Preparation method of infrared and radar stealth fabric

Abstract

The application discloses a preparation method of infrared and radar stealth fabric, comprising the following steps: S1, fabric is ultrasonically immersed, and is soaked by using an alkaline solution, is washed and dried, and a pretreated fabric is obtained; S2, wave-absorbing powder and coating glue are mixed, a thickening agent is added, and the mixture is coated on the fabric, and the fabric is dried, and a composite fabric is obtained; S3, a MAX phase material is etched, and an MXene dispersion liquid is obtained; S4, coating glue is coated on the composite fabric, the MXene dispersion liquid is coated, and the fabric is dried, and the coating is repeated 1-3 times, and an MXene / wave-absorbing powder / fabric is obtained. By using the wave-absorbing powder to form a radar stealth layer, and by coating polyurethane coating glue and then coating MXene, the stability and continuity of the MXene film are ensured, the emissivity is reduced, and infrared stealth is realized, that is, the integrity of the MXene structure is not damaged by traditional mixed coating, and by accurately controlling the amount of MXene, the infrared low emissivity and radar wave absorption performance are balanced, and high-performance infrared and radar dual-band stealth is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of infrared and radar stealth technology, and particularly relates to a preparation method of infrared and radar stealth fabric. BACKGROUND

[0002] With the continuous progress of modern science and technology, the importance of stealth technology in military and civilian fields is increasingly prominent. Among them, infrared stealth and radar stealth are two crucial technologies. Infrared stealth refers to reducing or eliminating the radiation of an object in the infrared spectrum to avoid being detected by an infrared detection system; while radar stealth refers to reducing or eliminating the reflection and scattering of radar waves by an object, so that it is not easily detected in a radar system.

[0003] In modern warfare, infrared detection systems and radar systems are widely used in target identification and navigation positioning. However, with the continuous progress of science and technology, the enemy is also constantly improving its reconnaissance and monitoring capabilities, and the detection methods are also diversifying, making traditional single and poor performance stealth technology gradually ineffective. Therefore, it is of great strategic significance to develop a new type of fabric that can have high-performance infrared stealth and radar stealth.

[0004] The detection range of infrared detectors mainly focuses on the 8-14 micrometer band, which highlights and identifies targets by capturing the thermal signals emitted by objects in this band. The infrared stealth effect is mainly affected by two factors: the surface temperature of the object and the emissivity of the object. Currently, there are three main ways to achieve infrared stealth: first, thermal insulation materials can be used to block the transfer of heat; second, a layer of low-emissivity material can be applied to the surface of the object; finally, thermal insulation materials and low-emissivity materials can be combined for use. The recently much-anticipated two-dimensional sheet material MXene is a low-emissivity material with an emissivity as low as 0.2 to 0.4. This material can effectively weaken the thermal radiation characteristics of the object, making the object more naturally blend into the surrounding environment. In addition, the high electrical conductivity of MXene can also cause strong conductive losses, thereby dissipating electromagnetic waves.

[0005] A preparation method of stealth fabric with radar stealth and infrared stealth dual functions is disclosed in Chinese patent CN104060474A. Polyaniline is successfully attached to the fabric by using the principle of electrostatic adsorption. Meanwhile, by coating heat preservation capsules and low emissivity powder on the surface of the composite fabric, compatible stealth function is achieved. A radar and infrared stealth integrated composite canopy cloth and its preparation method are disclosed in Chinese patent CN104990459A. The radar stealth effect is achieved by using the in-situ polymerization technology of silicon carbide fiber cloth and polyaniline. Then, ITO is sprayed on the surface of the material to enhance the infrared stealth performance. A novel infrared and radar integrated stealth fabric and its preparation method are disclosed in Chinese patent CN101995187A. Another strategy is adopted. Fabrics with different functions are prepared in sequence, and these fabrics are sewn in a specific order to create a multifunctional fabric. It is worth noting that the research on using MXene to prepare an infrared stealth layer is relatively rare at present. Most of the fabrics that realize infrared and radar dual-band stealth adopt the method of sewing multiple layers of fabric, which makes the overall thickness of the fabric larger. However, this method has a problem, that is, the infrared stealth layer on the surface will adversely affect the overall radar stealth performance of the fabric. Moreover, the actual stealth effect of these fabrics is not very ideal. SUMMARY

[0006] The present application overcomes the shortcomings of the prior art and provides a preparation method of infrared and radar stealth fabric.

