Aluminum-based graphene material and method of preparation

Abstract

The application discloses an aluminum-based graphene material and a preparation method, and aims to solve the technical problems of poor interface wettability of graphene and an aluminum matrix, easy agglomeration, secondary agglomeration in a solidification process and difficulty in continuous production. A nano copper coating layer is formed on the surface of graphene through chemical copper plating, so that the interface wettability is improved. The copper-coated graphene powder is uniformly dispersed in an aluminum melt through ultrasonic field and electromagnetic field composite dispersion or synchronous feeding of jet deposition, and then rapid solidification forming is carried out through a Castex continuous casting and extrusion or jet deposition and continuous extrusion integrated process, so that the uniform distribution and densification of graphene in the aluminum matrix are realized. The application is mainly used for high-conductivity and high-strength aluminum-based graphene materials required in the fields of new energy vehicles, 5G communication, rail transit and the like.

Description

Technical Field

[0001] This invention relates to the technical field of metal matrix composite material preparation, and in particular to an aluminum-based graphene material and its preparation method. Background Technology

[0002] Aluminum alloys, due to their low density, corrosion resistance, and ease of processing, have become the most widely used lightweight materials. However, pure aluminum has low strength. Traditional high-strength aluminum alloys such as 6061 and 7075, after strength is improved through alloying and heat treatment, have a significantly reduced conductivity to 40-55% IACS, which is insufficient to meet high conductivity requirements. Graphene, with its extremely high theoretical strength, electrical conductivity, and thermal conductivity, is widely recognized as the ideal reinforcing phase to resolve the contradiction between strength and conductivity in aluminum materials. However, the industrial preparation of aluminum-based graphene materials has long faced four core challenges: poor interfacial wettability, easy graphene agglomeration, secondary agglomeration during solidification, and difficulty in continuous production.

[0003] The contact angle between graphene and molten aluminum exceeds 140°, resulting in extremely poor wettability. Furthermore, at high temperatures, it readily reacts to form the brittle Al₄C₃ phase, severely disrupting the matrix and degrading material properties. The extremely strong van der Waals forces between graphene sheets make them highly susceptible to irreversible agglomeration; neither mechanical stirring, ultrasound, nor electromagnetic fields can completely break up these nanometer-scale agglomerates. Traditional casting has a low cooling rate, only 10... 0 With a solidification rate of -10²K / s and a long solidification time, graphene undergoes segregation and secondary agglomeration at the solid-liquid interface, disrupting the uniform dispersion state in the melt.

[0004] Currently, the main preparation methods each have fatal flaws. Powder metallurgy uses ball milling to mix powders and then sintering. Ball milling easily damages the graphene structure, and the high sintering temperature leads to severe interfacial reactions. Furthermore, it is a batch production method, unsuitable for producing large-sized, complex products. Stirred casting, while low-cost, suffers from graphene floating and burning, severe interfacial reactions, and limited reinforcement effects. Traditional jet deposition has a fast atomization cooling rate, which can suppress interfacial reactions, but it involves numerous steps, requiring the preparation of a deposited blank, followed by sawing, milling, preheating, and extrusion. This results in a long production cycle, high energy consumption, and secondary graphene agglomeration during intermediate processing, with material utilization rates below 70%. Continuous extrusion technology has advantages such as low energy consumption, high efficiency, and high material utilization, but traditional continuous extrusion can only process solid cast blanks and cannot directly introduce nanometer-sized reinforcing phases. Although some research has attempted to combine jet deposition with continuous extrusion, it is still a two-step process of preparing a blank first and then extruding, failing to solve the problems of secondary agglomeration and complex processes. In addition, among existing interface modification technologies, nickel plating significantly reduces conductivity, silver plating is too expensive, aluminum oxide coating reduces strength and conductivity, and grafted organic molecules are easily decomposed at high temperatures. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art.

[0006] To address these issues, this invention proposes an aluminum-based graphene material and its preparation method. The preparation method employs a Castex continuous casting and extrusion process or an integrated process of spray deposition and continuous extrusion. This aims to solve the problems of poor wettability between graphene and the aluminum matrix, easy agglomeration of graphene, secondary agglomeration during solidification, and difficulty in continuous production in existing technologies. The goal is to achieve high conductivity, high strength, short process, and low energy consumption continuous preparation of aluminum-based graphene materials.

[0007] According to an embodiment of the present invention, a method for preparing aluminum-based graphene material is adopted, using the Castex continuous casting and extrusion process, comprising the following steps: Step 1, chemically modifying graphene with copper plating to form a copper coating layer on the graphene surface, obtaining copper-coated graphene powder; Step 2, melting the aluminum matrix material into aluminum melt, and adding the copper-coated graphene powder into the aluminum melt under an inert gas protective atmosphere; wherein, the melting temperature can be 700-780℃, selected according to different alloy systems (1-series aluminum: 700-730℃, to reduce interfacial reactions; 6-series aluminum: 730-760℃, to ensure uniform composition; 8-series aluminum: 750-780℃); the blowing and feeding pressure can be 0.2-0.5MPa; the feeding time can be 5-15min, positively correlated with the amount of graphene added; if the blowing and feeding pressure is too low, the feeding speed is slow, and the graphene is easily burned off; if the blowing and feeding pressure is too high, air entrapment is easily generated. The feeding time is positively correlated with the amount of graphene added: 0.2wt% corresponds to 5-8 min, and 1.0wt% corresponds to 10-15 min. Step 3: The aluminum melt is subjected to composite dispersion treatment using ultrasonic and electromagnetic fields to uniformly disperse the copper-coated graphene powder in the aluminum melt. Step 4: The composite dispersed aluminum melt is introduced into the casting and extrusion wheel groove of the Castex continuous casting and extrusion machine. Under the rotation of the casting and extrusion wheel, the aluminum melt is cooled, solidified, and extruded to obtain an aluminum-based graphene material profile. Step 5: The aluminum-based graphene material profile is subjected to online cooling, traction, and winding.

