A composite ceramic stealth material based on metasurface subwavelength structure and its preparation method

Abstract

The present invention provides a composite ceramic stealth material based on a metasurface subwavelength structure and its preparation method, relating to the field of functional materials. The composite ceramic stealth material based on a metasurface subwavelength structure comprises, in sequence, a first dielectric layer, a subwavelength structural layer, a second dielectric layer, and a dense functional layer. This composite ceramic stealth material based on a metasurface subwavelength structure and its preparation method can achieve high-frequency (X-band) absorption / scattering control, minimizing the impact on the material's low-frequency wave transmission performance. This achieves efficient stealth at high frequencies (X-band) while also meeting the requirements for low-frequency electromagnetic wave transmission.

Description

Technical Field

[0001] The present invention relates to the field of functional materials, and in particular to a composite ceramic stealth material based on a metasurface subwavelength structure and a preparation method thereof. Background Art

[0002] Stealth technology, as an effective means of enhancing weapon system survivability, penetration, and deep strike capabilities, has long been highly valued worldwide. With the advancement of detection technology, radar detection has become the most widely used and effective reconnaissance method. Therefore, radar stealth technology, particularly X-band (8-12GHz) stealth technology, is currently a focus of research worldwide. Due to their poor maneuverability, surface ships face a higher level of radar stealth compared to aircraft. Furthermore, considering the operational requirements of the marine environment, radar stealth is even more challenging.

[0003] Antennas, core components for signal transmission in shipboard communication systems, are currently primarily made of metal. With the advancement of detection technology, when radar waves strike the surface of slender antenna structures (with aspect ratios between 20 and 60) perpendicular to the sea surface, the induced currents are distributed with equal amplitude and phase at all points along the antenna's height, with the strongest radiation occurring in the normal direction. At this point, the antenna's height can reach hundreds of times its wavelength, resulting in a strong radiation spike in the echo direction. This results in a significant radar cross-section (RCS) for the antenna, making it a major source of strong radar scattering for the communication system and easily detectable by anti-submarine patrol aircraft. To address the large RCS of antennas, existing technologies often employ surface coatings with absorbing materials (such as ferrites and carbon-based composites) or structural stealth designs (such as topological insulation and honeycomb sandwich panels). However, these solutions have significant drawbacks. First, traditional absorbing materials / coatings rely on dielectric and magnetic loss mechanisms. While they can achieve partial absorption in the X-band, their high dielectric constant severely interferes with the transmission of electromagnetic waves in the low-frequency band below 1 GHz, resulting in communication signal attenuation exceeding 30%, making them unsuitable for antenna systems that require high-frequency absorption and low-frequency transmission. Furthermore, the coatings have a weak bond with the metal substrate, leading to cracking and shedding after prolonged immersion in seawater, resulting in a service life of less than five years. Immersion in oil tanks also leads to peeling, shedding, and oil leakage. Furthermore, more complex structural stealth designs often result in complex multi-layer stacking structures (typically requiring 5-8 alternating layers of dielectric and metal), which exceed the application volume and thickness requirements, making them unsuitable for stealth applications on ship antennas less than 5 mm thick.

[0004] Metasurfaces are artificial planar structures with subwavelength characteristic dimensions that enable precise and flexible control of incident electromagnetic wave parameters such as amplitude, phase, polarization, and frequency on a subwavelength scale. The core principle is to independently control the phase and amplitude of electromagnetic waves by designing the geometry, size, and arrangement of nanostructures. Metasurfaces are being applied in radar stealth materials, meeting the requirements of a new generation of radar stealth materials: thin, wide, light, and strong.

[0005] Chinese patent CN113690631A discloses a highly efficient X-band absorbing metasurface material. This metasurface material consists of four layers: a first dielectric layer 1 (d = 3.5-3.7 mm), a microstructured impedance film layer (d = 0.05 mm), a second dielectric layer 3 (d = 3.5-3.7 mm), and a metal reflective layer (d = 0.017 mm). The dielectric layer is a cyanate ester prepreg. The material achieves an average RCS reduction of over 25 dB relative to a metal plate, effectively reducing the RCS. However, the total thickness of this metasurface material exceeds 7 mm, far exceeding the required thickness of less than 5 mm for this application. Furthermore, the cyanate ester prepreg used for the dielectric layer, when immersed in an oil cylinder, can cause oil to penetrate from the first dielectric layer into the microstructured impedance film and further into the metal reflective layer. This oil penetration causes delamination of the cyanate ester prepreg and shedding of the microstructured impedance film, resulting in a loss of the material's stealth properties.

[0006] Although traditional ceramic materials have the advantages of being resistant to seawater corrosion, wear-resistant, oil-resistant, and having stable chemical properties, they are brittle and lack toughness when used in ten-meter antennas. Once they encounter violent impacts such as gravel and birds, they are prone to defects such as cracks and fractures. At the same time, since the processing temperature of ceramics generally exceeds 750°C, which is much higher than the operating temperature of metal antennas (the operating temperature of metal does not exceed 700°C), they cannot be integrated into the surface of metal antennas and can only be bonded with adhesives. At this time, the dielectric properties and bonding gap of the adhesive have a great impact on the stealth performance. In addition, the adhesive is generally epoxy resin, which directly affects the service life of the stealth material.

[0007] Therefore, how to combine ceramic materials with metasurface materials to provide a composite ceramic stealth material based on the subwavelength structure of the metasurface and its preparation method, effectively achieve stealth in the high-frequency band (X-band) and wave transmission in the low-frequency band (less than 1GHz), and meet the actual use requirements in complex environments such as seawater resistance, motion wear resistance (repeated lifting and lowering), and oil resistance, is a technical problem that needs to be urgently solved by existing technologies. Summary of the Invention

[0008] In order to solve the technical problems existing in the prior art, the present invention provides a composite ceramic stealth material based on a metasurface subwavelength structure and a preparation method thereof, which can realize the regulation of high-frequency absorption / scattering at high frequency (X-band) and reduce the impact on the low-frequency wave transmission performance of the material; achieve efficient stealth at high frequency (X-band) while taking into account the wave transmission requirements of low-frequency electromagnetic waves.

[0009] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0010] A composite ceramic stealth material based on a metasurface subwavelength structure, which is sequentially provided with a first dielectric layer, a subwavelength structural layer, a second dielectric layer, and a dense functional layer;

[0011] The first dielectric layer is a quartz fiber reinforced quartz / cyanate composite material with a dielectric constant of 2.9-3.4 and a loss tangent value of ≤0.005;

[0012] The sub-wavelength structure layer is composed of periodic pattern units with hollow metal patches;

[0013] The second dielectric layer is a quartz fiber reinforced quartz / cyanate composite material with a dielectric constant of 2.9-3.4 and a loss tangent value of ≤0.005;

[0014] The dense functional layer is a polymer-based composite coating with a dielectric constant of 3.0-3.3 and a loss tangent value of ≤0.008.

[0015] Preferably, the thickness of the first dielectric layer is 1.7-2.5 mm, the thickness of the subwavelength structural layer is 0.025-0.08 mm, the thickness of the second dielectric layer is 0.1-0.3 mm, and the thickness of the dense functional layer is 0.5-1.2 mm.

[0016] Preferably, the pattern units of the sub-wavelength structure layer are composed of a base material, a metal patch and a void area formed by etching, and the metal patch and the void area are distributed in a two-dimensional central symmetry;

[0017] The base material is a polyimide film; the material of the metal patch is one of the following: gold, silver, copper;

[0018] The period of the pattern unit is 5.0-6.0 mm, the side length of the metal patch is 4.0-5.0 mm, the side length of the gap area is 1.0-1.8 mm, and the surface resistivity is 50-60 Ω / sq.

