Multi-spectrum compatible stealth coating based on high-entropy alloy nitride and preparation method of multi-spectrum compatible stealth coating

Abstract

The invention discloses a multi-spectrum compatible stealth coating based on high-entropy alloy nitride and a preparation method of the multi-spectrum compatible stealth coating, and belongs to the technical field of wide-spectrum and multi-band stealth. The invention aims to solve the problem that visible light absorption and infrared radiation inhibition of an existing stealth coating in a wide spectral range are difficult to collaboratively optimize. The coating comprises a high-entropy nitride coating formed by high-entropy alloy nitrides, metal elements are selected from four of Au, Ag, Cu, Ti, Al, Cr, W, V, Mn, Fe, Co, Mo, Nb, Zr, Ni, La, Yb, Pr, Lu, Sc, Y and Ce, and the atomic percent of all the elements is 1: 1: 1: 1. The high-entropy alloy target material is prepared through mechanical alloying and hot pressed sintering; the high-entropy alloy nitride coating is deposited on a metal or ceramic substrate in an Ar / N2 mixed atmosphere (the nitrogen accounts for 20%) by adopting a reaction magnetron sputtering and mask plate technology. The material can be widely applied to solar photo-thermal conversion and high-temperature radiation energy-saving devices in the energy field; the invention relates to a precise optical instrument anti-reflection coating and nuclear power corrosion-resistant protection.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of wide-spectrum, multi-band stealth, and in particular relates to a multi-spectrum compatible stealth coating based on high-entropy alloy nitride and a preparation method thereof. BACKGROUND

[0002] Modern detection technology multi-spectrum fusion (such as visible light-infrared-radar collaborative recognition) poses a severe challenge to traditional stealth systems. The core of stealth technology lies in suppressing the signal characteristics of the target in a specific waveband, including visible light reflection, infrared thermal radiation, and microwave scattering. Current mainstream stealth coatings are mostly based on single functional materials, and limited spectrum camouflage is achieved through multi-layer stacking, but due to the limitations of material intrinsic properties, existing technologies face three major bottlenecks in the field of multi-band stealth: material property contradictions, poor process compatibility, and low environmental tolerance. Therefore, developing a single-material stealth system with wide-spectrum absorption, low emissivity, and structural stability has become a key breakthrough in response to multi-mode detection threats.

[0003] Traditional stealth materials are limited by single functional properties and are difficult to cope with multi-band composite detection challenges. High-entropy alloys (HEAs) exhibit excellent thermal stability, oxidation resistance, and wide-spectrum optical control potential due to the synergistic effect of multiple main elements and lattice distortion characteristics. At the same time, high-entropy nitrides (HEA-N) can better break through this limitation through nitrogen atom solid solution strengthening and multi-phase coupling mechanism. On the one hand, it inherits the high hardness (≥20 GPa) and high temperature resistance characteristics (800℃ oxidation rate <0.05mg / cm 2 ·h) of high-entropy alloys, and on the other hand, it realizes the synergistic optimization of visible light wide-spectrum absorption (0.38-0.80μm reflectivity <10%) and infrared low radiation (ε<0.1) by adjusting the nitriding ratio of Al, Cr, etc. The multi-element hybrid interface further endows the microwave frequency band (2-18GHz) with dielectric-magnetic loss synergistic effect, solving the material property conflict of traditional materials "low reflection-low emission", and providing a cross-scale design basis from atomic-micro-nano-macro for multi-spectrum stealth.

[0004] In the preparation of coatings by traditional processes, the film thickness uniformity is poor (±20% deviation), and it is difficult to prepare nanoscale precision structures; it is difficult to accurately control the multi-element composition, and the material selection is limited. However, in the magnetron sputtering method, the sputtering ions bombard the substrate to form strong interface bonding, with an adhesion of ≥30MPa (far exceeding the 5MPa of spray coating technology). The film thickness uniformity error is <5%, suitable for preparing nanoscale multilayer structures (such as 100nm level infrared shielding layer). Through target sputtering and Ar / N2 flow adjustment, the element ratio of the film layer can be accurately controlled. And the substrate temperature can be controlled at <200℃ during sputtering, avoiding thermal damage, suitable for low melting point substrates such as aluminum alloys and composites.

