High-temperature-resistant copper / graphene composite wire and preparation method and application thereof

Abstract

The invention relates to the field of copper-based composite materials, and discloses a high-temperature-resistant copper / graphene composite wire and a preparation method and application thereof. The preparation method provided by the invention comprises the following steps: S1, by taking a dispersion strengthened copper wire as a processing object, growing graphene on the surface of the dispersion strengthened copper wire to prepare a composite unit; s2, bundling and assembling a plurality of composite units prepared in the step S1 to obtain an assembly, then loading the assembly into a dispersion strengthened copper pipe, carrying out vacuum sealing on two ends, and then carrying out plastic deformation treatment and intermediate annealing treatment to prepare a multi-core composite wire; s3, taking the multi-core composite wire prepared in S2 as a new processing object, and repeatedly executing S1 and S2 to obtain a composite wire; and S4, carrying out annealing treatment on the composite wire rod finally obtained in the step S3 to obtain the high-temperature-resistant copper / graphene composite wire. According to the copper / graphene composite wire prepared through the preparation method, collaborative optimization of high temperature resistance, high strength and high conductivity is achieved.

Description

Technical Field

[0001] This invention relates to the field of copper-based composite materials, specifically to a high-temperature resistant copper / graphene composite wire, its preparation method, and its application. Background Technology

[0002] In high-temperature, high-load applications such as resistance welding electrodes, high-energy physics devices, and nuclear fusion components, traditional dispersion-strengthened copper materials, represented by Al2O3 / Cu and Y2O3 / Cu, play an irreplaceable role. In these materials, the highly stable ceramic dispersion phase significantly increases the recrystallization temperature and high-temperature strength of the copper matrix through dislocation pinning and grain boundary mechanisms, but severely disrupts the conductive continuity of the copper matrix. These insulating dispersion phases become electron scattering centers, leading to a significant decrease in the material's conductivity, far below the 100% IACS of pure copper, making it difficult to meet the urgent demand for low-energy transmission in high-power-density electrical equipment.

[0003] To resolve this contradiction, graphene is considered an ideal reinforcement. Its theoretical strength reaches 130 GPa, and its carrier mobility is several orders of magnitude higher than copper, theoretically allowing for improved strength while maintaining high conductivity. However, existing fabrication techniques for copper / graphene composite wires all suffer from significant bottlenecks:

[0004] (1) Powder metallurgy route: Whether it is mechanical mixing or in-situ growth, nanoscale graphene is very easy to agglomerate in copper matrix, forming micro-defects, which not only leads to the attenuation of the enhancement effect, but also becomes the center of electron and phonon scattering, which seriously restricts the improvement of electrical and thermal conductivity.

[0005] (2) Surface CVD route: Graphene can be grown on the surface of pure copper by chemical vapor deposition (CVD). Although it can avoid agglomeration and obtain a high-quality interface, the high temperature (usually ≥1000℃) heat treatment required for this process will cause significant coarsening of the reinforcing phase (such as Al2O3, Y2O3) in the dispersion-strengthened copper, which will drastically weaken its pinning effect and lead to a significant decrease in the strength of the matrix, which is contrary to the original intention of introducing graphene.

[0006] Therefore, existing technologies lack a composite material system and feasible preparation method that can simultaneously and synergistically optimize the three properties of "high temperature resistance, high strength, and high conductivity." Developing a new material and process that can circumvent the above-mentioned shortcomings and achieve synergistic performance improvement has become a pressing technical challenge in this field. Summary of the Invention

[0007] Therefore, the technical problem to be solved by the present invention is to overcome the defect that the existing preparation process is difficult to achieve the synergistic optimization of "high temperature resistance-high strength-high conductivity" of copper / graphene composite wires, thereby providing a high temperature resistant copper / graphene composite wire, its preparation method and application.

[0008] Therefore, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for preparing a high-temperature resistant copper / graphene composite wire, comprising the following steps: S1. Using dispersion-strengthened copper wire as the processing object, graphene is grown on the surface of the dispersion-strengthened copper wire to obtain a composite unit; S2. Assemble multiple composite units obtained from S1 into a bundle to obtain an assembly. Then, insert the assembly into a dispersion-strengthened copper tube and vacuum seal both ends. Then, perform plastic deformation treatment and intermediate annealing treatment to obtain a multi-core composite wire. S3. Using the multi-core composite wire obtained in S2 as the new processing object, repeat S1 and S2 to obtain the composite wire; The number of repetitions k ≥ 1, and the processing object for each repetition is the multi-core composite wire obtained in the previous repetition; S4. Anneal the composite wire finally obtained in S3 to obtain the high-temperature resistant copper / graphene composite wire.

