Thermal radiation suppression layer and preparation method thereof and thermal management device

Abstract

The embodiment of the present application relates to a material for suppressing thermal radiation, a preparation method and application thereof, and a thermal management device, including: at least two sequentially stacked photonic crystal structures, each of which includes at least one sub-period consisting of a first material layer and a second material layer stacked in sequence; the first material layer and the second material layer have different refractive indices; in the direction of stacking the photonic crystal structures, the thicknesses of the first material layer and the second material layer in different photonic crystal structures are different, and along the direction from away from the heat source to close to the heat source during use of the material for suppressing thermal radiation, the thicknesses of the first material layer and the second material layer in different photonic crystal structures gradually decrease; for a photonic crystal structure including multiple sub-periods, the thicknesses of the first material layers in different sub-periods are the same, and the thicknesses of the second material layers in different sub-periods are the same. In this way, thermal radiation leakage can be effectively suppressed.

Description

Technical Field

[0001] The present application relates to the field of thermal radiation, and in particular to a material for suppressing thermal radiation, a preparation method and application thereof, and a thermal management device. Background Art

[0002] In the fields of aerospace, nuclear power conversion, and thermoelectric conversion, it is crucial to suppress the thermal radiation of ultra-high temperature heat sources. In addition, with the improvement and upgrading of more heat-based generators, research on thermal radiation suppression of small portable thermal generators is also imminent. Due to the extremely high temperature of some small heat-based generators, radiation replaces conduction and convection as the main mode of heat transfer. Therefore, an effective thermal radiation barrier across a small distance is one of the most important components of such systems. Using a thermal radiation suppression layer to reduce thermal radiation loss can not only improve the utilization rate of radiated heat and improve power generation efficiency, but also make the surface of the generator close to room temperature to avoid harm to people and the environment. At present, by covering the surface of the high-temperature emitter with a high-reflective material coating, it can be used to isolate thermal radiation, but the coating will evaporate and diffuse at high temperatures, causing the coating to degrade over time and the durability is not high. In addition, a non-contact housing with a highly reflective metal foil is another way to shield high-temperature thermal radiation. However, the commonly used refractory metal foil is difficult to achieve a high total reflectivity at the required infrared wavelength, and the metal itself absorbs heat due to its high extinction coefficient, causing its own temperature to rise and become a heat source itself. Although relatively high reflectivity can be achieved using gold, it is too expensive and too ductile to be used as a contactless housing. Summary of the invention

[0003] In view of this, the embodiments of the present application provide a material for suppressing thermal radiation, a preparation method and application thereof, and a thermal management device to solve at least one problem existing in the background technology.

[0004] In a first aspect, an embodiment of the present application provides a material for suppressing thermal radiation, including:

[0005] At least two sequentially stacked photonic crystal structures, each of the photonic crystal structures comprising at least one sub-period consisting of a first material layer and a second material layer stacked sequentially; the first material layer and the second material layer have different refractive indices;

[0006] In the direction of stacking the photonic crystal structures, the thicknesses of the first material layers in different photonic crystal structures are different, and the thicknesses of the second material layers in different photonic crystal structures are different; and along the direction from far away from the heat source to close to the heat source during use of the material for suppressing thermal radiation, the thicknesses of the first material layers and the second material layers in different photonic crystal structures gradually decrease;

[0007] For the photonic crystal structure including a plurality of sub-periods, the thicknesses of the first material layers in different sub-periods are the same, and the thicknesses of the second material layers in different sub-periods are the same.

[0008] In conjunction with the first aspect of the present application, in an optional implementation manner, the number of the photonic crystal structures is greater than or equal to three.

[0009] In combination with the first aspect of the present application, in an optional implementation, the number of the sub-periods in a single photonic crystal structure is greater than or equal to 2.

[0010] In combination with the first aspect of the present application, in an optional embodiment, in adjacent photonic crystal structures, the thickness of the first material layer and the second material layer with a higher refractive index is reduced by 30%-60%, and the thickness of the layer with a lower refractive index is reduced by 30%-60%.

[0011] In combination with the first aspect of the present application, in an optional embodiment, the refractive index ratio of one of the first material layer and the second material layer to the other is greater than or equal to 2.

[0012] In combination with the first aspect of the present application, in an optional implementation, the material of one of the first material layer and the second material layer includes magnesium fluoride, and the material of the other includes germanium.

[0013] In a second aspect, an embodiment of the present application provides a method for preparing a material for suppressing thermal radiation, the method comprising:

[0014] Sequentially forming alternately arranged first material layers and second material layers to form first to nth photonic crystal structures, wherein n is an integer greater than or equal to 2; the first material layers and the second material layers have different refractive indices;

[0015] Each of the first to nth photonic crystal structures comprises at least one sub-period consisting of the first material layer and the second material layer; for the photonic crystal structure comprising a plurality of sub-periods, the thickness of the first material layer in different sub-periods is the same, and the thickness of the second material layer in different sub-periods is the same;

[0016] From the first photonic crystal structure to the nth photonic crystal structure, the thickness of the first material layer in different photonic crystal structures is different, the thickness of the second material layer in different photonic crystal structures is different, and the thickness of the first material layer and the second material layer in different photonic crystal structures gradually decreases.

[0017] In conjunction with the second aspect of the present application, in an optional implementation, the first material layer in the first photonic crystal structure to the i-th photonic crystal structure is formed by a first process, and the first material layer in other photonic crystal structures except the first photonic crystal structure to the i-th photonic crystal structure is formed by a second process, 1≤i<n; the second material layer in the first photonic crystal structure to the j-th photonic crystal structure is formed by a third process, and the second material layer in other photonic crystal structures except the first photonic crystal structure to the j-th photonic crystal structure is formed by a fourth process, 1≤j<n; And / or, n is greater than or equal to 3; and / or, the sub-periods in a single photonic crystal structure are greater than or equal to 2; and / or, in adjacent photonic crystal structures, the thickness of the one with a higher refractive index between the first material layer and the second material layer is reduced by 30%-60%, and the thickness of the one with a lower refractive index is reduced by 30%-60%; and / or, the refractive index ratio of one of the first material layer and the second material layer to the other is greater than or equal to 2; and / or, the material of one of the first material layer and the second material layer includes magnesium fluoride, and the material of the other includes germanium.

