A method for preparing a copper / graphene composite wire by a winding method

Abstract

A method for preparing copper / graphene composite wire by winding method, first, uniformly coating carbon source on pretreated copper foil or laminating solid film-shaped carbon source with pretreated copper foil to make copper-carbon composite, then winding the copper-carbon composite on copper wire, loading into copper pipe with matching inner diameter, then plastic processing of the copper pipe, including hole type rolling and drawing, then cutting off both ends of the plastic processed copper pipe assembly, then putting into CVD furnace, growing graphene on the inside of the copper pipe and the surface of the copper foil. Finally, drawing the above graphene grown copper pipe assembly to obtain high performance copper / graphene composite wire. The copper / graphene composite wire prepared by the method of preparing copper-carbon composite, winding and loading into pipe, plastic processing and CVD growing graphene has uniform distribution of graphene, relatively complete structure, good quality, high electrical conductivity and strength. The wire has good application prospect in the fields of power electronics, electric vehicles and the like.

Description

Technical Field

[0001] This invention belongs to the field of copper / graphene composite material preparation, specifically relating to a method for preparing copper / graphene composite wires by winding. Background Technology

[0002] Conductive materials are fundamental materials crucial for the energy and power industries. Traditional copper conductors are widely used and have broad applications due to their excellent electrical and thermal conductivity. However, with rapid societal and technological advancements, the performance requirements for conductive copper materials are increasingly stringent across various industries. Copper-based composite materials, formed by combining copper and graphene, hold promise for further performance breakthroughs by leveraging the high strength, high conductivity, and high current-carrying capacity of graphene. Therefore, copper / graphene composites are currently among the most researched materials in the fields of electrical engineering and energy-related areas.

[0003] However, due to the influence of material properties, copper / graphene composites face technical bottlenecks in their research and development. For example, graphene tends to agglomerate due to van der Waals forces, resulting in poor interfacial wetting between copper and graphene and weak interfacial connectivity, leading to difficulties in subsequent processing. Furthermore, graphene cannot be oriented, resulting in significant discrepancies between its performance and theoretical values. Currently, the main methods for preparing copper / graphene composites include traditional powder metallurgy, electrochemical deposition, and chemical vapor deposition (CVD). Powder metallurgy involves mixing graphene powder and copper powder to prepare copper / graphene composites in batches. Mixing copper and graphene powders includes ball milling, chemical reaction mixing, and surface treatment mixing. Ball milling is difficult to avoid graphene agglomeration, and the graphene structure is damaged to varying degrees during the process. Chemical methods are beneficial for achieving good bonding between Cu and graphene, but these processes are complex, environmentally unfriendly, produce poorly crystallized graphene oxide with many defects, often requiring reduction treatment, and the performance of the resulting composite material is far below expectations. Electrochemical deposition involves surface modification to uniformly disperse graphene in a copper electrolyte, then using electroplating principles to deposit copper and graphene together into a film. The advantage of this method is the easy achievement of uniform graphene dispersion; however, its disadvantages include a relatively loose microstructure and limitations in film size, making it difficult to fabricate other profiles. CVD is currently the most commonly used process for preparing high-quality graphene. It utilizes gaseous carbon sources (methane, acetylene, etc.) at high temperatures to decompose on the surface of single-crystal or polycrystalline copper foil substrates, assembling them into single-layer or multi-layer graphene. This method allows for large-area graphene growth, and the in-situ grown graphene naturally maintains a good interfacial bond with the copper substrate, effectively avoiding problems such as interfacial porosity. However, growing only one or a few layers of graphene on the copper foil surface and then stacking them to prepare composite materials is a complex process, making mass production and application difficult. Currently, wires are needed in the manufacture of cables and the winding of motor coils. There is an urgent need to develop new manufacturing processes to mass-produce high-quality copper / graphene composite wires, while solving problems such as graphene dispersion, copper-carbon interface bonding, graphene orientation, and wire forming. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and to propose a method for preparing high-performance copper / graphene composite wires, the specific steps of which are as follows:

[0005] Step 1: Coat the carbon source evenly on the pretreated copper foil or stack the solid film carbon source with the pretreated copper foil to form a copper-carbon composite.

[0006] Step 2: Wind the above copper-carbon composite onto a copper wire, then insert it into a copper tube with a matching diameter, and seal both ends with copper rods matching the diameter of the copper tube by welding to form a copper tube assembly.

[0007] Step 3: Perform plastic forming on the above copper tube assembly, which includes die rolling and drawing;

[0008] Step 4: Cut off both ends of the copper tube assembly after plastic processing in Step 2, place it in a CVD furnace, and grow internal graphene to obtain a copper / graphene rod.

[0009] Step 5: The copper / graphene rod obtained in Step 3 is further drawn to obtain the high-performance copper / graphene composite wire.

