All-weather intelligent thermal control coating based on thermally induced phase change material and application

Abstract

The invention discloses an all-weather intelligent thermal control coating based on a thermally induced phase change material and application, and belongs to the technical field of intelligent thermal control coatings. The all-weather intelligent thermal control coating based on the thermally induced phase change material comprises a substrate, a first phase change layer, a dielectric layer, a second phase change layer and an antireflection structure layer which are sequentially laminated from bottom to top, wherein the thickness of the first phase change layer is larger than that of the second phase change layer, and the first phase change layer and the second phase change layer are made of thermally induced phase change materials. The solar-thermal radiation cooperative regulation and control of the coating can be realized only by using the thermally induced phase change material, the regulation and control amplitude is large, and solar heating at low temperature and radiation refrigeration at high temperature can be performed; the problems that an existing intelligent coating is difficult to carry out solar-thermal radiation cooperative regulation and control and the regulation and control amplitude is limited are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of intelligent thermal control coatings, and in particular to an all-weather intelligent thermal control coating based on thermoinduced phase change materials and its application. Background Art

[0002] The statements in this section merely mention background art related to the present invention and do not necessarily constitute prior art.

[0003] At present, a large part of energy is consumed in the form of cooling or heat. Among them, building energy consumption is an important part of total energy consumption and a key area for energy transformation and reducing carbon emissions. Heating, ventilation and air conditioning (HVAC) systems are the main components of building energy consumption, and their energy supply currently relies mainly on fossil energy, causing environmental problems such as ozone depletion, greenhouse effect and air pollution.

[0004] From a thermodynamic point of view, the sun and deep space are the ultimate heat sources (about 5762K) and cold sources (about 3K) for the earth's energy cycle, and they are clean and pollution-free. Solar heating and radiation cooling technology can use the sun and deep space to achieve passive heating and cooling.

[0005] Based on the intelligent control technology of radiation characteristics, the all-weather smart coating can switch between two modes: solar heating at low temperatures and radiation cooling at high temperatures, which is of great significance for achieving building energy conservation and reducing carbon emissions.

[0006] Intelligent control technology of radiation characteristics mainly includes thermochromism, electrochromism, mechanochromism and the combination of multiple methods. Both electrochromism and mechanochromism are active control methods, which require external stimulation, consume additional resources, have complex structures and low reliability, and also have defects such as performance degradation and limited control range. Thermochromism is based on thermochromic phase change materials and has the advantages of no power consumption, no moving parts, simple structure, light weight, and self-adjustable emissivity.

[0007] However, the current thermochromic smart coatings mainly regulate radiation characteristics by single-parameter regulation of either infrared emissivity or solar absorptivity, making it difficult to coordinate solar-thermal radiation regulation and unable to achieve reversible switching between low-temperature solar heating and high-temperature radiation cooling modes. The regulation range is extremely limited. Summary of the invention

[0008] In order to address the deficiencies of the prior art, the present invention provides an all-weather intelligent thermal control coating based on thermotropic phase change materials, which fully utilizes the reversible phase change characteristics of thermotropic phase change materials to realize coordinated regulation of solar thermal radiation of the coating, achieves reversible conversion of solar heating and radiation cooling modes, and meets the needs of all-weather application of the coating.

[0009] An all-weather intelligent thermal control coating based on a thermotropic phase change material, comprising a substrate, a first phase change layer, a dielectric layer, a second phase change layer and an anti-reflection structure layer stacked in sequence from bottom to top;

[0010] The thickness of the first phase change layer is greater than that of the second phase change layer, and the first phase change layer and the second phase change layer are made of thermotropic phase change material.

[0011] In some embodiments, the thickness of each layer in the all-weather intelligent thermal control coating is determined by iterative optimization with the goal of maximizing the sum of the solar absorptivity regulation amplitude and the infrared emissivity regulation amplitude, under the constraint that the changing trends of the solar absorptivity and the infrared emissivity are opposite.

[0012] In some embodiments, the material of the substrate includes one or more of aluminum, silver, gold, doped silicon, and semiconductor oxide.

[0013] In some embodiments, the first phase change layer is a single-layer structure.

[0014] In some embodiments, the material of the first phase change layer includes one or more of vanadium dioxide, vanadium trioxide, titanium dioxide, strontium-doped lanthanum manganate, calcium-doped lanthanum manganate, and chalcogenide.

[0015] Furthermore, the material of the first phase change layer includes vanadium dioxide, vanadium trioxide, titanium dioxide, strontium-doped lanthanum manganate, calcium-doped lanthanum manganate, Ge x Sb y Te z 、In x Sb y Te z , Sb2S3 and Sb2Se3 or more.

[0016] Preferably, the material of the first phase change layer is In x Sb y Te z .

[0017] In some embodiments, the first phase change layer is disposed on the upper surface of the substrate by magnetron sputtering, vacuum evaporation, sol-gel or pulsed laser deposition.

[0018] In some embodiments, the dielectric layer is a single-layer structure;

[0019] In some embodiments, the material of the dielectric layer includes barium fluoride, calcium fluoride, zinc selenide or zinc sulfide.