[0007] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: a preparation method of infrared and radar stealth fabric, comprising the following steps:

[0008] S1, immerse the fabric in anhydrous ethanol under ultrasonic, wash with water, and immerse in an alkaline solution, wash with water and dry to obtain a pretreated fabric;

[0009] S2, mix a certain amount of wave-absorbing powder with coating glue, add a thickening agent to prepare coating slurry, apply the coating slurry on the pretreated fabric, and dry to obtain a composite fabric;

[0010] S3, etch the MAX phase material to obtain a MXene dispersion liquid;

[0011] S4, apply a layer of coating glue on the composite fabric, apply the MXene dispersion liquid, and dry in a vacuum environment. Repeat the coating 1-3 times to obtain MXene / wave-absorbing powder / fabric.

[0012] In a preferred embodiment of the present application, in the step S1, the fabric is one of cellulose fiber fabric, protein fiber fabric, polyester fabric, nylon fabric or aramid fabric; the thickness of the fabric is 0.3-0.6mm.

[0013] In a preferred embodiment of the present application, in the step S1, the ultrasonic immersion uses an ultrasonic cleaner, the rated power is 1200w, the immersion ultrasonic power is 5-30%, and the time is 5-30min.

[0014] In a preferred embodiment of the present application, in the step S1, the alkaline solution is one of sodium hydroxide or potassium hydroxide; the concentration of the alkaline solution is 10-20g / L, and the soaking time is 4-12h.

[0015] In a preferred embodiment of the present application, in the step S2, the wave-absorbing powder is one of Fe3O4, Co, Ni or Fe; the thickening agent is one of alginic acid, sodium carboxymethyl cellulose or starch.

[0016] In a preferred embodiment of the present application, in the step S2, in the coating slurry, the proportion of the wave-absorbing powder is 20-40%, the proportion of the coating glue is 57-78%, and the proportion of the thickening agent is 2-3%.

[0017] In a preferred embodiment of the present application, in the step S3, the MXene is etched by one of HF, NH4HF2 or LiF+HCl2; the MXene is one of Ti3AlC2, Ti3C2T x , Ti2CT x , Ti3CNT x or V2CT x .

[0018] In a preferred embodiment of the present application, in the step S4, the amount of the MXene dispersion liquid is 0.2-0.8mg / cm 2 .

[0019] In a preferred embodiment of the present application, in the step S4, the drying temperature is 70-90℃, and the treatment time is 2-4h.

[0020] In a preferred embodiment of the present application, in the steps S2 and S4, the coating glue is one of acrylic coating glue or polyurethane coating glue.

[0021] The present application solves the defects in the background art, and has the following beneficial effects:

[0022] (1) The application provides a preparation method of an infrared and radar stealth fabric, which forms a radar stealth layer by using wave-absorbing powder, and ensures that MXene forms a stable and continuous film by coating polyurethane coating glue or acrylic coating glue and then coating MXene, so as to reduce the emissivity and realize infrared stealth, that is, to avoid damage to the integrity of MXene structure caused by traditional mixed coating, and to balance the low infrared emissivity and radar wave absorption performance by accurately controlling the amount of MXene, wherein the composite fabric prepared by the application has an RL min of-18.43 dB in the frequency band of 8-18 GHz, and the surface temperature difference on the hot stage at 40 DEG C and 100 DEG C is significantly lower than the temperature of the hot stage, realizing high-performance infrared and radar dual-band stealth.

[0023] (2) In the application, the synergistic effect of the appropriate amount of Fe3O4 and MXene can realize excellent performance of infrared and radar dual-band stealth, the mixed valence of Fe2+ and Fe3+ exists in the crystal structure of Fe3O4, which can cause interface polarization and electron transition in the electromagnetic field, and produce significant dielectric loss, the magnetic properties of Fe3O4 can convert electromagnetic wave energy into heat energy through magnetic loss, and the coating glue in the wave-absorbing powder slurry physically wraps the wave-absorbing powder particles to form a uniform dispersion system, reduces particle agglomeration, and adjusts the dielectric constant and magnetic permeability of the coating to optimize the impedance matching with the MXene layer and improve the overall performance.

