CN118604920A

CN118604920A - Material for inhibiting heat radiation, preparation method and application thereof, and thermal management device

Info

Publication number: CN118604920A
Application number: CN202410635093.9A
Authority: CN
Inventors: 王夏娃; 孙艺心; 周小奇
Original assignee: Duke Kunshan University
Current assignee: Duke Kunshan University
Priority date: 2024-05-22
Filing date: 2024-05-22
Publication date: 2024-09-06

Abstract

The embodiment of the application relates to a material for inhibiting heat radiation, a preparation method and application thereof, and a thermal management device, comprising the following steps: at least two photonic crystal structures stacked in sequence, each photonic crystal structure 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; the thicknesses of the first material layer and the second material layer in different photonic crystal structures are different in the stacking direction of the photonic crystal structures, and the thicknesses of the first material layer and the second material layer in different photonic crystal structures gradually decrease along the direction from a heat source to a heat source in the use process of the material for inhibiting heat radiation; for a 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. This can effectively suppress heat radiation leakage.

Description

Material for inhibiting heat radiation, preparation method and application thereof, and thermal management device

Technical Field

The application relates to the field of heat radiation, in particular to a material for inhibiting heat radiation, a preparation method and application thereof, and a thermal management device.

Background

In the fields of aerospace, nuclear power conversion, thermoelectric conversion and the like, it is important to inhibit heat radiation of an ultra-high temperature heat source from dispersing. In addition, with the improvement and upgrade of more heat-based generators, research on heat radiation suppression of small portable heat generators is also being made. Because of the extremely high temperatures of some heat-based small generators, radiation is the primary heat transport means instead of conduction and convection. Therefore, an effective thermal radiation barrier spanning a small distance is one of the most important components in such systems. The heat radiation inhibiting layer is used for reducing heat radiation loss, so that the utilization rate of radiation heat can be improved, the power generation efficiency is improved, the surface of the generator is close to the room temperature, and the damage to people and the environment is avoided. At present, the high-reflection material coating is covered on the surface of the high-temperature emitter to isolate heat radiation, but the coating can be evaporated and spread at high temperature, so that the effect of the coating for isolating heat radiation is degraded with the passage of time, and the durability is not high. Furthermore, a non-contact housing with a highly reflective metal foil is another way of shielding high temperature heat radiation, whereas conventional refractory metal foils have difficulty achieving a high total reflectivity at the required infrared wavelengths, and the metal itself, due to its high extinction coefficient, absorbs heat causing its own temperature to rise, becoming the heat source itself. While relatively high reflectivity can be achieved with gold, gold is too expensive and malleable to be used as a non-contact housing.

Disclosure of Invention

In view of the above, embodiments of the present application provide a material for suppressing thermal radiation, a method for preparing the same, an application of the same, and a thermal management device for solving at least one of the problems in the background art.

In a first aspect, embodiments of the present application provide a material for inhibiting thermal radiation, comprising:

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 in which the photonic crystal structures are stacked, 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 the thicknesses of the first material layer and the second material layer which are positioned in different photonic crystal structures are gradually reduced along the direction from the heat source to the heat source in the use process of the material for inhibiting heat radiation;

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

With reference to the first aspect of the present application, in an alternative embodiment, the number of photonic crystal structures is greater than or equal to 3.

With reference to the first aspect of the present application, in an alternative embodiment, the number of sub-periods in a single photonic crystal structure is greater than or equal to 2.

With reference to the first aspect of the present application, in an alternative embodiment, in the adjacent photonic crystal structures, a thickness reduction range of one of the first material layer and the second material layer with a higher refractive index is 30% -60%, and a thickness reduction range of one of the first material layer and the second material layer with a lower refractive index is 30% -60%.

In combination with the first aspect of the present application, in an alternative embodiment, a 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.

In combination with the first aspect of the present application, in an alternative embodiment, the material of one of the first material layer and the second material layer comprises magnesium fluoride, and the material of the other comprises germanium.

In a second aspect, embodiments of the present application provide a method for preparing a material for inhibiting thermal radiation, the method comprising:

Sequentially forming first material layers and second material layers which are alternately arranged to form a1 st photonic crystal structure to an n-th 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 of the 1 st to n-th photonic crystal structures includes at least one sub-period composed of the first and second material layers; for the photonic crystal structure including a plurality of the sub-periods, the thicknesses of the first material layers located in different sub-periods are the same, and the thicknesses of the second material layers located in different sub-periods are the same;

From the 1 st photonic crystal structure to the n-th photonic crystal structure, the thicknesses of the first material layers in different photonic crystal structures are different, the thicknesses of the second material layers in different photonic crystal structures are different, and the thicknesses of the first material layers and the second material layers in different photonic crystal structures are gradually reduced.

With reference to the second aspect of the present application, in an alternative embodiment, the first material layers in the 1 st to i st photonic crystal structures are formed by a first process, and the first material layers in the photonic crystal structures except the 1 st to i st photonic crystal structures are formed by a second process, wherein i is 1-n; the second material layers in the 1 st to j th photonic crystal structures are formed by a third process, and the second material layers in the photonic crystal structures except the 1 st to j th photonic crystal structures are formed by a fourth process, wherein j is more than or equal to 1 and less than n; and/or, n is greater than or equal to 3; and/or, the sub-period in a single photonic crystal structure is greater than or equal to 2; and/or in the adjacent photonic crystal structure, the thickness reduction amplitude of one of the first material layer and the second material layer with high refractive index is 30% -60%, and the thickness reduction amplitude of one of the first material layer and the second material layer with low refractive index is 30% -60%; and/or a 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 comprises magnesium fluoride, and the material of the other comprises germanium.

