A composite stealth coating resistant to harsh environments, its preparation method and applications

Abstract

The present invention relates to a composite stealth coating resistant to harsh environments, a preparation method and an application thereof, comprising the following steps: preparing a slurry required for preparing magnetite / carbon composite microspheres; preparing microsphere precursors; preparing fiber-magnetite / carbon microsphere composites; preparing a stealth absorbing coating containing magnetite / carbon composite microspheres; sequentially coating a mixed solution of a binder, a stealth absorbing coating and a curing agent on a substrate, then laying the fiber-magnetite / carbon microsphere composites flat on the surface of the coating, and after curing, obtaining a composite stealth coating on the surface of the substrate. Compared with the prior art, the present invention ensures high absorption efficiency while having stable stealth performance, flexible structure regulation, high temperature resistance, high humidity resistance and high corrosion resistance, and is suitable for applications in marine environment equipment.

Description

Technical Field

[0001] The present invention relates to the field of stealth materials, and particularly to a composite stealth coating resistant to harsh environments, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of information technology and the ever-changing war environment, the emergence of stealth detection technology has had a profound impact on modern weaponry. The development and application of various stealth detection technologies pose a serious threat to the survival of aircraft, ships, and various weaponry, becoming the main means of capturing information and target detection in the information-based electronic warfare in the new century. According to the current actual environment and detection technology, stealth detection is mainly achieved through channels such as radar waves, infrared signals, and sound waves. Therefore, reducing the radar echo intensity, weakening the infrared radiation, and reducing noise are the main methods to make equipment achieve stealth. In modern stealth technology, reducing the detectability of a target is mainly achieved by changing the appearance design and preparing a stealth coating on the surface. However, restricted by the usage conditions and environment, improving the shape is often difficult, costly, and prone to increasing additional mass, thereby reducing its comprehensive performance. Performance and shape design usually cannot meet the requirements simultaneously, while the stealth coating can just make up for this deficiency. The preparation of stealth coating materials is relatively simple, the construction is convenient, the design selectivity is strong, and the cost is relatively low.

[0003] Stealth coating materials are widely used in many aspects such as national defense, military, and civilian applications in China, and can play a key role in radar stealth technology, information leakage protection, etc. Currently, its main application fields are still concentrated on ground and air equipment. With the continuous development of China's maritime equipment technology, the demand for stealth coating materials for many maritime equipment such as Chinese naval ships and mass transfer is increasing. However, due to the significant difference between the marine environment and the application environments on the ground and in the air, current conventional stealth coating materials prepared with carbonyl iron powder as the absorber often fail to meet the requirements for long-term use in the marine environment of high temperature, high humidity, high corrosion, and strong light, which can lead to rusting, sagging, and peeling of the stealth coating materials. For example, the invention patent with the application number CN202211326831.9 discloses a coating material that improves the flexibility and impact resistance of the coating through a combined structure of alloy-plated glass flakes and carbonyl iron powder, and the invention patent with the application number CN202310345108.3 discloses a wave-absorbing material that adjusts the coating thickness by compounding an absorber with graphene. These currently studied wave-absorbing coating materials only focus on optimizing traditional indicators such as thickness and strength, and lack consideration of relevant influencing factors for application in the special marine environment.

[0004] In addition, the currently commonly used stealth coating materials have relatively single performance, and the material structure cannot be flexibly regulated. They often adopt single components and single structures, and can only meet a single stealth and wave absorption function. For example, the invention patent with the application number CN202110910391.0 discloses a preparation method for fine-tuning the coating performance and double-layer structure through the filling ratio, modification, and coating thickness design of magnetic absorbents. The regulation effect of its related technology is very limited, and it still cannot take into account the multi-scenario use requirements such as wide frequency band, multi-field stealth, and comprehensive mechanical properties, and it is difficult to meet the requirements for the compounding and diversification of stealth coating materials in the marine environment. Summary of the Invention

[0005] An object of the present invention is to provide a composite stealth coating resistant to harsh environments, its preparation method and application, in order to overcome at least one of the defects existing in the above-mentioned prior art. While ensuring high wave absorption efficiency, this composite stealth coating has stable stealth performance, a flexibly adjustable structure, high temperature resistance, high humidity resistance, and high corrosion resistance, and is suitable for applications in marine environment equipment.

