Preparation method of carbon fiber composite material with thermal conductivity and electromagnetic shielding properties

Abstract

The present invention discloses a method for preparing a carbon fiber composite material with thermal conductivity and electromagnetic shielding properties: using a magnetron sputtering method to alternately deposit Cu particles and AlN particles layer by layer on the surface of the carbon fiber to obtain functionalized fibers; making the functionalized fibers into functionalized carbon fiber mesh; alternately plying the functionalized carbon fiber mesh with carbon fiber unidirectional cloth, with the outermost layer being the carbon fiber unidirectional cloth, and vacuum-assisted molding to obtain a carbon fiber composite material with thermal conductivity and electromagnetic shielding properties. Compared with directly modifying carbon fiber cloth, the functionalized carbon fiber mesh used in the preparation of the carbon fiber composite material by the present invention has a simple process, strong operability and low cost; and because the addition of thermally conductive and conductive particles facilitates the carbon fiber mesh to construct a three-dimensional continuous network in the interlayer resin of the carbon fiber composite material, the bending strength and fracture toughness of the prepared composite material are slightly improved, and the thermal conductivity and electromagnetic shielding performance are significantly improved, and it has good application prospects.

Description

Technical Field

[0001] The invention relates to a method for preparing a carbon fiber composite material with thermal conductivity and electromagnetic shielding properties, and belongs to the field of preparation of carbon fiber composite materials. Background Art

[0002] Carbon fiber composites are widely used in aerospace, rail transit, and other fields due to their excellent characteristics such as light weight, high strength, and customizable performance. Their usage has gradually become an important indicator of engineering advancement. With the rapid development of miniaturization and high-power integrated circuits, thermal management has become one of the most important issues for electronic equipment. Some key structural components of spacecraft, such as satellite antennas, thermal radiators, and space remote sensing cameras, are affected by the huge temperature differences in the space environment and the high heat flux of integrated circuits, resulting in excessive heat accumulation, which damages the performance and life of the devices. In addition, the inevitable electromagnetic interference in highly integrated communication technologies has also become a serious challenge. Therefore, improving the thermal and electrical conductivity of carbon fiber composites is an effective and simple way to solve these problems.

[0003] Compared with the traditional molding process of fiber-reinforced resin composites - autoclave molding, vacuum-assisted resin infusion (VARI) has become one of the main molding processes due to its low cost and simple process. Carbon fiber composites molded by VARI are mostly in the form of laminates. The carbon fibers in the plates are arranged along the in-plane direction, and the layers are bonded and load-transmitted with epoxy resin. However, epoxy resin is highly cross-linked and brittle after curing. Therefore, the interlayer toughness of carbon fiber composites is poor. Moreover, due to the difference in crystallinity and structure, the thermal conductivity and electrical conductivity of epoxy resin are much lower than those of carbon fiber. Therefore, the transmission of phonons and electrons in the thickness direction of the carbon fiber composite is not continuous, affecting the heat transfer / conductivity effect.

[0004] At present, the improvement of the thermal conductivity and electrical conductivity of carbon fiber composite materials in the thickness direction is mainly achieved by treating the carbon fiber surface / structure, modifying the matrix resin and intercalation. For example, Chinese patent CN 114379167 A (publication date April 22, 2022) discloses an interlayer modified carbon fiber composite material and its preparation method and application. The method uses high voltage electricity to vertically orient short carbon fibers on carbon fiber prepregs, and then lays and cures them in sequence to obtain carbon fiber composite materials, which can improve the interlayer toughness and electrical conductivity of the composite materials. However, because the prepreg is made of a polymer pre-impregnated with a resin and poor thermal / electrical conductivity, there is an interface thermal resistance / electrical resistance between the prepreg and the short carbon fibers, and the performance improvement is limited. Chinese patent CN 109265919 B (publication date February 14, 2020) discloses a 3D thermally conductive composite material and its preparation method. This method inserts a thermally conductive film into the planar layer of the carbon fiber composite material and implants fiber pins or metal needles in the thickness direction, thereby achieving an increase in thermal conductivity in the thickness direction and effectively improving the interlaminar shear strength. However, this method destroys the structure of the main continuous fibers and damages the in-plane mechanical properties of the composite material, such as tensile strength. Modification of the matrix resin will increase the viscosity of the resin and is not conducive to actual processing. For example, Chinese patent CN 117603555 A (publication date April 27, 2024) discloses a method of using polyetheramine-functionalized boron nitride nanotubes to improve the thermal conductivity and toughness of epoxy resin, but it will affect the molding of the composite material and is not conducive to sufficient resin infiltration.