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

A device body;

A heat radiation suppressing layer surrounding the device body to suppress radiation of heat generated by the device body to the outside of the heat radiation suppressing layer or radiation of heat of the outside of the heat radiation suppressing layer to the device body; the material of the thermal radiation inhibiting layer comprises at least one photonic crystal structure, and the photonic crystal structure comprises at least one sub-period formed by sequentially stacking a first material layer and a second material layer; the first material layer and the second material layer have different refractive indices.

In a fourth aspect, embodiments of the present application provide a use of a material for inhibiting thermal radiation according to any one of the first aspects in a thermal management device.

The material for inhibiting heat radiation, the preparation method and the application thereof and the thermal management device provided by the embodiment of the application comprise the following steps: 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; the thicknesses of the first material layers in the different photonic crystal structures are different in the stacking direction of the photonic crystal structures, the thicknesses of the second material layers in the different photonic crystal structures are different, and the thicknesses of the first material layers and the second material layers in the different photonic crystal structures are gradually reduced along the direction from a heat source to a heat source in the use process of the material for inhibiting heat radiation; for the photonic crystal structure including a plurality of the sub-periods, the thicknesses of the first material layers located in different sub-periods are the same, and the thicknesses of the second material layers located in different sub-periods are the same. In the embodiment of the application, 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, so that each photonic crystal structure has different band gaps, and the thicknesses of the first material layers and the second material layers in different photonic crystal structures gradually decrease along the direction from a heat source to a heat source in the use process of the material for inhibiting heat radiation, so that the material for inhibiting heat radiation formed by a plurality of photonic crystal structures which are sequentially stacked has wider band gaps, and the material for inhibiting heat radiation can have stronger inhibition effect on heat radiation (electromagnetic waves) with the frequency within the band gaps, so that the heat radiation cannot pass through the material for inhibiting heat radiation, and the leakage of the heat radiation is effectively inhibited.

Additional aspects and advantages of the application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the application.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute a limitation on the application. In the drawings:

Fig. 1 is a schematic cross-sectional view of a material for suppressing heat radiation according to an embodiment of the present application;

FIG. 2 is a schematic diagram showing the band gap distribution of photonic crystal structures in a thermal radiation spectrum in a material for suppressing thermal radiation according to an embodiment of the present application;

FIG. 3 is a graph showing transmittance of heat radiation through a material for suppressing heat radiation provided in an embodiment of the present application at a heat source temperature of 1200K;

FIG. 4 is a graph of blackbody radiation spectrum and a graph of heat radiation leakage spectrum after heat radiation passes through a material for suppressing heat radiation provided by an embodiment of the present application at a heat source temperature of 1200K;

FIG. 5 is a graph showing the thermal radiation leakage rate of the first material layer and the second material layer under different thickness errors according to an embodiment of the present application;

FIG. 6 is a schematic flow chart of a method for preparing a material for suppressing thermal radiation according to an embodiment of the present application;

fig. 7 is a schematic cross-sectional structure of a material for suppressing heat radiation in a preparation process according to an embodiment of the present application.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the application are shown in the drawings, it should be understood that the application may be embodied in various forms and should not be limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present application. It will be apparent, however, to one skilled in the art that the application may be practiced without one or more of these details. In other instances, well-known features have not been described in detail so as not to obscure the application; that is, not all features of an actual implementation are described in detail herein, and well-known functions and constructions are not described in detail.

In the drawings, the size of layers, regions, elements and their relative sizes may be exaggerated for clarity. Like numbers refer to like elements throughout.

It will be understood that when an element or layer is referred to as being "on" … …, "" adjacent to "… …," "connected to" or "coupled to" another element or layer, it can be directly on, adjacent to, connected to or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on" … …, "" directly adjacent to "… …," "directly connected to" or "directly coupled to" another element or layer, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present application. When a second element, component, region, layer or section is discussed, it does not necessarily mean that the first element, component, region, layer or section is present.

Spatially relative terms, such as "under … …," "under … …," "below," "under … …," "over … …," "above," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use and operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements or features described as "under" or "beneath" other elements would then be oriented "on" the other elements or features. Thus, the exemplary terms "below … …" and "under … …" may include both an upper and a lower orientation. The device may be otherwise oriented (rotated 90 degrees or other orientations) and the spatially relative descriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.

In order to provide a thorough understanding of the present application, detailed steps and detailed structures will be presented in the following description in order to explain the technical solution of the present application. Preferred embodiments of the present application are described in detail below, however, the present application may have other embodiments in addition to these detailed descriptions.

