Multi-spectrum compatible camouflage and protection film and preparation method thereof

Abstract

The invention provides a multi-spectrum compatible camouflage and protection film and a preparation method thereof, and belongs to the technical field of camouflage films, and the method comprises the following steps: screening and determining a phase change functional layer material and a directional emission module material; coupling a directional transmitting module material, a phase change functional layer material and a mechanical protective layer material, constructing a Fabry-Perot resonant cavity type multilayer film structure, and calculating an initial thickness range of each layer of material in the directional transmitting module; carrying out parametric scanning by taking the initial thickness range of the optical spacing layer material as a variable, calculating the transmittance and the directional emissivity of the multi-layer film in a middle and far infrared band, and determining the optimal thickness of each layer of film at the same time; and according to the structure of the multi-layer film and the optimal thickness of the multi-layer film, sequentially depositing each layer of film material on the substrate by adopting a magnetron sputtering process to obtain the multi-spectrum compatible camouflage and protection film. The thin film in the scheme has dynamic infrared camouflage, efficient electromagnetic shielding, thermal management performance and mechanical protection performance.

Description

Technical Field

[0001] This invention relates to the field of camouflage film technology, and in particular to a multi-spectral compatible camouflage and protection film and its preparation method. Background Technology

[0002] The 3-5μm (mid-wave infrared, MWIR) and 8-14μm (far-wave infrared, LWIR) bands are key bands for infrared detection and transmission, while the 2-18GHz (microwave band) is the main frequency band for radar detection. Studying the electromagnetic wave characteristics of these bands is of great significance for military, medical, industrial, and energy utilization fields. For example, in the field of smart windows for buildings, windows often need high transmittance in the visible light band to allow natural light to enter, while simultaneously possessing high radiation characteristics in the infrared band to promote heat dissipation. For aircraft detection windows, it is necessary to simultaneously meet the requirements of high transmittance of mid- and far-infrared signals, suppression of self-heating radiation to achieve infrared camouflage, and electromagnetic shielding against radar waves. Furthermore, harsh working environments such as sandstorms also place clear demands on the mechanical protection of thin films. Thermal radiation propagates non-directionally, easily leading to equipment being monitored from all directions; therefore, reducing emissivity or achieving directional control of infrared radiation is a key approach to improving infrared camouflage and radiative cooling effects.

[0003] Currently, while directional thermal emission has been achieved through methods such as surface plasmon gratings, metasurfaces, phonon polariton grating structures, and photonic crystals, it generally suffers from a narrow operating wavelength, making it difficult to cover a wide range of infrared directional thermal radiation. While cascaded Berreman modes based on the superposition of multiple near-zero dielectric (ENZ) materials hold promise for achieving wide-band infrared directional thermal radiation, the electric field confinement capability decreases with increasing ENZ film thickness, leading to a reduction in material transmittance and the failure of wide-band directional radiation modes. Furthermore, such static structures cannot actively switch between high and low directional radiation states, lacking environmental adaptability. Although phase change materials such as In3SbTe2 (IST), Ge2Sb2Te5 (GST), and VO2 can achieve switching of specific optical properties across a specific wavelength range through reversible transitions between crystalline and amorphous states, integrating them into multilayer film structures to achieve reversible conversion between high emissivity and high transmittance still faces challenges in multilayer film optical admittance matching and precise stoichiometry preparation.

[0004] In summary, no thin-film material currently meets the comprehensive requirements of various application scenarios, including energy-saving windows in smart buildings, protective windows for precision instruments, and windows and skins for aerospace vehicles. Specifically, it needs dynamic adjustability of camouflage and transmission in the mid- and far-infrared bands, electromagnetic shielding effectiveness in the microwave band, and mechanical protection against sand and dust.

[0005] Therefore, there is an urgent need to provide a multi-spectral compatible camouflage and protection film and its preparation method. Summary of the Invention

[0006] This invention provides a multi-spectrum compatible camouflage and protection film and its preparation method, which can solve the problem that existing film materials cannot simultaneously meet the requirements of dynamic tunability of camouflage and transmission in the mid- and far-infrared bands, electromagnetic shielding of microwaves, and excellent mechanical protection.

[0007] In a first aspect, the present invention provides a method for preparing a multi-spectrum compatible camouflage and protection film, wherein, from the incident surface to the substrate direction, the film sequentially comprises a mechanical protection layer, a directional emission module, and a phase change functional layer; wherein, the phase change functional layer is capable of undergoing a reversible phase transition between an amorphous state and a crystalline state; and the directional emission module is capable of forming a Fabry-Perot resonant cavity structure with the mechanical protection layer to generate directional radiation in the far-infrared band. The preparation method includes: Based on the optical and electrical properties of phase change materials in the mid- and far-infrared bands, phase change functional layer materials were screened and determined. Based on far-infrared directional radiation performance and interface performance, materials for directional emission modules are screened and determined; wherein, the materials for directional emission modules include optical spacer layer materials, blocking layer materials and matching layer materials; The materials of the directional launch module, the phase change functional layer, and the mechanical protection layer are coupled to construct a Fabry-Perot resonant cavity type multilayer thin film structure, and the initial thickness range of each layer in the directional launch module is calculated. An optical simulation model of the multilayer thin film structure is constructed, and a parameterized scan is performed with the initial thickness range of the optical spacer material as a variable. The transmittance and directional emissivity of the multilayer thin film in the mid- and far-infrared bands are calculated, and the optimal thickness of each thin film is determined according to the preset optimization target. Based on the multilayer thin film structure and the optimal thickness of the multilayer thin film, the multi-spectral compatible camouflage and protection film is prepared by sequentially depositing each layer of thin film material on the substrate using a magnetron sputtering process.

