Reflection-heat insulation dual-functional aluminum oxide ceramic as well as preparation method and application thereof

Abstract

The invention discloses reflection-heat insulation dual-functional aluminum oxide ceramic and a preparation method and application thereof.The method comprises the steps that after surface silanization treatment is conducted on nanoscale hollow oxide filler, surface-modified nanoscale hollow oxide filler is prepared; and then adding the surface-modified nanoscale hollow oxide filler into a high-molecular polymer and a mixed polar solvent to obtain the thermal insulation coating. The method comprises the following steps: coating the surface of aluminum oxide ceramic with a heat insulation coating to form a primary coating, and carrying out gradient heating curing to obtain aluminum oxide ceramic with a functionalized heat insulation coating; and coating the surface of the thermal insulation coating functionalized aluminum oxide ceramic with an infrared reflection coating, and carrying out annealing treatment in a nitrogen atmosphere to prepare the reflection-thermal insulation dual-functionalized aluminum oxide ceramic. By constructing a double-layer composite structure, enhancing interface thermal resistance through chemical bonding, directionally distributing the nanofiller and designing a low-radiation layer structure, heat conduction and radiation heat transfer of the aluminum oxide ceramic-based material are synergistically reduced, and the high-temperature heat insulation performance of the aluminum oxide ceramic-based material is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional coatings, and relates to a reflection-insulation dual-functional alumina ceramic, a preparation method thereof, and an application thereof. Background Art

[0002] With the continuous advancement of the industrialization process, higher and higher requirements are put forward for the thermal management performance of materials in high-temperature application fields such as aerospace, electronic devices, and heat exchange systems. Alumina ceramic (Al2O3 ceramic), as an advanced ceramic material prepared from bauxite by high-temperature sintering, exhibits extensive application potential in high-temperature environments by virtue of its excellent physical, chemical, and mechanical properties, as well as good electrical insulation characteristics. For example, it can be used as a thermal insulation material, a packaging material for electronic devices, and a thermal shielding material. In these applications, alumina ceramic needs to exhibit excellent heat insulation and heat preservation effects to effectively prevent heat dissipation or avoid rapid temperature changes, thereby ensuring the stable operation of the device and the efficient utilization of energy.

[0003] However, the inherently high thermal conductivity (about 30 W / m·K) of Al2O3 ceramic-based materials severely restricts their further application in the field of high-efficiency heat insulation. Although high thermal conductivity is beneficial for rapid heat conduction in certain scenarios, it becomes a significant shortcoming in occasions where heat insulation and heat preservation are required, resulting in easy heat dissipation or difficult precise temperature control. In addition, Al2O3 ceramic-based materials have a relatively high mid-infrared radiation transmittance at high temperatures, which allows heat to penetrate the material in the form of radiation, further weakening their heat insulation performance. These limitations pose significant challenges to the application of Al2O3 ceramic-based materials in high-temperature heat insulation. Therefore, improving the heat insulation performance of Al2O3 ceramic-based materials is not only an important research direction in the field of materials science but also an urgent requirement to meet the high-efficiency thermal management needs of high-temperature application fields such as aerospace, electronic devices, and energy utilization. By optimizing the performance, the application range of alumina ceramic in high-temperature environments will be broadened, providing key material support for the technological progress of fields such as aerospace, electronic devices, and energy utilization, and at the same time promoting the innovative development of high-temperature thermal management technology.

[0004] In the prior art, although pure polymer coatings have certain heat insulation performance, their heat resistance is poor and it is difficult to be stably used in high-temperature environments for a long time; while pure ceramic coatings have excellent high-temperature resistance, but are prone to cracking due to their large brittleness, affecting their service life. In addition, the dispersion of traditional fillers in the coating is poor, and it is difficult to form a uniform organic / inorganic interface, resulting in insufficient improvement of the interfacial thermal resistance (Kapitza thermal resistance) and inability to effectively block heat conduction. At the same time, the existing coating designs often do not optimize for the relatively high mid-infrared radiation transmittance of Al2O3 ceramic-based materials, lack high-reflection functions, and cannot effectively inhibit heat radiation heat transfer, resulting in limited overall heat insulation efficiency. Summary of the Invention

[0005] In view of the problems existing in the prior art, the present invention provides a reflection-thermal insulation dual-functional alumina ceramic, its preparation method and application, so as to solve the technical problem of poor thermal insulation effect of ceramic-based materials in the prior art.

[0006] The present invention is realized through the following technical solutions:

[0007] A preparation method of a reflection-thermal insulation dual-functional alumina ceramic, comprising the following steps:

[0008] S1: Perform low-temperature plasma treatment on the nano-scale hollow oxide filler, and then add the treated nano-scale hollow oxide filler into a mixed solution of an organic solvent and a silane coupling agent, and stir and react to obtain a surface-modified nano-scale hollow oxide filler;

[0009] S2: Add the surface-modified nano-scale hollow oxide filler into a polymer and a mixed polar solvent, and perform ultrasonic treatment to obtain a heat-insulating and heat-preserving coating; the mixed polar solvent includes a first polar solvent and a second polar solvent; the boiling point of the first polar solvent is greater than that of the second polar solvent;

[0010] S3: Coat the heat-insulating and heat-preserving coating on the surface of the alumina ceramic to form a preliminary coating, and cure the coating through a gradient temperature-rising curing process to obtain an alumina ceramic with a heat-insulating coating function;

[0011] S4: Coat an infrared reflection coating on the surface of the alumina ceramic with a heat-insulating coating function, and perform annealing treatment in a nitrogen atmosphere to obtain the reflection-thermal insulation dual-functional alumina ceramic.

[0012] Preferably, by mass, the ratio of the nano-scale hollow oxide filler to the silane coupling agent is (33-105):(0.99-5.25).

[0013] Preferably, the nano-scale hollow oxide is one or more of hollow silica, hollow zirconia, hollow vanadium dioxide, and hollow mesoporous titanium oxide.

[0014] Preferably, by mass, the ratio of the nano-scale hollow oxide filler to the polymer and the mixed polar solvent is (33-105):(10-20):(66-100); by mass, the ratio of the first polar solvent to the second polar solvent is (8-6):(2-4).

[0015] Preferably, the polymer is at least one of polyimide, polyphenylene sulfide, and polyether ether ketone.

[0016] Preferably, in step S3, the gradient temperature rise curing process is specifically as follows: reacting at 80 - 120°C for 1 h, reacting at 150 - 220°C for 1 h, and reacting at 300 - 360°C for 1 h.

