Copper-based graphene composite wire and preparation method thereof

Abstract

The present invention proposes a copper-based graphene composite wire and its preparation method, which belongs to the field of metal powder processing. The copper-based graphene composite wire comprises copper filaments and a three-dimensional graphene network wrapped around the copper filaments. The copper filaments contain fibrous copper matrix grains oriented along one direction. In the oriented copper matrix grains, <111> The content of texture is ≥60%; the three-dimensional graphene network is an oriented network structure of graphene distributed on the grain boundaries of the copper matrix; the diameter of the copper-based graphene composite wire is 0.01-0.5mm, and the dislocation density is not greater than 10 14 m ‑2 .

Description

Technical Field

[0001] The present invention belongs to the field of metal powder processing, and in particular relates to a copper-based graphene composite wire and a preparation method thereof. Background Art

[0002] Copper microfilaments are the primary material for manufacturing tiny wires and cables. They can be used as bonding wires for electronic packaging, data transmission lines for high-precision instruments, and wires and cables. They are widely used in fields such as electronic communications, artificial intelligence, and aerospace. As electronic components continue to evolve towards miniaturization and integration, higher performance requirements are being placed on copper microfilaments: higher strength, higher conductivity, and high-temperature stability.

[0003] However, the inherent strength of pure copper is insufficient, which limits its industrial application. Traditional preparation and processing technologies have problems such as high wire breakage rate and poor wire diameter consistency, making it difficult to meet the high performance requirements of copper microwires in key areas. Although traditional strengthening methods such as alloying and large plastic deformation can improve the strength of copper materials, they will significantly reduce their functional properties such as conductivity. Therefore, while maintaining functional properties such as high electrical conductivity and thermal conductivity, improving the strength of copper and its alloys and achieving a good match between strength and physical and chemical properties have always been research hotspots and difficulties.

[0004] Graphene, a material with excellent mechanical, electrical, thermal, corrosion, and electromigration properties, is considered an ideal reinforcement for copper-based materials. Graphene / copper composites combine the performance advantages of copper and graphene, exhibiting properties such as high strength and high conductivity, ultra-high electrical conductivity, high thermal conductivity and low expansion, chemical stability, and electromigration resistance. These composites are expected to provide a potential solution to the urgent need for high-performance copper-based materials in integrated circuits and related fields. In related technologies, the main methods for preparing graphene / copper composites are powder metallurgy and chemical vapor deposition. However, the preparation of graphene / copper composite microfilaments based on these methods still faces significant challenges. First, the preparation of wires is typically based on a drawing process under large plastic deformation, and the composite of graphene and a copper matrix introduces complexity into the processing. Second, under large plastic deformation, strength often exhibits an inverse relationship with electrical conductivity and thermal stability.

[0005] Therefore, it is of far-reaching significance to improve the strength of graphene / copper composite microfilaments while maintaining high electrical conductivity and thermal stability to obtain graphene / copper composite microfilaments with good comprehensive performance. Summary of the Invention

[0006] In view of this, in order to solve at least one technical problem in related technologies and other aspects, the present invention proposes a copper-based graphene composite wire, which includes copper filaments and a three-dimensional graphene network wrapped around the copper filaments. The copper filaments contain fibrous copper matrix grains oriented along one direction, and in the oriented copper matrix grains, <111> The content of texture is ≥60%; the three-dimensional graphene network is an oriented network structure of graphene distributed on the grain boundaries of the copper matrix; the diameter of the copper-based graphene composite wire is 0.01-0.5mm, and the dislocation density is not more than 10 14 m -2 .

[0007] According to an embodiment of the present invention, the orientation direction of the copper matrix grains is the drawing deformation direction of the copper wire, and the graphene presents a three-dimensional continuous orientation network structure distributed on the copper matrix grain boundaries along the drawing direction.

[0008] According to an embodiment of the present invention, the mass of the three-dimensional graphene network accounts for 0.01-1.2% of the total mass of the copper-based graphene composite wire.

[0009] According to an embodiment of the present invention, the copper-based graphene composite wire has a strength of 500-1000 MPa, a conductivity of 90-103.5% IACS, and a thermal stability temperature greater than or equal to 600°C.

[0010] In another aspect of the present invention, a method for preparing the aforementioned graphene composite wire is also proposed, comprising: first, mixing a copper precursor powder with a carbon source and performing a heat treatment to obtain a graphene-coated copper matrix powder, wherein the mass fraction of graphene in the graphene-coated copper matrix powder is 0.01-1.2%; then, sintering and pre-deforming the graphene-coated copper matrix powder to obtain a copper-based graphene composite block, wherein the density of the copper-based graphene composite block is greater than 90%; finally, drawing the copper-based graphene composite block to obtain a copper-based graphene composite wire, wherein the diameter of the copper-based graphene composite wire is 0.01-0.5 mm.

[0011] According to an embodiment of the present invention, the carbon source includes any one of a gaseous carbon source, a liquid carbon source, and a solid carbon source. The gaseous carbon source includes any one of methane and acetylene; the liquid carbon source includes any one of n-hexane and glycerol; and the solid carbon source includes any one of glucose, sucrose, paraffin, and polymethacrylate.

