Nano-copper modified reduced graphene oxide powder, high-strength and high-conductivity graphene copper-plated-aluminum-based composite material and preparation method of high-strength and high-conductivity graphene copper-plated-aluminum-based composite material

Abstract

The invention discloses a nano-copper modified reduced graphene oxide powder preparation method, which comprises: S1, uniformly mixing a reduced graphene oxide dispersion liquid and a copper chloride solution to obtain a mixed liquid A; s2, reducing the mixed solution A by adopting a reducing agent to obtain a mixed solution B; s3, adjusting the pH value of the mixed solution B to 8-9 to obtain a mixed solution C; s4, titrating the mixed solution C with an alkaline solution until the mixed solution C is red, and standing and filtering to obtain a precipitate D; s5, washing the precipitate D until the pH value of supernatant liquid is neutral, and drying to obtain a precipitate E; and S6, sintering the precipitate E in an inert atmosphere to obtain the nano-copper modified reduced graphene oxide powder. The invention further discloses the nano-copper modified reduced graphene oxide powder, the high-strength and high-conductivity graphene copper plating-aluminum matrix composite and a preparation method of the high-strength and high-conductivity graphene copper plating-aluminum matrix composite.

Description

Technical Field

[0001] The present invention relates to the technical field of copper-based composite materials, and in particular to a high-strength and high-conductivity graphene-plated copper-aluminum-based composite material and a preparation method thereof. Background Art

[0002] Aluminum is the metal element with the highest content in the earth's crust. Pure aluminum has the characteristics of low density, high electrical conductivity, high thermal conductivity, corrosion resistance, and machinability. Based on the above advantages, pure aluminum or aluminum alloys are widely used in aluminum wires and cables in the electrical field, panels, doors and windows in the construction industry, and shells and stampings in the automotive industry. However, with the continuous development of high-performance materials, the requirements for aluminum or aluminum alloys are increasing, especially in the field of electrical conductivity and mechanical properties. The electrical conductivity of aluminum is second only to silver and copper.

[0003] At present, many composite materials have different preparation schemes for mechanical properties or electrical conductivity, especially for mechanical properties, various reinforcement phases emerge in an endless stream. But there are relatively few reports on improving electrical conductivity, and high-quality graphene has appeared in recent years, and graphene not only has excellent electrical properties and perfect structure, but also shows peculiar performance in other aspects, such as outstanding thermal conductivity, high light transmittance, extraordinary strength, etc., which makes graphene a new generation of metal reinforcement phase, making it possible to improve the mechanical properties and electrical conductivity of composite materials at the same time. Therefore, the present invention solves the phenomenon that graphene is easily agglomerated in metal as reinforcement phase by modification of graphene to a large extent, and improves the problem of poor wettability with metal, and obtains an aluminum-based composite material that mechanical properties and electrical conductivity are improved at the same time. Summary of the invention

[0004] To solve the above problems, the present invention provides a method for preparing nano-copper modified reduced graphene oxide powder, comprising:

[0005] S1: mixing the reduced graphene oxide dispersion and the copper chloride solution uniformly to obtain a mixed solution A;

[0006] S2: reducing the mixed solution A with a reducing agent to obtain a mixed solution B;

[0007] S3: adjusting the pH of the mixed solution B to 8-9 to obtain a mixed solution C;

[0008] S4: titrating the mixed solution C with an alkaline solution until the mixed solution C turns red, and filtering the mixed solution to obtain a precipitate D;

[0009] S5: washing the precipitate D until the supernatant has a neutral pH, and drying to obtain a precipitate E;

[0010] S6: Sintering the precipitate E in an inert atmosphere to obtain nano-copper modified reduced graphene oxide powder.

[0011] Furthermore, the preparation method of the reduced graphene oxide dispersion is: fully and uniformly mixing the reduced graphene oxide, polyethylene glycol and water;

[0012] Preferably, the mass ratio of carbon to polyethylene glycol in the reduced graphene oxide is 1:(3-8), more preferably 1:4;

[0013] Preferably, the mixing method is ultrasonic dispersion, and the time is 1-3 hours, preferably 2 hours.

[0014] Furthermore, the preparation method of the cupric chloride solution is: fully and evenly mixing cupric chloride dihydrate and water; preferably, the mass ratio of carbon in the reduced graphene oxide to copper in cupric chloride dihydrate is 1:(5-20), and more preferably 1:10.

[0015] Furthermore, in step S1, during the mixing process, mechanical stirring or electromagnetic stirring is used for mixing;

[0016] Preferably, the mixing temperature is 20-50°C, more preferably 25-40°C;

[0017] Preferably, the mixing time is 5-60 min, more preferably 10-40 min.

[0018] And / or, in step S2, the reducing agent is one or more of hydrazine hydrate, sodium borohydride, and lithium borohydride; preferably, the reducing agent is hydrazine hydrate;

[0019] Preferably, the mass ratio of copper to hydrazine hydrate in the cupric chloride dihydrate is 1:(5-20), more preferably 1:8;

[0020] Preferably, during the reduction process, the solution temperature is 20-50°C, more preferably 25-40°C;

[0021] and / or, in step S3, using aqueous ammonia to adjust the pH;

[0022] And / or, in step S4, the alkaline solution is a sodium hydroxide solution.

