Preparation method of bionic radar infrared compatible stealth metamaterial based on novel high-temperature-resistant matrix

Abstract

The invention relates to a preparation method of a material with high-temperature-resistant electromagnetic infrared stealth performance, in particular to a preparation method of a bionic radar infrared compatible stealth metamaterial based on a novel high-temperature-resistant matrix, which comprises the following steps: firstly, preparing mullite-silicon carbide composite fiber, then mixing tetraethoxysilane as a precursor with water and ethanol to prepare silicon dioxide sol, and then preparing the high-temperature-resistant electromagnetic infrared stealth metamaterial based on the mullite-silicon carbide composite fiber. The mullite-silicon carbide composite fibers are impregnated with the silicon dioxide aerogel, and the silicon dioxide composite aerogel is finally prepared through aging and CO2 supercritical drying. A frequency selective surface array cylinder with a micro-nano structure is designed to realize low absorption and high reflection on infrared rays and high transmission performance on radar electromagnetic waves, graphene-CNT-MXene composite resistance ink is prepared, the composite resistance ink is printed on an aerogel dielectric layer by adopting a silk-screen printing process to prepare a frequency selective surface pattern, and the frequency selective surface array cylinder with a micro-nano structure is prepared. And low reflection and high absorption performance on radar electromagnetic waves are realized. And finally, the radar infrared multispectral stealth metamaterial with high temperature resistance is obtained.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of a material with high-temperature-resistant electromagnetic and infrared stealth performance, in particular to a preparation method of a bionic radar-infrared compatible stealth metamaterial based on a novel high-temperature-resistant matrix. BACKGROUND

[0002] In recent years, various large-scale and strong-killing weapons have appeared on the battlefield. With the improvement of the flight speed of weapons and equipment and the new requirements for the stealth performance of thermal components of aircraft, the weapons and equipment will be subjected to extreme thermal load during service, and the working temperature can reach 800 DEG C or even higher, so that the survivability of the weapons and equipment is seriously threatened. On the other hand, in modern war, the acquisition and anti-acquisition of combat information have become the key factor for winning the war, and the continuous improvement of electromagnetic and infrared stealth performance will enhance the striking power of the weapons and equipment. If the combat target has a certain anti-radar detection and anti-infrared detection capability, the combat platform and personnel can obtain the first opportunity in the war and improve the battlefield survival rate. The conventional single-band stealth material has been difficult to meet the battlefield requirements, and the development of a material with long-term stable service and high-temperature-resistant electromagnetic and infrared stealth performance has become one of the core scientific problems restricting the development of weapons and equipment.

[0003] The radar stealth mechanism is to evade radar detection by reducing the radar scattering interface (RCS) of the incident electromagnetic wave, and the material needs to meet the low reflection and high absorption of electromagnetic waves to realize the radar stealth function. The infrared stealth mechanism is to reduce the thermal radiation characteristics of the target, and the material needs to meet the high reflection and low absorption of infrared to realize the infrared stealth function. Although the existing research has realized the radar and infrared compatible stealth function, the lightweight, toughness strength and wave absorption bandwidth of the material still need to be greatly improved. In recent years, aerogel has been widely studied and has great development potential in the field of aerospace due to its unique nano-porous structure, which can significantly suppress heat conduction, heat convection and heat radiation, thereby realizing high-efficiency heat insulation performance. Therefore, it is a great opportunity and challenge to apply aerogel to the design and manufacture of composite metamaterials to realize the compatibility of the material with high-temperature resistance, electromagnetic and infrared stealth performance. SUMMARY

[0004] In view of the problems of poor high-temperature resistance, low strength and poor electromagnetic infrared stealth synergy performance of the existing stealth materials, the application provides a metamaterial structure design scheme which has good heat insulation effect, large mechanical strength and good radar and infrared stealth synergy performance. The scheme uses reduced graphene as a raw material, and processes a biomimetic frequency selective surface (FSS) structure on a composite aerogel through an oxygen plasma etching process for infrared stealth. Graphene-CNT-MXene composite resistance ink is used to print on the SiO2 composite aerogel medium layer through a screen printing process to prepare a frequency selective surface (FSS), and electromagnetic absorption is realized through a resistive loss type periodic array structure and a dielectric loss type material. Low / high reflection and high / low absorption performance for radar / infrared stealth is realized, and the medium layer SiO2 composite aerogel effectively suppresses the radiation heat conduction under high temperature, thereby achieving significant heat insulation effect.

