Stealth material and application thereof

Abstract

The stealth material comprises an infrared reflection layer and a light regulation and control layer which are stacked, the infrared reflection layer is made of an infrared reflection material, the reflectivity of the infrared reflection layer in an infrared detection wave band is larger than 70%, and the light regulation and control layer comprises a visible light regulation and control material and an infrared selective transmission material. The visible light regulation and control material is used for regulating and controlling the color presented by the stealth material, the emissivity of the light regulation and control layer in an infrared detection wave band is smaller than 30%, and the emissivity of the light regulation and control layer in a wave band of 5-8 microns or / and a wave band of 14-20 microns is larger than 50%; when the stealth material is used, the infrared reflecting layer of the stealth material is close to a to-be-stealthy target object, and the light regulation and control layer is far away from the to-be-stealthy target object. The stealth material disclosed by the invention can realize stealth of visible light wave bands and infrared wave bands, and can realize heat balance between a target object and an external environment.

Description

Technical Field

[0001] The invention relates to a stealth material and application thereof, belonging to the field of optics. Background Art

[0002] In the fields of military, aerospace, meteorological observation, etc., camouflage technology is crucial. The main purpose of camouflage technology is to make the target object blend with the surrounding environment in terms of vision, thermal infrared, etc., so as to reduce the risk of detection and identification. With the development of science and technology, the requirements for camouflage technology are getting higher and higher. Not only camouflage should be achieved in the visible light band, but also in the mid-infrared band and far-infrared band to cope with detectors in different bands. At the same time, with the advancement of materials science, various detection and guidance methods are constantly being updated. In order to cope with enemy detection and not expose one's position, camouflage is extremely important. In the band that the human eye cannot see, camouflage is also needed to achieve consistency with the surrounding environment under the infrared detection instrument, which is infrared camouflage.

[0003] In the existing broadband low-emissivity traditional MIR camouflage, the radiant heat is blocked, which may cause thermal imbalance and increase the temperature of the object, which may not only cause thermal instability problems in the sample to be camouflaged, but also lead to enhanced detected signals. Existing multi-spectral camouflage work mainly focuses on the design of metamaterials. Since they all use metamaterials, the structure is relatively complex and the price of raw materials is relatively expensive. Summary of the invention

[0004] In order to solve at least one of the above problems, the present invention provides a stealth material, which has low emissivity in the infrared detection band, high emissivity in the non-atmospheric window, and a color that is the same or similar to the environment in the visible light band.

[0005] The technical solution adopted by the present invention is: a stealth material, including a stacked infrared reflection layer and a light regulation layer, the infrared reflection layer serves as the inner layer of the stealth material, and the light regulation layer serves as the outer layer of the stealth material, the infrared reflection layer has high reflection in the infrared band, especially in the infrared detection band, and the reflectivity is greater than 70%; the light regulation layer is used to regulate the light reflection performance of the invisible cloak in the visible light band and the light emission performance in the infrared band, and comprises a visible light regulation material and an infrared selective transmission material, the visible light regulation material is used to make the invisible cloak present the same or similar color as the environment, and the infrared selective transmission material makes the invisible cloak present high emission in the band that cannot be detected by the infrared detector, which is convenient for the target object to dissipate heat and achieve thermal equilibrium. In the present invention, the emissivity of the light regulation layer in the infrared detection band is less than 30%, and the emissivity in the non-infrared detection band (5-8um band and / or 14-20um band) is greater than 50%.

[0006] As a preferred embodiment, the infrared selectively transparent material in the present invention is polyhexamethylene adipamide (nylon 66), and its structural formula is:

[0007] The amide group in the formula has an obvious absorption peak at 5-8um, and no absorption at 3-5um and 8-14um. The crystal phase and crystal peak of the component work together to make the infrared selective transmission material have high emission at 5-8um and low emission at 3-5um and 8-14um.

[0008] As a preferred solution, the stealth material in the present invention can be a two-layer structure or a three-layer structure. When it is a two-layer structure, the light regulating layer is a mixed film layer of a visible light regulating material and an infrared selectively transparent material. The preparation method is: coating the light regulating material on the substrate by scraping, spin coating or other methods; the configuration method of the light regulating material is:

[0009] a. Preparing an infrared selective transmission material solution: dispersing poly(hexamethylene adipamide) in a mixed solution of formic acid and acetic acid to form a visible light regulation material solution, wherein the volume mixing ratio of formic acid to acetic acid is 1:1, and the concentration of poly(hexamethylene adipamide) in the visible light regulation material solution is 0.2 g / ml;

[0010] b. Prepare the light-regulating material solution: Add Fe to the infrared selectively transparent material solution. 2 O 3 、α-FeO(OH), Fe 4 [Fe(CN) 6 ] 3 One, two or three of the above are configured to obtain a light-regulating material solution of a desired color.