[0024] (3) In the application, the MXene layer and the wave-absorbing powder composite layer are formed, the dielectric constant of the MXene layer can be controlled by the coating glue and the thickening agent to make the impedance close to that of the free space, thereby reducing the reflection of electromagnetic waves on the surface, making the electromagnetic waves enter the MXene layer through conductive loss absorption, and the residual electromagnetic waves enter the wave-absorbing layer to consume energy through the dielectric loss and magnetic loss of Fe3O4, so that the composite fabric has excellent radar stealth effect.

[0025] (4) In the application, the pretreatment of the suitable concentration of alkaline solution enhances the surface polarity of the fabric, the wave-absorbing powder particles are more uniformly dispersed in the coating glue through electrostatic adsorption and chemical bonding, and the agglomeration is reduced, the uniformly distributed wave-absorbing particles can form a continuous energy loss network to improve the overall wave-absorbing efficiency, and the rough surface and the microporous structure formed by the thickening agent cooperate to prolong the electromagnetic wave propagation path. At the same time, it is beneficial to the adhesion of MXene nanosheets and the formation of conductive network, thereby improving the electromagnetic wave absorption performance of the fabric, the low emissivity of the MXene film and the electromagnetic wave absorption characteristics of the wave-absorbing layer are combined to realize the dual compatibility of infrared and radar stealth. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced. Obviously, the accompanying drawings in the following description only represent some embodiments of the present application, and all other drawings obtained by those of ordinary skill in the art without creative effort based on these drawings also belong to the protection scope of the present application.

[0027] Figure 1 is the infrared image of MXene / absorbing powder / fabric-1 on the hot stage at 40℃ and 100℃ respectively in the embodiment 1 of the present application;

[0028] Figure 2 is the electromagnetic wave absorption performance diagram of MXene / absorbing powder / fabric-1 at 8-12GHz and 12-18GHz respectively in the embodiment 1 of the present application;

[0029] Figure 3 is the infrared image of MXene / absorbing powder / fabric-1 on the hot stage at 40℃ and 100℃ respectively in the embodiment 2 of the present application;

[0030] Figure 4 is the electromagnetic wave absorption performance diagram of MXene / absorbing powder / fabric-1 at 8-12GHz and 12-18GHz respectively in the embodiment 2 of the present application;

[0031] Figure 5 is the infrared image of MXene / absorbing powder / fabric-1 on the hot stage at 40℃ and 100℃ respectively in the embodiment 3 of the present application;

[0032] Figure 6 is the electromagnetic wave absorption performance diagram of MXene / absorbing powder / fabric-1 at 8-12GHz and 12-18GHz respectively in the embodiment 3 of the present application. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be described clearly and completely below with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0034] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, however, the present application can be practiced in other manners different from those described herein, therefore, the protection scope of the present application is not limited by the specific embodiments disclosed below.

[0035] It should be noted that: the raw materials, equipment and reagents used in the present application can be purchased from the market or prepared by the existing technology.

[0036] A preparation method of an infrared and radar stealth fabric, comprising the following steps:

[0037] S1, the fabric is immersed in anhydrous ethanol by ultrasonic, washed with water, and immersed in an alkaline solution, washed with water and dried to obtain a pretreated fabric;

[0038] S2, a certain amount of wave-absorbing powder is mixed with coating glue, and a thickening agent is added to prepare a coating slurry, which is coated on the pretreated fabric and dried to obtain a composite fabric;

[0039] S3, etching MAX phase material to obtain MXene dispersion;

[0040] S4, coating a layer of coating glue on the composite fabric, coating MXene dispersion, and drying in a vacuum environment, repeating 1-3 times to obtain MXene / wave-absorbing powder / fabric.

[0041] In some specific embodiments, in the step of S1, the fabric is one of cellulose fiber fabric, protein fiber fabric, polyester fabric, nylon fabric or aramid fabric; the thickness of the fabric is 0.3-0.6mm.

