A metamaterial honeycomb and a method of making the same

Abstract

The application discloses a kind of metamaterial honeycomb and preparation method thereof, it is related to aramid paper honeycomb technical field.The preparation method of the metamaterial honeycomb includes: aramid paper is modified electromagnetically, gluing and ablation, superposition, press, stretch setting, pre-solidification, after reaching target density, the metamaterial honeycomb can be obtained.The method is modified to aramid paper honeycomb from the source aramid paper in the application, and alloy material is plated on the surface of aramid paper as electromagnetic function layer to realize the modulation of electromagnetic wave, which can realize wideband wave absorption, and the wave absorption performance can be designed, which is better than conventional wave absorption honeycomb, can greatly reduce the density of wave absorption honeycomb and realize excellent wave absorption performance at the same time, reduce the reflectivity difference of TE, TM two directions, so as to reduce the limitation of reflectivity difference of honeycomb on product design.

Description

Technical Field

[0001] This invention relates to the field of aramid paper honeycomb technology, and more specifically, to a metamaterial honeycomb and its preparation method. Background Technology

[0002] Aramid paper honeycomb possesses excellent mechanical properties, high temperature resistance, corrosion resistance, and lightweight characteristics, making it widely used in aerospace, rail transportation, and defense industries. In recent years, the emergence of stealth technology has significantly altered the nature of future warfare. To evade radar detection, the fabrication of novel structural absorbing honeycomb structures is of paramount importance. However, while aramid paper honeycomb is an ideal wave-transmitting material, it lacks excellent electromagnetic response capabilities, thus failing to achieve the stealth effect required for aircraft.

[0003] To fabricate ideal structural functional honeycombs, the traditional method involves first preparing a honeycomb core material using a honeycomb fabrication process, and then impregnating the honeycomb core material with a microwave absorbing agent to obtain an absorbing honeycomb. Although this fabrication method is relatively simple, it is difficult to achieve precise design of gradient honeycomb electromagnetic parameters due to factors such as thickness and gravity. Moreover, the honeycombs obtained by this method have significant differences in reflectivity in the TE / TM directions, leading to many limitations in design and use.

[0004] Therefore, how to achieve excellent absorption performance while significantly reducing the reflectivity difference in the TE / TM direction has always been a goal that the industry urgently needs to improve. Summary of the Invention

[0005] The main objective of this invention is to provide a metamaterial honeycomb and its preparation method, so as to solve the technical problem that the prior art cannot achieve a significant reduction in the reflectivity difference in the TE / TM direction while ensuring excellent wave absorption performance.

[0006] To achieve the above objectives, according to a first aspect of the present invention, a method for preparing a metamaterial honeycomb is provided, comprising the following steps:

[0007] S1, an alloy material is plated on the surface of aramid paper to obtain electromagnetically modified aramid paper;

[0008] S2, apply adhesive to the electromagnetically modified aramid paper, and after the adhesive is applied, ablate the alloy material at the node position of the electromagnetically modified aramid paper.

[0009] S3, the electromagnetically modified aramid paper after coating and ablation is stacked according to the required dimensions in the width direction using a staggered stacking method;

[0010] S4, Press the stacked aramid paper blocks together;

[0011] S5, stretch and shape the pressed aramid paper block to obtain a semi-finished honeycomb;

[0012] S6, the semi-finished honeycomb is impregnated in resin and pre-cured;

[0013] S7. Repeat S6 until the cell density reaches the preset target density to obtain the metamaterial cell.

[0014] Furthermore, in step S1, the alloy material includes aluminum alloy, nickel alloy, or silicon alloy.

[0015] Further, in step S2, after adjusting the mixing ratio of the node adhesive and ethyl acetate and the viscosity of the mixed adhesive solution, and setting the number of core strips, the length of the paper cut, and the coating rate, the electromagnetically modified aramid paper is coated with adhesive.

[0016] Furthermore, in step S4, the pressing is carried out at a temperature of 150℃-250℃ and a pressure of 0.4Mpa-1Mpa for 3-6 hours.

[0017] Furthermore, in step S5, the aramid paper block after pressing is stretched to the preset theoretical length using a honeycomb stretching machine at a stretching rate of 80-120 mm / min.