[0005] The application is implemented by using the following technical scheme: a preparation method of a biomimetic radar and infrared compatible stealth metamaterial based on a novel high-temperature-resistant matrix, comprising the following steps: (1) preparing mullite-silicon carbide composite fibers: using a silicon carbide precursor as an inner layer and a mullite precursor as an outer layer, mullite-silicon carbide composite fibers are prepared through a coaxial electrospinning process; (2) preparing SiO2 sol: using tetraethyl orthosilicate as a precursor, the precursor is mixed with water and ethanol, and SiO2 sol is formed through hydrolysis reaction and polycondensation reaction; (3) preparing SiO2 composite aerogel with mullite-silicon carbide composite fibers as a skeleton: the mullite-silicon carbide composite fibers prepared in step (1) are used as a skeleton, the mullite-silicon carbide composite fibers prepared in step (1) are impregnated with the SiO2 sol prepared in step (2), and finally SiO2 composite aerogel is formed through CO2 supercritical drying and heat treatment; (4) preparing graphene-CNT-MXene composite resistance ink: mixing graphene dispersion liquid and MXene dispersion liquid, and fully stirring through a magnetic stirrer, then sequentially adding methylpyrrolidone, fumed SiO2, carbon nanotube powder CNT and ascorbic acid, fully stirring to obtain the ink; finally, the ink is coated on paper by a spray pen, dried at room temperature, and then baked to remove the paper to obtain the composite resistance ink; (5) preparing a biomimetic micro-nano structure frequency selective surface as an infrared shielding layer: using reduced graphene as a raw material, a biomimetic frequency selective surface structure is processed on the SiO2 composite aerogel through an oxygen plasma etching process to obtain a biomimetic micro-nano structure frequency selective surface; (6) preparing the radar-infrared compatible stealth metamaterial with high-temperature resistance: the composite resistance ink prepared in step (4) is printed on the SiO2 composite aerogel prepared in step (3) by a screen printing process to form a radar-infrared compatible stealth metamaterial with aerogel as a matrix, then a copper sheet is used as the lowermost reflective layer, and a plurality of radar-infrared compatible stealth metamaterials are sequentially stacked on the copper sheet, then the infrared shielding layer prepared in step (5) is stacked on the uppermost radar-infrared compatible stealth metamaterial to complete the preparation of the radar-infrared compatible stealth metamaterial with high-temperature resistance.

[0006] The preparation method of the radar-infrared compatible stealth metamaterial based on the new high-temperature-resistant matrix, in step (6), the composite resistance ink is printed on the SiO2 composite aerogel by a screen printing process to form an open resonant ring structure.

[0007] The preparation method of the radar-infrared compatible stealth metamaterial based on the new high-temperature-resistant matrix, in step (5), the graphene cylinder array is formed on the surface of the SiO2 composite aerogel when the biomimetic frequency selective surface structure is processed on the SiO2 composite aerogel.

[0008] The preparation method of the radar-infrared compatible stealth metamaterial based on the new high-temperature-resistant matrix, the radar-infrared compatible stealth metamaterial with high-temperature resistance is periodically arranged in a unit structure to form an overall structure.

[0009] The preparation method of the radar-infrared compatible stealth metamaterial based on the new high-temperature-resistant matrix material, the mullite fiber-silicon carbide composite fiber is used as the skeleton of the SiO2 composite aerogel, the SiO2 composite aerogel prepared has the characteristics of high-temperature resistance and infrared stealth, the SiO2 composite aerogel is used as the substrate of the frequency selective surface (FSS), the pattern of the super surface is completely prepared, and the uniform regulation and control of the electromagnetic wave resistance type consumption are realized.

[0010] The specific process of preparing the mullite-silicon carbide composite fiber in step (1) of the preparation method of the bionic radar-infrared compatible stealth metamaterial based on a novel high-temperature-resistant matrix is as follows: preparing a core layer spinning solution: polycarbosilane is selected as a SiC precursor, and is mixed according to a proportion of polycarbosilane:N,N-dimethylformamide = 1:9, and a small amount of hydrochloric acid solution is added; preparing a shell layer spinning solution: mullite precursor is prepared by selecting aluminum nitrate nonahydrate and tetraethyl orthosilicate according to a molar ratio of 3:1, and is dissolved in an ethanol solution, 7wt% polyvinylpyrrolidone is added to adjust the viscosity, and a hydrochloric acid solution is added to promote the hydrolysis reaction, and the shell layer spinning solution is stirred to form a uniform shell layer spinning solution; the core layer spinning solution and the shell layer spinning solution are respectively filled into the inner tube and the outer tube of the coaxial needle of the electrostatic spinning, a high-voltage electric field and a syringe pump are started, and the mullite-silicon carbide composite fiber is prepared, the electrostatically spun mullite-silicon carbide composite fiber is sintered at 600 DEG C in air for 1h, the temperature is then increased to 1200 DEG C for sintering for 1h, and then the temperature is increased to 1500 DEG C and kept for 2h; through the above steps, the mullite-silicon carbide composite fiber is prepared.

