Graphene-based thermally conductive film with stable interface and preparation method thereof

Abstract

The application discloses a kind of interface stable graphene-based heat-conducting films and preparation method thereof.In the preparation of graphene film, the substrate with specific size screen structure is used, which is beneficial to the separation of high surface energy graphene oxide precursor film and substrate, and provides more stable nucleation sites and interlocking interface for subsequent in-situ growth of carbide.In-situ growth method can generate a layer of superhard carbide coating on the surface of graphene, which is dense in structure and combined by strong chemical bond.The carbide coating can form a superstable interface with graphene, effectively protecting the graphene film and greatly improving its wear resistance, impact resistance and resistance to space environmental erosion.

Description

Technical Field

[0001] This invention belongs to the field of functional materials technology, specifically relating to an interface-stable graphene-based thermal conductive film and its preparation method. Background Technology

[0002] High thermal conductivity graphene films, due to their extremely high in-plane thermal conductivity (typically exceeding 1500 W / mK), excellent flexibility, and lightweight properties, have become a key material in advanced thermal management systems. In the aerospace field, as electronic devices evolve towards higher power, miniaturization, and integration, the demand for efficient and lightweight thermal control technologies is increasingly urgent. Heat-generating components in spacecraft, such as onboard computers, high-power microwave devices, and lasers, require highly reliable heat dissipation components to rapidly dissipate and radiate the generated heat into space, ensuring the normal operation of these devices in extreme environments. Graphene films, with their ultra-high thermal conductivity and areal density, demonstrate enormous application potential in this field.

[0003] However, directly applying graphene films to aerospace thermal control systems still faces many severe technical bottlenecks. First, graphene films are composed of sp² hybrid carbon, and their surface chemical inertness results in extremely poor wettability with metal solders, making it difficult to achieve reliable mechanical connections and efficient thermal interface connections. Second, and more critically, graphene films themselves have low mechanical strength, and their surface is soft and not wear-resistant. During spacecraft launch, they will be subjected to severe vibrations, impacts, and acceleration stresses; during on-orbit operation, they may face complex environments such as impacts from micrometeoroids and space debris, and atomic oxygen erosion. Any wear, scratches, or damage to the surface will significantly reduce its mechanical integrity and may drastically degrade its in-plane heat diffusion capacity, leading to localized overheating and ultimately single-point failure, posing a serious risk to the entire space mission. Summary of the Invention

[0004] In view of the problems in the prior art, such as the easy wear of the surface of graphene high thermal conductivity film and the instability of the interface between the protective coating and the graphene film substrate, the present invention provides an interface-stable graphene-based thermal conductive film and its preparation method.

[0005] This invention utilizes a substrate with a specific sized network structure during the preparation of graphene films. This facilitates the separation of the high surface energy graphene oxide precursor film from the substrate and provides more stable nucleation sites and interlocking interfaces for subsequent in-situ growth of carbides. The in-situ growth method can generate a dense, chemically bonded, ultra-hard carbide coating on the graphene surface. This carbide coating forms an ultra-stable interface with the graphene, effectively protecting the graphene film and significantly enhancing its resistance to wear, impact, and space environment corrosion.

[0006] The technical solution of this invention is to provide a method for preparing an interface-stable graphene-based thermally conductive film, comprising the following steps: (1) Graphene oxide slurry is uniformly coated onto an 80-200 mesh textured substrate, and then an 80-200 mesh textured cloth is covered on the surface of the graphene slurry. A pressure of 10-50 Pa is applied, followed by a first drying to obtain a pre-dried graphene oxide film. Graphene oxide films have high surface energy and are easy to adhere to the substrate. In actual production, they are often difficult to separate from the substrate. The textured substrate helps to reduce the contact area with the graphene oxide film. During the coating process of graphene oxide slurry, an air layer exists between the mesh and the graphene oxide film, which further weakens the interaction force between the graphene oxide film and the substrate, which is beneficial for the subsequent peeling of the graphene oxide film from the substrate. If the mesh size is too small, the flowing graphene oxide slurry will almost completely wet the substrate surface, making it difficult to peel off. If the mesh size is too large, the surface roughness of the substrate will be too low, which will also cause the slurry to adhere. At the same time, it is not conducive to the construction of the subsequent secondary textured structure. After the first drying, the solvent content of the wet film is between 50wt.% and 80wt.%. If the solvent content is too low, the interaction between graphene oxide sheets will be enhanced, which is not conducive to the construction of the secondary mesh structure. If the solvent content is too high, the wet film structure will be unstable and will decompose during the first separation of the substrate and the mesh fabric.

