W-vo2-based mid- and far-infrared space thermal control multilayer film and method of making and using same

Abstract

The application discloses a kind of W-VO2-based middle far infrared spaceflight thermal control multilayer film and its preparation and application method.The film includes aluminium substrate, inorganic medium layer, W-VO2 functional layer and protective layer in turn from bottom to top.The medium layer is used to constitute interference cavity;W-VO2 functional layer is deposited using magnetron sputtering method and is annealed, realizes phase change crystallization and the dynamic control of infrared emissivity;Protective layer is used to protect functional layer from environmental oxidation and mechanical damage, while the influence on infrared performance is limited.By adjusting the proportion of W element doping and the thickness of each layer, the phase transition temperature can be adjusted in the range of 15~68℃, and the emissivity modulation rate of 2~25μm wave band is 0.5-0.7, the visible reflectivity is 0.55-0.65.No obvious oxidation occurs after being placed in air for two weeks.The film has simple structure, controllable preparation process and stable performance, and is suitable for spacecraft cabin, battery panel, optical load and other aspects.

Description

Technical Field

[0001] This invention relates to the field of intelligent thermal control materials technology, specifically to a mid-to-far-infrared aerospace thermal control multilayer thin film based on W-VO2 and its preparation and application methods. Background Technology

[0002] During their operation in orbit, spacecraft face extremely complex and harsh thermal environments: in sunny areas, spacecraft are heated by intense solar radiation, with surface temperatures rising above 100°C; while in shadow areas, temperatures plummet to below -100°C due to heat dissipation through radiation into deep space. This periodic and extreme alternation of hot and cold places extremely high demands on the adaptability and stability of the spacecraft's thermal control system.

[0003] Traditional passive thermal control technologies employ fixed emissivity coatings, which offer advantages such as simple structure and high reliability. However, their thermal radiation performance parameters remain constant, making them unable to dynamically respond to drastic changes in the space environment. This leads to large temperature fluctuations and excessive energy consumption in complex thermal environments, severely impacting the efficiency and lifespan of onboard equipment and making it difficult to meet the demands of next-generation space missions such as high-power payloads, large space stations, and deep space exploration.

[0004] Against this backdrop, intelligent thermal control materials, as novel functional materials capable of autonomously adjusting their thermal radiation performance according to changes in ambient temperature, offer a new approach to overcoming the aforementioned technical bottlenecks. Among them, vanadium dioxide (VO2)-based thermochromic materials have become a research hotspot in the field of intelligent thermal control due to their reversible metal-insulator phase transition around 68°C, accompanied by a significant change in infrared emissivity during the phase transition. When the temperature is below the phase transition temperature, VO2 is in a semiconductor state with high infrared emissivity, which is beneficial for spacecraft heat dissipation; when the temperature is above the phase transition temperature, VO2 transforms into a metallic state, reducing infrared emissivity and minimizing heat loss. This adaptive adjustment characteristic makes it a promising candidate for application in the aerospace thermal control field.

[0005] However, pure VO2 materials suffer from three key drawbacks that limit their practical engineering applications in the aerospace field: first, their phase transition temperature is too high (68℃), which does not match the actual operating temperature range of spacecraft; second, the range of infrared emissivity modulation is limited, and the thermal control effect fails to reach the ideal level; and third, their environmental stability is poor, making them susceptible to failure due to factors such as oxygen and water vapor in the space environment. Research shows that doping with metal elements such as W can effectively reduce the phase transition temperature of VO2, making it more suitable for the operating temperature range of spacecraft. Simultaneously, a well-designed multilayer thin-film structure including a high-reflectivity substrate layer, a functional layer, and a protective layer can further improve the material's infrared radiation modulation performance and environmental adaptability.

