A method for preparing a copper-graphene composite conductor and a copper-graphene composite conductor

Abstract

The application discloses a preparation method of a copper-graphene composite conductor, and comprises the following steps: S1, a graphene layer is formed on the surface of a copper strip by adopting a chemical vapor deposition method to obtain a graphene / copper composite strip; S2, a plurality of graphene / copper composite strips are stacked in a consistent direction of the graphene layer, and a copper strip without the graphene layer is placed on the outermost layer to form a laminated blank; S3, the laminated blank is subjected to multi-pass deformation treatment, the materials in each layer are metallurgically combined through cumulative deformation, and the laminated blank is formed into a rod-shaped blank through multi-directional forging of the laminated blank; S4, the rod-shaped blank is subjected to multi-stage reducing processing to gradually reduce the cross-sectional area, and a composite single wire with a relatively small diameter is obtained; and S5, a plurality of the composite single wires are twisted to obtain the copper-graphene composite conductor. Through the above scheme, the graphene is mechanically engaged with the copper matrix and is combined with the interface, the interface combined strength is strengthened through forging and extrusion, and the problem that the graphene is easy to fall off in the single vapor deposition method is solved.

Description

Technical Field

[0001] This invention relates to the field of cable manufacturing technology, and more specifically, to a method for preparing a copper-graphene composite conductor and the copper-graphene composite conductor itself. Background Technology

[0002] Copper, due to its excellent electrical conductivity, has long been the preferred conductive material and is widely used in wires and cables, electronic components, and other fields. However, traditional pure copper conductors have inherent drawbacks: to meet specific resistance standards, a large cross-sectional area design is required, resulting in thick conductor diameters and heavy weights, increasing material costs and laying difficulties; at the same time, pure copper has limited mechanical strength and is easily damaged under conditions such as vibration and bending, limiting its application in fields such as aerospace and new energy vehicles where lightweighting and high reliability are required.

[0003] Graphene, as a novel two-dimensional carbon nanomaterial, possesses ultra-high conductivity (approximately 10⁻⁶). 6 With its excellent electrical conductivity (S / m) and mechanical properties (tensile strength of approximately 130 GPa), graphene is an ideal reinforcing phase for copper-based materials. Combining graphene with copper is expected to significantly improve the mechanical and thermal properties of the material while maintaining good electrical conductivity, enabling lightweight designs.

[0004] Currently, the preparation of graphene / copper composite conductors mostly employs a single vapor deposition method, where graphene is directly deposited onto the surface of copper wire. However, this method has a core problem: the graphene and copper substrate are only physically adsorbed together, resulting in weak interfacial bonding. During subsequent processing (such as wire drawing and stranding) or use, the graphene layer easily detaches from the copper substrate surface, leading to performance degradation and failing to fully utilize graphene's ability to simultaneously improve strength and conductivity. Furthermore, graphene / copper composites prepared by powder metallurgy suffer from uneven graphene distribution within the copper substrate, affecting conductivity in the direction of current flow.

[0005] Therefore, developing a preparation process that can achieve a tight bond between graphene and a copper substrate and a uniformly oriented distribution of graphene has become the key to breaking through the current technological bottleneck. Summary of the Invention

[0006] One object of the present invention is to provide a new technical solution for the preparation method of copper-graphene composite conductor.

[0007] According to a first aspect of the present invention, a method for preparing a copper-graphene composite conductor is provided, comprising the following steps:

[0008] S1, a graphene layer is deposited on the surface of a copper strip using chemical vapor deposition to obtain a graphene / copper composite strip; S2, multiple graphene / copper composite strips are stacked in the same direction with the graphene layers facing the same direction, and a copper strip without graphene deposition is placed on the outermost layer to form a composite blank; S3, the composite billet is subjected to multiple deformation processes, and the material of each layer is metallurgically bonded through cumulative deformation. The composite billet is then formed into a rod-shaped billet through multi-directional forging. S4, the rod-shaped blank is subjected to multi-stage diameter reduction processing to gradually reduce the cross-sectional area and obtain a composite monofilament with a smaller diameter; S5, multiple composite monofilaments are twisted together to obtain the copper-graphene composite conductor.