[0005] Therefore, it is very necessary to prepare a stealth coating material based on high entropy nitrides with dual stealth performance in the visible light-infrared-microwave spectral range. Summary of the Invention

[0006] The present invention realizes the integrated innovation of material, structure and function through the composition gradient design of high entropy alloy nitride, magnetron sputtering and mask method, providing an efficient, reliable and engineering feasible solution for the next generation of multi-spectrum compatible stealth coating.

[0007] The present invention aims to solve the problem that existing stealth coatings are difficult to coordinately optimize visible light absorption and infrared radiation suppression within a wide spectral range, and provides a multi-spectral compatible stealth coating based on high entropy alloy nitride and a preparation method thereof.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solutions: One of the purposes of the present invention is to provide a multi-spectral compatible stealth coating based on high-entropy alloy nitride, wherein the coating includes a high-entropy nitride coating composed of high-entropy alloy nitride, whose general chemical formula is HEN, and the metal elements are selected from any four of Au, Ag, Cu, Ti, Al, Cr, W, V, Mn, Fe, Co, Mo, Nb, Zr, Ni, La, Yb, Pr, Lu, Sc, Y, and Ce, and the atomic percentage of each metal element is 1:1:1:1; the nitride coating realizes visible light-infrared-microwave multi-band stealth function through a multi-phase composite structure.

[0009] It is further defined that the preferred metal element composition is Al, Cr, Nb, and Zr, and the mask is fixed by a mechanical clamp and co-sputtered with Si in an Ar / N2 atmosphere to form a high entropy nitride, and the proportion of the nitride phase is controlled by the sputtering process.

[0010] The multi-spectral compatible stealth coating based on high entropy alloy nitride also includes an Al2O3, SiO2 or Si3N4 transparent layer stacked on the surface of the high entropy nitride.

[0011] It is further defined that the thickness of the transparent layer is 80 nm.

[0012] A second object of the present invention is to provide a method for preparing the above-mentioned coating, comprising the following steps: using high-purity metal powders of five kinds of Au, Ag, Cu, Ti, Al, Cr, W, V, Mn, Fe, Co, Mo, Nb, Zr, Ni, La, Yb, Pr, Lu, Sc, Y, and Ce as raw materials, preparing a high-entropy alloy target by mechanical alloying and hot pressing sintering; and using reactive magnetron sputtering and mask technology to deposit a high-entropy alloy nitride coating on a metal or ceramic substrate in an Ar / N2 mixed atmosphere.

[0013] The present invention can control the nitride phase composition and coating microstructure (such as columnar crystals and nanocrystals) by adjusting the nitrogen partial pressure and sputtering power.

[0014] Further defined, the step of depositing a high entropy alloy nitride coating is: Step (1) using deionized water to clean impurities on the surface of the metal substrate, then using anhydrous ethanol to perform ultrasonic cleaning and drying; Step (2) placing the metal substrate processed in step (1) into a magnetron sputtering chamber, fixing the mask by a mechanical clamp, and sputtering the high entropy nitride on the metal substrate in an Ar / N2 atmosphere to form a high entropy alloy nitride coating with a thickness of 80nm-120nm.

[0015] It is further defined that the sputtering conditions of step (2) are: the metal substrate is 25°C, the high entropy alloy and Si sputtering power is 100W-200W, the sputtering time is 5min, the Ar intake volume is 20sccm-40sccm, the N2 intake volume is 5sccm-10sccm, the vacuum degree is 0.2Pa-1.0Pa, and the nitrogen accounts for 20%.

[0016] It is further defined that the preparation method of the high entropy alloy target used in the above preparation method is carried out according to the following steps: using any four element powders of Au, Ag, Cu, Ti, Al, Cr, W, V, Mn, Fe, Co, Mo, Nb, Zr, Ni, La, Yb, Pr, Lu, Sc, Y, and Ce as raw materials in a ratio of 1:1:1:1 in atomic percentage, smelting and casting into an ingot, then crushing the ingot into a powder, and then isostatically pressing the alloy powder, and then sintering at a high temperature to obtain a round high entropy alloy target.

