Radiative cooling composite material with high conductivity in three-dimensional direction, preparation method and application thereof

Abstract

This invention provides a three-dimensionally highly conductive radiation-cooled composite material, its preparation method, and its applications, relating to the field of radiation-cooled energy-saving composite materials. The three-dimensionally highly conductive radiation-cooled composite material comprises: a foamed metal and a polymer for radiation cooling filling the pore structure of the foamed metal. The radiation-cooled composite material of this invention exhibits three-dimensional high conductivity while achieving efficient electron transport, effective sunlight reflection, and optimal mid-infrared emission.

Description

Technical Field

[0001] This invention relates to the field of radiation-cooled energy-saving composite materials, and in particular to a three-dimensionally highly conductive radiation-cooled composite material, its preparation method, and its applications. Background Technology

[0002] With global warming becoming increasingly severe, extreme heatwaves are becoming more frequent. To meet the growing demand for cooling, researchers are focusing on ensuring a comfortable living environment. However, current cooling methods not only consume large amounts of energy but also cause serious environmental damage. Therefore, developing a zero-energy-consumption, environmentally friendly cooling technology is of great significance.

[0003] The discovery of radiative cooling provides a new approach to solving the problem of global warming. Typical radiative cooling materials not only require high emissivity in the mid-infrared range (8~13 µm) for effective radiative heat transfer, but also high reflectivity in the solar spectrum (0.3~2.5 μm) to minimize the absorption of sunlight and avoid the material temperature from rising, thereby achieving radiative cooling.

[0004] Currently, various materials have been developed for passive radiative cooling, but they are typically composed of insulating materials such as polymers, metal oxides, or ceramics, including porous polymer films, coatings, and aerogels; polymer / metal oxide composite films or coatings; ceramics, or glass. Clearly, currently available passive radiative cooling materials are primarily insulating, which limits their application in scenarios requiring high conductivity, significantly restricting their use in applications demanding high conductivity. However, materials with high conductivity, such as metals, exhibit low solar reflectivity and infrared emissivity, while materials with high solar reflectivity and infrared emissivity, such as polymers and ceramics, have very low conductivity. In other words, existing conductors do not meet the necessary conditions for radiative cooling. Therefore, achieving passive radiative cooling with high conductivity while simultaneously possessing high solar reflectivity and high infrared emissivity remains a challenge.

[0005] While research has explored the use of polished metals as substrates to enhance solar reflectivity, such as polymer / metal or ceramic / metal multilayer photonic crystal structures that can achieve effective daytime radiative cooling, these anisotropic, continuous multilayer structures struggle to exhibit high three-dimensional conductivity. Therefore, simultaneously achieving efficient electron transport, effective solar reflection, and optimal mid-infrared emission remains a formidable challenge.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a three-dimensionally highly conductive radiation-cooled composite material, its preparation method, and its applications. The composite material of this invention can simultaneously achieve efficient electron transport, effective solar radiation reflection, and optimal mid-infrared emission.

[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: In a first aspect, the present invention provides a three-dimensionally highly conductive radiation-cooled composite material, the three-dimensionally highly conductive radiation-cooled composite material comprising: a foam metal and a polymer for radiation cooling filled within the pore structure of the foam metal.

[0009] Furthermore, the foam metal is selected from any one or a combination of at least two of the following: foamed copper (CF), foamed nickel (NF), foamed silver (AF), foamed iron, foamed nickel-iron, foamed nickel-molybdenum, foamed titanium, foamed cobalt-nickel, foamed copper-nickel, foamed zinc, foamed nickel-zinc, and foamed stainless steel.

[0010] Furthermore, the porosity of the foamed metal is 90-98%, the pore size of the foamed metal is 5-130 PPI, the average pore diameter of the foamed metal is 0.2-5.1 mm, and the thickness of the foamed metal is 1-30 mm.

[0011] Furthermore, the polymer used for radiation cooling is selected from fluoropolymers.

[0012] Furthermore, the fluoropolymer is selected from any one or a combination of at least two of the following: perfluoroethylene propylene copolymer, polytetrafluoroethylene, polyvinylidene fluoride, polyperfluoroalkoxy resin, polytrifluoroethylene, polychlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer, and polyvinyl fluoride, preferably perfluoroethylene propylene copolymer.

[0013] Furthermore, the polymer used for radiation cooling is filled at a concentration of 0.5~2 mg / mm³. 3 .

[0014] Furthermore, the average particle size of the polymer used for radiation cooling is 0.5~5 μm.

[0015] Furthermore, the conductivity of the three-dimensionally highly conductive radiation-cooled composite material is 1.0 × 10⁻⁶. 5 S / m or higher.

[0016] Furthermore, the infrared emissivity of the three-dimensionally highly conductive radiation-cooled composite material is above 85%; and the solar reflectivity of the three-dimensionally highly conductive radiation-cooled composite material is above 85%.

