Visible-infrared-radar band compatible stealth composite material, its preparation method and application

Abstract

The present invention discloses a visible-infrared-radar band compatible stealth composite material, its preparation method and application. The composite material includes a woven layer, a wide-spectrum functional layer and a transparent medium layer; the woven layer includes a plurality of fibers, and there are pores between adjacent fibers; the material of the wide-spectrum functional layer includes metal and / or nitride and the thickness is below a preset thickness to form a discontinuous structure; the transparent medium layer covers the surface of the discontinuous structure and forms optical resonance with the discontinuous structure to produce structural color. The present invention utilizes the fiber structure of the woven layer to form a wide-spectrum functional layer with a discontinuous structure to cooperate with the medium layer to achieve colorful structural colors in the visible light range; in the thermal infrared band, the effect of low infrared emissivity is achieved through the reflection effect of the resonant cavity; in the radar wave range, the discontinuous wide-spectrum functional layer cannot effectively reflect radar waves, so the material has visible, infrared and radar multi-band compatible stealth performance.

Description

Technical Field

[0001] The present invention relates to the field of wide-band stealth technology, and in particular to a visible-infrared-radar band compatible stealth composite material, a preparation method thereof, and applications thereof. Background Art

[0002] With the rapid development of precision guidance and integrated detection technologies, manned and unmanned equipment may face threats from multiple spectrum detection devices, including infrared, radar, and visible light. Therefore, single-band stealth materials will be unable to meet the stealth requirements of the complex electromagnetic environment of the battlefield. To reduce the likelihood of equipment being detected, the development of stealth materials compatible with visible light, infrared, and radar is an inevitable trend in the development of stealth technology. Among the various optoelectronic detection technologies, visible light, infrared, and radar detection account for 90%. Therefore, stealth technology that can simultaneously counter visible light, infrared, and radar is a key means of enhancing battlefield survivability.

[0003] Currently, existing stealth technologies primarily target one or two of the three aforementioned wavelengths, making it difficult to achieve compatible stealth across all three bands: visible light (typically 380-780 nm), infrared (typically 2.5-25 μm), and radar (typically 8-12 GHz). Existing technologies that integrate multi-band stealth across visible light, infrared, and radar primarily rely on composite stealth coatings. This technology combines a wave-absorbing coating with a low-emissivity infrared camouflage coating to create a coating with multi-band compatible stealth performance. However, infrared stealth requires the coating to have low infrared absorption and high reflectivity, while microwave (radar) stealth requires high absorption and low reflectivity. Consequently, the electromagnetic wave reflection properties of infrared and radar stealth conflict, making infrared-radar compatible stealth impossible. Existing multi-band stealth composite coatings struggle to overcome this inherent contradiction. At the same time, both optical camouflage materials and infrared low-emissivity materials need to be set on the target surface, and the mixture of the two usually significantly affects the overall camouflage effect. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a visible-infrared-radar band compatible stealth composite material, its preparation method and application.

[0005] To achieve the aforementioned object of the invention, the technical solutions adopted by the present invention include:

[0006] In a first aspect, the present invention provides a visible light-thermal infrared-radar band compatible stealth composite material, which includes a woven layer, a wide spectrum functional layer and a transparent medium layer;

[0007] The woven layer includes multiple fibers, and there are pores between adjacent fibers; the material of the wide-spectrum functional layer includes metal and / or nitride, and the thickness is below a preset thickness, so that the wide-spectrum functional layers attached to the surfaces of the multiple fibers independently form a discontinuous structure; the transparent medium layer covers the surface of the discontinuous structure and forms optical resonance with the discontinuous structure to produce structural color.

[0008] In a second aspect, the present invention further provides a method for preparing a visible light-thermal infrared-radar band compatible stealth composite material, which comprises:

[0009] The surface of the braided layer is plated with metal or nitride by physical sputtering to form a wide spectrum functional layer, and the thickness of the wide spectrum functional layer is controlled to be below a preset thickness;

[0010] A transparent medium layer is continuously plated on the surface of the wide spectrum functional layer.

[0011] In a third aspect, the present invention also provides an application of the above-mentioned visible light-thermal infrared-radar band compatible stealth composite material in wide-band stealth.