[0007] (2) Cover both sides of the pre-dried graphene oxide film with 300-800 mesh textured cloth, apply a pressure of 100-500 Pa, and then dry to obtain a completely dried graphene oxide film. The secondary textured structure is 300-800 mesh. If the mesh number is too small, it cannot form a microstructure that is conducive to subsequent reactions. If the mesh number is too large, the surface structure of the graphene oxide film may be damaged when pressure is applied. The drying temperature should not exceed 60℃. If the temperature is too high, the solvent will evaporate too quickly, reducing the uniformity of the graphene oxide film structure.

[0008] (3) The completely dried graphene oxide film was chemically reduced, carbonized at high temperature and graphitized to obtain a high thermal conductivity graphene film with a multi-level micro-nano structure on the surface. (4) A graphene film is embedded with completely dried transition metal powder and salt at a mass ratio of 1:(1-10), heated to 800-1200℃ in an argon atmosphere, held for more than 30 minutes, and then cooled to room temperature to obtain an interface-stable graphene-based thermally conductive film; the salt is one or more of lithium fluoride, lithium chloride, sodium fluoride, sodium chloride, potassium fluoride, and potassium chloride. The textured substrate constructs a large number of protrusions on the surface of the graphene oxide film. After chemical reduction, carbonization, and graphitization, the protrusions remain on the graphene film surface. These structures provide capillary forces during the subsequent carbide coating growth reaction, ensuring sufficient contact between the high-temperature molten metal and the graphene film substrate, thus ensuring the integrity of the carbide coating on the graphene film surface. During the reaction, these protrusions provide a large number of nucleation and anchoring sites. The large number of nucleation sites facilitates rapid nucleation in the early stages of carbide growth, effectively increasing the reaction rate. In high-temperature reaction environments, the carbide coating and the graphene film substrate have different coefficients of thermal expansion, and drastic temperature changes can cause significant thermal stress between them. The uneven surface of the graphene film can form a stable mechanically interlocked interface structure with the carbide coating to accommodate thermal stress. Furthermore, during use, these interlocking structures can firmly lock the carbide coating onto the graphene film surface, effectively improving the interfacial stability between the coating and the graphene film substrate.

[0009] Furthermore, the solvent content of the initially dried graphene oxide film is between 50 wt.% and 80 wt.%.

[0010] Furthermore, the interface-stable graphene-based thermally conductive film was boiled in deionized water at least three times to remove reaction residues, and then the sample was dried in an environment not exceeding 50-150°C.

[0011] Furthermore, the solid content of the graphene oxide slurry is 5-20 mg / ml; the diameter of the graphene oxide sheets is not less than 10 micrometers; and the solvent of the graphene oxide slurry is one of water, ethanol, DMF, and DMAc.

[0012] Furthermore, the particle size of the transition metal powder and the salt is no greater than 200 mesh.

[0013] Furthermore, the transition metal is one of titanium, chromium, zirconium, hafnium, rubidium, and thallium.

[0014] Furthermore, the chemical reduction is a fumigation reduction in a reducing gas, which is a mixture of 0.25-1 volume parts of hydroiodic acid and 0-0.75 volume parts of glacial acetic acid. The reduction is carried out at 90-120°C for 12-24 hours, and a pressure of 50-100 MPa is applied to the graphene oxide film during the reduction process. The high-temperature carbonization temperature is 1000-1600°C, and the carbonization atmosphere is nitrogen or argon. The graphitization temperature is 2500-3000°C, and the graphitization atmosphere is argon. A pressure of not less than 200 MPa needs to be applied to the graphene oxide film during the carbonization and graphitization processes.