[0017] In a second aspect, the present invention provides a method for preparing a three-dimensionally highly conductive radiation-cooled composite material as described in the first aspect, the method comprising: A fluoropolymer slurry is placed on the surface of the foam metal and repeatedly coated to penetrate the pore structure of the foam metal, eventually exposing the conductive network of the foam metal on the surface, thus obtaining the filled foam metal. The filled foam metal is preheated, vented, pressurized, and cooled sequentially to obtain the three-dimensionally highly conductive radiation-cooled composite material.

[0018] Furthermore, the fluoropolymer slurry comprises a fluoropolymer and a solvent.

[0019] Furthermore, the mass ratio of the fluoropolymer to the solvent is 1:(1~2).

[0020] Furthermore, the solvent is selected from any one or a combination of at least two of anhydrous ethanol, n-hexane, acetone, and toluene, preferably anhydrous ethanol.

[0021] Furthermore, the foamed metal requires the following pretreatment steps: The foamed metal was immersed in acetone and hydrochloric acid solutions respectively, ultrasonically cleaned, and then the residual acetone and hydrochloric acid solutions were cleaned and dried to obtain the pretreated foamed metal.

[0022] Furthermore, the concentration of the hydrochloric acid solution is 0.5~2 mol / L.

[0023] Furthermore, the ultrasonic cleaning time is 5-15 minutes.

[0024] Furthermore, the specific steps for preparing the filled foam metal are as follows: A fluoropolymer slurry is placed on one side of the foam metal surface, and the fluoropolymer slurry is scraped into the pore structure of the foam metal with a blade, adhering closely to the surface of the foam metal, and then dried. After flipping, repeat the same step on the other side of the foam metal surface, and then repeatedly scrape and coat the foam metal to fill the pore structure with the fluoropolymer slurry, and finally expose the conductive network of the foam metal on the surface to obtain the filled foam metal.

[0025] Furthermore, the total amount of the fluoropolymer slurry used is 1~4 mL / cm³. 3 .

[0026] Furthermore, in each coating process, the amount of the fluoropolymer slurry used is 0.5~2 mL / cm². 3 .

[0027] Furthermore, the total number of scraping applications is 2 to 6.

[0028] Furthermore, the drying temperature for each drying cycle is 60~80℃, and the drying time for each cycle is 2~5 minutes.

[0029] Furthermore, the preheating, venting, and pressure holding are carried out inside the flat vulcanizing machine.

[0030] Furthermore, when the polymer used for radiation cooling is a fluoropolymer, the preheating temperature is 170~350℃, the preheating pressure is 4~6 MPa, and the preheating time is 10~20 s.

[0031] Thirdly, the present invention provides the application of a three-dimensionally highly conductive radiation-cooled composite material as described in the first aspect in the preparation of articles for cooling.

[0032] Compared with the prior art, the present invention has the following beneficial effects: (1) The composite material described in this invention not only has a high emissivity in the mid-infrared range, which can reach more than 85%, to effectively transfer heat through radiation; at the same time, it also has a high reflectivity in the solar spectrum, which can reach more than 85%, to minimize the absorption of sunlight and avoid the rise in material temperature, thereby achieving radiation cooling. (2) The composite material described in this invention has a temperature that is more than 5°C lower than the ambient temperature and more than 27°C lower than the temperature of traditional metal conductors. Therefore, it represents a major advancement in the field of metal-like conductive radiation cooling.

[0033] (3) The composite material described in this invention has high electrical conductivity, with a conductivity of 1.0 × 10⁻⁶. 5 With a conductivity of S / m or higher, it can meet the needs of applications requiring high conductivity. Attached Figure Description

[0034] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0035] Figure 1 EDS spectrum of the surface of the three-dimensionally highly conductive radiation-cooled composite material provided in Embodiment 1 of the present invention.

[0036] Figure 2 Scanning electron microscope (SEM) image of the three-dimensionally highly conductive radiation-cooled composite material provided in Embodiment 1 of the present invention.

[0037] Figure 3 Comparison of spectral characteristics of the three-dimensional highly conductive radiation-cooled composite materials provided in Examples 1-3 of this invention.

[0038] Figure 4 Comparison of spectral characteristics of the three-dimensional highly conductive radiation-cooled composite materials provided in Embodiments 1 and 4-5 of the present invention.

[0039] Figure 5 A comparison of the spectral characteristics of the three-dimensional highly conductive radiation-cooled composite material provided in Embodiment 1 of the present invention, copper metal (Cu) provided in Comparative Example 1, and copper foam (CF) provided in Comparative Example 2.

[0040] Figure 6 Outdoor test images of the three-dimensional highly conductive radiation cooling composite material provided in Embodiment 1 of the present invention, copper metal (Cu) provided in Comparative Example 1, and copper foam (CF) provided in Comparative Example 2.

[0041] Figure 7 The conductivity test diagrams are for the three-dimensionally highly conductive radiation-cooled composite materials provided in Embodiments 1-3 of the present invention.