[0006] The object of the present invention can be achieved through the following technical solutions:

[0007] One of the objects of the present invention is a preparation method for a composite stealth coating resistant to harsh environments, including the following steps:

[0008] S1. Add iron oxide black powder to an organic solvent, disperse it evenly to form a uniform and stable suspension; then add a polymer, heat and stir evenly, cool to room temperature, and degas to obtain the slurry required for preparing iron oxide black / carbon composite microspheres.

[0009] S2. The slurry is dispersed into droplets by electrospray, and the droplets are immersed in a coagulation bath to form microsphere precursors; the precursors are impregnated in the coagulation bath, and after sufficient phase transformation, they are filtered out from the coagulation bath and dried to obtain microsphere precursors.

[0010] S3. Disperse the microsphere precursors in a non-organic solvent, disperse them evenly to form a uniform and stable suspension; arrange carbon fibers in the suspension, fully impregnate them, take them out, dry and sinter them to obtain fiber-iron oxide black / carbon microsphere composites.

[0011] S4. Sinter the microsphere precursors to obtain iron oxide black / carbon composite microspheres; add the iron oxide black / carbon composite microspheres to a mixed solution of an organic film-forming agent and a diluent, stir evenly to obtain a stealth wave-absorbing coating.

[0012] S5. Coating a mixed solution of an adhesive, a stealth wave-absorbing coating, and a curing agent on the substrate in sequence, then laying the fiber-iron oxide black / carbon microsphere composite flat on the surface of the coating, and after curing, a composite stealth coating is obtained on the surface of the substrate.

[0013] Among them, the order of S3 and S4 does not require S3 to be carried out before S4. The two can be carried out simultaneously, or S3 can be before S4 or S4 can be before S3.

[0014] In an embodiment of the present invention, by weight parts, the composite stealth coating comprises:

[0015]

[0016] In an embodiment of the present invention:

[0017] The organic film-forming agent is silicone rubber, preferably 107 silicone rubber;

[0018] The curing agent is bis(2,4-dichlorobenzoyl) peroxide;

[0019] The ferric ferrosoferric oxide powder is in powder form, with a particle size of 25 - 75 nm, preferably 50 nm;

[0020] The diluent is 120# gasoline;

[0021] The organic solvent is N-methylpyrrolidone;

[0022] The polymer is powdered polyethersulfone or cellulose acetate, and there is no specific requirement for the particle size, preferably polyethersulfone;

[0023] The non-organic solvent is water, preferably deionized water;

[0024] The binder is a silane coupling agent, preferably KH550.

[0025] In an embodiment of the present invention, in S1:

[0026] The dispersion is ultrasonic dispersion, and the dispersion time is 10 - 30 min, preferably 20 min;

[0027] The heating and stirring is mechanical stirring with an oil bath, the stirring time is 6 - 18 h, the stirring speed is 300 - 400 r / min, preferably, the stirring time is 12 h and the stirring speed is 350 r / min;

[0028] The degassing is vacuum degassing treatment, and the degassing time is 20 - 40 min, preferably 30 min.

[0029] In an embodiment of the present invention, in S2:

[0030] The electrospraying specifically is as follows: injecting the slurry into a syringe of an electrospraying sphere-making system, the slurry being dispersed into droplets during electrospraying, and the droplets forming microsphere precursors after being immersed in a coagulation bath; the electrospraying voltage is 15 - 25 kV, the slurry flow rate is 2 - 4 ml / min, the electrospraying nozzle diameter is 0.5 - 1 mm, and the distance between the electrospraying nozzle and the coagulation bath is 8 - 12 cm; preferably, the electrospraying voltage is 20 kV, the slurry flow rate is 2 - 4 ml / min, the electrospraying nozzle diameter is 0.8 mm, and the distance between the electrospraying nozzle and the coagulation bath is 10 cm.

[0031] The impregnation time of the precursor in the coagulation bath is 12 - 36 h, preferably 24 h;

[0032] The drying is drying at room temperature, and the drying time is 24 - 72 h, preferably 48 h.