[0008] According to one embodiment of the present invention, the composition of the electroless copper plating solution is as follows: copper sulfate 8-20 g / L, potassium sodium tartrate 30-40 g / L, reducing agent 5-30 g / L, sodium hydroxide 5-15 g / L, 2,2'-bipyridine 5-30 mg / L, and polyethylene glycol PEG6000 50-100 mg / L; the plating temperature is 35-60℃, the plating time is 5-45 min, the plating pH value is 11.5-13.5, and the stirring speed is 100-500 r / min; the reducing agent is one or more of glyoxylic acid, sodium gluconate, or sodium hypophosphite. Specifically, a low concentration of copper sulfate (8-12 g / L) is suitable for preparing a thin coating of 20-50 nm with a dense coating; a high concentration (12-20 g / L) is suitable for preparing a thick coating of 50-150 nm with a fast deposition rate. If the concentration of stabilizer (2,2'-bipyridine) is too low, the plating solution is prone to decomposition; if the concentration is too high, it will reduce the plating rate and increase the resistivity of the coating. For every 5°C increase in plating temperature, the plating rate increases by approximately 30%; above 60°C, the stability of the plating solution decreases sharply. Increasing the plating pH value accelerates the plating rate but increases the coating roughness; below 11.5, the plating rate is almost zero. A plating time of 5–10 min corresponds to a copper coating thickness of 10–20 nm and a copper mass fraction of 5%–10%; a plating time of 10–30 min corresponds to a copper coating thickness of 20–100 nm and a copper mass fraction of 10%–30%; and a plating time of 30–45 min corresponds to a copper coating thickness of 100–150 nm and a copper mass fraction of 30%–40%. Low-speed stirring is suitable for thin coatings with good uniformity; high-speed stirring is suitable for thick coatings, avoiding uneven local deposition.

[0009] According to one embodiment of the present invention, in step 3, the power of the ultrasonic field is 1.5 to 3.0 kW and the frequency is 20 kHz; the intensity of the electromagnetic field is 0.05 to 0.2 T and the frequency is 50 Hz; and the composite dispersion treatment time is 15 to 30 min.

[0010] According to one embodiment of the present invention, the process parameters for Castex continuous casting extrusion in step 4 are as follows: the rotation speed of the extrusion roller is 3–20 r / min, and the rotation speed is negatively correlated with the cross-sectional size of the profile: when the profile is a wire with a diameter of 3–10 mm, the rotation speed is 10–20 r / min; when the profile is a bar with a diameter of 10–30 mm, the rotation speed is 5–10 r / min; when the profile cross-section is greater than 100 mm², the rotation speed is 3–5 r / min. The extrusion temperature is 650–750 °C. If the extrusion temperature is too low, filling is difficult and cracks are easily generated; if the extrusion temperature is too high, secondary agglomeration and interfacial reactions are easily generated. The nitrogen protection pressure is 0.2–0.8 MPa, which is positively correlated with the melt temperature. The higher the melt temperature, the greater the nitrogen protection pressure to prevent melt oxidation. The cooling rate is 5 × 10²–2 × 10⁻⁶ MPa. 4 K / s. The cooling rate for water cooling is 10³~10⁻¹⁰.4 K / s; the cooling rate during water mist cooling is 5×10³~2×10 4 K / s; the cooling rate during air cooling is 5×10²~10³K / s. The higher the cooling rate, the less secondary agglomeration and the finer the grains. The mold preheating temperature is 300~400℃. Too low a mold preheating temperature can easily cause cold shuts; too high a mold preheating temperature will reduce the cooling rate.

[0011] According to one embodiment of the present invention, graphene undergoes roughening, sensitization, and activation pretreatment before electroless copper plating modification. Roughening uses a mixture of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 2:1 to 4:1. Increasing the nitric acid ratio increases the number of oxygen-containing functional groups on the graphene surface, improving the adhesion of the coating; increasing the sulfuric acid ratio reduces damage to the graphene sheets. The roughening temperature is 30–80°C. Low-temperature, long-time roughening reduces sheet breakage and is suitable for large-size graphene; high-temperature, short-time roughening is suitable for few-layer graphene. Sensitization uses a sensitizing solution composed of 10–25 g / L stannous chloride dihydrate and hydrochloric acid. Too low a concentration results in insufficient sensitization and easy coating detachment; too high a concentration leads to tin residue and reduced conductivity. Activation uses an activation solution composed of 0.5–1.5 g / L palladium chloride and hydrochloric acid. Low-concentration activation reduces costs and is suitable for thin coatings; high-concentration activation improves coating uniformity and is suitable for thick coatings.