[0009] In an optional embodiment, in the step of assembling the composite units obtained by multiple S1 strands in a bundle, the number of composite units is at least 2 strands; the composite unit uses dispersion-strengthened copper as the carrier substrate and surface graphene as the conductive reinforcement layer. In an optional implementation, the bundle assembly in S2 is a process of combining, binding, fixing, and finally encapsulating multiple independent graphene-grown, dispersed reinforced copper wires in a hexagonal close-packed arrangement to form an assembly.

[0010] In one optional embodiment, the materials of the dispersion-strengthened copper wire in S1 and the dispersion-strengthened copper tube in S2 are each independently selected from at least one of alumina dispersion-strengthened copper, yttrium oxide dispersion-strengthened copper, and titanium diboride dispersion-strengthened copper. Before use, the dispersion-strengthened copper wire in S1 and the dispersion-strengthened copper tube in S2 are pretreated. The pretreatment process includes grinding and cleaning the outer and inner surfaces of the dispersion-strengthened copper tube and the surface of the dispersion-strengthened copper wire in sequence, and then performing the first heat treatment respectively. And / or, the number of times k is repeated in S3 is 2-5 times.

[0011] In one alternative implementation, the polishing is mechanical polishing, and the sandpaper used for polishing has a grit of 1000-5000.

[0012] In one optional implementation, the cleaning method includes at least one of ultrasonic cleaning and acid washing; Optionally, the solvent for ultrasonic cleaning includes one of acetone and ethanol; Optionally, the pickling reagent includes hydrochloric acid solution; Optionally, the hydrochloric acid solution has a mass fraction of 5%-15%; Optionally, the pickling time is 5-30 minutes.

[0013] In an optional embodiment, the first heat treatment step is carried out in a mixed atmosphere of hydrogen and argon, wherein the volume ratio of hydrogen to argon is (5-20):(80-95); the temperature of the first heat treatment is 600-920°C, and the time is 30-60 min.

[0014] In one alternative embodiment, the plastic deformation process in S2 includes at least one of forging, extrusion, rolling, and drawing; The total deformation amount of the plastic deformation treatment in S2 is ≥90%, and the deformation amount per pass is ≤15%; the deformation amount per pass of the plastic deformation treatment refers to the deformation amount of each forging, extrusion, rolling or drawing. The total deformation amount of the plastic deformation treatment refers to the cumulative deformation amount of all passes, i.e., the change rate of copper tube area. The intermediate annealing process in S2 is carried out at a temperature of 300℃-800℃ for a time of 10min-60min; the intermediate annealing refers to the annealing process performed when the cumulative deformation reaches 50-70% of the outer diameter of the copper tube. The cross-sectional area of ​​the assembly in S2 accounts for ≥60% of the inner diameter area of ​​the dispersion-strengthened copper tube.

[0015] In an optional implementation, the process of vacuum sealing both ends in S2 includes: vacuum welding both ends of the dispersion-strengthened copper tube.

[0016] In one alternative implementation, rolling is a roll pass rolling.

[0017] In one optional embodiment, the diameter of the dispersion-strengthened copper wire in S1 is 0.05mm-1mm; the inner diameter of the dispersion-strengthened copper tube in S2 is 3-28mm, and the wall thickness is 0.5-2.5mm.

[0018] In one optional implementation, the process of growing graphene on the surface of the dispersion-reinforced copper wire in S1 includes: In a first reducing atmosphere, graphene is grown on the surface of a dispersion-strengthened copper wire by applying a gaseous carbon source to it via chemical vapor deposition. Alternatively, under a second reducing atmosphere, graphene can be grown after coating a liquid carbon source onto the surface of a dispersion-strengthened copper wire.

[0019] In one optional embodiment, the method for preparing the high-temperature resistant copper / graphene composite wire satisfies at least one of the following conditions: (1) The first reducing atmosphere includes hydrogen and argon; Optionally, in the first reducing atmosphere, the standard volume flow rate ratio of hydrogen to argon is (10-50):(100-500). (2) The gaseous carbon source includes methane; (3) The standard volume flow rate ratio of the first reducing atmosphere and the gaseous carbon source is (110-550):(1-10); the standard volume flow rate represents the volume flow rate of the gas under standard conditions (usually at a temperature of 0°C and a pressure of 1 standard atmosphere); (4) The growth temperature of graphene grown using gaseous carbon source is 800-1030℃ and the growth time is 30-60min; (5) The second reducing atmosphere includes hydrogen and argon; Optionally, in the second reducing atmosphere, the standard volume flow rate ratio of hydrogen to argon is (10-100):(100-500). (6) The liquid carbon source includes a carbon source that is liquid at room temperature or a carbon source that is liquid after being dissolved in a solvent; Optionally, the liquid carbon source includes at least one of paraffin, oleic acid, naphthol, and glucose; Optionally, the solvent includes at least one of water and ethanol; (7) The growth temperature of graphene grown using the liquid carbon source is 600-1000℃ and the time is 30-60min.