[0012] Based on the above technical solution, compared with the prior art, the beneficial effects of the present invention include at least:

[0013] The technical solution provided by the present invention constructs an optical resonance structure on the woven layer, utilizes the fiber structure of the woven layer to form a wide-spectrum functional layer with a discontinuous structure, and cooperates with the dielectric layer to achieve colorful structural colors in the visible light range; in the thermal infrared band, the effect of low infrared emissivity is achieved through the reflection of the resonant cavity, and the thermal radiation of the object itself is controlled, thereby achieving an infrared stealth effect; in the radar wave range, the discontinuous wide-spectrum functional layer cannot effectively reflect radar waves and cannot be detected, so the stealth effect of radar waves can be achieved. Therefore, the composite material provided by the present invention has multi-band compatible stealth performance in visible, infrared and radar, and can also have the characteristics of light weight, flexibility, high strength, breathability, etc., and can be applied to organisms and equipment to meet multi-environment stealth requirements.

[0014] The above description is only an overview of the technical solution of the present invention. In order to enable those skilled in the art to more clearly understand the technical means of this application and implement them according to the contents of the specification, the following is an explanation of the preferred embodiments of the present invention with detailed drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic structural diagram of a visible light-thermal infrared-radar band compatible stealth composite material provided by a typical embodiment of the present invention;

[0016] Figure 2This is a surface photograph of a visible light-thermal infrared-radar band compatible stealth composite material provided by a typical embodiment of the present invention;

[0017] Figure 3 This is a test chart of the infrared emission spectrum of a visible light-thermal infrared-radar band compatible stealth composite material provided by a typical embodiment of the present invention;

[0018] Figure 4 This is a radar transmission spectrum test chart of a visible light-thermal infrared-radar band compatible stealth composite material provided by a typical embodiment of the present invention;

[0019] Figure 5 This is a schematic diagram of the color adjustment spectrum of a visible light-thermal infrared-radar band compatible stealth composite material provided by a typical embodiment of the present invention;

[0020] Figure 6 This is a surface photograph of a visible light-thermal infrared-radar band compatible stealth composite material provided by another typical embodiment of the present invention;

[0021] Figure 7 This is a test chart of the infrared emission spectrum of a visible light-thermal infrared-radar band compatible stealth composite material provided by another typical embodiment of the present invention;

[0022] Figure 8 This is a radar transmission spectrum test chart of a composite material provided by a typical comparative example of the present invention;

[0023] Figure 9 This is an infrared emission spectrum test chart of a composite material provided by another typical comparative example of the present invention. DETAILED DESCRIPTION

[0024] In view of the shortcomings of the prior art, the inventors of this case, after long-term research and extensive practice, have proposed the technical solution of the present invention. The following will further explain this technical solution, its implementation process and principles.

[0025] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0026] Moreover, relational terms such as “first” and “second” are merely used to distinguish one component or method step from another with the same name, but do not necessarily require or imply any actual relationship or order between these components or method steps.

[0027] like Figure 1As shown, an embodiment of the present invention provides a visible light-thermal infrared-radar band compatible stealth composite material, which includes a woven layer, a wide-spectrum functional layer and a transparent medium layer; the woven layer includes a plurality of fibers, and there are pores between adjacent fibers; the material of the wide-spectrum functional layer includes metal and / or nitride, and the thickness is below a preset thickness, so that the wide-spectrum functional layers attached to the surfaces of the plurality of fibers independently form a discontinuous structure; the transparent medium layer covers the surface of the discontinuous structure and forms optical resonance with the discontinuous structure to produce structural color.

[0028] As a typical example, an embodiment of the present invention proposes a fabric with multiple colors, low infrared emissivity, and compatible broadband radar wave-transmitting characteristics. The surface of the fabric is a coating structure, including a wide-spectrum functional layer and a transparent dielectric layer. The transparent dielectric layer is deposited on the wide-spectrum functional layer. The multi-color is achieved through the thin film interference effect between coatings with different optical parameters, such as jungle green, sandy yellow, etc. At the same time, the wide-spectrum functional layer has low emissivity in the infrared band.

