A broadband wave-absorbing material and a preparation method thereof

Abstract

The application discloses a broadband wave-absorbing material and a preparation method thereof. The broadband wave-absorbing material comprises three-prism three-dimensional structure fibers. In the thickness direction of the broadband wave-absorbing material, the three-prism three-dimensional structure fibers comprise a wave-transparent layer and a wave-absorbing layer. The material of the wave-transparent layer comprises a fiber cloth, and the material of the wave-absorbing layer comprises a wave-absorbing fiber cloth. The broadband wave-absorbing material provided by the application can be integrally formed without layering. The three-prism three-dimensional structure is used to enhance the broadband wave-absorbing material. The shape units of the reinforcing bodies of each surface are all triangles. The triangle is the most stable shape in nature. Therefore, the obtained broadband wave-absorbing material not only has a broadband stealth performance, but also has higher mechanical properties as a whole. In particular, the layer shear force can reach 40-55 MPa and can be kept stable for a long time. Meanwhile, other mechanical properties such as tensile, compression and bending are also significantly improved under the enhancement of the three-prism three-dimensional structure fibers and the integral forming.

Description

Technical Field

[0001] This invention relates to the field of microwave absorbing materials technology, specifically to a broadband microwave absorbing material and its preparation method. Background Technology

[0002] Broadband absorbing materials are one of the important technical approaches to achieving stealth in weaponry and equipment, and also the material basis for absorbing radar waves. Without altering the target's shape, weapons and equipment using broadband absorbing materials can significantly reduce their signal signature and detectability, thereby improving their survivability and increasing their offensive capabilities.

[0003] Broadband absorbing materials occupy an important position among broadband absorbing materials. Compared with other broadband absorbing materials, broadband absorbing materials are structural broadband absorbing materials that can simultaneously absorb waves and bear loads. They can meet stealth requirements while greatly reducing the structural weight of weapons and equipment. They have received high attention both domestically and internationally and have rapidly developed into engineering applications.

[0004] With the improvement of weapon performance and the need for rapid strike capability, the speeds of cruise missiles, surface-to-surface missiles, and air-to-air missiles have reached Mach 5 or higher, and future spaceplanes will operate at speeds approaching Mach 10. Due to the heat generated by the drilling machine and the influence of air resistance, the surface temperature of the aircraft will rise sharply during flight, which places high-temperature resistance requirements on electromagnetic window materials subjected to intense aerodynamic heating. However, judging from the current research status of broadband microwave absorbing materials, most broadband microwave absorbing materials currently adopt a layer-by-layer fiber lay-up method. In this method, each layer is reinforced with fiber reinforcements to enhance tensile properties, but the shear strength between layers relies solely on the adhesive without any other reinforcements for support. Therefore, the layer shear strength is far from meeting the actual requirements and needs further improvement. Summary of the Invention

[0005] The main objective of this invention is to propose a broadband absorbing material and its preparation method, aiming to improve the shear strength of the broadband absorbing material.

[0006] To achieve the above objectives, the present invention proposes a broadband absorbing material, which includes a triangular pyramidal three-dimensional structure fiber. In the thickness direction of the broadband absorbing material, the triangular pyramidal three-dimensional structure fiber includes a wave-transparent layer and a wave-absorbing layer. The wave-transparent layer is made of fiber cloth, and the wave-absorbing layer is made of wave-absorbing fiber cloth.

[0007] Optionally, the triangular pyramid in the triangular pyramidal solid structure is a regular tetrahedron.

[0008] Optionally, the side length of the regular tetrahedron is 0.1 to 0.3 mm.

[0009] Optionally, the thickness of the broadband absorbing material is 2-5 mm, the thickness of the wave-transmitting layer is 1-4 mm, and the thickness of the absorbing layer is 1-4 mm.

[0010] Optionally, the material constituting the fiber cloth includes at least one of glass fiber, quartz fiber and basalt fiber.

[0011] Optionally, the microwave absorbing fiber cloth includes a fiber cloth substrate and an absorbent, wherein the absorbent includes at least one of conductive carbon black and carbon nanotubes, and the material constituting the fiber cloth substrate includes at least one of glass fiber, quartz fiber and basalt fiber.