[0020] In some embodiments, the dielectric layer is disposed on the upper surface of the first phase change layer by magnetron sputtering, vacuum evaporation, sol-gel or pulsed laser deposition.

[0021] In some embodiments, the second phase change layer is a single-layer structure or a grating structure.

[0022] In some embodiments, the material of the second phase change layer includes one or more of vanadium dioxide, vanadium trioxide, titanium dioxide, strontium-doped lanthanum manganate, calcium-doped lanthanum manganate, and chalcogenide.

[0023] Furthermore, the material of the second phase change layer includes vanadium dioxide, vanadium trioxide, titanium dioxide, strontium-doped lanthanum manganate, calcium-doped lanthanum manganate, Ge x Sb y Te z 、In x Sb y Te z , Sb2S3 and Sb2Se3 or more.

[0024] Preferably, the material of the second phase change layer is vanadium dioxide or In x Sb y Te z .

[0025] In some embodiments, the second phase change layer is disposed on the upper surface of the dielectric layer by magnetron sputtering, vacuum evaporation, sol-gel or pulsed laser deposition.

[0026] In some embodiments, if the second phase change layer is a grating structure, the grating structure is obtained by photolithography technology.

[0027] In some embodiments, the anti-reflection structural layer is a single-layer structure or a multi-layer structure;

[0028] Preferably, the anti-reflection structure layer is a multi-layer structure, and the refractive index of each layer of material in the multi-layer structure increases from top to bottom.

[0029] In some embodiments, the anti-reflection structural layer is disposed on the upper surface of the second phase change layer by magnetron sputtering, vacuum evaporation, sol-gel or pulsed laser deposition.

[0030] In some embodiments, the anti-reflection structural layer is made of one or more of barium fluoride, calcium fluoride, zinc selenide, and zinc sulfide.

[0031] In some embodiments, the first phase change layer and the second phase change layer are made of the same or different materials.

[0032] In some embodiments, the first phase change layer is prepared on the upper surface of the substrate by magnetron sputtering, vacuum evaporation, sol-gel or pulsed laser deposition.

[0033] In a second aspect, the present invention provides the application of the all-weather intelligent thermal control coating based on thermotropic phase change materials in the technical fields of buildings, vehicles, outdoor base stations, aircraft and spacecraft.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The technical solution provided by the present invention designs an all-weather intelligent thermal control coating based on thermotropic phase change materials. The solar-thermal radiation coordinated regulation of the coating can be achieved by only using thermotropic phase change materials. The regulation range is large, and it can perform solar heating at low temperatures (high solar absorptivity and low infrared emissivity) and radiation cooling at high temperatures (low solar absorptivity and high infrared emissivity). It has the advantages of no power consumption, no moving parts, simple structure, light weight, and autonomously adjustable emissivity.

[0036] 2. The technical solution provided by the present invention can realize multi-level regulation of radiation characteristics through the combination of multiple phase change materials, further increasing the flexibility of regulation and adaptability in application.

[0037] 3. The technical solution provided by the present invention can be applied to buildings, vehicles, field base stations, various aircraft and spacecraft and other equipment, effectively promoting energy conservation and emission reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0039] Figure 1 A schematic structural diagram of an all-weather intelligent thermal control coating based on a thermotropic phase change material is provided for an embodiment of the present invention;

[0040] Figure 2 A schematic diagram of the complex refractive index of the IST film in the crystalline and amorphous states provided by an embodiment of the present invention;

[0041] Figure 3 A schematic diagram of the normal spectral emissivity / absorptivity of the BaF2 / ZnS / IST / ZnS / IST / Al multilayer structure coating in Example 1 provided in an embodiment of the present invention under solar heating and radiation cooling modes;

[0042] Figure 4 A schematic diagram of the complex refractive index of the VO2 thin film in the insulating state and the metallic state provided by an embodiment of the present invention;

[0043] Figure 5 A schematic diagram of the normal spectral emissivity / absorptivity of the BaF2 / VO2 / BaF2 / IST / Al multilayer structure coating in Example 2 provided in an embodiment of the present invention under solar heating and radiation cooling modes;

[0044] Figure 6 A schematic diagram of the normal spectral emissivity / absorptivity of the BaF2 / VO2 / BaF2 / IST / Al multilayer structure coating in the insulating state VO2 / crystalline state IST and the metallic state VO2 / amorphous state IST in Example 2 provided in the embodiments of the present invention;

[0045] Figure 7 A schematic cross-sectional view of a grating structure 6 in Embodiment 3 provided in an embodiment of the present invention;

[0046] Figure 8 A schematic diagram of the normal spectral emissivity / absorptivity of the BaF2 / VO2 / BaF2 / IST / Al patterned grating structure 6 coating in the solar heating and radiation cooling modes in Example 3 provided for an embodiment of the present invention;

[0047] Fig. 9 A schematic diagram of the net radiation heat flux density of the BaF2 / ZnS / IST / ZnS / IST / Al multilayer structure coating in the amorphous IST state in Example 4 provided in the present invention;