[0011] When the stealth material has a three-layer structure, the light regulation layer includes a visible light regulation layer and an infrared selective transmission layer, and the infrared selective transmission layer is placed between the infrared reflection layer and the visible light regulation layer, wherein the infrared selective transmission layer is prepared by electrostatic spinning, and the specific preparation method is as follows: first, 10g of nylon 66 plastic particles are dispersed in a mixed solution of 25mL of formic acid and acetic acid. Then, heat and stir at 40°C and 500rpm for 12h, so that the nylon 66 plastic particles are evenly dispersed in the mixed solution of formic acid and acetic acid. Subsequently, an electrostatic spinning machine is used, and the parameters of the minimum voltage -4V and the maximum voltage 21.5V are set to control the nylon 66 injection rate to 0.15mL / h. After spinning for 6h, a nylon 66 spinning membrane is obtained, and the spinning membrane is set on an aluminum foil. The visible light regulation layer is coated on the infrared selective transmission layer by spraying, and the preparation method of the visible light regulation layer is: configure a first liquid, a second liquid and a third liquid, and the first liquid is Fe 2 O 3 The second liquid is an ethanol solution of α-FeO(OH), and the third liquid is an ethanol solution of Fe4 [Fe(CN) 6 ] 3 ethanol solution; mixing the first solution, the second solution and the third solution in a set ratio to form a mixed pigment liquid; spraying the mixed pigment liquid on the infrared selective transmission layer.

[0012] As an implementable method, the infrared detection band is 3-5um and 8-14um, and the non-infrared detection band is 5-8um and 14-20um. In the present invention, the infrared reflection layer shows high reflection in both the infrared detection band and the non-infrared detection band, the visible light regulation layer shows high transmittance in both the infrared detection band and the non-infrared detection band, and the infrared selective transmission layer has low emissivity and high transmittance in the infrared detection band, and high emissivity in the non-infrared detection band.

[0013] As an implementable method, the stealth material has a three-layer structure, which is an infrared reflection layer, an infrared selective transmission layer, and a visible light regulation layer. The visible light regulation layer can obtain the corresponding color by the following combination: a(0.047gFe 2 O 3 +0.010gα-FeO(OH)) / ml; b(0.025gFe 4 [Fe(CN) 6 ] 3 +0.017gα-FeO(OH)) / ml; c(0.043gFe 2 O 3 +0.029gFe 4 [Fe(CN) 6 ] 3 ) / ml.

[0014] The present invention also provides an application of the stealth material, wherein the stealth material is made into a stealth cloak for use in military activities.

[0015] The beneficial effects produced by the present invention include: the stealth material in the present invention realizes stealth under visible light and infrared stealth through the synergistic effect of multi-spectral bands, and has high emission in the non-atmospheric window part, thereby achieving thermal balance while satisfying the stealth effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the structure of the stealth material in Example 1;

[0017] Figure 2 Optical images of spun membranes;

[0018] Figure 3(a) to Figure 3(i) Color effect diagram of the invisible cloak produced in Example 1-9 displayed under visible light;

[0019] Figure 4(a) to Figure 4(d) Color effect diagrams of the invisibility cloaks obtained in Examples 14-17 under visible light;

[0020] Figure 5 Infrared transmission spectrogram of polyhexamethylene adipamide;

[0021] Figure 6 Infrared transmission spectrograms of the raw materials of the visible light regulation layer;

[0022] Figure 7 Reflection spectrogram of the stealth material at 3-5um;

[0023] Figure 8 Reflection spectrogram of the stealth material at 8-14um;

[0024] Fig. 9 Emissivity required for the stealth material to achieve camouflage at 3-5um band for different temperatures and background emissivities; Fig.10 Emissivity required for the stealth material to achieve camouflage at 8-14um band for different temperatures and background emissivities;

[0025] Fig.11 Optical properties of spinning films with different thicknesses;

[0026] Fig.12 Reflectance of the stealth materials obtained in Examples 1-3 under visible light;

[0027] Fig.13 Reflectance of the stealth materials obtained in Examples 1-3 under infrared light;

[0028] Fig.14 Reflectance of the stealth materials obtained in Examples 4-6 under visible light;

