Graphene reinforced aluminum-based composite material and preparation method thereof

Abstract

The invention relates to the technical field of metal composite materials, in particular to a graphene reinforced aluminum matrix composite material and a preparation method. The preparation method comprises the following steps: S1, dispersing graphene powder in a dispersion medium to form a graphene suspension of graphene monomer particles; s2, a low-temperature volatile dispersing agent is added into the graphene suspension liquid, then aluminum powder is added, the mixture is subjected to ball milling and mixing, a plurality of graphene monomer particles are attached to the surfaces of aluminum powder particles in a dispersed mode, graphene-aluminum composite powder is formed, and composite powder suspension liquid is obtained; s3, removing the dispersion medium in the composite powder suspension, and drying to obtain composite powder; s4, heating the composite powder at a first temperature in a reducing gas atmosphere, and removing the dispersing agent to obtain graphene-aluminum composite powder; and S5, the graphene-aluminum composite powder is subjected to powder metallurgy sintering, and the graphene reinforced aluminum-based composite material is obtained. The density, the hardness and the electric conduction and heat conduction performance of the graphene reinforced aluminum-based composite material can be effectively improved.

Description

Technical Field

[0001] This application relates to the field of metal composite materials technology, and more specifically, to a graphene-reinforced aluminum-based composite material and its preparation method. Background Technology

[0002] Aluminum and aluminum alloys possess numerous excellent properties, including low density, high specific strength, good machinability, excellent electrical and thermal conductivity, and superior corrosion resistance, making them widely used in equipment manufacturing for marine vessels, transportation, and aerospace. However, with the increasing complexity of equipment operating conditions, single aluminum or aluminum alloys are insufficient to meet the design performance requirements of relevant equipment components. Composite processes can comprehensively improve the strength, toughness, thermal and electrical conductivity of aluminum and aluminum alloys while preserving their intrinsic properties. Graphene, as a novel carbon material, possesses ultra-high strength, low density, excellent thermal and electrical conductivity, and good corrosion resistance, making it an ideal reinforcement for composite aluminum and aluminum alloy materials. However, graphene's small size and tendency to agglomerate result in poor dispersion within the aluminum matrix, limiting its performance enhancement of aluminum-based composites and making it difficult to achieve the desired results.

[0003] Among related technologies, the main technical means to improve the dispersibility of graphene in graphene-aluminum matrix composites include ball milling, electrostatic self-assembly, and surface coating modification. Although these methods can improve the dispersibility of graphene in aluminum matrix to a certain extent, they will introduce some new problems, such as causing damage to the graphene structure, introducing other impurities and having low processing efficiency, making it difficult to achieve industrial production, and the introduced impurities causing damage to the aluminum matrix.

[0004] How to achieve uniform dispersion of graphene without damaging the graphene and aluminum matrix is ​​an industry problem that urgently needs to be solved. Summary of the Invention

[0005] This application aims to provide a graphene-reinforced aluminum matrix composite material and its preparation method, which balances the integrity of graphene and aluminum matrix with the dispersion of graphene in aluminum matrix, thereby improving the density, hardness, and electrical and thermal conductivity of aluminum matrix composite material.

[0006] The embodiments of this application are implemented as follows:

[0007] In a first aspect, embodiments of this application provide a method for preparing graphene-reinforced aluminum-based composite materials, comprising:

[0008] S1, dispersing graphene powder in a dispersion medium to form a graphene suspension of graphene monomer particles.

[0009] S2, a low-temperature volatile dispersant is added to the graphene suspension, and then aluminum powder is added and ball-milled together to disperse several graphene monomer particles on the surface of the aluminum powder particles to form graphene-aluminum composite powder, thus obtaining a composite powder suspension.

[0010] S3, remove the dispersion medium from the composite powder suspension and dry to obtain the composite powder;

[0011] S4, the composite powder is heated in a reducing gas atmosphere at a first temperature to remove the dispersant and obtain graphene-aluminum composite powder;

[0012] S5, the graphene-aluminum composite powder is subjected to powder metallurgy sintering to obtain a graphene-reinforced aluminum-based composite material.

[0013] In one embodiment of this application, in S1:

[0014] The graphene powder is produced by physical exfoliation; and / or

[0015] The dispersion medium includes at least one of water, ethanol, and ethylene glycol; and / or

[0016] The mass ratio of graphene to the dispersion medium is ≤2:98; and / or

[0017] The method for "dispersing graphene powder in a dispersion medium" is mechanical stirring at a speed of 500-3000 r / min.

[0018] In one embodiment of this application, in S2:

[0019] The dispersant includes high molecular weight polyurethane block copolymers, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymers, Tween 80; and / or

[0020] The volume ratio of the graphene suspension to the dispersant is 500:(1-10); and / or

[0021] Ball milling is performed under water bath cooling conditions; and / or

[0022] Ball milling was performed using a ball-to-material ratio of 1:(1-3); and / or

[0023] The grinding balls include at least one of zirconium carbide, ceramics, silicon carbide, titanium carbide, and alumina; and / or

[0024] The diameter of the grinding ball is ≤5mm; and / or

[0025] The graphene content in the graphene-aluminum composite powder is ≤2%.