[0012] This invention also provides a method for preparing aluminum-based graphene material, employing an integrated process of spray deposition and continuous extrusion, comprising the following steps: Step a, chemically modifying graphene with copper plating to obtain copper-coated graphene powder; Step b, melting aluminum matrix material into aluminum melt, simultaneously feeding and atomizing the copper-coated graphene powder and aluminum melt using a spray deposition process, so that the graphene powder is uniformly dispersed in the atomized aluminum droplets, depositing to form a spray deposition billet, and pre-compacting it using a dual-disc flow pattern controller; Step c, continuously extruding the spray deposition billet to obtain an aluminum-based graphene material profile; Step d, cooling, straightening, and dimensionally measuring the aluminum-based graphene material profile.

[0013] According to one embodiment of the present invention, the atomization pressure of the jet deposition process in step b is 0.8–1.5 MPa. Higher atomization pressure results in smaller droplet sizes (average 20–60 μm) and more uniform graphene dispersion; however, excessively high atomization pressure leads to reduced deposition efficiency. The atomization temperature is 690–770 °C. Too low atomization temperature results in high droplet viscosity, easily clogging the nozzle; too high atomization temperature leads to severe droplet oxidation. The nozzle diameter is 2–5 mm. Small-diameter nozzles (2–3 mm) are suitable for fine droplets and high dispersibility; large-diameter nozzles (3–5 mm) are suitable for high-volume production. The feeding rate of copper-coated graphene powder is 3–20 g / min, strictly matched to the atomization rate. The carrier gas is argon, with a carrier gas swirl angle of 20°–45°. A 30° carrier gas swirl angle provides the best dispersion effect; too small an angle easily leads to localized enrichment; too large an angle easily blows away the graphene. The feed inlet should be positioned 80–150 mm from the nozzle, in the center of the atomizing cone, to ensure thorough mixing of graphene and molten droplets. The deposition distance should be 300–500 mm. If the deposition distance is too short, the deposition billet temperature will be too high, easily resulting in coarse crystals; if the deposition distance is too long, the density will be low.

[0014] According to one embodiment of the present invention, the continuous extrusion in step c uses a Castex continuous extruder with an extrusion ratio of 8–40. An extrusion ratio less than 8 results in insufficient density; an extrusion ratio greater than 40 leads to severe die wear and excessive fragmentation of the graphene sheets. The extrusion roller speed is 3–18 r / min, negatively correlated with product specifications and the extrusion ratio; a high extrusion ratio corresponds to a low speed. The extrusion temperature is 350–550℃, utilizing the residual heat from jet deposition, eliminating the need for additional heating and reducing energy consumption by more than 30%. The pre-pressure of the dual-disc flow controller is 0.1–0.3 MPa; too low a pre-pressure results in a loose deposited billet prone to porosity; too high a pre-pressure increases the extrusion pressure. The extrusion pressure is 1000–2000 kN, positively correlated with the extrusion ratio and the product cross-sectional area.

[0015] The present invention also provides an aluminum-based graphene material, comprising an aluminum matrix and copper-coated graphene uniformly dispersed in the aluminum matrix; the copper coating layer of the copper-coated graphene has a thickness of 10-150 nm and a copper mass fraction of 5%-40%; the aluminum-based graphene material has a conductivity ≥70% IACS, a tensile strength ≥160 MPa, and a density ≥99.5%.

[0016] According to one embodiment of the present invention, the aluminum matrix is ​​a 1-series, 6-series, or 8-series aluminum alloy; the amount of copper-coated graphene added is 0.2% to 1.0% of the mass of the aluminum matrix; and the content of Al4C3 brittle phase at the interface of the composite material is ≤0.2%.

[0017] The beneficial effects of this invention are: First, the copper coating reduces the contact angle between graphene and molten aluminum from over 140° to below 60°, significantly improving wettability. The copper layer acts as an intermediate barrier, effectively preventing direct contact between aluminum and carbon and inhibiting the formation of the brittle Al4C3 phase. The interfacial shear strength is more than 45% higher than that of uncoated graphene.

[0018] II. The Castex method employs a combined ultrasonic and electromagnetic field dispersion technique, which can break down over 95% of graphene agglomerates into single-layer or few-layer states, with no obvious agglomeration observed under a 1000x microscope. The jet deposition method achieves initial three-dimensional dispersion through simultaneous atomized feeding, combined with the intense shearing of continuous extrusion, ensuring that the graphene distribution deviation in the final product does not exceed [a certain value]. .

[0019] III. Castex scheme achieves 10³ to 10⁻⁶ 4 With an ultra-high cooling rate of K / s, the solidification time is shortened to the millisecond level, preventing graphene from segregating. The spray deposition method ensures that the total residence time of the material above 400°C does not exceed 10 minutes, far lower than the more than 10 hours of traditional processes, thus suppressing interfacial reactions at the source.

