Metallic graphene composite material and preparation method thereof

Abstract

The present application relates to a kind of metal graphene composite material and its preparation method, belong to graphene composite material technical field, to solve the production cost of metal graphene composite material prepared by existing method, alloy consistency is poor, graphene is not evenly distributed, low graphene content, low metal graphene composite material purity and other problems.The method of the present application is cooled after melting KCl and NaCl, boron carbide is added, so that the salt can be fully dehydrated, the melting point of the mixed salt after melting is reduced, the temperature required during secondary melting is lower, which is more conducive to the reaction, further improving the content of graphene in the composite material;It is also beneficial to reduce the size and number of graphene layers, and improve the purity of the composite material.The metal graphene composite material prepared by the method of the present application has uniform graphene distribution, high graphene content, high purity, simple preparation method, short preparation time, low production cost, no mechanical stirring, and the molten salt can be reused.

Description

Technical Field

[0001] This invention relates to the field of graphene composite materials technology, and in particular to a metal graphene composite material and its preparation method. Background Technology

[0002] Graphene is one of the strongest known materials, while also possessing excellent toughness and flexibility. Its theoretical Young's modulus reaches 1.0 TPa, and its inherent tensile strength is 130 GPa. The carrier mobility of graphene at room temperature is approximately 15,000 cm⁻¹. 2 The value of graphene is / (V·s), which is more than 10 times that of silicon and more than twice that of indium antimonide (InSb), the material with the highest known carrier mobility. Under certain specific conditions, such as low temperatures, the carrier mobility of graphene can even reach 250,000 cm⁻¹. 2 / (V·s). Unlike many materials, the electron mobility of graphene is less affected by temperature changes; at any temperature between 50 and 500 K, the electron mobility of monolayer graphene remains at 15000 cm⁻¹. 2 Approximately / (V·s).

[0003] By combining novel materials such as graphene with traditional metallic materials, the traditional metallic materials can exhibit superior properties, including electrical, mechanical, and thermodynamic characteristics. These materials have already gained significant recognition and application in both technology and the market. For example, metal-graphene composite materials have broad application prospects in fields such as aerospace, satellites, communications, and semiconductors.

[0004] However, current methods for preparing metal-graphene composite materials suffer from problems such as high cost, poor alloy consistency, uneven graphene dispersion, low graphene content, and low purity. Summary of the Invention

[0005] Based on the above analysis, the present invention aims to provide a metal-graphene composite material and its preparation method, in order to solve at least one of the following problems in metal-graphene composite materials prepared by existing methods: high production cost, poor alloy consistency, uneven graphene dispersion, low graphene content, and low purity of metal-graphene composite materials.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing a metal-graphene composite material, comprising the following steps:

[0008] (1) KCl and NaCl are melted to obtain a mixed molten salt, cooled and crushed to obtain a mixed salt, and the mixed salt is mixed with boron carbide to obtain a mixture;

[0009] (2) Add the mixture to the metal, put it into a graphite crucible, place it in a heating and stirring device, heat and melt it, let it stand, and obtain a molten salt mixture of upper and lower layers. The lower layer material is the metal graphene composite material.

[0010] Furthermore, in step (1), the molar ratio of KCl to NaCl is 1:2 to 4:2, preferably 2:3 to 3:2.

[0011] Furthermore, in step (1), the melting temperature is 800-900℃ and the melting and dehydration time is 30-60 min.

[0012] Furthermore, in step (1), the total mass ratio of KCl and NaCl to the mass ratio of boron carbide is 1:0.04 to 0.1, preferably 1:0.05 to 0.1.

[0013] Furthermore, in step (2), the metal is lead or aluminum.

[0014] Furthermore, in step (2), the total mass ratio of KCl and NaCl to the mass ratio of the metal is 1:3.0 to 3.6, preferably 1:3.0 to 3.5.

[0015] Furthermore, in step (2), the heating and melting temperature is 700-800℃ and the time is 0.5-2h.

[0016] Furthermore, the method also includes pouring the molten salt mixture of the upper and lower layers into a metal mold to obtain the metal graphene composite material.

[0017] Furthermore, the metal mold needs to be preheated at a temperature of 150-200°C for 1-2 hours.

[0018] Furthermore, the metal is at least one of lead, aluminum, or zinc.

[0019] Secondly, the present invention provides a metal graphene composite material prepared by the above method.

[0020] Thirdly, the present invention provides an application of the above-mentioned metal graphene composite material in aviation, aerospace, satellite, communication or semiconductor materials.

