A visible light and radar stealth compatible material and a preparation method thereof

Abstract

The application discloses a kind of compatible visible light and radar stealth material and preparation method thereof, belong to nano particulate stealth material and its preparation technical field.The application solves the problems such as thick coating, large specific gravity of traditional visible light-radar compatible stealth shell core coating material.The application prepares the stealth material of ferrite wrapping reduced graphene oxide by hydrothermal method, the stealth material has core-shell 3D porous structure, so that the overall quality of material is light, and better realizes the high absorption performance in the range of visible light and microwave, and, the color of the stealth material prepared by the application is black, further shows high absorption to visible light, specifically, in 350~750nm visible light range, the absorption rate is 0.92~0.96, and the reflection loss of 2~18GHz microwave band is about-40dB.Moreover, the preparation method provided by the application has the advantages of simplicity, abundant raw material resources, small environmental pollution and the like.

Description

Technical Field

[0001] This invention relates to a stealth material compatible with visible light and radar, and its preparation method, belonging to the technical field of nanoparticle stealth materials and their preparation. Background Technology

[0002] With the continuous development of science and technology, especially the emergence of 5G information technology and advanced, intelligent, and sensitive identification devices, serious threats are posed to national defense. Stealth technology is considered an effective method for reverse detection, thus attracting increasing research interest. However, single-band stealth technologies such as radar stealth, infrared stealth, and visible stealth cannot be used to cope with unpredictable military environments. Therefore, multi-band compatible stealth is needed to avoid the drawbacks of requiring multiple detection devices. Among various detection technologies, radar detection and infrared detection are widely used. Therefore, there is an urgent need to develop high-performance radar-visible compatible stealth materials for practical applications. Theoretically, radar stealth materials require high microwave absorption, while visible stealth materials require high visible light absorption. Current stealth technologies mainly target the visible light, infrared, and radar bands, and there are few reports on stealth materials that integrate visible light and radar compatibility.

[0003] Radar-visible compatible stealth refers to materials that simultaneously possess both visible light and radar stealth properties. Traditional radar stealth materials typically include coating-type and structural-type radar absorbing materials. The former involves mixing an absorber (metal or alloy powder, ferrite, conductive fibers, etc.) with a binder and then coating it onto the target surface to form a stealth coating. The latter has a dual function of load-bearing and radar absorption, usually by dispersing the absorber in a layered structure or using high-strength, high-transmittance polymer composite materials (such as fiberglass, aramid fiber composites, etc.) as the panel and a honeycomb corrugated or pyramidal core as the sandwich structure. For radar absorbing materials used on equipment targets, structural-type radar absorbing materials, which combine radar absorption and load-bearing functions, are more practical.

[0004] Structural radar-absorbing materials offer numerous advantages, such as ease of use, suitability for rapid camouflage and stealth of equipment targets in both field and on-site conditions, and the ability to conceal targets without altering their shape or imposing stringent design requirements. Consequently, these materials are widely used. Existing radar-visible compatible stealth materials achieve this by adding coloring pigments to radar stealth coatings. While this method provides good stealth performance when weight is not a primary concern due to the relatively large overall thickness of the film, existing stealth coatings often suffer from thickness and high density when lightweight requirements are present, making them unsuitable for modern weaponry. Therefore, there is an urgent need for a novel, lightweight, and easily prepared visible-radar compatible stealth material and its preparation method. Summary of the Invention

[0005] This invention addresses the problems of thick coating and high specific gravity in existing traditional visible light and radar compatible stealth shell-core coating materials by providing a visible light and radar compatible stealth material and its preparation method.

[0006] The technical solution of the present invention:

[0007] One of the objectives of this invention is to provide a stealth material compatible with both visible light and radar. This material has a core-shell structure consisting of reduced graphene oxide encapsulated by an encapsulating material, which can be a metal, alloy powder, or ferrite.

[0008] Further specifying, the coating material is aluminum powder, iron powder, nickel powder, or iron(II,III) oxide.

[0009] The second objective of this invention is to provide a method for preparing the above-mentioned stealth material compatible with visible light and radar. The method is as follows: using graphene oxide and encapsulation material as raw materials, a hydrothermal method is used to obtain a stealth material with a core-shell structure.

[0010] Further, graphene oxide was dispersed in distilled water and ultrasonically treated for 3 hours. Then, the coating material was added under stirring conditions, and stirring was continued for another 3 hours. The solution was then transferred to a reaction vessel. After the reaction was completed, the solution was cooled to room temperature, filtered to obtain the precipitate, washed, and vacuum dried to obtain the stealth material.

