High-temperature-resistant flexible metamaterial and preparation method and application thereof

Abstract

The invention belongs to the technical field of wave-absorbing materials, and particularly relates to a high-temperature-resistant flexible metamaterial and a preparation method and application thereof.The high-temperature-resistant flexible metamaterial takes quartz fiber cloth as a base material, an active carbon source and a protective atmosphere are added to be deposited on the surface of the quartz fiber cloth, and graphene / quartz fiber cloth is obtained; the graphene / quartz fiber cloth is immersed in a nickel salt solution with a certain concentration for deposition to obtain nano nickel / graphene / quartz fiber cloth, carbon nanotube / nano nickel / graphene / quartz fiber cloth is obtained through high-temperature vapor deposition, and finally, conductive patterns are processed on the nano nickel / graphene / quartz fiber cloth through laser irradiation. And finally obtaining the carbon nano tube / nano nickel / graphene / quartz fiber cloth metamaterial. According to the high-temperature-resistant flexible metamaterial, the graphene layer, the nickel nanoparticles and the carbon nanotubes are sequentially generated on the surface of the quartz fiber cloth from inside to outside to form a multi-layer structure, so that the high-temperature-resistant flexible metamaterial has excellent electromagnetic broadband absorption capacity and excellent temperature resistance.

Description

Technical Field

[0001] This invention belongs to the field of microwave absorbing materials technology, specifically, it relates to a high-temperature resistant flexible metamaterial, its preparation method and application. Background Technology

[0002] In the continuous development of materials science, the emergence of metamaterials marks a significant breakthrough in the field of electromagnetic functional materials research. Metamaterials are a class of composite materials with special structures designed and constructed artificially. At the microscopic scale, they can exhibit unique electromagnetic properties not found in conventional materials in nature, such as negative refractive index, electromagnetic band gap, and electromagnetic stealth. Therefore, they have wide application value in fields such as electromagnetic wave absorption, stealth, and anti-interference.

[0003] In recent years, with the rapid development of flexible electronics technology, flexible metamaterials, as an important branch of the metamaterials family, have received widespread attention. Flexible metamaterials not only inherit the excellent electromagnetic properties of traditional rigid metamaterials, but also possess good flexibility, foldability, and good processing adaptability. They can be attached to complex curved surfaces and non-flat structural surfaces, expanding their application range in high-tech fields such as aerospace, wearable electronic devices, and electromagnetic shielding.

[0004] Current methods for fabricating flexible metamaterials primarily rely on conductive silver paste printing technology. The basic principle is as follows: a metamaterial fabric with a certain degree of flexibility and foldability is selected as the substrate. This fabric can be made of organic polymer fibers (such as polyimide fibers, polyester fibers, etc.) or composites with other functional fibers. During the preparation of the flexible organic substrate, liquid resin materials (such as epoxy resin, phenolic resin, etc.) are typically injected into the fabric to fill the fiber gaps and enhance the inter-fiber bonding force, thereby improving the overall mechanical strength and dimensional stability. These resin systems usually contain a high proportion of organic solvents (such as ethanol, acetone, toluene, dimethylformamide, etc.) to reduce resin viscosity and improve permeability. Subsequently, the substrate undergoes surface treatment (such as plasma treatment, chemical roughening) to enhance the adhesion of the conductive silver paste to the surface. Then, based on the required periodic microstructures of the flexible metamaterial (such as electromagnetic bandgap structures, resonant ring arrays, fish-scale patterns, etc.), a CAD design is performed, and the designed pattern is transferred to a screen printing plate. Silver paste is typically composed of high-purity silver powder (micron or nanometer scale) as a conductive filler, organic binder as a film-forming carrier, and solvent as a diluent and flow modifier. The silver paste is uniformly pressed into the opening of the screen using a doctor blade, allowing it to deposit onto a designated area on the substrate surface to form a pattern. The printed conductive pattern is then combined with the flexible organic substrate to form a preliminary flexible metamaterial.

[0005] However, these flexible metamaterials have the following drawbacks:

[0006] 1. Poor temperature resistance: Organic substrate materials are prone to softening or even melting at high temperatures, and the organic binders in conductive silver paste are easily decomposed at high temperatures. As a result, the overall temperature resistance of this type of metamaterial is generally no more than 350℃, which is difficult to meet the requirements for stable operation in high-temperature environments. There are application limitations in aerospace, military and radar stealth, industrial high-temperature environments, high-temperature electronics and flexible sensors, etc. For example, it cannot be used as an electromagnetic shielding material around aircraft engines, where the temperature inside the engine compartment and near the jet nozzle can reach 400-600℃, and the organic substrate is prone to softening and failure; it cannot be used as a stealth metamaterial for the outer shell of high-speed aircraft, because aerodynamic heating during supersonic flight will cause the surface temperature of the fuselage to rise sharply (above 400℃ is very common); it cannot be used as an electromagnetic shielding material for metallurgical and electric furnace monitoring equipment, because the furnace mouth and furnace wall are in a high-temperature radiation environment (400-800℃) all year round.

[0007] 2. Poor resistance to organic solvents: In the preparation of flexible organic substrates, liquid resin materials are injected or coated onto prefabricated metamaterial fabrics. These resin systems contain a high proportion of organic solvents (such as ethanol, acetone, toluene, dimethylformamide, etc.). However, these organic solvent molecules have strong polarity or solubility, and can chemically swell, plasticize, or even partially dissolve the flexible organic substrate (such as polyimide, polyester, etc.), leading to increased surface roughness, microcrack formation, and decreased mechanical properties. Simultaneously, the solvents also dissolve and migrate the organic binders in the conductive silver paste layer, easily causing decreased adhesion, localized peeling, and degradation of conductivity. Under these combined effects, flexible metamaterials often exhibit structural instability, decreased electromagnetic properties, and shortened service life after resin treatment or prolonged exposure to organic solvent environments.

[0008] Based on the above problems, there is currently a lack of flexible metamaterials that combine high-temperature stability and resistance to organic solvent corrosion. Therefore, there is an urgent need to develop a novel flexible metamaterial based on an inorganic substrate, possessing good flexibility and conductivity, capable of withstanding high-temperature environments, and unaffected by organic solvent corrosion, in order to overcome the bottlenecks in existing technologies. Summary of the Invention

[0009] To address the above problems, this invention provides a method for preparing a high-temperature resistant flexible metamaterial, the method comprising the following steps:

[0010] Step 1: Quartz fibers are arranged in a tube furnace. Under vacuum conditions and at a predetermined temperature, an activated carbon source and a protective atmosphere are introduced to perform surface treatment on the quartz fiber cloth to form a graphene layer on its surface, thereby obtaining graphene / quartz fiber cloth.

[0011] Step 2: Immerse the graphene / quartz fiber cloth and the nickel sheet in a nickel salt electrolyte with a concentration of 0.5-1 mol / L, respectively. Connect the graphene / quartz fiber cloth to the negative terminal of a DC power supply and the nickel sheet to the positive terminal of a DC power supply. Perform electrodeposition under a set voltage condition to deposit discontinuously distributed nanoscale nickel particles on the surface of the graphene / quartz fiber cloth, thereby obtaining nano-nickel / graphene / quartz fiber cloth.

[0012] Step 3: Arrange the nano-nickel / graphene / quartz fiber in a tube furnace, and introduce an activated carbon source and protective atmosphere under vacuum and set pressure conditions. Utilize the catalytic effect of the nickel nanoparticles to catalytically grow a carbon nanotube array on its surface to obtain a carbon nanotube / nano-nickel / graphene / quartz fiber cloth.

[0013] Step 4: The carbon nanotube / nano nickel / graphene / quartz fiber cloth is patterned by laser of a predetermined wavelength to form a conductive pattern on its surface, and finally a carbon nanotube / nano nickel / graphene / quartz fiber cloth metamaterial with conductive pattern is obtained.

[0014] In a preferred embodiment, further, in step 1, the graphene / quartz fiber cloth preparation process includes: placing the quartz fiber cloth roll into a tubular atmosphere furnace, evacuating the tubular atmosphere furnace, heating the furnace body to a predetermined temperature, adding an activated carbon source and a protective atmosphere through the gas inlet of the tubular atmosphere furnace, maintaining the temperature for a predetermined time, shutting off the carbon source input and the protective gas, and cooling to room temperature while maintaining a vacuum state to obtain the graphene / quartz fiber cloth roll.

[0015] In a preferred embodiment, step 2 further includes the following steps for preparing the nano-nickel / graphene / quartz fiber cloth: cutting the prepared graphene / quartz fiber cloth roll into N×N square cloth blocks, placing them in a nickel salt solution of a predetermined concentration, using the graphene / quartz fiber cloth as the negative electrode and the nickel sheet as the positive electrode, maintaining a predetermined distance between the nickel sheet and the graphene / quartz fiber cloth, applying a voltage between the two electrodes for a predetermined holding time, depositing a layer of discontinuous nickel nanoparticles on the surface of the graphene / quartz fiber cloth, removing it from the nickel salt solution, rinsing it multiple times with pure water, and obtaining the nano-nickel / graphene / quartz fiber cloth.

[0016] In a preferred embodiment, further, in step 2, the distance between the nickel sheet and the graphene / quartz fiber cloth is 20-30 cm, the voltage applied between the two electrodes is 1-2 V, and the holding time is 4-5 min.

[0017] In a preferred embodiment, further, in step 3, the preparation process of carbon nanotube / nano nickel / graphene / quartz fiber cloth includes: placing the nano nickel / graphene / quartz fiber cloth into a tube furnace; under the catalytic action of nickel nanoparticles, using chemical vapor deposition technology to grow a carbon nanotube array on the surface of the nano nickel / graphene / quartz fiber cloth; evacuating the tube furnace and heating the furnace body to a predetermined temperature; introducing an activated carbon source and a protective atmosphere from the furnace inlet; maintaining the temperature for a certain period of time while the carbon source is in the inlet state; then turning off the carbon source input and the protective gas; maintaining the vacuum state and cooling to room temperature to obtain the carbon nanotube / nano nickel / graphene / quartz fiber cloth.