[0026] In one embodiment of this application, in step S3, the drying method is freeze drying.

[0027] In one embodiment of this application, in S4:

[0028] The reducing gas atmosphere includes hydrogen; and / or

[0029] The first temperature is 200-600℃; and / or

[0030] The composite powder is heated for 1-3 hours.

[0031] In one embodiment of this application, S5 includes:

[0032] S51, the graphene-aluminum composite powder is pressed into a blank;

[0033] S52, the blank is sintered in a reducing gas atmosphere to obtain the graphene-reinforced aluminum-based composite material.

[0034] In one embodiment of this application, S51 includes:

[0035] First, the graphene-aluminum composite powder is pressed under a first pressure for a first time to obtain a blank intermediate.

[0036] The billet intermediate is then pressed under a second pressure for a second duration to obtain the billet.

[0037] The first pressure is less than the second pressure.

[0038] In one embodiment of this application, in S51:

[0039] The first pressure is 3-7 MPa; and / or

[0040] The second pressure is 20-30 MPa; and / or

[0041] The first duration is 2-5 minutes; and / or

[0042] The second duration is 2-5 minutes.

[0043] In one embodiment of this application, in S52:

[0044] The reducing gas atmosphere includes hydrogen; and / or

[0045] The sintering temperature is 500-600℃; and / or

[0046] The sintering time is 1-3 hours.

[0047] Secondly, embodiments of this application provide a graphene-reinforced aluminum-based composite material, which is formed using the graphene-reinforced aluminum-based composite material preparation method described in any one of the first aspects.

[0048] Beneficial effects:

[0049] The preparation method provided in this application prepares a composite material by dispersing graphene monomer particles onto the surface of aluminum powder and then sintering them. This effectively alleviates the graphene agglomeration problem, improves the dispersibility of graphene in the aluminum matrix, and ensures that the graphene structure is not easily worn during the graphene dispersion process, nor does it introduce impurities that could damage the aluminum metal. It balances the integrity of both the graphene and the aluminum matrix with the dispersibility of graphene in the aluminum matrix, effectively improving the density, hardness, and electrical and thermal conductivity of the aluminum-based composite material. Furthermore, the process is simple and requires low-level equipment, which is conducive to promoting the industrial production of such materials. Attached Figure Description

[0050] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0051] Figure 1 This is a flowchart of a preparation method provided in one embodiment of this application;

[0052] Figure 2 This is a schematic diagram of the structure of a graphene-aluminum composite powder provided in an embodiment of this application;

[0053] Figure 3 This is an electron microscope image of the graphene-aluminum composite powder provided in Example 1 of this application;

[0054] Figure 4 A surface electron microscope image of a single graphene-aluminum composite powder provided in Example 1 of this application;

[0055] Figure 5 This is an electron microscope image of the graphene-reinforced aluminum matrix composite material provided in Example 1 of this application.

[0056] Icons: 100 - aluminum powder; 200 - graphene monomer particles. Detailed Implementation

[0057] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Furthermore, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application.

[0058] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0059] In this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural.

[0060] In this application, "at least one" means one or more, and "more than one" means two or more. "One or more", "at least one of the following", or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0061] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0062] To improve the dispersibility of graphene in aluminum matrices and enhance the performance of graphene-aluminum matrix composites, various techniques have been employed, including ball milling, electrostatic self-assembly, and surface coating modification. While these methods can improve graphene dispersibility to some extent, they each introduce new challenges. For example, ball milling improves the uniformity of aluminum and graphene dispersion, but the milling balls can easily damage the graphene structure, limiting its performance. Electrostatic self-assembly, while effectively improving the uniformity of graphene-aluminum matrix composites, suffers from low processing efficiency, long processing times, and the potential to introduce impurities, making industrial-scale production difficult. Surface coating modification involves introducing other phases through processes like chemical plating to modify the graphene surface, thereby reducing its surface energy and improving dispersibility. However, the process is complex, and the introduced phases can alter the properties of the aluminum matrix. Therefore, achieving uniform graphene dispersion without damaging either the graphene or the aluminum matrix remains a critical industry challenge.

[0063] In view of this, this application provides a technical solution, which first disperses graphene powder in a dispersion medium to form a graphene suspension with uniformly distributed graphene monomer particles, then ball-mills aluminum powder and graphene suspension under the action of a dispersant, so that several graphene monomer particles are dispersedly adhered to the surface of aluminum powder to form graphene-aluminum composite powder, then dries to remove the dispersion medium, and then allows the dispersant to evaporate in a reducing gas atmosphere to obtain graphene-aluminum composite powder without other impurities and with good graphene dispersibility, and finally sintersects such graphene-aluminum composite powder to form graphene-reinforced aluminum matrix composite material.

[0064] Compared with methods used in related technologies, the preparation method of this application avoids the problem of high-temperature oxidation of powder during traditional high-energy ball milling and is less likely to damage the structural integrity of graphene. Compared with electrostatic self-assembly, the preparation method of this application has higher mixing efficiency, and the quality of powder mixed in a single batch is not limited, which can well meet the requirements of industrialization and mass production. Compared with surface coating modification method, the preparation method of this application does not introduce a third phase, and the prepared graphene-reinforced aluminum matrix composite material is purer.

