Multi-spectral compatible stealth coating based on high entropy alloy and preparation method thereof

Abstract

The present invention discloses a multi-spectral compatible stealth coating based on a high-entropy alloy and a preparation method thereof, belonging to the technical field of functional high-entropy alloy coatings and their preparation. The present invention solves the problem of poor visible light and infrared stealth effects achieved in a wide spectral range in existing stealth coatings. The present invention utilizes magnetron sputtering technology to prepare high-entropy alloy films, and through scientific screening and optimized combination of elements, and by regulating magnetron sputtering parameters, efficient customization of material composition and structure is achieved, thereby obtaining a uniform, dense and high-performance high-entropy alloy film. Test results show that the high-entropy alloy coating has an absorptivity of approximately 0.95 in the visible light band and an emissivity of approximately 0.05 in the infrared band, achieving multi-spectral compatible stealth in the visible and infrared spectral ranges.

Description

Technical Field

[0001] The present invention relates to a multi-spectral compatible stealth coating based on a high-entropy alloy and a preparation method thereof, belonging to the technical field of functional high-entropy alloy coatings and preparation methods thereof. Background Art

[0002] The core goal of stealth technology is to reduce the optical visibility of a target, thereby avoiding detection by enemy or reconnaissance equipment. Existing stealth coating technologies primarily target targets by engineering their optical absorption properties to reduce reflection and radiation from targets in different spectral regions. However, existing stealth coatings face several technical challenges, particularly in light absorption and radiation control within the visible and infrared spectral ranges.

[0003] Traditional stealth coatings are often made of metals, ceramics, or composite materials. These materials have a certain light-absorbing capacity, but are usually only effective in a specific spectral range (such as visible light or infrared). For example, a black coating can effectively absorb visible light but has a poor effect on radiation suppression in the infrared spectral range, and vice versa.

[0004] With the emergence of high-entropy alloys (HEAs), due to their unique chemical composition and structural characteristics, they have gradually become a research hotspot for improving the optical properties of coatings. HEAs are composed of five or more main elements, and their diversified element configuration gives the material excellent physical and chemical properties, such as high thermal stability, good oxidation resistance, and durability at high temperatures. More importantly, HEAs can provide strong light absorption capabilities over a wide spectral range by adjusting the element composition and ratio. However, existing HEA-based stealth coatings are usually only effective in specific spectral ranges. Some coatings have good absorption performance in the visible light band, but weak emission performance in the infrared band, resulting in the inability to achieve a comprehensive stealth effect. In addition, although existing HEA coatings can reduce reflection, their radiation emission suppression effect is not significant. Especially in the infrared spectral range, the radiation emissivity of the coating is high, which easily exposes the target.

[0005] In the preparation of coating materials, magnetron sputtering technology has been widely used to prepare thin films. The main parameters of magnetron sputtering include operating pressure, target voltage, target current density, and deposition rate. Sputtering power is a critical process parameter in magnetron sputtering, directly affecting the deposition rate and quality of the film. The higher the sputtering power, the greater the plasma density on the target surface and the higher the sputtering rate. However, excessive sputtering power can lead to more defects within the film, such as bubbles and lattice distortion, which can affect film quality. The deposition rate affects the migration time of sputtered atoms on the substrate surface, thereby influencing factors such as the number of nuclei formed, internal film stress, and surface roughness. Too low a deposition rate results in prolonged atomic migration time, which easily leads to the formation of larger grains and a rough surface. Too high a deposition rate leads to excessive nucleation, increased internal stress, and an increase in defects. At high sputtering power, the coating exhibits higher hardness, smaller grain size, and a denser microstructure.

[0006] Therefore, it is essential to prepare a high-entropy alloy-based stealth coating with dual stealth performance in both the visible and infrared spectral ranges. Based on this, the present invention proposes a new material based on a high-entropy alloy. This material combines the excellent optical properties, thermal stability, and structural control capabilities of high-entropy alloys. Through the rational design of the high-entropy alloy composition, the adjustment of the coating structure, and the control of the preparation process, it can achieve excellent visible light and infrared stealth effects across a wide spectral range, thus addressing the shortcomings of the existing technology. Summary of the Invention

[0007] In order to solve the problem of poor visible light and infrared stealth effects achieved by existing stealth coatings within a wide spectral range, the present invention provides a multi-spectral compatible stealth coating based on high entropy alloy and a preparation method thereof.