[0048] Fig.10 A schematic diagram of the net radiation heat flux density of the BaF2 / ZnS / IST / ZnS / IST / Al multilayer structure coating in the crystalline IST state in Example 4 provided in the embodiments of the present invention;

[0049] Fig.11 A schematic diagram of the normal spectral emissivity / absorptivity of the BaF2 / ZnS / IST / ZnS / IST / Al multilayer structure coating in comparative example 1 provided in an embodiment of the present invention under solar heating and radiation cooling modes;

[0050] Fig.12 A schematic diagram of the normal spectral emissivity / absorptivity of the BaF2 / ZnS / IST / ZnS / IST / Al multilayer structure coating in comparative example 2 provided in an embodiment of the present invention under solar heating and radiation cooling modes;

[0051] Fig.13 A schematic diagram of the normal spectral emissivity / absorptivity of the BaF2 / ZnS / IST / ZnS / IST / Al multilayer structure coating in comparative example 3 provided in an embodiment of the present invention under solar heating and radiation cooling modes;

[0052] In the figure: 1. anti-reflection structure layer; 2. thin phase change layer; 3. dielectric layer; 4. thick phase change layer; 5. substrate; 6. grating structure. DETAILED DESCRIPTION

[0053] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0054] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0055] Embodiment 1

[0056] Existing smart coatings can only achieve single-parameter control of infrared emissivity or solar absorptivity, and it is difficult to perform coordinated control of solar-thermal radiation, and it is impossible to achieve reversible switching between the two modes of solar heating at low temperatures and radiation cooling at high temperatures; therefore, the present invention provides an all-weather smart thermal control coating based on thermotropic phase change materials, which utilizes thermotropic phase change materials and combines the structural design of the all-weather smart thermal control coating to achieve coordinated control of the smart thermal control coating.

[0057] Next, combine Figure 1-Figure 13 , an all-weather intelligent thermal control coating based on thermotropic phase change material disclosed in this embodiment is described in detail. The all-weather intelligent thermal control coating based on thermotropic phase change material includes a substrate 5, a first phase change layer, a dielectric layer 3, a second phase change layer and an anti-reflection structure layer 1 stacked in sequence from bottom to top, the thickness of the first phase change layer is greater than the thickness of the second phase change layer, that is, the first phase change layer is a thick phase change layer 4, the second phase change layer is a thin phase change layer 2, the materials of the first phase change layer and the second phase change layer are the same type or different types of thermotropic phase change materials, when the materials of the first phase change layer and the second phase change layer are different, multi-level regulation of the all-weather intelligent thermal control coating can be achieved.

[0058] In this embodiment, the thick phase change layer 4 is an absorption layer in the solar heating mode, and therefore, a certain thickness is required to ensure high absorption in the solar heating mode; at the same time, it can be used as a high reflection layer in the radiation cooling mode.

[0059] That is to say, the absorption of the all-weather intelligent thermal control coating in the solar heating mode is increased by using a first phase change layer with a thicker thickness, and the formation of a resonance cavity is promoted by designing a second phase change layer with a lower thickness.

[0060] The all-weather intelligent thermal control coating based on thermotropic phase change material provided in this embodiment uses the sudden change of the optical properties of the thermotropic phase change material before and after the phase change to adjust the radiation properties of the coating. The optical properties include solar absorptivity and infrared emissivity. Therefore, in one embodiment, the optimal thickness of each layer in the all-weather intelligent thermal control coating is determined by iterative optimization with the goal of maximizing the sum of the solar absorptivity control amplitude and the infrared emissivity control amplitude. The specific process is as follows:

[0061] (1) Based on the preset structural parameters, the spectral normal reflectivity R of the all-weather intelligent thermal control coating is obtained using the existing rigorous coupled wave analysis (RCWA) method. λ,θ , based on Kirchhoff's law, the normal spectral emissivity and normal spectral absorptivity of the all-weather intelligent thermal control coating are obtained, which is expressed as:

[0062] ε λ,θ =a λ,θ =1-R λ,θ ;

[0063] In the formula, ε λ，θ represents the normal spectral emissivity of the all-weather intelligent thermal control coating, a λ，θ Represents the normal spectral absorbance of the all-weather intelligent thermal control coating.

[0064] (2) According to the normal spectral emissivity and normal spectral absorptivity of the all-weather intelligent thermal control coating, the normal solar absorptivity and normal infrared emissivity of the all-weather intelligent thermal control coating are obtained, which are expressed as:

[0065]

[0066] In the formula, a θ represents the normal solar absorptivity of the all-weather intelligent thermal control coating, ε θ represents the normal infrared emissivity of the all-weather intelligent thermal control coating, S solar (λ) represents the solar spectrum radiation heat flux, E bλ (λ, T) represents the blackbody spectral radiation power, λ represents the wavelength, and T represents the thermodynamic temperature.

