A copper-based graphene composite wire and a preparation process thereof

Abstract

The application provides a copper-based graphene composite wire and a preparation process thereof, and belongs to the field of metal composite materials.The preparation process comprises in-situ growth, ball milling, continuous extrusion, multi-pass continuous extrusion, first annealing treatment, cold drawing and second annealing treatment.The graphene is uniformly distributed in the matrix through the processes of in-situ growth, ball milling, multi-pass continuous extrusion and cold drawing, the size of the graphene in the matrix is between 10nm and 20nm, the average grain size of copper is between 1mu m and 10mu m, the tensile strength is above 550MPa, and the conductivity is above 105%IACS.The application not only improves the conductivity of the copper-based graphene composite wire, but also retains the advantage of continuous processing of the wire.

Description

Technical Field

[0001] This invention provides a copper-based graphene composite wire and its preparation process, relating to the field of metal composite materials. Background Technology

[0002] Copper is widely used in wires, transformer windings, and integrated circuits due to its excellent electrical conductivity and processing properties. However, the conductivity of pure copper is approaching its theoretical limit, and traditional methods can only slightly improve its conductivity, which is insufficient to meet the stringent requirements of high conductivity and low signal loss. Research on the high conductivity of copper-based graphene composites aims to address the urgent need for highly efficient conductive materials. Graphene, as a two-dimensional material, possesses ultra-high carrier mobility, ultra-high thermal conductivity, and mechanical strength, providing a new approach for breakthroughs in the performance of copper-based composites.

[0003] The synergistic effect of graphene and copper can significantly improve the conductivity of composite materials, but practical research faces multiple challenges: weak interfacial bonding between graphene and copper (mainly relying on van der Waals forces), uneven graphene dispersion, structural damage (such as wrinkles and defects) during composite material preparation, and high interfacial contact resistance. In existing preparation methods, Yu Zhang et al. [Zhang Y, Li Y, Li Y, et al. Effect of Graphene Content on Microstructure and Properties of Gr / Cu Composites[C] / / Chinese Materials Conference.2020] used ball milling and hot pressing sintering processes to manufacture copper-based graphene composite materials. Although this method can be mass-produced, graphene agglomerates inside the copper matrix during the hot pressing sintering process, significantly reducing conductivity.

[0004] Therefore, the aforementioned preparation processes for copper-based graphene composite wires are all insufficient to meet the relevant requirements. Summary of the Invention

[0005] To address the bottleneck of limited conductivity improvement or difficulty in balancing mechanical properties and conductivity in existing technologies, this invention provides a copper-based graphene composite wire and its preparation process. This invention uses in-situ growth, ball milling, multi-pass continuous extrusion, cold drawing, and other processes to uniformly distribute graphene in the matrix. This invention not only improves the conductivity of the copper-based graphene composite wire but also retains the advantages of continuous wire processing.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A process for preparing copper-based graphene composite wires, the process comprising in-situ growth, ball milling, continuous extrusion, multi-pass continuous extrusion, first annealing, cold drawing, and second annealing, specifically including the following steps:

[0008] Step 1, in-situ growth:

[0009] Step 1.1: Mix copper powder with carbon precursor and add to solvent to obtain a uniform suspension, wherein the carbon precursor is α-naphthol;

[0010] Step 1.2: Post-process the suspension to obtain copper / α-naphthol powder;

[0011] Step 1.3: The coated copper / α-naphthol powder is placed in a quartz tube furnace and graphitized under an atmosphere of hydrogen and argon at a temperature between 700℃ and 900℃ for a growth time of 2h to 6h to obtain copper / graphene composite powder grown in situ.

[0012] Further, in step 1.1, the solvent is ethanol; the copper powder has a size of 50-500 mesh. After mixing the copper powder with the carbon precursor, the mixture is ultrasonically treated for 20-60 minutes under mechanical stirring at 200-450 rpm to obtain a suspension. The mass fraction of copper powder added to the carbon precursor is 0.4 wt%-6 wt%.

[0013] Furthermore, in step 1.2, the post-processing specifically involves: using a rotary evaporator to treat the material in an oil bath at 130°C for 30-45 minutes to remove the solvent, thereby uniformly coating the carbon precursor onto the surface of the copper particles to obtain copper / α-naphthol powder.

