High-thermal-conductivity pyrolytic graphite composite material, and preparation method and application thereof

Abstract

This invention relates to the field of lightweight porous carbon materials technology, and more particularly to a high thermal conductivity pyrolytic graphite composite material, its preparation method, and its applications. This invention uses mesophase pitch-based carbon foam as a three-dimensional porous framework and loose, high thermal conductivity carbon fiber cloth as a surface thermally conductive reinforcing phase. It does not use non-carbon phase bonding media such as resins or adhesives. The loose, high thermal conductivity carbon fiber cloth is directly bonded to the surface of the mesophase pitch-based carbon foam. Using chemical vapor deposition, pyrolytic graphite is deposited in situ on the surfaces of the mesophase pitch-based carbon foam and the loose, high thermal conductivity carbon fiber cloth, as well as at their interface. This forms a continuous carbonaceous bridging connection between the mesophase pitch-based carbon foam and the loose, high thermal conductivity carbon fiber cloth, achieving a stable, glue-free, integrated connection between them. Subsequently, graphitization annealing yields a high thermal conductivity pyrolytic graphite composite material that combines high in-plane thermal conductivity, relatively high out-of-plane thermal conductivity, and good interfacial stability.

Description

Technical Field

[0001] This invention relates to the field of lightweight porous carbon materials technology, and in particular to a high thermal conductivity pyrolytic graphite composite material, its preparation method, and its application. Background Technology

[0002] Pyrolytic graphite foam, as a novel lightweight porous carbon material, typically possesses an interconnected three-dimensional network framework structure internally, and its surface is deposited with a highly oriented pyrolytic graphite layer, resulting in a higher degree of graphitization and thus excellent mechanical properties and high thermal conductivity. As a high-performance thermal management framework material, pyrolytic graphite foam has attracted widespread attention in the past decade in fields such as military, aerospace, and electronic devices due to its high porosity, low density, low coefficient of thermal expansion, and excellent thermal conductivity.

[0003] Since the development of pyrolytic graphite foam, researchers have devoted considerable effort to studying high-quality pyrolytic graphite foam with extremely high in-plane and out-of-plane thermal conductivity and excellent structural stability. However, while carbon-based foams possess a three-dimensional framework and good heat transfer capabilities in the thickness direction, their rapid in-plane thermal diffusion capability remains insufficient. This is especially true in scenarios requiring rapid heat homogenization, in-plane thermal diffusion, and localized heat flow dissipation, where traditional pyrolytic graphite foams struggle to simultaneously achieve high in-plane and high thickness-direction thermal conductivity. High thermal conductivity carbon fiber cloth possesses excellent in-plane thermal conductivity and can serve as a highly efficient thermally conductive surface layer material, exhibiting significant advantages in in-plane thermal diffusion, heat flow spreading, and surface reinforcement. However, when carbon fiber cloth is used alone, its thickness-direction thermal conductivity is limited, and it lacks an effective supporting core layer and interfacial heat transfer pathways, making it difficult to fully leverage its thermal conductivity advantages in composite thermal management structures. Therefore, combining a three-dimensional carbon foam framework with two-dimensional high thermal conductivity carbon fiber cloth holds promise for constructing lightweight, high thermal conductivity sandwich structure materials that combine synergistic in-plane and out-of-plane thermal conductivity.

[0004] Typically, the composite of foam materials with fiber fabrics or layered reinforcements relies on resins, adhesives, or other organic compounds to achieve interlayer bonding. However, the above bonding methods have significant shortcomings: first, the organic adhesive layer itself has low thermal conductivity, which easily leads to thermal resistance at the interface; second, the organic phase is prone to decomposition in high-temperature environments, making it difficult to meet high-temperature thermal management requirements; and third, the introduction of a non-carbon phase adhesive layer is not conducive to subsequent ultra-high temperature graphitization treatment and can easily lead to complex interface composition and thermal expansion mismatch, thereby affecting the long-term stability and structural integrity of the material. Summary of the Invention

[0005] In view of this, the present invention provides a high thermal conductivity pyrolytic graphite composite material, its preparation method and application. The high thermal conductivity pyrolytic graphite composite material provided by the present invention does not introduce non-carbon phase bonding media such as resins and adhesives, and has high in-plane thermal conductivity, relatively high out-of-plane thermal conductivity and good interface stability.