[0011] Furthermore, the mass-to-volume ratio of graphene oxide, distilled water, and encapsulation material is (0.1-0.5)g:80mL:(0.2-0.4)g.

[0012] Furthermore, the reaction temperature in the reactor is 150℃, and the reaction time is 10 hours.

[0013] To further specify, the precipitate was washed three times in sequence with distilled water and anhydrous ethanol.

[0014] Further specified, the vacuum drying temperature is 60℃ and the time is 12h.

[0015] Further specifying that when the coating material is iron(III) oxide, the preparation method of the coating material is as follows:

[0016] (1) Dissolve FeCl3·6H2O and FeCl3·6H2O in deionized water, then add urea, and add sodium polyacrylate dropwise. After the addition is complete, stir at room temperature for 5 hours to obtain a homogeneous reaction solution.

[0017] (2) Transfer the reaction solution to a reaction vessel and react at 150°C for 10 hours, then cool to room temperature;

[0018] (3) Magnetic Fe3O4 nanoparticles were obtained by magnetic separation, washed and vacuum dried to obtain magnetic nanoparticles.

[0019] Further specifying, the required volume ratio of FeCl3·6H2O, FeCl3·6H2O and deionized water is (2-4)g:(5-7)g:(150-200)mL.

[0020] Further restrictions are placed on the dosage of urea and sodium polyacrylate, both of which are 1-3g.

[0021] Further specifying, the washing in step (3) involves washing three times in sequence with ethanol and deionized water.

[0022] Further specified, the vacuum drying temperature in step (3) is 70℃ and the time is 10h.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] (1) This invention employs a core-shell structured stealth material composed of reduced graphene oxide encapsulated in a coating material. Graphene oxide is selected as the visible light stealth material, and the coating material preferably uses iron oxide (Fe3O4), a double-dielectric material with both dielectric and magnetic loss characteristics, as a ferrite-oxygen system absorbing material. The quantum size effect of the iron oxide nanoparticles causes a blue shift in their absorption of certain wavelengths of light, and the iron oxide nanoparticles broaden their absorption of various wavelengths of light while possessing high permeability. This results in a stealth material prepared by this invention exhibiting excellent visible light and radar stealth performance, effectively absorbing electromagnetic waves in both bands, and demonstrating better technical performance in visible-radar compatible stealth. Furthermore, the stealth material prepared by this invention is black in color, further demonstrating its high absorption of visible light.

[0025] (2) The visible-radar compatible stealth material proposed in this invention, through structural encapsulation design and theoretical analysis, has an absorption rate of 0.92 to 0.96 in the visible light range of 350 to 750 nm and a reflection loss of about -40 dB in the microwave band of 2 to 18 GHz.

[0026] (3) The present invention uses a hydrothermal method to prepare a stealth material with a core-shell structure of reduced graphene oxide encapsulated by ferrite. The preparation process is simple and highly controllable. Moreover, the 3D porous structure of the stealth material makes the material lightweight, effectively solving the problems of thick coating and high specific gravity of traditional visible light-radar compatible stealth core-shell coating materials.

[0027] (4) The iron oxide used in this invention is a traditional iron-oxygen system microwave absorbing material with advantages such as abundant natural resources, low environmental pollution, simple preparation process, and deep microwave absorption intensity. Attached Figure Description

[0028] Figure 1 Here is a photograph of the stealth material prepared in Example 3;

[0029] Figure 2 SEM images of the stealth material prepared in Example 3;

[0030] Figure 3 TEM image of the stealth material prepared in Example 3;

[0031] Figure 4 The reflectance spectrum of the stealth material prepared in Example 3 in the visible light range;

[0032] Figure 5 The reflection loss of the coating formed by mixing the stealth material prepared in Example 3 with paraffin wax in the microwave range. Detailed Implementation

[0033] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0034] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0035] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0036] Example 1

[0037] The method for preparing a stealth material compatible with both visible light and radar in this embodiment is as follows:

[0038] (1) Precursor preparation: Magnetic nanoparticles were synthesized by hydrothermal method;