[0006] Currently, although research on VO2-based smart thermal control materials has been carried out both domestically and internationally, many challenges remain at the core technology level: the thin film structure design lacks systematic optimization, making it difficult to balance infrared control performance and environmental stability; the precise control of preparation process parameters is difficult, affecting product consistency; the performance control effect in the mid- and far-infrared bands is not good, failing to fully meet the thermal control requirements of spacecraft; and the long-term space environment stability is insufficient, and a mature engineering application solution has not yet been formed.

[0007] Therefore, developing a W-doped VO2-based mid-to-far-infrared intelligent thermal control film with excellent performance, controllable preparation process, and strong environmental stability is of great theoretical significance and practical application value for breaking through the limitations of traditional thermal control technology, improving the thermal control technology level of my country's spacecraft, and ensuring the smooth implementation of the new generation of space missions. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the purpose of this invention is to provide a mid-to-far-infrared aerospace thermal control multilayer thin film based on W-VO2, and its preparation and application methods.

[0009] The mid- and far-infrared aerospace thermal control multilayer film based on W-VO2 provided by the present invention comprises, from bottom to top, a reflective substrate, a dielectric layer, a W-VO2 functional layer, and a protective layer; The dielectric layer is deposited on the surface of the reflective substrate to form an interference cavity; The W-VO2 functional layer is deposited on a dielectric layer and then annealed to achieve phase change crystallization and dynamic control of infrared emissivity. The protective layer covers the surface of the W-VO2 functional layer and is used to protect the functional layer from environmental oxidation and mechanical damage.

[0010] Preferably, the material of the dielectric layer is selected from one of BaF2, HfO2, CaF2, SiO2, Al2O3, ZnS, TiO2 or MgF2, and the thickness ranges from 500 to 2000 nm.

[0011] Preferably, the thickness of the W-VO2 functional layer is 20-200 nm, and the W element content is 1-3 at%. The phase transition temperature of VO2 is controlled by adjusting the W element doping ratio, so that the phase transition temperature is adjustable in the range of 15~68℃.

[0012] Preferably, the material of the protective layer is selected from one of BaF2, HfO2, CaF2, SiO2, Al2O3, ZnS, TiO2 or MgF2, and the thickness is 100-300nm.

[0013] The method for preparing the mid-to-far-infrared aerospace thermal control multilayer thin film based on W-VO2 provided by the present invention includes the following steps: S1: Provide a mechanically polished substrate, perform ultrasonic cleaning on the substrate, and then dry it for later use; S2: Deposit a dielectric layer on the substrate to form an inorganic dielectric film; S3: Deposit a W-VO2 thin film on the dielectric layer to obtain a W-VO2 functional layer; S4: Deposit a protective layer on the surface of the W-VO2 functional layer; S5: Anneal the sample after deposition to crystallize the W-VO2 film and obtain reversible thermally induced phase transition characteristics.

[0014] Preferably, in step S2, an electron beam evaporation method is used to deposit a dielectric layer on an aluminum substrate; The filament current during electron beam evaporation is 0.5-1.5A, and the deposition rate is 1-2nm / s; In step S3, a W-VO2 thin film is deposited on the dielectric layer using DC magnetron sputtering. The sputtering process parameters are: working pressure 0.5-1 Pa, oxygen volume fraction 10-20%, and power 80-150 W.

[0015] Preferably, in step S5, the annealing temperature is 400-550℃, and the annealing atmosphere is an Ar / O2 mixture with an oxygen volume fraction of 5-10%.

[0016] The present invention provides an application method for the mid-to-far infrared aerospace thermal control multilayer film based on W-VO2. The multilayer film is applied to the thermal control of key parts of the spacecraft by means of aerospace-grade adhesive bonding or mechanical fixation, and the protective layer of the film faces outward and the substrate faces the object to be thermally controlled. The key components include: the back and sides of the lithium-ion battery pack and solar panels; the back or inner surface of the support structure for optical cameras, infrared detectors, and optical payloads; the outer surface of the spacecraft cabin; and the outer wall of the space station's experimental module.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention precisely controls the phase transition temperature within the range of 15~68℃ by adjusting the doping ratio of W element (1-3 at%) and the film thickness. This perfectly matches the periodic temperature changes of spacecraft in the sunlit area (above 100℃) and the shadow area (below -100℃), solving the core problem that the pure VO2 phase transition temperature is too high (68℃) and cannot adapt to the aerospace thermal environment, thus achieving dynamic thermal response control.