[0010] Furthermore, the carbon source mentioned in step one is a liquid carbon source or a solid carbon source. The liquid carbon source includes, but is not limited to, glucose, paraffin, and tetrabutyl titanate. The liquid carbon source can be directly coated onto the surface of the copper foil. The solid carbon source includes, but is not limited to, polymethyl methacrylate, malic acid, maleic acid, stearic acid, and lanthanum acetate. The solid carbon source is uniformly coated onto the surface of the copper foil after being dissolved in an organic solvent or melted by heating. The carbon film includes, but is not limited to, polyethylene, polyvinyl chloride, and polyvinylidene chloride.

[0011] Furthermore, the specific steps for growing graphene in the CVD furnace in step four are as follows:

[0012] (1) Place the copper tube assembly outside the heating zone of the CVD furnace tubes, evacuate the CVD furnace, and then introduce Ar gas (100-500 sccm) (e.g., Ar gas flow rate of 100, 150, 200, 250, 300, 350, 400, 450 or 500 sccm) and H2 gas (50-100 sccm) (e.g., H2 gas flow rate of 50, 60, 70, 80, 90 or 100 sccm) to raise the furnace temperature to 700- 1000℃ (e.g., furnace temperature rises to 700℃, 710℃, 720℃, 730℃, 740℃, 750℃, 760℃, 770℃, 780℃, 790℃, 800℃, 810℃, 820℃, 840℃, 850℃, 860℃, 870℃, 880℃, 890℃, 900℃, 910℃, 920℃, 930℃, 940℃, 950℃, 960℃, 970℃, 980℃, 990℃ or 1000℃);

[0013] (2) Quickly push the copper tube assembly into the furnace tube heating zone and hold it for 5 to 30 minutes (e.g., hold for 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29 or 30 minutes).

[0014] (3) Turn off the H2 gas and let the copper foil cool to room temperature under Ar atmosphere.

[0015] Furthermore, in step three, the copper tube assembly undergoes plastic processing, with the total deformation controlled at 50%-80% (e.g., the total deformation is controlled at 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, or 80%), and the deformation per pass is 5%-15% (e.g., the deformation per pass is 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%).

[0016] Further, the thickness of the copper foil in step one is 5-100μm (for example, the thickness of the copper foil is 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm or 100μm), the diameter of the copper wire is 0.5-2mm (the diameter of the copper wire is 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm or 2mm), and the length of the copper tube > the length of the copper wire > the width of the copper foil.

[0017] Furthermore, the copper foil mentioned in step one includes pure copper foil, copper-nickel alloy foil, copper-molybdenum alloy foil, copper-tungsten alloy foil, etc.

[0018] Further, the drawing rate in step five is 1-3 m / min (e.g., the drawing rate is 1 m / min, 1.5 m / min, 2 m / min, 2.5 m / min or 3 m / min), and the deformation per pass is 5%-15% (e.g., the deformation per pass is 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%). The diameter of the final copper / graphene composite wire is 0.05-0.8 mm (e.g., the diameter of the copper / graphene composite wire is 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75 or 0.8 mm).

[0019] Further, the carbon source in step one accounts for 0.01% to 1% of the mass of the copper-carbon complex (for example, the carbon source accounts for 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, or 1% of the mass of the copper-carbon complex).

[0020] The method for preparing the copper / graphene composite wire of the present invention is simple and easy to implement. During the preparation process, the graphene is generated in situ from the copper matrix, resulting in high quality, good dispersibility, strong interfacial bonding with the matrix, and directional alignment along the drawing direction, which helps to improve the conductivity and mechanical properties of the wire. Attached Figure Description

[0021] Figure 1 A schematic diagram of the process flow for preparing copper / graphene composite wires according to an embodiment of the present invention;

[0022] Figure 2 Raman spectrum of the copper / graphene composite wire prepared in Example 1 of this invention. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0024] like Figure 1 As shown, 1. A method for preparing copper / graphene composite wires by winding, comprising the following steps:

[0025] Step 1: Coat the carbon source evenly on the pretreated copper foil or stack the solid film carbon source with the pretreated copper foil to form a copper-carbon composite.

[0026] Step 2: Wind the above copper-carbon composite onto a copper wire, then insert it into a copper tube with a matching diameter, and seal both ends with copper rods matching the diameter of the copper tube by welding to form a copper tube assembly.

[0027] Step 3: Perform plastic forming on the above copper tube assembly, which includes die rolling and / or drawing, to obtain the plastic formed copper tube assembly (i.e., the intermediate conductor);

[0028] Step 4: Cut off both ends of the copper tube assembly after plastic processing in Step 3, place it in a CVD furnace, and grow internal graphene to obtain a copper / graphene rod.

[0029] Step 5: The copper / graphene rod obtained in Step 4 is further drawn to obtain the copper / graphene composite wire.