[0067] (3) Similarly, based on the formula in step (2), the normal solar total absorptivity and normal infrared total emissivity in the solar heating mode and the normal total absorptivity and normal total emissivity in the radiation cooling mode can be obtained. The FOM used to evaluate the solar absorptivity and infrared emissivity is determined by the normal solar total absorptivity and normal infrared total emissivity in the solar heating mode and the normal total absorptivity and normal total emissivity in the radiation cooling mode, which is expressed as:

[0068] FOM=(a normal,SH -a normal,RC )+(ε normal,SH -ε normal,RC );

[0069] In the formula, a normal,SH and ε normal,SH represents the normal solar total absorptivity and normal infrared total emissivity in solar heating mode, a normal,RC and ε normal,RCIt represents the normal solar total absorptivity and normal solar total emissivity in the radiation cooling mode.

[0070] (4) Iterative optimization is performed with the goal of maximizing the FOM value. Under the constraint that the changing trends of solar absorptivity and infrared emissivity are opposite, the structural parameters are changed through the optimization algorithm for iterative optimization to find the maximum value of FOM, determine the optimal normal spectral emissivity and optimal normal spectral absorptivity of the all-weather intelligent thermal control coating, and output the corresponding structural parameters, that is, the thickness of each layer of the all-weather thermal control coating.

[0071] Here, the optimization algorithm may be a genetic algorithm, a particle swarm algorithm, a machine learning algorithm or other optimization algorithms.

[0072] In some embodiments, the material of the substrate 5 is a metal material or a material with metallic properties, including one or more of aluminum, silver, gold, doped silicon, and semiconductor oxide.

[0073] In some embodiments, the first phase change layer is a single-layer structure.

[0074] In some embodiments, the material of the first phase change layer includes vanadium dioxide (VO2), vanadium trioxide, titanium dioxide, strontium-doped lanthanum manganate, calcium-doped lanthanum manganate, and chalcogenide (Ge2+, Ge ... x Sb y Te z (GST), Indium Antimony Telluride Series In x Sb y Te z (IST, Sb2S3 and Sb2Se3, etc.), preferably IST.

[0075] In some embodiments, the dielectric layer 3 is a single-layer structure.

[0076] In some embodiments, the material of the dielectric layer 3 is selected from materials with high transparency or semi-transparency in the visible light-infrared spectrum range, including barium fluoride, calcium fluoride, zinc selenide or zinc sulfide.

[0077] In some embodiments, the second phase change layer can be a single-layer structure or a grating structure 6, preferably a grating structure 6. The grating structure 6 can be a two-dimensional or three-dimensional grating, including rectangular, cylindrical, trapezoidal and other grating patterns. The material in the gap of the grating pattern is consistent with the material of the dielectric layer 3.

[0078] In some embodiments, the material of the second phase change layer includes vanadium dioxide, vanadium trioxide, titanium dioxide, strontium-doped lanthanum manganate, calcium-doped lanthanum manganate, and chalcogenide (Ge2+, Ge ... x Sb y Te z (GST), Indium Antimony Telluride Series Inx Sb y Te z (IST, Sb2S3 and Sb2Se3, etc.), preferably vanadium dioxide or IST.

[0079] In some embodiments, the second phase change layer is disposed on the upper surface of the dielectric layer by magnetron sputtering, vacuum evaporation, sol-gel, pulsed laser or deposition.

[0080] In some embodiments, if the second phase change layer is a grating structure, the grating structure is obtained by photolithography technology.

[0081] In some embodiments, the anti-reflection structure layer 1 is a single-layer structure or a multi-layer structure. When the anti-reflection structure layer 1 is a multi-layer structure, the refractive index of each layer of material gradually increases from top to bottom.

[0082] Specifically, the refractive index of the multilayer structure can be improved by setting different layers in the multilayer structure to be made of different materials.

[0083] In some embodiments, the material of the anti-reflection structure layer 1 includes one or more of barium fluoride, calcium fluoride, zinc selenide, and zinc sulfide.

[0084] In some embodiments, the first phase change layer is plated on the upper surface of the substrate 5 by magnetron sputtering, vacuum evaporation, sol-gel or pulsed laser deposition, the dielectric layer 3 is plated on the upper surface of the first phase change layer by magnetron sputtering, vacuum evaporation, sol-gel or pulsed laser deposition, the second phase change layer is plated on the upper surface of the dielectric layer 3 by magnetron sputtering, vacuum evaporation, sol-gel pulsed laser deposition, and the anti-reflection structure layer 1 is plated on the upper surface of the second phase change layer by magnetron sputtering, vacuum evaporation, sol-gel or pulsed laser deposition.

[0085] In a second aspect, this embodiment provides the application of the all-weather intelligent thermal control coating based on thermotropic phase change materials in the technical fields of buildings, vehicles, outdoor base stations, aircraft and spacecraft.

[0086] The present invention will be further described in detail below in conjunction with specific embodiments. It should be noted that the specific embodiments are intended to explain the present invention rather than to limit it.

[0087] Example 1

[0088] An all-weather intelligent thermal control coating based on thermotropic phase change material includes, from top to bottom, an anti-reflection structure layer 1, a second phase change layer, a dielectric layer 3, a first phase change layer, and a substrate 5. The second phase change layer is a thin phase change layer 2, and the first phase change layer is a thick phase change layer 4.