[0008] Preferably, the screening and determination of phase change functional layer materials based on the optical and electrical properties of phase change materials in the mid-infrared and far-infrared bands includes: The electrical and optical parameters of various phase change materials are obtained; wherein the electrical parameters include sheet resistance and dielectric constant; and the optical parameters include refractive index and extinction coefficient. Based on the electrical parameters of phase change materials in the crystalline state, phase change materials with sheet resistance close to that of metals and dielectric constants approaching zero are screened to obtain a material set. Based on the optical constants of each material in the amorphous and crystalline states in the material set, and based on preset screening conditions, the materials in the material set are screened to determine the phase change functional layer material; wherein, the preset screening conditions are as follows: the material is in a dielectric transparent state in the amorphous state and in a metallic reflective state in the crystalline state, and the material can form optical admittance matching with the adjacent directional emission module in the far-infrared band in both the crystalline and amorphous states.

[0009] Preferably, the phase change functional layer material is one or more of In3SbTe2, Ge2Sb2Te5, VO2, or their doped and modified materials.

[0010] Preferably, the process of screening and determining the materials for the directional emission module based on far-infrared directional radiation performance and interface performance includes: Based on the obtained complex dielectric functions of various thin film materials, calculate the variation curve of the function Im(-1 / ε) corresponding to the complex dielectric function in the far-infrared wavelength range; Based on the change curve, materials whose peak wavelength is located in the far-infrared wavelength range are selected to determine the set of directional emission materials and screen optical spacer layer materials; Based on the directional emission material set and the physicochemical parameters of adjacent thin film layers, and with the goal of satisfying interface stress buffering and optical admittance matching, the matching layer material and the barrier layer material are screened and determined.

[0011] Preferably, the optical spacer layer material is at least one of ZnS, ZnSe, Ge, or Si; the barrier layer material is HfO2; and the matching layer material is at least one of TiO2, Al2O3, or MgO.

[0012] Preferably, the mechanical protective layer material is at least one of Al2O3, AlN, SiC, or diamond-like carbon.

[0013] Preferably, based on the electromagnetic parameters of the material and the target directional radiation angle, the initial thickness range of each layer of material in the directional emission module is calculated, wherein the target directional radiation angle is 70°-80°; wherein the calculation formula for the initial thickness range of each layer of material is as follows: In the formula, The initial thickness of the material. For wavelength, Target-oriented radiation angle, Let be the dielectric constant of the material, and Im be the imaginary part of the complex number.

[0014] Preferably, the preset optimization target is: to make the average transmittance of the multilayer film in the mid- and far-infrared band not less than 70%, and the emissivity in the far-infrared band and within the target directional radiation angle not less than 0.7.

[0015] Preferably, the process parameters for magnetron sputtering are as follows: sputtering power of 30~180W, sputtering gas pressure of 0.3~1.5Pa, and substrate rotation speed of 3~12rad / min.

[0016] More preferably, the mechanical protective layer is deposited using a high-pulse magnetron sputtering process; wherein the sputtering power is 90~110W, the sputtering pulse frequency is 1900~2100Hz, the pulse width is 28~32us, the sputtering gas pressure is 0.4~0.6Pa, and the substrate rotation speed is 3~12rad / min.

[0017] Secondly, embodiments of the present invention also provide a multi-spectrum compatible camouflage and protection film, which is prepared using the preparation method described in any one of the first aspects above.

[0018] Preferably, from the incident surface to the substrate direction, the directional emission module includes a first matching layer, an optical spacer layer, a second matching layer, and a blocking layer arranged sequentially from top to bottom.

[0019] More preferably, from the incident surface to the substrate direction, the protective film structure is as follows: the mechanical protective layer is composed of Al2O3 or AlN, the first matching layer is composed of TiO2 or SiO2, the optical spacer layer is composed of ZnS or Ge, the second matching layer is composed of MgO, the blocking layer is composed of HfO2, and the phase change functional layer is composed of In3SbTe2 or Ge2Sb2Te5.