[0030] Example 1

[0031] Step 1: Select a copper wire with a diameter of 0.5 mm and a length of 100 mm, a copper foil with a width of 80 mm and a thickness of 10 μm, a copper tube with an outer diameter of 10 mm, an inner diameter of 6 mm and a length of 120 mm, and a copper rod with a diameter of 6 mm. Place the copper foil, copper wire, copper tube, and copper rod in acetone or alcohol for ultrasonic cleaning, and then dry them. Apply liquid paraffin (National Drug Number 30139828) evenly to the surface of the copper foil at a mass percentage of 0.1%, leaving the portion of the copper foil welded to the copper wire uncoated.

[0032] Step 2: Weld one end of the copper foil from Step 1 to the copper wire; rotate the copper wire to wind the paraffin-coated copper foil, then use a mold to press it tightly so that the diameter after winding is 5.8mm, and then put it into a matching copper tube. After plugging both ends of the copper tube with copper rods and welding them to seal, a copper tube assembly is formed.

[0033] Step 3: The copper tube assembly obtained in Step 2 is first rolled in multiple passes with a deformation amount of 10% per pass to obtain a bar with a diameter of 5mm. Then, it is drawn in multiple passes with a deformation amount of 10% per pass and a speed of 1.5m per minute until the copper tube assembly is processed to a diameter of 3mm.

[0034] Step 4: Cut off the copper rod plugs welded to both ends of the copper tube assembly after plastic processing in Step 3, and then place it outside the heating zone of the CVD furnace. Evacuate the CVD furnace, and then introduce Ar gas (200 sccm) and H2 gas (100 sccm) to raise the furnace temperature to 1000℃. Then, quickly push the part containing the copper tube assembly into the furnace tube heating zone and hold it at that temperature for 20 minutes. After that, turn off the H2 gas, and the copper tube assembly cools to room temperature in the Ar atmosphere to obtain copper / graphene rods.

[0035] Step 5: The copper / graphene rod obtained in Step 4 is further drawn at a rate of 2 m / min and a deformation of 10% per pass, finally yielding a copper / graphene composite wire with a diameter of 0.5 mm.

[0036] A schematic diagram of the fabrication process of the composite conductor is shown below. Figure 1 As shown, the microstructure of the conductor cross-section is as follows: Figure 2 As shown, the interior exhibits a concentric circular structure, as revealed by Raman spectroscopy analysis. Figure 2As shown, graphene has grown inside the conductor. The conductivity of the copper / graphene composite conductor was measured using a Keithley power supply voltmeter via the voltammetry method, and was found to be 99% IACS. The tensile strength of the composite conductor was tested using a tensile tester and found to be 450 MPa.

[0037] Example 2

[0038] Step 1: Select a copper wire with a diameter of 1mm and a length of 100mm, a copper foil with a width of 80mm and a thickness of 50μm, a copper tube with an outer diameter of 10mm, an inner diameter of 8mm and a length of 110mm, and a copper rod with a diameter of 8mm. Place the copper foil, copper wire, copper tube, and copper rod into acetone or alcohol for ultrasonic cleaning, and then dry them. Apply 98% pure tetrabutyl titanate (National Drug Number 80122860) evenly to the surface of the copper foil, according to a mass percentage of 0.2% of tetrabutyl titanate to copper foil. The portion of the copper foil welded to the copper wire at one end is not coated with tetrabutyl titanate.

[0039] Step 2: Weld one end of the copper foil from Step 1 to the copper wire; rotate the copper wire to wind the paraffin-coated copper foil, then use a mold to press it tightly so that the diameter of the coiled part is 7.8mm, and then put it into a matching copper tube. After plugging both ends of the copper tube with copper rods, weld them to seal, and a copper tube assembly is formed.

[0040] Step 3: The copper tube assembly obtained in Step 2 is first rolled in multiple passes with a deformation amount of 15% per pass to obtain a bar with a diameter of 5mm. Then, it is drawn in multiple passes with a deformation amount of 10% per pass and a speed of 1m per minute until the copper tube assembly is processed to a diameter of 4mm.

[0041] Step 4: Cut off the copper rod plugs welded to both ends of the copper tube assembly after plastic processing in Step 3, and then place it outside the heating zone of the CVD furnace. Evacuate the CVD furnace, and then introduce Ar gas (500 sccm) and H2 gas (50 sccm) to raise the furnace temperature to 900℃. Then, quickly push the part containing the copper tube assembly into the furnace tube heating zone and hold it at that temperature for 15 minutes. After that, turn off the H2 gas, and the copper tube assembly cools down to room temperature in the Ar atmosphere to obtain copper / graphene rods.

[0042] Step 5: The copper / graphene rod obtained in Step 4 is further drawn at a rate of 2 m / min and a deformation of 10% per pass, finally yielding a copper / graphene composite wire with a diameter of 0.8 mm.