[0019] A method for preparing the aforementioned composite ceramic stealth material based on a metasurface subwavelength structure comprises the following steps:

[0020] Step S002: adding quartz ceramic powder, cyanate resin and additives into a solvent and mixing them evenly to obtain a prepreg slurry;

[0021] Step S003: placing the prepreg slurry in a prepreg forming device and compounding it with quartz fiber cloth to form a prepreg;

[0022] Step S004: cutting the prepreg into prepreg tapes;

[0023] Step S005: Conformally wrapping the prepreg tape onto the metal antenna and forming a first dielectric layer through an autoclave process;

[0024] Step S006: Processing the first dielectric layer to a predetermined thickness to form a processed first dielectric layer;

[0025] Step S007: laying the sub-wavelength structure layer on the processed first dielectric layer;

[0026] Step S008: Conformally wrapping the prepreg tape onto the outer side of the subwavelength structure layer on the metal antenna, and forming a second dielectric layer through an autoclave process;

[0027] Step S009: Processing the second dielectric layer to a predetermined thickness to form a processed second dielectric layer;

[0028] Step S010: preparing a dense functional layer by spraying on the surface of the processed second dielectric layer to obtain a composite ceramic stealth material based on a metasurface subwavelength structure.

[0029] Furthermore, in step S002, the particle size of the quartz ceramic powder is ≤1 μm, and the SiO2 purity is ≥99%;

[0030] Cyanate ester resin has a dielectric constant of 2.8-3.0 and a loss tangent of <0.005;

[0031] Additives include: silane coupling agent KH-550, dispersant BYK-110;

[0032] The solvent is acetone;

[0033] The mass ratio of quartz ceramic powder, cyanate resin, silane coupling agent KH-550, dispersant BYK-110 and acetone in the prepreg slurry is 50-60:100:2.2-2.5:1.4-1.6:35-40.

[0034] Preferably, in step S003, the quartz fiber cloth is plain weave cloth, has a SiO2 content of ≥99.9%, a warp and weft density of at least 20×20 strands / cm, and a thickness of 0.1±0.05 mm;

[0035] The dielectric constant of the quartz fiber in the quartz fiber cloth is 3.7-3.8, and the loss tangent value is less than 0.001.

[0036] Preferably, in step S003, the composite temperature of the prepreg slurry and the quartz fiber cloth in the prepreg molding device is 260° C.-300° C., and the vehicle speed is 3-5 m / min;

[0037] In step S005, the tape pitch during winding is controlled at 15-28 mm, the rotation speed is 20-22 rpm, and the tension is 40-43 N;

[0038] In step S008, the tape pitch is controlled at 15-28 mm, the rotation speed is 20-22 rpm, and the tension is 40-43 N during winding.

[0039] Preferably, in step S005, the autoclave process is to first heat the temperature to 110-130°C at a heating rate of 1-3°C / min, keep the temperature for 1-2 hours, then continue to heat the temperature to 160-190°C, keep the temperature for 1-2 hours, then continue to heat the temperature to 210-230°C, keep the temperature for 2-3 hours, and then cool to room temperature; at the same time, when the temperature rises to 180°C, apply a pressure of 0.7-1.0 MPa and maintain it until the end of the process;

[0040] In step S008, the autoclave process is to first heat the temperature to 110-130°C at a heating rate of 1-3°C / min, keep the temperature for 1-2 hours, then continue to heat the temperature to 160-190°C, keep the temperature for 1-2 hours, then continue to heat the temperature to 210-230°C, keep the temperature for 2-3 hours, and then cool to room temperature; at the same time, when the temperature rises to 180°C, apply a pressure of 0.7-1.0 MPa and maintain it until the end of the process.

[0041] Furthermore, in step S010, the dense functional layer is prepared by spraying by cyclically heating material A and material B respectively, spraying material A and material B simultaneously onto the surface of the processed second dielectric layer at a spraying pressure of 15-17 MPa, and controlling the spraying thickness within 1.5 mm; after the spraying is completed, the material is cured and dried, and then processed to a predetermined thickness;

[0042] The material A is a polymer made from diisocyanate, polypropylene glycol and polydimethylsiloxane;

[0043] The material B is composed of the following raw materials: amino-terminated polyether D-200, diethyltoluenediamine, and silicon nitride with a particle size of 2-5 μm.

[0044] Preferably, the material A is a polymer prepared by using diisocyanate, polypropylene glycol, and polydimethylsiloxane as raw materials, and reacting at 80-85° C. for 2-3 hours in a nitrogen environment; the mass ratio of the diisocyanate, polypropylene glycol, and polydimethylsiloxane is 100:30-35:10-13;

[0045] The mass ratio of the amino-terminated polyether D-200, diethyltoluenediamine, and silicon nitride in the material B is 30-32:13-14:7-8;

[0046] The weight ratio of material A to material B sprayed per unit time is 1:1.5-1.6.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] (1) The composite ceramic stealth material based on the metasurface subwavelength structure of the present invention effectively breaks through the technical bottleneck of the unadjustable frequency band performance of traditional materials by combining the metasurface subwavelength structure with the composite ceramic matrix, and effectively realizes high-frequency band (X-band) stealth and low-frequency band (less than 1GHz) wave transmission. Among them, the subwavelength hollow metal patch array forms a local resonance in the X-band, and cooperates with the gradient dielectric design of the first dielectric layer and the second dielectric layer to effectively realize electromagnetic wave phase cancellation and energy absorption. Compared with existing materials, its average RCS reduction value in the X-band can reach more than 10dB. At the same time, the first dielectric layer and the second dielectric layer adopt a low-loss quartz ceramic matrix (loss tangent ≤ 0.003). In the low frequency band less than 1GHz, the dielectric constant is stable and the impedance matching is good. The wave transmittance is increased to more than 95%, which is significantly better than the 30% attenuation level of traditional ferrite materials. Furthermore, through the short-wave 8kW high-power loading and tuning test, it can normally transmit high-power signals and tune, and the radiation directionality and impedance characteristics are comparable to the radiation capability of metal antennas.

[0049] (2) The composite ceramic stealth material based on the metasurface subwavelength structure of the present invention adopts a "sandwich" type multilayer structure (dielectric layer-subwavelength structure layer-dielectric layer-dense functional layer). While ensuring high-frequency stealth and low-frequency wave transmission performance, the total thickness can be controlled within 4mm, which is more than 40% lighter than the traditional 5-8 layer stacking solution, effectively achieving lightweighting.

[0050] (3) After testing, the composite ceramic stealth material based on the metasurface subwavelength structure of the present invention can also achieve the following technical effects: First, the bonding strength between the metal antenna and the first dielectric layer after treatment in each embodiment is greater than 10MPa, reducing the risk of falling off after seawater immersion or oil pressure immersion. Secondly, in addition to being bonded by the added cyanate resin (the interlayer shear strength of the dielectric layer is greater than 50MPa), the bonding strength between the first dielectric layer, the second dielectric layer and the subwavelength structure layer is increased by increasing the pore size of the subwavelength structure layer, and the interlayer shear strength between the subwavelength structure layer and each dielectric layer is greater than 10MPa. Thirdly, the overall motion wear resistance and oil resistance of the material are further improved by the dense functional layer (polyurea composite coating), and the bonding strength between the dense functional layer and the second dielectric layer is greater than 10MPa; when the motion wear resistance (lifting) number is 2000 times, the surface of the dense functional layer is not damaged, the antenna lifting function is normal, and the communication function test in the low frequency band does not change before and after the test. Furthermore, the composite ceramic stealth materials based on the metasurface subwavelength structure described in each embodiment did not show delamination, blistering, cracking, or falling off after being subjected to tests such as seawater corrosion, seawater impact, high temperature, low temperature, temperature shock, damp heat, and neutral salt spray; after the mold test, the mold resistance level was 0, and they all had good hydrophobicity and adaptability to marine environments, and can be effectively applied to complex marine environments and complex marine electromagnetic environments.

[0051] (4) The present invention effectively solves the technical bottlenecks of traditional stealth materials in high-frequency absorption, low-frequency transmission, mechanical properties and environmental adaptability through multi-dimensional collaborative innovation of materials, structures and processes, and provides a high-performance, lightweight and engineerable solution for antenna stealth in complex electromagnetic environments.