[0018] Furthermore, in step S5, after stretching, the product is placed in a shaping oven and cured at a temperature of 200-300℃ for 2-3 hours to achieve shaping.

[0019] Furthermore, in step S6, the resin is phenolic resin, and the pre-curing temperature is 120℃~150℃, and the time is 0.5h~2h.

[0020] Furthermore, in step S7, the target density is 30 kg / m³ to 150 kg / m³.

[0021] Furthermore, in step S1, the honeycomb grid of the aramid paper is hexagonal or rectangular.

[0022] According to a second aspect of the present invention, a metamaterial honeycomb is provided, which is prepared by the above-described preparation method.

[0023] The preparation method disclosed in this invention can be used to prepare metamaterial honeycomb with excellent wave absorption performance over a wide frequency range. While achieving excellent wave absorption performance, it can significantly reduce the reflectivity difference in the TE / TM direction and increase the compressive strength at the same density. This can significantly reduce the weight of functional structural components of aircraft and improve the cost-effectiveness of aircraft. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating the fabrication process of metamaterial honeycomb in an embodiment of the present invention.

[0025] Figure 2 This is a schematic diagram of the paper stacking structure in an embodiment of the present invention.

[0026] Figure 3 This is a schematic diagram of the actual object after the coating alloy material on the back of the joint adhesive has been ablated using a laser device in an embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0028] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0029] As described in the background section of this invention, existing technologies suffer from the inability to significantly reduce the reflectivity difference in the TE / TM directions while ensuring excellent absorption performance. To address this problem, in a typical embodiment of this invention, a method for fabricating a metamaterial honeycomb is provided, the flowchart of which is shown below. Figure 1 As shown, it includes the following steps:

[0030] S1, an alloy material is plated on the surface of aramid paper to obtain electromagnetically modified aramid paper;

[0031] S2, apply adhesive to the electromagnetically modified aramid paper, and after the adhesive is applied, ablate the alloy material at the node position of the electromagnetically modified aramid paper.

[0032] S3, the electromagnetically modified aramid paper, after being coated and ablated, is stacked according to the required dimensions in the width direction using a staggered stacking method (e.g., ...). Figure 2 (as shown);

[0033] S4, Press the stacked aramid paper blocks together;

[0034] S5, stretch and shape the pressed aramid paper block to obtain a semi-finished honeycomb;

[0035] S6, the semi-finished honeycomb is impregnated in resin and pre-cured;

[0036] S7. Repeat S6 until the cell density reaches the preset target density to obtain the metamaterial cell.

[0037] The aramid paper honeycomb is empowered from the source of the aramid paper, that is, an alloy material is coated on the surface of the aramid paper to obtain electromagnetically modified aramid paper. After the improvement, while achieving excellent wave absorption performance, the reflectivity difference in the TE / TM direction can be significantly reduced.

[0038] The method described in this invention allows for flexible control of the density of metamaterial honeycomb through impregnation and pre-curing cycles, thereby meeting the specific needs of different application scenarios.

[0039] Through steps such as pressing, stretching and curing, the stability of metamaterial honeycomb structures can be ensured, avoiding structural deformation or damage during the process or subsequent use, thereby guaranteeing the consistency and stability of their wave absorption performance.

[0040] In some embodiments, in S1, the alloy material includes aluminum alloy, nickel alloy, or silicon alloy. Coating the alloy material onto the surface of aramid paper enables broadband wave absorption, and the absorption performance can be designed using different alloy materials, resulting in overall performance superior to conventional absorbing honeycomb structures in the prior art. The alloy material of the coating serves as the electromagnetic functional layer of the metamaterial honeycomb, used to modulate electromagnetic waves. The absorption performance of the metamaterial honeycomb can be designed using different coating alloy materials, achieving overall performance superior to existing conventional absorbing honeycomb structures and enabling broadband wave absorption.

[0041] In some embodiments, in step S2, after adjusting the mixing ratio of the node adhesive and ethyl acetate and the viscosity of the mixed adhesive solution, and setting the number of core strips, the paper cutting length, and the coating rate, the electromagnetically modified aramid paper is coated with adhesive. After coating, the alloy coating material on the back of the node adhesive is ablated at the node adhesive location using a laser device. The resulting image is shown below. Figure 3 As shown.

