Multistage carbon fiber wave-absorbing material as well as preparation method and application thereof

Abstract

The invention provides a multistage carbon fiber wave-absorbing material and a preparation method and application thereof, and belongs to the technical field of metamaterials. The multi-stage carbon fiber wave-absorbing material provided by the invention comprises a reflecting layer and an electromagnetic functional layer arranged on a single surface of the reflecting layer, the electromagnetic function layer comprises a transmission medium matrix and a plurality of carbon fiber array units arranged in the transmission medium matrix, each carbon fiber array unit is composed of a plurality of carbon fiber strips distributed in a width gradient mode at intervals, and the carbon fiber strips are kept continuous in the fiber direction; and the widest carbon fiber strip in the carbon fiber array unit is close to the reflecting layer. According to the multistage carbon fiber wave-absorbing material, the lightweight bearing capacity of a wave-absorbing structure is improved, the multistage carbon fiber wave-absorbing material further has excellent electromagnetic absorption performance, wide-angle efficient absorption of electromagnetic waves of the C wave band, the X wave band and the Ku wave band can be achieved, and the electromagnetic wave absorption and lightweight bearing integrated design is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of metamaterials, and in particular relates to a multi-level carbon fiber absorbing material and a preparation method and application thereof. Background Art

[0002] Electromagnetic metamaterials are a type of artificial composite material composed of artificially designed microstructure units arranged and combined in a specific way. These microstructure units show electromagnetic properties that are completely different from those of natural materials on a macro scale, such as negative dielectric constant, negative magnetic permeability, negative refractive index, etc. These properties give electromagnetic metamaterials unique advantages in electromagnetic wave regulation and have great application prospects in the fields of stealth materials, microwave devices, etc.

[0003] Traditional electromagnetic metamaterials are generally metal wires or resistor films. In this field, microstructure design is usually used to achieve efficient and precise control of electromagnetic waves. However, due to the limitations of preparation technology and structural form, the absorption band of traditional electromagnetic metamaterials under limited thickness is often narrow, and the electromagnetic wave absorption performance is poor. In addition, in the design process of traditional electromagnetic metamaterials, their mechanical properties are usually ignored, resulting in poor load-bearing performance and difficulty in meeting actual engineering needs. Summary of the invention

[0004] The purpose of the present invention is to provide a multi-level carbon fiber absorbing material and its preparation method and application. The multi-level carbon fiber absorbing material of the present invention improves the lightweight load-bearing capacity of the absorbing structure and also has excellent electromagnetic absorption performance, realizing the integrated design of electromagnetic wave absorption and lightweight load-bearing.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a multi-level carbon fiber absorbing material, comprising a reflective layer and an electromagnetic functional layer arranged on a single surface of the reflective layer; the electromagnetic functional layer comprises a transmission medium matrix and a plurality of carbon fiber array units arranged inside the transmission medium matrix, each carbon fiber array unit is composed of a plurality of carbon fiber strips with a width gradient distribution, the carbon fiber strips remain continuous along the fiber direction, and the widest carbon fiber strip in the carbon fiber array unit is close to the reflective layer.

[0007] Preferably, the electrical conductivity of the carbon fiber strip along the fiber direction is 32000-38000 S / m, and the electrical conductivity perpendicular to the fiber direction is 85-94 S / m.

[0008] Preferably, in each carbon fiber array unit, the width of the carbon fiber strip increases linearly and continuously from top to bottom in the vertical direction, the width of the top carbon fiber strip is 0.5-2.0 mm, and the width of the bottom carbon fiber strip is 7.5-9.0 mm; the width gradient of the carbon fiber strip is 0.2-1.0 mm.

[0009] Preferably, in each carbon fiber array unit, the upper and lower spacing between two adjacent layers of carbon fiber strips is 0.1-0.5 mm.

[0010] Preferably, when there are multiple carbon fiber array units, the multiple carbon fiber array units are periodically arranged in the horizontal direction, and the distance between the widest carbon fiber strips in two adjacent carbon fiber array units is 1-2 mm.

