Radar and infrared compatible stealth coating as well as preparation method and application thereof

Abstract

The invention discloses a radar and infrared compatible stealth coating as well as a preparation method and application thereof, and relates to the field of radar and infrared compatible stealth, the preparation method comprises the following steps: S1, preparing magnetic wave-absorbing powder by adopting a hydrothermal method; s2, mixing the wave-absorbing powder with a coating adhesive and a thickening agent to obtain coating slurry, and pouring the coating slurry into a mold for drying to obtain a radar stealth coating; s3, the MAX phase material is etched, and an MXene aqueous dispersion liquid is obtained; and S4, coating the radar stealth coating with the coating adhesive, then coating the radar stealth coating with the MXene aqueous dispersion, drying, and repeatedly coating for 1-3 times to obtain the radar and infrared compatible stealth coating. The surface of the fabric is coated with the composite coating, the minimum reflection loss within the frequency band of 8-18 GHz reaches-61.81 dB, the effective absorption bandwidth reaches 8.78 GHz, the infrared emissivity under the wave bands of 3-5 microns and 8-14 microns is 0.260 and 0.172 respectively, and high-performance infrared and radar dual-waveband stealth is achieved.

Description

Technical Field

[0001] The present invention relates to the field of radar and infrared compatible stealth technology, and in particular to a radar infrared compatible stealth coating and a preparation method and application thereof. Background Art

[0002] In modern warfare, radar and infrared detection systems are widely used for target identification and positioning. Traditional single-band stealth technologies struggle to achieve optimal stealth performance in complex and challenging battlefield environments and are gradually becoming ineffective. Therefore, the development of multi-band stealth materials with both radar and infrared stealth capabilities has become a key requirement for practical applications and holds great strategic significance.

[0003] According to radar and infrared stealth mechanisms, electromagnetic wave absorbing materials require high absorption and low reflection, while infrared stealth materials require low absorption and high reflection. Therefore, addressing the compatibility issue between infrared and radar is crucial. The effectiveness of infrared stealth is primarily influenced by two factors: the surface temperature of the object and its emissivity. Coating an object's surface with a low-emissivity material can effectively weaken its thermal radiation signature, allowing it to blend more naturally into its surroundings. Therefore, coating an electromagnetic wave absorbing base layer with a low-infrared emissivity layer can address the infrared and radar compatibility issue.

[0004] Zinc ferrite (ZnFe2O4) has the advantages of ferromagnetism, easy synthesis, low cost, and good dispersibility, and can be used in the preparation of the bottom electromagnetic wave absorption layer. Selecting a surface low infrared emissivity material that does not affect electromagnetic wave absorption will be an effective way to solve the multi-band stealth compatibility problem. Ti3C2T x -MXene is an emerging two-dimensional (2D) nanomaterial. Due to its intrinsic low infrared emissivity, Ti3C2T x -MXene is a promising material in the field of infrared stealth. More importantly, Ti3C2T x -MXene has a high specific surface area, excellent conductivity and rich surface functional groups. Based on the principle of electromagnetic synergy, the introduction of MXene into magnetic materials can optimize the impedance matching of the composite material and improve the electromagnetic wave absorption.

[0005] Chinese invention patent publication number CN114055874A discloses a dual-stealth shelter coating that combines radar and infrared stealth. The radar stealth layer utilizes an absorbing material layer with broadband radar shielding properties. The coating comprises a sequentially stacked infrared stealth coating, a wave-transparent outer skin, a radar stealth layer, a composite skin layer, a bulletproof layer, an absorbing foam layer, and an inner skin layer, thereby achieving dual stealth. However, the multi-layer coating structure may have disadvantages such as high cost, difficulty in preparation, insufficient interlayer adhesion, and heavy weight. Chinese invention patent publication number CN109423181A discloses a radar-resistant infrared coating and its preparation method. First, a radar-resistant infrared coating is prepared, which is then sprayed onto an absorbing material to form a radar-resistant coating. Notably, the resulting radar-resistant coating exhibits an absorption performance of only -3dB, which is insufficient for practical applications. Most of the coatings that currently achieve radar and infrared dual-band stealth have an infrared stealth layer on the surface that will adversely affect the overall radar stealth performance of the coating. The actual stealth effect of these coatings is also not very ideal. At present, research on the use of MXene to prepare infrared stealth surface layers is relatively rare. Selecting a surface low-infrared emissivity material that does not affect electromagnetic wave absorption will be an effective way to solve the multi-band stealth compatibility problem. Summary of the Invention

[0006] The present invention overcomes the deficiencies of the prior art and provides a radar infrared compatible stealth coating and a preparation method and application thereof.

