Wave-absorbing heat-conducting material and preparation method of wave-absorbing heat-conducting material

Abstract

The invention relates to a wave-absorbing heat-conducting material and a preparation method of the wave-absorbing heat-conducting material, and the wave-absorbing heat-conducting material comprises 60-70 parts of a core-shell Al2O3 (at) rGO composite material; 10 to 20 parts of boron nitride nanosheet powder; 18 parts of polydimethylsiloxane; and 2 parts of a curing agent. Through the wave-absorbing heat-conducting material, the impedance of Al2O3 and boron nitride nanosheets is close to the free space impedance, so that the impedance mismatch can be reduced, and the wave-absorbing performance can be improved; in addition, the rGO can consume electromagnetic waves, and the materials have excellent heat conduction performance, so that an effective solution is provided for the heat dissipation problem and the electromagnetic interference problem of an electronic device, namely, the heat absorption and conduction material has excellent electromagnetic wave absorption capacity and efficient heat conduction performance at the same time; the operation stability and reliability of the electronic equipment can be obviously improved.

Description

TECHNICAL FIELD

[0001] The embodiment of the present application relates to the technical field of wave-absorbing and heat-conducting materials, in particular to a wave-absorbing and heat-conducting material and a preparation method of the wave-absorbing and heat-conducting material. BACKGROUND

[0002] With the continuous evolution of electronic devices towards miniaturization, high power density and high frequency, the thermal management challenges of core heat-generating components such as processors, power devices and high-energy density batteries are becoming increasingly severe. Studies have shown that when the junction temperature of a semiconductor chip increases by 10°C, its reliability life is reduced by about 50%. In this context, the thermal management system design needs to achieve efficient heat conduction in a limited space to avoid heat accumulation leading to performance degradation or even device failure.

[0003] In some scenarios, electromagnetic wave absorption function is also needed to reduce electromagnetic interference and improve device stability.

[0004] Traditional materials are difficult to balance wave-absorbing and heat-conducting performance, therefore, it is necessary to develop a wave-absorbing and heat-conducting material to balance wave-absorbing and heat-conducting performance. SUMMARY

[0005] In view of the above problems, the embodiment of the present application provides a wave-absorbing and heat-conducting material and a preparation method of the wave-absorbing and heat-conducting material, which overcomes the above problems or at least partially solves the above problems.

[0006] According to one aspect of the embodiment of the present application, a wave-absorbing and heat-conducting material is provided, comprising: a core-shell Al2O3@rGO composite material, 60 to 70 parts; boron nitride nanosheet powder, 10 to 20 parts; polydimethylsiloxane, 18 parts; curing agent, 2 parts.

[0007] In an optional manner, the core-shell Al2O3@rGO composite material is obtained by heat reduction of a core-shell Al2O3@GO composite material.

[0008] In an optional manner, the method for heat reduction of the core-shell Al2O3@GO composite material is as follows: the core-shell Al2O3@GO composite material is placed in a tube furnace, nitrogen is introduced, the temperature is raised to 350 to 400 DEG C at a speed of 2 DEG C / min, the temperature is kept for 0.1 h, the temperature is raised to 800 to 900 DEG C at a speed of 3 DEG C / min to 5 DEG C / min, the temperature is kept for 2 h, and the temperature is naturally cooled to room temperature, to obtain the core-shell Al2O3@rGO composite material.

[0009] In an alternative manner, the core-shell Al2O3@GO composite material is prepared by the following method: dispersing spherical alumina powder in a mixed solution of Tris buffer and anhydrous ethanol to obtain a first solution, wherein 1 g of the spherical alumina powder corresponds to 30 mL of the Tris buffer and 10 mL of the anhydrous ethanol; dispersing dopamine powder in the first solution to form a second solution, wherein 0.1 g of the dopamine powder corresponds to 1 g of the spherical alumina powder; washing the second solution with deionized water, vacuum filtering and drying to obtain a first substance; mixing the first substance in a GO solution to obtain a third solution, wherein 1 g of the first substance corresponds to 20 mL of the GO solution; centrifugal washing the third solution with anhydrous ethanol and vacuum drying to obtain the core-shell Al2O3@GO composite material.