[0012] Optionally, the mass concentration of the absorbent in the microwave-absorbing fiber cloth is 1-8%.

[0013] Furthermore, the present invention also proposes a method for preparing the broadband absorbing material as described above, comprising the following steps:

[0014] A three-dimensional weaving model is designed based on the thickness of the wave-transmitting layer and the wave-absorbing layer;

[0015] According to the weaving model, fiber cloth and wave-absorbing fiber with triangular pyramidal three-dimensional structure are woven respectively;

[0016] The fiber cloth and the microwave absorbing fiber cloth are stacked together, and the vertices of the triangular pyramid at their contact surfaces are tied together to connect the fiber cloth and the microwave absorbing fiber cloth to form the triangular pyramid three-dimensional fiber structure.

[0017] The triangular pyramidal three-dimensional fiber is placed in a mold, an adhesive is injected, and then it is molded into a single piece to obtain a broadband absorbing material.

[0018] Optionally, in the step of placing the triangular pyramidal three-dimensional structure fiber in a mold, injecting adhesive, and then molding it integrally to obtain a broadband absorbing material:

[0019] In the molding process, the molding temperature is 80-150℃, the molding pressure is 2-5MPa, and the molding time is 2-8h.

[0020] Optionally, in the step of placing the triangular pyramidal three-dimensional structure fiber in a mold, injecting adhesive, and then molding it integrally to obtain a broadband absorbing material:

[0021] The adhesive comprises E51 resin and an amine curing agent.

[0022] In the technical solution provided by this invention, the broadband absorbing material comprises a triangular pyramidal three-dimensional structure fiber. In the thickness direction of the broadband absorbing material, the triangular pyramidal three-dimensional structure fiber comprises a wave-transmitting layer and a wave-absorbing layer. The wave-transmitting layer is made of fiber cloth, and the wave-absorbing layer is made of wave-absorbing fiber cloth. Thus, the broadband absorbing material can be integrally molded without layering. By using the triangular pyramidal three-dimensional structure to reinforce the broadband absorbing material, the reinforcing body shape unit on each face is a triangle. Since the triangle is the most stable shape in nature, the resulting broadband absorbing material not only possesses broadband stealth performance but also exhibits higher overall mechanical properties, especially a layer shear force that can reach 40–55 MPa and remain stable over a long period. Simultaneously, its tensile, compressive, and bending mechanical properties are significantly improved through the reinforcement of the triangular pyramidal three-dimensional structure fiber and the integral molding process. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A schematic diagram of the smallest structural unit of the triangular pyramidal three-dimensional structure in the broadband absorbing material provided by the present invention;

[0025] Figure 2 This is a schematic diagram of the structure of the wave-transmitting layer or wave-absorbing layer in the broadband absorbing material provided by the present invention.

[0026] Figure 3 This is a schematic diagram of the structure of the broadband absorbing material provided by the present invention;

[0027] Figure 4 This is a schematic flowchart of an embodiment of the method for preparing broadband absorbing materials provided by the present invention.

[0028] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially. Furthermore, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, or solution B, or a solution where both A and B are satisfied simultaneously. In addition, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] From the current research status of broadband absorbing materials, most broadband absorbing materials currently adopt a layer-by-layer fiber layup method. In this method, each layer is reinforced by fiber reinforcement to enhance tensile properties, but the shear strength between layers relies solely on the adhesive without any other reinforcement. Therefore, the layer shear strength is far from meeting the actual requirements and needs further improvement.

[0031] In view of this, the present invention proposes a broadband absorbing material, and designs the structure of the broadband absorbing material so that it can be integrally molded, thereby improving its layer shear strength. See reference. Figures 1 to 3 The image shows an embodiment of the broadband absorbing material provided by the present invention. In this embodiment, the broadband absorbing material includes a triangular pyramidal three-dimensional structure fiber. In the thickness direction of the broadband absorbing material, the triangular pyramidal three-dimensional structure fiber includes a wave-transmitting layer and a wave-absorbing layer. The wave-transmitting layer is made of fiber cloth, and the wave-absorbing layer is made of wave-absorbing fiber cloth.