[0043] The conductivity of the copper / graphene composite wire was measured to be 98.5% IACS using a Keithley power supply voltmeter via the voltammetry method; the strength of the composite wire was tested to be 500 MPa using a tensile tester.

[0044] Example 3

[0045] Step 1: Select a copper wire with a diameter of 2mm and a length of 120mm, a copper foil with a width of 100mm and a thickness of 100μm, a copper tube with an outer diameter of 10mm, an inner diameter of 8mm and a length of 130mm, and a copper rod with a diameter of 8mm. Soak the copper foil, copper wire, copper tube, and copper rod in acetone or alcohol for ultrasonic cleaning, and then dry them. Apply a 5g / L glucose aqueous solution (National Drug Number 69327565) evenly to the surface of the copper foil, with a mass percentage of 0.05% titanium glucose to copper foil. Do not coat the copper foil with glucose at the end where it is welded to the copper wire.

[0046] Step 2: Weld one end of the copper foil from Step 1 to the copper wire; rotate the copper wire to wind the glucose-coated copper foil, then use a mold to compress it tightly, so that the diameter of the coiled part is 7.8mm, and then put it into a matching copper tube. After plugging both ends of the copper tube with copper rods, weld them to seal, and a copper tube assembly is formed.

[0047] Step 3: The copper tube assembly obtained in Step 2 is first rolled in multiple passes with a deformation amount of 10% per pass to obtain a bar with a diameter of 6mm. Then, it is drawn in multiple passes with a deformation amount of 15% per pass and a speed of 1.5m per minute until the copper tube assembly is processed to a diameter of 5mm.

[0048] Step 4: Cut off the parts with copper rod plugs welded to both ends of the copper tube assembly after plastic processing in Step 3, and then place it outside the heating zone of the CVD furnace. Evacuate the CVD furnace, and then introduce Ar gas (500 sccm) and H2 gas (100 sccm) to raise the furnace temperature to 800℃. Then, quickly push the part containing the copper tube assembly into the furnace tube heating zone and hold it at that temperature for 30 minutes. After that, turn off the H2 gas, and the copper tube assembly cools to room temperature in the Ar atmosphere to obtain copper / graphene rods.

[0049] Step 5: The copper / graphene rod obtained in Step 4 is further drawn at a rate of 3 m / min and a deformation of 10% per pass, finally yielding a copper / graphene composite wire with a diameter of 0.3 mm.

[0050] The conductivity of the copper / graphene composite wire was measured to be 99.5% IACS using a Keithley power supply voltmeter via the voltammetry method; the strength of the composite wire was tested to be 475 MPa using a tensile tester.

[0051] Example 4

[0052] Step 1: Select a copper wire with a diameter of 2mm and a length of 120mm, a copper foil with a width of 100mm and a thickness of 25μm, a copper tube with an outer diameter of 6mm, an inner diameter of 4mm and a length of 130mm, and a copper rod with a diameter of 4mm. Place the copper foil, copper wire, copper tube, and copper rod in acetone or alcohol for ultrasonic cleaning, and then dry them thoroughly. Using a stearic acid to copper foil mass percentage of 1%, heat 0.35g of stearic acid (National Drug Number 30171118) until melted, and then evenly coat the copper foil surface. Do not coat the portion of the copper foil that is welded to the copper wire with stearic acid.

[0053] Step 2: Weld one end of the copper foil from Step 1 to the copper wire; rotate the copper wire to wind the copper foil coated with stearic acid, then use a mold to compress it tightly, so that the diameter of the wound is 3.8mm, and then put it into a matching copper tube. After plugging both ends of the copper tube with copper rods, weld them to seal, and a copper tube assembly is formed.

[0054] Step 3: The copper tube assembly obtained in Step 2 is drawn in multiple passes with a deformation amount of 10% per pass, at a drawing rate of 1m per minute, until the copper tube assembly is processed to a diameter of 2mm.

[0055] Step 4: Cut off the parts of the copper tube assembly with copper rod plugs welded to both ends after plastic processing in Step 3, and then place it outside the heating zone of the CVD furnace. Evacuate the CVD furnace, and then introduce Ar gas (100 sccm) and H2 gas (100 sccm) to raise the furnace temperature to 700℃. Then, quickly push the part containing the copper tube assembly into the furnace tube heating zone and hold it at that temperature for 30 minutes. After that, turn off the H2 gas, and the copper tube assembly cools down to room temperature in the Ar atmosphere to obtain copper / graphene rods.

[0056] Step 5: The copper / graphene rod obtained in step 4 is further drawn at a rate of 1.5 m / min and a deformation of 10% per pass, finally yielding a copper / graphene composite wire with a diameter of 0.3 mm.

[0057] The conductivity of the copper / graphene composite wire was measured to be 96.5% IACS using a Keithley power supply voltmeter via the voltammetry method; the strength of the composite wire was tested to be 550 MPa using a tensile tester.