[0039] Specifically, under the stirring action of a magnetic stirrer, 3g of FeCl3·6H2O and 6g of Na3C6H5O7·2H2O were dissolved sequentially in 160mL of deionized water. The solution was then filtered, and 2g of urea was added to the supernatant, followed by the gradual addition of 2g of sodium polyacrylate. As the amount of sodium polyacrylate added increased, the viscosity of the solution gradually increased. After stirring with a magnetic stirrer for 5 hours at room temperature, the resulting homogeneous solution was transferred to a 100mL stainless steel high-pressure reactor lined with Teflon. The high-pressure reactor was sealed and reacted at 150℃ for 10 hours, then allowed to cool naturally to room temperature. The resulting Fe3O4 nanoparticles were separated magnetically and washed three times, successively with ethanol and deionized water. Finally, the washed nanoparticles were dried under vacuum in a tube furnace at 70℃ for 10 hours to obtain Fe3O4 powder.

[0040] (2) Iron oxide encapsulates reduced graphene oxide;

[0041] Specifically, 0.1 g of graphene oxide was dispersed in 80 mL of distilled water and ultrasonically treated for 3 h. Then, 0.3 g of Fe3O4 powder obtained in step (1) was added to the solution under magnetic stirring, and stirring continued for 3 h. The solution was then transferred to a 100 mL stainless steel high-pressure reactor lined with Teflon, sealed, and placed in an oven at 150 °C for 5 h. After natural cooling to room temperature, the precipitate was filtered, washed three times with distilled water and anhydrous ethanol, and dried in a vacuum oven at 60 °C for 12 h to obtain the stealth material.

[0042] Example 2

[0043] (1) Precursor preparation: Magnetic nanoparticles were synthesized by hydrothermal method;

[0044] Specifically, under the stirring action of a magnetic stirrer, 3g of FeCl3·6H2O and 6g of Na3C6H5O7·2H2O were dissolved sequentially in 160mL of deionized water. The solution was then filtered, and 2g of urea was added to the supernatant, followed by the gradual addition of 2g of sodium polyacrylate. As the amount of sodium polyacrylate added increased, the viscosity of the solution gradually increased. After stirring with a magnetic stirrer for 5 hours at room temperature, the resulting homogeneous solution was transferred to a 100mL stainless steel high-pressure reactor lined with Teflon. The high-pressure reactor was sealed and reacted at 150℃ for 10 hours, then allowed to cool naturally to room temperature. The resulting Fe3O4 nanoparticles were separated magnetically and washed three times, successively with ethanol and deionized water. Finally, the treated nanoparticles were dried under vacuum at 70℃ for 10 hours in a vacuum tube furnace to obtain Fe3O4 powder.

[0045] (2) Iron oxide encapsulates reduced graphene oxide;

[0046] Specifically, 0.2 g of graphene oxide was dispersed in 80 mL of distilled water and ultrasonically treated for 3 h. Then, 0.3 g of Fe3O4 powder obtained in step (1) was added to the solution under magnetic stirring, and stirring continued for 3 h. The solution was then transferred to a 100 mL stainless steel high-pressure reactor lined with Teflon and reacted at 150 °C in an oven for 5 h. After natural cooling to room temperature, the filtered precipitate was washed three times with distilled water and anhydrous ethanol, and dried in a vacuum oven at 60 °C for 12 h to obtain the stealth material.

[0047] Example 3

[0048] (1) Precursor preparation: Magnetic nanoparticles were synthesized by hydrothermal method;

[0049] Specifically, under the stirring action of a magnetic stirrer, 3g of FeCl3·6H2O and 6g of Na3C6H5O7·2H2O were dissolved sequentially in 160mL of deionized water. The solution was then filtered, and 2g of urea was added to the supernatant, followed by the gradual addition of 2g of sodium polyacrylate. As the amount of sodium polyacrylate added increased, the viscosity of the solution gradually increased. After stirring with a magnetic stirrer for 5 hours at room temperature, the resulting homogeneous solution was transferred to a 100mL stainless steel high-pressure reactor lined with Teflon. The high-pressure reactor was sealed and reacted at 150℃ for 10 hours, then allowed to cool naturally to room temperature. The resulting Fe3O4 nanoparticles were separated magnetically and washed three times, successively with ethanol and deionized water. Finally, the treated nanoparticles were dried under vacuum at 70℃ for 10 hours in a vacuum tube furnace to obtain Fe3O4 powder.