[0011] The specific process of preparing the SiO2 sol in step (2) of the preparation method of the bionic radar-infrared compatible stealth metamaterial based on a novel high-temperature-resistant matrix is as follows: tetraethyl orthosilicate is used as a precursor, the precursor is mixed with water and ethanol according to a molar ratio of 1:12:16, a 0.1mol / L hydrochloric acid solution is added to adjust PH=2, a hydrolysis reaction is performed, a magnetic stirrer is used to continuously stir at a speed of 200r / min at a temperature of 60 DEG C for 180min, then an NH4OH solution is added to adjust PH=7 to complete the polycondensation reaction, and the SiO2 sol is formed.

[0012] The specific process of preparing the SiO2 composite aerogel with the mullite-silicon carbide composite fiber as the skeleton in step (3) of the preparation method of the bionic radar-infrared compatible stealth metamaterial based on a novel high-temperature-resistant matrix is as follows: the mullite-silicon carbide composite fiber is used as the skeleton, the prepared SiO2 sol is used to impregnate the composite fiber skeleton, the impregnated aerogel is placed in an ethanol solution at 50 DEG C for 8h to age and shape, then the sample is placed in a supercritical CO2 drying device at 50 DEG C and 10MPa for drying treatment, and then the sample is dried at constant temperature for 3h, 2h, 2h and 30min respectively at 40 DEG C, 60 DEG C, 100 DEG C and 120 DEG C, and finally the SiO2 composite aerogel with the mullite-silicon carbide composite fiber as the skeleton is successfully prepared.

[0013] The specific process of step (4) of the preparation method of the radar-infrared compatible stealth metamaterial based on the novel high-temperature-resistant matrix is as follows: the graphene dispersion liquid and the MXene dispersion liquid are mixed, and fully stirred for 30 minutes through a magnetic stirrer; then, the methylpyrrolidone, the fumed SiO2 powder, the carbon nanotube powder and the ascorbic acid are sequentially added and fully stirred for 30 minutes to obtain the ink; finally, the ink is coated on the paper through a spray pen, dried at room temperature, baked for 10 minutes, and then the composite resistance ink is obtained after the paper is removed.

[0014] The specific process of step (5) of the preparation method of the radar-infrared compatible stealth metamaterial based on the novel high-temperature-resistant matrix is as follows: the surface of the prepared SiO2 composite aerogel is modified by oxygen plasma etching and SDS solution combined treatment; then, the reduced graphene coating is uniformly applied; the sample is pre-baked at 100 DEG C for 90s, and then naturally cooled to room temperature; the reduced graphene coating is etched by mask plasma after accurate alignment with a cross standard; then, the sample is reversed baked at 120 DEG C for 180s, and then naturally cooled to room temperature; the AZ5200NJ glue is developed for 80s by using a developing solution, and finally the frequency selective surface of the biomimetic micro-nano structure is obtained after the mask is removed.

[0015] The present application provides a preparation method of a radar-infrared compatible stealth metamaterial based on a novel high-temperature-resistant matrix material, which comprises the following steps: firstly, mullite-silicon carbide composite fibers are prepared by electrospinning technology; then, tetraethyl orthosilicate is used as a precursor, and the precursor is mixed with water and ethanol according to a molar ratio of TEOS:H2O:ETOH=1:12:16; a silica sol is formed through hydrolysis and polycondensation reactions, and then the silica sol is used to impregnate the mullite-silicon carbide composite fibers; finally, the silica composite aerogel is prepared through aging and CO2 supercritical drying. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a schematic diagram of a high-temperature-resistant electromagnetic infrared stealth unit structure based on a periodic structure.

[0017] Figure 2 It is a schematic diagram of a high-temperature-resistant electromagnetic infrared stealth overall structure based on a periodic structure.