[0008] The technical solution of the present invention:

[0009] One of the objects of the present invention is to provide a multi-spectral compatible stealth coating based on a high-entropy alloy, which is a high-entropy alloy coating composed of any five elements of Al, Ti, Au, Ag, Cu, Cr, W, Mo, V, Fe, Co, Ni, Mn, La, Ce, Pr, Yb, Lu, Sc, and Y in an atomic percentage ratio of 1:1:1:1:1.

[0010] It is further defined that the coating consists of Al, Cr, Ti, W and Y.

[0011] The second object of the present invention is to provide a method for preparing the above-mentioned multi-spectral compatible stealth coating based on high-entropy alloy, which comprises: using a high-entropy alloy prepared by using powders of any five elements among Al, Ti, Au, Ag, Cu, Cr, W, Mo, V, Fe, Co, Ni, Mn, La, Ce, Pr, Yb, Lu, Sc, and Y as raw materials as a target material, and adopting magnetron sputtering technology to form a high-entropy alloy coating on a metal substrate.

[0012] It is further defined that the method comprises the following steps:

[0013] (1) Clean the impurities on the surface of the metal substrate with deionized water, then perform ultrasonic cleaning with anhydrous ethanol and dry;

[0014] (2) The metal substrate treated in (1) is placed in a magnetron sputtering chamber, and a high entropy alloy target is sputtered on the metal substrate in an argon atmosphere to form a stealth coating with a thickness of 40 to 90 nm.

[0015] It is further defined that the sputtering conditions of (2) are: the metal substrate is 25°C, the sputtering power is 80W-160W, the sputtering time is 5min, the argon gas intake volume is 20sccm, and the vacuum degree is 0.8Pa.

[0016] The third object of the present invention is to provide a method for preparing a high entropy alloy target used in the above-mentioned preparation method, which specifically comprises: using any five element powders of Al, Ti, Au, Ag, Cu, Cr, W, Mo, V, Fe, Co, Ni, Mn, La, Ce, Pr, Yb, Lu, Sc, and Y as raw materials, melting and casting them into an ingot in an atomic percentage ratio of 1:1:1:1:1, then crushing and grinding the ingot into a powder, and then isostatically pressing the alloy powder, and then sintering at a high temperature to obtain a round AlCrTiWY target.

[0017] The fourth object of the present invention is to provide another multi-spectral compatible stealth coating based on high entropy alloy, specifically the coating is composed of the above-mentioned high entropy alloy coating and an Al2O3, SiO2 or Si3N4 transparent oxide layer stacked on its surface.

[0018] It is further defined that the thickness of the transparent oxide layer is 100 nm.

[0019] The fifth object of the present invention is to provide a method for preparing the above-mentioned multi-spectral compatible stealth coating based on high entropy alloy, specifically using magnetron sputtering technology to sputter a transparent oxide layer on the surface of the high entropy alloy coating.

[0020] It is further defined that the conditions for sputtering the transparent oxide layer are: using Al2O3, SiO2 or Si3N4 powder as the target material, the temperature of the sample to be sputtered is 25°C, the power is 120W, the time is 5h, the argon gas intake volume is 30sccm, and the vacuum degree is 1.0Pa.

[0021] A sixth object of the present invention is to provide an application of the multi-spectral compatible stealth coating based on high entropy alloy, specifically for compatible stealth in the visible light and infrared spectral ranges.

[0022] Beneficial effects:

[0023] The present invention provides a method for preparing high-entropy alloy thin films using magnetron sputtering technology. By scientifically screening and optimizing the combination of elements and regulating magnetron sputtering parameters, efficient customization of material composition and structure is achieved, resulting in uniform, dense, and high-performance high-entropy alloy thin films. Compared to existing technologies, the present invention also has the following advantages:

[0024] (1) The present invention uses high entropy alloy (HEA) as the target material. By precisely designing the alloy composition and multilayer film structure, the spectral selective absorption and radiation performance are optimized, achieving dual optimization in the visible light and infrared bands. Specifically, the low radiation characteristics of Al, Au, and Ag are utilized to make the high entropy alloy exhibit lower radiation emission in the infrared band, further optimizing the stealth performance. Elements such as Cr, Ti, W, Mo, V, Fe, Co, Ni, and Mn can significantly enhance the absorption capacity of the material in the visible light band, especially the dd transition mechanism of Ti and Cr elements helps to improve the absorption intensity of the material in the visible light range. In addition, W, Mo, and V, as important elements in high entropy alloys, have extremely high thermal stability and radiation resistance, which can improve the performance of the material in high temperature environments. The introduction of aluminum effectively reduces the radiation emissivity in the infrared band, and La, Ce, Pr, Yb, Lu, Sc, and Y have excellent mechanical properties and chemical stability, and can work stably for a long time in extreme environments such as space, which makes high entropy alloys have unique advantages in spacecraft stealth coatings. The unique electronic and crystal structures of these elements give the coating a high absorptivity in the visible light band, especially in the range of 0.38μm to 0.80μm, where the absorptivity can reach over 0.9. This enables the coating to effectively absorb visible light radiation, improving the efficiency of photothermal conversion and is widely used in fields such as solar thermal collection and photothermal conversion.

[0025] (2) The present invention can control the microstructure of the coating to achieve the desired optical and physical properties by optimizing the sputtering deposition parameters. The stealth coating obtained by adopting a multi-layer structure has an extremely high absorptivity of about 0.95 in the visible light band (wavelength range of 0.38μm to 0.80μm) and an extremely low emissivity of about 0.05 in the infrared band (infrared window range of 3μm to 14μm). The low emissivity effectively suppresses the leakage of thermal radiation and improves the thermal shielding performance of the material. While maintaining the stealth effect, it can also effectively manage the heat load in a high temperature environment. In order to ensure the stability of the coating during long-term use, the high entropy alloy coating of the present invention has good thermal stability, avoids shedding or thermal stress problems in high temperature or extreme environments, and ensures long-term reliability and service life.

[0026] (3) The high-entropy alloy coating provided by the present invention combines the advantages of high visible light absorptivity and low infrared emissivity, and can effectively achieve light-to-heat conversion, stealth protection, and thermal management. It is widely used in fields such as solar thermal collection, infrared stealth coating, and aerospace, and has important application prospects. It also has excellent thermal stability and can be used for a long time in high-temperature environments while maintaining its optical properties. This makes the technology applicable to fields such as aerospace, military stealth, optical coatings, and high-temperature radiation control. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of the stealth coating structure provided by the present invention;

[0028] Figure 2 Visible light reflection spectra of the high entropy alloy coatings prepared in Example 3 and Comparative Example 1;

[0029] Figure 3 The infrared light reflection spectra of the high entropy alloy coatings prepared in Example 3 and Comparative Example 1 are shown;

[0030] Figure 4 This is a SEM photo of the high entropy alloy coating prepared in Example 3;

[0031] Figure 5 This is the SEM photograph of the high entropy alloy coating prepared in Comparative Example 1. DETAILED DESCRIPTION

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0033] 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. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0034] Secondly, the term "one embodiment" or "embodiment" 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 various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0035] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, methods, and instruments used are conventional in the art and can be obtained commercially by those skilled in the art unless otherwise specified.

[0036] Example 1

[0037] (1) Preparation of high entropy alloy target AlCrTiWY:

[0038] Al, Cr, Ti, W, and Y metal powders were mixed in a ratio of 1:1:1:1:1 atomic percent, smelted at 980°C for 240 minutes, and cast into an ingot. The ingot was then crushed and ground into a powder, which was then passed through a 240-mesh sieve to obtain an alloy powder. The alloy powder was placed in a mold and isostatically pressed at 12T for 180 minutes to obtain a circular AlCrTiWY target with a diameter of 50 mm and a height of 5 mm.

[0039] (2) Substrate cleaning:

[0040] Prepare the Al substrate material. Before sputtering, clean the substrate. First, use deionized water to clean any surface debris. Then, soak it in an ultrasonic cleaner with anhydrous ethanol for 20 minutes. Finally, dry the surface with a hair dryer. Place the treated substrate on the sample stage in the magnetron sputtering chamber and secure it securely.

[0041] (3) Sputtering AlCrTiWY layer on substrate material using magnetron sputtering method:

[0042] In an argon atmosphere, the high entropy alloy target AlCrTiWY was sputtered onto the substrate material. The sputtering conditions were: substrate temperature of 25°C, sputtering power of 80W, sputtering time of 5min, argon gas intake of 20sccm, and vacuum degree of 0.8Pa. A 45nm thick AlCrTiWY layer was formed to obtain a single-layer stealth coating.