[0050] (2) Iron oxide encapsulates reduced graphene oxide;

[0051] 0.3 g of graphene oxide was dispersed in 80 mL of distilled water and sonicated for 3 h. Then, 0.3 g of Fe3O4 powder obtained in step (1) was added to the solution under magnetic stirring, and stirring continued for 3 h. The solution was then transferred to a 100 mL stainless steel high-pressure reactor lined with Teflon and reacted in an oven at 150 °C for 5 h. After natural cooling to room temperature, the precipitate was filtered, washed three times with distilled water and anhydrous ethanol, and dried in a vacuum oven at 60 °C for 12 h to obtain the stealth material, abbreviated as Fe3O4@rGO.

[0052] The microstructure and stealth properties of Fe3O4@rGO prepared in this embodiment were characterized as follows:

[0053] Figure 1 The image shows a photograph of the Fe3O4@rGO prepared in this embodiment. Compared to the background, the material appears black, further demonstrating its high absorption of visible light.

[0054] Figure 2 This is a SEM image of Fe3O4@rGO prepared in this embodiment, by... Figure 2 It can be seen that Fe3O4@rGO exhibits particles with a size of 200nm.

[0055] Figure 3 The TEM image of Fe3O4@rGO prepared in this embodiment is shown by [the image source is missing]. Figure 3 It can be seen that 0.33 nm Fe3O4 was grown on the outside of rGO with lattice fringes of 0.336 nm, proving that iron oxide successfully encapsulated reduced graphene oxide.

[0056] Figure 4 The image shows the reflectance spectrum of Fe3O4@rGO prepared in this embodiment in the visible light range. Figure 4 It can be seen that the absorption rate of Fe3O4@rGO prepared in this embodiment is 0.96 in the 0.3-0.8 μm band.

[0057] Figure 5 The reflection loss of Fe3O4@rGO prepared in this embodiment, mixed with paraffin (blended at a mass ratio of 1:4) to form coatings of different thicknesses, is measured in the microwave range. Figure 5 It can be seen that in the 2-18 GHz band, the reflection loss of the 3 mm thick coating prepared by Fe3O4@rGO in this embodiment can reach -43.4 dB.

[0058] Example 4

[0059] (1) Precursor preparation: Magnetic nanoparticles were synthesized by hydrothermal method;

[0060] Specifically, under the stirring action of a magnetic stirrer, 3g of FeCl3·6H2O and 6g of Na3C6H5O7·2H2O were dissolved sequentially in 160mL of deionized water. The solution was then filtered, and 2g of urea was added to the supernatant, followed by the gradual addition of 2g of sodium polyacrylate. As the amount of sodium polyacrylate added increased, the viscosity of the solution gradually increased. After stirring with a magnetic stirrer for 5 hours at room temperature, the resulting homogeneous solution was transferred to a 100mL stainless steel high-pressure reactor lined with Teflon. The high-pressure reactor was sealed and reacted at 150℃ for 10 hours, then allowed to cool naturally to room temperature. The resulting Fe3O4 nanoparticles were separated magnetically and washed three times, successively with ethanol and deionized water. Finally, the treated nanoparticles were dried under vacuum at 70℃ for 10 hours in a vacuum tube furnace to obtain Fe3O4 powder.

[0061] (2) Iron oxide encapsulates reduced graphene oxide;

[0062] 0.4 g of graphene oxide was dispersed in 80 mL of distilled water and sonicated for 3 h. Then, 0.3 g of Fe3O4 powder obtained in step (1) was added to the solution under magnetic stirring, and stirring continued for 3 h. The solution was then transferred to a 100 mL stainless steel high-pressure reactor lined with Teflon and reacted in an oven at 150 °C for 5 h. After natural cooling to room temperature, the precipitate was filtered, washed three times with distilled water and anhydrous ethanol, and dried in a vacuum oven at 60 °C for 12 h.

[0063] Example 5

[0064] (1) Precursor preparation: Magnetic nanoparticles were synthesized by hydrothermal method;

[0065] Specifically, under magnetic stirring, 3g of FeCl3·6H2O and 6g of Na3C6H5O7·2H2O were dissolved sequentially in 160mL of deionized water. The solution was then filtered, and 2g of urea was added to the supernatant, followed by the gradual addition of 2g of sodium polyacrylate. As the amount of sodium polyacrylate added increased, the viscosity of the solution gradually increased. After stirring with a magnetic stirrer for 5 hours at room temperature, the resulting homogeneous solution was transferred to a 100mL stainless steel high-pressure reactor lined with Teflon. The reactor was sealed and reacted at 150℃ for 10 hours, then allowed to cool naturally to room temperature. The resulting Fe3O4 nanoparticles were separated magnetically and washed three times, successively with ethanol and deionized water. Finally, the treated nanoparticles were dried under vacuum at 70℃ for 10 hours in a vacuum tube furnace to obtain Fe3O4 powder.