[0007] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing a radar infrared compatible stealth coating, comprising the following steps:

[0008] S1. Prepare magnetic absorbing powder by hydrothermal method;

[0009] S2. Mixing the absorbing powder with the coating glue and thickener to obtain a coating slurry, and pouring the mixture into a mold and drying it to obtain a radar stealth coating;

[0010] S3, etching the MAX phase material to obtain a MXene aqueous dispersion;

[0011] S4. Apply coating glue on the radar stealth coating, then apply MXene aqueous dispersion, dry, and repeat the coating 1 to 3 times to obtain a radar infrared compatible stealth coating.

[0012] In a preferred embodiment of the present invention, in step S1, the magnetic absorbing powder is one of ZnFe2O4, Fe3O4, CuFe2O4 or Fe2O3; the hydrothermal temperature is 190-210°C, and the time is 8-12h.

[0013] In a preferred embodiment of the present invention, in steps S2 and S4, the coating adhesive is one of water-based polyurethane, acrylic resin or polyvinyl chloride coating adhesive.

[0014] In a preferred embodiment of the present invention, in step S2, the thickener is one of sodium alginate, sodium carboxymethyl cellulose or starch.

[0015] In a preferred embodiment of the present invention, in step S2, the coating slurry comprises, by mass percentage, 30-50% of the absorbing powder, 47-68% of the coating glue, and 2-3% of the thickener.

[0016] In a preferred embodiment of the present invention, in the step S3, the etching method of the MAX phase material is carried out by one of HF, NH4HF2 or LiF+HCl; the MXene is Ti3C2T x 、Ti2CT x 、Ti3CNT x or V2CT x One of them.

[0017] In a preferred embodiment of the present invention, in step S4, the concentration of the MXene aqueous dispersion is 2 to 8 mg / mL.

[0018] In a preferred embodiment of the present invention, in step S4, the drying temperature is 40-60° C., and the treatment time is 2-4 hours.

[0019] The present invention provides a radar infrared compatible stealth coating, which is prepared by any one of the aforementioned preparation methods.

[0020] The present invention provides an application of the aforementioned radar infrared compatible stealth coating on a fabric surface, wherein the fabric is one of cellulose fiber fabric, protein fiber fabric, polyester fabric, nylon fabric or aramid fabric.

[0021] The present invention solves the defects existing in the background technology and has the following beneficial effects:

[0022] (1) The present invention provides a radar infrared compatible stealth coating and its preparation method and application. The radar stealth layer is formed by using absorbing powder, and MXene is applied after applying polyurethane coating glue to ensure that MXene forms a stable and continuous film, reducing infrared emissivity to achieve infrared stealth. The low infrared emissivity and radar wave absorption performance are balanced by accurately controlling the amount of MXene, avoiding the surface infrared stealth layer from adversely affecting the radar stealth performance of the entire coating. The composite coating of the present invention is applied on the surface of the fabric, with minimum reflection loss (RL min ) reaches -61.81dB, the effective absorption bandwidth (EAB) reaches 8.78GHz, and the infrared emissivity in the 3-5μm and 8-14μm bands are 0.260 and 0.172 respectively, achieving high-performance infrared and radar dual-band stealth.