[0018] In a third aspect, an embodiment of the present application provides a thermal management device, including:

[0019] Device body;

[0020] A thermal radiation suppression layer surrounds the device body to suppress the heat generated by the device body from radiating to the outside of the thermal radiation suppression layer or the heat outside the thermal radiation suppression layer from radiating to the device body; the material of the thermal radiation suppression layer includes at least one photonic crystal structure, and the photonic crystal structure includes at least one sub-period composed of a first material layer and a second material layer stacked in sequence; the first material layer and the second material layer have different refractive indices.

[0021] In a fourth aspect, embodiments of the present application provide application of the material for suppressing thermal radiation as described in any one of the first aspects in a thermal management device.

[0022] The material for suppressing thermal radiation, its preparation method and application, and thermal management device provided in the embodiments of the present application include: at least two photonic crystal structures stacked in sequence, each of the photonic crystal structures including at least one sub-period composed of a first material layer and a second material layer stacked in sequence; the first material layer and the second material layer have different refractive indices; in the direction of stacking of the photonic crystal structures, the thickness of the first material layer in different photonic crystal structures is different, the thickness of the second material layer in different photonic crystal structures is different, and along the direction from away from the heat source to close to the heat source during use of the material for suppressing thermal radiation, the thickness of the first material layer and the second material layer in different photonic crystal structures gradually decreases; for the photonic crystal structure including multiple sub-periods, the thickness of the first material layer in different sub-periods is the same, and the thickness of the second material layer in different sub-periods is the same. In the embodiment of the present application, the thickness of the first material layer located in different photonic crystal structures is different, and the thickness of the second material layer located in different photonic crystal structures is different, so that each photonic crystal structure has a different band gap. Along the direction from far away from the heat source to close to the heat source during the use of the material for suppressing thermal radiation, the thickness of the first material layer and the second material layer located in different photonic crystal structures gradually decreases, so that the material for suppressing thermal radiation formed by multiple photonic crystal structures stacked in sequence has a wider band gap. The material for suppressing thermal radiation can have a strong inhibitory effect on thermal radiation (electromagnetic waves) with a frequency within its band gap, so that the thermal radiation cannot pass through the material for suppressing thermal radiation, thereby effectively suppressing the leakage of thermal radiation.

[0023] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0025] Figure 1 A schematic diagram of a cross-sectional structure of a material for suppressing thermal radiation provided in an embodiment of the present application;

[0026] Figure 2 A schematic diagram of the distribution of the band gap of the photonic crystal structure in the material for suppressing thermal radiation provided in an embodiment of the present application in a thermal radiation spectrum diagram;

[0027] Figure 3It is a transmittance curve of heat radiation after passing through the material for suppressing heat radiation provided in an embodiment of the present application under the condition that the heat source temperature is 1200K;

[0028] Figure 4 It is a black body radiation spectrum diagram under the condition that the heat source temperature is 1200K and a thermal radiation leakage spectrum diagram after the thermal radiation passes through the material for suppressing thermal radiation provided in the embodiment of the present application;

[0029] Figure 5 : is a thermal radiation leakage rate curve corresponding to the first material layer and the second material layer under different thickness errors in the embodiment of the present application;

[0030] Figure 6 A schematic flow chart of a method for preparing a material for suppressing thermal radiation provided in an embodiment of the present application;

[0031] Figure 7 A schematic diagram of the cross-sectional structure of the material for suppressing thermal radiation during the preparation process provided in an embodiment of the present application. DETAILED DESCRIPTION

[0032] The exemplary embodiments disclosed in the present application will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the specific embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present application and to fully convey the scope disclosed in the present application to those skilled in the art.

[0033] In the following description, a large number of specific details are given to provide a more thorough understanding of the present application. However, it is obvious to those skilled in the art that the present application can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present application, some technical features known in the art are not described; that is, all features of the actual embodiments are not described here, and well-known functions and structures are not described in detail.

[0034] In the drawings, the sizes of layers, regions, elements and their relative sizes may be exaggerated for clarity. Like reference numerals denote like elements throughout.

[0035] It should be understood that when an element or layer is referred to as "on ...", "adjacent to ...", "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to other elements or layers, or there can be intervening elements or layers. On the contrary, when an element is referred to as "directly on ...", "directly adjacent to ...", "directly connected to" or "directly coupled to" other elements or layers, there is no intervening element or layer. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present application, the first element, component, region, layer or part discussed below can be represented as the second element, component, region, layer or part. And when the second element, component, region, layer or part is discussed, it does not indicate that the present application necessarily has the first element, component, region, layer or part.

[0036] Spatially relative terms such as "under", "beneath", "below", "under", "above", "above", etc., may be used here for convenience of description to describe the relationship between an element or feature shown in the figure and other elements or features. It should be understood that in addition to the orientation shown in the figure, the spatial relationship terms are intended to also include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is turned over, then the elements or features described as "under other elements" or "under it" or "under it" will be oriented as "on" other elements or features. Therefore, the exemplary terms "under" and "under" may include both upper and lower orientations. The device can be oriented otherwise (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0037] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present application. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0038] In order to thoroughly understand the present application, detailed steps and detailed structures will be presented in the following description to illustrate the technical solution of the present application. The preferred embodiments of the present application are described in detail below, but in addition to these detailed descriptions, the present application may also have other implementation methods.

[0039] The commonly used thermal radiation suppression layer in the related art is the multi-layer insulation (MLI) structure, which is widely used in spacecraft and cryogenic equipment. The multi-layer insulation structure is composed of multiple layers of metal foils with high reflectivity as reflective layers, and low thermal conductivity materials are filled in the middle as gaskets. It can reduce the surface thermodynamic temperature while reducing the infrared emissivity, and has an extremely low thermal conductivity coefficient under high vacuum. Molybdenum foil, gold foil and titanium foil can be used as high reflectivity materials in the multi-layer insulation structure, and low thermal conductivity materials such as zirconium oxide, silicon dioxide or ytterbium powder can be filled in the middle of the two reflective layers. Although the multi-layer insulation structure has a certain heat insulation effect, the reflectivity of a single multi-layer insulation structure is still not high enough, and the high extinction coefficient of the metal material causes it to absorb part of the thermal radiation, resulting in a temperature increase, and it itself becomes an emitter, which in turn affects its insulation effect on thermal radiation.

