Carbon nanotube / graphene composite hyperbolic graphite carbon foam and method of making

Abstract

The application discloses a carbon nanotube / graphene composite double-curved graphite carbon foam and a preparation method thereof. The carbon nanotube is introduced into the graphene foam material, the carbon nanotube can fix graphene layers under ultra-high temperature conditions, the characteristics of the graphene layers are inhibited from easy slipping, and the lattice structure of the graphene material is constructed through high-temperature graphitization, so that the material still has good elasticity and flexibility under extreme high-temperature conditions. The problem of poor elasticity of the carbon foam after graphitization is solved, and the carbon foam can be effectively applied to the field of extreme high-temperature thermal interface materials.

Description

Technical Field

[0001] This invention relates to the field of ultra-high temperature thermal interface materials, specifically to a carbon nanotube / graphene composite hyperboloid graphite carbon foam and its preparation method. Background Technology

[0002] With the rapid development of aerospace technology, cutting-edge equipment such as aircraft, satellites, deep space probes, and nuclear fusion devices are constantly pushing the limits of extreme environments. These systems often face severe challenges during operation, including ultra-high temperatures, strong thermal shock, high vacuum, or corrosive media. In particular, for hypersonic aircraft (such as air-breathing scramjet engines), reusable rockets, and nuclear thermal propulsion systems, the heat dissipation of key components (such as combustion chambers, thermal protection structures, and high-power electronic equipment) directly determines the reliability and service life of the system.

[0003] Traditional thermal interface materials (such as silicone grease, metal foil, or graphite sheets) need to meet two core requirements simultaneously in practical applications: good interfacial adhesion to reduce contact thermal resistance and high intrinsic thermal conductivity to achieve efficient heat conduction. However, existing material systems struggle to achieve both, especially under extreme high-temperature environments.

[0004] Graphene aerogel, a three-dimensional porous material formed by the self-assembly of two-dimensional graphene sheets, exhibits excellent interfacial bonding capabilities in its untreated state due to its ultra-low density, high porosity, and superior structural compressibility. It can adaptively fill micron- and nanometer-level surface roughness, significantly reducing interfacial contact thermal resistance. However, its biggest bottleneck as a thermal interface material lies in the numerous defects in the graphene sheets and the incomplete sp² carbon network in the original aerogel, resulting in extremely low intrinsic thermal conductivity (typically less than 50 W / mK), far from realizing the thermal conductivity potential of graphene.

[0005] To improve thermal conductivity, high-temperature graphitization (>2500°C) is necessary, effectively repairing defects and increasing crystallinity, potentially pushing thermal conductivity above 1000 W / mK. However, existing graphitization processes lead to severe structural degradation—at high temperatures, the van der Waals forces-dominated interlaminar interactions cannot withstand thermal stress, causing irreversible collapse, densification, and even embrittlement of the three-dimensional network, completely losing its original flexibility and adhesion. This contradiction between "improved thermal conductivity" and "loss of adhesion" severely restricts the application of graphene aerogels in high-performance thermal management.

[0006] Furthermore, while current ceramic-based thermal interface materials suitable for high-temperature environments (such as boron nitride and aluminum nitride composites) can withstand 800–1200°C, they still face problems such as thermal conductivity decay and interface delamination in ultra-high temperatures (>2000°C), vacuum, or inert atmospheres. Most commercial organic-based or metal-based materials fail above 300°C: organic components undergo pyrolysis and carbonization, metals oxidize or soften, and ceramics become brittle, leading to a sharp increase in interfacial thermal resistance and even triggering system-level thermal runaway. Summary of the Invention

[0007] To address the difficulty in preparing thermal interface materials suitable for ultra-high temperature applications in existing technologies, this invention provides a carbon nanotube / graphene composite hyperboloid graphite carbon foam and its preparation method. By introducing carbon nanotubes into the graphene foam material, the carbon nanotubes can fix the graphene sheets under ultra-high temperature conditions, suppressing the easy slippage of graphite crystal sheets. At the same time, a graphite lattice structure is constructed through high-temperature graphitization, enabling the material to maintain good elasticity and flexibility under extreme high temperature conditions. This solves the problem of poor elasticity of carbon foam after graphitization and can be effectively applied in the field of extreme high-temperature thermal interface materials.

[0008] Specifically, the preparation method of the present invention includes the following steps: (1) uniformly mixing carbon nanotube solution and graphene oxide aqueous dispersion, drying into a film by scraper coating method, immersing in foaming agent, and foaming at room temperature to obtain carbon nanotube / graphene oxide hyperboloid composite carbon foam; the mass ratio of graphene oxide to carbon nanotube is greater than 4:1;

[0009] (2) Carbon nanotube / graphene hyperboloid composite carbon foam was obtained by chemical reduction of carbon nanotube / graphene hyperboloid composite carbon foam;

[0010] (3) The carbon nanotube / graphene hyperboloid composite carbon foam was heated at 3000℃ for 2h to perform graphitization treatment, and carbon nanotube / graphene composite hyperboloid graphite carbon foam was obtained.