[0023] (2) In the present invention, the synergy of ZnFe2O4 and MXene in appropriate amounts can achieve excellent performance in infrared and radar dual-band stealth. The three-dimensional conductive network formed by MXene is conductive, provides a continuous electron conduction path, and promotes conductive loss. The rich end groups (-O, -OH) and structural defects on the MXene sheet are used to induce dipole polarization, and the heterogeneous interface between MXene and ZnFe2O4 produces charge accumulation, inducing interface polarization and enhancing electromagnetic wave (EMW) dissipation. The magnetic properties of ZnFe2O4 can convert electromagnetic wave energy into heat energy through magnetic loss, and the coating glue in the absorbing powder slurry physically wraps the absorbing powder particles to form a uniform dispersion system, reducing particle agglomeration. By adjusting the dielectric constant and magnetic permeability of the coating, the impedance matching is optimized, and the overall absorbing performance is improved, thereby solving the disadvantages of high cost, difficulty in preparation, insufficient interlayer adhesion, and heavy weight brought about by the multi-layer coating structure to achieve radar infrared compatible stealth.

[0024] (3) In the present invention, a surface MXene layer and a bottom absorbing powder layer are formed. The dielectric constant of the MXene layer can be regulated by the coating glue and thickener to be close to the impedance of free space. The thickness of the MXene layer is effectively designed to minimize the reflection of electromagnetic waves at the interface, so that the electromagnetic waves entering the surface MXene layer are absorbed by conductive loss, and the residual electromagnetic waves enter the bottom absorbing powder layer and consume energy through the magnetic loss of ZnFe2O4, thereby making the composite coating have excellent radar stealth effect. At the same time, the low emissivity of the MXene film is combined with the electromagnetic wave absorption characteristics of the absorbing layer to achieve dual compatibility of infrared and radar stealth, avoiding the adverse effect of the surface infrared stealth layer on the overall radar stealth performance of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments described in the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive efforts.

[0026] Figure 1 Graphs showing the electromagnetic wave absorption performance of the MXene / ZnFe2O4 compatible stealth coating coated fabric-1 in Example 1 of the present invention, wherein (a) and (b) are graphs showing the electromagnetic wave absorption performance in the 8.2-12.4 GHz frequency band, and (c) and (d) are graphs showing the electromagnetic wave absorption performance in the 12.4-18 GHz frequency band;

[0027] Figure 2 Graphs showing the electromagnetic wave absorption performance of the MXene / ZnFe2O4 compatible stealth coating coated fabric-2 in Example 2 of the present invention, wherein (a) and (b) are graphs showing the electromagnetic wave absorption performance in the 8.2-12.4 GHz frequency band, and (c) and (d) are graphs showing the electromagnetic wave absorption performance in the 12.4-18 GHz frequency band;

[0028] Figure 3 3 is a graph showing the electromagnetic wave absorption performance of the MXene / ZnFe2O4 compatible stealth coating coated fabric-3 in Example 3 of the present invention, wherein (a) and (b) are graphs showing the electromagnetic wave absorption performance in the 8.2-12.4 GHz frequency band, and (c) and (d) are graphs showing the electromagnetic wave absorption performance in the 12.4-18 GHz frequency band;

[0029] Figure 4 This is the infrared emissivity diagram of the MXene / ZnFe2O4 compatible stealth coating coated fabric-2 in Example 2 of the present invention, wherein (a) is the infrared emissivity diagram in the 3-5 μm band, and (b) is the infrared emissivity diagram in the 8-14 μm band. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0031] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0032] It should be noted that the raw materials, equipment, reagents, etc. used in the present invention can be purchased from the market or obtained through existing preparation methods.

[0033] A method for preparing a radar infrared compatible stealth coating comprises the following steps:

[0034] S1. Prepare magnetic absorbing powder by hydrothermal method;

[0035] S2. Mixing the absorbing powder with the coating glue and thickener to obtain a coating slurry, and pouring the mixture into a mold and drying it to obtain a radar stealth coating;

[0036] S3, etching the MAX phase material to obtain a MXene aqueous dispersion;

[0037] S4. Apply coating glue on the radar stealth coating, then apply MXene aqueous dispersion, dry, and repeat the coating 1 to 3 times to obtain a radar infrared compatible stealth coating.