[0023] Further, in step S5, the drying is carried out in a vacuum drying oven;

[0024] Preferably, the drying temperature is 70-90°C; more preferably 75-85°C;

[0025] Preferably, the drying time is 20-40 hours, more preferably 25-35 hours.

[0026] And / or, in step S6, the sintering temperature is 200-350°C; more preferably 250-300°C;

[0027] Preferably, the sintering time is 30-60 min; more preferably 40-50 min;

[0028] Preferably, the gas of the inert environment is nitrogen or argon;

[0029] Preferably, before sintering, the precipitate E is ground into powder.

[0030] The present invention also discloses a nano-copper modified reduced graphene oxide powder, which is prepared by the above method. The mass ratio of C to Cu in the nano-copper modified reduced graphene oxide powder is 1:(5-20), preferably 1:(10-15).

[0031] Further, including:

[0032] (1) uniformly mixing the nano-copper modified reduced graphene oxide powder and aluminum powder;

[0033] (2) placing the mixed powder described in step (1) into a molding die and sintering the mixture to obtain a composite material. Further, the mixture is mixed by ball milling;

[0034] Preferably, the ball milling mixing method is: ball milling for 5 minutes clockwise or counterclockwise, stopping for 15 minutes, and repeating the above operation without changing the direction;

[0035] Preferably, the effective ball milling time is 60-180 min, preferably 90-150 min;

[0036] Preferably, the diameter of the grinding balls for ball milling is 2-7 mm, preferably 3-6 mm;

[0037] Preferably, the mass ratio of the grinding balls mixed by the grinding ball mill to the mixed powder of the nano-copper modified reduced graphene oxide powder and the aluminum powder is (3-7):1, preferably (4-5):1;

[0038] Preferably, the rotation speed of the ball milling mixing is 200-400 r / min, preferably 250-350 r / min;

[0039] Preferably, the sintering is performed by SPS sintering;

[0040] Preferably, the aluminum powder is pure aluminum powder or alloy aluminum powder; wherein the alloy aluminum powder is 2024 aluminum powder or 6061 aluminum powder;

[0041] Preferably, the diameter of the aluminum powder is 27-50 μm, more preferably 40 μm.

[0042] Furthermore, in step (2), the SPS sintering molding pressure is 5-40Mpa, and more preferably 25Mpa;

[0043] Preferably, the sintering molding temperature is 570°C to 620°C, more preferably 590°C;

[0044] Preferably, the sintering molding time is 30-90 minutes, more preferably 40 minutes.

[0045] The present invention also discloses a high-strength and high-conductivity graphene-plated copper-aluminum-based composite material, which is prepared by the preparation method;

[0046] The mass fraction of reduced graphene oxide in the composite material is 0.05-0.4wt%, the mass fraction of nano copper is 0.5-4wt%, and the rest is aluminum;

[0047] Preferably, the mass fraction of reduced graphene oxide in the composite material is 0.3wt%, the mass fraction of nano copper is 4.5wt%, and the rest is aluminum matrix.

[0048] The inventive principle of the present invention is as follows: in an aqueous environment, a strong reducing agent is used to reduce the nano copper element in the compound, and the nano copper and reduced graphene oxide are self-assembled by a high-speed stirring + sedimentation method to form a reinforced phase powder; since reduced graphene oxide does not have good surface compatibility with metals, nano copper is introduced on the surface of reduced graphene oxide to enhance the compatibility with the copper matrix, and at the same time, the specific gravity of the original reduced graphene oxide is increased, which is more conducive to subsequent uniform dispersion by ball milling, thereby achieving the improvement of mechanical properties; and the reduced graphene oxide has excellent conductivity, and can improve the conductivity of the aluminum matrix under the premise of uniform mixing.

[0049] Then, the nano-copper modified graphene powder and aluminum powder were mixed by ball milling. The ball milling process adopted reciprocating gap ball milling. Under the premise of sufficient ball milling, the aluminum powder was guaranteed not to be cold welded during the high-energy ball milling process, thus ensuring the stability of the mixed powder. Finally, the nano-copper modified graphene powder and aluminum powder were sintered by hot pressing to prepare nano-copper modified graphene enhanced conductive aluminum matrix composite material, which effectively solved the problems of composite material forming and density, improved the bonding and density between graphene and aluminum matrix, and the uniform dispersion of nano-copper modified reduced oxide graphene contributed to the comprehensive improvement of mechanical properties and conductive properties of composite materials.

[0050] The high-strength and high-conductivity graphene-plated copper-aluminum-based composite material prepared by the method of the present invention has the following beneficial effects:

[0051] (1) High conductivity: Graphene has excellent electronic conductivity. By copper-plating graphene and combining it with aluminum powder, the conductivity of the composite material can be significantly improved. High conductivity makes composite aluminum materials have more application scenarios.