[0011] Further, the foaming agent in step 1 is a 1 wt% hydrazine hydrate solution.

[0012] Preferably, the carbon nanotubes are single-walled carbon nanotubes.

[0013] Preferably, the length of the carbon nanotubes is 5-20 micrometers.

[0014] Furthermore, the chemical reduction in step 2 uses hydroiodic acid and acetic acid in a mass ratio of 1:3, at a temperature of 90°C, for a time of 12 hours.

[0015] Furthermore, the heating rate in step 3 is 10℃ / min.

[0016] The beneficial effects of this invention are as follows: the thermal interface material prepared by this invention has good flexibility and elasticity, and after 10,000 cycles of 50% strain compression, the remaining stress is 85% of the initial stress, and the plastic deformation is 1%. Furthermore, it still retains elasticity under high temperature conditions. Attached Figure Description

[0017] Figure 1 The image shows the SEM images of the graphene carbon foam obtained in Example 1 (the upper left image shows the hyperboloidal microstructure of the graphene carbon foam, the upper right image shows the morphology of carbon nanotubes distributed on the carbon foam facets, and the lower left image shows the morphology of carbon nanotubes distributed between the carbon foam facets).

[0018] Figure 2 The figures are Marlins curves (the left figure is the Marlins curve of carbon nanotube-graphene composite carbon foam in Example 1, and the right figure is the Marlins curve of pure graphene carbon foam in Comparative Example 1).

[0019] Figure 3 Infrared image of carbon nanotube-graphene composite graphite carbon foam at 2000℃. Detailed Implementation

[0020] 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.

[0021] 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.

[0022] The embodiments of the present invention will be further described below with reference to several examples.

[0023] 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.

[0024] 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.

[0025] Example 1

[0026] 1) Graphene oxide aqueous dispersion and carbon nanotube aqueous dispersion were mixed at a solid content mass ratio of 4:1. After being thoroughly mixed in a homogenizer, graphene oxide-carbon nanotube composite film was prepared by casting and then naturally dried.

[0027] 2) The dried membrane was immersed in a 1 wt% hydrazine hydrate solution and foamed at room temperature to prepare hyperboloid graphene oxide-carbon nanotube composite carbon foam.

[0028] 3) The graphene oxide-carbon nanotube composite carbon foam was chemically reduced using hydroiodic acid / acetic acid vapor at a temperature of 90℃ for 12 hours.

[0029] 4) High-temperature graphitization treatment: The temperature is increased to 3000℃ at a rate of 10℃ / min under high-purity argon gas and held for 2 hours to ensure that the graphitization process is fully completed.

[0030] 5) Compression tests were conducted using a compression testing machine. The results showed that the prepared composite carbon foam retained 85% of its initial stress after 10,000 cycles of 50% strain compression, with a plastic deformation of only 1%, exhibiting good elasticity. Figure 3 It can be seen that the material can withstand pressure at 2000℃ without structural collapse, and can recover after 50% compression, demonstrating its elasticity.

[0031] Example 2

[0032] 1) Graphene oxide aqueous dispersion and carbon nanotube aqueous dispersion were mixed at a solid content mass ratio of 9:1. After being thoroughly mixed in a homogenizer, graphene oxide-carbon nanotube composite film was prepared by casting and then naturally dried.

[0033] 2) The dried membrane was immersed in a 1wt% hydrazine hydrate solution and foamed at room temperature to prepare hyperboloid graphene oxide-carbon nanotube composite carbon foam.

[0034] 3) The graphene oxide-carbon nanotube composite carbon foam was chemically reduced using hydroiodic acid / acetic acid vapor at a temperature of 90℃ for 12 hours.

[0035] 4) High-temperature graphitization treatment: The temperature is increased to 3000℃ at a rate of 10℃ / min under high-purity argon gas and held for 2 hours to ensure that the graphitization process is fully completed.

[0036] 5) Compression tests were conducted on the prepared GA / CNT carbon foam using a compression testing machine. The results showed that after 10,000 cycles of 50% strain compression, the residual stress of the GA / CNT carbon foam was 85% of the initial stress, and the plastic deformation was 1%, indicating good elasticity.

[0037] Example 3

[0038] 1) Graphene oxide aqueous dispersion and carbon nanotube aqueous dispersion were mixed at a mass ratio of 19:1. After being thoroughly mixed in a homogenizer, graphene oxide-carbon nanotube composite films were prepared by casting and then naturally dried.