[0012] According to an embodiment of the present invention, when the carbon source is a gaseous carbon source or a liquid carbon source, the heat treatment operation includes: mixing the copper precursor powder and the gaseous carbon source or the liquid carbon source in a mixed atmosphere of hydrogen and argon, and reacting at a temperature of 500-700°C for 5-8 minutes. When the carbon source is a solid carbon source, the heat treatment operation includes: first mixing the copper precursor powder with a solution of the solid carbon source, evaporating and drying at 50-90°C to obtain a composite powder; and then reacting the composite powder at a temperature of 500-900°C for 5-60 minutes in a mixed atmosphere of hydrogen and argon.

[0013] According to an embodiment of the present invention, the copper precursor powder has a particle size of 0.5-100 μm and is copper powder or copper alloy powder, wherein the copper content of the copper alloy powder is greater than 95%. The copper alloy powder includes at least one of a copper-silver alloy, a copper-chromium alloy, a copper-tin alloy, a copper-iron alloy, a copper-lanthanum alloy, and a copper-zirconium alloy.

[0014] According to an embodiment of the present invention, in the sintering process, the sintering temperature is 400-1000°C, the sintering time is 0.1-5h, and the sintering pressure is 20-200MPa; in the pre-deformation process, the thermal deformation temperature is 400-1000°C, the single deformation amount is 5-400%, and the cumulative deformation amount is 70-400%.

[0015] According to an embodiment of the present invention, the drawing operation includes: first drawing the copper-based graphene composite block for the first time to obtain a copper-based graphene composite wire with a diameter of 0.1-0.5 mm; wherein, during the first drawing process, the deformation amount of a single drawing pass is 10-20%, and the drawing speed is 0.1-20 m / s; then drawing the copper-based graphene composite wire with a diameter of 0.1-0.5 mm for a second time to obtain a copper-based graphene composite wire with a diameter of 0.01-0.05 mm; wherein, during the second drawing process, the deformation amount of a single drawing pass is 5-10%, and the drawing speed is 5-50 m / s.

[0016] According to an embodiment of the present invention, a unique composite structure is formed by combining fibrous copper matrix grains with a three-dimensional graphene network. Specifically, the fibrous copper matrix grains in the copper filaments are oriented and distributed along one direction (the direction of the drawing deformation) to improve the mechanical strength of the wire. <111> The crystal orientation has higher electrical conductivity and thermal conductivity. By controlling the grain orientation of the copper filament, <111> The texture content reaches over 60%, reducing inelastic electron scattering at grain boundaries and significantly improving the wire's electrical and thermal conductivity. The three-dimensional graphene network uniformly wraps around the copper matrix grains, presenting a continuous, three-dimensional oriented network structure distributed along the copper matrix grain boundaries along the drawing direction. The graphene network distributed at the grain boundaries reduces inelastic electron scattering at the grain boundaries, creating additional electron transport pathways, effectively reducing grain boundary resistance and further improving the wire's overall electrical conductivity. Furthermore, the continuous graphene network limits the growth of the copper matrix grains, thereby improving heat resistance and extending its service life. The copper-based graphene composite material proposed in this invention exhibits high strength (500-1000 MPa), high electrical conductivity (90-103.5% IACS), and high-temperature stability (600°C), surpassing copper and copper alloy wires of comparable dimensions in overall performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the microstructure of the copper-based graphene composite wire in an embodiment of the present invention;

[0018] Figure 2 : are scanning electron microscope images of the copper-based graphene composite wire prepared in Example 1 of the present invention, wherein a is a scanning electron microscope image of the copper-based graphene composite wire with a resolution of 20 μm, b is a scanning electron microscope image of the copper-based graphene composite wire with a resolution of 10 μm, c is a scanning electron microscope image of the copper-based graphene composite wire with a resolution of 5 μm, and d is a scanning electron microscope image of the copper-based graphene composite wire with a resolution of 2 μm;

[0019] Figure 3 1 is a transmission electron micrograph of the copper-based graphene composite wire prepared in Example 1 of the present invention, wherein a is a transmission electron micrograph of a copper-based graphene composite wire with a diameter of 0.5 mm, b is a transmission electron micrograph of a copper-based graphene composite wire with a diameter of 0.05 mm, and c is a transmission electron micrograph of the interface structure between graphene and copper matrix in the copper-based graphene composite wire at a resolution of 10 μm;

[0020] Figure 4 1 is a mechanical tensile curve of the copper-based graphene composite wire and pure copper prepared in Example 1 of the present invention;

[0021] Figure 51 is a graph showing the change in hardness of the copper-based graphene composite wire and pure copper as a function of temperature, as prepared in Example 1 of the present invention;

[0022] Figure 6 1 is a graph showing the change in electrical conductivity of the copper-based graphene composite wire and pure copper as a function of temperature, as prepared in Example 1 of the present invention;

[0023] Figure 7 This is a scanning electron microscope image of the reduced graphene oxide / copper composite wire prepared in Comparative Example 4 of the present invention. DETAILED DESCRIPTION

[0024] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0025] The endpoints of the ranges disclosed herein and any values ​​are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to form one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed in the present invention.

[0026] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the presence of the features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0027] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0028] It should be noted that, unless otherwise defined, technical or scientific terms used in this invention should have the ordinary meanings understood by persons of ordinary skill in the art to which this invention belongs. Where the text refers to descriptions such as "first" and "second," such descriptions are used solely to distinguish similar objects and should not be construed as indicating or implying their relative importance, order of precedence, or implicitly specifying the quantity of the technical features being described. It should be understood that the terms "first" and "second," etc., are interchangeable under appropriate circumstances.