[0021] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0022] (1) The method of the present invention involves melting KCl and NaCl, cooling, and then adding boron carbide. This allows the salt to be fully dehydrated, lowering the melting point of the molten salt mixture and requiring a lower temperature for secondary melting. This temperature is more conducive to the reaction and further increases the graphene content in the composite material. It also helps to reduce the size and number of graphene layers, thus improving the purity of the composite material. Secondly, placing the molten salt mixture on top of the metal reduces the formation of metal oxides. All materials are added in a cold state, avoiding the temperature difference risks associated with the prior art of melting the metal first and then adding the molten salt. The uniform mixing of the molten salt material and the carbide results in a better eutectic and higher utilization rate.

[0023] (2) The metal graphene composite material prepared by the method of the present invention has a uniform and consistent graphene distribution, high graphene content (≥0.006%), high purity (≥99.92%), and hardness (≥4.6HB). The preparation method is simple, the preparation time is short, the production cost is low, no mechanical stirring is required, and the molten salt can be reused.

[0024] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0025] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0026] Figure 1 Here is a SEM image of the composite material prepared in Example 1 of this invention;

[0027] Figure 2 The image shown is a BES diagram of the composite material prepared in Example 1 of this invention.

[0028] Figure 3 The Raman spectrum of the metal-graphene composite material prepared in Example 1 of this invention.

[0029] Figure label:

[0030] 1-Graphene film. Detailed Implementation

[0031] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0032] A specific embodiment of the present invention discloses a method for preparing a metal-graphene composite material, comprising the following steps:

[0033] (1) KCl and NaCl are melted to obtain a mixed molten salt, cooled and crushed to obtain a mixed salt, and the mixed salt is mixed with boron carbide to obtain a mixture;

[0034] (2) Add the mixture to the metal, put it into a graphite crucible, place it in a heating and stirring device, heat and melt it, let it stand, and obtain a molten salt mixture of upper and lower layers. The lower layer material is the metal graphene composite material.

[0035] The method of this invention involves melting KCl and NaCl, cooling them, and then adding boron carbide. This allows for thorough dehydration of the salt, lowering the melting point of the molten salt mixture and requiring a lower temperature for secondary melting. This temperature is more conducive to the reaction, further increasing the graphene content in the composite material. It also helps reduce the size and number of graphene layers, improving the purity of the composite material. Secondly, placing the molten salt mixture on top of the metal reduces the formation of metal oxides. Adding all materials in a cold state avoids the temperature difference risks associated with adding molten salt after melting the metal, as is common in existing technologies. The homogeneous mixing of the molten salt and carbide results in a better eutectic state and higher utilization rate.

[0036] The metal-graphene composite material prepared by the method of this invention has uniform graphene distribution, high graphene content, high purity, simple preparation method, short preparation time, low production cost, does not require mechanical stirring, and the molten salt can be reused.

[0037] The carbon source in the method of this invention is boron carbide. Under specific conditions, boron carbide decomposes to form carbon atoms, which enter the lead solution and recombine to form a graphene structure after reaching a certain concentration. Therefore, the composite material prepared by the method of this invention has better binding properties with lead and more uniform dispersion. Secondly, graphene is expensive, and compared with the method of directly adding graphene, the method of this invention has a cost advantage.

[0038] In one specific implementation, in step (1), the molar ratio of KCl to NaCl is 1:2 to 4:2, for example, 1:2, 2:3, 5:6, 1:1, 7:6, 4:3, 3:2, 4:2.

[0039] In one specific implementation, in step (1), the molar ratio of KCl to NaCl is 2:3 to 3:2, for example, 2:3, 5:6, 1:1, 7:6, 4:3, 3:2.

[0040] The purpose of using NaCl and KCl as a mixed salt in this invention is that the mixed salt has a lower melting point than the single salt. Within the above molar ratio range, the melting point is relatively low near the eutectic point of NaCl and KCl.

[0041] In one specific embodiment, in step (1), the melting temperature is 800-900°C, for example, 800°C, 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, 870°C, 880°C, 890°C, or 900°C, and the melting and dehydration time is 30-60 min, for example, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, or 60 min.

[0042] Within the aforementioned melting temperature and time, NaCl and KCl can be fully melted with low energy consumption, without affecting the service life of the equipment.

[0043] In one specific implementation, in step (1), the particle size of the pulverized material is <3mm, which is beneficial for uniform mixing with boron carbide.

[0044] In one specific embodiment, in step (1), the total mass ratio of KCl and NaCl to boron carbide is 1:0.04 to 0.1, preferably 1:0.05 to 0.1, for example, 1:0.04, 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09, or 1:0.1. Since boron carbide is used as a carbon source, it must be used in excess to ensure sufficient graphene content in the product.

