A three-dimensional interconnected network heat-conducting and wave-absorbing foam material and its preparation method and application

Abstract

The present invention discloses a three-dimensional interconnected network thermally conductive and wave-absorbing foam material, its preparation method, and application, belonging to the field of nanomaterial technology. The present invention utilizes a bubble-assisted combustion method, utilizing a low-decomposition-temperature metal salt with the assistance of a high-boiling-point polyol to prepare the three-dimensional interconnected network thermally conductive and wave-absorbing foam material. Not only is the preparation method simple and the product structure novel, but a series of thermally conductive and wave-absorbing foam materials with three-dimensional interconnected network structures can also be prepared by varying the types of salt and polyol, the calcination temperature, the heating rate, and the molar ratio of different salts in the initial reactants, thereby enabling simple control of the product morphology, texture, and performance. Furthermore, the preparation method disclosed in the present invention not only has mild and safe reaction conditions but also high yield, overcoming the problems of harsh reaction conditions, difficult-to-control reaction product morphology, and poor experimental reproducibility in previous preparation processes. The method has certain versatility and good potential for industrial application.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanomaterials and relates to a preparation method of a three-dimensional interconnected network heat-conducting and wave-absorbing foam material and its application in the fields of heat management and microwave absorption, sensors, catalysis, supercapacitors or lithium-ion batteries. Background Art

[0002] With the rapid development of modern science and assembly technology, the size of electronic products has been miniaturized and reduced, and integrated circuits are developing towards multifunctionality and high integration. The power density within the system is getting higher and higher. As a result, the electromagnetic compatibility and heat dissipation problems of electronic devices are becoming increasingly serious. Research and preparation of thermal conductive and wave-absorbing materials with dual functional properties has become a new trend in solving this problem.

[0003] Traditional integrated thermally conductive and absorbing materials are usually achieved by adding absorbers and thermally conductive fillers to a base material at the same time. However, there is an upper limit to the total amount of functional fillers added to the base material. Increasing the amount of one type of filler (thermal conductive or absorbing) will inevitably lead to a decrease in the amount of another type of filler, resulting in a contradiction between the thermal conductivity and absorbing properties of the thermally conductive and absorbing materials.

[0004] Currently, the development of thermally conductive and absorbing materials relies solely on balancing the thermal conductivity and absorption performance of the materials by comprehensively coordinating the addition ratio of the two fillers. This fails to meet the requirements of sensitive electronic devices for materials that combine electromagnetic wave absorption with efficient heat conduction. Furthermore, the enhancement mechanisms of thermal conductivity and absorption are contradictory. For example, high electrical conductivity improves the material's thermal conductivity, but it also reduces the material's impedance matching and electrical insulation capabilities, hindering its absorption performance and significantly limiting its development. Designing material components and structures to create a single powder filler with true dual thermal conductivity and absorption properties, while addressing the challenges of selecting composite fillers and adjusting the composition ratio during production, has become a future research and development direction for thermally conductive and absorbing materials.

[0005] Porous, three-dimensional, interconnected reticular foam structures have the characteristics of low apparent density, adjustable pores, and compressibility, playing an important role in many fields such as adsorption, catalysis, and electrochemistry. It is reported that porous structures facilitate the multiple reflections and scattering of electromagnetic waves within the material. At the same time, by adjusting the size and density of the pores, the impedance matching of the absorbing material can be optimized, thereby further improving its electromagnetic wave absorption performance, showing broad development and application prospects in the field of electromagnetic wave absorption. At the same time, the porous three-dimensional interconnected network provides a thermal conductivity pathway, playing an important role in improving the thermal conductivity efficiency of the prepared material and reducing the contact thermal resistance within the composite material. However, there is currently very little research in the field of integrated thermal conductive and wave absorbing materials.