[0029] In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0030] As used herein, the terms "density" and "relative density" mean that a material without any pores is considered to have a density of 100%. In powder metallurgy processes, pores exist between metal powders, so the density is generally less than 100%.

[0031] In recent years, thanks to the rapid development of metal-matrix composites, significant research progress has been made, breaking through the performance bottlenecks of traditional copper and its alloys and initially achieving high strength and high conductivity in the laboratory. Graphene, with its excellent physical and chemical properties, including high strength, low density, high thermal conductivity, and high carrier mobility, coupled with its two-dimensional structure offering rich spatial design possibilities, is considered an ideal reinforcement for copper-matrix composites.

[0032] During the implementation of the present invention, it was found that a three-dimensional graphene network was introduced into the copper matrix, and the excellent performance of graphene was used to make up for the shortcomings of the copper matrix. By controlling the grain orientation of the copper matrix and the distribution of the graphene network, a synergistic effect was formed between the two at the micro and nano scales, and a multi-scale, multifunctional composite structure could be formed. The fibrous copper matrix provides the main conductive and thermal conductive channels, while the graphene network serves as an auxiliary channel and a reinforcing phase to comprehensively improve the performance of the copper microfilaments. The present invention, through the structural design of the copper-based graphene composite material, simultaneously achieves the optimization of multiple properties such as electrical conductivity, thermal conductivity, mechanical strength, and corrosion resistance, closely combines the actual application needs, and meets the higher requirements for material performance in the fields of electronic devices, power transmission, aerospace, etc.

[0033] Figure 1 Schematic diagram of the microstructure of the copper-based graphene composite wire in an embodiment of the present invention.

[0034] The present invention proposes a copper-based graphene composite wire, such as Figure 1 As shown, the copper-based graphene composite wire comprises copper filaments and a three-dimensional graphene network wrapped around the copper filaments. The copper filaments contain fibrous copper matrix grains oriented in one direction. In the oriented copper matrix grains, <111> The texture content is ≥60%; the three-dimensional graphene network is an oriented network structure of graphene distributed on the grain boundaries of the copper matrix.

[0035] According to an embodiment of the present invention, a unique composite structure is formed by combining fibrous copper matrix grains with a three-dimensional graphene network. Specifically, the fibrous copper matrix grains in the copper filaments are oriented and distributed along one direction to improve the mechanical strength of the wire. At the same time, the copper <111> The crystal orientation has higher electrical conductivity and thermal conductivity. By controlling the grain orientation of the copper filament, <111> A texture content exceeding 60% reduces inelastic electron scattering at grain boundaries, significantly improving the wire's electrical and thermal conductivity. A three-dimensional graphene network uniformly wraps around the grain boundaries of the copper matrix. The distributed graphene network at the grain boundaries reduces inelastic electron scattering at the grain boundaries, creating additional electron transport pathways and effectively reducing grain boundary resistance, further enhancing the wire's overall electrical conductivity. Furthermore, the continuous graphene network limits the growth of copper matrix grains, thereby improving heat resistance and extending its service life. The spatial distribution of graphene forms a three-dimensional, continuous, oriented network, oriented along the direction of tensile deformation. The excellent continuity of the graphene is due to the excellent deformation coordination of the graphene network configuration and the preferred processing technology of the present invention. According to embodiments of the present invention, the copper-based graphene composite material proposed in this invention exhibits high strength (500-1000 MPa), high electrical conductivity (90-103.5% IACS), and high-temperature stability (600°C), surpassing copper and copper alloy wires of comparable dimensions in overall performance.

[0036] According to an embodiment of the present invention, the diameter of the copper-based graphene composite wire is 0.01-0.5 mm, for example, it can be 0.01 mm, 0.03 mm, 0.05 mm, 0.08 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, etc., and the dislocation density is not more than 10 14 m -2 .

[0037] According to the embodiments of the present invention, the diameter range of the present invention is conducive to meeting the requirements of modern electronic devices for miniaturization and high integration, especially in applications in high-frequency and high-speed signal transmission. At the same time, it has good flexibility and processability and can adapt to the wiring requirements of complex shapes. The high density of nano twins effectively hinders dislocation movement, thereby improving the strength and hardness of the wire, which is conducive to its application in application scenarios that need to withstand mechanical stress (such as aerospace and automotive industries). At the same time, the nano twin structure also reduces grain boundary scattering, inhibits the initiation and expansion of cracks, thereby reducing resistivity, improving the fatigue resistance of the wire, and extending its service life. Control of dislocation density can optimize the mechanical properties of the wire. A moderate dislocation density can improve the strength and hardness of the material through the dislocation strengthening mechanism. However, too high a dislocation density may lead to increased electron scattering, thereby reducing conductivity, so it is necessary to control the dislocation density.

[0038] According to the embodiments of the present invention, by combining the limitation of the diameter of the copper-based graphene composite wire with the control of the nanotwin density and dislocation density, the present invention can achieve synergistic optimization of performance at the macro, micro and nano scales, which not only improves the electrical conductivity, thermal conductivity, strength and fatigue resistance of the wire, but also gives it significant advantages in miniaturization, high integration and high-end application scenarios.

[0039] According to an embodiment of the present invention, the mass of the three-dimensional graphene network accounts for 0.01-1.2% of the total mass of the copper-based graphene composite wire.

[0040] According to an embodiment of the present invention, the mass fraction of graphene is limited to 0.01-1.2%, and the volume fraction is less than 4%. Within this range, the amount of graphene used can be reduced while ensuring performance improvement, thereby controlling production costs.