[0018] In a preferred implementation, further, in steps 1 and 3: the activated carbon source includes, but is not limited to, one of carbon-containing gas, carbon-containing liquid, and carbon-containing solid; the protective atmosphere includes, but is not limited to, one or more of gases such as argon, nitrogen, hydrogen, and helium.

[0019] In a preferred implementation, further, in steps 1 and 3, the tubular atmosphere furnace is evacuated to -Pa and held for 1-2 hours; in step 1, the predetermined temperature for heating the furnace body of the tubular atmosphere furnace is 400-1200℃, and in step 3, the predetermined temperature for heating the furnace body of the tubular atmosphere furnace is 800-1200℃.

[0020] In a preferred implementation, further, in step 4, the preparation process of the carbon nanotube / nano nickel / graphene / quartz fiber cloth metamaterial includes: inputting the designed metamaterial pattern into the control computer of the laser engraving machine; placing the carbon nanotube / nano nickel / graphene / quartz fiber cloth flat on the operating table of the laser engraving machine; adjusting the appropriate laser wavelength and power so that the laser irradiation can only remove the carbon components on the surface of the carbon nanotube / nano nickel / graphene / quartz fiber cloth; and forming a conductive pattern on the carbon components remaining on the surface of the carbon nanotube / nano nickel / graphene / quartz fiber cloth by laser irradiation, thereby obtaining the carbon nanotube / nano nickel / graphene / quartz fiber cloth metamaterial.

[0021] On the other hand, the present invention provides a high-temperature resistant flexible metamaterial, the high-temperature resistant flexible metamaterial comprising a quartz fiber cloth substrate, the surface of the quartz fiber cloth substrate having a multi-level structure, the multi-level structure being, from the inside out, a graphene layer, nickel nanoparticles and carbon nanotubes.

[0022] The high-temperature resistant flexible metamaterial is prepared using any one of the above-described methods for preparing high-temperature resistant flexible metamaterials.

[0023] On the other hand, the present invention provides an application of the high-temperature resistant flexible metamaterial, wherein the high-temperature resistant flexible metamaterial is used as a microwave absorbing material; the high-temperature resistant flexible metamaterial has a temperature resistance of 600°C in an aerobic environment and a temperature resistance of 1000°C in an anaerobic environment.

[0024] The beneficial effects of this invention are:

[0025] First, the present invention provides a method for preparing a high-temperature resistant flexible metamaterial. Through steps 1-4, a multi-scale, fully inorganic conductive framework of "quartz fiber cloth / graphene / Ni / CNT" is constructed, addressing the shortcomings of temperature resistance and solvent resistance at the source while maintaining flexibility. The preparation process does not introduce organic solvents such as ethanol, acetone, toluene, or dimethylformamide. Step 1 of this application uses inorganic quartz fiber cloth to replace the organic thin film in the prior art, achieving a bulk temperature resistance far exceeding 350℃, and the surface is coated with graphene (sp... 2 Carbon also possesses excellent thermal stability and antioxidant capacity, making it much more stable than existing silver paste organic binders. Graphene provides a stable conductive transition layer, overcoming the shortcoming of existing technologies where silver paste-organic binder systems are easily decomposed at high temperatures. Quartz is an inorganic oxide, and graphene has strong chemical inertness, serving as a solvent barrier / inert interface layer. Step 2 uses nano-nickel particles as catalytic sites to form a strong interface with graphene / quartz. Unlike existing conductive silver paste printing technologies, the subsequent structure does not rely on "organic binders" for maintenance during thermal cycling. Nickel has a melting point of approximately 1455℃, exhibiting high thermal stability and adhesion. Furthermore, the conductive layer differs from existing technologies; it is not a coating of "silver powder + organic binder" but rather an in-situ grown carbon nanotube array and a Ni / graphene interface network. It contains no binders that can be dissolved or migrated by solvents, thus avoiding the root cause of "decreased adhesion, peeling, and conductivity attenuation" in the conductive layer. Through step 3, carbon nanotubes grow directly on Ni sites, forming a completely inorganic, binder-free, multi-scale conductive framework with graphene / quartz. CNT / graphene exhibits a temperature resistance limit far exceeding that of organic thin film systems in inert or weak oxygen environments. Quartz can withstand more severe thermal radiation, improving temperature resistance. The carbon nanotube array forms chemical bonds on the surface of fabric fibers, making it difficult to be destroyed by solvent immersion. Step 4 uses dry laser direct patterning, eliminating the need for solvent processes such as photoresist, development, and stripping, reducing the chance of the conductive structure being eroded by solvents or contaminated at the interface during the manufacturing process. This application fundamentally avoids the two major failure paths of the "organic substrate + silver paste binder" system in high-temperature and organic solvent environments by inorganicating the material system and in-situ growth / dry patterning of the conductive layer. It can provide high-temperature stable, solvent-resistant, and bendable flexible metamaterial solutions for aerospace, military stealth, metallurgical furnaces, high-temperature electronics / sensing and other scenarios, effectively overcoming the technical bottlenecks of poor temperature resistance and weak resistance to organic solvents in traditional flexible metamaterials.

[0026] Secondly, in the preferred implementation, step 1 of the present invention involves high-temperature carbon source deposition treatment of quartz fiber cloth in a tubular atmosphere furnace, achieving uniform growth of graphene on the surface of the fiber cloth under a protective atmosphere and vacuum environment. This effectively improves the bonding strength between graphene and quartz fiber and the film quality. This method has strong process controllability and is conducive to obtaining graphene / quartz fiber composite materials with complete structure, uniform distribution and excellent conductivity.

[0027] Third, in the preferred implementation, step 2 of the present invention achieves a high-temperature stable, binder-free catalytic and anchoring interface by precisely controlling the entire process and key parameters of "rolling-cutting-electrodeposition-cleaning". This involves constructing uniformly distributed, discontinuously distributed nano-nickel particles in situ on the surface of graphene / quartz fiber. First, the graphene / quartz fiber cloth is rolled and cut into N×N cubes, which facilitates the uniform distribution of the electric field and ion mass transfer within the plane, reducing edge thickening and current concentration. Using these cubes and nickel sheets as cathodes / anodes respectively, with a 20-30cm electrode spacing, ensures sufficient electric field strength while suppressing local hot spots and dendrite formation, thus improving the consistency of large-area deposition. A nickel salt solution concentration of 0.5-1 mol / L provides suitable Ni... 2+ Flux is controlled to avoid excessively high concentrations leading to rapid and continuous nickel film formation, or excessively low concentrations resulting in insufficient nucleation. Applying a voltage of 1-2V and holding it for 4-5 minutes ensures that, in the early stages of electrodeposition, the cathode overpotential is adjusted to a suitable range, causing the rate of new nucleus formation to far exceed the growth rate of existing nuclei. This results in numerous small dots appearing on the substrate surface first, rather than a few large particles / continuous films forming initially. This produces nanoscale "island-like" particles with high density, small size, uniform distribution, and no interconnectedness, rather than a dense metal layer. This maximizes the subsequent nucleation activity of carbon nanotubes. The density of electrodeposition sites is high, while avoiding the rigidity and thermal mismatch problems caused by continuous metal layers. After electrodeposition, the residual salt ions and adsorbed impurities are removed by rinsing with pure water multiple times, which reduces the interference on the conductivity of graphene and subsequent catalytic growth (step 3). The resulting nano-nickel / graphene / quartz fiber cloth has both high specific surface area catalytic activity and strong interface anchoring effect. It can achieve a high-density, strong adhesion, and low-defect three-dimensional conductive framework when growing carbon nanotubes in situ. This improves the structural stability and electromagnetic performance consistency of the material in high temperature and organic solvent environments, while maintaining the flexibility and bending durability of the fabric.

[0028] Fourth, in the preferred implementation, step 3 of the present invention achieves the synergistic integration of multiple nanomaterials by growing a carbon nanotube array on the surface of nano-nickel / graphene / quartz fiber cloth, thereby improving the conductivity, thermal stability and mechanical strength of the material. By utilizing the catalytic effect of nickel nanoparticles and chemical vapor deposition technology, the arrangement and growth quality of carbon nanotubes can be effectively controlled, thus forming a composite material with high specific surface area, excellent interfacial bonding performance and good structural integrity, providing excellent performance assurance for subsequent applications such as electrothermal, energy storage or structural reinforcement.

[0029] Fifth, in the preferred implementation, the present invention, by employing a combination of activated carbon source and protective atmosphere in steps 1 and 3, not only effectively prevents the oxidation of materials under high-temperature conditions but also promotes the reduction of reactants and the removal of impurities, thereby improving the purity and stability of the product. The activated carbon source covers three types of carbon-containing materials: gas, liquid, and solid. This allows the carbon precursor to be used both as a vapor-phase deposition agent to achieve a uniform and dense coating between quartz fiber monofilaments and fiber bundles, and to rely on liquid capillary penetration or localized carbon supply from solid precursors to enhance the continuity and thickness of the coating. Controlled atmosphere; a protective atmosphere (Ar, N2, H2, He, etc., alone or in combination) provides an inert / reducing environment: Ar and N2 inhibit disordered carbon and oxidation side reactions, H2 can reduce the Ni surface oxide layer in situ and activate catalytic sites, and He helps to homogenize heat and mass transfer, together reducing the defect density of graphene and carbon nanotubes (CNTs), improving crystallinity and interfacial bonding; vacuuming (-Pa) and holding at a temperature for 1-2 hours in a tube furnace can reduce oxygen / water residue and side reaction rates, promote the diffusion of precursors into the fiber bundle and the removal of by-products. This process yields highly uniform, low-porosity carbon layers / arrays. Regarding temperature, step 1 is set at 400-1200℃, allowing for controllable growth of multilayer graphene on the quartz fiber surface from nucleation to graphitization: lower temperatures facilitate substrate protection and stress control, while higher temperatures enhance the number of layers, crystallinity, and adhesion. Step 3 is increased to 800-1200℃ to match the catalytic activity of Ni nanoparticles, promoting rapid and ordered epitaxy and vertical array formation of CNTs, balancing diameter, length, and density, and avoiding the negative effects of excessively low temperatures on CNT formation. Insufficient or excessive T nucleation leads to coarsening of Ni particles and imbalance in array density. The above parameter combination enables in-situ construction and fine control of a multi-scale all-inorganic conductive network of quartz / graphene / Ni / CNT. Without introducing organic binders and solvent etching steps, it improves the high-temperature stability and resistance to organic solvents of the conductive layer, reduces the risk of detachment / migration under thermal cycling and solvent immersion, and finally obtains a flexible metamaterial whose sheet resistance, layer thickness, array orientation and electromagnetic response can be engineered and is suitable for harsh environments (high temperature and solvent exposure).