[0017] Preferably, in step S4, the preparation process of the infrared reflective coating is as follows: by mass, dissolve 10 - 20 parts of a high molecular polymer in 66 - 100 parts of a third polar solvent, then successively add 10 - 40 parts of an infrared reflective filler and polyvinylpyrrolidone, and after ultrasonic treatment, obtain the infrared reflective coating; the mass of the polyvinylpyrrolidone accounts for 0.5% - 2% of the total mass of the high molecular polymer, the third polar solvent, and the infrared reflective filler.

[0018] Preferably, in step S4, the annealing treatment is specifically as follows: heat preservation at 200 - 400°C for 1 - 2 h.

[0019] A reflection - heat insulation dual - functionalized alumina ceramic is prepared by the above - mentioned method; the reflectivity of the reflection - heat insulation dual - functionalized alumina ceramic to infrared radiation is greater than 85%, and the thermal conductivity of the reflection - heat insulation dual - functionalized alumina ceramic is not greater than 0.15 W / m·K.

[0020] The application of the above - mentioned reflection - heat insulation dual - functionalized alumina ceramic in the preparation of heat insulation devices.

[0021] Compared with the prior art, the present invention has the following beneficial technical effects:

[0022] The present invention discloses a preparation method of a reflection-thermal insulation dual-functional alumina ceramic. First, the present invention uses low-temperature plasma technology to perform surface hydroxyl activation on nano-sized hollow oxide fillers, enhance the surface hydroxyl density, effectively achieve the combination with silane coupling agents, enhance the interfacial bonding force, and improve the dispersion stability of nano-sized hollow oxide fillers in polymer matrices. The nano-sized hollow oxide fillers can utilize their hollow structures to form a large number of gas-solid interfaces in the matrix, increase the interfacial thermal resistance (Kapitza), and inhibit heat conduction. Then, the evaporation rate of the solvent is regulated by polar solvents with different boiling points to achieve a gradient distribution of nano-fillers in the coating during the drying process of the coating. Specifically, by utilizing the miscibility of different polar solvents and the difference in their evaporation rates, the fillers are driven to migrate directionally in the coating. The highly volatile solvent evaporates rapidly from the surface layer of the solution, resulting in a rapid increase in the surface viscosity and forming a "surface shell layer", which restricts the upward diffusion of the fillers. The low-volatile solvent remains in the bottom of the coating for a longer time, prolongs the sedimentation time of the fillers, and promotes the enrichment of the fillers at the bottom. During this process, the nano-fillers settle to the bottom under the action of gravity, while the smaller particles remain suspended due to Brownian motion, finally forming a gradient distribution structure with a high concentration at the bottom and a low concentration at the top. This structure effectively improves the thermal insulation effect. An infrared reflection coating is continuously constructed on top of this coating to form a reflection-thermal insulation dual-functional coating, effectively improving the infrared reflection effect of the coating and enhancing the thermal insulation effect. The preparation method of the present invention constructs a double-layer composite structure, enhances the interfacial thermal resistance through chemical bonding, the directional distribution of nano-fillers, and the design of the low-emissivity layer structure, and synergistically reduces the heat conduction and radiative heat transfer of the alumina ceramic-based material, improving its high-temperature thermal insulation performance. Description of the Drawings

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0024] Figure 1 Thermal conductivity of the reflection-thermal insulation coatings prepared in Example 1 and Example 2 of the present invention;

[0025] Figure 2 Infrared thermal imaging comparison diagrams of the nano-sized hollow oxide fillers before and after modification in Example 3 of the present invention;

[0026] Figure 3 Temperature change curve diagram of the reflection-thermal insulation coating prepared in Example 4 of the present invention. Detailed Description of the Invention

[0027] To enable those skilled in the art to understand the features and effects of the present invention, the following is a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein shall have the ordinary meaning understood by those skilled in the art with respect to the present invention. In case of conflict, the definition in this specification shall prevail.

[0028] The theories or mechanisms described and disclosed herein, whether right or wrong, shall not limit the scope of the present invention in any way, that is, the content of the present invention can be implemented without being limited by any specific theory or mechanism.

[0029] In this article, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are only for the sake of brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be regarded as having covered and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0030] In this article, unless otherwise specified, the terms "comprising", "including", "containing", "having", or similar terms cover the meanings of "consisting of" and "consisting essentially of". For example, "A comprises a" covers the meanings of "A comprises a and others" and "A consists only of a".

[0031] In this article, for the sake of brevity of description, all possible combinations of all technical features in each embodiment or example are not described. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered as within the scope described in this specification.

[0032] The present invention provides a method for preparing a reflection-thermal insulation dual-functional alumina ceramic, comprising the following steps:

[0033] S1: By mass, 33-105 parts of nano-sized hollow oxide fillers are subjected to low-temperature plasma treatment at a power of 100 W for 30 min, and then added to a mixed solution of 330-1050 parts of a solvent and 0.99-5.25 parts of a silane coupling agent, and reacted at 80 °C for 4-6 h to obtain surface-modified nano-sized hollow oxide fillers, and this surface modification process enhances the interfacial compatibility between the nano-sized hollow oxide fillers and the polymer matrix;

[0034] Wherein the solvent can be one or more of ethanol, toluene, and N,N-dimethylformamide.

[0035] The nano-sized hollow oxide filler is one or more of hollow silica, hollow zirconia, hollow vanadium dioxide, and hollow mesoporous titanium oxide, and the nano-sized hollow oxide filler is purchased from Yumu New Materials, Shandong Leibao Zirconium Industry Co., Ltd., Yuanying New Materials, and Nanjing Jike Biotechnology Co., Ltd.

[0036] The silane coupling agent is one or more of KH550, KH560, KH845-4, KH570, and KH792.

[0037] S2: Add the surface-modified nano-sized hollow oxide filler to 10 - 20 parts of the polymer and 66 - 100 parts of the mixed polar solvent, and perform ultrasonic treatment for 30 - 60 min to obtain the heat-insulating and heat-preserving coating.

[0038] The polymer is one or more of polyimide, polyphenylene sulfide, and polyether ether ketone.

[0039] The mixed polar solvent includes a first polar solvent and a second polar solvent.

[0040] The first polar solvent is at least one of dimethyl sulfoxide, N-methylpyrrolidone, and N,N-dimethylacetamide.

[0041] The second polar solvent is one of acetone, ethanol, and N,N-dimethylformamide.

[0042] The boiling point of the first polar solvent is greater than that of the second polar solvent.

[0043] By mass, the ratio of the first polar solvent to the second polar solvent is (8 - 6):(2 - 4).