[0041] According to an embodiment of the present invention, the copper-based graphene composite wire has a strength of 500-1000 MPa, a conductivity of 90-103.5% IACS, and a thermal stability temperature greater than or equal to 600°C.

[0042] According to embodiments of the present invention, the copper-based graphene composite wire proposed herein can achieve a strength of 500-1000 MPa, significantly exceeding that of pure copper (typically 200-300 MPa). This high strength enables the wire to withstand greater mechanical stress, making it suitable for high-load and high-stress applications. High-strength wires are less susceptible to plastic deformation or breakage during long-term use, significantly extending their service life and reducing maintenance and replacement costs. Their electrical conductivity reaches 90-103.5% IACS, demonstrating that even with the incorporation of graphene, the wire maintains extremely high electrical conductivity. This meets the low resistance and low signal loss requirements of high-frequency electronic devices, making it suitable for high-end applications such as 5G communications and integrated circuits. Their thermal stability temperature is greater than or equal to 600°C, demonstrating that the wire maintains stable performance even in high-temperature environments. This has significant implications for applications in aerospace, the nuclear industry, and high-temperature electronic devices. The structure of the copper-based graphene composite wire proposed in the present invention, by designing the texture orientation of the copper matrix grains and the synergistic effect of the three-dimensional graphene network, enables the wire to perform excellently in mechanical, electrical and thermal properties, and can meet the needs of a variety of high-end applications.

[0043] In another aspect of the present invention, a method for preparing the aforementioned graphene composite wire is also proposed, comprising: first, mixing a copper precursor powder with a carbon source and performing a heat treatment to obtain a graphene-coated copper matrix powder, wherein the mass fraction of graphene in the graphene-coated copper matrix powder is 0.01-1.2%; then, sintering and pre-deforming the graphene-coated copper matrix powder to obtain a copper-based graphene composite block, wherein the density of the copper-based graphene composite block is greater than 90%; finally, drawing the copper-based graphene composite block to obtain a copper-based graphene composite wire, wherein the diameter of the copper-based graphene composite wire is 0.01-0.5 mm.

[0044] According to an embodiment of the present invention, a preparation method successfully produced a copper-based graphene composite wire with excellent performance through heat treatment, sintering, pre-deformation, and drawing. This method not only optimizes the wire's microstructure (such as uniform graphene distribution, fibrous grain orientation, and high density), but also significantly improves the wire's electrical conductivity, thermal conductivity, mechanical strength, thermal stability, and corrosion resistance.

[0045] In some specific embodiments, first, by mixing copper precursor powder with a carbon source and heat treating it, graphene can be evenly coated on the surface of the copper matrix powder. This distribution ensures that graphene can form a continuous three-dimensional network structure in the final wire and is evenly distributed on the grain boundaries of the copper matrix. Then, sintering and pre-deformation are performed to improve the density of the copper-based graphene composite block before drawing to reduce internal defects in the material. Finally, during the drawing process, the grains of the copper matrix form a fibrous orientation distribution along the drawing direction, especially <111> Texture content ≥ 60%. This oriented structure significantly improves the electrical conductivity, thermal conductivity, and mechanical strength of the wire. Furthermore, the graphene exhibits a three-dimensional, continuous oriented network structure distributed along the grain boundaries of the copper matrix along the drawing direction. The number of graphene layers ranges from 1 to 10. Due to the graphene network's ability to coordinate deformation, the copper-based graphene composite wire can be stretched to a diameter of 0.01-0.5mm without intermediate annealing.

[0046] In some specific embodiments, the preparation method further includes performing a reductive pretreatment on the copper precursor powder before the heat treatment. Specifically, the copper precursor powder can be spherical, flaky, or irregular in shape. The copper precursor powder is heated in a tube furnace at 300-400°C for 1-2 hours. During the heating process, a mixture of hydrogen and argon is introduced at a flow rate ratio of (20-100):(20-200) mL / min.

[0047] According to an embodiment of the present invention, the carbon source includes any one of a gaseous carbon source, a liquid carbon source, and a solid carbon source. The gaseous carbon source includes any one of methane and acetylene; the liquid carbon source includes n-hexane and glycerol; and the solid carbon source includes any one of glucose, sucrose, paraffin, and polymethyl methacrylate.

[0048] According to an embodiment of the present invention, when the carbon source is a gaseous carbon source or a liquid carbon source, the heat treatment operation includes: mixing the copper precursor powder and the gaseous carbon source or the liquid carbon source in a mixed atmosphere of hydrogen and argon, and reacting at a temperature of 500-700°C for 5-8 minutes. When the carbon source is a solid carbon source, the heat treatment operation includes: first mixing the copper precursor powder with a solution of the solid carbon source, evaporating and drying at 50-90°C to obtain a composite powder; and then reacting the composite powder at a temperature of 500-900°C for 5-60 minutes in a mixed atmosphere of hydrogen and argon.

[0049] In some specific embodiments, when the carbon source is a gaseous or liquid carbon source, chemical vapor growth can be performed directly on the surface of the copper precursor powder. Specifically, using acetylene gas as an example, a mixture of acetylene, hydrogen, and argon is introduced into a tube furnace containing the copper precursor powder. The tube furnace is then heated to 500-700°C and the reaction is allowed to proceed for 5-8 minutes to obtain a graphene-coated copper substrate powder.