[0043] (4) Sputtering Al2O3 layer on AlCrTiWY layer by magnetron sputtering method:

[0044] In an argon atmosphere, the target material Al2O3 was sputtered on the AlCrTiWY layer. The sputtering conditions were: substrate temperature of 25°C, sputtering power of 200W, sputtering time of 5h, argon gas flow rate of 30sccm, vacuum degree of 1.0Pa, and an Al2O3 layer with a thickness of 75nm was formed. Figure 1 Multi-layer stealth coating shown.

[0045] Example 2

[0046] (1) Preparation of high entropy alloy target AlCrTiWY:

[0047] Al, Cr, Ti, W, and Y metal powders were mixed in a ratio of 1:1:1:1:1 atomic percent, smelted at 980°C for 240 minutes, and cast into an ingot. The ingot was then crushed and ground into a powder, which was then passed through a 240-mesh sieve to obtain an alloy powder. The alloy powder was placed in a mold and isostatically pressed at 12T for 180 minutes to obtain a circular AlCrTiWY target with a diameter of 50 mm and a height of 5 mm.

[0048] (2) Substrate cleaning:

[0049] Prepare the Al substrate material. Before sputtering, clean the substrate. First, use deionized water to clean any surface debris. Then, soak it in an ultrasonic cleaner with anhydrous ethanol for 20 minutes. Finally, dry the surface with a hair dryer. Place the treated substrate on the sample stage in the magnetron sputtering chamber and secure it securely.

[0050] (3) Sputtering AlCrTiWY layer on substrate material using magnetron sputtering method:

[0051] In an argon atmosphere, the high entropy alloy target AlCrTiWY was sputtered onto the substrate material. The sputtering conditions were: substrate temperature of 25°C, sputtering power of 100W, sputtering time of 5min, argon gas intake of 20sccm, and vacuum degree of 0.8Pa. A 55nm thick AlCrTiWY layer was formed to obtain a single-layer stealth coating.

[0052] (4) Sputtering Al2O3 layer on AlCrTiWY layer by magnetron sputtering method:

[0053] In an argon atmosphere, the target material Al2O3 is sputtered on the AlCrTiWY layer. The sputtering conditions are: substrate temperature of 25°C, sputtering power of 200W, sputtering time of 5h, argon gas intake of 30sccm, vacuum degree of 1.0Pa, forming an Al2O3 layer with a thickness of 75nm to obtain a multi-layer stealth coating.

[0054] Example 3

[0055] (1) Preparation of high entropy alloy target AlCrTiWY:

[0056] Al, Cr, Ti, W, and Y metal powders were mixed in a ratio of 1:1:1:1:1 atomic percent, smelted at 980°C for 240 minutes, and cast into an ingot. The ingot was then crushed and ground into a powder, which was then passed through a 240-mesh sieve to obtain an alloy powder. The alloy powder was placed in a mold and isostatically pressed at 12T for 180 minutes to obtain a circular AlCrTiWY target with a diameter of 50 mm and a height of 5 mm.

[0057] (2) Substrate cleaning:

[0058] Prepare the Al substrate material. Before sputtering, clean the substrate. First, use deionized water to clean any surface debris. Then, soak it in an ultrasonic cleaner with anhydrous ethanol for 20 minutes. Finally, dry the surface with a hair dryer. Place the treated substrate on the sample stage in the magnetron sputtering chamber and secure it securely.

[0059] (3) Sputtering AlCrTiWY layer on substrate material using magnetron sputtering method:

[0060] In an argon atmosphere, the high entropy alloy target AlCrTiWY was sputtered onto the substrate material. The sputtering conditions were: substrate temperature of 25°C, sputtering power of 120W, sputtering time of 5min, argon gas intake of 20sccm, vacuum degree of 0.8Pa, forming an AlCrTiWY layer with a thickness of 75nm to obtain a single-layer stealth coating.

