Preparation method of silicon carbide induced graphene-based bidirectional heat-conducting high-temperature-resistant film

Abstract

The invention discloses a preparation method of a silicon carbide induced graphene-based bidirectional heat-conducting high-temperature-resistant film, which comprises the following steps: S1, pretreating graphene, silicon carbide, 4, 4 '-diaminodiphenyl ether and pyromellitic dianhydride; s2, adding 4, 4 '-diaminodiphenyl ether into the N, N-dimethylacetamide solution, and continuously stirring until the 4, 4'-diaminodiphenyl ether is completely dissolved; s3, adding silicon carbide powder and graphene nanosheets, and continuously stirring for 30 minutes, so that the silicon carbide powder and the graphene nanosheets are uniformly dispersed; s4, pyromellitic dianhydride is added, and meanwhile the stirring speed is reduced; in the step, the three-necked flask is placed in an ice-water mixture, so that the reaction temperature is below 5 DEG C; and S5, removing bubbles from the viscous solution obtained in the step S4, and drying to form a film. And S6, carrying out gradient heating on the film. The thin film prepared by the invention has high conductivity, excellent thermal stability and excellent stability at high temperature.

Description

Technical Field

[0001] The invention relates to the technical field of polyimide films, and in particular to a method for preparing a silicon carbide-induced graphene-based bidirectional heat-conducting and high-temperature-resistant film. Background Art

[0002] In recent years, the miniaturization and multifunctionalization of highly integrated circuits in electronic devices has triggered great interest in the development of thermally conductive and heat-dissipating materials that can facilitate the heat dissipation of heat sources in working equipment to ensure long service life, high performance and reliability. Polymer-based thermally conductive materials have attracted widespread attention due to their low cost, light weight and good processing properties. In addition, polymers can fill the voids and gaps present in the contact interface due to their low elastic modulus and strong affinity with other materials.

[0003] However, bulk polymers have thermal conductivity that is typically less than 0.3 Wm -1 K -1 Introducing highly thermally conductive particles into insulating polymer matrices is one of the most promising approaches to improve the thermal conductivity of amorphous organic materials. Incorporation of zero-dimensional particles, such as aluminum oxide and magnesium oxide, can produce isotropic thermal conductivity, but their thermal conductivity is typically less than 5 Wm due to small contact areas and strong phonon scattering. -1 K -1 The incorporation of two-dimensional particles such as graphene and boron nitride can significantly enhance the thermal conductivity of heat dissipation materials, but due to their anisotropic heat transfer, heat can only be dissipated quickly in one direction. Oriented graphene paper or film can achieve higher than 200Wm -1 K -1 The in-plane thermal conductivity is good, but the out-of-plane thermal conductivity is poor due to interface phonon scattering.

[0004] It is crucial that the heat dissipation material has high bidirectional thermal conductivity, as this capability enables efficient in-plane and out-of-plane synergistic heat transfer, thereby achieving rapid dissipation of localized heat generated by the chip. Summary of the invention

[0005] In view of the shortcomings of the existing technology, the present invention provides a method for preparing a silicon carbide-induced graphene-based bidirectional heat-conducting high-temperature-resistant film. The film prepared by the present invention has high conductivity, excellent thermal stability, and excellent stability at high temperatures.

[0006] The present invention is achieved through the following technical solution: a method for preparing a silicon carbide-induced graphene-based bidirectional heat-conducting high-temperature-resistant film, comprising the following steps:

[0007] A method for preparing a silicon carbide-induced graphene-based bidirectional heat-conducting high-temperature-resistant film, characterized in that it comprises the following steps:

[0008] Step S1: pretreating graphene, silicon carbide, 4,4'-diaminodiphenyl ether, and pyromellitic anhydride;

[0009] Step S2: putting 4,4'-diaminodiphenyl ether into N,N-dimethylacetamide solution, and stirring continuously until 4,4'-diaminodiphenyl ether is completely dissolved;

[0010] Step S3: then adding silicon carbide powder and graphene nanosheets, and stirring continuously for 30 minutes to make the silicon carbide powder and graphene nanosheets evenly dispersed;

[0011] Step S4: adding pyromellitic anhydride while reducing the stirring speed; in this step, the three-necked flask is placed in an ice-water mixture so that the reaction temperature is below 5°C;

[0012] Step S5: remove bubbles from the viscous solution obtained in step S4 and dry it into a film.