The heat radiation inhibiting layer commonly used in the related art is a multi-layer insulation (MLI) structure, which is widely used for spacecraft and low temperature devices. The multi-layer insulating structure is formed by alternately filling low-heat-conductivity materials serving as gaskets into the middle of a plurality of layers of metal foils with high reflectivity serving as reflecting layers, can reduce the surface thermodynamic temperature while reducing the infrared emissivity, and has extremely low heat conductivity under high vacuum. The molybdenum foil, the gold foil and the titanium foil can be used as high-reflectivity materials in a multi-layer insulating structure, and zirconium oxide, silicon dioxide or ytterbium powder and the like which are low-heat-conductivity materials can be filled between the two reflecting layers. Although the multilayer insulating structure has a certain heat insulation effect, the reflectivity of the single multilayer insulating structure is still not high enough, and the high extinction coefficient of the metal material enables the single multilayer insulating structure to absorb part of heat radiation, so that the temperature is increased, the single multilayer insulating structure becomes an emitter, and the heat radiation insulation effect of the single multilayer insulating structure is further affected.

The omnidirectional reflector (Omnidirectional Reflector, ODR) is composed of alternating material layers with different dielectric constants, and the photonic crystal band gap can be generated by forming a periodic structure by alternating materials with high and low refractive indexes, so that electromagnetic waves with frequencies within the band gap can not propagate in the crystal, and light in a certain wave band can be selectively allowed to pass while light in other wavelengths is prevented from passing. In the related art, an omni-directional reflector is generally applied to a waveguide, a filter, a light emitting diode, etc. at normal temperature for spectrum control, and the omni-directional reflector in the waveguide and the filter has only a narrow band gap. The heat radiation has a wider wave band, and particularly, the wave band coverage range of the heat radiation generated by the heat source is larger along with the temperature rise of the heat source, so that the requirement on the heat radiation shielding material is higher. Because the omnidirectional reflectors in the related art have only a narrow bandwidth, the effect of effective radiation shielding can not be achieved by covering the heat radiation with a wide band, and if the bandwidth is enlarged to be enough by increasing the number of cycles in the photonic crystal, the materials of tens or even hundreds of layers are required to be overlapped, so that the omnidirectional reflectors can not be realized in production and manufacture.

Based on this, the embodiment of the present application provides a material for suppressing heat radiation. As shown in fig. 1, the material for suppressing heat radiation includes:

at least two photonic crystal structures 10 stacked in sequence, each photonic crystal structure 10 including at least one sub-period composed of a first material layer 11 and a second material layer 12 stacked in sequence; the first material layer 11 and the second material layer 12 have different refractive indices;

In the direction in which the photonic crystal structures 10 are stacked, the thicknesses of the first material layers 11 located in different photonic crystal structures 10 are different, and the thicknesses of the second material layers 12 located in different photonic crystal structures 10 are different; and, along the direction from the heat source to the heat source during use of the material for suppressing heat radiation, the thicknesses of the first material layer 11 and the second material layer 12 in the different photonic crystal structures 10 are gradually reduced;

For a photonic crystal structure 10 comprising 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.

It should be noted that the material for suppressing heat radiation may be applied to a thermal management device, for example, the material for suppressing heat radiation may be a material surrounding a device body in the thermal management device during use, the thicknesses of the first material layer and the second material layer in the photonic crystal structure near the heat source in the material for suppressing heat radiation are the thinnest, and thus the thicknesses of the first material layer and the second material layer in the photonic crystal structure far from the heat source are the thickest, and thus the thickness of the photonic crystal structure from the direction far from the heat source to the direction near the heat source in use in which the material for suppressing heat radiation is the thinnest may be considered as a direction from the photonic crystal structure where the thickness of the first material layer and the thickness of the second material layer are the thickest to the direction of the photonic crystal structure where the thickness of the first material layer and the second material layer are the thickest, and the thickness of the first material layer 11 and the second material layer 12 in the different photonic crystal structures 10 may be gradually reduced, for example, or may be a non-linear reduction, such as at least one of an exponential reduction, a logarithmic reduction, a stepwise reduction, and the like.

In the embodiment of the application, the thicknesses of the first material layers 11 located in different photonic crystal structures 10 are different, the thicknesses of the second material layers 12 located in different photonic crystal structures 10 are different, so that each photonic crystal structure 10 has a different band gap, and the thicknesses of the first material layers 11 and the second material layers 12 located in different photonic crystal structures 10 gradually decrease along the direction from far away from the heat source to near the heat source in the use process of the material for inhibiting heat radiation, so that the material for inhibiting heat radiation formed by sequentially stacking a plurality of photonic crystal structures 10 has a wider band gap, and the material for inhibiting heat radiation can generate a stronger inhibition effect on heat radiation (electromagnetic waves) with the frequency within the band gap, so that the heat radiation cannot pass through the material for inhibiting heat radiation, and heat radiation leakage is effectively inhibited.

The material for inhibiting heat radiation in the embodiment of the application realizes a stronger inhibiting effect on heat radiation through at least two photonic crystal structures 10 which are sequentially laminated, is completely different from the inhibiting modes of high-reflection material coatings and multi-layer insulating structures in the related art, and has the advantages of better heat stability, higher durability, lower emissivity, stronger effect on inhibiting heat radiation and lighter weight. Moreover, the material for suppressing thermal radiation in the embodiment of the present application has a wider band gap than the single photonic crystal structure design in the omni-directional reflector in the related art by the design of the thicknesses of the first material layer 11 and the second material layer 12 in the photonic crystal structure 10 and the number of the photonic crystal structures 10, so that it is possible to cover thermal radiation having a wide band to achieve an effective radiation shielding effect, and it is easy to implement in a process.

