Wave-absorbing material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of composite materials, and discloses a wave-absorbing material as well as a preparation method and application thereof. The wave-absorbing material comprises an absorbing substrate and a photonic crystal metamaterial layer which are sequentially arranged in a laminated mode. The photonic crystal metamaterial layer comprises a plurality of photonic crystal layers, raw materials of the photonic crystal metamaterial layer comprise a metal-based material, a high-molecular polymer and a cross-linking agent, and the weight ratios of components in different photonic crystal layers are different; the raw materials of the absorption substrate comprise a metal-based material and silicone rubber. The preparation method is simple and efficient, the absorbing substrate and the photonic crystal metamaterial layer are prepared firstly, then the absorbing substrate and the photonic crystal metamaterial layer are compounded, and the wave-absorbing material is obtained. The maximum absorption of the wave-absorbing material is enhanced, the effective bandwidth is widened, the absorption capacity of compounding the absorption substrate and the multi-concentration photonic crystal metamaterial layer is remarkably improved compared with that of compounding the absorption substrate and the multi-concentration photonic crystal metamaterial layer with a single-concentration photonic crystal metamaterial layer, and the wave-absorbing material has topological properties, can resist interference of processing errors and environmental changes, and maintains good wave-absorbing performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite materials, and particularly relates to an electromagnetic wave absorbing material, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid transformation of informatization and intelligence, electronic devices or wireless connection devices can be found almost everywhere. While bringing convenience to life, they also bring problems such as electromagnetic interference and electromagnetic pollution. Electromagnetic wave absorbing materials have been widely used in military and civilian fields. In the modern military field, the stealth performance of military aircraft, missiles and other equipment is crucial. The performance of electromagnetic wave absorbing materials directly affects the survivability and combat effectiveness of military equipment. In communication systems, electromagnetic wave absorbing materials can effectively absorb sidelobe signals, improve the directivity and gain of antennas, reduce the impact of electromagnetic radiation from facilities such as communication base stations on the surrounding environment, improve the security of communication systems, and improve the quality of satellite communication and indoor wireless communication. Electromagnetic wave absorbing materials are roughly divided into two categories: traditional absorbing materials and metamaterials. Traditional absorbing materials have limited absorption ability and narrow bandwidth. Metamaterials are composed of periodic structural units, and can achieve any combination of magnetic permeability and dielectric constant by designing the structural units, which cannot be achieved by natural synthetic materials. However, the preparation of metamaterials usually has the disadvantages of difficult processing, time-consuming and high cost. Summary of the Invention

[0003] In order to at least overcome one of the problems existing in the above-mentioned prior art, one of the purposes of the present invention is to provide an electromagnetic wave absorbing material. Another purpose of the present invention is to provide a preparation method of the electromagnetic wave absorbing material. The third purpose of the present invention is to provide an application of the electromagnetic wave absorbing material. Through the electromagnetic wave absorbing material of the present invention, a flexible absorption substrate is combined with a flexible photonic crystal metamaterial layer. The absorption substrate provides a baseline for the maximum absorption frequency, and the photonic crystal metamaterial layer introduces microwave resonance to achieve field enhancement and generate a resonance peak of perfect absorption. The present invention makes full use of the advantages of each component, enables microwaves to effectively propagate and absorb inside the electromagnetic wave absorbing material, and thus improves the overall performance of the electromagnetic wave absorbing material.

[0004] To this end, the present invention adopts the following technical solutions:

[0005] In a first aspect of the present invention, there is provided an electromagnetic wave absorbing material, which includes an absorption substrate and a photonic crystal metamaterial layer stacked in sequence; the photonic crystal metamaterial layer includes a plurality of photonic crystal layers, and the raw material composition of the photonic crystal metamaterial layer includes a metal-based material, a polymer, and a cross-linking agent, and the weight ratios of the components in different photonic crystal layers are different; the raw material composition of the absorption substrate includes a metal-based material and silicone rubber.