[0010] In an alternative manner, the concentration of the GO solution is 2 mg / mL to 5 mg / mL.

[0011] In an alternative manner, the particle size of the spherical alumina in the spherical alumina powder is 3 μm to 5 μm.

[0012] In an alternative manner, the curing agent is curing agent 184.

[0013] According to another aspect of the embodiments of the present application, a preparation method of a wave-absorbing and heat-conducting material is provided, comprising: preparing a core-shell Al2O3@rGO composite material; homogenously treating 60 to 70 parts of the core-shell Al2O3@rGO composite material, 10 to 20 parts of boron nitride nanosheet powder, 18 parts of polydimethylsiloxane and 2 parts of a curing agent to obtain the wave-absorbing and heat-conducting material.

[0014] In an alternative manner, the method for preparing the core-shell Al2O3@rGO composite material comprises: heat-reducing a core-shell Al2O3@GO composite material to obtain the core-shell Al2O3@rGO composite material.

[0015] In an alternative mode, the preparation method of the core-shell Al2O3@GO composite material comprises: dispersing spherical alumina powder in a mixed solution of Tris buffer and anhydrous ethanol to obtain a first solution, wherein 1g of the spherical alumina powder corresponds to 30mL of the Tris buffer and 10mL of the anhydrous ethanol; dispersing dopamine powder in the first solution to form a second solution, wherein 0.1g of the dopamine powder corresponds to 1g of the spherical alumina powder; washing the second solution with deionized water, vacuum filtering and drying to obtain a first substance; mixing the first substance in a GO solution to obtain a third solution, wherein 1g of the first substance corresponds to 20mL of the GO solution; centrifugal washing the third solution with anhydrous ethanol and vacuum drying to obtain the core-shell Al2O3@GO composite material.

[0016] The beneficial effects of the embodiment of the present application include providing a wave-absorbing and heat-conducting material, comprising: core-shell Al2O3@rGO composite material, 60 to 70 parts; boron nitride nanosheet powder, 10 to 20 parts; polydimethylsiloxane, 18 parts; curing agent, 2 parts. Through the wave-absorbing and heat-conducting material, the impedance of Al2O3 and boron nitride nanosheet is close to the free space impedance, which can reduce the impedance mismatch and improve the wave-absorbing performance; in addition, rGO can absorb electromagnetic waves, and several materials all have excellent heat conduction performance, which is an effective solution to the heat dissipation problem and electromagnetic interference problem of electronic devices, that is, the wave-absorbing and heat-conducting material has excellent electromagnetic wave absorption capacity and high-efficiency heat conduction performance at the same time, which can significantly improve the stability and reliability of electronic equipment operation. BRIEF DESCRIPTION OF DRAWINGS

[0017] One or more embodiments are illustrated by way of example in the figures that form a part of this patent document, these illustrative examples do not limit the embodiments, elements having the same reference numerals in the figures represent like elements unless otherwise specified, the figures in the drawings do not constitute a proportional limitation.

[0018] Figure 1 is a flowchart of preparing a core-shell Al2O3@GO composite material provided by the embodiment of the present application.

[0019] Figure 2 is a flowchart of preparing a wave-absorbing and heat-conducting material provided by the embodiment of the present application.

[0020] Figure 3 is a flowchart of preparing a wave-absorbing and heat-conducting material provided by the embodiment of the present application. DETAILED DESCRIPTION

[0021] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0022] The wave-absorbing and heat-conducting material provided by the embodiment of the present application comprises a core-shell Al2O3@rGO composite material, 60-70 parts; boron nitride nanosheet powder, 10-20 parts; polydimethylsiloxane, 18 parts; and a curing agent, 2 parts. Through the wave-absorbing and heat-conducting material, the impedance of Al2O3 and the boron nitride nanosheet is close to the free space impedance, which can reduce impedance mismatch and improve wave-absorbing performance. In addition, rGO can absorb electromagnetic waves, and the several materials all have excellent heat-conducting performance, which is an effective solution to the heat dissipation problem and the electromagnetic interference problem of electronic devices, that is, the wave-absorbing and heat-conducting material has excellent electromagnetic wave absorption capacity and high-efficiency heat-conducting performance, and can significantly improve the stability and reliability of electronic device operation.