[0058] Example 5

[0059] Step 1: Select a copper wire with a diameter of 0.5 mm and a length of 120 mm, a copper foil with a width of 100 mm and a thickness of 5 μm, a copper tube with an outer diameter of 7 mm, an inner diameter of 5 mm and a length of 130 mm, and a copper rod with a diameter of 5 mm. Place the copper foil, copper wire, copper tube, and copper rod in acetone or alcohol for ultrasonic cleaning, and then dry them thoroughly. Weigh out malic acid at a mass percentage of 0.01% of the copper foil. Dissolve 0.025 g of malic acid (National Drug Number 30111632) in 1 ml of ethanol and evenly coat it onto the surface of the copper foil. Do not coat the portion of the copper foil that is welded to the copper wire with malic acid.

[0060] Step 2: Weld one end of the copper foil from Step 1 to the copper wire; rotate the copper wire to wind the malic acid-coated copper foil, then use a mold to compress it to a diameter of 4.8mm after winding. Then place it into a matching copper tube and dry it. After plugging both ends of the copper tube with copper rods and welding them to seal, a copper tube assembly is formed.

[0061] Step 3: The copper tube assembly obtained in Step 2 is drawn in multiple passes with a deformation amount of 10% per pass, at a drawing rate of 1m per minute, until the copper tube assembly is processed to a diameter of 3mm.

[0062] Step 4: Cut off the copper rod plugs welded to both ends of the copper tube assembly after plastic processing in Step 3, and then place it outside the heating zone of the CVD furnace. Evacuate the CVD furnace, and then introduce Ar gas (100 sccm) and H2 gas (50 sccm) to raise the furnace temperature to 950℃. Then, quickly push the part containing the copper tube assembly into the furnace tube heating zone and hold it at that temperature for 20 minutes. After that, turn off the H2 gas, and the copper tube assembly cools to room temperature in the Ar atmosphere to obtain copper / graphene rods.

[0063] Step 5: The copper / graphene rod obtained in Step 4 is further drawn at a rate of 3 m / min and a deformation of 15% per pass, finally yielding a copper / graphene composite wire with a diameter of 0.5 mm.

[0064] The conductivity of the copper / graphene composite wire was measured to be 100.5% IACS using a Keithley power supply voltmeter via the voltammetry method; the strength of the composite wire was tested to be 500 MPa using a tensile tester.

[0065] Example 6

[0066] Step 1: Select a copper wire with a diameter of 1mm and a length of 120mm, a copper foil with a width of 100mm and a thickness of 50μm, a copper tube with an outer diameter of 7mm, an inner diameter of 5mm and a length of 130mm, and a copper rod with a diameter of 5mm. Place the copper foil, copper wire, copper tube, and copper rod in acetone or alcohol for ultrasonic cleaning, and then dry them. Weigh out polymethyl methacrylate (PMMA) according to a mass percentage of 0.5% between PMMA (National Drug Number XW90111471) and copper foil. Dissolve 0.0313g of PMMA (National Drug Number XW90111471) in 10ml of acetone and evenly coat it onto the surface of the copper foil. Do not coat the portion of the copper foil where it is welded to the copper wire with PMMA.

[0067] Step 2: Weld one end of the copper foil from Step 1 to the copper wire; rotate the copper wire to wind the copper foil coated with polymethyl methacrylate, then use a mold to press it tightly so that the diameter of the wound is 4.8mm, then put it into a matching copper tube and dry it. After plugging both ends of the copper tube with copper rods, weld them to seal, and a copper tube assembly is formed.

[0068] Step 3: The copper tube assembly obtained in Step 2 is drawn in multiple passes with a deformation amount of 10% per pass, at a drawing rate of 1m per minute, until the copper tube assembly is processed to a diameter of 3mm.

[0069] Step 4: Cut off the copper rod plugs welded to both ends of the copper tube assembly after plastic processing in Step 3, and then place it outside the heating zone of the CVD furnace. Evacuate the CVD furnace, and then introduce Ar gas (200 sccm) and H2 gas (50 sccm) to raise the furnace temperature to 850℃. Then, quickly push the part containing the copper tube assembly into the furnace tube heating zone and hold it at that temperature for 20 minutes. After that, turn off the H2 gas, and the copper tube assembly cools to room temperature in the Ar atmosphere to obtain copper / graphene rods.

[0070] Step 5: The copper / graphene rod obtained in step 4 is further drawn at a rate of 1.5 m / min and a deformation of 15% per pass, finally yielding a copper / graphene composite wire with a diameter of 0.05 mm.

[0071] The conductivity of the copper / graphene composite wire was measured using a Keithley power supply voltmeter via the voltammetry method, and was found to be 97% IACS. The tensile strength of the composite wire was tested using a tensile tester and found to be 600 MPa.