[0065] like Figure 1 As shown, the method for preparing graphene-reinforced aluminum-based composite materials provided in this application includes the following steps:

[0066] S1, dispersing graphene powder in a dispersion medium to form a graphene suspension of graphene monomer particles.

[0067] S2, a low-temperature volatile dispersant is added to the graphene suspension, and then aluminum powder is added and ball-milled together, so that several graphene monomer particles 200 are dispersedly adhered to the surface of the aluminum powder particles 100, forming a graphene-aluminum composite powder (e.g. Figure 2 As shown), a composite powder suspension was obtained;

[0068] S3, remove the dispersion medium from the composite powder suspension, and dry to obtain the composite powder;

[0069] S4. The composite powder is heated in a reducing gas atmosphere at a first temperature to remove the dispersant and obtain graphene-aluminum composite powder.

[0070] S5, graphene-aluminum composite powder is sintered by powder metallurgy to obtain graphene-reinforced aluminum-based composite material.

[0071] The embodiments of this application propose to prepare composite materials by dispersing graphene monomer particles onto the surface of aluminum powder and then sintering them. This effectively alleviates the graphene agglomeration problem, improves the dispersibility of graphene in aluminum, and ensures that the graphene structure is not easily worn during the process of achieving graphene dispersion and graphene-aluminum powder composite, and also avoids the introduction of impurities that could damage the aluminum metal.

[0072] It should be noted that the "aluminum powder" mentioned in the embodiments of this application includes powder made from any of aluminum metal or aluminum alloy.

[0073] In some embodiments, in S1, the graphene powder is produced by physical exfoliation so that the graphene powder has relatively finer monomer particles.

[0074] In some embodiments, in S1, the dispersion medium includes at least one of water, ethanol, and ethylene glycol. By using pure water, ethanol, or ethylene glycol as the dispersion medium, energy is applied to the graphene powder under liquid conditions, achieving micro-nano-scale uniform dispersion of graphene particles while ensuring that the graphene does not suffer structural damage.

[0075] When the graphene powder content in the dispersion medium is low, although uniform dispersion of graphene can be achieved, it will cause difficulties in drying and low dispersion efficiency in subsequent steps S3 and S4. On the other hand, when the graphene content is high, the graphene cannot be fully dispersed, and graphene agglomerates are easily formed in the dispersion medium, resulting in poor dispersion effect. In some embodiments, in S1, the mass ratio of graphene to dispersion medium is ≤2:98.

[0076] In some embodiments, in S1, the method of "dispersing graphene powder in a dispersion medium" is mechanical stirring at a stirring rate of 500-3000 r / min. Compared with common ultrasonic mixing, mechanical stirring is less likely to damage the structure of graphene. Exemplarily, mechanical stirring is performed at stirring rates of 800 r / min, 1000 r / min, 1200 r / min, 1400 r / min, 1500 r / min, 1600 r / min, 1800 r / min, 2000 r / min, 2200 r / min, 2400 r / min, 2500 r / min, 2600 r / min, 2800 r / min, or 3000 r / min. By setting the stirring rate to 500-3000 r / min, it avoids the situation where the stirring impeller cannot provide sufficient energy to achieve complete dispersion of graphene due to excessively low rotation speed, and avoids the situation where excessively high rotation speed causes stratification between graphene and water due to density differences, thus preventing the formation of a uniformly dispersed graphene suspension.

[0077] In some embodiments, in S2, the dispersant includes a high molecular weight polyurethane block copolymer (hereinafter referred to as KY1 dispersant), a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (hereinafter referred to as P123), and Tween 80. KY1 dispersant is a hydrophilic polymer containing graphene affinity groups, while P123 and Tween 80 are nonionic surfactants. Using these dispersants not only prolongs the time of uniformity maintenance of the graphene suspension but also activates the surface of the aluminum powder, making it easier for graphene particles to be uniformly adsorbed on the surface of the aluminum particles.

[0078] In some embodiments, in S2, the volume ratio of graphene suspension to dispersant is 500:(1-10). By setting the volume ratio of graphene suspension to dispersant, the uniformity of the graphene suspension is maintained for a certain period of time, and the dispersant is easily removed in subsequent steps.

[0079] After the graphene suspension and dispersant are prepared in a certain volume ratio, they are then ball-milled together with aluminum powder. The ball milling process involves placing the materials (graphene suspension, dispersant, and aluminum powder) into the cylinder of a ball mill, then adding grinding balls as grinding media. When the cylinder rotates, the grinding balls impact the materials, thereby fully dispersing and combining the components of the materials, resulting in graphene particles being more dispersed and more stably adsorbed on the surface of the aluminum powder.

[0080] In some embodiments, in S2, ball milling is performed under water bath cooling conditions to further avoid the high temperature of ball milling to prevent material oxidation and ensure that the aluminum material and graphene are not damaged.

[0081] In some embodiments, in S2, ball milling is performed using a ball-to-material ratio of 1:(1-3). The ball-to-material ratio refers to the mass ratio of grinding balls to material in the ball mill cylinder.