[0042] In some embodiments, in step S4, the pressing is performed at a temperature of 150°C-250°C and a pressure of 0.4 MPa-1 MPa for 3-6 hours. Pressing under these conditions can improve the curing effect of the core adhesive, enhance the bonding strength between the aramid composite paper and the core adhesive, and thus improve the structural stability of the metamaterial honeycomb.

[0043] In some embodiments, in step S5, the aramid paper block after pressing is stretched to a preset theoretical length using a honeycomb stretching machine at a stretching rate of 80-120 mm / min. During the process of stretching the composite paper block into a honeycomb structure, a certain amount of residual stress is generated inside the material. After the tensile force is removed, the uncured honeycomb may shrink or deform due to the residual stress, resulting in unstable geometric dimensions and affecting its performance as a structural material. Stretching under the above conditions can improve the stability of the structural material.

[0044] In some embodiments, in step S5, after stretching, the material is placed in a setting oven and cured at 200-300°C for 2-3 hours to achieve the desired shape. Under these conditions, curing and shaping after stretching can also improve the stability of the structural material.

[0045] In some embodiments, in step S6, the resin is phenolic resin, and the pre-curing temperature is 120℃~150℃, with a time of 0.5h~2h. The purpose of resin impregnation and pre-curing in step S6 is to improve the mechanical properties of the metamaterial honeycomb, such as compressive strength, tensile strength, and impact resistance. Through resin impregnation, the structure of the metamaterial honeycomb becomes more compact, enabling it to withstand greater external forces, thereby improving its overall mechanical properties. Furthermore, resin impregnation can also improve the processing performance, molding performance, and chemical stability of the aramid honeycomb, thus improving its durability and service life.

[0046] The purpose of controlling the pre-curing and curing conditions is as follows: During the pre-curing stage, controlling the temperature and time ensures that the resin fully impregnates every tiny pore of the aramid paper, forming a more uniform composite structure and preventing the resin from curing too quickly at high temperatures, which would limit its flowability. By controlling the curing temperature and time within the aforementioned range, the resin can be fully cured, forming a stable three-dimensional cross-linked network, improving the mechanical strength and stiffness of the metamaterial honeycomb, and enhancing the overall structural stability and durability.

[0047] In some embodiments, the resin is a phenolic resin (e.g., F01-30, 2124, etc.), or the resin may also be a polyimide resin (e.g., GI001, etc.). The selection of at least one of phenolic resin and polyimide resin as the resin matrix for the metamaterial honeycomb is primarily due to the excellent thermal stability, good dielectric properties, high strength and stiffness, chemical stability, low hygroscopicity, environmental adaptability, good processing performance, and environmental friendliness of these resins. These advantages work together to enable the metamaterial honeycomb to maintain a stable structure and efficient wave absorption performance under complex environmental conditions, making it suitable for various fields such as aerospace and defense. The basic structure of the honeycomb wall of the resulting metamaterial honeycomb is: phenolic resin - alloy material - aramid paper - phenolic resin, or phenolic resin - alloy material - aramid paper - alloy material - phenolic resin, polyimide resin - alloy material - aramid paper - polyimide resin, or polyimide resin - alloy material - aramid paper - alloy material - polyimide resin.

[0048] In some embodiments, in step S7, the target density is 30 kg / m³. 3 ~150kg / m 3 Controlling the target density opens up broader applications for metamaterial cellular structures. Lower densities (e.g., close to 30 kg / m³) 3 This means lighter weight, which is especially important in the aerospace industry because it directly affects a vehicle's payload capacity and fuel efficiency. Higher density (e.g., close to 150 kg / m³) also contributes to this. 3 This density flexibility can provide better mechanical strength and stiffness, making it more suitable for structural components that withstand higher loads. This density flexibility allows metamaterial honeycombs to adapt to the needs of different application scenarios, improving their applicability and innovation in multiple industries. The metamaterial honeycomb prepared by this invention has a low density, the same as that of ordinary white honeycomb, and less than 50% of the density of existing conventional microwave absorbing honeycombs. Furthermore, controlling the density by controlling the number of impregnation cycles ensures that the metamaterial honeycomb possesses both good structural integrity and microwave absorption performance.