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

[0018] It is further defined that the thickness of the transparent layer is 80 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 nitride, specifically using magnetron sputtering and mask technology to sputter a transparent layer on the surface of the high-entropy nitride coating.

[0020] It is further defined that the conditions for sputtering the transparent oxide layer are: using Al2O3, SiO2 or Si powder as the target material, the temperature of the sample to be sputtered is 25°C, the sputtering power is 120W, the sputtering time is 3h, the Ar intake volume is 20sccm, the N2 intake volume is 5sccm, and the vacuum degree is 0.7Pa.

[0021] The sixth object of the present invention is to provide an application of the above-mentioned multi-spectral compatible stealth coating based on high entropy nitride, specifically for compatible stealth in the visible light-infrared-microwave spectral range.

[0022] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a multi-spectral stealth coating based on AlCrNbZr-Si high-entropy alloy nitride. This coating utilizes magnetron sputtering technology to achieve precise element ratios and multi-phase composite structure control. Combined with a mask, multi-principal element synergy, and cross-scale design, it overcomes the multi-band performance bottleneck of traditional stealth materials. Compared with existing technologies, this invention offers the following significant advantages: (1) Multi-band compatible stealth performance is significantly improved High visible light absorption (0.38-0.80μm): The plasma resonance effect of ZrN and Si3N4 and the gradient refractive index design (n=2.3→1.7) achieve a wide-spectrum absorption rate ≥ 0.93 (better than the 0.85 of traditional TiN coating) and resistance to ambient light interference (reflectivity fluctuation <5% at an incident angle of 0-60°).

[0023] Low infrared emission (3-14μm): The AlN / Si3N4 composite dense phase suppresses thermal radiation, and the 3-14μm atmospheric window emissivity is ≤0.25 (traditional CrN coating ε≈0.5). Combined with the high-temperature stability of NbN, it effectively avoids thermal imaging lock.

[0024] Microwave broadband absorption (2-18GHz): The synergistic effect of NbN dielectric loss (ε''>6) and Si3N4 magnetic loss (μ''>1) makes it suitable for complex electromagnetic environments.

[0025] (2) Breakthroughs in extreme environment tolerance and structural reliability High temperature stability: NbN / Si3N4 phase melting point>2300℃, oxidation rate at 800℃≤0.02mg / cm 2 ·h.

[0026] Thermal shock and corrosion resistance: Si3N4 has low thermal expansion coefficient (3.2×10 ⁻6 / K) matches the metal substrate, and there is no cracking in the thermal cycle of ΔT>800℃; the CrN / AlN passivation film ensures no corrosion in the salt spray test of >1200h.

[0027] (3) Low cost and process adaptability optimization Reduced material costs: Si and Zr replace scarce metals (target material costs are reduced by 40%), and raw material reserves are abundant (Si accounts for 27.7% of the earth's crust).

[0028] The sputtering process is simplified: the element nitriding activity is matched (Si requires high nitrogen pressure, Zr is easily reactive), the process window is wide (nitrogen partial pressure 25-50%, power is 150-250W), and the deposition rate is >50nm / min.

[0029] Expanded engineering applicability: Compatible with curved substrates (radius of curvature ≥ 5mm), suitable for complex configurations such as fighter aircraft skins and satellite fairings, without the generation of brittle phases (interface toughness increased by 20%).

[0030] This coating can be widely used for infrared, radar, and visible light camouflage across the entire spectrum of aircraft and ships, reducing the probability of multi-mode detection by >70%. It is also used in aerospace applications for satellite thermal control coatings (performance degradation <5% under space radiation) and thermal protection for hypersonic vehicles (temperature resistance >1500°C). In the new energy sector, it is also used for solar thermal conversion (absorption rate >93%, reducing heat loss by 40%) and high-temperature radiation energy-saving devices. It is also used as an anti-reflection coating (R <5%) for precision optical instruments and corrosion protection for nuclear power plants.