[0020] IV. The composite materials prepared using the Castex method achieve a conductivity exceeding 70% IACS, surpassing 62% of pure aluminum; tensile strength is 160-210 MPa, an increase of 80%–130% compared to pure aluminum; elongation is 12%–18%, maintaining good plasticity. Using the spray deposition method with 1.0% graphene addition, the tensile strength of the 1060 aluminum-based composite material is more than 45% higher than the matrix, while maintaining a conductivity exceeding 56.5% IACS; the 6061 aluminum-based composite material, after T6 treatment, achieves a tensile strength of 355 MPa and a conductivity exceeding 51.2% IACS. Simultaneously, the large deformation and dynamic recrystallization of continuous extrusion refine the matrix grains by more than 30%, with an average grain size of less than 5 μm.

[0021] V. The Castex solution achieves a production efficiency of 5-10 tons per day, more than 10 times that of traditional powder metallurgy, and reduces product costs by over 40%. The spray deposition solution eliminates multiple intermediate processes such as sawing, milling, and preheating, shortening the production cycle from over 24 hours to less than 2 hours, reducing overall energy consumption by over 30%, and increasing material utilization from 70% to over 95%. Product length is unlimited, and performance fluctuations do not exceed [a certain threshold]. This meets the requirements of large-scale industrial production.

[0022] Furthermore, this invention has a wide range of applications and can be used to prepare various aluminum matrices such as 1-series, 6-series, and 8-series aluminum matrices. The product forms include rods, wires, profiles, and plates, and can be widely used in new energy vehicles, 5G communications, rail transportation, aerospace and other fields. Attached Figure Description

[0023] Figure 1 This is a process flow diagram of the preparation of aluminum-based graphene materials using the Castex continuous casting and extrusion process of this invention; Figure 2 This is a process flow diagram of the preparation of aluminum-based graphene materials using the integrated process of jet deposition and continuous extrusion in this invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1 This embodiment is a high-conductivity pure aluminum-based graphene material. The aluminum-based graphene material is prepared by Castex continuous casting and extrusion process, with industrial pure aluminum as the matrix and a graphene addition amount of 0.2 wt%. The specific steps are as follows.

[0026] Graphene chemical copper plating modification: Few-layer reduced graphene oxide (FREE) with 3 to 8 layers and a sheet diameter of 5-10 μm was selected. The graphene was placed in a mixture of concentrated sulfuric acid and concentrated nitric acid (volume ratio 3:1) and ultrasonically treated for 45 min at 60℃ (250 W). After treatment, the graphene was washed with deionized water until the pH of the filtrate reached 7, and then dried in a vacuum drying oven at 60℃ for 12 h. The roughened graphene was then placed in a sensitization solution and stirred at room temperature for 15 min. The sensitization solution consisted of 15 g / L stannous chloride dihydrate and 40 mL / L 37% hydrochloric acid. After sensitization, the graphene was washed three times with deionized water and then placed in an activation solution and stirred at room temperature for 8 min. The activation solution consisted of 0.8 g / L palladium chloride and 15 mL / L 37% hydrochloric acid. After activation, the graphene was washed until neutral. Activated graphene was added to a chemical copper plating solution containing 12 g / L copper sulfate pentahydrate, 35 g / L sodium potassium tartrate, 5 g / L glyoxylic acid, 10 g / L sodium hydroxide, 15 mg / L 2,2'-bipyridine, and 80 mg / L polyethylene glycol PEG6000. Plating was carried out at 45°C and pH 12.5 for 15 min. After plating, the solution was filtered, washed, and dried to obtain copper-coated graphene powder with a copper coating thickness of 30 nm and a copper mass fraction of 15%. The copper-coated graphene powder was then subjected to airflow pulverization and classification under argon protection, and passed through a 200-mesh sieve for later use.

[0027] Batching and Smelting: Weigh out 99.8% industrial pure aluminum ingots and 0.2% copper-coated graphene powder. Smelt the aluminum ingots at 730℃ until completely melted, hold at that temperature for 10 minutes, and then refine and degas using rotary argon gas to remove surface slag. This reduces the hydrogen content to ≤0.08mL / 100gAl, decreases porosity defects, and increases the yield by more than 5%. Argon gas is used for protection throughout the entire smelting process.

[0028] Composite dispersion: Copper-coated graphene powder was added to molten aluminum using an argon-protected ultrasonic jetting device. The jetting pressure was 0.3 MPa, and the jetting time was 8 min. After the addition was completed, ultrasonic and electromagnetic field treatments were simultaneously activated for 15 min of composite dispersion. The ultrasonic power was 1.5 kW, and the frequency was 20 kHz; the electromagnetic field strength was 0.08 T, and the frequency was 50 Hz; the melt temperature was 720℃.

[0029] Castex Continuous Casting Extrusion: The composite-dispersed aluminum molten material is introduced into the preheating funnel of the Castex continuous casting extruder through an insulated conveyor pipe, with the melt temperature controlled at 690℃. The melt enters the extrusion roller groove, the roller speed is 12 r / min, the extrusion temperature is 690℃, the nitrogen protection pressure is 0.35 MPa, the cooling rate is 3 × 10³ K / s, and the die preheating temperature is 350℃. The extruded profile is then subjected to online water cooling, traction, and winding to obtain aluminum-based graphene material wire.

[0030] Performance testing: conductivity 70.5% IACS, tensile strength 168MPa, elongation 18%.