[0013] Step S6: raising the temperature of the membrane in a gradient manner.

[0014] Graphene is a two-dimensional material. Generally, graphene thermal conductive films usually only have super high thermal conductivity within the plane, but due to the existence of interface thermal resistance, the thermal conductivity in the out-of-plane direction is very poor. The present invention achieves the bidirectional thermal conductivity function of the graphene thermal conductive film by inducing the microscopic arrangement structure of graphene through silicon carbide.

[0015] After the viscous polyimide is formed, the graphene slurry can always maintain a fully dispersed state, so that the denser silicon carbide does not settle, maintains the uniform distribution of silicon carbide in the slurry, and reduces agglomeration. Moreover, when graphene is mixed with polyimide, the aromatic ring in the polyimide molecule can be close to the graphene surface, so that the π electron clouds of the two overlap with each other, and the π-π interaction causes the π-π bond to connect. This improves the mechanical properties of the composite film, such as tensile strength. The addition of graphene can also improve the thermal stability of polyimide, making it stable at higher temperatures, and form a conductive network in the polyimide matrix through π-π interaction, thereby improving the conductivity of the composite film. The interaction of several materials improves the various properties of the composite film.

[0016] Furthermore, the step of gradient heating in step S6 is:

[0017] 100℃ / 30min-150℃ / 30min-200℃ / 30min-250℃ / 30min-300℃ / 1h-350℃ / 1h.

[0018] Furthermore, in step S3, the mass ratio of silicon carbide powder to graphene nanosheets is 70-40:25-55.

[0019] Furthermore, the mass ratio of the silicon carbide powder to the graphene nanosheets is 70:25, 60:35, 50:45, 40:50 and 40:55.

[0020] Furthermore, the pretreatment method in step S1 is to put graphene, silicon carbide, 4,4'-diaminodiphenyl ether and pyromellitic anhydride into a vacuum oven, dry them at a constant temperature of 40°C for 12 hours, and then evacuate them at room temperature for 1 hour.

[0021] Furthermore, the stirring speed after reduction in step S4 is ≤120 rad / min.

[0022] Furthermore, the step of removing bubbles and drying to form a film in step S5 is as follows: after removing bubbles in a vacuum oven at 40° C. for 2 hours, the temperature is raised to 80° C. and allowed to stand for 1 hour to evaporate the solvent from the solution to form a film.

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

[0024] By adding different contents of zero-dimensional high thermal conductivity silicon carbide particles into graphene, the graphene, which was originally two-dimensional and tended to be in a horizontal plane structure, was formed into a wavy hierarchical structure of varying degrees, and even the cross section of the film formed a structure similar to a honeycomb, changing the horizontal structure with the original plane direction, so as to regulate the orientation of the graphene sheet structure. Due to its strong affinity with other materials, polyimide can fill the gaps and gaps in the contact interface. Since the gaps in the film are filled, the occurrence of phonon scattering is reduced. In addition, silicon carbide also has thermal conductivity. Graphene and silicon carbide play a synergistic role in thermal conductivity in the film, thus changing its thermal conductivity effect. The high-temperature resistant PI film constructed has a three-dimensional network structure. The graphene nanosheets are mainly used as the main heat transfer material to guide the heat transfer along the constructed skeleton, while the SiC particles act as a subordinate heat transfer medium to enable the film to conduct heat in and between planes. Therefore, the PI film produced has bidirectional thermal conductivity, and the bidirectional heat conduction occurs simultaneously, so it is more efficient than general thermal conductivity.