[0018] In this invention, the emissivity modulation rate of the thin film in the key far-infrared band of 2~25μm reaches 0.5-0.7, and the visible reflectivity is maintained at 0.55-0.65. At low temperature (below the phase transition temperature), it exhibits high emissivity for efficient heat dissipation, and at high temperature (above the phase transition temperature), it exhibits low emissivity to reduce heat loss, which greatly improves the thermal control accuracy of spacecraft and solves the problems of large temperature fluctuation and high energy consumption of traditional fixed emissivity coatings.

[0019] This invention adds a 100-300nm infrared transparent protective layer (selected from materials such as BaF2 and HfO2) to the surface of the W-VO2 functional layer, which effectively isolates oxygen, water vapor erosion and mechanical damage. After the sample is placed in the air for two weeks, there is no obvious oxidation, and the infrared modulation performance decays by only 3%-5%, which is significantly better than similar materials without a protective layer, and meets the stability requirements of long-term on-orbit service of spacecraft. Attached Figure Description

[0020] 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 merely embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort. Other features, objects, and advantages of the present invention will become more apparent by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the structure of a mid-to-far-infrared aerospace thermal control multilayer thin film based on W-VO2 in an embodiment of the present invention.

[0021] In the picture: 1 is the protective layer; 2 is the W-VO2 functional layer; 3 is the dielectric layer; 4 is the reflective substrate. Detailed Implementation

[0022] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0023] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0024] The technical solution of the present invention will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0025] The technical solutions of the present invention and how they solve the above-mentioned technical problems will be described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present invention will now be described with reference to the accompanying drawings.

[0026] The design concept of the W-VO2-based mid-to-far-infrared aerospace thermal control multilayer thin film in this invention is as follows: Utilizing the metal-insulator phase transition characteristics of the W-VO2 thin film, reversible changes in mid-to-far-infrared reflectivity and emissivity are achieved near the phase transition temperature, enabling dynamic control of radiative heat. Simultaneously, an inorganic dielectric layer is introduced below the W-VO2 functional layer to optimize the infrared modulation rate using interference effects. An infrared transparent protective layer is then added above this layer to suppress environmental oxidation, humidity corrosion, and mechanical damage. This approach maintains excellent infrared modulation performance while improving the device's environmental stability and long-term reliability.

[0027] This embodiment prepares a mid-to-far-infrared aerospace thermal control multilayer thin film based on W-VO2. The specific preparation method is as follows: First, a commercially available aluminum plate was selected as the substrate. The aluminum plate was ultrasonically cleaned with acetone, ethanol, and deionized water for 10 minutes each, and then dried at 80°C for later use.

[0028] Secondly, an inorganic dielectric layer of BaF2 was deposited on an aluminum substrate using electron beam evaporation. The evaporation source was high-purity BaF2 particles, and the vacuum level was maintained at 1×10⁻⁶. -3 With a filament current set below Pa and 0.7 A, a BaF2 thin film with a thickness of approximately 1300 nm was deposited. This dielectric layer was used to modulate the interference effect to optimize infrared modulation performance.

[0029] Then, a W-VO2 thin film was deposited on the dielectric layer using DC magnetron sputtering. The sputtering target was a WV alloy target with a W content of 2 at%, and the working atmosphere was an Ar / O2 mixture with 15% oxygen at a pressure of 0.5 Pa and a sputtering power of 80 W. The deposition time was controlled at 10 minutes, resulting in a W-VO2 thin film with a thickness of approximately 50 nm. After deposition, the sample was placed in a tube furnace and annealed at 550 °C for 30 minutes with an oxygen volume fraction of 5% to crystallize the film and form single-phase W-VO2, achieving stable metal-insulator phase transition characteristics.