[0011] Preferably, the number of the carbon fiber array units in the transverse direction is 33-36, and the number in the longitudinal direction is 1.

[0012] Preferably, the transmission medium matrix is ​​a glass fiber laminate, an aramid fiber laminate or a basalt fiber laminate; and the height of the transmission medium matrix is ​​4.0-4.8 mm.

[0013] Preferably, the reflective layer is a carbon fiber laminate, a graphene laminate or a carbon nanotube laminate; and the height of the reflective layer is 0.25-0.5 mm.

[0014] The present invention provides a method for preparing the multi-level carbon fiber absorbing material described in the above technical solution, comprising the following steps:

[0015] According to the structure of the electromagnetic functional layer, a plurality of carbon fiber array units are embedded in a transmission medium matrix to obtain the electromagnetic functional layer;

[0016] The reflective layer and the electromagnetic functional layer are stacked and assembled, and the widest carbon fiber strip in the carbon fiber array unit is placed close to the reflective layer to obtain the multi-level carbon fiber absorbing material.

[0017] The present invention provides the use of the multi-level carbon fiber absorbing material described in the above technical solution or the multi-level carbon fiber absorbing material obtained by the preparation method described in the above technical solution in stealth materials.

[0018] The present invention provides a multi-level carbon fiber absorbing material, comprising a reflective layer and an electromagnetic functional layer arranged on the surface of the reflective layer; the electromagnetic functional layer comprises a transmission medium matrix and a plurality of carbon fiber array units arranged inside the transmission medium matrix, each carbon fiber array unit is composed of a plurality of carbon fiber strips with a width gradient distribution, the carbon fiber strips remain continuous along the fiber direction, and the widest carbon fiber strip in the carbon fiber array unit is close to the reflective layer. In the present invention, the transmission medium enables electromagnetic waves to penetrate into the interior of the carbon fiber array unit, the reflective layer can prevent electromagnetic waves from interfering with the internal electromagnetic environment, and enhance the secondary absorption efficiency of the absorbing structure for electromagnetic waves; the carbon fiber strips are gradiently distributed in the electromagnetic functional layer, which can excite the surface plasmon propagation mode of electromagnetic waves and realize electromagnetic absorption through the ohmic loss of carbon fiber; in addition, the plurality of carbon fiber strips with a width gradient distribution can realize broadband absorption and avoid strong reflection of electromagnetic waves; at the same time, the carbon fiber strips remain continuous along the fiber direction, and the excellent mechanical properties of carbon fiber can be used to improve the bearing performance of the absorbing structure. The multi-level carbon fiber absorbing material provided by the present invention can efficiently absorb electromagnetic waves in the C-band, X-band and Ku-band at a wide angle, and has excellent tensile bearing performance and three-point bending bearing performance, ultimately realizing an integrated design of electromagnetic wave absorption and lightweight bearing.

[0019] Furthermore, the present invention uses a laminate with excellent mechanical properties and a sufficient number of designable layers as the base skeleton of the absorbing structure, which can improve the bearing performance of the absorbing structure and provide sufficient space for the internal electromagnetic microstructure design while reducing the weight of the structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0021] Figure 1 Schematic diagram of the multi-level carbon fiber absorbing material obtained in Example 1; 1 is the transmission medium matrix, 2 is the reflection layer, and 3 is the carbon fiber array unit;

[0022] Figure 2 This is a front view of the multi-level carbon fiber absorbing material obtained in Example 1;

[0023] Figure 3 This is a diagram of the wave absorbing performance of the multi-level carbon fiber wave absorbing material obtained in Example 1;

[0024] Figure 4This is a comparison chart of the absorbing performance of the multi-stage carbon fiber absorbing material obtained in Example 1, the #1 material obtained in Comparative Example 1, and the #2 material obtained in Comparative Example 2;

[0025] Figure 5 This is a comparison chart of the tensile bearing performance of the multi-level carbon fiber absorbing material obtained in Example 1 and the #1 material obtained in Comparative Example 1;

[0026] Figure 6 This is a comparison chart of the three-point bending bearing performance of the multi-level carbon fiber absorbing material obtained in Example 1 and the #1 material obtained in Comparative Example 1. DETAILED DESCRIPTION