[0049] In some embodiments, in step S1, the honeycomb cells of the aramid paper are hexagonal or rectangular. This structural design can increase the compressive strength at the same density and significantly reduce the weight of functional structural components of the aircraft, improving the cost-effectiveness of the aircraft and enhancing the structural stability of the metamaterial honeycomb.

[0050] In another typical embodiment of the present invention, a metamaterial honeycomb prepared by the preparation method described in the above embodiments is provided. This metamaterial honeycomb exhibits excellent wave absorption performance over a wide frequency range. While achieving excellent wave absorption performance, it can significantly reduce the reflectivity difference in the TE / TM direction and increase the compressive strength at the same density. This can significantly reduce the weight of functional structural components of aircraft, improve the cost-effectiveness of aircraft, and enhance the structural stability of the metamaterial honeycomb, thus broadening its application fields. Because the metamaterial honeycomb of the present invention has lightweight, structural stability, and wave absorption performance over a wide frequency range, it is suitable for application in the aerospace and defense industries.

[0051] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0052] Some of the materials used in the examples are as follows:

[0053] Resin: Phenolic resin, model F01-30;

[0054] Aramid paper: thickness 0.03mm-0.08mm, model YT-836;

[0055] Core strip adhesive: Model J-80B;

[0056] Joint adhesive: Model J-80B Nomex;

[0057] Example 1

[0058] One embodiment of the metamaterial honeycomb of the present invention is described below, and the specific method for preparing the metamaterial honeycomb is as follows:

[0059] S1, Aluminum alloy material is coated on the surface of aramid paper with a thickness of 0.08mm to obtain electromagnetically modified aramid paper, forming a structure of aluminum alloy material + aramid paper, or a structure of aluminum alloy material + aramid paper + aluminum alloy material, to make a composite thin layer, wherein the S21 of aramid paper is controlled within the range of -1dB to 0, and the honeycomb pores of aramid paper are hexagonal or rectangular;

[0060] S2, adjust the mixing ratio and viscosity of J-80B Nomex joint adhesive and ethyl acetate, and set parameters such as the number of core strips, paper cutting length, and coating rate. Then, apply the adhesive to the electromagnetically modified aramid paper. After coating, use a laser device to ablate the alloy coating material on the back of the joint adhesive at the joint location. The actual image after ablation is shown below. Figure 3 As shown;

[0061] S3, the electromagnetically modified aramid paper after coating and ablation is stacked according to the required dimensions in the width direction (i.e., W direction) in a staggered stacking manner.

[0062] S4, press the aramid paper blocks after stacking the paper; specifically, according to the curing parameters of the joint adhesive, press for 3 hours at a temperature of 180℃ and a pressure of 0.5Mpa, and then cool down and release the pressure;

[0063] S5, stretch and shape the aramid paper block after pressing to obtain a semi-finished honeycomb; specifically, use a honeycomb stretching machine to stretch the aramid paper block after pressing to the preset theoretical length at a stretching rate of 100mm / min, and then put it into a setting oven to cure at a temperature of 260℃ for 2 hours for setting.

[0064] S6, the semi-finished honeycomb is impregnated and pre-cured in resin; specifically, the stretched and shaped semi-finished honeycomb is impregnated with phenolic resin according to the target density. The pre-curing temperature is 130°C and the time is 1 hour. If the target density is not reached, the impregnation is repeated until the target density is reached.

[0065] S7, Repeat S6 until the honeycomb density reaches the preset target density, thus obtaining the metamaterial honeycomb, where the target density is 30 kg / m³. 3 ~150kg / m 3 .

