and perform a hydrothermal reaction at 200°C for 24 hours with a stirring speed of 500 r / min to obtain the second mixed solution; cool the second mixed solution to room temperature and freeze-dry it at -50°C for 24 hours with a vacuum degree of 0.1 MPa to obtain a solid aerogel.

[0101] Step 3: Stir the phenolic resin and graphene at 500 r / min for 20 min to prepare an adhesive;

[0102] Step 4: Coat the surface of the solid aerogel with the adhesive and attach graphite paper to the surface of the solid aerogel after coating with the adhesive to obtain a composite aerogel; dry the composite aerogel at 80°C for 30 min, then carbonize it at 450°C for 1 h under nitrogen protection at a flow rate of 10 mL / min, and then graphitize it at 1500°C under nitrogen protection at a flow rate of 10 mL / min for 3 h to obtain the carbon fiber doped graphene oxide foam material.

[0103] In this embodiment, based on the total mass of each component in the solid aerogel, the components and contents of the solid aerogel are as follows: graphene oxide: 4 wt%, deionized water: 85 wt%, carbon fiber: 3 wt%, polyvinyl butyral resin: 6 wt%, hydrazine hydrate: 2 wt%; the mass ratio of phenolic resin to graphene in the binder is 10:1; the mass ratio of the binder to the solid aerogel is 1:10.

[0104] In this embodiment, the graphene oxide has a particle size of 30 μm and an atomic layer structure of 1-3 atomic layers.

[0105] In this embodiment, the carbon fiber has a diameter of 20 μm and a length of 3 mm.

[0106] In this embodiment, the graphene has a particle size of 30 μm and an oxygen content of 36%.

[0107] In this embodiment, the graphite paper has a thickness of 100 μm and a purity of 99.9%.

[0108] Example 4

[0109] This embodiment provides a carbon fiber-doped graphene oxide foam material. The foam material is made by carbonizing composite aerogel and then graphitizing it. The foam material can withstand a high temperature of 3000℃, has a thermal conductivity of 0.25 W / m·K, and a density of 0.15 g / cm³. 3 The compressive strength is 200 kPa, the in-plane shear strength is 50 kPa, and the specific strength is 1.3 MPa·cm. 3 / g, with a porosity of 85%; the composite aerogel is prepared by hydrothermal and freeze-drying a mixture of graphene oxide, deionized water, carbon fiber, polyvinyl butyral resin and hydrazine hydrate to obtain a solid aerogel, and then graphite paper is attached to the surface of the solid aerogel.

[0110] This embodiment also provides a method for preparing the carbon fiber doped graphene oxide foam material, wherein the components are prepared according to the specified proportions, and the preparation method includes the following steps:

[0111] Step 1: Prepare an aqueous solution of graphene oxide by mixing graphene oxide with deionized water. Add carbon fiber and polyvinyl butyral resin to the aqueous solution of graphene oxide and stir and mix at 500 r / min for 20 min to obtain a viscous mixed solution.

[0112] Step 2: Add hydrazine hydrate dropwise to the first mixed solution at a rate of 0.5 drops / s, and perform a hydrothermal reaction at 200°C for 24 hours with a stirring speed of 500 r / min to obtain the second mixed solution; cool the second mixed solution to room temperature and freeze-dry it at -50°C for 24 hours with a vacuum degree of 0.1 MPa to obtain a solid aerogel.

[0113] Step 3: Stir the phenolic resin and graphene at 500 r / min for 20 min to prepare an adhesive;

[0114] Step 4: Coat the surface of the solid aerogel with the adhesive and attach graphite paper to the surface of the solid aerogel after coating with the adhesive to obtain a composite aerogel; dry the composite aerogel at 80°C for 30 min, then carbonize it at 450°C for 1 h under nitrogen protection at a flow rate of 10 mL / min, and then graphitize it at 1500°C under nitrogen protection at a flow rate of 10 mL / min for 3 h to obtain the carbon fiber doped graphene oxide foam material.

[0115] In this embodiment, based on the total mass of each component in the solid aerogel, the components and contents of the solid aerogel are as follows: graphene oxide: 5 wt%, deionized water: 82.5 wt%, carbon fiber: 5 wt%, polyvinyl butyral resin: 6 wt%, hydrazine hydrate: 1.5 wt%; the mass ratio of phenolic resin to graphene in the binder is 10:1; the mass ratio of the binder to the solid aerogel is 1:10.

[0116] In this embodiment, the graphene oxide has a particle size of 40 μm and an atomic layer structure of 2-3 atomic layers.

[0117] In this embodiment, the carbon fiber has a diameter of 20 μm and a length of 5 mm.