[0050] In some specific embodiments, when the carbon source is a solid carbon source, it is necessary to add a coating process for loading the solid carbon source precursor on the surface of the copper powder. For example, taking sucrose as a solid carbon source as an example, 0.1-2g of sucrose needs to be dissolved in 20-100mL of deionized water and 20-200mL of alcohol to form an alcohol aqueous solution of sucrose. The formation of an alcohol aqueous solution can improve the wettability between sucrose and copper precursor powder, which is beneficial to the subsequent growth of graphene. Subsequently, 15-500g of copper precursor powder is added to the alcohol aqueous solution of sucrose and stirred, heated and evaporated in a water bath at 50-90°C, and then placed in a vacuum oven at 50-90°C for further drying to obtain a composite powder. The composite powder is then placed in a tubular furnace with a powder thickness of 4-6 mm. A mixed gas of hydrogen and argon is introduced at a gas flow ratio of (20-100): (20-200) mL / min. The heating temperature is 500-900°C and the heating time is 5-60 min to obtain a graphene-coated copper matrix powder.

[0051] According to an embodiment of the present invention, the copper precursor powder has a particle size of 0.5-100 μm and is copper powder or copper alloy powder, wherein the copper content of the copper alloy powder is greater than 95%. The copper alloy powder includes at least one of a copper-silver alloy, a copper-chromium alloy, a copper-tin alloy, a copper-iron alloy, a copper-lanthanum alloy, and a copper-zirconium alloy.

[0052] According to an embodiment of the present invention, in the sintering process, the sintering temperature is 400-1000°C, the sintering time is 0.1-5h, and the sintering pressure is 20-200MPa; in the pre-deformation process, the thermal deformation temperature is 400-1000°C, the single deformation amount is 5-400%, and the cumulative deformation amount is 70-400%.

[0053] According to an embodiment of the present invention, during the sintering process, a three-dimensional continuous graphene network is formed by "welding" thousands of graphene-coated copper powders together under the combined effects of pressure and temperature. To further increase the material's density and achieve a size suitable for subsequent drawing, a pre-deformation process is required to produce a copper-based graphene composite block. Selecting the appropriate temperature and deformation amount helps maintain the integrity of the graphene network's three-dimensional structure during the deformation process.

[0054] In some specific embodiments, the sintering process can be any one of cold pressing, hot isostatic pressing, hot pressing, and rapid hot pressing, preferably hot isostatic pressing, hot pressing, and rapid hot pressing. The copper-based graphene composite block density should be greater than 90%, which helps to facilitate subsequent processing deformation and prevent cracking. The pre-deformation process can be one or more of hot forging, hot extrusion, or hot rolling.

[0055] According to an embodiment of the present invention, the drawing operation includes: first drawing the copper-based graphene composite block for the first time to obtain a copper-based graphene composite wire with a diameter of 0.1-0.5 mm; wherein, during the first drawing process, the deformation amount of a single drawing pass is 10-20%, and the drawing speed is 0.1-20 m / s; then drawing the copper-based graphene composite wire with a diameter of 0.1-0.5 mm for a second time to obtain a copper-based graphene composite wire with a diameter of 0.01-0.05 mm; wherein, during the second drawing process, the deformation amount of a single drawing pass is 5-10%, and the drawing speed is 5-50 m / s.

[0056] According to embodiments of the present invention, deformation of a material typically results in strong work-hardening behavior, manifested as an increase in strength and a sharp decrease in machinability. Therefore, during the material's machining and deformation process, especially during drawing processes involving large plastic deformation, annealing is typically performed after a certain amount of deformation to reduce the material's hardness and improve its machinability. This results in increased complexity and cost, and may also cause oxidation of the wire during the process, reducing the material's surface quality and causing a decrease in electrical conductivity. For the copper-based graphene composite wire of the present invention, the three-dimensional continuous graphene network reinforces the copper matrix, thereby forming a copper-based graphene composite material. The graphene network has a good coordination effect on deformation. During deformation, the graphene network can synergistically deform with the copper matrix through its own interlayer slip. This characteristic can greatly improve ductility during drawing, eliminating the need for annealing or other heat treatments during the entire drawing process, greatly improving processing efficiency. Furthermore, due to the self-lubricating effect of the graphene network and the preferred processing technology, the structural integrity of the graphene network can be guaranteed. Ultimately, the graphene network in the composite wire becomes an oriented network distributed along the drawing direction.

[0057] In some specific embodiments, as the drawing process increases the deformation of the copper-based graphene composite wire, the copper-based graphene composite wire <111> The content of copper-based graphene composite wire also shows an increasing trend. Specifically, when the diameter of the copper-based graphene composite wire is 0.1-0.5 mm, <111> The texture content is greater than 60%. When the diameter of the copper-based graphene composite wire is 0.01-0.05mm, <111> The content of texture is greater than 90%.

[0058] The present invention is illustrated below by specific embodiments. It should be noted that the embodiments described are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, other embodiments obtained by ordinary technicians in this field without making creative efforts are all within the scope of protection of the present invention.

[0059] Example 1

[0060] Weigh 0.2g of sucrose and dissolve it in 30mL of deionized water. Stir until the solution is clear, then add 40mL of ethanol and continue stirring to mix thoroughly. Subsequently, add 30g of spherical copper powder with an average particle size of 3-10μm to the sucrose-alcohol aqueous solution and stir in a 75°C water bath until the liquid is completely evaporated. The resulting mixture is placed in a vacuum oven at 70°C for 3 hours to obtain a composite powder. The resulting composite powder is then placed in a graphite ark and reacted at 800°C for 10-15 minutes with a hydrogen flow rate of 200mL / min. After the reaction is completed, the temperature is rapidly cooled to obtain a graphene-coated copper matrix powder.