[0032] In the technical solution provided by this invention, the broadband absorbing material comprises a triangular pyramidal three-dimensional structure fiber. In the thickness direction of the broadband absorbing material, the triangular pyramidal three-dimensional structure fiber comprises a wave-transmitting layer and a wave-absorbing layer. The wave-transmitting layer is made of fiber cloth, and the wave-absorbing layer is made of wave-absorbing fiber cloth. Thus, the broadband absorbing material can be integrally molded without layering. By using the triangular pyramidal three-dimensional structure to reinforce the broadband absorbing material, the reinforcing body shape unit on each face is a triangle. Since the triangle is the most stable shape in nature, the resulting broadband absorbing material not only possesses broadband stealth performance but also exhibits higher overall mechanical properties, especially a layer shear force that can reach 40–55 MPa and remain stable over a long period. Simultaneously, its tensile, compressive, and bending mechanical properties are significantly improved through the reinforcement of the triangular pyramidal three-dimensional structure fiber and the integral molding process.

[0033] See Figure 1 The diagram shown is a schematic representation of the smallest unit in the triangular pyramidal three-dimensional structure described in this invention. The triangular pyramidal three-dimensional structure is composed of a large number of triangular pyramids, and the structure of the wave-transmitting layer and / or the wave-absorbing layer formed is as follows: Figure 2 As shown, the final combined structure is as follows Figure 3 The fiber has a triangular pyramidal three-dimensional structure.

[0034] In some embodiments of the present invention, the triangular pyramid in the triangular pyramidal solid structure is a regular tetrahedron, which makes structural design easier, simplifies subsequent production processes, and enhances structural stability.

[0035] Furthermore, in some embodiments of the present invention, the side length of the regular tetrahedron is 0.1 to 0.3 mm.

[0036] In some embodiments of the present invention, the thickness of the broadband absorbing material is 2-5 mm, the thickness of the wave-transmitting layer is 1-4 mm, and the thickness of the wave-absorbing layer is 1-4 mm. It should be noted that the thicknesses of the wave-transmitting layer and the wave-absorbing layer can be the same or different, as long as the thicknesses of both the wave-transmitting layer and the wave-absorbing layer are within the range of 1-4 mm, and the total thickness of the broadband absorbing material is 2-5 mm.

[0037] The fiber cloth is formed by weaving fiber raw materials, such as... Figure 2The structure shown indicates that the material constituting the fiber cloth includes at least one of glass fiber, quartz fiber, and basalt fiber. It can be any one of these fibers, or a combination of any two or three of them; that is, the fiber cloth is woven from a mixture of two or three of the aforementioned fibers. It should be noted that when the material constituting the fiber cloth is a combination, the proportion of each fiber raw material is not limited and can be flexibly adjusted according to actual conditions. In some embodiments of the present invention, it is preferred that the material constituting the fiber cloth includes any one of glass fiber, quartz fiber, and basalt fiber.

[0038] The microwave-absorbing fiber cloth is formed by weaving microwave-absorbing fiber raw materials, such as... Figure 2 The described structure, the microwave-absorbing fiber cloth, comprises a fiber cloth substrate and an absorbent. The absorbent includes at least one of conductive carbon black and carbon nanotubes. The material constituting the fiber cloth substrate includes at least one of glass fiber, quartz fiber, and basalt fiber. That is, the microwave-absorbing fiber cloth is woven from fiber raw materials compounded with an absorbent. The fiber raw materials can be any one of glass fiber, quartz fiber, and basalt fiber, or a combination of any two or three of them; that is, it is woven from a mixture of two or three fiber raw materials. The absorbent can be any one of conductive carbon black and carbon nanotubes, or a mixture of both. It should be noted that when the fiber raw materials and / or the absorbent are a combination, the combination ratio of each raw material is not limited and can be flexibly adjusted according to actual conditions. Furthermore, the fiber raw materials constituting the fiber cloth and the fiber raw materials constituting the microwave-absorbing fiber cloth can be the same or different, both falling within the scope of protection of this invention.