[0005] In comparison, the intercalation method does not destroy the excellent properties of carbon fiber itself, nor does it affect the mechanical properties of the composite material. Chinese patent CN 102909905 B (publication date May 13, 2015) discloses a composite thermal conductive thin layer and its preparation method and application, but the author does not point out that the thin layer inserted between the layers of the composite material will contribute to its electromagnetic shielding performance. Summary of the Invention

[0006] The problem to be solved by the present invention is to improve the thermal conductivity / electrical conductivity of carbon fiber composite materials in the thickness direction while maintaining the excellent mechanical properties of carbon fiber composite materials, overcome the problems caused by the modification of carbon fiber and resin matrix, and simply and pollution-free prepare carbon fiber composite materials with thermal conductivity and electromagnetic shielding.

[0007] In order to solve the above problems, the present invention provides a method for preparing a carbon fiber composite material with thermal conductivity and electromagnetic shielding properties, comprising the following steps:

[0008] Step 1): reflux the carbon fiber in an acetone solution for 12-24 hours to remove the sizing agent on the surface, rinse with deionized water, and then dry in an oven for 3-6 hours;

[0009] Step 2): Use magnetron sputtering method at a background vacuum of 1×10 -4 ~5×10 -4 Under the conditions of 0.25-0.5 Pa and a working vacuum of 0.25-0.5 Pa, Cu (copper) particles are deposited on the surface of the carbon fiber obtained in step 1), followed by continuous deposition of AlN (aluminum nitride) particles, alternately depositing layer by layer to obtain Cu / AlN synergistic functionalized fibers;

[0010] Step 3): dispersing the functionalized fibers obtained in step 2) in a prepared dispersant solution, and preparing a functionalized carbon fiber mesh by wet-laying, shaping, and drying;

[0011] Step 4): The functionalized carbon fiber mesh obtained in step 3) is alternately layered with carbon fiber unidirectional cloth, with the outermost layer being the carbon fiber unidirectional cloth, and vacuum-assisted molding is performed to obtain a carbon fiber composite material with a thickness of 2-5 mm and having thermal conductivity and electromagnetic shielding properties.

[0012] Preferably, the carbon fibers in step 1) include any one of polyacrylonitrile-based and mesophase pitch-based carbon fibers, or a combination of both; and the carbon fibers are 4-6 mm chopped carbon fibers.

[0013] Preferably, in step 2), the deposition area of ​​the Cu particles occupies 20-40% of the carbon fiber surface, the deposition area of ​​the AlN particles occupies 10-30% of the fiber surface, and the deposition is performed alternately layer by layer 1-5 times.

[0014] Preferably, the process parameters of the magnetron sputtering method in step 2) are: sputtering power 50-100 W, sputtering time for depositing Cu particles is 10-30 min, and sputtering time for depositing AlN particles is 5-20 min.

[0015] Preferably, the mass concentration of the dispersant solution in step 3) is 0.5-1%, and the dispersant includes any one or more of dodecyltrimethylammonium bromide, octadecyltrimethylammonium bromide and sodium oleate.

[0016] Preferably, the material used for shaping in step 3) includes any one or more of polyamide hot melt adhesive, silicone resin, and polyacrylic resin.

[0017] Preferably, the functionalized carbon fiber mesh obtained in step 3) has an area density of 4 to 10 gsm.

[0018] Preferably, the carbon fiber unidirectional cloth in step 4) is T700 12K carbon fiber unidirectional cloth with an area density of 150-200 gsm.

[0019] Preferably, the process parameters of the vacuum-assisted molding in step 4) are: using epoxy resin E-44, an infusion temperature of 60-80° C., a curing temperature of 120-140° C., and a curing time of 1-2 hours.

[0020] The composite material provided by the present invention is prepared by depositing Cu and AlN materials on the surface of carbon fiber using magnetron sputtering, and obtaining carbon fiber mesh by wet web forming. This functionalized carbon fiber mesh is laid between carbon fiber cloth layers, and a carbon fiber composite material with a thickness of 2-5 mm is prepared by a vacuum-assisted molding process.

[0021] The present invention constructs a continuous thermal and electrical conductive path on the three-dimensional skeleton structure of the carbon fiber mesh, thereby improving the thermal conductivity and electromagnetic shielding performance of the composite material. At the same time, the insertion of the fiber mesh changes the way stress is transmitted between the layers of the composite material, thereby improving the toughness of the composite material. It has the characteristics of simple operation, strong processability and excellent performance.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) In the present invention, magnetron sputtering is used to assemble thermally conductive and electrically conductive material layers on chopped fibers, thereby improving the interface bonding between the material and the fibers and between the fibers, and producing a synergistic thermal conductive and electromagnetic shielding effect with the short carbon fibers inside the carbon fiber mesh.