[0015] Furthermore, the heating rate is no higher than 10°C / min; the cooling rate is no higher than 20°C / min.

[0016] The present invention also provides an interface-stable graphene-based thermally conductive film prepared by the above method, which is composed of a graphene film and a metal carbide on its surface. The thickness of the metal carbide is greater than 100 nm.

[0017] The beneficial effects of this invention are as follows: by constructing a multi-level network structure on the surface of a graphene film and increasing the reaction rate during the growth of transition metal carbides on the graphene surface via the molten salt method, a high thermal conductivity graphene-based composite film with a stable interface structure is prepared. While retaining the high thermal conductivity of the graphene film, the transition metal carbide coating provides protection for the graphene film in extreme environments. Attached Figure Description

[0018] Figure 1 Photographs of the composite membrane samples obtained in Example 1 and Comparative Example 1; Figure 2 The image shows an electron microscope image of the composite film interface obtained in Example 4. Figure 3 The images show cross-sectional views of the wear tracks on the composite films obtained in Example 4 and Comparative Example 2 after a spherical friction pair test. Figure 4 Photographs of the composite films obtained in Example 5 and Comparative Example 3; Figure 5 These are photographs of the composite film planar load friction pair before and after friction in Example 5 and Comparative Example 3. Detailed Implementation

[0019] The following examples are provided to further illustrate the present invention and are intended to explain the invention, not to limit its scope. Unless otherwise specified, all figures are expressed in parts by weight and weight percentages.

[0020] Unless otherwise specified, the raw materials used in this invention are all conventional commercially available products; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0021] The embodiments of the present invention will be further described below with reference to several examples.

[0022] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0023] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0024] Example 1 (1) Preparation and coating of graphene oxide slurry: Graphene oxide slurry (solid content 10 mg / ml, solvent: water, graphene oxide sheet diameter 15 μm) was uniformly coated on a primary textured substrate (mesh size 100 mesh). A layer of primary textured fabric (mesh size 100 mesh) was covered on the slurry surface and a pressure of 20 Pa was applied. The film was dried once at 50 °C, and the solvent content of the wet film after drying was 60 wt.%. The textured fabric was then peeled off, and a secondary textured fabric (mesh size 500 mesh) was applied to both sides of the graphene oxide film and a pressure of 300 Pa was applied. After complete drying at 50 °C, the textured fabric was peeled off.

[0025] (2) Reduction, carbonization, and graphitization: The dried graphene oxide film was chemically reduced by fumigating it at 100°C for 18 hours in a reducing gas (hydroiodic acid and glacial acetic acid in a volume ratio of 1:1) under a pressure of 80 MPa. High-temperature carbonization was then performed at 1200°C in a nitrogen atmosphere under a pressure of 200 MPa. Finally, graphitization was carried out at 2800°C for 60 minutes in an argon atmosphere under a pressure of 200 MPa, resulting in a high thermal conductivity graphene film with a multi-level micro / nano structure on its surface.

[0026] (3) Molten salt method for growing carbide coatings: Chromium powder (particle size of 200 mesh) and sodium chloride are ground and mixed evenly at a mass ratio of 1:5 and dried in an oven at 120℃ for 2 hours. The graphene film is embedded with the dried mixed powder, heated to 1000℃ in an argon atmosphere at a heating rate of 5℃ / min, held for 60 minutes, and then cooled to room temperature at a cooling rate of 10℃ / min.

[0027] (4) Post-treatment: The sample was boiled three times in deionized water to remove reaction residues, and then dried at 100°C to obtain a highly interface-stable, environmentally resistant graphene-based high thermal conductivity film. Figure 1 (See the image above). The carbide coating thickness is approximately 10 μm. The in-plane thermal conductivity of the composite film is 800 W / mK. No significant changes in structure and properties were observed after 30 min of plasma treatment.