[0033] In an embodiment of the present invention, in S3:

[0034] The carbon fiber cloth is a carbon fiber cloth with surface oil removed and surface roughness increased;

[0035] The dispersion is ultrasonic dispersion, and the dispersion time is 10 - 30 min, preferably 20 min;

[0036] The sintering of the microsphere precursors specifically is as follows: placing the fully impregnated carbon fiber cloth in a crucible and sintering it in a muffle furnace in two stages. The sintering atmosphere is an inert atmosphere. The sintering temperature in the first stage is 500 - 700 °C, the sintering time is 8 - 12 h, the sintering temperature in the second stage is 1000 - 1400 °C, the sintering time is 1 - 3 h, and the heating and cooling rate is 3 - 6 °C / min. Preferably, the sintering temperature in the first stage is 600 °C, the sintering time is 10 h, the sintering temperature in the second stage is 1200 °C, the sintering time is 2 h, and the heating and cooling rate is 5 °C / min.

[0037] In an embodiment of the present invention, in S4, the sintering step of the microsphere precursors is the same as the sintering step in S3.

[0038] In an embodiment of the present invention, in S5, the curing time is 30 - 50 h, preferably 48 h.

[0039] Specifically, the preparation method of the composite stealth coating in the present invention includes the following steps:

[0040] (1) According to a certain ratio, add iron tetroxide powder to an organic solvent, and disperse it by ultrasonic waves to form a uniform and stable suspension. Subsequently, add polymer powder to the suspension, and conduct mechanical stirring in an oil bath. After the stirring is completed, let the obtained uniform slurry stand to room temperature, and then place it in a vacuum dryer for degassing treatment to remove the air mixed in during the stirring process, obtaining the slurry required for preparing the iron tetroxide / carbon composite microspheres.

[0041] (2) Inject the slurry into the syringe of the electrospraying system for spherical preparation. The slurry is dispersed into droplets during the electrospraying process, and the droplets form microsphere precursors after immersing in the coagulation bath. The precursors are impregnated in the coagulation bath, filtered out from the coagulation bath after sufficient phase transformation, and dried at room temperature to obtain the microsphere precursors.

[0042] (3) Cut the carbon fiber cloth with a preset weaving structure into appropriate sizes, conduct surface treatment on it, soak it in sodium hydroxide solution to remove the surface oil stains, and then acidify it with nitric acid and conduct ultrasonic treatment to increase its surface roughness, making it easy for the microspheres to adhere uniformly. Then mix a part of the microsphere precursors with a certain amount of non-organic solvent, stir ultrasonically to form a stable suspension, immerse it in the suspension, and continue ultrasonic treatment to make the solution fully impregnate into the carbon fiber cloth structure. Then take out the impregnated carbon fiber cloth, place it in an oven to dry and take it out.

[0043] (4) Place the impregnated fiber cloth in a corundum crucible and sinter it in a muffle furnace in two stages. The sintering atmosphere is nitrogen. During the sintering process, the organic matter pyrolyzes into carbon materials, and iron tetroxide / carbon composite microspheres are in-situ generated on the surface of the fiber cloth. After the sintering is completed, wait until it cools down to room temperature to obtain the fiber - iron tetroxide / carbon microsphere composite material.

[0044] (5) Take a certain amount of microsphere precursors and place them in a crucible for sintering. The sintering steps are the same as in (4) to obtain iron tetroxide / carbon composite microspheres. Pour the organic film-forming agent and diluent into the mixing tank according to the ratio, and continuously add an appropriate amount of microspheres during this period to mix evenly. After mixing, obtain a uniform stealth absorbing coating.

[0045] (6) After cleaning and treating the surface of the substrate, thinly coat a layer of binder. Then add an appropriate amount of curing agent to the evenly mixed absorbing coating and stir evenly. Then spray the coating evenly on the surface of the substrate. Then lay the fiber - iron tetroxide / carbon microsphere composite material flat on the surface of the coating and cure for a period of time. Wait until the silicone rubber cross-linking reaction is complete and at the same time the organic solvent completely volatilizes, and a composite stealth coating is obtained on the surface of the substrate.

[0046] The second object of the present invention is a composite stealth coating that can withstand harsh environments obtained by the preparation method as described above.

[0047] A third object of the present invention lies in the application of a composite stealth coating that can withstand harsh environments as described above. This composite stealth coating is applied to various corrosive environments such as acids and / or alkalis and / or salts, and is particularly suitable for special application scenarios such as marine environments.