[0044] S3: Adopt the spraying or spin-coating process to apply the heat-insulating and heat-preserving coating on the surface of the alumina ceramic to form a preliminary coating, and through the gradient temperature rising and curing process, gradually increase the temperature to cure the coating to obtain the alumina ceramic functionalized with a heat-insulating coating. The thickness of the heat-insulating coating on the alumina ceramic functionalized with the heat-insulating coating is 10 - 100 μm.

[0045] Gradient temperature rising can eliminate internal stress and form a dense structure, thus ensuring that the coating has excellent mechanical properties and heat-insulating effect.

[0046] When adopting the spraying process, the air pressure is 0.3 - 0.5 MPa.

[0047] When adopting the spin-coating process, the rotation speed is 500 - 4000 rpm.

[0048] The specific gradient temperature curing process is as follows: reacting at 80 - 120°C for 1 h, reacting at 150 - 220°C for 1 h, and reacting at 300 - 360°C for 1 h. This gradient temperature curing process is one of the inventive points of the present invention. During this process, the pre-curing volatilizes the remaining solvent and initially fixes the filler distribution. The medium-temperature curing forms a dense layer at the bottom, and the high-temperature curing can shape the loose layer at the top. Due to the significant difference in the thermal expansion coefficients between the polymer and the oxide, if high-temperature curing is directly adopted, it is easy to cause the coating to crack or peel off due to thermal stress concentration. In addition, rapid heating may also cause the solvent to volatilize too quickly, forming bubbles or pores, thus affecting the denseness and uniformity of the coating. Therefore, the present invention adopts a gradient curing process. By gradually increasing the temperature, it realizes the slow release of internal stress, the gradient uniform volatilization of the solvent, the optimization of interface bonding, and the controllability of the cross-linking reaction. This process not only effectively avoids coating cracking and bubble defects, but also significantly improves the denseness, adhesion, and mechanical properties of the coating, becoming one of the key processes for preparing high-performance composite coatings.

[0049] S4: By mass, dissolve 10 - 20 parts of the polymer in 66 - 100 parts of the third polar solvent, and then successively add 10 - 40 parts of the infrared reflection filler and a dispersant (polyvinylpyrrolidone). Among them, the mass of the polyvinylpyrrolidone accounts for 0.5% - 2% of the total mass of the polymer, the third polar solvent, and the infrared reflection filler, and ultrasonically treat for 30 - 60 min to form an infrared reflection coating. Then coat the infrared reflection coating on the surface of the heat-insulating coating-functionalized alumina ceramic. This coating process can use a high-pressure spray gun. Finally, perform annealing treatment under a nitrogen atmosphere protection to effectively eliminate the internal stress in the coating and promote interface bonding, and obtain a reflection-insulation dual-functionalized alumina ceramic. The thickness of the reflection functional layer on this reflection-insulation dual-functionalized alumina ceramic is 1 - 10 μm.

[0050] The infrared reflection filler is tungsten oxide or titanium dioxide.

[0051] The third polar solvent here is N-methylpyrrolidone or N,N-dimethylacetamide.

[0052] The above-mentioned annealing treatment is another inventive point of the present invention. During the preparation process, the coating may generate internal stress due to rapid cooling or solvent volatilization, causing the coating to crack or peel off; microscopic pores or defects may be introduced during the spraying process, affecting its density and mechanical properties; when the interface bonding force between the coating and the substrate is weak, it is easy to peel off under high temperature or thermal shock conditions; unannealed coatings may cause infrared reflectivity or thermal insulation performance to fail to meet the standards due to structural defects or interface problems. Annealing process, as a heat treatment method to improve material properties by heating and slow cooling, can effectively solve the above problems. Through annealing treatment, the internal stress of the coating is slowly released, stress concentration is avoided, the bonding force between the coating and the substrate is enhanced, the coating material particles are sintered, the pores are filled, and a dense structure is formed, thereby improving the mechanical strength and thermal insulation performance of the coating, while improving the overall functional characteristics, so that the coating can maintain its structural integrity and functional performance in a high temperature environment.

[0053] The invention discloses a method for preparing a reflective-heat-insulating dual-functionalized alumina ceramic, which achieves an optimized balance between high-efficiency heat insulation and high-temperature resistance through material optimization and structural design innovation.

[0054] First, in terms of material selection, special engineering materials are used as polymer substrates. These materials have excellent high temperature resistance and high strength, can meet the needs of extreme working conditions, and effectively solve the problem that traditional materials (such as polyethylene, epoxy resin) cannot be used due to poor temperature resistance or high brittleness. At the same time, hollow oxide fillers with low thermal conductivity, high melting point and low cost are selected, and their hollow structure is used to form a large number of gas-solid interfaces in the matrix, further increasing the interfacial thermal resistance (Kapitza) and inhibiting heat conduction. The outer layer uses tungsten oxide or titanium dioxide as mid-infrared high-reflection materials. These materials have the advantages of high infrared reflectivity, high temperature stability and versatility and are not easy to oxidize. They can form an efficient reflection layer for mid- and far-infrared waves (2 to 14 μm), and the measured infrared reflectivity is more than 85%, which is about 40% higher than the traditional metal reflection layer.

[0055] In terms of the preparation process, first, low-temperature plasma is used to activate the surface hydroxyl groups of the selected nano-sized hollow oxide fillers. This can not only enhance the surface hydroxyl density, providing sufficient active sites for subsequent coupling reactions, but also enhance the interfacial binding force and improve the dispersion stability. Subsequently, a silane coupling agent is used to modify the surface of the hydroxyl-activated nano-oxides, and a uniform composite solution (dispersion degree > 98%) is formed with the polymer matrix through ultrasonic dispersion. Through the directional design of coupling agents for different special polymer matrices, covalent bonding between the hollow oxide fillers and polyimide, polyphenylene sulfide, or polyether ether ketone is achieved, significantly improving the interfacial thermal resistance. This method has the advantages of simple process and low cost, avoiding the stringent requirements of complex processes such as chemical vapor deposition for equipment and the environment, and at the same time solving the problem of easy agglomeration of fillers caused by traditional mechanical mixing. The dense organic / inorganic heterogeneous interface formed by this method can significantly increase the Kapitza thermal resistance, reducing the room-temperature thermal conductivity of the bottom composite layer to 0.12 W / (m·K), a 72% reduction compared to the pure polymer matrix, and still maintaining an ultra-low thermal conductivity below 0.15 W / (m·K) at high temperatures. By controlling the difference in the evaporation rate of solvents, a gradient distribution of nano-fillers in the coating is achieved. The mixed solution is uniformly coated on the surface of the alumina matrix through spin coating or spraying processes. Utilizing the miscibility of different polar solvents and the difference in their evaporation rates, the fillers are driven to migrate directionally in the coating. The highly volatile solvent evaporates rapidly from the surface of the solution, causing the surface viscosity to rise rapidly, forming a "surface shell layer", which restricts the upward diffusion of the fillers. At the same time, the low-volatile solvent remains in the bottom of the coating for a longer time, prolonging the sedimentation time of the fillers and promoting the enrichment of the fillers at the bottom. During this process, the nano-fillers settle to the bottom under the action of gravity, while the smaller particles remain suspended due to Brownian motion, finally forming a gradient distribution structure with a high concentration at the bottom and a low concentration at the top. This method does not require complex equipment, has a low process cost, and through the construction of the gradient structure, can significantly extend the heat conduction path, thus effectively improving the heat insulation performance of the coating.