[0028] Example 2 (1) Preparation and coating of graphene oxide slurry: Graphene oxide slurry (solid content 15 mg / ml, solvent ethanol, graphene oxide sheet diameter 20 μm) was uniformly coated on a primary textured substrate (mesh count 150 mesh). A layer of primary textured fabric (mesh count 150 mesh) was covered on the slurry surface and a pressure of 30 Pa was applied. The film was dried once at 40°C, and the solvent content of the wet film after drying was 70 wt.%. The textured fabric was then peeled off, and a secondary textured fabric (mesh count 600 mesh) was applied to both sides of the graphene oxide film and a pressure of 400 Pa was applied. After complete drying at 40°C, the textured fabric was peeled off.

[0029] (2) Reduction, carbonization, and graphitization: The dried graphene oxide film was chemically reduced by fumigating it at 110°C for 20 hours in a reducing gas (hydroiodic acid and glacial acetic acid in a volume ratio of 0.5:1) under a pressure of 60 MPa. High-temperature carbonization was then performed at 1400°C in an argon atmosphere under a pressure of 250 MPa. Finally, graphitization was carried out at 2600°C in an argon atmosphere for 70 minutes under a pressure of 250 MPa, resulting in a high thermal conductivity graphene film with a multi-level micro / nano structure on its surface.

[0030] (3) Molten salt method for growing carbide coatings: Titanium powder (particle size 180 mesh) and lithium fluoride were ground and mixed evenly at a mass ratio of 1:3 and dried in an oven at 130℃ for 1.5 hours. The dried mixed powder was used to embed the graphene film, and the mixture was heated to 900℃ in an argon atmosphere at a heating rate of 8℃ / min, held at that temperature for 45 minutes, and then cooled to room temperature at a cooling rate of 15℃ / min.

[0031] (4) Post-treatment: The sample was boiled four times in deionized water to remove reaction residues, and then dried at 80°C to obtain a highly interface-stable, environmentally resistant graphene-based high thermal conductivity film. The carbide coating thickness was approximately 800 nm. The in-plane thermal conductivity of the composite film was 900 W / mK. After rubbing the surface of the composite film with 500-grit sandpaper attached to a 300 cN load, the coating wear area was 5%, and the thermal conductivity did not change significantly.

[0032] Example 3 (1) Preparation and coating of graphene oxide slurry: Graphene oxide slurry (solid content 5 mg / ml, solvent DMF, graphene oxide sheet diameter 12 μm) was uniformly coated on a primary textured substrate (mesh size 80 mesh). A layer of primary textured fabric (mesh size 80 mesh) was covered on the slurry surface and a pressure of 10 Pa was applied. The film was dried once at 55°C, and the solvent content of the wet film after drying was 50 wt.%. The textured fabric was then peeled off, and a secondary textured fabric (mesh size 300 mesh) was applied to both sides of the graphene oxide film and a pressure of 100 Pa was applied. After complete drying at 55°C, the textured fabric was peeled off.

[0033] (2) Reduction, carbonization, and graphitization: The dried graphene oxide film was chemically reduced by fumigating it at 90°C for 24 hours in a reducing gas atmosphere (hydroiodic acid and glacial acetic acid in a volume ratio of 0.25:1) under a pressure of 50 MPa. High-temperature carbonization was then performed at 1000°C in a nitrogen atmosphere under a pressure of 200 MPa. Finally, graphitization was carried out at 2500°C for 90 minutes in an argon atmosphere under a pressure of 200 MPa, resulting in a high thermal conductivity graphene film with a multi-level micro / nano structure on its surface.

[0034] (3) Molten salt method for growing carbide coatings: Hafnium powder (particle size of 200 mesh) and potassium chloride were ground and mixed evenly at a mass ratio of 1:10 and dried in an oven at 110℃ for 3 hours. The graphene film was embedded with the dried mixed powder and heated to 800℃ in an argon atmosphere at a heating rate of 3℃ / min, held for 90 minutes, and then cooled to room temperature at a cooling rate of 5℃ / min.

[0035] (4) Post-treatment: The sample was boiled three times in deionized water to remove reaction residues, and then dried at 50°C to obtain a highly interface-stable, environmentally resistant graphene-based high thermal conductivity film. The carbide coating thickness was approximately 5 μm. The in-surface thermal conductivity of the composite film was 950 W / mK. After rubbing the surface of the composite film with 500-grit sandpaper attached to a 300 cN load, the wear area of ​​the coating was approximately 8%, and the thermal conductivity did not change significantly. After ablation with a butane flame at 1300°C for 120 s, there were no significant changes in the surface structure and thermal conductivity.