[0039] 2) The dried membrane was immersed in a 1wt% hydrazine hydrate solution and foamed at room temperature to prepare hyperboloid graphene oxide-carbon nanotube composite carbon foam.

[0040] 3) The graphene oxide-carbon nanotube composite carbon foam was chemically reduced using hydroiodic acid / acetic acid vapor at a temperature of 90℃ for 12 hours.

[0041] 4) High-temperature graphitization treatment: The temperature is increased to 3000℃ at a rate of 10℃ / min under high-purity argon gas and held for 2 hours to ensure that the graphitization process is fully completed.

[0042] 5) Compression tests were conducted on the prepared GA / CNT carbon foam using a compression testing machine. The results showed that after 10,000 cycles of 50% strain compression, the residual stress of the GA / CNT carbon foam was 85% of the initial stress, and the plastic deformation was 1%, indicating good elasticity.

[0043] Comparative Example 1

[0044] 1) Graphene oxide films were prepared by casting an aqueous dispersion of graphene oxide and then naturally dried.

[0045] 2) The dried membrane was immersed in a 1wt% hydrazine hydrate solution and foamed at room temperature to prepare hyperboloid graphene oxide carbon foam.

[0046] 3) The hyperboloid graphene oxide carbon foam was chemically reduced using hydroiodic acid / acetic acid vapor at a temperature of 90℃ for 12 hours.

[0047] 4) High-temperature graphitization treatment: Under high-purity argon gas, the temperature is increased at 10℃ / min to 3000℃ and held for 2 hours to ensure that the graphitization process is fully completed.

[0048] 5) Compression tests were conducted on the prepared pure GA carbon foam using a compression testing machine. It was found that the foam could not recover after one 50% strain compression and lacked elasticity.

[0049] Comparative Example 2

[0050] 1) Graphene oxide aqueous dispersion and carbon nanotube aqueous dispersion were mixed at a mass ratio of 19:1. After being thoroughly mixed in a homogenizer, graphene oxide-carbon nanotube composite films were prepared by casting and then naturally dried.

[0051] 2) The dried membrane was immersed in a 1wt% hydrazine hydrate solution and foamed at room temperature to prepare hyperboloid graphene oxide-carbon nanotube composite carbon foam.

[0052] 3) The graphene oxide-carbon nanotube composite carbon foam was chemically reduced using hydroiodic acid / acetic acid vapor at a temperature of 90℃ for 12 hours.

[0053] 4) The prepared carbon foam has not undergone graphitization treatment, so it cannot form a graphite lattice structure. It has many defects, poor stability, and low thermal conductivity. It will collapse under pressure at 2000℃ and cannot be used as a high-temperature thermal interface material. However, the material prepared by this invention, after graphitization post-treatment, originally exhibits plasticity due to the weak interlayer van der Waals forces, which easily cause slippage between graphite sheets. By introducing carbon nanotubes, while ensuring that the hyperboloid carbon foam forms a highly repaired graphite lattice after graphitization treatment, the carbon nanotubes form anchoring points between graphite sheets, producing a pinning effect. This can effectively inhibit the slippage of graphite crystal sheets, maintain the good elasticity of the hyperboloid carbon foam, and make it suitable for use as a high-temperature thermal interface material.

[0054] 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 carbon nanotube / graphene composite hyperboloid graphite carbon foam, characterized in that, It includes the following steps: (1) A carbon nanotube solution and a graphene oxide aqueous dispersion are uniformly mixed, dried into a film by a scraper coating method, and then immersed in a foaming agent. The film is foamed at room temperature to obtain a carbon nanotube / graphene oxide hyperboloid composite carbon foam. The mass ratio of graphene oxide to carbon nanotube is greater than 4:

1. The foaming agent is a 1wt% hydrazine hydrate solution. (2) Carbon nanotube / graphene hyperboloid composite carbon foam was obtained by chemical reduction of carbon nanotube / graphene hyperboloid composite carbon foam; (3) The carbon nanotube / graphene hyperboloid composite carbon foam was heated at 3000℃ for 2h to perform graphitization treatment, and carbon nanotube / graphene composite hyperboloid graphite carbon foam was obtained.

2. The method according to claim 1, characterized in that, The chemical reduction in step 2 uses hydroiodic acid and acetic acid in a mass ratio of 1:3, at a temperature of 90°C, for a time of 12 hours.

3. The method according to claim 1, characterized in that, The heating rate in step 3 is 10℃ / min.

4. A carbon nanotube / graphene composite hyperboloid graphite carbon foam prepared by the method described in claim 1, characterized in that, Carbon nanotubes form anchor points between graphite sheets, creating a pinning effect.

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