[0042] Figure 8 The water contact angle test diagrams are for the three-dimensional highly conductive radiation-cooled composite materials provided in Embodiments 1-3 of the present invention. Detailed Implementation

[0043] Unless otherwise defined herein, the scientific and technical terms used in conjunction with this invention shall have the meanings commonly understood by one of ordinary skill in the art. The meaning and scope of terms shall be clear; however, in any case of potential ambiguity, the definitions provided herein shall prevail over any dictionary or foreign definitions. In this application, unless otherwise stated, the use of "or" means "and / or". Furthermore, the use of the term "comprising" and other forms is non-limiting.

[0044] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] In a first aspect, the present invention provides a three-dimensionally highly conductive radiation-cooled composite material, the three-dimensionally highly conductive radiation-cooled composite material comprising: a foam metal and a polymer for radiation cooling filled within the pore structure of the foam metal.

[0046] It should be noted that the composite material of this invention uses foamed metal as a three-dimensional framework. This foamed metal is interconnected by metal ligaments to form a robust and continuous conductive network. Because this network is connected in the X, Y, and Z directions, current can be conducted unimpeded throughout the three dimensions of the material. Furthermore, the porous structure inside the foamed metal is filled with a fluoropolymer, exhibiting a micron-sized spherical structure. Simultaneously, the surface of this spherical structure contains nanoscale pores. The spherical structure and its surface pores highly scatter and reflect sunlight. At the same time, the fluoropolymer has strong infrared absorption in the mid-infrared band, thus exhibiting high infrared emissivity. Therefore, the composite material of this invention is a three-dimensionally highly conductive radiation-cooled composite material, capable of simultaneously achieving efficient electron transport, effective sunlight reflection, and optimal mid-infrared emission.

[0047] As an optional implementation, the foam metal is selected from any one or a combination of at least two of the following: foamed copper (CF), foamed nickel (NF), foamed silver (AF), foamed iron, foamed nickel-iron, foamed nickel-molybdenum, foamed titanium, foamed cobalt-nickel, foamed copper-nickel, foamed zinc, foamed nickel-zinc, and foamed stainless steel.

[0048] As an optional implementation, the porosity of the foamed metal is 90-98%, for example, it can be 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, etc.

[0049] As an optional implementation, the pore size of the foamed metal is 5~130 PPI, for example, it can be 5 PPI, 10 PPI, 20 PPI, 30 PPI, 40 PPI, 50 PPI, 60 PPI, 70 PPI, 80 PPI, 90 PPI, 100 PPI, 110 PPI, 120 PPI, 130 PPI, etc.

[0050] As an optional implementation, the average pore size of the foamed metal is 0.2~5.1 mm, for example, it can be 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 4.5 mm, 5.1 mm, etc.

[0051] As an optional implementation, the thickness of the foamed metal is 1 to 30 mm, for example, it can be 1 mm, 2 mm, 3 mm, 5 mm, 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, etc.

[0052] In a preferred embodiment, the polymer used for radiation cooling is a fluoropolymer.

[0053] As an optional implementation, the fluoropolymer is selected from any one or a combination of at least two of the following: perfluoroethylene-propylene copolymer (FEP), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyperfluoroalkoxy resin, polytrifluoroethylene, polychlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer, and polyvinylidene fluoride.

[0054] In a preferred embodiment, the fluoropolymer is a perfluoroethylene propylene copolymer (FEP).

[0055] As an optional embodiment, the polymer used for radiation cooling is filled at a concentration of 0.5~2 mg / mm². 3 For example, it could be 0.5 mg / mm 3 0.6 mg / mm 3 0.7 mg / mm 3 0.8 mg / mm 3 1 mg / mm 3 1.1 mg / mm 3 1.2 mg / mm 3 1.3 mg / mm 3 1.4 mg / mm 3 1.5 mg / mm 3 1.6 mg / mm 3 1.7 mg / mm 3 1.8 mg / mm 3 1.9 mg / mm 3 2 mg / mm 3 wait.

[0056] As an optional implementation, the average particle size of the polymer used for radiation cooling is 0.5~5 μm, for example, it can be 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, etc.

[0057] As an optional implementation, the polymer used for radiation cooling is a perfluoroethylene-propylene copolymer.

[0058] As an optional implementation, the conductivity of the three-dimensionally highly conductive radiation-cooled composite material is 1.0 × 10⁻⁶. 5 S / m or higher, for example, 1.0 × 10 5 S / m, 1.5×10 5 S / m, 2.0×10 5 S / m, 2.5×10 5 S / m, 3.0×105 S / m, 3.5×10 5 S / m, 4.0×10 5 S / m, 4.2×10 5 S / m, 4.5×10 5 S / m, 5.0×10 5 S / m, 5.5×10 5 S / m, 6.0×10 5 S / m, 6.5×10 5 S / m, 7.0×10 5 S / m, 7.5×10 5 S / m, 8.0×10 5 S / m, 8.5×10 5 S / m, 9.0×10 5 S / m, 9.5×10 5 S / m, 10.0×10 5 S / m, etc.

[0059] As an optional implementation, the infrared emissivity of the three-dimensionally highly conductive radiation-cooled composite material is above 85%, for example, it can be 85.0%, 85.5%, 86.0%, 86.5%, 87.0%, 87.5%, 88.0%, 88.2%, 88.4%, 88.6%, 88.8%, 89.0%, 89.2%, 89.4%, 89.6%, 89.8%, 90.0%, 90.2%, 90.4%, 90.6%, 90.8%, 91.0%, 91.2%, 91.4%, 91.6%, 91.8%, 92.0%, etc.