[0009] Optionally, before step S1, step S0 is further included, in which the copper strip is subjected to surface cleaning treatment to remove oil, oxide layer and impurities, so as to obtain the copper strip.

[0010] Optionally, in S0, industrial copper strips with a purity of ≥99.95% are selected and subjected to surface purification treatment by degreasing, rust removal, deionized water rinsing and vacuum drying.

[0011] Optionally, in step S1, the number of graphene layers is ≤10, the deposition temperature is 900-1000℃, the methane flow rate is 50-100 sccm, the argon flow rate is 200-300 sccm, the deposition time is 30-60 min, and the deposition is cooled to room temperature under argon protection.

[0012] Optionally, in step S2, 10-50 pieces of graphene / copper composite strip are taken and stacked sequentially with the graphene layers facing upwards, so that each graphene layer is in close contact with the copper base surface of the upper copper strip; the top layer is covered with a copper strip without graphene deposition, and after forming a composite blank, it is fixed with a high-temperature resistant clamp.

[0013] Optionally, S3 includes: S31, the composite billet is rolled in multiple passes to metallurgically bond the graphene / copper composite strips of each layer to form a continuous graphene / copper composite master strip. S32, the graphene / copper composite master tape is rolled into a cylindrical blank and then forged on multiple sides to form a rod-shaped blank.

[0014] Optionally, in S31, a two-roll hot rolling mill is used for 6-10 passes, with a reduction of 2-15% per pass and a rolling speed of 0.2-5 m / s. Rolling oil is used for lubrication and cooling to obtain a continuous graphene / copper composite master strip with uniform thickness and no gaps between layers.

[0015] Optionally, in S32, the composite master tape is tightly rolled along its length to form a cylindrical blank, which is then forged in multiple directions using free forging at 600-700℃, with a hammering frequency of 10-30 times / min, a hammering force of 10-80kN, and a deformation of 2-10% per forging. Each side is forged sequentially until a composite round bar with a diameter of 10-20mm is formed. Inert gas protection is used during the forging process.

[0016] Optionally, between S31 and S32, S311 is also included, in which the rolled graphene / copper composite master strip is placed in a degreasing agent for ultrasonic cleaning, then rinsed with deionized water, dried, and then subjected to stress-relief annealing in an environment that can prevent the copper-based oxidation of the copper strip.

[0017] Optionally, S4 includes: S41: The rod-shaped billet is fed into a continuous extruder and extruded through a die to obtain a continuous composite wire. S42: The continuous composite wire is drawn in multiple passes to obtain a composite monofilament with a smaller diameter.

[0018] Optionally, in S41, the continuous extrusion process parameters are: temperature 400-650℃, extrusion roller speed 2-20r / min, die orifice diameter 5-10mm, extrusion speed 2-10m / s, and nitrogen protection is used; extrusion further enhances the bonding force between the graphene forming the graphene layer and the copper-based interface of the copper strip, and makes it evenly distributed along the line length direction.

[0019] Optionally, in S42, a 2-5 drawing process is adopted. After each drawing, annealing is performed in an environment that can prevent the copper base of the copper strip from oxidizing. The annealing temperature is 180-250℃ and the holding time is 10-30min, finally obtaining a composite monofilament with a diameter of 0.10-0.50mm.

[0020] Optionally, in S5, a regular stranding method is used for stranding, with a stranding pitch of 16-30 mm, to obtain a copper-graphene composite conductor.

[0021] According to a second aspect of the present invention, a copper-graphene composite conductor is provided, wherein the copper-graphene composite conductor is prepared by any of the preparation methods described above.

[0022] According to the preparation method of the copper-graphene composite conductor disclosed herein, and the copper-graphene composite conductor, the following beneficial effects are achieved: Through cumulative rolling, graphene and copper substrate form mechanical interlocking and interfacial bonding, solving the problem of graphene easy detachment in simple vapor deposition; subsequent multi-faceted forging and continuous extrusion further strengthen the interfacial bonding strength.