[0082] In some embodiments, in S2, the type of grinding balls includes at least one of zirconium carbide, ceramics, silicon carbide, titanium carbide, and alumina.

[0083] In some embodiments, in S2, the diameter of the grinding ball is ≤5mm.

[0084] By using lightweight, small-diameter grinding balls, graphene and aluminum powder can be thoroughly ground without damaging the graphene structure. This promotes the uniform adhesion of graphene monomer particles to the surface of aluminum particles and improves the bonding strength between the graphene monomer particles and the aluminum particle surface, forming... Figure 2 The graphene-aluminum composite powder, which resembles a "hemp ball", solves the problem of poor dispersion uniformity of micro-nano-sized graphene, aluminum and aluminum alloy powders.

[0085] In some embodiments, the graphene content in the graphene-aluminum composite powder is ≤2%. By adding trace amounts of graphene, the dispersion requirements can be better met, while ensuring the enhancement effect of graphene on the composite material.

[0086] In some embodiments, in S3, the drying method is freeze drying. For example, the composite powder suspension obtained in S2 is passed through a 20-mesh sieve to remove grinding balls, and then subjected to rapid freeze drying. Specifically, the composite powder suspension is evenly spread on a tray and placed in a vacuum dryer, where it is freeze-dried for 72 hours to obtain a composite powder, which may also include a dispersant component.

[0087] Further, step S4 is performed to remove the dispersant component, so as to obtain a number of graphene monomer particles that are dispersedly adhered to the surface of pure aluminum powder particles to form graphene-aluminum composite powder.

[0088] In some embodiments, in S4, the reducing gas atmosphere includes hydrogen to prevent the aluminum base from oxidizing and deteriorating during the removal of the dispersant.

[0089] In some embodiments, in S4, the first temperature is 200-600°C.

[0090] In some embodiments, in S4, the heating time of the composite powder is 1-3 hours.

[0091] For example, S4 includes: placing the composite powder in a vacuum tube furnace, introducing hydrogen gas into the tube for protection, and heating the composite powder at 300°C for 2 hours to allow the dispersant to fully volatilize, thereby obtaining graphene-aluminum composite powder.

[0092] In some embodiments, S5 includes:

[0093] S51, pressing graphene-aluminum composite powder into a blank;

[0094] S52, the blank is sintered in a reducing gas atmosphere to obtain a graphene-reinforced aluminum matrix composite material.

[0095] S51 includes: first pressing the graphene-aluminum composite powder with a first pressure for a first time to obtain a billet intermediate; then pressing the billet intermediate with a second pressure for a second time to obtain a billet; wherein the first pressure is less than the second pressure.

[0096] The first pressure is 3-7 MPa, the second pressure is 20-30 MPa, the first duration is 2-5 min, and the second duration is 2-5 min.

[0097] By first pressing the billet with a relatively small first pressure for a first time to form a billet intermediate with a relatively small density, and then pressing it with a relatively large second pressure for a second time to form a dense billet, the shape of the billet, the bonding strength between particles, the interface quality, and the uniformity of the billet are improved.

[0098] After initial pressing and repressing in step S51 to obtain a billet with high density, the billet is then sintered in step S52 to obtain a graphene-reinforced aluminum matrix composite material with high density, low density, high hardness and good thermal and electrical conductivity.

[0099] In some embodiments, in S52, the reducing gas atmosphere includes hydrogen to prevent the aluminum base from oxidizing and deteriorating during sintering.

[0100] In some embodiments, the sintering temperature in S52 is 500-600°C.

[0101] In some embodiments, the sintering time in S52 is 1-3 hours.

[0102] For example, the blank was sintered in a hydrogen protective atmosphere at 550°C for 2 hours to obtain a graphene-reinforced aluminum matrix composite material.

[0103] Secondly, embodiments of this application also provide a graphene-reinforced aluminum-based composite material, which is formed using the graphene-reinforced aluminum-based composite material preparation method provided in any embodiment of the first aspect.

[0104] The graphene-reinforced aluminum matrix composite material includes an aluminum matrix and graphene particles, with the graphene particles dispersed in the aluminum matrix. The graphene content in the graphene-reinforced aluminum matrix composite material is greater than zero and less than or equal to 2%.

[0105] The present application will be specifically described below through specific embodiments. The following embodiments are only some embodiments of the present application and are not intended to limit the present application.

[0106] Example 1

[0107] S1, using graphene powder prepared by physical exfoliation as raw material, the dispersion medium (pure water) and graphene powder were mixed at a mass ratio of 98:2, and the mechanical stirring impeller speed was set to 2000 r / min to stir the solution for 1 h; a graphene suspension with a solid content of 2 wt% and uniform dispersion without obvious agglomeration was obtained.

[0108] S2, calculate and weigh the required aluminum powder according to the graphene content in the composite material being 0-2wt%, add the aluminum powder to the graphene suspension obtained in S1, and add zirconium carbide grinding balls with a diameter of 2mm according to a ball-to-material ratio of 1:1. Add KY1 dispersant according to a volume ratio of graphene suspension to dispersant of 500:1. Adjust the speed of the mechanical stirring impeller to 2000r / min. The grinding tank is cooled by circulating water to stabilize the temperature of the grinding tank and the internal stirring solution. After stirring for 3 hours, sieve through a 20-mesh stainless steel sieve to filter out the zirconium carbide grinding balls. After filtering the zirconium carbide grinding balls, a composite powder suspension is obtained.