[0006] Chinese patent literature (CN111217586A) discloses a kind of graphene / multi-walled carbon nanotube composite wave-absorbing foam and preparation method thereof, after the raw materials such as graphene oxide and carboxylated multi-walled carbon nanotubes are ultrasonically dispersed into water, alcoholic solvent is added and stirred evenly, then placed in a vacuum environment and left to stand for treatment and freeze-dried and thermally reduced to obtain, but the required time is long and the process is cumbersome. Chinese patent literature (CN 113880601A) discloses a kind of magnesium oxysulfate cement-based foam wave-absorbing plate and preparation method thereof, by adding foaming agent, foam stabilizer, composite modifier and wave-absorbing material, comprehensive proportioning, finally obtain and have good wave-absorbing performance, low density, high thermal conductivity, the wave-absorbing plate with compressive strength concurrently. But this method operation is too cumbersome, is unfavorable for large-scale use in actual production life, and engineering cost is higher. In addition, a Chinese patent document (CN114133700A) uses a thermosetting resin, an absorbent, a diluent, and a thermally conductive filler as raw materials, and forms a porous slurry by introducing supercritical carbon dioxide gas, which is then solidified and foamed to obtain a high-efficiency, lightweight electromagnetic absorption material with a closed-cell structure. However, this method is cumbersome and the pore size distribution of the resulting product is uneven.

[0007] Therefore, how to develop a porous three-dimensional interconnected network thermally conductive and wave-absorbing foam material with simple process, easy industrialization, controllable morphology and size, and excellent performance is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0008] In view of this, the purpose of the present invention is to address the problems existing in the prior art and provide a three-dimensional interconnected network heat-conducting and wave-absorbing foam material with simple process and controllable morphology.

[0009] In order to achieve the above object, the technical solution of the present invention is as follows:

[0010] A three-dimensional interconnected network heat-conducting and wave-absorbing foam material is prepared by a bubble-assisted combustion method; the structure of the heat-conducting and wave-absorbing foam material is a porous three-dimensional interconnected network structure, and the average pore size of the three-dimensional interconnected network structure is 3.36 to 37.45 nm, and the specific surface area is 13.29 to 222.86 m 2 ·g -1 , carbon accounts for 12.95% to 51.03% in the composite.

[0011] Preferably, the bubble-assisted combustion method is as follows: a soluble metal salt is dissolved and dispersed in a polyol aqueous solution, and then the salt solution is transferred to an ark and calcined to obtain the three-dimensional interconnected network-like heat-conducting and wave-absorbing foam material.

[0012] The specific process principles are as follows:

[0013] The bubble-assisted combustion method is used to prepare one or more metal salts with low decomposition temperature, mainly nitrates or a mixture of nitrates and other soluble salts, which are decomposed in a high-boiling polyol solution to produce a large number of bubbles at low temperatures, making the product present a three-dimensional porous network structure; and at high temperatures, the polyol is carbonized into carbon, and the carbon thermal reduction of the metal oxide is achieved at the same time.

[0014] The present invention discloses a three-dimensional interconnected network thermally conductive and wave-absorbing foam material prepared using a bubble-assisted combustion process. The material not only has a novel structure, a simple formation mechanism, and a simple preparation method, but also can be used to prepare a series of thermally conductive and wave-absorbing foam materials having a three-dimensional interconnected network structure by varying the types of salt and polyol, the calcination temperature, the heating rate, and the molar ratio of different salts in the initial reactants. The prepared three-dimensional interconnected network thermally conductive and wave-absorbing foam material has an average pore diameter of 3.36 to 37.45 nm. Furthermore, the three-dimensional interconnected network thermally conductive and wave-absorbing foam has multiple relaxation polarizations and good impedance matching, thus showing great potential in the field of wave absorption.

[0015] Furthermore, the three-dimensional interconnected network structure heat-conducting and absorbing foam material disclosed in the present invention has excellent microwave absorption properties, wherein the maximum effective bandwidth with a reflectivity of less than or equal to -10dB is 5.04 to 13.92GHz, the maximum absorption is -32.17 to -59.42dB, and the thickness is 2.0 to 3.8mm.

[0016] In addition, the three-dimensional interconnected network structure heat-conducting and wave-absorbing foam material prepared by the present invention has excellent thermal conductivity, and its thermal conductivity, thermal diffusivity and specific heat can reach 4.792~5.654W / (m·K), 4.172~5.417mm 2 / s and 0.927~1.149MJ / m 3 K.