[0023] The synergistic effect of cumulative rolling, multi-face forging, and continuous extrusion enables graphene to be evenly distributed in the copper matrix along the processing direction, forming oriented conductive channels and fully leveraging the role of graphene in simultaneously improving strength and conductivity.

[0024] The prepared composite conductor (0.22mm² specification) has a resistance of 73.1Ω, which is about 12% higher than that of ordinary pure copper conductor (82.5Ω).

[0025] The tensile strength of the composite monofilament is close to 260MPa, which is about 11% higher than that of ordinary pure copper monofilament (232MPa), while the elongation remains basically unchanged (≥15%). The addition of graphene simultaneously improves the strength and conductivity of the composite monofilament, making it suitable for more complex working conditions.

[0026] The high thermal conductivity and directional distribution of graphene improve the heat dissipation efficiency of the composite conductor. Under the same specifications and current load, the conductor temperature is about 6°C lower than that of pure copper wire, extending service life and improving electrical safety.

[0027] From copper strip pretreatment to final stranding and forming, a complete process chain is formed, with each step closely connected to ensure the stable performance of the final product, making it suitable for industrial production.

[0028] Under the same conductivity requirements, the conductor cross-sectional area can be reduced to achieve lightweight design, meeting the urgent need for weight reduction in fields such as aerospace and new energy vehicles.

[0029] Other features and advantages of the invention will become clear from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0030] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.

[0031] Figure 1 A flowchart illustrating a method for preparing a copper-graphene composite conductor, provided as a preferred embodiment of the present invention; Figure 2 for Figure 1 Flowchart of step S3; Figure 3 for Figure 1 The flowchart for step S4.

[0032] The diagram is marked as follows: Detailed Implementation Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0033] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0034] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0035] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0036] According to a method for preparing a copper-graphene composite conductor disclosed herein, such as... Figures 1 to 3 As shown, it includes the following steps: S1, a graphene layer is deposited on the surface of a copper strip using chemical vapor deposition to obtain a graphene / copper composite strip; S2, multiple graphene / copper composite strips are stacked in the same direction with the graphene layers facing the same direction, and a copper strip without graphene deposition is placed on the outermost layer to form a composite blank; S3, the composite billet is subjected to multiple deformation processes, and the material of each layer is metallurgically bonded through cumulative deformation. The composite billet is then formed into a rod-shaped billet through multi-directional forging. S4, the rod-shaped blank is subjected to multi-stage diameter reduction processing to gradually reduce the cross-sectional area and obtain a composite monofilament with a smaller diameter; S5, multiple composite monofilaments are twisted together to obtain the copper-graphene composite conductor.

[0037] A graphene layer is deposited on the surface of copper strip using a deposition method. Multiple deformation processes on the laminated billet allow the graphene to mechanically interlock with the copper substrate and form an interfacial bond. Subsequent multi-faceted forging and continuous extrusion further strengthen the interfacial bond, solving the problem of graphene detachment in single vapor deposition methods. The synergistic effect of multi-pass deformation (multi-pass rolling), multi-faceted forging, and continuous extrusion ensures that the graphene is evenly distributed along the processing direction within the copper substrate, forming oriented conductive channels and fully utilizing the ability of graphene to simultaneously improve strength and conductivity. The resulting copper-graphene composite conductor exhibits comprehensively improved performance, with conductivity increased by approximately 12%, tensile strength increased by approximately 11%, heat dissipation improved (temperature drop of approximately 6°C), and elongation maintained above 15%. This demonstrates that graphene simultaneously enhances the strength and conductivity of the composite conductor. The closely integrated steps in the preparation method form a complete process chain, ensuring stable performance of the final product.

[0038] According to an embodiment of a method for preparing a copper-graphene composite conductor disclosed herein, before step S1, a step S0 is further included, in which the copper strip is subjected to surface purification treatment to remove oil, oxide layer and impurities, thereby obtaining the copper strip.