[0006] This invention provides a high thermal conductivity pyrolytic graphite composite material, comprising mesophase pitch-based carbon foam and loose high thermal conductivity carbon fiber cloth covering at least one side of the mesophase pitch-based carbon foam; the mesophase pitch-based carbon foam and the loose high thermal conductivity carbon fiber cloth are connected by pyrolytic graphite; the mesophase pitch-based carbon foam is graphitized carbon foam; the surface of the high thermal conductivity pyrolytic graphite composite material is covered with a pyrolytic graphite layer.

[0007] Preferably, the density of the mesophase pitch-based carbon foam is 0.36~0.6 g / cm³. 3 .

[0008] Preferably, the mesophase pitch-based carbon foam has a length of 8-10 mm, a width of 5-7 mm, and a thickness of 2.8-3.2 mm.

[0009] Preferably, the length and width of the loose, highly thermally conductive carbon fiber cloth are consistent with those of the mesophase pitch-based carbon foam.

[0010] Preferably, the thickness of the loose, highly thermally conductive carbon fiber cloth is 0.1~0.2mm.

[0011] Preferably, the loose high thermal conductivity carbon fiber cloth has a porosity of 49-51%; the warp / weft thermal conductivity of the loose high thermal conductivity carbon fiber cloth is 5-8 W / (m·K), and the Z thermal conductivity is 0.3-0.5 W / (m·K).

[0012] This invention also provides a method for preparing the high thermal conductivity pyrolytic graphite composite material described above, comprising the following steps: (1) After bonding the loose, high thermal conductivity carbon fiber cloth to the surface of the mesophase pitch-based carbon foam, fix it to obtain a preform; (2) The preform is subjected to chemical vapor deposition pyrolytic graphite followed by graphitization annealing to obtain the high thermal conductivity pyrolytic graphite composite material.

[0013] Preferably, the parameters for the chemical vapor deposition include: the carbon source is methane with a purity of 99.99% or higher; the load gas is argon with a purity of 99.99% or higher; the mass ratio of the carbon source to the load gas is 1:1.8~2.2; the furnace pressure is 0.23~0.27 kPa; the temperature is 1780~1820 degrees Celsius; and the deposition time is 6~8 days.

[0014] Preferably, the graphitization annealing temperature is 2990~3010 degrees Celsius, the vacuum degree is 480~520 Pa, and the holding time is 23~25 hours.

[0015] The present invention also provides the application of the high thermal conductivity pyrolytic graphite composite material described in the above-described scheme or the high thermal conductivity pyrolytic graphite composite material obtained by the preparation method described in the above-described scheme in the aerospace field or the electronic device field.

[0016] Compared with the prior art, the present invention has achieved the following beneficial effects: To address the problems of insufficient in-plane thermal conductivity, high interfacial thermal resistance, and the inability of traditional adhesive bonding methods to meet high-temperature resistance requirements in existing carbon-based porous materials, this invention uses mesophase pitch-based carbon foam as a three-dimensional porous framework and loose, highly thermally conductive carbon fiber cloth as a surface thermally conductive reinforcing phase. It avoids using non-carbon phase bonding media such as resins and adhesives. By directly bonding the loose, highly thermally conductive carbon fiber cloth to the surface of the mesophase pitch-based carbon foam, pyrolytic graphite is deposited in situ on the surfaces of the mesophase pitch-based carbon foam and the loose, highly thermally conductive carbon fiber cloth, as well as at their interface, using chemical vapor deposition. This creates a continuous carbonaceous bridging connection between the mesophase pitch-based carbon foam and the loose, highly thermally conductive carbon fiber cloth, achieving a stable, adhesive-free, integrated connection between them. Subsequent graphitization annealing yields a pyrolytic graphite foam material with high in-plane thermal conductivity, relatively high out-of-plane thermal conductivity, and good interfacial stability—a high thermal conductivity pyrolytic graphite composite material.