Illustratively, 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), for example. The extinction coefficients of the materials of the first material layer 11 and the second material layer 12 are close to 0 in the visible light to near infrared band, so that the temperature of the materials for inhibiting heat radiation can be well prevented from rising in the using process. The thicknesses of the first material layer 11 and the second material layer 12 in the photonic crystal structure 10 may be set according to actual requirements, for example, may be set according to the temperature of a heat source of thermal radiation to form a desired band gap range.

Generally, as the temperature of the heat source increases, the wider the band range of the heat radiation generated by the heat source, and as the number of photonic crystal structures 10 increases, the wider the band gap of the material for suppressing the heat radiation, the wider the band of the heat radiation can be covered, so, in some embodiments, referring to fig. 1, the number of photonic crystal structures 10 is greater than or equal to 3. This can suppress heat radiation generated by the high-temperature heat source more effectively. In some embodiments, the number of photonic crystal structures 10 may be 4-5, which may provide for lower cost control while better suppressing thermal radiation.

The number of photonic crystal structures 10 is 4 in fig. 1, and for convenience of description to follow, the photonic crystal structures 10 may be referred to as a first photonic crystal structure, a second photonic crystal structure, a third photonic crystal structure, and a fourth photonic crystal structure in this order in fig. 1.

Referring to fig. 2, the spectrum of thermal radiation generally covers a wide band, and the wavelength corresponding to the maximum of the intensity of the spectral radiation may be referred to as the peak radiation wavelength. Taking the number of photonic crystal structures 10 as 4 as an example (as shown in fig. 1), the thicknesses of the first material layer 11 and the second material layer 12 in the first photonic crystal structure to the fourth photonic crystal structure are gradually reduced, 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 interval (as shown in fig. 2) of the thermal radiation, so that a better reflection effect can be performed on the thermal radiation in the corresponding wavelength range, and thus, after the photonic crystal structures 10 are sequentially laminated, a wider band range of the thermal radiation, particularly a stronger band range of the spectral radiation intensity can be covered, and a stronger inhibition effect can be performed on the thermal radiation. As the temperature of the heat source increases, the wider the band of the heat radiation spectrum is, the greater the total intensity of the spectrum radiation is, and therefore, in the case where the temperature of the heat source is high, more photonic crystal structures 10 may be stacked in order to form a material for suppressing heat radiation having a wider band gap, for example, 5 or more, thereby achieving a better effect of suppressing heat radiation.

The single photonic crystal structure 10 has a better reflection effect on the band of thermal radiation whose band gap can be covered, the greater the number of periods in the single photonic crystal structure 10, the stronger the reflection effect on thermal radiation within a particular band, and thus, in some embodiments, the number of sub-periods in the single photonic crystal structure 10 is greater than or equal to 2. This allows the reflection of the thermal radiation by the photonic crystal structure 10 to be brought to a high level by superposition of a plurality of sub-periods.

In practical applications, the number of sub-periods in a single photonic crystal structure 10 may be set according to the temperature of the heat source of the thermal radiation, the expected reflection effect, the cost, and the like. In addition, the number of sub-periods in different photonic crystal structures 10 may or may not be the same. In some specific embodiments, the number of sub-periods in different photonic crystal structures 10 may be different, as shown in fig. 2, where the spectrum of thermal radiation has a peak radiation wavelength, the spectral radiation intensity is greater at the peak radiation wavelength and the band around the peak radiation wavelength, and the number of sub-periods in the corresponding photonic crystal structure 10 with a band gap covering the peak radiation wavelength and the band around the peak radiation wavelength may be greater than the number of sub-periods in other photonic crystal structures 10 to achieve a better suppression effect on thermal radiation. For example, the test result of suppressing the heat radiation by sequentially stacking the four photonic crystal structures 10 under the condition that the heat source temperature is 1200K shows that the leakage rate of the heat radiation is 6.51% under the shielding of the material for suppressing the heat radiation when the number of the sub-periods in the single photonic crystal structure 10 is 2, the leakage rate of the heat radiation is reduced to 5.49% under the same condition when the number of the sub-periods in the single photonic crystal structure 10 is increased to 3, and the leakage rate of the heat radiation is reduced to 5.43% under the same condition when the number of the sub-periods in the single photonic crystal structure 10 is increased to 4.

In some embodiments, in the adjacent photonic crystal structure 10, the thickness of the one with the higher refractive index of the first material layer 11 and the second material layer 12 is reduced by 30% -60%, for example, may be 35%, 40%, 45%, 50%, 55%, or the like, and the thickness of the one with the lower refractive index is reduced by 30% -60%, for example, may be 35%, 40%, 45%, 50%, 55%, or the like.

As shown in fig. 2, the spectral band of the thermal radiation is continuous, in order to make the material for suppressing the thermal radiation have a better effect on suppressing the thermal radiation, in the embodiment of the present application, in the adjacent photonic crystal structure 10, the thickness of one of the first material layer 11 and the second material layer 12 having a higher refractive index is reduced by 30% to 60%, and the thickness of the other having a lower refractive index is reduced by 30% to 60%, so that the band that can be covered by the band gap of the adjacent photonic crystal structure 10 is continuous, and thus the effect of suppressing the thermal radiation can be better achieved.