[0039] Removing oil, oxide layers, and impurities from the copper strip surface provides a clean substrate surface for graphene growth, ensuring a uniform and continuous graphene layer and improving the quality of graphene deposition. A clean surface facilitates the tight bonding between graphene and the copper substrate, increasing the interfacial bonding strength. It also prevents impurities from introducing defects during the deposition process, ensuring the structural integrity of the graphene layer.

[0040] Specifically, in S0, industrial copper strips with a purity of ≥99.95% are selected and subjected to surface purification treatment in sequence through degreasing, rust removal, deionized water rinsing and vacuum drying.

[0041] A purity greater than 99.95% ensures excellent conductivity of the copper substrate and avoids the adverse effects of impurities on graphene growth and interfacial bonding; degreasing removes oil stains, rust removal removes oxide layers, deionized water rinsing removes residues, and vacuum drying ensures surface dryness, creating optimal conditions for chemical vapor deposition (CVD); standardized purification processes facilitate quality control and ensure batch consistency.

[0042] According to an embodiment of a method for preparing a copper-graphene composite conductor disclosed herein, in step S1, the number of graphene layers is ≤10, the deposition temperature is 900-1000℃, the methane flow rate is 50-100 sccm, the argon flow rate is 200-300 sccm, the deposition time is 30-60 min, and the material is cooled to room temperature under argon protection.

[0043] A graphene layer count of less than 10 layers can provide reinforcement while avoiding excessive thickness that could lead to increased brittleness; the range of parameters such as temperature, flow rate, and time has been optimized to adapt to different production conditions and ensure stable graphene quality; argon-protected cooling prevents copper strips from oxidizing at high temperatures and ensures a clean graphene / copper interface.

[0044] According to an embodiment of a method for preparing a copper-graphene composite conductor disclosed herein, in step S2, 10-50 pieces of graphene / copper composite strips are taken and stacked sequentially with the graphene layers facing upwards, so that each graphene layer is in close contact with the copper base surface of the upper copper strip; the top layer is covered with a copper strip without graphene deposition, and after forming a composite blank, it is fixed with a high-temperature resistant fixture.

[0045] The graphene layer faces upward and is in close contact with the upper copper strip substrate to ensure that the graphene and copper substrate are fully bonded during subsequent rolling. The outermost layer is covered with a graphene-free copper strip to protect the inner graphene layer from damage during processing. High-temperature resistant fixtures fix the stacked billets to prevent relative sliding between layers during rolling and ensure uniform interlayer bonding.

[0046] According to an embodiment of a method for preparing a copper-graphene composite conductor disclosed herein, step S3 includes: S31, the composite billet is rolled in multiple passes to metallurgically bond the graphene / copper composite strips of each layer to form a continuous graphene / copper composite master strip. S32, the graphene / copper composite master tape is rolled into a cylindrical blank and then forged on multiple sides to form a rod-shaped blank.

[0047] Multi-pass rolling ensures that each layer of strip is fully bonded, eliminating interlayer gaps and achieving metallurgical bonding; rolling achieves initial orientation, and multi-face forging ensures that graphene is evenly distributed in all directions, while further oriented along the forging direction; forging eliminates internal micropores, improves material density, and provides high-quality billets for subsequent extrusion.

[0048] Specifically, in S31, a two-roll hot rolling mill is used for 6-10 passes, with a reduction of 2-15% per pass and a rolling speed of 0.2-5 m / s. Rolling oil is used for lubrication and cooling to obtain a continuous graphene / copper composite master strip with uniform thickness and no gaps between layers.

[0049] Multi-pass, low-reduction rolling ensures full bonding of strip layers and eliminates interlayer gaps; during rolling, graphene deforms with the copper matrix, initially achieving directional distribution along the rolling direction; rolling oil reduces friction, lowers temperature rise, and protects the graphene layer.

[0050] Specifically, in S32, the composite mother strip is tightly rolled along its length to form a cylindrical blank, which is then forged in multiple directions using free forging at 600-700℃. The hammering frequency is 10-30 times / min, the hammering force is 10-80kN, and the deformation amount is 2-10% for each forging. Each side is forged in sequence until a composite round bar with a diameter of 10-20mm is formed. Inert gas protection is used during the forging process.