[0020] In one optional embodiment, the annealing temperature in S4 is 300-500°C and the time is 10-60 min; And / or, S4 further includes a drawing step of the composite wire prior to annealing; Optionally, a second heat treatment step may be included before the drawing step; Optionally, the temperature of the second heat treatment is 600-800℃ and the time is 30min-1h.

[0021] Secondly, the present invention provides a high-temperature resistant copper / graphene composite wire, which is prepared according to the preparation method of the high-temperature resistant copper / graphene composite wire.

[0022] In one optional embodiment, the high-temperature resistant copper / graphene composite wire has a softening temperature ≥850℃, a conductivity ≥81%IACS, and a tensile strength ≥680MPa.

[0023] Thirdly, the present invention provides an application of the high-temperature resistant copper / graphene composite wire in the fields of drone motors, high-speed generators for aerospace, new energy vehicles, and high-end electronic devices.

[0024] The technical solution of this invention has the following advantages: 1. The method for preparing high-temperature resistant copper / graphene composite wire provided by the present invention includes the following steps: S1. Using dispersion-reinforced copper wire as the processing object, graphene is grown on the surface of the dispersion-reinforced copper wire to obtain a composite unit; S2. Multiple composite units obtained in S1 are bundled and assembled to obtain an assembly, and then the assembly is placed into a dispersion-reinforced copper tube and vacuum-sealed at both ends, followed by plastic deformation treatment and intermediate annealing treatment to obtain a multi-core composite wire; S3. Using the multi-core composite wire obtained in S2 as a new processing object, S1 and S2 are repeated to obtain a composite wire; the number of repetitions k≥1 times, and the processing object for each repetition is the multi-core composite wire obtained in the previous repetition; S4. The composite wire finally obtained in S3 is annealed to obtain the high-temperature resistant copper / graphene composite wire.

[0025] This invention employs multiple bundled processing steps to refine the coarsened reinforcing phase during graphene growth through large plastic deformation. The graphene thins and fractures along the drawing direction, resulting in a spatially differentiated and synergistic composite structure between the dispersed reinforcing phase and graphene within the conductor: the dispersed reinforcing phase is primarily distributed within the grains to ensure matrix strength and thermal stability, while the graphene is mainly distributed at the grain boundaries formed by deformation to construct highly efficient conductive channels. This invention utilizes a process combining dispersed reinforcing copper surface graphene growth with bundled assembly and plastic deformation treatment. This ensures the uniform distribution of the dispersed reinforcing phase within the grains, while simultaneously aligning the graphene along the elongated grain boundaries, thereby obtaining a high-temperature resistant copper / graphene composite conductor that possesses high conductivity, high strength, and excellent high-temperature thermal stability. Furthermore, this invention features a simple process, is easy to mass-produce, and has promising application prospects in aerospace, drones, electronics and microelectronics, new energy, and power systems.

[0026] 2. The cross-sectional area of ​​the assembly in S2 accounts for ≥60% of the inner diameter area of ​​the dispersion-strengthened copper tube.

[0027] The higher the density of the composite, the more copper wires inside, and the more graphene grown on the surface of the copper wires. This configuration ensures the density of the material and the graphene content.

[0028] 3. The total deformation amount of the plastic deformation treatment is ≥90%.

[0029] The beneficial effects of this setup are as follows: high-strain deformation treatment promotes the fragmentation and uniform dispersion of dispersed phases (such as alumina and yttrium oxide), forming submicron-scale reinforcing phases and improving the strength of the conductor; simultaneously, the high-density dislocations accumulated during plastic deformation treatment work synergistically with the dispersed phase to form a multi-scale strengthening mechanism, breaking through the strength limit; furthermore, the large deformation induces strong interfacial bonding between the copper matrix and the dispersed phase, driving the graphene to align along the elongated grain boundaries. Both work together to pin the grain boundaries, effectively suppressing high-temperature grain coarsening, increasing the softening temperature of the conductor, and the oriented graphene provides channels for electron transport, improving the conductivity of the conductor. Attached Figure Description

[0030] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0031] Figure 1 A metallographic microscope image of the cross-sectional metallographic structure of the high-temperature resistant copper / graphene composite wire of Embodiment 1 of the present invention; Figure 2 This is the Raman spectrum of graphene grown on the surface of alumina dispersion-reinforced copper wire in Example 1 of the present invention. Detailed Implementation

[0032] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0033] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0034] Example 1 This embodiment provides a method for preparing a high-temperature resistant copper / graphene composite wire, including the following steps: Pretreatment steps: Take an alumina dispersion-strengthened copper tube with an outer diameter of 4mm, an inner diameter of 3mm, a length of 30cm, and a wall thickness of 0.5mm (the mass fraction of alumina in the alumina dispersion-strengthened copper tube is 0.7%) and an alumina dispersion-strengthened copper wire with a diameter of 0.95mm and a length of 30cm (the mass fraction of alumina in the alumina dispersion-strengthened copper wire is 0.7%). The outer and inner surfaces of the alumina dispersion-strengthened copper tube and the surface of the alumina dispersion-strengthened copper wire are mechanically polished (using 2000-grit sandpaper) and ultrasonically cleaned (using ethanol as solvent, 200W power, and 20min time) respectively. Then, the obtained alumina dispersion-strengthened copper tube and copper wire are subjected to the first heat treatment. The first heat treatment is carried out in a mixed atmosphere of hydrogen and argon (the volume ratio of hydrogen to argon is 20:80), at a temperature of 600℃ for 60min, thus completing the pretreatment of the alumina dispersion-strengthened copper tube and alumina dispersion-strengthened copper wire.