[0029] Fig.15 Reflectance of the stealth materials obtained in Examples 4-6 under infrared light;

[0030] Fig.16 Reflectance of the stealth materials obtained in Examples 7-9 under visible light;

[0031] Fig.17 Reflectance of the stealth materials obtained in Examples 17-19 under infrared light;

[0032] Fig.18 Infrared camouflage effect diagram of the stealth material at 3-5um;

[0033] Fig.19 Infrared camouflage effect diagram of the stealth material at 8-14um;

[0034] Fig. 20 、 Fig.21Thermal balance diagram of stealth material under outdoor conditions;

[0035] Fig. 22 Color renderings of different pigments;

[0036] Fig.23 The invisible effect of invisible materials in the jungle under visible light;

[0037] Fig.24 The stealth effect of stealth material in the jungle under infrared light. DETAILED DESCRIPTION

[0038] The present invention is further explained in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments. Unless otherwise specified, all raw materials of the present invention are not particularly limited to their purity, and the present invention preferably adopts analytically pure. All raw materials of the present invention, their sources and abbreviations belong to conventional sources and abbreviations in this field, and are clear and definite in the field of their related uses. Those skilled in the art can purchase them from the market or prepare them by conventional methods according to the abbreviations and corresponding uses. All percentages of the present invention are mass percentages unless otherwise specified, and the solutions are all water-based solvents unless otherwise specified.

[0039] Example 1

[0040] Stealth materials such as Figure 1 As shown, it includes an infrared reflection layer 1, an infrared selective transmission layer 2 and a visible light regulation layer 3, the infrared reflection layer is an aluminum foil with a thickness of 20um, and the preparation method of the stealth material is:

[0041] (1) dispersing 10 g of poly(hexamethylene adipamide) plastic particles in a solvent to form a mixed solution, wherein the solvent is a mixture of 25 mL of formic acid and 25 mL of acetic acid;

[0042] (2) heating and stirring the mixed solution at 40° C. and 500 rpm for 12 h, so that the polyhexamethylene adipamide plastic particles are evenly dispersed in formic acid and acetic acid to obtain a spinning solution;

[0043] (3) Using an electrospinning machine, the minimum voltage of the electrospinning machine was set to -4 V, the maximum voltage was set to 21.5 V, the injection rate of the spinning solution was set to 0.15 mL / h, and after spinning for 6 hours, a spinning membrane with a thickness of 45 μm was obtained, i.e., an infrared selective permeable membrane. The optical photograph of the infrared selective permeable membrane is shown in FIG. Figure 2 .

[0044] (4) The spinning membrane is supported on one side of the aluminum foil.

[0045] (5) A 0.067 g / ml iron oxide solution was prepared as a visible light regulation material solution. The iron oxide solution was sprayed on the side of the spinning membrane facing away from the aluminum foil using a spray gun. The spraying amount ω was 3.8%, forming a visible light regulation layer. The color was shown in FIG3(a).

[0046]

[0047] Among them, M 1 is the mass of the sample before spraying the paint, M 2 It is the mass of the sample after spraying the paint.

[0048] Embodiments 2 to 9

[0049] The visible light regulating material solution in Example 1 is changed to enable the invisibility cloak to achieve invisibility in different environments. The components and concentration of the visible light regulating solution, the spraying amount and the color of the invisibility cloak are shown in Table 1.

[0050]

[0051] Embodiments 10 to 13

[0052] The electrospinning time in Example 1 was adjusted to obtain spinning membranes of different thicknesses. The electrospinning times in Examples 10 to 13 were 2 h, 4 h, 8 h, and 10 h, respectively, and the obtained spinning membranes had thicknesses of 15 μm, 30 μm, 60 μm, and 75 μm, respectively.

[0053] Examples 14-17

[0054] The stealth material in this embodiment comprises two layers, namely an infrared reflection layer and a light regulation layer. The infrared reflection layer is an aluminum foil. The light regulation layer is formed by scraping a light regulation solution on the infrared reflection layer. The preparation method comprises the following steps:

[0055] (1) dispersing 10 g of poly(hexamethylene adipamide) plastic particles in a solvent to form a mixed solution, wherein the solvent is a mixture of 25 mL of formic acid and 25 mL of acetic acid;

[0056] (2) heating and stirring the mixed solution at 40° C. and 500 rpm for 12 h, so that the poly(hexamethylene adipamide) plastic particles are evenly dispersed in the formic acid and acetic acid to obtain an infrared selectively transparent solution;

[0057] (3) According to Table 2, corresponding components and dosages are added to the infrared selective transmission solution to obtain a light regulating solution. (4) The light regulating solution is scraped onto an aluminum foil with a coating thickness as shown in Table 2, and dried to obtain an invisible cloak.