[0006] Preferably, the thickness of the wave-absorbing material is 1.5 to 3.5 mm. Further preferably, the thickness of the wave-absorbing material is 2.0 to 3.5 mm. More preferably, the thickness of the wave-absorbing material is 2.0 to 3.0 mm.

[0007] Preferably, the thickness of the absorption substrate is 0.5 to 1.5 mm. Further preferably, the thickness of the absorption substrate is 0.8 to 1.2 mm. More preferably, the thickness of the absorption substrate is 1.0 to 1.2 mm.

[0008] Preferably, the metal matrix material is a magnetic metal matrix material. Further preferably, the metal matrix material is a magnetic organometallic matrix material. More preferably, the metal matrix material is carbonyl iron powder (CIP).

[0009] Preferably, the polymer is a silicone material. Further preferably, the polymer is silicone oil. More preferably, the polymer is polydimethylsiloxane (PDMS).

[0010] Preferably, the crosslinking agent is selected from at least one of dicumyl peroxide (DCP), tetraethyl orthosilicate (TEOS), methyltriethoxysilane (MTES), and chloroplatinic acid. Further preferably, the crosslinking agent is selected from at least one of TEOS, MTES, and chloroplatinic acid. More preferably, the crosslinking agent is TEOS.

[0011] Preferably, in the raw material composition of the absorption substrate, the weight ratio of the metal matrix material to the silicone rubber is (7 to 9):(1 to 3). Further preferably, in the raw material composition of the absorption substrate, the weight ratio of the metal matrix material to the silicone rubber is (8 to 9):(1 to 2).

[0012] Preferably, in the raw material composition of the photonic crystal metamaterial layer, the weight ratio of the metal matrix material, the polymer, and the crosslinking agent is (1 to 5):(5 to 9):(0.3 to 1.1). Further preferably, in the raw material composition of the photonic crystal metamaterial layer, the weight ratio of the metal matrix material, the polymer, and the crosslinking agent is (1 to 4):(6 to 9):(0.5 to 1.0). More preferably, in the raw material composition of the photonic crystal metamaterial layer, the weight ratio of the metal matrix material, the polymer, and the crosslinking agent is (1 to 3):(7 to 9):(0.7 to 0.8).

[0013] The second aspect of the present invention provides a method for preparing the wave-absorbing material according to the first aspect of the present invention, comprising the following steps:

[0014] (1) Mix the metal matrix material and the silicone rubber, form a film, and dry it to obtain an absorption substrate;

[0015] (2) Mix the metal matrix material, polymer, and crosslinking agent, and perform 3D printing to obtain a photonic crystal metamaterial layer.

[0016] (3) Composite the absorption substrate with the photonic crystal metamaterial layer to obtain the absorbing material.

[0017] Preferably, in step (1), the drying temperature is 80 - 110 °C. Further preferably, in step (1), the drying temperature is 90 - 110 °C. Even more preferably, in step (1), the drying temperature is 100 - 110 °C.

[0018] Preferably, in step (1), the drying time is 50 - 70 min. Further preferably, in step (1), the drying time is 55 - 70 min. Even more preferably, in step (1), the drying time is 55 - 65 min.

[0019] Preferably, in step (2), the number of 3D printing layers is more than 2 layers, the layer height is 600 - 800 μm, and the adjacent line spacing is 1.5 - 2.5 mm. Further preferably, in step (2), the number of 3D printing layers is more than 2 layers, the layer height is 650 - 800 μm, and the adjacent line spacing is 1.8 - 2.5 mm. Even more preferably, in step (2), the number of 3D printing layers is more than 2 layers, the layer height is 700 - 800 μm, and the adjacent line spacing is 2.0 - 2.3 mm.