[0072] Example 7

[0073] Step 1: Select a copper wire with a diameter of 2mm and a length of 80mm, a copper foil with a width of 60mm and a thickness of 75μm, a copper tube with an outer diameter of 8mm, an inner diameter of 6mm and a length of 100mm, and a copper rod with a diameter of 6mm. Soak the copper foil, copper wire, copper tube, and copper rod in acetone or alcohol for ultrasonic cleaning, and then dry them thoroughly. Weigh out maleic acid (National Drug Number 30111316) at a mass percentage of 0.01% of the copper foil. Dissolve 0.001g of maleic acid in 5ml of ethanol and evenly coat it onto the corresponding copper foil surface. Do not coat the portion of the copper foil where it is welded to the copper wire with maleic acid.

[0074] Step 2: Weld one end of the copper foil from Step 1 to the copper wire; rotate the copper wire to wind the copper foil coated with maleic acid, then use a mold to press it tightly so that the diameter of the wound is 5.8mm, then put it into a copper tube and dry it. After plugging both ends of the copper tube with copper rods, weld them to seal, and a copper tube assembly is formed.

[0075] Step 3: The copper tube assembly obtained in Step 2 is drawn in multiple passes with a deformation amount of 5% per pass, at a drawing rate of 1m per minute, until the copper tube assembly is processed to a diameter of 4mm.

[0076] Step 4: Cut off the copper rod plugs welded to both ends of the copper tube assembly after plastic processing in Step 3, and then place it outside the heating zone of the CVD furnace. Evacuate the CVD furnace, and then introduce Ar gas (200 sccm) and H2 gas (100 sccm) to raise the furnace temperature to 800℃. Then, quickly push the part containing the copper tube assembly into the furnace tube heating zone and hold it at that temperature for 10 minutes. After that, turn off the H2 gas, and the copper tube assembly cools down to room temperature in the Ar atmosphere to obtain copper / graphene rods.

[0077] Step 5: The copper / graphene rod obtained in Step 4 is further drawn at a rate of 2 m / min and a deformation of 10% per pass, finally yielding a copper / graphene composite wire with a diameter of 0.1 mm.

[0078] The conductivity of the copper / graphene composite wire was measured to be 101% IACS using a Keithley power supply voltmeter via the voltammetry method; the strength of the composite wire was tested to be 550 MPa using a tensile tester.

[0079] Example 8

[0080] Step 1: Select a copper wire with a diameter of 0.5 mm and a length of 80 mm, a copper foil with a width of 60 mm and a thickness of 25 μm, a copper tube with an outer diameter of 8 mm, an inner diameter of 6 mm and a length of 100 mm, and a copper rod with a diameter of 6 mm. Place the copper foil, copper wire, copper tube, and copper rod in acetone or alcohol for ultrasonic cleaning, and then dry them thoroughly. Weigh out lanthanum acetate according to a mass percentage of 0.025% (national drug number XW1005879045) to copper foil. Dissolve 0.0012 g of lanthanum acetate in 5 ml of deionized water and evenly coat it onto the surface of the copper foil. Do not coat the portion of the copper foil that is welded to the copper wire with lanthanum acetate.

[0081] Step 2: Weld one end of the copper foil from Step 1 to the copper wire; rotate the copper wire to wind the copper foil coated with lanthanum acetate, then use a mold to press it tightly so that the diameter of the wound is slightly less than 5.8 mm, then put it into a copper tube and dry it. Then, plug both ends of the copper tube with copper rods and weld them to seal, thus forming a copper tube assembly.

[0082] Step 3: The copper tube assembly obtained in Step 2 is drawn in multiple passes with a deformation amount of 10% per pass, at a drawing rate of 1m per minute, until the copper tube assembly is processed to a diameter of 3mm.

[0083] Step 4: Cut off the parts with copper rod plugs welded to both ends of the copper tube assembly after plastic processing in Step 3, and then place it outside the heating zone of the CVD furnace. Evacuate the CVD furnace, and then introduce Ar gas (200 sccm) and H2 gas (100 sccm) to raise the furnace temperature to 900℃. Then, quickly push the part containing the copper tube assembly into the furnace tube heating zone and hold it at that temperature for 10 minutes. After that, turn off the H2 gas, and the copper tube assembly cools down to room temperature in the Ar atmosphere to obtain copper / graphene rods.

[0084] Step 5: The copper / graphene rod obtained in step 4 is further drawn at a rate of 2.5 m / min and a deformation of 15% per pass, finally yielding a copper / graphene composite wire with a diameter of 0.3 mm.

[0085] The conductivity of the copper / graphene composite wire was measured to be 99.5% IACS using a Keithley power supply voltmeter via the voltammetry method; the strength of the composite wire was tested to be 520 MPa using a tensile tester.

