Hollow copper drawing wire with small resistance and preparation process thereof

Abstract

The invention belongs to the technical field of cables, particularly relates to a small-resistance hollow copper drawn wire and a preparation process thereof, and provides the following scheme aiming at the problems of bottleneck, extensive preparation process and insufficient core performance of an existing material system: the hollow copper drawn wire is prepared by taking a composite modified copper-based material as a raw material through multi-pass stretching; the composite modified copper-based material is composed of, by weight, 98.50%-99.70% of high-purity electrolytic copper, 0.05%-0.30% of silver, 0.001%-0.01% of a rare earth element compound and 0.02%-0.08% of a transition metal strengthening phase, the mixing uniformity is improved through raw material differentiation pretreatment, and a high-bonding-strength anti-oxidation transition layer is formed through plasma spraying to enhance the corrosion resistance; a gradual change die and a DLC coating are adopted, sectional variable-speed stretching and gradient deformation are matched with material plasticity, and online detection and accurate shape control are achieved; and work hardening and oxidation are avoided through zoned temperature control annealing, finally, the size precision, the mechanical property and the stability of the product are greatly improved, and machining defects are reduced.

Description

Technical Field

[0001] This invention relates to the field of cable technology, and in particular to a hollow copper wire with low resistance and its preparation process. Background Technology

[0002] Chinese patent application number 202211371691.7 discloses an efficient copper wire drawing process, comprising: S1, pretreatment: polishing and removing impurities such as copper rust from the exterior of the copper wire, then immersing the copper wire in a cleaning solution at 90-100℃ for 15-25 minutes; S2, annealing: heating the cleaned copper wire in a vacuum furnace; S3, pre-drawing: spraying lubricant onto the annealed copper wire and pre-drawing the copper wire to a diameter of 2-3mm. The copper wire is first drawn into a vacuum furnace and heated to 650-700℃, then held at that temperature for one to two hours. Steps S4 and S5 are performed: Inspection of the inside and outside of the drawing die before fine drawing; Step S6 is the drawing process: the copper wire is drawn through the drawing die to obtain the desired diameter, with continuous spraying of lubricant during the process. A copper material collection box is installed at the bottom of the drawing die; Step S7 is the annealing process: the drawn copper wire is returned to the vacuum furnace for annealing; Step S8 is the cleaning process: the exterior of the copper wire is cleaned and dried. This copper wire drawing process reduces the number of drawing operations and greatly improves the forming efficiency of the copper wire.

[0003] However, this efficient copper wire drawing process also has some problems. For example, it mainly uses pure copper or simple binary alloys, without multi-component synergistic strengthening design, resulting in significant performance shortcomings. Pure copper has an conductivity of approximately 100% IACS, but its tensile strength is <250MPa, making it prone to breakage. After increasing the strength of conventional copper alloys, the resistivity rises to... In environments above 300℃ or corrosive conditions, oxidation weight gain is ≥0.5g / m², corrosion rate is >0.01mm / a, lifespan is short, casting easily leads to elemental segregation and poor dispersion of nano-reinforcing phases, copper billets contain microcracks / porosity, product qualification rate is <80%, pretreatment is simple, casting easily introduces impurities, mold design defects, and ambiguous stretching / annealing parameters result in low dimensional accuracy (wall thickness deviation >8%), low production efficiency, high resistivity, elongation <10%, and weak corrosion resistance, making it unable to meet the needs of high-end fields such as high-frequency communication and aerospace. Summary of the Invention

[0004] Given the limitations of the prior art in terms of material system bottlenecks, crude preparation processes, and insufficient core performance, this invention proposes a hollow copper wire drawing method with low resistance and its preparation process.

[0005] This invention proposes a hollow copper wire with low resistance. The hollow copper wire is prepared by multiple stretching processes using a composite modified copper-based material as raw material. The composite modified copper-based material consists of the following components by weight percentage: 98.50%–99.70% high-purity electrolytic copper, 0.05%–0.30% silver, 0.001%–0.01% rare earth element composite, 0.02%–0.08% transition metal reinforcing phase, 0.01%–0.05% nano-conductive reinforcing phase, and 0.10%–0.20% antioxidant coating precursor, with the balance being unavoidable impurities. The rare earth element composite is a lanthanum-cerium-yttrium ternary alloy with a lanthanum, cerium, and yttrium weight ratio of 3:2:1; the transition metal reinforcing phase is a zirconium-niobium-titanium composite powder, in which zirconium accounts for no less than 50% by weight and niobium to titanium has a weight ratio of 1:1.2; the nano-conductive reinforcing phase is a carbon nanotube-graphene composite powder modified with silane coupling agent KH550, with a carbon nanotube to graphene mass ratio of 4:1 and the modified powder surface hydroxyl content of 0.8–1.2 mmol / g; the antioxidant coating precursor is a tetrabutyl titanate-silane coupling agent KH560-ethanol mixture system, with a tetrabutyl titanate to KH560 molar ratio of 1:0.8 and the amount of ethanol added being 3–5 times the mass of tetrabutyl titanate; The manufacturing process of hollow copper wire includes the following steps: S1: High-purity electrolytic copper is crushed into copper particles with a particle size of 5-10 mm, ultrasonically cleaned for 15-20 minutes, and then placed in a vacuum drying oven and dried at 120-150℃ for 2-3 hours. Silver blocks are processed into silver foil with a thickness of 0.5-1 mm. Rare earth element composites are crushed into particles with a particle size of 1-2 mm. The transition metal strengthening phase is ball-milled to a particle size of 50-100 nm. The nano-conductive strengthening phase is added to ethanol and ultrasonically dispersed for 30-40 minutes to form a dispersion with a mass concentration of 5%-8%. The components of the antioxidant coating precursor are mixed in proportion and stirred at 40-50℃ for 60-90 minutes to prepare a stable precursor solution. S2: Add the pretreated copper granules to the vacuum induction melting furnace and evacuate to a vacuum level. The temperature is raised to 1150–1200℃ to completely melt the copper particles. After holding at this temperature for 20–30 minutes, silver foil, rare earth element composite, and transition metal reinforcing phase are added sequentially. The stirring speed is 300–400 r / min, and the stirring time is 15–20 minutes. Then, the nano-conductive reinforcing phase dispersion is sprayed into the melt through a high-pressure atomizing nozzle at an atomization pressure of 1.2–1.5 MPa, while stirring at a high speed of 500–600 r / min for 10–15 minutes. The molten composite copper liquid is then poured into a hollow mold preheated to 300–350℃. The inner diameter of the mold is 20–30 mm, the wall thickness is 5–8 mm, the casting speed is 0.8–1.2 kg / min, and the cooling rate is controlled at 80–100℃ / min. After complete solidification, the mold is demolded to obtain a hollow copper billet. S3: Place the prepared hollow copper billet in a plasma spraying equipment, use argon as the protective gas, and spray the anti-oxidation coating precursor solution onto the inner and outer surfaces of the hollow copper billet. The spraying temperature is 200-250℃, and the coating thickness is controlled to be 5-10μm. After spraying, keep it at 280-300℃ for 1-2 hours to allow the precursor to fully solidify and form an anti-oxidation transition layer. S4: Employs a vertical multi-head wire drawing machine equipped with a dual-cavity die with a gradually decreasing inlet angle. The inlet angle of the die gradually decreases from 18° to 12°, and the outlet angle is 3-4°. The inner hole of the die is coated with a DLC diamond-like carbon coating with a thickness of 3-5μm. Before wire drawing, the hollow copper billet is preheated at 80-100℃. Simultaneously, a high-pressure atomization lubrication system is used to spray oil-based lubricant at a pressure of 1.0-1.2MPa into the die inlet. The lubricant particle size is ≤5μm. The wire drawing process adopts segmented speed control. The first stage of drawing speed is 6-8m / s, with a single-pass surface reduction rate of 15%-18%; the second stage of drawing speed is 12-15m / s, with a single-pass surface reduction rate of 20%-22%; and the third stage of drawing speed is 18-20m / s, with a single-pass surface reduction rate of 23%-25%. After each stage of drawing is completed, the outer diameter and wall thickness of the hollow copper wire are detected in real time using a laser diameter gauge and an ultrasonic thickness gauge. S5: Intermediate annealing is performed between the second and third drawing stages. The copper wire that has been drawn in the second stage is placed in a continuous annealing furnace and a nitrogen-hydrogen mixed protective atmosphere is introduced, wherein the hydrogen content is 5% to 8%, the annealing temperature is 350 to 400℃, the holding time is 40 to 60 minutes, the heating rate is 5 to 8℃ / min, the cooling rate is 3 to 5℃ / min, and the Vickers hardness of the copper wire after annealing is controlled at 80 to 90 HV. S6: The hollow copper wires that have undergone the third stage of stretching are sequentially subjected to ultrasonic cleaning and hot air drying. The cleaning solution is an ethanol-deionized water mixture with a volume ratio of 1:3, and the cleaning time is 10-15 minutes. The drying temperature is 80-100℃, and the drying time is 5-8 minutes. After drying, the hollow copper wires are inspected to obtain hollow copper wires with low resistance. Differentiated pretreatment of raw materials improves the mixing uniformity, and plasma spraying forms a high-bonding-strength, anti-oxidation transition layer to enhance corrosion resistance. Gradient mold + DLC coating, segmented variable speed stretching, and gradient deformation are used to adapt to the material's plasticity, and online detection ensures precise shape control. Zoned temperature-controlled annealing avoids work hardening and oxidation, ultimately significantly improving the product's dimensional accuracy, mechanical properties, and stability, and reducing processing defects.