[0017] The high thermal conductivity pyrolytic graphite composite material provided by this invention constructs a "mesophase pitch-based carbon foam-loose high thermal conductivity carbon fiber cloth" sandwich structure without adhesive bonding. This avoids the problems of easy decomposition, easy failure, low thermal conductivity, and high interfacial thermal resistance of traditional organic adhesive layers under high temperature conditions. It significantly improves the thermal stability and thermal conductivity continuity of the sandwich structure interface, giving it excellent overall thermal conductivity. It has high in-plane thermal conductivity, relatively high out-of-plane thermal conductivity, low interfacial thermal resistance, and good interfacial stability, and also has high compressive strength.

[0018] This invention uses mesophase pitch-based carbon foam as a matrix, with loose, highly thermally conductive carbon fiber cloth laminated to its surface. Using methane as a carbon source, pyrolytic graphite is deposited on the surface of the mesophase pitch-based carbon foam, the surface of the loose, highly thermally conductive carbon fiber cloth, and at the interface between the mesophase pitch-based carbon foam and the loose, highly thermally conductive carbon fiber cloth via chemical vapor deposition. Subsequently, graphitization annealing is performed to obtain a high-thermal-conductivity pyrolytic graphite composite material. The preparation method provided by this invention utilizes widely available and inexpensive raw materials (such as mesophase pitch-based carbon foam and methane), has a clear synthetic route, simple and mature steps, is easy to control, and is convenient to operate, possessing the potential for industrial-scale production. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of this invention, the accompanying drawings used in the embodiments of this invention or in the prior art are briefly described below. For those skilled in the art, other drawings can be derived from the following drawings without creative effort, and all such drawings are within the protection scope of this invention.

[0020] Figure 1 This is a schematic diagram of chemical vapor deposition; Figure 2 X-ray diffraction patterns of the high thermal conductivity pyrolytic graphite composite materials prepared in Examples 1-4; Figure 3 SEM images of the high thermal conductivity pyrolytic graphite composites prepared in Examples 1-4 are shown below. Specifically, (a1)-(a2) are SEM images of the high thermal conductivity pyrolytic graphite composite prepared in Example 1, with scale bars of 500 μm and 50 μm respectively; (b1)-(b2) are SEM images of the high thermal conductivity pyrolytic graphite composite prepared in Example 2, with scale bars of 500 μm and 50 μm respectively; (c1)-(c2) are SEM images of the high thermal conductivity pyrolytic graphite composite prepared in Example 3, with scale bars of 500 μm and 20 μm respectively; and (d1)-(d2) are SEM images of the high thermal conductivity pyrolytic graphite composite prepared in Example 4, with scale bars of 500 μm and 20 μm respectively. Figure 4 The thermal conductivity properties of the high thermal conductivity pyrolytic graphite composites prepared in Examples 1-4 are shown in the diagram. Figure 5 The stress-strain curves of the high thermal conductivity pyrolytic graphite composite materials prepared in Examples 1 to 4 are shown below. Among them, (a) is the stress-strain curve of the high thermal conductivity pyrolytic graphite composite material prepared in Example 1, (b) is the stress-strain curve of the high thermal conductivity pyrolytic graphite composite material prepared in Example 2, (c) is the stress-strain curve of the high thermal conductivity pyrolytic graphite composite material prepared in Example 3, and (d) is the stress-strain curve of the high thermal conductivity pyrolytic graphite composite material prepared in Example 4. Detailed Implementation

[0021] This invention provides a high thermal conductivity pyrolytic graphite composite material, comprising mesophase pitch-based carbon foam and loose high thermal conductivity carbon fiber cloth covering at least one side of the mesophase pitch-based carbon foam; the mesophase pitch-based carbon foam and the loose high thermal conductivity carbon fiber cloth are connected by pyrolytic graphite; the mesophase pitch-based carbon foam is graphitized carbon foam; the surface of the high thermal conductivity pyrolytic graphite composite material is covered with a pyrolytic graphite layer.