[0042] In some specific embodiments, in the step of S1, the ultrasonic immersion uses an ultrasonic cleaner, the rated power is 1200w, the immersion ultrasonic power is 5-30%, and the time is 5-30min.

[0043] In some specific embodiments, in the step of S1, the alkaline solution is one of sodium hydroxide (NaOH) or potassium hydroxide (KOH); the concentration of the alkaline solution is 10-20g / L, and the soaking time is 4-12h.

[0044] In some specific embodiments, in the step of S2, the wave-absorbing powder is one of Fe3O4, Co, Ni or Fe; the thickening agent is one of alginic acid, sodium carboxymethyl cellulose or starch.

[0045] In some specific embodiments, in the step of S2, in the coating slurry, the proportion of wave-absorbing powder is 20-40%, the proportion of coating glue is 57-78%, and the proportion of thickening agent is 2-3%.

[0046] In some specific embodiments, in the step of S3, MXene is etched by one of HF, NH4HF2 or LiF+HCl2; MXene is Ti3AlC2, Ti3C2T x , Ti2CTx Ti3C2T x or V2C x .

[0047] MAX phase is a kind of layered structure material with the composition of Mn+1AXn (M is an early transition metal, A is a group IIIA or IV A element, and X is carbon or nitrogen). The name of MXene is derived from MAX phase, in which 'M' represents an early transition metal, 'X' represents carbon or nitrogen, and 'ene' indicates that it is a two-dimensional material. Since the M-X bond has a strong bond energy, and the A element has a relatively active chemical activity, the A element can be removed from the MAX phase by etching process, thereby obtaining a two-dimensional structure like graphene-MXene.

[0048] In some specific embodiments, in the step of S4, the amount of the MXene dispersion liquid is 0.2-0.8 mg / cm 2 .

[0049] In some specific embodiments, in the step of S4, the temperature for drying is 70-90℃, and the treatment time is 2-4h.

[0050] In some specific embodiments, in the steps of S2 and S4, the coating glue is one of acrylic coating glue or polyurethane coating glue.

[0051] In order to make the purpose and effect of the present application simple and easy to understand, the present application is further described in combination with the following specific examples and comparative examples.

[0052] Example 1

[0053] A preparation method of an infrared and radar stealth fabric, comprising the following steps:

[0054] S1, a cotton fabric with a thickness of 0.3mm is treated with ultrasonic in anhydrous ethanol at an ultrasonic power of 10% for 20min, and then washed with water. Subsequently, the fabric is immersed in a NaOH solution with a concentration of 15g / L for 8h, washed with water and dried to obtain a pretreated cotton fabric;

[0055] S2, a coating slurry is prepared by mixing Fe3O4 at a proportion of 35%, water-based polyurethane coating glue at a proportion of 63%, and alginic acid at a proportion of 2%. The coating slurry is uniformly coated on the surface of the pretreated cotton fabric, and then dried to prepare a radar stealth layer with a thickness of 0.1mm to obtain a composite cotton fabric.

[0056] S3. Pour 20 mL of 9 M HCl solution into a polytetrafluoroethylene beaker, weigh 1.6 g of LiF and add it to the beaker. Stir for 5 min to obtain an etching solution. Slowly add 1 g of Ti3AlC2 powder to the etching solution in multiple batches. Continue the reaction at 38 °C (with magnetic stirring) for 48 h. After the reaction is complete, the multilayer MXene dispersion obtained is washed by centrifugation in water multiple times until the pH is 7. Finally, sonicate the multilayer MXene dispersion for 60 min and centrifuge for 30 min to obtain a few-layer MXene dispersion with a concentration of 4 g / mL.

[0057] S4. First, form a radar stealth layer on the surface of the composite cotton fabric, then apply a layer of polyurethane coating adhesive, and then quickly apply MXene dispersion at a concentration of 0.5 mg / cm³. 2 Then, it was dried at 80°C for 4 hours to obtain MXene / absorbing powder / fabric-1 (coating thickness 0.21 mm).