[0006] Preferably, the high-purity electrolytic copper has a purity of not less than 99.995%, wherein the weight content of impurity elements meets the following requirements: iron ≤ 0.0005%, lead ≤ 0.0003%, tin ≤ 0.0002%, sulfur ≤ 0.0001%, oxygen ≤ 0.0005%, the individual content of other impurity elements ≤ 0.0001%, and the total impurity content ≤ 0.005%. The high-purity electrolytic copper has a grain size of 50-80 μm and a conductivity ≥ 101% IACS, ensuring product quality.

[0007] Preferably, in the rare earth element complex, the purity of lanthanum is not less than 99.9%, the purity of cerium is not less than 99.9%, and the purity of yttrium is not less than 99.95%. The rare earth element complex is added as follows: lanthanum, cerium, and yttrium are mixed in a weight ratio of 3:2:1, then melted at 800-900℃ for 20-30 minutes under an inert atmosphere, cooled, and crushed to a specified particle size. The inert atmosphere is argon with a gas purity ≥99.999%, in order to improve the performance of the product.

[0008] Preferably, in the transition metal reinforcing phase, the purity of zirconium is not less than 99.9%, the purity of niobium is not less than 99.9%, and the purity of titanium is not less than 99.8%. The ball milling treatment of the transition metal reinforcing phase is carried out in a planetary ball mill with a ball-to-material ratio of 20:1, a ball milling speed of 300-400 r / min, and a ball milling time of 4-6 hours. Anhydrous ethanol is added as a dispersant during the ball milling process, and the amount of dispersant is 10%-15% of the total mass of the transition metal powder. After ball milling, the powder is dried in a vacuum drying oven at 60-80℃ for 2-3 hours to remove the dispersant. This process can increase the compatibility between materials.

[0009] Preferably, the carbon nanotubes in the nano-conductive reinforcing phase are single-walled carbon nanotubes with a diameter of 1–3 nm, a length of 5–10 μm, and a purity ≥98%; the graphene is single-layer graphene with a sheet diameter of 0.5–2 μm and a purity ≥99%; the amount of silane coupling agent KH550 added is 3%–5% of the total mass of the carbon nanotube-graphene composite powder, and the modification process is as follows: the carbon nanotube-graphene composite powder and KH550 are added to ethanol, stirred and reacted at 60–70 °C for 2–3 hours, followed by centrifugation and vacuum drying at 80–100 °C for 4–6 hours, which can increase the conductivity of the product.

[0010] Preferably, in step S2, the induction coil frequency of the vacuum induction melting furnace is 200–300 kHz, and the power is 50–80 kW; a vibration crystallization device is used during the casting process, with a vibration frequency of 50–60 Hz and an amplitude of 0.1–0.2 mm. Vibration promotes the escape of bubbles in the melt, reducing porosity defects inside the billet. The porosity of the hollow copper billet is ≤0.01%, the outer diameter tolerance of the hollow copper billet is ±0.2 mm, and the wall thickness tolerance is ±0.1 mm.

[0011] Preferably, in S3, the plasma arc voltage of the plasma spraying equipment is 60-80V, the current is 150-200A, and the spraying distance is 100-150mm; the surface roughness Ra of the anti-oxidation transition layer is ≤0.2μm, and the bonding strength with the hollow copper blank is ≥50MPa, thereby improving the spraying effect.

[0012] Preferably, in step S4, the oil-based lubricant is composed of the following components: hydrotreated mineral oil, zinc dialkyl dithiophosphate, benzotriazole, polyoxyethylene castor oil, and polydimethylsiloxane; the lubricant has a kinematic viscosity of 20-30 mm² / s at 40°C, a flash point ≥200°C, an acid value ≤0.5 mg KOH / g, an outer diameter detection accuracy of ±0.001 mm, a wall thickness detection accuracy of ±0.002 mm, and adjusts the tensile tension based on the detection results, controlling the tension fluctuation within ±2%, thus achieving effective lubrication and reducing friction.

[0013] Preferably, in step S5, the furnace atmosphere pressure of the continuous annealing furnace is 0.12 to 0.15 MPa, and a zoned temperature control method is adopted, with the temperature fluctuations of the heating zone, the holding zone, and the cooling zone controlled within ±5℃, ±2℃, and ±3℃, respectively; the annealed copper wire is cooled to room temperature with inert gas, and the cooling gas flow rate is 10 to 15 m / s to improve the drawing efficiency.

[0014] Preferably, in step S6, the outer diameter of the hollow copper wire is 0.5–5 mm, the wall thickness is 0.05–0.5 mm, and the resistivity at room temperature is [not specified]. Tensile strength ≥320MPa, and oxidation weight gain ≤0.05g / m² after 100 hours of constant temperature oxidation at 300℃.