[0056] The coating process adopts spraying or spin coating methods, which have the advantages of high coating uniformity, low cost, simple process, flexible parameters and controllable thickness, while avoiding harsh conditions such as high-temperature vacuum environment. When the mixed solution is spin-coated on the surface of the alumina substrate, by adjusting the instrument parameters, the gradient distribution of nano-fillers in the coating can be precisely controlled. At the initial low-speed stage (500 - 1000 rpm), the sedimentation time of the fillers is extended to promote the enrichment of the fillers towards the bottom. At the high-speed stage (2000 - 4000 rpm), the evaporation of the top solvent is accelerated to form a low-filler-concentration region at the top. Secondly, the coating is prepared by the method of step-by-step coating (bottom composite layer + outer infrared reflection layer), which can independently optimize the functions of each layer, precisely control the coating thickness, achieve double blocking of heat conduction and heat radiation, and increase the comprehensive heat insulation efficiency by 30% - 50%. After coating, gradient curing (80 - 360 °C) and annealing process (200 - 400 °C) are used to eliminate internal stress.

[0057] This method enhances the interfacial thermal resistance through chemical bonding, the directional distribution of nano-fillers and the design of the low-emission layer structure, significantly improving the coating performance while simplifying the process. The thermal conductivity of the obtained coating is reduced by 30% - 50% compared with the traditional coating and 99.5% compared with the matrix alumina ceramic (30 W / (m·K)). Under the continuous action of the heat source, a stable heat insulation temperature difference of 20 - 30 °C can be formed. The coating also shows excellent performance under low-temperature conditions, and a cold insulation temperature difference of 10 - 15 °C can be achieved on the ice surface. Through the interface bonding optimization technology, the bonding strength between the coating and the matrix is significantly improved, and the complete interface structure is still maintained after 100 thermal shock cycles, fully meeting the long-term service requirements under extreme temperature environments.

[0058] In summary, the present invention discloses a reflection-thermal insulation dual-functional alumina ceramic, its preparation method and application. The preparation method of the present invention constructs a double-layer composite structure, enhances the interfacial thermal resistance through chemical bonding, the directional distribution of nano-fillers and the design of the low-emissivity layer structure, and synergistically reduces the heat conduction and radiative heat transfer of the alumina ceramic-based material, thereby improving its high-temperature thermal insulation performance. The bottom layer uses a coupling agent to modify the surface of the nano-fillers, forms a covalent bond with the polymer matrix, enhances the interfacial thermal resistance, and then prepares a thermal insulation coating through the solvent evaporation-induced self-assembly technology to achieve the gradient distribution of the nano-fillers in the matrix and extend the heat conduction path. The outer layer effectively suppresses the thermal radiation through the infrared reflection layer. Through the synergistic effect of heat conduction and thermal radiation, a dual heat blocking mechanism is constructed, thereby significantly improving the comprehensive thermal insulation performance of the material. During this process, the nano-metal oxides can be uniformly dispersed in the polymer matrix to form a dense organic / inorganic heterogeneous interface, and the Kapitza thermal resistance is greatly improved through phonon scattering, reducing the thermal conductivity of the composite layer to below 0.15 W / m·K and effectively suppressing heat conduction. At the same time, the infrared reflection layer on the outer layer has a reflectivity of more than 85% for infrared radiation (wavelength 2-14 μm), which can significantly reduce the radiative heat transfer. This dual thermal insulation coating has excellent overall performance, with a comprehensive thermal conductivity ≤ 0.15 W / m·K, a reduction of two orders of magnitude compared to the uncoated alumina ceramic (about 30 W / m·K), and an improvement in the thermal insulation efficiency of 30% - 50%. The temperature difference for heat insulation of the thermal insulation coating is 20 - 30 °C, and the temperature difference for cold insulation can reach 10 - 15 °C.

[0059] The alumina thermal insulation ceramic with a composite structure in the present invention has a wide range of application scenarios. For example, in the aerospace field, it can be used for the hot-end components of engines and the thermal insulation of aircraft skins to reduce the high-temperature heat load; in the energy industry, it can be used for pipeline thermal insulation to improve energy utilization efficiency; in electronic devices, it can be used for high-power chip heat dissipation substrates to solve the problem of local overheating; in building energy conservation, it can be used for the thermal insulation of building glass or walls to reduce energy consumption. The alumina thermal insulation ceramic with a composite structure in the present invention exhibits excellent environmental stability, and at the same time has the potential for large-scale production and cost competitiveness, and has broad application prospects.

[0060] The following further elaborates the present invention in combination with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0061] Conventional instruments and equipment in the art are used in the following examples. For the experimental methods without specific conditions noted in the following examples, they are generally carried out under conventional conditions or according to the conditions recommended by the manufacturer. Various raw materials are used in the following examples. Unless otherwise stated, commercially available products of conventional specifications in the art are used, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" represents weight percentage, "parts" represents weight parts, and the ratio represents weight ratio.

[0062] Example 1

[0063] A preparation method of a reflection-thermal insulation dual-functional alumina ceramic, comprising the following steps:

[0064] S1: By mass, 33 parts of hollow silica are weighed and subjected to low-temperature plasma treatment at a power of 100 W for 30 min, and then added to 330 parts of ethanol and 0.99 part of silane coupling agent KH550, and reacted at 80 °C for 4 h for modification to obtain surface-modified hollow silica filler;

[0065] S2: The surface-modified hollow silica filler is added to 10 parts of polyimide and 66 parts of a mixed polar solvent of N-methylpyrrolidone / N,N-dimethylformamide (6:4), and an insulating and heat-preserving coating is obtained through 30 min of ultrasonic treatment;

[0066] S3: The insulating and heat-preserving coating is applied to the surface of the alumina ceramic by spraying process with an air pressure of 0.3 MPa to initially form a 10-μm coating. And through a gradient temperature curing process, the curing process is to react at 80 °C for 1 h, 150 °C for 1 h, and 300 °C for 1 h, and the temperature is gradually increased to cure the coating to obtain an alumina ceramic with a heat-insulating coating function;

[0067] S4: By mass, 10 parts of polyimide are dissolved in 66 parts of N-methylpyrrolidone to form a uniform mixed solution, and then 10 parts of tungsten oxide are added. By adding 0.5% of polyvinylpyrrolidone and cooperating with 30 min of ultrasonic treatment, an infrared reflection coating is formed; Subsequently, the infrared reflection coating is sprayed on the surface of the alumina ceramic with a heat-insulating coating function by a high-pressure spray gun with a nozzle diameter of 0.3 mm, and the thickness of the sprayed infrared reflection coating is 1 μm, and then annealed at 200 °C for 1 h under the protection of a nitrogen atmosphere to effectively eliminate the internal stress in the coating and promote the interface combination, and finally obtain a reflection-thermal insulation dual-functional alumina ceramic with a dense structure and firm combination. The thickness of the reflection-thermal insulation coating prepared in this example is 11 μm.