[0051] Multi-faceted forging ensures that graphene is evenly distributed in all directions, and further oriented along the forging direction; the impact force of forging further enhances the bonding strength between graphene and the copper matrix; inert gas protection prevents the copper from oxidizing at high temperatures and ensures interface cleanliness.

[0052] Specifically, between S31 and S32, there is also S311, in which the rolled graphene / copper composite master strip is placed in a degreasing agent for ultrasonic cleaning, then rinsed with deionized water, dried, and then subjected to stress-relief annealing in an environment that can prevent the copper-based oxidation of the copper strip.

[0053] Ultrasonic cleaning, combined with degreasing agents, thoroughly removes rolling oil and impurities, providing a clean surface for subsequent forging; annealing eliminates internal stress generated during rolling, improves the material's machinability, and prevents cracking during subsequent forging; annealing makes the copper matrix structure uniform, which is beneficial for subsequent forging and extrusion molding.

[0054] The environment that can prevent the copper-based oxidation of the copper strip can be a protective atmosphere annealing furnace or a vacuum annealing furnace. The protective atmosphere annealing furnace can be a nitrogen-filled protective atmosphere annealing furnace, which is cooled to room temperature with the furnace to prevent copper oxidation and ensure interface quality.

[0055] According to an embodiment of a method for preparing a copper-graphene composite conductor disclosed herein, step S4 includes: S41: The rod-shaped billet is fed into a continuous extruder and extruded through a die to obtain a continuous composite wire. S42: The continuous composite wire is drawn in multiple passes to obtain a composite monofilament with a smaller diameter.

[0056] Continuous extrusion transforms the rod-shaped billet into wire, while drawing further refines the diameter to obtain composite monofilaments of the required specifications. The high temperature and pressure during extrusion allow the graphene to bond optimally with the copper matrix interface. Extrusion and drawing further orient the graphene along the length of the wire, forming a stable conductive channel.

[0057] Specifically, in S41, the continuous extrusion process parameters are: temperature 400-650℃, extrusion wheel speed 2-20r / min, die orifice diameter 5-10mm, extrusion speed 2-10m / s, and nitrogen protection is used; extrusion further enhances the bonding force between the graphene forming the graphene layer and the copper-based interface of the copper strip, and makes it evenly distributed along the line length direction.

[0058] The high temperature and pressure during the extrusion process allow the graphene and copper substrate to bond to an optimal state at the interface; extrusion causes the graphene to be finally oriented along the length of the wire, forming a stable conductive channel; continuous extrusion process can produce long wires to meet industrial needs; nitrogen protection prevents copper oxidation and ensures interface quality.

[0059] Specifically, in S42, a 2-5 drawing process is adopted. After each drawing, annealing is performed in an environment that can prevent the copper base of the copper strip from oxidizing. The annealing temperature is 180-250℃ and the holding time is 10-30min, finally obtaining a composite monofilament with a diameter of 0.10-0.50mm.

[0060] Multi-pass drawing enables precise diameter reduction from larger to smaller diameters to meet different specification requirements; annealing after each drawing pass eliminates work hardening, avoids wire breakage, and ensures a high yield; annealing ensures uniform and stable performance of the final monofilament, with elongation maintained above 15%; The environment for preventing copper-based oxidation of the copper strip can be a protective atmosphere annealing furnace or a vacuum annealing furnace. The protective atmosphere annealing furnace can be a nitrogen-filled protective atmosphere annealing furnace. Annealing in a protective atmosphere annealing furnace or a vacuum annealing furnace can prevent copper oxidation and ensure interface quality.

[0061] According to one embodiment of the preparation method of a copper-graphene composite conductor disclosed herein, in S5, a regular stranding method is used for stranding, and the stranding pitch is 16-30 mm to obtain a copper-graphene composite conductor.

[0062] The stranding of multiple monofilaments gives the final conductor good flexibility, making it easy to lay and use; the regular stranding structure ensures uniform stress on the conductor and improves its bending resistance; conductors with different cross-sectional areas can be stranded as needed to meet diverse requirements.