[0023] Among them, Al2O3 is aluminum oxide, which has high thermal conductivity and good chemical stability.

[0024] Among them, GO is the English name of Graphene Oxide, which corresponds to the Chinese name of graphene oxide, which has excellent electrical conductivity and mechanical properties.

[0025] Graphene oxide is a material obtained by treating graphite with a strong oxidizing agent (such as potassium permanganate, concentrated sulfuric acid, etc.), also known as graphite oxide. It contains a large number of oxygen-containing functional groups (such as hydroxyl, epoxy, carboxyl, carbonyl, etc.).

[0026] Among them, rGO is the English name of Reduced Graphene Oxide, which corresponds to the Chinese name of reduced graphene oxide.

[0027] Reduced graphene oxide is obtained by reducing graphene oxide.

[0028] The purpose of reduction is to remove part or most of the oxygen-containing functional groups and partially restore the sp2 carbon network structure of graphene that has been oxidized.

[0029] rGO restores electrical conductivity / conductivity enhancement: after removing the oxygen-containing functional groups, the electrical conductivity of rGO is much better than that of GO. The electrical conductivity is significantly improved (up to several hundred or even 1000 S / m or more). Through mechanisms such as resistance loss and dielectric loss, rGO can convert the energy of incident electromagnetic waves into heat energy and be consumed.

[0030] rGO improves thermal conductivity: While graphene oxide itself has some thermal conductivity, the reduction process removes the oxidized defects and functional groups that interfere with phonon transport, and the thermal conductivity of rGO will be further improved (closer to the excellent thermal conductivity of intrinsic graphene) than that of GO.

[0031] The core-shell Al2O3@rGO composite material is a composite material with aluminum oxide as the core and rGO as the shell.

[0032] For example, 60g to 70g of the core-shell Al2O3@rGO composite material corresponds to 10 to 20 parts of boron nitride nanosheet powder, 18 parts of polydimethylsiloxane, and 2 parts of curing agent.

[0033] It is worth noting that in some embodiments, the curing agent is curing agent 184, as described in patent CN118225279A.

[0034] It is worth noting that in some embodiments, the boron nitride nanosheet has a sheet diameter of 5μm. The sheet diameter of 5μm of the boron nitride nanosheet refers to the size (i.e. sheet diameter) in the plane direction of 5 microns.

[0035] It is worth noting that in some embodiments, the core-shell Al2O3@rGO composite material is obtained by heat reduction of the core-shell Al2O3@GO composite material.

[0036] The core-shell Al2O3@GO composite material is a composite material with aluminum oxide as the core and GO as the shell.

[0037] In some embodiments, the method of heat reduction of the core-shell Al2O3@GO composite material is as follows: the core-shell Al2O3@GO composite material is placed in a tube furnace, nitrogen is introduced, the temperature is raised to 350℃ to 400℃ at a rate of 2℃ / min, and then the temperature is raised to 800℃ to 900℃ at a rate of 3℃ / min to 5℃ / min, and then the temperature is kept for 2h, and then the temperature is naturally cooled to room temperature, to obtain the core-shell Al2O3@rGO composite material.

[0038] In some embodiments, please refer to Figure 1 , the core-shell Al2O3@GO composite material is prepared by the following method: Step S11, dispersing the spherical aluminum oxide powder in a mixed solution of Tris buffer and anhydrous ethanol to obtain a first solution, wherein 1g of the spherical aluminum oxide powder corresponds to 30mL of the Tris buffer and 10mL of the anhydrous ethanol.

[0039] The particle size of the spherical aluminum oxide in the spherical aluminum oxide powder is 3μm to 5μm.