[0068] The performance test of the reflective-insulating dual-functional alumina ceramic prepared in this embodiment was carried out. According to the relevant provisions of GB / T13475-2008 "Determination and calibration of adiabatic steady-state heat transfer properties and protective hot box method", the thermal conductivity of the coating after the 200°C test was 0.08W / m·K. The cross-hatch method (ASTM D3359) showed that the coating had no shedding (4B grade). The Fourier infrared spectrum showed that the reflectivity of the outer coating was 88% in the 2-14μm band. The average thermal insulation temperature difference was 23°C when heated on an 80°C heating plate for 5 minutes, and the cold insulation temperature difference was 10°C when measured on an ice surface.

[0069] Example 2

[0070] A method for preparing a reflective-insulating dual-functionalized alumina ceramic comprises the following steps:

[0071] S1: 105 parts of hollow silica were weighed by mass and subjected to low-temperature plasma treatment at 100 W power for 30 min, then added to 1050 parts of ethanol and 5.25 parts of silane coupling agent KH560, and reacted at 80°C for 6 h to obtain a surface-modified hollow silica filler;

[0072] S2: adding the surface-modified hollow silica filler to a mixed polar solvent of 20 parts of polyimide and 100 parts of N-methylpyrrolidone / N,N-dimethylformamide (8:2), and subjecting the mixture to ultrasonic treatment for 60 minutes to obtain a thermal insulation coating;

[0073] S3: The thermal insulation coating is applied on the surface of the alumina ceramics with a spraying process at a pressure of 0.5 MPa to initially form a coating of 100 μm. The coating is cured by a gradient temperature increase process, in which the curing process is 1 hour at 80°C, 1 hour at 150°C, and 1 hour at 300°C. The temperature is gradually increased to cure the coating, forming a stable thermal insulation coating and obtaining alumina ceramics with a functionalized thermal insulation coating.

[0074] S4: By mass, 20 parts of polyimide are dissolved in 100 parts of N-methylpyrrolidone to form a uniform mixed solution, and then 40 parts of tungsten oxide are added. By adding 2% polyvinylpyrrolidone and coordinating with 60 minutes of ultrasonic treatment, an infrared reflective coating is formed; then a high-pressure spray gun with a nozzle diameter of 0.5 mm is used to spray the infrared reflective coating on the surface of the alumina ceramic functionalized with the thermal insulation coating. The thickness of the sprayed infrared reflective coating is 10 μm, and then annealing treatment is carried out at 400°C for 2 hours under the protection of a nitrogen atmosphere to effectively eliminate the internal stress of the coating and promote interface bonding, and finally obtain a dense structure and firmly bonded reflective-insulating dual-functionalized alumina ceramic. The thickness of the reflective-insulating coating prepared in this embodiment is 110 μm.

[0075] Performance tests were carried out on the reflection-thermal insulation dual-functionalized alumina ceramics prepared in this example. According to the relevant regulations of GB / T 13475-2008 "Determination of steady-state heat transfer properties Calibration and guarded hot box method", the thermal conductivity of the coating after a 200 °C test was 0.05 W / m·K. The cross-cut method (ASTM D3359) showed that the coating had no peeling (grade 5B). Fourier transform infrared spectroscopy showed that the reflectivity of the outer coating in the 2-14 μm band was 92%. When heated on an 80 °C hot plate for 5 minutes, the average thermal insulation temperature difference was 25 °C, and the cold insulation temperature difference measured on the ice surface reached 14 °C.

[0076] Example 3

[0077] A preparation method of a reflection-thermal insulation dual-functionalized alumina ceramic, comprising the following steps:

[0078] S1: By mass, 33 parts of hollow zirconia were subjected to low-temperature plasma treatment at a power of 100 W for 30 minutes, and then added to 330 parts of toluene and 5.25 parts of silane coupling agent KH570, and reacted at 80 °C for 6 hours for modification to obtain surface-modified hollow zirconia filler;

[0079] S2: The surface-modified hollow zirconia filler was added to 20 parts of polyether ether ketone and 66 parts of a mixed polar solvent of N,N-dimethylacetamide / acetone (7:3), and an insulating and heat-preserving coating was obtained through 50 minutes of ultrasonic treatment;

[0080] S3: The spin coating process was carried out at a low speed stage of 500 rpm for 30 s and at a high speed stage of 3000 rpm for 30 s. The insulating and heat-preserving coating was applied to the surface of the alumina ceramic to initially form a 20-μm coating. Through a gradient temperature curing process, the curing process was to react at 80 °C for 1 h, 180 °C for 1 h, and 320 °C for 1 h, gradually increasing the temperature to cure the coating, and an alumina ceramic with a heat-insulating coating function was obtained.

[0081] S4: By mass, 20 parts of polyether ether ketone were dissolved in 100 parts of N,N-dimethylacetamide to form an infrared reflection coating. Then 10 parts of titanium dioxide were added, and a stable dispersion system was formed by adding 2% of polyvinylpyrrolidone and cooperating with 60 minutes of ultrasonic treatment; subsequently, the infrared reflection coating was sprayed on the surface of the alumina ceramic with a heat-insulating coating function using a high-pressure spray gun with a nozzle diameter of 0.5 mm, and the thickness of the sprayed infrared reflection coating was 2 μm. Finally, an annealing treatment was carried out at 300 °C for 1 h under a nitrogen atmosphere protection. The internal stress in the coating was effectively eliminated and the interfacial bonding was promoted, and finally a reflection-thermal insulation dual-functionalized alumina ceramic with a dense structure and firm bonding was obtained. The thickness of the reflection-thermal insulation coating prepared in this example was 22 μm.