[0031] Example 2 This embodiment uses a balanced 6101 aluminum-based graphene material, differing from Embodiment 1 in that it uses 6101 aluminum alloy as the matrix and adds 0.3 wt% graphene. The electroless copper plating time is extended to 20 min, the copper coating thickness is 50 nm, and the copper mass fraction is 20%. The reducing agent used is sodium gluconate at 5 g / L.

[0032] Ingredients: Weigh out 99.7% of 6101 aluminum alloy ingots and 0.3% of copper-coated graphene powder. The chemical composition of the 6101 aluminum alloy is strictly controlled as follows: silicon 0.45% to 0.55%, magnesium 0.50% to 0.60%, iron no more than 0.2%, and copper no more than 0.1%. Melting temperature: 740℃, holding temperature for 15 minutes, refining and degassing, then standing for 20 minutes.

[0033] Composite dispersion: ultrasonic power 2.0kW, electromagnetic field strength 0.1T, dispersion time 20min.

[0034] Castex continuous casting extrusion: casting roller speed 10 r / min, extrusion temperature 700℃, nitrogen pressure 0.4 MPa, cooling rate 5×10³ K / s, mold preheating temperature 350℃.

[0035] Performance testing: conductivity 70.3% IACS, tensile strength 185MPa, elongation 16%.

[0036] Example 3 This embodiment uses a high-strength 6101 aluminum-based graphene material, differing from Example 1 in that it uses 6101 aluminum alloy as the matrix and adds 0.5 wt% graphene. The electroless copper plating time is 25 min, the copper coating thickness is 70 nm, and the copper mass fraction is 25%. Sodium hypophosphite at 5 g / L is used as the reducing agent.

[0037] Ingredients: Weigh 99.5% of 6101 aluminum alloy ingots and 0.5% of copper-coated graphene powder. Melt at 750℃ and hold for 20 minutes.

[0038] Composite dispersion: ultrasonic power 2.5kW, electromagnetic field strength 0.15T, dispersion time 25min.

[0039] Castex continuous casting extrusion: casting roller speed 8 r / min, extrusion temperature 710℃, nitrogen pressure 0.5MPa, cooling rate 7×10³K / s, mold preheating temperature 350℃.

[0040] Performance testing: conductivity 70.1% IACS, tensile strength 202 MPa, elongation 14%.

[0041] Example 4 This embodiment uses a high-addition-content 6101 aluminum-based graphene material, differing from Example 1 in that it uses 6101 aluminum alloy as the matrix and the graphene addition is 1.0 wt%. The electroless copper plating time is 30 min, the copper coating thickness is 100 nm, and the copper mass fraction is 30%. The reducing agent used is glyoxylic acid at 10 g / L.

[0042] Ingredients: Weigh 99.0% of 6101 aluminum alloy ingots and 1.0% of copper-coated graphene powder. Melt at 760℃ and hold for 20 minutes.

[0043] Composite dispersion: ultrasonic power 3.0kW, electromagnetic field strength 0.2T, dispersion time 30min.

[0044] Castex continuous casting extrusion: extrusion roller speed 5 r / min, extrusion temperature 720℃, nitrogen pressure 0.6 MPa, cooling rate 1×10 4 K / s, mold preheating temperature is 350℃.

[0045] Performance testing: conductivity 70.0% IACS, tensile strength 215MPa, elongation 12%.

[0046] Example 5 This embodiment is a heat-treated and strengthened 6101 aluminum-based graphene material. The difference between this embodiment and Example 2 is that the sample obtained in Example 2 was subjected to T6 heat treatment, solution treatment at 530°C for 1 hour, water quenching, and then aging treatment at 175°C for 8 hours.

[0047] The performance test results are as follows: conductivity 70.4% IACS, tensile strength 220MPa, and elongation 13%.

[0048] Table 1: Comparison of main process parameters and composite material properties of different embodiments of Castex continuous casting extrusion process

[0049] Example 6 This embodiment describes the preparation of 6063 aluminum-based graphene material using an integrated spray deposition and continuous extrusion process. The integrated spray deposition and continuous extrusion equipment mainly includes a melting and spraying device, a dual-disc flow pattern controller, a Conform extrusion roller, a shoe holder, and a die. Its working principle is as follows: molten aluminum is atomized and mixed with synchronously fed copper-coated graphene powder, then directly sprayed into the groove of the rotating extrusion roller. After pre-compaction by the dual-disc flow pattern controller, it enters the die cavity with the extrusion roller, where it undergoes densification under the combined action of residual heat and frictional deformation heat. In this embodiment, 6063 aluminum alloy is used as the matrix, and the graphene content is 0.8 wt%.

[0050] Graphene modified by electroless copper plating: The same electroless copper plating method as in Example 1 was used, but the plating time was adjusted to achieve a copper coating thickness of 30 nm and a copper mass fraction of 15%. After being pulverized and classified under an argon protective gas flow, it was passed through a 200-mesh sieve for later use.

[0051] Smelting and Refining: 6063 aluminum ingots were smelted at 740℃ until completely melted. Argon gas was then injected and refined for 15 minutes, with an argon purity of not less than 99.999%. The injection pressure was 0.25 MPa, ensuring the hydrogen content was not greater than 0.12 mL / 100g Al. The mixture was allowed to stand for 20 minutes to allow inclusions to float to the surface. Argon gas was continuously introduced into the furnace for protection during both smelting and refining processes.