[0089] Specifically, the anti-reflection structure layer 1 is a double-layer structure, the upper layer is a BaF2 layer with a thickness of 0.11μm, and the lower layer is a ZnS layer with a thickness of 1.01μm; the thin phase change layer 2 is an IST layer with a thickness of 0.01μm; the dielectric layer 3 is a ZnS layer with a thickness of 1.18μm; the thick phase change layer 4 is an In3SbTe2 (IST) layer with a thickness of 6.98μm; the substrate layer 5 is an Al layer with a thickness of 0.20μm.

[0090] IST is a non-volatile phase change material that can achieve reversible phase change between crystalline and amorphous states. Its phase change point is 300°C. The dielectric function before and after the phase change is as follows: Figure 2 shown.

[0091] The crystallization of IST is that amorphous IST will transform into crystalline IST after the temperature exceeds 300℃, but when the temperature drops to 300℃, the crystalline IST will not transform into amorphous. The amorphization of IST requires heating the crystalline IST to a temperature above the melting point, which is about 630℃, and then quickly quenching it to obtain amorphous IST. Before the temperature is heated to 300℃, the amorphous IST will not switch to the crystalline state.

[0092] After the phase change layer is heated to over 300°C, it is converted into a crystalline state. The crystalline IST has a large complex refractive index and strong metallic properties, which enables the all-weather intelligent thermal control coating to form an IST / ZnS / IST Fabry-Perot resonance and has high emission characteristics in the infrared band. However, in the solar band, the absorption coefficient of the crystalline IST is very small and the Fabry-Perot resonance intensity is weak, resulting in a small solar absorption rate, which in turn causes the all-weather intelligent thermal control coating to switch to a radiation cooling mode to achieve radiation cooling at high temperatures.

[0093] In order to switch the all-weather intelligent thermal control coating to the solar heating mode, the phase change layer is heated to 630°C and then rapidly quenched to switch the phase change layer from the crystalline state to the amorphous state. After that, when the temperature is below 300°C, the phase change layer material IST is amorphous. Amorphous IST is transparent in the infrared and is easy to obtain low infrared emissivity, while it has strong absorption characteristics in the visible-near infrared band. Combined with the anti-reflection effect of the anti-reflection layer, the solar absorption rate of the all-weather intelligent thermal control coating is high, and the all-weather intelligent thermal control coating is switched to the solar heating mode to achieve solar heating at low temperatures.

[0094] In addition, multi-level control can be achieved by constructing IST gratings of different sizes through local laser heating.

[0095] Specifically, the amorphous IST can be crystallized by heating it to 300°C by irradiating it from above with a high-energy laser. Then, laser heating can be used to make crystalline gratings with different strip widths in the amorphous IST phase change layer. Crystalline IST and amorphous IST can be present on the same all-weather intelligent thermal control coating. Based on the same principle mentioned above, multi-level regulation of different radiation characteristics can be achieved.

[0096] The spectral normal emissivity / absorptivity of the all-weather intelligent thermal control coating in this embodiment is Figure 3 The solar absorptivity and infrared emissivity parameters (a normal ,ε normal ) are (0.83, 0.05) and (0.36, 0.84) respectively, which well achieves the technical goal of this embodiment.

[0097] Example 2

[0098] An all-weather intelligent thermal control coating based on thermotropic phase change material comprises, from top to bottom, an anti-reflection structure layer 1, a second phase change layer, a dielectric layer 3, a first phase change layer and a substrate 5, wherein the second phase change layer is a thin phase change layer 2, and the first phase change layer is a thick phase change layer 4.

[0099] Specifically, the anti-reflection structure layer 1 is a single-layer structure, the material is a BaF2 layer with a thickness of 1.30μm, the thin phase change layer 2 is a vanadium dioxide (VO2) layer with a thickness of 0.014μm; the dielectric layer 3 is a BaF2 layer with a thickness of 1.51μm; the thick phase change layer 4 is an IST layer with a thickness of 6.98μm; the substrate layer 5 is an Al layer with a thickness greater than 0.2μm.

[0100] VO2 is a volatile phase change material that can reversibly switch between an insulating state and a metallic state, with a phase change temperature of 68°C. When the temperature is higher than 68°C, VO2 is in a metallic state, and when the temperature is lower than 68°C, VO2 is in an insulating state.

[0101] VO2 can realize reversible phase transition between insulating state and metallic state. The complex refractive index before and after the phase transition is as follows: Figure 4 IST can realize a reversible phase transition process between crystalline and amorphous states. The complex refractive index before and after the phase transition is shown in Figure 2 shown.

[0102] It can be seen that after the thick phase change layer 4 is heated to 300°C and switched to the crystalline state, when the ambient temperature is higher than 68°C, the thin phase change layer 2 switches to the metallic state. In the temperature range of 68°C to 630°C, the metallic VO2 and the crystalline IST have a large complex refractive index, which can form a VO2 / ZnS / IST Fabry-Perot resonance and form a high infrared emission characteristic. At the same time, the visible light absorption coefficient of the crystalline IST is very small, which makes the coating have a low solar absorption rate, so that the all-weather smart coating switches to the radiation cooling mode.