[0020] More preferably, the thickness of the mechanical protective layer is 140~180nm; when the first matching layer is composed of TiO2, the thickness is 80~140nm; when the first matching layer is composed of SiO2, the thickness is 100~180nm; when the optical spacer layer is composed of ZnS, the thickness is 2300~2700nm; when the optical spacer layer is composed of Ge, the thickness is 600~650nm; the thickness of the second matching layer is 90~110nm; the thickness of the blocking layer is 120~160nm; when the phase change functional layer is composed of In3SbTe2, the thickness of the second matching layer is 80~120nm; when the phase change functional layer is composed of Ge2Sb2Te5, the thickness is 100~140nm.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects: In this invention, firstly, based on the optical and electrical properties of phase change materials in the mid- and far-infrared bands, phase change functional layer materials capable of reversible phase transitions are screened and determined. In its amorphous state, this material allows the thin film to maintain high transmittance in the mid-infrared band to meet signal detection and heat dissipation requirements. When it transforms into a crystalline state, the thin film switches to a multifunctional camouflage and protection state, exhibiting low emissivity in the mid-infrared band for thermal camouflage and high-angle directional emission characteristics in the far-infrared band for efficient heat radiation. In this state, it achieves up to 99% electromagnetic shielding efficiency in the 2-18 GHz microwave band. Subsequently, a directional emission module is constructed by further screening thin film materials, and a matching layer and a blocking layer are introduced as a stress buffer system, effectively avoiding the problems of interface cracking and element diffusion between the high-hardness directional emission layer and the soft phase change functional layer. By combining the aforementioned phase change functional layer, directional emission module, and mechanical protection layer, a Fabry-Perot resonant cavity type multilayer thin film structure is constructed. Parametric scanning is used to perform multi-objective collaborative optimization of the optical spacer layer thickness, thereby determining the optimal thickness of each layer. Finally, by sequentially depositing each thin film layer through magnetron sputtering, the resulting integrated thin film possesses both excellent mechanical hardness and interfacial stability, enabling it to withstand complex environments such as sand and dust. In this way, the formed multilayer thin film combines dynamic infrared camouflage, efficient electromagnetic shielding, and thermal management performance. Furthermore, while ensuring reliable mechanical protection, it achieves a synergistic protection effect of intelligent response and multi-spectral compatibility. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 A schematic diagram of the overall structure of a multi-spectrum compatible camouflage and protection film provided in an embodiment of the present invention; Figure 2 Transmittance variation of a multi-spectral compatible camouflage and protection film at different angles in the 3-14μm band, provided as an embodiment of the present invention; Figure 3 Average infrared emissivity curves of a multi-spectrum compatible camouflage and protection film in the 3-5μm and 8-14μm bands provided for embodiments of the present invention; Figure 4 Radiometric map of a multi-spectral compatible camouflage and protection film at 500K, provided as an embodiment of the present invention; Figure 5Electromagnetic shielding effectiveness diagram of a multi-spectrum compatible camouflage and protection film in the 2-18GHz band, provided for embodiments of the present invention; Figure 6 This is a hardness and modulus test chart of a multi-spectral compatible camouflage and protection film provided for an embodiment of the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0025] To meet the collaborative needs of applications such as energy-saving windows in smart buildings, protective windows for precision instruments, and windows and skins for aerospace vehicles, this invention proposes a controllable film for mid- and far-infrared and microwave camouflage. When high transmittance is required, it can achieve high transmittance in the mid- and far-infrared bands; when camouflage is needed, it can simultaneously achieve low emissivity in the mid-infrared band and directional angular emission in the far-infrared band, thus balancing heat dissipation and stealth; when electromagnetic component protection is required, it can achieve shielding effectiveness through microwave reflection; simultaneously, while ensuring the film achieves the above functions, it also needs to possess good mechanical protection properties and be able to withstand complex environments such as sand and dust.

[0026] Therefore, embodiments of the present invention provide a method for preparing a multi-spectrum compatible camouflage and protection film. From the incident surface to the substrate, the film sequentially includes a mechanical protection layer, a directional emission module, and a phase change functional layer. The phase change functional layer is capable of undergoing a reversible phase transition between an amorphous state and a crystalline state. The directional emission module is capable of forming a Fabry-Perot resonant cavity structure with the mechanical protection layer to generate directional radiation in the far-infrared band. The preparation method includes: Based on the optical and electrical properties of phase change materials in the mid- and far-infrared bands, phase change functional layer materials were screened and determined. Based on far-infrared directional radiation performance and interface performance, materials for directional emission modules are screened and determined; wherein, the materials for directional emission modules include optical spacer layer materials, blocking layer materials and matching layer materials; The materials of the directional launch module, the phase change functional layer, and the mechanical protection layer are coupled to construct a Fabry-Perot resonant cavity type multilayer thin film structure, and the initial thickness range of each layer in the directional launch module is calculated. An optical simulation model of the multilayer thin film structure is constructed, and a parameterized scan is performed with the initial thickness range of the optical spacer material as a variable. The transmittance and directional emissivity of the multilayer thin film in the mid- and far-infrared bands are calculated, and the optimal thickness of each thin film is determined according to the preset optimization target. Based on the multilayer thin film structure and the optimal thickness of the multilayer thin film, the multi-spectral compatible camouflage and protection film is prepared by sequentially depositing each layer of thin film material on the substrate using a magnetron sputtering process.

[0027] In this embodiment of the invention, firstly, based on the optical and electrical properties of phase change materials in the mid- and far-infrared bands, phase change functional layer materials capable of reversible phase transitions are screened and determined. In its amorphous state, this material allows the thin film to maintain high transmittance in the mid-infrared band to meet signal detection and heat dissipation requirements. When it transforms into a crystalline state, the thin film switches to a multifunctional camouflage and protection state, exhibiting low emissivity in the mid-infrared band for thermal camouflage, and high-angle directional emission characteristics in the far-infrared band for efficient heat radiation. In this state, it achieves up to 99% electromagnetic shielding efficiency in the 2-18 GHz microwave band. Subsequently, a directional emission module is constructed by further screening thin film materials, and a matching layer and a blocking layer are introduced as a stress buffer system, effectively avoiding the problems of interface cracking and element diffusion between the high-hardness directional emission layer and the soft phase change functional layer. By combining the aforementioned phase change functional layer, directional emission module, and mechanical protection layer, a Fabry-Perot resonant cavity type multilayer thin film structure is constructed, and parametric scanning is used to perform multi-objective collaborative optimization of the optical spacer layer thickness, thereby determining the optimal thickness of each layer. Finally, by sequentially depositing each thin film layer through magnetron sputtering, the resulting integrated thin film possesses both excellent mechanical hardness and interfacial stability, enabling it to withstand complex environments such as sand and dust. In this way, the formed multilayer thin film combines dynamic infrared camouflage, efficient electromagnetic shielding, and thermal management performance. Furthermore, while ensuring reliable mechanical protection, it achieves a synergistic protection effect of intelligent response and multi-spectral compatibility.