[0040] Omnidirectional reflectors (ODR) are composed of alternating layers of materials with different dielectric constants. The materials with high and low refractive indices are arranged alternately to form a periodic structure, which can produce a photonic crystal band gap, so that electromagnetic waves with frequencies in the band gap cannot propagate in the crystal, and can selectively allow light of a certain wavelength to pass through while preventing light of other wavelengths from passing through. In the related art, omnidirectional reflectors are usually used in waveguides, filters, and light-emitting diodes at room temperature to control the spectrum. The omnidirectional reflectors in waveguides and filters only have a narrower band gap. Thermal radiation has a wider band, especially as the temperature of the heat source increases, the band coverage of the thermal radiation generated by the heat source is larger, and the requirements for thermal radiation shielding materials are higher. Since the omnidirectional reflectors in the related art have only a narrow bandwidth and cannot cover thermal radiation with a wide band to achieve the effect of effective radiation shielding, if the number of periods inside the photonic crystal is continuously increased to expand to a sufficient bandwidth, dozens or even hundreds of layers of materials need to be superimposed, so it cannot be achieved in production.

[0041] Based on this, the present application embodiment provides a material for suppressing thermal radiation. Figure 1 As shown, materials used to suppress thermal radiation include:

[0042] At least two sequentially stacked photonic crystal structures 10, each of the photonic crystal structures 10 includes at least one sub-period consisting of a first material layer 11 and a second material layer 12 stacked sequentially; the first material layer 11 and the second material layer 12 have different refractive indices;

[0043] In the direction of stacking the photonic crystal structures 10, the thickness of the first material layer 11 in different photonic crystal structures 10 is different, and the thickness of the second material layer 12 in different photonic crystal structures 10 is different; and along the direction from far away from the heat source to close to the heat source during use of the material for suppressing thermal radiation, the thickness of the first material layer 11 and the second material layer 12 in different photonic crystal structures 10 gradually decreases;

[0044] For the photonic crystal structure 10 including a plurality of sub-periods, the thicknesses of the first material layers 11 in different sub-periods are the same, and the thicknesses of the second material layers 12 in different sub-periods are the same.

[0045] It should be noted that the material for suppressing thermal radiation can be used in thermal management devices. For example, the material for suppressing thermal radiation can be around the device body in the thermal management device during use. The thickness of the first material layer and the second material layer in the photonic crystal structure close to the heat source of the material for suppressing thermal radiation is the thinnest, and the thickness of the first material layer and the second material layer in the photonic crystal structure away from the heat source is the thickest. Therefore, along the direction from away from the heat source to close to the heat source of the material for suppressing thermal radiation during use, it can be considered as the direction from the photonic crystal structure with the thinnest first material layer and the second material layer to the photonic crystal structure with the thickest first material layer and the second material layer. The thickness of the first material layer 11 and the second material layer 12 in different photonic crystal structures 10 gradually decreases. The gradual reduction method here can be, for example, a linear reduction or a nonlinear reduction, such as at least one of an exponential reduction, a logarithmic reduction, a step-by-step reduction, etc.

[0046] In the embodiment of the present application, the thickness of the first material layer 11 located in different photonic crystal structures 10 is different, and the thickness of the second material layer 12 located in different photonic crystal structures 10 is different, so that each photonic crystal structure 10 has a different band gap, and along the direction from far away from the heat source to close to the heat source during use of the material for suppressing thermal radiation, the thickness of the first material layer 11 and the second material layer 12 located in different photonic crystal structures 10 gradually decreases, so that the material for suppressing thermal radiation formed by the multiple photonic crystal structures 10 stacked in sequence has a wider band gap, and the material for suppressing thermal radiation can have a strong inhibitory effect on thermal radiation (electromagnetic waves) with a frequency within its band gap, so that the thermal radiation cannot pass through the material for suppressing thermal radiation, thereby effectively suppressing thermal radiation leakage.

[0047] The material for suppressing thermal radiation in the embodiment of the present application achieves a strong suppression effect on thermal radiation through at least two sequentially stacked photonic crystal structures 10, which is completely different from the suppression method of thermal radiation by high-reflective material coatings and multi-layer insulation structures in the related art, and has the advantages of better thermal stability, higher durability, lower emissivity, stronger suppression effect of thermal radiation, and lighter weight. Moreover, compared with the single photonic crystal structure design in the omnidirectional reflector in the related art, the material for suppressing thermal radiation in the embodiment of the present application has a wider band gap by designing the thickness of the first material layer 11 and the second material layer 12 in the photonic crystal structure 10 and the number of photonic crystal structures 10, so that the material for suppressing thermal radiation has a wider band gap, thereby covering thermal radiation with a wide band to achieve an effective radiation shielding effect, and it is easy to implement in terms of process.

[0048] Exemplarily, the material of one of the first material layer 11 and the second material layer 12 may include at least one of zinc sulfide, zinc selenide, magnesium fluoride, ytterbium fluoride, calcium fluoride, and lithium fluoride, and the material of the other may include at least one of germanium, silicon nitride, gallium indium phosphide (GaInP), and aluminum indium phosphide (AlInP). The extinction coefficients of the materials of the first material layer 11 and the second material layer 12 in the visible light to near-infrared band are close to 0, so that the temperature of the material used to suppress thermal radiation during use can be better avoided. The thickness of the first material layer 11 and the second material layer 12 in the photonic crystal structure 10 can be set according to actual needs, for example, it can be set according to the temperature of the thermal radiation heat source to form the desired band gap range.

[0049] Generally, as the temperature of the heat source increases, the wavelength range of the thermal radiation generated by the heat source becomes wider. In the embodiment of the present application, as the number of the photonic crystal structures 10 increases, the band gap of the material used to suppress the thermal radiation becomes wider, and the wavelength range of the thermal radiation that can be covered becomes wider. Therefore, in some embodiments, please refer to Figure 1 , the number of photonic crystal structures 10 is greater than or equal to 3. This can better suppress the heat radiation generated by the high-temperature heat source. In some specific embodiments, the number of photonic crystal structures 10 can be 4-5, which can better suppress the heat radiation while keeping the cost at a low level.

[0050] Figure 1 FIG. 4 shows a case where the number of photonic crystal structures 10 is 4. For the convenience of subsequent description, Figure 1 From bottom to top, the photonic crystal structure 10 can be sequentially referred to as a first photonic crystal structure, a second photonic crystal structure, a third photonic crystal structure, and a fourth photonic crystal structure.