[0061] 50g of graphene-coated copper matrix powder was weighed and poured into a graphite mold with a diameter of 30mm for hot pressing and sintering. The hot pressing temperature was set to 900℃, the pressure was 50MPa, and the holding time was 1h. Then, it was densified and pre-deformed by hot rolling deformation to achieve a size suitable for drawing deformation. The composite material block was hot rolled at 800℃ to obtain a copper-based graphene composite block. The single rolling amount was 10% and the total rolling amount was 70%. Its composition was tested, and the graphene content in the copper-based graphene composite block was 0.3%, and the relative density was 99.8%.

[0062] The copper-based graphene composite block is roughly drawn to obtain a wire with a diameter (φ) of 0.5 mm, with a deformation of 10% in each pass and a drawing speed of 5 m / s; then the composite wire is processed into a copper-based graphene composite wire with a diameter of 0.05 mm through fine drawing, with a deformation of 8% in each pass and a drawing speed of 20 m / s.

[0063] The morphology of the copper-based graphene composite wire prepared in Example 1 was tested.

[0064] Figure 2 : are scanning electron microscope images of the copper-based graphene composite wire prepared in Example 1 of the present invention, wherein a is a scanning electron microscope image of the copper-based graphene composite wire with a resolution of 20 μm, b is a scanning electron microscope image of the copper-based graphene composite wire with a resolution of 10 μm, c is a scanning electron microscope image of the copper-based graphene composite wire with a resolution of 5 μm, and d is a scanning electron microscope image of the copper-based graphene composite wire with a resolution of 2 μm.

[0065] like Figure 2 As shown in a, the surface of the copper-based graphene composite wire prepared in Example 1 of the present invention is smooth and flat, without obvious scratches and defects caused by processing, which structurally ensures the service life and avoids energy loss when used as a wire. Figure 2 As shown in bd, the three-dimensional graphene network is evenly distributed and completely wraps the fibrous copper matrix grains.

[0066] Figure 3 3 is a transmission electron micrograph of the copper-based graphene composite wire prepared in Example 1 of the present invention, wherein a is a transmission electron micrograph of a copper-based graphene composite wire with a diameter of 0.5 mm, b is a transmission electron micrograph of a copper-based graphene composite wire with a diameter of 0.05 mm, and c is a transmission electron micrograph of the interface structure between graphene and copper matrix in the copper-based graphene composite wire at a resolution of 10 μm.

[0067] like Figure 3As shown in ac in the figure, in the copper-based graphene composite wire, the grains of the copper matrix are elongated along the direction of the drawing deformation and form fibrous grains. Graphene is distributed at the grain boundaries of the copper matrix, showing a continuous network distribution. The interface between the in-situ synthesized graphene and the copper matrix is ​​tightly and cleanly bonded, which helps to improve the strength and electrical conductivity of the copper-based graphene. In addition, a high density of nano twins is found inside the grains of the copper-based graphene composite wire prepared in the present invention, which improves the strength of the material without reducing the electrical conductivity of the material. Specifically, as Figure 3 a and Figure 3 As can be seen from b in FIG, as the deformation increases, the number of nano twins in the copper-based graphene composite wire increases continuously. Further, the mechanical properties, thermal stability, and electrical properties of the copper-based graphene composite wire prepared in Example 1 were tested.

[0068] Figure 4 3 is a mechanical tensile curve diagram of the copper-based graphene composite wire (denoted as graphene / copper, the same below) and pure copper (denoted as pure copper, the same below) prepared in Example 1 of the present invention.

[0069] like Figure 4 As shown, the stress of both materials gradually increases with strain. The copper-based graphene composite wire exhibits a distinct yield plateau after reaching approximately 800 MPa, demonstrating typical plastic deformation characteristics. Pure copper rapidly increases to approximately 450 MPa before breaking. This demonstrates that the copper-based graphene composite wire proposed in this invention exhibits superior mechanical properties. The three-dimensional graphene network, distributed along the grain boundaries of the copper matrix, hinders dislocation motion and facilitates plastic deformation. Furthermore, the excellent interfacial bonding between the graphene and copper matrix alleviates stress concentration and enhances overall strength.

[0070] The hardness of copper-based graphene composite wires and pure copper microwires was tested as a function of temperature after being annealed at different temperatures for 1 hour.

[0071] Figure 5 3 is a graph showing the change in hardness of the copper-based graphene composite wire and pure copper as a function of temperature, as prepared in Example 1 of the present invention.

[0072] like Figure 5 As shown, the thermal stability temperatures of the copper-based graphene composite wire and pure copper microfilament are 600°C and 200°C, respectively, demonstrating the excellent thermal stability of the copper-based graphene composite wire proposed in this invention. The thermal stability temperature is defined as the material's softening resistance, or thermal stability temperature, at which the material retains 80% of its untreated hardness after annealing for one hour.

[0073] The changes in the hardness and electrical conductivity of copper-based graphene composite wires and pure copper microwires with temperature were tested after being annealed at different temperatures for 1 hour.

[0074] Figure 6 3 is a curve diagram showing the change in electrical conductivity of the copper-based graphene composite wire and pure copper as a function of temperature, as prepared in Example 1 of the present invention.