[0020] Preferably, in step (3), the composite is carried out by hot pressing, and the hot pressing temperature is 100 - 120 °C, the hot pressing pressure is 5 - 10 MPa, and the hot pressing time is 5 - 15 min.

[0021] The third aspect of the present invention provides the application of the absorbing material prepared by the preparation method of the absorbing material according to the first aspect of the present invention or the absorbing material according to the second aspect of the present invention in the field of composite materials.

[0022] Compared with traditional absorption films, the beneficial effects of the present invention are:

[0023] (1) In the incident angle range of 0° - 60°, the maximum absorption of the absorbing material of the present invention is enhanced, and the effective bandwidth is broadened.

[0024] (2) The absorption ability of the composite of the absorption substrate of the present invention and the photonic crystal metamaterial layer with multiple concentrations is significantly improved compared with the composite with a single - concentration photonic crystal metamaterial layer.

[0025] (3) The microwave absorbing material of the present invention has topological properties, which can resist the interference of processing errors and environmental changes and maintain good microwave absorbing performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described below in conjunction with the drawings, examples and comparative examples, wherein:

[0027] Figure 1 FIG. is a schematic structural diagram of a dual-concentration photonic crystal metamaterial layer during the preparation process of Example 1.

[0028] Figure 2 FIG. is a schematic structural diagram of a triple-concentration photonic crystal metamaterial layer during the preparation process of Example 2.

[0029] Figure 3 FIG. is a schematic structural diagram of a quadruple-concentration photonic crystal metamaterial layer during the preparation process of Example 3.

[0030] Figure 4 FIG. is a schematic structural diagram of the microwave absorbing material obtained in Example 3. DETAILED DESCRIPTION OF THE INVENTION

[0031] The content of the present invention will be further described in detail below through specific examples and comparative examples, but it is not limited to all the descriptions and data.

[0032] Among the raw materials for preparing the absorption substrate, the silicone rubber is the silicone rubber of model CMT305AB from Shenzhen Dazhou Material Technology Co., Ltd. Among the raw materials for preparing the photonic crystal metamaterial layer, the crosslinking agent is DOWSIL TM SE 1700 silicone rubber (containing TEOS).

[0033] It should be emphasized that, unless otherwise specified, the raw materials, reagents or devices in the present invention can be obtained from conventional commercial channels unless otherwise specified.

[0034] Example 1:

[0035] A microwave absorbing material, comprising an absorption substrate and a photonic crystal metamaterial layer stacked in sequence; the photonic crystal metamaterial layer includes a plurality of photonic crystal layers, the raw material composition of the photonic crystal metamaterial layer includes a metal-based material, a polymer, and a crosslinking agent, and the weight ratios of the components in different photonic crystal layers are different; the raw material composition of the absorption substrate includes a metal-based material and silicone rubber.

[0036] A preparation method of a microwave absorbing material, comprising the following steps:

[0037] (1) Prepare the absorption substrate

[0038] Use a planetary gravity vacuum defoaming mixer to fully mix CIP and silicone rubber in a weight ratio of 7:3. The mixer works at a speed of 600r / min for 40s under a vacuum of 1KPa to obtain a composite precursor for preparing an absorption substrate. Based on the composite precursor, a wet film with a thickness of 1.15mm is prepared by a casting method with the help of an adjustable precision coating scraper. The thickness and uniformity of the wet film should be well controlled. The wet film is dried and cured in an oven at 100°C for 60min to obtain a dry film with a thickness of 1.00mm, which is the absorption substrate.

[0039] (2) Preparation of dual-concentration photonic crystal metamaterial layer

[0040] CIP and PDMS were mixed in a weight ratio of (1:9) and (2:8) respectively. Premixed in a planetary vacuum mixer at 80r / min for 2min to make CIP and PDMS preliminarily mixed evenly. Add crosslinking agent (weight ratio of PDMS to crosslinking agent is 10:1) respectively, stirred at 60r / min for 3min under 1KPa vacuum, transferred to the barrel, and vacuum degassed at 1KPa for 2min to remove bubbles. Finally, freeze the barrel in a refrigerator for 30min to reduce bubbles and prepare ink slurry for 3D printing.