[0030] Finally, a protective layer of BaF2 was deposited on the W-VO2 functional layer. The layer was deposited under vacuum conditions using electron beam evaporation with a filament current of 0.7 A and a thickness of 200 nm. This protective layer effectively isolates the W-VO2 functional layer from ambient oxygen and moisture, preventing oxidation and mechanical wear, while having minimal impact on the mid- and far-infrared modulation performance.

[0031] In this embodiment, a mid-to-far-infrared aerospace thermal control multilayer thin film based on W-VO2 was fabricated with a phase transition temperature of 20℃, a high mid-to-far-infrared emissivity of 0.68 in the 2~25μm range, and a visible reflectance of 0.58. The sample showed no significant oxidation after being placed in air for two weeks, and the infrared modulation performance decreased by only 3%. Example 2 This embodiment prepares a mid-to-far-infrared aerospace thermal control multilayer thin film based on W-VO2. The specific preparation method is as follows: First, a commercially available aluminum plate was selected as the substrate. The aluminum plate was ultrasonically cleaned with acetone, ethanol, and deionized water for 10 minutes each, and then dried at 80°C for later use.

[0032] Secondly, an inorganic dielectric layer of BaF2 was deposited on an aluminum substrate using electron beam evaporation. The evaporation source was high-purity BaF2 particles, and the vacuum level was maintained at 1×10⁻⁶. -3 With a filament current set below Pa and 0.7 A, a BaF2 thin film with a thickness of approximately 1300 nm was deposited. This dielectric layer was used to modulate the interference effect to optimize infrared modulation performance.

[0033] Then, a W-VO2 thin film was deposited on the dielectric layer using DC magnetron sputtering. The sputtering target was a WV alloy target with a W content of 2 at%, and the working atmosphere was an Ar / O2 mixture with 10% oxygen at a pressure of 0.5 Pa and a sputtering power of 80 W. The deposition time was controlled at 10 minutes, resulting in a W-VO2 thin film with a thickness of approximately 50 nm. After deposition, the sample was placed in a tube furnace and annealed at 550 °C for 30 minutes with an oxygen volume fraction of 7% to crystallize the film and form single-phase W-VO2, achieving stable metal-insulator phase transition characteristics.

[0034] Finally, a protective layer of BaF2 was deposited on the W-VO2 functional layer. The layer was deposited under vacuum conditions using electron beam evaporation with a filament current of 0.7 A and a thickness of 200 nm. This protective layer effectively isolates the W-VO2 functional layer from ambient oxygen and moisture, preventing oxidation and mechanical wear, while having minimal impact on the mid- and far-infrared modulation performance.

[0035] In this embodiment, a mid-to-far-infrared aerospace thermal control multilayer thin film based on W-VO2 was prepared with a phase transition temperature of 20℃, a high mid-to-far-infrared emissivity of 0.7 in the 2~25μm range, and a visible reflectance of 0.65. After being placed in air for two weeks, the sample showed no significant oxidation, and the infrared modulation performance decreased by only 3%. Example 3 This embodiment prepares a mid-to-far-infrared aerospace thermal control multilayer thin film based on W-VO2. The specific preparation method is as follows: First, a commercially available aluminum plate was selected as the substrate. The aluminum plate was ultrasonically cleaned with acetone, ethanol, and deionized water for 10 minutes each, and then dried at 80°C for later use.

[0036] Secondly, an inorganic dielectric layer of HfO2 was deposited on an aluminum substrate using electron beam evaporation. The evaporation source was high-purity HfO2 particles, and the vacuum level was maintained at 1×10⁻⁶. -3 With a filament current set below Pa and 0.7 A, an HfO2 thin film with a thickness of approximately 1100 nm was deposited. This dielectric layer was used to modulate the interference effect to optimize infrared modulation performance.