[0030] Sixth, in the preferred implementation, step 4 of the present invention achieves efficient construction of conductive patterns by precisely controlling the surface carbon composition of carbon nanotubes / nano nickel / graphene / quartz fiber cloth with laser, thus preparing metamaterial structures with excellent electrical conductivity and pattern controllability. This method has the advantages of being non-contact, programmable, and having high spatial resolution, which improves the functional integration and processing flexibility of materials and provides a reliable technical foundation for applications in fields such as flexible electronic devices and electromagnetic control materials.

[0031] Seventh, the high-temperature resistant flexible metamaterial of the present invention uses quartz fiber cloth as the substrate, which has the characteristics of being lightweight, having good temperature resistance, high tensile strength and length stability. By generating a multi-level structure of graphene layer, nickel nanoparticles and carbon nanotubes sequentially from the inside to the outside on the surface of quartz fiber cloth, the high-temperature resistant flexible metamaterial has excellent electromagnetic broadband absorption capability and excellent temperature resistance. It can withstand temperatures up to 600℃ in an oxygen-rich environment and up to 1000℃ in an oxygen-free environment. Since graphene and carbon fiber are conductive, the patterns formed on the surface of carbon nanotubes / nano-nickel / graphene / quartz fiber cloth by laser irradiation are conductive. Based on the controllability of laser irradiation, the high-temperature resistant flexible metamaterial can obtain a variety of conductive patterns. Attached Figure Description

[0032] Figure 1 This is a scanning electron microscope (SEM) microstructure image of the high-temperature resistant flexible metamaterial of the present invention;

[0033] Figure 2 This is a schematic diagram of the preparation method involved in step 1 of the present invention;

[0034] Figure 3 This is a schematic diagram of the preparation method involved in step 2 of the present invention;

[0035] Figure 4 This is a scanning electron microscope image of the nano-nickel / graphene / quartz fiber cloth composite material prepared in step 2 of the present invention.

[0036] Figure 5 This is a schematic diagram of the preparation of carbon nanotube / nano nickel / graphene / quartz fiber cloth metamaterial by laser irradiation in step 4 of the present invention.

[0037] Figure 6 This is a schematic diagram of a carbon nanotube / nano nickel / graphene / quartz fiber cloth metamaterial pattern in step 4 of the present invention.

[0038] Figure 7 This is a physical image of the high-temperature resistant flexible metamaterial prepared in Example 1 of the present invention;

[0039] Figure 8 This is a physical image of the high-temperature resistant flexible metamaterial prepared in Example 2 of the present invention;

[0040] Figure 9 Raman spectra of the sample surfaces obtained in Examples 1 and 2 of this invention;

[0041] Figure 10 This is a scanning electron microscope (SEM) image of the sample obtained in step 2 of Example 3 of the present invention under the condition of using a high concentration of nickel chloride solution;

[0042] Figure 11 This is a scanning electron microscope (SEM) image of the carbon nanotube array prepared in step 3 of embodiment 4 of the present invention under conditions of excessively high temperature, excessively long holding time and insufficient vacuum.

[0043] Figure 12 This is a graph showing the comparative test results of the high-temperature resistance of the material of the present invention in Example 5 of the present invention and the flexible metamaterial prepared by the conductive silver paste printing method in the prior art;

[0044] Figure 13 This is a schematic diagram of the pattern structure of several different carbon nanotube / nano nickel / graphene / quartz fiber cloth metamaterials in Embodiment 6 of the present invention;

[0045] Figure 14 This is a physical image of the heat-resistant composite material shell made of high-temperature resistant flexible metamaterials in Embodiment 6 of the present invention;

[0046] Figure 15 This is a contact angle test diagram of the graphene fiber surface in Example 7 of the present invention;

[0047] Figure 16 This is a scanning electron microscope (SEM) image of the graphene fiber surface after chemical nickel plating in Example 7 of the present invention.

[0048] Among them, 1-carbon source; 2-tube atmosphere furnace; 20-air inlet end; 21-air outlet end; 3-quartz fiber cloth roll; 4-vacuum pump; 5-nickel salt solution; 6-negative electrode; 7-positive electrode; 8-graphene / quartz fiber cloth; 9-nickel sheet; 10-nano nickel / graphene / quartz fiber cloth. Detailed Implementation

[0049] To enable those skilled in the art to better understand the technical solutions of this application, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0050] The directional terms such as above, below, left, right, front, and back used in this application are based on the positional relationships shown in the attached drawings. Different attached drawings may result in different positional relationships, therefore they should not be interpreted as limitations on the scope of protection.

[0051] In this application, the terms "installation," "connection," "interlocking," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, an integral connection, a mechanical connection, an electrical connection, or a connection that allows communication between components. They can also refer to a direct connection or an indirect connection through an intermediate medium. They can refer to the internal connection of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0052] This invention discloses a method for preparing a high-temperature resistant flexible metamaterial. Using quartz fiber cloth as a substrate, an activated carbon source is first introduced into a protective atmosphere, and a graphene coating is formed by deposition to obtain a graphene / quartz fiber cloth. Subsequently, it is immersed in a nickel salt solution of a specific concentration, and nano-nickel particles are formed through reduction deposition to obtain nano-nickel / graphene / quartz fiber cloth. Then, carbon nanotubes are grown on its surface using a high-temperature vapor deposition process to obtain a carbon nanotube / nano-nickel / graphene / quartz fiber cloth composite material. Finally, its surface is patterned using laser irradiation technology to construct a metamaterial with a multi-level structure, whose structure, from the inside out, includes a graphene layer, nano-nickel particles, and a carbon nanotube layer (as shown in the attached specification). Figure 1 (As shown). This metamaterial combines flexibility and high-temperature resistance, withstanding temperatures up to 600°C in an oxygen-rich environment and up to 1000°C in an oxygen-free environment, making it suitable for complex high-temperature applications.

[0053] This preparation method uses quartz fiber cloth as a substrate. An activated carbon source and a protective atmosphere are added to deposit graphene / quartz fiber cloth on its surface. The graphene / quartz fiber cloth is then immersed in a nickel salt solution of a certain concentration to deposit nano-nickel / graphene / quartz fiber cloth. High-temperature vapor deposition is then used to obtain carbon nanotube / nano-nickel / graphene / quartz fiber cloth. Finally, patterns are processed on the nano-nickel / graphene / quartz fiber cloth using laser irradiation to obtain a carbon nanotube / nano-nickel / graphene / quartz fiber cloth metamaterial. The surface of the quartz fiber cloth substrate of this high-temperature resistant flexible metamaterial has a multi-level structure. This multi-level structure, from the inside out, consists of a graphene layer, nickel nanoparticles, and carbon nanotubes (as shown in the attached specification). Figure 1 As shown, this high-temperature resistant flexible metamaterial can withstand temperatures up to 600℃ in an aerobic environment and up to 1000℃ in an anaerobic environment.

[0054] The specific steps are as follows:

[0055] Step 1: Quartz fibers are arranged in a tube furnace. Under vacuum conditions and at a predetermined temperature, an activated carbon source and a protective atmosphere are introduced to perform surface treatment on the quartz fiber cloth to form a graphene layer on its surface, thereby obtaining graphene / quartz fiber cloth.

[0056] The purpose of Step 1 is to endow quartz fibers with excellent electrical and thermal conductivity by in-situ growing a graphene layer on the surface of quartz fibers, thereby expanding their application value in the fields of electronics, thermal management, and functional composite materials. This can enhance the interfacial compatibility and interfacial strength between quartz fibers and subsequent matrix materials. The graphene surface has a large number of π-bond structures, which can be further used for surface functionalization treatments (such as loading nanoparticles, chemical modification, etc.). Furthermore, by utilizing vacuum and atmosphere control, oxidation and side reactions can be avoided, ensuring that the number, thickness, and structure of the graphene layers formed are controllable.

[0057] It should be noted that the π bond structure on the surface of graphene is a form of chemical bond. The π bond structure determines the physical properties of graphene, such as high conductivity, which comes from the free movement of π electrons in the two-dimensional plane. Optical absorption, electromagnetic response, and surface activity are all affected by the π bond structure. Surface functionalization often uses π-π stacking (such as non-covalent interactions between aromatic molecules) to load materials or introduce functional groups.

[0058] As per the instruction manual Figure 2 As shown, the equipment used in step 1 includes a winding structure, a tubular atmosphere furnace 2, a vacuum system, and a gas path control system. The winding structure is used to mount the quartz fiber cloth roll 3 onto its stainless steel support or ceramic roller, ensuring uniform unfolding or winding of the fiber cloth. The winding structure works in conjunction with the tubular atmosphere furnace, with the entire winding structure installed in the central heating zone of the furnace. The stainless steel support or ceramic roller of the winding structure is heat-resistant and corrosion-resistant, and does not affect the uniformity of the atmosphere. The tubular atmosphere furnace uses a single-temperature zone or multi-temperature zone electric heating furnace body with good sealing properties, used to control the heating rate, temperature zone distribution, and isothermal time. A vacuum interface is provided at the tail or side wall of the tubular atmosphere furnace. The vacuum system includes a mechanical pump or molecular pump group, equipped with a vacuum gauge for monitoring. The vacuum pump 4 (mechanical pump / molecular pump) is connected to the outlet 21 (vacuum interface) of the tubular atmosphere furnace 2 via a high-temperature resistant hose. The gas path control system is equipped with a mass flow controller (MFC) and a gas purifier to ensure atmosphere accuracy. The tubular atmosphere furnace provides a sealed reaction space. The vacuum system first extracts air from the furnace to remove impurities. Then, the gas path control system precisely introduces activated carbon source 1 and a protective atmosphere through the inlet 20 of the tubular atmosphere furnace 2. The MFC controls the flow rate and proportion of each gas. Gas inlets and outlets are located at both ends of the furnace body to create a stable airflow. The vacuum system and the gas path control system do not operate simultaneously to prevent system overload. After vacuuming is complete, the extraction port is closed or a bypass valve is used to switch the gas passage.