[0029] The above-mentioned product is provided in the form of fabric and can be used for applications such as biological wear and device covering. However, based on the same technical ideas, a non-independent fabric product can also be provided. For example, the surface of the device shell itself exposes an outer layer with a woven structure, and then the structure of the above-mentioned composite material is prepared based on the outer layer, which is integrated with the shell to form a self-stealth structure, etc. Various feasible implementation methods fall within the scope of protection of the present invention.

[0030] In the above technical solution, a key technical means is to utilize the discontinuous characteristics of the woven fabric, that is, there are gaps between multiple fibers or multiple fibers form a hole, and there is cross-division of fibers in different directions. For example, the warp divides the weft into multiple segments. Combined with precise control of the thickness of the wide-spectrum functional layer, the independent segmentation of the metal and / or nitride is achieved to form independent discontinuous structures with different scattering effects at different thicknesses. The discontinuous structure can reduce infrared emission without affecting the structural color. At the same time, the structure does not have a continuous conductive network, and therefore plays a key role in enhancing radar wave transmission.

[0031] Specifically, the composite material achieves multi-colored structural colors in the visible light range by creating optical resonance between a discontinuous structure and a transparent dielectric layer on a fiber woven base. Furthermore, by controlling the thickness of the dielectric layer, the desired color can be customized for visual stealth. In the thermal infrared region, a low-emissivity effect is achieved through a metal / nitride reflective layer with a micro-nano resonant cavity, controlling the object's own thermal radiation and thus achieving infrared stealth. In the radar wave range, the discontinuous wide-band functional layer cannot effectively reflect radar waves, making it undetectable, thereby achieving stealth against radar waves.

[0032] Regarding specific structural dimensions, in some embodiments, the fiber diameter of the woven layer is about 80 μm, such as 60-100 μm, and the average pore width between the fibers is about 50 μm, such as 30-70 μm.

[0033] In some embodiments, the predetermined thickness is subwavelength, for example, below the lower limit of visible light, 380 nm. In some specific implementations, the thickness of the broadband functional layer may be significantly lower than the predetermined thickness, but is not limited to this range. The predetermined thickness may need to be adjusted based on the material and deposition method to avoid forming a large, continuous broadband functional layer and to ensure that the broadband functional layer is thick enough to function properly.

[0034] In the above technical solution, the fiber diameter, average gap width, and predetermined thickness all significantly influence the size of the discontinuous structures. When the fiber diameter is large (e.g., exceeding 150 μm), the individual structures of the resulting discontinuous structure are larger. When the fiber gap is large (e.g., exceeding 80 μm), the individual structures of the discontinuous structure are spaced farther apart, absorbing or transmitting most visible light, thereby affecting the structural color. Furthermore, the thickness of the broadband functional layer also affects the size and spacing. When the thickness is large, the individual structures become larger while the spacing decreases. When the thickness is too large, for example, when the thickness exceeds 300 nm, the inventors have observed in practice that multiple discontinuous structures often merge to form a more continuous functional layer, triggering full-band reflection and significantly losing high radar transmittance. Therefore, in specific applications, the above parameters should be properly controlled.

[0035] In some embodiments, the thickness of the broadband functional layer is 20-300 nm. Of course, in addition to having an upper limit, the broadband functional layer should not be too thin. Thickness determines thermal infrared and radar stealth effects, and the thickness varies on different fabric substrates, depending on whether the metal layer is continuous and whether a continuous conductive network is formed. An excessively thick metal layer will form a continuous film with excellent conductivity, thereby reflecting radar waves and being detected. On the other hand, the thickness of this layer cannot be less than 30 nm, otherwise it will affect its infrared reflection effect. When the thickness is reduced to 20 nm, its infrared reflection effect is greatly lost, making it difficult to achieve infrared stealth.

[0036] Regarding the transparent dielectric layer, in some embodiments, the thickness of the transparent dielectric layer is 50-400 nm, and the structural color changes with the thickness of the transparent dielectric layer. The thickness of the transparent dielectric layer can be adjusted over a wide range, and its thickness can be freely adjusted to produce different structural colors. In a preferred embodiment, the thickness of the transparent dielectric layer can be set to different levels in different areas to achieve a camouflage effect.

