Graphene heat diffusion structural plate and preparation method thereof

Abstract

The invention provides a graphene heat diffusion structural plate and a preparation method thereof. The graphene plate is creatively used as a heat conduction material on a spacecraft, and the defects that a traditional aluminum alloy heat conduction material is large in weight, low in heat conductivity and the like are overcome by means of the characteristics of light weight, high heat conductivity, small thermal expansion coefficient and the like of the graphene plate. Meanwhile, the carbon nanotube film is adopted to package the graphene plate, on one hand, the characteristics of small brittleness, excellent mechanical property, surface wear resistance and the like of the carbon nanotube film are utilized, and the problem that the graphene plate is difficult to directly apply due to the fact that the graphene plate is large in brittleness, low in mechanical strength and easy to damage is solved; on the other hand, the high-toughness resin is fully and effectively borne by utilizing pores of a porous network cross-linked structure of the carbon nanotube film, the mechanical and heat-conducting properties in the thickness direction are enhanced through adhesion of the high-toughness resin, and good coating and protection are formed on the porous high-heat-conducting graphene plate, so that application substitution on a spaceflight heat diffusion structure is realized.

Description

Technical Field

[0001] This invention belongs to the field of high thermal conductivity materials for spacecraft, and relates to a graphene heat-expanding structural plate and its preparation method. Background Technology

[0002] In recent years, thermal management issues have become increasingly prevalent in weaponry and aerospace, with heat conduction gradually becoming a key factor limiting the structural design of future aircraft and spacecraft. In traditional spacecraft heat dissipation schemes, aluminum alloys are commonly used for heat dissipation, primarily for heat amplification and transfer in high-power components, temperature homogenization in equipment, or as part of integrated mechanical-thermal structures. However, aluminum alloys constitute a significant portion of the weight in spacecraft structures such as satellites, and their relatively low thermal conductivity (around 200 W / (m·K)) cannot meet the higher thermal conductivity requirements of next-generation spacecraft. Furthermore, the coefficient of thermal expansion of aluminum alloys is approximately 2.36 × 10⁻⁶. -5 K -1 The coefficient of thermal expansion of the composite skin is approximately 1.5 × 10⁻⁶. -6 K -1 The mismatch in the coefficients of thermal expansion will lead to problems such as bending deformation, warping, large internal stress, delamination and debonding on the assembly surfaces of the two parts.

[0003] To address the aforementioned issues, research on lightweight, high thermal conductivity materials has flourished in recent years, with novel materials possessing even higher thermal conductivity representing a future direction for spacecraft thermal control systems. Some novel carbon-based thermally conductive materials (such as graphene) exhibit highly oriented structures, utilizing phonon heat transfer mechanisms. They possess characteristics such as high thermal conductivity, stable performance (radiation resistance, minimal changes in thermal conductivity with external environment), low coefficient of thermal expansion, and low specific gravity (only 20%–50% of that of metallic materials). Graphene is a two-dimensional crystalline material composed of a tightly packed single layer of carbon atoms. Its excellent thermal conductivity primarily stems from its unique heat conduction mode and inherent internal structure. Structurally, graphene is a two-dimensional sheet structure with a large specific surface area, reducing phonon boundary scattering at grain boundaries. Furthermore, the orderly arrangement of carbon atoms in graphene allows its lattice vibrations to propagate forward in a regular manner. Importantly, the small mass of carbon atoms and the strong covalent bonds between carbon atoms enable phonons to have relatively high sound speeds.

[0004] However, high thermal conductivity graphene films also have some problems: (1) High thermal conductivity graphene films are brittle, have poor mechanical properties, and are easily worn and damaged; (2) High thermal conductivity graphene films are currently mostly used in civilian applications, and there is little research on their performance in the vacuum environment of spacecraft; however, it has been found that high thermal conductivity graphene films are prone to bulging in a vacuum environment, which limits their engineering application in spacecraft. Therefore, how to apply high thermal conductivity graphene films to the field of spacecraft is the technical problem to be solved by this invention. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings and deficiencies of the prior art and provide a graphene heat-expanding structural plate and its preparation method.