[0058] like Figure 1 As shown, the MXene / absorbing powder / fabric-1 obtained in Example 1 was placed on hot stages at 40°C and 100°C (ambient temperature 22°C). Infrared thermal imager detection (operating frequency band 8-14µm) showed that the fabric surface temperatures were only 26.9°C and 40.6°C, respectively. Figure 2 As shown, the electromagnetic wave absorption performance of MXene / absorbing powder / fabric-1 was tested using a vector network analyzer. The results show that the minimum reflection loss (RL) is achieved. min It reached -13.9dB.

[0059] Example 2

[0060] This embodiment is basically the same as Embodiment 1, except that: Step S4 is as follows: first, a radar stealth layer is applied to the surface of the composite cotton fabric, then a layer of polyurethane coating adhesive is applied, and then MXene dispersion is quickly applied. The amount of MXene dispersion is 0.5 mg / cm³. 2 Then, it was dried at 80°C for 4 hours, and the coating was repeated a second time to obtain MXene / absorbing powder / fabric-2 (coating thickness 0.22mm).

[0061] like Figure 3 As shown, the MXene / absorbing powder / fabric-2 obtained in Example 2 was placed on hot stages at 40°C and 100°C (ambient temperature 22°C). Infrared thermal imager detection (operating frequency band 8-14µm) showed that the fabric surface temperature was only 26.8°C and 39.8°C, respectively. Figure 4 As shown, the electromagnetic wave absorption performance of MXene / absorbing powder / fabric-2 was tested using a vector network analyzer. The results show that RL min-18.43dB.

[0062] Example 3

[0063] This example is basically the same as Example 1, the difference is that the step S4 is: on the radar stealth layer of the composite cotton fabric, a layer of polyurethane coating is coated again, then MXene dispersion liquid is quickly coated, the amount of MXene dispersion liquid is 0.5mg / cm 2 , then dried at 80℃ for 4h, and coated for the third time to obtain MXene / absorbing powder / fabric-3 (coating thickness 0.23mm).

[0064] As shown in Figure 5 , the MXene / absorbing powder / fabric-3 obtained in Example 3 is placed on the hot stage at 40℃ and 100℃ (ambient temperature 22℃), and detected by an infrared thermal imager (working frequency band 8-14um), the results show that the surface temperature of the fabric is only 26.0℃ and 38.3℃ respectively; as shown in Figure 6 , the electromagnetic wave absorption performance of MXene / absorbing powder / fabric-3 is tested by a vector network analyzer, the results show that RL min reaches-13.46dB.

[0065] From the infrared and radar dual-band stealth performance test results of Examples 1-3, it can be seen that by using the absorbing powder to form a radar stealth layer, and then coating MXene after coating a polyurethane coating glue, the present application ensures that MXene forms a stable and continuous film, reduces the emissivity to achieve infrared stealth, that is, avoids the damage to the integrity of MXene structure caused by traditional mixed coating, and balances the low infrared emissivity and radar wave absorption performance by accurately controlling the amount of MXene, finally, the composite fabric has RL min of-18.43dB in the frequency band of 8-18GHz, and the surface temperature difference is significantly lower than the temperature of the hot stage at 40℃ and 100℃, realizing high-performance infrared and radar dual-band stealth.

[0066] Meanwhile, in Example 3, compared with Example 2, the coating of the MXene layer is repeated once more, although the thickness of the coating increases, the low emissivity characteristic is more significant, further inhibiting heat radiation, and the infrared stealth effect is slightly better than that of Example 2, but the electromagnetic wave absorption performance has decreased to a certain extent, because with the increase of the thickness of the MXene layer, a continuous film similar to metal is formed, which is easy to reflect part of the radar wave instead of absorbing, weakening the loss effect of the absorbing powder layer, so that the electromagnetic wave absorption performance decreases.

[0067] In order to further illustrate the present application, the optimal Example 2 is used as a basis for comparison.

[0068] Comparative Example 1

[0069] The comparative example is basically the same as example 2, the difference is that there is no S2 step, and the step of S4 is: first apply a layer of polyurethane coating glue on the surface of the pretreated cotton fabric, then quickly apply MXene dispersion liquid, the amount of MXene dispersion liquid is 0.5 mg / cm 2 , then dry at a temperature of 80℃ for 4h, and repeat the second coating to obtain MXene / fabric-2.1 (coating thickness 0.21mm).