[0028] According to some preferred embodiments, the screening and determination of phase change functional layer materials based on the optical and electrical properties of phase change materials in the mid-infrared and far-infrared bands includes: The electrical and optical parameters of various phase change materials are obtained; wherein the electrical parameters include sheet resistance and dielectric constant; and the optical parameters include refractive index and extinction coefficient. Based on the electrical parameters of phase change materials in the crystalline state, phase change materials with sheet resistance close to that of metals and dielectric constants approaching zero are screened to obtain a material set. Based on the optical constants of each material in the amorphous and crystalline states in the material set, and based on preset screening conditions, the materials in the material set are screened to determine the phase change functional layer material; wherein, the preset screening conditions are as follows: the material is in a dielectric transparent state in the amorphous state and in a metallic reflective state in the crystalline state, and the material can form optical admittance matching with the adjacent directional emission module in both the crystalline and amorphous states.

[0029] According to some preferred embodiments, the phase change functional layer material is one or more of In3SbTe2, Ge2Sb2Te5, VO2, or their doped and modified materials.

[0030] In this embodiment of the invention, firstly, phase change materials with sheet resistance close to that of metals and dielectric constants approaching zero are screened based on electrical parameters, enabling the materials to achieve efficient microwave electromagnetic shielding in the crystalline state. Then, based on the optical constants of each material in the amorphous and crystalline states, and through their optical properties in the mid-infrared (3-5 μm) and far-infrared (8-14 μm) bands, materials with extinction coefficients approaching zero and refractive indices between 3 and 4 in the mid- and far-infrared bands in the amorphous state are screened to ensure high transmittance of the thin film to infrared signals. Simultaneously, materials with refractive indices greater than 5 in the far-infrared band in the crystalline state are screened to ensure high reflectivity in the mid- and far-infrared bands. Under the premise of satisfying the above optical performance, materials whose optical constants (such as refractive index and extinction coefficient) are matched with the optical admittance of the directional emission module (such as the blocking layer) and whose phase change temperature is suitable are further screened. Ultimately, the screened material can undergo a reversible phase transition between amorphous and crystalline states. In the amorphous state, it exhibits dielectric permeability and high transmittance in the far-infrared band; in the crystalline state, it exhibits metallic reflectivity, electromagnetic shielding properties, and high reflectivity in the far-infrared band, laying the foundation for the dynamic response of subsequent multilayer thin films.

[0031] According to some preferred embodiments, the process of screening and determining directional emission module materials based on far-infrared directional radiation performance and interface performance includes: Based on the obtained complex dielectric functions of various thin film materials, calculate the variation curve of the function Im(-1 / ε) corresponding to the complex dielectric function in the far-infrared wavelength range; Based on the change curve, materials whose peak wavelength is located in the far-infrared wavelength range are selected to determine the set of directional emission materials and screen optical spacer layer materials; Based on the directional emission material set and the physicochemical parameters of adjacent thin film layers, and with the goal of satisfying interface stress buffering and optical admittance matching, the matching layer material and the barrier layer material are screened and determined.

[0032] According to some preferred embodiments, the optical spacer layer material is at least one of ZnS, ZnSe, Ge or Si; the barrier layer material is HfO2; the matching layer material is at least one of TiO2, Al2O3 or MgO; and the mechanical protection layer material is at least one of Al2O3, AlN, SiC or diamond-like carbon.

[0033] To address the challenge of balancing optical performance and high-hardness mechanical properties in dusty environments—specifically, to ensure excellent adhesion, strength, and hardness of multilayer films while simultaneously meeting the optical admittance requirements for infrared transmittance and camouflage—and to overcome the inherent conflict between high-hardness film layers prepared at high temperatures or high energy levels and low-heat-resistance chalcogenide phase change materials, while also meeting the requirements for high transmittance and directional radiation performance in the mid- and far-infrared bands, this invention first selects materials with high-angle directional radiation in the far-infrared band as a set of directional emission materials based on complex dielectric functions. Then, suitable materials are selected from these materials to serve as optical spacers, enabling them to form a Fabry-Perot resonant cavity structure with the matching layer, blocking layer, and mechanical protection layer, thereby achieving wide-band, high-angle directional absorption. Building upon this foundation, materials for the matching and barrier layers are further screened based on the complex permittivity and physicochemical parameters (such as coefficient of thermal expansion, film density, chemical inertness, and mechanical properties). Specifically, matching layer materials are selected where the peak value of the complex permittivity and physical parameters fall between those of the phase change functional layer material and the adjacent film material. This achieves optical admittance matching and thermal stress matching, and serves as a stress buffer layer to suppress interfacial cracking and element diffusion caused by the direct deposition of high-hardness oxides. Simultaneously, materials with good density and chemical inertness are selected as barrier layers to block the migration and diffusion of elements from the phase change functional layer. Furthermore, their coefficient of thermal expansion and complex permittivity are considered concurrently during the selection process to ensure thermal expansion matching and optical admittance matching with adjacent film layers, respectively. In summary, by selecting materials using the above method, the resulting directional emission module not only forms an optical resonant structure with the mechanical protection layer but also solves multiple problems such as optical matching, thermal stress buffering, and environmental mechanical protection between film materials. Ultimately, this helps ensure that multilayer films possess both excellent optical functionality and mechanical durability in complex environments.