[0118] In this embodiment, the graphene has a particle size of 40 μm and an oxygen content of 36%.

[0119] In this embodiment, the graphite paper has a thickness of 100 μm and a purity of 99.9%.

[0120] Example 5

[0121] This embodiment provides a carbon fiber-doped graphene oxide foam material. The foam material is made by carbonizing composite aerogel and then graphitizing it. The foam material can withstand a high temperature of 3000℃, has a thermal conductivity of 0.23 W / m·K, and a density of 0.11 g / cm³. 3 The compressive strength is 150 kPa, the in-plane shear strength is 45 kPa, and the specific strength is 1.4 MPa·cm. 3 / g, with a porosity of 89%; the composite aerogel is prepared by hydrothermal and freeze-drying a mixture of graphene oxide, deionized water, carbon fiber, polyvinyl butyral resin and hydrazine hydrate to obtain a solid aerogel, and then graphite paper is attached to the surface of the solid aerogel.

[0122] This embodiment also provides a method for preparing the carbon fiber doped graphene oxide foam material, wherein the components are prepared according to the specified proportions, and the preparation method includes the following steps:

[0123] Step 1: Prepare an aqueous solution of graphene oxide by mixing graphene oxide with deionized water. Add carbon fiber and polyvinyl butyral resin to the aqueous solution of graphene oxide and stir and mix at 500 r / min for 20 min to obtain a viscous mixed solution.

[0124] Step 2: Add hydrazine hydrate dropwise to the first mixed solution at a rate of 0.5 drops / s, and perform a hydrothermal reaction at 200°C for 24 hours with a stirring speed of 500 r / min to obtain the second mixed solution; cool the second mixed solution to room temperature and freeze-dry it at -50°C for 24 hours with a vacuum degree of 0.1 MPa to obtain a solid aerogel.

[0125] Step 3: Stir the phenolic resin and graphene at 500 r / min for 20 min to prepare an adhesive;

[0126] Step 4: Coat the surface of the solid aerogel with the adhesive and attach graphite paper to the surface of the solid aerogel after coating with the adhesive to obtain a composite aerogel; dry the composite aerogel at 80°C for 30 min, then carbonize it at 450°C for 1 h under nitrogen protection at a flow rate of 10 mL / min, and then graphitize it at 1500°C under nitrogen protection at a flow rate of 10 mL / min for 3 h to obtain the carbon fiber doped graphene oxide foam material.

[0127] In this embodiment, based on the total mass of each component in the solid aerogel, the components and contents of the solid aerogel are as follows: graphene oxide: 3 wt%, deionized water: 85 wt%, carbon fiber: 4 wt%, polyvinyl butyral resin: 6 wt%, hydrazine hydrate: 2 wt%; the mass ratio of phenolic resin to graphene in the binder is 10:1; the mass ratio of the binder to the solid aerogel is 1:10.

[0128] In this embodiment, the graphene oxide has a particle size of 40 μm and an atomic layer structure of 2-3 atomic layers.

[0129] In this embodiment, the carbon fiber has a diameter of 20 μm and a length of 5 mm.

[0130] In this embodiment, the graphene has a particle size of 40 μm and an oxygen content of 36%.

[0131] In this embodiment, the graphite paper has a thickness of 100 μm and a purity of 99.9%.

[0132] Comparative Example 1

[0133] This comparative example provides a foam material made by carbonizing and then graphitizing a composite aerogel. The foam material has a thermal conductivity of 0.1 W / m·K and a density of 0.18 g / cm³. 3 The compressive strength is 150 kPa, the in-plane shear strength is 10 kPa, and the specific strength is 0.8 MPa·cm. 3 / g, with a porosity of 80%; the composite aerogel is prepared by hydrothermal and freeze-drying a mixture of deionized water, carbon fiber, polyvinyl butyral resin and hydrazine hydrate to obtain a solid aerogel, and then graphite paper is attached to the surface of the solid aerogel.

[0134] This comparative example also provides a method for preparing a foam material, wherein the components are prepared according to their respective content ratios, and the preparation method includes the following steps:

[0135] Step 1: Mix deionized water, carbon fiber and polyvinyl butyral resin at 500 r / min for 20 min to obtain a viscous mixed solution.

[0136] Step 2: Add hydrazine hydrate dropwise to the first mixed solution at a rate of 0.5 drops / s, and perform a hydrothermal reaction at 200°C for 24 hours with a stirring speed of 500 r / min to obtain the second mixed solution; cool the second mixed solution to room temperature and freeze-dry it at -50°C for 24 hours with a vacuum degree of 0.1 MPa to obtain a solid aerogel.