[0066] Example 2

[0067] One embodiment of the metamaterial honeycomb of the present invention is described below, and the specific method for preparing the metamaterial honeycomb is as follows:

[0068] S1, a nickel alloy material is plated on the surface of aramid paper with a thickness of 0.05mm to obtain electromagnetically modified aramid paper, forming a structure of nickel alloy material + aramid paper, or a structure of nickel alloy material + aramid paper + nickel alloy material, to make a composite thin layer, wherein the S21 of aramid paper is controlled within the range of -0.5dB to 0, and the honeycomb pores of aramid paper are hexagonal or rectangular;

[0069] S2, adjust the mixing ratio and viscosity of J-80B Nomex joint adhesive and ethyl acetate, and set parameters such as the number of core strips, paper cutting length, and coating rate. Then, apply the adhesive to the electromagnetically modified aramid paper. After coating, use a laser device to ablate the alloy coating material on the back of the joint adhesive at the joint location. The actual image after ablation is shown below. Figure 3 As shown;

[0070] S3, the electromagnetically modified aramid paper after coating and ablation is stacked according to the required size in the width direction (i.e. W direction) in a staggered stacking manner.

[0071] S4, press the aramid paper blocks after stacking the paper; specifically, according to the curing parameters of the joint adhesive, press for 3 hours at a temperature of 180℃ and a pressure of 0.5Mpa, and then cool down and release the pressure;

[0072] S5, stretch and shape the aramid paper block after pressing to obtain a semi-finished honeycomb; specifically, use a honeycomb stretching machine to stretch the aramid paper block after pressing to the preset theoretical length at a stretching rate of 90mm / min, and then put it into a setting oven to cure at a temperature of 230℃ for 2 hours for setting.

[0073] S6, the semi-finished honeycomb is impregnated and pre-cured in resin; specifically, the stretched and shaped semi-finished honeycomb is impregnated with phenolic resin according to the target density. The pre-curing temperature is 130°C and the time is 1 hour. If the target density is not reached, the impregnation is repeated until the target density is reached.

[0074] S7, Repeat S6 until the honeycomb density reaches the preset target density, thus obtaining the metamaterial honeycomb, where the target density is 30 kg / m³. 3 ~150kg / m 3 .

[0075] Example 3

[0076] One embodiment of the metamaterial honeycomb of the present invention is described below, and the specific method for preparing the metamaterial honeycomb is as follows:

[0077] S1, a silicon alloy material is deposited on the surface of aramid paper with a thickness of 0.08mm to obtain electromagnetically modified aramid paper, forming a structure of silicon alloy material + aramid paper, or a structure of silicon alloy material + aramid paper + silicon alloy material, to make a composite thin layer, wherein the S21 of aramid paper is controlled within the range of -0.1dB to 0, and the honeycomb pores of aramid paper are hexagonal or rectangular;

[0078] S2, adjust the mixing ratio and viscosity of J-80B Nomex joint adhesive and ethyl acetate, and set parameters such as the number of core strips, paper cutting length, and coating rate. Then, apply the adhesive to the electromagnetically modified aramid paper. After coating, use a laser device to ablate the alloy coating material on the back of the joint adhesive at the joint location. The actual image after ablation is shown below. Figure 3 As shown;

[0079] S3, the electromagnetically modified aramid paper after coating and ablation is stacked according to the required size in the width direction (i.e. W direction) in a staggered stacking manner.

[0080] S4, press the aramid paper blocks after stacking the paper; specifically, according to the curing parameters of the joint adhesive, press for 3 hours at a temperature of 160℃ and a pressure of 0.7Mpa, and then cool down and release the pressure;

[0081] S5, stretch and shape the aramid paper block after pressing to obtain a semi-finished honeycomb; specifically, use a honeycomb stretching machine to stretch the aramid paper block after pressing to the preset theoretical length at a stretching rate of 90mm / min, and then put it into a setting oven to cure at a temperature of 200℃ for 3 hours for setting.

[0082] S6, the semi-finished honeycomb is impregnated and pre-cured in resin; specifically, the stretched and shaped semi-finished honeycomb is impregnated with phenolic resin according to the target density. The pre-curing temperature is 120°C and the time is 2 hours. If the target density is not reached, the impregnation is repeated until the target density is reached.

[0083] S7, Repeat S6 until the honeycomb density reaches the preset target density, thus obtaining the metamaterial honeycomb, where the target density is 30 kg / m³. 3 ~150kg / m 3 .