[0025] The present invention adopts a green and simple self-assembly method to prepare a graphene nanosheet / polyimide film with bidirectional adjustable thermal conductivity. Specifically, the thermal conductivity of the flake graphene is very high in all directions in the plane, but because it is a two-dimensional sheet, it can only conduct heat in the plane, and the honeycomb cubic lattice of silicon carbide makes it evenly dispersed in the film, not only generating heat conduction in the horizontal plane, but also having a heat conduction effect in the vertical direction. The flake graphene can be used as a "bridge" for heat conduction, providing an additional heat conduction path between silicon carbide particles, thereby improving the thermal conductivity of the overall material and achieving good thermal conductivity in both directions. And fine-tuning the micron silicon carbide (SiC) induced phonon transfer path. It is expected that the graphene nanosheet will serve as the main heat transfer medium to guide the heat transfer along the constructed skeleton, while the SiC particles will serve as the secondary heat transfer medium. As a third-generation semiconductor material, SiC particles also have high thermal conductivity, high temperature and high pressure resistance, and high critical breakdown electric field performance compared to traditional silicon materials, so the prepared film also has interesting multifunctional properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention.

[0027] Figure 1 It is an electron microscope image;

[0028] Figure 2 is the out-of-plane thermal conductivity test result;

[0029] Figure 3 is the in-plane thermal conductivity test result;

[0030] Figure 4 For Joule heat test;

[0031] Figure 5 For EMI shielding performance test;

[0032] Figure 6 This is the flame retardant test result. DETAILED DESCRIPTION

[0033] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0034] Example 1

[0035] A method for preparing a silicon carbide-induced graphene-based bidirectional heat-conducting high-temperature-resistant film comprises the following steps:

[0036] Step S1: putting graphene, silicon carbide, 4,4'-diaminodiphenyl ether and pyromellitic anhydride into a vacuum oven, drying at a constant temperature of 40°C for 12 hours, and then evacuating at room temperature for 1 hour;

[0037] Step S2: 20.02 g of 4,4'-diaminodiphenyl ether was added to a three-necked flask containing 380 mL of N,N-dimethylacetamide solution, and the mixture was stirred continuously until the 4,4'-diaminodiphenyl ether was completely dissolved;

[0038] Step S3: then add silicon carbide powder and graphene nanosheets, and stir continuously for 30 minutes to make the silicon carbide powder and graphene nanosheets uniformly dispersed; wherein the mass ratio of silicon carbide powder to graphene nanosheets is: 70:25; (Step S4: add 22.25g of pyromellitic anhydride, and reduce the stirring speed at the same time, so that the stirring speed is ≤120rad / min; in this step, the three-necked flask is placed in an ice-water mixture so that the reaction temperature is below 5°C; wherein the total mass of silicon carbide powder and graphene nanosheets in step S3 is M1; the total mass of 4,4'-diaminodiphenyl ether in step S2 and pyromellitic anhydride in step S4 is M2; M1:M2=95:5;

[0039] Step S5: placing the viscous solution obtained in step S4 on a polytetrafluoroethylene mold, placing it in a vacuum oven at 40°C for 2 hours to remove bubbles, then heating it to 80°C and allowing it to stand for 1 hour to evaporate the solvent and form a film;

[0040] Step S6: placing the peeled composite film into a muffle furnace for gradient heating, the heating steps are: 100°C / 30min-150°C / 30min-200°C / 30min-250°C / 30min-300°C / 1h-350°C / 1h.