[0037] Then, a W-VO2 thin film was deposited on the dielectric layer using DC magnetron sputtering. The sputtering target was a WV alloy target with a W content of 2 at%, and the working atmosphere was an Ar / O2 mixture with 10% oxygen at a pressure of 0.5 Pa and a sputtering power of 80 W. The deposition time was controlled at 10 minutes, resulting in a W-VO2 thin film with a thickness of approximately 50 nm. After deposition, the sample was placed in a tube furnace and annealed at 550 °C for 30 minutes with an oxygen volume fraction of 7% to crystallize the film and form single-phase W-VO2, achieving stable metal-insulator phase transition characteristics.

[0038] Finally, a protective layer of BaF2 was deposited on the W-VO2 functional layer. The layer was deposited under vacuum conditions using electron beam evaporation with a filament current of 0.7 A and a thickness of 200 nm. This protective layer effectively isolates the W-VO2 functional layer from ambient oxygen and moisture, preventing oxidation and mechanical wear, while having minimal impact on the mid- and far-infrared modulation performance.

[0039] In this embodiment, the mid-to-far-infrared aerospace thermal control multilayer thin film based on W-VO2 was prepared with a phase transition temperature of 20℃, a mid-to-far-infrared emissivity of up to 0.65 in the 2~25μm range, and a visible reflectance of 0.63. The sample showed no significant oxidation after being placed in air for two weeks, and the infrared modulation performance decreased by only 3%.

[0040] Example 4 This embodiment prepares a mid-to-far-infrared aerospace thermal control multilayer thin film based on W-VO2. The specific preparation method is as follows: First, a commercially available aluminum plate was selected as the substrate. The aluminum plate was ultrasonically cleaned with acetone, ethanol, and deionized water for 10 minutes each, and then dried at 80°C for later use.

[0041] Secondly, an inorganic dielectric layer of CaF2 was deposited on an aluminum substrate using electron beam evaporation. The evaporation source was high-purity CaF2 particles, and the vacuum level was maintained at 1×10⁻⁶. -3 With a filament current set below Pa and 0.7 A, a CaF2 thin film with a thickness of approximately 1100 nm was deposited. This dielectric layer was used to modulate the interference effect to optimize infrared modulation performance.

[0042] Then, a W-VO2 thin film was deposited on the dielectric layer using DC magnetron sputtering. The sputtering target was a WV alloy target with a W content of 2 at%, and the working atmosphere was an Ar / O2 mixture with 10% oxygen at a pressure of 1 Pa and a sputtering power of 150 W. The deposition time was controlled at 15 minutes, resulting in a W-VO2 thin film with a thickness of approximately 70 nm. After deposition, the sample was placed in a tube furnace and annealed at 550 °C for 30 minutes with an oxygen volume fraction of 7% to crystallize the film and form single-phase W-VO2, achieving stable metal-insulator phase transition characteristics.

[0043] Finally, a protective layer of BaF2 was deposited on the W-VO2 functional layer. The layer was deposited under vacuum conditions using electron beam evaporation with a filament current of 0.7 A and a thickness of 200 nm. This protective layer effectively isolates the W-VO2 functional layer from ambient oxygen and moisture, preventing oxidation and mechanical wear, while having minimal impact on the mid- and far-infrared modulation performance.

[0044] In this embodiment, the mid-to-far-infrared aerospace thermal control multilayer thin film based on W-VO2 was prepared with a phase transition temperature of 20℃, a mid-to-far-infrared emissivity of up to 0.67 in the 2~25μm range, and a visible reflectance of 0.59. The sample showed no significant oxidation after being placed in air for two weeks, and the infrared modulation performance decreased by only 3%.