[0035] S1. Using methane as the carbon source, graphene was grown on the surface of pretreated alumina dispersion-reinforced copper wire by chemical vapor deposition in a mixed atmosphere of hydrogen and argon (the standard volume flow rates of hydrogen, argon and methane were 50 sccm, 500 sccm and 10 sccm, respectively). The growth temperature was set to 1000℃ and the time was 30 min to obtain the composite unit.

[0036] S2. Assemble the 7 composite units obtained in S1 into a bundle to obtain an assembly. Insert the assembly into the pre-treated alumina dispersion-strengthened copper tube (the cross-sectional area of ​​the assembly accounts for 70.1% of the inner cross-sectional area of ​​the alumina dispersion-strengthened copper tube). Vacuum weld both ends and then perform multi-pass die rolling. Set the deformation amount per pass to 5%. After die rolling, a wire with a diameter of 2 mm is obtained. Then, perform intermediate annealing treatment. Set the intermediate annealing temperature to 300℃ and the time to 60 min. Then, perform multi-pass drawing. Set the deformation amount per pass to 10%. After drawing, a multi-core composite wire with a diameter of 0.95 mm is obtained.

[0037] S3. Using a multi-core composite wire with a diameter of 0.95mm as the new processing object, repeat steps S1 and S2 above, repeating the process k=1 times, to obtain a composite wire with a diameter of 0.95mm.

[0038] S4. The composite wire with a diameter of 0.95 mm obtained in S3 is subjected to a second heat treatment (800℃, 30 min) and then drawn to a diameter of 0.05 mm to obtain a composite wire with a diameter of 0.05 mm.

[0039] S5. The composite wire with a diameter of 0.05 mm from S4 is annealed at 300℃ for 30 min to obtain a high-temperature resistant copper / graphene composite wire.

[0040] Example 2 In this embodiment, step S3 repeats steps S1 and S2 twice (each time the processing object is the multi-core composite wire obtained in the previous repetition), and the other steps are the same as in embodiment 1.

[0041] Example 3 In this embodiment, step S3 repeats steps S1 and S2 three times (each time the processing object is the multi-core composite wire obtained in the previous repetition), and the other steps are the same as in embodiment 1.

[0042] Example 4 In this embodiment, step S3 repeats steps S1 and S2 a total of 4 times (each time the processing object is the multi-core composite wire obtained in the previous repetition), and the other steps are the same as in embodiment 1.

[0043] Example 5 In this embodiment, step S3 repeats steps S1 and S2 a total of 5 times (each repetition involves processing the multi-core composite wire obtained in the previous repetition), and the other steps are the same as in embodiment 1.

[0044] Example 6 This embodiment provides a method for preparing a high-temperature resistant copper / graphene composite wire, including the following steps: Pre-treatment steps: Take an alumina dispersion-strengthened copper tube with an outer diameter of 15mm, an inner diameter of 10mm, a length of 10cm, and a wall thickness of 2.5mm (the mass fraction of alumina in the alumina dispersion-strengthened copper tube is 1.2%) and an alumina dispersion-strengthened copper wire with a diameter of 0.5mm and a length of 10cm (the mass fraction of alumina in the alumina dispersion-strengthened copper wire is 1.2%); The outer and inner surfaces of the alumina dispersion-strengthened copper tube and the surface of the alumina dispersion-strengthened copper wire are then mechanically polished sequentially (20 mm). The copper tubes and wires were pretreated by annealing. The first heat treatment was carried out in a mixed atmosphere of hydrogen and argon (volume ratio of hydrogen to argon was 5:95) at a temperature of 800℃ for 30 minutes. After the first heat treatment, the pretreatment of the copper tubes and wires was completed.

[0045] S1. Using methane as the carbon source, graphene was grown on the surface of pretreated alumina dispersion-reinforced copper wire by chemical vapor deposition in a mixed atmosphere of hydrogen and argon (the standard volume flow rates of hydrogen, argon and methane were 30 sccm, 300 sccm and 5 sccm, respectively). The growth temperature was set to 900℃ and the time was 40 min to obtain the composite unit.