[0070] Comparative example 2

[0071] The comparative example is basically the same as example 2, the difference is that in the S2 step, the proportion of Fe3O4 in the coating slurry is 18%, the proportion of water-based polyurethane coating glue is 80%, and the proportion of alginic acid is 2%; MXene / absorbing powder / fabric-2.2 (coating thickness 0.22mm) is obtained.

[0072] Comparative example 3

[0073] The comparative example is basically the same as example 2, the difference is that in the S2 step, the proportion of Fe3O4 in the coating slurry is 44%, the proportion of water-based polyurethane coating glue is 54%, and the proportion of alginic acid is 2%; MXene / absorbing powder / fabric-2.3 (coating thickness 0.22mm) is obtained.

[0074] Comparative example 4

[0075] The comparative example is basically the same as example 2, the difference is that the preparation of the MXene layer is carried out first, and then the preparation of the radar stealth layer is carried out, which specifically includes the following steps:

[0076] S1, the cotton fabric with a thickness of 0.3mm is treated with ultrasonic in anhydrous ethanol for 20min at an ultrasonic power of 10%, then washed with water, and then the fabric is immersed in a NaOH solution with a concentration of 15g / L for 8h, washed with water and dried to obtain a pretreated cotton fabric;

[0077] S2, 20mL of 9M HCl solution is poured into a polytetrafluoroethylene beaker, 1.6g of LiF is weighed and added into the beaker, stirred for 5min to obtain an etching solution, 1g of Ti3AlC2 powder is slowly added into the etching solution for multiple times, and the reaction is continued at a temperature of 38℃ (with magnetic stirring) for 48h, then the multilayer MXene dispersion obtained after the reaction is washed in water for multiple times until the pH is 7, finally the multilayer MXene dispersion is ultrasonic treated for 60min and centrifuged for 30min to obtain a few-layer MXene dispersion liquid with a concentration of 4g / mL;

[0078] S3, on the surface of the pretreated cotton fabric, first apply a layer of polyurethane coating glue, then quickly apply MXene dispersion liquid, the amount of MXene dispersion liquid is 0.5 mg / cm 2 , then dry at a temperature of 80℃ for 4h, repeat the second time to get MXene / fabric;

[0079] S4, configure the coating slurry with Fe3O4 accounting for 35%, water-based polyurethane coating glue accounting for 63%, and alginate accounting for 2%, uniformly apply the coating slurry on the surface of MXene / fabric, dry to prepare a radar stealth layer with a thickness of 0.1mm, to obtain MXene / absorbing powder / fabric-2.4 (coating thickness 0.22mm).

[0080] Comparative Example 5

[0081] This comparative example is basically the same as Example 2, the difference is that there is no alkaline treatment, the step S1 is: the cotton fabric with a thickness of 0.3mm is treated in anhydrous ethanol with an ultrasonic power of 10% for 20min, then washed with water and dried to obtain the pretreated cotton fabric; MXene / absorbing powder / fabric-2.5 (coating thickness 0.22mm) is obtained.

[0082] Comparative Example 6

[0083] This comparative example is basically the same as Example 2, the difference is that in the step S1, the concentration of NaOH solution is 8g / L; MXene / absorbing powder / fabric-2.6 (coating thickness 0.22mm) is obtained.

[0084] Comparative Example 7

[0085] This comparative example is basically the same as Example 2, the difference is that in the step S1, the concentration of NaOH solution is 23g / L; MXene / absorbing powder / fabric-2.7 (coating thickness 0.22mm) is obtained.

[0086] Performance detection: the MXene / absorbing powder / fabric obtained in Comparative Examples 1-7 is tested for surface temperature using an infrared thermal imager (working frequency band 8-14um) on a hot stage at 40℃ and 100℃ (ambient temperature 22℃), and the minimum reflection loss of MXene / absorbing powder / fabric is tested by a vector network analyzer at 8-18GHz, and compared with Example 2, the results are shown in Table 1.