[0015] The beneficial effects of this invention are: 1. This application breaks through the traditional single material formulation and designs a composite system of "high-purity copper matrix + multi-component functional phase". By precisely controlling the proportion and morphology of each component, the conductive, mechanical and corrosion-resistant properties are synergistically optimized. 2. In the pretreatment stage, this application performs differentiated treatment on each raw material. In the surface modification stage, plasma spraying technology is used to spray the anti-oxidation precursor onto the inner and outer surfaces of the copper billet, which effectively improves corrosion resistance. In the core wire drawing stage, a dual-cavity mold with a gradient entry angle is innovatively adopted to reduce friction. Combined with the segmented variable speed stretching process and gradient deformation, it matches the plasticity changes of the material at different stretching stages. An online detection system is introduced to provide real-time feedback and adjust the tension to ensure dimensional accuracy. In the intermediate annealing stage, a nitrogen-hydrogen mixed atmosphere is used with zoned temperature control to avoid work hardening and oxidation. By improving the uniformity of mixing through differentiated pretreatment of raw materials, plasma spraying forms a high-bonding-strength, antioxidant transition layer to enhance corrosion resistance; gradient mold + DLC coating, segmented variable speed stretching and gradient deformation are used to adapt to the plasticity of the material, and online detection is used for precise shape control; zoned temperature-controlled annealing avoids work hardening and oxidation, ultimately significantly improving the dimensional accuracy, mechanical properties and stability of the product, and reducing processing defects. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the workflow proposed in this invention. Detailed Implementation

[0017] The present invention will be further explained below with reference to specific embodiments.

[0018] Reference Figure 1 Example 1 This embodiment proposes a hollow copper wire with low resistance. The hollow copper wire is prepared by multiple stretching processes using a composite modified copper-based material as raw material. The composite modified copper-based material consists of the following components by weight percentage: 99.39% high-purity electrolytic copper, 0.27% silver, 0.007% rare earth element composite, 0.08% transition metal reinforcing phase, 0.05% nano-conductive reinforcing phase, and 0.20% antioxidant coating precursor, with the balance being unavoidable impurities. The rare earth element composite is a lanthanum-cerium-yttrium ternary alloy with a lanthanum, cerium, and yttrium weight ratio of 3:2:1; the transition metal reinforcing phase is a zirconium-niobium-titanium composite powder, in which zirconium accounts for no less than 50% by weight and niobium to titanium has a weight ratio of 1:1.2; the nano-conductive reinforcing phase is a carbon nanotube-graphene composite powder modified with silane coupling agent KH550, with a carbon nanotube to graphene mass ratio of 4:1 and a surface hydroxyl content of 1.1 mmol / g; the antioxidant coating precursor is a tetrabutyl titanate-silane coupling agent KH560-ethanol mixture, with a tetrabutyl titanate to KH560 molar ratio of 1:0.8. The amount of alcohol added is 4 times the mass of tetrabutyl titanate. The purity of the high-purity electrolytic copper is not less than 99.995%, and the weight content of impurity elements meets the following requirements: iron ≤ 0.0005%, lead ≤ 0.0003%, tin ≤ 0.0002%, sulfur ≤ 0.0001%, oxygen ≤ 0.0005%, and the individual content of other impurity elements ≤ 0.0001%, with a total impurity content ≤ 0.005%. The grain size of the high-purity electrolytic copper is 56μm, and the conductivity is ≥ 101% IACS. In the rare earth element complex, the purity of lanthanum is not less than 99.9%, the purity of cerium is not less than 99.9%, and the purity of yttrium is not less than 99.95%. The composite was added as follows: Lanthanum, cerium, and yttrium were mixed in a weight ratio of 3:2:1, melted at 880℃ for 25 minutes under an inert atmosphere, cooled, and then crushed to the specified particle size. The inert atmosphere was argon with a purity ≥99.999%. In the transition metal strengthening phase, the purity of zirconium was not less than 99.9%, the purity of niobium was not less than 99.9%, and the purity of titanium was not less than 99.8%. The ball milling treatment of the transition metal strengthening phase was carried out in a planetary ball mill with a ball-to-material ratio of 20:1, a ball milling speed of 350 r / min, and a ball milling time of 5 hours. Anhydrous ethanol was added as a dispersant during the ball milling process, and the amount of dispersant was the transition metal powder. The carbon nanotubes in the nano-conductive reinforcing phase, which account for 14% of the total mass, are ball-milled and dried in a vacuum drying oven at 70°C for 2 hours to remove the dispersant. The carbon nanotubes in the nano-conductive reinforcing phase are single-walled carbon nanotubes with a diameter of 2 nm, a length of 7 μm, and a purity of ≥98%. The graphene is a single-layer graphene with a sheet diameter of 1.2 μm and a purity of ≥99%. The amount of silane coupling agent KH550 added is 4% of the total mass of the carbon nanotube-graphene composite powder. The modification process is as follows: the carbon nanotube-graphene composite powder and KH550 are added to ethanol and stirred at 60-70°C for 2 hours. Then, the mixture is centrifuged, vacuum dried at 90°C for 5 hours. The manufacturing process of hollow copper wire includes the following steps: S1: High-purity electrolytic copper was crushed into copper particles with a particle size of 8 mm. After ultrasonic cleaning for 18 minutes, it was placed in a