[0059] Step 1, the specific process for preparing graphene / quartz fiber cloth, includes: using chemical vapor deposition (CVD) technology, uniformly winding or unfolding the quartz fiber cloth onto a ceramic or stainless steel support, and placing it in a tube furnace. The tube furnace system is sealed, and the vacuum pump system is started to evacuate the furnace chamber to 10 °C.5 -10 -5 Pa (i.e., the range from rough vacuum to high vacuum), initially using a rotary vane pump to reduce it to 10 Pa. 2 -10 1 Pa, subsequently pumped to a high vacuum (10 Pa) using molecular pumps, turbopumps, etc. -3 -10 -5 At this vacuum level (Pa), the impurity content of the atmosphere can be reduced, promoting effective decomposition of the carbon source and interface deposition. The heating rate is set to 5-10℃ / min, raising the furnace temperature to 400-1200℃, preferably 800-1100℃. The temperature is maintained stable for approximately 10 minutes before holding to ensure uniform atmosphere exchange. The atmosphere is introduced for the deposition reaction. Activated carbon sources include, but are not limited to, carbon-containing gases, carbon-containing liquids, and carbon-containing solids. Carbon gases include methane (CH4), acetylene (C2H2), benzene vapor, etc.; carbon-containing liquids include ethanol (C2H5OH), phenol, xylene, etc. (introduced via carrier gas evaporation); carbon-containing solids include naphthalene (C... 10 Sublimated carbon sources such as H8 are used. The carbon source flow rate is controlled at 10-100 sccm, while a protective gas is introduced at a flow rate of 100-500 sccm. The protective atmosphere includes, but is not limited to, one or more mixtures of gases such as argon, nitrogen, hydrogen, and helium. The gas flow time of the protective atmosphere is consistent with the holding time. The holding time is 1-2 hours, preferably 90 minutes. At high temperature, the carbon source undergoes thermal decomposition to generate activated carbon seeds or intermediates, and a graphene film is formed on the surface of the quartz fiber through chemical adsorption and catalytic reaction. The carbon source and protective gas flow are stopped, and the tube furnace is allowed to cool naturally to room temperature under vacuum or inert atmosphere. The resulting graphene / quartz fiber roll is then removed.

[0060] Step 2: Immerse the graphene / quartz fiber cloth and the nickel sheet in a nickel salt electrolyte with a concentration of 0.5-1 mol / L, respectively. Connect the graphene / quartz fiber cloth to the negative terminal of a DC power supply and the nickel sheet to the positive terminal of a DC power supply. Perform electrodeposition under a set voltage condition to deposit discontinuously distributed nanoscale nickel particles on the surface of the graphene / quartz fiber cloth, thereby obtaining nano-nickel / graphene / quartz fiber cloth.

[0061] The purpose of step 2 is to load nanoscale nickel particles onto the surface of graphene / quartz fiber cloth to enhance the conductivity, catalytic activity, or electromagnetic shielding performance of the composite material. By forming discontinuously distributed nanoscale nickel particles through electrodeposition, the arrangement, size, and density of metal particles on the fiber surface can be effectively controlled. This enhances the interfacial activity of the material, improves the bonding ability between the graphene layer and subsequent materials, increases the controllability of the microstructure, facilitates subsequent functionalization, optimizes specific surface area and particle distribution, and provides a foundation for energy storage, electrocatalysis, or other functions.

[0062] Step 2 specifically includes:

[0063] Step 2.1: Pretreatment of graphene / quartz fiber cloth.

[0064] The pre-prepared graphene / quartz fiber cloth was cut into several N×N square samples (e.g., 2cm×2cm), ultrasonically cleaned (5 minutes each with ethanol and deionized water) and dried to remove surface impurities.

[0065] Step 2.2: Prepare the electrolyte (nickel salt solution).

[0066] NiSO4·6H2O was used as the main nickel salt, with a concentration controlled at 0.5-1 mol / L. An appropriate amount of boric acid (e.g., 0.2 mol / L) was added as a buffer to stabilize the pH. Optional surfactants (e.g., SDS) could be added to control the nanoparticle size and deposition uniformity. The solution temperature was maintained at 25±2℃, and stirring was performed as needed to ensure homogeneity.

[0067] Step 2.3: Set up the electrodeposition apparatus.

[0068] As per the instruction manual Figure 3 The cut graphene / quartz fiber cloth 8 is held at its exposed edges using conductive clamps or metal wires to prevent obscuring the deposition area. The nickel sheet 9 is fixed to the other end of the electrolytic cell in the same manner. Using a DC power supply, the graphene / quartz fiber cloth 8 is connected to the negative terminal 6 (black clamp), and the nickel sheet 9 is connected to the positive terminal 7 (red clamp). The two electrodes are suspended parallel to each other in the electrolytic cell, ensuring they are completely immersed in the nickel salt solution 5. The distance between the two electrodes is controlled at 20-30 cm, and the electrodes are kept stationary or slowly agitated in the solution to improve deposition uniformity.

[0069] Step 2.4: Electrodeposition process.

[0070] Turn on the power supply and apply a constant DC voltage of 1-2V between the two electrodes, maintaining this voltage for 4-5 minutes (holding time). During this process, nickel ions are reduced to metallic nickel on the surface of the graphene / quartz fiber cloth, depositing as discontinuous nanoparticles in an "island" manner.

[0071] It's important to clarify that "island-like" is a figurative term, referring to the fact that the metal deposited on the material surface (such as nano-nickel) is not a continuous thin film or layered structure, but rather exists as discretely distributed small particles or blocks, much like isolated islands scattered across the sea, rather than forming a continuous metal film. The advantages of island-like deposition are that its granular structure has more active sites than continuous films. Each metal "island" can serve as an independent active center, improving catalytic efficiency. The discrete particle distribution can be used to construct electromagnetic wave absorption / reflection channels, resulting in good electromagnetic properties. Furthermore, the size and density of the islands can be adjusted by controlling voltage, electrolysis time, and concentration, offering strong controllability.

[0072] During the electrochemical deposition process of this application, the following reactions occur at the cathode and anode:

[0073] The anodic reaction is the dissolution process of metallic nickel. The anode is made of a nickel sheet. When a DC power supply is applied, the anode comes into contact with the electrolyte, and nickel atoms lose electrons and enter the electrolyte, becoming migratable Ni atoms. 2+ ion:

[0074] Ni(s)→Ni 2+ (aq)+2e -

[0075] In the formula: Ni(s) represents one solid nickel atom; Ni 2+ (aq) indicates that divalent nickel ions exist in aqueous solution; 2e - This indicates that two electrons were transferred during the reaction. Specifically, a solid nickel atom, Ni(s), loses two electrons (2e) at the anode. - Upon entering the aqueous solution, it transforms into divalent nickel ions (Ni). 2+ (aq).

[0076] This reaction continuously replenishes Ni in the electrolyte. 2+ To maintain a stable ion concentration.

[0077] The cathode reaction is a deposition process where Ni in the solution is deposited on the surface of graphene / quartz fiber cloth. 2+ It gains electrons, is reduced, and deposited as metallic nickel:

[0078] Ni 2+ (aq)+2e - →Ni(s)

[0079] The deposited Ni is formed as nanoparticles on the surface of graphene / quartz fiber cloth. In the initial stage, defect sites or active sites on the graphene sheets and quartz fiber cloth surface first form nickel nucleation sites. During the growth stage, as electrolysis continues, nickel atoms are continuously reduced and accumulate, forming nanoscale nickel particles. Ultimately, due to limitations imposed by voltage, current density, and interfacial energy, the nickel particles are discontinuously distributed on the substrate surface, rather than forming a continuous nickel layer. The resulting nano-nickel / graphene / quartz fiber cloth exhibits enhanced conductivity and catalytic performance from surface nanoparticles, increased specific surface area and interfacial activity from the discontinuous distribution, and good mechanical support and stability provided by the graphene and quartz fiber cloth.

[0080] Step 2.5: Washing and drying.

[0081] After electrodeposition, remove the sample and rinse it 3-5 times with pure water or deionized water to thoroughly remove residual nickel salts on the surface. Finally, place the sample in an oven at 60-80℃ to dry until there is no obvious moisture residue.

[0082] As per the instruction manual Figure 4 The product obtained through steps 2.1-2.5 is a nano-nickel / graphene / quartz fiber cloth composite material with nano-nickel particles loaded on the surface. Its microstructure presents a state of discontinuous nickel particles dotting the graphene substrate, which is beneficial for subsequent heat treatment or functionalization reaction.

[0083] Step 3: Arrange the nano-nickel / graphene / quartz fiber in a tube furnace, and introduce an activated carbon source and protective atmosphere under vacuum and set pressure conditions. Utilize the catalytic effect of nickel nanoparticles to catalytically grow carbon nanotube arrays on their surface to obtain carbon nanotube / nano-nickel / graphene / quartz fiber cloth.

[0084] The purpose of step 3 is to synthesize carbon nanotube arrays in situ on the surface of the composite support structure to construct a carbon nanotube / nickel nanoparticle / graphene / quartz fiber (CNT / Ni / G / SiO2) composite material with a three-dimensional hierarchical structure. This approach can increase the specific surface area and the number of electrochemically active sites, enhancing its application performance in energy storage, electrocatalysis, and other fields; strengthen electron transport channels, with carbon nanotubes acting as a conductive framework to improve the conductivity of the entire system; enhance the mechanical stability of the composite structure, as the carbon nanotubes form a "scaffold-bridge-support" network with graphene and quartz fibers, contributing to structural stability; improve the utilization efficiency of nickel nanoparticles, with nickel acting as a catalyst to participate in carbon source pyrolysis and induce the ordered growth of CNTs; and achieve efficient and controllable synthesis of carbon materials, firmly integrating them with the underlying structure, thus improving the consistency and reproducibility of the overall material performance.

[0085] Step 3 includes:

[0086] Step 3.1: Lay the pre-made nano-nickel / graphene / quartz fiber cloth (Ni / G / SiO2 cloth for short) flat on a high-temperature resistant quartz boat or ceramic carrier in a tube furnace.