[0075] like Figure 6 As shown, the electrical conductivity of both materials increases first and then decreases with increasing annealing temperature. The difference is that the electrical conductivity of the copper-based graphene composite wire reaches its highest value at 600°C, while that of the pure copper microfilament reaches its highest value at 200°C. The reason for the increase in electrical conductivity of both materials is the decrease in dislocation density after annealing. The different temperature inflection points are due to the different thermal stabilities of the two materials. After annealing at 600°C, the graphene / copper microfilaments can still maintain a fibrous grain structure, while pure copper cannot maintain this grain structure, which increases electron scattering at the grain boundaries and leads to a decrease in electrical conductivity.

[0076] Example 2

[0077] In this embodiment 2, the preparation method of the copper-based graphene composite wire is the same as or similar to that of embodiment 1. The difference from embodiment 1 is that in this embodiment 2, the average particle size of the copper precursor powder is 1-3 μm.

[0078] Example 3

[0079] In this embodiment 3, the preparation method of the copper-based graphene composite wire is the same as or similar to that of embodiment 1. The difference from embodiment 1 is that in this embodiment 3, the average particle size of the copper precursor powder is 10-40 μm.

[0080] Example 4

[0081] In this embodiment 4, the preparation method of the copper-based graphene composite wire is the same as or similar to that of embodiment 1. The difference from embodiment 1 is that the pre-deformation method in this embodiment 4 is hot extrusion. The extrusion temperature is 950° C. and the extrusion ratio is 16:1.

[0082] Example 5

[0083] In this embodiment 5, the preparation method of the copper-based graphene composite wire is the same or similar to that of Example 1. The difference from Example 1 is that the solid carbon source in this embodiment 5 is 0.1 g of sucrose, and the graphene content in the prepared copper-based graphene composite wire is 0.1%.

[0084] Example 6

[0085] In this Example 6, the preparation method of the copper-based graphene composite wire is the same or similar to that in Example 1. The difference from Example 1 is that the solid carbon source in this Example 6 is 0.4 g of sucrose, and the graphene content in the prepared copper-based graphene composite wire is 0.5%.

[0086] Example 7

[0087] In this Example 7, the preparation method of the copper-based graphene composite wire is the same as or similar to that of Example 1. The difference from Example 1 is that the diameter of the copper-based graphene composite wire finally obtained in this Example 7 is 0.5 mm.

[0088] Example 8

[0089] In this embodiment 8, the preparation method of the copper-based graphene composite wire is the same as or similar to that of embodiment 1. The difference from embodiment 1 is that in this embodiment 8, the copper precursor powder is random copper powder.

[0090] Example 9

[0091] In this embodiment 9, the preparation method of the copper-based graphene composite wire is the same as or similar to that of Example 1. The difference from Example 1 is that in this embodiment 9, the copper precursor powder is a copper-silver alloy powder, wherein the silver content is 1% and the copper content is 99%.

[0092] Comparative Example 1

[0093] In Comparative Example 1, the preparation method of the graphene-copper composite material is the same as or similar to that of Example 1. Unlike Example 1, the graphene-copper composite material in Comparative Example 1 is a composite wire with a diameter of 2 mm. During the drawing process, the deformation amount in each pass is 20%, and the drawing speed is 20 m / s.

[0094] Comparative Example 2

[0095] In this comparative example 2, the preparation method of the graphene-copper composite material is the same as or similar to that of Example 1. The difference from Example 1 is that in this comparative example 2, the graphene-copper composite material is a composite wire with a diameter of 1 mm.

[0096] Comparative Example 3

[0097] In this comparative example 3, the preparation method of the graphene-copper-based composite material is as follows, wherein copper exists in the form of copper-lanthanum alloy.

[0098] Take 50g of spherical copper-lanthanum alloy powder (lanthanum content 0.5%, copper content 99.5%) with an average particle size of 3-5μm and spread it flat in a rotary tube furnace. -1 After 1000 Torr, a mixture of acetylene, hydrogen, and argon is introduced in a ratio of 30:20:30 sccm. Acetylene serves as a carbon source. The system is then heated to 500-700°C for 5-8 minutes to deposit graphene on the surface of the copper-lanthanum alloy powder, yielding a graphene / copper-lanthanum alloy composite powder with a graphene content of 0.3%.

[0099] Then, the graphene / copper lanthanum alloy composite powder was processed according to the processing technology in Example 4 to obtain a graphene / copper lanthanum composite wire with a diameter of 0.8 mm.

[0100] Comparative Example 4

[0101] In this comparative example 4, a reduced graphene oxide / copper composite wire was prepared. The preparation method was the same or similar to that in Example 1. The difference from Example 1 was that in this comparative example 4, the carbon source was 0.2 g of graphene oxide nanosheets having a thickness of 5 layers and a planar size of 100-200 nm, and the diameter of the reduced graphene oxide / copper composite wire was 0.5 mm.

[0102] The morphology of the reduced graphene oxide / copper composite wire prepared in Comparative Example 4 was tested.

[0103] Figure 7 This is a scanning electron microscope image of the reduced graphene oxide / copper composite wire prepared in Comparative Example 4 of the present invention.

[0104] like Figure 7 As shown in FIG. 4 , in the composite wire prepared by the external addition method, the graphene exists in the form of graphene sheets. Figure 2 By comparison, it can be seen that the distribution of graphene in the composite wire prepared by the external addition method in Comparative Example 4 is significantly different from that in the composite wire prepared by the in-situ synthesis method in Example 1 of the present invention. The graphene in the composite wire prepared by the external addition method in Comparative Example 4 is scattered in the copper matrix, without the good processability and synergistic improvement of performance brought by the graphene network. At the same time, the graphene / copper composite wire prepared by the external addition method can only be processed to a diameter of 0.5 mm and cannot be further processed into a micro-wire with a diameter of 0.05 mm. Its performance is basically the same as that of pure copper of the same size, and there is no performance improvement.