[0082] The performance of the reflection-insulation dual-functionalized alumina ceramic prepared in this example was tested. According to the relevant regulations of GB / T 13475-2008 "Determination of Steady-State Heat Transfer Properties - Guarded Hot Box Method", the thermal conductivity of the coating after the 200 °C test was 0.06 W / m·K. The cross-cut method (ASTM D3359) showed that the coating had no peeling (grade 5B). Fourier transform infrared spectroscopy showed that the reflectivity of the outer coating in the 2-14 μm band was 90%. When heated on an 80 °C hot plate for 5 min, the average insulation temperature difference was 26 °C, and when measured on an ice surface, the cold insulation temperature difference reached 15 °C.

[0083] Example 4

[0084] A preparation method of a reflection-insulation dual-functionalized alumina ceramic includes the following steps:

[0085] S1: By mass, 105 parts of hollow zirconia were weighed and subjected to low-temperature plasma treatment at a power of 100 W for 30 min, and then added to 1050 parts of toluene and 0.99 parts of silane coupling agent KH570, and reacted at 80 °C for 6 h for modification to obtain surface-modified hollow zirconia fillers.

[0086] S2: The surface-modified hollow zirconia fillers were added to 20 parts of polyether ether ketone and 100 parts of a mixed polar solvent of N,N-dimethylacetamide / acetone (6:4), and an insulation coating was obtained through 60 min of ultrasonic treatment.

[0087] S3: The spin coating process was carried out at a low speed of 500 rpm for 30 s and at a high speed of 3000 rpm for 30 s to coat the insulation coating on the surface of the alumina ceramic, initially forming a 10-μm coating. Finally, through a gradient temperature curing process, the curing process was to react at 80 °C for 1 h, 180 °C for 1 h, and 320 °C for 1 h, gradually increasing the temperature to cure the coating to obtain an insulation coating-functionalized alumina ceramic.

[0088] S4: By mass, 10 parts of polyether ether ketone were dissolved in 100 parts of N,N-dimethylacetamide to form a uniform mixed solution. Then 10 parts of titanium dioxide were added, and through the addition of 0.5% of polyvinylpyrrolidone and 30 min of ultrasonic treatment, an infrared reflection coating was formed; subsequently, the infrared reflection coating was sprayed on the surface of the insulation coating-functionalized alumina ceramic using a high-pressure spray gun with a nozzle diameter of 0.3 mm, and the thickness of the sprayed infrared reflection coating was 1 μm. Finally, an annealing treatment was carried out at 200 °C for 1 h under a nitrogen atmosphere protection. The internal stress of the coating was effectively eliminated and the interfacial bonding was promoted, and finally a reflection-insulation dual-functionalized alumina ceramic with a dense structure and strong bonding was obtained. The thickness of the reflection-insulation coating prepared in this example was 11 μm.

[0089] The performance test of the reflective-insulating dual-functional alumina ceramic prepared in this embodiment was carried out. According to the relevant provisions of GB / T13475-2008 "Determination and calibration of adiabatic steady-state heat transfer properties and protective hot box method", the thermal conductivity of the coating after the 200°C test was 0.15W / m·K. The cross-hatch method (ASTM D3359) showed that the coating had no shedding (grade 3B). The Fourier infrared spectrum showed that the reflectivity of the outer coating was 86% in the 2-14μm band. The average thermal insulation temperature difference was 22°C when heated on an 80°C heating plate for 5 minutes, and the cold insulation temperature difference was 10°C when measured on an ice surface.

[0090] Example 5

[0091] A method for preparing a reflective-insulating dual-functionalized alumina ceramic comprises the following steps:

[0092] S1: 33 parts of hollow vanadium dioxide were weighed by mass and subjected to low-temperature plasma treatment at 100 W power for 30 minutes, then added to 330 parts of N,N-dimethylformamide and 0.99 parts of silane coupling agent KH845-4, and reacted at 80°C for 4 hours to obtain a surface-modified hollow vanadium dioxide filler;

[0093] S2: adding the surface-modified hollow vanadium dioxide filler into a mixed polar solvent of 10 parts of polyphenylene sulfide and 66 parts of N-methylpyrrolidone / ethanol (6:4), and subjecting the mixture to ultrasonic treatment for 30 minutes to obtain a thermal insulation coating;

[0094] S3: The thermal insulation coating is applied to the surface of the alumina ceramic by spraying at a pressure of 0.3 MPa to initially form a coating of 100 μm. Finally, the curing process is carried out by a gradient temperature rise method, with the temperature rising for 1 hour at 80°C, 1 hour at 230°C, and 1 hour at 360°C. The temperature is gradually raised to cure the coating, and the alumina ceramic with thermal insulation coating functionalization is obtained.

[0095] S4: In terms of mass fractions, 10 parts of polyphenylene sulfide are dissolved in 66 parts of N-methylpyrrolidone to form an infrared reflective coating; then 10 parts of tungsten oxide are added, and a stable dispersion system is formed by adding 0.5% polyvinyl pyrrolidone and coordinating with 30 minutes of ultrasonic treatment; then the infrared reflective coating is sprayed on the surface of the alumina ceramic functionalized with the thermal insulation coating using a high-pressure spray gun with a nozzle diameter of 0.3 mm, and the thickness of the sprayed infrared reflective coating is 10 μm. Finally, annealing treatment is performed at 200°C for 1 hour under nitrogen atmosphere protection. Effectively eliminate the internal stress of the coating and promote interface bonding, and finally obtain a densely structured, firmly bonded reflective-insulating dual-functionalized alumina ceramic. The thickness of the reflective-insulating coating prepared in this embodiment is 110 μm.

[0096] Performance tests were carried out on the reflection- and heat-insulation dual-functionalized alumina ceramics prepared in this example. According to the relevant regulations of GB / T 13475-2008 "Determination of Steady-State Heat Transfer Properties - Guarded Hot Box Method", the thermal conductivity of the coating after a 200 °C test was 0.15 W / m·K. The cross-cut method (ASTM D3359) showed that the coating had no peeling (grade 3B). Fourier transform infrared spectroscopy showed that the reflectivity of the outer coating in the 2-14 μm band was 85%. When heated on an 80 °C hot plate for 5 min, the average heat-insulation temperature difference was 20 °C, and the cold-insulation temperature difference measured on the ice surface reached 10 °C.

[0097] Example 6

[0098] A preparation method of reflection- and heat-insulation dual-functionalized alumina ceramics includes the following steps:

[0099] S1: Weigh 105 parts by mass of hollow vanadium dioxide, perform low-temperature plasma treatment at a power of 100 W for 30 min, and then add it to 1050 parts of N,N-dimethylformamide and 5.25 parts of silane coupling agent KH845-4, and react at 80 °C for 6 h for modification to obtain surface-modified vanadium dioxide filler.