vacuum drying oven and dried at 130°C for 2 hours. The silver block was processed into silver foil with a thickness of 0.8 mm. The rare earth element composite was crushed into particles with a particle size of 1 mm. The transition metal strengthening phase was ball-milled to a particle size of 70 nm. The nano-conductive strengthening phase was added to ethanol and ultrasonically dispersed for 35 minutes to form a dispersion with a mass concentration of 7%. The components of the antioxidant coating precursor were mixed in proportion and stirred at 45°C for 80 minutes to prepare a stable precursor solution. S2: Add the pretreated copper granules to the vacuum induction melting furnace and evacuate to a vacuum level. The temperature was raised to 1180℃ to completely melt the copper particles. After holding at this temperature for 27 minutes, silver foil, rare earth element composite, and transition metal reinforcing phase were added sequentially. The stirring speed was 360 r / min, and the stirring time was 17 minutes. Subsequently, the nano-conductive reinforcing phase dispersion was sprayed into the melt through a high-pressure atomizing nozzle at an atomization pressure of 1.3 MPa, while simultaneously stirring at a high speed of 560 r / min for 14 minutes. The molten composite copper liquid was then poured into a hollow mold preheated to 340℃. The inner diameter of the mold was 25 mm, and the wall thickness was 6 mm. The casting speed is 0.9 kg / min, and the cooling rate is controlled at 90℃ / min. After complete solidification, the product is demolded to obtain a hollow copper billet. The induction coil frequency of the vacuum induction melting furnace is 250 kHz, and the power is 60 kW. During the casting process, a vibration crystallization device is used with a vibration frequency of 55 Hz and an amplitude of 0.1 mm. Vibration promotes the escape of bubbles in the melt, reduces the porosity defects inside the billet, and the porosity of the hollow copper billet is ≤0.01%. The outer diameter tolerance of the hollow copper billet is ±0.2 mm, and the wall thickness tolerance is ±0.1 mm. S3: The prepared hollow copper blank is placed in a plasma spraying equipment with argon as the protective gas and a gas flow rate of 18L / min. The antioxidant coating precursor solution is sprayed onto the inner and outer surfaces of the hollow copper blank at a spraying temperature of 240℃ and a coating thickness of 6μm. After spraying, the blank is kept at 280℃ for 2 hours to allow the precursor to fully solidify and form an antioxidant transition layer. The plasma arc voltage of the plasma spraying equipment is 67V, the current is 180A, and the spraying distance is 120mm. The surface roughness Ra of the antioxidant transition layer is ≤0.2μm, and the bonding strength with the hollow copper blank is ≥50MPa. S4: Employs a vertical multi-head wire drawing machine equipped with a dual-cavity die with a gradually decreasing inlet angle. The die's inlet angle gradually decreases from 18° to 12°, and the outlet angle is 4°. The die's inner bore is coated with a DLC (diamond-like carbon) coating with a thickness of 4μm. Before wire drawing, the hollow copper billet is preheated to 90℃. A high-pressure atomization lubrication system is used to spray oil-based lubricant at a pressure of 1.2MPa into the die inlet. The lubricant particle size is ≤5μm. The wire drawing process employs segmented speed control: the first stage drawing speed is 7m / s, with a single-pass area reduction rate of 17%; the second stage drawing speed is 14m / s, with a single-pass area reduction rate of 21%; the third stage drawing... The speed is 18 m / s, and the single-pass surface reduction rate is 24%. After each stretching section is completed, the outer diameter and wall thickness of the hollow copper wire are detected in real time using a laser diameter gauge and an ultrasonic thickness gauge. The oil-based lubricant consists of the following components: hydrogenated refined mineral oil, zinc dialkyl dithiophosphate, benzotriazole, polyoxyethylene castor oil, and polydimethylsiloxane. The kinematic viscosity of the lubricant at 40℃ is 25 mm² / s, the flash point is ≥200℃, the acid value is ≤0.5 mgKOH / g, the outer diameter detection accuracy is ±0.001 mm, and the wall thickness detection accuracy is ±0.002 mm. The tensile tension is adjusted based on the detection results, and the tension fluctuation is controlled within ±2%. S5: Intermediate annealing is performed between the second and third drawing stages. The copper wire drawn in the second stage is placed in a continuous annealing furnace, and a nitrogen-hydrogen mixed protective atmosphere is introduced, with a hydrogen content of 7%. The annealing temperature is 370℃, the holding time is 50 minutes, the heating rate is 7℃ / min, and the cooling rate is 4℃ / min. After annealing, the Vickers hardness of the copper wire is controlled at 86HV. The atmosphere pressure inside the continuous annealing furnace is 0.14MPa. A zoned temperature control method is adopted, and the temperature fluctuations in the heating zone, holding zone, and cooling zone are controlled within ±5℃, ±2℃, and ±3℃, respectively. After annealing, the copper wire is cooled to room temperature with an inert gas flow rate of 14m / s. S6: The hollow copper wires that have undergone the third stage of stretching are sequentially subjected to ultrasonic cleaning and hot air drying. The cleaning solution is an ethanol-deionized water mixture with a volume ratio of 1:3, and the cleaning time is 14 minutes. The drying temperature is 90℃, and the drying time is 7 minutes. After drying, the hollow copper wires are inspected to obtain hollow copper wires with low resistance. The outer diameter of the hollow copper wires is 4mm, the wall thickness is 0.25mm, and the resistivity at room temperature is [not specified]. Tensile strength ≥320MPa, and oxidation weight gain ≤0.05g / m² after 100 hours of constant temperature oxidation at 300℃.