[0018] Figure 3 Figure 1 is a diagram of the internal porous structure based on aerogel matrix.

[0019] Figure 4 Figure 2 is a simulation curve of wave absorption performance of the present application.

[0020] Figure 5 Figure 3 is a design optimization diagram based on biomimetic micro-nano frequency selective surface (FSS).

[0021] Figure 6 Figure 4 is a functional effect diagram of the present application with high-temperature-resistant radar and infrared stealth metamaterials. DETAILED DESCRIPTION

[0022] The present application proposes a fiber-reinforced method for preparing aerogel, and uses mullite-silicon carbide composite fibers as the skeleton to provide strong support for the aerogel, so that the composite material has strong strength and obtains aerogel thermal insulation composite material with high thermal insulation effect and good mechanical properties. The fly-eye surface sub-wavelength nano-protrusion structure weakens light reflection (reflectivity < 2%) through gradient refraction effect and scattering. Inspired by the unique anti-reflection mechanism of fly-eye, a periodic nano-cylinder structure is designed to achieve low reflection characteristics in a wide wave band and a large angle. The structure has high transmissivity in the radar frequency band and high reflectivity in the infrared frequency band. The innovation path of combining biological bionics and artificial micro-nano processing provides an important direction for future multi-physical field coupling technology.

[0023] The present application will be further described below in combination with specific implementation examples. Example 1

[0024] First step: preparation of mullite-silicon carbide composite fiber skeleton Preparation of core layer spinning solution: polycarbosilane (PCS) is selected as SiC precursor, mixed according to the ratio of polycarbosilane (PCS): N, N-dimethylformamide (DMF) = 1:9, add a small amount of hydrochloric acid solution; preparation of shell layer spinning solution: aluminum nitrate nine water (Al (NO3) 3·9H2O) and tetraethyl orthosilicate (TEOS) are selected as mullite precursor according to the molar ratio of 3:1, which is dissolved in ethanol solution, 7wt% polyvinylpyrrolidone (PVP) is added to adjust the viscosity, hydrochloric acid solution is added to promote hydrolysis reaction, and stirring for 24h forms a uniform shell layer spinning solution; the core layer spinning solution and the shell layer spinning solution are respectively filled into the inner tube and the outer tube of the coaxial needle of electrospinning, the high voltage electric field and the injection pump are started, and the mullite-silicon carbide composite fiber is prepared, the electrospun mullite-silicon carbide composite fiber is sintered at 600℃ in air for 1h, then the temperature is increased to 1200℃ and sintered for 1h, and then the temperature is increased to 1500℃ and kept for 2h. Through the above steps, mullite-silicon carbide composite fiber is prepared.

[0025] Second step: preparation of SiO2 sol With tetraethyl orthosilicate (TEOS) as precursor, the precursor is mixed with water and ethanol according to the molar ratio of TEOS:H2O:ETOH=1:12:16, 0.1mol / L hydrochloric acid solution is added to adjust PH=2, hydrolysis reaction is carried out, magnetic stirrer is used to stir at the speed of 200r / min at the temperature of 60℃ for 180min, then NH4OH solution is added, PH=7 is adjusted to complete the polycondensation reaction, and SiO2 sol is formed.

[0026] Third step: preparation of SiO2 composite aerogel with mullite-silicon carbide composite fiber as skeleton With mullite-silicon carbide composite fiber as skeleton, the prepared SiO2 sol is used to impregnate the composite fiber skeleton, the impregnated aerogel is placed in 50℃ ethanol solution for 8h to make it aging and shaping, then the sample is placed in supercritical CO2 drying equipment at 50℃ and 10MPa for drying treatment, and then it is dried at constant temperature of 40℃, 60℃, 100℃ and 120℃ for 3h, 2h, 2h and 30min respectively, finally the SiO2 composite aerogel with mullite-silicon carbide composite fiber as skeleton is successfully prepared.

[0027] Fourth step: preparation of graphene-CNT-MXene composite resistance ink The graphene dispersion liquid and the MXene dispersion liquid are mixed and fully stirred by a magnetic stirrer for 30 min, and then methylpyrrolidone (NMP), fumed SiO2 powder, carbon nanotube powder (CNT), and ascorbic acid are sequentially added and fully stirred for 30 min to obtain an ink. Finally, the ink is coated on paper by a spray pen, air-dried at room temperature, and baked for 10 min to obtain a composite resistance ink after paper removal.