[0137] Step 3: Stir the phenolic resin and graphene at 500 r / min for 20 min to prepare an adhesive;

[0138] Step 4: Apply the adhesive evenly to the surface of the solid aerogel, and attach graphite paper to the surface of the solid aerogel after applying the adhesive to obtain a composite aerogel; dry the composite aerogel at 80°C for 30 min, then carbonize it at 450°C for 1 h under nitrogen protection at a flow rate of 10 mL / min, and then graphitize it at 1500°C under nitrogen protection at a flow rate of 10 mL / min for 3 h to obtain the foam material.

[0139] In this comparative example, based on the total mass of the components in the solid aerogel, the components and contents of the solid aerogel are as follows: deionized water: 90 wt%, carbon fiber: 3 wt%, polyvinyl butyral resin: 5 wt%, hydrazine hydrate: 2 wt%; the mass ratio of phenolic resin to graphene in the binder is 10:1; the mass ratio of the binder to the solid aerogel is 1:10.

[0140] The carbon fiber described in this comparative example has a diameter of 20 μm and a length of 5 mm.

[0141] The graphene described in this comparative example has a particle size of 40 μm and an oxygen content of 36%.

[0142] The graphite paper described in this comparative example has a thickness of 100 μm and a purity of 99.9%.

[0143] In this comparative example, no graphene oxide was added to the composite aerogel. Therefore, the resulting foam material has poor structural strength, high density, and is easy to disperse, making it difficult to form a stable porous structure and resulting in poor adhesion to the graphite paper.

[0144] Comparative Example 2

[0145] This comparative example provides a foam material, which is made by carbonizing a composite material and then graphitizing it. The foam material has a thermal conductivity of 0.45 W / m·K and a density of 0.1 g / cm³. 3 The compressive strength is 100 kPa, the in-plane shear strength is 30 kPa, and the specific strength is 1 MPa·cm. 3 / g, with a porosity of 96%; the composite material is made by mixing graphene oxide, deionized water, carbon fiber, polyvinyl butyral resin and hydrazine hydrate to obtain a mixed material, and then covering the surface of the mixed material with graphite paper.

[0146] This comparative example also provides a method for preparing a foam material, wherein the components are prepared according to their respective content ratios, and the preparation method includes the following steps:

[0147] Step 1: Prepare an aqueous solution of graphene oxide by mixing graphene oxide with deionized water. Add carbon fiber and polyvinyl butyral resin to the aqueous solution of graphene oxide and stir and mix at 500 r / min for 20 min to obtain a viscous mixed solution.

[0148] Step 2: Add hydrazine hydrate dropwise to the first mixed solution at a rate of 0.5 drops / s, and stir at a speed of 500 r / min to obtain the second mixed solution; dry the second mixed solution at 200℃ for 24 h and then cool it to room temperature to obtain the mixed material;

[0149] Step 3: Stir the phenolic resin and graphene at 500 r / min for 20 min to prepare an adhesive;

[0150] Step 4: Apply the adhesive evenly to the surface of the mixed material, and attach graphite paper to the surface of the mixed material after applying the adhesive to obtain the composite material; dry the composite material at 80°C for 30 min, then carbonize it at 450°C for 1 h under nitrogen protection at a flow rate of 10 mL / min, and then graphitize it at 1500°C under nitrogen protection at a flow rate of 10 mL / min for 3 h to obtain the foam material.

[0151] In this comparative example, based on the total mass of each component in the composite material, the components and contents of the mixed material are as follows: graphene oxide: 5 wt%, deionized water: 85 wt%, carbon fiber: 3 wt%, polyvinyl butyral resin: 5 wt%, hydrazine hydrate: 2 wt%; the mass ratio of phenolic resin to graphene in the binder is 10:1; the mass ratio of the binder to the mixed material is 1:10.

[0152] The graphene oxide described in this comparative example has a particle size of 40 μm and an atomic layer structure of 2-3 atomic layers.

[0153] The carbon fiber described in this comparative example has a diameter of 20 μm and a length of 5 mm.

[0154] The graphene described in this comparative example has a particle size of 40 μm and an oxygen content of 36%.

[0155] The graphite paper described in this comparative example has a thickness of 100 μm and a purity of 99.9%.

[0156] In the preparation method of the foam material described in this comparative example, no hydrothermal reaction and freeze-drying treatment were performed. Therefore, the material will agglomerate during the preparation process, and the resulting foam material has a high thermal conductivity.

[0157] Table 1. Components and contents of the foam materials described in Examples 1-5 and Comparative Examples 1-2

[0158] Table 2 Performance tests of the foam materials described in Examples 1-5 and Comparative Examples 1-2

[0159] As shown in Table 2, the thermal conductivity and rate of change of the foam materials in Examples 1-5 are low. The foam materials are stable, have a slow thermal conductivity, a large shear rate, and a low density, making them more convenient to use.