[0038] In some specific embodiments, in step S1, the magnetic absorbing powder is one of ZnFe2O4, Fe3O4, CuFe2O4 or Fe2O3; the hydrothermal temperature is 190-210°C, and the time is 8-12h.

[0039] In some specific embodiments, in steps S2 and S4, the coating adhesive is one of water-based polyurethane, acrylic resin or polyvinyl chloride coating adhesive.

[0040] In some specific embodiments, in step S2, the thickener is one of sodium alginate, sodium carboxymethyl cellulose or starch.

[0041] In some specific embodiments, in step S2, the coating slurry comprises, by mass percentage, 30-50% of the absorbing powder, 47-68% of the coating glue, and 2-3% of the thickener.

[0042] In some specific embodiments, in step S3, the etching of the MAX phase material is performed by one of HF, NH4HF2 or LiF+HCl; MXene is Ti3C2T x 、Ti2CT x 、Ti3CNT x or V2CT x One of them.

[0043] MAX phases are a class of materials with a layered structure composed of Mn+1AXn (M is an early transition metal, A is a Group IIIA or IVA element, and X is carbon or nitrogen). MXene is named after the MAX phase, with "M" representing an early transition metal, "X" representing carbon or nitrogen, and "ene" indicating its two-dimensional nature. Because MX bonds have strong bonding energy and the chemically active A element, the A element can be removed from the MAX phase through an etching process, resulting in a graphene-like two-dimensional structure called MXene.

[0044] In some specific embodiments, in step S4, the concentration of the MXene aqueous dispersion is 2 to 8 mg / mL.

[0045] In some specific embodiments, in step S4, the drying temperature is 40-60° C., and the treatment time is 2-4 hours.

[0046] The present invention provides a radar infrared compatible stealth coating, which is prepared by any one of the aforementioned preparation methods.

[0047] The present invention provides an application of the aforementioned radar infrared compatible stealth coating on a fabric surface, wherein the fabric is one of cellulose fiber fabric, protein fiber fabric, polyester fabric, nylon fabric or aramid fabric.

[0048] In order to further make the purpose and effect of the present invention simple and easy to understand, the present invention is further described in conjunction with the following specific examples and comparative examples.

[0049] It should be noted that, in the Examples and Comparative Examples, the description of the preparation of raw materials is as follows:

[0050] ZnCl2: purity >98%, molecular weight 136.29, purchased from Jinan Kaichuang Chemical; FeCl3·6H2O: purity >99%, CAS number 10025-77-1, purchased from Hubei Dali Chemical; PEG4000: purity >99%, density 1.27 g / cm 3 , CAS No. 25322-68-3, purchased from Jinan 168 Chemical Industry; NaAc: purity >99%, molecular weight 77.082, density 1.01 g / cm 3 , purchased from Jinan Kaichuang Chemical; waterborne polyurethane: molecular weight 116.9, density 1.325g / cm 3 , purchased from Xiamen Shenghonghua Chemical; sodium alginate: purity > 99%, purchased from Sichuan Kangbairui Biological; HCl: brand WKQ-0016730, purchased from Sichuan Weikeqi Biological; LiF: purity > 99%, CAS number 7789-24-4, purchased from Wuhan Jixin Yibang Biological; Ti3AlC2: brand 26531, particle size 6000 mesh, purchased from Shanghai Yingfeng Ruihuang Metal;

[0051] Example 1

[0052] A method for preparing a radar infrared compatible stealth coating applied to a fabric surface comprises the following steps:

[0053] S1. ZnCl2, FeCl3·6H2O, PEG4000, and NaAc were mixed in an ethylene glycol solution and stirred evenly. The mixed solution was then transferred to a reactor and hydroheated at 200°C for 10 h. The precipitate was washed with water and dried at 60°C for 12 h to obtain magnetic ZnFe2O4 powder.