[0045] Example 5 This embodiment prepares a mid-to-far-infrared aerospace thermal control multilayer thin film based on W-VO2. The specific preparation method is as follows: First, a commercially available aluminum plate was selected as the substrate. The aluminum plate was ultrasonically cleaned with acetone, ethanol, and deionized water for 10 minutes each, and then dried at 80°C for later use.

[0046] Secondly, an inorganic dielectric layer of HfO2 was deposited on an aluminum substrate using electron beam evaporation. The evaporation source was high-purity HfO2 particles, and the vacuum level was maintained at 1×10⁻⁶.-3 With a filament current set below Pa and 0.7 A, an HfO2 thin film with a thickness of approximately 1100 nm was deposited. This dielectric layer was used to modulate the interference effect to optimize infrared modulation performance.

[0047] Then, a W-VO2 thin film was deposited on the dielectric layer using DC magnetron sputtering. The sputtering target was a WV alloy target with a W content of 2 at%, and the working atmosphere was an Ar / O2 mixture with 10% oxygen at a pressure of 1 Pa and a sputtering power of 150 W. The deposition time was controlled at 15 minutes, resulting in a W-VO2 thin film with a thickness of approximately 70 nm. After deposition, the sample was placed in a tube furnace and annealed at 550 °C for 30 minutes with an oxygen volume fraction of 7% to crystallize the film and form single-phase W-VO2, achieving stable metal-insulator phase transition characteristics.

[0048] Finally, a protective HfO2 layer was deposited on the W-VO2 functional layer. The layer was deposited under vacuum conditions using electron beam evaporation at a filament current of 1.5 A, with a thickness of 250 nm. This protective layer effectively isolates the W-VO2 functional layer from ambient oxygen and moisture, preventing oxidation and mechanical wear, while having minimal impact on mid- and far-infrared modulation performance.

[0049] In this embodiment, the W-VO2-based mid- and far-infrared dynamically modulated thin film exhibits a phase transition temperature of 20°C, a high mid- and far-infrared emissivity of 0.66 in the 2–25 μm range, and a visible reflectance of 0.57. After being exposed to air for two weeks, the sample showed no significant oxidation, and the infrared modulation performance decreased by only 5%.

[0050] Comparative Example 1 An infrared-controlled thin film was prepared in this comparative example. The preparation method was basically the same as that in Example 1, except that a protective layer was not deposited on the surface of the W-VO2 functional layer.

[0051] The specific preparation steps are as follows: First, a commercially available aluminum plate was selected as the substrate. The aluminum plate was ultrasonically cleaned with acetone, ethanol, and deionized water for 10 minutes each, and then dried at 80°C for later use.

[0052] Secondly, a BaF2 dielectric layer was deposited on an aluminum substrate using electron beam evaporation. The vacuum level was maintained at 1×10⁻⁶. -3 Below Pa, the filament current is 0.7A, and the deposition thickness is approximately 1300nm.

[0053] Then, a W-VO2 thin film was deposited on the dielectric layer using DC magnetron sputtering. The target was a WV alloy target with a W content of 2 at%, the working atmosphere was an Ar / O2 mixture with 15% oxygen, a pressure of 0.5 Pa, a sputtering power of 80 W, a deposition time of 10 min, and a film thickness of 50 nm. After deposition, the film was annealed at 550 °C for 30 min under conditions of 5% oxygen volume to crystallize the film and form single-phase W-VO2.

[0054] Unlike Example 1, this comparative example did not deposit any protective layer on the W-VO2 layer and directly tested the sample.

[0055] Test results show that the infrared modulation rate of the film is significantly reduced in the 2–25 μm band, the change in infrared emissivity is less than 30%, and the sample shows significant oxidation after being placed in air for two weeks, resulting in significant attenuation of infrared performance and a 13% decrease in infrared modulation rate. The visible reflectance is 0.44. This indicates that the introduction of the protective layer has a significant effect on improving the environmental stability and infrared modulation performance of the W-VO2 functional layer.

