Modified graphene paper / carbon fiber slurry composite heat-conducting wave-absorbing material and preparation method thereof
By combining modified graphene paper with carbon fiber slurry to form a wound structure, the thermal failure problem of terahertz absorbing materials is solved, achieving a combination of high thermal conductivity and high absorption performance. This is suitable for fields such as electromagnetic shielding, wireless communication, security imaging, radar detection, atmospheric remote sensing, and astronomical exploration.
Patent Information
- Application Number
- CN202511719617.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-21
- Publication Date
- 2026-02-24
AI Technical Summary
Existing terahertz absorbing materials suffer from insufficient thermal diffusion performance and poor thermal stability, failing to effectively address the problem of material performance degradation or failure caused by heat accumulation from high-power microwaves.
The method employs a composite of modified graphene paper and carbon fiber slurry. The graphene paper is modified by a polyurethane and graphene aerogel coating to form a wound structure. The graphene paper provides thermal conductivity, the graphene aerogel provides microwave absorption, and the carbon fiber slurry fills the gaps between the layers. Combined with polyurethane, it provides support and curing, thus achieving the integration of thermal conductivity and microwave absorption.
It achieves a combination of high thermal conductivity and high wave absorption performance. By utilizing the thermal conductivity of graphene paper and the porous structure of graphene aerogel, the transmission path of electromagnetic waves is extended, electromagnetic loss is enhanced, and the wave absorption and thermal conductivity performance can be controlled by adjusting the coating thickness to avoid thermal failure.
Smart Images
Figure CN121555154A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of terahertz microwave absorption technology, specifically providing a modified graphene paper / carbon fiber slurry composite thermally conductive microwave absorbing material and its preparation method. Background Technology
[0002] With the rapid development of millimeter-wave and terahertz technologies, the demand for absorbing materials for various applications is increasing, particularly in electromagnetic shielding, wireless communication, security imaging, radar detection, atmospheric remote sensing, and astronomical exploration, where they have demonstrated significant application value. As application scenarios deepen, the demand for terahertz absorbing materials in different environments is also growing. However, existing terahertz absorbing materials often suffer from insufficient thermal diffusion performance and poor thermal stability, failing to address the problem of heat accumulation leading to material performance degradation or even failure under high-power microwave conditions. Therefore, developing terahertz absorbing materials with high thermal conductivity, high absorption, and thermally stable structures has become an important research direction in the field of terahertz absorbing technology.
[0003] Microwave absorbing materials are typically made primarily of polymer composites, prepared as absorbing blocks, foams, or films. These structures offer advantages such as ease of fabrication, low cost, and excellent absorption performance. However, due to the poor thermal conductivity of polymers, the absorbed electromagnetic energy is converted into heat energy and remains inside the absorber. When the accumulated heat energy reaches a certain level, it can cause material loss or even damage. Two-dimensional graphene paper, which relies on phonon mode heat transfer, possesses extremely high thermal conductivity. However, because graphene has strong reflective properties, directly using it as a microwave absorbing material often results in high reflectivity and low absorptivity. Therefore, combining the advantages of both, this invention focuses on developing a microwave absorbing material that combines thermal conductivity and microwave absorption properties by modifying graphene paper. By incorporating the high thermal conductivity of graphene paper, the absorption of electromagnetic waves and the transfer of electromagnetic heat can be achieved, thus avoiding thermal failure problems. Summary of the Invention
[0004] The purpose of this invention is to provide a modified graphene paper / carbon fiber slurry composite thermally conductive and microwave absorbing material and its preparation method, to solve the problems of thermal accumulation and thermal failure in existing microwave absorbing materials. This invention uses graphene paper modified with polyurethane and graphene aerogel coatings, rolled into a cylindrical shape, and fills the gaps between the graphene paper layers with carbon fiber slurry. The graphene aerogel provides microwave absorption properties, the graphene paper and carbon fiber provide thermal conductivity, and the polyurethane and epoxy resin provide support and curing, ultimately achieving a multifunctional material integrating microwave absorption and thermal conductivity.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0006] A modified graphene paper / carbon fiber slurry composite thermally conductive and microwave absorbing material is characterized in that the composite thermally conductive and microwave absorbing material comprises modified graphene paper and carbon fiber slurry; the modified graphene paper is in a wound shape, and when unfolded, the single-layer structure consists of graphene paper and a graphene aerogel coating coated on the inner side of the graphene paper; the carbon fiber slurry fills the spaces between adjacent single-layer structures of the wound modified graphene paper.