[0052] (2) Improved mechanical strength: Graphene, as a nano-reinforcement phase, is evenly dispersed in the matrix through modification with nano-copper, overcoming the problem of poor wettability between graphene and the aluminum matrix, improving the mechanical properties of the final composite material, and making it better suitable for various complex usage scenarios.

[0053] (3) The process of the present invention is simple and controllable, and has good repeatability. The required equipment has high production capacity, low cost and low energy consumption, and is suitable for large-scale batch production. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0055] Figure 1 The process flow chart of the present invention for preparing high-strength and high-conductivity graphene-plated copper-aluminum-based composite materials;

[0056] Figure 2 This is a SEM image of nano-copper modified graphene powder in an embodiment of the present invention. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the present invention is specifically described below through examples. This example is only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Those skilled in the art may make some non-essential changes and adjustments based on the contents of the above invention, which all fall within the scope of protection of the present invention.

[0058] The preparation method of the present invention is described in detail below.

[0059] A high-strength and high-conductivity graphene-plated copper-aluminum-based composite material, comprising:

[0060] 1. Preparation of Nano-copper Modified Graphene Powder

[0061] (1) Preparation of reduced graphene oxide dispersion

[0062] The reduced graphene oxide, polyethylene glycol and deionized water are fully mixed and ultrasonically dispersed to obtain a uniform dispersion of the oxidized and reduced graphene oxide, wherein the mass ratio of carbon in the reduced graphene oxide to polyethylene glycol is 1:(3-8), such as 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, and more preferably 1:4.

[0063] The mass ratio of carbon in the reduced graphene oxide to polyethylene glycol is 1:(3-8). Within this mass ratio range, polyethylene glycol can disperse the reduced graphene oxide as much as possible, and the subsequent calcination of the powder to remove polyethylene glycol does not consume a lot of time.

[0064] (2) placing cupric chloride dihydrate (CuCl2·2H2O) in deionized water and stirring, and after fully dissolving, mixing with the reduced graphene oxide dispersion, and fully stirring until the mixture is uniformly mixed, wherein the mass ratio of the reduced graphene oxide to cupric chloride dihydrate is 1:(5-20), for example, 1:5, 1:10, 1:15, 1:20, preferably 1:10, the mixing and stirring temperature is 20-50°C, for example, 20°C, 30°C, 40°C, 50°C, preferably 25-40°C, and the stirring time is 5-60min, for example, 5min, 10min, 20min, 30min, 40min, 50min, 60min, preferably 10-40min.

[0065] (3) Dissolve hydrazine hydrate (N2H4·H2O) in deionized water, stir evenly, mix with the mixed solution of step (2), stir evenly, the mass ratio of copper element in the cupric chloride dihydrate to hydrazine hydrate is 1:(5-20), for example 1:5, 1:10, 1:15, 1:20, preferably 1:8, the stirring temperature is 20-50°C, for example 20°C, 30°C, 40°C, 50°C, preferably 25-40°C, the stirring time is 5-30min, for example 5min, 10min, 20min, 30min. At this time, the Cu in the cupric chloride dihydrate is 1:(5-20), for example 1:5, 1:10, 1:15, 1:20, preferably 1:8, the stirring temperature is 20-50°C, for example 20°C, 30°C, 40°C, 50°C, preferably 25-40°C, the stirring time is 5-30min, for example 5min, 10min, 20min, 30min. 2+ is fully reduced to Cu particles.

[0066] Based on the above, the amount of copper sulfate pentahydrate is determined, thereby determining the amount of reducing agent sodium borohydride; at room temperature or in a heated environment, it is more conducive to the solution to undergo a reduction reaction under stirring conditions, and the time decreases as the temperature increases.

[0067] (4) Add ammonia water to the mixed solution of step (3), stir thoroughly, and keep the solution in an alkaline environment.

[0068] (5) Sodium hydroxide is fully dissolved in deionized water, and then slowly and uniformly added to the mixed solution obtained in step (4) until the solution turns red. After the titration is completed, the mixture is stirred for 10-30 minutes and then allowed to stand to precipitate. The temperature of the reaction system during the whole process is 20-50°C

[0069] During the titration process, the solution gradually turns red. After the titration of the sodium hydroxide solution is completed, continue stirring for 30 minutes to allow for full reaction, and then let it stand and wait for precipitation.

[0070] (6) The precipitate obtained in step (5) is repeatedly washed until the pH of the supernatant is neutral, filtered and dried in a vacuum drying oven for 20 h to 40 h, for example, 20 h, 25 h, 30 h, 35 h, 40 h, preferably 25 to 35 h, and the drying temperature is 70°C to 90°C, for example, 70°C, 80°C, 90°C, preferably 75 to 85°C.

[0071] The purpose of washing is to remove excess sodium hydroxide, and the purpose of sufficient drying is to remove excess water in the precipitate to form blocks or powder.