[0051] Please refer to Figure 2The spectrum of thermal radiation usually covers a wide band, and the wavelength corresponding to the maximum spectral radiation intensity can be called the peak radiation wavelength. Figure 1 As shown), wherein the thickness of the first material layer 11 and the second material layer 12 in the first photonic crystal structure to the fourth photonic crystal structure gradually decreases, and the band gaps of the first photonic crystal structure, the second photonic crystal structure, the third photonic crystal structure and the fourth photonic crystal structure can respectively cover a wavelength range of thermal radiation (such as Figure 2 As shown), it can better reflect the thermal radiation within the corresponding wavelength range, so that multiple photonic crystal structures 10 can cover a wider band range of thermal radiation after being stacked in sequence, especially a band range with stronger spectral radiation intensity, so that it can have a stronger inhibitory effect on thermal radiation. As the temperature of the heat source increases, the wider the band of the thermal radiation spectrum, the greater the total intensity of the spectral radiation. Therefore, when the temperature of the heat source is high, more photonic crystal structures 10 can be stacked in sequence to form a material with a wider band gap for suppressing thermal radiation, such as 5 or more, so as to achieve a better effect of suppressing thermal radiation.

[0052] A single photonic crystal structure 10 has a good reflective effect on the wavelength band of thermal radiation that can be covered by its band gap. The more periods there are in a single photonic crystal structure 10, the stronger the reflective effect on thermal radiation in a specific wavelength band. Therefore, in some embodiments, the number of sub-periods in a single photonic crystal structure 10 is greater than or equal to 2. In this way, the superposition of multiple sub-periods can make the reflective effect of the photonic crystal structure 10 on thermal radiation reach a higher level.

[0053] In practical applications, the number of sub-periods in a single photonic crystal structure 10 can be set according to the temperature of the thermal radiation heat source, the expected reflection effect, and the cost. In addition, the number of sub-periods in different photonic crystal structures 10 can be the same or different. In some specific embodiments, the number of sub-periods in different photonic crystal structures 10 can be different, such as Figure 2As shown, there is a peak radiation wavelength in the spectrum of thermal radiation, and the spectral radiation intensity is relatively large in the peak radiation wavelength and the band near the peak radiation wavelength. The number of sub-periods in the corresponding photonic crystal structure 10 whose band gap covers the peak radiation wavelength and the band near the peak radiation wavelength can be more than the number of sub-periods in other photonic crystal structures 10, so as to achieve a better suppression effect on thermal radiation. For example, under the condition that the heat source temperature is 1200K, the test results of suppressing thermal radiation on the material for suppressing thermal radiation formed by stacking four photonic crystal structures 10 in sequence show that when the number of sub-periods in a single photonic crystal structure 10 is 2, under the shielding of the material for suppressing thermal radiation, the leakage rate of thermal radiation is 6.51%, when the number of sub-periods in a single photonic crystal structure 10 increases to 3, under the same conditions, the leakage rate of thermal radiation is reduced to 5.49%, and when the number of sub-periods in a single photonic crystal structure 10 increases to 4, under the same conditions, the leakage rate of thermal radiation is reduced to 5.43%.

[0054] In some embodiments, in adjacent photonic crystal structures 10, the thickness of the one with a higher refractive index in the first material layer 11 and the second material layer 12 is reduced by 30%-60%, for example, it can be 35%, 40%, 45%, 50% or 55%, and the thickness of the one with a lower refractive index is reduced by 30%-60%, for example, it can be 35%, 40%, 45%, 50% or 55%, etc.

[0055] like Figure 2 As shown, the spectral band of thermal radiation is continuous. In order to make the material used to suppress thermal radiation have a better suppressing effect on thermal radiation, in the embodiment of the present application, in adjacent photonic crystal structures 10, the thickness of the first material layer 11 and the second material layer 12 with a higher refractive index is reduced by 30%-60%, and the thickness of the other with a lower refractive index is reduced by 30%-60%. This can make the band covered by the band gap of adjacent photonic crystal structures 10 continuous, thereby achieving a better effect of suppressing thermal radiation.

[0056] It can be understood that the wavelengths covered by the band gaps of adjacent photonic crystal structures 10 may also partially overlap, which can further ensure the suppression effect on thermal radiation.

[0057] In some embodiments, a refractive index ratio between one of the first material layer 11 and the second material layer 12 and the other is greater than or equal to 2.

[0058] For a single photonic crystal structure 10, the ratio of the refractive index of the first material layer 11 to the refractive index of air and the ratio of the refractive index of the second material layer 12 to the refractive index of air are both greater than 1. The greater the difference in refractive index between the first material layer 11 and the second material layer 12, the wider the band gap of the single photonic crystal structure 10 can be. In this embodiment, the ratio of the refractive index of one of the first material layer 11 and the second material layer 12 to the other is greater than or equal to 2, so that the band gap of the single photonic crystal structure 10 can be wider. Compared with the case where the difference in refractive index between the first material layer 11 and the second material layer 12 is smaller, a relatively smaller number of photonic crystal structures 10 can be used to form a material for suppressing thermal radiation to achieve basically the same effect of suppressing thermal radiation, thereby simplifying the manufacturing process and reducing costs. In addition, the greater the difference in refractive index between the first material layer 11 and the second material layer 12, the better the reflection effect of the stacked structure of the first material layer 11 and the second material layer 12 on thermal radiation. Therefore, compared with the case where the difference in refractive index between the first material layer 11 and the second material layer 12 is small, the thickness of the first material layer 11 and the second material layer 12 can be set relatively smaller to achieve basically the same effect of suppressing thermal radiation, which can reduce costs and make the final material for suppressing thermal radiation thinner and more applicable.

[0059] In some specific embodiments, within the wavelength band of thermal radiation, the extinction coefficients of the first material layer 11 and the second material layer 12 are both close to zero.

[0060] The extinction coefficients of the first material layer 11 and the second material layer 12 are close to 0, and the absorptivity of the photonic crystal structure 10 to thermal radiation is close to 0. According to Kirchhoff's law, the emissivity is equal to the absorptivity, and the emissivity of the photonic crystal structure 10 is also close to 0. This can prevent the temperature of the material used to suppress thermal radiation from rising and becoming an emitter, thereby further reducing the leakage of thermal radiation.