[0007] Furthermore, the thickness of the graphene paper is 10μm~200μm, preferably 25μm~50μm; the thickness of the graphene aerogel coating is 60μm~500μm.
[0008] Furthermore, the gap between adjacent monolayer structures of the modified graphene paper is 60μm~600μm.
[0009] Furthermore, the carbon fiber slurry is composed of carbon fiber and epoxy resin, wherein the mass percentage of carbon fiber is 15wt%~25wt%.
[0010] Furthermore, the graphene aerogel coating is composed of polyurethane and graphene aerogel particles, wherein the mass percentage of the graphene aerogel particles is 1.5wt% to 2.5wt%.
[0011] Furthermore, the particle size of graphene aerogel particles is 150μm~270μm (100 mesh~50 mesh).
[0012] Furthermore, the preparation method of the modified graphene paper / carbon fiber slurry composite thermally conductive and microwave absorbing material is characterized by comprising the following steps:
[0013] S1: Cut the graphene paper into strips of a preset size, apply the graphene aerogel slurry onto the graphene paper and dry it. Repeat the application multiple times to reach the preset thickness to obtain the modified graphene paper.
[0014] S2: The modified graphene paper is wound into a cylindrical shape. The cylindrical shape is placed in a mold and carbon fiber slurry is injected so that the carbon fiber slurry completely submerges the cylindrical shape. Then, the carbon fiber slurry is filled into the interlayer gaps of the cylindrical shape through vacuum treatment.
[0015] S3: Heat and cure the impregnated cylindrical roll and cut it into shape.
[0016] Furthermore, in step S1, the graphene paper has a width of 6mm~10mm and a length of 400mm; the specific drying process is as follows: dry at 80℃ for 1h~2h on a constant temperature heating table, and then completely dry after cooling.
[0017] Furthermore, in step S2, the specific process of vacuum treatment is as follows: let it stand for 1 to 3 hours in an environment with a vacuum degree of -1.0 MPa to 0.01 MPa.
[0018] Furthermore, in step S3, the specific process of heating and curing is as follows: in an environment with a vacuum degree of -1.0MPa to 0.01MPa, the curing temperature is set to 60℃ to 80℃, and the curing time is 2h to 5h.
[0019] Furthermore, in step S3, the specific process of cutting and forming is as follows: cutting the cylindrical coil into sheets along its circular cross-section to obtain a composite thermally conductive and wave-absorbing material; preferably, the cutting is done by wire cutting, blade cutting, or cryogenic cutting; preferably, the thickness of the sheet is 1mm to 5mm, and more preferably 2mm to 3mm.
[0020] In terms of working principle:
[0021] Graphene paper possesses excellent thermal conductivity and reflectivity but poor microwave absorption, while graphene aerogel exhibits excellent microwave absorption but poor thermal conductivity. Therefore, a composite thermally conductive and microwave-absorbing roll structure is achieved by combining graphene paper and graphene aerogel. Utilizing the thermal conductivity of epoxy resin and carbon fiber composite materials, the advantages of both thermal conductivity and microwave absorption can be combined. The thickness and spacing of the microwave-absorbing layer and the thermally conductive layer can be controlled by adjusting the thickness of the polyurethane and graphene aerogel coating. The graphene paper layer, acting as a thermally conductive layer, conducts and diffuses the heat generated by the electromagnetic loss of the microwave-absorbing layer to the surface of the absorber. The microwave-absorbing layer, through the combined effects of the porosity and loss properties of the graphene aerogel, attenuates the incident electromagnetic waves and converts them into heat energy. Simultaneously, the graphene paper layers on both sides of the microwave-absorbing layer and the graphene inside cause multiple reflections of the incident electromagnetic waves, extending the transmission path and enhancing electromagnetic loss.