[0027] The present invention provides a multi-level carbon fiber absorbing material, comprising a reflective layer and an electromagnetic functional layer arranged on a single surface of the reflective layer; the electromagnetic functional layer comprises a transmission medium matrix and a plurality of carbon fiber array units arranged inside the transmission medium matrix, each carbon fiber array unit is composed of a plurality of carbon fiber strips with a width gradient distribution, the carbon fiber strips remain continuous along the fiber direction, and the widest carbon fiber strip in the carbon fiber array unit is close to the reflective layer.

[0028] The multi-level carbon fiber absorbing material of the present invention includes a reflective layer. In the present invention, the reflective layer is preferably a carbon fiber laminate, a graphene laminate or a carbon nanotube laminate; the height of the reflective layer is preferably 0.25 to 0.5 mm, more preferably 0.3 to 0.45 mm. In the present invention, the reflective layer is preferably a rectangular plate. The present invention uses a reflective layer as the lower structure of the multi-level carbon fiber absorbing material, which can prevent electromagnetic waves from entering and interfering with the internal electromagnetic environment. At the same time, the incident electromagnetic waves can be absorbed twice to improve the absorption efficiency.

[0029] The multi-level carbon fiber absorbing material of the present invention comprises an electromagnetic functional layer arranged on a single surface of the reflective layer; the electromagnetic functional layer comprises a transmission medium matrix and a plurality of carbon fiber array units arranged inside the transmission medium matrix.

[0030] In the present invention, the transmission medium matrix is ​​preferably a glass fiber laminate, an aramid fiber laminate or a basalt fiber laminate. In an embodiment of the present invention, the transmission medium matrix is ​​a glass fiber laminate with a dielectric constant of 4.3. The height of the transmission medium matrix of the present invention is preferably 4.0 to 4.8 mm, more preferably 4.2 to 4.5 mm. In the present invention, the transmission medium matrix is ​​preferably a rectangular plate. The present invention uses a transmission medium matrix as the upper structure of a multi-level carbon fiber absorbing material, which can allow electromagnetic waves to penetrate into the interior of the absorbing structure and reduce the reflection ability of the absorbing structure to electromagnetic waves.

[0031] In the present invention, each carbon fiber array unit is composed of carbon fiber strips with a width gradient distribution, and the carbon fiber strips remain continuous along the fiber direction. The widest carbon fiber strip in the carbon fiber array unit is close to the reflective layer. The carbon fiber array unit of the present invention is preferably arranged in the ply of the electromagnetic functional layer. The present invention preferably embeds the carbon fiber strips into the holes of the partial ply of the electromagnetic functional layer. In the present invention, the electrical conductivity of the carbon fiber strip along the fiber direction is preferably 32000-38000S / m, more preferably 35000S / m; the electrical conductivity perpendicular to the fiber direction is preferably 85-94S / m, more preferably 89S / m. In the present invention, the carbon fiber array unit has a pyramid configuration. The carbon fiber array units of the present invention are preferably arranged periodically in the horizontal direction (x direction and / or y direction); the number of the carbon fiber array units in the transverse direction (x direction) is preferably 33 to 36, specifically 33, 34, 35 or 36; the number in the longitudinal direction (y direction) is preferably 1; the distance between the widest carbon fiber strips of two adjacent carbon fiber array units is preferably 1 to 2 mm, specifically 1 mm, 1.5 mm or 2 mm. In each carbon fiber array unit of the present invention, the width of the carbon fiber strips preferably increases linearly and continuously from top to bottom along the vertical direction (z direction); the width of the top carbon fiber strips is preferably 0.5 to 2.0 mm, more preferably 1.0 to 1.5 mm; the width of the bottom carbon fiber strips is preferably 7.5 to 9.0 mm, more preferably 8.0 to 8.5 mm; the width gradient of the carbon fiber strips is preferably 0.2 to 1.0 mm, further preferably 0.4 to 1.0 mm, more preferably 0.5 mm; the upper and lower spacing between two adjacent layers of carbon fiber strips is preferably 0.1 to 0.5 mm, more preferably 0.2 to 0.4 mm. In the present invention, the number of the carbon fiber strips in each carbon fiber array unit is preferably 13 to 15, and more preferably 15; the height of each carbon fiber array unit is preferably 3.4 to 4.2 mm, and more preferably 3.5 to 4.0 mm.