[0037] Regarding the materials of each layer, in some embodiments, the metal includes any one or a combination of two or more of gold, silver, copper, aluminum, tungsten, and titanium, and the nitride includes any one or a combination of two of titanium nitride and zirconium nitride, but is not limited thereto.

[0038] In some embodiments, the transparent medium layer includes any one or a combination of two or more of aluminum oxide, titanium oxide, tungsten oxide, zinc oxide, zirconium oxide, and niobium oxide, but is not limited thereto.

[0039] In some embodiments, the fibers may include commercially available conventional finished fibers such as nylon, polyester, acrylic, polyamide, spandex, polypropylene, and vinylon, as well as various advanced fibers, as long as they meet radar transmission characteristics.

[0040] The above materials are a variety of materials that the inventors of the present invention have tried for a long time, and they can all achieve similar three-band stealth effects. However, this does not mean that the materials that can achieve this effect are limited to the materials listed above.

[0041] Furthermore, in some embodiments, the transparent dielectric layer is further covered with a transparent protective layer made of a radar-transparent material. In some preferred embodiments, the transparent protective layer, such as a silicon dioxide layer or a polymer layer, can provide protection without affecting the structural color.

[0042] A second aspect of the embodiments of the present invention further provides a method for preparing the visible light-thermal infrared-radar band compatible stealth composite material provided in any of the above embodiments, comprising the following steps:

[0043] The surface of the braided layer is plated with metal or nitride by physical sputtering to form a wide spectrum functional layer, and the thickness of the wide spectrum functional layer is controlled to be below a preset thickness;

[0044] A transparent medium layer is continuously plated on the surface of the wide spectrum functional layer.

[0045] In some embodiments, the physical sputtering method includes any one or a combination of two or more of magnetron sputtering, vacuum evaporation, spin coating, and spray coating, but is not limited thereto.

[0046] As a typical example, the method for preparing the stealth fabric with multiple visible colors, low infrared emissivity, and radar-transparent compatibility provided by the present invention includes the following steps:

[0047] S1: Using fabric as the substrate, a wide-spectrum functional layer is deposited on its surface using physical vapor deposition methods such as magnetron sputtering and evaporation. By controlling the film thickness, low infrared emissivity is achieved while ensuring radar transparency.

[0048] S2: A transparent dielectric layer is deposited on the surface of the wide-spectrum functional layer using magnetron sputtering. The film thickness is then adjusted according to the desired color, and a variety of colors are obtained using the thin film interference effect.

[0049] Furthermore, an embodiment of the present invention also provides an application of the visible light-thermal infrared-radar band compatible stealth composite material provided by any of the above embodiments in wide-band stealth.

[0050] The visible light-thermal infrared-radar band compatible stealth composite material provided by the present invention can be realized through a continuous coating process, and has the advantage of large-area processing. The wide-spectrum functional layer and the transparent medium layer are deposited in sequence on the flexible base fabric, and the compatibility of low infrared emissivity and broadband radar wave transparency can be achieved through precise thickness control. The wavelength selective interference between the layer and the transparent medium layer in the visible light band is utilized to achieve a wide color gamut and high-saturation visible color of the fabric. At the same time, the infrared lossless medium layer will not affect the low emissivity of the wide-spectrum functional layer, thereby achieving the application effect of visible light-thermal infrared-microwave wide-band compatible stealth.

[0051] The technical solution of the present invention is further described in detail below through several embodiments and in conjunction with the accompanying drawings. However, the selected embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0052] Example 1

[0053] This embodiment provides a visible light-thermal infrared-radar wave wide band compatible fabric, such as Figure 1 As shown, it includes, from top to bottom, a transparent medium layer A, a wide spectrum functional layer B, and a porous woven base layer C. The porous woven base layer C is made of nylon fabric with a thickness of about 50 μm and a pore size of about 50 μm, providing support, breathability, and basic radar wave transmission performance.

[0054] The transparent medium layer A is a TiO2 layer with a thickness of about 130 nm. The wide spectrum functional layer is a metal Ti with a thickness of about 100 nm, which is in-situ deposited on the porous woven base layer C and also has a porous structure.