[0045] In one specific implementation, in step (2), the metal is at least one of lead, aluminum or zinc.

[0046] In one specific implementation, in step (2), the mass ratio of the total mass of KCl and NaCl to the mass of the metal is 1:3.0 to 3.6, preferably 1:3.0 to 3.5, for example 1:3.0, 1:3.1, 1:3.2, 1:3.3, 1:3.4, 1:3.5.

[0047] In one specific embodiment, in step (2), the heating and melting temperature is 700-800℃, for example, 700℃, 710℃, 720℃, 730℃, 740℃, 750℃, 760℃, 770℃, 780℃, 790℃, 800℃, and the time is 0.5-2h, for example, 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1.0h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, 2h.

[0048] Preferably, the heating and stirring device described in this invention is an induction furnace. The metal-graphene composite material described in this invention is manufactured in an induction furnace. In the induction furnace, due to electrodynamics, convection of the molten metal is ensured, achieving mixing of the molten metal. Using an induction furnace for the reaction can reduce impurities introduced by stirring, eliminate the stirring step, and simplify operation. In addition, the induction furnace heats up quickly, shortening the heating and melting time. Molten salt is not conductive; therefore, it can only heat the molten metal and will not move under the action of electromagnetic force. The convection in the molten salt is essentially just heat flow. The salt heated by the metal rises from the molten metal-salt interface to the salt-furnace atmosphere interface and is replaced by cooler salt, ensuring continuous movement of the molten metal-salt interface. This is because boron carbide and salt are mixed together. Under the action of heat flow, the salt at the metal-salt interface moves upward, while the cooler salt at the top sinks. Boron carbide also undergoes the same movement. The material at the metal-salt interface is constantly changing, thus achieving a stirring effect without the need for additional mechanical stirring.

[0049] In one specific embodiment, the method further includes pouring the molten salt mixture of the upper and lower layers into a mold to obtain the metal graphene composite material.

[0050] Specifically, the mold needs to be preheated at a temperature of 150-200℃ (e.g., 150℃, 155℃, 160℃, 165℃, 170℃, 175℃, 180℃, 185℃, 190℃, 195℃, 200℃) for 1-2 hours, for example, 1 hour, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours, 2 hours.

[0051] It should be noted that the mold is preheated in a low-temperature resistance furnace, and the low-density molten salt floats up in slag form. After it is removed from the mold, it is easily separated from the ingot. The separated molten salt can be used in step (1).

[0052] In this invention, the purity of lead is 99.99%, the purity of KCl is 99.8%, the purity of NaCl is 99.8%, the purity of boron carbide is ≥96.0%, and the particle size of boron carbide is at least F220.

[0053] Specifically, the metal is at least one of lead, aluminum, or zinc.

[0054] Another specific embodiment of the present invention discloses a metal graphene composite material prepared by the above method.

[0055] In the metal graphene composite material prepared by the method of the present invention, graphene is uniformly dispersed in the form of a transparent film with a size of approximately (5-20)×(20-40)μm. Preferably, the graphene is bilayer graphene.

[0056] The graphene content in the metal-graphene composite material prepared by the method of this invention is 0.005-0.01%, and the purity is ≥99.95%.

[0057] Another specific embodiment of the present invention discloses the application of the above-mentioned metal graphene composite material in aviation, aerospace, satellite, communication or semiconductor materials.

[0058] The technical solution of the present invention will be further explained below with reference to specific embodiments.

[0059] In the following examples, the purity of lead and aluminum is 99.99%, the purity of KCl is 99.8%, the purity of NaCl is 99.8%, the purity of boron carbide is 96.0%, and the particle size of boron carbide is F220.

[0060] Example 1

[0061] A method for preparing a metal-graphene composite material includes the following steps:

[0062] (1) KCl and NaCl were mixed in a molar ratio of 1:1 (total mass of 150g), and placed in a graphite crucible in a Graficarbo resistance furnace. The mixture was melted and dehydrated at 850℃ for 40min, cooled, and pulverized to a particle size of less than 3mm. 12.5g of boron carbide was added to obtain the mixture.

[0063] (2) Mix 500g of lead with the mixture and put it into a crucible made of high-density graphite. Place it in an induction furnace (YiHuiM.MF.00004) and heat it at 750°C for 1 hour to obtain a molten salt mixture. Pour the molten salt mixture into a metal mold. The metal mold is preheated to 200°C for 1 hour in a low-temperature resistance furnace (SNOL 58 / 350). The low-density molten salt floats up as slag and can be easily separated from the metal graphene composite material after being removed from the mold.