[0052] Atomization and Synchronous Feeding: Adjust the atomization temperature to 725℃, atomization pressure to 1.05MPa, and nozzle diameter to 3mm. Feed copper-coated graphene powder into the center of the atomizing cone at a rate of 8.5g / min using a twin-screw loss-in-weight feeder, with the feed inlet 120mm from the nozzle. Argon carrier gas enters the atomizing cone at a 30° swirl angle and a flow rate of 11L / min, causing the graphene powder to form a uniform suspended cloud. After flowing out through the guide tube, the molten aluminum is broken into aluminum droplets with an average size of 40-50μm by the atomizing gas. Each droplet encapsulates 1-5 pieces of graphene, with a deposition distance of 400mm.

[0053] Pre-compaction and continuous extrusion: The atomized mixture is directly sprayed into the groove of the extrusion wheel. A dual-disc flow pattern controller applies a pre-pressure of 0.2 MPa, compacting the loose deposit into a continuous strip. The extrusion wheel speed is 8 r / min, the extrusion ratio is 20, and the extrusion force is 1200 kN. The extrusion temperature is 450℃. After extrusion, the profile undergoes online water cooling, traction, straightening, and length setting.

[0054] Performance testing: Density 99.5%, conductivity 70.2% IACS, tensile strength 200MPa, yield strength 190MPa, elongation 15%, graphene dispersion deviation not exceeding [percentage missing]. The Al4C3 phase content at the interface is no more than 0.2%. The production cycle is shortened to less than 2 hours, the material utilization rate is 95%, and the yield is 96%.

[0055] Example 7 This embodiment uses 1060 aluminum-based graphene material, with 1060 aluminum as the matrix and 1.0 wt% graphene added.

[0056] The graphene electroless copper plating modification was the same as in Example 1, with a copper content of 15 wt%. 1060 aluminum ingots were melted at 730℃ and refined with rotary argon for 15 min, resulting in a hydrogen content of 0.10 mL / 100 g Al. After standing for 20 min, the atomization temperature was adjusted to 720℃, the atomization pressure to 1.0 MPa, the nozzle diameter to 4 mm, and the deposition distance to 300 mm. Copper-coated graphene powder was simultaneously fed at a rate of 10 g / min. The extrusion roller speed was 10 r / min, the extrusion ratio to 20, the extrusion pressure to 1500 kN, and the pre-pressure of the dual-disc flow controller to 0.2 MPa. The product outlet temperature was 380℃, and the product was air-cooled after extrusion. The extruded product was then subjected to a full annealing treatment at 340℃ for 1.5 h.

[0057] Performance testing: Density 99.6%, tensile strength 162 MPa, yield strength 125 MPa, elongation 18%, electrical conductivity 70.1% IACS, thermal conductivity 220 W / (m·K). No continuous Al4C3 phase was formed at the interface, and the graphene was uniformly dispersed.

[0058] Example 8 This embodiment is a 6061 aluminum-based graphene material in the T6 state, with 6061 aluminum alloy as the matrix and a graphene addition amount of 1.0 wt%.

[0059] The graphene-coated copper modification was performed as in Example 1. 6061 aluminum ingots were melted at 750℃ and refined with rotary argon for 15 min, resulting in a hydrogen content of 0.11 mL / 100g Al. After standing for 20 min, the atomization temperature was adjusted to 740℃, the atomization pressure to 1.1 MPa, the nozzle diameter to 2 mm, and the deposition distance to 400 mm. Copper-coated graphene powder was simultaneously fed in at a rate of 10 g / min. The extrusion roller speed was 9 r / min, the extrusion ratio to 18, the extrusion pressure to 1600 kN, and the pre-pressure of the dual-disc flow controller to 0.25 MPa. The product outlet temperature was 420℃. Immediately after extrusion, online water mist quenching was performed at a cooling rate of 30℃ / s and a quenching transfer time of 8 s. Subsequently, artificial aging treatment was carried out at 175℃ for 8 h.

[0060] Performance testing: Density 99.5%, tensile strength 355MPa, yield strength 305MPa, elongation 12%, electrical conductivity 70.0%IACS, thermal conductivity 215W / (m·K).

[0061] Example 9 This embodiment uses 8011 aluminum-based graphene material, with 8011 aluminum alloy as the matrix and graphene addition of 0.8 wt%.

[0062] The graphene-coated copper modification was performed as in Example 1. 8011 aluminum ingots were melted at 730℃ and refined with rotary argon for 15 min, resulting in a hydrogen content of 0.09 mL / 100g Al. After standing for 20 min, the atomization temperature was adjusted to 720℃, the atomization pressure to 0.9 MPa, the nozzle diameter to 5 mm, and the deposition distance to 500 mm. Copper-coated graphene powder was simultaneously fed in at a rate of 8 g / min. The extrusion roller speed was 12 r / min, the extrusion ratio to 22, the extrusion pressure to 1400 kN, and the pre-pressure of the dual-disc flow controller to 0.15 MPa. The product outlet temperature was 385℃, and the product was air-cooled after extrusion. The extruded product was then subjected to a full annealing treatment at 350℃ for 1 h.