[0041] Example 2

[0042] A method for preparing a silicon carbide-induced graphene-based bidirectional heat-conducting high-temperature-resistant film comprises the following steps:

[0043] Step S1: putting graphene, silicon carbide, 4,4'-diaminodiphenyl ether and pyromellitic anhydride into a vacuum oven, drying at a constant temperature of 40°C for 12 hours, and then evacuating at room temperature for 1 hour;

[0044] Step S2: 20.02 g of 4,4'-diaminodiphenyl ether was added to a three-necked flask containing 380 mL of N,N-dimethylacetamide solution, and the mixture was stirred continuously until the 4,4'-diaminodiphenyl ether was completely dissolved;

[0045] Step S3: then adding silicon carbide powder and graphene nanosheets, and stirring continuously for 30 minutes to make the silicon carbide powder and graphene nanosheets evenly dispersed; wherein the mass ratio of silicon carbide powder to graphene nanosheets is: 60:35;

[0046] Step S4: adding 22.25 g of pyromellitic anhydride, while reducing the stirring speed so that the stirring speed is ≤120 rad / min; in this step, the three-necked flask is placed in an ice-water mixture so that the reaction temperature is below 5° C.; wherein the total mass of the silicon carbide powder and the graphene nanosheets in step S3 is M1; the total mass of the 4,4'-diaminodiphenyl ether in step S2 and the pyromellitic anhydride in step S4 is M2; M1:M2=95:5;

[0047] Step S5: placing the viscous solution obtained in step S4 on a polytetrafluoroethylene mold, placing it in a vacuum oven at 40°C for 2 hours to remove bubbles, then heating it to 80°C and allowing it to stand for 1 hour to evaporate the solvent and form a film;

[0048] Step S6: placing the peeled composite film into a muffle furnace for gradient heating, the heating steps are: 100°C / 30min-150°C / 30min-200°C / 30min-250°C / 30min-300°C / 1h-350°C / 1h.

[0049] Example 3

[0050] A method for preparing a silicon carbide-induced graphene-based bidirectional heat-conducting high-temperature-resistant film comprises the following steps:

[0051] Step S1: putting graphene, silicon carbide, 4,4'-diaminodiphenyl ether and pyromellitic anhydride into a vacuum oven, drying at a constant temperature of 40°C for 12 hours, and then evacuating at room temperature for 1 hour;

[0052] Step S2: 20.02 g of 4,4'-diaminodiphenyl ether was added to a three-necked flask containing 380 mL of N,N-dimethylacetamide solution, and the mixture was stirred continuously until the 4,4'-diaminodiphenyl ether was completely dissolved;

[0053] Step S3: then adding silicon carbide powder and graphene nanosheets, and stirring continuously for 30 minutes to make the silicon carbide powder and graphene nanosheets evenly dispersed; wherein the mass ratio of silicon carbide powder to graphene nanosheets is: 50:45;

[0054] Step S4: adding 22.25 g of pyromellitic anhydride, while reducing the stirring speed so that the stirring speed is ≤120 rad / min; in this step, the three-necked flask is placed in an ice-water mixture so that the reaction temperature is below 5° C.; wherein the total mass of the silicon carbide powder and the graphene nanosheets in step S3 is M1; the total mass of the 4,4'-diaminodiphenyl ether in step S2 and the pyromellitic anhydride in step S4 is M2; M1:M2=95:5;

[0055] Step S5: placing the viscous solution obtained in step S4 on a polytetrafluoroethylene mold, placing it in a vacuum oven at 40°C for 2 hours to remove bubbles, then heating it to 80°C and allowing it to stand for 1 hour to evaporate the solvent and form a film;

[0056] Step S6: placing the peeled composite film into a muffle furnace for gradient heating, the heating steps are: 100°C / 30min-150°C / 30min-200°C / 30min-250°C / 30min-300°C / 1h-350°C / 1h.

[0057] Example 4

[0058] A method for preparing a silicon carbide-induced graphene-based bidirectional heat-conducting high-temperature-resistant film comprises the following steps:

[0059] Step S1: putting graphene, silicon carbide, 4,4'-diaminodiphenyl ether and pyromellitic anhydride into a vacuum oven, drying at a constant temperature of 40°C for 12 hours, and then evacuating at room temperature for 1 hour;

[0060] Step S2: 20.02 g of 4,4'-diaminodiphenyl ether was added to a three-necked flask containing 380 mL of N,N-dimethylacetamide solution, and the mixture was stirred continuously until the 4,4'-diaminodiphenyl ether was completely dissolved;