[0040] Tris, which is the full name of Tris(hydroxymethyl)aminomethane in English, corresponds to Chinese as three (hydroxymethyl) aminomethane, which is often used in the preparation of buffer solution to ensure the stability of the pH of the reaction environment.

[0041] It is worth noting that the pH of the Tris buffer solution is 8.0 to 9.0, preferably 8.5, to ensure the stable dispersion of the spherical alumina powder during the reaction and the effective progress of the subsequent reaction.

[0042] Among them, anhydrous ethanol is an organic solvent that can promote the dispersion of alumina powder and help the uniformity of the subsequent reaction. The purity of the anhydrous ethanol is greater than 99%.

[0043] In some embodiments, the operation process of dispersing the spherical alumina powder in the mixed solution of the Tris buffer solution and the anhydrous ethanol to obtain the first solution can be to slowly add the spherical alumina powder to the mixed solution of the Tris buffer solution and the anhydrous ethanol while stirring to ensure uniform dispersion of the powder and avoid agglomeration. The stirring speed is controlled at 200 rpm to 300 rpm, and the stirring is continued for 30 minutes to 60 minutes.

[0044] Step S12, dispersing dopamine powder in the first solution to form a second solution, wherein 0.1g of the dopamine powder corresponds to 1g of the spherical alumina powder.

[0045] Among them, the operation process of dispersing dopamine powder in the first solution to form a second solution can be to add dopamine powder to the first solution, stir at room temperature for 6h, and control the stirring rate at 200 rpm to 300 rpm to ensure uniform dispersion of the dopamine powder and sufficient contact with the spherical alumina powder, forming a uniform composite solution.

[0046] It is worth noting that dopamine can self-aggregate to form polydopamine.

[0047] Step S13, using deionized water to wash, vacuum filter and dry the second solution to obtain a first material.

[0048] The specific operation process of using deionized water to wash, vacuum filter and dry the second solution to obtain a first material includes repeatedly washing the second solution in deionized water for 3 times, vacuum filtering after each washing to remove unreacted dopamine and other impurities. Then, the washed material is placed in a 65°C oven for drying, for example, for 12h, to obtain the first material.

[0049] Among them, deionized water is high-purity water purified by ion exchange resin.

[0050] Step S14, mixing the first substance in the GO solution to obtain a third solution, wherein 1 g of the first substance corresponds to 20 mL of the GO solution.

[0051] The concentration of the GO solution is 2 mg / mL to 5 mg / mL, which is prepared by using deionized water.

[0052] The operation process of mixing the first substance in the GO solution to obtain a third solution is to add the first substance into the GO solution, continuously stir at room temperature for 12 h, and the stirring speed can be controlled at 200 rpm to 300 rpm, so that the first substance and the GO are fully contacted to form a stable third solution.

[0053] Step S15, using anhydrous ethanol to centrifugally wash and vacuum dry the third solution to obtain the core-shell Al2O3@GO composite material.

[0054] The specific operation process of using anhydrous ethanol to centrifugally wash and vacuum dry the third solution is to centrifugally wash the third solution in anhydrous ethanol for 3 times, the centrifugal speed is 8000 rpm each time, and the centrifugal time is 10 minutes. After washing, vacuum drying is performed, the drying temperature is set to 80°C, and the drying lasts for 3 h.

[0055] According to another aspect of the embodiment of the present application, a preparation method of a wave-absorbing and heat-conducting material is provided, please refer to Figure 2 , which comprises: Step S10, preparing a core-shell Al2O3@rGO composite material.

[0056] In some embodiments, the method for preparing the core-shell Al2O3@rGO composite material comprises: performing thermal reduction on the core-shell Al2O3@GO composite material to obtain the core-shell Al2O3@rGO composite material. For details, please refer to the foregoing content, which will not be repeated here.

[0057] In some embodiments, the method for preparing the core-shell Al2O3@GO composite material can refer to the foregoing steps S11 to S15, which will not be repeated here.