[0072] (7) Sintering under an inert environment to remove residual polyethylene glycol, the sintering temperature is 200-350° C., for example, 200° C., 240° C., 260° C., 300° C., 320° C., 350° C., preferably 250-300° C. The sintering time is 30-60 min, for example, 30 min, 40 min, 50 min, 60 min, preferably 40-50 min.

[0073] This step is to volatilize the excess polyethylene glycol in the powder to ensure the purity of the powder.

[0074] Figure 2 The SEM image of the nano-copper modified reduced graphene oxide powder provided for some embodiments of the present invention shows that the nano-copper particles are evenly distributed on the surface of the graphene sheet. These particles show a smaller size and a more even distribution, indicating that the preparation method effectively realizes the modification of reduced graphene oxide by nano-copper. The distribution of the nano-copper particles on the graphene sheet is more even, and the evenly distributed nano-copper particles can enhance the interface bonding between graphene and the copper matrix, thereby improving the mechanical properties and electrical conductivity of the composite material. In summary, these characteristics show that the preparation method of the present invention effectively realizes the modification of reduced graphene oxide by nano-copper, and the prepared nano-copper modified reduced graphene oxide powder has good structure and performance, and is suitable for preparing high-performance nano-copper modified graphene copper-based composite materials.

[0075] 2. Preparation of composite powder

[0076] Weigh a certain amount of the nano-copper modified graphene powder and aluminum powder obtained in step 1, and mix them thoroughly in a ball mill, wherein the mass fraction of the reduced graphene oxide is 0.05-0.4wt%, for example, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, the mass fraction of the nano-copper is 0.5-4wt%, for example, 0.5%, 1%, 2%, 3%, 4%, 5%, and the rest is aluminum powder.

[0077] In this step, when preparing nano-copper modified graphene powder in step 1, the reduced graphene oxide and cupric chloride dihydrate added in the preparation process have a certain mass ratio, so when step 1 is completed, the mass ratio of reduced graphene oxide to nano-copper in the nano-copper modified reduced graphene oxide powder is also a fixed value. Then, the amount of copper matrix added is determined according to the need to prepare the final composite material product.

[0078] In the present invention, the mass fraction of reduced graphene oxide is 0.05-0.4wt%, the mass fraction of nano copper is 0.5-4wt%, and the rest is aluminum powder.

[0079] In the present invention, the aluminum powder can be spherical powder, and the powder particle size is 27-50 μm, preferably 40 μm. The aluminum powder can also be replaced by other alloy aluminum powders, such as 2024 aluminum powder, 6061 aluminum powder, etc., as long as the product content of the aluminum matrix in the final composite material can be met, and there is no limitation here.

[0080] In the present invention, high-energy ball milling can be performed in a planetary ball mill. The grinding balls can be stainless steel grinding balls, alumina grinding balls, etc. The diameter of the grinding balls is 2-7 mm, for example, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm. The mass ratio of the grinding balls to the mixed powder is (3-7): 1, for example, 3: 1, 4: 1, 5: 1, 6: 1, 7: 1. The ball milling speed is 200-400 r / min, for example, 200 r / min, 250 r / min, 300 r / min, 350 r / min, 400 r / min, preferably 250-350 r / min. Each time, the ball milling is performed clockwise or counterclockwise for 5 min, and then stopped for 15 min. The direction is changed, and the ball milling is performed for 5 min and then stopped for 15 min. The cumulative effective ball milling time is 60-180 min, for example, 60 min, 80 min, 100 min, 120 min, 140 min, 160 min, 180 min, and preferably 90-150 min. After the ball milling, the grinding balls are sieved to obtain the composite powder.

[0081] In the present invention, a planetary ball mill can be used for high-energy ball milling. The grinding balls are stainless steel grinding balls with a grinding ball diameter of 2-7 mm, a ball-to-material mass ratio of (3-7): 1, a ball milling speed of 200-400 r / min, clockwise ball milling for 20 minutes each time, stop for 10 minutes, change the direction, counterclockwise ball milling for 20 minutes, stop for 10 minutes, the cumulative effective ball milling time is 60-180 minutes, and after the ball milling is completed, the grinding balls are sieved to obtain a composite powder. This ball milling process adopts a reciprocating gap ball milling. Using this ball milling process ensures that the aluminum powder will not be cold-welded during the high-energy ball milling process under the premise of sufficient ball milling, thereby ensuring the stability of the mixed powder.

[0082] 3. Preparation of aluminum matrix composites

[0083] The composite powder obtained in step 2 is filled in a mold and subjected to SPS sintering. The temperature of SPS sintering is 570°C-620°C, such as 570°C, 580°C, 590°C, 600°C, 610°C, 620°C, preferably 590°C; the sintering time is 30min-90min, such as 30min, 40min, 50min, 60min, 70min, 80min, 90min, preferably 40min, and the sintering pressure is 5-40MPa, such as 5MPa, 10MPa, 20MPa, 30MPa, 40MPa, preferably 25Mpa. Then cool with the furnace, and take out when the temperature drops below 80°C to obtain a nano-copper modified graphene enhanced conductive copper-based composite material.