[0017] Another object of the present invention is to provide a method for preparing a three-dimensional interconnected network foam thermal conductive and wave absorbing integrated material that has a simple and safe preparation process, strong versatility, controllable morphology, and is suitable for industrial production.

[0018] In order to achieve the above object, the present invention adopts the following technical solutions:

[0019] A method for preparing a three-dimensional interconnected network heat-conducting and wave-absorbing foam material, the method specifically comprising the following steps:

[0020] A soluble metal salt is weighed according to a certain stoichiometric amount and stirred and dissolved in a polyol aqueous solution to prepare a mixed solution. The solution is then transferred to an ark, sealed with a lid, and placed in a tubular furnace for calcination. The temperature is increased at a certain heating rate and kept at a certain temperature for a certain time under the protection of an inert gas to obtain a three-dimensional interconnected network heat-conducting and wave-absorbing foam material.

[0021] By adopting the above technical solution, the beneficial effects of the present invention are as follows:

[0022] The preparation method disclosed in the present invention is simple to operate and has a novel product morphology. It overcomes the characteristics of previous preparation processes, such as harsh reaction conditions, difficult to control the morphology of the reaction product, and poor experimental repeatability. In addition, the product composition, texture, and performance can be regulated by changing the types of soluble metal salts and polyols, the calcination temperature and rate, and the molar ratio of different salts in the initial reactants. The method has certain versatility and good potential for industrial application.

[0023] Preferably, the stirring time is 10 to 30 minutes.

[0024] Preferably, the calcination temperature in the tube furnace is 500° C. to 700° C., the heating rate is 2 to 5° C. / min, and the holding time is 1 to 4 hours.

[0025] Preferably, the ark is a high-temperature resistant jade or ceramic ark, and the inert gas is argon, nitrogen or a mixture thereof.

[0026] Further preferably, the soluble metal salt is one or more of cobalt nitrate, manganese nitrate, copper nitrate, nickel nitrate, iron nitrate, nickel sulfate, magnesium chloride, and nickel acetylacetonate, and the total concentration of the soluble metal salt is 1.083 to 2.165 mol / L.

[0027] More preferably, the polyol in the polyol aqueous solution is one or more of ethylene glycol and glycerol, and the volume ratio of the polyol to water is 0.5-2.

[0028] Another object of the present invention is to provide applications of the three-dimensional interconnected network heat-conducting and wave-absorbing foam material in the fields of microwave absorption, heat conduction, sensors, supercapacitors, photocatalysis or lithium-ion batteries.

[0029] As can be seen from the above technical solutions, compared with the prior art, the present invention provides a three-dimensional interconnected network heat-conducting and wave-absorbing foam material and its preparation method and application, which have the following excellent effects:

[0030] 1) The present invention adopts the bubble-assisted combustion method for the first time to prepare a three-dimensional interconnected network of thermally conductive and wave-absorbing foam materials, which can easily control their composition, texture and thermal conductive-wave-absorbing properties.

[0031] 2) The three-dimensional interconnected network-shaped thermally conductive and absorbing foam material disclosed in the present invention has both dielectric and magnetic losses and good impedance matching. Furthermore, due to its phonon / electron dual heat conduction and unique three-dimensional interconnected network-shaped thermally conductive network, it exhibits excellent electromagnetic wave absorption and thermal conductivity properties. It is expected to become an integrated thermal conductive and absorbing material with broad application potential in the fields of thermal conduction and absorbing.

[0032] 3) The preparation method of the three-dimensional interconnected network thermally conductive and wave-absorbing foam material of the present invention is simple and unique, and the raw materials are cheap and easily available. The reaction process is simple, the cycle is short, the energy consumption is low, the reaction steps are concise, the formation is done in one step, the yield is high, the synthesis conditions are mild, the reproducibility is good, the requirements for synthesis equipment are low, and it has good potential for industrial application.