[0032] The multi-level carbon fiber absorbing material of the present invention can effectively absorb incident electromagnetic waves in the C band, X band and Ku band, and has excellent tensile strength and bending strength.

[0033] The present invention also provides a method for preparing the multi-level carbon fiber absorbing material described in the above technical solution, comprising the following steps:

[0034] According to the structure of the electromagnetic functional layer, a plurality of carbon fiber array units are embedded in a transmission medium matrix to obtain the electromagnetic functional layer;

[0035] The reflective layer and the electromagnetic functional layer are stacked and assembled, and the widest carbon fiber strip in the carbon fiber array unit is placed close to the reflective layer to obtain the multi-level carbon fiber absorbing material.

[0036] In the present invention, unless otherwise specified, the raw materials used are commercially available products well known to those skilled in the art or are prepared by methods well known to those skilled in the art.

[0037] The method of embedding a plurality of carbon fiber array units in a transmission medium matrix according to the present invention preferably includes the following steps: opening holes in a blank single-layer board and embedding carbon fiber strips to obtain a mixed single-layer board; performing a first stacking assembly of a plurality of mixed single-layer boards and a plurality of blank single-layer boards in a manner of alternatingly laying a layer of mixed single-layer boards and a layer of blank single-layer boards along the width growth direction of the carbon fiber strips to obtain an electromagnetic functional layer; the electromagnetic functional layer includes a transmission medium matrix and a plurality of carbon fiber array units arranged inside the transmission medium matrix, each carbon fiber array unit consisting of a plurality of carbon fiber strips distributed in a gradient.

[0038] The present invention makes holes in a single-layer board and embeds carbon fiber strips to obtain a hybrid single-layer board. In an embodiment of the present invention, the blank single-layer board is cut according to the designed size of each layer of carbon fiber strips, so that through holes are formed in the thickness direction of the blank single-layer board, and then the carbon fiber strips are embedded in the aforementioned holes of corresponding size to obtain a hybrid single-layer board.

[0039] After obtaining the hybrid single-layer board, the present invention stacks and assembles multiple hybrid single-layer boards and multiple blank single-layer boards in a manner of alternately laying hybrid single-layer boards and blank single-layer boards along the direction of the width growth of the carbon fiber strips to obtain an electromagnetic functional layer; the electromagnetic functional layer includes a transmission medium matrix and a plurality of carbon fiber array units arranged inside the transmission medium matrix, and each carbon fiber array unit is composed of a plurality of carbon fiber strips distributed in a gradient. In the present invention, the stacking assembly preferably includes stacking multiple hybrid single-layer boards and multiple blank single-layer boards alternately together in the direction of the width growth of the carbon fiber strips, and using an adhesive to stick the hybrid single-layer boards and the blank single-layer boards together. The adhesive of the present invention is preferably an epoxy resin. In an embodiment of the present invention, the epoxy resin is the 9A16 epoxy resin contained in the G15000 / 9A16 / 33% unidirectional glass fiber prepreg and USN12500 / 9A16 / 33% unidirectional carbon fiber prepreg produced by Weihai Guangwei Composite Materials Technology Co., Ltd., China.