[0048] Compared with the prior art, the present invention has the following advantages:

[0049] (1) In the present invention, composite absorbing material microspheres are in-situ generated on the surface of carbon fibers through processes such as electrospraying and sintering to obtain fiber-Fe₃O₄ / carbon microsphere composites. The magnetic components therein have high saturation magnetization intensity and high absorption rate. The carbon material components have characteristics such as high thermal stability, corrosion resistance, low density, and adjustable dielectric properties. Moreover, the fiber structure in which the fiber braids are mutually carried constructs a suitable attenuation space for electromagnetic waves. Therefore, this magnetic carbon-based absorbing material can greatly improve the wave-absorbing ability of the coating through its combined effects such as magnetic-dielectric double-loss mechanism and magnetoelectric synergy.

[0050] (2) The silicone rubber matrix in the present invention has excellent insulation properties. After adding conductive fillers (Fe₃O₄ / carbon microspheres), the composite material prepared has a wide range of conductivity regulation, high infrared transmittance, and high absorption rate of medium and low-frequency sound waves of the material itself.

[0051] (3) In the present invention, the composite material adopts a new research idea of integrated design of materials and structures. The internal porous structure of the composite material microspheres, the woven structure of the carbon fiber cloth, and the distribution structure of the silicone rubber intermediate layer absorbing microspheres can all be regulated. That is, the material microspheres can regulate the shape of the internal pores such as finger-shaped pores and spherical pores; the woven structure of the carbon fiber cloth can regulate the weaving density, weaving direction, weaving pattern, etc.; the distribution of the silicone rubber microspheres can adjust the distribution density of the microspheres, etc. It can design the electromagnetic properties of the coating in combination with different application scenarios, enabling the coating to have good impedance matching characteristics and electromagnetic wave absorption efficiency.

[0052] (4) The coating in the present invention is a multi-layer gradient structure absorbing coating. In addition to being able to achieve stealth detection protection, it also has excellent protection capabilities and service performance. The carbon fiber cloth matrix applied on the surface layer has many advantages such as high strength, high modulus, light self-weight, good durability, and corrosion resistance, which can further extend the service performance and life of the coating. The intermediate layer matrix is silicone rubber, which has a wide service temperature range, good compatibility with powders (Fe₃O₄ / carbon microspheres), oxidation resistance, and excellent service performance in various corrosive environments such as acids, alkalis, and salts, and is well-suited for special application scenarios such as marine environments. Description of the Drawings

[0053] Figure 1 Photographs of carbon fiber cloth with different woven structures on the surface layer of the coating in Example 1.

[0054] Figure 2Morphology photograph of the Fe₃O₄ / C composite microspheres (i.e., microwave absorbing microspheres) obtained in Example 1.

[0055] Figure 3 Electromagnetic parameter diagrams of the composite stealth coating and the coating without Fe₃O₄ / C microspheres in Example 1, where ε’ is the real part of the dielectric constant, ε” is the imaginary part of the dielectric constant, μ’ is the real part of the magnetic permeability, and μ” is the imaginary part of the magnetic permeability.

[0056] Figure 4 Experimental data diagram of the attenuation constant α of the composite stealth coating and the coating without Fe₃O₄ / C microspheres in Example 1. Specific implementation manners

[0057] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0058] A preparation method of a composite stealth coating resistant to harsh environments includes the following steps:

[0059] S1. Add ferric oxide powder into an organic solvent, disperse it evenly to form a uniform and stable suspension; then add a polymer, heat and stir evenly, cool to room temperature, and degas to obtain the slurry required for preparing Fe₃O₄ / C composite microspheres.

[0060] S2. The slurry is dispersed into droplets by electrospray, and the droplets are immersed in a coagulation bath to form microsphere precursors; the precursors are impregnated in the coagulation bath, and after sufficient phase conversion, they are filtered out from the coagulation bath and dried to obtain microsphere precursors.

[0061] S3. Disperse the microsphere precursors in a non-organic solvent, disperse them evenly to form a uniform and stable suspension; arrange carbon fibers in the suspension, fully impregnate them, take them out, dry and sinter them to obtain fiber-Fe₃O₄ / C microsphere composite materials.