[0022] In summary, the beneficial effects of the present invention are as follows:
[0023] This invention proposes a composite thermally conductive and microwave-absorbing material. It utilizes a highly thermally conductive graphene paper roll structure to provide a heat conduction channel for the heat energy generated by electromagnetic loss. At the same time, the graphene aerogel allows the incident electromagnetic waves to be reflected multiple times within the microwave-absorbing layer, extending the propagation path and enhancing the loss of electromagnetic waves. Furthermore, the thickness of the microwave-absorbing layer can be adjusted according to the thickness of the polyurethane graphene aerogel coating to achieve different microwave absorption and thermal conductivity requirements, resulting in a novel microwave-absorbing material that combines thermal conductivity and microwave absorption properties. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of the structure of the modified graphene paper / carbon fiber slurry composite thermally conductive and microwave absorbing material in an embodiment of the present invention.
[0025] Figure 2This is a physical image of the modified graphene paper / carbon fiber slurry composite thermally conductive and microwave-absorbing material in an embodiment of the present invention.
[0026] Figure 3 The figure shows the terahertz performance test results of the modified graphene paper in the embodiments of the present invention.
[0027] Figure 4 The figure shows the terahertz absorption performance test results of composite thermally conductive and microwave absorbing materials with multiple thicknesses of graphene aerogel coatings in the embodiments of the present invention.
[0028] Figure 5 The graph shows the thermal conductivity test results of composite thermally conductive and microwave absorbing materials with multiple thicknesses of graphene aerogel coatings in this embodiment of the invention. Detailed Implementation
[0029] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.
[0030] This embodiment provides a modified graphene paper / carbon fiber slurry composite thermally conductive and microwave absorbing material and its preparation method. The composite thermally conductive and microwave absorbing material is as follows: Figure 1 As shown, it specifically includes: modified graphene paper and carbon fiber slurry; the modified graphene paper is in a wound shape (similar to a cylindrical paper roll), and when unfolded, the single-layer structure consists of graphene paper and a graphene aerogel coating coated on the inner side of the graphene paper; the carbon fiber slurry fills the spaces between adjacent single-layer structures of the wound modified graphene paper.
[0031] The preparation process of the composite thermally conductive and microwave absorbing material mainly includes: preparation of carbon fiber slurry, preparation of graphene aerogel coating, and filling of carbon fiber slurry; specifically as follows:
[0032] The carbon fiber slurry is prepared by the following steps:
[0033] First, use a clean beaker and electronic scale to take 6g of epoxy resin soft glue; use weighing paper and electronic scale to take 1.2g of carbon fiber; mix the two together and stir at 600rpm~700rpm for 10min~30min until uniformly mixed.
[0034] Then, weigh 2g of epoxy resin curing agent into a clean beaker, pour it into the mixture obtained in step 1, and stir at 600rpm~700rpm for 5min~10min until uniformly mixed.
[0035] Finally, let it stand at room temperature for 5 to 10 minutes to complete the defoaming process. Once the bubbles have dissipated, a black gel-like material is obtained, which is the carbon fiber slurry.
[0036] The graphene aerogel coating is prepared by the following steps:
[0037] First, the 8 mg / ml graphene oxide solution prepared by the Hummers method was frozen at -18℃ for 7 h to form a graphene aerogel block, and then freeze-dried for 48 h to obtain a graphene aerogel block. A graphene aerogel block larger than 0.5 g was placed in a mortar and crushed, and particles of 50-100 mesh size were screened through a sieve. 0.1 g of graphene aerogel particles were placed in a clean beaker, and 5 g of waterborne polyurethane was added using a dropper. After mixing the two, the mixture was stirred at 600-700 rpm for 10-30 min to obtain a graphene aerogel coating.
[0038] Then, take several strips of graphene paper with a width of 9mm to 11mm (the length can be appropriate) and place them on a flat workbench. Apply graphene aerogel coating evenly to the graphene paper (the thermal conductivity and wave absorption properties can be controlled by adjusting the number of coatings; in this embodiment, the number of coatings is 2, 4, and 6, and the thickness of a single coating is 40 μm to 60 μm). Dry the paper on a constant temperature heating table at 80℃ for 1 to 2 hours. After cooling, dry it completely to obtain modified graphene paper strips with a polyurethane coating thickness of 80 μm to 360 μm.
