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

Abstract

The invention discloses a multi-spectral-band compatible stealth coating based on a high-entropy alloy and a preparation method of the multi-spectral-band compatible stealth coating, and belongs to the technical field of functional high-entropy alloy coatings and preparation of the functional high-entropy alloy coatings. The problem that the visible light and infrared stealth effect of an existing stealth coating in a wide spectrum range is poor is solved. According to the preparation method, the high-entropy alloy film is prepared through the magnetron sputtering technology, efficient customization of material components and structures is achieved through scientific screening and optimal combination of elements and regulation and control of magnetron sputtering parameters, and therefore the high-entropy alloy film which is uniform, compact and excellent in performance is obtained. Test results show that the visible light band absorptivity of the high-entropy alloy coating is about 0.95, the infrared band emissivity of the high-entropy alloy coating is about 0.05, and multi-spectrum-band compatible stealth in the visible light and infrared spectrum range is achieved.

Description

Technical Field

[0001] The 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 target objects to avoid detection by enemy or reconnaissance equipment. Existing stealth coating technology mainly reduces the reflection and radiation of targets in different spectral regions by designing the optical absorption characteristics of materials. However, existing stealth coatings face some technical difficulties, especially in light absorption and radiation control in the visible and infrared spectral ranges.

[0003] Traditional stealth coating materials are mostly made of metal, ceramic or composite materials, which have a certain light absorption capacity, but are usually only effective in a specific spectral range (such as visible light or infrared). For example, the use of black coating can effectively absorb visible light, but the radiation suppression effect on the infrared spectral range is poor, and vice versa.

[0004] With the emergence of high entropy alloys (HEAs), based on 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 stealth coatings based on high entropy alloys are usually only effective for a specific spectral range. 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. And although the existing high entropy alloy coatings can reduce reflection, the emission suppression effect on radiation 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 in the preparation of thin films. The main parameters of magnetron sputtering include working pressure, target voltage, target current density and deposition rate. Among them, sputtering power is an important process parameter in the magnetron sputtering process, which directly affects 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, too high sputtering power will cause more defects inside the film, such as bubbles, lattice distortion, etc., thus affecting the quality of the film. The deposition rate affects the migration time of sputtered atoms on the substrate surface, thereby affecting factors such as the number of nuclei, stress in the film, and surface roughness. Too low a deposition rate will result in a long atomic migration time, easy formation of larger grains, and a rough surface; too high a deposition rate will result in too many nuclei, increased internal stress, and more defects. At high sputtering power, the coating exhibits higher hardness, smaller grain size, and a denser microstructure.

[0006] Therefore, it is very necessary to prepare a coating with dual stealth performance in the visible light and infrared spectrum range based on a stealth coating material of a high entropy alloy. Based on this, the present invention proposes a new material based on a high entropy alloy, which combines the excellent optical properties, thermal stability and structural regulation ability of the high entropy alloy, and can achieve excellent visible light and infrared stealth effects in a wide spectral range through reasonable high entropy alloy composition design, coating structure adjustment and preparation process control, thereby solving the deficiencies in the prior art. Summary of the invention

[0007] In order to solve the problem that existing stealth coatings have poor visible light and infrared stealth effects within a wide spectral range, the present invention provides a multi-spectral compatible stealth coating based on a 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 coating 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 method is: using a high entropy alloy prepared by 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 as a target material, and using 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) using deionized water to clean impurities on the surface of the metal substrate, then using anhydrous ethanol for ultrasonic cleaning and drying;

[0014] (2) The metal substrate treated by (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 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 ingots in a ratio of 1:1:1:1:1 in atomic percentage, crushing and grinding the ingots into powder, isostatically pressing the alloy powder, and then sintering at 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 is 30sccm, and the vacuum degree is 1.0Pa.

[0021] The 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 a high entropy alloy film using magnetron sputtering technology, which achieves efficient customization of material composition and structure by scientifically screening and optimizing the combination of elements and regulating magnetron sputtering parameters, thereby obtaining a uniform, dense and high-performance high entropy alloy film. Compared with the prior art, the present invention also has the following advantages:

[0024] (1) The present invention uses high entropy alloy (HEA) as the target material, optimizes the spectral selective absorption and radiation performance by accurately designing the alloy composition and multilayer film structure, and realizes dual optimization in the visible light and infrared bands. Specifically, the low radiation characteristics of Al, Au, and Ag are used to make the high entropy alloy show 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 structure and crystal structure of these elements give the coating a high absorption rate in the visible light band, especially in the range of 0.38μm to 0.80μm, the absorption rate can reach more than 0.9. This enables the coating to effectively absorb visible light radiation, improve the efficiency of photothermal conversion, and is widely used in the fields of solar thermal collection and photothermal conversion.