[0006] The objective of this invention can be achieved through the following methods: In a first aspect, the present invention provides a graphene heat-expanding structural plate, the graphene heat-expanding structural plate comprising a carbon nanotube film, a graphene plate, and a carbon nanotube film arranged sequentially; a high-toughness resin layer is disposed between the carbon nanotube film and the graphene plate, the high-toughness resin layer comprising a layer body and protrusions on both sides, the protrusions on both sides being respectively embedded in the pores of the carbon nanotube film and the graphene plate.

[0007] In one embodiment of the present invention, the thickness of the graphene heat-diffusing structure plate is 0.43-0.49 mm, and the thickness of the carbon nanotube film does not exceed 15 μm. The graphene heat-diffusing structure plate of the present invention is produced by floating catalytic chemical vapor deposition.

[0008] In one embodiment of the present invention, the graphene plate includes a plurality of pores extending through the thickness direction; the carbon nanotube film includes pores with a porous network cross-linked structure. The pores in the graphene plate, extending through the thickness direction and uniformly arranged, allow for better impregnation of the graphene plate by the high-toughness resin and, through a "rivet" effect, connect the carbon nanotube film, thereby reinforcing the thickness direction of the heat-expanding plate; the porous network cross-linked structure in the carbon nanotube film can fully and effectively support the high-toughness resin, achieving good coating and protection of the porous, high-thermal-conductivity graphene plate through the adhesion of the high-toughness resin.

[0009] In this invention, the carbon nanotube film possesses the characteristics of being thin, lightweight, highly thermally conductive, and highly electrically conductive.

[0010] As one embodiment of the present invention, the carbon nanotube film has a two-layer structure; a high-toughness resin layer is disposed between the two layers, and the protrusions on both sides of the high-toughness resin layer are respectively embedded in the pores of the two layers.

[0011] In one embodiment of the present invention, the high-toughness resin layer comprises epoxy resin, curing agent, and accelerator. The high-toughness resin of the present invention is a medium-temperature curing epoxy resin, which has the characteristics of high strength, good toughness, low viscosity, and good flowability, and can act as a "rivet" between porous high thermal conductivity graphene plate and carbon nanotube thin film.

[0012] Further, the mass ratio of the epoxy resin, curing agent, and accelerator is 90-110:70-90:1-3. Preferably, it is 100:80:2.

[0013] Further, the epoxy resin includes epoxy resin E51; the curing agent includes methyltetrahydrophthalic anhydride; and the accelerator includes methylimidazole.

[0014] Furthermore, the method for preparing the high-toughness resin layer includes: mixing and stirring epoxy resin, curing agent, and accelerator, followed by vacuum degassing treatment at 30-50°C. This ensures that no bubbles escape from the resin under vacuum conditions.

[0015] Secondly, the present invention provides a method for preparing a graphene heat-expanding structural plate, comprising the following steps: S1. Coat both sides of the graphene plate with high-toughness resin and vacuum dry to remove gas; S2. Apply adhesive to one side of the vacuum-dried graphene plate, lay a carbon nanotube film, and perform vacuum pre-extraction. S3. Repeat step S2 to lay a carbon nanotube film on the other side of the graphene plate, and then perform vacuum drying, degassing, and curing to obtain the final product.

[0016] As one embodiment of the present invention, in step S1 or S3, the temperature of the vacuum drying and degassing is 30-50°C, the time is 10-20 min, and the vacuum degree is not lower than -0.097 MPa.

[0017] In some embodiments, step S1 specifically involves: laying several layers of impermeable polytetrafluoroethylene film on a rigid flat mold, placing a graphene plate on the impermeable polytetrafluoroethylene film, uniformly coating the graphene plate with high-toughness resin, transferring it to a vacuum oven through a rigid mold, and degassing it at 30-50 ℃ for 15 min with a vacuum degree not lower than -0.097 MPa.

[0018] In some embodiments, step S2 specifically involves: applying an appropriate amount of adhesive to the graphene plate, then uniformly laying a layer of pre-cut carbon nanotube film to ensure that its size is larger than the porous, high thermal conductivity graphene plate; subsequently, uniformly coating the first layer of carbon nanotube film with high toughness resin, and uniformly laying the second layer of carbon nanotube film to ensure that each layer of carbon nanotube film is uniformly impregnated with resin, without bulging, and uniformly laid.