[0086] Example 9

[0087] Step 1: Select a copper wire with a diameter of 1.0 mm and a length of 80 mm, a copper foil with a width of 60 mm and a thickness of 100 μm, a copper tube with an outer diameter of 8 mm, an inner diameter of 6 mm and a length of 100 mm, and a copper rod with a diameter of 6 mm. Soak the copper foil, copper wire, copper tube, and copper rod in acetone or alcohol for ultrasonic cleaning, and then dry them thoroughly. Lay a 10 μm thick polyethylene film flat on the surface of the copper foil, leaving the portion of the copper foil welded to the copper wire without the polyethylene film.

[0088] Step 2: Weld one end of the copper foil laminated with the polyethylene film in Step 1 to a copper wire; rotate the copper wire to wind the copper foil and polyethylene film together, then use a mold to compress it tightly, so that the diameter of the wound is 5.8mm. Then place it in a copper tube and dry it. Finally, plug both ends of the copper tube with copper rods and weld them to seal, thus forming a copper tube assembly.

[0089] Step 3: The copper tube assembly obtained in Step 2 is drawn in multiple passes with a deformation amount of 10% per pass, at a drawing rate of 1m per minute, until the copper tube assembly is processed to a diameter of 3mm.

[0090] Step 4: Cut off the copper rod plugs welded to both ends of the copper tube assembly after plastic processing in Step 3, and then place it outside the heating zone of the CVD furnace. Evacuate the CVD furnace, and then introduce Ar gas (200 sccm) and H2 gas (100 sccm) to raise the furnace temperature to 850℃. Then, quickly push the part containing the copper tube assembly into the furnace tube heating zone and hold it at that temperature for 15 minutes. After that, turn off the H2 gas, and the copper tube assembly cools to room temperature in the Ar atmosphere to obtain copper / graphene rods.

[0091] Step 5: The copper / graphene rod obtained in Step 4 is further drawn at a rate of 1.5 m / min and a deformation of 10% per pass, finally yielding a copper / graphene composite wire with a diameter of 0.2 mm.

[0092] The conductivity of the copper / graphene composite wire was measured to be 96.5% IACS using a Keithley power supply voltmeter via the voltammetry method; the strength of the composite wire was tested to be 580 MPa using a tensile tester.

[0093] Example 10

[0094] Step 1: Select a copper wire with a diameter of 1.0 mm and a length of 80 mm, a copper foil with a width of 60 mm and a thickness of 80 μm, a copper tube with an outer diameter of 10 mm, an inner diameter of 7 mm and a length of 100 mm, and a copper rod with a diameter of 7 mm. Place the copper foil, copper wire, copper tube, and copper rod in acetone or alcohol for ultrasonic cleaning, and then dry them. Lay a 5 μm thick polypropylene film flat on the surface of the copper foil, leaving the portion of the copper foil welded to the copper wire without the polypropylene film.

[0095] Step 2: Weld one end of the copper foil laminated with the polyethylene film in Step 1 to a copper wire; rotate the copper wire to wind the copper foil and polypropylene film, then use a mold to press them tightly so that the diameter after winding is 6.8mm, then put them into a copper tube and dry them. Then, plug both ends of the copper tube with copper rods and weld them to seal, thus forming a copper tube assembly.

[0096] Step 3: The copper tube assembly obtained in Step 2 is drawn in multiple passes with a deformation amount of 5% per pass, at a drawing rate of 1m per minute, until the copper tube assembly is processed to a diameter of 2mm.

[0097] Step 4: Cut off the parts with copper rod plugs welded to both ends of the copper tube assembly after plastic processing in Step 3, and then place the part outside the heating zone of the CVD furnace. Evacuate the CVD furnace, and then introduce Ar gas (300 sccm) and H2 gas (100 sccm) to raise the furnace temperature to 700℃. Then, quickly push the part containing the copper tube assembly into the furnace tube heating zone and hold it at that temperature for 5 minutes. After that, turn off the H2 gas, and the copper tube assembly cools down to room temperature in the Ar atmosphere to obtain copper / graphene rods.

[0098] Step 5: The copper / graphene rod obtained in Step 4 is further drawn at a rate of 1.0 m / min, with a deformation of about 10% per pass, finally yielding a copper / graphene composite wire with a diameter of 0.3 mm.

[0099] The conductivity of the copper / graphene composite wire was measured using a Keithley power supply voltmeter via the voltammetry method, and was found to be 95% IACS. The tensile strength of the composite wire was tested to be 600 MPa.

[0100] Example 11

[0101] Step 1: Select a copper wire with a diameter of 1.0 mm and a length of 80 mm, a copper foil with a width of 60 mm and a thickness of 100 μm, a copper tube with an outer diameter of 10 mm, an inner diameter of 7 mm and a length of 100 mm, and a copper rod with a diameter of 7 mm. Soak the copper foil, copper wire, copper tube, and copper rod in acetone or alcohol for ultrasonic cleaning, and then dry them thoroughly. Lay a 30 μm thick polyvinyl chloride (PVC) film flat on the surface of the copper foil, leaving the PVC film off the part of the copper foil where it is welded to the copper wire.