[0014] The second step is ball milling: the in-situ grown copper / graphene composite powder is quantitatively mixed with pure copper powder and ball milled using a stirred ball mill, wherein the mass ratio of copper / graphene composite powder to pure copper powder is 1:1-1:3. This yields mixed granules with a graphene content of 0.1wt%-2.5wt%.

[0015] Furthermore, in the second step, the ball milling time is 1-4 hours, and the ball mill speed is 200-500 rpm.

[0016] Furthermore, in the second step, petroleum ether is added before ball milling to prevent excessive agglomeration of graphene; during ball milling, 99.99% pure argon gas is continuously introduced to prevent copper powder oxidation.

[0017] The third step is continuous extrusion: the continuous extrusion die is placed in a box-type resistance furnace for preheating, the preheated continuous extrusion die is assembled onto the continuous extruder, and the mixed granules are poured into the extrusion cavity of the continuous extruder at a uniform speed of 4r / min-6r / min to obtain copper-based graphene rod blanks with a diameter of 8mm-12mm.

[0018] Furthermore, in the third step, the preheating temperature is 400℃-600℃ and the time is 20min-45min.

[0019] The fourth step is multi-pass continuous extrusion: the continuous extrusion die is placed in a box-type resistance furnace for preheating, and the heat-preserved continuous extrusion die is assembled into a continuous extruder. The copper-based graphene rod obtained in the third step is subjected to multi-pass continuous extrusion, with 3-10 extrusion passes, to obtain copper-based graphene composite wires with a diameter of 2mm-4mm.

[0020] Furthermore, in the fourth step, the preheating temperature is 400℃-600℃ and the time is 20min-45min.

[0021] Step 5, annealing: Place the copper-based graphene composite wire obtained in step 4 into an inert atmosphere annealing furnace for annealing. Argon gas is continuously introduced as a protective gas during annealing. The annealing time is 30-45 minutes and the annealing temperature is 300℃-800℃. After annealing, the furnace is cooled to room temperature.

[0022] Step 6, cold drawing: The annealed copper-based graphene composite wire is assembled onto a cold drawing machine and subjected to multiple cold drawing passes to obtain the copper-based graphene composite wire.

[0023] Furthermore, in the sixth step, the surface of the copper-based graphene composite wire needs to be recoated with drawing lubricant before each cold drawing pass. The cold drawing ratio for each pass is set at 15%-25%, and the total cold drawing processing rate is 50%-99%.

[0024] Step 7, Annealing: The cold-drawn copper-based graphene composite wire is placed in an atmosphere annealing furnace for annealing. Argon gas is continuously introduced as a protective gas during annealing. The annealing time is 15-30 minutes and the annealing temperature is 300℃-800℃. After annealing, the furnace is cooled to room temperature to obtain the copper-based graphene composite wire.

[0025] A copper-based graphene composite wire is prepared using the above-mentioned process through in-situ growth, ball milling, continuous extrusion, multi-pass continuous extrusion, first annealing, cold drawing, and second annealing. It consists of a copper matrix and graphene. The graphene is uniformly distributed in the copper matrix, with the graphene size ranging from 10 nm to 20 nm, and the average copper grain size ranging from 1 μm to 10 μm. The copper-based graphene composite wire has a tensile strength of over 550 MPa and a conductivity of over 105% IACS.

[0026] Compared with the prior art, the preparation process of copper-based graphene composite wire provided by the present invention has the following advantages:

[0027] (1) In this invention, an in-situ growth process is used to form a fine and dispersed three-dimensional graphene conductive network in the copper matrix. The dispersion is further optimized to limit the growth size of graphene to 10-20nm, avoiding stress concentration or folding defects caused by excessively large sheets. Compared with traditional copper base materials, its conductivity is improved by 5%-10%.

[0028] (2) This invention uses a multi-pass continuous extrusion process. During each extrusion pass, the copper matrix undergoes intense plastic deformation and dynamic recrystallization, resulting in elongated grains (1μm-10μm). Simultaneously, the graphene at the copper grain boundaries forms a specific orientation. This significantly improves the mechanical properties of the copper matrix compared to traditional copper matrix materials.

[0029] (3) The present invention has the advantages of continuous production, uniform feeding and extrusion speed, combined with continuous extrusion die preheating and uniform feeding, to ensure continuous and stable process, suitable for large-scale industrial production, and reduce energy consumption and cost. Attached Figure Description

[0030] Figure 1 Metallographic image of Example 1: Metallographic image of copper-based graphene composite material.