[0087] The surface of the nano-nickel / graphene / quartz fiber cloth is spread out as much as possible to avoid stacking, thereby improving the uniform contact efficiency of the carbon source gas. The tubular atmosphere furnace type in this application adopts a dual-zone or single-zone tubular atmosphere furnace (quartz tube inner diameter ≥ 50mm).

[0088] Step 3.2: Use a vacuum pump to evacuate the tubular atmosphere furnace to an initial vacuum state (10). 5 -10 -5 To remove impurity gases, heat the gas to 800-1200℃ at a rate of 5-10℃ / min, and maintain the target temperature for 5-10 minutes before introducing the carbon source to eliminate temperature differences.

[0089] For example, if acetylene (C2H2) is used as the carbon source, the tubular atmosphere furnace will be heated to 600-700℃. If methane (CH4) is used as the carbon source, the tubular atmosphere furnace will be heated to 700-800℃.

[0090] Step 3.3: Introduce the mixed atmosphere according to the preset gas type, ratio and flow rate.

[0091] The activated carbon source includes, but is not limited to, one of carbon-containing gases, liquids, and solids. The protective atmosphere includes, but is not limited to, one or more gases such as argon, nitrogen, hydrogen, and helium. The carbon source gas, such as methane (CH4), acetylene (C2H2), or ethylene (C2H4), has a volume fraction of 5-20% and a recommended flow rate of 10-100 sccm. The protective atmosphere has a volume fraction of 80-95% and a recommended flow rate of 100-500 sccm. The atmosphere ratio is carbon source:protective = 1:4-1:9 to prevent the formation of combustible or explosive mixtures. Additionally, a small amount of hydrogen (H2, approximately 5%) can be selected to prevent metal oxidation and enhance catalytic activity; a recommended flow rate is 5-20 sccm.

[0092] Step 3.4: Keep warm for 1-2 hours. The surface of nickel nanoparticles catalytically decomposes the carbon source gas, and carbon atoms diffuse, deposit, and epitaxially form a carbon nanotube array.

[0093] Step 3.5: After heat preservation is completed, turn off the carbon source input and protective gas in sequence, maintain vacuum and cool to room temperature to obtain carbon nanotube / nano nickel / graphene / quartz fiber cloth.

[0094] Step 3.6: Remove the carbon nanotube / nano nickel / graphene / quartz fiber cloth from the quartz boat in the tube atmosphere furnace. The surface of the carbon nanotube / nano nickel / graphene / quartz fiber cloth shows a black, uniformly distributed array of carbon nanotubes. Wash with diluted acid (such as HCl) to remove excess Ni particles, rinse with deionized water until pH=7, and dry at 60-80℃.

[0095] Step 4: The carbon nanotube / nano nickel / graphene / quartz fiber cloth is patterned by laser of a predetermined wavelength to form a conductive pattern on its surface, and finally a carbon nanotube / nano nickel / graphene / quartz fiber cloth metamaterial with conductive pattern is obtained.

[0096] The purpose of step 4 is to transfer a pre-defined metamaterial pattern onto the surface of a carbon nanotube / nickel nanoparticle / graphene / quartz fiber cloth (hereinafter referred to as "composite fiber cloth") with high precision using a laser patterning irradiation process. This process can accurately remove unwanted carbon-based materials from the surface of the composite fiber cloth without damaging the quartz fibers, retaining only the conductive carbon structure, thereby forming a predetermined conductive pattern and endowing the composite material with the pre-defined electromagnetic response characteristics to meet the functional design requirements of metamaterial devices.

[0097] Specifically, see the instruction manual. Figure 5 As shown, step 4 includes:

[0098] Step 4.1: Use graphic design software to design the micro-nano conductive patterns required for the metamaterial, and input the designed patterns into the laser engraving control software.

[0099] Graphical design software such as CAD is used, along with micro / nano conductive patterns such as periodic structures and resonant rings of specific shapes. The designed patterns are then input into the laser engraving control software in compatible formats (such as DXF, SVG, etc.).

[0100] Step 4.2: Lay the carbon nanotube / nano nickel / graphene / quartz fiber cloth flat on the laser engraving machine operating platform and fix it with vacuum adsorption or clamps to prevent slippage.

[0101] Step 4.3: Based on the absorption spectrum of carbon-based materials in carbon nanotubes / nano nickel / graphene / quartz fiber cloth, set the matching wavelength and power, and simultaneously set the scanning speed and frequency.

[0102] It should be noted that carbon-based materials refer to carbon nanotubes and graphene, excluding nano-nickel (Ni) and quartz fiber. An absorption spectrum is a spectral image that describes the phenomenon where certain wavelengths of light (or other electromagnetic waves) are absorbed and weakened when they pass through a material. The horizontal axis of an absorption spectrum is usually wavelength (nm) or frequency (Hz), and the vertical axis is usually absorbance (or the reciprocal of transmittance) or absorption intensity.

[0103] The preferred wavelengths are 355nm (ultraviolet laser) or 1064nm (near-infrared light) to match the absorption spectrum of carbon-based materials. The laser power should be set within the parameter range that allows for the ablation of carbon components without damaging the quartz fibers (e.g., 0.5-2W, fine-tuned according to material thickness). The scanning speed should be set between 100-300mm / s, and the pulse frequency should be moderate (e.g., 20-50kHz) to prevent over-burning or residue.

[0104] Step 4.4: The laser scans the surface of the carbon nanotube / nano nickel / graphene / quartz fiber cloth according to the control pattern. In the laser-irradiated area, the carbon nanotube / nano nickel / graphene are ablated, oxidized or vaporized and removed due to photothermal effect or photolysis. The quartz fiber remains intact due to its high heat resistance and low absorption. The area not irradiated by the laser still retains the highly conductive carbon nanotube / graphene structure. The retained carbon components form a conductive pattern, thus obtaining the carbon nanotube / nano nickel / graphene / quartz fiber cloth metamaterial.

[0105] Instruction manual attached Figure 6This is an exemplary illustration of a carbon nanotube / nano-nickel / graphene / quartz fiber fabric metamaterial with a specific pattern. The fabric surface shown in the image has a periodic square concentric pattern (also known as an "electromagnetic metastructure unit"). Each pattern unit is etched onto the surface of the carbon-based material using a laser ablation method. The black areas in the pattern retain conductive materials such as carbon nanotubes / graphene, forming electromagnetic response units, while the gray-white areas represent the exposed quartz fiber regions (insulating) after laser removal.

[0106] Example 1

[0107] Based on the above-mentioned method for preparing high-temperature resistant flexible metamaterials, this paper describes the preparation method of high-temperature resistant flexible metamaterials with specific parameters.

[0108] Methane was used as the carbon source at a flow rate of 100 sccm, hydrogen was used as the protective gas at a flow rate of 100 sccm, and the deposition temperature was 1000℃. The quartz fiber roll was placed into the furnace at room temperature. The furnace was closed, the vacuum device was activated, and the pressure was evacuated to 10... -2 At step 1, turn on the heating element and raise the furnace tube temperature to 1000℃ at a rate of 10℃ / min. Turn on the air inlet device and maintain the temperature for 1 hour. Turn off the heating element, carbon source, and hydrogen gas, and maintain a vacuum until cooling to room temperature. After cooling to room temperature, turn off the vacuum device, open the discharge hopper, and remove the graphene / quartz fiber cloth roll. Cut the graphene / quartz fiber cloth roll into 100x100cm cubes. Connect one side to the negative electrode of the voltage source and place it in a 1mol / L nickel nitrate solution. The counter electrode is a 100x100cm nickel sheet, with a distance of 30cm between the nickel sheet and the graphene / quartz fiber cloth roll. Apply a 2V voltage between the two electrodes and maintain this voltage for 5 minutes to deposit nano-nickel particles on the surface of the graphene / quartz fiber cloth roll. Turn off the power, remove the graphene / quartz fiber cloth roll, and rinse it 5 times with pure water to obtain nano-nickel / graphene / quartz fiber cloth. Nano-nickel / graphene / quartz fiber cloth was placed in a CVD furnace. Methane was used as the carbon source at a flow rate of 50 sccm, hydrogen was used as the protective gas at a flow rate of 100 sccm, and the deposition temperature was 800℃. The vacuum device was turned on, and the gas pressure was evacuated to 10. -2At step 1, turn on the heating element and raise the furnace tube temperature to 1000℃ at a rate of 10℃ / min. Turn on the air inlet device and maintain the temperature for 0.5 hours. Then, turn off the heating element, carbon source, and hydrogen, maintaining a vacuum until cooling to room temperature. After cooling to room temperature, turn off the vacuum device and open the discharge chamber to obtain carbon nanotube / nano-nickel / graphene / quartz fiber cloth. Place the carbon nanotube / nano-nickel / graphene / quartz fiber cloth flat on the laser engraving machine's operating table. Adjust the appropriate laser wavelength and power so that the laser irradiation can only remove the carbon components on the surface of the carbon nanotube / nano-nickel / graphene / quartz fiber cloth without damaging the quartz fibers. Input the designed metamaterial pattern into the laser engraving machine's control computer. The carbon nanotube / nano-nickel / graphene / quartz fiber cloth is selectively irradiated by the laser to obtain the carbon nanotube / nano-nickel / graphene / quartz fiber cloth metamaterial.

[0109] As per the instruction manual Figure 7 , Figure 7 The image shown is a physical representation of a carbon-based flexible metamaterial fabric with a periodic electromagnetic response pattern prepared in this embodiment, demonstrating a large-area, uniform, and high-fidelity periodic metamaterial unit array. Each pattern unit has a uniform size and is arranged periodically, facilitating simulation and control. This structure helps to achieve electromagnetic bandgap / shielding / stealth / absorption functions at specific frequency bands.

[0110] Example 2

[0111] High-temperature resistant flexible metamaterials were prepared in the same manner as in Example 1.