[0061] (4) Sputtering Al2O3 layer on AlCrTiWY layer by magnetron sputtering method:

[0062] The target material Al2O3 was sputtered onto the AlCrTiWY layer in an argon atmosphere. The sputtering conditions were: substrate temperature of 25°C, sputtering power of 200W, sputtering time of 5h, argon gas intake of 30sccm, and vacuum degree of 1.0Pa. A 75nm thick Al2O3 layer was formed to obtain a multilayer stealth coating named AlCrTiWY / Al2O3.

[0063] Example 4

[0064] (1) Preparation of high entropy alloy target AlCrTiWY:

[0065] Al, Cr, Ti, W, and Y metal powders were mixed in a ratio of 1:1:1:1:1 atomic percent, smelted at 980°C for 240 minutes, and cast into an ingot. The ingot was then crushed and ground into a powder, which was then passed through a 240-mesh sieve to obtain an alloy powder. The alloy powder was placed in a mold and isostatically pressed at 12T for 180 minutes to obtain a circular AlCrTiWY target with a diameter of 50 mm and a height of 5 mm.

[0066] (2) Substrate cleaning:

[0067] Prepare the Al substrate material. Before sputtering, clean the substrate. First, use deionized water to clean any surface debris. Then, soak it in an ultrasonic cleaner with anhydrous ethanol for 20 minutes. Finally, dry the surface with a hair dryer. Place the treated substrate on the sample stage in the magnetron sputtering chamber and secure it securely.

[0068] (3) Sputtering AlCrTiWY layer on substrate material using magnetron sputtering method:

[0069] In an argon atmosphere, the high entropy alloy target AlCrTiWY was sputtered onto the substrate material. The sputtering conditions were: substrate temperature of 25°C, sputtering power of 140W, sputtering time of 5min, argon gas intake of 20sccm, and vacuum degree of 0.8Pa. A 100nm thick AlCrTiWY layer was formed to obtain a single-layer stealth coating.

[0070] (4) Sputtering Al2O3 layer on AlCrTiWY layer by magnetron sputtering method:

[0071] In an argon atmosphere, the target material Al2O3 is sputtered on the AlCrTiWY layer. The sputtering conditions are: substrate temperature of 25°C, sputtering power of 200W, sputtering time of 5h, argon gas intake of 30sccm, vacuum degree of 1.0Pa, forming an Al2O3 layer with a thickness of 75nm to obtain a multi-layer stealth coating.

[0072] Example 5

[0073] (1) Preparation of high entropy alloy target AlCrTiWY:

[0074] Al, Cr, Ti, W, and Y metal powders were mixed in a ratio of 1:1:1:1:1 atomic percent, smelted at 980°C for 240 minutes, and cast into an ingot. The ingot was then crushed and ground into a powder, which was then passed through a 240-mesh sieve to obtain an alloy powder. The alloy powder was placed in a mold and isostatically pressed at 12T for 180 minutes to obtain a circular AlCrTiWY target with a diameter of 50 mm and a height of 5 mm.

[0075] (2) Substrate cleaning:

[0076] Prepare the Al substrate material. Before sputtering, clean the substrate. First, use deionized water to clean any surface debris. Then, soak it in an ultrasonic cleaner with anhydrous ethanol for 20 minutes. Finally, dry the surface with a hair dryer. Place the treated substrate on the sample stage in the magnetron sputtering chamber and secure it securely.

[0077] (3) Sputtering AlCrTiWY layer on substrate material using magnetron sputtering method:

[0078] In an argon atmosphere, the high entropy alloy target AlCrTiWY was sputtered onto the substrate material. The sputtering conditions were: substrate temperature of 25°C, sputtering power of 160W, sputtering time of 5min, argon gas intake of 20sccm, vacuum degree of 0.8Pa, forming an AlCrTiWY layer with a thickness of 125nm to obtain a single-layer stealth coating.

[0079] (4) Sputtering Al2O3 layer on AlCrTiWY layer by magnetron sputtering method:

[0080] In an argon atmosphere, the target material Al2O3 is sputtered on the AlCrTiWY layer. The sputtering conditions are: substrate temperature of 25°C, sputtering power of 200W, sputtering time of 5h, argon gas intake of 30sccm, vacuum degree of 1.0Pa, forming an Al2O3 layer with a thickness of 75nm to obtain a multi-layer stealth coating.