[0039] In the microwave absorbing fiber, the concentration of the microwave absorbing agent can be set according to the actual application requirements of the broadband microwave absorbing material. In some embodiments of the present invention, the mass concentration of the absorber in the microwave absorbing fiber cloth is 1 to 8%.

[0040] In some embodiments of the present invention, multiple absorbing layers may be provided. In this case, the absorbing agents in each absorbing layer may be the same or different from each other, both of which are within the scope of protection of the present invention. One way to obtain multiple absorbing layers is, for example, to combine multiple layers of woven absorbing fiber cloth with a triangular pyramidal three-dimensional structure by weaving to form multiple absorbing layers.

[0041] Furthermore, the present invention also proposes a method for preparing the broadband absorbing material as described above. Figure 4 The illustration shows an embodiment of the improved broadband absorbing material preparation method of the present invention, which specifically includes the following steps:

[0042] Step S10: Design a three-dimensional weaving model based on the thickness of the wave-transmitting layer and the wave-absorbing layer;

[0043] Step S20: Weave fiber cloth and wave-absorbing fiber with triangular pyramidal three-dimensional structure according to the weaving model respectively;

[0044] Step S30: Stack the fiber cloth and the microwave absorbing fiber cloth, and tie a knot at the vertices of the triangular pyramid at their contact surfaces to connect the fiber cloth and the microwave absorbing fiber cloth to form the triangular pyramid three-dimensional fiber structure.

[0045] Step S40: Place the triangular pyramidal three-dimensional structure fiber in a mold, inject adhesive, and then mold it into a single piece to obtain a broadband absorbing material.

[0046] First, based on the performance requirements of the broadband absorbing material, its total thickness, wave-transmitting layer thickness, wave-absorbing layer thickness, and absorber concentration are designed, and a three-dimensional weaving model is designed according to the aforementioned design parameters. Then, weaving is performed according to the designed weaving model to obtain fiber cloth and wave-absorbing fiber cloth with triangular pyramidal three-dimensional structures, respectively. Next, the woven fiber cloth and wave-absorbing fiber cloth are stacked, and the vertices of the triangular pyramids at the contact surfaces of the two fiber layers are knotted. Thus, the fiber cloth and wave-absorbing fiber cloth are connected together through the final weaving step, forming a structure as shown below. Figure 3 The illustrated triangular pyramidal three-dimensional fiber structure includes a wave-transmitting layer composed of the fiber cloth and a wave-absorbing layer composed of the wave-absorbing fiber cloth. Finally, a composite molding process is performed. The woven triangular pyramidal three-dimensional fiber structure is evenly laid in a designed mold, and an adhesive is injected into the mold to fill the gaps in the entire triangular pyramidal three-dimensional fiber structure. Then, it is molded into a single piece to obtain the broadband wave-absorbing material. When multiple wave-absorbing layers are provided, they can also be composited by knotting the vertices of the triangular pyramids at the contact surfaces of adjacent fiber layers, thus forming multiple wave-absorbing layers.

[0047] The preparation method provided by this invention realizes the integral molding of broadband absorbing materials, and the reinforcement is achieved by a triangular pyramidal three-dimensional structure, which greatly improves the layer shear force of broadband absorbing materials and effectively solves the problem of insufficient layer shear force in current layered broadband absorbing materials.

[0048] In some embodiments of the present invention, the molding process is characterized by a molding temperature of 80–150°C, a molding pressure of 2–5 MPa, and a molding time of 2–8 h.

[0049] In some embodiments of the present invention, the adhesive comprises E51 resin and an amine curing agent. More specifically, the mass ratio of the E51 resin to the amine curing agent is 100:33.

[0050] The technical solution of the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that the following embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0051] Example 1

[0052] (1) Based on the performance requirements of broadband absorbing materials, the total thickness of broadband absorbing materials is designed to be 2mm. The thickness of the wave-transmitting layer is 1mm, which is composed of quartz fiber cloth, and the thickness of the wave-absorbing layer is 1mm, which is composed of wave-absorbing fiber cloth with a conductive carbon black mass concentration of 5%. The stacking sequence is: quartz fiber cloth → conductive carbon black wave-absorbing fiber cloth; the substrate of the wave-absorbing fiber cloth is quartz fiber.

