Carbon-based wave-absorbing coating structure

Abstract

The utility model discloses a carbon-based wave-absorbing coating structure which comprises a first skin layer, a wave-absorbing layer and a second skin layer which are sequentially adhered up and down, the first skin layer, the second skin layer and the wave absorbing layer are connected through adhesive film layers. The wave absorbing layer is a honeycomb core formed by connecting a plurality of honeycomb units; the inner wall of each honeycomb unit is provided with a plurality of layers of gradient-shaped carbon-based wave-absorbing coatings; the gradient carbon-based wave-absorbing coating is similar to a wave-absorbing pyramid structure, electromagnetic waves entering the coating are converted into heat energy through the resonance effect of the carbon-based wave-absorbing coating to be dissipated, and the reflected electromagnetic waves interact in the honeycomb units to generate multiple reflection or interference so as to quickly dissipate the electromagnetic waves. Therefore, the wave absorbing efficiency of electromagnetic waves in the honeycomb units is improved through combined action; and meanwhile, the gradient-shaped carbon-based wave-absorbing coating has a pyramid-like structure, so that the effect of gradually changing impedance is achieved, the wave-absorbing bandwidth is improved, and the use requirements of customers are further met.

Description

Technical Field

[0001] The utility model belongs to the technical field of microwave absorbing materials, and particularly relates to a carbon-based microwave absorbing coating structure. Background Art

[0002] Structural microwave absorbing materials usually include laminated composites, structural filled composites, woven composites, etc. The honeycomb structure is usually used as a sandwich layer and combined with the skin structures on both sides to form a microwave absorbing honeycomb. The honeycomb layer and the skin layer are bonded and cured through an adhesive film. Among them, the microwave absorbing honeycomb layer is usually made by impregnating or filling the honeycombs of wave-transparent materials such as aramid honeycombs, glass fiber honeycombs, and PBO honeycombs with a specific formula of microwave absorbing slurry. At present, most use resistive absorbers to improve the microwave absorbing performance of the composite material. For example, carbon black, graphite, metal powder, etc.

[0003] Although the microwave absorbing honeycomb made of aramid paper honeycomb core material has the advantages of light weight, good strength and stiffness, it can not only bear the load as a structural member, but also absorb electromagnetic waves well. However, in actual use, the existing honeycomb microwave absorbing materials have unsatisfactory microwave absorbing performance and narrow frequency bandwidth, thus unable to meet the actual use requirements. Summary of the Utility Model

[0004] The purpose of the utility model is to provide a carbon-based microwave absorbing coating structure to overcome the deficiencies of the prior art, with good microwave absorbing performance, wide frequency bandwidth and good practicability.

[0005] To achieve the above purpose, the technical scheme adopted by the utility model is: a carbon-based microwave absorbing coating structure, including a first skin layer, a microwave absorbing layer and a second skin layer which are sequentially pasted up and down; the first skin layer, the second skin layer and the microwave absorbing layer are respectively connected through an adhesive film layer; the microwave absorbing layer is a honeycomb core formed by connecting a plurality of honeycomb units; and a multi-layer gradient carbon-based microwave absorbing coating is coated on the inner wall of each honeycomb unit.

[0006] Further, the number of layers of the gradient is at least three.

[0007] Further, the volume ratio of the weight of the carbon-based microwave absorbing coating to the volume of the honeycomb core without the carbon-based microwave absorbing coating is 0.01 - 1 g / cm 3 .

[0008] Further, the material of the honeycomb core is aramid, glass fiber, quartz, PBO.

[0009] Further, the material of the first skin layer is aramid, glass fiber, quartz, PBO.

[0010] Further, the material of the second skin layer is a carbon fiber board.

[0011] Due to the application of the above technical scheme, the utility model has the following advantages compared with the prior art:

[0012] The carbon-based wave-absorbing coating structure of the present utility model has an absorbing layer which is a honeycomb core formed by connecting a number of honeycomb units. A gradient carbon-based wave-absorbing coating is provided on the inner wall of the honeycomb unit. The gradient carbon-based wave-absorbing coating is similar to the structure of an absorbing pyramidal horn. When electromagnetic waves are incident, the electromagnetic waves entering the interior of the coating are dissipated as heat through the "resonance" effect of the carbon-based wave-absorbing coating. The reflected electromagnetic waves interact with each other inside the honeycomb unit to generate multiple reflections or interference, thereby dissipating the electromagnetic waves. The combined effect of these two aspects improves the wave-absorbing efficiency of the electromagnetic waves within the honeycomb unit.