[0063] According to the present disclosure, a copper-graphene composite conductor is prepared by any of the preparation methods described above.

[0064] The conductor prepared by the method of the present invention has excellent comprehensive properties—the conductivity is improved by about 12%, the tensile strength is improved by about 11%, the heat dissipation performance is improved (temperature drop of about 6°C), and the elongation is ≥15%.

[0065] In practice, the composite conductor has a diameter of 0.50-1.00 mm and a cross-sectional area of ​​0.15-0.30 mm². The graphene in the composite conductor is oriented and uniformly distributed along the processing direction, forming oriented conductive channels.

[0066] The specific implementation steps are as follows: S0: Copper strip pretreatment like Figure 1 As shown, this embodiment first performs copper strip pretreatment.

[0067] Industrial pure copper strips with a purity of ≥99.95% are selected, with specifications of 200mm width (10-500mm is acceptable), 0.1mm thickness (0.05-0.2mm is acceptable), and 20m length (up to 100 meters is acceptable). The strips undergo degreasing, rust removal, deionized water rinsing, and vacuum drying to remove surface oil, oxide layer, and impurities, resulting in pretreated copper strips.

[0068] Degreasing is performed using an alkaline degreasing agent, rust removal is done using a dilute acid solution, and rinsing with deionized water 2-6 times to ensure no residue remains on the surface. Vacuum drying is carried out at 80-100℃ for 10-20 minutes.

[0069] S1: Graphene deposition like Figures 1 to 3 As shown, in this embodiment, graphene is deposited on the surface of a pretreated copper strip using chemical vapor deposition.

[0070] Deposition process parameters: deposition temperature 900-1000℃, carbon source methane (CH4) flow rate 50-100 sccm, carrier gas argon (Ar) flow rate 200-300 sccm, deposition time 30-60 min. The number of graphene layers deposited was controlled to be within 10 layers. After deposition, the material was cooled to room temperature under argon protection to obtain graphene / copper composite tape.

[0071] S2: Assembly of stacked blanks like Figures 1 to 3 As shown, this embodiment involves assembling stacked blanks.

[0072] Take 21 sheets (10-50 sheets are acceptable) of graphene / copper composite strip and stack them sequentially with the graphene layer facing upwards, ensuring that each graphene layer is in close contact with the copper substrate surface of the upper copper strip. Cover the top layer with a sheet of pure copper strip of the same specification without graphene deposition, forming a laminated billet. Secure it with a high-temperature resistant fixture to prevent misalignment during rolling.

[0073] S31 in S3: Cumulative Lamination Composite like Figures 1 to 3 As shown, this embodiment performs cumulative lamination and bonding.

[0074] The composite billet is fed into a two-roll hot rolling mill and rolled in 6-10 passes, with a reduction of 2-15% per pass and a rolling speed of 0.2-5 m / s. Rolling oil is used for lubrication and cooling. After rolling, a continuous graphene / copper composite master strip with uniform thickness and no gaps between layers is obtained.

[0075] During this process, graphene deforms along the copper matrix, initially achieving directional distribution along the rolling direction.

[0076] S311 in S3: Cleaning stress-relief annealing This embodiment performs a cleaning and stress-relief annealing process.

[0077] The rolled graphene / copper composite master tape is immersed in a degreasing agent for ultrasonic cleaning. The degreasing agent formula is: sodium carbonate 20-30 g / L, trisodium phosphate 10-15 g / L, nonionic surfactant 5-8 g / L, with the pH value controlled at around 10. The cleaning temperature is 40-50℃, the ultrasonic frequency is 28-40 kHz, the power density is 0.3-0.5 W / cm², and the cleaning time is 3-5 minutes.

[0078] Then rinse 2-6 times with deionized water at a temperature of 40-50℃ to remove any residual degreasing agent from the surface. The final rinse water should be circulated and filtered to prevent impurities from adhering.

[0079] After drying in a vacuum drying oven, stress-relief annealing is performed at a temperature of 220-270℃ for 1.5-4 hours using a vacuum annealing furnace or a nitrogen-filled protective atmosphere annealing furnace, and the product is cooled to room temperature in the same furnace.