It will be appreciated that the bands that the band gaps of adjacent photonic crystal structures 10 can cover may also have a partial overlap, so that the effect of suppressing thermal radiation can be further ensured.

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.

For the 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 refractive index difference between the first material layer 11 and the second material layer 12, the wider the bandgap of the single photonic crystal structure 10 can be made, in this embodiment, 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, so that the bandgap of the single photonic crystal structure 10 can be made wider, and a relatively smaller number of photonic crystal structures 10 can be used to form a material for suppressing heat radiation, relative to the case where the refractive index difference between the first material layer 11 and the second material layer 12 is smaller, so as to achieve substantially the same effect of suppressing heat radiation, thereby making the manufacturing process simplified and cost reduced. In addition, the larger the difference of the refractive indexes of the first material layer 11 and the second material layer 12, the better the reflection effect of the laminated structure of the first material layer 11 and the second material layer 12 on the heat radiation is, so that the thickness of the first material layer 11 and the second material layer 12 can be set to be smaller relatively than the case that the difference of the refractive indexes of the first material layer 11 and the second material layer 12 is smaller, so as to achieve the effect of basically the same heat radiation inhibition, reduce the cost, and make the finally formed material for heat radiation inhibition lighter and thinner, and have wider application range.

In some specific embodiments, the extinction coefficients of the first material layer 11 and the second material layer 12 are each close to 0 in the band of thermal radiation.

The extinction coefficients of the first material layer 11 and the second material layer 12 are close to 0, the absorptivity of the photonic crystal structure 10 to heat radiation is close to 0, the emissivity is equal to the absorptivity according to kirchhoff's law, and the emissivity of the photonic crystal structure 10 is close to 0, so that the material for inhibiting heat radiation can be prevented from becoming an emitter due to the fact that the temperature of the material is increased, and leakage of heat radiation is further reduced.

In some embodiments, the material of one of the first material layer 11 and the second material layer 12 comprises magnesium fluoride, and the material of the other comprises germanium.

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, the extinction coefficients of magnesium fluoride and germanium are close to 0, and the photonic crystal structure 10 can realize better reflection performance for large-angle incident waves. In view of the omnidirectionality of the heat radiation, it is thus possible to make the material for suppressing the heat radiation effectively suppress the heat radiation leakage in a wide band. In addition, the magnesium fluoride and the germanium have good high temperature resistance, so that the material for inhibiting heat radiation has good heat stability, and can be applied to heat radiation of a high-temperature heat source, for example, the heat source temperature is greater than or equal to 1000K.

The performance of the material for suppressing heat radiation in the above-described embodiment was tested, in which the temperature of the heat source, the sub-period setting in the photonic crystal structure 10, and the heat radiation leakage rate are referred to in table 1.

The number of photonic crystal structures 10 in the material for suppressing heat radiation is 4, the number of sub-periods in the single photonic crystal structure 10 is 2, and only the material composition and thickness of a single sub-period in the single photonic crystal structure 10 are shown in table 1. In the test, the fourth photonic crystal structure is close to the heat source and is not in contact with the heat source, and the heat radiation is incident to the surface of the fourth photonic crystal structure.

TABLE 1

As can be seen from table 1, from the first photonic crystal structure to the fourth photonic crystal structure, the thickness of MgF ₂ is gradually reduced, and the thickness of Ge is also gradually reduced, so that the material for suppressing thermal radiation formed by sequentially stacking a plurality of photonic crystal structures has a wide band gap, and under the condition that the temperature of the heat source is greater than or equal to 800K, the thermal radiation leakage rate is less than 10% under the shielding of the material for suppressing thermal radiation, that is, the reflectivity of the material for suppressing thermal radiation to thermal radiation reaches more than 90%.

Fig. 3 is a transmittance curve of heat radiation passing through a material for suppressing heat radiation at a heat source temperature of 1200K, and fig. 4 is a blackbody radiation spectrum and a heat radiation leakage spectrum of heat radiation passing through a material for suppressing heat radiation at a heat source temperature of 1200K. As shown in the black body radiation spectrum diagram in fig. 4, under the condition of 1200K, the wavelength range of the thermal radiation is mainly between 0 μm and 20 μm, the spectral radiation intensity is close to 0 in a partial wave band with the wavelength close to 0, the spectral radiation intensity is smaller in a wave band with the wavelength larger than 10 μm, especially in a wave band with the wavelength larger than 15 μm, the spectral radiation intensity is gradually close to 0, and referring to fig. 3, since the band gaps of the first photonic crystal structure to the fourth photonic crystal structure cover most wave bands of the thermal radiation, especially the wave bands with the larger spectral radiation intensity, the thermal radiation transmittance of the corresponding wave band is lower, the spectral radiation intensity corresponding to the wave bands which are not covered by the band gaps of the first photonic crystal structure to the fourth photonic crystal structure is smaller, even if the transmittance of the thermal radiation of the corresponding wave band is higher, the effect on the overall thermal radiation leakage rate is very low after the reflection of the first photonic crystal structure to the fourth photonic crystal structure is shown in the thermal radiation leakage spectrum in fig. 4. Therefore, the material for suppressing heat radiation constituted by 4 to 5 photonic crystal structures can be controlled at a low level while having a good heat radiation suppressing effect in consideration of the manufacturing cost. The specific data shows that for a 1200K heat source, the band gap range of the material used for suppressing heat radiation can be close to 99% (0-20 μm) of its heat radiation intensity, and the heat radiation leakage rate is only 6.51%.