[0034] It should be noted that in this embodiment of the invention, the above-mentioned material is selected as the top protective layer that is in direct contact with the external environment. It not only provides high hardness and high wear resistance to resist mechanical damage such as sand and dust scratches, but also can work together with the optical spacer layer and matching layer in the adjacent directional emission module to form a Fabry-Perot resonant cavity structure, thereby generating high-angle directional emission in a specific far-infrared band.

[0035] According to some preferred embodiments, based on the electromagnetic parameters of the material and the target directional radiation angle, the initial thickness range of each layer of material in the directional emission module is calculated, wherein the target directional radiation angle is 70°-80°; wherein the calculation formula for the initial thickness range of each layer of material is as follows: In the formula, The initial thickness of the material. For wavelength, Target-oriented radiation angle, Let be the dielectric constant of the material, and Im be the imaginary part of the complex number.

[0036] According to some preferred embodiments, the preset optimization target is: to make the average transmittance of the multilayer film in the mid- and far-infrared band not less than 70%, and the emissivity in the far-infrared band and within the target directional radiation angle not less than 0.7.

[0037] In this embodiment of the invention, after selecting and determining the materials for the directional emission module, the initial thickness range of each layer of material in the directional emission module is calculated based on the electromagnetic parameters of the materials and the target directional radiation angle, which helps to shorten the subsequent simulation optimization time. Then, an optical simulation model of the multilayer thin film structure is constructed using multiphysics software, and parametric scanning is performed with the initial thickness range of the optical spacer layer material as a variable. The overall transmittance and directional emissivity of the multilayer thin film in the mid- and far-infrared bands are simulated and calculated. At the same time, the optimal thickness of each thin film is determined by selecting from the calculation results according to the preset dual optimization targets of transmittance and emissivity, which is conducive to the design of camouflage and protection films that are compatible with multiple spectra.

[0038] According to some preferred embodiments, the process parameters of the magnetron sputtering are as follows: sputtering power of 30~180W (e.g., 30W, 40W, 50W, 60W, 70W, 80W, 90W, 100W, 110W, 120W, 130W, 140W, 150W, 160W, 170W or 180W), sputtering gas pressure of 0.3~1.5Pa (e.g., 0.3Pa, 0.5Pa, 0.8Pa, 1.0Pa, 1.2Pa or 1.5Pa), sputtering time of 2~5min (e.g., 2min, 3min, 4min or 5min), and substrate rotation speed of 3~12rad / min (e.g., 3rad / min, 5rad / min, 8rad / min, 10rad / min or 12rad / min).

[0039] The process parameters used in sputtering vary depending on the thin film material layer. According to some specific implementation methods, when preparing phase change functional layer materials, the target material is selected as In3SbTe2, Ge2Sb2Te5, or VO2, the sputtering gas is argon, the argon flow rate is 25-35 sccm, the sputtering power is 145-155 W, the sputtering pressure is 0.7-0.9 Pa, the sputtering time is 2-5 min, and the substrate rotation speed is 10-15 rad / min. When preparing optical spacer layer materials, the target material is selected as ZnS, ZnSe, Ge, or Si, the sputtering gas is argon, the argon flow rate is 25-35 sccm, the sputtering power is 90-110 W, the sputtering pressure is 0.5-0.7 Pa, the sputtering time is 2-5 min, and the substrate rotation speed is 10-15 rad / min. When preparing barrier layer materials, the target material is selected as HfO2, and the sputtering gas is argon. For the preparation of MgO matching layer materials, the target material is MgO, the sputtering gas is argon, the argon flow rate is 25~35 sccm, the sputtering power is 110~130W, the sputtering pressure is 0.4~0.6Pa, the sputtering time is 2~5min, and the substrate rotation speed is 10~15rad / min. For the preparation of TiO2 matching layer materials, the target material is TiO2, the sputtering gases are argon and oxygen, the argon flow rate is 25~35 sccm, the oxygen flow rate is 0.1~0.3 sccm, the sputtering power is 90~110W, the sputtering pressure is 0.5~0.7Pa, the sputtering time is 2~5min, and the substrate rotation speed is 10~15rad / min.

[0040] According to some preferred embodiments, the mechanical protective layer is deposited using a high-pulse magnetron sputtering process; wherein the sputtering gas includes argon and oxygen, the sputtering power is 90~110W (e.g., 90W, 100W or 110W), the sputtering pulse frequency is 1900~2100Hz (e.g., 1900Hz, 2000Hz or 2100Hz), the pulse width is 28~32µs (e.g., 28µs, 29µs, 30µs, 31µs or 32µs), the sputtering pressure is 0.4~0.6Pa (e.g., 0.4Pa, 0.5Pa or 0.6Pa), the sputtering time is 2~5min (e.g., 2min, 3min, 4min or 5min), and the substrate rotation speed is 3~12rad / min (e.g., 3rad / min, 5rad / min, 8rad / min, 10rad / min or 12rad / min).