[0081] Comparative Example 1

[0082] The difference between this comparative example and Example 3 is that the Al2O3 layer is not sputtered on the AlCrTiWY layer, and the remaining process steps and parameter settings are the same as those in Example 3, obtaining a single-layer stealth coating named AlCrTiWY.

[0083] Effect Examples

[0084] (1) Lambda950 was used to measure the visible light absorption performance of the multilayer stealth coating (AlCrTiWY / Al2O3) obtained in Example 3 and the single-layer stealth coating (AlCrTiWY) obtained in Comparative Example 1. The results are as follows: Figure 2 As shown in the figure, it can be seen that the absorption rate of AlCrTiWY / Al2O3 in the 0.38μm to 0.8μm band is about 0.95. The absorption rate of AlCrTiWY in the 0.38μm to 0.8μm band is about 0.8.

[0085] (2) The infrared reflection spectra of the multilayer stealth coating (AlCrTiWY / Al2O3) obtained in Example 3 and the single-layer stealth coating (AlCrTiWY) obtained in Comparative Example 1 were tested using an FTIR infrared spectrometer. The results were as follows: Figure 3 As shown in the figure, it can be seen that the emissivity of AlCrTiWY / Al2O3 in the 3μm~14μm band is about 0.05. The emissivity of AlCrTiWY in the 3μm~14μm band is about 0.04.

[0086] (3) The microscopic surface morphology of the coating obtained in Example 3 was characterized. The results are as follows Figure 4 As shown in the figure, the coating surface is smooth, uniform and dense, without obvious holes and defects, and it can be seen that the coating is formed by alloy nanoparticles with a size of 5nm to 20nm uniformly arranged on the substrate material. The microscopic surface morphology of the single-layer stealth coating obtained in Comparative Example 3 is shown in Figure 5 As shown in the figure, the particles of the single-layer film are smaller than those of the double-layer film, and the rest of the microscopic surface morphology is not much different from that of the coating obtained in Example 3, which shows that sputtering the Al2O3 layer on the AlCrTiWY layer has little effect on the microscopic morphology.

[0087] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A stealth coating, characterized in that: The coating consists of a high-entropy alloy coating composed of five elements, Al, Cr, Ti, W and Y, in an atomic percentage ratio of 1:1:1:1:1, and an Al2O3, SiO2 or Si3N4 transparent oxide layer stacked on the surface of the high-entropy alloy coating.

2. The stealth coating according to claim 1, characterized in that The thickness of the transparent oxide layer is 100 nm.

3. A method for preparing a stealth coating according to any one of claims 1 to 2, characterized in that: A high-entropy alloy coating is formed on a metal substrate using magnetron sputtering technology using a high-entropy alloy target made from powders of five elements: Al, Cr, Ti, W, and Y. A transparent oxide layer is sputtered on the surface of the high entropy alloy coating using magnetron sputtering technology.

4. The preparation method according to claim 3, characterized in that The preparation of high entropy alloy coating includes: (1) Use deionized water to clean the impurities on the surface of the metal substrate, then use anhydrous ethanol for ultrasonic cleaning and dry; (2) The metal substrate treated in (1) is placed in a magnetron sputtering chamber, and a high entropy alloy target is sputtered on the metal substrate in an argon atmosphere to form a stealth coating with a thickness of 40 to 90 nm.

5. The preparation method according to claim 4, characterized in that The sputtering conditions of (2) are as follows: the metal substrate is 25°C, the sputtering power is 80W-160W, the sputtering time is 10min, the argon gas intake volume is 20sccm, and the vacuum degree is 0.8Pa.

6. The preparation method according to claim 3, characterized in that The preparation method of high-entropy alloy target is as follows: Al, Cr, Ti, W and Y five element powders are used as raw materials and melted and cast into ingots in an atomic percentage ratio of 1:1:1:1:1, the ingots are then crushed and ground into powder, the alloy powder is isostatically pressed, and then sintered at high temperature to obtain a round AlCrTiWY target.

7. The preparation method according to claim 3, characterized in that The conditions for sputtering the transparent oxide layer are: using Al2O3, SiO2 or Si3N4 powder as the target material, the sample temperature to be sputtered is 25°C, the power is 120W, the time is 5h, the argon gas intake is 30sccm, and the vacuum degree is 1.0Pa.

8. An application of the stealth coating according to claim 1 or 2, characterized in that: Compatible stealth for use in the visible and infrared spectral ranges.

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