[0046] S2. Assemble 310 composite units obtained in S1 into a bundle to obtain an assembly. Insert the assembly into a pre-treated alumina dispersion-strengthened copper tube (the cross-sectional area of ​​the assembly accounts for 77.5% of the inner cross-sectional area of ​​the alumina dispersion-strengthened copper tube). Vacuum weld both ends and then perform multi-pass die rolling. Set the deformation amount per pass to 10%. After die rolling, a wire with a diameter of 8mm is obtained. Then, the wire is subjected to intermediate annealing. Set the intermediate annealing temperature to 400℃ and the time to 30min. Finally, it is drawn with a deformation amount of 8% per pass to obtain a multi-core composite wire with a diameter of 0.5mm.

[0047] S3. Using a multi-core composite wire with a diameter of 0.5mm as the new processing object, repeat steps S1 and S2 above, repeating the process k=3 times (each time the processing object is the multi-core composite wire obtained in the previous repetition), to obtain a composite wire with a diameter of 0.5mm.

[0048] S4. Draw the composite wire to a diameter of 0.25 mm to obtain a composite wire with a diameter of 0.25 mm.

[0049] S5. Anneal the composite wire with a diameter of 0.25 mm at 300℃ for 20 min to obtain a high-temperature resistant copper / graphene composite wire.

[0050] Example 7 This embodiment provides a method for preparing a high-temperature resistant copper / graphene composite wire, including the following steps: Pretreatment steps: Take a yttrium oxide dispersion-strengthened copper tube with an outer diameter of 8mm, an inner diameter of 5mm, a length of 20cm, and a wall thickness of 1.5mm (the mass fraction of yttrium oxide in the yttrium oxide dispersion-strengthened copper tube is 2%) and a yttrium oxide dispersion-strengthened copper wire with a diameter of 0.2mm and a length of 20cm (the mass fraction of yttrium oxide in the yttrium oxide dispersion-strengthened copper wire is 2%); mechanically grind the outer and inner surfaces of the yttrium oxide dispersion-strengthened copper tube and the surface of the yttrium oxide dispersion-strengthened copper wire sequentially (5000 grit). The yttrium oxide dispersion-strengthened copper tubes and wires were pretreated by annealing with sandpaper and acid (using a 10% hydrochloric acid solution for 5 minutes). The resulting yttrium oxide dispersion-strengthened copper tubes and wires were then subjected to a first heat treatment in a mixed atmosphere of hydrogen and argon (volume ratio of hydrogen to argon was 10:90). The first heat treatment was performed at 700℃ for 50 minutes. After annealing, the pretreatment of the yttrium oxide dispersion-strengthened copper tubes and wires was completed.

[0051] S1. Oleic acid (mass ratio of oleic acid to copper wire is 0.005:1) is coated on the surface of the pretreated yttrium oxide dispersion-reinforced copper wire. Graphene is grown in a mixed atmosphere of hydrogen and argon (standard volume flow rates of hydrogen and argon are 50 sccm and 200 sccm, respectively). The growth temperature is set to 1030℃ and the time is 50 min.

[0052] S2. Assemble 400 composite units obtained in S1 into a bundle to obtain an assembly. Insert the assembly into a pretreated yttrium oxide dispersion-strengthened copper tube (the cross-sectional area of ​​the assembly accounts for 64% of the inner cross-sectional area of ​​the yttrium oxide dispersion-strengthened copper tube). Vacuum weld both ends, and then perform multi-pass die rolling with a single-pass deformation of 8%. After die rolling, a wire with a diameter of 4 mm is obtained. Then, the wire is subjected to intermediate annealing at a temperature of 500℃ for 20 minutes. Finally, it is drawn with a single-pass deformation of 8%, resulting in a multi-core composite wire with a diameter of 0.65 mm.

[0053] S3. Using a multi-core composite wire with a diameter of 0.65mm as the new processing object, repeat steps S1 and S2 above, repeating the process k=5 times (each time the processing object is the multi-core composite wire obtained in the previous repetition), to obtain a composite wire with a diameter of 0.65mm.

[0054] S4. Draw the composite wire to a diameter of 0.12 mm to obtain a composite wire with a diameter of 0.12 mm.

[0055] S5. Anneal the composite wire with a diameter of 0.12 mm at 400℃ for 10 min to obtain a high-temperature resistant copper / graphene composite wire.