[0031] The AlCrNbZr-Si system achieves synergistic breakthroughs in multi-band stealth, extreme environment tolerance and low-cost manufacturing through an integrated design of composition, structure and performance, providing innovative solutions for the next generation of stealth technology.

[0032] In order to further understand the features and technical contents of the present invention, please refer to the following detailed description of the present invention and the accompanying drawings. However, the accompanying drawings are provided for reference and illustration only and are not intended to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of the stealth coating structure provided by the present invention; Figure 2 This is a visible light reflection spectrum of the high entropy nitride coating prepared in Example 3; Figure 3 This is an infrared light reflection spectrum of the high entropy nitride coating prepared in Example 3; Figure 4 This is a microwave absorption spectrum of the high entropy nitride coating prepared in Example 3; Figure 5 This is a SEM image of the high entropy nitride coating prepared in Example 3; Figure 6 This is a structural diagram of the mask for the high-entropy nitride coating prepared in Example 3. DETAILED DESCRIPTION

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] The purity of the metal elements in the following examples is by mass.

[0039] Example 1: In this embodiment, the multi-spectral compatible stealth coating based on high entropy nitride is prepared according to the following steps: (1) Preparation of high entropy alloy target AlCrNbZr Raw material ratio: Mix Al, Cr, Nb, and Zr metal powders (purity ≥ 99.9%) in an atomic ratio of 1:1:1:1.

[0040] Melting and crushing: Under argon protection, melt at 1050℃ in a vacuum induction furnace for 180min and cast into ingots; the ingots are mechanically crushed and ball milled for 60h, and passed through a 300-mesh sieve to obtain uniform alloy powder.

[0041] Isostatic pressing: The powder is loaded into a mold and hot isostatically pressed at 12T pressure and 1000℃ for 240min to produce a Φ50mm×5mm target (relative density ≥96%).

[0042] (2) Silicon target pretreatment Silicon target material specifications: single crystal silicon target (purity 99.99%, Φ50mm×3mm); Surface treatment: ultrasonic cleaning with hydrofluoric acid (mass concentration of 5%) for 10 minutes, rinsing with deionized water and drying with nitrogen.

[0043] (3) Substrate cleaning Cleaning process: Aluminum substrate (6061 alloy) was ultrasonically cleaned with acetone and ethanol for 15 minutes each; rinsed with deionized water and dried with nitrogen; and plasma cleaned (power: 100W, 5 minutes).

[0044] (4) Magnetron sputtering co-deposition of AlCrNbZr-Si layer Sputtering system: dual-target co-sputtering system (AlCrNbZr target DC power supply; Si target RF power supply); Mask: Select a polymer mask based on the target pattern, use an optical microscope to assist in aligning the mask with the substrate surface, and fix the mask with a mechanical clamp to ensure that it fits tightly to the substrate to prevent sputtered material from penetrating through the gaps.

[0045] Sputtering parameters: AlCrNbZr target sputtering power is 200 W (DC), Si target 200 W (RF), Ar / N2 mixed gas (nitrogen 20%, total flow rate 25 sccm), substrate temperature 25 °C, vacuum degree 0.6 Pa, sputtering time 30 min.

[0046] (5) Magnetron sputtering deposition of Si3N4 protective layer Sputtering parameters: high-purity Si ceramic target (purity 99.99%); Ar / N2 mixed gas (nitrogen volume ratio 20%, total flow rate 25 sccm); sputtering power 200 W (RF mode); vacuum degree 0.8 Pa; sputtering time 180 min.

[0047] Coating characteristics: Thickness: 80nm; surface roughness Ra<5nm.

[0048] The coating prepared by the method of this embodiment was subjected to performance tests including visible light absorptivity in the 0.38-0.80 μm wavelength range (AM1.5 spectrum), infrared emissivity in the 3-14 μm wavelength range, and microwave reflection loss in the 2-18 GHz wavelength range.