[0028] Fifth step: preparing a biomimetic micro-nano structure frequency selective surface (FSS) as an infrared shielding layer The surface of the prepared SiO2 composite aerogel is modified by oxygen plasma etching (PLASMA) and SDS solution treatment, and then a reduced graphene oxide (GO) coating is uniformly applied. The sample is pre-baked at 100°C for 90s, and then naturally cooled to room temperature. The reduced graphene oxide coating is masked and plasma etched using a "cross" standard, and then the sample is inverted and baked at 120°C for 180s, and naturally cooled to room temperature. The AZ5200NJ glue is developed using a developing solution for 80s, and finally the mask is removed to obtain a biomimetic micro-nano structure frequency selective surface, i.e., a graphene cylinder array is formed on the surface of the SiO2 composite aerogel.

[0029] Sixth step: preparing a high-temperature-resistant radar and infrared stealth super material The composite resistance ink is printed on the surface of the SiO2 composite aerogel by a screen printing process as a heat-insulating electromagnetic resonance layer, and a copper sheet is used as an electromagnetic reflection layer and placed at the bottom of the structure. Four layers of electromagnetic resonance layers are sequentially stacked on top of it, and then a prepared infrared shielding layer is stacked on the topmost layer. Finally, the preparation of a high-temperature-resistant radar and infrared stealth super material is completed. Example 2

[0030] First step: preparing a silicon carbide fiber skeleton Preparation of spinning solution: poly-carbosilane (PCS) is selected as the SiC precursor, and mixed according to the ratio of poly-carbosilane (PCS): N,N-dimethylformamide (DMF) = 1:9, with a small amount of hydrochloric acid solution added. The silicon carbide precursor spinning solution is loaded into the electrospinning needle, and a high-voltage electric field and a syringe pump are started to prepare silicon carbide fibers. The electrospun fibers are directly raised to 1200°C in air for 1h, and then raised to 1400°C for 2h. Through the above steps, silicon carbide fibers are prepared.

[0031] Second step: preparation of SiO2 sol The precursor is prepared by using tetraethyl orthosilicate (TEOS) as the precursor, mixing the precursor with water and ethanol according to the molar ratio of TEOS:H2O:ETOH=1:12:16, adding 0.1 mol / L hydrochloric acid solution to adjust PH=2, and performing hydrolysis reaction. The magnetic stirrer is used to stir at a speed of 200 r / min at a temperature of 60°C for 180 min. Then, NH4OH solution is added to adjust PH=7 to complete the polycondensation reaction, and SiO2 sol is formed.

[0032] Step 3: Preparation of SiO2 composite aerogel with silicon carbide fiber as the skeleton The prepared SiO2 sol is used to impregnate the fiber skeleton with silicon carbide fiber as the skeleton. The impregnated aerogel is placed in an ethanol solution at 50°C for 8h to age and shape. Then, the sample is directly placed in a 60°C oven for drying for 24h, and then the temperature is increased to 100°C for drying for 6h. Finally, the SiO2 composite aerogel with silicon carbide fiber as the skeleton is successfully prepared.

[0033] Step 4: Preparation of graphene-MXene composite resistance ink The graphene dispersion liquid and MXene dispersion liquid are mixed and stirred thoroughly by a magnetic stirrer for 30 min. Then, methyl pyrrolidone (NMP), fumed SiO2 powder, carbon nanotube powder (CNT), and ascorbic acid are added in sequence and stirred thoroughly for 30 min. Finally, the ink is coated on paper by a spray pen, dried at room temperature, and baked for 10 min. After removing the paper, the composite resistance ink is obtained.

[0034] Step 5: Preparation of frequency selective surface (FSS) as an infrared shielding layer The surface of the prepared composite aerogel is modified by oxygen plasma etching (PLASMA) treatment. Then, a reduced graphene oxide (GO) coating is uniformly applied, and the sample is pre-baked at a temperature of 100°C for 90s, and then naturally cooled to room temperature.

[0035] Step 6: Preparation of a metamaterial with high-temperature-resistant radar and infrared stealth performance The composite resistance ink is printed on the surface of the SiO2 composite aerogel by a screen printing process as a heat-insulating electromagnetic resonance layer. A copper sheet is used as an electromagnetic reflection layer and placed at the bottom of the structure. Four layers of electromagnetic resonance layers are stacked in sequence on top of the copper sheet. Then, a prepared infrared shielding layer is added on the topmost layer. Finally, the preparation of a metamaterial with high-temperature-resistant radar and infrared stealth performance is completed.