[0109] S3, the composite powder suspension is evenly spread in a quartz tray and freeze-dried in a vacuum freeze dryer for 72 hours to obtain the composite powder;

[0110] S4. The composite powder obtained in S3 is loaded into a vacuum tube furnace and protected with hydrogen gas at a pressure of 0.02 MPa. The heating rate is set to 10℃ / min, the holding temperature is 300℃, and the holding time is 2h to allow the dispersant to fully volatilize, thus obtaining a pure graphene-aluminum composite powder.

[0111] S5. The graphene-aluminum composite powder is placed in a steel mold with a diameter of 20mm and initially pressed with a first pressure of 3MPa and a holding time of 3min to obtain a billet intermediate with a low density. The billet intermediate is then placed back into the mold and repressed with a second pressure of 25MPa and a holding time of 3min to obtain a billet with a higher density.

[0112] S6. The blank is placed in a corundum ceramic boat and then placed in a vacuum tube furnace. Hydrogen gas with a flow rate of 200 ml / min is introduced for protection. The heating rate is set to 10℃ / min to raise the temperature to 550℃. After holding at this temperature for 2 hours, the furnace is cooled to obtain a graphene-reinforced aluminum-based composite material with a graphene content of 2%.

[0113] Example 2

[0114] S1, using graphene powder prepared by physical exfoliation as raw material, the dispersion medium (ethylene glycol) and graphene powder were mixed at a mass ratio of 98:2, and the mechanical stirring impeller speed was set to 2000 r / min to stir the solution for 1 h; a graphene suspension with a solid content of 2 wt% and uniform dispersion without obvious agglomeration was obtained.

[0115] S2, calculate and weigh the required aluminum powder according to the graphene content in the composite material being 0-2wt%, add the aluminum powder to the graphene suspension obtained in S1, and add zirconium carbide grinding balls with a diameter of 2mm according to a ball-to-material ratio of 1:1. Add KY1 dispersant according to a volume ratio of graphene suspension to dispersant of 500:1. Adjust the speed of the mechanical stirring impeller to 2000r / min. The grinding tank is cooled by circulating water to stabilize the temperature of the grinding tank and the internal stirring solution. After stirring for 3 hours, sieve through a 20-mesh stainless steel sieve to filter out the zirconium carbide grinding balls. After filtering the zirconium carbide grinding balls, a composite powder suspension is obtained.

[0116] S3, the composite powder suspension is evenly spread in a quartz tray and freeze-dried in a vacuum freeze dryer for 72 hours to obtain the composite powder;

[0117] S4. The composite powder obtained in S3 is loaded into a vacuum tube furnace and protected with hydrogen gas at a pressure of 0.02 MPa. The heating rate is set to 10℃ / min, the holding temperature is 300℃, and the holding time is 2h to allow the dispersant to fully volatilize, thus obtaining a pure graphene-aluminum composite powder.

[0118] S5. The graphene-aluminum composite powder is placed in a steel mold with a diameter of 20mm and initially pressed with a first pressure of 3MPa and a holding time of 3min to obtain a billet intermediate with a low density. The billet intermediate is then placed back into the mold and repressed with a second pressure of 25MPa and a holding time of 3min to obtain a billet with a higher density.

[0119] S6. The blank is placed in a corundum ceramic boat and then placed in a vacuum tube furnace. Hydrogen gas with a flow rate of 200 ml / min is introduced for protection. The heating rate is set to 10℃ / min to raise the temperature to 550℃. After holding at this temperature for 2 hours, the furnace is cooled to obtain a graphene-reinforced aluminum-based composite material with a graphene content of 2%.

[0120] Example 3

[0121] S1, using graphene powder prepared by physical exfoliation as raw material, the dispersion medium (pure water) and graphene powder were mixed at a mass ratio of 98:2, and the mechanical stirring impeller speed was set to 2000 r / min to stir the solution for 1 h; a graphene suspension with a solid content of 2 wt% and uniform dispersion without obvious agglomeration was obtained.

[0122] S2, calculate and weigh the required aluminum powder according to the graphene content of 0-2wt% in the composite material, add the aluminum powder to the graphene suspension obtained in S1, add zirconium carbide grinding balls with a diameter of 2mm according to the ball-to-particle ratio of 1:1, add P123 dispersant according to the volume ratio of graphene suspension to dispersant of 500:1, adjust the speed of the mechanical stirring impeller to 2000r / min, and use circulating water to achieve water bath cooling to stabilize the temperature of the grinding tank and the internal stirring solution. After stirring for 3 hours, sieve through a 20-mesh stainless steel sieve to filter out the zirconium carbide grinding balls. After filtering the zirconium carbide grinding balls, a composite powder suspension is obtained.

[0123] S3, the composite powder suspension is evenly spread in a quartz tray and freeze-dried in a vacuum freeze dryer for 72 hours to obtain the composite powder;

[0124] S4. The composite powder obtained in S3 is loaded into a vacuum tube furnace and protected with hydrogen gas at a pressure of 0.02 MPa. The heating rate is set to 10℃ / min, the holding temperature is 300℃, and the holding time is 2h to allow the dispersant to fully volatilize, thus obtaining a pure graphene-aluminum composite powder.