[0041] In this embodiment of the invention, considering that traditional high-temperature and high-pulse energy impacts can easily cause stoichiometric shifts in the film layer, leading to film failure, a matching layer is first introduced as a stress buffer layer during the film layer design process. Furthermore, high-power pulsed magnetron sputtering technology is employed during the fabrication process to effectively suppress interface cracking and element diffusion. Specifically, when fabricating the mechanical protective layer, Al or Si is selected as the target material, and argon and oxygen are introduced as sputtering gases. The argon flow rate is 95-105 sccm, and the oxygen flow rate is 0.5-1.5 sccm. The sputtering power, sputtering frequency, pulse width, and other process parameters are controlled in a coordinated manner, thereby achieving a synergistic improvement in film layer stress optimization and structural compactness. This ensures that the final film not only achieves functional coupling between multi-spectral compatible camouflage and efficient heat dissipation performance but also guarantees its stability in complex dusty environments.

[0042] This invention also provides a multi-spectral compatible camouflage and protection film obtained by any of the above-described preparation methods.

[0043] According to some preferred embodiments, from the incident surface to the substrate, the directional emission module includes a first matching layer, an optical spacer layer, a second matching layer, and a blocking layer arranged sequentially from top to bottom; from the incident surface to the substrate, the protective film structure is as follows: the mechanical protective layer is composed of Al2O3 or AlN, the first matching layer is composed of TiO2 or SiO2, the optical spacer layer is composed of ZnS or Ge, the second matching layer is composed of MgO, the blocking layer is composed of HfO2, and the phase change functional layer is composed of In3SbTe2 or Ge2Sb2Te5; the thickness of the mechanical protective layer is 140. The thickness is ~180nm (e.g., it can be 140nm, 150nm, 160nm, 170nm, or 180nm); when the matching layer is composed of TiO2, the thickness is 80~140nm (e.g., it can be 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, or 140nm); when the matching layer is composed of SiO2, the thickness is 100~180nm (e.g., it can be 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, 160nm, or 170nm). Or 180nm); when the optical spacer layer is composed of ZnS, the thickness is 2300~2700nm (e.g., 2300nm, 2400nm, 2500nm, 2600nm or 2700nm); when the optical spacer layer is composed of Ge, the thickness is 600~650nm (e.g., 600nm, 610nm, 620nm, 630nm, 640nm or 650nm); the thickness of the second matching layer is 90~110nm (e.g., 90nm, 100nm or 110nm); the resistance The thickness of the barrier layer is 120~160nm (e.g., it can be 120nm, 130nm, 140nm, 150nm or 160nm); when the phase change functional layer is composed of In3SbTe2, the thickness of the second matching layer is 80~120nm (e.g., it can be 80nm, 90nm, 100nm, 110nm or 120nm); when the phase change functional layer is composed of Ge2Sb2Te5, the thickness is 100~140nm (e.g., it can be 100nm, 110nm, 120nm, 130nm or 140nm).

[0044] Because Al2O3 exhibits strong phonon absorption in the far-infrared band (8-14 μm), it is generally considered unsuitable as a top layer material for long-wave infrared windows. However, in this embodiment of the invention, by precisely controlling its thickness and achieving a specific admittance match with the underlying directional emission module, the absorption in this band is suppressed using interference effects. Simultaneously, its excellent mechanical properties are fully utilized, successfully designing it as a mechanical protective layer with both infrared functionality and protective characteristics. Subsequently, by selecting a suitable phase-change functional layer material and optimizing its thickness, it is determined that if the thickness is too low, it cannot meet the requirements. The shielding effectiveness fails due to the skin depth requirement of radar waves; if the thickness is too high, the infrared transmittance will decrease due to intrinsic absorption in the amorphous state. In this embodiment of the invention, an extremely narrow thickness optimization window was found in the gap between infrared transmission and electromagnetic shielding through extensive experiments. In addition, considering that depositing high-stress, high-hardness oxide films on soft, low-melting-point phase change functional layer materials is prone to process failure, a matching layer is introduced as a stress buffer layer when designing the directional emission module, and high-power pulsed magnetron sputtering technology is used to effectively solve the problems of interface cracking and element diffusion. In summary, through the selection of materials for each thin film layer, the optimization design of the thickness, and the systematic design of specific preparation processes, the obtained thin film material not only achieves multi-spectral compatible camouflage and heat dissipation functions, but also has an excellent hardness of up to 15.1 GPa.

[0045] To more clearly illustrate the technical solution and advantages of the present invention, the following examples provide a detailed description of a multi-spectral compatible camouflage and protection film and its preparation method.

[0046] Example The optimal structure and thickness of the thin film were screened and calculated using the above method, such as... Figure 1 As shown, the thin film, from the incident surface to the substrate, comprises, in sequence, a mechanical protective layer (Al2O3 with a thickness of 160 nm), a first matching layer (TiO2 with a thickness of 110 nm), an optical spacer layer (ZnS with a thickness of 2500 nm), a second matching layer (MgO with a thickness of 100 nm), a barrier layer (HfO2 with a thickness of 140 nm), and a phase change functional layer (In3SbTe2 with a thickness of 100 nm).