[0052] (5) The preparation method of the composite ceramic stealth material based on the metasurface subwavelength structure of the present invention is simple, the preparation process is easy to control, and is conducive to large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 This is a schematic diagram of the structure of a composite ceramic stealth material based on a metasurface subwavelength structure according to an embodiment of the present invention. In the figure, 1 is the first dielectric layer; 2 is the subwavelength structural layer; 3 is the second dielectric layer; and 4 is the dense functional layer.

[0054] Figure 2 Schematic diagram of the microstructure of the sub-wavelength structure layer 2 according to an embodiment of the present invention. In the figure, 5 is a polyimide film; 6 is a metal patch; and 7 is a void area.

[0055] Figure 3This is a radar cross-section (RCS) test plot of the composite ceramic stealth material based on a metasurface subwavelength structure and a metal antenna at 11 GHz, as prepared in Example 1 of the present invention. The red line represents the RCS value (2-5 dB) for the metal antenna at 11 GHz under horizontal polarization; the blue line represents the RCS value (-8 dB to -35 dB) for the composite ceramic stealth material based on a metasurface subwavelength structure at 11 GHz under horizontal polarization. DETAILED DESCRIPTION

[0056] In order to provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention are now described. It should be noted that the following detailed description is illustrative and is intended to further illustrate the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0057] It should be noted that the terms used herein are intended only to describe specific embodiments and are not intended to limit the exemplary embodiments of the present invention. As used herein, "first," "second," and the like are used to distinguish similar objects and are not used to describe a specific order or precedence. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0058] like Figure 1 As shown, an embodiment of the present invention provides a composite ceramic stealth material based on a metasurface subwavelength structure directly prepared on the surface of a metal antenna. The material is a multifunctional layer stacked structure, comprising a first dielectric layer 1, a subwavelength structure layer 2, a second dielectric layer 3, and a dense functional layer 4 arranged in sequence.

[0059] Wherein, the first dielectric layer 1 is a quartz fiber reinforced quartz / cyanate composite material with a dielectric constant of 2.9-3.4 and a loss tangent value of ≤0.005;

[0060] The sub-wavelength structure layer 2 is composed of periodic hollow metal patch units;

[0061] The second dielectric layer 3 is a quartz fiber reinforced quartz / cyanate composite material with a dielectric constant of 2.9-3.4 and a loss tangent value of ≤0.005;

[0062] The dense functional layer 4 is a polymer-based composite coating (ie, a polyurea composite coating) with a dielectric constant of 3.0-3.3 and a loss tangent value of ≤0.008.

[0063] The composite ceramic stealth material based on the metasurface subwavelength structure preferably has a thickness of the first dielectric layer 1 of 1.7-2.5 mm, a thickness of the subwavelength structure layer 2 of 0.025-0.08 mm, a thickness of the second dielectric layer 3 of 0.1-0.3 mm, and a thickness of the dense functional layer 4 of 0.5-1.2 mm.

[0064] The subwavelength structure layer 2 is an impedance film layer with a microstructure. The microstructure consists of periodically repeating pattern units in the horizontal and vertical directions. Each pattern unit consists of a base material, a metal patch 6, and a void region 7 formed by etching. The metal patch 6 and the void region 7 are arranged in a two-dimensional, centrosymmetrical pattern. The base material 5 is a polyimide film; the metal patch 6 can be made of gold, silver, or copper. The pattern unit period is 5.0-6.0 mm, the surface resistivity is 50-60 Ω / sq, and the thickness is 50±0.1 μm.

[0065] Preferably, Figure 2 As shown, in the pattern unit, the side length a1 of the gap area 7 is 1.0-1.8 mm, the side length b1 of the metal patch 6 is 4-5 mm, and the period P1 of the pattern unit is 5-6 mm.

[0066] As a general inventive concept, the present invention also provides a method for preparing the above-mentioned composite ceramic stealth material based on the metasurface subwavelength structure, comprising the following steps:

[0067] Step S001: preparing quartz fiber cloth, cyanate resin, and quartz ceramic powder;

[0068] Step S002: adding quartz ceramic powder, cyanate resin and additives into a solvent and stirring evenly to obtain a prepreg slurry;

[0069] Step S003: pouring the prepreg slurry containing cyanate resin / quartz ceramic powder into a prepreg molding device, and then laminating it with quartz fiber cloth at a temperature of 260°C-300°C and a vehicle speed of 3-5m / min to form a prepreg;

[0070] Step S004: using a cutting machine to cut the prepreg prepared in step S003 into prepreg tapes with a width of 15-30 mm and a length greater than 5 m;

[0071] Step S005: The prepreg tape cut and formed in step S004 is conformally wound around the metal antenna using a winding molding device until the winding thickness reaches the predetermined requirement, and then a first dielectric layer 1 is prepared using an autoclave process. Preferably, the metal antenna is pretreated before winding, including sandblasting with 40# glass sand at a sandblasting pressure of 0.6-0.8 MPa. Subsequently, the metal antenna is further treated by chemical etching to achieve a surface roughness of Ra = 5-7.

[0072] Step S006, processing the first dielectric layer 1 wound on the surface of the metal antenna prepared in step S005 to produce a processed first dielectric layer 1;

[0073] Step S007: laying the subwavelength structure layer 2 on the processed first dielectric layer 1 obtained in step S006;

[0074] Step S008: The prepreg tape cut and formed in step S004 is conformally wound around the outer side of the subwavelength structure layer 2 on the metal antenna by a winding molding device until the winding thickness reaches a predetermined requirement, and then the second dielectric layer 3 is prepared by an autoclave process.

[0075] Step S009, processing the wound second dielectric layer 3 prepared in step S008 to produce a processed second dielectric layer 3;

[0076] Step S010: spraying a polymer-based composite coating (i.e., dense functional layer 4) on the surface of the processed second dielectric layer 3, and then curing, drying, and processing to produce a composite ceramic stealth material based on a metasurface subwavelength structure.

[0077] In the above preparation method, preferably, in step S001, the selected quartz fiber cloth is a plain weave cloth with a SiO2 content of ≥99.9%, a warp and weft density of at least (20×20) roots / cm, and a thickness of 0.1±0.05 mm; the dielectric constant of the quartz fiber is 3.7-3.8, and the loss tangent value is <0.001; the selected cyanate ester resin is developed by the Institute of Chemistry of the Chinese Academy of Sciences, with a dielectric constant of 2.8-3.0 and a loss tangent value of <0.005; the selected quartz ceramic powder has a particle size of ≤1 μm and a SiO2 purity of ≥99%.

[0078] In the above preparation method, preferably, in step S002, the additives in the prepreg slurry include: silane coupling agent KH-550, dispersant BYK-110; the solvent is acetone; and the mass ratio of quartz ceramic powder, cyanate resin, silane coupling agent KH-550, dispersant BYK-110, and acetone in the prepreg slurry is 50-60:100:2.2-2.5:1.4-1.6:35-40.

[0079] In the above preparation method, preferably, in step S005, the tape pitch is controlled at 15-28 mm during winding, the rotation speed is 20-22 rpm, the tension is 40-43 N, and the overlap method is that the portion of the latter circle covering the previous circle is greater than 50% of the width of the prepreg tape.

[0080] In the above preparation method, preferably, in step S005 and step S008, the autoclave process parameters are as follows: raising the temperature to 110-130°C and keeping it warm for 1-2 hours; then raising the temperature to 160-190°C and keeping it warm for 1-2 hours; finally, raising the temperature to 210-230°C, keeping it warm for 2-3 hours, and then naturally cooling it; wherein the heating rate is 1-3°C / min, and when the temperature rises to 180°C, a nitrogen pressure of 0.7-1.0 MPa is applied and maintained until the curing is completed; wherein the pressure increase rate is 0.05-0.1 MPa / min.