[0019] In one embodiment of the present invention, in step S3, the curing temperature is 100-120℃, the time is 1-3h, and the heating rate is 1-2℃ / min.

[0020] In some embodiments, step S3 specifically involves: sequentially laying two layers of breathable PTFE release cloth and one layer of impermeable PTFE release cloth on top of a graphene plate with two layers of carbon nanotube films, and placing it, along with a rigid mold, in a vacuum bag for pre-evacuation. After pre-evacuation, the porous graphene plate is flipped over, and the above steps are repeated to lay two layers of carbon nanotube films on the other side of the graphene plate, followed by two layers of breathable PTFE release cloth and one layer of impermeable PTFE release cloth. After laying, the plate is transferred to a vacuum oven through a rigid mold and degassed at 30-50 °C for 15 min, with a vacuum level not lower than -0.097 MPa. Finally, curing is completed in the vacuum oven, with vacuum throughout, a heating rate of 1 °C / min, and a curing period of 110 °C / 2 h. The plate is then demolded after cooling to room temperature in the oven.

[0021] The sample cured by this invention has a smooth surface, with the resin evenly adhering to the surface of the graphene plate and no obvious bubbling.

[0022] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention creatively utilizes graphene sheets as thermal conductive materials in spacecraft, leveraging their lightweight, high thermal conductivity, and low coefficient of thermal expansion to overcome the drawbacks of traditional aluminum alloy thermal conductive materials, such as heavy weight and low thermal conductivity. Simultaneously, carbon nanotube films are used to encapsulate the graphene sheets. On one hand, the low brittleness, excellent mechanical properties, and wear-resistant surface of carbon nanotube films solve the problem of the difficulty in direct application caused by the high brittleness, low mechanical strength, and easy breakage of graphene sheets. On the other hand, the porous network cross-linked structure of the carbon nanotube film effectively supports high-toughness resin, and the bonding with high-toughness resin enhances the mechanical and thermal conductivity properties in the thickness direction, achieving excellent encapsulation and protection of the porous, high-thermal-conductivity graphene sheet.

[0023] 2. This invention utilizes the technical features of high-toughness resin-based carbon nanotube film coating graphene plates and employs machining and drilling processes to prepare permeable pores in the thickness direction. The high-performance resin bonding between the graphene material and the carbon nanotube film exhibits a "rivet" effect, enhancing the mechanical and thermal conductivity in the thickness direction. Compared to 6063 aluminum alloy, this invention achieves lightweight and superior thermal conductivity, enabling its application as a replacement in aerospace heat expansion structures. Attached Figure Description

[0024] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a structural diagram of the graphene heat-expanding structure plate in Example 1; Figure 2 This is a microscopic image of the carbon nanotube film with a porous network cross-linked structure in Example 1; Figure 3 This is a schematic diagram of the pores penetrating the thickness direction of the graphene plate in Example 1. Figure 4 This is a photograph of the high-toughness resin used in Example 1; Figure 5 This is a schematic diagram of the high-toughness resin coating on the graphene plate in Example 1; Figure 6 This is a schematic diagram showing the relative dimensions of the nanotube film and the graphene plate in Example 1; Figure 7 This is a photograph of the graphene plate encapsulated with carbon nanotube film in Example 1. Figure 8 This is a photograph of the carbon nanotube thin film-encapsulated graphene heat spreader honeycomb in Example 2. Figure reference numerals: 1-Graphene heat expansion structure plate, 2-Carbon nanotube film, 3-Graphene plate, 4-High toughness resin layer, 5-Protrusion. Detailed Implementation

[0025] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The following examples are implemented under the premise of the technical solution of the present invention, providing detailed implementation methods and specific operating procedures, which will help those skilled in the art to further understand the present invention. It should be noted that the scope of protection of the present invention is not limited to the following embodiments; any adjustments and improvements made under the concept of the present invention are all within the scope of protection of the present invention.