[0049] Example 2: In this embodiment, the multi-spectral compatible stealth coating based on high entropy nitride is prepared according to the following steps: (1) Preparation of high entropy alloy target AlCrNbZr Raw material ratio: Mix Al, Cr, Nb, and Zr metal powders (purity ≥ 99.9%) in an atomic ratio of 1:1:1:1.

[0050] Melting and crushing: Under argon protection, melt at 1050℃ in a vacuum induction furnace for 180min and cast into ingots; the ingots are mechanically crushed and ball milled for 60h, and passed through a 300-mesh sieve to obtain uniform alloy powder.

[0051] Isostatic pressing: The powder is loaded into a mold and hot isostatically pressed at 12T pressure and 1000℃ for 240min to produce a Φ50mm×5mm target (relative density ≥96%).

[0052] (2) Silicon target pretreatment Silicon target material specifications: single crystal silicon target (purity 99.99%, Φ50mm×3mm); Surface treatment: ultrasonic cleaning with hydrofluoric acid (mass concentration of 5%) for 10 minutes, rinsing with deionized water and drying with nitrogen.

[0053] (3) Substrate cleaning Cleaning process: Aluminum substrate (6061 alloy) was ultrasonically cleaned with acetone and ethanol for 15 minutes each; rinsed with deionized water and dried with nitrogen; and plasma cleaned (power: 100W, 5 minutes).

[0054] (4) Magnetron sputtering co-deposition of AlCrNbZr-Si layer Sputtering system: dual-target co-sputtering system (AlCrNbZr target DC power supply; Si target RF power supply); Mask: Select a polymer mask based on the target pattern, use an optical microscope to assist in aligning the mask with the substrate surface, and fix the mask with a mechanical clamp to ensure that it fits tightly to the substrate to prevent sputtered material from penetrating through the gaps.

[0055] Sputtering parameters: AlCrNbZr target sputtering power is 200 W (DC), Si target 200 W (RF), Ar / N2 mixed gas (nitrogen 20%, total flow rate 30 sccm), substrate temperature 25 °C, vacuum degree 0.6 Pa, sputtering time 30 min.

[0056] (5) Magnetron sputtering deposition of Si3N4 protective layer Sputtering parameters: high-purity Si ceramic target (purity 99.99%); Ar / N2 mixed gas (nitrogen 20%, total flow rate 25 sccm); sputtering power 200 W (RF mode); vacuum degree 0.8 Pa; sputtering time 180 min.

[0057] Coating characteristics: Thickness: 80nm; surface roughness Ra<5nm.

[0058] The coating prepared by the method of this embodiment was subjected to performance tests including visible light absorptivity in the 0.38-0.80 μm wavelength range (AM1.5 spectrum), infrared emissivity in the 3-14 μm wavelength range, and microwave reflection loss in the 2-18 GHz wavelength range.

[0059] Example 3: In this embodiment, the multi-spectral compatible stealth coating based on high entropy nitride is prepared according to the following steps: (1) Preparation of high entropy alloy target AlCrNbZr Raw material ratio: Mix Al, Cr, Nb, and Zr metal powders (purity ≥ 99.9%) in an atomic ratio of 1:1:1:1.

[0060] Melting and crushing: Under argon protection, melt at 1050℃ in a vacuum induction furnace for 180min and cast into ingots; the ingots are mechanically crushed and ball milled for 60h, and passed through a 300-mesh sieve to obtain uniform alloy powder.

[0061] Isostatic pressing: The powder is loaded into a mold and hot isostatically pressed at 12T pressure and 1000℃ for 240min to produce a Φ50mm×5mm target (relative density ≥96%).

[0062] (2) Silicon target pretreatment Silicon target material specifications: single crystal silicon target (purity 99.99%, Φ50mm×3mm); Surface treatment: ultrasonic cleaning with hydrofluoric acid (mass concentration of 5%) for 10 minutes, rinsing with deionized water and drying with nitrogen.

[0063] (3) Substrate cleaning Cleaning process: Aluminum substrate (6061 alloy) was ultrasonically cleaned with acetone and ethanol for 15 minutes each; rinsed with deionized water and dried with nitrogen; and plasma cleaned (power: 100W, 5 minutes).