[0112] Ethylene was used as the carbon source at a flow rate of 100 sccm, hydrogen was used as the protective gas at a flow rate of 200 sccm, and the deposition temperature was 800℃. The quartz fiber roll was placed into the furnace at room temperature. The furnace was closed, and the vacuum device was activated to evacuate the gas pressure to 10. -2At step 1, turn on the heating element and raise the furnace tube temperature to 800°C at a rate of 5°C / min. Turn on the air inlet device and maintain the temperature for 2 hours. Turn off the heating element, carbon source, and hydrogen gas, and maintain a vacuum until cooling to room temperature. After cooling to room temperature, turn off the vacuum device, open the discharge hopper, and remove the graphene / quartz fiber cloth roll. Cut the graphene / quartz fiber cloth roll into 50x50 cm cubes. Connect one side to the negative electrode of the voltage source and place it in a 0.5 mol / L nickel chloride solution. The counter electrode is a 50x50 cm nickel sheet, with a distance of 20 cm between the nickel sheet and the graphene / quartz fiber cloth roll. Apply a voltage of 1.5 V between the two electrodes and maintain this voltage for 4 minutes to deposit nano-nickel particles on the surface of the graphene / quartz fiber cloth roll. Turn off the power, remove the graphene / quartz fiber cloth roll, and rinse it 5 times with pure water to obtain nano-nickel / graphene / quartz fiber cloth. Nano-nickel / graphene / quartz fiber cloth was placed in a CVD furnace. Propane was used as the carbon source at a flow rate of 20 sccm, hydrogen was used as the protective gas at a flow rate of 80 sccm, and the deposition temperature was 900℃. The vacuum device was turned on, and the gas pressure was evacuated to 10. -1 At step 1, turn on the heating element and raise the furnace tube temperature to 900°C at a rate of 10°C / min. Turn on the air inlet and maintain the temperature for 1 hour. Turn off the heating element, carbon source, and hydrogen, and maintain a vacuum until cooling to room temperature. After cooling to room temperature, turn off the vacuum device and open the discharge chamber to obtain carbon nanotube / nano-nickel / graphene / quartz fiber cloth. Place the carbon nanotube / nano-nickel / graphene / quartz fiber cloth flat on the laser engraving machine's operating table. Adjust the appropriate laser wavelength and power so that the laser irradiation can only remove the carbon components on the surface of the carbon nanotube / nano-nickel / graphene / quartz fiber cloth without damaging the quartz fibers. Input the designed metamaterial pattern into the laser engraving machine's control computer. The carbon nanotube / nano-nickel / graphene / quartz fiber cloth is selectively irradiated by the laser to obtain the carbon nanotube / nano-nickel / graphene / quartz fiber cloth metamaterial.

[0113] Figure 8 The image shows a physical sample of the high-temperature resistant flexible metamaterial prepared according to the parameter method of Example 2. The surface pattern is a neatly arranged "cross + square" structure with obvious twisted and wavy deformation areas, indicating that the material has good flexibility and pattern retention capabilities.

[0114] To evaluate the structural quality of the carbon-based conductive layer in the prepared high-temperature resistant flexible metamaterial, Raman spectroscopy analysis was performed on the surfaces of the samples obtained in Example 1 and Example 2. The results are shown in the appendix to the specification. Figure 9 As shown. From Figure 9 As can be seen, both groups of samples exhibit typical characteristic peaks of carbon-based materials, including the D peak (approximately 1340 cm⁻¹). -1 G peak (approximately 1580cm) -1 ) and 2D peak (approximately 2700 cm⁻¹) -1In the spectrum corresponding to Example 1 (orange curve in the figure), the D peak is relatively weaker than the G peak (lower ID / IG), indicating fewer defects in its surface graphene layer and a more complete lattice structure, resulting in higher graphene quality. In contrast, the D peak intensity of the sample in Example 2 (cyan curve in the figure) is slightly higher, indicating that a certain number of boundary or defect sites were formed during the preparation process, but overall it still maintains good sp. 2 Carbon structure.

[0115] Further measurements of the electrical properties of the two samples revealed the following results: the average sheet resistivity of the high-temperature resistant flexible metamaterial of Example 1 was approximately 120 Ω / sq, with uniform resistance distribution and minimal fluctuations; the average sheet resistivity of the high-temperature resistant flexible metamaterial of Example 2 was approximately 170 Ω / sq, also exhibiting good uniformity. These resistance test results indicate that the material of Example 1, due to its more ordered graphene layer structure, better conductive network connectivity, and lower sheet resistivity, is more suitable for applications requiring high conductivity; Example 2, on the other hand, demonstrates higher flexible deformation stability and is suitable for the design of electromagnetically controlled materials under conditions of large curvature or dynamic loads.

[0116] In summary, through Raman spectroscopy structure evaluation combined with electrical performance testing, it can be confirmed that the metamaterials of both embodiments possess superior conductivity and structural uniformity, proving that the process of the present invention achieves a good balance between flexibility, high temperature resistance, conductivity and process controllability.

[0117] Example 3

[0118] This embodiment uses the same equipment and substrate as Embodiments 1 and 2, but the key process parameters differ from those in Embodiments 1 and 2 to verify the importance of the parameters and observe failure modes. Specifically:

[0119] Step 1 (Construction of carbon layer on quartz fiber surface): Methane as carbon source (100 sccm), hydrogen as protective gas (100 sccm); the tubular atmosphere furnace is evacuated to 10... -2 The furnace is set to a vacuum, heated to 900°C and held for 1 hour before being shut down. After cooling, a quartz fiber cloth with a carbon-coated surface is obtained.

[0120] Step 2 (Electrodeposition of Ni seed): Connect the 2cm×2cm sample of the above material to the negative electrode and place it in a 2mol / L nickel chloride solution; the counter electrode is a nickel sheet with an electrode spacing of 25cm, satisfying the range of 20-30cm; after maintaining a constant voltage of 1.5V for 5min, remove the sample, wash it with water and dry it to obtain the Ni deposition layer.

[0121] Step 3 (CNT growth): Propane is used as the carbon source (50 sccm) and hydrogen (100 sccm) in the CVD furnace; the pressure is reduced to 10... -2Under initial vacuum (Pa), the temperature was raised to 1000℃ and held for 1.5 hours. After cooling, carbon nanotube / nano nickel / graphene / quartz fiber cloth was obtained.

[0122] Step 4 (Laser Patterning): Patterning is performed using the same laser equipment and process as in Example 1.

[0123] Comparison of results and defects (relative to Examples 1 and 2): Ni seed morphology out of control (due to high concentration of nickel chloride solution in step 2): strong hydrogen evolution, dendrite / clustering, localized film formation and "sintered" rough surface; Ni particle size increased significantly and distribution was uneven, making it difficult to obtain high-density and discrete catalytic sites.

[0124] As per the instruction manual Figure 10 The image shows a surface scanning electron microscope (SEM) image of the sample prepared in step 2 using a 2 mol / L high-concentration nickel chloride solution. It can be observed that: the Ni seed surface is rough and exhibits a "sintered" morphology; the substrate surface is covered with uneven protrusions, fused particles, and irregular clusters, indicating that the deposition process was severely interfered with by side reactions; dendrite formation and clustering are evident, with nickel particles spontaneously growing into dendritic or large clusters in some areas, lacking a uniform distribution of nanoscale particles; localized continuous film formation occurs, and in some areas, the Ni deposition has evolved from "island-like particles" to sheet-like or continuous coverage, losing the expected discrete distribution characteristics; cracks and particle growth are visible in the SEM image, indicating that the deposited layer was subjected to stress concentration and uneven growth under strong hydrogen evolution.

[0125] This is because the electrolyte concentration is too high, leading to an increase in cathode overpotential, intense hydrogen side reactions, and unstable nickel deposition due to bubble disturbance. 2 The oversaturated supply leads to rapid particle agglomeration, high local current density, and the formation of dendrites, clusters, and continuous films. The attached figure visually demonstrates that under non-optimal conditions (NiCl2 concentration 2 mol / L), the obtained Ni seed layer exhibits significantly increased particle size, severely uneven distribution, and a rough surface morphology with dendritic and clustered characteristics, making it difficult to meet the uniform catalytic site requirements for subsequent CNT growth.

[0126] As can be seen from Examples 1 and 2, when the nickel salt concentration is within the preferred range, the electrodeposited nickel nanoparticles are uniformly dispersed and have controllable particle size. In contrast, Example 3 shows that when the nickel salt concentration exceeds the preferred range, the microstructure and properties of the resulting composite structure are severely degraded, exhibiting a typical failure mode of uncontrolled Ni seed morphology. This result verifies the criticality and necessity of the nickel salt concentration parameter defined in this application.

[0127] Example 4

[0128] This embodiment uses the same equipment and substrate as Embodiments 1 and 2, but the key process parameters differ from those in Embodiments 1 and 2 to verify the importance of the parameters and observe failure modes. Specifically:

[0129] Step 1 (Construction of carbon layer on quartz fiber surface): Methane as carbon source (100 sccm), hydrogen as protective gas (100 sccm); the tubular atmosphere furnace is evacuated to 10... -2 The furnace is set to a vacuum, heated to 900°C and held for 1 hour before being shut down. After cooling, a quartz fiber cloth with a carbon-coated surface is obtained.

[0130] Step 2 (Electrodeposition of Ni seed): Connect a 2cm×2cm sample of the above material to the negative electrode and place it in a 0.5mol / L nickel chloride solution; the counter electrode is a nickel sheet with an electrode spacing of 25cm; after maintaining a constant voltage of 1.5V for 5min, remove the sample, wash it with water and dry it to obtain the Ni deposition layer.

[0131] Step 3 (CNT growth): Propane is used as the carbon source (50 sccm) and hydrogen (100 sccm) in the CVD furnace; the pressure is reduced to 10... -2 Under initial vacuum, the temperature was raised to 1400℃ and held for 2 hours. After cooling, carbon nanotube / nano nickel / graphene / quartz fiber cloth was obtained.

[0132] Step 4 (Laser Patterning): Patterning is performed using the same laser equipment and process as in Example 1.

[0133] Comparison of results and defects (relative to Examples 1 and 2): Disorder / coarsening of CNT array (due to excessively high temperature in step 3): Coarsening and migration of Ni particles lead to increased CNT diameter, poor orientation, tilting and entanglement, and inclusion of graphite / amorphous carbon external deposition; uneven array density and height, with local bridging and clumping.