[0041] Create a cube model in the printing software and set the geometric parameters. The number of layers L = 4, the number of cycles n = 2, the height of each layer h = 700 μm, the spacing between adjacent lines d = 2 mm, the offset distance perpendicular to the printing direction s = 1 mm, and the cycle parameter is selected as 2. Figure 1 As shown, two nozzles are used, the first nozzle contains 20% CIP (CIP accounts for the mass percentage of CIP and PDMS) ink slurry, and prints and builds the first and third layers; the second nozzle contains 10% CIP ink slurry, and prints and builds the second and fourth layers. WP lines are printed on a glass substrate coated with a release agent along the input path at a speed of 4mm / s with an 18G distribution needle (inner diameter 0.84mm). It is recorded as 20 / 10WP-4 (L=4, n=2).

[0042] (3) Preparation of absorbing materials

[0043] A 0.5 μm thick layer of γ-aminopropyltriethoxysilane (2 wt% ethanol solution) was sprayed on the surface of the absorbent substrate, and the surface of the photonic crystal metamaterial layer was plasma treated to activate the surface Si-OH groups (power 50 W, Ar gas flow rate 10 L / min, time 30 s), and then Figure 4 As shown, the absorbing substrate and the photonic crystal metamaterial layer are composited by hot pressing (the hot pressing temperature is 100° C., the hot pressing pressure is 5 MPa, and the hot pressing time is 10 min) to obtain the absorbing material.

[0044] Embodiment 2:

[0045] A method for preparing an absorbing material, which differs from Example 1 in that in the preparation method of Example 2, step (2) is to prepare a three-concentration photonic crystal metamaterial layer, and the remaining steps are the same as those of Example 1.

[0046] In the preparation method of Example 2, the specific steps of step (2) for preparing the three-concentration photonic crystal metamaterial layer are as follows:

[0047] CIP and PDMS were mixed in a weight ratio of (1:9), (2:8): (3:7) respectively. Premixed in a planetary vacuum mixer at 80r / min for 2min to make CIP and PDMS preliminarily mixed evenly. Add the crosslinking agent (the weight ratio of PDMS to the crosslinking agent is 10:1) respectively, stirred at 60r / min for 3min under 1KPa vacuum, transferred to the barrel, and vacuum degassed at 1KPa for 2min to remove bubbles. Finally, the barrel was frozen in a refrigerator for 30min to reduce bubbles and obtain the ink slurry for 3D printing.

[0048] Create a cube model in the printing software and set the geometric parameters. The number of layers L = 6, the number of cycles n = 3, the height of each layer h = 700 μm, the spacing between adjacent lines d = 2 mm, the offset distance perpendicular to the printing direction s = 1 mm, and select the cycle parameter as 2. Figure 2 As shown, three nozzles are used, the first nozzle contains 10% CIP ink slurry, and prints and builds the first and fourth layers; the second nozzle contains 20% CIP ink slurry, and prints and builds the second and fifth layers; the third nozzle contains 30% CIP ink slurry, and prints and builds the third and sixth layers. WP lines are printed on a glass substrate coated with a release agent along the input path at a speed of 4mm / s with an 18G distribution needle (inner diameter 0.84mm). It is recorded as 10 / 20 / 30WP-6 (L=6, n=3).

[0049] Embodiment 3:

[0050] A method for preparing an absorbing material, which differs from Example 1 in that in the preparation method of Example 3, step (2) is to prepare a four-concentration photonic crystal metamaterial layer, and the remaining steps are the same as those of Example 1.