[0100] S2: Add the surface-modified vanadium dioxide filler to 20 parts of polyphenylene sulfide and 100 parts of a mixed polar solvent of N-methylpyrrolidone / ethanol (8:2), and obtain a heat-insulating and heat-preserving coating through 60 min of ultrasonic treatment.

[0101] S3: Adopt a spraying process with an air pressure of 0.5 MPa, apply the heat-insulating and heat-preserving coating on the surface of the alumina ceramic, and initially form a 60-μm coating. Finally, through the gradient heating method, the curing process is to react at 80 °C for 1 h, 230 °C for 1 h, and 360 °C for 1 h, gradually increasing the temperature to cure the coating to obtain heat-insulating coating-functionalized alumina ceramics.

[0102] S4: Weigh 20 parts by mass of polyphenylene sulfide and dissolve it in 100 parts of N-methylpyrrolidone to form a uniform mixed solution. Then add 15 parts of titanium dioxide, form an infrared reflection coating by adding 1.5% of polyvinylpyrrolidone and cooperating with 50 min of ultrasonic treatment; subsequently, spray the infrared reflection coating on the surface of the heat-insulating coating-functionalized alumina ceramic by using a high-pressure spray gun with a nozzle diameter of 0.4 mm, and the thickness of the sprayed infrared reflection coating is 3 μm. Finally, perform annealing treatment at 200 °C for 1 h under the protection of a nitrogen atmosphere. Effectively eliminate the internal stress in the coating and promote interface bonding, and finally obtain a reflection- and heat-insulation dual-functionalized alumina ceramic with a dense structure and firm bonding. The thickness of the reflection- and heat-insulation coating prepared in this example is 63 μm.

[0103] reflection- and heat-insulation dual-functionalized alumina ceramics.

[0104] The performance of the reflection-insulation dual-functionalized alumina ceramic prepared in this example was tested. According to the relevant regulations of GB / T 13475-2008 "Determination of Steady-State Heat Transfer Properties - Guarded Hot Box Method", the thermal conductivity of the coating after the 200 °C test was 0.13 W / m·K. The cross-cut method (ASTM D3359) showed that the coating had no peeling (grade 4B). Fourier transform infrared spectroscopy showed that the reflectivity of the outer coating in the 2-14 μm band was 88%. When heated on an 80 °C hot plate for 5 min, the average insulation temperature difference was 27 °C, and the cold insulation temperature difference measured on the ice surface reached 12 °C.

[0105] Example 7

[0106] A preparation method of a reflection-insulation dual-functionalized alumina ceramic, comprising the following steps:

[0107] S1: By mass, 54 parts of hollow mesoporous titanium oxide were weighed and subjected to low-temperature plasma treatment at a power of 100 W for 30 min, and then added to 540 parts of ethanol and 2.7 parts of silane coupling agent KH550, and reacted at 80 °C for 5 h for modification to obtain surface-modified hollow mesoporous titanium oxide filler.

[0108] S2: The surface-modified hollow mesoporous titanium oxide filler was added to 14 parts of polyimide and 100 parts of a mixed polar solvent of dimethyl sulfoxide / acetone (7:3), and an insulation coating was obtained through 50 min of ultrasonic treatment.

[0109] S3: The spin coating process was carried out at a low speed of 1000 rpm for 30 s and at a high speed of 4000 rpm for 30 s. The insulation coating was applied on the surface of the alumina ceramic to initially form a 50 μm coating. Finally, through the gradient heating method, the curing process was to react at 80 °C for 1 h, 190 °C for 1 h, and 300 °C for 1 h, gradually increasing the temperature to cure the coating to obtain an insulation coating-functionalized alumina ceramic.

[0110] S4: By mass, 5 parts of polyether ether ketone were dissolved in 88 parts of N,N-dimethylacetamide to form a uniform mixed solution. Then 10 parts of tungsten oxide were added, and by adding 1% of polyvinylpyrrolidone and cooperating with 40 min of ultrasonic treatment, an infrared reflection coating was formed; subsequently, the infrared reflection coating was sprayed on the surface of the insulation coating-functionalized alumina ceramic using a high-pressure spray gun with a nozzle diameter of 0.4 mm, and the thickness of the sprayed infrared reflection coating was 8 μm. Finally, annealing treatment was carried out at 300 °C for 1 h under a nitrogen atmosphere protection. The internal stress in the coating was effectively eliminated and the interfacial bonding was promoted, and finally a reflection-insulation dual-functionalized alumina ceramic with a dense structure and firm bonding was obtained. The thickness of the reflection-insulation coating prepared in this example was 58 μm.

[0111] The performance of the reflection-insulation dual-functionalized alumina ceramic prepared in this example was tested. According to the relevant regulations of GB / T 13475-2008 "Determination of Steady-State Heat Transfer Properties - Guarded Hot Box Method", the thermal conductivity of the coating after a 200 °C test was 0.11 W / m·K. The cross-cut method (ASTM D3359) showed that the coating had no peeling (grade 5B). Fourier transform infrared spectroscopy showed that the reflectivity of the outer coating in the 2-14 μm band was 91%. When heated on an 80 °C hot plate for 5 min, the average insulation temperature difference was 23 °C, and the cold insulation temperature difference measured on the ice surface reached 14 °C.

[0112] Example 8

[0113] A preparation method of a reflection-insulation dual-functionalized alumina ceramic, comprising the following steps:

[0114] S1: By mass, 93 parts of hollow mesoporous titanium oxide were weighed and subjected to low-temperature plasma treatment at a power of 100 W for 30 min, and then added to 930 parts of ethanol and 4.65 parts of silane coupling agent KH792, and reacted at 80 °C for 5 h for modification to obtain surface-modified hollow silica fillers;

[0115] S2: The surface-modified hollow silica fillers were added to 18 parts of polyphenylene sulfide and 100 parts of a mixed polar solvent of N,N-dimethylacetamide / ethanol (7:3), and an insulation coating was obtained through 50 min of ultrasonic treatment;

[0116] S3: The spin coating process was carried out at a low speed of 1000 rpm for 30 s and at a high speed of 4000 rpm for 30 s to apply the insulation coating on the surface of the alumina ceramic, initially forming an 80-μm coating. Finally, through the gradient heating method, the curing process was to react at 90 °C for 1 h, 170 °C for 1 h, and 300 °C for 1 h, gradually increasing the temperature to cure the coating to obtain an alumina ceramic with an insulated coating function.