[0054] S2. Prepare a coating slurry with a ZnFe2O4 ratio of 45%, a water-based polyurethane ratio of 53%, and a sodium alginate ratio of 2%, pour the coating slurry into a mold and dry it to obtain a radar stealth coating;

[0055] S3. Pour 40 mL of 9 M HCl solution into a polytetrafluoroethylene beaker, weigh 3.2 g of LiF and add it to the beaker, stir for 5 min to obtain an etching solution, add 2 g of Ti3AlC2 powder to the etching solution, and react at 38°C with magnetic stirring for 48 h. Then, the multilayer MXene dispersion obtained after the reaction is centrifuged and washed in water several times until the pH reaches 7. Finally, the multilayer MXene dispersion is ultrasonically treated for 60 min and centrifuged for 30 min to prepare a few-layer MXene aqueous dispersion with a concentration of 2 mg / mL.

[0056] S4. Coat water-based polyurethane on the radar stealth coating, then coat it with 2 mg / mL of MXene aqueous dispersion, dry it, and repeat the coating twice to obtain a radar infrared compatible stealth coating, and apply it to the surface of the aramid fabric. The amount of MXene aqueous dispersion is 10 mL. Then, dry it in a vacuum oven at 60°C for 4 hours to obtain MXene / ZnFe2O4 compatible stealth coating coated fabric-1.

[0057] The MXene / ZnFe2O4 compatible stealth coating obtained in Example 1 was applied to fabric-1, and its electromagnetic wave absorption performance was tested using a vector network analyzer. Figure 1 As shown in (b) and (d), RL of MXene / ZnFe2O4 compatible stealth coating fabric-1 min (minimum reflection loss) reaches -13.94dB, such as Figure 1 As shown in (a) and (c), its effective absorption bandwidth is 6.62 GHz.

[0058] Example 2

[0059] This embodiment is basically the same as Example 1, except that the amount of MXene dispersion used is different. The step of S3 is to prepare a few-layer MXene aqueous dispersion with a concentration of 5 mg / mL. The step of S4 is to coat the radar stealth coating with water-based polyurethane, then coat it with 5 mg / mL of MXene aqueous dispersion, dry it, and repeat the coating twice to obtain a radar infrared compatible stealth coating, and then apply it to the surface of the aramid fabric. The amount of MXene aqueous dispersion used is 10 mL, and then it is dried in a vacuum oven at 60°C for 4 hours to obtain MXene / ZnFe2O4 compatible stealth coating coated fabric-2.

[0060] The MXene / ZnFe2O4 compatible stealth coating obtained in Example 2 was applied to fabric-2, and its electromagnetic wave absorption performance was tested using a vector network analyzer. Figure 2 As shown in (b) and (d), RL of MXene / ZnFe2O4 compatible stealth coating coated fabric-2 min Reach -61.81dB, such as Figure 1 As shown in (a) and (c), its effective absorption bandwidth is 8.78 GHz. The infrared emissivity of the MXene / ZnFe2O4 compatible stealth coating coated fabric-2 was tested using a Fourier transform infrared spectrometer. Figure 4 As shown in (a) and (b), the results show that its infrared emissivity in the 3-5μm and 8-14μm bands is 0.260 and 0.172 respectively, achieving high-performance infrared and radar dual-band stealth.

[0061] Example 3

[0062] This embodiment is basically the same as Example 1, except that the amount of MXene dispersion used is different. The step of S3 is to prepare a few-layer MXene aqueous dispersion with a concentration of 8 mg / mL. The step of S4 is to coat the radar stealth coating with water-based polyurethane, then coat it with 8 mg / mL of MXene aqueous dispersion, dry it, and repeat the coating twice to obtain a radar infrared compatible stealth coating, and then apply it to the surface of the aramid fabric. The amount of MXene aqueous dispersion used is 10 mL, and then it is dried in a vacuum oven at 60°C for 4 hours to obtain MXene / ZnFe2O4 compatible stealth coating coated fabric-3.

[0063] The MXene / ZnFe2O4 compatible stealth coating obtained in Example 3 was applied to fabric-3, and its electromagnetic wave absorption performance was tested using a vector network analyzer. Figure 3 As shown in (b) and (d), RL of MXene / ZnFe2O4 compatible stealth coating coated fabric-3 min Reach -26.10dB, such as Figure 3As shown in (a) and (c), its effective absorption bandwidth is 7.92 GHz.