[0058] Step S20, homogenously treating 60 to 70 parts of the core-shell Al2O3@rGO composite material, 10 to 20 parts of boron nitride nanosheet powder, 18 parts of polydimethylsiloxane, and 2 parts of a curing agent to obtain the wave-absorbing and heat-conducting material.

[0059] The specific operation of homogenously treating is to mix 60 to 70 parts of the core-shell Al2O3@rGO composite material, 10 to 20 parts of boron nitride nanosheet powder, 18 parts of polydimethylsiloxane, and 2 parts of a curing agent, and stir at a speed of 3000 rpm for 30 minutes by using a high-speed stirrer.

[0060] The curing agent is curing agent 184, and reference is made to patent CN118225279A.

[0061] It is worth mentioning that when the wave-absorbing heat-conducting material is applied, please refer to Figure 3 The wave-absorbing heat-conducting material is placed in the mold, and the wave-absorbing heat-conducting part is formed by hot pressing.

[0062] The hot pressing pressure is 10 kgf, the hot pressing temperature is 120 DEG C, and the hot pressing time is 10 min.

[0063] The mold is a metal mold with a certain shape and size, which ensures that the material is uniformly heated during hot pressing. The mold can be customized according to the specific application requirements, such as for electronic device heat dissipation, the mold shape needs to match the contact surface of the device to ensure the material adhesion. After hot pressing, cool to room temperature and take out the finished product.

[0064] For example, in some embodiments, the mold is a 5x5 cm rectangular metal mold with a depth of 1 cm.

[0065] In order to facilitate the reader to understand the inventive concept of the embodiments of the present application, the technical effects of using the embodiments of the present application are demonstrated as follows.

[0066] Example 1 <Preparation of the first substance> 10 spherical alumina powders (particle size 3-5 μm) were dispersed in a mixture of 300 mL Tris buffer (pH 8.5) and 100 mL anhydrous ethanol to obtain a first solution; 1 g of dopamine powder was dispersed in the first solution, stirred at room temperature for 6 h, and the stirring rate can be 200-300 rpm to form a second solution; the second solution was washed with deionized water for several times (3 times), vacuum filtered and dried at 65 DEG C to obtain the first substance.

[0067] <Preparation of core-shell Al2O3@GO composite material> 10 g of the first substance was mixed in 200 mL of GO solution (concentration 2 mg / mL), stirred at room temperature for 12 h, and the stirring rate can be 200-300 rpm to obtain a third solution; the third solution was centrifuged and vacuum dried with anhydrous ethanol, the drying temperature was 80 DEG C, and the drying time was 3 h to obtain the core-shell Al2O3@GO composite material.

[0068] <Preparation of core-shell Al2O3@rGO composite material> The core-shell Al2O3@GO composite material is placed in a tube furnace, nitrogen is introduced, and the temperature is increased to 350-400°C at a rate of 2°C / min, and then the temperature is kept for 0.1 h, and then the temperature is increased to 800°C at a rate of 3-5°C / min, and then the temperature is kept for 2 h, and then the temperature is naturally cooled to room temperature, to obtain the core-shell Al2O3@rGO composite material.

[0069] <Preparation of wave-absorbing and heat-conducting material> The core-shell Al2O3@rGO composite material, 20 g of boron nitride nanosheet powder, 18 g of polydimethylsiloxane, and 2 g of curing agent 184 are homogenously treated to obtain the wave-absorbing and heat-conducting material.

[0070] <Performance test> The wave-absorbing and heat-conducting material is placed in a 5*5 cm square (1 cm deep) mold, and a wave-absorbing and heat-conducting piece is formed by hot pressing. The pressure of hot pressing is 10 kgf, the temperature of hot pressing is 120°C, and the time of hot pressing is 10 min.

[0071] The wave-absorbing and heat-conducting piece formed by hot pressing is subjected to shielding performance testing. Specifically, an Agilent vector network analyzer is used to test the shielding performance of the wave-absorbing and heat-conducting piece in the X-band (8.2-12.4 GHz).