[0036] Example 4 (1) Preparation and coating of graphene oxide slurry: Graphene oxide slurry (solid content 20 mg / ml, solvent: water, graphene oxide sheet diameter 25 μm) was uniformly coated on a primary textured substrate (mesh size 200 mesh). A layer of primary textured fabric (mesh size 200 mesh) was covered on the slurry surface and a pressure of 50 Pa was applied. The film was dried once at 60°C, and the solvent content of the wet film after drying was 80 wt.%. The textured fabric was then peeled off, and a secondary textured fabric (mesh size 800 mesh) was applied to both sides of the graphene oxide film and a pressure of 500 Pa was applied. After complete drying at 60°C, the textured fabric was peeled off.

[0037] (2) Reduction, carbonization, and graphitization: The dried graphene oxide film was chemically reduced by fumigating it at 120°C for 12 hours in a reducing gas (hydroiodic acid and glacial acetic acid in a volume ratio of 1:0.5) under a pressure of 100 MPa. High-temperature carbonization was then performed at 1600°C in an argon atmosphere under a pressure of 300 MPa. Finally, graphitization was performed at 3000°C in an argon atmosphere for 60 minutes under a pressure of 300 MPa, resulting in a high thermal conductivity graphene film with a multi-level micro / nano structure on its surface.

[0038] (3) Molten salt method for growing carbide coatings: Rubidium powder (particle size of 150 mesh) and sodium fluoride were ground and mixed evenly at a mass ratio of 1:2 and dried in an oven at 150°C for 1 hour. The graphene film was embedded with the dried mixed powder and heated to 950°C at a heating rate of 10°C / min in an argon atmosphere, held at that temperature for 4 hours, and then cooled to room temperature at a cooling rate of 20°C / min.

[0039] (3) Post-treatment: The sample was boiled five times in deionized water to remove reaction residues, and then dried at 150°C to obtain a highly interface-stable, environmentally resistant graphene-based high thermal conductivity film. Figure 2 As shown, the carbide coating thickness is approximately 25 μm.

[0040] Example 5 (1) Preparation and coating of graphene oxide slurry: Graphene oxide slurry (solid content 8 mg / ml, solvent DMAc, graphene oxide sheet diameter 10 μm) was uniformly coated on a primary textured substrate (mesh size 120 mesh). A layer of primary textured fabric (mesh size 120 mesh) was covered on the slurry surface and a pressure of 40 Pa was applied. The film was dried once at 45°C, and the solvent content of the wet film after drying was 65 wt.%. The textured fabric was then peeled off, and a secondary textured fabric (mesh size 400 mesh) was applied to both sides of the graphene oxide film and a pressure of 200 Pa was applied. After complete drying at 45°C, the textured fabric was peeled off.

[0041] (2) Reduction, carbonization, and graphitization: The dried graphene oxide film was chemically reduced by fumigating it at 95°C for 16 hours in a reducing gas atmosphere (hydroiodic acid and glacial acetic acid in a volume ratio of 0.75:1) under a pressure of 70 MPa. High-temperature carbonization was then performed at 1300°C in a nitrogen atmosphere under a pressure of 220 MPa. Finally, graphitization was carried out at 2700°C for 80 minutes in an argon atmosphere under a pressure of 220 MPa, resulting in a high thermal conductivity graphene film with a multi-level micro / nano structure on its surface.

[0042] (3) Molten salt method for growing carbide coatings: Thallium powder (particle size of 200 mesh) and lithium chloride were ground and mixed evenly at a mass ratio of 1:4 and dried in an oven at 140℃ for 2 hours. The dried mixed powder was used to embed the graphene film, and the film was heated to 1100℃ in an argon atmosphere at a heating rate of 6℃ / min, held for 50 minutes, and then cooled to room temperature at a cooling rate of 12℃ / min.