[0033] Therefore, in summary, the three-dimensional interconnected network heat-conducting and wave-absorbing foam material and the preparation method thereof disclosed and protected by the present invention have great market promotion and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0035] Figures 1 to 3 The phase, composition and morphology of the product obtained in Example 1 of the present invention were measured by XRD, EDX and scanning electron microscope respectively.

[0036] Figures 4 to 6 The phase, composition and morphology of the product obtained in Example 2 of the present invention measured by XRD, EDX and scanning electron microscope are respectively.

[0037] Figures 7 to 9 The phase, composition and morphology of the product obtained in Example 3 of the present invention were measured by XRD, EDX and scanning electron microscope respectively.

[0038] Figures 10 to 12 These are the phase, composition and morphology of the product obtained in Example 4 of the present invention measured under XRD, EDX and scanning electron microscope.

[0039] Figures 13 to 15 These are the phase, composition and morphology of the product obtained in Example 5 of the present invention measured under XRD, EDX and scanning electron microscope.

[0040] Figure 16 The morphology of the product obtained in Example 6 of the present invention was measured under a scanning electron microscope.

[0041] Figure 17 The morphology of the product obtained in Example 7 of the present invention was measured under a scanning electron microscope.

[0042] Figure 18 The morphology of the product obtained in Example 8 of the present invention was measured under a scanning electron microscope.

[0043] Figure 19The morphology of the product obtained in Example 9 of the present invention was measured under a scanning electron microscope.

[0044] Figure 20 The morphology of the product obtained in Example 10 of the present invention was measured under a scanning electron microscope.

[0045] Figure 21 The morphology of the product obtained in Example 11 of the present invention was measured under a scanning electron microscope.

[0046] Figure 22 The morphology of the product obtained in Example 12 of the present invention was measured under a scanning electron microscope.

[0047] Figure 23 The morphology of the product obtained in Example 13 of the present invention was measured under a scanning electron microscope.

[0048] Figure 24 This is the morphology of the product obtained in Example 14 of the present invention measured under a scanning electron microscope.

[0049] Figure 25 This is the morphology of the product obtained in Example 15 of the present invention measured under a scanning electron microscope.

[0050] Figures 26 to 28 These are the phase, composition and morphology of the product obtained in Example 16 of the present invention measured under XRD, EDX and scanning electron microscope.

[0051] Figure 29 The morphology of the product obtained in Example 17 of the present invention was measured under a scanning electron microscope.

[0052] Figure 30 This is the morphology of the product obtained in Example 18 of the present invention measured under a scanning electron microscope.

[0053] Figure 31 This is the morphology of the product obtained in Example 19 of the present invention measured under a scanning electron microscope. DETAILED DESCRIPTION

[0054] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0055] The embodiment of the present invention discloses a three-dimensional porous network structure heat-conducting and wave-absorbing foam material with simple process, controllable size and good microwave absorption and thermal conductivity properties, as well as a preparation method and application thereof.

[0056] For a better understanding of the present invention, the present invention is further specifically described below through the following examples, but it should not be understood as limiting the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above invention content are also considered to fall within the scope of protection of the present invention.

[0057] The technical solution of the present invention will be further described below in conjunction with specific embodiments.

[0058] Example 1

[0059] A method for preparing a three-dimensional interconnected network structure MgO / Co / C foam material, specifically comprising the following steps:

[0060] 1.998g of magnesium nitrate hexahydrate and 0.252g of cobalt nitrate hexahydrate were dissolved in 4mL of ethylene glycol aqueous solution (v:v = 1:1) and magnetically stirred for 30 minutes to thoroughly mix to obtain a clear and transparent nitrate mixed solution with a molar ratio of magnesium and cobalt ions of 9:1. Subsequently, the solution was transferred to an ark, sealed with a lid, and placed in a tube furnace. It was calcined at 600°C (heating rate of 2°C / min) in an argon atmosphere for 2 hours and naturally cooled to room temperature to obtain a three-dimensional porous network structure MgO / Co / C foam material.

[0061] The phase, composition and morphology of the obtained products measured by XRD, EDX and scanning electron microscopy are as follows: Figures 1 to 3 As shown in the above analysis, the product has a porous three-dimensional interconnected network foam structure with an average pore size of 7.97nm and a Co / Mg atomic ratio of 0.172. The specific surface area of the sample was analyzed by a specific surface area tester and was 102.94m 2 ·g -1 .