[0062] S4. Sinter the microsphere precursors to obtain Fe₃O₄ / C composite microspheres; add the Fe₃O₄ / C composite microspheres into a mixed solution of an organic film-forming agent and a diluent, stir evenly to obtain a stealth microwave absorbing coating.

[0063] S5. Coating a mixed solution of a binder, a stealth microwave absorbing coating and a curing agent on the substrate in sequence, and then laying the fiber-Fe₃O₄ / C microsphere composite materials flat on the surface of the coating, and after curing, a composite stealth coating is obtained on the surface of the substrate.

[0064] Preferably, by weight, the composite stealth coating includes:

[0065]

[0066]

[0067] Preferably:

[0068] The organic film-forming agent is silicone rubber;

[0069] The curing agent is bis(2,4-dichlorobenzoyl) peroxide;

[0070] The iron tetroxide powder is in powder form with a particle size of 25 - 75 nm;

[0071] The diluent is 120# gasoline;

[0072] The organic solvent is N-methylpyrrolidone;

[0073] The polymer is polyethersulfone or cellulose acetate;

[0074] The non-organic solvent is water;

[0075] The binder is a silane coupling agent.

[0076] Preferably, in S1:

[0077] The dispersion is ultrasonic dispersion with a dispersion time of 10 - 30 min;

[0078] The heating and stirring is mechanical stirring with an oil bath, the stirring time is 6 - 18 h, and the stirring speed is 300 - 400 r / min;

[0079] The degassing is vacuum degassing treatment with a degassing time of 20 - 40 min.

[0080] Preferably, in S2:

[0081] The electrospraying specifically is: injecting the slurry into the syringe of the electrospraying system for forming spheres, the slurry is dispersed into droplets during electrospraying, and the droplets form microsphere precursors after immersing in the coagulation bath; the electrospraying voltage is 15 - 25 kV, the slurry flow rate is 2 - 4 ml / min, the electrospraying nozzle diameter is 0.5 - 1 mm, and the distance between the electrospraying nozzle and the coagulation bath is 8 - 12 cm;

[0082] The immersion time of the precursor in the coagulation bath is 12 - 36 h;

[0083] The drying is drying at room temperature with a drying time of 24 - 72 h.

[0084] Preferably, in S3:

[0085] The carbon fiber cloth is a carbon fiber cloth with the surface oil removed and surface roughness increased;

[0086] The dispersion is ultrasonic dispersion, and the dispersion time is 10 - 30 min;

[0087] The sintering of the microsphere precursor is specifically as follows: The fully impregnated carbon fiber is arranged in a crucible and sintered in a muffle furnace in two stages. The sintering atmosphere is an inert atmosphere. The sintering temperature in the first stage is 500 - 700 °C, the sintering time is 8 - 12 h, the sintering temperature in the second stage is 1000 - 1400 °C, the sintering time is 1 - 3 h, and the heating and cooling rate is 3 - 6 °C / min.

[0088] Preferably, in S4, the sintering step of the microsphere precursor is the same as the sintering step in S3.

[0089] Preferably, in S5, the curing time is 30 - 50 h.

[0090] Example 1

[0091] This example provides a composite silicone rubber stealth coating resistant to harsh environments, including the following raw material components in parts by weight;

[0092]

[0093] A method for preparing a composite silicone rubber stealth coating is as follows.

[0094] (1) Add 10 parts of iron tetroxide powder to 20 parts of N - methylpyrrolidone, and disperse ultrasonically for 20 min to form a uniform and stable suspension. Subsequently, add 2 parts of polyethersulfone powder to the suspension and perform mechanical stirring in an oil bath. The temperature of the oil bath is 50 °C, the stirring duration is 12 h, and the rotation speed of the stirring rod is 350 r / min. After stirring is completed, let the obtained uniform slurry stand to room temperature, and then place it in a vacuum dryer for degassing treatment for 30 min to remove the air mixed in during the stirring process, and obtain the slurry required for preparing the absorbing microspheres.

[0095] (2) Inject the slurry into the syringe of the electrospray spheronization system. The electrospray voltage is 20 kV, the slurry flow rate is 2 ml / min, the nozzle diameter is 0.8 mm, and the height from the nozzle to the coagulation bath is 10 cm. The slurry is dispersed into droplets during electrospray, and the droplets form ceramic microsphere precursors after immersing in the coagulation bath. The precursors are impregnated in the coagulation bath for 24 h, and after sufficient phase conversion, they are filtered out from the coagulation bath and dried at room temperature for 48 h.