[0043] (4) Post-treatment: The sample was boiled three times in deionized water to remove reaction residues, and then dried at 120°C to obtain an environmentally resistant graphene-based high thermal conductivity film with high interfacial stability. The carbide coating thickness was approximately 8 μm. This composite film balances thermal conductivity and mechanical strength, with a thermal conductivity of approximately 1100 W / mK, making it suitable for long-term on-orbit operation.

[0044] Comparative Example 1 (1) Preparation and coating of graphene oxide slurry: The graphene oxide slurry (solid content of 10 mg / ml, solvent of water, graphene oxide sheet diameter of 15 μm) was uniformly coated on the PET substrate and completely dried in an environment of 50°C before peeling the graphene oxide film off the substrate.

[0045] (2) Reduction, carbonization, and graphitization: The dried graphene oxide film was chemically reduced by fumigating it at 100°C for 18 hours in a reducing gas (hydroiodic acid and glacial acetic acid in a volume ratio of 1:1) under a pressure of 80 MPa. High-temperature carbonization was then performed at 1200°C in a nitrogen atmosphere under a pressure of 200 MPa. Finally, graphitization was carried out at 2800°C for 60 minutes in an argon atmosphere under a pressure of 200 MPa, resulting in a high thermal conductivity graphene film with a multi-level micro / nano structure on its surface.

[0046] (3) Molten salt method for growing carbide coatings: Chromium powder (particle size of 200 mesh) and sodium chloride are ground and mixed evenly at a mass ratio of 1:5 and dried in an oven at 120℃ for 2 hours. The graphene film is embedded with the dried mixed powder, heated to 1000℃ in an argon atmosphere at a heating rate of 5℃ / min, held for 60 minutes, and then cooled to room temperature at a cooling rate of 10℃ / min.

[0047] (4) Post-treatment: The sample was boiled three times in deionized water to remove reaction residues, and then dried at 100°C. Compared with Example 1, the chromium carbide coating on the surface of the composite film obtained under the same reaction conditions was almost completely peeled off. Figure 1 (See image below).

[0048] Comparative Example 2 The sample from Example 4 was subjected to a friction experiment with a graphene film. The friction pair consisted of silicon nitride spheres with a radius of 0.5 mm and a weight of 1 N, rubbed reciprocally at a frequency of 1 Hz for 10 minutes. The calculated wear rate of the composite film obtained in Example 4 was 2.8 × 10⁻⁶. -12 m 3 / Nm ( Figure 3 (Above), the wear rate of the graphene film is 4.6 × 10⁻⁶. -12 m 3 / Nm ( Figure 3 (See below) This demonstrates that the carbide coating effectively protects the graphene film.

[0049] Comparative Example 3 (1) Preparation and coating of graphene oxide slurry: The graphene oxide slurry (solid content of 8 mg / ml, solvent of DMAc, graphene oxide sheet diameter of 10 μm) was uniformly coated on the PET substrate and completely dried in an environment of 45℃ before the graphene oxide film was peeled off from the substrate.

[0050] (2) Reduction, carbonization, and graphitization: The dried graphene oxide film was chemically reduced by fumigating it at 95°C for 16 hours in a reducing gas atmosphere (hydroiodic acid and glacial acetic acid in a volume ratio of 0.75:1) under a pressure of 70 MPa. High-temperature carbonization was then performed at 1300°C in a nitrogen atmosphere under a pressure of 220 MPa. Finally, graphitization was carried out at 2700°C for 80 minutes in an argon atmosphere under a pressure of 220 MPa, resulting in a high thermal conductivity graphene film with a multi-level micro / nano structure on its surface.

[0051] (3) Molten salt method for growing carbide coatings: Titanium powder (particle size of 200 mesh) and lithium chloride were ground and mixed evenly at a mass ratio of 1:4 and dried in an oven at 140℃ for 2 hours. The graphene film was embedded with the dried mixed powder and heated to 1100℃ in an argon atmosphere at a heating rate of 6℃ / min, held for 50 minutes, and then cooled to room temperature at a cooling rate of 12℃ / min.