[0026] Example 1 like Figure 1 As shown, this embodiment provides a graphene heat-expanding structure plate 1, which includes a carbon nanotube film 2, a graphene plate 3, and a carbon nanotube film 2 arranged sequentially; a high-toughness resin layer 4 is disposed between the carbon nanotube film and the graphene plate, the high-toughness resin layer including a layer body and protrusions 5 on both sides, the protrusions on both sides being embedded in the pores of the carbon nanotube film and the graphene plate respectively.

[0027] The graphene heat-expanding structure plate has a thickness of 0.49 mm, and the carbon nanotube film has a thickness of 15 μm. Carbon nanotube films contain pores with a porous network cross-linked structure, such as Figure 2 As shown, the graphene plate contains several pores that extend through the thickness direction, such as... Figure 3 As shown; The carbon nanotube film has a two-layer structure with a high-toughness resin layer between the two layers. The protrusions on both sides of the high-toughness resin layer are embedded in the pores of the two layers.

[0028] The preparation method of the graphene heat-diffusing structure plate includes the following steps: Prepare the high-toughness resin according to the requirements (Component A: epoxy resin E51 main body, Component B: methyltetrahydrophthalic anhydride curing agent, Component C: methylimidazolium accelerator, mass ratio 100:80:2), stir thoroughly to ensure uniform mixing, and then perform vacuum degassing treatment on the resin at 50℃ until no more bubbles overflow under vacuum conditions. After degassing, the resin should be clear and free of bubbles. Figure 4 As shown. Due to the high brittleness and easy damage of graphene plates, the porous, high thermal conductivity graphene plate, along with auxiliary materials, needs to be placed on a rigid flat mold for processing. A high-toughness resin is then uniformly coated onto the porous, high thermal conductivity graphene plate, such as... Figure 5 .

[0029] The graphene board was laid flat on an impermeable polytetrafluoroethylene (PTFE) film and transferred via a flat tray to a vacuum oven at 50 °C for degassing (vacuum level not lower than -0.097 MPa) for 15 minutes. Under vacuum conditions, numerous bubbles were observed emerging, which was attributed to the extraction of gas from the pores of the graphene board. During this process, resin filled the pores, and bubbles embedded during resin coating were also removed. After vacuum treatment, the surface of the porous, high thermal conductivity graphene board was fully impregnated with resin, which adhered uniformly to the surface.

[0030] After applying an appropriate amount of adhesive to the porous, high thermal conductivity graphene plate, a pre-cut carbon nanotube film is evenly laid on top, ensuring that the size of the carbon nanotube film is larger than the size of the porous, high thermal conductivity graphene plate. Figure 6 A high-toughness resin was uniformly coated onto the first layer of carbon nanotube film, ensuring resin coverage at every location. A second layer of carbon nanotube film was then uniformly laid on top of the first layer. Two layers of breathable PTFE release cloth and one layer of impermeable PTFE release cloth were then sequentially laid on top of the porous, high-thermal-conductivity graphene plate with the two carbon nanotube films. The plate was then placed in a vacuum bag with the sample using a flat-plate transport fixture for pre-vacuuming for 15 minutes. After pre-vacuuming, the above steps were repeated to lay the two carbon nanotube films on the other side of the porous, high-thermal-conductivity graphene plate. After laying, the sample was placed in a vacuum bag with the flat-plate transport fixture for pre-vacuuming for 15 minutes. The vacuum bag is prepared by layering in the following order: 2 layers of breathable PTFE release fabric / 1 layer of non-breathable PTFE release fabric / sample / 2 layers of breathable PTFE release fabric / 1 layer of non-breathable PTFE release fabric / non-woven fabric / vacuum bag.

[0031] The material was transferred to a vacuum oven and degassed at 50 °C for 15 min, with a vacuum level not lower than -0.097 MPa. Finally, curing was completed in the vacuum oven, with vacuum maintained throughout. The heating rate was 1 °C / min, and the curing period was 110 °C / 2 h. After cooling to room temperature in the oven, the material was demolded to obtain the graphene thermal expansion structure plate. Figure 7 As shown. During the demolding process, pay attention to the force with which the auxiliary materials are released to prevent damage to the graphene plate.