[0064] The carbon modification of the composite material prepared in this example was examined using a Renishaw INVIA0820-04 confocal Raman scattering spectrometer. The analysis revealed that the carbon modification was graphene. SEM and BES images of the cross-section of the composite material prepared in this example are shown below. Figure 1 and 2 As shown, graphene film 1 is transparent and has a size of approximately 20 × 40 μm. From Figure 1 and 2 As can be seen from the above, the graphene film in the graphene composite material prepared by the method of the present invention has small size and uniform dispersion, and no agglomeration or clumping.

[0065] The Raman spectrum of the metal-graphene composite material prepared in this embodiment is as follows: Figure 3 As shown, the intensity ratio of the 2D peak to the G peak (I²D / IG), which is equal to 0.61, indicates the formation of bilayer graphene. Due to the interaction between the two layers, it is stronger than a single layer, exhibiting better mechanical strength and higher fracture toughness. The two layers support each other, preventing brittle fracture under stress unlike a single layer. Its thermal and electrical conductivity are also better, resulting in higher stability than a single layer. The low defect rate of graphene is demonstrated by the intensity of peak D, which characterizes carbon film defects, and the fact that the peak D / G ratio (ID / IG) is 0.42, indicating that graphene has been incorporated into the composite material, forming a bilayer structure.

[0066] Example 2

[0067] A method for preparing a metal-graphene composite material includes the following steps:

[0068] (1) KCl and NaCl are mixed in a molar ratio of 3:2. In a Graficarbo resistance furnace, the mixture is placed in a graphite crucible and melted and dehydrated at 800°C for 60 min. After cooling, the mixture is pulverized to a particle size of less than 3 mm. Boron carbide is added. The total mass ratio of KCl and NaCl to the mass ratio of boron carbide is 1:0.05 to obtain a mixture.

[0069] (2) The lead is mixed with the mixture, and the total mass ratio of KCl and NaCl to lead is 1:3.0. The mixture is placed in a crucible made of high-density graphite and placed in an induction furnace of YiHui M.MF.00004. The mixture is heated and melted at 700°C for 2 hours to obtain a molten salt mixture. The molten salt mixture is poured into a metal mold. The metal mold is preheated to 150°C for 2 hours in a low-temperature resistance furnace SNOL 58 / 350. The low-density molten salt floats up as slag and is easily separated from the metal graphene composite material after being removed from the mold.

[0070] As in Example 1, the performance of the composite material prepared in this embodiment was tested, and the results were basically consistent. Due to space limitations, they will not be listed one by one.

[0071] Example 3

[0072] A method for preparing a metal-graphene composite material includes the following steps:

[0073] (1) KCl and NaCl are mixed in a molar ratio of 2:3. In a Graficarbo resistance furnace, the mixture is placed in a graphite crucible and melted and dehydrated at 900°C for 30 min. After cooling, the mixture is pulverized to a particle size of less than 3 mm. Boron carbide is added. The total mass ratio of KCl and NaCl to the mass ratio of boron carbide is 1:0.1 to obtain a mixture.

[0074] (2) The lead is mixed with the mixture, and the total mass ratio of KCl and NaCl to lead is 1:3.5. The mixture is placed in a crucible made of high-density graphite and placed in an induction furnace of YiHui M.MF.00004. The mixture is heated and melted at 800°C for 0.5h to obtain a molten salt mixture. The molten salt mixture is poured into a metal mold. The metal mold is preheated to 200°C for 1h in a low-temperature resistance furnace SNOL 58 / 350. The low-density molten salt floats up as slag and is easily separated from the metal graphene composite material after being removed from the mold.

[0075] As in Example 1, the performance of the composite material prepared in this embodiment was tested, and the results were basically consistent. Due to space limitations, they will not be listed one by one.

[0076] Example 4

[0077] The preparation method of a metal graphene composite material is the same as that in Example 1, except that in step (2), lead is replaced with aluminum, and the final aluminum graphene composite material is obtained.

[0078] Example 5

[0079] The preparation method of the metal graphene composite material in this embodiment is the same as that in Example 1, except that in step (1), the molar ratio of KCl and NaCl is 1:2.

[0080] Example 6

[0081] The preparation method of the metal graphene composite material in this embodiment is the same as that in Example 1, except that in step (1), the total mass ratio of KCl and NaCl to boron carbide is 1:0.04.

[0082] Example 7

[0083] The preparation method of the metal graphene composite material in this embodiment is the same as that in Example 1, except that in step (2), the total mass ratio of KCl and NaCl to the mass ratio of lead is 1:3.6.