[0103] The thick phase change layer 4 is heated to 630°C and then rapidly quenched to switch the thick phase change layer 4 from a crystalline state to an amorphous state; when the temperature is below 68°C, the thin phase change layer 2 is in an insulating state. That is to say, after the thick phase change layer 4 is switched to an amorphous state, when the temperature is below 68°C, the insulating state VO2 and the amorphous state IST are transparent in the infrared, making it easy to obtain low infrared emissivity, and have strong absorption characteristics in the visible light-near infrared band. Combined with the anti-reflection effect of the anti-reflection layer, the coating has a high solar absorption rate, allowing the all-weather smart coating to switch to solar heating mode.

[0104] The spectral normal emissivity / absorptivity of the all-weather intelligent thermal control coating in this embodiment is Figure 5 The solar absorptivity and infrared emissivity parameters (a) in solar heating mode and radiation cooling mode are given in normal ,ε normal ) are (0.78, 0.09) and (0.46, 0.84) respectively, which better achieves the technical objectives of the present invention.

[0105] In addition, from Figure 6 It can be seen that the combination of insulating VO2 and crystalline IST can obtain an intermediate mode between the solar heating mode and the radiation cooling mode. The solar absorptivity and infrared emissivity parameters (a normal ,ε normal ) is (0.49, 0.16); the combination of metallic VO2 and amorphous IST can achieve strong absorption / emission characteristics in the full spectrum, and the solar absorptivity and infrared emissivity parameters (a normal ,ε normal ) is (0.78, 0.71), which enables switching between solar heating mode and radiation cooling mode. According to the combination of different phase changes of VO2 and IST, the multi-level regulation of the radiation characteristics of the all-weather intelligent thermal control coating can be achieved by switching between crystalline, amorphous, insulating and metallic states, further increasing the flexibility of regulation and adaptability in applications.

[0106] Example 3

[0107] An all-weather intelligent thermal control coating based on thermotropic phase change material comprises, from top to bottom, an anti-reflection structure layer 1, a second phase change layer, a dielectric layer 3, a first phase change layer and a substrate 5, wherein the second phase change layer is a thin phase change layer 2, and the first phase change layer is a thick phase change layer 4.

[0108] Specifically, the anti-reflection structure layer 1 is a single-layer structure, the material is a BaF2 layer, the thickness is 0.01 μm, the thin phase change layer 2 is a VO2 square pattern grating structure 6, and the cross section of the grating structure 6 is as follows: Figure 7 As shown, the side length of the square is 2.76μm, the grating period is 6μm, the thickness is 0.01μm, the material at the gap between the square patterns is consistent with the material of the dielectric layer 3; the dielectric layer 3 is a BaF2 layer with a thickness of 1.50μm; the thick phase change layer 4 is an IST layer with a thickness of 6.98μm; the substrate layer 5 is an Al layer with a thickness greater than 0.2μm.

[0109] The spectral normal emissivity / absorptivity of the all-weather intelligent thermal control coating in this embodiment is Figure 8 The solar absorptivity and infrared emissivity parameters (a) in solar heating mode and radiation cooling mode are given in normal ,ε normal ) are (0.71, 0.07) and (0.30, 0.97) respectively, where the infrared emissivity only considers the 8-13 μm atmospheric window band, which better achieves the technical goal of the present invention. In addition, the combination of different phases of VO2 and IST can obtain a multi-level regulation mode of radiation characteristics.

[0110] Example 4

[0111] An all-weather intelligent thermal control coating based on thermotropic phase change material is applied to aircraft. From top to bottom, it includes an anti-reflection structure layer 1, a second phase change layer, a dielectric layer 3, a first phase change layer, and a substrate 5. The second phase change layer is a thin phase change layer 2, and the first phase change layer is a thick phase change layer 4.

[0112] Specifically, the anti-reflection structure layer 1 is a double-layer structure, the upper layer is a BaF2 layer with a thickness of 0.11μm, and the lower layer is a ZnS layer with a thickness of 1.01μm; the thin phase change layer 2 is an IST layer with a thickness of 0.01μm; the dielectric layer 3 is a ZnS layer with a thickness of 1.18μm; the thick phase change layer 4 is an IST layer with a thickness of 6.98μm; the substrate layer 5 is an Al layer with a thickness of 0.20μm.

[0113] The all-weather intelligent thermal control coating is placed in an atmosphere with an ambient temperature of 280K. The net radiation heat flux density of its amorphous and crystalline states is as follows: Fig. 9 and Fig.10 The all-weather smart thermal control coating with amorphous IST exhibits significant solar heating capabilities, with a net heat flux of -800W / m at 250K. 2The net heat flux increases significantly with increasing temperature, which is due to the reduction of heat flux absorbed by convection. When the temperature exceeds about 290K, the all-weather smart thermal control coating with crystalline IST is able to enter the radiation cooling mode. With the increase of temperature, the net radiation cooling flux increases significantly, reaching 600W / m at 330K. 2 This phenomenon can be attributed to the significant increase in the total emitted heat flux, which is mainly due to the high infrared emissivity. In summary, the smart coating shows significant radiative property regulation, which enables the solar heating of amorphous IST at low temperatures and the radiative cooling of crystalline IST at high temperatures.