[0055] The method for preparing the visible light-thermal infrared-radar wave wide-band compatible fabric includes:

[0056] S1: Select commodity fabric base with high strength and breathability;

[0057] S2: Using magnetron sputtering to deposit a metal layer and a transparent dielectric layer on the base fabric in sequence;

[0058] This example produces a visible light-thermal infrared-microwave wide-band compatible fabric such as Figure 2 The visual color shown is khaki, and the effect of low emissivity in the infrared band can be found in Figure 3As shown, the infrared emissivity at 10μm wavelength is less than 0.3, and the high transmittance characteristics test in the microwave band can be found in Figure 4 shown.

[0059] Obviously, the visible light-thermal infrared-radar wave wide band compatible fabric provided by this embodiment has excellent three-band stealth capability. In addition, by adjusting the thickness of the transparent medium layer, it can be adjusted between different colors. For details, please refer to Figure 5 shown.

[0060] Example 2

[0061] This embodiment provides a visible light-thermal infrared-microwave broadband compatible fabric, which is similar to embodiment 1. It includes a transparent medium layer, a wide spectrum functional layer, and a porous woven base layer arranged in order from top to bottom.

[0062] The difference between the two is:

[0063] The wide-spectrum functional layer adopts a double-layer structure, consisting of about 50nm of metallic copper and 100nm of aluminum. Compared with the single-layer metal in Example 1, the double-layer structure used in this embodiment does not affect the low infrared emissivity, but enhances the interference effect and achieves highly saturated visible colors.

[0064] A method for preparing a visible light-thermal infrared-microwave broadband compatible fabric comprises:

[0065] S1: Select commodity fabric base with high strength and breathability;

[0066] S2: Using magnetron sputtering to deposit a wide spectrum functional layer and a transparent dielectric layer on the porous woven base layer;

[0067] The visible light-thermal infrared-microwave broadband compatible fabric prepared in this embodiment is visually green. Figure 6 As shown; the infrared emissivity at 10μm wavelength is less than 0.1, which is lower than that of Example 1. For test results, see Figure 7 shown.

[0068] Example 3

[0069] This embodiment provides a wide-band visible light, thermal infrared, and microwave-compatible fabric, similar to Example 1. The difference lies in the addition of a silicon dioxide layer on top of the topmost transparent dielectric layer. The thickness of this layer can be adjusted appropriately without significantly affecting the performance in the visible, infrared, and microwave bands. However, it enhances the surface stability of the wide-band visible light, thermal infrared, and radar-compatible stealth fabric, including its abrasion resistance and water and oxygen resistance. This embodiment is also applicable to Example 2.

[0070] Comparative Example 1-1

[0071] This comparative example is substantially the same as Example 1, except that:

[0072] The magnetron sputtering time was extended to increase the thickness of the broadband functional layer to 400 nm.

[0073] The functional layer prepared in this comparative example does not have the discontinuous structure characteristic of the wide-spectrum functional layer prepared in Example 1. Due to its thick deposition thickness, the coatings between multiple fibers are combined to form a continuous structure, which loses the radar transmission property.

[0074] Specifically, the transparent medium layer A is a TiO2 layer with a thickness of about 130 nm. The wide spectrum functional layer is a metal Ti with a thickness of about 400 nm, which is in-situ deposited on the porous woven base layer C.

[0075] The method for preparing the visible light-thermal infrared-radar wave wide-band compatible fabric includes:

[0076] S1: Select commodity fabric base with high strength and breathability;

[0077] S2: Using magnetron sputtering to deposit a metal layer and a transparent dielectric layer on the base fabric in sequence;

[0078] The microwave band test of a fabric prepared in this comparative example is shown in FIG. Figure 8 As shown, it is obvious that the fabric provided in this comparative example does not have high microwave permeability.

[0079] Comparative Example 1-2

[0080] This comparative example is substantially the same as Example 1, except that:

[0081] The magnetron sputtering time was shortened and the thickness of the broadband functional layer was reduced to 15 nm.

[0082] The fabric prepared in this comparative example does not have low infrared emissivity. Its emission spectrum is shown in Figure 9 As shown, no infrared stealth function is presented.

