Heat-insulating and wave-absorbing composite material

Abstract

The utility model discloses a heat-insulating and wave-absorbing composite material which comprises a wave-absorbing layer, the wave-absorbing layer is formed by arranging a plurality of layers of fabrics up and down, each layer of fabrics is formed by distributing wave-absorbing fibers and heat-insulating fibers in a staggered manner, the content of the wave-absorbing fibers in each layer of fabrics is increased layer by layer from top to bottom, and a heat-insulating layer is arranged between every two vertically adjacent layers of fabrics; the plurality of needling parts are arranged in the thickness direction of the fabric and the heat insulation layer and are used for connecting the fabric and the heat insulation layer to form a three-dimensional needling structure; the gap between the fabric and the heat insulation layer is filled with the filling layer. According to the three-dimensional needled structure, the problem of cracking and failure of a multi-layer gradient material can be avoided, the content of the wave-absorbing fibers in the three-dimensional needled structure is increased layer by layer from outside to inside so as to realize impedance gradual change, so that electromagnetic waves can enter the material to the maximum extent, then are progressively increased layer by layer and are lost by the gradually increased wave-absorbing fibers, and the electromagnetic wave absorption effect is improved. And meanwhile, the heat conductivity of the arranged heat insulation layer and the filling layer is very low, and the better heat insulation effect is achieved.

Description

Technical Field

[0001] The utility model belongs to the technical field of microwave absorbing composite materials, and particularly relates to a heat-insulating and microwave absorbing composite material. Background Art

[0002] At present, when aircraft such as supersonic aircraft perform high-Mach flight, the aerodynamic heating generated will cause the surface temperature to rise sharply. In order to protect the personnel and equipment in the cavity, heat-insulating materials need to be used for protection. On the premise that the designability of the aircraft's external shape structure is severely limited, using a functional material with integrated heat insulation and microwave absorption is an effective means to reduce its target characteristics.

[0003] In order to achieve the impedance gradient of the composite material and make the electromagnetic wave enter the material as much as possible and be dissipated, a multi-layer structure in which materials with different impedance characteristics are stacked in layers according to a certain design is generally adopted in the research. It is found in actual use that although this can improve the microwave absorption performance of the material, under various stresses of high-altitude and high-speed flight, the multi-layer material is prone to cracking and delamination, causing potential safety hazards. Therefore, there is an urgent need for a microwave absorbing composite material with good microwave absorption performance and not easy to crack. Summary of the Utility Model

[0004] The purpose of the utility model is to provide a heat-insulating and microwave absorbing composite material to overcome the deficiencies of the prior art. The composite material has good microwave absorption performance, stable structure and not easy to crack, and good heat insulation performance.

[0005] To achieve the above purpose, the technical solution adopted by the utility model is: a heat-insulating and microwave absorbing composite material, comprising:

[0006] A microwave absorption layer, which is formed by stacking multiple layers of fabrics up and down in sequence. Each layer of the fabric is formed by the interlaced distribution of microwave absorption fibers and heat insulation fibers, and the content of microwave absorption fibers in each layer of the fabric increases layer by layer from top to bottom; [[ID=***]]

[0007] A heat insulation layer, and heat insulation layers are provided between two adjacent layers of the fabrics;

[0008] Needling components, and a plurality of the needling components are arranged along the thickness direction of the fabric and the heat insulation layer to pierce and connect the plurality of fabrics and the plurality of heat insulation layers to form a three-dimensional needled structure;

[0009] A filling layer, which is filled in the gaps between the fabrics and the heat insulation layer.

[0010] Further, the filling layer is a ceramic aerogel with a three-dimensional network porous structure.

[0011] Further, the ceramic aerogel is SiC aerogel, SiCN aerogel, or SiBNC aerogel.

[0012] Further, the wave-absorbing fiber is carbon fiber or silicon carbide fiber.

[0013] Further, the heat-insulating fiber is quartz fiber, mullite fiber or aluminum silicate fiber.

[0014] Further, the wave-absorbing fiber and the heat-insulating fiber are in a plain weave or twill weave structure.

[0015] Further, the heat-insulating layer is a short fiber thin felt.

[0016] Further, the needling member is used to pierce and connect the heat-insulating layers, the fabric and the heat-insulating layers adjacent to each other in sequence from top to bottom, or to pierce and connect the adjacent heat-insulating layers and the fabric from top to bottom.