[0061] Step S3: then adding silicon carbide powder and graphene nanosheets, and stirring continuously for 30 minutes to make the silicon carbide powder and graphene nanosheets uniformly dispersed; wherein the mass ratio of silicon carbide powder to graphene nanosheets is: 40:50;

[0062] Step S4: adding 22.25 g of pyromellitic anhydride, while reducing the stirring speed so that the stirring speed is ≤120 rad / min; in this step, the three-necked flask is placed in an ice-water mixture so that the reaction temperature is below 5° C.; wherein the total mass of the silicon carbide powder and the graphene nanosheets in step S3 is M1; the total mass of the 4,4'-diaminodiphenyl ether in step S2 and the pyromellitic anhydride in step S4 is M2; M1:M2=95:5;

[0063] Step S5: placing the viscous solution obtained in step S4 on a polytetrafluoroethylene mold, placing it in a vacuum oven at 40°C for 2 hours to remove bubbles, then heating it to 80°C and allowing it to stand for 1 hour to evaporate the solvent and form a film;

[0064] Step S6: placing the peeled composite film into a muffle furnace for gradient heating, the heating steps are: 100°C / 30min-150°C / 30min-200°C / 30min-250°C / 30min-300°C / 1h-350°C / 1h.

[0065] Example 5

[0066] A method for preparing a silicon carbide-induced graphene-based bidirectional heat-conducting high-temperature-resistant film comprises the following steps:

[0067] Step S1: putting graphene, silicon carbide, 4,4'-diaminodiphenyl ether and pyromellitic anhydride into a vacuum oven, drying at a constant temperature of 40°C for 12 hours, and then evacuating at room temperature for 1 hour;

[0068] Step S2: 20.02 g of 4,4'-diaminodiphenyl ether was added to a three-necked flask containing 380 mL of N,N-dimethylacetamide solution, and the mixture was stirred continuously until the 4,4'-diaminodiphenyl ether was completely dissolved;

[0069] Step S3: then adding silicon carbide powder and graphene nanosheets, and stirring continuously for 30 minutes to make the silicon carbide powder and graphene nanosheets uniformly dispersed; wherein the mass ratio of silicon carbide powder to graphene nanosheets is: 40:55;

[0070] Step S4: adding 22.25 g of pyromellitic anhydride, while reducing the stirring speed so that the stirring speed is ≤120 rad / min; in this step, the three-necked flask is placed in an ice-water mixture so that the reaction temperature is below 5° C.; wherein the total mass of the silicon carbide powder and the graphene nanosheets in step S3 is M1; the total mass of the 4,4'-diaminodiphenyl ether in step S2 and the pyromellitic anhydride in step S4 is M2; M1:M2=95:5;

[0071] Step S5: placing the viscous solution obtained in step S4 on a polytetrafluoroethylene mold, placing it in a vacuum oven at 40°C for 2 hours to remove bubbles, then heating it to 80°C and allowing it to stand for 1 hour to evaporate the solvent and form a film;

[0072] Step S6: placing the peeled composite film into a muffle furnace for gradient heating, the heating steps are: 100°C / 30min-150°C / 30min-200°C / 30min-250°C / 30min-300°C / 1h-350°C / 1h.

[0073] Test Example 1

[0074] Use a scanning electron microscope to observe the microscopic morphology. The corresponding morphological features were observed at different magnifications (200μm, 50μm, and 10μm) under the electron microscope. The electron microscope at a magnification of 200μm can roughly observe the fracture surface morphology of the film, the distribution of SiC particles in the film and whether the polymer fills the gaps intact can be observed at a magnification of 50μm, and the film under the electron microscope at a magnification of 10μm can clearly observe the hierarchical structure and neatness of the film. The results are shown in Figure 1 .

[0075] Test Example 2

[0076] The thermal conductivity test equipment LFA 447Nanoflash was used to test the in-plane and out-of-plane thermal conductivity of the film as a function of SiC content at room temperature and pressure (25°C, 101 kPa).