[0061] In some embodiments, the material of one of the first material layer 11 and the second material layer 12 includes magnesium fluoride, and the material of the other includes germanium.

[0062] The refractive index of magnesium fluoride is 1.36, the refractive index of germanium is 4.25, the refractive index difference between the first material layer 11 and the second material layer 12 is large enough, and the extinction coefficients of magnesium fluoride and germanium are close to 0, so the photonic crystal structure 10 can achieve good reflection performance for large-angle incident waves. In view of the omnidirectionality of thermal radiation, the material used to suppress thermal radiation can effectively suppress thermal radiation leakage in a wider band. In addition, magnesium fluoride and germanium have good high temperature resistance, so that the material used to suppress thermal radiation has good thermal stability and can be applied to thermal radiation of high-temperature heat sources, such as heat sources with a temperature greater than or equal to 1000K.

[0063] The performance of the material for suppressing heat radiation in the above embodiment was tested, wherein the temperature of the heat source, the sub-period arrangement in the photonic crystal structure 10 and the heat radiation leakage rate are shown in Table 1.

[0064] It should be noted that the number of photonic crystal structures 10 in the material for suppressing thermal radiation is 4, the number of sub-periods in a single photonic crystal structure 10 is 2, and Table 1 only shows the material composition and thickness of a single sub-period in a single photonic crystal structure 10. In the test, the fourth photonic crystal structure is close to the heat source but not in contact with the heat source, and thermal radiation is incident on the surface of the fourth photonic crystal structure.

[0065] Table 1

[0066]

[0067] It can be seen from Table 1 that from the first photonic crystal structure to the fourth photonic crystal structure, the thickness of MgF2 gradually decreases, and the thickness of Ge also gradually becomes smaller, so that the material for suppressing thermal radiation formed by the multiple photonic crystal structures stacked in sequence has a wider band gap. When the heat source temperature is greater than or equal to 800K, under the shielding of the material for suppressing thermal radiation, the thermal radiation leakage rate is less than 10%, that is, the reflectivity of the material for suppressing thermal radiation to thermal radiation reaches more than 90%.

[0068] Figure 3 This is the transmittance curve of the thermal radiation after passing through the material used to suppress thermal radiation under the condition of the heat source temperature of 1200K. Figure 4 It is the black body radiation spectrum under the condition of heat source temperature of 1200K and the thermal radiation leakage spectrum after the thermal radiation passes through the material used to suppress thermal radiation. Figure 4 As shown in the blackbody radiation spectrum, under the condition of 1200K, the wavelength range of thermal radiation is mainly between 0-20μm. In the part of the band with wavelength close to 0, the spectral radiation intensity is close to 0. In the band with wavelength greater than 10μm, the spectral radiation intensity is relatively small, especially in the band with wavelength greater than 15μm, the spectral radiation intensity gradually approaches 0. Figure 3 , since the band gaps from the first photonic crystal structure to the fourth photonic crystal structure cover most of the bands of thermal radiation, especially the bands with large spectral radiation intensity, the thermal radiation transmittance of the corresponding bands is low, and the spectral radiation intensity corresponding to the bands not covered by the band gaps from the first photonic crystal structure to the fourth photonic crystal structure is relatively small. Even if the transmittance of thermal radiation in the corresponding band is high, the impact on the overall thermal radiation leakage rate is very small, such as Figure 4As shown in the thermal radiation leakage spectrum, after reflection from the first photonic crystal structure to the fourth photonic crystal structure, the leakage rate of thermal radiation is very low. Therefore, taking into account the production cost, the material for suppressing thermal radiation composed of 4-5 photonic crystal structures can have a good effect in suppressing thermal radiation while keeping the cost at a low level. Specific data show that for a heat source of 1200K, the band gap range of the material used to suppress thermal radiation can be close to 99% (0-20μm) of its thermal radiation intensity, and the thermal radiation leakage rate is only 6.51%.

[0069] As can be seen from the above, the material used to suppress thermal radiation in the present application has a wide band gap, is resistant to high temperatures, can be applied to heat sources above 800K, and can have a high reflectivity (over 90%) regardless of the angle and polarization form of the incident wave, and can establish an effective thermal radiation barrier. The thickness of the material layer in the sub-period in a single photonic crystal structure 10, the number of sub-periods, and the number of photonic crystal structures 10 can be flexibly set according to the temperature of the heat source. According to Wien's displacement law, the peak radiation wavelength of thermal radiation is inversely proportional to the temperature of the heat source, that is, the higher the temperature, the shorter the peak radiation wavelength, that is, as the temperature of the heat source increases, the band with a larger spectral radiation intensity will shift to the left. As shown in the data in Table 1, as the temperature of the heat source increases, the thickness of the first material layer 11 and the second material layer 12 in the sub-period in a single photonic crystal structure 10 can be gradually reduced, and the thinner the photonic crystal structure 10 can cover a shorter band. The material used to suppress thermal radiation in the embodiment of the present application is very suitable for suppressing thermal radiation from a high-temperature heat source. The material for suppressing thermal radiation formed by the four photonic crystal structures 10 for the 1200K heat source has a total thickness of less than 13μm. The total thickness of the material for suppressing thermal radiation is small, and it has the advantage of being light and thin, and can be better applied to various portable small heat sources in deep space and deep sea exploration equipment. For the multi-layer insulation structure in relative technology, if the thermal radiation shielding efficiency of the multi-layer insulation structure is to be improved, the number of layers of the multi-layer insulation structure needs to be increased. Due to the large volume and weight of the metal foil and powder material, the total thickness of the multi-layer insulation structure will reach the centimeter or even decimeter level. Therefore, the material for suppressing thermal radiation in the present application has significant advantages.