[0019] Reference Figure 1 Example 2 This embodiment proposes a hollow copper wire with low resistance. The hollow copper wire is prepared by multiple stretching processes using a composite modified copper-based material as raw material. The composite modified copper-based material consists of the following components by weight percentage: 99.44% high-purity electrolytic copper, 0.25% silver, 0.008% rare earth element composite, 0.06% transition metal reinforcing phase, 0.04% nano-conductive reinforcing phase, and 0.20% antioxidant coating precursor, with the balance being unavoidable impurities. The rare earth element composite is a lanthanum-cerium-yttrium ternary alloy with a lanthanum, cerium, and yttrium weight ratio of 3:2:1; the transition metal reinforcing phase is a zirconium-niobium-titanium composite powder, in which zirconium accounts for no less than 50% by weight and niobium to titanium has a weight ratio of 1:1.2; the nano-conductive reinforcing phase is a carbon nanotube-graphene composite powder modified with silane coupling agent KH550, with a carbon nanotube to graphene mass ratio of 4:1 and a surface hydroxyl content of 1.1 mmol / g; the antioxidant coating precursor is a tetrabutyl titanate-silane coupling agent KH560-ethanol mixture, with a tetrabutyl titanate to KH560 molar ratio of 1:0.8. The amount of alcohol added is 4 times the mass of tetrabutyl titanate. The purity of the high-purity electrolytic copper is not less than 99.995%, and the weight content of impurity elements meets the following requirements: iron ≤ 0.0005%, lead ≤ 0.0003%, tin ≤ 0.0002%, sulfur ≤ 0.0001%, oxygen ≤ 0.0005%, and the individual content of other impurity elements ≤ 0.0001%, with a total impurity content ≤ 0.005%. The grain size of the high-purity electrolytic copper is 56μm, and the conductivity is ≥ 101% IACS. In the rare earth element complex, the purity of lanthanum is not less than 99.9%, the purity of cerium is not less than 99.9%, and the purity of yttrium is not less than 99.95%. The composite was added as follows: Lanthanum, cerium, and yttrium were mixed in a weight ratio of 3:2:1, melted at 880℃ for 25 minutes under an inert atmosphere, cooled, and then crushed to the specified particle size. The inert atmosphere was argon with a purity ≥99.999%. In the transition metal strengthening phase, the purity of zirconium was not less than 99.9%, the purity of niobium was not less than 99.9%, and the purity of titanium was not less than 99.8%. The ball milling treatment of the transition metal strengthening phase was carried out in a planetary ball mill with a ball-to-material ratio of 20:1, a ball milling speed of 350 r / min, and a ball milling time of 5 hours. Anhydrous ethanol was added as a dispersant during the ball milling process, and the amount of dispersant was the transition metal powder. The carbon nanotubes in the nano-conductive reinforcing phase, which account for 14% of the total mass, are ball-milled and dried in a vacuum drying oven at 70°C for 2 hours to remove the dispersant. The carbon nanotubes in the nano-conductive reinforcing phase are single-walled carbon nanotubes with a diameter of 2 nm, a length of 7 μm, and a purity of ≥98%. The graphene is a single-layer graphene with a sheet diameter of 1.2 μm and a purity of ≥99%. The amount of silane coupling agent KH550 added is 4% of the total mass of the carbon nanotube-graphene composite powder. The modification process is as follows: the carbon nanotube-graphene composite powder and KH550 are added to ethanol and stirred at 60-70°C for 2 hours. Then, the mixture is centrifuged, vacuum dried at 90°C for 5 hours. The manufacturing process of hollow copper wire includes the following steps: S1: High-purity electrolytic copper was crushed into copper particles with a particle size of 8 mm. After ultrasonic cleaning for 18 minutes, it was placed in a vacuum drying oven and dried at 130°C for 2 hours. The silver block was processed into silver foil with a thickness of 0.8 mm. The rare earth element composite was crushed into particles with a particle size of 1 mm. The transition metal strengthening phase was ball-milled to a particle size of 70 nm. The nano-conductive strengthening phase was added to ethanol and ultrasonically dispersed for 35 minutes to form a dispersion with a mass concentration of 7%. The components of the antioxidant coating precursor were mixed in proportion and stirred at 45°C for 80 minutes to prepare a stable precursor solution. S2: Add the pretreated copper granules to the vacuum induction melting furnace and evacuate to a vacuum level. The temperature was raised to 1180℃ to completely melt the copper particles. After holding at this temperature for 27 minutes, silver foil, rare earth element composite, and transition metal reinforcing phase were added sequentially. The stirring speed was 360 r / min, and the stirring time was 17 minutes. Subsequently, the nano-conductive reinforcing phase dispersion was sprayed into the melt through a high-pressure atomizing nozzle at an atomization pressure of 1.3 MPa, while simultaneously stirring at a high speed of 560 r / min for 14 minutes. The molten composite copper liquid was then poured into a hollow mold preheated to 340℃. The inner diameter of the mold was 25 mm, and the wall thickness was 6 mm. The casting speed is 0.9 kg / min, and the cooling rate is controlled at 90℃ / min. After complete solidification, the product is demolded to obtain a hollow copper billet. The induction coil frequency of the vacuum induction melting furnace is 250 kHz, and the power is 60 kW. During the casting process, a vibration crystallization device is used with a vibration frequency of 55 Hz and an amplitude of 0.1 mm. Vibration promotes the escape of bubbles in the melt, reduces the porosity defects inside the billet, and the porosity of the hollow copper billet is ≤0.01%. The outer diameter tolerance of the hollow copper billet is ±0.2 mm, and the wall thickness tolerance is ±0.1 mm. S3: The prepared hollow copper blank is placed in a plasma spraying equipment with argon as the protective gas and a gas flow rate of 18L / min. The antioxidant coating precursor solution is sprayed onto the inner and outer surfaces of the hollow copper blank at a spraying temperature of 240℃ and a coating thickness of 6μm. After spraying, the blank is kept at 280℃ for 2 hours to allow the precursor to fully solidify and form an antioxidant transition layer. The plasma arc voltage of the plasma spraying equipment is 67V, the current is 180A, and the spraying distance is 120mm. The surface roughness Ra of the antioxidant transition layer is ≤0.2μm, and the bonding strength with the hollow copper blank is ≥50MPa. S4: Employs a vertical multi-head wire drawing machine equipped with a dual-cavity die with a gradually decreasing inlet angle. The die's inlet angle gradually decreases from 18° to 12°, and the outlet angle is 4°. The die's inner bore is coated with a DLC (diamond-like carbon) coating with a thickness of 4μm. Before wire drawing, the hollow copper billet is preheated to 90℃. A high-pressure atomization lubrication system is used to spray oil-based lubricant at a pressure of 1.2MPa into the die inlet. The lubricant particle size is ≤5μm. The wire drawing process employs segmented speed control: the first stage drawing speed is 7m / s, with a single-pass area reduction rate of 17%; the second stage drawing speed is 14m / s, with a single-pass area reduction rate of 21%; the third stage drawing... The speed is 18 m / s, and the single-pass surface reduction rate is 24%. After each stretching section is completed, the outer diameter and wall thickness of the hollow copper wire are detected in real time using a laser diameter gauge and an ultrasonic thickness gauge. The oil-based lubricant consists of the following components: hydrogenated refined mineral oil, zinc dialkyl dithiophosphate, benzotriazole, polyoxyethylene castor oil, and polydimethylsiloxane. The kinematic viscosity of the lubricant at 40℃ is 25 mm² / s, the flash point is ≥200℃, the acid value is ≤0.5 mgKOH / g, the outer diameter detection accuracy is ±0.001 mm, and the wall thickness detection accuracy is ±0.002 mm. The tensile tension is adjusted based on the detection results, and the tension fluctuation is controlled within ±2%. S5: Intermediate annealing is performed between the second and third drawing stages. The copper wire drawn in the second stage is placed in a continuous annealing furnace, and a nitrogen-hydrogen mixed protective atmosphere is introduced, with a hydrogen content of 7%. The annealing temperature is 370℃, the holding time is 50 minutes, the heating rate is 7℃ / min, and the cooling rate is 4℃ / min. After annealing, the Vickers hardness of the copper wire is controlled at 86HV. The atmosphere pressure inside the continuous annealing furnace is 0.14MPa. A zoned temperature control method is adopted, and the temperature fluctuations in the heating zone, holding zone, and cooling zone are controlled within ±5℃, ±2℃, and ±3℃, respectively. After annealing, the copper wire is cooled to room temperature with an inert gas flow rate of 14m / s. S6: The hollow copper wires that have undergone the third stage of stretching are sequentially subjected to ultrasonic cleaning and hot air drying. The cleaning solution is an ethanol-deionized water mixture with a volume ratio of 1:3, and the cleaning time is 14 minutes. The drying temperature is 90℃, and the drying time is 7 minutes. After drying, the hollow copper wires are inspected to obtain hollow copper wires with low resistance. The outer diameter of the hollow copper wires is 4mm, the wall thickness is 0.25mm, and the resistivity at room temperature is [not specified]. Tensile strength ≥320MPa, and oxidation weight gain ≤0.05g / m² after 100 hours of constant temperature oxidation at 300℃.