[0040] After obtaining the electromagnetic functional layer, the present invention laminates and assembles the reflective layer and the electromagnetic functional layer, and makes the widest carbon fiber strip in the carbon fiber array unit close to the reflective layer to obtain the multi-level carbon fiber absorbing material. In the present invention, the laminated assembly preferably includes using an adhesive to stick the electromagnetic functional layer on the upper surface of the reflective layer, and obtaining the multi-level carbon fiber absorbing material after curing. In the present invention, the adhesive is preferably an epoxy resin. In an embodiment of the present invention, the epoxy resin is the 9A16 epoxy resin contained in the G15000 / 9A16 / 33% unidirectional glass fiber prepreg and USN12500 / 9A16 / 33% unidirectional carbon fiber prepreg produced by Weihai Guangwei Composite Materials Technology Co., Ltd., China. In the present invention, the curing temperature is preferably 110-130°C, more preferably 120°C; the time is preferably 1.5-3h, more preferably 2h; the pressure is preferably 0.8-1bar, specifically 0.8bar, 0.9bar or 1bar. In the present invention, the curing is preferably carried out in a compression mold. The present invention can make the laminate and the carbon fiber strips embedded therein fit closely by curing, thereby improving the wave absorbing performance. The present invention preferably removes the molding device after curing, cleans the surface dirt and polishes, thereby improving the surface quality of the multi-level carbon fiber wave absorbing material.

[0041] The present invention adopts continuous carbon fiber strips along the fiber direction and embeds them into the laminate. On the one hand, the excellent mechanical properties of carbon fiber are used to improve the strength of the structure. On the other hand, the gradient arrangement of carbon fiber strips delays the occurrence of structural failure under bending load, improves the fiber bearing efficiency of the whole structure, and finally greatly improves the tensile properties and three-point bending properties of the obtained multi-level carbon fiber absorbing material.

[0042] The present invention provides the use of the multi-level carbon fiber absorbing material described in the above technical solution or the multi-level carbon fiber absorbing material obtained by the preparation method described in the above technical solution in stealth materials. The application of the present invention preferably includes applying the multi-level carbon fiber absorbing material as a stealth material to an aircraft structure.

[0043] The multi-level carbon fiber absorbing material of the present invention not only improves the lightweight bearing capacity of the absorbing structure, but also gives it excellent electromagnetic absorption performance, thereby realizing a stealth bearing integrated design.

[0044] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] The adhesive used for pasting is 9A16 epoxy resin contained in G15000 / 9A16 / 33% unidirectional glass fiber prepreg and USN12500 / 9A16 / 33% unidirectional carbon fiber prepreg produced by Weihai Guangwei Composite Materials Technology Co., Ltd., China.

[0046] Example 1

[0047] This embodiment provides a multi-level carbon fiber absorbing material. Figure 1 This is a schematic diagram of a multi-level carbon fiber absorbing material. Figure 2 This is a front view of the multi-level carbon fiber absorbing material.

[0048] like Figures 1-2 As shown, the multi-level carbon fiber absorbing material in this embodiment includes a glass fiber laminate 1 and a carbon fiber laminate 2 stacked in layers, and the glass fiber laminate 1 is provided with 33 carbon fiber array units 3 periodically distributed along the transverse direction (y direction); each of the carbon fiber array units 3 is composed of 15 gradient-distributed carbon fiber strips along the vertical direction (z direction).

[0049] The dielectric constant of the glass fiber laminate is 4.3; the height of the glass fiber laminate h1 = 4.4 mm, the glass fiber laminate is rectangular, the width is equal to the sum of the transverse period lengths of 33 carbon fiber array units 297 mm (9 mm × 33), and the length is equal to the longitudinal (x direction) dimension l of the multi-level carbon fiber absorbing material x =300mm.

[0050] The thickness of the carbon fiber laminate is h2 = 0.5 mm. The carbon fiber laminate is rectangular, and its width is equal to the transverse period length p of the carbon fiber array unit. y =9mm, and its length is equal to the longitudinal dimension of the multi-level carbon fiber absorbing material (300mm).

[0051] The height h3 of the carbon fiber array unit is 3.62 mm.

[0052] The conductivity of the carbon fiber strip along the fiber direction is set to 3.5×10 4 S / m, the conductivity perpendicular to the fiber direction was set to 89 S / m;

[0053] The 15 carbon fiber strips in the carbon fiber array unit grow linearly from top to bottom in the vertical direction, with the longest width w n =8mm, shortest width w1 =1mm, carbon fiber strip width gradient d w =0.5mm, the height of each carbon fiber strip is s=0.125mm, the spacing between two adjacent carbon fiber strips is t=0.125mm, the distance between two adjacent carbon fiber array units is d=1mm, and the carbon fiber strips remain continuous along the fiber direction.