[0080] S32 in S3: Forging Directional Forming like Figures 1 to 3 As shown, this embodiment uses forging directional forming.

[0081] The annealed composite masterbatch is tightly rolled along its length to form a cylindrical blank, which is then placed in a hydraulic forging machine. At a forging temperature of 600-700℃, it undergoes multi-sided forging using free forging techniques, with a hammering frequency of 10-30 times / min, a hammering force of 10-80kN, and a deformation of 2-10% per forging. Multiple sides of the blank are forged sequentially until a composite round bar with a diameter of 15mm is formed. Inert gas protection is used during the forging process to prevent copper oxidation.

[0082] During this process, multi-faceted forging enables graphene to be evenly distributed in multiple directions within the copper matrix, further strengthening the interfacial bonding.

[0083] S41 in S4: Continuous extrusion like Figures 1 to 3 As shown, this embodiment involves continuous extrusion.

[0084] A composite round bar with a diameter of 15mm is fed into a continuous extrusion press and extruded through a die with a diameter of 7mm to obtain a continuous composite wire with a diameter of 7mm.

[0085] Continuous extrusion process parameters: temperature 400-650℃, extrusion roller speed 2-20 r / min, extrusion speed 2-10 m / s, nitrogen protection. Extrusion further enhances the interfacial bonding force between graphene and the copper substrate, and ensures that the graphene is evenly distributed along the length of the wire.

[0086] S42 in S4: Fine wire drawing like Figures 1 to 3 As shown, this embodiment refines the wire drawing process.

[0087] The 7mm diameter composite wire is processed using a three-stage drawing process: the first stage draws to a diameter of 2mm, the second stage to 0.8mm, and the third stage to the target diameter of 0.20mm. After each drawing stage, annealing is performed at 180-250℃ for 10-30 minutes, using a protective atmosphere to prevent copper oxidation. Alternatively, annealing can be carried out in an air-isolated, vacuum, or nitrogen-filled environment to prevent copper oxidation and ensure interface quality.

[0088] Finally, a copper-graphene composite monofilament with a diameter of 0.20 mm was obtained.

[0089] S5: Stranded type like Figures 1 to 3 As shown, this embodiment performs stranding.

[0090] Seven composite monofilaments with a diameter of 0.20 mm were twisted together using a standard twisting method with a twisting pitch of 16-30 mm to obtain a copper-graphene composite conductor with a diameter of 0.62 mm and a cross-sectional area of ​​approximately 0.22 mm².

[0091] Performance testing of a copper-graphene composite conductor

[0092] Test results show that the copper-graphene composite conductor prepared by this invention has excellent conductivity, mechanical properties and heat dissipation properties. The addition of graphene simultaneously improves the strength and conductivity of the composite conductor, making it suitable for fields with high comprehensive performance requirements such as aerospace, new energy vehicles, and industrial robots.

[0093] While specific embodiments of the invention have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of the invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. A method for preparing a copper-graphene composite conductor, characterized in that, Includes the following steps: S1, a graphene layer is deposited on the surface of a copper strip using chemical vapor deposition to obtain a graphene / copper composite strip; S2, multiple graphene / copper composite strips are stacked in the same direction with the graphene layers facing the same direction, and a copper strip without graphene deposition is placed on the outermost layer to form a composite blank; S3, the composite billet is subjected to multiple deformation processes, and the material of each layer is metallurgically bonded through cumulative deformation. The composite billet is then formed into a rod-shaped billet through multi-directional forging. S4, the rod-shaped blank is subjected to multi-stage diameter reduction processing to gradually reduce the cross-sectional area and obtain a composite monofilament with a smaller diameter; S5, multiple composite monofilaments are twisted together to obtain the copper-graphene composite conductor.

2. The method for preparing the copper-graphene composite conductor according to claim 1, characterized in that, Before step S1, step S0 is also included, in which the copper strip is subjected to surface cleaning treatment to remove oil, oxide layer and impurities, so as to obtain the copper strip.