[0096] (3) Cut the carbon fiber cloth with a preset weaving structure into an appropriate size, perform surface treatment on it, soak it in sodium hydroxide solution to remove surface oil stains, then acidify it with nitric acid, and ultrasonically treat it for 20 min to increase its surface roughness, which is conducive to the uniform attachment of microspheres. Then mix 5 parts of microsphere precursors with an appropriate amount of deionized water, ultrasonically stir to form a stable suspension, immerse it in the suspension, and continue ultrasonic treatment for 20 min to fully impregnate the solution into the fiber cloth structure. Then take out the impregnated fiber cloth, place it in an oven to dry, and then take it out.

[0097] (4) Place the impregnated fiber cloth in a corundum crucible and sinter it in a muffle furnace in two stages. The sintering atmosphere is nitrogen. The sintering temperature in the first stage is 600 °C, and the sintering time is 10 minutes. The sintering temperature in the second stage is 1200 °C, and the sintering time is 2 h. The heating and cooling rate is 5 °C / min. During the sintering process, the organic matter pyrolyzes into carbon materials, and Fe₃O₄ / C composite microspheres are in-situ generated on the surface of the fiber cloth, as shown in Figure 2 , and after sintering is completed and cooled to room temperature, the fiber-Fe₃O₄ / C microsphere composite material can be obtained.

[0098] (5) Take 5 parts of microsphere precursors and place them in a crucible for sintering. The sintering steps are the same as in (4) to obtain Fe₃O₄ / C composite microspheres, as shown in Figure 2 . Pour 90 parts of 107 silicone rubber and 100 parts of gasoline into a stirring tank, and gradually add 5 parts of Fe₃O₄ / C composite microspheres during this period and mix them evenly. After mixing, a uniform stealth absorbing coating is obtained.

[0099] (6) After cleaning the surface of the substrate, thinly coat a layer of KH550. Then add 3 parts of curing agent to the evenly mixed absorbing coating and stir evenly. Then spray the coating evenly on the surface of the substrate. Then lay the fiber-Fe₃O₄ / C microsphere composite material flat on the surface of the coating and cure it for 40 h. Wait for the silicone rubber cross-linking reaction to be complete and at the same time make the organic solvent completely volatilize, and a composite stealth coating can be obtained on the surface of the substrate.

[0100] In this embodiment, the substrate is a metal, such as high-strength steel, aluminum alloy, etc.

[0101] For details, see Figure 1 , there are multiple weaving structures of the carbon fiber cloth used in the present invention, specifically manifested as different weaving densities. The weaving structure used in this embodiment is Figure 1 a.

[0102] Figure 2 This is the morphology diagram of the Fe₃O₄ / C composite microspheres (i.e., absorbing agent microspheres) in this embodiment.

[0103] Figure 3This is the experimental data graph of the electromagnetic parameters of the composite stealth coating (experimental group) and the coating without Fe₃O₄ / C microspheres (control group) in this embodiment. As can be seen from the graph, the dielectric constant and magnetic permeability parameters of the experimental group are higher than those of the control group in the range of 2 - 8 GHz, indicating that the experimental group has better abilities in absorbing, storing, and dissipating electric field energy and magnetic field energy at low frequencies than the control group. Among them, the preparation method of the control group is the same as that of the experimental group, except that Fe₃O₄ / C microspheres are not added during the preparation process.

[0104] Figure 4 This is the experimental data graph of the attenuation constant α of the composite stealth coating and the coating without Fe₃O₄ / C microspheres in this embodiment. As can be obtained from the graph, the attenuation constant of the experimental group is higher than that of the control group in the ranges of 2 - 8 GHz and 14 - 18 Hz, indicating that the experimental group has better abilities in attenuating electromagnetic waves than the control group in both low-frequency and high-frequency ranges.

[0105] Example 2

[0106] This embodiment provides a composite silicone rubber stealth coating resistant to harsh environments, including the following raw material components in parts by weight;

[0107]

[0108] A preparation method of the composite silicone rubber stealth coating is as follows.