[0084] The mold filled with composite powder can be a graphite mold or a steel mold. The shape of the mold can be a cuboid, a cylinder, etc. It can be selected according to actual needs and is not limited here.

[0085] The following is a detailed description of the preparation method of the high-strength and high-conductivity graphene copper-plated-aluminum-based composite material based on a preferred embodiment:

[0086] Embodiment 1:

[0087] A high-strength and high-conductivity copper-plated graphene-aluminum-based composite material and a preparation method thereof, which specifically comprises the following steps:

[0088] S1: Preparation of graphene copper-plated powder

[0089] Weigh 0.5g of reduced graphene oxide and 2g of polyethylene glycol, place them in 400ml of deionized water, and ultrasonically disperse them for 2h to fully open the graphene sheets; weigh 13.4g of cupric chloride dihydrate, place them in 500ml of deionized water, stir and dissolve them, then pour them into the graphene solution after ultrasonication, heat the mixture in a 40°C water bath and mechanically stir for 1h to make the solution fully uniform; weigh 25ml of hydrazine hydrate, place them in 300ml of deionized water, stir them evenly, and add them to the above mixture at a uniform speed, keep heating in a 40°C water bath and mechanically stir them 10min; then place the reaction system at room temperature, add 10ml of ammonia water, and continue stirring for 5min; weigh 15g of sodium hydroxide powder and dissolve it in 250ml of deionized water, and then slowly titrate it into the mixture at a uniform speed; after the titration, stir the reaction for 30min and then let it stand to precipitate, repeatedly wash the precipitate to make the pH value of the supernatant neutral, vacuum dry the precipitate at 70℃ for 30h, and after grinding, sinter in a tubular furnace at 250℃ in a nitrogen environment for 40min to remove residual PEG, and obtain graphene copper-plated powder.

[0090] S2: Preparation of composite powder

[0091] Weigh a certain amount of graphene copper-plated powder and pure aluminum powder and put them in a planetary ball mill for high-energy ball milling, where the mass fraction of graphene is 0.1%, the mass fraction of copper is 1%, and the rest is aluminum. Stainless steel grinding balls are used, the grinding ball diameter is 3mm, the ball-to-material ratio is 5:1, the ball milling speed is 240r / min, each ball milling is 5min, stop for 15min, and the ball milling direction remains unchanged, the total ball milling is 8h, and the cumulative effective ball milling time is 120min. After the ball milling is completed, the grinding balls are sieved out to obtain the composite powder.

[0092] S3: Preparation of aluminum matrix composites

[0093] The composite powder obtained in S2 was filled into a graphite mold with a diameter of 60 mm, and sintered in a plasma discharge sintering furnace. The heat and pressure were maintained at a pressure of 30 MPa and a temperature of 615°C for 40 minutes, and then cooled with the furnace to obtain a high-strength and high-conductivity copper-plated graphene-aluminum-based composite material.

[0094] Embodiment 2:

[0095] A high-strength and high-conductivity copper-plated graphene-aluminum-based composite material and a preparation method thereof, which specifically comprises the following steps:

[0096] S1: Preparation of graphene copper-plated powder

[0097] Weigh 0.5g of reduced graphene oxide and 3g of polyethylene glycol, place them in 400ml of deionized water, and ultrasonically disperse them for 2h to fully open the graphene sheets; weigh 26.8g of cupric chloride dihydrate, place them in 500ml of deionized water, stir and dissolve them, then pour them into the graphene solution after ultrasonication, place the mixed solution in a 40°C water bath and mechanically stir for 1h to make the solution fully uniform; weigh 50ml of hydrazine hydrate, place them in 300ml of deionized water and stir them evenly, and add them to the above mixed solution at a uniform speed, keep heating in a 40°C water bath and mechanically stir them 10min; then place the reaction system at room temperature, add 15ml of ammonia water, and continue stirring for 5min; weigh 30g of sodium hydroxide powder and dissolve it in 250ml of deionized water, and then slowly titrate it into the mixture at a uniform speed; after the titration is completed, stir the reaction for 30min and then let it stand to precipitate, repeatedly wash the precipitate to make the pH value of the supernatant neutral, vacuum dry the precipitate at 80℃ for 24h, and after grinding, sinter in a tubular furnace at 300℃ in a nitrogen environment for 30min to remove residual PEG, and obtain graphene copper-plated powder.

[0098] S2: Preparation of composite powder

[0099] A certain amount of graphene copper-plated powder and pure aluminum powder were weighed and put into a planetary ball mill for high-energy ball milling, wherein the mass fraction of graphene was 0.1%, the mass fraction of copper was 2%, and the rest was aluminum. Stainless steel grinding balls were used for grinding balls, the diameter of the grinding balls was 4 mm, the ball-to-material ratio was 6:1, the ball milling speed was 200 r / min, each ball milling was 5 min, and stopped for 15 min, and the ball milling direction remained unchanged, for a total of 9 h, and the cumulative effective ball milling time was 135 min. After the ball milling was completed, the grinding balls were sieved to obtain the composite powder.