[0062] As shown in Table 1, the obtained porous three-dimensional interconnected network structure MgO / Co / C foam material has excellent microwave absorption properties, wherein the maximum effective bandwidth with a reflectivity of less than or equal to -10 dB is 10.00 GHz and the maximum absorption is -40.00 dB, corresponding to a thickness of 3.5 mm.

[0063] In addition, the porous three-dimensional interconnected network structure MgO / Co / C foam material also has excellent thermal conductivity, and its thermal conductivity, thermal diffusivity and specific heat can reach 5.573W / (m·K), 5.076mm 2 / s and 1.098MJ / m 3 K, as shown in Table 2.

[0064] Example 2

[0065] A method for preparing a porous three-dimensional interconnected network structure MgO / Co / C foam material. Other conditions remain unchanged, and the mass of magnesium nitrate hexahydrate is changed to 1.554 g, the mass of cobalt nitrate hexahydrate is changed to 0.756 g, and the molar ratio of magnesium ions to cobalt ions in the obtained solution is 7:3.

[0066] The phase, composition and morphology of the obtained products measured by XRD, EDX and scanning electron microscopy are as follows: Figures 4-6 As shown. From the above analysis, it can be seen that the product has a porous three-dimensional interconnected network foam structure with an average pore size of 4.35nm and a Co / Mg atomic ratio of 1.328. The specific surface area of the sample was analyzed by a specific surface area tester and was 222.86m 2 ·g -1 .

[0067] As shown in Table 1, the obtained porous three-dimensional interconnected network structure MgO / Co / C foam material has excellent microwave absorption properties, wherein the maximum effective bandwidth with a reflectivity of less than or equal to -10 dB is 6.48 GHz and the maximum absorption is -32.17 dB, corresponding to a thickness of 2.0 mm.

[0068] In addition, the porous three-dimensional interconnected network structure MgO / Co / C foam material also has excellent thermal conductivity, and its thermal conductivity, thermal diffusivity and specific heat can reach 4.81W / (m·K), 5.197mm 2 / s and 0.9265MJ / m 3 K, as shown in Table 2.

[0069] Example 3

[0070] A method for preparing a porous three-dimensional interconnected network structure MgO / Co / C foam material. Other conditions remain unchanged, and the mass of magnesium nitrate hexahydrate is changed to 1.11 g, the mass of cobalt nitrate hexahydrate is changed to 1.26 g, and the molar ratio of magnesium ions to cobalt ions in the obtained solution is 5:5.

[0071] The phase, composition and morphology of the obtained products measured by XRD, EDX and scanning electron microscopy are as follows: Figures 7-9 As shown. From the above analysis, it can be seen that the product has a porous three-dimensional interconnected network foam structure with an average pore size of 3.36nm and a Co / Mg atomic ratio of 1.946. The specific surface area of the sample was analyzed by a specific surface area tester and was found to be 93.46m 2 ·g -1 .

[0072] As shown in Table 1, the obtained porous three-dimensional interconnected network structure MgO / Co / C foam material has excellent microwave absorption properties, wherein the maximum effective bandwidth with a reflectivity less than or equal to -10 dB is 10.32 GHz, and the maximum absorption is -53.67 dB, corresponding to a thickness of 3.8 mm.

[0073] In addition, the porous three-dimensional interconnected network structure MgO / Co / C foam material also has excellent thermal conductivity, and its thermal conductivity, thermal diffusivity and specific heat can reach 4.792W / (m·K), 4.172mm 2 / s and 1.149MJ / m 3 K, as shown in Table 2.

[0074] Example 4

[0075] A method for preparing a porous three-dimensional interconnected network structure MgO / Co / C foam material. Other conditions remain unchanged, and the mass of magnesium nitrate hexahydrate is changed to 0.666 g, the mass of cobalt nitrate hexahydrate is changed to 1.764 g, and the molar ratio of magnesium ions to cobalt ions in the obtained solution is 3:7.