[0109] (1) Add 10 parts of iron oxide powder to 20 parts of N-methylpyrrolidone, and ultrasonically disperse for 20 min to form a uniform and stable suspension. Subsequently, add 1 part of cellulose acetate to the suspension, and perform mechanical stirring in an oil bath. The temperature of the oil bath is 50 °C, the stirring duration is 12 h, and the rotation speed of the stirring rod is 350 r / min. After stirring is completed, let the obtained uniform slurry stand to room temperature, and then place it in a vacuum dryer for degassing treatment for 30 min to remove the air mixed in during the stirring process, and obtain the slurry required for preparing the absorbing microspheres.

[0110] (2) Inject the slurry into the syringe of the electrospray ball-making system. The electrospray voltage is 20 kV, the slurry flow rate is 4 ml / min, the nozzle diameter is 0.8 mm, and the height from the nozzle to the coagulation bath is 10 cm. The slurry is dispersed into droplets during electrospray, and the droplets form ceramic microsphere precursors after immersing in the coagulation bath. The precursors are impregnated in the coagulation bath for 24 h, and after sufficient phase transformation, they are filtered out from the coagulation bath and dried at room temperature for 48 h.

[0111] (3) Cut the carbon fiber cloth with a preset weaving structure into a suitable size, perform surface treatment on it, soak it in sodium hydroxide solution to remove surface oil stains, then acidify it with nitric acid, and perform ultrasonic treatment for 20 min to increase its surface roughness, which is conducive to the uniform attachment of microspheres. Then mix 2.5 parts of microsphere precursors with an appropriate amount of deionized water, stir ultrasonically to form a stable suspension, immerse it in the suspension, and continue ultrasonic treatment for 20 min to allow the solution to fully impregnate the fiber cloth structure. Then take out the impregnated fiber cloth, place it in an oven to dry and take it out.

[0112] (4) Place the impregnated fiber cloth in a corundum crucible and sinter it in a muffle furnace in two stages. The sintering atmosphere is nitrogen. The sintering temperature in the first stage is 600 °C, and the sintering time is 10 min. The sintering temperature in the second stage is 1200 °C, and the sintering time is 2 h. The heating and cooling rate is 5 °C / min. During the sintering process, the organic matter pyrolyzes into carbon materials, and Fe₃O₄ / C composite microspheres are in-situ generated on the surface of the fiber cloth. After sintering is completed and cooled to room temperature, the fiber-Fe₃O₄ / C microsphere composite material can be obtained.

[0113] (5) Take 2.5 parts of microsphere precursors and place them in a crucible for sintering. The sintering steps are the same as in (4) to obtain Fe₃O₄ / C composite microspheres. Pour 95 parts of 108 silicone rubber and 100 parts of gasoline into a stirring tank, and gradually add 2.5 parts of Fe₃O₄ / C composite microspheres during this period and mix them evenly to obtain a uniform stealth absorbing coating after mixing.

[0114] (6) After cleaning the surface of the substrate, thinly apply a layer of KH550. Then add 4 parts of curing agent to the evenly mixed absorbing coating and stir evenly. Then spray the coating evenly on the surface of the substrate. Then lay the fiber-Fe₃O₄ / C microsphere composite material flat on the surface of the coating and cure it for 40 h. Wait for the silicone rubber cross-linking reaction to be complete and at the same time allow the organic solvent to completely volatilize, and a composite stealth coating is obtained on the surface of the substrate.

[0115] The above is only the preferred embodiment of the present invention, and it is not a limitation of the present invention in other forms. Any person skilled in the art may use the disclosed technical content to make changes or modifications into equivalent embodiments with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solution content of the present invention still belong to the protection scope of the technical solution of the present invention.