[0031] Figure 2 Metallographic image of Example 1: Metallographic image of copper-based graphene composite material.

[0032] Figure 3 Metallographic image of Example 1: Metallographic image of copper-based graphene composite material. Detailed Implementation

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are only some embodiments of the present invention, and not all embodiments.

[0034] Example 1

[0035] This invention provides a low-energy-consumption continuous preparation method for copper-based graphene composite materials, the method comprising the following steps:

[0036] (1) Mix 1 kg of 50 mesh copper powder with 4 g of α-naphthol and add it to 0.9 L of anhydrous ethanol. Under mechanical stirring at 200 r / min, the mixture is ultrasonically treated for 60 min. Then, it is treated in an oil bath at 130 °C for 30 min using a rotary evaporator to remove the ethanol. The powder is placed in a quartz tube furnace and graphitized under the atmosphere of hydrogen and argon. The hydrogen flow rate is 30 mL / min, the argon flow rate is 70 mL / min, the temperature is 900 °C, and the growth time is 2 h to obtain copper / graphene composite powder grown in situ.

[0037] (2) The copper / graphene composite powder grown in situ and 1 kg of 200 mesh pure copper powder were ball-milled in a stirred ball mill. Petroleum ether was added during the ball milling to prevent excessive agglomeration of graphene. The ball milling time was 1 hour and the ball mill speed was 500 rpm. Argon gas with a purity of 99.99% was continuously introduced during the ball milling process to prevent the copper powder from oxidizing, and mixed granules were obtained.

[0038] (3) Place the continuous extrusion die into a box-type resistance furnace for preheating. The preheating temperature is 400℃ and the time is 45min. After preheating, assemble the die onto the continuous extruder. Pour the mixed granules into the extrusion cavity of the continuous extruder at a uniform speed. The extrusion speed is 6r / min to obtain a copper-based graphene rod blank with a diameter of 8mm.

[0039] (4) After all the mixed granules are extruded, the rod blank is directly subjected to multiple continuous extrusions. The extrusion ratio of the second pass is 1:1 and the extrusion ratio of the third pass is 3:1 to obtain a copper-based graphene composite wire with a diameter of 3.5 mm. After extrusion, the wire is placed in pure water to cool to room temperature.

[0040] (5) Place the copper-based graphene composite wire into an atmosphere annealing furnace for annealing. Argon gas is continuously introduced as a protective gas during annealing. The annealing time is 30 minutes and the annealing temperature is 800℃. After annealing, the furnace is cooled to room temperature.

[0041] (6) The annealed copper-based graphene composite wire is assembled onto a cold drawing machine and cold drawn in one pass. Before each cold drawing, the surface of the copper-based graphene composite wire needs to be recoated with wire drawing lubricant. The cold drawing ratio for each pass is set at 25% to obtain a copper-based graphene composite wire with a diameter of 2.5 mm.

[0042] (7) Annealing: The cold-drawn copper-based graphene composite wire is placed in an atmosphere annealing furnace for annealing. Argon gas is continuously introduced as a protective gas during annealing. The annealing time is 30 minutes and the annealing temperature is 300℃. After annealing, the furnace is cooled to room temperature to obtain the copper-based graphene composite wire.

[0043] Example 2

[0044] (1) Mix 1 kg of 200-mesh copper powder with 60 g of carbon precursor α-naphthol and add it to 0.9 L of ethanol. Stir in a mechanical stirrer (450 r / min) for 20 min, and simultaneously sonicate for 20 min to form a uniform suspension. Treat in a 130 °C oil bath using a rotary evaporator for 45 min to remove ethanol, and obtain copper / α-naphthol powder uniformly coated with carbon precursor. Place the powder in a quartz tube furnace, introduce hydrogen and argon (volume ratio 1:3), heat to 700 °C and hold for 6 h to complete in-situ graphene growth, and obtain copper / graphene composite powder.

[0045] (2) Add 3 kg of 200 mesh pure copper powder and petroleum ether to the composite powder, place it in a stirred ball mill, and ball mill at 350 rpm for 3 hours. 99.99% argon gas is introduced throughout the process to obtain uniformly mixed granules.