[0081] In the above-mentioned preparation method, preferably, in steps S006 and S009, the processing is grinding, using a PCD tool with a feed rate of 0.03-0.05 mm / r, a rotation speed of 300-500 r / min, and a cutting depth of 0.4-0.6 mm per cut. The purpose of the processing is to remove surface defects such as wrinkles and missing material, and to control the thickness of the first dielectric layer 1 and the second dielectric layer 3 to a predetermined value (the thickness of the first dielectric layer 1 is 1.7-2.5 mm, and the thickness of the second dielectric layer 3 is 0.1-0.3 mm), with a tolerance of ±0.02 mm and a surface roughness of ≤ Ra3.2.

[0082] In the above-mentioned preparation method, preferably, the size of the subwavelength structural layer 2 in step S007 is generally 500×500 mm. Since the size of the antenna is generally 2.5 meters, a butt-jointing method is adopted during paving. The distance between the two subwavelength structural layers 2 must be ensured to be the same as the distance between the structural units. The structural units are arranged neatly in the circumferential direction and the axial direction, and in a straight line, without any structural unit damage or overlap.

[0083] In the above preparation method, preferably, in step S010, the Shore hardness of the dense functional layer 4 is D60-D65. The raw materials for preparing the dense functional layer 4 include material A and material B. A and material B are cyclically heated using a dedicated spraying device. When the temperature of material A and material B reaches 55-65°C, the spraying pressure is set to 15-17 MPa. Material A and material B are simultaneously sprayed onto the surface of the processed second dielectric layer 3, and the spraying thickness is controlled within 1.5 mm. After spraying, the coating is placed in an environment of 110-120°C and allowed to cure for 1-1.5 hours to form a polymer-based composite coating (i.e., a polyurea composite coating), followed by drying at 60-80°C for 23-30 hours. The dried coating is then ground to a predetermined thickness (0.5-1.2 mm), using the same process parameters as steps S006 and S009. The surface roughness Ra after processing is less than 1 μm.

[0084] In the above preparation method, preferably, in step S010, the material A is a polymer prepared by using diisocyanate, polypropylene glycol, and polydimethylsiloxane as raw materials, and reacting at 80-85°C in a nitrogen environment for 2-3 hours; the mass ratio of diisocyanate, polypropylene glycol, and polydimethylsiloxane is 100:30-35:10-13.

[0085] The material B is composed of the following raw materials: amino-terminated polyether D-200, diethyltoluenediamine, and silicon nitride with a particle size of 2-5 μm; the mass ratio of amino-terminated polyether D-200, diethyltoluenediamine, and silicon nitride is 30-32:13-14:7-8.

[0086] In the above preparation method, preferably, in step S010, the weight ratio of material A to material B sprayed per unit time is 1:1.5-1.6.

[0087] The present invention will be further described below with reference to some specific embodiments.

[0088] Example 1

[0089] This embodiment provides a composite ceramic stealth material based on a metasurface subwavelength structure. It is a multifunctional layered structure, comprising a first dielectric layer 1, a subwavelength structure layer 2, a second dielectric layer 3, and a dense functional layer 4. The first dielectric layer 1 is a quartz fiber-reinforced quartz / cyanate composite material with a dielectric constant of 3.1 and a loss tangent of 0.004; the subwavelength structure layer 2 is composed of periodic metal patch units; the second dielectric layer 3 is a quartz fiber-reinforced quartz / cyanate composite material with a dielectric constant of 3.1 and a loss tangent of 0.004; and the dense functional layer 4 is a polymer-based composite coating with a dielectric constant of 3.1 and a loss tangent of 0.006.

[0090] In the composite ceramic stealth material based on the metasurface subwavelength structure of this embodiment, the thickness of the first dielectric layer 1 is 2.45 mm, the thickness of the subwavelength structure layer 2 is 0.05 mm, the thickness of the second dielectric layer 3 is 0.2 mm, the thickness of the dense functional layer 4 is 0.8 mm, and the total thickness of the composite ceramic stealth material is 3.5 mm.

[0091] The subwavelength structure layer 2 is an impedance film layer with a microstructure, and the microstructure is a pattern unit periodically repeated in the horizontal and vertical directions; each pattern unit is composed of a base material, a metal patch 6 and a gap area 7 formed by etching, and the metal patch 6 and the gap area 7 are distributed in a two-dimensional central symmetry.

[0092] The base material is a polyimide film 5, and the metal patch 6 is made of copper. The surface resistivity of the pattern unit is 55Ω / sq, and a1=1mm, b1=5mm, and P1=6mm in the pattern unit.

[0093] This embodiment also provides a method for preparing the aforementioned composite ceramic stealth material based on the metasurface subwavelength structure, specifically:

[0094] Step S001: prepare quartz fiber cloth, cyanate resin, and quartz ceramic powder for use.

[0095] The quartz fiber cloth is plain weave with a SiO2 content of 99.92%, a warp density of (20 x 20) strands / cm, and a thickness of 0.1 mm. The quartz fiber has a dielectric constant of 3.72 and a loss tangent of 0.0007. The cyanate ester resin, developed by the Institute of Chemistry of the Chinese Academy of Sciences, has a dielectric constant of 2.91 and a loss tangent of 0.003. The quartz ceramic powder has a particle size of 0.85 μm and a SiO2 purity of 99.3%.

[0096] Step S002: adding quartz ceramic powder, cyanate resin and additives into a solvent and stirring evenly to obtain a prepreg slurry.

[0097] The prepreg slurry contains additives including silane coupling agent KH-550 and dispersant BYK-110, and the solvent is acetone. The mass ratio of quartz ceramic powder, cyanate ester resin, silane coupling agent KH-550, dispersant BYK-110, and acetone in the prepreg slurry is 55:100:2.3:1.5:38.

[0098] Step S003: pour the prepreg slurry containing cyanate resin / quartz ceramic powder into a prepreg molding device, and then laminate it with quartz fiber cloth at a temperature of 275° C. and a vehicle speed of 4 m / min to form a prepreg.

[0099] The weight ratio of the prepreg slurry to the quartz fiber cloth is 1:1.25.

[0100] Step S004: using a cutting machine to cut the prepreg prepared in step S003 into prepreg tapes with a width of 20 mm and a length greater than 5 m.

[0101] Step S005: Pre-treat the metal antenna by sandblasting with 40# glass sand at a pressure of 0.7 MPa. Then, further treatment is performed using chemical etching to achieve a surface roughness of Ra = 6. The prepreg tape cut and formed in step S004 is then conformally wound around the metal antenna using a winding forming device until the winding thickness reaches the predetermined requirement. The first dielectric layer 1 is then prepared using an autoclave process.

[0102] During winding, the tape spacing is controlled at 22 mm, the rotation speed is 20 rpm, the tension is 40 N, and the overlap method is that the portion of the latter circle covering the former circle is greater than 50% of the width of the prepreg tape.

[0103] The autoclave process is to first heat the temperature to 120°C at a heating rate of 2°C / min, keep the temperature for 1.5 hours, then continue to heat the temperature to 170°C at the aforementioned heating rate, keep the temperature for 1.5 hours, then continue to heat the temperature to 220°C at the aforementioned heating rate, keep the temperature for 2.5 hours, and then naturally cool to room temperature; at the same time, when the temperature rises to 180°C, apply a nitrogen pressure of 0.8MPa at a pressure increase rate of 0.07MPa / min and maintain the pressure until the end of the treatment.

[0104] Step S006 , processing the first dielectric layer 1 wound on the surface of the metal antenna prepared in step S005 to produce a processed first dielectric layer 1 .

[0105] Among them, the processing is grinding, using PCD tools, the feed speed is 0.04mm / r, the rotation speed is 350r / min, and the cutting depth of each cut is 0.5mm; the thickness of the first dielectric layer 1 is processed to be 2.45mm, the tolerance is ±0.02mm, and the surface roughness is ≤Ra3.2.