[0024] (2) The present invention controls the bonding form and thickness of particles attached to the fiber mesh by adjusting the magnetron sputtering power and time, so that the sputtering coating is uniform and stable, effectively avoiding the problem of easy enrichment of nanomaterials.

[0025] (3) The present invention utilizes carbon fiber mesh as an intercalation toughening composite material, and simultaneously sputters the required materials to form interlayer heat transfer and electrical conductivity pathways, effectively solving the problem of poor interlayer performance of carbon fiber composite materials.

[0026] (4) The method for preparing a carbon fiber composite material with thermal conductivity and electromagnetic shielding described in the present invention has a simple process and strong operability, and can simultaneously achieve thermal conductivity, electromagnetic shielding and toughening of the carbon fiber composite material, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the ply structure of the carbon fiber composite material prepared by the present invention;

[0028] Figure 2 for Figure 1 The partial enlarged view of part A is a schematic diagram of the carbon fibers in the functionalized carbon fiber mesh;

[0029] Figure 3 This is a photo of the carbon fiber composite material prepared in the present invention. DETAILED DESCRIPTION

[0030] To make the present invention more clearly understood, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0031] The laminate structure of the carbon fiber composite material prepared by the present invention is as follows Figure 1 、 2 As shown, it includes alternating functionalized carbon fiber mesh 2 and carbon fiber unidirectional cloth 1 (the outermost layer is carbon fiber unidirectional cloth 1, due to the limitations of the accompanying drawings, Figure 1 Only 5 layers are given as an example). Among them, the functionalized carbon fiber mesh 2 is as follows Figure 2 As shown, Cu particles 3 and AlN particles 4 are deposited on the fiber surface.

[0032] Example 1

[0033] (1) 4 mm mesophase pitch-based chopped carbon fibers were refluxed in an acetone solution for 12 h to remove the surface sizing agent, washed with deionized water, and dried in an oven for 6 h;

[0034] (2) Using magnetron sputtering method at a background vacuum of 5×10 -4 Pa, working vacuum degree 0.5Pa, Cu particles were deposited on the surface of the carbon fiber obtained in the above step (1), the sputtering time was 20min, and the deposition area accounted for 20% of the fiber surface; then AlN particles were deposited, the sputtering time was 10min, the deposition area accounted for 10% of the fiber surface, the sputtering power was 50W, and the layer-by-layer alternating deposition was repeated twice to obtain functionalized short carbon fibers synergistically formed with Cu and AlN;

[0035] (3) dispersing the functionalized short carbon fibers obtained in step (2) above in a prepared 0.5 wt% dodecyltrimethylammonium bromide dispersant, wet-forming the mesh, spraying the mesh with polyacrylic resin for shaping, and drying the mesh to produce a functionalized carbon fiber mesh with an area density of 5 gsm;

[0036] (4) The functionalized carbon fiber mesh obtained in step (3) is alternately layered with T700 12K carbon fiber unidirectional cloth with a surface density of 200 gsm, with the outermost layer being the carbon fiber unidirectional cloth, and vacuum-assisted molding is performed to prepare a high-toughness carbon fiber composite material with a thickness of 4 mm and having thermal conductivity and electromagnetic shielding.

[0037] After testing, the in-plane thermal conductivity of carbon fiber composite materials is 20.53±0.21W / (m·K), the thermal conductivity in the thickness direction is 0.55±0.25W / (m·K), and the electromagnetic shielding effectiveness S ET The interlaminar fracture toughness of type I is 1.25±0.32kJ / m 2 , the interlaminar fracture toughness of mode II is 2.47±0.26kJ / m 2 .