[0117] S4: By mass, 10 parts of polyphenylene sulfide were dissolved in 66 parts of N,N-dimethylacetamide to form a uniform mixed solution. Then 10 parts of tungsten oxide were added, and by adding 2% of polyvinylpyrrolidone and cooperating with 60 min of ultrasonic treatment, an infrared reflection coating was formed; subsequently, the infrared reflection coating was sprayed on the surface of the alumina ceramic with an insulated coating function using a high-pressure spray gun with a nozzle diameter of 0.5 mm, and the thickness of the sprayed infrared reflection coating was 10 μm. Finally, an annealing treatment was carried out at 400 °C for 1 h under a nitrogen atmosphere protection. The internal stress in the coating was effectively eliminated and the interface bonding was promoted, and finally a reflection-insulation dual-functionalized alumina ceramic with a dense structure and firm bonding was obtained. The thickness of the reflection-insulation coating prepared in this example was 90 μm.

[0118] The performance of the reflection-insulation dual-functional alumina ceramic prepared in this embodiment was tested. According to the relevant regulations of GB / T 13475-2008 "Determination of Steady-State Heat Transfer Properties Calibration and Guarded Hot Box Method", the thermal conductivity of the coating after a 200 °C test was 0.09 W / m·K. The cross-cut method (ASTM D3359) showed that the coating had no peeling (grade 4B). Fourier transform infrared spectroscopy showed that the reflectivity of the outer coating in the 2-14 μm band was 87%. When heated on an 80 °C hot plate for 5 minutes, the average insulation temperature difference was 20 °C, and the cold insulation temperature difference measured on the ice surface reached 15 °C.

[0119] Figure 1 This is the thermal conductivity of the reflection-insulation coatings prepared in Example 1 and Example 2 of the present invention. As can be seen from the figure, the reflection-insulation coating has a low thermal conductivity. Through the synergistic effect of the selection of low-thermal-conductivity materials and the design of a multi-level pore structure, excellent heat insulation performance is achieved.

[0120] Figure 2 This is the comparison diagram of infrared thermal imaging before and after the modification of the nano-sized hollow oxide filler in Example 3 of the present invention. As can be seen from the figure, when using an infrared thermal imager to test the coating before and after the modification of the nano-sized hollow oxide filler, it can be seen that the heat diffusion at the edge of the unmodified coating is faster, while the overall temperature distribution of the modified coating is uniform after 10 minutes, and the temperature in the central region is significantly lower than that of the unmodified coating. This shows that chemical modification can reduce the phonon transfer at the interface between the filler and the matrix and improve the Kapitza thermal resistance.

[0121] Figure 3 This is the temperature change curve of the reflection-insulation coating prepared in Example 4 of the present invention. As can be seen from the figure, keeping the hot plate at 80 °C unchanged and using a thermocouple to monitor the temperature change trend of the coating, it can be found that the coating temperature shows an ideal heat insulation trend of rapid initial rise - slowdown in the middle - approaching steady state in the later stage, and the average temperature difference reaches 22 °C, verifying its excellent heat insulation effect.

[0122] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A preparation method of a reflection-thermal insulation dual-functionalized alumina ceramic, characterized in that, It includes the following steps: S1: Perform low-temperature plasma treatment on the nano-sized hollow oxide filler, and then add the treated nano-sized hollow oxide filler into a mixed solution of an organic solvent and a silane coupling agent, and stir and react to obtain a surface-modified nano-sized hollow oxide filler; S2: Add the surface-modified nano-sized hollow oxide filler into a polymer and a mixed polar solvent, and perform ultrasonic treatment to obtain a heat-insulating and heat-preserving coating; the mixed polar solvent includes a first polar solvent and a second polar solvent; the boiling point of the first polar solvent is higher than that of the second polar solvent; S3: Coat the heat-insulating and heat-preserving coating on the surface of alumina ceramic to form a preliminary coating, and cure the coating through a gradient temperature-rising curing process to obtain an alumina ceramic functionalized with a heat-insulating coating; S4: Coat an infrared reflective coating on the surface of the alumina ceramic functionalized with the heat-insulating coating, and perform annealing treatment in a nitrogen atmosphere to obtain the alumina ceramic with dual reflection and heat-insulating functions.

2. The preparation method of a reflection- and heat-insulation dual-functionalized alumina ceramic according to claim 1, characterized in that, By mass, the ratio of the nano-sized hollow oxide filler to the silane coupling agent is (33-105):(0.99-5.25).

3. The preparation method of a reflection- and heat-insulation dual-functional alumina ceramic according to claim 1, characterized in that, The nano-sized hollow oxide is one or more of hollow silica, hollow zirconia, hollow vanadium dioxide, and hollow mesoporous titanium oxide.

4. The preparation method of a reflection- and heat-insulation dual-functional alumina ceramic according to claim 1, characterized in that, By mass, the ratio of the nano-sized hollow oxide filler to the polymer and the mixed polar solvent is (33-105):(10-20):(66-100); by mass, the ratio of the first polar solvent to the second polar solvent is (8-6):(2-4).

5. The preparation method of a reflection-thermal insulation dual-functional alumina ceramic according to claim 1, characterized in that, The polymer is at least one of polyimide, polyphenylene sulfide, and polyether ether ketone.

6. The preparation method of a reflection-thermal insulation dual-functional alumina ceramic according to claim 1, characterized in that, In step S3, the gradient temperature-rising curing process is specifically: react at 80-120°C for 1 h, react at 150-220°C for 1 h, and react at 300-360°C for 1 h.

7. The preparation method of a reflection-thermal insulation dual-functional alumina ceramic according to claim 1, characterized in that, In step S4, the preparation process of the infrared reflective coating is: by mass, dissolve 10-20 parts of the polymer in 66-100 parts of a third polar solvent, and then sequentially add 10-40 parts of an infrared reflective filler and polyvinylpyrrolidone, and perform ultrasonic treatment to obtain the infrared reflective coating; the mass of the polyvinylpyrrolidone accounts for 0.5%-2% of the total mass of the polymer, the third polar solvent, and the infrared reflective filler.

8. The preparation method of a reflection- and heat-insulation dual-functional alumina ceramic according to claim 1, wherein In step S4, the annealing treatment is specifically: keep the temperature at 200-400°C for 1-2 h.

9. A reflection- and heat-insulating dual-functionalized alumina ceramic, characterized in that, It is obtained by the method described in any one of claims 1-8; the reflectivity of the alumina ceramic with dual reflection and heat-insulating functions to infrared radiation is greater than 85%, and the thermal conductivity of the alumina ceramic with dual reflection and heat-insulating functions is not greater than 0.15 W / m·K.

10. Use of the alumina ceramic with dual reflection and heat-insulating functions described in claim 9 in the preparation of heat-insulating devices.

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