[0106] Step S007 , laying the subwavelength structure layer 2 on the processed first dielectric layer 1 obtained in step S006 .

[0107] Among them, the size of the subwavelength structural layer 2 is 500×500mm and the thickness is 0.05mm; the butt-jointing method is adopted during paving, and the distance between the two subwavelength structural layers 2 must be ensured to be the same as the distance between the structural units. The structural units are arranged neatly in the circumferential direction and axial direction, and on a straight line, without any structural unit damage or overlap.

[0108] Step S008: The prepreg tape cut and formed in step S004 is conformally wound around the outer side of the subwavelength structure layer 2 on the metal antenna by a winding molding device until the winding thickness reaches a predetermined requirement, and then the second dielectric layer 3 is prepared by an autoclave process.

[0109] During winding, the tape spacing is controlled at 22 mm, the rotation speed is 20 rpm, the tension is 40 N, and the overlap method is that the portion of the latter circle covering the former circle is greater than 50% of the width of the prepreg tape.

[0110] The specific process and process parameters of the autoclave are the same as those in step S005.

[0111] Step S009 , processing the wound second dielectric layer 3 prepared in step S008 to produce a processed second dielectric layer 3 .

[0112] Among them, the processing is grinding, using PCD tools, the feed speed is 0.04mm / r, the rotation speed is 350r / min, and the cutting depth of each cut is 0.5mm; the thickness of the first dielectric layer 1 is processed to be 2.45mm, the tolerance is ±0.02mm, and the surface roughness is ≤Ra3.2.

[0113] Step S010: spraying a polymer-based composite coating (i.e., dense functional layer 4) on the surface of the processed second dielectric layer 3. Specifically, the raw materials for preparing the dense functional layer 4 (material A and material B) are cyclically heated using a dedicated spraying device. When the temperature of material A and material B reaches 60°C, the spraying pressure is set to 16 MPa, and material A and material B are simultaneously sprayed onto the surface of the processed second dielectric layer 3, and the spraying thickness is controlled to be 1.3 mm. After spraying, the coating is placed in an environment of 115°C, allowed to stand and cure for 1.2 hours, and then dried at 70°C for 28 hours. The dried coating is then ground to a thickness of 0.8 mm for the dense functional layer 4, and the surface roughness Ra after processing is controlled to be less than 1 μm.

[0114] Among them, the material A is a polymer prepared by using diisocyanate, polypropylene glycol and polydimethylsiloxane as raw materials, and reacting at 80°C for 2 hours in a nitrogen environment; the mass ratio of diisocyanate, polypropylene glycol and polydimethylsiloxane is 100:30:10.

[0115] The material B is composed of the following raw materials: amino-terminated polyether D-200, diethyltoluenediamine, and silicon nitride with a particle size of 2-5 μm; the mass ratio of amino-terminated polyether D-200, diethyltoluenediamine, and silicon nitride is 30:13:7.

[0116] The weight ratio of material A and material B sprayed per unit time is 1:1.5.

[0117] After testing, the composite ceramic stealth material based on the metasurface subwavelength structure of this embodiment has a wave transmittance of 96.1% in the low frequency band below 1 GHz; the average RCS reduction in the X-band is shown in the following table:

[0118]

[0119] Furthermore, the RCS test diagram of the composite ceramic stealth material based on the metasurface subwavelength structure and the metal antenna at 11GHz is as follows: Figure 3 shown.

[0120] Example 2

[0121] This embodiment provides a composite ceramic stealth material based on a metasurface subwavelength structure. It is a multifunctional layered structure, comprising a first dielectric layer 1, a subwavelength structure layer 2, a second dielectric layer 3, and a dense functional layer 4. The first dielectric layer 1 is a quartz fiber-reinforced quartz / cyanate composite material with a dielectric constant of 3.1 and a loss tangent of 0.004; the subwavelength structure layer 2 is composed of periodic metal patch units; the second dielectric layer 3 is a quartz fiber-reinforced quartz / cyanate composite material with a dielectric constant of 3.1 and a loss tangent of 0.004; and the dense functional layer 4 is a polymer-based composite coating with a dielectric constant of 3.1 and a loss tangent of 0.006.

[0122] In the composite ceramic stealth material based on the metasurface subwavelength structure of this embodiment, the thickness of the first dielectric layer 1 is 2.45 mm, the thickness of the subwavelength structure layer 2 is 0.05 mm, the thickness of the second dielectric layer 3 is 0.2 mm, the thickness of the dense functional layer 4 is 0.8 mm, and the total thickness of the composite ceramic stealth material is 3.5 mm.

[0123] The subwavelength structure layer 2 is an impedance film layer with a microstructure, and the microstructure is a pattern unit periodically repeated in the horizontal and vertical directions; each pattern unit is composed of a base material, a metal patch 6 and a gap area 7 formed by etching, and the metal patch 6 and the gap area 7 are distributed in a two-dimensional central symmetry.

[0124] The base material is a polyimide film 5, and the metal patch 6 is made of copper. The surface resistivity of the pattern unit is 55Ω / sq, and a1=1mm, b1=5mm, and P1=6mm in the pattern unit.

[0125] This embodiment also provides a method for preparing the aforementioned composite ceramic stealth material based on the metasurface subwavelength structure, specifically:

[0126] Step S001: prepare quartz fiber cloth, cyanate resin, and quartz ceramic powder for use.

[0127] The quartz fiber cloth is plain weave with a SiO2 content of 99.92%, a warp density of (20 x 20) strands / cm, and a thickness of 0.1 mm. The quartz fiber has a dielectric constant of 3.72 and a loss tangent of 0.0007. The cyanate ester resin, developed by the Institute of Chemistry of the Chinese Academy of Sciences, has a dielectric constant of 2.91 and a loss tangent of 0.003. The quartz ceramic powder has a particle size of 0.85 μm and a SiO2 purity of 99.3%.

[0128] Step S002: adding quartz ceramic powder, cyanate resin and additives into a solvent and stirring evenly to obtain a prepreg slurry.

[0129] The prepreg slurry contains additives including silane coupling agent KH-550 and dispersant BYK-110, and the solvent is acetone. The mass ratio of quartz ceramic powder, cyanate ester resin, silane coupling agent KH-550, dispersant BYK-110, and acetone in the prepreg slurry is 50:100:2.2:1.4:35.

[0130] Step S003: pour the prepreg slurry containing cyanate resin / quartz ceramic powder into a prepreg molding device, and then laminate it with quartz fiber cloth at a temperature of 260° C. and a vehicle speed of 3 m / min to form a prepreg.

[0131] The weight ratio of the prepreg slurry to the quartz fiber cloth is 1:1.2.

[0132] Step S004: using a cutting machine to cut the prepreg prepared in step S003 into prepreg tapes with a width of 20 mm and a length greater than 5 m.

[0133] Step S005: Pre-treat the metal antenna by sandblasting with 40# glass sand at a pressure of 0.6 MPa. Then, further treatment is performed using chemical etching to achieve a surface roughness of Ra = 6. The prepreg tape cut and formed in step S004 is then conformally wound around the metal antenna using a winding forming device until the winding thickness reaches the predetermined requirement. The first dielectric layer 1 is then prepared using an autoclave process.

[0134] During winding, the tape spacing is controlled at 15 mm, the rotation speed is 21 rpm, the tension is 42 N, and the overlap method is that the portion of the latter circle covering the former circle is greater than 50% of the width of the prepreg tape.

[0135] The autoclave process is to first heat the temperature to 110°C at a heating rate of 1°C / min, keep the temperature for 1 hour, then continue to heat the temperature to 160°C at the aforementioned heating rate, keep the temperature for 1 hour, then continue to heat the temperature to 210°C at the aforementioned heating rate, keep the temperature for 2 hours, and then naturally cool to room temperature; at the same time, when the temperature rises to 180°C, apply a nitrogen pressure of 0.7MPa at a pressure increase rate of 0.05MPa / min and maintain the pressure until the end of the treatment.