Claims

1. A preparation method of a composite stealth coating resistant to harsh environments, characterized in that, It includes the following steps: S1. Add iron tetroxide powder into an organic solvent, disperse it evenly to form a uniform and stable suspension; then add a polymer, heat and stir evenly, cool to room temperature, and after degassing, obtain the slurry required for preparing the iron tetroxide / carbon composite microspheres; S2. Disperse the slurry by electrospraying into droplets, and the droplets form the first microsphere precursor after immersing in the coagulation bath; the first precursor is impregnated in the coagulation bath, and after sufficient phase transformation, it is filtered out from the coagulation bath and dried to obtain the second microsphere precursor; S3. Disperse the second microsphere precursor obtained in S2 in a non-organic solvent, disperse it evenly to form a uniform and stable suspension; Arrange carbon fiber in the suspension, fully impregnate it, take it out, dry and sinter it to obtain the fiber-iron tetroxide / carbon microsphere composite material; S4. Sinter the second microsphere precursor obtained in S2 to obtain the iron tetroxide / carbon composite microspheres; add the iron tetroxide / carbon composite microspheres into the mixed solution of an organic film-forming agent and a diluent, stir evenly to obtain the stealth absorbing coating; S5. Coating a mixed solution of a binder, a stealth absorbing coating and a curing agent on the substrate in sequence, and then laying the fiber-iron tetroxide / carbon microsphere composite material flat on the surface of the coating, after curing, a composite stealth coating is obtained on the surface of the substrate.

2. The preparation method of a composite stealth coating resistant to harsh environments according to claim 1, characterized in that, By weight, the composite stealth coating includes: 85 - 95 parts of an organic film-forming agent; 3 - 5 parts of a curing agent; 2 - 10 parts of iron tetroxide; 100 - 150 parts of a diluent; 4 - 20 parts of an organic solvent; 1 - 5 parts of a polymer; 400 - 500 parts of a non-organic solvent; 3 - 5 parts of a binder.

3. The preparation method of a composite stealth coating resistant to harsh environments according to claim 1, characterized in that: The organic film-forming agent is silicone rubber; The curing agent is bis(2,4-dichlorobenzoyl) peroxide; The iron tetroxide powder is in powder form with a particle size of 25 - 75 nm; The diluent is 120# gasoline; The organic solvent is N-methylpyrrolidone; The polymer is polyethersulfone or cellulose acetate; The non-organic solvent is water; The binder is a silane coupling agent.

4. The preparation method of a composite stealth coating resistant to harsh environments according to claim 1, characterized in that, In S1: The dispersion is ultrasonic dispersion with a dispersion time of 10 - 30 min; The heating and stirring is mechanical stirring with an oil bath pan heating, the stirring time is 6 - 18 h, and the stirring speed is 300 - 400 r / min; The degassing is vacuum degassing treatment with a degassing time of 20 - 40 min.

5. The preparation method of a composite stealth coating resistant to harsh environments according to claim 1, characterized in that, In S2: The electrospraying specifically is: injecting the slurry into the syringe of the electrospraying system for making microspheres, and the slurry is dispersed into droplets during electrospraying, and the droplets form the microsphere precursor after immersing in the coagulation bath; the electrospraying voltage is 15 - 25 kV, the slurry flow rate is 2 - 4 mL / min, the electrospraying nozzle diameter is 0.5 - 1 mm, and the distance between the electrospraying nozzle and the coagulation bath is 8 - 12 cm; The impregnation time of the precursor in the coagulation bath is 12 - 36 h; The drying is room temperature drying with a drying time of 24 - 72 h.

6. The preparation method of a composite stealth coating resistant to harsh environments according to claim 1, characterized in that, In S3: The carbon fiber cloth is a carbon fiber cloth with the surface oil removed and the surface roughness increased; The dispersion is ultrasonic dispersion, and the dispersion time is 10 - 30 min; The sintering of the microsphere precursor is specifically as follows: The fully impregnated carbon fiber is arranged in a crucible and sintered in a muffle furnace in two stages. The sintering atmosphere is an inert atmosphere. The sintering temperature in the first stage is 500 - 700 °C, and the sintering time is 8 - 12 h. The sintering temperature in the second stage is 1000 - 1400 °C, and the sintering time is 1 - 3 h. The heating and cooling rate is 3 - 6 °C / min.

7. The preparation method of a composite stealth coating resistant to harsh environments according to claim 1, characterized in that In S4, the sintering step of the microsphere precursor is the same as the sintering step in S3.

8. The preparation method of a composite stealth coating resistant to harsh environments according to claim 1, characterized in that, In S5, the curing time is 30 - 50 h.

9. The composite stealth coating resistant to harsh environments obtained by the preparation method according to any one of claims 1 - 8.

10. The application of the composite stealth coating resistant to harsh environments according to claim 9, characterized in that This composite stealth coating is applied to the acid and / or alkali and / or salt corrosion environment.

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