[0114] In this embodiment, the calculation method of heat flux is expressed as follows:

[0115] Q net =Q emit (T)-Q atm (T atm )-Q parasitic (T,T atm )-Q sum (T)-Q heat ;

[0116]

[0117] Q parasitic (T,T atm )=Ah(T atm -T);

[0118]

[0119] In the formula, Q net represents the net emission / absorption power of the all-weather intelligent thermal control coating, that is, the heat flux density; T represents the temperature of the all-weather intelligent thermal control coating, T atm Indicates the ambient temperature, Q emit (T) represents the transmission power of the all-weather intelligent thermal control coating; Q atm (T atm ) represents the power of incident thermal radiation absorbed from the atmosphere, A represents the area of ​​the all-weather intelligent thermal control coating, E bλ Represents the spectral radiation power of a black body; represents the absorption rate of the atmosphere, which can be expressed by 1-τ atm (λ, Ω) is calculated, where τ atm (λ, Ω) represents the spectral atmospheric transmittance, which can be obtained through MODTRAN5; Q parasitic represents the parasitic power loss due to conduction and convection, h represents the heat transfer coefficient, Q sum represents the incident solar energy absorbed by the all-weather intelligent thermal control coating, I AM1.5Indicates AM1.5 solar radiation power.

[0120] Comparative Example 1

[0121] An all-weather intelligent thermal control coating based on thermotropic phase change material includes, from top to bottom, an anti-reflection structure layer 1, a second phase change layer, a dielectric layer 3, a first phase change layer, and a substrate 5. The second phase change layer is a thin phase change layer 2, and the first phase change layer is a thick phase change layer 4.

[0122] Specifically, the anti-reflection structure layer 1 is a double-layer structure, the upper layer is a BaF2 layer with a thickness of 0.11μm, and the lower layer is a ZnS layer with a thickness of 1.01μm; the thin phase change layer 2 is an IST layer with a thickness of 6.98μm; the dielectric layer 3 is a ZnS layer with a thickness of 1.18μm; the thick phase change layer 4 is an IST layer with a thickness of 6.98μm; the substrate layer 5 is an Al layer with a thickness of 0.22μm.

[0123] The spectral normal emissivity / absorption rate of the all-weather intelligent thermal control coating in this comparative example is Fig.11 It is shown in the figure that compared with Example 1, the coating in this comparative example can only achieve a significant regulation of the solar absorptivity of the coating by using the phase change of IST, and the regulation range of the infrared emissivity is extremely small. The solar absorptivity and infrared emissivity parameters of the coating in the amorphous IST and crystalline IST states (a normal ,ε normal ) are (0.82, 0.05) and (0.27, 0.22) respectively, which makes it impossible to effectively switch between solar heating and radiation cooling modes.

[0124] Comparative Example 2

[0125] An all-weather intelligent thermal control coating based on thermotropic phase change material includes, from top to bottom, an anti-reflection structure layer 1, a second phase change layer, a dielectric layer 3, a first phase change layer, and a substrate 5. The second phase change layer is a thin phase change layer 2, and the first phase change layer is a thick phase change layer 4.

[0126] Specifically, the anti-reflection structure layer 1 is a double-layer structure, the upper layer is a BaF2 layer with a thickness of 0.11μm, and the lower layer is a ZnS layer with a thickness of 1.01μm; the thin phase change layer 2 is an IST layer with a thickness of 0.01μm; the dielectric layer 3 is a ZnS layer with a thickness of 1.18μm; the thick phase change layer 4 is an IST layer with a thickness of 0.01μm; the substrate layer 5 is an Al layer with a thickness of 0.22μm.

[0127] The spectral normal emissivity / absorption rate of the all-weather intelligent thermal control coating in this comparative example is Fig.12It is shown in the figure that compared with Example 1, the coating in this comparative example can only achieve a large regulation of the infrared emissivity of the coating by using the phase change of IST, and the regulation range of the solar absorptivity is extremely small. The solar absorptivity and infrared emissivity parameters (anormal, normal) of the coating in the amorphous IST and crystalline IST states are (0.57, 0.04) and (0.34, 0.83), respectively, and it is impossible to achieve effective switching between solar heating and radiation cooling modes.

[0128] Comparative Example 3

[0129] An all-weather intelligent thermal control coating based on thermotropic phase change material comprises, from top to bottom, an anti-reflection structure layer 1, a second phase change layer, a dielectric layer 3, a first phase change layer, and a substrate 5.

[0130] Specifically, the anti-reflection structure layer 1 is a double-layer structure, the upper layer is a BaF2 layer with a thickness of 0.11μm, and the lower layer is a ZnS layer with a thickness of 1.01μm; the second phase change layer is an IST layer with a thickness of 6.98μm; the dielectric layer 3 is a ZnS layer with a thickness of 1.18μm; the first phase change layer is an IST layer with a thickness of 0.01μm; the substrate 5 layer is an Al layer with a thickness of 0.22μm.