[0072] The wave-absorbing and heat-conducting piece formed by hot pressing is subjected to thermal conductivity testing. The specific testing method is as follows: the sample is placed in a thermal conductivity tester, the temperature gradient is set to 50°C, the heat flow density and temperature difference are measured, and the thermal conductivity is calculated. The test is repeated three times to ensure the accuracy of the data.

[0073] Example Two <Preparation of first substance> The same as Example One.

[0074] <Preparation of core-shell Al2O3@GO composite material> 10 g of the first substance is mixed in 200 mL of a GO solution (concentration of 5 mg / mL), and stirred at room temperature for 12 h, and the stirring rate can be 200-300 rpm, to obtain a third solution; the third solution is centrifuged and washed with anhydrous ethanol and vacuum dried, the drying temperature is 80°C, and the drying time is 3 h, to obtain the core-shell Al2O3@GO composite material.

[0075] <Preparation of core-shell Al2O3@rGO composite material> The core-shell Al2O3@GO composite material is placed in a tube furnace, nitrogen is introduced, and the temperature is increased to 350-400°C at a rate of 2°C / min, and then the temperature is kept for 0.1 h, and then the temperature is increased to 900°C at a rate of 3-5°C / min, and then the temperature is kept for 2 h, and then the temperature is naturally cooled to room temperature, to obtain the core-shell Al2O3@rGO composite material.

[0076] <Preparation of wave-absorbing and heat-conducting material> The 70 g of the core-shell Al2O3@rGO composite material, 10 g of boron nitride nanosheet powder, 18 g of polydimethylsiloxane, and 2 g of curing agent 184 are homogenized to obtain the wave-absorbing and heat-conducting material.

[0077] <Performance test> The same as Example 1.

[0078] Comparative Example 1 <Preparation of wave-absorbing and heat-conducting material> The 40 g of spherical Al2O3 powder, 30 g of rGO, 10 g of boron nitride nanosheet powder, 18 g of polydimethylsiloxane, and 2 g of curing agent 184 are homogenized to obtain the wave-absorbing and heat-conducting material.

[0079] <Performance test> The same as Example 1.

[0080] The absorption loss and thermal conductivity data of Example 1, Example 2, and Comparative Example 1 are shown in Table 1.

[0081] Table 1

[0082] According to Table 1, the RL min (minimum reflection loss) of the wave-absorbing and heat-conducting material of Example 1 is -52.2 dB, indicating that it has excellent electromagnetic shielding performance; the thermal conductivity of the wave-absorbing and heat-conducting material of Example 1 is as high as 5.85 W / m·K, indicating that it has good heat conduction performance. Although Example 2 is slightly inferior, the RL min reaches -48.4 dB, and the thermal conductivity is 5.62 W / m·K, which still performs outstandingly; the performance of Comparative Example 1 is relatively weak, the RL min is only -35.4 dB, and the thermal conductivity is 3.95 W / m·K, verifying the key role of the core-shell Al2O3@rGO composite material in improving material performance. By optimizing the preparation process, the core-shell Al2O3@rGO composite material significantly improves the wave-absorbing and heat-conduction performance, providing an efficient solution for the electromagnetic shielding and thermal management fields.

[0083] However, in Example 1 or Example 2 of the present application, the impedance of Al2O3 and boron nitride nanosheet is close to the impedance of free space, which can reduce impedance mismatch and improve wave-absorbing performance; in addition, rGO can absorb electromagnetic waves, and all the materials have excellent heat conduction performance, providing an effective solution for the heat dissipation and electromagnetic interference problems of electronic devices, i.e., the wave-absorbing and heat-conducting material has excellent electromagnetic wave absorption capacity and high-efficiency heat conduction performance, which can significantly improve the stability and reliability of electronic device operation.

[0084] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not limited thereto; under the idea of the present application, the technical features of the above examples or different examples can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the present application as described above, which are not provided in detail for simplicity; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A wave-absorbing heat-conducting material, characterized by, The core-shell Al2O3@rGO composite material comprises: 60-70 parts of the core-shell Al2O3@rGO composite material; 10-20 parts of boron nitride nanosheet powder; 18 parts of polydimethylsiloxane; and 2 parts of a curing agent.