[0056] Comparative Example 2 This comparative example prepared a VO2 mid-far-infrared dynamically regulated thin film with a high magnetron sputtering oxygen content. The preparation method was basically the same as that in Example 1, except that the magnetron sputtering oxygen content was changed to 25%, while other process conditions remained the same.

[0057] The specific steps are as follows: First, a commercially available aluminum plate was selected as the substrate. The aluminum plate was ultrasonically cleaned with acetone, ethanol, and deionized water for 10 minutes each, and then dried at 80°C for later use.

[0058] Secondly, an inorganic dielectric layer of BaF2 was deposited on an aluminum substrate using electron beam evaporation. The evaporation source was high-purity BaF2 particles, and the vacuum level was maintained at 1×10⁻⁶. -3 With a filament current of 0.7A and a Pa below, a BaF2 film with a thickness of approximately 1300 nm was deposited.

[0059] Then, a VO2 thin film was deposited on the dielectric layer using DC magnetron sputtering. A pure V target was used as the sputtering target, and the working atmosphere was an Ar / O2 mixture with 25% oxygen, a pressure of 0.5 Pa, and a sputtering power of 80 W. The deposition time was controlled at 10 minutes, resulting in a VO2 film with a thickness of approximately 50 nm. After deposition, the sample was placed in a tube furnace and annealed at 550 °C for 30 minutes under conditions of 5% oxygen by volume to crystallize the film and form single-phase VO2.

[0060] Finally, a protective BaF2 layer was deposited on the VO2 functional layer. The layer was deposited under vacuum conditions using electron beam evaporation with a filament current of 0.7 A and a thickness of 200 nm.

[0061] Test results show that the infrared modulation rate of the comparative sample in the 2-25 μm range is 0.36. After being exposed to air for two weeks, the sample showed partial oxidation, with an infrared performance degradation of approximately 12%. The visible reflectance is 0.55.

[0062] Compared with Example 1, the infrared performance and environmental stability of this comparative example decreased significantly, indicating that an excessively high proportion of oxygen in magnetron sputtering is detrimental to infrared performance and environmental stability.

[0063] Comparative Example 3 This comparative example prepared a W-VO2 mid-far-infrared dynamic control film with a lower annealing temperature. The preparation method was basically the same as that in Example 1, except that the annealing temperature was reduced from 550℃ to 350℃, while the other process conditions remained the same.

[0064] The specific steps are as follows: First, a commercially available aluminum plate was selected as the substrate. The aluminum plate was ultrasonically cleaned with acetone, ethanol, and deionized water for 10 minutes each, and then dried at 80°C for later use.

[0065] Secondly, an inorganic dielectric layer of BaF2 was deposited on an aluminum substrate using electron beam evaporation. The evaporation source was high-purity BaF2 particles, and the vacuum level was maintained at 1×10⁻⁶. -3 With a filament current of 0.7A and a Pa below, a BaF2 film with a thickness of approximately 1300 nm was deposited.

[0066] Then, a W-VO2 thin film was deposited on the dielectric layer using DC magnetron sputtering. The sputtering target was a WV alloy target with a W content of 2 at%, and the working atmosphere was an Ar / O2 mixture with 15% oxygen at a pressure of 0.5 Pa and a sputtering power of 80 W. The deposition time was controlled at 10 minutes, resulting in a W-VO2 thin film with a thickness of approximately 50 nm. After deposition, the sample was placed in a tube furnace and annealed at 450 °C for 30 minutes under conditions of 5% oxygen by volume to crystallize the film.

[0067] Finally, a protective layer of BaF2 was deposited on the W-VO2 functional layer. The deposition was performed under vacuum conditions using electron beam evaporation at a filament current of 0.7 A, with a thickness of 200 nm.