[0131] The spectral normal emissivity / absorption rate of the all-weather intelligent thermal control coating in this comparative example is Fig.13 It is shown that compared with Example 1, the coating in this comparative example can only achieve a large regulation of the solar absorptivity of the coating by using the phase change of IST, and the regulation range of infrared emissivity is extremely small. The solar absorptivity and infrared emissivity parameters (anormal, normal) of the coating in the amorphous IST and crystalline IST states are (0.82, 0.03) and (0.27, 0.22), respectively, and it is impossible to achieve effective switching between solar heating and radiation cooling modes.

[0132] The description of each embodiment in the above embodiments has different emphases. For parts not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0133] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. All-weather intelligent thermal control coating based on thermotropic phase change materials, characterized in that: It includes a substrate, a first phase change layer, a dielectric layer, a second phase change layer and an anti-reflection structure layer which are stacked in sequence from bottom to top; The thickness of the first phase change layer is greater than that of the second phase change layer, and the first phase change layer and the second phase change layer are made of thermotropic phase change material.

2. The all-weather intelligent thermal control coating based on thermotropic phase change material according to claim 1, characterized in that: The thickness of each layer in the all-weather intelligent thermal control coating is determined by iterative optimization with the goal of maximizing the sum of the solar absorptivity control amplitude and the infrared emissivity control amplitude, under the constraint that the changing trends of the solar absorptivity and the infrared emissivity are opposite.

3. The all-weather intelligent thermal control coating based on thermotropic phase change material according to claim 1, characterized in that: The material of the substrate includes one or more of aluminum, silver, gold, doped silicon, and semiconductor oxide.

4. The all-weather intelligent thermal control coating based on thermotropic phase change material according to claim 1, characterized in that: The first phase change layer is a single-layer structure; Or, the material of the first phase change layer includes one or more of vanadium dioxide, vanadium trioxide, titanium dioxide, strontium-doped lanthanum manganate, calcium-doped lanthanum manganate and chalcogenide; Furthermore, the material of the first phase change layer includes vanadium dioxide, vanadium trioxide, titanium dioxide, strontium-doped lanthanum manganate, calcium-doped lanthanum manganate, Ge x Sb y Te z 、In x Sb y Te z , Sb2S3 and Sb2Se3; Preferably, the material of the first phase change layer is In x Sb y Te z ; Alternatively, the first phase change layer is disposed on the upper surface of the substrate by magnetron sputtering, vacuum evaporation, sol-gel or pulsed laser deposition.

5. The all-weather intelligent thermal control coating based on thermotropic phase change material according to claim 1, characterized in that: The dielectric layer is a single-layer structure; Or, the material of the dielectric layer includes barium fluoride, calcium fluoride, zinc selenide or zinc sulfide; Alternatively, the dielectric layer is disposed on the upper surface of the first phase change layer by magnetron sputtering, vacuum evaporation, sol-gel or pulsed laser deposition.

6. The all-weather intelligent thermal control coating based on thermotropic phase change material according to claim 1, characterized in that: The second phase change layer is a single layer structure or a grating structure; Or, the material of the second phase change layer includes one or more of vanadium dioxide, vanadium trioxide, titanium dioxide, strontium-doped lanthanum manganate, calcium-doped lanthanum manganate and chalcogenide; Furthermore, the material of the second phase change layer includes vanadium dioxide, vanadium trioxide, Ge x Sb y Te z 、In x Sb y Te z , Sb2S3 and Sb2Se3; Preferably, the material of the second phase change layer is vanadium dioxide or In x Sb y Te z ; Or, the second phase change layer is disposed on the upper surface of the dielectric layer by magnetron sputtering, vacuum evaporation or sol-gel pulse laser deposition; Alternatively, if the second phase change layer is a grating structure, the grating structure is obtained by photolithography technology.

7. The all-weather intelligent thermal control coating based on thermotropic phase change material according to claim 1, characterized in that: The anti-reflection structure layer is a single-layer structure or a multi-layer structure; Preferably, the anti-reflection structure layer is a multi-layer structure, and the refractive index of each layer of material in the multi-layer structure increases from top to bottom.

8. The all-weather intelligent thermal control coating based on thermotropic phase change material according to claim 1, characterized in that: The material of the anti-reflection structural layer includes one or more of barium fluoride, calcium fluoride, zinc selenide, and zinc sulfide; or, The anti-reflection structural layer is disposed on the upper surface of the second phase change layer by magnetron sputtering, vacuum evaporation, sol-gel or pulse laser deposition.

9. The all-weather intelligent thermal control coating based on thermotropic phase change material according to claim 1, characterized in that: The first phase change layer and the second phase change layer are made of the same or different materials.

10. Application of the all-weather intelligent thermal control coating based on thermotropic phase change materials as claimed in any one of claims 1 to 9 in the technical fields of buildings, vehicles, field base stations, aircraft and spacecraft.

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