[0060] As an optional implementation, the solar reflectivity of the three-dimensionally highly conductive radiation-cooled composite material is above 85%, for example, it can be 85.0%, 85.5%, 86.0%, 86.5%, 87.0%, 87.5%, 88.0%, 88.5%, 89.0%, 89.5%, 90.0%, 90.5%, 91.0%, 91.5%, 92.0%, 92.5%, 93.0%, 93.5%, 94.0%, 94.5%, 95.0%, etc.

[0061] In a second aspect, the present invention provides a method for preparing a three-dimensionally highly conductive radiation-cooled composite material as described in the first aspect, the method comprising: A fluoropolymer slurry is placed on the surface of the foam metal and repeatedly coated to penetrate the pore structure of the foam metal, eventually exposing the conductive network of the foam metal on the surface, thus obtaining the filled foam metal. The filled foam metal is preheated, vented, pressurized, and cooled sequentially to obtain the three-dimensionally highly conductive radiation-cooled composite material.

[0062] As an optional implementation, the fluoropolymer slurry comprises a fluoropolymer and a solvent.

[0063] As an optional implementation, the mass ratio of the fluoropolymer to the solvent is 1:(1~2), for example, it can be 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2, etc.

[0064] As an optional implementation, the solvent is selected from any one or a combination of at least two of anhydrous ethanol, n-hexane, acetone, and toluene.

[0065] In a preferred embodiment, the solvent is anhydrous ethanol.

[0066] As an optional implementation, the foamed metal also needs to undergo the following pretreatment steps: The foamed metal was immersed in acetone and hydrochloric acid solutions respectively, ultrasonically cleaned, and then the residual acetone and hydrochloric acid solutions were cleaned and dried to obtain the pretreated foamed metal.

[0067] As an optional implementation, the concentration of the hydrochloric acid solution is 0.5~2 mol / L, for example, it can be 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1.0 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, 2.0 mol / L, etc.

[0068] As an optional implementation, the ultrasonic cleaning time is 5 to 15 minutes, for example, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, 15 minutes, etc.

[0069] As an optional implementation, the specific steps for preparing the filled foam metal are as follows: A fluoropolymer slurry is placed on one side of the foam metal surface, and the fluoropolymer slurry is scraped into the pore structure of the foam metal with a blade, adhering closely to the surface of the foam metal, and then dried. After flipping, repeat the same step on the other side of the foam metal surface, and then repeatedly scrape and coat the foam metal to fill the pore structure with the fluoropolymer slurry, and finally expose the conductive network of the foam metal on the surface to obtain the filled foam metal.

[0070] As an optional implementation, the total amount of the fluoropolymer slurry used is 1~4 mL / cm³. 3 For example, it could be 1 mL / cm 3 1.5 mL / cm 3 2 mL / cm 3 2.5 mL / cm 3 3 mL / cm 3 3.5 mL / cm 3 4 mL / cm 3 wait.

[0071] As an optional implementation, the amount of fluoropolymer slurry used in each coating process is 0.5~2 mL / cm². 3 For example, it could be 0.5 mL / cm 3 0.6 mL / cm 3 0.7 mL / cm 3 0.8 mL / cm 3 1.0 mL / cm 3 1.2 mL / cm 3 1.4 mL / cm 3 1.6 mL / cm 3 1.8 mL / cm 3 2 mL / cm 3 wait.

[0072] As an optional implementation, the total number of scraping applications is 2 to 6 times, for example, 2, 3, 4, 5, or 6 times.

[0073] As an optional implementation, the drying temperature for each drying is 60~80℃, for example, 60℃, 65℃, 70℃, 75℃, 80℃, etc., and the drying time for each drying is 2~5 min, for example, 2 min, 2.5 min, 3 min, 3.5 min, 4 min, 4.5 min, 5 min, etc.

[0074] As an optional implementation, the preheating, venting, and pressure holding are carried out inside a flat vulcanizing machine.

[0075] As an optional implementation, when the polymer used for radiation cooling is a fluoropolymer, the preheating temperature is 170~350℃, for example, it can be 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, etc.

[0076] As an optional implementation, when the polymer used for radiation cooling is a fluoropolymer, the preheating pressure is 4~6 MPa, for example, it can be 4.0 MPa, 4.2 MPa, 4.4 MPa, 4.6 MPa, 4.8 MPa, 5.0 MPa, 5.2 MPa, 5.4 MPa, 5.6 MPa, 5.8 MPa, 6.0 MPa, etc.

[0077] As an optional implementation, when the polymer used for radiation cooling is a fluoropolymer, the preheating time is 10~20 s, for example, 10 s, 11 s, 12 s, 13 s, 14 s, 15 s, 16 s, 17 s, 18 s, 19 s, 20 s, etc.

[0078] Thirdly, the present invention provides the application of a three-dimensionally highly conductive radiation-cooled composite material as described in the first aspect in the preparation of articles for cooling.