[0036] Disadvantages compared with Example 1 The pure SiC fiber skeleton used therein has lower oxidation resistance and mechanical strength at high temperature than the mullite-SiC composite fiber in the benchmark scheme, and the missing gradient sintering process can introduce structural defects; the aerogel prepared by the ordinary drying method exhibits high shrinkage, easy fragmentation, low porosity, and high thermal conductivity, etc., making its thermal insulation performance far inferior to that of the sample prepared by supercritical drying; in addition, the simplified infrared shielding layer is only a uniform GO coating, lacking the micro-nano structure frequency selective surface (FSS) in the benchmark scheme, which not only leads to low infrared shielding efficiency, but more critically, loses frequency selectivity, and cannot accurately manage the radiant heat signal in a specific infrared waveband. Example 3

[0037] First step: preparation of mullite-silicon carbide composite fiber skeleton Preparation of core layer spinning solution: polycarbosilane (PCS) is selected as the SiC precursor, mixed according to the ratio of polycarbosilane (PCS): N,N-dimethylformamide (DMF) = 1:9, and a small amount of hydrochloric acid solution is added; preparation of shell layer spinning solution: aluminum nitrate (Al(NO3)3·9H2O) and tetraethyl orthosilicate (TEOS) are selected as the precursors, prepared according to a molar ratio of 3:1, dissolved in an ethanol solution, 7wt% polyvinylpyrrolidone (PVP) is added to adjust the viscosity, and a hydrochloric acid solution is added to promote the hydrolysis reaction, and stirred for 24h to form a uniform mullite sol; the core layer silicon carbide precursor spinning solution and the shell layer mullite sol spinning solution are respectively loaded into the coaxial needle, the high-voltage electric field and the injection pump are started, and the mullite-silicon carbide composite fiber is prepared, the electrospun composite fiber is sintered at 600℃ in air for 1h, then the temperature is raised to 1200℃ and sintered for 1h, and then the temperature is raised to 1500℃ and kept for 2h. Through the above steps, the mullite-silicon carbide composite fiber is prepared.

[0038] Second step: preparation of SiO2 sol With tetraethyl orthosilicate (TEOS) as the precursor, the precursor is mixed with water and ethanol according to a molar ratio of TEOS:H2O:ETOH=1:12:16, 0.1mol / L hydrochloric acid solution is added to adjust the pH to 2, hydrolysis reaction is carried out, and the magnetic stirrer is stirred at a speed of 200r / min for 180min at a temperature of 60℃, then NH4OH solution is added, the pH is adjusted to 7 to complete the polycondensation reaction, and SiO2 sol is formed.

[0039] Third step: preparation of SiO2 composite aerogel with mullite-silicon carbide composite fiber as skeleton The prepared SiO2 sol was used to impregnate the mullite-silicon carbide composite fiber framework, and the impregnated aerogel was placed in an ethanol solution at 50°C for 8h to age and shape. Subsequently, the sample was placed in a supercritical CO2 drying device at 50°C and 10MPa for drying treatment, and then constant temperature drying was carried out at 40°C, 60°C, 100°C and 120°C for 3h, 2h, 2h and 30min respectively. Finally, the SiO2 composite aerogel with mullite-silicon carbide composite fiber as the framework was successfully prepared.

[0040] Fourth step: preparation of graphene resistance ink Methyl pyrrolidone (NMP), fumed SiO2 powder, carbon nanotube powder (CNT), and ascorbic acid were sequentially added to the graphene dispersion and stirred for 30min. Finally, the ink was applied to the paper using a spray pen, and the paper was dried at room temperature and then baked for 10min. After removing the paper, the composite resistance ink was obtained.

[0041] Fifth step: preparation of micro-nano structure frequency selective surface (FSS) as an infrared shielding layer The surface of the prepared composite aerogel was modified by combined treatment of oxygen plasma etching (PLASMA) and SDS solution, and then a reduced graphene oxide (GO) coating was uniformly applied. The sample was pre-baked at 100°C for 90s and then naturally cooled to room temperature. A simple grid structure was obtained after developing using ordinary photoresist and conventional ultraviolet lithography process.