2. The wave- and heat-absorbing material according to claim 1, characterized in that, The core-shell Al2O3@rGO composite material is obtained by heat reduction of a core-shell Al2O3@GO composite material.

3. The wave- and heat-absorbing material according to claim 2, characterized in that, The method for heat reduction of the core-shell Al2O3@GO composite material comprises: placing the core-shell Al2O3@GO composite material in a tube furnace, introducing nitrogen, heating at a speed of 2 ℃ / min to 350-400 ℃, keeping the temperature for 0.1 h, then heating at a speed of 3-5 ℃ / min to 800-900 ℃, keeping the temperature for 2 h, and naturally cooling to room temperature to obtain the core-shell Al2O3@rGO composite material.

4. The wave- and heat-absorbing material according to claim 2, wherein The core-shell Al2O3@GO composite material is prepared by the following method: dispersing spherical alumina powder in a mixed solution of Tris buffer and anhydrous ethanol to obtain a first solution, wherein 1 g of the spherical alumina powder corresponds to 30 mL of the Tris buffer and 10 mL of the anhydrous ethanol; dispersing dopamine powder in the first solution to form a second solution, wherein 0.1 g of the dopamine powder corresponds to 1 g of the spherical alumina powder; washing the second solution with deionized water, vacuum filtering and drying to obtain a first substance; mixing the first substance in a GO solution to obtain a third solution, wherein 1 g of the first substance corresponds to 20 mL of the GO solution; centrifugal washing the third solution with anhydrous ethanol and vacuum drying to obtain the core-shell Al2O3@GO composite material.

5. The wave- and heat-absorbing material according to claim 4, wherein The concentration of the GO solution is 2-5 mg / mL.

6. The wave- and heat-absorbing material according to claim 5, wherein The particle size of the spherical alumina in the spherical alumina powder is 3-5 μm.

7. The wave- and heat-absorbing material according to claim 1, wherein The curing agent is curing agent 184.

8. A method of producing a wave-absorbing heat-conducting material, characterized by The core-shell Al2O3@rGO composite material is prepared. The wave-absorbing and heat-conducting material is obtained by homogenously treating 60-70 parts of the core-shell Al2O3@rGO composite material, 10-20 parts of boron nitride nanosheet powder, 18 parts of polydimethylsiloxane and 2 parts of a curing agent. The method for preparing the core-shell Al2O3@rGO composite material comprises heat reduction of a core-shell Al2O3@GO composite material to obtain the core-shell Al2O3@rGO composite material.

9. The method of claim 8, wherein the wave-absorbing heat-conducting material is prepared by mixing the metal powder and the carbon nanotube powder in a weight ratio of 1 : 1 to 1 :

10. The method for preparing the core-shell Al2O3@GO composite material comprises:

10. The method of claim 9, wherein the wave-absorbing heat-conducting material is prepared by mixing the metal powder and the carbon nanotube powder in a weight ratio of 1 : 1 to 1 :

10. dispersing spherical alumina powder in a mixed solution of Tris buffer and anhydrous ethanol to obtain a first solution, wherein 1 g of the spherical alumina powder corresponds to 30 mL of the Tris buffer and 10 mL of the anhydrous ethanol; dispersing dopamine powder in the first solution to form a second solution, wherein 0.1 g of the dopamine powder corresponds to 1 g of the spherical alumina powder; washing the second solution with deionized water, vacuum filtering and drying to obtain a first substance; mixing the first substance in a GO solution to obtain a third solution, wherein 1 g of the first substance corresponds to 20 mL of the GO solution; and centrifugal washing the third solution with anhydrous ethanol and vacuum drying to obtain the core-shell Al2O3@GO composite material. The third solution is centrifugally washed with anhydrous ethanol and vacuum dried to obtain the core-shell Al2O3@GO composite material.

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