[0079] The present invention will be further illustrated below by way of examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.

[0080] The parameters of the raw materials for the following examples and comparative examples are shown in Table 1 below: Table 1

[0081] Example 1 This embodiment provides a three-dimensionally highly conductive radiation-cooled composite material, which is prepared by the following steps: (1) Cut the copper foam (CF) into 6 cm × 6 cm × 2 mm pieces, immerse them in acetone and 1 mol / L HCl solution respectively, and clean them in an ultrasonic cleaner for 10 min each. Then wash the surface of the acetone and hydrochloric acid residue with distilled water and anhydrous ethanol respectively, and dry the CF for later use.

[0082] (2) The perfluoroethylene propylene copolymer (FEP) powder (average particle size 1.3 μm) and anhydrous ethanol are stirred into a slurry with a mass ratio of 5:5.

[0083] (3) Take an appropriate amount of the above slurry and place it on the surface of the copper foam (CF). Use a blade to scrape the mixture tightly into the porous structure of the foam metal, and let it air dry naturally. Then, turn the foam metal over to the back and repeat the above scraping and drying steps. Through repeated scraping, the interior of the foam metal is filled with perfluoroethylene propylene copolymer (FEP), while the conductive network of the foam metal on the surface is exposed, forming a three-dimensional conductive network, thus obtaining the filled copper foam metal. In each scraping process, the amount of FEP slurry used is 0.75 mL / cm. 3 The total number of coats was 4, and the total amount of slurry used was 3 mL / cm². 3 The drying temperature was 70℃ each time, and the drying time was 3 minutes each time.

[0084] (4) Place the filled foamed copper metal obtained in step (3) into a mold, put it into a flat vulcanizing machine, preheat it for 15 s at 270℃ and 5 MPa, exhaust it once, hold it under pressure for 25 s at 270℃ and 5 MPa, and after cooling, obtain the three-dimensional high conductivity radiation cooling composite material (denoted as CFF).

[0085] Figure 1 The EDS spectrum of the surface of the three-dimensionally highly conductive radiation-cooled composite material provided in Example 1, with blue, red, and yellow markings representing Cu, C, and F elements, respectively; as shown Figure 1 As shown, the red markers (C) and yellow markers (F) together represent the fluoropolymers filling the porous structure of the foamed metal. Their distribution fills the voids in the blue-marked (Cu) copper network, visually demonstrating the composite structure "filled within the porous structure" and the fact that the Cu network surface is free of FEP coverage, thus enabling efficient electron transport.

[0086] Figure 2 The scanning electron microscope (SEM) image of the three-dimensionally highly conductive radiation-cooled composite material provided in Embodiment 1 of the present invention; as shown. Figure 2 As shown, FEP exhibits a spherical structure with pores on its surface. Both the spherical structure and its surface pores can reflect sunlight, thereby increasing reflectivity. At the same time, FEP has high infrared emissivity, thus giving the sample the ability to radiatively cool.

[0087] Example 2 This embodiment provides a three-dimensionally highly conductive radiation-cooled composite material, which is prepared by the following steps: (1) Cut the nickel foam (NF) into 6 cm × 6 cm × 2 mm pieces, immerse them in acetone and 1 mol / L HCl solution respectively, and clean them in an ultrasonic cleaner for 10 min each. Then wash the surface of residual acetone and hydrochloric acid with distilled water and anhydrous ethanol respectively, and dry the NF for later use.

[0088] (2) The perfluoroethylene propylene copolymer (FEP) powder (average particle size 1.3 μm) and anhydrous ethanol are stirred into a slurry with a mass ratio of 5:5.

[0089] (3) Take an appropriate amount of the above slurry and place it on the surface of the nickel foam (NF). Use a blade to scrape the mixture tightly into the porous structure of the foam metal, and let it air dry naturally. Then, turn the foam metal over to the back and repeat the above scraping and drying steps. By repeatedly scraping, the interior of the foam metal is filled with perfluoroethylene propylene copolymer (FEP), while the conductive network of the foam metal on the surface is exposed, forming a three-dimensional conductive network, thus obtaining the filled nickel foam (NF). In each scraping process, the amount of FEP slurry used is 0.75 mL / cm. 3 The total number of coats was 4, and the total amount of slurry used was 3 mL / cm². 3 The drying temperature was 70℃ each time, and the drying time was 3 minutes each time.

[0090] (4) Place the filled nickel foam obtained in step (3) into a mold, put it into a flat vulcanizing machine, preheat it for 15 s at 270℃ and 5MPa, exhaust it once, hold it under pressure for 25 s at 270℃ and 5MPa, and after cooling, obtain the three-dimensional high conductivity radiation cooling composite material (denoted as NFF).

[0091] Example 3 This embodiment provides a three-dimensionally highly conductive radiation-cooled composite material, which is prepared by the following steps: (1) Cut the foam silver (AF) into 6 cm × 6 cm × 2 mm pieces, immerse them in acetone and 1 mol / L HCl solution respectively, and clean them in an ultrasonic cleaner for 10 min each. Then wash the surface of the acetone and hydrochloric acid residue with distilled water and anhydrous ethanol respectively, and dry the AF for later use.