[0022] In this invention, the density of the mesophase pitch-based carbon foam is preferably 0.36~0.6 g / cm³. 3 More preferably, it is 0.4~0.5 g / cm³. 3 .

[0023] In this invention, the length of the mesophase pitch-based carbon foam is preferably 8-10 mm, more preferably 9 mm, the width is preferably 5-7 mm, more preferably 6 mm, and the thickness is preferably 2.8-3.2 mm, more preferably 3 mm.

[0024] In a specific embodiment of the present invention, the mesophase pitch-based carbon foam is pitch synthesized from naphthalene using HF / BF3 catalysis by Huaqiao University.

[0025] In this invention, the length and width of the loose, high thermal conductivity carbon fiber cloth are preferably consistent with those of the mesophase pitch-based carbon foam, which will not be elaborated here; the thickness of the loose, high thermal conductivity carbon fiber cloth is preferably 0.1~0.2mm, more preferably 0.13mm.

[0026] In this invention, the looseness of the loose high thermal conductivity carbon fiber cloth is preferably 49-51%, the warp / weft (XY direction, in-plane) thermal conductivity (λ) of the loose high thermal conductivity carbon fiber cloth is preferably 5-8 W / (m·K), more preferably 6-7 W / (m·K), and the Z thermal conductivity is preferably 0.3-0.5 W / (m·K), more preferably 0.4 W / (m·K).

[0027] In this invention, the loose, high thermal conductivity carbon fiber cloth is preferably T300 carbon fiber cloth from Toray Industries, Japan. The loose, high thermal conductivity carbon fiber cloth used in this invention has a loose structure, which facilitates the entry of deposition gas into the fiber layer and the formation of deposition bridging structures in the interface region.

[0028] This invention also provides a method for preparing the high thermal conductivity pyrolytic graphite composite material described above, comprising the following steps: (1) After bonding the loose, high thermal conductivity carbon fiber cloth to the surface of the mesophase pitch-based carbon foam, fix it to obtain a preform; (2) The preform is subjected to chemical vapor deposition pyrolytic graphite followed by graphitization annealing to obtain the high thermal conductivity pyrolytic graphite composite material.

[0029] This invention involves bonding a loose, highly thermally conductive carbon fiber cloth to the surface of a mesophase pitch-based carbon foam and then fixing it to obtain a preform. In this invention, the fixing is preferably achieved using a long-tail clip for slight clamping. This invention constructs a sandwich composite structure of loose, highly thermally conductive carbon fiber cloth and mesophase pitch-based carbon foam by bonding the loose, highly thermally conductive carbon fiber cloth to the upper surface of the mesophase pitch-based carbon foam. The slight clamping and fixing with a long-tail clip ensures sufficient contact between the surfaces of the loose, highly thermally conductive carbon fiber cloth and the mesophase pitch-based carbon foam, while preserving the loose structure of the mesophase pitch-based carbon foam.

[0030] After obtaining the preform, the present invention performs chemical vapor deposition (CVD) on the preform followed by graphitization annealing to obtain the high thermal conductivity pyrolytic graphite composite material. In the present invention, the preferred parameters for the CVD include: the carbon source is methane with a purity of 99.99% or higher; the load gas is argon with a purity of 99.99% or higher; the mass ratio of the carbon source to the load gas is 1:1.8~2.2, more preferably 1:2; the furnace pressure is 0.23~0.27 kPa, more preferably 0.25 kPa; the temperature is 1780~1820 degrees Celsius, more preferably 1800 degrees Celsius; and the deposition time is 6~8 days, more preferably 7 days.