[0054] The preparation method is as follows:

[0055] The single-layer glass fiber board is cut according to the designed size of each layer of carbon fiber strips, so that the single-layer glass fiber board is completely cut through in the thickness direction to form through holes, and the carbon fiber strips are embedded in the aforementioned holes of corresponding sizes to obtain a mixed single-layer board;

[0056] According to the direction of the increase of the width of the carbon fiber strips, a plurality of mixed single-layer boards and a plurality of blank single-layer boards are stacked in a manner of alternately laying a layer of mixed single-layer board and a layer of single-layer glass fiber board (blank single-layer board), and then bonded together with an adhesive to obtain a glass fiber laminate 1 (i.e., a transmission medium matrix); 33 carbon fiber array units 3 are arranged inside the transmission medium matrix, and each carbon fiber array unit 3 is composed of 15 carbon fiber strips distributed in a gradient;

[0057] The glass fiber laminate 1 is adhered to the upper surface of the carbon fiber laminate 2 (reflection layer) with an adhesive, and cured for 2 hours at a pressure of 1 bar and a temperature of 120° C. to obtain the multi-level carbon fiber absorbing material.

[0058] Test Example 1 Simulation Test

[0059] The electromagnetic performance of the multi-level carbon fiber absorbing material obtained in Example 1 was simulated and tested, and the results are as follows: Figure 3 As shown. Figure 3 It can be seen that within the incident angle range of 0 to 70°, the average absorption rate of the multi-level carbon fiber absorbing material to electromagnetic waves in the 5 to 18 GHz frequency band is higher than 85%, and within the incident angle range of 30-70°, the absorption rate of electromagnetic waves in the above frequency band is higher than 85%, and it has a broadband and large angular absorption effect.

[0060] Comparative Example 1

[0061] It is basically the same as Example 1, except that no holes are opened to embed the carbon fiber array unit. The obtained product is named #1 material.

[0062] Comparative Example 2

[0063] The metamaterial absorber described in the literature "DING F, CUI YX, GE XC, et al. Ultra-broadband microwave metamaterial absorber [J]. Applied Physics Letters, 2012, 100: 103506" is named #2 material.

[0064] Test Example 2: Wave Absorption Performance Test

[0065] The bow method was used to test the absorbing performance of the multi-level carbon fiber absorbing material obtained in Example 1, the #1 material obtained in Comparative Example 1, and the #2 material obtained in Comparative Example 2. The test method refers to the following literature: Zhang Haiyan, Duan Yuping. Development of microwave parameter variable temperature test system for absorbing materials [D]. Dalian: Dalian University of Technology, 2023: 13-15. The results are as follows Figure 4 shown.

[0066] Depend on Figure 4 It can be seen that the average electromagnetic wave absorption rate of the multi-level carbon fiber absorbing material obtained in Example 1 is 91%, the average electromagnetic wave absorption rate of the #1 material obtained in Comparative Example 1 is 13%, and the average electromagnetic wave absorption rate of the #2 material obtained in Comparative Example 2 is 82%. It can be seen that the laminated structure material without opening holes and embedding carbon fiber array units has almost no electromagnetic wave absorption ability for 4-18GHz electromagnetic waves, while the wave absorption performance of the laminated structure material obtained after opening holes and embedding carbon fiber array units is greatly improved.

[0067] Test Example 3 Mechanical Properties Test

[0068] The tensile bearing properties of the multi-level carbon fiber absorbing material obtained in Example 1 and the #1 material obtained in Comparative Example 1 were tested with reference to the tensile test standard ASTM D3039M-17. The results are as follows: Figure 5 shown.

[0069] Depend on Figure 5 It can be seen that the stiffness of the multi-level carbon fiber absorbing material obtained in Example 1 is 13.30 kN / mm, and the ultimate stress is 591.4 MPa; the stiffness of the #1 material obtained in Comparative Example 1 is 8.831 kN / mm, and the ultimate stress is 355.8 MPa. It can be seen that compared with the laminated structural material without opening holes and embedding carbon fiber array units, the tensile strength and tensile stiffness of the laminated structural material obtained after opening holes and embedding carbon fiber array units are greatly improved.