[0092] (2) The perfluoroethylene propylene copolymer (FEP) powder (average particle size 1.3 μm) and anhydrous ethanol are stirred into a slurry with a mass ratio of 5:5.

[0093] (3) Take an appropriate amount of the above slurry and place it on the surface of the foamed silver (AF). Use a blade to scrape the mixture tightly into the porous structure of the foamed metal, and let it air dry naturally. Then, turn the foamed metal over to the back and repeat the above scraping and drying steps. By repeatedly scraping, the interior of the foamed metal is filled with perfluoroethylene propylene copolymer (FEP), while the conductive network of the foamed metal on the surface is exposed, forming a three-dimensional conductive network, thus obtaining the filled foamed silver (AF). In each scraping process, the amount of FEP slurry used is 0.7 mL / cm. 3 The total number of coats was 4, and the total amount of slurry used was 2.8 mL / cm². 3 The drying temperature was 70℃ each time, and the drying time was 3 minutes each time.

[0094] (4) Place the filled foam silver obtained in step (3) into the mold, put it into the flat vulcanizing machine, preheat it for 15 s at 270℃ and 5MPa, exhaust it once, hold it under pressure for 25 s at 270℃ and 5MPa, and after cooling, obtain the three-dimensional high conductivity radiation cooling composite material (denoted as AFF).

[0095] Example 4 This embodiment provides a three-dimensionally highly conductive radiation-cooled composite material, which is prepared by the following steps: (1) Cut the copper foam (CF) into 6 cm × 6 cm × 2 mm pieces, immerse them in acetone and 1 mol / L HCl solution respectively, and clean them in an ultrasonic cleaner for 10 min each. Then wash the surface of the acetone and hydrochloric acid residue with distilled water and anhydrous ethanol respectively, and dry the CF for later use.

[0096] (2) Mix polytetrafluoroethylene (PTFE) powder and anhydrous ethanol into a slurry with a mass ratio of 5:5.

[0097] (3) Take an appropriate amount of the above slurry and place it on the surface of the foamed copper (CF). Use a blade to scrape the mixture tightly into the porous structure of the foamed metal, and let it air dry naturally. Then, turn the foamed metal over to the back and repeat the above scraping and drying steps. By repeatedly scraping, the interior of the foamed metal is filled with polytetrafluoroethylene (PTFE), while the conductive network of the foamed metal on the surface is exposed, forming a three-dimensional conductive network, and the filled foamed copper is obtained. In each scraping process, the amount of PTFE slurry used is 0.75 mL / cm 3 The total number of coats was 4, and the total amount of slurry used was 3 mL / cm². 3 The drying temperature was 70℃ each time, and the drying time was 3 minutes each time.

[0098] (4) Place the filled foamed copper metal obtained in step (3) into a mold, put it into a flat vulcanizing machine, preheat it for 15 s at 350℃ and 5 MPa, exhaust it once, hold it under pressure for 25 s at 350℃ and 5 MPa, and after cooling, obtain the three-dimensional high conductivity radiation cooling composite material (denoted as CF / PTFE).

[0099] Example 5 This embodiment provides a three-dimensionally highly conductive radiation-cooled composite material, which is prepared by the following steps: (1) Cut the copper foam (CF) into 6 cm × 6 cm × 2 mm pieces, immerse them in acetone and 1 mol / L HCl solution respectively, and clean them in an ultrasonic cleaner for 10 min each. Then wash the surface of the acetone and hydrochloric acid residue with distilled water and anhydrous ethanol respectively, and dry the CF for later use.

[0100] (2) Mix polyvinylidene fluoride (PVDF) powder and anhydrous ethanol into a slurry with a mass ratio of 5:5.

[0101] (3) Take an appropriate amount of the above slurry and place it on the surface of the copper foam (CF). Use a blade to scrape the mixture tightly into the porous structure of the foam metal, and let it air dry naturally. Then, turn the foam metal over to the back and repeat the above scraping and drying steps. By repeatedly scraping, the foam metal is filled with vinylidene fluoride (PVDF), while the conductive network of the foam metal on the surface is exposed, forming a three-dimensional conductive network, and the filled copper foam metal is obtained. In each scraping process, the amount of PVDF slurry used is 0.8 mL / cm 3 The total number of coats was 4, and the total amount of slurry used was 3.2 mL / cm². 3 The drying temperature was 70℃ each time, and the drying time was 3 minutes each time.

[0102] (4) Place the filled foamed copper metal obtained in step (3) into a mold, put it into a flat vulcanizing machine, preheat it for 20 s at 170℃ and 5 MPa, exhaust it once, hold it under pressure for 25 s at 170℃ and 5 MPa, and after cooling, obtain the three-dimensional high conductivity radiation cooling composite material (denoted as CF / PVDF).

[0103] Comparative Example 1 This comparative example is provided in metallic copper (Cu), cut to size 6 cm × 6 cm × 2 mm.