[0160] As can be seen from the above, the carbon fiber doped graphene oxide foam material described in this patent has a wide range of applications, low cost, and extremely high market prospects.

[0161] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any modifications or equivalent changes made based on the technical essence of the present invention shall still fall within the scope of protection claimed by the present invention.

Claims

1. A carbon fiber doped graphene oxide foam material, characterized by, The foam material is made by carbonizing and graphitizing composite aerogel, the foam material is resistant to high temperature of 2000-3000 DEG C, the foam material has thermal conductivity of 0.16-0.27 W / m K, density of 0.1-0.15 g / cm 3 , compressive strength of 150-200 kPa, in-plane shear strength of 40-50 kPa, specific strength of 1.3-2 MPa cm / g, and porosity of 85-95%; the composite aerogel is prepared by mixing graphene oxide, deionized water, carbon fiber, polyvinyl butyral ester resin and hydrazine hydrate for hydrothermal reaction, and freeze-drying to obtain solid aerogel, and then pasting graphite paper on the surface of the solid aerogel. 3 The foam material is made by carbonizing and graphitizing composite aerogel, the foam material is resistant to high temperature of 2000-3000 DEG C, the foam material has thermal conductivity of 0.16-0.27 W / m K, density of 0.1-0.15 g / cm 3 , compressive strength of 150-200 kPa, in-plane shear strength of 40-50 kPa, specific strength of 1.3-2 MPa cm / g, and porosity of 85-95%; the composite aerogel is prepared by mixing graphene oxide, deionized water, carbon fiber, polyvinyl butyral ester resin and hydrazine hydrate for hydrothermal reaction, and freeze-drying to obtain solid aerogel, and then pasting graphite paper on the surface of the solid aerogel. 3 The foam material is made by carbonizing and graphitizing composite aerogel, the foam material is resistant to high temperature of 2000-3000 DEG C, the foam material has thermal conductivity of 0.16-0.27 W / m K 2. The carbon fiber doped graphene oxide foam material of claim 1, wherein, The components and contents of the solid aerogel are prepared based on the total mass of each component in the solid aerogel, and are as follows: Graphene oxide: 2-5wt%; Deionized water: 80-90wt%; Carbon fiber: 3-5wt%; Polyvinyl butyral ester resin: 4-6wt%; Hydrazine hydrate: 1-2wt%.

3. A method of producing the carbon fiber-doped graphene oxide foam material according to claim 1 or 2, characterized by, Each component is taken according to the content ratio, and the preparation method comprises the following steps: Step 1, graphene oxide and deionized water are prepared into a graphene oxide aqueous solution, carbon fiber and polyvinyl butyral ester resin are added to the graphene oxide aqueous solution, and stirring and mixing are performed to obtain a viscous mixed solution I; Step 2, hydrazine hydrate is added dropwise to the mixed solution I, and hydrothermal reaction is performed by stirring to obtain a mixed solution II; the mixed solution II is cooled to room temperature, and solid aerogel is obtained after freeze-drying; Step 3, phenolic resin and graphene are stirred and mixed to prepare a binder; Step 4, the binder is coated on the surface of the solid aerogel, and graphite paper is attached to the surface of the solid aerogel after coating the binder to obtain a composite aerogel; the composite aerogel is dried and carbonized, and then graphitized to obtain the carbon fiber doped graphene oxide foam material.

4. The production method according to claim 3, characterized by, The particle size of the graphene oxide in step 1 is 30-40μm.

5. The preparation method according to claim 3, characterized in that, The diameter of the carbon fiber in step 1 is 10-30μm, and the length is 5-6mm.

6. The preparation method according to claim 3, characterized in that, The temperature of the hydrothermal reaction in step 2 is 150-250℃, and the hydrothermal reaction time is 24-48h.

7. The preparation method according to claim 3, characterized in that, The temperature of the freeze-drying in step 2 is -50 to -10℃, the freeze-drying time is 24-48h, and the vacuum degree of freeze-drying is 0.1MPa.

8. The preparation method according to claim 3, characterized in that, The temperature of the carbonization in step 4 is 300-500℃, and the carbonization time is 1-2h.

9. The preparation method according to claim 3, characterized in that, The temperature of the graphitization in step 4 is 1500-2000℃, and the time is 1-3h.

10. A thermal insulation material comprising the carbon fiber doped graphene oxide foam material of claim 1 or 2, characterized in that, The thermal insulation material is applied in a high-temperature environment of 2000-3000℃, and the thermal insulation material is made of the carbon fiber doped graphene oxide foam material.

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