[0070] The multi-level carbon fiber absorbing material obtained in Example 1 and the #1 material obtained in Comparative Example 1 were tested according to the three-point bending test standard ASTM D7264M-21. The results are as follows: Figure 6 As shown. Figure 6 It can be seen that the stiffness of the multi-level carbon fiber absorbing material obtained in Example 1 is 69.87 N / mm, and the ultimate load is 1403 MPa; the stiffness of the #1 material obtained in Comparative Example 1 is 43.86 kN / mm, and the ultimate load is 816 N. It can be seen that compared with the laminated structural material without opening holes and embedding carbon fiber array units, the bending strength and bending stiffness of the laminated structural material obtained after opening holes and embedding carbon fiber array units are greatly improved.

[0071] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A multi-level carbon fiber absorbing material, characterized in that: It comprises a reflective layer and an electromagnetic functional layer arranged on one side of the reflective layer; the electromagnetic functional layer comprises a transmission medium matrix and a plurality of carbon fiber array units arranged inside the transmission medium matrix, each carbon fiber array unit is composed of a plurality of carbon fiber strips with a width gradient distribution, the carbon fiber strips are continuous along the fiber direction, and the widest carbon fiber strip in the carbon fiber array unit is close to the reflective layer.

2. The multi-level carbon fiber absorbing material according to claim 1, characterized in that: The electrical conductivity of the carbon fiber strip along the fiber direction is 32000-38000 S / m, and the electrical conductivity perpendicular to the fiber direction is 85-94 S / m.

3. The multi-level carbon fiber absorbing material according to claim 1, characterized in that: In each carbon fiber array unit, the width of the carbon fiber strip increases linearly and continuously from top to bottom along the vertical direction, the width of the top carbon fiber strip is 0.5-2.0 mm, the width of the bottom carbon fiber strip is 7.5-9.0 mm, and the width gradient of the carbon fiber strip is 0.2-1.0 mm.

4. The multi-level carbon fiber absorbing material according to claim 1 or 3, characterized in that: In each carbon fiber array unit, the upper and lower spacing between two adjacent layers of carbon fiber strips is 0.1 to 0.5 mm.

5. The multi-level carbon fiber absorbing material according to claim 1, characterized in that: When there are multiple carbon fiber array units, the multiple carbon fiber array units are periodically arranged in the horizontal direction, and the distance between the widest carbon fiber strips in two adjacent carbon fiber array units is 1 to 2 mm.

6. The multi-level carbon fiber absorbing material according to claim 1 or 5, characterized in that: The number of the carbon fiber array units in the transverse direction is 33 to 36, and the number in the longitudinal direction is 1.

7. The multi-level carbon fiber absorbing material according to claim 1, characterized in that: The transmission medium matrix is ​​a glass fiber laminate, an aramid fiber laminate or a basalt fiber laminate; the height of the transmission medium matrix is ​​4.0-4.8 mm.

8. The multi-level carbon fiber absorbing material according to claim 1, characterized in that: The reflective layer is a carbon fiber laminate, a graphene laminate or a carbon nanotube laminate; the height of the reflective layer is 0.25-0.5 mm.

9. The method for preparing the multi-level carbon fiber absorbing material according to any one of claims 1 to 8, comprising the following steps: According to the structure of the electromagnetic functional layer, a plurality of carbon fiber array units are embedded in a transmission medium matrix to obtain the electromagnetic functional layer; The reflective layer and the electromagnetic functional layer are stacked and assembled, and the widest carbon fiber strip in the carbon fiber array unit is placed close to the reflective layer to obtain the multi-level carbon fiber absorbing material.

10. Use of the multi-level carbon fiber absorbing material according to any one of claims 1 to 8 or the multi-level carbon fiber absorbing material obtained by the preparation method according to claim 9 in stealth materials.

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