[0032] Comparative Example 1 The only difference between the graphene heat-expanding structural plate in this comparative example and Example 1 is that the carbon nanotube film and the high-toughness resin layer are omitted, and only the graphene plate is retained.

[0033] Performance testing The densities ρ of 6063 aluminum alloy, graphene plate (Comparative Example 1 sample), and carbon nanotube film-encapsulated graphene plate (Example 1 sample) were tested, and the results are shown in Table 1. Compared with 6063 aluminum alloy, carbon nanotube film-encapsulated graphene plate has a lower density, demonstrating the advantage of being lightweight.

[0034] Table 1. Density test results (unit: g / cm³) 3 )

[0035] The specific heat capacity (c) of 6063 aluminum alloy and the carbon nanotube film-encapsulated graphene plate from Example 1 at 25°C was tested using the DSC method. The specific heat capacity of the carbon nanotube film-encapsulated graphene plate was measured to be 0.65 J / (g). (℃), the results are shown in Table 2.

[0036] Table 2. Specific heat capacity test results at 25℃ (unit: J / (g)) ℃))

[0037] The thermal conductivity of 6063 aluminum alloy, the graphene plate of Comparative Example 1, and the graphene plate encapsulated with carbon nanotube film of Example 1 are compared in Table 3. Compared to 6063 aluminum alloy, the graphene plate encapsulated with carbon nanotube film of Example 1 exhibits superior in-plane thermal conductivity. Compared to the graphene plate of Comparative Example 1, the graphene plate encapsulated with carbon nanotube film of Example 1 is less brittle, has excellent mechanical properties, and its surface is less prone to wear and damage.

[0038] Table 3 Thermal conductivity test results (unit: W / (m)) K)

[0039] The vacuum outgassing performance test was conducted in accordance with the standard QJ1558B-2016. Specifically, the material was prepared into a sample according to the standard requirements, stored in a constant temperature and humidity chamber for 24 h, and then placed in a sample boat. The sample boat containing the sample was uniformly heated in a vacuum to cause the sample to exhale. The exhaled gas molecules were deposited on a collection plate that maintained a constant temperature. The total mass loss (TML) was calculated by weighing the change in mass of the sample boat containing the sample before and after the process. The condensable volatile matter (CVCM) of the collection plate was calculated by weighing the change in mass of the collection plate before and after the test. After the test, the sample was stored in a constant temperature and humidity chamber again, and the mass of the sample was weighed again to obtain the water vapor reabsorption (WVR). Test conditions: (1) Vacuum degree better than 7×10-3 Pa; (2) Sample heating temperature: 125±1 ℃; (3) Collection plate temperature: 25±1 ℃; (4) Thermal vacuum time: 24h.

[0040] The average condensable volatile matter content of the graphene plate encapsulated with carbon nanotube film was 0.044%, which meets the technical requirement of <0.1% for condensable volatile matter content of non-metallic materials in spacecraft, meaning it is less prone to bulging. Specific test results are shown in Table 4.

[0041] Table 4. Vacuum venting performance test results

[0042] Example 2 Example 2 is an extension of Example 1.

[0043] Aluminum honeycomb panels with dimensions of 5×0.04×27.1 mm were prepared by oven curing. The honeycomb panel was made of 0.3 mm thick aluminum skin. After cleaning the surface impurities, epoxy film (AG-80 epoxy film) was evenly applied on top of it.

[0044] After demolding, heat spreader plates were bonded on a platform. The heat spreader plates consisted of a 6063 aluminum alloy heat spreader plate and an encapsulated graphene heat spreader plate. The 6063 aluminum alloy heat spreader plate measured 292 mm × 292 mm × 2 mm, while the encapsulated graphene heat spreader plate measured 292 mm × 292 mm × 0.50 mm. The 0.50 mm thick encapsulated graphene heat spreader plate had a higher heat flux than the 2 mm thick aluminum alloy heat spreader plate. Tooling was used to assist in pressurization, and J-133 adhesive was used for room temperature curing to ensure uniform bonding of the heat spreader plates in the center of the honeycomb panel. Residual adhesive and honeycomb burrs were cleaned from the heat spreader plates, resulting in the 6063 heat spreader plate honeycomb and the carbon nanotube film encapsulated graphene heat spreader plate honeycomb. The carbon nanotube film encapsulated graphene heat spreader plate honeycomb is shown below. Figure 8 As shown, under the same heat flux conditions, the carbon nanotube film-encapsulated graphene plate has a thinner thickness than the 6063 aluminum alloy plate, thus greatly reducing the weight of the material itself.