[0031] This invention utilizes chemical vapor deposition to deposit pyrolytic graphite on the surface of the carbon fibers of a loose, high thermal conductivity carbon fiber cloth, the surface of the three-dimensional skeleton of the mesophase pitch-based carbon foam, and the contact area between the mesophase pitch-based carbon foam and the loose, high thermal conductivity carbon fiber cloth. As the chemical vapor deposition process proceeds, a continuous pyrolytic graphite bonding layer and bridging structure gradually form between the mesophase pitch-based carbon foam and the loose, high thermal conductivity carbon fiber cloth, thereby achieving in-situ bonding between the mesophase pitch-based carbon foam and the loose, high thermal conductivity carbon fiber cloth.

[0032] In this invention, the process of graphitizing annealing preferably includes cooling the resulting product in the furnace.

[0033] In this invention, the graphitization annealing temperature is preferably 2990~3010 degrees Celsius, more preferably 3000 degrees Celsius, the vacuum degree is preferably 480~520 Pa, more preferably 500 Pa, and the holding time is preferably 23~25 hours, more preferably 24 hours.

[0034] In this invention, the graphitization annealing process preferably further includes cooling the resulting product to room temperature.

[0035] The present invention also provides the application of the high thermal conductivity pyrolytic graphite composite material described in the above-described scheme or the high thermal conductivity pyrolytic graphite composite material obtained by the preparation method described in the above-described scheme in the aerospace field or the electronic device field.

[0036] The high thermal conductivity pyrolytic graphite composite material provided by this invention does not introduce non-carbon phase bonding media such as resins and adhesives, and has high in-plane thermal conductivity, relatively high out-of-plane thermal conductivity and good interface stability, making it suitable for use in the aerospace or electronic device fields.

[0037] To further illustrate the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments.

[0038] Example 1: (1) The density (0.36 g / cm³) 3The mesophase pitch-based carbon foam (HF / BF3 catalytic naphthalene synthesis pitch from Huaqiao University) was cut to a size of 9mm×6mm×3mm and used as a template for chemical vapor deposition.

[0039] (2) Cut the loose, high thermal conductivity carbon fiber cloth (Toray T300 from Japan) to match the surface size of the mesophase pitch-based carbon foam, specifically 9 mm × 6 mm, as the surface material.

[0040] (3) The cut loose high thermal conductivity carbon fiber cloth is attached to the upper surface of the mesophase pitch-based carbon foam to construct a sandwich composite structure of loose high thermal conductivity carbon fiber cloth-mesophase pitch-based carbon foam. It is lightly clamped and fixed with long tail clips so that the surfaces of loose high thermal conductivity carbon fiber cloth and mesophase pitch-based carbon foam can maintain sufficient contact without damaging the loose structure of mesophase pitch-based carbon foam, thus obtaining a preform.

[0041] (4) such as Figure 1 As shown, the preform was placed in a chemical vapor deposition pyrolysis furnace. High-purity (99.99%) methane was used as the carbon source, and high-purity (99.99%) argon was used as the load gas. The mass flow rate ratio of methane to argon was set to 1:2, and the furnace pressure was controlled at 0.25 kPa. Deposition was carried out at 1800 degrees Celsius for 7 days.

[0042] (5) After deposition, the preform of pyrolytic graphite was cooled in the furnace and transferred to a graphitization furnace for graphitization annealing at 3000°C and 500 Pa for 24 hours. After cooling to room temperature, it was removed to obtain a high thermal conductivity pyrolytic graphite composite material, designated PGF-1, with a density of 0.46 g / cm³. 3 .

[0043] Example 2: (1) The density (0.40 g / cm³) 3 The mesophase pitch-based carbon foam (HF / BF3 catalytic naphthalene synthesis pitch from Huaqiao University) was cut to a size of 9mm×6mm×3mm and used as a template for chemical vapor deposition.

[0044] (2) Cut the loose, high thermal conductivity carbon fiber cloth (Toray T300 from Japan) to match the surface size of the mesophase pitch-based carbon foam, specifically 9 mm × 6 mm, as the surface material.