[0066] (2) Iron oxide encapsulates reduced graphene oxide;

[0067] 0.5 g of graphene oxide was dispersed in 80 mL of distilled water and sonicated for 3 h. Then, 0.3 g of Fe3O4 powder obtained in step (1) was added to the solution under magnetic stirring, and stirring continued for 3 h. The solution was then transferred to a 100 mL stainless steel high-pressure reactor lined with Teflon and reacted in an oven at 150 °C for 5 h. After natural cooling to room temperature, the precipitate was filtered, washed three times with distilled water and anhydrous ethanol, and dried in a vacuum oven at 60 °C for 12 h.

[0068] The stealth performance of the stealth materials prepared in Examples 1-5 was tested in various frequency bands, and the results are shown in Table 1 below:

[0069] Table 1. Comparison of stealth performance of stealth materials across different frequency bands.

[0070]

[0071]

[0072] As shown in Table 1 above, the radar-infrared-visible multi-spectral camouflage and stealth structure designed in this invention exhibits an average reflectivity of less than -1dB in the S-band (2-4GHz), less than -5dB and -15dB in the C-band (4-8GHz) and X-band (8-12GHz) respectively, and less than -13dB in the Ku-band (12-18GHz). In the visible light band, the absorptivity reaches as high as 0.92–0.96. This invention not only solves the problem of multi-spectral stealth in radar and visible light bands using current absorbing materials, but also boasts a simple process, strong controllability, and low cost, making it of significant commercial application value.

[0073] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A stealth material compatible with both visible light and radar, characterized in that, The material is a core-shell structure consisting of reduced graphene oxide encapsulated by a material, which can be a metal, alloy powder, or ferrite.

2. The visible light and radar-compatible stealth material according to claim 1, characterized in that, The coating material is aluminum powder, iron powder, nickel powder, or iron(II,III) oxide.

3. A method for preparing a visible light and radar-compatible stealth material as described in claim 1, characterized in that, The method involves using graphene oxide and encapsulation materials as raw materials and employing a hydrothermal method to obtain a stealth material with a core-shell structure.

4. The method for preparing a stealth material compatible with visible light and radar according to claim 3, characterized in that, Graphene oxide was dispersed in distilled water and ultrasonically treated for 3 hours. Then, the coating material was added under stirring and stirring was continued for 3 hours. The solution was then transferred to a reaction vessel. After the reaction was completed, the solution was cooled to room temperature, filtered to obtain the precipitate, washed, and vacuum dried to obtain the stealth material.

5. The method for preparing a visible light and radar-compatible stealth material according to claim 4, characterized in that, The mass-to-volume ratio of graphene oxide, distilled water, and encapsulation material is (0.1-0.5) g: 80 mL: (0.2-0.4) g.

6. The method for preparing a visible light and radar-compatible stealth material according to claim 4, characterized in that, The reaction temperature in the reactor was 150℃, and the reaction time was 10 hours.

7. The method for preparing a stealth material compatible with visible light and radar according to claim 3, characterized in that, When the coating material is iron(III) oxide, the preparation method of the coating material is as follows: (1) Dissolve FeCl3·6H2O and FeCl3·6H2O in deionized water, then add urea, and add sodium polyacrylate dropwise. After the addition is complete, stir at room temperature for 5 hours to obtain a homogeneous reaction solution. (2) Transfer the reaction solution to a reaction vessel and react at 150°C for 10 h, then cool to room temperature; (3) Magnetic Fe3O4 nanoparticles were obtained by magnetic separation, washed and vacuum dried to obtain magnetic nanoparticles.

8. The method for preparing a visible light and radar-compatible stealth material according to claim 7, characterized in that, The recommended volume ratio of FeCl3·6H2O, FeCl3·6H2O and deionized water is (2-4) g: (5-7) g: (150-200) mL.

9. The method for preparing a visible light and radar-compatible stealth material according to claim 8, characterized in that, The dosage of both urea and sodium polyacrylate is 1-3g.

10. The method for preparing a visible light and radar-compatible stealth material according to claim 7, characterized in that, The vacuum drying temperature is 70℃ and the time is 10h.

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