[0056] Example 8 This embodiment provides a method for preparing a high-temperature resistant copper / graphene composite wire, including the following steps: Pretreatment steps: Take a titanium diboride dispersion-strengthened copper tube with an outer diameter of 30mm, an inner diameter of 28mm, a length of 10cm, and a wall thickness of 1mm (the volume fraction of titanium diboride in the titanium diboride dispersion-strengthened copper tube is 15%) and a titanium diboride dispersion-strengthened copper wire with a diameter of 1mm and a length of 10cm (the volume fraction of titanium diboride in the titanium diboride dispersion-strengthened copper wire is 15%); The outer and inner surfaces of the titanium diboride dispersion-strengthened copper tube and the surface of the titanium diboride dispersion-strengthened copper wire are then mechanically polished sequentially (20 mm). The copper tubes and wires were pretreated with 0.00 mesh sandpaper and pickled (using a 10% hydrochloric acid solution for 5 minutes). Then, the obtained titanium diboride dispersion-strengthened copper tubes and wires were subjected to a first heat treatment. The first heat treatment was carried out in a mixed atmosphere of hydrogen and argon (volume ratio of hydrogen to argon was 7:93) at a temperature of 920℃ for 30 minutes. After annealing, the pretreatment of the titanium diboride dispersion-strengthened copper tubes and wires was completed.

[0057] S1. A glucose aqueous solution was coated on the surface of the pretreated titanium diboride dispersion-reinforced copper wire, and graphene was grown in a mixed atmosphere of hydrogen and argon (the standard volume flow rates of hydrogen and argon were 50 sccm and 500 sccm, respectively). The growth temperature was set to 800℃ and the time was 60 min.

[0058] S2. Assemble 660 composite units obtained in S1 into a bundle to obtain an assembly. Insert the assembly into a pre-treated titanium diboride dispersion-strengthened copper tube (the cross-sectional area of ​​the assembly accounts for 84% of the inner cross-sectional area of ​​the titanium diboride dispersion-strengthened copper tube). Vacuum weld both ends, and then perform multi-pass forging with a deformation amount of 15% per pass to obtain a wire with a diameter of 10mm. Then, perform intermediate annealing treatment on the wire, setting the temperature of the intermediate annealing treatment to 300℃ and the time to 60min. Finally, perform multi-pass drawing with a deformation amount of 10% per pass to obtain a multi-core composite wire with a diameter of 1mm.

[0059] S3. Using a multi-core composite wire with a diameter of 1mm as the new processing object, repeat steps S1 and S2 above, repeating the process k=2 times (each time the processing object is the multi-core composite wire obtained in the previous repetition), to obtain a composite wire with a diameter of 1mm.

[0060] S4. Draw the composite wire to a diameter of 0.5 mm to obtain a composite wire with a diameter of 0.5 mm.

[0061] S5. Anneal the composite wire with a diameter of 0.5 mm at 500℃ for 10 min to finally obtain a high-temperature resistant copper / graphene composite wire.

[0062] Comparative Example 1 This comparative example provides a method for preparing a high-temperature resistant copper / graphene composite wire, including the following steps: Pretreatment steps: Take a pure copper tube (99.99% purity) with an outer diameter of 4mm, an inner diameter of 3mm, and a length of 30cm, and a pure copper wire (99.99% purity) with a diameter of 0.95mm and a length of 30cm. Mechanically polish the outer and inner surfaces of the pure copper tube and the surface of the pure copper wire (using 2000-grit sandpaper) and then ultrasonically clean them (using ethanol as solvent, 200W power, for 20 minutes). Next, subject the obtained pure copper tube and pure copper wire to a first heat treatment in a mixed atmosphere of hydrogen and argon (volume ratio of hydrogen to argon of 20:80) at 600℃ for 60 minutes. This completes the pretreatment of the pure copper tube and pure copper wire.

[0063] S1. Using methane as the carbon source, graphene was grown on the surface of pretreated pure copper wire by chemical vapor deposition in a mixed atmosphere of hydrogen and argon (the standard volume flow rates of hydrogen, argon and methane were 50 sccm, 500 sccm and 10 sccm, respectively). The growth temperature was set to 1000℃ and the time was 30 min.

[0064] S2. Seven pure copper wires with grown graphene are bundled together to obtain an assembly. The assembly is then inserted into a pre-treated pure copper tube (the cross-sectional area of ​​the assembly accounts for 70.1% of the inner cross-sectional area of ​​the pure copper tube). The two ends are vacuum welded, and then multi-pass die rolling is performed. The deformation amount per pass is set to 5%. After die rolling, a wire with a diameter of 2 mm is obtained. The wire is then subjected to intermediate annealing at a temperature of 300℃ for 60 min. Finally, multi-pass drawing is performed with a deformation amount of 10% per pass. After drawing, a composite wire with a diameter of 0.95 mm is obtained.

[0065] S3. Using a multi-core composite wire with a diameter of 0.95mm as the new processing object, repeat steps S1 and S2 above, repeating the process k=1 times, to obtain a composite wire with a diameter of 0.95mm.

[0066] S4. The composite wire with a diameter of 0.95 mm obtained in S3 is subjected to a second heat treatment (800℃, 30 min) and then drawn to a diameter of 0.05 mm to obtain a composite wire with a diameter of 0.05 mm.

[0067] S5. The composite wire with a diameter of 0.05 mm from S4 is annealed at 300℃ for 30 min to obtain a high-temperature resistant copper / graphene composite wire.