[0047] The Si substrate was cleaned three times with 99.99% alcohol and ultrasonic cleaning. The cleaned substrate was then dried and fixed on the substrate holder (maintaining good thermal contact). The deposition chamber of the magnetron sputtering equipment was evacuated to a vacuum level of ≤5×10⁻⁶. -4 Pa, introduce high-purity argon gas to a working pressure of 5Pa, open the baffle to protect the substrate, turn on the stepper motor, and maintain the workpiece stage speed at 8rad / min; Adjust the RF power supply to 150W, argon gas to 30sccm, sputtering gas pressure to 0.8Pa, and start the power supply. Perform pre-sputtering of In3SbTe2 target material for 3 minutes. Then open the baffle and start formal deposition. According to the film thickness gauge, sputter the IST film thickness to 100nm of the target. After the deposition thickness is reached, close the baffle and turn off the target power supply to obtain the phase change functional layer. Switch the RF power supply to the HfO2 target, adjust the sputtering power to 100W, use argon gas at 30sccm, and pre-sputter at a sputtering pressure of 0.5Pa for 3 minutes. Then open the baffle and begin the formal deposition. According to the film thickness gauge, sputter the HfO2 film thickness to the target of 140nm. After the deposition thickness is reached, close the baffle and turn off the target power supply to obtain the barrier layer. Switch the RF power supply to the MgO target, adjust the sputtering power to 120W, use argon gas at 30sccm, and pre-sputter at a sputtering pressure of 0.5Pa for 5 minutes. Then open the baffle and begin the formal deposition. According to the film thickness gauge, sputter the MgO film thickness to the target of 100nm. After reaching the deposition thickness, close the baffle and turn off the target power supply to obtain the second matching layer. Switch the RF power supply to the ZnS target, adjust the sputtering power to 100W, use argon gas at 30 sccm, and pre-sputter at a sputtering pressure of 0.6 Pa for 5 minutes. Then open the baffle and begin the formal deposition. According to the film thickness gauge, sputter the ZnS film thickness to the target of 2500 nm. After reaching the deposition thickness, close the baffle and turn off the target power supply to obtain the optical spacer layer. Switch the RF power supply to the TiO2 target, adjust the sputtering power to 100W, use argon gas at 30 sccm, oxygen gas at 0.2 sccm, and sputtering pressure at 0.6 Pa for 5 minutes of pre-sputtering. Then open the baffle and begin formal deposition. According to the film thickness gauge, sputter the TiO2 film thickness to the target of 110 nm. After reaching the deposition thickness, close the baffle and turn off the target power supply to obtain the first matching layer. Switch the high-pulse power supply to the Al target, adjust the sputtering power to 100W, argon to 99 sccm, oxygen to 1 sccm, sputtering pulse frequency to 2000Hz, pulse width to 30µs, sputtering pressure to 0.5Pa, pre-sputter for 5 minutes, then open the baffle and begin formal deposition. According to the film thickness gauge, sputter the Al2O3 film thickness to the target of 160nm. After reaching the deposition thickness, close the baffle, turn off the target power supply, and turn off the oxygen to obtain the mechanical protective layer. Subsequently, argon gas was continued to flow for 10 minutes until the sputtering chamber temperature reached room temperature (25°C), allowing the substrate to cool under an inert atmosphere. Finally, the argon gas source was turned off, and atmospheric gas was introduced into the chamber. After the gas pressure was balanced, the chamber was opened, the sample was removed, and a multi-spectral compatible camouflage and protective film was obtained.

[0048] The performance of the multi-spectral compatible camouflage and protection films prepared in the above embodiments was tested. Figures 2 to 6As can be seen from this, the thin film in the embodiments of the present invention achieves dynamic multifunctional synergy; specifically, it is composed of... Figure 2 As can be seen, when the phase change functional layer is in the amorphous state (aIST state), the film exhibits high transmittance in both the 3-5 μm and 8-14 μm wavelength ranges, with an average transmittance exceeding 75%; when the phase change functional layer transforms from the amorphous to the crystalline state (cIST state), such as Figure 3 As shown, the thin film exhibits a low emissivity of 0.25 in the 3-5 μm band for mid-infrared camouflage, while achieving a high directional emissivity of up to 0.7 in the 8-14 μm band at high angles of 70°-80°, effectively realizing directional heat radiation; Figure 4 As shown, the integral of the radiation intensity (shaded area) of the device in the 8-14 μm band at a temperature of 500 K yields a radiative heat flux density of 733 W·m. -2 The heat dissipation effect is significant, thus achieving both infrared camouflage and efficient heat dissipation in a coordinated manner; in terms of electromagnetic protection, such as Figure 5 As shown, in the amorphous state, the thin film exhibits an average electromagnetic shielding performance superior to -19 dB in the 2-18 GHz band, achieving a shielding efficiency of 99%; regarding mechanical properties, such as... Figure 6 As shown, through integrated optical admittance matching and mechanical protection design, the overall hardness of the film reaches 15.1 GPa, and the modulus reaches 264.2 GPa. However, if the mechanical protection layer is prepared using a conventional radio frequency magnetron sputtering method (i.e., without pulse application), the overall hardness of the film is only 7.4 GPa after testing. The above test results demonstrate that the film in this embodiment effectively achieves the coupling of high transmittance and high-temperature camouflage switching, electromagnetic shielding, and mechanical protection.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a multi-spectral compatible camouflage and protection film, characterized in that, From the incident surface to the substrate, the thin film sequentially includes a mechanical protective layer, a directional emission module, and a phase change functional layer; wherein, the phase change functional layer is capable of undergoing a reversible phase transition between an amorphous state and a crystalline state; the directional emission module is capable of forming a Fabry-Perot resonant cavity structure with the mechanical protective layer to generate directional radiation in the far-infrared band; The preparation method includes: Based on the optical and electrical properties of phase change materials in the mid- and far-infrared bands, phase change functional layer materials were screened and determined. Based on far-infrared directional radiation performance and interface performance, materials for directional emission modules are screened and determined; wherein, the materials for directional emission modules include optical spacer layer materials, blocking layer materials and matching layer materials; The materials of the directional launch module, the phase change functional layer, and the mechanical protection layer are coupled to construct a Fabry-Perot resonant cavity type multilayer thin film structure, and the initial thickness range of each layer in the directional launch module is calculated. An optical simulation model of the multilayer thin film structure is constructed, and a parameterized scan is performed with the initial thickness range of the optical spacer material as a variable. The transmittance and directional emissivity of the multilayer thin film in the mid- and far-infrared bands are calculated, and the optimal thickness of each thin film is determined according to the preset optimization target. Based on the multilayer thin film structure and the optimal thickness of the multilayer thin film, the multi-spectral compatible camouflage and protection film is prepared by sequentially depositing each layer of thin film material on the substrate using a magnetron sputtering process.