[0053] (2) Design a three-dimensional weaving model. The three-dimensional structure of the triangular pyramid is a regular tetrahedron with a side length of 0.244 mm. The wave-transmitting layer is made of quartz fiber triangular pyramid three-dimensional weaving, and the wave-absorbing layer is made of conductive carbon black wave-absorbing fiber triangular pyramid three-dimensional weaving.

[0054] (3) Stack the wave-transmitting layer and wave-absorbing layer obtained by weaving in sequence, and tie the apex of the triangular pyramid at the contact surface of the two layers of fibers to form a triangular pyramid three-dimensional fiber structure.

[0055] (4) The woven triangular pyramidal three-dimensional structure fiber is placed into a mold, and an adhesive (E51 resin and amine curing agent with a mass ratio of 100:33) is injected into the mold. Then, it is molded using a flat vulcanizing machine with a molding temperature of 80°C, a molding pressure of 5MPa, and a molding time of 8h to obtain a broadband absorbing material.

[0056] Testing revealed that the prepared broadband absorbing material exhibits a reflectivity of ≤-16dB in the 26.5–40GHz band and a shear strength of 43–48 MPa.

[0057] Example 2

[0058] (1) Based on the performance requirements of broadband absorbing materials, the total thickness of broadband absorbing materials is designed to be 5mm. Among them, the thickness of the wave-transmitting layer is 4mm, which is composed of quartz fiber cloth, and the thickness of the wave-absorbing layer is 1mm, which is composed of wave-absorbing fiber cloth with a conductive carbon black mass concentration of 5%. The stacking sequence is: quartz fiber cloth → conductive carbon black wave-absorbing fiber cloth; the substrate of the wave-absorbing fiber cloth is quartz fiber.

[0059] (2) Design a three-dimensional weaving model. The triangular pyramid in the three-dimensional structure is a regular tetrahedron with a side length of 0.122 mm. The wave-transmitting layer is made of quartz fiber triangular pyramid three-dimensional weaving, and the wave-absorbing layer is made of conductive carbon black wave-absorbing fiber triangular pyramid three-dimensional weaving.

[0060] (3) Stack the wave-transmitting layer and wave-absorbing layer obtained by weaving in sequence, and tie the apex of the triangular pyramid at the contact surface of the two layers of fibers to form a triangular pyramid three-dimensional fiber structure.

[0061] (4) The woven triangular pyramidal three-dimensional structure fiber is placed into a mold, and an adhesive (E51 resin and amine curing agent with a mass ratio of 100:33) is injected into the mold. Then, it is molded using a flat vulcanizing machine with a molding temperature of 90°C, a molding pressure of 4MPa, and a molding time of 6h to obtain a broadband absorbing material.

[0062] Testing revealed that the prepared broadband absorbing material exhibits a reflectivity of ≤-6dB in the 4–12 GHz band, with a reflectivity of ≤-9dB in the 8–12 GHz band, and a shear strength of 45–50 MPa.

[0063] Example 3

[0064] (1) Based on the performance requirements of broadband absorbing materials, the total thickness of the broadband absorbing material is designed to be 5mm. Among them, the thickness of the wave-transmitting layer is 1mm, which is composed of basalt fiber cloth. The thickness of the absorbing layer is 4mm, which is composed of absorbing fiber cloth with a thickness of 2mm and a conductive carbon black mass concentration of 1%, absorbing fiber cloth with a thickness of 1mm and a conductive carbon black mass concentration of 3%, and absorbing fiber cloth with a thickness of 1mm and a conductive carbon black mass concentration of 5%. The stacking sequence is: basalt fiber cloth → conductive carbon black absorbing fiber cloth with a mass concentration of 1% → conductive carbon black absorbing fiber cloth with a mass concentration of 3% → conductive carbon black absorbing fiber cloth with a mass concentration of 5%. The substrate of the absorbing fiber cloth is basalt fiber.