[0068] Comparative Example 2 This comparative example provides a method for preparing a high-temperature resistant copper / graphene composite wire, including the following steps: Pretreatment steps: Take an alumina dispersion-strengthened copper tube with an outer diameter of 4mm, an inner diameter of 3mm, and a length of 30cm (the mass fraction of alumina in the alumina dispersion-strengthened copper tube is 0.7%) and an alumina dispersion-strengthened copper wire with a diameter of 0.95mm and a length of 30cm (the mass fraction of alumina in the alumina dispersion-strengthened copper tube is 0.7%). The outer and inner surfaces of the alumina dispersion-strengthened copper tube and the surface of the alumina dispersion-strengthened copper wire are mechanically polished (using 2000-grit sandpaper) and ultrasonically cleaned (using ethanol as solvent, 200W power, for 20min) respectively. Then, the obtained alumina dispersion-strengthened copper tube and alumina dispersion-strengthened copper wire are subjected to a first heat treatment. The first heat treatment is carried out in a mixed atmosphere of hydrogen and argon (the volume ratio of hydrogen to argon is 20:80), at a temperature of 600℃ for 60min, thus completing the pretreatment of the pure copper tube and pure copper wire.

[0069] S1. Using methane as the carbon source, graphene was grown on the surface of pretreated alumina dispersed reinforced copper wire by chemical vapor deposition in a mixed atmosphere of hydrogen and argon (the standard volume flow rates of hydrogen, argon and methane were 50 sccm, 500 sccm and 10 sccm, respectively). The growth temperature was set to 1000℃ and the time was 30 min.

[0070] S2. Seven graphene-grown alumina-reinforced copper wires are bundled and assembled to obtain an assembly. The assembly is then inserted into a pre-treated alumina-reinforced copper tube (the cross-sectional area of ​​the assembly accounts for 70.1% of the inner cross-sectional area of ​​the alumina-reinforced copper tube). The two ends are vacuum welded, and then multi-pass die rolling is performed. The deformation amount per pass is set to 5%. After die rolling, a wire with a diameter of 2 mm is obtained. The wire is then subjected to intermediate annealing at a temperature of 300℃ for 60 min. Finally, multi-pass drawing is performed with a deformation amount of 10% per pass. After drawing, a composite wire with a diameter of 0.95 mm is obtained.

[0071] S3. Perform a second heat treatment on the composite wire with a diameter of 0.95mm (temperature 800℃, time 30min) and draw it to a diameter of 0.05mm to obtain a composite wire with a diameter of 0.05mm.

[0072] S4. The composite wire with a diameter of 0.05 mm from S3 is annealed at 300℃ for 30 min to obtain a high-temperature resistant copper / graphene composite wire.

[0073] Test Example 1 The high-temperature resistant copper / graphene composite wire prepared in Example 1 was characterized, and the results are as follows: Figure 1-2 As shown. Figure 1 Here is a metallographic microscope image of the cross-sectional metallographic structure of the high-temperature resistant copper / graphene composite wire of Embodiment 1 of the present invention. Figure 1 As can be seen from the above, the high-temperature resistant copper / graphene composite wire prepared in Example 1 of the present invention exhibits a multi-core structure. Figure 2 This is the Raman spectrum of graphene grown on the surface of alumina-dispersion-reinforced copper wire in Example 1 of the present invention. The G peak represents the characteristic peak of in-plane vibrations of carbon atoms in the graphene, the D peak represents the disorder-induced peak or defect peak, and the 2D peak represents the second overtone of the G peak. The number of graphene layers can be inferred from the intensity ratio of the 2D peak to the G peak. Figure 2 It can be seen that the surface of the alumina dispersion-reinforced copper wire is covered with multilayer graphene, which can be uniformly distributed through interlayer slip after subsequent large deformation drawing.

[0074] Test Example 2 The high-temperature resistant copper / graphene composite wires prepared in Comparative Example 1 and Examples 1-8 were tested for conductivity, tensile strength and softening temperature, respectively, according to the standards GB / T 351-2019, GB / T 228-2002 and GB / T 33370-2016. The test results are recorded in Table 1.

[0075] Table 1 Test Results

[0076] As can be seen from Table 1, the high-temperature resistant copper / graphene composite wires obtained by the preparation methods of Examples 1-8 of the present invention have a softening temperature ≥850℃, conductivity ≥81%IACS, and tensile strength ≥680MPa, achieving synergistic optimization of high temperature resistance, high strength, and high conductivity of copper / graphene composite wires.