[0136] Step S006 , processing the first dielectric layer 1 wound on the surface of the metal antenna prepared in step S005 to produce a processed first dielectric layer 1 .

[0137] Among them, the processing is grinding, and PCD tools are selected, the feed speed is 0.03mm / r, the rotation speed is 300r / min, and the cutting depth of each cut is 0.4mm; the thickness of the first dielectric layer 1 is processed to 2.45mm, the tolerance is ±0.02mm, and the surface roughness is ≤Ra3.2.

[0138] Step S007 , laying the subwavelength structure layer 2 on the processed first dielectric layer 1 obtained in step S006 .

[0139] Among them, the size of the subwavelength structural layer 2 is 500×500mm and the thickness is 0.05mm; the butt-jointing method is adopted during paving, and the distance between the two subwavelength structural layers 2 must be ensured to be the same as the distance between the structural units. The structural units are arranged neatly in the circumferential direction and axial direction, and on a straight line, without any structural unit damage or overlap.

[0140] Step S008: The prepreg tape cut and formed in step S004 is conformally wound around the outer side of the subwavelength structure layer 2 on the metal antenna by a winding molding device until the winding thickness reaches a predetermined requirement, and then the second dielectric layer 3 is prepared by an autoclave process.

[0141] During winding, the tape spacing is controlled at 15 mm, the rotation speed is 21 rpm, the tension is 42 N, and the overlap method is that the portion of the latter circle covering the former circle is greater than 50% of the width of the prepreg tape.

[0142] The specific process and process parameters of the autoclave are the same as those in step S005.

[0143] Step S009 , processing the wound second dielectric layer 3 prepared in step S008 to produce a processed second dielectric layer 3 .

[0144] Among them, the processing is grinding, and PCD tools are selected, the feed speed is 0.03mm / r, the rotation speed is 300r / min, and the cutting depth of each cut is 0.4mm; the thickness of the first dielectric layer 1 is processed to 2.45mm, the tolerance is ±0.02mm, and the surface roughness is ≤Ra3.2.

[0145] Step S010: spraying a polymer-based composite coating (i.e., dense functional layer 4) on the surface of the processed second dielectric layer 3. Specifically, the raw materials for preparing the dense functional layer 4 (material A and material B) are cyclically heated using a dedicated spraying device. When the temperature of material A and material B reaches 55°C, the spraying pressure is set to 15 MPa, and material A and material B are simultaneously sprayed onto the surface of the processed second dielectric layer 3, and the spraying thickness is controlled to be 1.3 mm. After spraying, the coating is placed in a 110°C environment, allowed to stand and cure for 1 hour, and then dried at 60°C for 30 hours. The dried coating is then ground to a thickness of 0.8 mm for the dense functional layer 4, and the surface roughness Ra after processing is controlled to be less than 1 μm.

[0146] Among them, the material A is a polymer prepared by using diisocyanate, polypropylene glycol and polydimethylsiloxane as raw materials, and reacting at 82°C in a nitrogen environment for 2.5 hours; the mass ratio of diisocyanate, polypropylene glycol and polydimethylsiloxane is 100:32:11.

[0147] The material B is composed of the following raw materials: amino-terminated polyether D-200, diethyltoluenediamine, and silicon nitride with a particle size of 2-5 μm; the mass ratio of amino-terminated polyether D-200, diethyltoluenediamine, and silicon nitride is 31:13.4:7.8.

[0148] The weight ratio of material A and material B sprayed per unit time is 1:1.53.

[0149] After testing, the composite ceramic stealth material based on the metasurface subwavelength structure of this embodiment has a wave transmittance of 95.9% in the low frequency band below 1 GHz; the average RCS reduction in the X-band is shown in the following table:

[0150]

[0151] Example 3

[0152] This embodiment provides a composite ceramic stealth material based on a metasurface subwavelength structure. It is a multifunctional layered structure, comprising a first dielectric layer 1, a subwavelength structure layer 2, a second dielectric layer 3, and a dense functional layer 4. The first dielectric layer 1 is a quartz fiber-reinforced quartz / cyanate composite material with a dielectric constant of 3.1 and a loss tangent of 0.004; the subwavelength structure layer 2 is composed of periodic metal patch units; the second dielectric layer 3 is a quartz fiber-reinforced quartz / cyanate composite material with a dielectric constant of 3.1 and a loss tangent of 0.004; and the dense functional layer 4 is a polymer-based composite coating with a dielectric constant of 3.1 and a loss tangent of 0.006.

[0153] In the composite ceramic stealth material based on the metasurface subwavelength structure of this embodiment, the thickness of the first dielectric layer 1 is 2.45 mm, the thickness of the subwavelength structure layer 2 is 0.05 mm, the thickness of the second dielectric layer 3 is 0.2 mm, the thickness of the dense functional layer 4 is 0.8 mm, and the total thickness of the composite ceramic stealth material is 3.5 mm.

[0154] The subwavelength structure layer 2 is an impedance film layer with a microstructure, and the microstructure is a pattern unit periodically repeated in the horizontal and vertical directions; each pattern unit is composed of a base material, a metal patch 6 and a gap area 7 formed by etching, and the metal patch 6 and the gap area 7 are distributed in a two-dimensional central symmetry.

[0155] The base material is a polyimide film 5, and the metal patch 6 is made of copper. The surface resistivity of the pattern unit is 55Ω / sq, and a1=1mm, b1=5mm, and P1=6mm in the pattern unit.

[0156] This embodiment also provides a method for preparing the aforementioned composite ceramic stealth material based on the metasurface subwavelength structure, specifically:

[0157] Step S001: prepare quartz fiber cloth, cyanate resin, and quartz ceramic powder for use.

[0158] The quartz fiber cloth is plain weave with a SiO2 content of 99.92%, a warp density of (20 x 20) strands / cm, and a thickness of 0.1 mm. The quartz fiber has a dielectric constant of 3.72 and a loss tangent of 0.0007. The cyanate ester resin, developed by the Institute of Chemistry of the Chinese Academy of Sciences, has a dielectric constant of 2.91 and a loss tangent of 0.003. The quartz ceramic powder has a particle size of 0.85 μm and a SiO2 purity of 99.3%.

[0159] Step S002: adding quartz ceramic powder, cyanate resin and additives into a solvent and stirring evenly to obtain a prepreg slurry.

[0160] The prepreg slurry contains additives including silane coupling agent KH-550 and dispersant BYK-110, and the solvent is acetone. The mass ratio of quartz ceramic powder, cyanate resin, silane coupling agent KH-550, dispersant BYK-110, and acetone in the prepreg slurry is 60:100:2.5:1.6:40.

[0161] Step S003: pour the prepreg slurry containing cyanate resin / quartz ceramic powder into a prepreg molding device, and then laminate it with quartz fiber cloth at a temperature of 300° C. and a vehicle speed of 5 m / min to form a prepreg.

[0162] The weight ratio of the prepreg slurry to the quartz fiber cloth is 1:1.3.

[0163] Step S004: using a cutting machine to cut the prepreg prepared in step S003 into prepreg tapes with a width of 20 mm and a length greater than 5 m.

[0164] Step S005: Pre-treat the metal antenna by sandblasting with 40# glass sand at a pressure of 0.8 MPa. Chemical etching is then combined with the metal antenna to achieve a surface roughness of Ra 6. The prepreg tape cut and formed in step S004 is then conformally wound around the metal antenna using a winding device until the winding thickness reaches the desired thickness. The first dielectric layer 1 is then formed using an autoclave process.

[0165] During winding, the tape spacing is controlled at 28 mm, the rotation speed is 22 rpm, the tension is 43 N, and the overlap method is that the portion of the latter circle covering the former circle is greater than 50% of the width of the prepreg tape.