[0125] S5. The graphene-aluminum composite powder is placed in a steel mold with a diameter of 20mm and initially pressed with a first pressure of 3MPa and a holding time of 3min to obtain a billet intermediate with a low density. The billet intermediate is then placed back into the mold and repressed with a second pressure of 25MPa and a holding time of 3min to obtain a billet with a higher density.

[0126] S6. The blank is placed in a corundum ceramic boat and then placed in a vacuum tube furnace. Hydrogen gas with a flow rate of 200 ml / min is introduced for protection. The heating rate is set to 10℃ / min to raise the temperature to 550℃. After holding at this temperature for 2 hours, the furnace is cooled to obtain a graphene-reinforced aluminum-based composite material with a graphene content of 2%.

[0127] Example 4

[0128] S1, using graphene powder prepared by physical exfoliation as raw material, the dispersion medium (pure water) and graphene powder were mixed at a mass ratio of 98:2, and the mechanical stirring impeller speed was set to 2000 r / min to stir the solution for 1 h; a graphene suspension with a solid content of 2 wt% and uniform dispersion without obvious agglomeration was obtained.

[0129] S2, calculate and weigh the required aluminum powder according to the graphene content in the composite material being 0-2wt%, add the aluminum powder to the graphene suspension obtained in S1, and add zirconium carbide grinding balls with a diameter of 2mm according to a ball-to-material ratio of 1:2. Add KY1 dispersant according to a volume ratio of graphene suspension to dispersant of 500:1. Adjust the speed of the mechanical stirring impeller to 2000r / min. The grinding tank is cooled by circulating water to stabilize the temperature of the grinding tank and the internal stirring solution. After stirring for 3 hours, sieve through a 20-mesh stainless steel sieve to filter out the zirconium carbide grinding balls. After filtering the zirconium carbide grinding balls, a composite powder suspension is obtained.

[0130] S3, the composite powder suspension is evenly spread in a quartz tray and freeze-dried in a vacuum freeze dryer for 72 hours to obtain the composite powder;

[0131] S4. The composite powder obtained in S3 is loaded into a vacuum tube furnace and protected with hydrogen gas at a pressure of 0.02 MPa. The heating rate is set to 10℃ / min, the holding temperature is 300℃, and the holding time is 2h to allow the dispersant to fully volatilize, thus obtaining a pure graphene-aluminum composite powder.

[0132] S5. The graphene-aluminum composite powder is placed in a steel mold with a diameter of 20mm and initially pressed with a first pressure of 3MPa and a holding time of 3min to obtain a billet intermediate with a low density. The billet intermediate is then placed back into the mold and repressed with a second pressure of 25MPa and a holding time of 3min to obtain a billet with a higher density.

[0133] S6. The blank is placed in a corundum ceramic boat and then placed in a vacuum tube furnace. Hydrogen gas with a flow rate of 200 ml / min is introduced for protection. The heating rate is set to 10℃ / min to raise the temperature to 550℃. After holding at this temperature for 2 hours, the furnace is cooled to obtain a graphene-reinforced aluminum-based composite material with a graphene content of 2%.

[0134] Comparative Example 1

[0135] S1, using graphene powder prepared by physical exfoliation as raw material, the dispersion medium (pure water) and graphene powder are mixed in a mass ratio of 98:2, and ultrasonically dispersed for 1 hour to obtain a graphene suspension with a solid content of 2wt%.

[0136] S2, calculate and weigh the required aluminum powder according to the graphene content in the composite material being 0-2wt%, add the aluminum powder to the graphene suspension obtained in S1, add KY1 dispersant according to the volume ratio of graphene suspension to dispersant being 500:1, and ultrasonically disperse for 3 hours to obtain a composite powder suspension.

[0137] S3, the composite powder suspension is evenly spread in a quartz tray and freeze-dried in a vacuum freeze dryer for 72 hours to obtain the composite powder;

[0138] S4. The composite powder obtained in S3 is loaded into a vacuum tube furnace and protected with hydrogen gas at a pressure of 0.02 MPa. The heating rate is set to 10℃ / min, the holding temperature is 300℃, and the holding time is 2h to allow the dispersant to fully volatilize, thus obtaining a pure graphene-aluminum composite powder.

[0139] S5. The graphene-aluminum composite powder is placed in a steel mold with a diameter of 20mm and initially pressed with a first pressure of 3MPa and a holding time of 3min to obtain a billet intermediate with a low density. The billet intermediate is then placed back into the mold and repressed with a second pressure of 25MPa and a holding time of 3min to obtain a billet with a higher density.

[0140] S6. The blank is placed in a corundum ceramic boat and then placed in a vacuum tube furnace. Hydrogen gas with a flow rate of 200 ml / min is introduced for protection. The heating rate is set to 10℃ / min to raise the temperature to 550℃. After holding at this temperature for 2 hours, the furnace is cooled to obtain a graphene-reinforced aluminum-based composite material with a graphene content of 2%.