[0084] Comparative Example 1

[0085] The preparation method of the metal graphene composite material in this comparative example is the same as that in Example 1, except that in step (1), KCl, NaCl and boron carbide are directly mixed, and KCl and NaCl are not melted, cooled and pulverized.

[0086] Comparative Example 2

[0087] The preparation method of the metal graphene composite material in this comparative example is the same as that in Example 1, except that in step (2), the heating and melting temperature is 850°C and the time is 2.2h.

[0088] Comparative Example 3

[0089] The preparation method of the metal graphene composite material in this comparative example is the same as that in Example 1, except that in step (2), instead of using an induction furnace for heating and melting, an open furnace is used for melting with a mechanical stirrer.

[0090] Experimental Example 1

[0091] The purity, graphene content, and number of layers of the composite materials prepared in Examples 1-7 and Comparative Examples 1-3 were tested respectively. The hardness of the composite materials was tested using a VERZUS 750CCD hardness tester. The results are shown in Table 1.

[0092] Table 1

[0093]

[0094] Compared with Example 1, Comparative Example 1 eliminated the raw material pretreatment step, resulting in a significant reduction in the graphene content in the composite material, as well as a certain degree of reduction in purity and hardness. The number of graphene layers increased to 3.

[0095] Compared with Example 1, the graphene content in the prepared composite materials of Examples 5-7 was reduced, and the purity and hardness were also reduced to a certain extent. In Example 5, the number of graphene layers increased to 3.

[0096] Compared with Example 1, the graphene content in the composite material prepared at a temperature not specified in this invention was significantly reduced in Comparative Example 2, and the purity and hardness were also reduced to a certain extent. The number of graphene layers increased to 4.

[0097] Compared with Example 1, the graphene content in the composite material prepared by the induction furnace heating melt method designed in this invention is not much different in Comparative Example 3. However, the open furnace heats up slowly, and mechanical stirring makes the production process more complicated and may introduce a certain amount of impurities, which reduces the purity of the composite material.

[0098] Experimental Example 2

[0099] Samples were taken from different locations of the graphene composite material obtained in Example 1 to test the carbon content. The data obtained are shown in Table 2.

[0100] Table 2. Test data of carbon content at different locations in graphene composite materials.

[0101] Location number Carbon content (%) 1 0.0087 2 0.0091 3 0.0089 4 0.0088 5 0.0090 6 0.0091 7 0.0089 8 0.0092

[0102] As can be seen from the table above, the carbon content in the graphene composite material at different locations is not significantly different, indicating that the composite material prepared by the method of this invention has good consistency.

[0103] The inventors conducted the above-mentioned experiments on the composite materials prepared in other embodiments, and the results were basically the same. Due to space limitations, they will not be listed one by one.

[0104] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a metal-graphene composite material, characterized in that, Includes the following steps: (1) KCl and NaCl are melted at a temperature of 800~900℃ and the melting and dehydration time is 30~60min to obtain a mixed molten salt. The mixture is cooled and crushed to obtain a mixed salt. The mixed salt is then mixed with boron carbide to obtain a mixture. (2) Add the mixture to the metal, place it in a heating and stirring device, heat and melt it at a temperature of 700~800℃ for 0.5~2h, let it stand, and obtain a molten salt mixture of upper and lower layers. The lower layer material is the metal graphene composite material.

2. The method for preparing a metal-graphene composite material according to claim 1, characterized in that, In step (1), the molar ratio of KCl to NaCl is 1:2 to 4:

2.

3. The method for preparing a metal-graphene composite material according to claim 1, characterized in that, In step (1), the melting temperature is 810~890℃ and the melting and dehydration time is 35~55min.

4. A method for preparing a metal-graphene composite material according to any one of claims 1-3, characterized in that, In step (1), the total mass ratio of KCl and NaCl to boron carbide is 1:0.04~0.

1.

5. The method for preparing a metal-graphene composite material according to claim 1, characterized in that, In step (2), the metal is at least one of lead, aluminum or zinc.

6. The method for preparing a metal-graphene composite material according to claim 5, characterized in that, In step (2), the total mass of KCl and NaCl is in the mass ratio of the metal to 1:3.0~3.

6.

7. A method for preparing a metal-graphene composite material according to any one of claims 1-3, characterized in that, In step (2), the heating and melting temperature is 710~790℃ and the time is 0.6~1.9h.

8. The method for preparing a metal-graphene composite material according to claim 1, characterized in that, The method further includes pouring the molten salt mixture of the upper and lower layers into a mold to obtain the metal graphene composite material.

9. A metal graphene composite material prepared by the method according to any one of claims 1-8.

10. The application of the metal graphene composite material of claim 9 in aerospace, communications or semiconductor materials.

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