[0045] Temperature difference tests were conducted on 6063 heat spreader honeycomb and carbon nanotube film-encapsulated graphene heat spreader honeycomb. The test method involved connecting 20 T-type thermocouples to the honeycomb plate. The thermocouples were marked as 101#, 102#, 103#, etc. The heating element was 80mm×80mm in size, with a rated power of 20W and a rated voltage of 24V. Heating powers of 10W, 15W, and 20W were applied to the two types of honeycomb plates, respectively, to ensure that thermocouples were distributed on the heating element, heat spreader plate, and honeycomb plate.

[0046] Table 5 summarizes the temperature differences of the two types of heat-expanding honeycomb plates. It can be seen that the temperature difference of the graphene heat-expanding honeycomb plate is slightly lower than that of the aluminum alloy heat-expanding honeycomb plate. The encapsulated graphene heat-expanding plate prepared by this invention has obvious advantages.

[0047] Table 5 Summary of temperature differences between the two types of heat-expanding honeycomb panels

[0048] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A graphene heat-expanding structural plate, characterized in that, The graphene heat expansion structure plate includes a carbon nanotube film, a graphene plate, and a carbon nanotube film arranged sequentially; a high-toughness resin layer is disposed between the carbon nanotube film and the graphene plate, the high-toughness resin layer includes a layer body and protrusions on both sides, the protrusions on both sides being embedded in the pores of the carbon nanotube film and the graphene plate respectively.

2. The graphene heat-diffusing structural plate according to claim 1, characterized in that, The thickness of the graphene heat-expanding structure plate is 0.43-0.49 mm, and the thickness of the carbon nanotube film is no more than 15 μm.

3. The graphene heat-diffusing structural plate according to claim 1, characterized in that, The graphene plate contains a number of pores that extend through the thickness direction; the carbon nanotube film contains pores with a porous network cross-linked structure.

4. The graphene heat-diffusing structural plate according to claim 1, characterized in that, The carbon nanotube film has a two-layer structure; a high-toughness resin layer is disposed between the two layers, and the protrusions on both sides of the high-toughness resin layer are respectively embedded in the pores of the two layers.

5. The graphene heat-diffusing structural plate according to claim 1, characterized in that, The high-toughness resin layer comprises epoxy resin, curing agent, and accelerator; the mass ratio of epoxy resin, curing agent, and accelerator is 90-110:70-90:1-3.

6. The graphene heat-diffusing structural plate according to claim 5, characterized in that, The epoxy resin includes epoxy resin E51; the curing agent includes methyltetrahydrophthalic anhydride; and the accelerator includes methylimidazole.

7. The graphene heat-diffusing structural plate according to claim 5, characterized in that, The preparation method of the high-toughness resin layer includes: mixing and stirring epoxy resin, curing agent and accelerator, and then performing vacuum degassing treatment at 30-50℃.

8. A method for preparing a graphene heat-diffusing structural plate according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Coat both sides of the graphene plate with high-toughness resin and vacuum dry to remove gas; S2. Apply adhesive to one side of the vacuum-dried graphene plate, lay a carbon nanotube film, and perform vacuum pre-extraction. S3. Repeat step S2 to lay a carbon nanotube film on the other side of the graphene plate, and then perform vacuum drying, degassing, and curing to obtain the final product.

9. The preparation method according to claim 8, characterized in that, In step S1 or S3, the temperature of the vacuum drying and degassing is 30-50 ℃, the time is 10-20 min, and the vacuum degree is not lower than -0.097 MPa.

10. The preparation method according to claim 8, characterized in that, In step S3, the curing temperature is 100-120℃, the time is 1-3h, and the heating rate is 1-2℃ / min.

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