[0084] Example 4

[0085] One embodiment of the metamaterial honeycomb of the present invention is described below, and the specific method for preparing the metamaterial honeycomb is as follows:

[0086] S1, Aluminum alloy material is coated on the surface of aramid paper with a thickness of 0.08mm to obtain electromagnetically modified aramid paper, forming a structure of aluminum alloy material + aramid paper, or a structure of aluminum alloy material + aramid paper + aluminum alloy material, to make a composite thin layer, wherein the S21 of aramid paper is controlled within the range of -0.2dB to 0, and the honeycomb pores of aramid paper are hexagonal or rectangular;

[0087] S2, adjust the mixing ratio and viscosity of J-80B Nomex joint adhesive and ethyl acetate, and set parameters such as the number of core strips, paper cutting length, and coating rate. Then, apply the adhesive to the electromagnetically modified aramid paper. After coating, use a laser device to ablate the alloy coating material on the back of the joint adhesive at the joint location. The actual image after ablation is shown below. Figure 3 As shown;

[0088] S3, the electromagnetically modified aramid paper after coating and ablation is stacked according to the required size in the width direction (i.e. W direction) in a staggered stacking manner.

[0089] S4, press the aramid paper blocks after stacking the paper; specifically, according to the curing parameters of the joint adhesive, press for 3 hours at a temperature of 150℃ and a pressure of 0.4Mpa, and then cool down and release the pressure;

[0090] S5, stretch and shape the aramid paper block after pressing to obtain a semi-finished honeycomb; specifically, use a honeycomb stretching machine to stretch the aramid paper block after pressing to the preset theoretical length at a stretching rate of 80mm / min, and then put it into a setting oven to cure at a temperature of 200℃ for 2 hours for setting.

[0091] S6, the semi-finished honeycomb is impregnated and pre-cured in resin; specifically, the stretched and shaped semi-finished honeycomb is impregnated with phenolic resin according to the target density. The pre-curing temperature is 120°C and the time is 0.5h. If the target density is not reached, the impregnation is repeated until the target density is reached.

[0092] S7, Repeat S6 until the honeycomb density reaches the preset target density, thus obtaining the metamaterial honeycomb, where the target density is 30 kg / m³. 3 ~150kg / m 3 .

[0093] Example 5

[0094] One embodiment of the metamaterial honeycomb of the present invention is described below, and the specific method for preparing the metamaterial honeycomb is as follows:

[0095] S1, a nickel alloy material is plated on the surface of aramid paper with a thickness of 0.08mm to obtain electromagnetically modified aramid paper, forming a structure of nickel alloy material + aramid paper, or a structure of nickel alloy material + aramid paper + nickel alloy material, to make a composite thin layer, wherein the S21 of aramid paper is controlled within the range of -0.4dB to 0, and the honeycomb pores of aramid paper are hexagonal or rectangular;

[0096] S2, adjust the mixing ratio and viscosity of J-80B Nomex joint adhesive and ethyl acetate, and set parameters such as the number of core strips, paper cutting length, and coating rate. Then, apply the adhesive to the electromagnetically modified aramid paper. After coating, use a laser device to ablate the alloy coating material on the back of the joint adhesive at the joint location. The actual image after ablation is shown below. Figure 3 As shown;

[0097] S3, the electromagnetically modified aramid paper after coating and ablation is stacked according to the required size in the width direction (i.e. W direction) in a staggered stacking manner.

[0098] S4, press the aramid paper blocks after stacking the paper; specifically, according to the curing parameters of the joint adhesive, press for 6 hours at a temperature of 250°C and a pressure of 1 MPa, and then cool down and release the pressure.

[0099] S5, stretch and shape the aramid paper block after pressing to obtain a semi-finished honeycomb; specifically, use a honeycomb stretching machine to stretch the aramid paper block after pressing to the preset theoretical length at a stretching rate of 1200mm / min, and then put it into a setting oven to cure at a temperature of 300℃ for 3 hours for setting.

[0100] S6, the semi-finished honeycomb is impregnated and pre-cured in resin; specifically, the stretched and shaped semi-finished honeycomb is impregnated with phenolic resin according to the target density. The pre-curing temperature is 150°C and the time is 2 hours. If the target density is not reached, the impregnation is repeated until the target density is reached.