[0064] Comparison of Examples 1-3 shows that the MXene layer and the absorbing powder layer form a composite layer. The dielectric constant of the MXene layer can be adjusted by the coating adhesive and thickener to approach the impedance of free space, thereby reducing the reflection of electromagnetic waves on the surface. The electromagnetic waves first enter the MXene layer and are absorbed through conductive losses (free electron oscillations). The residual waves then enter the absorbing powder layer, where the magnetic losses of ZnFe2O4 consume energy. By adjusting the dielectric constant and magnetic permeability of the coating, the impedance matching is optimized. If the MXene layer is too thick, the high conductivity of MXene causes the electromagnetic waves to be reflected at the surface, preventing them from entering the absorbing layer. The absorbing layer cannot effectively function, resulting in a significant decrease in overall absorption performance.

[0065] In order to further illustrate the present invention, the best embodiment 2 is used as the basis for comparative example.

[0066] Comparative Example 1

[0067] This comparative example is basically the same as Example 2, except that: the MXene layer is missing, there is no S3 step, and the S4 step is: applying the radar stealth coating on the surface of the aramid fabric, and then drying it in a vacuum oven at a temperature of 60°C for 4 hours to obtain the ZnFe2O4 absorbing coating coated fabric.

[0068] Comparative Example 2

[0069] This comparative example is basically the same as Example 2, except that the concentration of the MXene aqueous dispersion is different. The step of S3 is to prepare a few-layer MXene aqueous dispersion with a concentration of 1 mg / mL. The step of S4 is to apply water-based polyurethane on the radar stealth coating, and then apply 1 mg / mL of MXene aqueous dispersion, dry it, and repeat the coating twice to obtain a radar infrared compatible stealth coating, and apply it to the surface of the aramid fabric. The amount of MXene aqueous dispersion is 10 mL, and then it is dried in a vacuum oven at 60°C for 4 hours to obtain a MXene / ZnFe2O4 compatible stealth coating coated fabric.

[0070] Comparative Example 3

[0071] This comparative example is basically the same as Example 2, except that the concentration of the MXene aqueous dispersion is different. The step of S3 is to prepare a few-layer MXene aqueous dispersion with a concentration of 10 mg / mL. The step of S4 is to apply water-based polyurethane on the radar stealth coating, and then apply 10 mg / mL of MXene aqueous dispersion, dry it, and repeat the coating twice to obtain a radar infrared compatible stealth coating, and apply it to the surface of the aramid fabric. The amount of MXene aqueous dispersion is 10 mL, and then it is dried in a vacuum oven at 60°C for 4 hours to obtain a MXene / ZnFe2O4 compatible stealth coating coated fabric.

[0072] Comparative Example 4

[0073] This comparative example is basically the same as Example 2, except that: the radar stealth coating is missing, there are no steps S1 and S2, and the step S4 is: coating 5 mg / mL of MXene aqueous dispersion in the mold, drying, repeating the coating twice to obtain an infrared stealth coating, and applying it on the surface of the aramid fabric. The amount of MXene aqueous dispersion is 10 mL, and then drying at a temperature of 60°C in a vacuum oven for 4 hours to obtain a MXene infrared stealth coating-coated fabric.

[0074] Comparative Example 5

[0075] This comparative example is basically the same as Example 2, except that the amount of absorbing powder used is different. The step of S2 is: preparing a coating slurry with a ZnFe2O4 ratio of 30%, a water-based polyurethane ratio of 68%, and a sodium alginate ratio of 2%, pouring the coating slurry into a mold and drying it to obtain a radar stealth coating.

[0076] Comparative Example 6

[0077] This comparative example is basically the same as Example 2, except that the amount of absorbing powder used is different. The step of S2 is: preparing a coating slurry with a ZnFe2O4 ratio of 28%, a water-based polyurethane ratio of 70%, and a sodium alginate ratio of 2%, pouring the coating slurry into a mold and drying it to obtain a radar stealth coating.