[0070] Considering the processing accuracy problem in the actual process, the first material layer 11 and the second material layer 12 in the material for suppressing thermal radiation provided by the present application will have certain thickness errors during the manufacturing process, that is, changes in material thickness and reflectivity due to process limitations. In order to verify the influence of possible process errors of the first material layer 11 and the second material layer 12 on the performance of the material for suppressing thermal radiation, the Monte Carlo method is used to introduce the relative thickness uncertainty of the first material layer 11 and the second material layer 12 according to the fixed Gaussian standard deviation, and the results are interpreted as the material design for the 1200K heat source in Table 1. For each standard deviation, the simulation was run 100,000 times, and the results are as follows: Figure 5 As shown. The smaller the process error, the closer the thermal radiation leakage rate is to the optimal value and the narrower the distribution. A relatively small process error (for example, 5%) will cause the average value of the thermal radiation leakage rate to be concentrated around 6.84%. When the process error is larger, the thermal radiation leakage rate will also increase. However, even when the process error is as high as 13%, the average thermal radiation leakage rate is still less than 8%, which shows that when the process error is large, the shielding effect of the material used to suppress thermal radiation in this application is still very good. At the same time, the change of the optical constants of the material is also simulated. Considering the potential temperature rise of the first material layer 11 and the second material layer 12, some optical constants at high temperatures are used to increase the difference in reflectivity of the first material layer 11 and the second material layer 12 to about 3%-5%. The results show that the thermal radiation leakage rate is only slightly increased from 6.51% to 7.48%. It can be seen that the material used to suppress thermal radiation in this application has a good fault tolerance (the level of accommodating process errors). Considering that the tolerance (error) of processes commonly used to form the first material layer 11 and the second material layer 12, such as sputtering, optical coating, etc., is about 9%, the material for suppressing thermal radiation in the present application is easy to implement in terms of technology.

[0071] Based on this, an embodiment of the present application provides a method for preparing a material for suppressing thermal radiation. Figure 6 A schematic diagram of a process for preparing a material for suppressing thermal radiation provided in an embodiment of the present application; Figure 6 As shown, the method includes:

[0072] Step S101, sequentially forming alternately arranged first material layers and second material layers to form the first photonic crystal structure to the nth photonic crystal structure, wherein n is an integer greater than or equal to 2; the first material layer and the second material layer have different refractive indices; each photonic crystal structure from the first photonic crystal structure to the nth photonic crystal structure includes at least one sub-period consisting of the first material layer and the second material layer; for a photonic crystal structure including a plurality of sub-periods, the thickness of the first material layer in different sub-periods is the same, and the thickness of the second material layer in different sub-periods is the same; from the first photonic crystal structure to the nth photonic crystal structure, the thickness of the first material layer in different photonic crystal structures is different, the thickness of the second material layer in different photonic crystal structures is different, and the thickness of the first material layer and the second material layer in different photonic crystal structures gradually decreases.

[0073] It can be understood that in the first to nth photonic crystal structures formed by the above method, the thickness of the first material layer in different photonic crystal structures is different, and the thickness of the second material layer in different photonic crystal structures is different, so that each photonic crystal structure has a different band gap, and along the direction from away from the heat source to close to the heat source during the use of the material for suppressing thermal radiation, the thickness of the first material layer and the second material layer in different photonic crystal structures gradually decreases, so that the material for suppressing thermal radiation formed by multiple photonic crystal structures stacked in sequence has a wider band gap, which can produce a stronger reflection effect on thermal radiation, thereby effectively suppressing thermal radiation leakage.

[0074] Next, combine Figure 7 , the preparation method of the material for suppressing thermal radiation provided in the embodiment of the present application and its beneficial effects are further described in detail.

[0075] First, please refer to Figure 7, executing step S101, sequentially forming alternately arranged first material layers 11 and second material layers 12 to form the first photonic crystal structure 101 to the nth photonic crystal structure 104, wherein n is an integer greater than or equal to 2; the first material layer 11 and the second material layer 12 have different refractive indices; each photonic crystal structure in the first photonic crystal structure 101 to the nth photonic crystal structure 104 includes at least one sub-period composed of the first material layer 11 and the second material layer 12; for a photonic crystal structure including a plurality of sub-periods, the thickness of the first material layer 11 in different sub-periods is the same, and the thickness of the second material layer 12 in different sub-periods is the same; from the first photonic crystal structure 101 to the nth photonic crystal structure 104, the thickness of the first material layer 11 in different photonic crystal structures is different, the thickness of the second material layer 12 in different photonic crystal structures is different, and the thickness of the first material layer 11 and the second material layer 12 in different photonic crystal structures gradually decreases.

[0076] Exemplarily, the first material layer 11 and the second material layer 12 can be formed by at least one of magnetron sputtering, electron beam evaporation, chemical vapor deposition, physical vapor deposition, atomic layer deposition, sol-gel process, electrochemical deposition, optical coating, laser chemical vapor deposition process, etc., wherein the material of one of the first material layer 11 and the second material layer 12 can include at least one of zinc sulfide, zinc selenide, magnesium fluoride, ytterbium fluoride, calcium fluoride, and lithium fluoride, and the material of the other can include at least one of germanium, silicon nitride, gallium indium phosphide (GaInP), and aluminum indium phosphide (AlInP).

[0077] In some specific embodiments, first material layers 11 and second material layers 12 arranged alternately may be sequentially formed on a substrate (not shown) to form the above-mentioned first to nth photonic crystal structures 101 to 104 .

[0078] Here, the material of the substrate may include, for example, any material capable of growing the first material layer 11 , such as at least one of silicon, germanium or tantalum, etc. Usually, the first material layer 11 has good adhesion to the substrate.

[0079] In some embodiments, the first material layer 11 in the first photonic crystal structure 101 to the i-th photonic crystal structure 102 is formed by a first process, and the first material layer 11 in other photonic crystal structures except the first photonic crystal structure 101 to the i-th photonic crystal structure 102 is formed by a second process, 1≤i<n; the second material layer 12 in the first photonic crystal structure 101 to the j-th photonic crystal structure 103 is formed by a third process, and the second material layer 12 in other photonic crystal structures except the first photonic crystal structure 101 to the j-th photonic crystal structure 103 is formed by a fourth process, 1≤j<n.

[0080] In the embodiment of the present application, from the first photonic crystal structure 101 to the nth photonic crystal structure 104, the thickness of the first material layer 11 located in different photonic crystal structures is different, the thickness of the second material layer 12 located in different photonic crystal structures is different, and the thickness of the first material layer 11 and the second material layer 12 located in different photonic crystal structures gradually decreases. Therefore, different processes can be used to form first material layers 11 of different thicknesses and second material layers 12 of different thicknesses. By selecting a suitable process to reduce the error in thickness of the first material layer 11 and the second material layer 12 formed, the process accuracy is improved, and then the performance of the prepared material for suppressing thermal radiation is improved.

[0081] It should be noted that Figure 7 The positions of the i-th photonic crystal structure 102 and the j-th photonic crystal structure 103 are only examples. In the embodiment of the present application, i and j may be equal, i may be greater than j, or i may be less than j.