[0077] The test steps are to place the sample in the sample platform and heat it, then emit a laser pulse to heat the front of the sample, and at the same time the detector starts to record the temperature change of the back of the sample over time. The data of temperature change over time are used to calculate the thermal conductivity. The sample used for measuring the in-plane thermal conductivity is a circular film with a diameter of 25.4mm and a thickness of 180μm, and the sample used for measuring the out-of-plane thermal conductivity is a circular film with a diameter of 12.7mm and a thickness of 500μm.

[0078] Test results, see Figure 2 and Figure 3 . Where K ⊥ represents the out-of-plane thermal conductivity, K ∥ Indicates the in-plane thermal conductivity. In the figure, G70SiC25, G60SiC325, etc. represent the percentage of graphene and silicon carbide in the entire film, respectively. For example, G70SiC25 has 70% graphene and 25% silicon carbide. It can be seen from the figure that when the SiC concentration is 45wt.%K ⊥ Increase to the maximum value (8.00Wm -1 K -1 ), it is inferred here that this SiC concentration is suitable for forming a solid foam structure, which is beneficial for heat conduction in both vertical and horizontal directions. The subsequent films decrease with further increase in SiC weight percentage, which is due to the limited heat conduction path at relatively low graphene concentrations. The in-plane thermal conductivity (K ∥ ) shows a decreasing trend with the increase of SiC concentration because the incorporation of SiC destroys the in-plane orientation of graphene nanosheets. It can be concluded that the PI film (G50M45) produced by the SiC particles with a concentration of 45wt% has the highest thermal conductivity among these samples.

[0079] In the present invention, after dissolving 4,4'-diaminodiphenyl ether, graphene and silicon carbide are first added, and finally pyromellitic anhydride is added for polymerization. In the prior art, polyimide particles are physically dry-mixed with fillers such as graphene or silicon carbide and then rolled into a film, such as CN110591127A. Compared with the prior art, the in-plane thermal conductivity K of the present invention is ∥ High over 17Wm -1 K -1 , out-of-plane thermal conductivity K ⊥ Maximum over 4Wm -1 K -1 .

[0080] Test Example 3

[0081] The film obtained in Example 3 was subjected to a Joule heat test. The detection method was to use a DC power supply at a constant current (10A) to perform gradient voltage increase and decrease on a rectangular film (10*20mm). Each pressure lasted for 100 seconds. The positive and negative wires of the DC power supply were mainly attached to both sides of the film with single-sided copper glue. The test results are shown in Figure 4 , using only a relatively low voltage, the Joule heating of the film can reach a high temperature of nearly 350°C, indicating that the film has efficient Joule heating capabilities.

[0082] Test Example 4

[0083] The film obtained in Example 3 was tested for EMI shielding performance. The EMI test is mainly based on standards such as GB / T 30142-2013. The size and shape of the test sample in the preparation method meet the test conditions required by the equipment (a rectangle of 22.86*10.16). Then a relatively quiet electromagnetic environment was selected for testing, away from equipment that may interfere with the test results. It was ensured that the background noise level of the test site was at least 20dB lower than the test signal level, and a good grounding system was established. The test frequency range was then determined according to the expected frequency band of the shielding box. Test method:

[0084] Empty box test: When no device under test is placed inside the shielding box, use a signal generator to send a signal, and use a spectrum analyzer connected to an antenna outside the shielding box to receive the signal, and record the received signal strength at each frequency point as the reference level.

[0085] Load test: Place a simulated load similar to the actual usage inside the shielding box, repeat the above test steps, and record the data.