From the above, the material for inhibiting heat radiation in the application has wide band gap, high temperature resistance, can be applied to heat sources above 800K, has high reflectivity (more than 90%) no matter the angle and polarization form of incident waves, and can establish effective heat radiation barriers. The thickness of the material layer in the sub-period in the 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 the wien's law of displacement, the peak radiation wavelength of the heat radiation is inversely proportional to the temperature of the heat source, i.e. the higher the temperature, the shorter the peak radiation wavelength, i.e. the band with higher spectral radiation intensity will shift to the left as the temperature of the heat source increases. As the data in table 1 show, as the temperature of the heat source increases, the thicknesses of the first material layer 11 and the second material layer 12 in the sub-period in the single photonic crystal structure 10 may be gradually reduced, and the thinner photonic crystal structure 10 may cover a shorter wavelength band, the material for suppressing heat radiation in the embodiment of the present application is very suitable for suppressing heat radiation of a high temperature heat source. The material for inhibiting heat radiation, which is formed by the four photonic crystal structures 10 of the 1200K heat source, has the total thickness of less than 13 mu m, has the advantage of light weight and thinness, and can be better applied to various portable small heat sources of deep space and deep sea exploration equipment. For the multilayer insulation structure in the relative technology, if the heat radiation shielding efficiency of the multilayer insulation structure is required to be improved, the number of layers of the multilayer insulation structure is required to be increased, and the total thickness of the multilayer insulation structure reaches the centimeter-level or even decimeter-level thickness due to the large volume and weight of the metal foil and the powder material, so that the material for inhibiting heat radiation has remarkable advantages.

In view of the processing precision problem in the actual process, certain thickness errors of the first material layer 11 and the second material layer 12 in the material for suppressing heat radiation, that is, variations in material thickness and reflectivity due to process limitations, occur during the manufacturing process, in order to verify the effect of possible errors of the first material layer 11 and the second material layer 12 in the process on the material performance for suppressing heat radiation, a Monte Carlo (Monte Carlo) method is adopted, the relative thickness uncertainty of the first material layer 11 and the second material layer 12 is introduced according to a fixed gaussian standard deviation, and the result is resolved into a material design for a 1200K heat source in table 1. For each standard deviation, the simulation was run 10 ten thousand times, and the results are shown in fig. 5. The smaller the process error, the closer the heat radiation leak rate is to the optimum value and the narrower the distribution. A relatively small process error (e.g., 5%) will concentrate the average value of the heat radiation leak rate around 6.84%, and as the process error is larger, the heat radiation leak rate will also increase. However, even when the process error is as high as 13%, the average heat radiation leakage rate is still lower than 8%, which indicates that the shielding effect of the material for suppressing heat radiation in the present application is still good in the case where the process error is large. The change in optical constants of the materials was also simulated, and the difference in reflectivity of the first material layer 11 and the second material layer 12 was increased to about 3% -5% by using some optical constants at high temperature in consideration of potential temperature rise of the first material layer 11 and the second material layer 12, and as a result, the heat radiation leakage rate was slightly increased from 6.51% to 7.48%. It is clear from this that the material for suppressing heat radiation in the present application has a good tolerance (a level of accommodating process errors). The material for suppressing heat radiation in the present application is easy to realize in terms of process in consideration of the tolerance (error) of about 9% of the process typically used for forming the first material layer 11 and the second material layer 12, such as sputtering, optical plating, and the like.

Based on the above, the embodiment of the application provides a preparation method of a material for inhibiting heat radiation. FIG. 6 is a schematic flow chart of a method for preparing a material for suppressing thermal radiation according to an embodiment of the present application; as shown in fig. 6, the method includes:

Step S101, sequentially forming a first material layer and a second material layer which are alternately arranged to form a1 st photonic crystal structure to an n-th 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 of the 1 st to nth photonic crystal structures includes at least one sub-period composed of a first material layer and a second material layer; for a photonic crystal structure comprising 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; the thicknesses of the first material layers in the different photonic crystal structures are different from the 1 st photonic crystal structure to the n-th photonic crystal structure, the thicknesses of the second material layers in the different photonic crystal structures are different, and the thicknesses of the first material layers and the second material layers in the different photonic crystal structures are gradually reduced.

It can be understood that in the 1 st to n th photonic crystal structures formed by the above method, the thicknesses of the first material layers located in different photonic crystal structures are different, and the thicknesses of the second material layers located in different photonic crystal structures are different, so that each photonic crystal structure has a different band gap, and the thicknesses of the first material layers and the second material layers located in different photonic crystal structures gradually decrease along the direction from the heat source to the heat source in the use process of the material for inhibiting heat radiation, so that the material for inhibiting heat radiation formed by sequentially stacking a plurality of photonic crystal structures has a wider band gap, and thus a stronger reflection effect can be generated on heat radiation, and heat radiation leakage is effectively inhibited.