[0078] Comparative Example 7

[0079] This comparative example is basically the same as Example 2, except that the amount of absorbing powder used is different. The step of S2 is: preparing a coating slurry with a ZnFe2O4 ratio of 50%, a water-based polyurethane ratio of 48%, and a sodium alginate ratio of 2%, pouring the coating slurry into a mold and drying it to obtain a radar stealth coating.

[0080] Comparative Example 8

[0081] This comparative example is basically the same as Example 2, except that the amount of absorbing powder used is different. The step of S2 is: preparing a coating slurry with a ZnFe2O4 ratio of 53%, a water-based polyurethane ratio of 45%, and a sodium alginate ratio of 2%, pouring the coating slurry into a mold and drying it to obtain a radar stealth coating.

[0082] Performance testing: The coated fabrics obtained in Comparative Examples 1-8 were tested for minimum reflection loss at 8.2-18 GHz using a vector network analyzer, and their infrared emissivity at 3-5 μm and 8-14 μm bands using a Fourier transform infrared spectrometer, and compared with Example 2. The results are shown in Table 1.

[0083] Table 1: Performance test results of the coated fabrics of Comparative Examples 1-8

[0084]

[0085]

[0086] As shown in Table 1:

[0087] By comparing Example 2 with Comparative Example 1, it can be seen that the absence of the MXene layer leads to a significant increase in infrared emissivity (reaching 0.564 in the 3-5 μm band and 0.483 in the 8-14 μm band), while the radar stealth performance (RLmin is only -10.23 dB) is much lower than that of Example 2 (-61.81 dB). The absence of the MXene layer not only causes the surface to lose its low infrared emissivity characteristics, but also causes the dielectric-magnetic cooperative loss mechanism to fail. The conductive network and surface functional groups of MXene (such as -O, -OH) can induce interfacial polarization, while the magnetic particles of ZnFe2O4 dissipate electromagnetic wave energy through magnetic loss. When the MXene layer is missing, the electromagnetic wave cannot be effectively absorbed through the surface conductive loss. When the residual wave enters the underlying absorbing layer, the lack of interfacial polarization leads to insufficient energy dissipation. At the same time, the charge accumulation effect of the heterogeneous interface between MXene and ZnFe2O4 disappears, and the overall absorbing performance is greatly reduced.

[0088] By comparing Example 2 with Comparative Examples 2-3, it can be seen that the radar absorption and infrared stealth performance of Comparative Example 2 (MXene concentration 1 mg / mL) and Comparative Example 3 (MXene concentration 10 mg / mL) are inferior to those of Example 2 (5 mg / mL). When the MXene concentration is too low, the content of MXene nanosheets in the dispersion is insufficient, and a continuous and dense conductive network cannot be formed on the coating surface, resulting in a limited reduction in infrared emissivity. At the same time, the interface polarization effect between MXene and ZnFe2O4 is weakened, and electromagnetic wave absorption is limited. When the MXene concentration is too high, the MXene nanosheets are stacked too densely, and a highly conductive interface is formed on the coating surface. The electromagnetic waves are strongly reflected at the surface and cannot enter the underlying absorbing layer. At the same time, the synergistic effect of MXene and ZnFe2O4 is hindered by the densification of the interlayer structure, and the magnetic loss mechanism cannot be effectively exerted, resulting in deterioration of the absorbing performance.

[0089] By comparing Example 2 with Comparative Example 4, it can be seen that the absence of the ZnFe2O4 absorbing layer and the presence of the MXene layer alone result in a significant decrease in the electromagnetic wave absorption performance (RLmin is only -2.46dB). The high conductivity of MXene causes its surface layer to form a highly reflective interface similar to that of metal, and electromagnetic waves are directly reflected on the surface instead of being absorbed. In addition, the absence of the ZnFe2O4 absorbing layer causes the bottom layer to lose its magnetic loss mechanism, and the electromagnetic wave energy cannot be converted into heat energy through the eddy current loss and natural resonance of the magnetic particles. Relying solely on the conductive loss of MXene is not enough to achieve efficient wave absorption. Although the low infrared emissivity characteristics of MXene are retained (0.294 in the 3-5μm band), the loss of radar stealth performance shows that the synergistic effect of the absorbing layer and the MXene layer is crucial for dual-band stealth.