[0017] Due to the application of the above technical solution, the utility model has the following advantages compared with the prior art:

[0018] For the heat-insulating and wave-absorbing composite material of the utility model, the three-dimensional needling structure can avoid the problem of cracking and failure of multi-layer gradient materials. The content of the wave-absorbing fiber increases layer by layer from the surface to the inside in the three-dimensional needling structure to achieve impedance gradient change. The heat-insulating fiber can improve the impedance matching between the composite material and free space, enabling electromagnetic waves to enter the material interior to the greatest extent, and then layer by layer, being dissipated by the gradually increasing wave-absorbing fibers, enhancing the wave-absorbing performance. At the same time, the provided heat-insulating layer and filling layer make the wave-absorbing composite material also have a good heat-insulating effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The following further illustrates the technical solution of the utility model with reference to the drawings:

[0020] Figure 1 is a schematic structural diagram of the utility model;

[0021] Figure 2 is a partial cross-sectional view of the fabric, the heat-insulating layer, the needling member and the filling layer in an embodiment of the utility model;

[0022] Figure 3 is a schematic structural diagram of the fabric in an embodiment of the utility model;

[0023] Figure 4 is a schematic structural diagram of the special-shaped member prepared by the utility model;

[0024] Wherein: fabric 1, heat-insulating layer 2, needling member 3, filling layer 4, wave-absorbing fiber 10, heat-insulating fiber 11. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] To enable those skilled in the art to better understand the solution of this application, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall within the protection scope of this application.

[0026] The utility model provides a heat-insulating and wave-absorbing composite material to solve the problem that in the prior art, in various stresses of high-altitude and high-speed flight, multi-layer materials of wave-absorbing composite materials are prone to cracking and delamination, causing potential safety hazards.

[0027] For ease of understanding, the specific process in the embodiments of this application will be described below. Please refer to Figures 1 to 3 , a heat-insulating and wave-absorbing composite material in the embodiments of this application includes a wave-absorbing layer, a heat-insulating layer 2, a needling component 3, and a filling layer 4; the wave-absorbing layer is formed by arranging multiple layers of fabrics 1 up and down, each layer of the fabric is formed by the staggered distribution of wave-absorbing fibers 10 and heat-insulating fibers 11, and the content of wave-absorbing fibers 10 in each layer of the fabric increases layer by layer from top to bottom. A heat-insulating layer 2 is provided between two adjacent fabrics 1 up and down; multiple needling components 3 are arranged along the thickness direction of the fabric 1 and the heat-insulating layer 2 to connect the fabric 1 and the heat-insulating layer 2 to form a three-dimensional needled structure; the filling layer 4 is filled in the gap between the fabric 1 and the heat-insulating layer 2.

[0028] Furthermore, the filling layer 4 is a ceramic aerogel with a three-dimensional network porous structure. The ceramic aerogel has an extremely high porosity and an extremely low thermal conductivity. The extremely high porosity causes electromagnetic waves to be reflected multiple times inside it, and the propagation path is extended, and then a large amount of attenuation occurs; the extremely low thermal conductivity can make this material have a better heat-insulating effect. The filling layer is used to fill the entire composite material of the utility model, thereby improving its wave-absorbing efficiency.

[0029] Specifically, the ceramic aerogel in this embodiment is SiC aerogel, SiCN aerogel, or SiBNC aerogel. The above aerogels all have a low thermal conductivity and good wave-absorbing performance, and their properties can be adjusted by designing the precursor, changing the pyrolysis temperature, or using a catalyst.

[0030] Furthermore, the wave-absorbing fiber 10 is a carbon fiber or a silicon carbide fiber. Both have good wave-absorbing performance, and the content of wave-absorbing fibers 10 in the fabric 1 increases layer by layer from the outside to the inside in the three-dimensional needled structure, thereby forming a structure with a gradually changing impedance, making the entire composite material have the characteristics of wide frequency and strong absorption.

[0031] Further, the heat-insulating fiber 11 is quartz fiber, mullite fiber or aluminosilicate fiber, which has good heat-insulating performance and a low dielectric constant, and can be used to adjust the impedance characteristics of the composite material.

[0032] In addition, the wave-absorbing fiber 10 and the heat-insulating fiber 11 in this embodiment can be in a plain weave structure or a twill weave structure, and can be set accordingly according to actual needs.

[0033] Further, the heat-insulating layer 2 is a short fiber thin felt, which also has heat-insulating performance and is used to improve the heat-insulating effect of the entire composite material.

[0034] Further, the needling member 3 connects the multi-layer fabric 1 and the multi-layer heat-insulating layer 2 together through a needling process. Specifically, a plurality of needling members 3 are arranged between the thickness directions of the fabric 1 and the heat-insulating layer 2. The needling member 3 can pierce and connect the heat-insulating layer 2, the fabric 1, and the heat-insulating layer 2 that are adjacent to each other in sequence up and down, or can pierce and connect the heat-insulating layer 2 and the fabric 1 that are adjacent up and down. The above structure forms the three-dimensional needling structure of the present utility model. The three-dimensional needling structure can avoid the problem of cracking and failure of the multi-layer gradient material, thereby improving the structural stability of the entire composite material.