The preparation method and the beneficial effects of the material for inhibiting heat radiation provided in the embodiment of the application are described in further detail below with reference to fig. 7.

First, referring to fig. 7, step S101 is performed to sequentially form the first material layers 11 and the second material layers 12 alternately arranged to form the 1 st to n-th photonic crystal structures 101 to 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 of the 1 st to n-th photonic crystal structures 101 to 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 thicknesses of the first material layers 11 located in different sub-periods are the same, and the thicknesses of the second material layers 12 located in different sub-periods are the same; from the 1 st photonic crystal structure 101 to the n-th photonic crystal structure 104, the thicknesses of the first material layers 11 located in the different photonic crystal structures are different, the thicknesses of the second material layers 12 located in the different photonic crystal structures are different, and the thicknesses of the first material layers 11 and the second material layers 12 located in the different photonic crystal structures are each gradually reduced.

Illustratively, the first material layer 11 and the second material layer 12 may be formed using at least one of magnetron sputtering, electron beam evaporation, chemical vapor deposition, physical vapor deposition, atomic layer deposition, sol-gel process, electrochemical deposition, optical plating, laser chemical vapor deposition process, etc., wherein 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, lithium fluoride, for example, and the material of the other may include at least one of germanium, silicon nitride, gallium indium phosphorus (GaInP), aluminum indium phosphorus (AlInP), for example.

In some embodiments, the first material layers 11 and the second material layers 12 alternately arranged may be sequentially formed on a substrate (not shown) to form the 1 st to nth photonic crystal structures 101 to 104 described above.

Here, the material of the substrate may include, for example, any material capable of growing the first material layer 11, for example, at least one of silicon, germanium, tantalum, or the like, and generally, the first material layer 11 has good adhesion with the substrate.

In some embodiments, the first material layer 11 in the 1 st to i st photonic crystal structures 101 to 102 is formed using a first process, and the first material layer 11 in the photonic crystal structures other than the 1 st to i st photonic crystal structures 101 to 102 is formed using a second process, 1.ltoreq.i < n; the second material layer 12 in the 1 st to j-th photonic crystal structures 101 to 103 is formed by a third process, and the second material layer 12 in the other photonic crystal structures except the 1 st to j-th photonic crystal structures 101 to 103 is formed by a fourth process, wherein j is 1-n.

In the embodiment of the application, from the 1 st photonic crystal structure 101 to the n-th photonic crystal structure 104, the thicknesses of the first material layers 11 located in different photonic crystal structures are different, the thicknesses of the second material layers 12 located in different photonic crystal structures are different, and the thicknesses of the first material layers 11 and the second material layers 12 located in different photonic crystal structures are gradually reduced, so that the first material layers 11 and the second material layers 12 with different thicknesses can be formed by adopting different processes, and by selecting proper processes, the errors of the formed first material layers 11 and second material layers 12 in thickness are reduced, the process accuracy is improved, and the performance of the prepared material for inhibiting heat radiation is further improved.

It should be noted that, in fig. 7, the positions of the ith photonic crystal structure 102 and the jth photonic crystal structure 103 are only examples, and 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.

Illustratively, taking n as 4, i as 1, and j as 2 as an example, the first material layer 11 (more specifically, germanium, for example) in the 1 st photonic crystal structure 101 may be formed using a magnetron sputtering process, the first material layers 11 (more specifically, germanium, for example) in the 2nd to 4 th photonic crystal structures may be formed using an electron beam evaporation process, that is, relatively thin germanium may be formed using an electron beam evaporation process, and relatively thick germanium may be formed using a magnetron sputtering process; the second material layer 12 (more specifically, for example, magnesium fluoride) in the 1 st and 2nd photonic crystal structures 101 and 12 may be formed using, for example, a chemical vapor deposition process, the second material layer 12 (more specifically, for example, magnesium fluoride) in the 3 rd and 4 th photonic crystal structures may be formed using an electron beam evaporation process, that is, relatively thin magnesium fluoride may be formed using an electron beam evaporation process, and relatively thick magnesium fluoride may be formed using a chemical vapor deposition process, thereby reducing errors in thickness of the first and second material layers 11 and 12 and improving process accuracy.

In some embodiments, n is greater than or equal to 3. The larger the number of photonic crystal structures in the material for suppressing heat radiation, the wider the band gap, the wider the band of heat radiation that can be covered, so that heat radiation generated by a high-temperature heat source can be suppressed better. In some embodiments, n may be 4-5, which may provide for lower cost control while better suppressing thermal emissions.

In some embodiments, the sub-period in a single photonic crystal structure is greater than or equal to 2. The superposition of a plurality of subcycles can lead to a higher level of the reflection effect of the photonic crystal structure on the heat radiation.

In some embodiments, in the adjacent photonic crystal structure, the thickness of the one with the higher refractive index of the first material layer 11 and the second material layer 12 is reduced by 30% -60%, for example, may be 35%, 40%, 45%, 50%, 55%, or the like, and the thickness of the one with the lower refractive index is reduced by 30% -60%, for example, may be 35%, 40%, 45%, 50%, 55%, or the like. Therefore, the band gap of the adjacent photonic crystal structure can cover the continuous wave band, and the effect of better inhibiting heat radiation can be achieved.