[0063] Performance testing: density 99.6%, tensile strength 165MPa, yield strength 110MPa, elongation 20%, electrical conductivity 70.0%IACS, thermal conductivity 205W / (m·K).

[0064] Table 2: Comparison of key process parameters and composite material properties of different embodiments of the integrated jet deposition and continuous extrusion process

[0065] Example 10 This example illustrates the effect of different graphene addition amounts on the properties of 1060 aluminum-based composite materials. The same process parameters as in Example 7 were maintained, but the amount of copper-coated graphene added was varied to 0.5 wt%, 1.0 wt%, 1.5 wt%, and 2.0 wt%. The performance test results are as follows: with an addition amount of 0.5 wt%, the tensile strength was 160 MPa, the conductivity was 70.5% IACS, and the elongation was 21%; with an addition amount of 1.0 wt%, the tensile strength was 175 MPa, the conductivity was 70.3% IACS, and the elongation was 18%; with an addition amount of 1.5 wt%, the tensile strength was 180 MPa, the conductivity was 70.1% IACS, and the elongation was 15%; with an addition amount of 2.0 wt%, the tensile strength was 210 MPa, the conductivity was 70.0% IACS, and the elongation was 12%.

[0066] Using the same process as in Example 7 but without adding graphene, a pure 1060 aluminum control sample was prepared. The tensile strength was measured to be 112 MPa, the conductivity to be 62.0% IACS, and the elongation to be 25%.

[0067] It is evident that the overall performance is optimal when the graphene content is 1.0 wt%.

[0068] Table 3: Comparison of the effects of graphene addition on the mechanical properties and electrical conductivity of aluminum matrix composites

[0069] Example 11 This example illustrates the effect of different copper plating contents on the properties of 6061 aluminum-based composite materials. Maintaining the same process parameters as in Example 8, the electroless copper plating time was varied to obtain copper-coated graphene with copper contents of 10wt%, 15wt%, and 20wt%, respectively. Performance test results: with a copper content of 10wt%, the tensile strength was 325MPa, conductivity was 70.2% IACS, and elongation was 10%; with a copper content of 15wt%, the tensile strength was 355MPa, conductivity was 70.5% IACS, and elongation was 12%; with a copper content of 20wt%, the tensile strength was 340MPa, conductivity was 70.0% IACS, and elongation was 11%.

[0070] The composite material prepared using unmodified virgin graphene (without copper plating) and with all other process parameters exactly the same as in Example 8 has a tensile strength of only 280 MPa, a conductivity of 70.0% IACS, and an elongation of 6%.

[0071] It is evident that the performance is optimal when the copper content is 15wt%.

[0072] Table 4: Comparison of the effects of copper plating content on the mechanical properties and electrical conductivity of aluminum matrix composites

[0073] Comparative Example 1 This comparative example uses uncoated graphene combined with a traditional stirred casting process. Following the same raw material ratio as in Example 2, uncoated copper-impregnated raw graphene was used, and the composite material was prepared by conventional mechanical stirring dispersion and sand casting. The resulting composite material exhibited a conductivity of 58.3% IACS, a tensile strength of 125 MPa, a yield strength of 80 MPa, an elongation of 8%, and a density of 96%. Microscopic analysis revealed the presence of numerous graphene aggregates, with significant Al4C3 brittle phase formation at the interfaces.

[0074] Comparative Example 2 This comparative example uses copper-coated graphene combined with a traditional stirred casting process. Following the same copper-coated graphene powder and raw material ratios as in Example 2, the composite material was prepared via conventional mechanical stirring dispersion and sand casting. The resulting composite material exhibited a conductivity of 62.7% IACS, a tensile strength of 142 MPa, a yield strength of 95 MPa, an elongation of 11%, and a density of 97%. Microscopic analysis revealed uneven graphene dispersion and severe secondary agglomeration during solidification.

[0075] Comparative Example 3 This comparative example uses copper-coated graphene, employing only ultrasonic dispersion combined with a Castex continuous casting extrusion process. The process is the same as in Example 2, but only ultrasonic dispersion is used, without activating the electromagnetic field. The resulting composite material exhibits a conductivity of 65.4% IACS, a tensile strength of 163 MPa, a yield strength of 110 MPa, an elongation of 13%, and a density of 98.5%. Microscopic analysis revealed the presence of a small number of fine graphene aggregates.

[0076] Comparative Example 4 This comparative example uses unmodified graphene-reinforced 1060 aluminum-based composite material, combined with an integrated spray deposition and continuous extrusion process. The same integrated spray deposition and continuous extrusion process as in Example 7 was used, but unmodified raw graphene without chemical copper plating was employed. Performance test results were: density 97.2%, tensile strength 125 MPa, yield strength 95 MPa, elongation 8%, and conductivity 52% IACS. Compared to Example 7, the performance is significantly lower due to poor wettability of the unmodified graphene with the aluminum matrix, uneven dispersion, and low interfacial bonding strength.