[0042] Sixth step: preparation of a metamaterial with high-temperature resistant radar and infrared stealth performance The composite resistance ink was printed on the surface of the SiO2 composite aerogel by screen printing process as a heat-insulating electromagnetic resonance layer. A copper sheet was used as an electromagnetic reflector and placed at the bottom of the structure. Four layers of electromagnetic resonance layers were sequentially stacked on top of it, and then a prepared infrared shielding layer was added on the topmost layer. Finally, the preparation of a metamaterial with high-temperature resistant radar and infrared stealth performance was completed.

[0043] Disadvantages compared with Example 1 The resistance ink only contains graphene, and due to the lack of the high conductivity of MXene and the bridging / enhancing synergy of carbon nanotubes (CNT), the formed conductive network has low conductivity, poor high-temperature stability, and a narrow electromagnetic wave absorption band and weakened wave absorption intensity. At the same time, the infrared shielding layer uses a simple grid structure prepared by conventional lithography process, which is far inferior to the precise plasma etching biomimetic micro-nano FSS in terms of size precision, feature size control, structural complexity and biomimetic optimization. The infrared frequency selection characteristics of this layer are inaccurate, and the shielding efficiency is significantly reduced.

Claims

1. A method for preparing a biomimetic radar-infrared compatible stealth metamaterial based on a novel high-temperature resistant matrix, characterized in that: The method comprises the following steps: (1) preparing a mullite-silicon carbide composite fiber: taking a silicon carbide precursor as an inner layer and a mullite precursor as an outer layer, a mullite-silicon carbide composite fiber is prepared by a coaxial electrospinning process; (2) preparing a SiO2 sol: taking tetraethyl orthosilicate as a precursor, the precursor is mixed with water and ethanol, and a SiO2 sol is formed through a hydrolysis reaction and a polycondensation reaction; (3) preparing a SiO2 composite aerogel with the mullite-silicon carbide composite fiber as a skeleton: the mullite-silicon carbide composite fiber prepared in step (1) is used as a skeleton, the SiO2 sol prepared in step (2) is used to impregnate the mullite-silicon carbide composite fiber prepared in step (1), and finally a SiO2 composite aerogel is formed through CO2 supercritical drying and heat treatment; (4) preparing a graphene-CNT-MXene composite resistance ink: a graphene dispersion liquid and a MXene dispersion liquid are mixed, and then fully stirred by a magnetic stirrer; then methylpyrrolidone, fumed SiO2, carbon nanotube powder and ascorbic acid are sequentially added and fully stirred to obtain the ink; Finally, the ink is coated on paper by a spray pen, dried at room temperature, and then de-papered after baking to obtain the composite resistance ink; (5) preparing a biomimetic micro-nano structure frequency selection surface as an infrared shielding layer: reduced graphene is used as a raw material, and a biomimetic frequency selection surface structure is processed on the SiO2 composite aerogel by oxygen plasma etching to obtain the biomimetic micro-nano structure frequency selection surface; (6) preparing a metamaterial with high-temperature-resistant radar and infrared stealth performance: the composite resistance ink prepared in step (4) is printed on the SiO2 composite aerogel prepared in step (3) by a screen printing process to form a radar and infrared compatible stealth metamaterial with the aerogel as a matrix, then a copper sheet is used as the lowermost reflective layer, and multiple layers of radar and infrared compatible stealth metamaterials are sequentially stacked on the copper sheet, then the infrared shielding layer prepared in step (5) is stacked on the uppermost layer of the radar and infrared compatible stealth metamaterials, and the preparation of the metamaterial with high-temperature-resistant radar and infrared stealth performance is completed.

2. The preparation method of the new high-temperature-resistant substrate-based biomimetic radar-infrared compatible stealth metamaterial according to claim 1, characterized in that: In step (6), the composite resistance ink is printed on the SiO2 composite aerogel by a screen printing process and forms an open resonant ring structure.

3. The preparation method of the new high-temperature-resistant substrate-based biomimetic radar-infrared compatible stealth metamaterial according to claim 1 or 2, characterized in that: In step (5), the graphene cylinder array is formed on the surface of the SiO2 composite aerogel when the biomimetic frequency selection surface structure is processed on the SiO2 composite aerogel.

4. The preparation method of the new high-temperature-resistant substrate-based biomimetic radar-infrared compatible stealth metamaterial according to claim 1 or 2, characterized in that: The prepared metamaterial with high-temperature-resistant radar and infrared stealth performance is periodically arranged in a unit structure to form an overall structure.