[0058] Table 2

[0059]

[0060] Optical performance test

[0061] Test the optical properties of various raw materials of stealth materials, such as Figure 5 and Figure 6 As shown, Figure 5 This is the infrared transmission diagram of polyhexamethylene adipamide. It can be seen that the axial deformation of C=O, axial deformation of C-N and angular deformation of CO-N-H in the molecular structure of polyhexamethylene adipamide, as well as the crystal phase and crystallization peak of the material make the material have an obvious absorption peak at 5-8um. Figure 6 The infrared transmission diagram of each raw material of the visible light regulation layer shows that Fe 2 O 3 , Fe 4 [Fe(CN) 6 ] 3 , α-FeO(OH) has basically no absorption in the entire infrared band, the raw material or mixture of raw materials of the visible light regulation layer is transparent in the infrared band, and does not affect the camouflage of the stealth material in the infrared band.

[0062] The optical properties of the stealth material obtained in Example 1 are tested. Figure 7 and Figure 8 It can be seen that the stealth material prepared in this embodiment has a reflectivity of nearly 90% and 80% in the two atmospheric window bands of 3-5um and 8-14um respectively (e.g. Figure 7 ), with an emissivity of nearly 60% in the 5-8um non-atmospheric window band (e.g. Figure 8 ).

[0063] The emissivity of the stealth material obtained in Test Example 1 changes with temperature and background emissivity, as shown in Fig. 9 and Fig.10 As shown, it can be seen that under different conditions of temperature and background emissivity, the emissivity required for an object to achieve complete infrared stealth in the two atmospheric window bands of 3-5um and 8-14um is different.

[0064] The optical properties of the spun membranes obtained in Example 1 and Examples 10-13 were tested. Fig.11 As shown, it can be seen that the spinning membranes of different thicknesses all show obvious absorption peaks in the 5-8 μm band and can achieve high emissivity in this band.

[0065] The optical properties of the stealth materials prepared in Examples 1-3 were tested. Fig.12 is the visible spectrum of the stealth material, Fig.13 is the infrared spectrum of the stealth material. It can be seen that as Fe 2 O 3 As the spraying amount increases, the stealth material can still maintain good infrared properties.

[0066] The optical properties of the stealth materials prepared in Examples 4-6 were tested. Fig.14 is the visible spectrum of the stealth material, Fig.15 is the infrared spectrum of the stealth material. It can be seen that with the increase of the α-FeO(OH) spraying amount, the stealth material can still maintain good infrared properties.

[0067] The optical properties of the stealth materials prepared in Examples 7-9 were tested. Fig.16 is the visible spectrum of the stealth material, Fig.17 is the infrared spectrum of the stealth material. It can be seen that as Fe 4 [Fe(CN) 6 ] 3 As the spraying amount increases, the stealth material can still maintain good infrared properties.

[0068] The experimental group and the blank group were set to test the infrared camouflage performance of the stealth material at 3-5um and 8-14um. The experimental group used the stealth material prepared in Example 1 to cover the heat conductor, and the temperature of the heat conductor was higher than the ambient temperature. The blank group was the heat conductor without the stealth material. The infrared camouflage performance at 3-5um and 8-14um was as follows: Fig.18 and Fig.19 As shown, the implementation group exhibits infrared detection signals that are more similar to the environment in both bands compared to the blank group.

[0069] An experimental group, a control group, and a blank group were set up to test the radiative cooling performance of the stealth material. The experimental group used the stealth material prepared in Example 1 to cover the target object, the control group used aluminum foil to cover the target object, and the blank group did not cover the target object. The temperature of the target object in each group was tested under outdoor conditions. The results are as follows: Fig. 20 and Fig.21 As shown by Fig. 20 It can be seen that the temperature of the experimental group is nearly 10°C lower than that of the control group, which means that the setting of the spinning membrane helps to improve the radiation cooling performance of the stealth material, reduce the temperature of the target object, and achieve thermal balance. Fig.21 It can be seen that, while maintaining the same temperature, the experimental group has a higher heating power than the control group, and the heating power of the experimental group is closer to the heating power of the blank group, which further verifies the radiation cooling performance of the spinning membrane.