[0166] The autoclave process is to first heat the temperature to 130°C at a heating rate of 3°C / min, keep the temperature for 2 hours, then continue to heat the temperature to 190°C at the aforementioned heating rate, keep the temperature for 2 hours, then continue to heat the temperature to 230°C at the aforementioned heating rate, keep the temperature for 3 hours, and then naturally cool to room temperature; at the same time, when the temperature rises to 180°C, apply a nitrogen pressure of 1.0MPa at a pressure increase rate of 0.1MPa / min and maintain the pressure until the end of the treatment.

[0167] Step S006 , processing the first dielectric layer 1 wound on the surface of the metal antenna prepared in step S005 to produce a processed first dielectric layer 1 .

[0168] Among them, the processing is grinding, and PCD tools are selected, the feed speed is 0.05mm / r, the rotation speed is 500r / min, and the cutting depth of each cut is 0.6mm; the thickness of the first dielectric layer 1 is processed to be 2.45mm, the tolerance is ±0.02mm, and the surface roughness is ≤Ra3.2.

[0169] Step S007 , laying the subwavelength structure layer 2 on the processed first dielectric layer 1 obtained in step S006 .

[0170] Among them, the size of the subwavelength structural layer 2 is 500×500mm and the thickness is 0.05mm; the butt-jointing method is adopted during paving, and the distance between the two subwavelength structural layers 2 must be ensured to be the same as the distance between the structural units. The structural units are arranged neatly in the circumferential direction and axial direction, and on a straight line, without any structural unit damage or overlap.

[0171] Step S008: The prepreg tape cut and formed in step S004 is conformally wound around the outer side of the subwavelength structure layer 2 on the metal antenna by a winding molding device until the winding thickness reaches a predetermined requirement, and then the second dielectric layer 3 is prepared by an autoclave process.

[0172] During winding, the tape spacing is controlled at 28 mm, the rotation speed is 22 rpm, the tension is 43 N, and the overlap method is that the portion of the latter circle covering the former circle is greater than 50% of the width of the prepreg tape.

[0173] The specific process and process parameters of the autoclave are the same as those in step S005.

[0174] Step S009 , processing the wound second dielectric layer 3 prepared in step S008 to produce a processed second dielectric layer 3 .

[0175] Among them, the processing is grinding, and PCD tools are selected, the feed speed is 0.05mm / r, the rotation speed is 500r / min, and the cutting depth of each cut is 0.6mm; the thickness of the second dielectric layer 3 is processed to 0.2mm, the tolerance is ±0.02mm, and the surface roughness is ≤Ra3.2.

[0176] Step S010: spraying a polymer-based composite coating (i.e., dense functional layer 4) on the surface of the processed second dielectric layer 3. Specifically, the raw materials for preparing the dense functional layer 4 (material A and material B) are cyclically heated using a dedicated spraying device. When the temperature of material A and material B reaches 65°C, the spraying pressure is set to 17 MPa, and material A and material B are simultaneously sprayed onto the surface of the processed second dielectric layer 3, and the spraying thickness is controlled to be 1.3 mm. After spraying, the coating is placed in a 120°C environment, allowed to stand and cure for 1.5 hours, and then dried at 80°C for 23 hours. The dried coating is then ground to a thickness of 0.8 mm for the dense functional layer 4, and the surface roughness Ra after processing is controlled to be less than 1 μm.

[0177] Among them, the material A is a polymer prepared by using diisocyanate, polypropylene glycol and polydimethylsiloxane as raw materials, and reacting at 85°C for 2 hours in a nitrogen environment; the mass ratio of diisocyanate, polypropylene glycol and polydimethylsiloxane is 100:35:13.

[0178] The material B is composed of the following raw materials: amino-terminated polyether D-200, diethyltoluenediamine, and silicon nitride with a particle size of 2-5 μm; the mass ratio of amino-terminated polyether D-200, diethyltoluenediamine, and silicon nitride is 32:14:8.

[0179] The weight ratio of material A and material B sprayed per unit time is 1:1.6.

[0180] After testing, the composite ceramic stealth material based on the metasurface subwavelength structure of this embodiment has a wave transmittance of 95.6% in the low frequency band below 1 GHz; the average RCS reduction in the X-band is shown in the following table:

[0181]

[0182] As can be seen, the composite ceramic stealth material based on a metasurface subwavelength structure, through the integration of the metasurface subwavelength structure with a composite ceramic matrix, effectively overcomes the technical bottleneck of traditional materials' unadjustable frequency band performance, achieving both high-frequency (X-band) stealth and low-frequency (less than 1 GHz) transmission. The subwavelength hollow metal patch array forms local resonance in the X-band, which, combined with the gradient dielectric design of the first and second dielectric layers, effectively achieves electromagnetic wave phase cancellation and energy absorption. Compared to existing materials, the material achieves a reduction in average RCS of over 10 dB in the X-band. Furthermore, the first and second dielectric layers utilize a low-loss quartz ceramic matrix (loss tangent ≤ 0.003), resulting in a stable dielectric constant and excellent impedance matching at low frequencies below 1 GHz. This increases the wave transmittance to over 95%, significantly surpassing the 30% attenuation of traditional ferrite materials. Furthermore, shortwave 8kW high-power loading and tuning tests demonstrated normal high-power signal transmission and tuning, with radiation directivity and impedance characteristics comparable to those of metal antennas.

[0183] Furthermore, the composite ceramic stealth material based on the metasurface subwavelength structure of the present invention adopts a "sandwich" multi-layer structure (dielectric layer-subwavelength structure layer-dielectric layer-dense functional layer). While ensuring high-frequency stealth and low-frequency wave transmission performance, the total thickness can be controlled within 4mm, which is more than 40% lighter than the traditional 5-8 layer stacking scheme, effectively achieving lightweighting; and the preparation method of the composite ceramic stealth material based on the metasurface subwavelength structure is simple, the preparation process is easy to control, which is conducive to large-scale industrial production, and effectively realizes the engineering feasibility of material preparation.

[0184] Furthermore, testing of the relevant performance of the composite ceramic stealth materials based on the metasurface subwavelength structure of Examples 1-3 revealed the following technical benefits: First, the bonding strength between the treated metal antenna and the first dielectric layer in each example was >10 MPa, reducing the risk of detachment after seawater or oil pressure immersion. Second, in addition to the bonding between the first and second dielectric layers and the subwavelength structure layer using the added cyanate ester resin (interlayer shear strength >50 MPa), the bonding strength between the first and second dielectric layers was enhanced by increasing the pore size of the subwavelength structure layer, resulting in interlayer shear strength >10 MPa between the subwavelength structure layer and each dielectric layer. Third, the addition of a dense functional layer (polyurea composite coating) further enhanced the overall wear and oil resistance of the material, achieving a bonding strength >10 MPa between the dense functional layer and the second dielectric layer. After 2000 cycles of wear resistance (lifting and lowering), the dense functional layer surface remained intact, the antenna lifting function remained normal, and low-frequency communication function tests remained unchanged before and after the test. Furthermore, the composite ceramic stealth materials based on the metasurface subwavelength structure described in each embodiment did not show delamination, blistering, cracking, or falling off after being subjected to tests such as seawater corrosion, seawater impact, high temperature, low temperature, temperature shock, damp heat, and neutral salt spray; after the mold test, the mold resistance level was 0, and they all had good hydrophobicity and adaptability to marine environments, and can be effectively applied to complex marine environments and complex marine electromagnetic environments.

[0185] Unless otherwise specified, all percentages used in the present invention are by mass.