[0100] S3: Preparation of aluminum matrix composites

[0101] The composite powder obtained in S2 is filled in a graphite mold with a diameter of 60 mm, and sintered in a plasma discharge sintering furnace. The heat and pressure are maintained at a pressure of 40 MPa and a temperature of 620°C for 40 minutes, and then cooled in the furnace to obtain a high-strength and high-conductivity copper-plated graphene-aluminum-based composite material.

[0102] Embodiment 3:

[0103] A high-strength and high-conductivity copper-plated graphene-aluminum-based composite material and a preparation method thereof, which specifically comprises the following steps:

[0104] S1: Preparation of graphene copper-plated powder

[0105] Weigh 0.5g of reduced graphene oxide and 2g of polyethylene glycol, place them in 400ml of deionized water, and ultrasonically disperse them for 2h to fully open the graphene sheets; weigh 13.4g of cupric chloride dihydrate, place them in 500ml of deionized water, stir and dissolve them, then pour them into the graphene solution after ultrasonication, place the mixed solution in a 40°C water bath and mechanically stir for 1h to make the solution fully uniform; weigh 25ml of hydrazine hydrate, place them in 300ml of deionized water and stir them evenly, and add them to the above mixed solution at a uniform speed, keep heating in a 40°C water bath and mechanically stir them 10min; then place the reaction system at room temperature, add 20ml of ammonia water, and continue stirring for 5min; weigh 15g of sodium hydroxide powder and dissolve it in 250ml of deionized water, and then slowly titrate it into the mixed solution at a uniform speed; after the titration is completed, stir the reaction for 30min and then let it stand to precipitate, repeatedly wash the precipitate to make the pH value of the supernatant neutral, vacuum dry the precipitate at 80℃ for 30h, and after grinding, sinter in a tubular furnace at 350℃ in a nitrogen environment for 20min to remove residual PEG, and obtain graphene copper-plated powder.

[0106] S2: Preparation of composite powder

[0107] Weigh a certain amount of graphene copper-plated powder and pure aluminum powder and put them in a planetary ball mill for high-energy ball milling, where the mass fraction of graphene is 0.2%, the mass fraction of copper is 2%, and the rest is aluminum. Stainless steel grinding balls are used, the grinding ball diameter is 3mm, the ball-to-material ratio is 4:1, the ball milling speed is 350r / min, each ball milling is 5min, stop for 15min, and the ball milling direction remains unchanged, the total ball milling is 6h, and the cumulative effective ball milling time is 90min. After the ball milling is completed, the grinding balls are sieved to obtain the composite powder.

[0108] S3: Preparation of aluminum matrix composites

[0109] The composite powder obtained in S2 is filled in a graphite mold with a diameter of 60 mm, and sintered in a plasma discharge sintering furnace. The heat and pressure are maintained at a pressure of 30 MPa and a temperature of 570°C for 40 minutes, and then cooled in the furnace to obtain a high-strength and high-conductivity copper-plated graphene-aluminum-based composite material.

[0110] Example 4

[0111] A high-strength and high-conductivity copper-plated graphene-aluminum-based composite material and a preparation method thereof, which specifically comprises the following steps:

[0112] S1: Preparation of graphene copper-plated powder

[0113] Weigh 0.5g of reduced graphene oxide and 4g of polyethylene glycol, place them in 400ml of deionized water, and ultrasonically disperse them for 2h to fully open the graphene sheets; weigh 20.1g of cupric chloride dihydrate, place them in 500ml of deionized water, stir and dissolve them, then pour them into the graphene solution after ultrasonication, heat the mixture in a 40°C water bath and mechanically stir for 1h to make the solution fully uniform; weigh 40ml of hydrazine hydrate, place them in 300ml of deionized water, stir them evenly, and add them to the above mixture at a uniform speed, keep heating in a 40°C water bath and mechanically stir them 10min; then place the reaction system at room temperature, add 10ml of ammonia water, and continue stirring for 5min; weigh 20g of sodium hydroxide powder and dissolve it in 250ml of deionized water, and then slowly titrate it into the mixed solution at a uniform speed; after the titration is completed, stir the reaction for 30min and then let it stand to precipitate, repeatedly wash the precipitate to make the pH value of the supernatant neutral, vacuum dry the precipitate at 80℃ for 24h, and after grinding, sinter in a tubular furnace at 300℃ in a nitrogen environment for 25min to remove residual PEG, thereby obtaining graphene copper-plated powder.

[0114] S2: Preparation of composite powder

[0115] Weigh a certain amount of graphene copper-plated powder and pure aluminum powder and put them in a planetary ball mill for high-energy ball milling, where the mass fraction of graphene is 0.3%, the mass fraction of copper is 4.5%, and the rest is aluminum. Stainless steel grinding balls are used for grinding balls, the diameter of the grinding balls is 5mm, the ball-to-material ratio is 5:1, the ball milling speed is 300r / min, each ball milling is 5min, stop for 15min, and the ball milling direction remains unchanged, the total ball milling is 10h, and the cumulative effective ball milling time is 150min. After the ball milling is completed, the grinding balls are sieved out to obtain the composite powder.