[0082] Exemplarily, taking n as 4, i as 1, and j as 2 as an example, a magnetron sputtering process can be used to form the first material layer 11 (more specifically, for example, germanium) in the first photonic crystal structure 101, and an electron beam evaporation process can be used to form the first material layer 11 (more specifically, for example, germanium) in the second photonic crystal structure to the fourth photonic crystal structure, that is, the electron beam evaporation process is used to form relatively thin germanium, and the magnetron sputtering process is used to form relatively thick germanium; for example, a chemical vapor deposition process can be used to form the second material layer 12 (more specifically, for example, magnesium fluoride) in the first photonic crystal structure 101 and the second photonic crystal structure, and an electron beam evaporation process can be used to form the second material layer 12 (more specifically, for example, magnesium fluoride) in the third photonic crystal structure and the fourth photonic crystal structure, that is, the electron beam evaporation process is used to form relatively thin magnesium fluoride, and the chemical vapor deposition process is used to form relatively thick magnesium fluoride, thereby reducing the thickness error of the first material layer 11 and the second material layer 12 and improving the accuracy of the process.

[0083] In some embodiments, n is greater than or equal to 3. The more photonic crystal structures in the material used to suppress thermal radiation, the wider the band gap, and the wider the wavelength band of thermal radiation that can be covered, so that the thermal radiation generated by the high-temperature heat source can be better suppressed. In some specific embodiments, n can be 4-5, so that the cost can be controlled at a low level while better suppressing thermal radiation.

[0084] In some embodiments, the number of sub-periods in a single photonic crystal structure is greater than or equal to 2. Thus, the superposition of multiple sub-periods can enable the photonic crystal structure to achieve a higher level of reflection effect on thermal radiation.

[0085] In some embodiments, in adjacent photonic crystal structures, the thickness of the one with a higher refractive index in the first material layer 11 and the second material layer 12 is reduced by 30%-60%, such as 35%, 40%, 45%, 50% or 55%, and the thickness of the one with a lower refractive index is reduced by 30%-60%, such as 35%, 40%, 45%, 50% or 55%, etc. In this way, the band gaps of adjacent photonic crystal structures can cover a continuous band, thereby achieving a better effect of suppressing thermal radiation.

[0086] In some embodiments, the refractive index ratio of one of the first material layer 11 and the second material layer 12 to the other is greater than or equal to 2. This can make the band gap of the single photonic crystal structure wider, thereby achieving a better effect of suppressing thermal radiation.

[0087] In some embodiments, the material of one of the first material layer 11 and the second material layer 12 includes magnesium fluoride, and the material of the other includes germanium.

[0088] Based on this, an embodiment of the present application provides a thermal management device, which includes:

[0089] Device body;

[0090] A thermal radiation suppression layer surrounds the device body to suppress the heat generated by the device body from radiating to the outside of the thermal radiation suppression layer or the heat outside of the thermal radiation suppression layer from radiating to the device body; the material of the thermal radiation suppression layer includes at least one photonic crystal structure, the photonic crystal structure includes at least one sub-period composed of a first material layer and a second material layer stacked in sequence; the first material layer and the second material layer have different refractive indices.

[0091] The thermal management device in the embodiment of the present application may include, for example, a heat-to-electricity conversion device (e.g., a nuclear battery, a fuel cell, a micro-turbine, a Stirling generator, an alkali metal fluid battery, etc.), a device for isolating a heat source (an aircraft protection device, etc.). The material of the thermal radiation suppression layer includes at least one photonic crystal structure, so that it can have a good reflection effect on the thermal radiation, thereby effectively suppressing the thermal radiation generated by the heat source.

[0092] Based on this, an embodiment of the present application provides another thermal management device, which includes:

[0093] Device body;

[0094] A thermal radiation suppression layer surrounds the device body to suppress the heat generated by the device body from radiating to the outside of the thermal radiation suppression layer or the heat outside the thermal radiation suppression layer from radiating to the device body; the material of the thermal radiation suppression layer includes the material for suppressing thermal radiation described in any of the aforementioned embodiments.

[0095] The thermal management device in the embodiment of the present application can be understood with reference to the thermal management device in the above-mentioned embodiment. Since the material of the thermal radiation suppression layer in the embodiment of the present application includes the material for suppressing thermal radiation described in any of the above-mentioned embodiments, the beneficial effects of the material for suppressing thermal radiation described in any of the above-mentioned embodiments are applicable to the thermal radiation suppression layer in the embodiment of the present application, and the thermal radiation suppression layer can also suppress the thermal radiation generated by the heat source well.

[0096] Based on this, an embodiment of the present application provides an application of a material for suppressing thermal radiation in a thermal management device, wherein the material for suppressing thermal radiation includes at least one photonic crystal structure, and the photonic crystal structure includes at least one sub-period composed of a first material layer and a second material layer stacked in sequence; the first material layer and the second material layer have different refractive indices.

[0097] Based on this, an embodiment of the present application also provides an application of a material for suppressing thermal radiation as described in any of the aforementioned embodiments in a thermal management device.

[0098] It should be noted that the material embodiments for suppressing thermal radiation, the preparation method embodiments of the material for suppressing thermal radiation, the application embodiments of the material for suppressing thermal radiation, and the thermal management device embodiments provided in the present application belong to the same concept; the technical features in the technical solutions recorded in the embodiments can be arbitrarily combined without conflict. However, it should be further noted that the combination of the various technical features of the material for suppressing thermal radiation provided in the embodiments of the present application can already solve the technical problem to be solved by the present application; therefore, the material for suppressing thermal radiation provided in the embodiments of the present application may not be limited by the preparation method of the material for suppressing thermal radiation provided in the embodiments of the present application, and any material for suppressing thermal radiation prepared by the preparation method of the material for suppressing thermal radiation provided in the embodiments of the present application is within the scope of protection of the present application.

[0099] It should be understood that the above embodiments are exemplary and are not intended to include all possible implementations included in the claims. Various modifications and changes may be made on the basis of the above embodiments without departing from the scope of the present disclosure. Similarly, the various technical features of the above embodiments may be arbitrarily combined to form other embodiments of the present application that may not be explicitly described. Therefore, the above embodiments only express several implementations of the present application and do not limit the scope of protection of the patent of this application.