[0104] Comparative Example 2 This comparative example is provided in foamed copper (CF, cut to size 6 cm × 6 cm × 2 mm).

[0105] Test Example 1 Spectral Characteristic Test Test samples: Three-dimensional highly conductive radiation cooling composite material provided in Examples 1-5, copper metal (Cu) provided in Comparative Example 1, and copper foam (CF) provided in Comparative Example 2.

[0106] Test method: The solar reflectance (0.3~2.5 µm) of the samples was measured using a UV-Vis-NIR spectrophotometer (Lambda 1050+) equipped with an integrating sphere. The infrared reflectance and transmittance of the samples in the wavelength range of 2~20 µm were measured using a Fourier transform infrared spectrometer (Spotlight 200i) equipped with a gold-plated integrating sphere, and the infrared emissivity was further calculated.

[0107] Specific test results are as follows: Figures 3-5 And as shown in Table 2 below: Table 2

[0108] As shown in Table 2, the infrared emissivity of the three-dimensionally highly conductive radiative cooling composite material is above 88%, and the solar reflectivity is above 85%. This indicates that the three-dimensionally highly conductive radiative cooling composite material of the present invention not only has high emissivity in the mid-infrared range for effective radiative heat transfer, but also high reflectivity in the solar spectrum. Therefore, it can minimize the absorption of sunlight, avoid the rise in material temperature, and thus achieve radiative cooling.

[0109] Test Example 2 Outdoor testing Test samples: Three-dimensional highly conductive radiation cooling composite material provided in Example 1, copper metal (Cu) provided in Comparative Example 1, and copper foam (CF) provided in Comparative Example 2. Test Method: A test device for outdoor performance evaluation was designed, consisting of an aluminized polyester film and polystyrene (PS) foam insulation (15×15×15 cm). 3 It consists of a PS foam layer and a transparent low-density polyethylene (LDPE) film. The PS foam layer acts to suppress heat conduction from the surrounding environment. To test the air temperature beneath the sample, a groove (6×6×0.2 cm) was machined on the top surface of the foam. 3The entire apparatus was encased in a 0.6 mm thick aluminized polyester film to minimize radiative heat absorption, while a transparent LDPE film sealed the sample chamber to limit convective heat exchange. Temperature data for both the sample and ambient air were continuously recorded using a type K thermocouple connected to a temperature recorder (PicoScope TC-08, UK). Solar irradiance was measured using a TES1333R radiometer, and wind speed and relative humidity were monitored in real-time using a PM6252B digital anemometer.

[0110] Test results: as follows Figure 6 As shown, at noon, the temperature of the three-dimensionally highly conductive radiation-cooled composite material provided in Example 1 is approximately 5.8°C lower than the ambient temperature, 27.1°C lower than the conventional conductor Cu, and 27.7°C lower than CF. Therefore, it represents a significant advancement in the field of metalloid conductive radiation cooling, making a substantial contribution to the world's sustainable development and possessing immense application value.

[0111] Test Example 3 Conductivity test Test samples: Three-dimensionally highly conductive radiation-cooled composite materials provided in Examples 1-3; Test method: The resistance of the sample was measured using a digital multimeter (DMM4050 6-1 / 2, Tektronix, Inc.). The sample was cut into 6×6×0.2 cm pieces. 3 A rectangular sample was used. The Kelvin four-wire method was employed for testing. The sample was clamped at both ends and connected to a multimeter to measure its resistance. The conductivity was then calculated.

[0112] Specific test results are as follows: Figure 7 And as shown in Table 3 below: Table 3

[0113] As shown in Table 3, the electrical conductivity of the three-dimensionally highly conductive radiation-cooled composite material of the present invention is 4.2 × 10⁻⁶. 5 S / m or higher; and the CFF provided in Example 1 has a conductivity as high as 1.1 × 10⁻⁶. 6 It has reached the conductivity level of metals.

[0114] Test Example 4 Water contact angle test Test samples: Three-dimensionally highly conductive radiation-cooled composite materials provided in Examples 1-3; Test method: The water contact angle of the sample was tested using a droplet contact angle meter (JC2000C1). The droplet volume was approximately 5 μL, and the test temperature was room temperature.

[0115] Specific test results are as follows: Figure 8 And as shown in Table 4 below: Table 4

[0116] As shown in Table 3, the water contact angles of the three-dimensionally highly conductive radiation-cooled composite materials of this invention are all above 144°, and the CFF water contact angle provided in Example 1 reaches 159.3°, achieving a superhydrophobic level. This indicates that the foam metal itself provides a micron-level rough framework. After polymer filling, a more complex microstructure may be formed on the surface. The contact angle data proves that the roughness formed by this composite, combined with low surface energy chemistry, perfectly creates the conditions required for excellent hydrophobic performance. The hydrophobic surface means that rainwater or tiny dewdrops can easily roll off, carrying away surface contaminants in the process. This ensures the long-term stability and durability of the material's cooling performance, maintaining high efficiency even in complex outdoor environments. The hydrophobic surface effectively blocks water vapor and liquid water from contacting the internal metal framework, providing excellent corrosion and moisture protection. This protects the integrity of the three-dimensional conductive network, ensuring the long-term stability of the material's conductivity.