[0065] (2) Design a three-dimensional weaving model. The triangular pyramid in the three-dimensional structure is a regular tetrahedron with a side length of 0.122 mm. The wave-transmitting layer is made of basalt fiber triangular pyramid three-dimensional weaving. The wave-absorbing layer is divided into three layers. The first layer is made of conductive carbon black wave-absorbing fiber triangular pyramid three-dimensional weaving with a mass concentration of 1%. The second layer is made of conductive carbon black wave-absorbing fiber triangular pyramid three-dimensional weaving with a mass concentration of 3%. The third layer is made of conductive carbon black wave-absorbing fiber triangular pyramid three-dimensional weaving with a mass concentration of 5%.

[0066] (3) Stack the wave-transmitting layer and wave-absorbing layer obtained by weaving in sequence, and tie the apex of the triangular pyramid at the contact surface of the two layers of fibers to form a triangular pyramid three-dimensional fiber structure.

[0067] (4) The woven triangular pyramidal three-dimensional structure fiber is placed into a mold, and an adhesive (E51 resin and amine curing agent with a mass ratio of 100:33) is injected into the mold. Then, it is molded using a flat vulcanizing machine with a molding temperature of 100℃, a molding pressure of 3MPa, and a molding time of 5h to obtain a broadband absorbing material.

[0068] Testing revealed that the prepared broadband absorbing material exhibits a reflectivity of ≤-12dB in the 8–18GHz band and a shear strength of 45–47 MPa.

[0069] Example 4

[0070] (1) Based on the performance requirements of the broadband absorbing material, the total thickness of the broadband absorbing material is designed to be 4mm. The thickness of the wave-transmitting layer is 1.5mm, which is composed of glass fiber cloth. The thickness of the absorbing layer is 2.5mm, which is composed of absorbing fiber cloth with a thickness of 2mm and a mass concentration of 4% conductive carbon black, and absorbing fiber cloth with a thickness of 0.5mm and a mass concentration of 5% conductive carbon black. The stacking sequence is: glass fiber cloth → absorbing fiber cloth with a mass concentration of 4% conductive carbon black → absorbing fiber cloth with a mass concentration of 5% conductive carbon black. The substrate of the absorbing fiber cloth is glass fiber.

[0071] (2) Design a three-dimensional braided model. The triangular pyramid in the three-dimensional structure is a regular tetrahedron with a side length of 0.122 mm. The wave-transmitting layer is made of glass fiber triangular pyramid three-dimensional braid. The wave-absorbing layer is divided into two layers. The first layer is made of conductive carbon black wave-absorbing fiber triangular pyramid three-dimensional braid with a mass concentration of 4%, and the second layer is made of conductive carbon black wave-absorbing fiber triangular pyramid three-dimensional braid with a mass concentration of 5%.

[0072] (3) Stack the wave-transmitting layer and wave-absorbing layer obtained by weaving in sequence, and tie the apex of the triangular pyramid at the contact surface of the two layers of fibers to form a triangular pyramid three-dimensional fiber structure.

[0073] (4) The woven triangular pyramidal three-dimensional structure fiber is placed into a mold, and an adhesive (E51 resin and amine curing agent with a mass ratio of 100:33) is injected into the mold. Then, it is molded using a flat vulcanizing machine with a molding temperature of 120°C, a molding pressure of 2MPa, and a molding time of 4h to obtain a broadband absorbing material.

[0074] Testing revealed that the prepared broadband absorbing material exhibits a reflectivity of ≤-20dB in the 26.5–40GHz band, and its layer shear strength reaches 48–50 MPa.

[0075] Example 5

[0076] (1) Based on the performance requirements of broadband absorbing materials, the total thickness of broadband absorbing materials is designed to be 3mm. The thickness of the wave-transmitting layer is 1mm, which is composed of quartz fiber cloth, and the thickness of the wave-absorbing layer is 2mm, which is composed of wave-absorbing fiber cloth with a carbon nanotube mass concentration of 8%. The stacking sequence is: quartz fiber cloth → carbon nanotube wave-absorbing fiber cloth; the substrate of the wave-absorbing fiber cloth is quartz fiber.