[0116] S3: Preparation of aluminum matrix composites

[0117] The composite powder obtained in S2 is filled in a graphite mold with a diameter of 80 mm, and sintered in a plasma discharge sintering furnace. The heat and pressure are maintained at a pressure of 25 MPa and a temperature of 590°C for 40 minutes, and then cooled in the furnace to obtain a high-strength and high-conductivity copper-plated graphene-aluminum-based composite material.

[0118] Embodiment 5:

[0119] In this embodiment, the mass fraction of graphene in the composite material is 0.4%, the mass fraction of copper is 4%, and the remainder is aluminum. The other reaction conditions are the same as those in Example 1.

[0120] Comparative Example 1:

[0121] S1: Preparation of composite powder

[0122] Weigh a certain amount of graphene powder, copper powder and pure aluminum powder and put them together in a planetary ball mill for high-energy ball milling, where the mass fraction of graphene is 0.2%, the mass fraction of copper is 2%, and the rest is aluminum. Stainless steel grinding balls are used for grinding balls, the diameter of the grinding balls is 5mm, the ball-to-material ratio is 5:1, the ball milling speed is 250r / min, each ball milling is 5min, stop for 15min, and the ball milling direction remains unchanged, the total ball milling is 10h, and the cumulative effective ball milling time is 150min. After the ball milling is completed, the grinding balls are sieved out to obtain composite powder.

[0123] S2: Preparation of aluminum matrix composites

[0124] The composite powder obtained in S1 was filled into a graphite mold with a diameter of 60 mm, and sintered in a plasma discharge sintering furnace. The temperature and pressure were maintained at 40 MPa and 600° C. for 40 min, and then cooled in the furnace to obtain an aluminum-based composite material.

[0125] Comparative Example 2:

[0126] In this comparative example, graphene is replaced by conductive carbon black, and the mass fraction of the conductive carbon black is 0.3%, the mass fraction of copper is 3%, and the rest is aluminum. The other reaction conditions are the same as those in comparative example one.

[0127] The high-strength and high-conductivity copper-plated graphene-aluminum-based composite materials prepared in Examples 1-5 and Comparative Examples 1-2 were tested for mechanical strength and electrical conductivity, and the electrical conductivity was expressed using the international annealed copper electrical conductivity standard. The mechanical strength was expressed by polishing the sample according to the ASTM standard, and a tensile test was performed at a rate of 0.05 mm / s at room temperature. The tests of mechanical strength and electrical conductivity should be performed three or more times. The results are shown in Table 1.

[0128] Table 1 Tensile strength and electrical conductivity of aluminum-based composite materials prepared in Example Comparative Examples

[0129] Material Tensile strength(MPa) Electrical conductivity (IACS%) Example 1 207 65.4 Example 2 221 74.3 Example 3 240 79.7 Example 4 276 84.2 Example 5 310 63.8 Comparative Example 1 190 58.5 Comparative Example 2 203 62.1

[0130] From the test data in Table 1, the tensile strength of the high-strength and high-conductivity copper-plated graphene-aluminum-based composite materials prepared in Examples 1-5 of the present invention is not less than 207 MPa, and can reach up to 310 MPa, and the conductivity is not less than 63.8% IACS, and can reach up to 84.2% IACS. Although different carbon sources or copper are added to the comparative examples, the tensile strength and conductivity are reduced to varying degrees.

[0131] The above embodiments illustrate that the method for preparing a high-strength and high-conductivity copper-plated graphene-aluminum-based composite material provided by the embodiments of the present invention achieves a synergistic improvement in the mechanical strength and electrical properties of the aluminum-based composite material, solves the shortcomings of traditional composite methods, and provides a new idea for the preparation of high-strength and high-conductivity aluminum-based composite materials.

[0132] In summary, the embodiments of the present invention solve the problems of graphene agglomeration and poor wettability with metallic aluminum, and achieve uniform dispersion of modified graphene in aluminum powder by ball milling; at the same time, a method for preparing nano-copper modified graphene enhanced conductive aluminum-based composite material using high temperature and high pressure is provided, which achieves close combination of metallic aluminum and graphene, thereby giving play to the high strength of graphene to improve the strength of aluminum, thereby achieving a dual improvement in the mechanical properties and electrical properties of the graphene aluminum composite material. The process of the present invention is simple and controllable, and has good repeatability, high equipment production capacity, low energy consumption, and is suitable for large-scale batch production. And the chemical plating method used in the preparation of nano-copper modified graphene by the present invention has not been reported yet, which provides a new idea for the preparation of nano-copper modified graphene.