[0083] Comparative Example 2-1

[0084] This comparative example is substantially the same as Example 1, except that:

[0085] Replace nylon cloth with nylon film.

[0086] Since the substrate does not have a woven structure, after the metal layer is deposited, a complete continuous metal layer is formed, which is similar to the result of Comparative Example 1-1 and completely loses the radar transmission property.

[0087] Comparative Example 2-2

[0088] This comparative example is substantially the same as Example 1, except that:

[0089] Adjust the weaving parameters of the nylon fabric so that it is tightly woven, with close contact between the fibers and almost no noticeable gaps.

[0090] Since the substrate does not have a porous structure, after the metal layer is deposited, a nearly continuous metal layer is formed, which is similar to the result of Comparative Example 1-1 and completely loses the radar transmission property.

[0091] Based on the above embodiments and comparative examples, it can be clearly seen that the technical solution provided by the embodiments of the present invention constructs an optical resonance structure on the woven layer, utilizes the fiber structure of the woven layer to form a wide-spectrum functional layer with a discontinuous structure, and cooperates with the dielectric layer to achieve colorful structural colors in the visible light range; in the thermal infrared band, the effect of low infrared emissivity is achieved through the reflection of the resonant cavity, and the thermal radiation of the object itself is controlled, thereby achieving an infrared stealth effect; in the radar wave range, the discontinuous wide-spectrum functional layer cannot effectively reflect radar waves and cannot be detected, so the stealth effect of radar waves can be achieved. Therefore, the composite material provided by the present invention has visible, infrared and radar multi-band compatible stealth performance, and at the same time has the characteristics of light weight, flexibility, high strength, breathability, etc., and can be applied to organisms and equipment to meet multi-environment stealth requirements.

[0092] It should be understood that the above embodiments are merely illustrative of the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit and substance of the present invention are intended to be encompassed within the scope of protection of the present invention.

Claims

1. A visible light-thermal infrared-radar band compatible stealth composite material, characterized in that: It includes a woven layer, a wide spectrum functional layer and a transparent medium layer; The woven layer includes a plurality of fibers, with pores between adjacent fibers. The wide-spectrum functional layer is made of a metal and / or a nitride and has a thickness below a predetermined thickness, so that the wide-spectrum functional layers attached to the surfaces of the plurality of fibers independently form a discontinuous structure. The transparent medium layer covers the surface of the discontinuous structure and forms optical resonance with the discontinuous structure to produce structural color. The fiber diameter of the braided layer is 60-100 μm, the average pore width between the fibers is 30-70 μm, and the thickness of the wide-spectrum functional layer is 30-300 nm.

2. The visible light-thermal infrared-radar band compatible stealth composite material according to claim 1, characterized in that: The thickness of the transparent medium layer is 50-400 nm, and the structural color changes with the thickness of the transparent medium layer.

3. The visible light-thermal infrared-radar band compatible stealth composite material according to claim 1, characterized in that: The metal includes any one of gold, silver, copper, aluminum, tungsten, and titanium, or a combination of two or more thereof; the nitride includes any one of titanium nitride and zirconium nitride, or a combination of two thereof; And / or, the transparent medium layer includes any one or a combination of two or more of aluminum oxide, titanium oxide, tungsten oxide, zinc oxide, zirconium oxide, and niobium oxide.

4. The visible light-thermal infrared-radar band compatible stealth composite material according to claim 1, characterized in that: The surface of the transparent medium layer is further covered with a transparent protective layer, and the material of the transparent protective layer is a radar-transparent material.

5. The method for preparing the visible light-thermal infrared-radar band compatible stealth composite material according to any one of claims 1 to 4, characterized in that: include: The surface of the braided layer is plated with metal or nitride by physical sputtering to form a wide spectrum functional layer, and the thickness of the wide spectrum functional layer is controlled to be below a preset thickness; A transparent medium layer is continuously plated on the surface of the wide spectrum functional layer.

6. The preparation method according to claim 5, characterized in that The physical sputtering method includes any one or a combination of two or more of magnetron sputtering, vacuum evaporation, spin coating, and spray coating.

7. Application of the visible light-thermal infrared-radar band compatible stealth composite material according to any one of claims 1 to 4 in wide-band stealth.

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