[0013] Secondly, the gradient carbon-based wave-absorbing coating can improve the impedance matching of the overall material. The structure similar to a pyramidal horn achieves the effect of impedance gradual change, improving the wave-absorbing bandwidth. Different gradients and the ratio of the carbon-based wave-absorbing coating can be adjusted according to the technical index requirements of different customers, thereby meeting the usage needs of customers. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The technical solution of the present utility model will be further described below with reference to the accompanying drawings:

[0015] Figure 1 is a three-dimensional structural schematic diagram of an embodiment of the present utility model;

[0016] Figure 2 is a partial structural schematic diagram of the absorbing layer in an embodiment of the present utility model;

[0017] Figure 3 is a structural schematic diagram of the carbon-based wave-absorbing coating provided on the inner wall of the honeycomb unit in an embodiment of the present utility model;

[0018] Figure 4 is the reflectivity of the present utility model at 2 - 18 GHz;

[0019] Wherein: the first skin layer 1, the absorbing layer 2, the second skin layer 3, the adhesive film layer 4, the honeycomb unit 20, the carbon-based wave-absorbing coating 21, the first absorbing coating 30, the second absorbing coating 31, the third absorbing coating 32, the fourth absorbing coating 33, the fifth absorbing coating 34, the sixth absorbing coating 35. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] In order 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 with reference to 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. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of this application.

[0021] The present utility model provides a carbon-based wave-absorbing coating structure to solve the problems of unsatisfactory wave-absorbing performance and narrow wave-absorbing bandwidth of wave-absorbing materials in the prior art.

[0022] For the convenience of understanding, the following describes the specific process in the embodiments of the present application. Please refer to Figures 1 to 2 A carbon-based wave-absorbing coating structure in an embodiment of the present application includes a first skin layer 1, a wave-absorbing layer 2, and a second skin layer 3 that are sequentially pasted up and down; the first skin layer 1, the second skin layer 3, and the wave-absorbing layer 2 are respectively connected by an adhesive film layer 4; the wave-absorbing layer 2 is composed of a honeycomb core formed by connecting a plurality of honeycomb units 20; on the inner wall of each honeycomb unit 20, there are provided multiple layers of gradient carbon-based wave-absorbing coatings 21.

[0023] The present utility model improves the wave-absorbing performance and wave-absorbing bandwidth of the coating structure by coating a carbon-based wave-absorbing coating 21 on the inner wall of the honeycomb unit 20.

[0024] Further, in this embodiment, the gradient number of the carbon-based wave-absorbing coating 21 is at least three layers, and of course, it can also be four layers, which can be set according to the actual wave-absorbing performance. Different numbers of gradient layers will result in corresponding differences in wave-absorbing performance. In this embodiment, the number of gradient layers is three.

[0025] Based on Figure 2 and Figure 3 , in this embodiment, the gradient number of the carbon-based wave-absorbing coating 21 is three. The carbon-based wave-absorbing coating 21 is composed of a first wave-absorbing coating 30, a second wave-absorbing coating 31, and a third wave-absorbing coating 32 that are in a gradient shape and are arranged on the inner wall of the honeycomb unit 20. This has the following advantages: First, after setting the carbon-based wave-absorbing coating 21 composed of the first wave-absorbing coating 30, the second wave-absorbing coating 31, and the third wave-absorbing coating 32, the overall thickness of each honeycomb unit 20 becomes thicker, increasing the dissipation path of electromagnetic waves, so that the carbon-based wave-absorbing coating 21 can dissipate electromagnetic waves to the greatest extent through the "resonance" effect. At the same time, the gradient carbon-based wave-absorbing coating 21 has a structure similar to a pyramidal horn to achieve the effect of impedance gradual change, and the reflected electromagnetic waves interact with each other, so that the wave-absorbing performance is stronger, better meeting the use requirements.

[0026] Secondly, the overall carbon-based wave-absorbing coating 21 is in a gradient shape. At the top part, the width of the carbon-based wave-absorbing coating 21 is small, which is for absorbing high-frequency electromagnetic waves. Then, as it gets closer to the bottom of the carbon-based wave-absorbing coating 21, the width of the carbon-based wave-absorbing coating 21 becomes wider and wider, which is for absorbing low-frequency electromagnetic waves. In this way, the entire structure improves the wave-absorbing bandwidth and meets the use requirements.

[0027] Further, the volume ratio of the weight of the carbon-based wave-absorbing coating to the honeycomb core volume without coating the carbon-based wave-absorbing coating is 0.01 - 1 g / cm 3The thickness of the first skin layer 1 is not less than 0.1 mm, the thickness of the second skin layer 3 is not less than 0.5 mm, and the thickness of the film layer 4 is 0.01-0.2 mm. The specific thickness can be adjusted according to actual conditions.

[0028] The absorbing layer 2 is made of aramid paper, which has high heat resistance, can be used for a long time at a high temperature of 220°C without aging, has good flame retardancy, and has excellent electrical insulation and stable chemical properties.

[0029] Furthermore, in this embodiment, the material of the first skin layer 1 is glass fiber, and the material of the second skin layer 3 is carbon fiber board.