[0076] The phase, composition and morphology of the obtained products measured by XRD, EDX and scanning electron microscopy are as follows: Figures 10-12 From the above analysis, it can be seen that the product has a porous three-dimensional interconnected network foam structure with a Co / Mg atomic ratio of 3.431.

[0077] As shown in Table 1, the obtained porous three-dimensional interconnected network structure MgO / Co / C foam material has excellent microwave absorption properties, wherein the maximum effective bandwidth with a reflectivity less than or equal to -10 dB is 13.92 GHz, and the maximum absorption is -41.60 dB, corresponding to a thickness of 3.1 mm.

[0078] In addition, the porous three-dimensional interconnected network structure MgO / Co / C foam material also has excellent thermal conductivity, and its thermal conductivity, thermal diffusivity and specific heat can reach 5.19W / (m·K), 5.28mm 2 / s and 0.983MJ / m 3 K, as shown in Table 2.

[0079] Example 5

[0080] A method for preparing a porous three-dimensional interconnected network structure MgO / Co / C foam material. Other conditions remain unchanged, and the mass of magnesium nitrate hexahydrate is changed to 0.222 g, the mass of cobalt nitrate hexahydrate is changed to 2.268 g, and the molar ratio of magnesium ions to cobalt ions in the obtained solution is 1:9.

[0081] The phase, composition and morphology of the obtained products measured by XRD, EDX and scanning electron microscopy are as follows: Figures 13-15 As shown. From the above analysis, it can be seen that the product has a porous three-dimensional interconnected network foam structure with an average pore size of 37.45nm and a Co / Mg atomic ratio of 9.499. The specific surface area of the sample was analyzed by a specific surface area tester and was 13.29m 2 ·g -1 .

[0082] As shown in Table 1, the obtained porous three-dimensional interconnected network structure MgO / Co / C foam material has excellent microwave absorption properties, wherein the maximum effective bandwidth with a reflectivity less than or equal to -10 dB is 13.68 GHz, and the maximum absorption is -59.42 dB, corresponding to a thickness of 2.8 mm.

[0083] In addition, the porous three-dimensional interconnected network structure MgO / Co / C foam material also has excellent thermal conductivity, and its thermal conductivity, thermal diffusivity and specific heat can reach 5.057W / (m·K), 4.85mm 2 / s and 1.043MJ / m 3 K, as shown in Table 2.

[0084] Example 6

[0085] A method for preparing a porous three-dimensional interconnected network structure MgO / Co / C foam material is provided. Other conditions remain unchanged, and the calcination temperature is changed to 500° C. on the basis of Example 2. Scanning electron microscopy analysis shows that the product has a porous three-dimensional interconnected network foam structure.

[0086] Example 7

[0087] A method for preparing a porous three-dimensional interconnected network structure MgO / Co / C foam material is provided. Other conditions remain unchanged, and the calcination temperature is changed to 700° C. on the basis of Example 2. Scanning electron microscopy analysis shows that the product has a porous three-dimensional interconnected network foam structure.

[0088] Example 8

[0089] A method for preparing a porous three-dimensional interconnected network structure MgO / Co / C foam material is provided. Other conditions remain unchanged, but the heating rate during calcination is changed to 5°C / min, as in Example 2. Scanning electron microscopy analysis shows that the product has a porous three-dimensional interconnected network structure.

[0090] Example 9

[0091] A porous three-dimensional interconnected network structure (MgO) 0.91 (FeO) 0.09A method for preparing a 1.5-μm / C foam material was used. Other conditions remained unchanged, except that 0.252 g of cobalt nitrate hexahydrate was replaced with 0.35 g of ferric nitrate nonahydrate, resulting in a molar ratio of magnesium ions to iron ions of 9:1 in the resulting solution. Scanning electron microscopy analysis revealed that the product possessed a porous, three-dimensional, interconnected network foam structure.