[0064] (4) Magnetron sputtering co-deposition of AlCrNbZr-Si layer Sputtering system: dual-target co-sputtering system (AlCrNbZr target DC power supply; Si target RF power supply); Mask: Select a polymer mask based on the target pattern, use an optical microscope to assist in aligning the mask with the substrate surface, and fix the mask with a mechanical clamp to ensure that it fits tightly to the substrate to prevent sputtered material from penetrating through the gaps.

[0065] Sputtering parameters: AlCrNbZr target sputtering power is 200 W (DC), Si target 200 W (RF), Ar / N2 mixed gas (nitrogen 20%, total flow rate 35 sccm), substrate temperature 25 °C, vacuum degree 0.6 Pa, sputtering time 30 min.

[0066] (5) Magnetron sputtering deposition of Si3N4 protective layer Sputtering parameters: high-purity Si ceramic target (purity 99.99%); Ar / N2 mixed gas (nitrogen 20%, total flow rate 25 sccm); sputtering power 200 W (RF mode); vacuum degree 0.8 Pa; sputtering time 180 min.

[0067] Coating characteristics: Thickness: 80nm; surface roughness Ra<5nm.

[0068] The coating prepared by the method of this embodiment was subjected to performance tests including visible light absorptivity in the 0.38-0.80 μm wavelength range (AM1.5 spectrum), infrared emissivity in the 3-14 μm wavelength range, and microwave reflection loss in the 2-18 GHz wavelength range.

[0069] Example 4: In this embodiment, the multi-spectral compatible stealth coating based on high entropy nitride is prepared according to the following steps: (1) Preparation of high entropy alloy target AlCrNbZr Raw material ratio: Mix Al, Cr, Nb, and Zr metal powders (purity ≥ 99.9%) in an atomic ratio of 1:1:1:1.

[0070] Melting and crushing: Under argon protection, melt at 1050℃ in a vacuum induction furnace for 180min and cast into ingots; the ingots are mechanically crushed and ball milled for 60h, and passed through a 300-mesh sieve to obtain uniform alloy powder.

[0071] Isostatic pressing: The powder is loaded into a mold and hot isostatically pressed at 12T pressure and 1000℃ for 240min to produce a Φ50mm×5mm target (relative density ≥96%).

[0072] (2) Silicon target pretreatment Silicon target material specifications: single crystal silicon target (purity 99.99%, Φ50mm×3mm); Surface treatment: ultrasonic cleaning with hydrofluoric acid (mass concentration of 5%) for 10 minutes, rinsing with deionized water and drying with nitrogen.

[0073] (3) Substrate cleaning Cleaning process: Aluminum substrate (6061 alloy) was ultrasonically cleaned with acetone and ethanol for 15 minutes each; rinsed with deionized water and dried with nitrogen; and plasma cleaned (power: 100W, 5 minutes).

[0074] (4) Magnetron sputtering co-deposition of AlCrNbZr-Si layer Sputtering system: dual-target co-sputtering system (AlCrNbZr target DC power supply; Si target RF power supply); Mask: Select a polymer mask based on the target pattern, use an optical microscope to assist in aligning the mask with the substrate surface, and fix the mask with a mechanical clamp to ensure that it fits tightly to the substrate to prevent sputtered material from penetrating through the gaps.

[0075] Sputtering parameters: AlCrNbZr target sputtering power is 200 W (DC), Si target 200 W (RF), Ar / N2 mixed gas (nitrogen 20%, total flow rate 40 sccm), substrate temperature 25 °C, vacuum degree 0.6 Pa, sputtering time 30 min.

[0076] (5) Magnetron sputtering deposition of Si3N4 protective layer Sputtering parameters: high-purity Si ceramic target (purity 99.99%); Ar / N2 mixed gas (nitrogen 20%, total flow rate 25 sccm); sputtering power 200 W (RF mode); vacuum degree 0.8 Pa; sputtering time 180 min.

[0077] Coating characteristics: Thickness: 80nm; surface roughness Ra<5nm.