[0020] Reference Figure 1 Example 3 This embodiment proposes a hollow copper wire with low resistance. The hollow copper wire is prepared by multiple stretching processes using a composite modified copper-based material as raw material. The composite modified copper-based material consists of the following components by weight percentage: 99.51% high-purity electrolytic copper, 0.21% silver, 0.009% rare earth element composite, 0.07% transition metal reinforcing phase, 0.05% nano-conductive reinforcing phase, and 0.15% antioxidant coating precursor, with the balance being unavoidable impurities. The rare earth element composite is a lanthanum-cerium-yttrium ternary alloy with a lanthanum, cerium, and yttrium weight ratio of 3:2:1; the transition metal reinforcing phase is a zirconium-niobium-titanium composite powder, in which zirconium accounts for no less than 50% by weight and niobium to titanium has a weight ratio of 1:1.2; the nano-conductive reinforcing phase is a carbon nanotube-graphene composite powder modified with silane coupling agent KH550, with a carbon nanotube to graphene mass ratio of 4:1 and a surface hydroxyl content of 1.1 mmol / g; the antioxidant coating precursor is a tetrabutyl titanate-silane coupling agent KH560-ethanol mixture, with a tetrabutyl titanate to KH560 molar ratio of 1:0.8. The amount of alcohol added is 4 times the mass of tetrabutyl titanate. The purity of the high-purity electrolytic copper is not less than 99.995%, and the weight content of impurity elements meets the following requirements: iron ≤ 0.0005%, lead ≤ 0.0003%, tin ≤ 0.0002%, sulfur ≤ 0.0001%, oxygen ≤ 0.0005%, and the individual content of other impurity elements ≤ 0.0001%, with a total impurity content ≤ 0.005%. The grain size of the high-purity electrolytic copper is 56μm, and the conductivity is ≥ 101% IACS. In the rare earth element complex, the purity of lanthanum is not less than 99.9%, the purity of cerium is not less than 99.9%, and the purity of yttrium is not less than 99.95%. The composite was added as follows: Lanthanum, cerium, and yttrium were mixed in a weight ratio of 3:2:1, melted at 880℃ for 25 minutes under an inert atmosphere, cooled, and then crushed to the specified particle size. The inert atmosphere was argon with a purity ≥99.999%. In the transition metal strengthening phase, the purity of zirconium was not less than 99.9%, the purity of niobium was not less than 99.9%, and the purity of titanium was not less than 99.8%. The ball milling treatment of the transition metal strengthening phase was carried out in a planetary ball mill with a ball-to-material ratio of 20:1, a ball milling speed of 350 r / min, and a ball milling time of 5 hours. Anhydrous ethanol was added as a dispersant during the ball milling process, and the amount of dispersant was the transition metal powder. The carbon nanotubes in the nano-conductive reinforcing phase, which account for 14% of the total mass, are ball-milled and dried in a vacuum drying oven at 70°C for 2 hours to remove the dispersant. The carbon nanotubes in the nano-conductive reinforcing phase are single-walled carbon nanotubes with a diameter of 2 nm, a length of 7 μm, and a purity of ≥98%. The graphene is a single-layer graphene with a sheet diameter of 1.2 μm and a purity of ≥99%. The amount of silane coupling agent KH550 added is 4% of the total mass of the carbon nanotube-graphene composite powder. The modification process is as follows: the carbon nanotube-graphene composite powder and KH550 are added to ethanol and stirred at 60-70°C for 2 hours. Then, the mixture is centrifuged, vacuum dried at 90°C for 5 hours. The manufacturing process of hollow copper wire includes the following steps: S1: High-purity electrolytic copper was crushed into copper particles with a particle size of 8 mm. After ultrasonic cleaning for 18 minutes, it was placed in a vacuum drying oven and dried at 130°C for 2 hours. The silver block was processed into silver foil with a thickness of 0.8 mm. The rare earth element composite was crushed into particles with a particle size of 1 mm. The transition metal strengthening phase was ball-milled to a particle size of 70 nm. The nano-conductive strengthening phase was added to ethanol and ultrasonically dispersed for 35 minutes to form a dispersion with a mass concentration of 7%. The components of the antioxidant coating precursor were mixed in proportion and stirred at 45°C for 80 minutes to prepare a stable precursor solution. S2: Add the pretreated copper granules to the vacuum induction melting furnace and evacuate to a vacuum level. The temperature was raised to 1180℃ to completely melt the copper particles. After holding at this temperature for 27 minutes, silver foil, rare earth element composite, and transition metal reinforcing phase were added sequentially. The stirring speed was 360 r / min, and the stirring time was 17 minutes. Subsequently, the nano-conductive reinforcing phase dispersion was sprayed into the melt through a high-pressure atomizing nozzle at an atomization pressure of 1.3 MPa, while simultaneously stirring at a high speed of 560 r / min for 14 minutes. The molten composite copper liquid was then poured into a hollow mold preheated to 340℃. The inner diameter of the mold was 25 mm, and the wall thickness was 6 mm. The casting speed is 0.9 kg / min, and the cooling rate is controlled at 90℃ / min. After complete solidification, the product is demolded to obtain a hollow copper billet. The induction coil frequency of the vacuum induction melting furnace is 250 kHz, and the power is 60 kW. During the casting process, a vibration crystallization device is used with a vibration frequency of 55 Hz and an amplitude of 0.1 mm. Vibration promotes the escape of bubbles in the melt, reduces the porosity defects inside the billet, and the porosity of the hollow copper billet is ≤0.01%. The outer diameter tolerance of the hollow copper billet is ±0.2 mm, and the wall thickness tolerance is ±0.1 mm. S3: The prepared hollow copper blank is placed in a plasma spraying equipment with argon as the protective gas and a gas flow rate of 18L / min. The antioxidant coating precursor solution is sprayed onto the inner and outer surfaces of the hollow copper blank at a spraying temperature of 240℃ and a coating thickness of 6μm. After spraying, the blank is kept at 280℃ for 2 hours to allow the precursor to fully solidify and form an antioxidant transition layer. The plasma arc voltage of the plasma spraying equipment is 67V, the current is 180A, and the spraying distance is 120mm. The surface roughness Ra of the antioxidant transition layer is ≤0.2μm, and the bonding strength with the hollow copper blank is ≥50MPa. S4: Employs a vertical multi-head wire drawing machine equipped with a dual-cavity die with a gradually decreasing inlet angle. The die's inlet angle gradually decreases from 18° to 12°, and the outlet angle is 4°. The die's inner bore is coated with a DLC (diamond-like carbon) coating with a thickness of 4μm. Before wire drawing, the hollow copper billet is preheated to 90℃. A high-pressure atomization lubrication system is used to spray oil-based lubricant at a pressure of 1.2MPa into the die inlet. The lubricant particle size is ≤5μm. The wire drawing process employs segmented speed control: the first stage drawing speed is 7m / s, with a single-pass area reduction rate of 17%; the second stage drawing speed is 14m / s, with a single-pass area reduction rate of 21%; the third stage drawing... The speed is 18 m / s, and the single-pass surface reduction rate is 24%. After each stretching section is completed, the outer diameter and wall thickness of the hollow copper wire are detected in real time using a laser diameter gauge and an ultrasonic thickness gauge. The oil-based lubricant consists of the following components: hydrogenated refined mineral oil, zinc dialkyl dithiophosphate, benzotriazole, polyoxyethylene castor oil, and polydimethylsiloxane. The kinematic viscosity of the lubricant at 40℃ is 25 mm² / s, the flash point is ≥200℃, the acid value is ≤0.5 mgKOH / g, the outer diameter detection accuracy is ±0.001 mm, and the wall thickness detection accuracy is ±0.002 mm. The tensile tension is adjusted based on the detection results, and the tension fluctuation is controlled within ±2%. S5: Intermediate annealing is performed between the second and third drawing stages. The copper wire drawn in the second stage is placed in a continuous annealing furnace, and a nitrogen-hydrogen mixed protective atmosphere is introduced, with a hydrogen content of 7%. The annealing temperature is 370℃, the holding time is 50 minutes, the heating rate is 7℃ / min, and the cooling rate is 4℃ / min. After annealing, the Vickers hardness of the copper wire is controlled at 86HV. The atmosphere pressure inside the continuous annealing furnace is 0.14MPa. A zoned temperature control method is adopted, and the temperature fluctuations in the heating zone, holding zone, and cooling zone are controlled within ±5℃, ±2℃, and ±3℃, respectively. After annealing, the copper wire is cooled to room temperature with an inert gas flow rate of 14m / s. S6: The hollow copper wires that have undergone the third stage of stretching are sequentially subjected to ultrasonic cleaning and hot air drying. The cleaning solution is an ethanol-deionized water mixture with a volume ratio of 1:3, and the cleaning time is 14 minutes. The drying temperature is 90℃, and the drying time is 7 minutes. After drying, the hollow copper wires are inspected to obtain hollow copper wires with low resistance. The outer diameter of the hollow copper wires is 4mm, the wall thickness is 0.25mm, and the resistivity at room temperature is [not specified]. Tensile strength ≥320MPa, and oxidation weight gain ≤0.05g / m² after 100 hours of constant temperature oxidation at 300℃.