[0039] The carbon fiber slurry filler is prepared by the following steps:
[0040] First, take the prepared modified graphene paper strip, fix one end of it on the winding needle of the winding machine, and gently pull the other end to fix it by hand. At a speed of 60rpm~70rpm, roll the graphene paper strip with a width of 9mm~11mm into a cylindrical paper roll with a height of 9mm~11mm and a diameter of 12mm~13mm. It should be noted that when the length of the graphene paper strip is not long enough, carbon fiber slurry can be used to bond multiple graphene paper strips end to end (epoxy resin material has a certain degree of adhesion).
[0041] Then, the cylindrical paper roll with its circular cross-section facing up is placed into the mold and fixed. Carbon fiber slurry is poured into it until the cylindrical paper roll is completely submerged. Subsequently, the mold is placed in a vacuum drying oven and left to stand at room temperature for 2 to 3 hours in a vacuum environment of -0.08 MPa to -0.07 MPa to eliminate internal air bubbles and ensure complete impregnation. After the liquid level stabilizes and no more air bubbles emerge, the temperature of the drying oven is adjusted to 60°C for curing, and the curing time is 2 to 4 hours.
[0042] Finally, using a wire cutting machine at a cutting speed of 2 mm / min, the cylindrical paper roll is cut into 3 mm thick sheets along its circular cross-section to obtain sheet-like composite thermally conductive and microwave-absorbing material.
[0043] The beneficial effects of the present invention will be described in detail below with reference to testing.
[0044] like Figure 1 The diagram shows the structure of the modified graphene paper / carbon fiber slurry composite thermally conductive and microwave absorbing material in this embodiment. The outermost layer is graphene paper 1, which provides a thermally conductive channel; the middle layer is polyurethane & graphene aerogel layer 2, which provides microwave absorption performance; the innermost layer is resin & carbon fiber slurry 3, which fills gaps and assists in microwave absorption and thermal conduction; the electromagnetic wave incident direction is perpendicular to the incident direction.
[0045] like Figure 2 The image shown is a physical picture of the modified graphene paper / carbon fiber slurry composite thermally conductive and microwave absorbing material prepared in this embodiment. The modified graphene paper / carbon fiber slurry composite thermally conductive and microwave absorbing material is in a wound shape.
[0046] like Figure 3 The image shows the terahertz absorption performance of the modified graphene paper in this embodiment. The wave absorption performance of the modified graphene paper has been greatly improved, with the overall absorption rate increasing from 80% to over 90% and the reflection loss increasing from -8dB to better than -10dB.
[0047] Furthermore, the absorption performance of the modified graphene paper / carbon fiber slurry composite thermally conductive and microwave-absorbing material prepared in this embodiment was measured in the range of 0.2 THz to 1.2 THz using a terahertz time-domain spectroscopy system. The results were obtained after calculation as follows: Figure 4 As shown, the average reflection loss of the composite thermally conductive and absorbing material is less than -10dB across the frequency band. Furthermore, the reflection loss is further enhanced as the number of polyurethane coating layers increases, i.e., the coating thickness increases. When the number of coating layers reaches 6, the reflection loss is less than -10dB across the entire frequency band, achieving effective broadband absorption.
[0048] In addition, such as Figure 5 The figure shows the vertical thermal conductivity test results of the laser thermal conductivity meter of the rolled composite thermally conductive and microwave absorbing material prepared in this embodiment. As can be seen from the figure, as the number of polyurethane coatings increases, that is, the coating thickness increases, the thickness of the microwave absorbing layer will increase, which will reduce the proportion of the thermally conductive layer, thus resulting in a decrease in thermal conductivity. When the number of coatings reaches 6, the thermal conductivity is still 122 W / (m·K), which is much higher than that of traditional microwave absorbing materials.