[0141] Comparative Example 2

[0142] S1. Using graphene powder prepared by physical exfoliation as raw material, the dispersion medium (pure water) and graphene powder are mixed at a mass ratio of 98:2. Then, aluminum powder is weighed according to the graphene content in the composite material being 0-2wt% and added to the dispersion medium. KY1 dispersant is measured at a volume ratio of 1 / 500 and added to the dispersion medium. Zirconia carbide grinding balls with a diameter of 2mm are added at a ball-to-material ratio of 1:1. The speed of the mechanical stirring impeller is adjusted to 2000r / min. The grinding tank is cooled by circulating water to stabilize the temperature of the grinding tank and the internal stirring solution. After stirring for 3 hours, the mixture is sieved through a 20-mesh stainless steel sieve to filter out the zirconium carbide grinding balls. After filtering the zirconium carbide grinding balls, a composite powder suspension is obtained.

[0143] S2, the composite powder suspension is evenly spread in a quartz tray and freeze-dried in a vacuum freeze dryer for 72 hours to obtain the composite powder;

[0144] S3. The composite powder obtained in S2 is loaded into a vacuum tube furnace and protected by hydrogen gas at a pressure of 0.02 MPa. The heating rate is set to 10℃ / min, the holding temperature is 300℃, and the holding time is 2h to allow the dispersant to fully volatilize, thus obtaining a pure graphene-aluminum composite powder.

[0145] S4. The graphene-aluminum composite powder is placed in a steel mold with a diameter of 20mm and initially pressed with a first pressure of 3MPa for 3min to obtain a billet intermediate with low density. The billet intermediate is then placed back into the mold and repressed with a second pressure of 25MPa for 3min to obtain a billet with high density.

[0146] S5. The blank is placed in a corundum ceramic boat and then placed in a vacuum tube furnace. Hydrogen gas with a flow rate of 200 ml / min is introduced for protection. The heating rate is set to 10℃ / min to raise the temperature to 550℃. After holding at this temperature for 2 hours, the furnace is cooled to obtain a graphene-reinforced aluminum matrix composite material with a graphene content of 2%.

[0147] Comparative Example 3

[0148] S1. Add aluminum powder to the dispersion medium, and add KY1 dispersant at a volume ratio of 1 / 500 to the dispersion medium. Then add zirconium carbide grinding balls with a diameter of 2mm at a ball-to-material ratio of 1:1. Adjust the speed of the mechanical stirring impeller to 2000r / min. The grinding tank is cooled by circulating water to stabilize the temperature of the grinding tank and the internal stirring solution. After stirring for 3 hours, sieve the mixture through a 20-mesh stainless steel sieve to remove the zirconium carbide grinding balls. After filtering the zirconium carbide grinding balls, a suspension is obtained.

[0149] S2, the suspension is evenly spread in a quartz tray and freeze-dried in a vacuum freeze dryer for 72 hours to obtain composite powder;

[0150] S3. The composite powder obtained in S2 is loaded into a vacuum tube furnace and protected with hydrogen gas at a pressure of 0.02 MPa. The heating rate is set to 10℃ / min, the holding temperature is 300℃, and the holding time is 2h to allow the dispersant to fully volatilize and obtain pure aluminum powder.

[0151] S4. The aluminum powder in S3 is placed in a steel mold with a diameter of 20mm. The initial pressing is carried out with a first pressure of 3MPa and a holding time of 3min to obtain a billet intermediate with a lower density. The billet intermediate is then placed back into the mold and repressed with a second pressure of 25MPa and a holding time of 3min to obtain a billet with a higher density.

[0152] S5. The billet is placed in a corundum ceramic boat and then placed in a vacuum tube furnace. Hydrogen gas with a flow rate of 200 ml / min is introduced for protection. The heating rate is set to 10℃ / min to raise the temperature to 550℃. After holding at this temperature for 2 hours, the material is cooled with the furnace to obtain aluminum-based material.

[0153] The materials obtained in Examples 1-4 and Comparative Examples 1-3 were used as research objects. Density, conductivity, and Vickers hardness were characterized and analyzed using a densitometer, eddy current conductivity meter, and Vickers hardness tester, respectively. The results are shown in Table 1. Furthermore, the graphene-aluminum composite powder in Example 1 was subjected to electron microscopy scanning, and electron micrographs of the stacked graphene-aluminum composite powder were obtained (e.g., ...). Figure 3 (as shown), surface electron micrographs of a single graphene-aluminum composite powder (e.g.) Figure 4 As shown), the graphene-reinforced aluminum matrix composite material in Example 1 was subjected to electron microscopy scanning to obtain electron micrographs of the graphene-reinforced aluminum matrix composite material (as shown). Figure 5 (As shown).

[0154] Table 1

[0155]

[0156] Compare the data from Examples 1-4 in Table 1 with those from Comparative Examples 1-3, and combine them with... Figure 3 , Figure 4 and Figure 5 As shown, in the graphene-reinforced aluminum matrix composite prepared in the embodiments of this application, the graphene exhibits good dispersion and structural integrity, resulting in good formability. The mechanical properties such as density and Vickers hardness, as well as the electrical properties such as conductivity, are improved. Compared with Examples 2, 3, and 4, Example 1 demonstrates that the parameters of the dispersion medium, dispersant, and ball milling process used in the preparation method provided in the embodiments of this application can all be adjusted within a certain set range, and can also achieve a good improvement effect on the graphene-reinforced aluminum matrix composite.