[0068] Test results show that the comparative sample has a low degree of crystallization, still contains some amorphous structures, and the phase transition temperature is increased to approximately 45°C. The 2~25μm infrared modulation rate is 0.37, and the visible reflectance is 0.6. Compared with Example 1, the infrared modulation performance of this comparative sample is significantly reduced, indicating that an excessively low annealing temperature is not conducive to the complete formation of the W-VO2 crystal phase and the metal-insulator phase transition characteristics.

[0069] The various embodiments described in this specification are presented in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0070] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A mid-to-far-infrared aerospace thermal control multilayer thin film based on W-VO2, characterized in that, The thin film consists of a reflective substrate, a dielectric layer, a W-VO2 functional layer, and a protective layer from bottom to top. The dielectric layer is deposited on the surface of the reflective substrate to form an interference cavity; The W-VO2 functional layer is deposited on a dielectric layer and then annealed to achieve phase change crystallization and dynamic control of infrared emissivity. The protective layer covers the surface of the W-VO2 functional layer and is used to protect the functional layer from environmental oxidation and mechanical damage.

2. The mid-to-far-infrared aerospace thermal control multilayer thin film based on W-VO2 according to claim 1, characterized in that, The material of the dielectric layer is selected from one of BaF2, HfO2, CaF2, SiO2, Al2O3, ZnS, TiO2 or MgF2, and the thickness ranges from 500 to 2000 nm.

3. The mid-to-far-infrared aerospace thermal control multilayer thin film based on W-VO2 according to claim 1, characterized in that, The thickness of the W-VO2 functional layer is 20-200 nm, and the W element content is 1-3 at%. The phase transition temperature of VO2 is controlled by adjusting the W element doping ratio, so that the phase transition temperature is adjustable in the range of 15~68℃.

4. The mid-to-far-infrared aerospace thermal control multilayer thin film based on W-VO2 according to claim 1, characterized in that, The material of the protective layer is selected from one of BaF2, HfO2, CaF2, SiO2, Al2O3, ZnS, TiO2 or MgF2, and the thickness is 100-300nm.

5. A method for preparing a mid-to-far-infrared aerospace thermal control multilayer thin film based on W-VO2 as described in any one of claims 1-4, characterized in that, Includes the following steps: S1: Provide a mechanically polished substrate, perform ultrasonic cleaning on the substrate, and then dry it for later use; S2: Deposit a dielectric layer on the substrate to form an inorganic dielectric film; S3: Deposit a W-VO2 thin film on the dielectric layer to obtain a W-VO2 functional layer; S4: Deposit a protective layer on the surface of the W-VO2 functional layer; S5: Anneal the sample after deposition to crystallize the W-VO2 film and obtain reversible thermally induced phase transition characteristics.

6. The preparation method according to claim 5, characterized in that, In step S2, an electron beam evaporation method is used to deposit a dielectric layer on an aluminum substrate; The filament current during electron beam evaporation is 0.5-1.5A, and the deposition rate is 1-2nm / s; In step S3, a W-VO2 thin film is deposited on the dielectric layer using DC magnetron sputtering. The sputtering process parameters are: working pressure 0.5-1 Pa, oxygen volume fraction 10-20%, and power 80-150 W.

7. The preparation method according to claim 5, characterized in that, In step S5, the annealing temperature is 400-550℃, and the annealing atmosphere is an Ar / O2 mixture with an oxygen volume fraction of 5-10%.

8. An application method of the mid-to-far-infrared aerospace thermal control multilayer thin film based on W-VO2 as described in any one of claims 1-4, characterized in that, The multilayer film is applied to the thermal control of key parts of the spacecraft by aerospace-grade adhesive bonding or mechanical fixation, with the protective layer of the film facing outward and the substrate facing the object being thermally controlled. The key components include: the back and sides of the lithium-ion battery pack and solar panels; the back or inner surface of the support structure for optical cameras, infrared detectors, and optical payloads; the outer surface of the spacecraft cabin; and the outer wall of the space station's experimental module.

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