[0090] Comparison of Example 2 with Comparative Examples 5-8 reveals that when the ZnFe2O4 dosage is less than 30%, insufficient absorbing powder content weakens the magnetic loss capability, and an excessively high coating adhesive ratio causes the dielectric constant to deviate from the optimized range, disrupting the impedance matching between the surface MXene and the underlying absorbing layer, preventing electromagnetic waves from effectively entering the absorbing layer. Furthermore, the lack of ZnFe2O4 particles reduces the heterogeneous interface between the surface MXene and the underlying absorbing layer, reducing the interfacial polarization effect. When the ZnFe2O4 dosage exceeds 50%, the absorbing powder particles tend to agglomerate due to the high concentration, resulting in an uneven internal structure of the coating, an imbalance in the dielectric constant and magnetic permeability, and deteriorated impedance matching. Furthermore, excessive ZnFe2O4 reduces the coating's flexibility, affects the uniform coating of the MXene layer, and further weakens the synergistic effect of conductive and magnetic losses, ultimately leading to a decrease in absorbing bandwidth and reflection loss performance.

[0091] The above description is based on the ideal embodiment of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be considered as illustrative and non-restrictive in all respects. The scope of the present invention is defined by the appended claims, not the foregoing description, and it is intended that all variations within the meaning and range of equivalents of the claims be encompassed within the present invention. Any reference signs in the claims should not be construed as limiting the claim to which they relate.

[0092] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for preparing a radar infrared compatible stealth coating, characterized in that: The following steps are involved: S1. Prepare magnetic absorbing powder by hydrothermal method; S2. Mixing the absorbing powder with the coating glue and thickener to obtain a coating slurry, and pouring the mixture into a mold and drying it to obtain a radar stealth coating; S3, etching the MAX phase material to obtain a MXene aqueous dispersion; S4. Apply coating glue on the radar stealth coating, then apply MXene aqueous dispersion, dry, and repeat the coating 1 to 3 times to obtain a radar infrared compatible stealth coating.

2. The method for preparing a radar infrared compatible stealth coating according to claim 1, characterized in that: In step S1, the magnetic absorbing powder is one of ZnFe2O4, Fe3O4, CuFe2O4 or Fe2O3; the hydrothermal temperature is 190-210°C, and the time is 8-12 hours.

3. The method for preparing a radar infrared compatible stealth coating according to claim 1, characterized in that: In steps S2 and S4, the coating adhesive is one of water-based polyurethane, acrylic resin or polyvinyl chloride coating adhesive.

4. The method for preparing a radar infrared compatible stealth coating according to claim 1, characterized in that: In step S2, the thickener is one of sodium alginate, sodium carboxymethyl cellulose or starch.

5. The method for preparing a radar infrared compatible stealth coating according to claim 1, characterized in that: In the step S2, the coating slurry comprises, by mass percentage, 30-50% of the absorbing powder, 47-68% of the coating glue, and 2-3% of the thickener.

6. The method for preparing a radar infrared compatible stealth coating according to claim 1, characterized in that: In the step S3, the etching method of the MAX phase material is carried out by one of HF, NH4HF2 or LiF+HCl; the MXene is Ti3C2T x 、Ti2CT x 、Ti3CNT x or V2CT x One of them.

7. The method for preparing a radar infrared compatible stealth coating according to claim 1, characterized in that: In the step S4, the concentration of the MXene aqueous dispersion is 2 to 8 mg / mL.

8. The method for preparing a radar infrared compatible stealth coating according to claim 1, characterized in that: In the step S4, the drying temperature is 40-60° C., and the treatment time is 2-4 hours.

9. A radar infrared compatible stealth coating, characterized by: Prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the radar infrared compatible stealth coating according to claim 9 on a fabric surface, characterized in that: The fabric is one of cellulose fiber fabric, protein fiber fabric, polyester fabric, nylon fabric or aramid fabric.

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