[0105] The materials prepared in the above Examples 1-9 and Comparative Examples 1-4 were subjected to comprehensive performance tests, and the results are recorded in Table 1 below.

[0106] Table 1

[0107] Strength (MPa) Conductivity (%IACS) Thermal stability (℃) pure copper 460 97.3 200 Example 1 909 99.4 600 Example 2 755 99.4 600 Example 3 680 100 600 Example 4 870 99 600 Example 5 712 100 600 Example 6 762 100 600 Example 7 576 97.6 600 Example 8 608 99 600 Example 9 810 90 500 Comparative Example 1 413 94.5 500 Comparative Example 2 446 95.6 600 Comparative Example 3 333 87.5 400 Comparative Example 4 391 95.8 200

[0108] As shown in Table 1, the copper-based graphene composite wire proposed in the present invention has the characteristics of high strength (500-1000 MPa), high conductivity (90-103.5% IACS) and high-temperature stability (600°C). Its comprehensive performance is higher than that of copper and copper alloy wires / wires of the same size.

[0109] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A copper-based graphene composite wire, characterized in that: The copper-based graphene composite wire comprises: Copper filaments comprising fibrous copper matrix grains oriented in one direction, and The three-dimensional graphene network wrapped on the copper filament is an oriented network structure of graphene distributed three-dimensionally and continuously on the grain boundaries of the copper matrix. Among them, in the oriented copper matrix grains, <111> Texture content ≥90%; The diameter of the copper-based graphene composite wire is 0.01-0.05 mm, and the dislocation density is not greater than 10 14 m -2 , nano twins are distributed in the copper-based graphene composite wire.

2. The copper-based graphene composite wire according to claim 1, characterized in that The mass of the three-dimensional graphene network accounts for 0.01-1.2% of the total mass of the copper-based graphene composite wire.

3. The copper-based graphene composite wire according to claim 1, characterized in that The copper-based graphene composite wire has a strength of 500-1000 MPa, a conductivity of 90-103.5% IACS, and a thermal stability temperature greater than or equal to 600°C.

4. A method for preparing a copper-based graphene composite wire according to any one of claims 1 to 3, characterized in that: The preparation method comprises: Mixing a copper precursor powder with a carbon source and performing heat treatment to obtain a graphene-coated copper matrix powder, wherein the mass fraction of graphene in the graphene-coated copper matrix powder is 0.01-1.2%; The graphene-coated copper matrix powder is sintered and pre-deformed to obtain a copper-based graphene composite block, wherein the density of the copper-based graphene composite block is greater than 90%; in the pre-deformation treatment, the thermal deformation temperature is 400-1000° C., the single deformation amount is 5-400%, and the cumulative deformation amount is 70-400%; Drawing the copper-based graphene composite block to obtain a copper-based graphene composite wire, wherein the copper-based graphene composite wire has a diameter of 0.01-0.05 mm; The drawing operation includes: The copper-based graphene composite block is subjected to a first drawing to obtain a copper-based graphene composite wire having a diameter of 0.1-0.5 mm; wherein, during the first drawing process, the deformation of a single drawing pass is 10-20%, and the drawing speed is 0.1-20 m / s; The copper-based graphene composite wire with a diameter of 0.1-0.5 mm is drawn for a second time to obtain the copper-based graphene composite wire with a diameter of 0.01-0.05 mm; wherein, during the second drawing process, the deformation of a single drawing pass is 5-10%, and the drawing speed is 5-50 m / s.

5. The preparation method according to claim 4, characterized in that The carbon source includes any one of a gaseous carbon source, a liquid carbon source, and a solid carbon source; wherein, The gaseous carbon source includes any one of methane and acetylene; The liquid carbon source includes any one of n-hexane and glycerol; The solid carbon source includes any one of glucose, sucrose, paraffin and polymethyl methacrylate.

6. The preparation method according to claim 5, characterized in that When the carbon source is the gaseous carbon source or the liquid carbon source, the heat treatment operation includes: In a mixed atmosphere of hydrogen and argon, the copper precursor powder and the gaseous carbon source or the liquid carbon source are mixed and reacted at a temperature of 500-700° C. for 5-8 minutes; When the carbon source is the solid carbon source, the heat treatment operation includes: After mixing the copper precursor powder with the solid carbon source solution, evaporating and drying at 50-90° C. to obtain a composite powder; The composite powder is reacted at a temperature of 500-900° C. for 5-60 minutes in a mixed atmosphere of hydrogen and argon.

7. The preparation method according to claim 4, characterized in that The particle size of the copper precursor powder is 0.5-100 μm, and the copper precursor powder is copper powder or copper alloy powder, wherein the copper content in the copper alloy powder is greater than 95%; The copper alloy powder includes at least one of copper-silver alloy, copper-chromium alloy, copper-tin alloy, copper-iron alloy, copper-lanthanum alloy, and copper-zirconium alloy.

8. The preparation method according to claim 4, characterized in that In the sintering process, the sintering temperature is 400-1000° C., the sintering time is 0.1-5 hours, and the sintering pressure is 20-200 MPa.

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