[0086] Among them, SET (single-particle transient) refers to a single high-energy particle (such as heavy ions in cosmic rays) hitting a semiconductor device in a radiation environment, causing the device to generate a temporary error signal. This phenomenon is of particular concern in aerospace electronic equipment because cosmic rays can affect these devices in space. SER (single-particle effect) refers to the effect caused by a single high-energy particle. It includes a series of phenomena, such as SET (single-particle transient), SEU (single-particle upset, that is, a single particle causes a change in the state of a storage unit), SEL (single-particle lockout, that is, the device enters a continuous high-current state due to a radiation event), etc. SEA (single-particle latchup) is a type of single-particle effect, which refers to the parasitic transistor in the device being triggered by high-energy particles, thereby causing a high-current latchup phenomenon. This effect may cause device damage or functional failure. See the test results. Figure 5 , it can be seen that the film prepared by the method exhibits excellent EMI shielding performance.

[0087] Test Example 5

[0088] Flame retardant test, by Figure 6 It can be seen that the morphology of the film did not change significantly when the alcohol lamp was burned for at least 30 seconds, demonstrating its excellent anti-combustion performance.

[0089] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a silicon carbide-induced graphene-based bidirectional thermally conductive high-temperature resistant film, characterized in that: The following steps are involved: Step S1: pretreating graphene, silicon carbide, 4,4'-diaminodiphenyl ether, and pyromellitic anhydride; Step S2: putting 4,4'-diaminodiphenyl ether into N,N-dimethylacetamide solution, and stirring continuously until 4,4'-diaminodiphenyl ether is completely dissolved; Step S3: then adding silicon carbide powder and graphene nanosheets, and stirring continuously for 30 minutes to make the silicon carbide powder and graphene nanosheets evenly dispersed; Step S4: adding pyromellitic anhydride while reducing the stirring speed; in this step, the three-necked flask is placed in an ice-water mixture so that the reaction temperature is below 5°C; Step S5: removing bubbles from the viscous solution obtained in step S4 and drying it to form a film; Step S6: subjecting the membrane to a gradient temperature increase.

2. The method for preparing a silicon carbide-induced graphene-based bidirectional thermally conductive high-temperature resistant film according to claim 1, characterized in that: The gradient temperature increase steps in step S6 are: 100°C / 30min-150°C / 30min-200°C / 30min-250°C / 30min-300°C / 1h-350°C / 1h.

3. The method for preparing a silicon carbide-induced graphene-based bidirectional thermally conductive high-temperature resistant film according to claim 1, characterized in that: In the step S3, the mass ratio of silicon carbide powder to graphene nanosheets is 70-40:25-55.

4. The method for preparing a silicon carbide-induced graphene-based bidirectional thermally conductive and high-temperature resistant film according to claim 3, characterized in that the mass ratio of the silicon carbide powder to the graphene nanosheets is 70:25, 60:35, 50:45, 40:50 and 40:

55.

5. The method for preparing a silicon carbide-induced graphene-based bidirectional thermally conductive and high-temperature resistant film according to claim 1, characterized in that the pretreatment method in step S1 is to put graphene, silicon carbide, 4,4'-diaminodiphenyl ether, and pyromellitic anhydride into a vacuum oven, dry them at a constant temperature of 40°C for 12 hours, and then evacuate them at room temperature for 1 hour.

6. The method for preparing a silicon carbide-induced graphene-based bidirectional thermally conductive and high-temperature resistant film according to claim 1, characterized in that the stirring speed after reduction in step S4 is ≤120 rad / min.

7. The method for preparing a silicon carbide-induced graphene-based bidirectional thermally conductive and high-temperature resistant film according to claim 1, characterized in that the total mass of the silicon carbide powder and the graphene nanosheets in step S3 is M1; the total mass of 4,4'-diaminodiphenyl ether in step S2 and pyromellitic anhydride in step S4 is M2; wherein M1:M2=95:

5.

8. The method for preparing a silicon carbide-induced graphene-based bidirectional heat-conducting and high-temperature-resistant film according to claim 1 is characterized in that the step of removing bubbles and drying to form a film in step S5 is: after removing bubbles in a 40°C vacuum oven for 2 hours, the temperature is raised to 80°C and allowed to stand for 1 hour to evaporate the solution and form a film.

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