[0035] In the heat-insulating and wave-absorbing composite material of the present utility model, the content of the wave-absorbing fiber increases layer by layer from the surface to the inside in the three-dimensional needling structure to achieve impedance gradient. At the same time, the heat-insulating fiber can improve the impedance matching between the composite material and free space, so that electromagnetic waves can enter the material interior to the greatest extent, and then layer by layer, and be attenuated by the gradually increasing wave-absorbing fiber, so as to achieve the purpose of wideband and strong absorption. At the same time, the provided filling layer and heat-insulating layer make this wave-absorbing composite material also have a good heat-insulating effect.

[0036] In actual applications, this heat-insulating and wave-absorbing composite material is not limited to being used as a flat material only, and can be fabricated into special-shaped components.

[0037] The following lists two embodiments to describe the manufacturing methods of making the heat-insulating and wave-absorbing composite material into a flat plate and a special-shaped component.

[0038] Embodiment 1:

[0039] The wave-absorbing fiber is carbon fiber, the heat-insulating fiber is mullite fiber, and the ceramic aerogel is SiC aerogel. The method of fabricating it into a flat plate is as follows:

[0040] (1) Mix and braid carbon fiber and mullite fiber in different proportions into fiber cloth, and arrange them from top to bottom in the order of increasing carbon fiber content. Lay mullite short fiber thin felt between the fiber cloths, and make fiber clusters in the thickness direction through a three-dimensional needling process to form an integrated three-dimensional needling fiber preform;

[0041] (2) Using polycarbosilane as the precursor, divinylbenzene as the crosslinking agent, cyclohexane as the solvent, and adding a Pt catalyst to prepare the precursor solution;

[0042] (3) Vacuum impregnate the precursor solution in step (2) uniformly into the fiber preform in step (1), then crosslink to obtain a wet gel composite, and then vacuum freeze-dry for 24 h. Finally, pyrolyze at 1200 °C for 2 h in an inert atmosphere to obtain the thermal insulation and wave-absorbing composite material.

[0043] Example Two:

[0044] The wave-absorbing fiber is a silicon carbide fiber, the thermal insulation fiber is a quartz fiber, and the ceramic aerogel is a SiCN aerogel. The method for preparing a special-shaped component is as follows:

[0045] (1) Weave silicon carbide fibers and quartz fibers in different proportions into a fiber cloth, and arrange them from top to bottom in the order of increasing silicon carbide fiber content. Lay a quartz short fiber thin felt between the fiber cloths, and use a three-dimensional needle punching process to generate fiber clusters in the thickness direction to form an integrated three-dimensional needle-punched fiber preform;

[0046] (2) Using polysilazane and divinylbenzene as the precursor and crosslinking agent respectively, cyclohexane as the solvent, and adding a Pt complex as the catalyst to prepare the precursor solution;

[0047] (3) Cut the fiber preform in step (1) as required and place it in a designed mold;

[0048] (4) Vacuum impregnate the precursor solution in step (2) uniformly into the fiber preform in step (3), then crosslink to obtain a wet gel composite, and then vacuum freeze-dry for 24 h. Finally, pyrolyze at 1000 °C for 2 h in an inert atmosphere to obtain a special-shaped component that can be used for thermal insulation and wave-absorbing composite materials. Refer to Figure 4 .

[0049] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present application.

Claims

1. A heat-insulating and wave-absorbing composite material, characterized in that Comprising: An electromagnetic wave absorbing layer, which is formed by arranging multiple layers of fabrics one above the other in sequence. Each layer of the fabric is formed by the interlaced distribution of electromagnetic wave absorbing fibers and heat insulating fibers, and the content of the electromagnetic wave absorbing fibers in each layer of the fabric increases layer by layer from top to bottom; A heat insulating layer, and a heat insulating layer is provided between two adjacent layers of the fabrics; Needling components, and a plurality of the needling components are arranged along the thickness direction of the fabric and the heat insulating layer to pierce and connect the plurality of fabrics and the plurality of heat insulating layers to form a three-dimensional needled structure; A filling layer, which is filled in the gap between the fabric and the heat insulating layer.

2. The heat-insulating and wave-absorbing composite material according to claim 1, characterized in that: The filling layer is a ceramic aerogel having a three-dimensional network porous structure.

3. The heat-insulating and wave-absorbing composite material according to claim 1, characterized in that: The electromagnetic wave absorbing fibers are carbon fibers or silicon carbide fibers.

4. The heat-insulating and wave-absorbing composite material according to claim 1, wherein: The heat insulating fibers are quartz fibers, mullite fibers or aluminum silicate fibers.

5. The heat-insulating and wave-absorbing composite material according to claim 1, wherein: The electromagnetic wave absorbing fibers and the heat insulating fibers are in a plain weave or twill weave structure.

6. The heat-insulating and wave-absorbing composite material according to claim 1, wherein: The heat insulating layer is a short fiber thin felt.

7. The heat-insulating and wave-absorbing composite material according to claim 1, characterized in that: The needling components are used to pierce and connect the heat insulating layers, fabrics and heat insulating layers adjacent to each other in sequence from top to bottom or to pierce and connect the adjacent heat insulating layers and fabrics from top to bottom.

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