[0025] (2) The present invention can control the microstructure to achieve the desired optical and physical properties by optimizing the sputtering deposition parameters. The stealth coating obtained by adopting the multilayer 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 thermal radiation leakage 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, can effectively achieve light-to-heat conversion, stealth protection and thermal management, and is widely used in the fields of 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 a high temperature environment while maintaining its optical properties unchanged. This makes the technology applicable to the fields of aerospace, military stealth, optical coatings and high-temperature radiation control. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0028] Figure 2 Visible light reflection spectra of 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, but the present invention may also be implemented in other ways different from those described herein, and 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" 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 term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with 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 materials, reagents, methods and instruments in the art unless otherwise specified, and can be obtained through commercial channels by those skilled in the art.

[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 in atomic percentage, smelted at 980°C for 240 minutes, and cast into ingots. The ingots were crushed and ground into powder, and passed through a 240-mesh sieve to obtain alloy powder. The alloy powder was placed in a mold and isostatically pressed for 180 minutes at a pressure of 12T to obtain a circular AlCrTiWY target with a diameter of 50mm and a height of 5mm.

[0039] (2) Substrate cleaning:

[0040] Prepare the Al substrate used as the substrate material. The substrate material needs to be cleaned before sputtering. The specific cleaning process is: first use deionized water to clean the surface debris, then soak it in an ultrasonic cleaner with anhydrous ethanol for 20 minutes, then use a hair dryer to dry the surface, and place the treated substrate material on the sample stage of the magnetron sputtering chamber and fix it.

[0041] (3) Sputtering AlCrTiWY layer on the 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, vacuum degree of 0.8Pa, forming an AlCrTiWY layer with a thickness of 45nm 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 Al2O3 was sputtered onto the AlCrTiWY layer. The sputtering conditions were: substrate temperature of 25°C, sputtering power of 200W, sputtering time of 5h, argon gas intake 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 in atomic percentage, smelted at 980°C for 240 minutes, and cast into ingots. The ingots were crushed and ground into powder, and passed through a 240-mesh sieve to obtain alloy powder. The alloy powder was placed in a mold and isostatically pressed for 180 minutes at a pressure of 12T to obtain a circular AlCrTiWY target with a diameter of 50mm and a height of 5mm.

[0048] (2) Substrate cleaning:

[0049] Prepare the Al substrate used as the substrate material. The substrate material needs to be cleaned before sputtering. The specific cleaning process is: first use deionized water to clean the surface debris, then soak it in an ultrasonic cleaner with anhydrous ethanol for 20 minutes, then use a hair dryer to dry the surface, and place the treated substrate material on the sample stage of the magnetron sputtering chamber and fix it.

[0050] (3) Sputtering AlCrTiWY layer on the 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 100 W, sputtering time of 5 min, argon gas intake of 20 sccm, vacuum degree of 0.8 Pa, forming an AlCrTiWY layer with a thickness of 55 nm 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 Al2O3 is sputtered onto the AlCrTiWY layer. The sputtering conditions are: substrate temperature is 25°C, sputtering power is 200W, sputtering time is 5h, argon gas intake is 30sccm, vacuum degree is 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 in atomic percentage, smelted at 980°C for 240 minutes, and cast into ingots. The ingots were crushed and ground into powder, and passed through a 240-mesh sieve to obtain alloy powder. The alloy powder was placed in a mold and isostatically pressed for 180 minutes at a pressure of 12T to obtain a circular AlCrTiWY target with a diameter of 50mm and a height of 5mm.

[0057] (2) Substrate cleaning:

[0058] Prepare the Al substrate used as the substrate material. The substrate material needs to be cleaned before sputtering. The specific cleaning process is: first use deionized water to clean the surface debris, then soak it in an ultrasonic cleaner with anhydrous ethanol for 20 minutes, then use a hair dryer to dry the surface, and place the treated substrate material on the sample stage of the magnetron sputtering chamber and fix it.

[0059] (3) Sputtering AlCrTiWY layer on the 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] In an argon atmosphere, the target material Al2O3 was sputtered onto the AlCrTiWY layer. The sputtering conditions were: 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 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 in atomic percentage, smelted at 980°C for 240 minutes, and cast into ingots. The ingots were crushed and ground into powder, and passed through a 240-mesh sieve to obtain alloy powder. The alloy powder was placed in a mold and isostatically pressed for 180 minutes at a pressure of 12T to obtain a circular AlCrTiWY target with a diameter of 50mm and a height of 5mm.