[0045] (3) The cut loose high thermal conductivity carbon fiber cloth is attached to the upper surface of the mesophase pitch-based carbon foam to construct a sandwich composite structure of loose high thermal conductivity carbon fiber cloth-mesophase pitch-based carbon foam. It is lightly clamped and fixed with long tail clips so that the surfaces of loose high thermal conductivity carbon fiber cloth and mesophase pitch-based carbon foam can maintain sufficient contact without damaging the loose structure of mesophase pitch-based carbon foam, thus obtaining a preform.

[0046] (4) such as Figure 1 As shown, the preform was placed in a chemical vapor deposition pyrolysis furnace. High-purity (99.99%) methane was used as the carbon source, and high-purity (99.99%) argon was used as the load gas. The mass flow rate ratio of methane to argon was set to 1:2, and the furnace pressure was controlled at 0.25 kPa. Deposition was carried out at 1800 degrees Celsius for 7 days.

[0047] (5) After deposition, the preform of pyrolytic graphite was cooled in the furnace and transferred to a graphitization furnace for graphitization annealing at 3000°C and 500 Pa for 24 hours. After cooling to room temperature, it was removed to obtain a high thermal conductivity pyrolytic graphite composite material, denoted as PGF-2, with a density of 0.55 g / cm³. 3 .

[0048] Example 3: (1) The density (0.50 g / cm³) 3 The mesophase pitch-based carbon foam (HF / BF3 catalytic naphthalene synthesis pitch from Huaqiao University) was cut to a size of 9mm×6mm×3mm and used as a template for chemical vapor deposition.

[0049] (2) Cut the loose, high thermal conductivity carbon fiber cloth (Toray T300 from Japan) to match the surface size of the mesophase pitch-based carbon foam, specifically 9 mm × 6 mm, as the surface material.

[0050] (3) The cut loose high thermal conductivity carbon fiber cloth is attached to the upper surface of the mesophase pitch-based carbon foam to construct a sandwich composite structure of loose high thermal conductivity carbon fiber cloth-mesophase pitch-based carbon foam. It is lightly clamped and fixed with long tail clips so that the surfaces of loose high thermal conductivity carbon fiber cloth and mesophase pitch-based carbon foam can maintain sufficient contact without damaging the loose structure of mesophase pitch-based carbon foam, thus obtaining a preform.

[0051] (4) such as Figure 1 As shown, the preform was placed in a chemical vapor deposition pyrolysis furnace. High-purity (99.99%) methane was used as the carbon source, and high-purity (99.99%) argon was used as the load gas. The mass flow rate ratio of methane to argon was set to 1:2, and the furnace pressure was controlled at 0.25 kPa. Deposition was carried out at 1800 degrees Celsius for 7 days.

[0052] (5) After deposition, the preform of pyrolytic graphite was cooled in the furnace and transferred to a graphitization furnace for graphitization annealing at 3000°C and 500 Pa for 24 hours. After cooling to room temperature, it was removed to obtain a high thermal conductivity pyrolytic graphite composite material, designated PGF-3, with a density of 0.69 g / cm³. 3 .

[0053] Example 4: (1) The density (0.60 g / cm³) 3 The mesophase pitch-based carbon foam (HF / BF3 catalytic naphthalene synthesis pitch from Huaqiao University) was cut to a size of 9mm×6mm×3mm and used as a template for chemical vapor deposition.

[0054] (2) Cut the loose, high thermal conductivity carbon fiber cloth (Toray T300 from Japan) to match the surface size of the mesophase pitch-based carbon foam, specifically 9 mm × 6 mm, as the surface material.

[0055] (3) The cut loose high thermal conductivity carbon fiber cloth is attached to the upper surface of the mesophase pitch-based carbon foam to construct a sandwich composite structure of loose high thermal conductivity carbon fiber cloth-mesophase pitch-based carbon foam. It is lightly clamped and fixed with long tail clips so that the surfaces of loose high thermal conductivity carbon fiber cloth and mesophase pitch-based carbon foam can maintain sufficient contact without damaging the loose structure of mesophase pitch-based carbon foam, thus obtaining a preform.