[0134] As per the instruction manual Figure 11 The image shows a scanning electron microscope (SEM) image of the carbon nanotube array prepared under excessively high temperature conditions in step 3. As can be seen from the image, a large number of carbon nanotubes failed to maintain a vertically ordered arrangement, instead exhibiting tilting, bending, and even tangling. Due to the migration and sintering of Ni catalyst particles at high temperatures, the CNT diameter significantly coarsens. Some outer walls are adhered with graphite or amorphous carbon deposits, and the growth height of CNTs varies significantly in different regions. The array distribution is sparse and discontinuous, and some CNTs intertwine or bridge each other during growth, forming a clump-like structure that disrupts the array's independence.

[0135] This is because excessively high temperatures cause Ni nanoparticles to coarsen and migrate, losing their original nanoscale dispersion state, resulting in a reduction and uneven distribution of catalytic sites. The attached figure visually illustrates that under growth conditions exceeding the optimal parameters, the resulting CNT array exhibits a failure mode of disorder, coarsening, and bridging, making it impossible to achieve a high-density, vertically oriented three-dimensional hierarchical structure.

[0136] As can be seen from Examples 1 and 2, when the CNT growth temperature is within the preferred range, the carbon nanotube array catalyzed on the surface of the nickel nanoparticles exhibits good orientation, a dense and uniform structure. In contrast, Example 3 shows that when the CNT growth temperature process parameters exceed the preferred range, the microstructure and performance of the resulting composite structure are severely degraded, exhibiting a typical failure mode of disordered coarsening of the CNT array. This result verifies the criticality and necessity of the CNT growth temperature parameters defined in this application.

[0137] Example 5

[0138] Based on Example 1, the advantages of the high-temperature resistant flexible metamaterial of the present invention are further illustrated by comparing it with flexible metamaterials prepared by conductive silver paste printing in the prior art. Existing flexible metamaterials prepared by conductive silver paste printing, such as the commercially available Loctite ECI-1011 material, are conductive silver paste products used in the field of flexible electronics.

[0139] Through systematic testing of the conductive material's ability to maintain stable conductivity under various extreme conditions, the reliability of the flexible conductive material of this invention under practical application conditions is comprehensively evaluated. The following is a classification and functional description of each test method:

[0140] 1. The high-temperature resistant flexible metamaterial prepared by the method of the present invention and the flexible metamaterial prepared by commercial conductive silver paste printing are respectively placed in a muffle furnace, and heated from room temperature to the temperature that the sample can withstand under atmospheric conditions, and held at that temperature for 1 minute. The temperature resistance and conductivity of the sample are then tested.

[0141] 2. The high-temperature resistant flexible metamaterial prepared by the method of this invention and the flexible metamaterial prepared by commercial conductive silver paste printing are respectively placed in a vacuum furnace. Under a vacuum or nitrogen atmosphere, the temperature is raised from room temperature to the temperature that the sample can withstand, and held for 1 minute. The temperature resistance and conductivity of the sample are then tested.

[0142] from Figure 12It can be seen that the sheet resistance (Ω / sq) of the high-temperature resistant flexible metamaterial prepared in this invention and the existing silver paste-printed metamaterial changes at different temperatures (20℃ to 1000℃). The test environments include both air and vacuum atmospheres. ▼ represents the existing silver paste-printed metamaterial under air testing environment, ▲ represents the existing silver paste-printed metamaterial under vacuum testing environment, ● represents the high-temperature resistant flexible metamaterial of this invention under air testing environment, and ■ represents the high-temperature resistant flexible metamaterial of this invention under vacuum testing environment. Regardless of whether in air or vacuum environments, the sheet resistance of the high-temperature resistant flexible metamaterial of this invention (● and ■) remains consistently between 40-60 Ω / sq within the range of 20℃-1000℃, with minimal variation. This indicates that the material possesses excellent thermal stability and conductivity structure retention under high-temperature conditions, and the surface carbon nanotube / graphene network did not undergo significant ablation, oxidation, or structural damage.

[0143] Existing silver paste printing materials exhibit a sharp decline in performance at high temperatures. In a vacuum (▲), the resistivity of the silver paste material drops sharply to near 0 Ω / sq after the temperature rises to 400℃, suggesting possible material melting or silver migration. In air (▼), the sheet resistivity of the silver paste sample disappears after 200℃ (curve terminates), indicating severe oxidation and failure of the material. This reflects that silver-based conductive layers are extremely prone to instability in high-temperature environments, making them unsuitable for high-temperature electromagnetic control or thermal protection applications.

[0144] 3. Fold the high-temperature resistant flexible metamaterial prepared by the method of this invention and the flexible metamaterial prepared by commercial conductive silver paste printing in half, and test the conductivity of the samples.

[0145] 4. Polish the high-temperature resistant flexible metamaterial prepared by the method of this invention and the flexible metamaterial prepared by commercial conductive silver paste printing with 1000-grit sandpaper respectively, and test the conductivity of the samples.

[0146] 5. The high-temperature resistant flexible metamaterial prepared by the method of the present invention and the flexible metamaterial prepared by commercial conductive silver paste printing are respectively immersed in an organic solution (e.g., acetone solution), left to stand for more than 30 minutes, and the conductivity of the samples is tested.

[0147] 6. Using a needle plate with a density of 5x5 and a size of 1x1cm, the high-temperature resistant flexible metamaterial prepared by the method of this invention and the flexible metamaterial prepared by commercial conductive silver paste printing are punctured at least 5 times to test the conductivity of the samples.

[0148]

[0149] As can be seen from the table above, the high-temperature resistant flexible metamaterial prepared by this invention maintains stable conductivity without significant degradation or structural delamination after undergoing the aforementioned series of tests, which is superior to existing commercial conductive silver paste materials (such as LoctiteECI-1011). It exhibits higher temperature resistance, bending resistance, abrasion resistance, resistance to organic solvent immersion, and puncture resistance. Its synergistic enhancement of high-temperature resistance, mechanical flexibility, and chemical stability makes it more suitable for applications in harsh conditions such as flexible electronics, smart textiles, and aerospace thermal protection.

[0150] Example 6

[0151] As per the instruction manual Figure 13 Based on step 4 of Example 1, a laser-controlled patterning method is further used to perform local sintering and reduction treatment on the carbon nanotube / nano nickel / graphene composite layer to achieve metamaterial patterned structures with different wave absorption properties and resonant frequencies. Figure 13 Each pattern shown has a periodic structure and each pattern corresponds to a specific reflection loss characteristic, making them suitable for different application environments (such as X-band or Ku-band stealth).

[0152] This invention also provides a high-temperature resistant flexible metamaterial applicable to various fields of microwave absorbing materials. The applications of microwave absorbing materials are very broad, including at least the military, aerospace, communications, geological exploration, automotive manufacturing, and architecture and urban planning fields.

[0153] Taking the heat-resistant composite material shell of a high-speed aircraft as an example, the high-temperature resistant flexible metamaterial of the present invention is integrated into the aircraft structural shell to form a composite component that combines structural load-bearing capacity, thermal protection capacity, and stealth wave absorption capacity, thereby meeting the integrated performance requirements in the hypersonic flight environment.

[0154] A heat-resistant composite material shell was prepared using the high-temperature resistant flexible metamaterial prepared by the method of this invention.

[0155] First, a carbon nanotube / graphene / nano-nickel composite-coated quartz fiber cloth is patterned using laser patterning technology to create a honeycomb-like electromagnetic response pattern on its surface, exhibiting high conductivity, wide electromagnetic absorption bandwidth, good flexibility, and high temperature resistance. Then, high-temperature needle-punching technology (such as high-temperature steel needles or ceramic needle plates) is used to puncture and connect the patterned flexible metamaterial to the quartz fiber fabric at multiple points, achieving mechanical anchoring and preliminary integrated molding of the metamaterial layer and the quartz substrate. The material's "needle-punching toughness" prevents the conductive layer from peeling or being damaged. Further, the pre-fabricated composite sheet is placed in a high-speed aircraft curved shell mold. This material can naturally conform to complex curved surfaces (due to its excellent bending properties). Phenolic resin is injected into the mold cavity using resin transfer molding (RTM) technology. The selected phenolic resin is a heat-resistant, ablation-resistant, and low-outgassing system. The injection process requires no binder assistance. The metamaterial layer has strong solvent resistance and is unaffected by the resin, completing curing under temperature control (e.g., 120-180℃) and vacuum assistance. Finally, after the resin cures, it is demolded to obtain a composite shell component with a surface pattern structure. The conductive pattern layer is completely preserved, and the composite structure has high temperature stability (up to 800-1000℃), structural strength (quartz / phenolic composite), stealth and wave absorption performance (cellular structure electromagnetic response), and can be directly assembled to key parts such as the nose cone, belly plate, and cabin of high-speed aircraft.

[0156] The prepared composite material components are shown in the attached instruction manual. Figure 14 As shown in the figure, the heat-resistant composite material shell prepared using the high-temperature resistant flexible metamaterial described in this invention is an actual product. The left side shows the flat state, and the right side shows the bent state. In the flat state, the surface of the heat-resistant composite material shell exhibits a uniformly distributed honeycomb hexagonal conductive pattern. The pattern is formed by a laser patterning process. The conductive areas in the pattern are carbon nanotube / graphene composite network layers, while the un-irradiated areas show exposed quartz fibers. The overall shell surface is smooth with neat edges, indicating high pattern fidelity and mass production capability. In the bent state, the honeycomb conductive pattern did not peel off, crack, or break under bending conditions, demonstrating that the metamaterial of this invention has excellent mechanical flexibility, strong pattern adhesion, and deformation adaptability, making it suitable for bonding to irregularly shaped structures, such as the nose cone and belly of aircraft, for thermal protection applications.

[0157] Example 7

[0158] To further verify the advantages of the electroplating nickel method described in this invention in loading nano-nickel particles, the commonly used electroless nickel plating (ENP) method was selected as a comparison. Both methods were carried out on the same graphene / quartz fiber cloth substrate, and the resulting materials were "electroplated nickel / graphene / quartz fiber cloth" and "electroplated nickel / graphene / quartz fiber cloth", respectively.