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. Therefore, the band gap of the single photonic crystal structure is wider, and the effect of better inhibiting heat radiation can be achieved.

Based on this, an embodiment of the present application provides a thermal management device including:

A device body;

Thermal management devices in embodiments of the application may include, for example, heat-to-electricity conversion devices (e.g., nuclear batteries, fuel cells, microturbines, stirling generators, alkali metal fluid cells, etc.), devices for insulating heat sources (aircraft protection devices, etc.). The material of the thermal radiation inhibiting layer comprises at least one photonic crystal structure, so that the thermal radiation inhibiting layer can generate better reflection effect on thermal radiation, and thus the thermal radiation generated by a heat source can be effectively inhibited.

Based on this, an embodiment of the present application provides another thermal management device, including:

A device body;

A heat radiation suppressing layer surrounding the device body to suppress radiation of heat generated by the device body to the outside of the heat radiation suppressing layer or radiation of heat of the outside of the heat radiation suppressing layer to the device body; the material of the heat radiation inhibiting layer includes the material for inhibiting heat radiation described in any of the foregoing embodiments.

The thermal management device in the embodiments of the present application may be understood with reference to the thermal management device in the above-described embodiments. Since the material for the thermal radiation inhibiting layer in the embodiment of the present application includes the material for inhibiting thermal radiation described in any of the foregoing embodiments, the material for inhibiting thermal radiation described in any of the foregoing embodiments has the beneficial effects that it is applicable to the thermal radiation inhibiting layer in the embodiment of the present application, and the thermal radiation inhibiting layer can also better inhibit thermal radiation generated by a heat source.

Based on the above, the embodiment of the application provides an application of a material for inhibiting heat radiation in a thermal management device, wherein the material for inhibiting heat radiation comprises at least one photonic crystal structure, and the photonic crystal structure comprises at least one sub-period formed by sequentially stacking a first material layer and a second material layer; the first material layer and the second material layer have different refractive indices.

Based on this, the embodiment of the present application further provides a use of the material for suppressing thermal radiation as described in any of the previous embodiments in a thermal management device.

It should be noted that, the material embodiment for suppressing heat radiation, the preparation method embodiment of the material for suppressing heat radiation, the application embodiment of the material for suppressing heat radiation, and the thermal management device embodiment provided by the application belong to the same concept; the features of the embodiments described in the present application may be combined arbitrarily without any conflict. However, it should be further described that the material for suppressing heat radiation provided by the embodiment of the present application has various technical feature combinations that can solve the technical problems to be solved by the present application; thus, the material for suppressing heat radiation provided by the embodiment of the present application may not be limited by the method for preparing a material for suppressing heat radiation provided by the embodiment of the present application, and any material for suppressing heat radiation prepared by the method for preparing a material for suppressing heat radiation provided by the embodiment of the present application can be formed within the scope of protection of the present application.

It should be understood that the above examples are illustrative and are not intended to encompass all possible implementations encompassed by the claims. Various modifications and changes may be made in the above embodiments without departing from the scope of the disclosure. Likewise, the individual features of the above embodiments can also be combined arbitrarily to form further embodiments of the application which may not be explicitly described. Therefore, the above examples merely represent several embodiments of the present application and do not limit the scope of protection of the patent of the present application.

Claims

1. A material for suppressing thermal radiation, comprising:

2. The material for suppressing thermal radiation of claim 1, wherein the number of photonic crystal structures is greater than or equal to 3.

3. The material for suppressing thermal radiation according to claim 1 or 2, wherein the number of the sub-periods in a single photonic crystal structure is greater than or equal to 2.

4. The material for suppressing thermal radiation according to claim 1 or 2, wherein in the adjacent photonic crystal structure, the thickness reduction of one of the first material layer and the second material layer, which is higher in refractive index, is 30% -60%, and the thickness reduction of the one, which is lower in refractive index, is 30% -60%.

5. The material for suppressing thermal radiation as defined in claim 1, wherein a 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.

6. The material for suppressing thermal radiation as defined in claim 5, wherein the material of one of said first material layer and said second material layer comprises magnesium fluoride and the material of the other comprises germanium.

7. A method of preparing a material for inhibiting thermal radiation, the method comprising:

8. The method for producing a material for suppressing heat radiation as defined in claim 7, wherein the first material layer in the 1 st to i-th photonic crystal structures is formed by a first process, the first material layer in the photonic crystal structures other than the 1 st to i-th photonic crystal structures is formed by a second process, 1.ltoreq.i < n; the second material layers in the 1 st to j th photonic crystal structures are formed by a third process, and the second material layers in the photonic crystal structures except the 1 st to j th photonic crystal structures are formed by a fourth process, wherein j is more than or equal to 1 and less than n; and/or, n is greater than or equal to 3; and/or, the sub-period in a single photonic crystal structure is greater than or equal to 2; and/or in the adjacent photonic crystal structure, the thickness reduction amplitude of one of the first material layer and the second material layer with high refractive index is 30% -60%, and the thickness reduction amplitude of one of the first material layer and the second material layer with low refractive index is 30% -60%; and/or a 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 comprises magnesium fluoride, and the material of the other comprises germanium.

9. A thermal management device, comprising:

A device body;

10. Use of a material for suppressing thermal radiation as claimed in any one of claims 1 to 6 in a thermal management device.