[0078] The coating prepared by the method of this embodiment was subjected to performance tests including visible light absorptivity in the 0.38-0.80 μm wavelength range (AM1.5 spectrum), infrared emissivity in the 3-14 μm wavelength range, and microwave reflection loss in the 2-18 GHz wavelength range.

[0079] Example 5: In this embodiment, the multi-spectral compatible stealth coating based on high entropy nitride is prepared according to the following steps: (1) Preparation of high entropy alloy target AlCrNbZr Raw material ratio: Mix Al, Cr, Nb, and Zr metal powders (purity ≥ 99.9%) in an atomic ratio of 1:1:1:1.

[0080] Melting and crushing: Under argon protection, melt at 1050℃ in a vacuum induction furnace for 180min and cast into ingots; the ingots are mechanically crushed and ball milled for 60h, and passed through a 300-mesh sieve to obtain uniform alloy powder.

[0081] Isostatic pressing: The powder is loaded into a mold and hot isostatically pressed at 12T pressure and 1000℃ for 240min to produce a Φ50mm×5mm target (relative density ≥96%).

[0082] (2) Silicon target pretreatment Silicon target material specifications: single crystal silicon target (purity 99.99%, Φ50mm×3mm); Surface treatment: ultrasonic cleaning with hydrofluoric acid (mass concentration of 5%) for 10 minutes, rinsing with deionized water and drying with nitrogen.

[0083] (3) Substrate cleaning Cleaning process: Aluminum substrate (6061 alloy) was ultrasonically cleaned with acetone and ethanol for 15 minutes each; rinsed with deionized water and dried with nitrogen; and plasma cleaned (power: 100W, 5 minutes).

[0084] (4) Magnetron sputtering co-deposition of AlCrNbZr-Si layer Sputtering system: dual-target co-sputtering system (AlCrNbZr target DC power supply; Si target RF power supply); Mask: Select a polymer mask based on the target pattern, use an optical microscope to assist in aligning the mask with the substrate surface, and fix the mask with a mechanical clamp to ensure that it fits tightly to the substrate to prevent sputtered material from penetrating through the gaps.

[0085] Sputtering parameters: AlCrNbZr target sputtering power is 200 W (DC), Si target 200 W (RF), Ar / N2 mixed gas (nitrogen 20%, total flow rate 45 sccm), substrate temperature 25 °C, vacuum degree 0.6 Pa, sputtering time 30 min.

[0086] (5) Magnetron sputtering deposition of Si3N4 protective layer Sputtering parameters: high-purity Si ceramic target (purity 99.99%); Ar / N2 mixed gas (nitrogen 20%, total flow rate 25 sccm); sputtering power 200 W (RF mode); vacuum degree 0.8 Pa; sputtering time 180 min.

[0087] Coating characteristics: Thickness: 80nm; surface roughness Ra<5nm.

[0088] The coating prepared by the method of this embodiment was subjected to performance tests including visible light absorptivity in the 0.38-0.80 μm wavelength range (AM1.5 spectrum), infrared emissivity in the 3-14 μm wavelength range, and microwave reflection loss in the 2-18 GHz wavelength range.

[0089] This embodiment achieves the synergistic optimization of "broad-spectrum absorption-low thermal radiation-strong environmental tolerance" through the integrated design of AlCrNbZr-Si co-sputtering and Si3N4 protective layer, providing an efficient, reliable and economical new solution for stealth coatings of high-value equipment.

[0090] Comparative Example 1 The difference between this comparative example and Example 3 is that the Si3N4 layer is not sputtered on the AlCrNbZr-SiN layer, and the remaining process steps and parameter settings are the same as those in Example 3, obtaining a single-layer stealth coating named AlCrNbZr-SiN.

[0091] Lambda950 was used to measure the visible light reflectance spectrum of the film to measure the multilayer stealth coating (AlCrNbZr-SiN / Si3N4) obtained in Example 3. The results are as follows: Figure 2 As shown by Figure 2 It can be seen that the absorption rate of AlCrNbZr-SiN / Si3N4 in the 0.38-0.80μm band is about 0.90. The absorption rate of AlCrNbZr-SiN in the 0.38-0.80μm band is about 0.78.