[0038] Example 2

[0039] (1) 4 mm mesophase pitch-based chopped carbon fibers were refluxed in acetone solution for 12 h to remove the surface sizing agent, washed with deionized water, and dried in an oven for 6 h;

[0040] (2) Using magnetron sputtering method at a background vacuum of 5×10 -4 Pa, working vacuum degree 0.5Pa, Cu particles were deposited on the surface of the carbon fiber obtained in the above step (1), the sputtering time was 20min, and the deposition area accounted for 20% of the fiber surface; then AlN particles were deposited, the sputtering time was 10min, the deposition area accounted for 10% of the fiber surface, the sputtering power was 50W, and the layer-by-layer alternating deposition was repeated 4 times to obtain functionalized short carbon fibers synergistically formed with Cu and AlN;

[0041] (3) dispersing the functionalized chopped carbon fibers obtained in step (2) above in a prepared 0.5 wt% dodecyltrimethylammonium bromide dispersant, wet-forming the mesh, spraying the mesh with polyacrylic resin for shaping, and drying the mesh to produce a functionalized carbon fiber mesh with an area density of 6 gsm;

[0042] (4) The functionalized carbon fiber mesh obtained in step (3) is alternately layered with T700 12K carbon fiber unidirectional cloth with a surface density of 200 gsm, with the outermost layer being the carbon fiber unidirectional cloth, and vacuum-assisted molding is performed to prepare a high-toughness carbon fiber composite material with a thickness of 4 mm and having thermal conductivity and electromagnetic shielding.

[0043] After testing, the in-plane thermal conductivity of carbon fiber composite materials is 24.26±0.24W / (m·K), the thermal conductivity in the thickness direction is 0.62±0.18W / (m·K), and the electromagnetic shielding effectiveness S ET is 47.26±2.15dB, and the interlaminar fracture toughness of mode I is 1.22±0.17kJ / m 2 , the interlaminar fracture toughness of mode II is 2.33±0.24kJ / m 2 .

[0044] Example 3

[0045] (1) 4 mm mesophase pitch-based chopped carbon fibers were refluxed in acetone solution for 12 h to remove the surface sizing agent, washed with deionized water, and dried in an oven for 6 h;

[0046] (2) Using magnetron sputtering method at a background vacuum of 5×10 -4Pa, working vacuum degree 0.5Pa, Cu particles were deposited on the surface of the carbon fiber obtained in the above step (1), the sputtering time was 25min, and the deposition area accounted for 30% of the fiber surface; then AlN particles were deposited, the sputtering time was 10min, the deposition area accounted for 10% of the fiber surface, the sputtering power was 50W, and the layer-by-layer alternating deposition was repeated twice to obtain functionalized short carbon fibers synergistically formed with Cu and AlN;

[0047] (3) dispersing the functionalized chopped carbon fibers obtained in step (2) above in a prepared 0.5 wt% dodecyltrimethylammonium bromide dispersant, wet-forming the mesh, spraying the mesh with polyacrylic resin for shaping, and drying the mesh to produce a functionalized carbon fiber mesh with an area density of 8 gsm;

[0048] (4) The functionalized carbon fiber mesh obtained in step (3) is alternately layered with T700 12K carbon fiber unidirectional cloth with a surface density of 200 gsm, with the outermost layer being the carbon fiber unidirectional cloth, and vacuum-assisted molding is performed to prepare a high-toughness carbon fiber composite material with a thickness of 4 mm and having thermal conductivity and electromagnetic shielding.

[0049] After testing, the in-plane thermal conductivity of carbon fiber composite materials is 28.18±0.21W / (m·K), the thermal conductivity in the thickness direction is 0.75±0.20W / (m·K), and the electromagnetic shielding effectiveness S ET is 51.16±2.23dB, and the interlaminar fracture toughness of mode I is 1.25±0.13kJ / m 2 , the interlaminar fracture toughness of type II is 2.12±0.16kJ / m 2 .

[0050] Comparative Example 1

[0051] (1) 4 mm mesophase pitch-based chopped carbon fibers were refluxed in acetone solution for 12 h to remove the surface sizing agent, washed with deionized water, and dried in an oven for 6 h;

[0052] (2) dispersing the chopped carbon fibers obtained in step (1) above in a prepared 0.5 wt% dodecyltrimethylammonium bromide dispersant, wet-forming the mesh, spraying polyacrylic resin for shaping, and drying the mesh to produce a functionalized carbon fiber mesh with an area density of 4 gsm;

[0053] (3) The carbon fiber mesh obtained in step (2) is alternately layered with T700 12K carbon fiber unidirectional cloth with a surface density of 200 gsm, with the outermost layer being the carbon fiber unidirectional cloth, and vacuum-assisted molding is performed to prepare a high-toughness carbon fiber composite material with a thickness of 4 mm and having thermal conductivity and electromagnetic shielding.

[0054] After testing, the in-plane thermal conductivity of carbon fiber composite materials is 16.26±0.24W / (m·K), the thermal conductivity in the thickness direction is 0.52±0.16W / (m·K), and the electromagnetic shielding effectiveness SET is 40.27±2.15dB, and the interlaminar fracture toughness of mode I is 1.15±0.26kJ / m 2 , the interlaminar fracture toughness of mode II is 2.16±0.25kJ / m 2 .