[0046] (3) Place the continuous extrusion die in a box-type resistance furnace and preheat it to 500°C. Keep it at that temperature for 30 minutes. Add the mixed granules into the cavity of the continuous extruder at a uniform speed. Set the extrusion speed to 5 r / min to obtain a copper-based graphene rod blank with a diameter of 9 mm.

[0047] (4) The mold and the rod blank are preheated to 500℃ and kept at that temperature for 30 minutes. The mold is then assembled into a continuous extruder to extrude the rod blank in four consecutive passes with a compression ratio of 1.5:1 for each pass, finally yielding a copper-based graphene composite wire with a diameter of 2.75 mm.

[0048] (5) Place the copper-based graphene composite wire into an atmosphere annealing furnace for annealing. Argon gas is continuously introduced as a protective gas during annealing. The annealing time is 40 minutes and the annealing temperature is 600℃. After annealing, the furnace is cooled to room temperature.

[0049] (6) Cold drawing: The annealed copper-based graphene composite wire is assembled onto a cold drawing machine and subjected to two cold drawing passes. Before each cold drawing pass, the surface of the copper-based graphene composite wire needs to be re-coated with wire drawing lubricant. The cold drawing ratio for each pass is set at 15%, resulting in a copper-based graphene composite wire with a diameter of 1.75 mm.

[0050] (7) Annealing: The cold-drawn copper-based graphene composite wire is placed in an atmosphere annealing furnace for annealing. Argon gas is continuously introduced as a protective gas during annealing. The annealing time is 15 minutes and the annealing temperature is 800℃. After annealing, the furnace is cooled to room temperature to obtain the copper-based graphene composite wire.

[0051] Example 3

[0052] (1) Mix 1 kg of 100-mesh copper powder with 30 g of carbon precursor α-naphthol and add it to 0.9 L of ethanol. Stir in a mechanical stirrer (300 r / min) for 30 min, and simultaneously sonicate for 40 min to form a uniform suspension. Treat in a rotary evaporator in an oil bath at 130 °C for 35 min to remove ethanol, and obtain copper / α-naphthol powder uniformly coated with carbon precursor. Place the powder in a quartz tube furnace, introduce hydrogen and argon (volume ratio 1:3), heat to 800 °C and hold for 5 h to complete in-situ graphene growth, and obtain copper / graphene composite powder.

[0053] (2) Add 3 kg of 200 mesh pure copper powder and petroleum ether to the composite powder, place it in a stirred ball mill, and ball mill at 200 rpm for 4 hours. 99.99% argon gas is introduced throughout the process to obtain uniformly mixed granules.

[0054] (3) Place the continuous extrusion die in a box-type resistance furnace and preheat it to 600°C. Keep it at that temperature for 20 minutes. Add the mixed granules into the cavity of the continuous extruder at a uniform speed. Set the extrusion speed to 5 r / min to obtain a copper-based graphene rod blank with a diameter of 12 mm.

[0055] (4) The mold and the rod blank are preheated to 500℃ and kept at that temperature for 30 minutes. The mold is then assembled into a continuous extruder to extrude the rod blank in four consecutive passes with a compression ratio of 1.5:1 for each pass, finally yielding a copper-based graphene composite wire with a diameter of 2.5 mm.

[0056] (5) Place the copper-based graphene composite wire into an atmosphere annealing furnace for annealing. Argon gas is continuously introduced as a protective gas during annealing. The annealing time is 45 minutes and the annealing temperature is 300℃. After annealing, the furnace is cooled to room temperature.

[0057] (6) Cold drawing: The annealed copper-based graphene composite wire is assembled onto a cold drawing machine and subjected to two cold drawing passes. Before each cold drawing pass, the surface of the copper-based graphene composite wire needs to be recoated with wire drawing lubricant. The cold drawing ratio for each pass is set at 15%, resulting in a copper-based graphene composite wire with a diameter of 2mm.

[0058] (7) Annealing: The cold-drawn copper-based graphene composite wire is placed in an atmosphere annealing furnace for annealing. Argon gas is continuously introduced as a protective gas during annealing. The annealing time is 20 minutes and the annealing temperature is 600℃. After annealing, the furnace is cooled to room temperature to obtain the copper-based graphene composite wire.