[0049] In summary, this invention provides a paper roll-shaped thermally conductive and microwave-absorbing material, and verifies its microwave absorption and thermal conductivity performance. This thermally conductive and microwave-absorbing material has strong microwave absorption performance and extremely strong thermal conductivity performance. At the same time, the coating thickness can be adjusted to control the performance between different thermal conductivity and microwave absorption requirements, which can effectively solve the problem of poor heat dissipation of polymer microwave-absorbing materials.
[0050] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All disclosed features, or steps in all methods or processes, may be combined in any way except for mutually exclusive features and / or steps.
Claims
1. A modified graphene paper / carbon fiber slurry composite thermally conductive and microwave absorbing material, characterized in that, The composite thermally conductive and microwave-absorbing material includes modified graphene paper and carbon fiber slurry; the modified graphene paper is in a rolled shape, and when unfolded, the single-layer structure consists of graphene paper and a graphene aerogel coating coated on the inner side of the graphene paper; the carbon fiber slurry fills the spaces between adjacent single-layer structures of the rolled modified graphene paper.
2. The modified graphene paper / carbon fiber slurry composite thermally conductive and microwave absorbing material according to claim 1, characterized in that, The graphene paper has a thickness of 10μm to 200μm, the graphene aerogel coating has a thickness of 60μm to 500μm, and the gap between adjacent monolayer structures of the modified graphene paper is 60μm to 600μm.
3. The modified graphene paper / carbon fiber slurry composite thermally conductive and microwave absorbing material according to claim 1, characterized in that, The carbon fiber slurry is composed of carbon fiber and epoxy resin, wherein the mass percentage of carbon fiber is 15wt%~25wt%.
4. The modified graphene paper / carbon fiber slurry composite thermally conductive and microwave absorbing material according to claim 1, characterized in that, The graphene aerogel coating is composed of polyurethane and graphene aerogel particles, wherein the mass percentage of the graphene aerogel particles is 1.5wt% to 2.5wt%.
5. The modified graphene paper / carbon fiber slurry composite thermally conductive and microwave absorbing material according to claim 4, characterized in that, The particle size of graphene aerogel particles ranges from 150 μm to 270 μm.
6. The preparation method of the modified graphene paper / carbon fiber slurry composite thermally conductive and microwave absorbing material according to claim 1, characterized in that, Includes the following steps: S1: Cut the graphene paper into strips of a preset size, apply the graphene aerogel slurry onto the graphene paper and dry it. Repeat the application multiple times to reach the preset thickness to obtain the modified graphene paper. S2: The modified graphene paper is wound into a cylindrical shape. The cylindrical shape is placed in a mold and carbon fiber slurry is injected so that the carbon fiber slurry completely submerges the cylindrical shape. Then, the carbon fiber slurry is filled into the interlayer gaps of the cylindrical shape through vacuum treatment. S3: Heat and cure the impregnated cylindrical coil and cut it into shape.
7. The preparation method of the modified graphene paper / carbon fiber slurry composite thermally conductive and microwave absorbing material according to claim 6, characterized in that, In step S1, the graphene paper has a width of 6mm~10mm and a length of 400mm; the specific drying process is as follows: dry at 80℃ for 1h~2h on a constant temperature heating table, and then completely dry after cooling.
8. The preparation method of the modified graphene paper / carbon fiber slurry composite thermally conductive and microwave absorbing material according to claim 6, characterized in that, In step S2, the specific process of vacuum treatment is as follows: let it stand for 1 to 3 hours in an environment with a vacuum degree of -1.0 MPa to 0.01 MPa.
9. The preparation method of the modified graphene paper / carbon fiber slurry composite thermally conductive and microwave absorbing material according to claim 6, characterized in that, In step S3, the specific process of heating and curing is as follows: in an environment with a vacuum degree of -1.0MPa to 0.01MPa, the curing temperature is set to 60℃ to 80℃, and the curing time is 2h to 5h.
10. The preparation method of the modified graphene paper / carbon fiber slurry composite thermally conductive and microwave absorbing material according to claim 6, characterized in that, In step S3, the specific process of cutting and forming is as follows: cut the cylindrical coil into sheets along the circular cross-section to obtain a composite thermally conductive and microwave-absorbing material with a thickness of 1mm to 5mm.