[0055] Comparative Example 2

[0056] (1) 4 mm polyacrylonitrile-based short-cut carbon fibers were refluxed in acetone solution for 12 h to remove the surface sizing agent, washed with deionized water, and dried in an oven for 6 h;

[0057] (2) dispersing the chopped carbon fibers obtained in step (1) above in a prepared 0.5 wt% dodecyltrimethylammonium bromide dispersant, wet-forming the mesh, spraying polyacrylic resin for shaping, and drying the mesh to produce a functionalized carbon fiber mesh with an area density of 4 gsm;

[0058] (3) The carbon fiber mesh obtained in step (2) is alternately layered with T700 12K carbon fiber unidirectional cloth with a surface density of 200 gsm, with the outermost layer being the carbon fiber unidirectional cloth, and vacuum-assisted molding is performed to prepare a high-toughness carbon fiber composite material with a thickness of 4 mm and having thermal conductivity and electromagnetic shielding.

[0059] After testing, the in-plane thermal conductivity of carbon fiber composite materials is 4.69±0.18W / (m·K), the thermal conductivity in the thickness direction is 0.48±0.22W / (m·K), and the electromagnetic shielding effectiveness S ET is 36.25±2.22dB, and the interlaminar fracture toughness of mode I is 1.21±0.24kJ / m 2 , the interlaminar fracture toughness of type II is 2.05±0.26kJ / m 2 .

[0060] The performance test results of Examples 1-3 and Comparative Examples 1-2 are shown in Table 1.

[0061] Table 1

[0062]

[0063] Compared with the comparative example, the composite material prepared by the functionalized mesh intercalation of the present invention has excellent thermal conductivity, effectively improved electromagnetic shielding performance, and excellent interlayer toughness.

Claims

1. A method for preparing a carbon fiber composite material with thermal conductivity and electromagnetic shielding properties, characterized in that: The following steps are involved: Step 1): Reflux the carbon fiber in an acetone solution for 12-24 hours to remove the slurry on the surface, rinse with deionized water and then dry in an oven; the carbon fiber is a mesophase pitch-based carbon fiber, using 4-6 mm short chopped carbon fiber; Step 2): Use magnetron sputtering method at a background vacuum of 1×10 -4 ~5×10 -4 Pa and a working vacuum of 0.25-0.5 Pa, depositing Cu particles on the surface of the carbon fiber obtained in step 1), followed by depositing AlN particles, alternately depositing layer by layer to obtain Cu / AlN synergistic functionalized fibers; the deposited area of ​​the Cu particles accounts for 20-40% of the carbon fiber surface, and the deposited area of ​​the AlN particles accounts for 10-30% of the fiber surface, and the alternate deposition is repeated 1-5 times; Step 3): The functionalized fibers obtained in step 2) are dispersed in a prepared dispersant solution, and the functionalized carbon fiber mesh is prepared by wet-laying, shaping, and drying; Step 4): The functionalized carbon fiber mesh obtained in step 3) is alternately layered with carbon fiber unidirectional cloth, with the outermost layer being the carbon fiber unidirectional cloth, and vacuum-assisted molding is performed to obtain a carbon fiber composite material with a thickness of 2-5 mm and having thermal conductivity and electromagnetic shielding properties.

2. The preparation method according to claim 1, wherein The process parameters of the magnetron sputtering method in step 2) are: sputtering power 50-100 W, sputtering time for depositing Cu particles is 10-30 minutes, and sputtering time for depositing AlN particles is 5-20 minutes.

3. The preparation method according to claim 1, wherein The mass concentration of the dispersant solution in step 3) is 0.5-1%, and the dispersant includes any one or more of dodecyltrimethylammonium bromide, octadecyltrimethylammonium bromide and sodium oleate.

4. The preparation method according to claim 1, wherein The materials used for shaping in step 3) include any one or more of polyamide hot melt adhesive, silicone resin, and polyacrylic resin.

5. The preparation method according to claim 1, wherein The functionalized carbon fiber mesh prepared in step 3) has an area density of 4-10 gsm.

6. The preparation method according to claim 1, wherein The carbon fiber unidirectional fabric in step 4) is T700 12K carbon fiber unidirectional fabric with an area density of 150-200 gsm.

7. The preparation method according to claim 1, wherein The process parameters of the vacuum-assisted molding in step 4) are: epoxy resin E-44, infusion temperature 60-80° C., curing temperature 120-140° C., and curing time 1-2 hours.

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