[0101] S7, Repeat S6 until the honeycomb density reaches the preset target density, thus obtaining the metamaterial honeycomb, where the target density is 30 kg / m³. 3 ~150kg / m 3 .

[0102] Example 6

[0103] One embodiment of the metamaterial honeycomb of the present invention is described below, and the specific method for preparing the metamaterial honeycomb is as follows:

[0104] S1, a silicon alloy material is deposited on the surface of aramid paper with a thickness of 0.08mm to obtain electromagnetically modified aramid paper, forming a structure of silicon alloy material + aramid paper, or a structure of silicon alloy material + aramid paper + silicon alloy material, to make a composite thin layer, wherein the S21 of aramid paper is controlled within the range of -0.3dB to 0, and the honeycomb pores of aramid paper are hexagonal or rectangular;

[0105] S2, adjust the mixing ratio and viscosity of J-80B Nomex joint adhesive and ethyl acetate, and set parameters such as the number of core strips, paper cutting length, and coating rate. Then, apply the adhesive to the electromagnetically modified aramid paper. After coating, use a laser device to ablate the alloy coating material on the back of the joint adhesive at the joint location. The actual image after ablation is shown below. Figure 3 As shown;

[0106] S3, the electromagnetically modified aramid paper after coating and ablation is stacked according to the required size in the width direction (i.e. W direction) in a staggered stacking manner.

[0107] S4, press the aramid paper blocks after stacking the paper; specifically, according to the curing parameters of the joint adhesive, press for 5 hours at a temperature of 230℃ and a pressure of 0.9Mpa, and then cool down and release the pressure;

[0108] S5, stretch and shape the aramid paper block after pressing to obtain a semi-finished honeycomb; specifically, use a honeycomb stretching machine to stretch the aramid paper block after pressing to the preset theoretical length at a stretching rate of 110mm / min, and then put it into a setting oven to cure at a temperature of 280℃ for 2.5 hours for setting.

[0109] S6, the semi-finished honeycomb is impregnated and pre-cured in resin; specifically, the stretched and shaped semi-finished honeycomb is impregnated with phenolic resin according to the target density. The pre-curing temperature is 130°C and the time is 1.5h. If the target density is not reached, the impregnation is repeated until the target density is reached.

[0110] S7, Repeat S6 until the honeycomb density reaches the preset target density, thus obtaining the metamaterial honeycomb, where the target density is 30 kg / m³. 3 ~150kg / m 3 .

[0111] Example 7

[0112] One embodiment of the metamaterial honeycomb of the present invention is described below, and the specific method for preparing the metamaterial honeycomb is as follows:

[0113] S1, Aluminum alloy material is coated on the surface of aramid paper with a thickness of 0.08mm to obtain electromagnetically modified aramid paper, forming a structure of aluminum alloy material + aramid paper, or a structure of aluminum alloy material + aramid paper + aluminum alloy material, to make a composite thin layer, wherein the S21 of aramid paper is controlled within the range of -0.2dB to 0, and the honeycomb pores of aramid paper are hexagonal or rectangular;

[0114] S2, adjust the mixing ratio and viscosity of J-80B Nomex joint adhesive and ethyl acetate, and set parameters such as the number of core strips, paper cutting length, and coating rate. Then, apply the adhesive to the electromagnetically modified aramid paper. After coating, use a laser device to ablate the alloy coating material on the back of the joint adhesive at the joint location. The actual image after ablation is shown below. Figure 3 As shown;

[0115] S3, the electromagnetically modified aramid paper after coating and ablation is stacked according to the required size in the width direction (i.e. W direction) in a staggered stacking manner.

[0116] S4, press the aramid paper blocks after stacking the paper; specifically, according to the curing parameters of the joint adhesive, press for 4 hours at a temperature of 190℃ and a pressure of 0.8Mpa, and then cool down and release the pressure;

[0117] S5, stretch and shape the aramid paper block after pressing to obtain a semi-finished honeycomb; specifically, use a honeycomb stretching machine to stretch the aramid paper block after pressing to the preset theoretical length at a stretching rate of 100mm / min, and then put it into a setting oven to cure at a temperature of 250℃ for 2 hours for setting.