[0087] Table 1: Infrared and radar dual-band stealth performance test results

[0088]

[0089]

[0090] As shown in Table 1:

[0091] It can be seen from the comparison of Example 2 and Comparative Example 1 that the absence of wave-absorbing powder results in the overall degradation of the dual-band stealth performance in the infrared and radar bands. The mixed valence of Fe2+ and Fe3+ in the crystal structure of the wave-absorbing powder (Fe3O4) can induce interfacial polarization and electronic transition in the electromagnetic field, resulting in significant dielectric loss. The magnetic properties of Fe3O4, such as magnetic domain motion and magnetic hysteresis, can convert electromagnetic wave energy into heat energy through magnetic loss. If the wave-absorbing powder is absent, the coating cannot form an effective dielectric-magnetic synergistic loss mechanism, resulting in a significant decrease in radar stealth performance. The coating glue (polyurethane) in the wave-absorbing powder slurry physically wraps the wave-absorbing powder particles, forming a uniform dispersion system, reducing particle agglomeration, and allowing the wave-absorbing powder to form a continuous and dense wave-absorbing layer on the fabric, maintaining the high-efficiency working state of the wave-absorbing material. The dielectric constant and magnetic permeability of the coating can be adjusted to optimize impedance matching. If the wave-absorbing powder layer is absent, the high electrical conductivity of MXene will directly form a highly reflective interface with the fabric substrate, causing most of the electromagnetic waves to be reflected back into the air, destroying its electromagnetic wave absorption properties.

[0092] It can be seen from the comparison of Example 2 and Comparative Example 2 and Comparative Example 3 that the synergistic effect of the appropriate amount of wave-absorbing powder (Fe3O4) and MXene can achieve excellent performance in the infrared and radar dual-band stealth. When the amount of wave-absorbing powder is too low, the mixed valence of Fe2+ and Fe3+ in the Fe3O4 crystal cannot form a continuous electronic transition path, resulting in interfacial polarization and magnetic hysteresis loss. The wave-absorbing powder is dispersed sparsely in the coating glue, and cannot form a conductive path through tunneling effect, making it difficult for electromagnetic wave energy to dissipate through Ohmic loss. At the same time, it cannot provide sufficient support for MXene nanosheets, which may spontaneously agglomerate due to van der Waals forces, resulting in a decrease in film continuity. When the amount of Fe3O4 particles is excessive, the coating magnetic loss dominates, and the impedance mismatch with the MXene layer increases the reflectivity of electromagnetic waves at the interface. At the same time, due to the magnetic dipole interaction, micron-sized agglomerates are formed, exciting eddy current loss and causing a sharp decrease in high-frequency wave-absorbing performance.

[0093] It can be seen from the comparison of Example 2 and Comparative Example 4 that the MXene layer and the wave-absorbing powder (Fe3O4) layer form a composite layer, the dielectric constant of the MXene layer can be regulated by the coating glue and the thickening agent to approach the impedance of the free space, thereby reducing the reflection of electromagnetic waves on the surface, and the electromagnetic waves first enter the MXene layer and are absorbed by the electromagnetic waves through conductive loss (free electron oscillation). The residual waves then enter the wave-absorbing powder layer, and the dielectric loss and magnetic loss of Fe3O4 consume energy. If there is only a MXene layer, its impedance is much lower than that of the free space, resulting in the reflection of most electromagnetic waves at the interface. The high conductivity of MXene causes the electromagnetic waves to be reflected on the surface, and the wave-absorbing layer cannot effectively play a role, thereby significantly reducing the overall absorption performance.

[0094] It can be seen from the comparison of Example 2 and Comparative Example 5 that by using an alkaline solution to pretreat the fabric, the non-polar groups (such as ester groups and ether bonds) on the surface of the fabric fibers can be destroyed by a hydrolysis reaction to generate polar functional groups such as hydroxyl groups (-OH) or carboxylate groups (-COO-), thereby enhancing the hydrophilicity of the fabric surface, providing more active sites for the attachment of the wave-absorbing powder and MXene, and forming a micron-level rough structure by partially dissolving the fiber surface, which can increase the contact area between the wave-absorbing powder and the fabric, reduce interface reflection, and prolong the propagation path of electromagnetic waves in the wave-absorbing layer, thereby improving the infrared stealth, dielectric loss, and magnetic loss efficiency.