[0157] The technical solutions provided by the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method of producing a graphene-reinforced aluminum matrix composite material, characterized by, The method comprises the following steps: S1, dispersing graphene powder in a dispersion medium to form a graphene suspension of graphene monomer particles; S2, adding a low-temperature volatile dispersant into the graphene suspension, and then adding aluminum powder to ball mill and mix together, so that the surface of aluminum powder particles dispersively adheres to several graphene monomer particles to form graphene-aluminum composite powder, and a composite powder suspension is obtained; S3, removing the dispersion medium in the composite powder suspension, and drying to obtain the composite powder; S4, heating the composite powder in a reducing gas atmosphere at a first temperature to remove the dispersant, and obtaining graphene-aluminum composite powder; S5, performing powder metallurgy sintering on the graphene-aluminum composite powder to obtain graphene reinforced aluminum matrix composite material.

2. The method for preparing graphene-reinforced aluminum-based composite materials according to claim 1, characterized in that, In the S1, the graphene powder is prepared by physical exfoliation; and / or the dispersion medium comprises at least one of water, ethanol and ethylene glycol; and / or the mass ratio of the graphene to the dispersion medium is ≤2:98; and / or the mechanical stirring is used to disperse the graphene powder in the dispersion medium, and the stirring rate is 500-3000 r / min. In the S2, the dispersant comprises at least one of high-molecular polyurethane block copolymer, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer and Tween 80; and / or the volume ratio of the graphene suspension to the dispersant is 500:(1-10); and / or the ball milling and mixing are performed under water bath cooling condition; and / or the ball milling and mixing are performed with a ball-to-material ratio of 1:(1-3); and / or the types of the grinding balls used in the ball milling and mixing include at least one of zirconium carbide, ceramic, silicon carbide, titanium carbide and aluminum oxide; and / or the diameter of the grinding balls is ≤5 mm; and / or the content of graphene in the graphene-aluminum composite powder is ≤2%. In the S3, the drying is performed by freeze drying. In the S4, the reducing gas atmosphere comprises hydrogen; and / or the first temperature is 200-600℃; and / or the heating time of the composite powder is 1-3 h. The S5 comprises:

3. The method for preparing graphene-reinforced aluminum-based composite materials according to claim 1, characterized in that, S51, pressing the graphene-aluminum composite powder into a blank; S52, sintering the blank in a reducing gas atmosphere to obtain the graphene reinforced aluminum matrix composite material. The S51 comprises: firstly, pressing the graphene-aluminum composite powder at a first pressure for a first time to obtain a blank intermediate; secondly, pressing the blank intermediate at a second pressure for a second time to obtain the blank; wherein the first pressure is less than the second pressure. In the S51, the first pressure is 3-7 MPa; and / or the second pressure is 20-30 MPa; and / or the first time is 2-5 min; and / or the second time is 2-5 min. In the S52, the reducing gas atmosphere comprises hydrogen; and / or the sintering temperature is 500-600℃; and / or the sintering time is 1-3 h.

4. The method of claim 1, wherein the graphene-reinforced aluminum matrix composite is prepared by a process comprising: providing a graphene dispersion; providing an aluminum alloy; and mixing the graphene dispersion and the aluminum alloy to form a graphene-reinforced aluminum matrix composite. The graphene reinforced aluminum matrix composite material is prepared by the method according to any one of claims 1-9.

5. The method of claim 1, wherein the graphene-reinforced aluminum matrix composite is prepared by a process comprising: providing a graphene dispersion; providing an aluminum alloy; and combining the graphene dispersion and the aluminum alloy to form a graphene-reinforced aluminum matrix composite. ​ ​ ​ ​ 6. The method of claim 1, wherein the graphene-reinforced aluminum matrix composite is prepared by a process comprising: providing a graphene dispersion; providing an aluminum alloy; and combining the graphene dispersion and the aluminum alloy to form a graphene-reinforced aluminum matrix composite. ​ ​ ​ 7. The method of claim 6, wherein the graphene reinforced aluminum matrix composite is prepared by a process comprising: providing a graphene dispersion; providing an aluminum alloy; and combining the graphene dispersion and the aluminum alloy to form the graphene reinforced aluminum matrix composite. 7 ​ ​ ​ ​ 8. The method of claim 7, wherein the graphene reinforced aluminum matrix composite is prepared by a process comprising: providing a graphene dispersion; providing an aluminum alloy; and combining the graphene dispersion and the aluminum alloy to form the graphene reinforced aluminum matrix composite. 8 ​ ​ ​ ​ ​ 9. The method of claim 6, wherein the graphene-reinforced aluminum matrix composite is prepared by a process comprising: providing a graphene dispersion; providing an aluminum alloy; and combining the graphene dispersion and the aluminum alloy to form a graphene-reinforced aluminum matrix composite. ​ ​ ​ ​ 10. A graphene-reinforced aluminum matrix composite material, characterized by, ​

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