3. The method for preparing the copper-graphene composite conductor according to claim 2, characterized in that, In the S0 process, industrial copper strips with a purity of ≥99.95% are selected and subjected to surface purification treatment through degreasing, rust removal, deionized water rinsing, and vacuum drying.

4. The method for preparing the copper-graphene composite conductor according to claim 1, characterized in that, In step S1, the number of graphene layers is ≤10, the deposition temperature is 900-1000℃, the methane flow rate is 50-100 sccm, the argon flow rate is 200-300 sccm, the deposition time is 30-60 min, and the deposition is cooled to room temperature under argon protection.

5. The method for preparing the copper-graphene composite conductor according to claim 1, characterized in that, In step S2, 10-50 pieces of graphene / copper composite strip are taken and stacked sequentially with the graphene layers facing upwards, so that each graphene layer is in close contact with the copper base surface of the upper copper strip; the top layer is covered with a copper strip without graphene deposition, and after forming a composite blank, it is fixed with a high-temperature resistant fixture.

6. The method for preparing the copper-graphene composite conductor according to claim 1, characterized in that, S3 includes: S31, the composite billet is rolled in multiple passes to metallurgically bond the graphene / copper composite strips of each layer to form a continuous graphene / copper composite master strip. S32, the graphene / copper composite master tape is rolled into a cylindrical blank and then forged on multiple sides to form a rod-shaped blank.

7. The method for preparing the copper-graphene composite conductor according to claim 6, characterized in that, In S31, a two-roll hot rolling mill is used for 6-10 passes, with a reduction of 2-15% per pass and a rolling speed of 0.2-5 m / s. Rolling oil is used for lubrication and cooling to obtain a continuous graphene / copper composite master strip with uniform thickness and no gaps between layers.

8. The method for preparing the copper-graphene composite conductor according to claim 6, characterized in that, In S32, the composite master tape is tightly rolled along its length to form a cylindrical blank, which is then forged in multiple directions using free forging at 600-700℃. The hammering frequency is 10-30 times / min, the hammering force is 10-80kN, and the deformation amount is 2-10% for each forging. Each side is forged in sequence until a composite round bar with a diameter of 10-20mm is formed. Inert gas protection is used during the forging process.

9. The method for preparing the copper-graphene composite conductor according to claim 6, characterized in that, Between S31 and S32, there is also S311, in which the rolled graphene / copper composite master strip is placed in a degreasing agent for ultrasonic cleaning, then rinsed with deionized water, dried, and then subjected to stress-relief annealing in an environment that can prevent the copper-based oxidation of the copper strip.

10. The method for preparing the copper-graphene composite conductor according to claim 1, characterized in that, The S4 includes: S41: The rod-shaped billet is fed into a continuous extruder and extruded through a die to obtain a continuous composite wire. S42: The continuous composite wire is drawn in multiple passes to obtain a composite monofilament with a smaller diameter.

11. The method for preparing the copper-graphene composite conductor according to claim 10, characterized in that, In S41, the continuous extrusion process parameters are: temperature 400-650℃, extrusion roller speed 2-20r / min, die orifice diameter 5-10mm, extrusion speed 2-10m / s, and nitrogen protection is used; extrusion further enhances the bonding force between the graphene forming the graphene layer and the copper-based interface of the copper strip, and makes it evenly distributed along the line length direction.

12. The method for preparing the copper-graphene composite conductor according to claim 10, characterized in that, In S42, a 2-5 drawing process is adopted. After each drawing process, annealing is performed in an environment that can prevent the copper base of the copper strip from oxidizing. The annealing temperature is 180-250℃ and the holding time is 10-30min, finally obtaining a composite monofilament with a diameter of 0.10-0.50mm.

13. The method for preparing the copper-graphene composite conductor according to claim 9, characterized in that, In S5, a regular stranding method is used for stranding, with a stranding pitch of 16-30 mm, to obtain a copper-graphene composite conductor.

14. A copper-graphene composite conductor, characterized in that, The copper-graphene composite conductor prepared by the preparation method according to any one of claims 1-13.

Images