[0186] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A composite ceramic stealth material based on a metasurface subwavelength structure, characterized in that: A first dielectric layer (1), a subwavelength structure layer (2), a second dielectric layer (3), and a dense functional layer (4) are sequentially provided; The first dielectric layer (1) is a quartz fiber reinforced quartz / cyanate composite material with a dielectric constant of 2.9-3.4 and a loss tangent value of ≤0.005; The preparation method of the first dielectric layer (1) is as follows: quartz ceramic powder, cyanate resin and additives are added to a solvent and mixed evenly to obtain a prepreg slurry; the prepreg slurry is placed in a prepreg forming device and compounded with quartz fiber cloth to form a prepreg; the prepreg is cut into prepreg tapes; the prepreg tapes are wrapped around the metal antenna in a form-fitting manner, and the first dielectric layer (1) is formed by a hot-pressing process; In the preparation of the first dielectric layer (1), the auxiliary agents include: silane coupling agent KH-550, dispersant BYK-110; the solvent is acetone; the mass ratio of quartz ceramic powder, cyanate resin, silane coupling agent KH-550, dispersant BYK-110, and acetone in the prepreg slurry is 50-60:100:2.2-2.5:1.4-1.6:35-40; The sub-wavelength structure layer (2) is composed of periodic pattern units having hollow metal patches (6); The second dielectric layer (3) is a quartz fiber reinforced quartz / cyanate composite material with a dielectric constant of 2.9-3.4 and a loss tangent value of ≤0.005; The preparation method of the second dielectric layer (3) is as follows: quartz ceramic powder, cyanate resin and additives are added to a solvent and mixed evenly to obtain a prepreg slurry; the prepreg slurry is placed in a prepreg forming device and compounded with quartz fiber cloth to form a prepreg; the prepreg is cut into prepreg tapes; the prepreg tapes are wrapped around the outer side of the subwavelength structure layer (2) on the metal antenna, and the second dielectric layer (3) is formed by a hot-pressing process; In the preparation of the second dielectric layer (3), the auxiliary agents include: silane coupling agent KH-550, dispersant BYK-110; the solvent is acetone; the mass ratio of quartz ceramic powder, cyanate resin, silane coupling agent KH-550, dispersant BYK-110, and acetone in the prepreg slurry is 50-60:100:2.2-2.5:1.4-1.6:35-40; The dense functional layer (4) is a polymer-based composite coating with a dielectric constant of 3.0-3.3 and a loss tangent value of ≤0.

008.

2. The composite ceramic stealth material based on the metasurface subwavelength structure according to claim 1 is characterized in that: The thickness of the first dielectric layer (1) is 1.7-2.5 mm, the thickness of the subwavelength structure layer (2) is 0.025-0.08 mm, the thickness of the second dielectric layer (3) is 0.1-0.3 mm, and the thickness of the dense functional layer (4) is 0.5-1.2 mm.

3. The composite ceramic stealth material based on the metasurface subwavelength structure according to claim 1 is characterized in that: The pattern units of the sub-wavelength structure layer (2) are composed of a base material, a metal patch (6) and a void region (7) formed by etching, and the metal patch (6) and the void region (7) are distributed in a two-dimensional central symmetric manner; The base material is a polyimide film (5); The material of the metal patch (6) is one of the following: gold, silver, copper; The period of the pattern unit is 5.0-6.0 mm, the side length of the metal patch (6) is 4.0-5.0 mm, the side length of the gap area (7) is 1.0-1.8 mm, and the surface resistivity is 50-60 Ω / sq.

4. A method for preparing a composite ceramic stealth material based on a metasurface subwavelength structure according to any one of claims 1 to 3, characterized in that: The following steps are involved: Step S002: adding quartz ceramic powder, cyanate resin and additives into a solvent and mixing them evenly to obtain a prepreg slurry; In step S002, the particle size of the quartz ceramic powder is ≤1 μm, the SiO2 purity is ≥99%; the cyanate ester resin has a dielectric constant of 2.8-3.0 and a loss tangent of <0.005; In step S002, the auxiliary agents include: silane coupling agent KH-550, dispersant BYK-110; the solvent is acetone; the mass ratio of quartz ceramic powder, cyanate resin, silane coupling agent KH-550, dispersant BYK-110, and acetone in the prepreg slurry is 50-60:100:2.2-2.5:1.4-1.6:35-40; Step S003: placing the prepreg slurry in a prepreg forming device and compounding it with quartz fiber cloth to form a prepreg; In step S003, the quartz fiber cloth is a plain weave cloth, has a SiO2 content of ≥99.9%, a warp and weft density of at least 20×20 strands / cm, and a thickness of 0.1±0.05 mm; the dielectric constant of the quartz fiber in the quartz fiber cloth is 3.7-3.8, and the loss tangent value is <0.001; Step S004: cutting the prepreg into prepreg tapes; Step S005, wrapping the prepreg tape onto the metal antenna in a form-fitting manner, and forming a first dielectric layer (1) through an autoclave process; Step S006, processing the first dielectric layer (1) to a predetermined thickness to produce a processed first dielectric layer (1); Step S007, laying the subwavelength structure layer (2) on the processed first dielectric layer (1); Step S008, wrapping the prepreg tape conformally onto the outer side of the subwavelength structure layer (2) on the metal antenna, and forming a second dielectric layer (3) through an autoclave process; Step S009, processing the second dielectric layer (3) to a predetermined thickness to produce a processed second dielectric layer (3); Step S010, spraying a dense functional layer (4) on the surface of the processed second dielectric layer (3) to obtain a composite ceramic stealth material based on a metasurface subwavelength structure; In the step S010, the dense functional layer (4) is prepared by spraying by cyclically heating the material A and the material B respectively, spraying the material A and the material B simultaneously onto the surface of the processed second dielectric layer (3) under the condition of a spraying pressure of 15-17 MPa, and controlling the spraying thickness within 1.5 mm; after the spraying is completed, the material A and the material B are cured and dried, and then processed to a predetermined thickness; The material A is a polymer made from diisocyanate, polypropylene glycol and polydimethylsiloxane; The material B is composed of the following raw materials: amino-terminated polyether D-200, diethyltoluenediamine, and silicon nitride with a particle size of 2-5 μm.

5. The method for preparing a composite ceramic stealth material based on a metasurface subwavelength structure according to claim 4, characterized in that: In step S003, the composite temperature of the prepreg slurry and the quartz fiber cloth in the prepreg molding device is 260°C-300°C, and the vehicle speed is 3-5m / min; In step S005, the tape pitch during winding is controlled at 15-28 mm, the rotation speed is 20-22 rpm, and the tension is 40-43 N; In step S008, the tape pitch is controlled at 15-28 mm, the rotation speed is 20-22 rpm, and the tension is 40-43 N during winding.

6. The method for preparing a composite ceramic stealth material based on a metasurface subwavelength structure according to claim 4, characterized in that: In step S005, the autoclave process is to first heat the temperature to 110-130°C at a heating rate of 1-3°C / min, keep the temperature for 1-2 hours, then continue to heat the temperature to 160-190°C, keep the temperature for 1-2 hours, then continue to heat the temperature to 210-230°C, keep the temperature for 2-3 hours, and then cool to room temperature; at the same time, when the temperature rises to 180°C, apply a pressure of 0.7-1.0 MPa and maintain it until the end of the process; In step S008, the autoclave process is to first heat the temperature to 110-130°C at a heating rate of 1-3°C / min, keep the temperature for 1-2 hours, then continue to heat the temperature to 160-190°C, keep the temperature for 1-2 hours, then continue to heat the temperature to 210-230°C, keep the temperature for 2-3 hours, and then cool to room temperature; at the same time, when the temperature rises to 180°C, apply a pressure of 0.7-1.0 MPa and maintain it until the end of the process.

7. The method for preparing a composite ceramic stealth material based on a metasurface subwavelength structure according to claim 4, characterized in that: The material A is a polymer prepared by using diisocyanate, polypropylene glycol, and polydimethylsiloxane as raw materials, and reacting at 80-85°C in a nitrogen environment for 2-3 hours; the mass ratio of the diisocyanate, polypropylene glycol, and polydimethylsiloxane is 100:30-35:10-13; The mass ratio of the amino-terminated polyether D-200, diethyltoluenediamine, and silicon nitride in the material B is 30-32:13-14:7-8; The weight ratio of material A to material B sprayed per unit time is 1:1.5-1.6.

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