[0070] Iron oxide (Fe 2 O 3 ), Prussian blue (Fe 4 [Fe(CN) 6 ] 3 ), goethite (α-FeO(OH)) as the basic raw materials, and different colors are obtained by adjusting the ratio of each raw material. The pigment components and corresponding colors are as follows

[0071] Table 2. The color column in Table 2 corresponds to Fig. 22 Colors shown.

[0072]

[0073] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A stealth material, characterized in that: It includes a stacked infrared reflection layer and a light regulation layer, wherein the infrared reflection layer is formed of an infrared reflection material, the reflectivity of the infrared reflection layer in the infrared detection band is greater than 70%, the light regulation layer includes a visible light regulation material and an infrared selective transmission material, the visible light regulation material is used to regulate the color presented by the stealth material, the emissivity of the light regulation layer in the infrared detection band is less than 30%, and the emissivity in the 5-8um band and / or the 14-20um band is greater than 50%; when in use, the infrared reflection layer of the stealth material is close to the target object to be invisible, and the light regulation layer is far away from the target object to be invisible.

2. The stealth material according to claim 1, characterized in that: The infrared selective transmission material is polyhexamethylene adipamide, and the infrared reflection material is aluminum foil.

3. The stealth material according to claim 1, characterized in that: The visible light regulating material and the infrared selective transmission material are mixed to form the light regulating layer.

4. The stealth material according to claim 3, characterized in that: The infrared reflective material is an aluminum foil, and a light regulating material is coated on the aluminum foil with the aluminum foil as a substrate. The light regulating material is a mixed material of the infrared selective transmission material and the visible light regulating material. The coating method of the light regulating material comprises the following steps: Preparing an infrared selective transmission material solution: dispersing poly(hexamethylene adipamide) in a mixed solution of formic acid and acetic acid to form a visible light regulation material solution, wherein the volume mixing ratio of formic acid to acetic acid is 1:1, and the concentration of poly(hexamethylene adipamide) in the visible light regulation material solution is 0.2 g / ml; Add one, two or three of Fe2O3, α-FeO(OH) and Fe4[Fe(CN)6]3 to the infrared selective transmission material solution in a set ratio, and mix them evenly to obtain a light regulation material solution; Mixing the visible light regulating material solution and the infrared selective transmission material solution to form a light regulating material solution; The light regulating material solution is coated on the aluminum foil.

5. The stealth material according to claim 1, characterized in that: The visible light regulating material forms a visible light regulating layer, the infrared selectively transmitting material forms an infrared selectively transmitting layer, and the stealth material includes the infrared reflecting layer, the infrared selectively transmitting layer, and the visible light regulating layer stacked in sequence. The emissivity of the visible light regulating layer in the infrared detection band is less than 30%, and the emissivity in the 5-8um band and / or the 14-20um band is less than 30%; the emissivity of the infrared selectively transmitting layer in the infrared detection band is less than 30%, and the emissivity in the 5-8um band and / or the 14-20um band is greater than 70%.

6. The stealth material according to claim 5, characterized in that: The preparation method of the infrared selective transmission layer is as follows: a. dispersing poly(hexamethylene adipamide) in a mixed solution of formic acid and acetic acid to form a spinning solution, wherein the volume mixing ratio of formic acid to acetic acid is 1:1, and the concentration of poly(hexamethylene adipamide) in the spinning solution is 0.2 g / ml; b. The spinning solution is spun using an electrostatic spinning process to obtain an infrared selective transmission layer.

7. The stealth material according to claim 5, characterized in that: The preparation method of the visible light regulation layer comprises: preparing a first liquid, a second liquid and a third liquid, wherein the first liquid is an ethanol solution of Fe2O3, the second liquid is an ethanol solution of α-FeO(OH), and the third liquid is an ethanol solution of α-FeO(OH); Mixing the first solution, the second solution and the third solution in a set ratio to form a mixed pigment solution; The mixed pigment liquid is sprayed on the infrared selective transmission layer.

8. The stealth material according to claim 1, characterized in that: The infrared detection band is 3-5um and / or 8-14um.

9. The stealth material according to any one of claims 1 to 8, characterized in that: The visible light regulating material includes Fe2O3, Fe4[Fe(CN)6]3, and α-FeO(OH), and the Fe2O3, Fe4[Fe(CN)6]3, and α-FeO(OH) are mixed in a set ratio to form the visible light regulating material.

10. An application of the stealth material according to claim 1, characterized in that: The stealth material serves as an invisible cloak.

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