5. The preparation method of the new high-temperature-resistant substrate-based biomimetic radar-infrared compatible stealth metamaterial according to claim 1, characterized in that: The specific process for preparing the mullite-silicon carbide composite fiber in step (1) is as follows: preparing a core layer spinning solution: polycarbosilane is selected as the SiC precursor, and is mixed with N,N-dimethylformamide at a ratio of 1:9, and a small amount of hydrochloric acid solution is added; preparing a shell layer spinning solution: mullite precursor is prepared by selecting aluminum nitrate nonahydrate and tetraethyl orthosilicate at a molar ratio of 3:1, and is dissolved in an ethanol solution, 7wt% polyvinylpyrrolidone is added to adjust the viscosity, and a hydrochloric acid solution is added to promote the hydrolysis reaction, and the shell layer spinning solution is stirred to form a uniform shell layer spinning solution; the core layer spinning solution and the shell layer spinning solution are respectively filled into the inner tube and the outer tube of the coaxial needle of the electrospinning, a high-voltage electric field and a syringe pump are started, and the mullite-silicon carbide composite fiber is prepared, the electrospun mullite-silicon carbide composite fiber is sintered at 600℃ in air for 1h, the temperature is then increased to 1200℃ and sintered for 1h, and then the temperature is increased to 1500℃ and kept for 2h; through the above steps, the mullite-silicon carbide composite fiber is prepared.

6. The preparation method of the novel high-temperature-resistant substrate-based biomimetic radar-infrared compatible stealth metamaterial according to claim 5, characterized in that: The specific process for preparing the SiO2 sol in step (2) is as follows: tetraethyl orthosilicate is used as the precursor, and the precursor is mixed with water and ethanol at a molar ratio of 1:12:16, 0.1mol / L hydrochloric acid solution is added to adjust the pH to 2, and the hydrolysis reaction is carried out, and the magnetic stirrer is used to stir at a speed of 200r / min for 180min at a temperature of 60℃, then NH4OH solution is added to adjust the pH to 7 to complete the polycondensation reaction, and the SiO2 sol is formed.

7. The preparation method of the novel high-temperature-resistant substrate-based biomimetic radar-infrared compatible stealth metamaterial according to claim 6, characterized in that: The specific process for preparing the SiO2 composite aerogel with the mullite-silicon carbide composite fiber as the skeleton in step (3) is as follows: the mullite-silicon carbide composite fiber is used as the skeleton, and the prepared SiO2 sol is used to impregnate the composite fiber skeleton, the impregnated aerogel is placed in an ethanol solution at 50℃ for 8h to age and shape, then the sample is placed in a supercritical CO2 drying device at 50℃ and 10MPa for drying treatment, and then the sample is dried at a constant temperature of 40℃, 60℃, 100℃ and 120℃ for 3h, 2h, 2h and 30min respectively, and finally the SiO2 composite aerogel with the mullite-silicon carbide composite fiber as the skeleton is successfully prepared.

8. The preparation method of the novel high-temperature-resistant substrate-based biomimetic radar-infrared compatible stealth metamaterial according to claim 7, characterized in that: The specific process for preparing the graphene-CNT-MXene composite resistance ink in step (4) is as follows: the graphene dispersion liquid and the MXene dispersion liquid are mixed, and are fully stirred for 30min by a magnetic stirrer, then methylpyrrolidone, fumed SiO2 powder, carbon nanotube powder and ascorbic acid are added in sequence and are fully stirred for 30min to obtain the ink, finally the ink is coated on paper by a spray pen, is air-dried at room temperature, and is baked for 10min, and after the paper is removed, the composite resistance ink is obtained.

9. The preparation method of the novel high-temperature-resistant substrate-based biomimetic radar-infrared compatible stealth metamaterial according to claim 8, characterized in that: The specific process of step (5) for preparing the biomimetic micro-nano structure frequency selective surface as an infrared shielding layer is as follows: the surface of the prepared SiO2 composite aerogel is modified by oxygen plasma etching and SDS solution combined treatment, then a reduced graphene coating is uniformly applied, the sample is pre-baked at a temperature of 100 DEG C for 90 s, then it is naturally cooled to room temperature, the reduced graphene coating is masked and plasma etched by using a cross standard, then the sample is reverse baked at 120 DEG C for 180 s, it is naturally cooled to room temperature, the AZ5200NJ glue is developed by using a developing solution for 80 s, and finally the mask is removed to obtain the biomimetic micro-nano structure frequency selective surface.

Images