[0066] (2) Substrate cleaning:

[0067] Prepare the Al substrate used as the substrate material. The substrate material needs to be cleaned before sputtering. The specific cleaning process is: first use deionized water to clean the surface debris, then soak it in an ultrasonic cleaner with anhydrous ethanol for 20 minutes, then use a hair dryer to dry the surface, and place the treated substrate material on the sample stage of the magnetron sputtering chamber and fix it.

[0068] (3) Sputtering AlCrTiWY layer on the 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, vacuum degree of 0.8Pa, forming an AlCrTiWY layer with a thickness of 100nm 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 Al2O3 is sputtered onto the AlCrTiWY layer. The sputtering conditions are: substrate temperature is 25°C, sputtering power is 200W, sputtering time is 5h, argon gas intake is 30sccm, vacuum degree is 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 in atomic percentage, smelted at 980°C for 240 minutes, and cast into ingots. The ingots were crushed and ground into powder, and passed through a 240-mesh sieve to obtain alloy powder. The alloy powder was placed in a mold and isostatically pressed for 180 minutes at a pressure of 12T to obtain a circular AlCrTiWY target with a diameter of 50mm and a height of 5mm.

[0075] (2) Substrate cleaning:

[0076] Prepare the Al substrate used as the substrate material. The substrate material needs to be cleaned before sputtering. The specific cleaning process is: first use deionized water to clean the surface debris, then soak it in an ultrasonic cleaner with anhydrous ethanol for 20 minutes, then use a hair dryer to dry the surface, and place the treated substrate material on the sample stage of the magnetron sputtering chamber and fix it.

[0077] (3) Sputtering AlCrTiWY layer on the 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 Al2O3 is sputtered onto the AlCrTiWY layer. The sputtering conditions are: substrate temperature is 25°C, sputtering power is 200W, sputtering time is 5h, argon gas intake is 30sccm, vacuum degree is 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, thereby obtaining a single-layer stealth coating named AlCrTiWY.

[0083] Effect example

[0084] (1) 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 was tested by Lambda950 on the visible light reflection spectrum of the film. 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~0.8μm band is about 0.95. The absorption rate of AlCrTiWY in the 0.38μm~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 are 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 as follows Figure 5 As shown in the figure, it can be seen that 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 indicates that sputtering the Al2O3 layer on the AlCrTiWY layer has little effect on the microscopic morphology.

[0087] Although the present invention has been disclosed as above in the preferred embodiment, 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 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.

2. The stealth coating according to claim 1, characterized in that: The coating consists of Al, Cr, Ti, W and Y.

3. A method for preparing a stealth coating according to any one of claims 1 to 2, characterized in that: A high entropy alloy prepared with 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 is used as a target, and a high entropy alloy coating is formed on a metal substrate by magnetron sputtering technology.

4. The preparation method according to claim 3, characterized in that: include: (1) using deionized water to clean impurities on the surface of the metal substrate, and then using anhydrous ethanol for ultrasonic cleaning and drying; (2) The metal substrate treated by (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: the metal substrate is 25°C, the sputtering power is 80W-160W, the sputtering time is 10min, the argon gas intake is 20sccm, and the vacuum degree is 0.8Pa.

6. A method for preparing a high entropy alloy target material used in the preparation method according to claim 3, characterized in that: 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 are used as raw materials, and are melted and cast into ingots in a ratio of 1:1:1:1:1 in atomic percentage. The ingots are then crushed and ground into powder, and the alloy powders are isostatically pressed and then sintered at high temperature to obtain a round AlCrTiWY target.

7. A stealth coating, characterized in that: The coating consists of the high entropy alloy coating according to claim 1 and an Al2O3, SiO2 or Si3N4 transparent oxide layer stacked on the surface thereof; the thickness of the transparent oxide layer is 100nm.

8. A method for preparing the stealth coating according to claim 7, characterized in that: The transparent oxide layer is sputtered on the surface of the high entropy alloy coating by magnetron sputtering technology.

9. The preparation method according to claim 8, characterized in 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 is 30sccm, and the vacuum degree is 1.0Pa.

10. An application of the stealth coating according to claim 1 or 7, characterized in that: Compatible stealth for use in both visible and infrared spectral ranges.

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