[0102] Step 2: Weld one end of the copper foil laminated with the polyethylene film in Step 1 to a copper wire; rotate the copper wire to wind the copper foil and PVC film together, then use a mold to press them tightly so that the diameter after winding is 6.8mm, then put them into a copper tube and dry them. Then, plug both ends of the copper tube with copper rods and weld them to seal, thus forming a copper tube assembly.

[0103] Step 3: The copper tube assembly obtained in Step 2 is drawn in multiple passes with a deformation amount of 5% per pass, at a drawing rate of 1m per minute, until the copper tube assembly is processed to a diameter of 4mm.

[0104] Step 4: Cut off the parts with copper rod plugs welded to both ends of the copper tube assembly after plastic processing in Step 3, and then place it outside the heating zone of the CVD furnace. Evacuate the CVD furnace, and then introduce Ar gas (200 sccm) and H2 gas (100 sccm) to raise the furnace temperature to 800℃. Then, quickly push the part containing the copper tube assembly into the furnace tube heating zone and hold it at that temperature for 5 minutes. After that, turn off the H2 gas, and the copper tube assembly cools down to room temperature in the Ar atmosphere to obtain copper / graphene rods.

[0105] Step 5: The copper / graphene rod obtained in step 4 is further drawn at a rate of 1.0 m / min, with a deformation of about 5% per pass, finally yielding a copper / graphene composite wire with a diameter of 0.8 mm.

[0106] The conductivity of the copper / graphene composite wire was measured using a Keithley power supply voltmeter by the voltmeter-ammeter method, and the conductivity was 93% IACS. The strength of the composite wire was tested using a tensile tester and found to be 650 MPa.

[0107] The parts of this invention not described in detail are well-known to those skilled in the art. The embodiments described above are merely preferred embodiments of the invention, and do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Various modifications and improvements to the technical solutions of this invention made by those skilled in the art without departing from the spirit of the invention should fall within the protection scope defined by the claims of this invention.

Claims

1. A method for preparing copper / graphene composite wires by winding, characterized in that, The method includes the following steps: Step 1: Coat the carbon source evenly on the pretreated copper foil or stack the solid film carbon source with the pretreated copper foil to form a copper-carbon composite. Step 2: Wind the above copper-carbon composite onto a copper wire, then insert it into a copper tube with a matching diameter, and seal both ends with copper rods matching the diameter of the copper tube by welding to form a copper tube assembly. Step 3: Perform plastic processing on the above copper tube assembly, which includes die rolling and / or drawing; Step 4: Cut off both ends of the copper tube assembly after plastic processing in Step 3, place it in a CVD furnace, and grow internal graphene to obtain a copper / graphene rod. Step 5: The copper / graphene rod obtained in Step 4 is further drawn to obtain the copper / graphene composite wire. The copper foil has a thickness of 10-100 µm, the copper wire has a diameter of 0.5-2 mm, and the length of the copper tube is greater than the length of the copper wire, which is greater than the width of the copper foil. The carbon source mentioned in step one is a liquid carbon source or a solid carbon source. The liquid carbon source includes one or more of glucose, paraffin and tetrabutyl titanate. The liquid carbon source is directly coated onto the surface of the copper foil. The solid carbon source includes one or more of polymethyl methacrylate, malic acid, maleic acid, stearic acid and lanthanum acetate. The solid carbon source is uniformly coated onto the surface of copper foil after being dissolved in an organic solvent or melted by heating. The solid film carbon source is a carbon film, and the carbon film includes one or more of polyethylene, polyvinyl chloride and polyvinylidene chloride. In step three, the copper tube assembly is plastically processed, with the total deformation controlled at 50%-80% and the deformation per pass at 5%-15%.

2. The method according to claim 1, characterized in that, Step four involves the specific growth of graphene in the CVD furnace: (1) Place the copper tube assembly after plastic processing in step three outside the heating zone of the CVD furnace tube, evacuate the CVD furnace, and then introduce Ar gas and H2 gas to raise the furnace temperature to 700~1000℃. (2) Push the copper tube assembly into the furnace tube heating zone and keep it warm for 5~30 min; (3) Turn off the H2 gas and let the copper tube assembly cool to room temperature in the Ar atmosphere.

3. The method according to claim 1, characterized in that, The copper foil includes one or more of pure copper foil, copper-nickel alloy foil, copper-molybdenum alloy foil, and copper-tungsten alloy foil.

4. The method according to claim 1, characterized in that, The drawing rate in step five is 1-3 m / min, the deformation per pass is 5%-15%, and the final diameter of the copper / graphene composite wire is 0.05-0.8 mm.

5. The method according to claim 1, characterized in that, The mass percentage of carbon source to copper foil mentioned in step one is between 0.01% and 1%.

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