[0021] Reference Figure 1 Example 4 This embodiment proposes a hollow copper wire with low resistance. The hollow copper wire is prepared by multiple stretching processes using a composite modified copper-based material as raw material. The composite modified copper-based material consists of the following components by weight percentage: 99.49% high-purity electrolytic copper, 0.23% silver, 0.006% rare earth element composite, 0.04% transition metal reinforcing phase, 0.03% nano-conductive reinforcing phase, and 0.20% antioxidant coating precursor, with the balance being unavoidable impurities. The rare earth element composite is a lanthanum-cerium-yttrium ternary alloy with a lanthanum, cerium, and yttrium weight ratio of 3:2:1; the transition metal reinforcing phase is a zirconium-niobium-titanium composite powder, in which zirconium accounts for no less than 50% by weight and niobium to titanium has a weight ratio of 1:1.2; the nano-conductive reinforcing phase is a carbon nanotube-graphene composite powder modified with silane coupling agent KH550, with a carbon nanotube to graphene mass ratio of 4:1 and a surface hydroxyl content of 1.1 mmol / g; the antioxidant coating precursor is a tetrabutyl titanate-silane coupling agent KH560-ethanol mixture, with a tetrabutyl titanate to KH560 molar ratio of 1:0.8. The amount of alcohol added is 4 times the mass of tetrabutyl titanate. The purity of the high-purity electrolytic copper is not less than 99.995%, and the weight content of impurity elements meets the following requirements: iron ≤ 0.0005%, lead ≤ 0.0003%, tin ≤ 0.0002%, sulfur ≤ 0.0001%, oxygen ≤ 0.0005%, and the individual content of other impurity elements ≤ 0.0001%, with a total impurity content ≤ 0.005%. The grain size of the high-purity electrolytic copper is 56μm, and the conductivity is ≥ 101% IACS. In the rare earth element complex, the purity of lanthanum is not less than 99.9%, the purity of cerium is not less than 99.9%, and the purity of yttrium is not less than 99.95%. The composite was added as follows: Lanthanum, cerium, and yttrium were mixed in a weight ratio of 3:2:1, melted at 880℃ for 25 minutes under an inert atmosphere, cooled, and then crushed to the specified particle size. The inert atmosphere was argon with a purity ≥99.999%. In the transition metal strengthening phase, the purity of zirconium was not less than 99.9%, the purity of niobium was not less than 99.9%, and the purity of titanium was not less than 99.8%. The ball milling treatment of the transition metal strengthening phase was carried out in a planetary ball mill with a ball-to-material ratio of 20:1, a ball milling speed of 350 r / min, and a ball milling time of 5 hours. Anhydrous ethanol was added as a dispersant during the ball milling process, and the amount of dispersant was the transition metal powder. The carbon nanotubes in the nano-conductive reinforcing phase, which account for 14% of the total mass, are ball-milled and dried in a vacuum drying oven at 70°C for 2 hours to remove the dispersant. The carbon nanotubes in the nano-conductive reinforcing phase are single-walled carbon nanotubes with a diameter of 2 nm, a length of 7 μm, and a purity of ≥98%. The graphene is a single-layer graphene with a sheet diameter of 1.2 μm and a purity of ≥99%. The amount of silane coupling agent KH550 added is 4% of the total mass of the carbon nanotube-graphene composite powder. The modification process is as follows: the carbon nanotube-graphene composite powder and KH550 are added to ethanol and stirred at 60-70°C for 2 hours. Then, the mixture is centrifuged, vacuum dried at 90°C for 5 hours. The manufacturing process of hollow copper wire includes the following steps: S1: High-purity electrolytic copper was crushed into copper particles with a particle size of 8 mm. After ultrasonic cleaning for 18 minutes, it was placed in a vacuum drying oven and dried at 130°C for 2 hours. The silver block was processed into silver foil with a thickness of 0.8 mm. The rare earth element composite was crushed into particles with a particle size of 1 mm. The transition metal strengthening phase was ball-milled to a particle size of 70 nm. The nano-conductive strengthening phase was added to ethanol and ultrasonically dispersed for 35 minutes to form a dispersion with a mass concentration of 7%. The components of the antioxidant coating precursor were mixed in proportion and stirred at 45°C for 80 minutes to prepare a stable precursor solution. S2: Add the pretreated copper granules to the vacuum induction melting furnace and evacuate to a vacuum level. The temperature was raised to 1180℃ to completely melt the copper particles. After holding at this temperature for 27 minutes, silver foil, rare earth element composite, and transition metal reinforcing phase were added sequentially. The stirring speed was 360 r / min, and the stirring time was 17 minutes. Subsequently, the nano-conductive reinforcing phase dispersion was sprayed into the melt through a high-pressure atomizing nozzle at an atomization pressure of 1.3 MPa, while simultaneously stirring at a high speed of 560 r / min for 14 minutes. The molten composite copper liquid was then poured into a hollow mold preheated to 340℃. The inner diameter of the mold was 25 mm, and the wall thickness was 6 mm. The casting speed is 0.9 kg / min, and the cooling rate is controlled at 90℃ / min. After complete solidification, the product is demolded to obtain a hollow copper billet. The induction coil frequency of the vacuum induction melting furnace is 250 kHz, and the power is 60 kW. During the casting process, a vibration crystallization device is used with a vibration frequency of 55 Hz and an amplitude of 0.1 mm. Vibration promotes the escape of bubbles in the melt, reduces the porosity defects inside the billet, and the porosity of the hollow copper billet is ≤0.01%. The outer diameter tolerance of the hollow copper billet is ±0.2 mm, and the wall thickness tolerance is ±0.1 mm. S3: The prepared hollow copper blank is placed in a plasma spraying equipment with argon as the protective gas and a gas flow rate of 18L / min. The antioxidant coating precursor solution is sprayed onto the inner and outer surfaces of the hollow copper blank at a spraying temperature of 240℃ and a coating thickness of 6μm. After spraying, the blank is kept at 280℃ for 2 hours to allow the precursor to fully solidify and form an antioxidant transition layer. The plasma arc voltage of the plasma spraying equipment is 67V, the current is 180A, and the spraying distance is 120mm. The surface roughness Ra of the antioxidant transition layer is ≤0.2μm, and the bonding strength with the hollow copper blank is ≥50MPa. S4: Employs a vertical multi-head wire drawing machine equipped with a dual-cavity die with a gradually decreasing inlet angle. The die's inlet angle gradually decreases from 18° to 12°, and the outlet angle is 4°. The die's inner bore is coated with a DLC (diamond-like carbon) coating with a thickness of 4μm. Before wire drawing, the hollow copper billet is preheated to 90℃. A high-pressure atomization lubrication system is used to spray oil-based lubricant at a pressure of 1.2MPa into the die inlet. The lubricant particle size is ≤5μm. The wire drawing process employs segmented speed control: the first stage drawing speed is 7m / s, with a single-pass area reduction rate of 17%; the second stage drawing speed is 14m / s, with a single-pass area reduction rate of 21%; the third stage drawing... The speed is 18 m / s, and the single-pass surface reduction rate is 24%. After each stretching section is completed, the outer diameter and wall thickness of the hollow copper wire are detected in real time using a laser diameter gauge and an ultrasonic thickness gauge. The oil-based lubricant consists of the following components: hydrogenated refined mineral oil, zinc dialkyl dithiophosphate, benzotriazole, polyoxyethylene castor oil, and polydimethylsiloxane. The kinematic viscosity of the lubricant at 40℃ is 25 mm² / s, the flash point is ≥200℃, the acid value is ≤0.5 mgKOH / g, the outer diameter detection accuracy is ±0.001 mm, and the wall thickness detection accuracy is ±0.002 mm. The tensile tension is adjusted based on the detection results, and the tension fluctuation is controlled within ±2%. S5: Intermediate annealing is performed between the second and third drawing stages. The copper wire drawn in the second stage is placed in a continuous annealing furnace, and a nitrogen-hydrogen mixed protective atmosphere is introduced, with a hydrogen content of 7%. The annealing temperature is 370℃, the holding time is 50 minutes, the heating rate is 7℃ / min, and the cooling rate is 4℃ / min. After annealing, the Vickers hardness of the copper wire is controlled at 86HV. The atmosphere pressure inside the continuous annealing furnace is 0.14MPa. A zoned temperature control method is adopted, and the temperature fluctuations in the heating zone, holding zone, and cooling zone are controlled within ±5℃, ±2℃, and ±3℃, respectively. After annealing, the copper wire is cooled to room temperature with an inert gas flow rate of 14m / s. S6: The hollow copper wires that have undergone the third stage of stretching are sequentially subjected to ultrasonic cleaning and hot air drying. The cleaning solution is an ethanol-deionized water mixture with a volume ratio of 1:3, and the cleaning time is 14 minutes. The drying temperature is 90℃, and the drying time is 7 minutes. After drying, the hollow copper wires are inspected to obtain hollow copper wires with low resistance. The outer diameter of the hollow copper wires is 4mm, the wall thickness is 0.25mm, and the resistivity at room temperature is [not specified]. Tensile strength ≥320MPa, and oxidation weight gain ≤0.05g / m² after 100 hours of constant temperature oxidation at 300℃.