[0077] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a high-temperature resistant copper / graphene composite wire, characterized in that, Includes the following steps: S1. Using dispersion-strengthened copper wire as the processing object, graphene is grown on the surface of the dispersion-strengthened copper wire to obtain a composite unit; S2. Assemble multiple composite units obtained from S1 into a bundle to obtain an assembly. Then, insert the assembly into a dispersion-strengthened copper tube and vacuum seal both ends. Then, perform plastic deformation treatment and intermediate annealing treatment to obtain a multi-core composite wire. S3. Using the multi-core composite wire obtained in S2 as the new processing object, repeat S1 and S2 to obtain the composite wire; The number of repetitions k ≥ 1, and the processing object for each repetition is the multi-core composite wire obtained in the previous repetition; S4. Anneal the composite wire finally obtained in S3 to obtain the high-temperature resistant copper / graphene composite wire.

2. The method for preparing high-temperature resistant copper / graphene composite wire according to claim 1, characterized in that, The materials of the dispersion-strengthened copper wire in S1 and the dispersion-strengthened copper tube in S2 are independently selected from at least one of alumina dispersion-strengthened copper, yttrium oxide dispersion-strengthened copper, and titanium diboride dispersion-strengthened copper. Before use, the dispersion-strengthened copper wire in S1 and the dispersion-strengthened copper tube in S2 are pretreated. The pretreatment process includes grinding and cleaning the outer and inner surfaces of the dispersion-strengthened copper tube and the surface of the dispersion-strengthened copper wire in sequence, and then performing the first heat treatment respectively. And / or, the number of times k is repeated in S3 is 2-5 times.

3. The method for preparing high-temperature resistant copper / graphene composite wires according to claim 1 or 2, characterized in that, The plastic deformation treatment in S2 includes at least one of forging, extrusion, rolling and drawing; The total deformation amount in the plastic deformation treatment in S2 is ≥90%, and the deformation amount per pass is ≤15%; The intermediate annealing process in S2 is performed at a temperature of 300℃-800℃ for a time of 10min-60min. The cross-sectional area of ​​the assembly in S2 accounts for ≥60% of the inner diameter area of ​​the dispersion-strengthened copper tube.

4. The method for preparing high-temperature resistant copper / graphene composite wire according to claim 1, characterized in that, The diameter of the dispersion-strengthened copper wire in S1 is 0.05mm-1mm; the inner diameter of the dispersion-strengthened copper tube in S2 is 3-28mm, and the wall thickness is 0.5-2.5mm.

5. The method for preparing high-temperature resistant copper / graphene composite wires according to claim 1 or 2, characterized in that, The process of growing graphene on the surface of the dispersion-reinforced copper wire in S1 includes: In a first reducing atmosphere, graphene is grown on the surface of a dispersion-strengthened copper wire by applying a gaseous carbon source to it via chemical vapor deposition. Alternatively, under a second reducing atmosphere, graphene can be grown after coating a liquid carbon source onto the surface of a dispersion-strengthened copper wire.

6. The method for preparing high-temperature resistant copper / graphene composite wire according to claim 5, characterized in that, At least one of the following conditions must be met: (1) The first reducing atmosphere includes hydrogen and argon; Optionally, in the first reducing atmosphere, the standard volume flow rate ratio of hydrogen to argon is (10-50):(100-500). (2) The gaseous carbon source includes methane; (3) The standard volumetric flow rate ratio of the first reducing atmosphere to the gaseous carbon source is (110-550):(1-10); (4) The growth temperature of graphene grown using gaseous carbon source is 800-1030℃ and the growth time is 30-60min; (5) The second reducing atmosphere includes hydrogen and argon; Optionally, in the second reducing atmosphere, the standard volume flow rate ratio of hydrogen to argon is (10-100):(100-500). (6) The liquid carbon source includes a carbon source that is liquid at room temperature or a carbon source that is liquid after being dissolved in a solvent; Optionally, the liquid carbon source includes at least one of paraffin, oleic acid, naphthol, and glucose; Optionally, the solvent includes at least one of water and ethanol; (7) The growth temperature of graphene grown using the liquid carbon source is 600-1000℃ and the time is 30-60min.

7. The method for preparing high-temperature resistant copper / graphene composite wire according to claim 1, characterized in that, The annealing process in S4 is carried out at a temperature of 300-500℃ for 10-60 minutes. And / or, S4 further includes a drawing step of the composite wire prior to annealing; Optionally, a second heat treatment step may be included before the drawing step; Optionally, the temperature of the second heat treatment is 600-800℃ and the time is 30min-1h.

8. A high-temperature resistant copper / graphene composite wire, characterized in that, The high-temperature resistant copper / graphene composite wire is prepared according to any one of claims 1-7.

9. The high-temperature resistant copper / graphene composite wire according to claim 8, characterized in that, The high-temperature resistant copper / graphene composite wire has a softening temperature ≥850℃, a conductivity ≥81%IACS, and a tensile strength ≥680MPa.

10. The application of the high-temperature resistant copper / graphene composite wire as described in claim 8 or 9 in the fields of drone motors, high-speed generators for aerospace, new energy vehicles, and high-end electronic devices.

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