[0077] (2) Design a three-dimensional braided model. The triangular pyramid in the three-dimensional structure is a regular tetrahedron with a side length of 0.244 mm. The wave-transmitting layer is made of quartz fiber triangular pyramid three-dimensional braid, and the wave-absorbing layer is made of nano carbon tube wave-absorbing fiber triangular pyramid three-dimensional braid.

[0078] (3) Stack the wave-transmitting layer and wave-absorbing layer obtained by weaving in sequence, and tie the apex of the triangular pyramid at the contact surface of the two layers of fibers to form a triangular pyramid three-dimensional fiber structure.

[0079] (4) The woven triangular pyramidal three-dimensional structure fiber is placed into a mold, and an adhesive (E51 resin and amine curing agent with a mass ratio of 100:33) is injected into the mold. Then, it is molded using a flat vulcanizing machine with a molding temperature of 150°C, a molding pressure of 2MPa, and a molding time of 2h to obtain a broadband absorbing material.

[0080] Testing revealed that the prepared broadband absorbing material exhibits a reflectivity of ≤-6dB in the 8–18 GHz band, with a reflectivity of ≤-10dB in the 8–12 GHz band, and a shear strength of 50–55 MPa.

[0081] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the patent protection scope of the present invention.

Claims

1. A broadband absorbing material, characterized in that, The broadband absorbing material includes a triangular pyramidal three-dimensional structure fiber. In the thickness direction of the broadband absorbing material, the triangular pyramidal three-dimensional structure fiber includes a wave-transmitting layer and a wave-absorbing layer. The wave-transmitting layer is made of fiber cloth, and the wave-absorbing layer is made of wave-absorbing fiber cloth. The fiber cloth is made of at least one of glass fiber, quartz fiber, and basalt fiber. The method for preparing the broadband absorbing material includes the following steps: A three-dimensional weaving model is designed based on the thickness of the wave-transmitting layer and the wave-absorbing layer; According to the weaving model, fiber cloth and wave-absorbing fiber cloth with triangular pyramidal three-dimensional structure are woven respectively; The fiber cloth and the microwave absorbing fiber cloth are stacked together, and the vertices of the triangular pyramid at their contact surfaces are tied together to connect the fiber cloth and the microwave absorbing fiber cloth to form the triangular pyramid three-dimensional fiber structure. The triangular pyramidal three-dimensional fiber is placed in a mold, an adhesive is injected, and then it is molded into a single piece to obtain a broadband absorbing material.

2. The broadband absorbing material as described in claim 1, characterized in that, The triangular pyramid in the aforementioned triangular pyramidal solid structure is a regular tetrahedron.

3. The broadband absorbing material as described in claim 2, characterized in that, The side length of the regular tetrahedron is 0.1~0.3mm.

4. The broadband absorbing material as described in claim 1, characterized in that, The thickness of the broadband absorbing material is 2-5 mm, the thickness of the wave-transmitting layer is 1-4 mm, and the thickness of the absorbing layer is 1-4 mm.

5. The broadband absorbing material as described in claim 1, characterized in that, The microwave absorbing fiber cloth includes a fiber cloth substrate and an absorbent. The absorbent includes at least one of conductive carbon black and carbon nanotubes. The material constituting the fiber cloth substrate includes at least one of glass fiber, quartz fiber and basalt fiber.

6. The broadband absorbing material as described in claim 5, characterized in that, The absorbent concentration in the microwave absorbing fiber cloth is 1-8%.

7. The broadband absorbing material as described in claim 1, characterized in that, In the method for preparing the broadband absorbing material, the step of placing the triangular pyramidal three-dimensional structure fiber in a mold, injecting an adhesive, and then molding it integrally to obtain the broadband absorbing material is as follows: In the molding process, the molding temperature is 80~150℃, the molding pressure is 2~5MPa, and the molding time is 2~8h.

8. The broadband absorbing material as described in claim 1, characterized in that, In the method for preparing the broadband absorbing material, the step of placing the triangular pyramidal three-dimensional structure fiber in a mold, injecting an adhesive, and then molding it integrally to obtain the broadband absorbing material is as follows: The adhesive comprises E51 resin and an amine curing agent.

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