[0052] (4) Post-treatment: The sample was boiled three times in deionized water to remove reaction residues, and then dried at 120°C. Coating peeling occurred on the surface of the resulting composite membrane. Figure 4 The composite film surface coating obtained in Example 5 is uniformly dense and has a stable interface structure. After being rubbed with 300cN load using 600Cw sandpaper, the wear area ratio of the composite film surface coating obtained from the textured graphene film is less than 10%. Figure 5 a) The surface wear rate of the composite film obtained from the graphene film without a textured structure is about 30%. Figure 5 (b) This demonstrates that the textured structure is beneficial for improving coating stability.

[0053] The above embodiments describe in detail the structure, features, and effects of the present invention. The above description is only a preferred embodiment of the present invention. Any changes made in accordance with the concept of the present invention, or equivalent embodiments modified to have equivalent changes, shall still fall within the scope of protection of the present invention if they do not exceed the scope covered by the specification.

Claims

1. A method for preparing an interface-stable graphene-based thermally conductive film, characterized in that, It includes the following steps: (1) The graphene oxide slurry is uniformly coated on the substrate with an 80-200 mesh textured structure, and then an 80-200 mesh textured cloth is covered on the surface of the graphene slurry. A pressure of 10-50 Pa is applied, and then the first drying is carried out to obtain a pre-dried graphene oxide film. (2) Cover both sides of the pre-dried graphene oxide film with 300-800 mesh fabric, apply 100-500 Pa pressure, and then dry to obtain a completely dried graphene oxide film. (3) The completely dried graphene oxide film was chemically reduced, carbonized at high temperature and graphitized to obtain a high thermal conductivity graphene film with a multi-level micro-nano structure on the surface. (4) The graphene film is embedded with completely dried transition metal powder and salt in a mass ratio of 1:(1-10), heated to 800-1200℃ in an argon atmosphere, held for more than 30 minutes, and then cooled to room temperature to obtain an interface-stable graphene-based thermal conductive film. The graphene-based thermal conductive film is composed of a graphene film and metal carbides on its surface. The salt is one or more of lithium fluoride, lithium chloride, sodium fluoride, sodium chloride, potassium fluoride, and potassium chloride.

2. The method according to claim 1, characterized in that, The solvent content of the initially dried graphene oxide film is between 50 wt.% and 80 wt.%.

3. The method according to claim 1, characterized in that, The interface-stable graphene-based thermally conductive film was boiled in deionized water at least three times to remove reaction residues.

4. The method according to claim 1, characterized in that, The solid content of the graphene oxide slurry is 5-20 mg / ml; the diameter of the graphene oxide sheets is not less than 10 micrometers; and the solvent of the graphene oxide slurry is one of water, ethanol, DMF, and DMAc.

5. The method according to claim 1, characterized in that, The particle size of the transition metal powder and salt is no greater than 200 mesh.

6. The method according to claim 1, characterized in that, The transition metal is one of titanium, chromium, zirconium, hafnium, rubidium, and thallium.

7. The method according to claim 1, characterized in that, The chemical reduction is a fumigation reduction in a reducing gas, which is a mixture of 0.25-1 volume parts of hydroiodic acid and 0-0.75 volume parts of glacial acetic acid. The reduction is carried out at 90-120℃ for 12-24 hours, and a pressure of 50-100 MPa is applied to the graphene oxide film during the reduction process. The high-temperature carbonization temperature is 1000-1600℃, and the carbonization atmosphere is nitrogen or argon. The graphitization temperature is 2500-3000℃, and the graphitization atmosphere is argon. A pressure of not less than 200 MPa needs to be applied to the graphene oxide film during the carbonization and graphitization processes.

8. The method according to claim 1, characterized in that, The heating rate shall not exceed 10℃ / min; the cooling rate shall not exceed 20℃ / min.

9. A graphene-based thermally conductive film with an interface stable prepared by the method described in claim 1, characterized in that, It consists of a graphene film and metal carbides on its surface.

10. The graphene-based thermally conductive film according to claim 9, characterized in that, The thickness of the metal carbide is greater than 100 nm.

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