[0092] The infrared reflectance spectrum of the multilayer stealth coating (AlCrNbZr-SiN / Si3N4) obtained in Example 3 was tested by using an FTIR infrared spectrometer, and the result is shown in Figure 3 As shown in the figure, the emissivity of AlCrNbZr-SiN / Si3N4 in the 3-14 μm band is about 0.09. The emissivity of AlCrNbZr-SiN in the 3-14 μm band is about 0.07.

[0093] The microwave reflection loss of the multilayer stealth coating (AlCrNbZr-SiN / Si3N4) obtained in Example 3 was tested by using a vector network analyzer, and the result is shown in Figure 4 As shown in the figure, the AlCrNbZr-SiN / Si3N4 prepared by using a mask has the strongest absorption performance (the reflection loss is about -13 dB) at about 12 GHz, and has good electromagnetic wave absorption capacity in the range of 11-13.5 GHz.

[0094] The micro cross-sectional morphology of the coating obtained in Example 3 was characterized, and the result is shown in Figure 5 As shown in the figure, Figure 5 It can be known that the thickness of AlCrNbZr-SiN is about 100 nm, and the thickness of Si3N4 is about 80 nm, and the structure thereof is columnar crystal.

[0095] The surface morphology of the coating obtained in Example 3 was characterized, and the result is shown in Figure 6 As shown in the figure, the unit size of the mask can be observed from the surface morphology of the coating.

[0096] The above describes the specific embodiments of the present application. It should be noted that the present application is not limited to the above specific embodiments, and those skilled in the art can make various modifications or changes within the scope of the claims, which does not affect the essential content of the present application.

Claims

1. A multi-spectral compatible stealth coating based on high entropy alloy nitride, characterized in that: The coating includes a high-entropy nitride coating composed of high-entropy alloy nitride, and the metal elements are selected from four of Au, Ag, Cu, Ti, Al, Cr, W, V, Mn, Fe, Co, Mo, Nb, Zr, Ni, La, Yb, Pr, Lu, Sc, Y, and Ce, and the atomic percentage of each element is 1:1:1:

1.

2. The coating according to claim 1, characterized in that The metal elements are Al, Cr, Nb, and Zr.

3. The coating according to claim 1, characterized in that The thickness of the high entropy nitride coating is 80nm-120nm.

4. The coating according to claim 1, characterized in that It also includes a transparent layer of Al2O3, SiO2 or Si3N4 stacked on the surface of the high entropy nitride.

5. The coating according to claim 4, characterized in that The thickness of the transparent layer was 80 nm.

6. The method for preparing the coating according to claim 1 or 2, wherein: The following steps are involved: The metal element powder is melted and cast into an ingot, crushed and ground into powder, isostatically pressed, and then sintered at high temperature to obtain a high-entropy alloy target; Reactive magnetron sputtering and mask technology are used to deposit high entropy alloy nitride coatings on metal or ceramic substrates in an Ar / N2 atmosphere.

7. The method according to claim 5, characterized in that Magnetron sputtering: the metal substrate is 25°C, the high entropy alloy and Si sputtering power is 100W-200W, the sputtering time is 5min, the Ar intake volume is 20sccm-40sccm, the N2 intake volume is 5sccm-10sccm, the vacuum degree is 0.5Pa, and the nitrogen accounts for 20%.

8. The method according to claim 5, characterized in that Melted at 1050℃ under argon protection.

9. The method according to claim 8, characterized in that Hot isostatic pressing treatment at 12T pressure and 1000℃.

10. The method according to any one of claims 6 to 9, characterized in that: On the surface of the high entropy alloy nitride coating, Al2O3, SiO2 or Si powder was used as the target material, the sample temperature to be sputtered was 25°C, the sputtering power was 120W, the sputtering time was 3h, the Ar intake volume was 20sccm, the N2 intake volume was 5sccm, and the vacuum degree was 0.7Pa.

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