[0051] In the preparation method of Example 3, the specific steps of step (2) for preparing the four-concentration photonic crystal metamaterial layer are as follows:

[0052] CIP and PDMS were mixed in a weight ratio of (1:9), (2:8): (3:7): (4:6) respectively. Premixed in a planetary vacuum mixer at 80r / min for 2min to make CIP and PDMS preliminarily mixed and evenly mixed. Add the crosslinking agent (the weight ratio of PDMS to the crosslinking agent is 10:1) respectively, stirred at 60r / min for 3min under 1KPa vacuum, transferred to the barrel, and vacuum degassed at 1KPa for 2min to remove bubbles. Finally, the barrel was frozen in a refrigerator for 30min to reduce bubbles and obtain the ink slurry for 3D printing.

[0053] Create a cube model in the printing software and set the geometric parameters. The number of layers L = 4, the number of cycles n = 4, the height of each layer h = 700 μm, the spacing between adjacent lines d = 2 mm, the offset distance perpendicular to the printing direction s = 1 mm, and the cycle parameter is selected as 2. Figure 3 As shown, 4 nozzles are used, the first nozzle contains 10% CIP ink slurry to print and build the first layer; the second nozzle contains 20% CIP ink slurry to print and build the second layer; the third nozzle contains 30% CIP ink slurry to print and build the third layer; the fourth nozzle contains 40% CIP ink slurry to print and build the fourth layer. WP lines are printed on a glass substrate coated with a release agent along the input path at a speed of 4mm / s with an 18G distribution needle (inner diameter 0.84mm). It is recorded as 10 / 20 / 30 / 40WP-4 (L=4, n=1).

[0054] Comparative Example 1:

[0055] A method for preparing an absorbing material, which differs from Example 1 in that in the preparation method of Comparative Example 1, step (2) is to prepare a single-concentration photonic crystal metamaterial layer, and the remaining steps are the same as those of Example 1.

[0056] In the preparation method of Comparative Example 1, the specific steps of preparing a single-concentration photonic crystal metamaterial layer in step (2) are as follows:

[0057] Mix CIP and PDMS in a weight ratio of (1:9). Premix in a planetary vacuum mixer at 80r / min for 2 minutes to make CIP and PDMS preliminarily mixed and evenly mixed. Add a crosslinker (the weight ratio of PDMS to the crosslinker is 10:1), stir at 60r / min for 3 minutes under 1KPa vacuum, transfer to a barrel, and vacuum degas for 2 minutes at 1KPa to remove bubbles. Finally, freeze the barrel in a refrigerator for 30 minutes to reduce bubbles and prepare ink slurry for 3D printing.

[0058] Create a square model in the printing software and set the geometric parameters. The number of layers L = 1, the height of each layer h = 700 μm, the spacing between adjacent lines d = 2 mm, and the cycle parameter is selected as 2. Use 1 nozzle with 10% CIP ink slurry to print the first layer. Use an 18G distribution needle (inner diameter 0.84 mm) to print WP lines on a glass substrate coated with a release agent along the input path at a speed of 4 mm / s. Recorded as 10WP-1 (L = 1).

[0059] Material performance test:

[0060] The performance test standards of absorbing materials are as follows:

[0061] Thickness: measured with a digital micrometer;

[0062] Minimum reflection loss: tested according to the bow method of GJB 2038-94;

[0063] Effective absorption bandwidth: tested according to the bow method of GJB 2038-94;

[0064] Optimal absorption frequency band: tested according to the GJB 2038-94 bow method.

[0065] The performance data are shown in Table 1 below.

[0066] Table 1 Wave absorption performance test data table of Examples 1-3 and Comparative Example 1

[0067]

[0068] As shown in Table 1, the minimum reflection loss of Example 1 is -45 dB, while the minimum reflection loss of Comparative Example 1 is only -10 dB. The absorbing capacity of the absorbing material of Example 1 is 4.5 times that of the comparative example. According to the conversion formula of reflection loss and energy absorption rate: Reflection loss (dB) = -10·log 10 (1-energy absorption rate / 100), the energy absorption rate of Example 1 is >99.99%, and that of Comparative Example 1 is 90%, and the absorbing ability of the absorbing material of Example 1 is good. The minimum reflection loss of Example 3 at a thickness of 3.0 mm reaches -52 dB, proving that the absorption performance of the absorbing material in the low frequency band (6-9 GHz) can be significantly improved by component optimization.