[0092] Example 10

[0093] A method for preparing a porous, three-dimensional interconnected network MgO / Ni / C foam material is disclosed. Other conditions remain unchanged, but 0.756 g of cobalt nitrate hexahydrate is replaced with 0.756 g of nickel nitrate hexahydrate, as in Example 2, such that the molar ratio of magnesium ions to nickel ions in the resulting solution is 7:3. Scanning electron microscopy analysis reveals that the product has a porous, three-dimensional interconnected network foam structure.

[0094] Example 11

[0095] A porous three-dimensional interconnected network structure (MgO) 0.725 (MnO) 0.275 A method for preparing a 1.5-μm / C foam material was used. Other conditions remained unchanged, except that 0.756 g of cobalt nitrate hexahydrate was replaced with 0.651 g of manganese nitrate tetrahydrate, resulting in a molar ratio of magnesium ions to manganese ions of 7:3 in the resulting solution. Scanning electron microscopy analysis revealed that the product possessed a porous, three-dimensional, interconnected network foam structure.

[0096] Example 12

[0097] A method for preparing a porous, three-dimensional interconnected network MgO / Cu / C foam material is disclosed. Other conditions remain unchanged, but 0.756 g of cobalt nitrate hexahydrate is replaced with 0.627 g of copper nitrate trihydrate, as in Example 2, such that the molar ratio of magnesium ions to copper ions in the resulting solution is 7:3. Scanning electron microscopy analysis reveals that the product has a porous, three-dimensional interconnected network foam structure.

[0098] Example 13

[0099] A method for preparing a porous three-dimensional interconnected network structure MgO / Co / C foam material is provided. Other conditions remain unchanged, but the type of polyol is changed to glycerol based on Example 2. Scanning electron microscopy analysis shows that the product has a porous three-dimensional interconnected network foam structure.

[0100] Example 14

[0101] A method for preparing a porous, three-dimensional interconnected network Ni / C foam material is described. 2.52g of nickel nitrate hexahydrate is dissolved in 4mL of ethylene glycol aqueous solution (v:v = 1:1) and magnetically stirred for 30 minutes to thoroughly mix to obtain a clear, transparent nickel nitrate solution. The solution is then transferred to an ark, sealed with a lid, and calcined in a tube furnace at 600°C (heating rate of 2°C / min) under an argon atmosphere for 2 hours. The solution is then cooled naturally to room temperature to obtain a porous, three-dimensional interconnected network Ni / C foam material. Scanning electron microscopy analysis shows that the product has a porous, three-dimensional interconnected network foam structure.

[0102] Example 15

[0103] A method for preparing a porous, three-dimensional interconnected network MnO / C foam material is described. Other conditions remain unchanged, except that 2.52 g of nickel nitrate hexahydrate is replaced with 2.17 g of manganese nitrate tetrahydrate as in Example 14. Scanning electron microscopy analysis reveals that the product has a porous, three-dimensional interconnected network foam structure.

[0104] Example 16

[0105] A method for preparing a porous three-dimensional interconnected network structure MgO / C foam material, in which other conditions remain unchanged, 2.52g of nickel nitrate hexahydrate is replaced with 2.22g of magnesium nitrate hexahydrate on the basis of Example 14. The phase, composition and morphology of the obtained product measured by XRD, EDX and scanning electron microscopy are as follows: Figures 26-28 Its thermal conductivity and wave absorption properties are shown in Table 1 and Table 2.

[0106] Example 17

[0107] A method for preparing a porous, three-dimensional, interconnected network-like thermally conductive and wave-absorbing foam material is disclosed. Other conditions remain unchanged, except that 2.52g of nickel nitrate hexahydrate is replaced with 1.76g of magnesium chloride hexahydrate as in Example 14. Scanning electron microscopy analysis reveals that the product has a porous, three-dimensional, interconnected network-like foam structure.

[0108] Example 18

[0109] A method for preparing a porous, three-dimensional, interconnected, reticulated thermally conductive and wave-absorbing foam material is disclosed. Other conditions remain unchanged, except that 2.52g of nickel nitrate hexahydrate is replaced with 1.14g of nickel sulfate as in Example 14. Scanning electron microscopy analysis reveals that the product has a porous, three-dimensional, interconnected, reticulated foam structure.