2. The preparation method according to claim 1, characterized in that, The process of screening and determining phase change functional layer materials based on their optical and electrical properties in the mid-infrared and far-infrared bands includes: The electrical and optical parameters of various phase change materials are obtained; wherein the electrical parameters include sheet resistance and dielectric constant; and the optical parameters include refractive index and extinction coefficient. Based on the electrical parameters of phase change materials in the crystalline state, phase change materials with sheet resistance close to that of metals and dielectric constants approaching zero are screened to obtain a material set. Based on the optical constants of each material in the amorphous and crystalline states in the material set, and based on preset screening conditions, the materials in the material set are screened to determine the phase change functional layer material; wherein, the preset screening conditions are as follows: the material is in a dielectric transparent state in the amorphous state and in a metallic reflective state in the crystalline state, and the material can form optical admittance matching with the adjacent directional emission module in the far-infrared band in both the crystalline and amorphous states.

3. The preparation method according to claim 1 or 2, characterized in that, The phase change functional layer material is one or more of In3SbTe2, Ge2Sb2Te5, VO2, or their doped and modified materials.

4. The preparation method according to claim 1, characterized in that, The process of screening and determining materials for directional emission modules based on far-infrared directional radiation performance and interface properties includes: Based on the obtained complex dielectric functions of various thin film materials, calculate the variation curve of the function Im(-1 / ε) corresponding to the complex dielectric function in the far-infrared wavelength range; Based on the change curve, materials whose peak wavelength is located in the far-infrared wavelength range are selected to determine the set of directional emission materials and then select optical spacer layer materials from them. Based on the directional emission material set and the physicochemical parameters of adjacent thin film layers, and with the goal of satisfying interface stress buffering and optical admittance matching, the matching layer material and the barrier layer material are screened and determined.

5. The preparation method according to claim 1, characterized in that, The optical spacer layer material is at least one of ZnS, ZnSe, Ge, or Si; the barrier layer material is HfO2; the matching layer material is at least one of TiO2, Al2O3, or MgO; and / or The mechanical protective layer material is at least one of Al2O3, AlN, SiC, or diamond-like carbon.

6. The preparation method according to claim 1, characterized in that, Based on the electromagnetic parameters of the material and the target directional radiation angle, the initial thickness range of each layer of material in the directional emission module is calculated, where the target directional radiation angle is 70°-80°; the calculation formula for the initial thickness range of each layer of material is as follows: In the formula, The initial thickness of the material. For wavelength, Target-oriented radiation angle, Let be the dielectric constant of the material, and Im be the imaginary part of the complex number; and / or The preset optimization target is to ensure that the average transmittance of the multilayer film in the mid- and far-infrared band is not less than 70%, and the emissivity in the far-infrared band and within the target directional radiation angle is not less than 0.

7.

7. The preparation method according to claim 1, characterized in that, The magnetron sputtering process parameters are as follows: sputtering power of 30~180W, sputtering gas pressure of 0.3~1.5Pa, and substrate rotation speed of 3~12rad / min; and / or The mechanical protective layer is deposited using a high-pulse magnetron sputtering process; wherein the sputtering power is 90~110W, the sputtering frequency is 1900~2100Hz, the pulse width is 28~32us, the sputtering pressure is 0.4~0.6Pa, and the substrate rotation speed is 3~12rad / min.

8. A multi-spectrum compatible camouflage and protection film, characterized in that, It is prepared by any one of claims 1 to 7.

9. The multi-spectrum compatible camouflage and protection film according to claim 8, characterized in that, From the incident surface to the substrate, the directional emission module includes, from top to bottom, a first matching layer, an optical spacer layer, a second matching layer, and a blocking layer; and / or From the incident surface to the substrate, the protective film structure is as follows: the mechanical protective layer is composed of Al2O3 or AlN, the first matching layer is composed of TiO2 or SiO2, the optical spacer layer is composed of ZnS or Ge, the second matching layer is composed of MgO, the blocking layer is composed of HfO2, and the phase change functional layer is composed of In3SbTe2 or Ge2Sb2Te5.

10. The multi-spectrum compatible camouflage and protection film according to claim 9, characterized in that, The thickness of the mechanical protective layer is 140~180nm; when the first matching layer is composed of TiO2, the thickness is 80~140nm; when the first matching layer is composed of SiO2, the thickness is 100~180nm; when the optical spacer layer is composed of ZnS, the thickness is 2300~2700nm; when the optical spacer layer is composed of Ge, the thickness is 600~650nm; the thickness of the second matching layer is 90~110nm; the thickness of the barrier layer is 120~160nm; when the phase change functional layer is composed of In3SbTe2, the thickness of the second matching layer is 80~120nm; when the phase change functional layer is composed of Ge2Sb2Te5, the thickness is 100~140nm.

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