[0059] The embodiments described above are merely illustrative of the implementation methods of the present invention, but should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A preparation process for copper-based graphene composite wires, characterized in that, The preparation process includes in-situ growth, ball milling, continuous extrusion, multi-pass continuous extrusion, first annealing, cold drawing, and second annealing. Specifically... Includes the following steps: Step 1, in-situ growth: Step 1.1: Mix copper powder with carbon precursor and add to solvent to obtain a uniform suspension, wherein the carbon precursor is α-naphthol; Step 1.2: Post-process the suspension to obtain copper / α-naphthol powder; Step 1.3: Place copper / α-naphthol powder into a quartz tube furnace and perform graphitization treatment in an atmosphere of hydrogen and argon at a temperature between 700℃ and 900℃ for a growth time of 2h to 6h to obtain copper / graphene composite powder grown in situ. The second step is ball milling: the in-situ grown copper / graphene composite powder is mixed with pure copper powder and then ball-milled to obtain mixed granules with a graphene content of 0.1wt%-2.5wt%; the mass ratio of the copper / graphene composite powder to the pure copper powder is 1:1-1:3; the ball milling time is 1h-4h, and the ball mill speed is 200rpm-500rpm; petroleum ether is added before ball milling to prevent excessive graphene agglomeration; 99.99% pure argon gas is continuously introduced during the ball milling process to prevent copper powder oxidation; The third step is continuous extrusion: the mixed granules are poured into the extrusion cavity of the continuous extruder at a uniform speed to obtain copper-based graphene rod blanks; the continuous extruder in the third step is preheated before use; the preheating temperature is 400℃-600℃ and the time is 20min-45min. Step 4, multi-pass continuous extrusion: The copper-based graphene rod blank obtained in step 3 is subjected to multi-pass continuous extrusion using a continuous extrusion die to obtain copper-based graphene composite wire; the continuous extrusion press in step 4 is preheated before use; the preheating temperature is 400℃-600℃ and the time is 20min-45min. Step 5, First Annealing: Under an inert atmosphere, the copper-based graphene composite wire obtained in Step 4 is annealed; during the annealing, argon gas is continuously introduced as a protective gas, the annealing time is 30min-45min, and the annealing temperature is 300℃-800℃. Step 6, cold drawing: The annealed copper-based graphene composite wire is assembled onto a cold drawing machine and subjected to multiple cold drawing passes to obtain the copper-based graphene composite wire. Step 7, Second Annealing: Under an inert atmosphere, the copper-based graphene composite wire obtained in Step 6 is annealed to obtain the copper-based graphene composite wire.

2. The preparation process of a copper-based graphene composite wire according to claim 1, characterized in that, In the first step: In step 1.1, the solvent is ethanol; the copper powder has a size of 50-500 mesh; and the mass fraction of copper powder added to the carbon precursor is 0.4wt%-6wt%. In step 1.2, the post-processing specifically involves: using a rotary evaporator to treat the material in an oil bath at 130°C for 30-45 minutes to remove the solvent, thereby uniformly coating the carbon precursor onto the surface of the copper particles to obtain copper / α-naphthol powder.

3. The preparation process of a copper-based graphene composite wire according to claim 1, characterized in that, In the third step, the continuous extruder is preheated before use; the extrusion speed is 4r / min-6r / min; in the fourth step, the continuous extruder is preheated before use, and the number of extrusion passes is 3-10.

4. The preparation process of a copper-based graphene composite wire according to claim 1, characterized in that, In the sixth step, the surface of the copper-based graphene composite wire needs to be recoated with drawing lubricant before each cold drawing pass. The cold drawing ratio for each pass is set at 15%-25%, and the total cold drawing processing rate is 50%-99%.

5. The preparation process of a copper-based graphene composite wire according to claim 1, characterized in that, In the seventh step, argon gas is continuously introduced as a protective gas during the second annealing, the annealing time is 15 min-30 min, and the annealing temperature is 300℃-800℃.

6. A copper-based graphene composite wire, characterized in that, The copper-based graphene composite wire is prepared using any one of the preparation processes described in claims 1-5, and is composed of a copper matrix and graphene, with the graphene uniformly distributed in the copper matrix.

7. The copper-based graphene composite wire according to claim 6, characterized in that, The graphene in the copper matrix has a size between 10nm and 20nm, and the average copper grain size is between 1μm and 10μm; the copper-based graphene composite wire has a tensile strength of over 550MPa and a conductivity of over 105%IACS.

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