[0069] The effective absorption bandwidth of the absorbing material of Example 1 reaches 13.8 GHz (4.2-18.0 GHz), covering the C band to the Ku band, which is 245% wider than that of the comparative example 1 (4.0 GHz), meeting the multi-band compatibility requirements.

[0070] The absorbing material of Example 2 still maintains an effective absorption bandwidth of 11.5 GHz at a thinner thickness (2.0 mm), reflecting the synergistic advantages of lightweight and broadband.

[0071] In addition, the microwave absorbing material in Example 1 achieves efficient absorption across the entire frequency band at a thickness of 2.5 mm, showing a significant improvement in absorption performance compared to Comparative Example 1, which also demonstrates the crucial role of the microstructure design in reducing the thickness.

[0072] The above are only the preferred embodiments of the present invention, and there is no limitation to the present invention in any form. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications within the scope of the technical solution of the present invention by using the technical content mentioned above to make equivalent embodiments of equivalent changes. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention still fall within the scope of the present invention.

Claims

1. A wave absorbing material, characterized in that: The absorbing material comprises an absorbing substrate and a photonic crystal metamaterial layer which are stacked in sequence; The photonic crystal metamaterial layer comprises a plurality of photonic crystal layers, the raw material composition of the photonic crystal metamaterial layer comprises a metal-based material, a high molecular polymer, and a cross-linking agent, and the weight ratios of the components in different photonic crystal layers are different; The raw materials of the absorption substrate include metal-based materials and silicone rubber.

2. The absorbing material according to claim 1, characterized in that: The thickness of the absorbing material is 1.5 to 3.5 mm; And / or, the absorption substrate has a thickness of 0.5 to 1.5 mm.

3. The absorbing material according to claim 1, characterized in that: In the raw material composition of the absorption substrate, the weight ratio of the metal-based material to the silicone rubber is (7-9): (1-3).

4. The absorbing material according to claim 1, characterized in that: In the raw material composition of the photonic crystal metamaterial layer, the weight ratio of the metal-based material, the high molecular polymer, and the cross-linking agent is (1-5): (5-9): (0.3-1.1).

5. The absorbing material according to claim 1, characterized in that: The metal-based material is a magnetic metal-based material; And / or, the high molecular polymer is an organic silicon material; And / or, the cross-linking agent is selected from at least one of dicumyl peroxide, ethyl orthosilicate, methyltriethoxysilane and chloroplatinic acid.

6. The method for preparing the absorbing material according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) mixing the metal base material and the silicone rubber, forming a film, and drying to obtain an absorption substrate; (2) mixing a metal-based material, a high molecular polymer, and a cross-linking agent, and performing 3D printing to obtain a photonic crystal metamaterial layer; (3) Compounding the absorbing substrate with the photonic crystal metamaterial layer to obtain the absorbing material.

7. The method for preparing the absorbing material according to claim 6, characterized in that: In step (1), the drying temperature is 80-110° C., and the drying time is 50-70 min.

8. The method for preparing the absorbing material according to claim 6, characterized in that: In step (2), the number of layers of the 3D printing is more than 2, the layer height is 600-800 μm, and the spacing between adjacent lines is 1.5-2.5 mm.

9. The method for preparing the wave absorbing material according to claim 6, characterized in that: In step (3), the compounding is carried out by hot pressing.

10. Use of the absorbing material according to any one of claims 1 to 5 or the absorbing material prepared by the method for preparing the absorbing material according to claims 6 to 9 in a composite material.

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