[0110] Example 19

[0111] A method for preparing a porous, three-dimensional, interconnected network-like thermally conductive and wave-absorbing foam material is described. Other conditions remain unchanged, except that 2.52g of nickel nitrate hexahydrate is replaced with 1.27g of nickel acetylacetonate. Scanning electron microscopy analysis reveals that the product has a porous, three-dimensional, interconnected network-like foam structure.

[0112] Table 1 Absorption properties of the products obtained in Examples 1 to 5 and Example 16 of the present invention

[0113]

[0114] Table 2 Thermal conductivity of the products obtained in Examples 1 to 5 and Example 16 of the present invention

[0115]

[0116] It can be seen that the three-dimensional interconnected network structure thermal conductive and absorbing foam material prepared by the present invention has excellent microwave absorption properties, wherein the maximum effective bandwidth with a reflectivity less than or equal to -10dB is 5.04~13.92GHz, the maximum absorption is -32.17~-59.42dB, and the thickness is 2.0~3.8mm.

[0117] In addition, the three-dimensional interconnected network structure heat-conducting and wave-absorbing foam material prepared by the present invention has excellent thermal conductivity, and its thermal conductivity, thermal diffusivity and specific heat can reach 4.792~5.654W / (m·K), 4.172~5.417mm 2 / s and 0.927~1.149MJ / m 3 K.

[0118] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A three-dimensional interconnected network of heat-conducting and wave-absorbing foam material, characterized in that: The thermal conductive and wave-absorbing foam material is a composite of C and metal, metal oxide, or C and metal oxide prepared by a bubble-assisted combustion method; wherein the metal is at least one of Fe, Co, Ni, Cu, and Mn; the metal oxide is MgO; the carbon content in the composite is 12.95-51.03%; and the foam material has a porous three-dimensional interconnected network structure, an average pore size of 3.36-37.45 nm, and a specific surface area of 13.29-222.86 m 2 ·g -1 ; It is prepared by bubble-assisted combustion method, which uses metal salts with low decomposition temperature to decompose in high-boiling-point polyol solution, generating bubbles at low temperature, so that the product presents a porous three-dimensional network structure; and at high temperature, the polyol is carbonized into carbon, and the carbon thermal reduction of the metal oxide is achieved at the same time.

2. A method for preparing the three-dimensional interconnected network heat-conducting and wave-absorbing foam material according to claim 1, characterized in that: The method specifically comprises the following steps: (1) dissolving a soluble metal salt in a mixed solution of polyol and water, and stirring at room temperature to obtain a polyol solution of the metal salt; (2) The polyol solution of the metal salt is loaded into an ark and calcined and decomposed under the protection of an inert gas to obtain the three-dimensional interconnected network heat-conducting and wave-absorbing foam material.

3. The method for preparing a three-dimensional interconnected network heat-conducting and wave-absorbing foam material according to claim 2, characterized in that: The polyol is one of ethylene glycol and glycerol with a high boiling point.

4. The method for preparing a three-dimensional interconnected network heat-conducting and wave-absorbing foam material according to claim 2, characterized in that: The soluble metal salt is one or more of cobalt nitrate, manganese nitrate, copper nitrate, nickel nitrate, iron nitrate, nickel sulfate, magnesium chloride, and nickel acetylacetonate; The total concentration of the soluble metal salt is 1.083-2.165 mol / L.

5. The method for preparing a three-dimensional interconnected network heat-conducting and wave-absorbing foam material according to claim 4, characterized in that: The volume ratio of the polyol to water is 0.5-2.

6. The method for preparing a three-dimensional interconnected network heat-conducting and wave-absorbing foam material according to claim 2, characterized in that: The calcination temperature in step (2) is 500°C to 700°C, the holding time is 1 to 4 h, and the heating rate is 2 to 5°C / min.

7. Use of the three-dimensional interconnected network heat-conducting and wave-absorbing foam material according to claim 1 or the three-dimensional interconnected network heat-conducting and wave-absorbing foam material prepared by the method according to any one of claims 2 to 6 in microwave absorption and thermal management.

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