[0133] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions described in the above embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing nano-copper modified reduced graphene oxide powder, characterized in that: include: S1: mixing the reduced graphene oxide dispersion and the copper chloride solution uniformly to obtain a mixed solution A; S2: reducing the mixed solution A with a reducing agent to obtain a mixed solution B; S3: adjusting the pH of the mixed solution B to 8-9 to obtain a mixed solution C; S4: titrating the mixed solution C with an alkaline solution until the mixed solution C turns red, and filtering the mixed solution to obtain a precipitate D; S5: washing the precipitate D until the supernatant has a neutral pH, and drying to obtain a precipitate E; S6: Sintering the precipitate E in an inert atmosphere to obtain nano-copper modified reduced graphene oxide powder.

2. The preparation method according to claim 1, characterized in that: The preparation method of the reduced graphene oxide dispersion is as follows: the reduced graphene oxide, polyethylene glycol and water are fully and uniformly mixed; Preferably, the mass ratio of carbon to polyethylene glycol in the reduced graphene oxide is 1:(3-8), more preferably 1:4; Preferably, the mixing method is ultrasonic dispersion, and the time is 1-3 hours, preferably 2 hours.

3. The preparation method according to claim 1, characterized in that: The preparation method of the copper chloride solution is: fully and evenly mixing copper chloride dihydrate and water; Preferably, the mass ratio of carbon in the reduced graphene oxide to copper in cupric chloride dihydrate is 1:(5-20), and more preferably 1:

10.

4. The preparation method according to claim 1, characterized in that: In step S1, during the mixing process, mechanical stirring or electromagnetic stirring is used for mixing; Preferably, the mixing temperature is 20-50°C, more preferably 25-40°C; Preferably, the mixing time is 5-60 min, more preferably 10-40 min; and / or, in step S2, the reducing agent is one or more of hydrazine hydrate, sodium borohydride, and lithium borohydride; Preferably, the reducing agent is hydrazine hydrate; Preferably, the mass ratio of copper to hydrazine hydrate in the cupric chloride dihydrate is 1:(5-20), more preferably 1:8; Preferably, during the reduction process, the solution temperature is 20-50°C, more preferably 25-40°C; and / or, in step S3, using aqueous ammonia to adjust the pH; And / or, in step S4, the alkaline solution is a sodium hydroxide solution.

5. The preparation method according to claim 1, characterized in that: In step S5, the drying is carried out in a vacuum drying oven; Preferably, the drying temperature is 70-90°C; more preferably 75-85°C; Preferably, the drying time is 20-40 hours, more preferably 25-35 hours; And / or, in step S6, the sintering temperature is 200-350°C; more preferably 250-300°C; Preferably, the sintering time is 30-60 min; more preferably 40-50 min; Preferably, the gas of the inert environment is nitrogen or argon; Preferably, before sintering, the precipitate E is ground into powder.

6. A nano-copper modified reduced graphene oxide powder, characterized in that: The nano-copper modified reduced graphene oxide powder is prepared by any preparation method of claim 1-5, wherein the mass ratio of C to Cu is 1: (5-20), preferably 1: (10-15).

7. A method for preparing a high-strength and high-conductivity graphene-plated copper-aluminum-based composite material, characterized in that: include: (1) uniformly mixing the nano-copper modified reduced graphene oxide powder and aluminum powder according to claim 6; (2) The mixed powder described in step (1) is placed into a molding die and sintered to obtain a composite material.

8. The preparation method according to claim 7, characterized in that: In step (1), mixing is performed by ball milling; Preferably, the ball milling mixing method is: ball milling for 5 minutes clockwise or counterclockwise, stopping for 15 minutes, and repeating the above operation without changing the direction; Preferably, the effective ball milling time is 60-180 min, preferably 90-150 min; Preferably, the diameter of the grinding balls for ball milling is 2-7 mm, preferably 3-6 mm; Preferably, the mass ratio of the grinding balls mixed in the grinding ball mill to the mixed powder of the nano-copper modified reduced graphene oxide powder and the aluminum powder is (3-7):1, preferably (4-5):1; Preferably, the rotation speed of the ball milling mixing is 200-400r / min, preferably 250-350r / min; Preferably, the sintering is performed by SPS sintering; Preferably, the aluminum powder is pure aluminum powder or alloy aluminum powder; wherein the alloy aluminum powder is 2024 aluminum powder or 6061 aluminum powder; Preferably, the diameter of the aluminum powder is 27-50 μm, more preferably 40 μm.

9. The preparation method according to claim 8, characterized in that: In step (2), the SPS sintering molding pressure is 5-40Mpa, more preferably 25Mpa; Preferably, the sintering molding temperature is 570°C to 620°C, more preferably 590°C; Preferably, the sintering molding time is 30-90 minutes, more preferably 40 minutes.

10. A high-strength and high-conductivity graphene-plated copper-aluminum-based composite material, characterized in that: Prepared by any preparation method of claims 7-9; The mass fraction of reduced graphene oxide in the composite material is 0.05-0.4wt%, the mass fraction of nano copper is 0.5-4wt%, and the rest is aluminum; Preferably, the mass fraction of reduced graphene oxide in the composite material is 0.3wt%, the mass fraction of nano copper is 4.5wt%, and the rest is aluminum matrix.

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