[0077] Comparative Example 5 This comparative example uses a conventional jet deposition followed by a secondary extrusion process to prepare Cu@rGO / 1060 composite materials. Following the conventional jet deposition process, a preform was first prepared, then sawn, preheated at 400°C for 2 hours, and then extruded. Other parameters were the same as in Example 7. Performance test results were: density 99.3%, tensile strength 145 MPa, yield strength 110 MPa, elongation 15%, and electrical conductivity 54% IACS. Compared to Example 7, the performance decreased because the intermediate preheating process led to secondary graphene agglomeration and intensified interfacial reactions.

[0078] Table 5: Comparison of composite material properties and defects under different comparative processes

[0079] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing an aluminum-based graphene material, employing a Castex continuous casting and extrusion process, characterized in that, Includes the following steps: Step 1: Modify graphene by chemical copper plating to form a copper coating layer on the graphene surface, thereby obtaining copper-coated graphene powder. Step 2: Melt the aluminum matrix material into an aluminum melt, and add the copper-coated graphene powder into the aluminum melt under an inert gas protective atmosphere; Step 3: The aluminum melt is subjected to a composite dispersion treatment using an ultrasonic field and an electromagnetic field to uniformly disperse the copper-coated graphene powder in the aluminum melt; the power of the ultrasonic field is 1.5-3.0 kW and the frequency is 20 kHz; the intensity of the electromagnetic field is 0.05-0.2 T and the frequency is 50 Hz; the composite dispersion treatment time is 15-30 min. Step 4: The composite dispersed aluminum melt is introduced into the extrusion roller groove of the Castex continuous casting extruder. Under the rotation of the extrusion roller, the aluminum melt is cooled, solidified, and extruded to obtain an aluminum-based graphene material profile. The process parameters of the Castex continuous casting extrusion are: extrusion roller speed of 3-20 r / min, extrusion temperature of 650-750℃, nitrogen protection pressure of 0.2-0.8 MPa, and cooling rate of 5×10⁻⁶. 2 ~2×10 4 K / s, mold preheating temperature is 300~400℃; Step 5: Online cooling, traction, and winding of the aluminum-based graphene material profile.

2. The preparation method according to claim 1, characterized in that, The electroless copper plating solution comprises: 8-20 g / L copper sulfate, 30-40 g / L sodium potassium tartrate, 5-30 g / L reducing agent, 5-15 g / L sodium hydroxide, 5-30 mg / L 2,2'-bipyridine, and 50-100 mg / L polyethylene glycol PEG6000; the plating temperature is 35-60℃, the plating time is 5-45 min, the plating pH value is 11.5-13.5, and the stirring speed is 100-500 r / min; the reducing agent is one or more of glyoxylic acid, sodium gluconate, or sodium hypophosphite.

3. The preparation method according to claim 1, characterized in that, Before the chemical copper plating modification, the graphene undergoes roughening, sensitization, and activation pretreatment. The roughening is performed using a mixture of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 2:1 to 4:1, at a temperature of 30 to 80°C. The sensitization is performed using a sensitizing solution composed of 10 to 25 g / L stannous chloride dihydrate and hydrochloric acid. The activation is performed using an activation solution composed of 0.5 to 1.5 g / L palladium chloride and hydrochloric acid.

4. A method for preparing aluminum-based graphene material, employing an integrated process of spray deposition and continuous extrusion, characterized in that, Includes the following steps: Step a: Modify graphene by chemical copper plating to obtain copper-coated graphene powder. Step b: The aluminum matrix material is melted into aluminum melt. The copper-coated graphene powder is simultaneously fed and atomized with the aluminum melt using a spray deposition process, so that the graphene powder is uniformly dispersed in the atomized aluminum droplets, deposited to form a spray deposition preform, and pre-compacted by a dual-disc flow pattern controller. The atomization pressure of the spray deposition process is 0.8-1.5 MPa, the atomization temperature is 690-770℃, the nozzle diameter is 2-5 mm, the feeding rate of the copper-coated graphene powder is 3-20 g / min, the carrier gas is argon, the carrier gas swirl angle is 20°-45°, the distance from the feeding port to the nozzle is 80-150 mm, and the deposition distance is 300-500 mm. Step c: The spray-deposited billet is continuously extruded to obtain an aluminum-based graphene material profile; the continuous extrusion adopts a Castex continuous extruder, the extrusion ratio is 8 to 40, the extrusion roller speed is 3 to 18 r / min, the extrusion temperature is 350 to 550℃, the pre-pressure of the dual-disc flow controller is 0.1 to 0.3 MPa, and the extrusion force is 1000 to 2000 kN; Step d involves cooling, straightening, and measuring the aluminum-based graphene material profile.

5. An aluminum-based graphene material prepared by the preparation method according to claim 1 or claim 4, characterized in that, The material comprises an aluminum matrix and copper-coated graphene uniformly dispersed in the aluminum matrix; the copper coating thickness of the copper-coated graphene is 10-150 nm, and the copper mass fraction is 5%-40%; the aluminum-based graphene material has a conductivity ≥70% IACS, a tensile strength ≥160 MPa, and a density ≥99.5%.

6. The aluminum-based graphene material according to claim 5, characterized in that, The aluminum matrix is ​​a 1-series, 6-series, or 8-series aluminum alloy; the amount of copper-coated graphene added is 0.2% to 1.0% of the mass of the aluminum matrix; the content of Al4C3 brittle phase at the interface of the material is ≤0.2%.

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