[0117] 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 them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A three-dimensionally highly conductive radiation-cooled composite material, characterized in that, The three-dimensionally highly conductive radiation-cooled composite material includes: a foamed metal and a polymer for radiation cooling filled within the porous structure of the foamed metal.

2. The three-dimensionally highly conductive radiation-cooled composite material according to claim 1, characterized in that, The foam metal is selected from any one or a combination of at least two of the following: foam copper, foam nickel, foam silver, foam iron, foam nickel iron, foam nickel molybdenum, foam titanium, foam cobalt nickel, foam copper nickel, foam zinc, foam nickel zinc, and foam stainless steel. Preferably, the porosity of the foam metal is 90-98%, the pore size of the foam metal is 5-130 PPI, the average pore diameter of the foam metal is 0.2-5.1 mm, and the thickness of the foam metal is 1-30 mm.

3. The three-dimensionally highly conductive radiation-cooled composite material according to claim 1, characterized in that, The polymer used for radiation cooling is a fluoropolymer; Preferably, the fluoropolymer is selected from any one or a combination of at least two of the following: perfluoroethylene propylene copolymer, polytetrafluoroethylene, polyvinylidene fluoride, polyperfluoroalkoxy resin, polychlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer, and polyvinyl fluoride, and is preferably a perfluoroethylene propylene copolymer; Preferably, the polymer used for radiation cooling is filled at a concentration of 0.5~2 mg / mm³. 3 ; Preferably, the average particle size of the polymer used for radiation cooling is 0.5~5 μm.

4. The three-dimensionally highly conductive radiation-cooled composite material according to claim 1, characterized in that, The conductivity of the three-dimensionally highly conductive radiation-cooled composite material is 1.0 × 10⁻⁶. 5 S / m or higher; Preferably, the infrared emissivity of the three-dimensionally highly conductive radiation-cooled composite material is above 85%; and the solar reflectivity of the three-dimensionally highly conductive radiation-cooled composite material is above 85%.

5. A method for preparing a three-dimensionally highly conductive radiation-cooled composite material according to any one of claims 1 to 4, characterized in that, The preparation method includes: A fluoropolymer slurry is placed on the surface of the foam metal and repeatedly coated to penetrate the pore structure of the foam metal, eventually exposing the conductive network of the foam metal on the surface, thus obtaining the filled foam metal. The filled foam metal is preheated, vented, pressurized, and cooled sequentially to obtain the three-dimensionally highly conductive radiation-cooled composite material.

6. The method for preparing the three-dimensionally highly conductive radiation-cooled composite material according to claim 5, characterized in that, The fluoropolymer slurry comprises a fluoropolymer and a solvent; Preferably, the mass ratio of the fluoropolymer to the solvent is 1:(1~2); Preferably, the solvent is selected from any one or a combination of at least two of anhydrous ethanol, n-hexane, acetone, and toluene, with anhydrous ethanol being the most preferred.

7. The method for preparing a three-dimensionally highly conductive radiation-cooled composite material according to claim 5, characterized in that, The foamed metal also needs to undergo the following pretreatment steps: The foamed metal was immersed in acetone and hydrochloric acid solutions respectively, ultrasonically cleaned, and then the residual acetone and hydrochloric acid solutions were cleaned and dried to obtain the pretreated foamed metal. Preferably, the concentration of the hydrochloric acid solution is 0.5~2 mol / L; Preferably, the ultrasonic cleaning time is 5 to 15 minutes.

8. The method for preparing a three-dimensionally highly conductive radiation-cooled composite material according to claim 5, characterized in that, The specific steps for preparing the filled foam metal are as follows: A fluoropolymer slurry is placed on one side of the foam metal surface, and the fluoropolymer slurry is scraped into the pore structure of the foam metal with a blade, adhering closely to the surface of the foam metal, and then dried. After flipping, repeat the same step on the other side of the foam metal. Then, by repeatedly scraping and coating, the pore structure of the foam metal is filled with the fluoropolymer slurry, and finally the conductive network of the foam metal on the surface is exposed to obtain the filled foam metal. Preferably, the total amount of the fluoropolymer slurry used is 1~4 mL / cm³. 3 ; Preferably, the amount of fluoropolymer slurry used in each coating process is 0.5~2 mL / cm². 3 ; Preferably, the total number of coat strokes is 2 to 6. Preferably, the drying temperature is 60~80℃ each time, and the drying time is 2~5 min each time.

9. The method for preparing a three-dimensionally highly conductive radiation-cooled composite material according to claim 5, characterized in that, The preheating, venting, and pressure holding are carried out inside the flat vulcanizing machine; Preferably, when the polymer used for radiation cooling is a fluoropolymer, the preheating temperature is 170~350°C, the preheating pressure is 4~6 MPa, and the preheating time is 10~20 s.

10. The use of a three-dimensionally highly conductive radiation-cooled composite material according to any one of claims 1 to 4 in the preparation of articles for cooling.

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