[0030] In addition, in this embodiment, the carbon-based absorbing coating 21 is formed by immersing the absorbing layer 2 in a carbon-based absorbing slurry, and the mass ratio of the carbon-based absorbing slurry is 25-40 parts of absorbent, 30-45 parts of adhesive, 100 parts of solvent, and 1 part of dispersant.

[0031] The absorbent is selected from any one of carbon black, graphene, carbon nanotubes and carbon fibers, or a mixture of any of the above; the adhesive is selected from any one of cellulose derivatives, modified oils, modified polybutadiene resins, epoxy resins, alkyd resins, amino resins, polyester resins, phenolic resins, acrylic resins, polyurethane resins, silicone resins and organic fluorine resins; the solvent is any one of deionized water, methyl ethyl ketone, DMF, ethyl acetate, butyl acetate and other solvents; the dispersant is any one of methyl cellulose, polyvinyl pyrrolidone, sodium carboxymethyl cellulose, BYK2012 and other dispersants.

[0032] An example is listed below for illustration.

[0033] Take 1000g of deionized water, 150g of graphene, 45g of carbon black, 45g of carbon nanotubes, 20g of carbon fiber, 450g of polyurethane resin, and 1g of methyl cellulose; add graphene, carbon black, and carbon nanotubes into the methyl cellulose aqueous solution, fully disperse them, and grind them with a sand mill; then add the resin and carbon fiber to the above solution, stir with a disperser at a speed of 600-800r / min, and stir for 20min to obtain a carbon-based absorbing slurry.

[0034] The 30mm×30mm×30mm absorbing layer 2 is immersed in the above carbon-based absorbing slurry in three layers. The height of each layer is controlled by controlling the depth of the carbon-based absorbing slurry. The heights of the three layers are 30mm, 20mm, and 10mm respectively. The weight gain of the absorbing layer 2 after immersion is 300g.

[0035] Then, based on the above-mentioned wave-absorbing layer 2, after bonding with the first skin layer and the second skin layer, the carbon-based wave-absorbing coating structure of the present invention is formed. The weight of the wave-absorbing layer increases by 300 g. The thickness of the first skin layer is 0.8 mm ± 0.2 mm, the thickness of the second skin layer is 0.5 mm ± 0.2 mm, the thickness of the structural adhesive film layer is 0.2 mm, and the average radar reflectivity value of the honeycomb sandwich structure is below -20 dB in the range of 2 - 18 GHz, and the average radar reflectivity is below -35 dB in the range of 5 - 12 GHz, as Figure 4 shown.

[0036] For the carbon-based wave-absorbing coating structure of the present invention, the gradient carbon-based wave-absorbing coating is similar to the structure of a wave-absorbing horn. When electromagnetic waves are incident, the electromagnetic waves entering the interior of the coating are converted into heat energy and dissipated through the "resonance" effect of the carbon-based wave-absorbing coating. The reflected electromagnetic waves interact with each other inside the honeycomb cells to generate multiple reflections or interference, thereby dissipating the electromagnetic waves. The combined effect of these two aspects improves the wave-absorbing efficiency of the electromagnetic waves in the honeycomb cells. At the same time, the gradient carbon-based wave-absorbing coating can improve the impedance matching of the overall material. The structure similar to a horn achieves the effect of impedance gradual change, improving the wave-absorbing bandwidth. Different gradients and the ratio of micro-nano carbon-based absorbents can be adjusted according to the technical index requirements of different customers, so as to meet the usage needs of customers.

[0037] As mentioned 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 embodiments of the present application.

Claims

1. A carbon-based radar absorbing coating structure, characterized in that: It comprises a first skin layer, an absorbing layer and a second skin layer which are sequentially pasted up and down; the first skin layer, the second skin layer and the absorbing layer are connected by adhesive film layers respectively; the absorbing layer is a honeycomb core formed by connecting a plurality of honeycomb units; and a multi-layer gradient carbon-based absorbing coating is coated on the inner wall of each of the honeycomb units.

2. The carbon-based radar absorbing coating structure according to claim 1, characterized in that: The number of layers of the gradient is at least three.

3. The carbon-based radar absorbing coating structure according to claim 1, characterized in that: The ratio of the weight of the carbon-based microwave-absorbing coating to the volume of the honeycomb core not coated with the carbon-based microwave-absorbing coating is 0.01-1 g / cm3.

4. The carbon-based radar absorbing coating structure according to claim 1, characterized in that: The honeycomb core is made of one of aramid, glass fiber, quartz and PBO.

5. The carbon-based radar absorbing coating structure according to claim 1, characterized in that: The material of the first skin layer is one of aramid, glass fiber, quartz and PBO.

6. The carbon-based radar absorbing coating structure according to claim 1, characterized in that: The second skin layer is made of a carbon fiber plate.

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