Claims

1. A thermal radiation suppression layer, characterized in that: include: Four sequentially stacked photonic crystal structures, each of the photonic crystal structures comprises two sub-periods consisting of a first material layer and a second material layer stacked sequentially, in each of the sub-periods, the direction from the first material layer to the second material layer is the direction from away from the heat source to close to the heat source during use of the thermal radiation suppression layer; the first material layer is germanium, and the second material layer is magnesium fluoride; in a single photonic crystal structure, the thickness of the first material layer in the two sub-periods is the same, and the thickness of the second material layer in the two sub-periods is the same; The direction from the first photonic crystal structure to the fourth photonic crystal structure is the direction from far away from the heat source to close to the heat source during use of the thermal radiation suppression layer; the temperature of the heat source is 800K; in the first photonic crystal structure, the thickness of the first material layer is 1228.2nm, and the thickness of the second material layer is 3687.0nm; in the second photonic crystal structure, the thickness of the first material layer is 646.4nm, and the thickness of the second material layer is 2145.2nm; in the third photonic crystal structure, the thickness of the first material layer is 280.1nm, and the thickness of the second material layer is 1407.8nm; in the fourth photonic crystal structure, the thickness of the first material layer is 150.8nm, and the thickness of the second material layer is 804.4nm; The reflectivity of the heat radiation suppression layer to heat radiation from a heat source reaches more than 90%.

2. A thermal radiation suppression layer, characterized in that: include: Four sequentially stacked photonic crystal structures, each of the photonic crystal structures comprises two sub-periods consisting of a first material layer and a second material layer stacked sequentially, in each of the sub-periods, the direction from the first material layer to the second material layer is the direction from away from the heat source to close to the heat source during use of the thermal radiation suppression layer; the first material layer is germanium, and the second material layer is magnesium fluoride; in a single photonic crystal structure, the thickness of the first material layer in the two sub-periods is the same, and the thickness of the second material layer in the two sub-periods is the same; The direction from the first photonic crystal structure to the fourth photonic crystal structure is the direction from far away from the heat source to close to the heat source during use of the thermal radiation suppression layer; the temperature of the heat source is 1000K; in the first photonic crystal structure, the thickness of the first material layer is 857.0nm, and the thickness of the second material layer is 2612.1nm; in the second photonic crystal structure, the thickness of the first material layer is 445.6nm, and the thickness of the second material layer is 1439.3nm; in the third photonic crystal structure, the thickness of the first material layer is 205.7nm, and the thickness of the second material layer is 959.6nm; in the fourth photonic crystal structure, the thickness of the first material layer is 102.8nm, and the thickness of the second material layer is 533.1nm; The reflectivity of the heat radiation suppression layer to heat radiation from a heat source reaches more than 90%.

3. A thermal radiation suppression layer, characterized in that: include: Four sequentially stacked photonic crystal structures, each of the photonic crystal structures comprises two sub-periods consisting of a first material layer and a second material layer stacked sequentially, in each of the sub-periods, the direction from the first material layer to the second material layer is the direction from away from the heat source to close to the heat source during use of the thermal radiation suppression layer; the first material layer is germanium, and the second material layer is magnesium fluoride; in a single photonic crystal structure, the thickness of the first material layer in the two sub-periods is the same, and the thickness of the second material layer in the two sub-periods is the same; The direction from the first photonic crystal structure to the fourth photonic crystal structure is the direction from far away from the heat source to close to the heat source during use of the thermal radiation suppression layer; the temperature of the heat source is 1200K; in the first photonic crystal structure, the thickness of the first material layer is 751.4nm, and the thickness of the second material layer is 2303.7nm; in the second photonic crystal structure, the thickness of the first material layer is 382.8nm, and the thickness of the second material layer is 1284.7nm; in the third photonic crystal structure, the thickness of the first material layer is 184.3nm, and the thickness of the second material layer is 841.7nm; in the fourth photonic crystal structure, the thickness of the first material layer is 85.1nm, and the thickness of the second material layer is 487.3nm; The reflectivity of the heat radiation suppression layer to heat radiation from a heat source reaches more than 90%.

4. A thermal radiation suppression layer, characterized in that: include: Four sequentially stacked photonic crystal structures, each of the photonic crystal structures comprises two sub-periods consisting of a first material layer and a second material layer stacked sequentially, in each of the sub-periods, the direction from the first material layer to the second material layer is the direction from away from the heat source to close to the heat source during use of the thermal radiation suppression layer; the first material layer is germanium, and the second material layer is magnesium fluoride; in a single photonic crystal structure, the thickness of the first material layer in the two sub-periods is the same, and the thickness of the second material layer in the two sub-periods is the same; The direction from the first photonic crystal structure to the fourth photonic crystal structure is the direction from far away from the heat source to close to the heat source during use of the thermal radiation suppression layer; the temperature of the heat source is 1400K; in the first photonic crystal structure, the thickness of the first material layer is 677.1nm, and the thickness of the second material layer is 2115.3nm; in the second photonic crystal structure, the thickness of the first material layer is 350.6nm, and the thickness of the second material layer is 1171.0nm; in the third photonic crystal structure, the thickness of the first material layer is 157.2nm, and the thickness of the second material layer is 793.2nm; in the fourth photonic crystal structure, the thickness of the first material layer is 72.5nm, and the thickness of the second material layer is 453.3nm; The reflectivity of the heat radiation suppression layer to heat radiation from a heat source reaches more than 90%.

5. A method for preparing a thermal radiation suppression layer according to any one of claims 1 to 4, characterized in that: The method comprises: The first material layers and the second material layers are alternately formed in sequence to form the first to fourth photonic crystal structures.

6. The method for preparing a thermal radiation suppression layer according to claim 5, characterized in that: The first material layer in the first photonic crystal structure is formed by a first process, and the first material layer in the second photonic crystal structure to the fourth photonic crystal structure is formed by a second process; the second material layer in the first photonic crystal structure and the second photonic crystal structure is formed by a third process, and the second material layer in the third photonic crystal structure and the fourth photonic crystal structure is formed by a fourth process.

7. A thermal management device, characterized in that: A device body and a heat radiation suppression layer according to any one of claims 1 to 4, wherein the heat radiation suppression layer surrounds the device body to suppress the heat generated by the device body from being radiated to the outside of the heat radiation suppression layer or the heat outside of the heat radiation suppression layer from being radiated to the device body.

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