[0056] (4) such as Figure 1 As shown, the preform was placed in a chemical vapor deposition pyrolysis furnace. High-purity (99.99%) methane was used as the carbon source, and high-purity (99.99%) argon was used as the load gas. The mass flow rate ratio of methane to argon was set to 1:2, and the furnace pressure was controlled at 0.25 kPa. Deposition was carried out at 1800 degrees Celsius for 7 days.

[0057] (5) After deposition, the preform of pyrolytic graphite was cooled in the furnace and transferred to a graphitization furnace for graphitization annealing at 3000°C and 500 Pa for 24 hours. After cooling to room temperature, it was removed to obtain a high thermal conductivity pyrolytic graphite composite material, designated PGF-4, with a density of 0.75 g / cm³. 3 .

[0058] Test Example 1: The performance of the high thermal conductivity pyrolytic graphite composite materials prepared in Examples 1-4 was tested using X-ray diffraction (XRD). The results are as follows: Figure 2 As shown.

[0059] according to Figure 2 It can be seen that the XRD characteristic peaks of the high thermal conductivity pyrolytic graphite composite material are consistent with the characteristic peaks of the graphite standard spectrum, indicating that the prepared high thermal conductivity pyrolytic graphite composite material meets the expected target.

[0060] Test Example 2: The high thermal conductivity pyrolytic graphite composite materials prepared in Examples 1-4 were subjected to performance testing. The testing method was as follows: the structure was characterized using scanning electron microscopy to further confirm that the structure met the expected target. The results are as follows. Figure 3 As shown.

[0061] according to Figure 3 It can be seen that chemical vapor deposition has a significant regulatory effect on the microstructure of mesophase pitch-based carbon foam.

[0062] Test Example 3: The performance of the high thermal conductivity pyrolytic graphite composite materials prepared in Examples 1-4 was tested. The test method was as follows: the high thermal conductivity pyrolytic graphite composite materials prepared in Examples 1-4 were prepared into Φ13mm×6mm circular samples. The laser scintillation method was used, and the laser thermal conductivity meter was used to measure the samples three times in an argon atmosphere at room temperature. The average value was taken and the results were calculated according to the formula. The thermal conductivity was calculated, and the results are as follows: Figure 4 As shown.

[0063] according to Figure 4 It can be seen that in both the XY and Z directions, the thermal conductivity of the high thermal conductivity pyrolytic graphite composite material increases with the increase of the density after deposition (as the density of the mesophase pitch-based carbon foam used in preparation increases). All high thermal conductivity pyrolytic graphite composite materials exhibit significant anisotropy, with the thermal conductivity in the Z direction being higher than that in the XY direction. Due to the graphitized structure of the pore walls, heat is conducted along the graphite sheets in the Z direction due to the stacking of pore walls, resulting in low conduction loss. In the XY direction, the pores are dense, requiring heat conduction to pass through the pore wall and pore interface, significantly reducing thermal conductivity efficiency due to the porosity.

[0064] Test Example 4: The performance of the high thermal conductivity pyrolytic graphite composite materials prepared in Examples 1-4 was tested. The testing method was as follows: samples of the high thermal conductivity pyrolytic graphite composite materials prepared in Examples 1-4 were taken, prepared, and processed into cylindrical samples with a diameter of Φ15mm × 30mm. The densities of the cylindrical samples prepared in Examples 1-4 were 0.43g / cm³, respectively. 3 0.50g / cm 3 0.63g / cm 3 and 0.73g / cm 3Using an electronic universal testing machine, pressure was applied at a compression rate of 0.1 mm / min, and stress-strain curves were recorded. A mesophase pitch-based carbon foam (without deposited pyrolytic graphite) of similar density was used as a control, with a density of 0.48 g / cm³. 3 0.53g / cm 3 0.63g / cm 3 and 0.74 g / cm 3 The result is as follows Figure 5 As shown.