[0095] It can be seen from the comparison of Example 2 and Comparative Examples 6 and 7 that when the concentration of the alkaline solution is too low or too high, impurities on the surface of the fabric cannot be sufficiently removed, or the fiber structure of the fabric is excessively damaged, resulting in insufficient adhesion of the wave-absorbing powder layer and MXene to the fabric, and being not conducive to the formation of a uniform functional layer, which affects the infrared stealth and electromagnetic wave absorption effect. By pretreating the fabric with an alkaline solution of an appropriate concentration, the polarity of the fabric surface is enhanced, the wave-absorbing powder particles are more uniformly dispersed in the coating glue through electrostatic adsorption and chemical bonding, and the agglomeration is reduced. The uniformly distributed wave-absorbing particles can form a continuous energy loss network, thereby improving the overall wave-absorbing efficiency, and the rough surface introduced cooperates with the microporous structure formed by the thickening agent to prolong the propagation path of electromagnetic waves. At the same time, it is conducive to the adhesion of MXene nanosheets and the formation of a conductive network, thereby improving the electromagnetic wave absorption performance of the fabric. The low emissivity of the MXene film and the wideband absorption characteristics of the wave-absorbing layer are combined to achieve dual compatibility of infrared and radar stealth.

[0096] The above is based on the ideal embodiment of the present application, through the above description, for those skilled in the art, it is obvious that the present application is not limited to the details of the above exemplary embodiments, and the present application can be realized in other specific forms without departing from the spirit or basic characteristics of the present application. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-limiting, the scope of the present application is defined by the appended claims rather than the above description, therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application. Any reference signs in the claims should not be regarded as limiting the claims involved.

[0097] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A method for preparing an infrared and radar stealth fabric, characterized in that, Includes the following steps: S1. The fabric is ultrasonically impregnated in anhydrous ethanol, washed with water, soaked in an alkaline solution, washed with water and dried to obtain a pretreated fabric; the fabric is one of cellulose fiber fabric, protein fiber fabric, polyester fabric, nylon fabric or aramid fabric. The concentration of the alkaline solution is 10~20 g / L; S2. A certain amount of microwave absorbing powder is mixed with coating adhesive, and a thickener is added to prepare a coating slurry. This slurry is then coated onto the pretreated fabric and dried to obtain a composite fabric. In the coating slurry, the microwave absorbing powder accounts for 20-40%, the coating adhesive accounts for 57-78%, and the thickener accounts for 2-3%. The microwave absorbing powder is Fe3O4. S3. Etch the MAX phase material to obtain an MXene dispersion; S4. Coat the composite fabric with a coating adhesive, then coat with MXene dispersion, and dry under vacuum. Repeat the coating process 1-3 times to obtain MXene / microwave absorbing powder / fabric; the amount of MXene dispersion is 0.2-0.8 mg / cm³. 2 .

2. The method for preparing an infrared and radar stealth fabric according to claim 1, characterized in that: In step S1, the thickness of the fabric is 0.3~0.6 mm.

3. The method for preparing an infrared and radar stealth fabric according to claim 1, characterized in that: In step S1, the ultrasonic impregnation uses an ultrasonic cleaner with a rated power of 1200W, the ultrasonic power of the impregnation is 5-30% of the rated power, and the time is 5-30 minutes.

4. The method for preparing an infrared and radar stealth fabric according to claim 1, characterized in that: In step S1, the alkaline solution is either sodium hydroxide or potassium hydroxide; the soaking time is 4-12 hours.

5. The method for preparing an infrared and radar stealth fabric according to claim 1, characterized in that: In step S2, the thickener is one of alginate, sodium carboxymethyl cellulose, or starch.

6. The method for preparing an infrared and radar stealth fabric according to claim 1, characterized in that: In step S3, the MXene is etched using one of HF, NH4HF2, or LiF+HCl2; the MXene is Ti3AlC2 or Ti3C2T. x Ti2CT x Ti3CNT x or V2CT x One of them.

7. The method for preparing an infrared and radar stealth fabric according to claim 1, characterized in that: In step S4, the drying temperature is 70~90 ℃ and the processing time is 2~4 h.

8. The method for preparing an infrared and radar stealth fabric according to claim 1, characterized in that: In steps S2 and S4, the coating adhesive is either an acrylic coating adhesive or a polyurethane coating adhesive.

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