[0159] 1. Method Comparison

[0160] The electroplating method of this invention involves using an external current to drive the directional reduction of nickel ions into metallic nickel particles on the surface of a cathode (graphene / quartz fiber cloth). The deposition rate, particle size, and distribution state during this process can be precisely controlled by parameters such as voltage, current density, electrolyte concentration, and reaction time. It is independent of solution wettability, making it suitable for hydrophobic substrates such as graphene. This results in uniformly distributed, size-controllable nano-nickel particles that form a "discontinuous" island structure, which is beneficial for the uniform nucleation and epitaxial growth of carbon nanotubes.

[0161] In contrast, existing electroless nickel plating methods rely on chemical reducing agents (such as sodium hypophosphite) to drive the reduction and deposition of nickel ions. For conventional hydrophilic metal substrates (such as metal / active surfaces), the deposition process typically tends to form a continuous Ni-P or Ni-B alloy film. However, on hydrophobic carbon-based surfaces such as graphene fibers, due to poor surface wettability (large contact angle), the plating solution is difficult to spread sufficiently and uniformly contact the substrate. This makes it difficult for the deposition process to achieve uniform nucleation across the entire surface, often resulting in areas with blank, uncoated areas, while nucleated areas easily evolve into locally continuous films. As a result, the size and distribution of the coated particles are difficult to control precisely, making it difficult to obtain high-density, discretely distributed nanoscale catalytic particles, which is detrimental to the subsequent uniform nucleation and epitaxial growth of carbon nanotubes.

[0162] As per the instruction manual Figure 15-16 , Figure 15 This is a test diagram of the contact angle of the graphene fiber surface, from... Figure 15 It can be seen that the droplet forms a contact angle of about 136° on the fiber surface, indicating that the surface has significant hydrophobic properties. Figure 16 The image shows a SEM image of the graphene fiber surface after chemical nickel plating. Figure 16 It can be observed that there are large areas of blank areas on the fiber surface where no nickel has been deposited, with only a few scattered particles. This indicates that the nickel layer deposition is discontinuous and has low coverage due to insufficient wettability of the solution during the electroless plating process.

[0163] 2. Comparison of structure and morphology

[0164] This invention employs electroplating nickel on the surface of graphene / quartz fiber. SEM observation shows that the resulting nickel deposition consists of discretely distributed, uniformly distributed nanoparticles with controllable coverage. This method can provide high-density, uniform catalytic sites while maintaining the high specific surface area of ​​graphene fibers.

[0165] When using electroless nickel plating, the graphene fiber surface is highly hydrophobic (contact angle of about 136°), and the plating solution has insufficient wettability, making it difficult to uniformly nucleate on the entire surface. This often results in large blank areas without nickel deposition, and the overall lack of nanoparticle dispersion leads to insufficient effective catalytic sites.

[0166] 3. Performance Comparison

[0167] The electroplated nickel / graphene / quartz fiber cloth of this invention exhibits stable dispersion of nickel particles during chemical vapor deposition, thereby inducing vertical and uniform epitaxial growth of carbon nanotube arrays, resulting in a three-dimensional hierarchical structure with uniform diameter, good orientation, and high density. In contrast, the electroless nickel-plated nickel / graphene / quartz fiber cloth obtained by electroless nickel plating results in sparse carbon nanotubes with large diameter differences due to uneven coating coverage.

[0168] In summary, the electroplating nickel method of the present invention exhibits significant advantages on hydrophobic carbon-based surfaces such as graphene fibers.

[0169] The present invention discloses a high-temperature resistant flexible metamaterial and its preparation method. By sequentially constructing a graphene layer, electrodepositing nickel nanoparticles, growing a carbon nanotube array, and laser patterning on the surface of a quartz fiber cloth, a multi-scale composite structure material with excellent conductivity, thermal stability, and electromagnetic functions is formed. This overcomes the bottleneck of insufficient temperature resistance and solvent resistance of traditional flexible metamaterials and is suitable for the field of flexible electronics and electromagnetic control in extreme environments.

[0170] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics of the solutions is not described in detail here. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the present invention is defined by the appended claims rather than the foregoing description. Therefore, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for preparing a high-temperature resistant flexible metamaterial, the method comprising the following steps: Step 1: Quartz fibers are arranged in a tube furnace. Under vacuum conditions and at a predetermined temperature, an activated carbon source and a protective atmosphere are introduced to perform surface treatment on the quartz fiber cloth to form a graphene layer on its surface, thereby obtaining graphene / quartz fiber cloth. Step 2: Immerse the graphene / quartz fiber cloth and the nickel sheet in a nickel salt electrolyte with a concentration of 0.5-1 mol / L, respectively. Connect the graphene / quartz fiber cloth to the negative terminal of a DC power supply and the nickel sheet to the positive terminal of a DC power supply. Perform electrodeposition under a set voltage condition to deposit discontinuously distributed nanoscale nickel particles on the surface of the graphene / quartz fiber cloth, thereby obtaining nano-nickel / graphene / quartz fiber cloth. Step 3: Arrange the nano-nickel / graphene / quartz fiber in a tube furnace, and introduce an activated carbon source and protective atmosphere under vacuum and set pressure conditions. Utilize the catalytic effect of the nickel nanoparticles to catalytically grow a carbon nanotube array on its surface to obtain a carbon nanotube / nano-nickel / graphene / quartz fiber cloth. Step 4: The carbon nanotube / nano nickel / graphene / quartz fiber cloth is patterned by laser of a predetermined wavelength to form a conductive pattern on its surface, and finally a carbon nanotube / nano nickel / graphene / quartz fiber cloth metamaterial with conductive pattern is obtained.

2. The method for preparing the high-temperature resistant flexible metamaterial according to claim 1, characterized in that, In step 1, the preparation process of graphene / quartz fiber cloth includes: placing the quartz fiber cloth roll into a tubular atmosphere furnace, evacuating the tubular atmosphere furnace, heating the furnace body to a predetermined temperature, adding an activated carbon source and a protective atmosphere through the gas inlet of the tubular atmosphere furnace, maintaining the temperature for a predetermined time, shutting off the carbon source input and protective gas, and cooling to room temperature while maintaining a vacuum state to obtain the graphene / quartz fiber cloth roll.

3. The method for preparing the high-temperature resistant flexible metamaterial according to claim 1, characterized in that, In step 2, the preparation process of nano-nickel / graphene / quartz fiber cloth includes: cutting the prepared graphene / quartz fiber cloth roll into N×N square cloth, placing it in a nickel salt solution of a predetermined concentration, using the graphene / quartz fiber cloth as the negative electrode and the nickel sheet as the positive electrode, maintaining a predetermined distance between the nickel sheet and the graphene / quartz fiber cloth, applying a voltage between the two electrodes for a predetermined holding time, depositing a layer of discontinuous nickel nanoparticles on the surface of the graphene / quartz fiber cloth, removing it from the nickel salt solution and rinsing it multiple times with pure water to obtain nano-nickel / graphene / quartz fiber cloth.

4. The method for preparing the high-temperature resistant flexible metamaterial according to claim 3, characterized in that, In step 2, the distance between the nickel sheet and the graphene / quartz fiber cloth is 20-30cm, the voltage applied between the two electrodes is 1-2V, and the holding time is 4-5min.

5. The method for preparing the high-temperature resistant flexible metamaterial according to claim 1, characterized in that, In step 3, the preparation process of carbon nanotube / nano nickel / graphene / quartz fiber cloth includes: placing the nano nickel / graphene / quartz fiber cloth into a tube furnace; under the catalytic action of nickel nanoparticles, using chemical vapor deposition technology to grow a carbon nanotube array on the surface of the nano nickel / graphene / quartz fiber cloth; evacuating the tube furnace and heating the furnace body to a predetermined temperature; introducing an activated carbon source and a protective atmosphere from the furnace inlet; maintaining the temperature for a certain period of time with the carbon source in place; then turning off the carbon source input and the protective gas; and cooling to room temperature while maintaining a vacuum state to obtain the carbon nanotube / nano nickel / graphene / quartz fiber cloth.

6. The method for preparing the high-temperature resistant flexible metamaterial according to claim 1, characterized in that, In steps 1 and 3: the activated carbon source includes one of carbon gas, carbon-containing liquid, or carbon-containing solid, and the protective atmosphere includes one or more gases such as argon, nitrogen, hydrogen, and helium.

7. The method for preparing the high-temperature resistant flexible metamaterial according to claim 1, characterized in that, In steps 1 and 3, the tubular atmosphere furnace is evacuated to a vacuum level of 10. -1 -10 -5 Pa, the holding time is 1-2h; the predetermined temperature for heating the furnace body in step 1 is 400-1200℃, and the predetermined temperature for heating the furnace body in step 3 is 800-1200℃.

8. The method for preparing the high-temperature resistant flexible metamaterial according to claim 1, characterized in that, In step 4, the preparation process of the carbon nanotube / nano nickel / graphene / quartz fiber cloth metamaterial includes: inputting the designed metamaterial pattern into the control computer of the laser engraving machine; placing the carbon nanotube / nano nickel / graphene / quartz fiber cloth flat on the operating table of the laser engraving machine; adjusting the appropriate laser wavelength and power so that the laser irradiation can only remove the carbon components on the surface of the carbon nanotube / nano nickel / graphene / quartz fiber cloth; and forming a conductive pattern on the carbon components remaining on the surface of the carbon nanotube / nano nickel / graphene / quartz fiber cloth by laser irradiation, thereby obtaining the carbon nanotube / nano nickel / graphene / quartz fiber cloth metamaterial.

9. A high-temperature resistant flexible metamaterial, characterized in that, The high-temperature resistant flexible metamaterial includes a quartz fiber cloth substrate, the surface of which has a multi-level structure, the multi-level structure consisting of a graphene layer, nickel nanoparticles, and carbon nanotubes from the inside out. The high-temperature resistant flexible metamaterial is prepared using the preparation method described in any one of claims 1-8.

10. An application of the high-temperature resistant flexible metamaterial as described in claim 9, characterized in that, The high-temperature resistant flexible metamaterial is used as a microwave absorbing material; the high-temperature resistant flexible metamaterial has a temperature resistance of 600℃ in an aerobic environment and a temperature resistance of 1000℃ in an anaerobic environment.

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