[0118] S6, the semi-finished honeycomb is impregnated and pre-cured in resin; specifically, the stretched and shaped semi-finished honeycomb is impregnated with phenolic resin according to the target density. The pre-curing temperature is 130°C and the time is 1 hour. If the target density is not reached, the impregnation is repeated until the target density is reached.

[0119] S7, Repeat S6 until the honeycomb density reaches the preset target density, thus obtaining the metamaterial honeycomb, where the target density is 30 kg / m³. 3 ~150kg / m 3 .

[0120] Performance testing

[0121] Reflectivity test: The test was conducted according to the national military standard "GJB 2038A-2011 Test Method for Reflectivity of Radar Absorbing Materials". The results are shown in Table 1.

[0122] Table 1

[0123]

[0124] The test results above show that the metamaterial honeycomb in this embodiment exhibits low reflectivity at 10 GHz. This indicates that the metamaterial honeycomb in this embodiment has excellent wave absorption performance over a wide frequency range, and the reflectivity difference in the TE and TM directions is less than 2 dB. This demonstrates that while achieving excellent wave absorption performance, it can significantly reduce the reflectivity difference in the TE / TM directions, while increasing the compressive strength at the same density. This can significantly reduce the weight of functional structural components of aircraft, improve the cost-effectiveness of aircraft, and enhance the structural stability of metamaterial honeycomb, thus broadening its application areas. Because the metamaterial honeycomb of this invention is lightweight, structurally stable, and has wave absorption performance over a wide frequency range, it is suitable for application in the aerospace and defense industries.

[0125] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing metamaterial honeycomb, characterized in that, Includes the following steps: S1, an alloy material is coated on the surface of aramid paper to obtain electromagnetically modified aramid paper. The alloy material includes aluminum alloy, nickel alloy, or silicon alloy. The coated alloy material serves as the electromagnetic functional layer of the metamaterial honeycomb to achieve modulation of electromagnetic waves. The wave absorption performance of the metamaterial honeycomb is designed by different coated alloy materials to achieve broadband wave absorption. S2, apply adhesive to the electromagnetically modified aramid paper, and after the adhesive is applied, ablate the alloy material at the node position of the electromagnetically modified aramid paper. S3, the electromagnetically modified aramid paper after coating and ablation is stacked according to the required dimensions in the width direction using a staggered stacking method; S4, Press the stacked aramid paper blocks together; S5, stretch and shape the pressed aramid paper block to obtain a semi-finished honeycomb; S6, the semi-finished honeycomb is impregnated and pre-cured in resin, the resin being phenolic resin, the pre-curing temperature being 120℃~150℃, and the time being 0.5h~2h; S7, Repeat S6 until the honeycomb density reaches the preset target density, thus obtaining the metamaterial honeycomb, where the target density is 30 kg / m³. 3 ~150kg / m 3 .

2. The preparation method according to claim 1, characterized in that, In step S2, the mixing ratio of the node adhesive and ethyl acetate and the viscosity of the mixed adhesive solution are adjusted. After setting the number of core strips, the length of the paper cut, and the coating rate, the electromagnetically modified aramid paper is coated with adhesive.

3. The preparation method according to claim 1, characterized in that, In step S4, the pressing is carried out at a temperature of 150℃-250℃ and a pressure of 0.4Mpa-1Mpa for 3-6 hours.

4. The preparation method according to claim 1, characterized in that, In step S5, the aramid paper block after pressing is stretched to the preset theoretical length using a honeycomb stretching machine at a stretching rate of 80-120 mm / min.

5. The preparation method according to claim 4, characterized in that, In step S5, after stretching, the product is placed in a shaping oven and cured at 200-300℃ for 2-3 hours to set its shape.

6. The preparation method according to claim 1, characterized in that, In step S1, the honeycomb cells of the aramid paper are hexagonal or rectangular.

7. A metamaterial honeycomb, characterized in that, Prepared by the preparation method according to any one of claims 1 to 6.

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