[0065] according to Figure 5 It can be seen that, comparing the compressive properties of mesophase pitch-based carbon foam and high thermal conductivity pyrolytic graphite composites with four different densities, the compressive strength of the mesophase pitch-based carbon foam after chemical vapor deposition is significantly greater, indicating that chemical vapor deposition effectively improves the compressive strength of the high thermal conductivity pyrolytic graphite composite.

[0066] The embodiments of the present invention have been described above; however, these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. All other embodiments obtained by those skilled in the art based on the above embodiments of the present invention without inventive effort are within the protection scope of the present invention.

Claims

1. A high thermal conductivity pyrolytic graphite composite material, characterized in that, Includes mesophase pitch-based carbon foam and loose, highly thermally conductive carbon fiber cloth covering at least one side of the mesophase pitch-based carbon foam; The mesophase pitch-based carbon foam and the loose, highly thermally conductive carbon fiber cloth are connected by pyrolytic graphite. The mesophase pitch-based carbon foam is graphitized carbon foam; The surface of the high thermal conductivity pyrolytic graphite composite material is covered with a pyrolytic graphite layer.

2. The high thermal conductivity pyrolytic graphite composite material according to claim 1, characterized in that, The density of the mesophase pitch-based carbon foam is 0.36~0.6 g / cm³. 3 .

3. The high thermal conductivity pyrolytic graphite composite material according to claim 1, characterized in that, The mesophase pitch-based carbon foam has a length of 8-10 mm, a width of 5-7 mm, and a thickness of 2.8-3.2 mm.

4. The high thermal conductivity pyrolytic graphite composite material according to claim 1, characterized in that, The length and width of the loose, highly thermally conductive carbon fiber cloth are consistent with those of the mesophase pitch-based carbon foam.

5. The high thermal conductivity pyrolytic graphite composite material according to claim 1, characterized in that, The thickness of the loose, high thermal conductivity carbon fiber cloth is 0.1~0.2mm.

6. The high thermal conductivity pyrolytic graphite composite material according to claim 1, characterized in that, The porous, high thermal conductivity carbon fiber cloth has a porosity of 49-51%. The loose, high thermal conductivity carbon fiber cloth has a warp / weft thermal conductivity of 5~8 W / (m·K) and a Z-direction thermal conductivity of 0.3~0.5 W / (m·K).

7. A method for preparing a high thermal conductivity pyrolytic graphite composite material, characterized in that, The high thermal conductivity pyrolytic graphite composite material is the high thermal conductivity pyrolytic graphite composite material according to any one of claims 1 to 6, and includes the following steps: (1) After bonding the loose, high thermal conductivity carbon fiber cloth to the surface of the mesophase pitch-based carbon foam, fix it to obtain a preform; (2) The preform is subjected to chemical vapor deposition pyrolytic graphite followed by graphitization annealing to obtain the high thermal conductivity pyrolytic graphite composite material.

8. The method for preparing the high thermal conductivity pyrolytic graphite composite material according to claim 7, characterized in that, The parameters for the chemical vapor deposition include: The carbon source is methane, and the purity of the methane is above 99.99%. The load gas is argon, and the purity of the argon is above 99.99%; The mass ratio of the carbon source to the load gas is 1:1.8~2.2; The furnace pressure is 0.23~0.27 kPa; The temperature is 1780~1820 degrees Celsius; The deposition time is 6 to 8 days.

9. The method for preparing the high thermal conductivity pyrolytic graphite composite material according to claim 7, characterized in that, The graphitization annealing temperature is 2990~3010 degrees Celsius, the vacuum degree is 480~520 Pa, and the holding time is 23~25 hours.

10. An application of a high thermal conductivity pyrolytic graphite composite material in the aerospace or electronic device fields, characterized in that, The high thermal conductivity pyrolytic graphite composite material is the high thermal conductivity pyrolytic graphite composite material according to any one of claims 1 to 6 or the high thermal conductivity pyrolytic graphite composite material obtained by the preparation method according to any one of claims 7 to 9.

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