[0022] Reference Figure 1 Example 5 This embodiment proposes a hollow copper wire with low resistance. The hollow copper wire is prepared by multiple stretching processes using a composite modified copper-based material as raw material. The composite modified copper-based material consists of the following components by weight percentage: 99.385% high-purity electrolytic copper, 0.30% silver, 0.01% rare earth element composite, 0.06% transition metal reinforcing phase, 0.04% nano-conductive reinforcing phase, and 0.20% antioxidant coating precursor, with the balance being unavoidable impurities. The rare earth element composite is a lanthanum-cerium-yttrium ternary alloy with a lanthanum, cerium, and yttrium weight ratio of 3:2:1; the transition metal reinforcing phase is a zirconium-niobium-titanium composite powder, in which zirconium accounts for no less than 50% by weight and niobium to titanium has a weight ratio of 1:1.2; the nano-conductive reinforcing phase is a carbon nanotube-graphene composite powder modified with silane coupling agent KH550, with a carbon nanotube to graphene mass ratio of 4:1 and a surface hydroxyl content of 1.1 mmol / g; the antioxidant coating precursor is a tetrabutyl titanate-silane coupling agent KH560-ethanol mixture, with a tetrabutyl titanate to KH560 molar ratio of 1:0.8. The amount of alcohol added is 4 times the mass of tetrabutyl titanate. The purity of the high-purity electrolytic copper is not less than 99.995%, and the weight content of impurity elements meets the following requirements: iron ≤ 0.0005%, lead ≤ 0.0003%, tin ≤ 0.0002%, sulfur ≤ 0.0001%, oxygen ≤ 0.0005%, and the individual content of other impurity elements ≤ 0.0001%, with a total impurity content ≤ 0.005%. The grain size of the high-purity electrolytic copper is 56μm, and the conductivity is ≥ 101% IACS. In the rare earth element complex, the purity of lanthanum is not less than 99.9%, the purity of cerium is not less than 99.9%, and the purity of yttrium is not less than 99.95%. The composite was added as follows: Lanthanum, cerium, and yttrium were mixed in a weight ratio of 3:2:1, melted at 880℃ for 25 minutes under an inert atmosphere, cooled, and then crushed to the specified particle size. The inert atmosphere was argon with a purity ≥99.999%. In the transition metal strengthening phase, the purity of zirconium was not less than 99.9%, the purity of niobium was not less than 99.9%, and the purity of titanium was not less than 99.8%. The ball milling treatment of the transition metal strengthening phase was carried out in a planetary ball mill with a ball-to-material ratio of 20:1, a ball milling speed of 350 r / min, and a ball milling time of 5 hours. Anhydrous ethanol was added as a dispersant during the ball milling process, and the amount of dispersant was the transition metal powder. The carbon nanotubes in the nano-conductive reinforcing phase, which account for 14% of the total mass, are ball-milled and dried in a vacuum drying oven at 70°C for 2 hours to remove the dispersant. The carbon nanotubes in the nano-conductive reinforcing phase are single-walled carbon nanotubes with a diameter of 2 nm, a length of 7 μm, and a purity of ≥98%. The graphene is a single-layer graphene with a sheet diameter of 1.2 μm and a purity of ≥99%. The amount of silane coupling agent KH550 added is 4% of the total mass of the carbon nanotube-graphene composite powder. The modification process is as follows: the carbon nanotube-graphene composite powder and KH550 are added to ethanol and stirred at 60-70°C for 2 hours. Then, the mixture is centrifuged, vacuum dried at 90°C for 5 hours. The manufacturing process of hollow copper wire includes the following steps: S1: High-purity electrolytic copper was crushed into copper particles with a particle size of 8 mm. After ultrasonic cleaning for 18 minutes, it was placed in a vacuum drying oven and dried at 130°C for 2 hours. The silver block was processed into silver foil with a thickness of 0.8 mm. The rare earth element composite was crushed into particles with a particle size of 1 mm. The transition metal strengthening phase was ball-milled to a particle size of 70 nm. The nano-conductive strengthening phase was added to ethanol and ultrasonically dispersed for 35 minutes to form a dispersion with a mass concentration of 7%. The components of the antioxidant coating precursor were mixed in proportion and stirred at 45°C for 80 minutes to prepare a stable precursor solution. S2: Add the pretreated copper granules to the vacuum induction melting furnace and evacuate to a vacuum level. The temperature was raised to 1180℃ to completely melt the copper particles. After holding at this temperature for 27 minutes, silver foil, rare earth element composite, and transition metal reinforcing phase were added sequentially. The stirring speed was 360 r / min, and the stirring time was 17 minutes. Subsequently, the nano-conductive reinforcing phase dispersion was sprayed into the melt through a high-pressure atomizing nozzle at an atomization pressure of 1.3 MPa, while simultaneously stirring at a high speed of 560 r / min for 14 minutes. The molten composite copper liquid was then poured into a hollow mold preheated to 340℃. The inner diameter of the mold was 25 mm, and the wall thickness was 6 mm. The casting speed is 0.9 kg / min, and the cooling rate is controlled at 90℃ / min. After complete solidification, the product is demolded to obtain a hollow copper billet. The induction coil frequency of the vacuum induction melting furnace is 250 kHz, and the power is 60 kW. During the casting process, a vibration crystallization device is used with a vibration frequency of 55 Hz and an amplitude of 0.1 mm. Vibration promotes the escape of bubbles in the melt, reduces the porosity defects inside the billet, and the porosity of the hollow copper billet is ≤0.01%. The outer diameter tolerance of the hollow copper billet is ±0.2 mm, and the wall thickness tolerance is ±0.1 mm. S3: The prepared hollow copper blank is placed in a plasma spraying equipment with argon as the protective gas and a gas flow rate of 18L / min. The antioxidant coating precursor solution is sprayed onto the inner and outer surfaces of the hollow copper blank at a spraying temperature of 240℃ and a coating thickness of 6μm. After spraying, the blank is kept at 280℃ for 2 hours to allow the precursor to fully solidify and form an antioxidant transition layer. The plasma arc voltage of the plasma spraying equipment is 67V, the current is 180A, and the spraying distance is 120mm. The surface roughness Ra of the antioxidant transition layer is ≤0.2μm, and the bonding strength with the hollow copper blank is ≥50MPa. S4: Employs a vertical multi-head wire drawing machine equipped with a dual-cavity die with a gradually decreasing inlet angle. The die's inlet angle gradually decreases from 18° to 12°, and the outlet angle is 4°. The die's inner bore is coated with a DLC (diamond-like carbon) coating with a thickness of 4μm. Before wire drawing, the hollow copper billet is preheated to 90℃. A high-pressure atomization lubrication system is used to spray oil-based lubricant at a pressure of 1.2MPa into the die inlet. The lubricant particle size is ≤5μm. The wire drawing process employs segmented speed control: the first stage drawing speed is 7m / s, with a single-pass area reduction rate of 17%; the second stage drawing speed is 14m / s, with a single-pass area reduction rate of 21%; the third stage drawing... The speed is 18 m / s, and the single-pass surface reduction rate is 24%. After each stretching section is completed, the outer diameter and wall thickness of the hollow copper wire are detected in real time using a laser diameter gauge and an ultrasonic thickness gauge. The oil-based lubricant consists of the following components: hydrogenated refined mineral oil, zinc dialkyl dithiophosphate, benzotriazole, polyoxyethylene castor oil, and polydimethylsiloxane. The kinematic viscosity of the lubricant at 40℃ is 25 mm² / s, the flash point is ≥200℃, the acid value is ≤0.5 mgKOH / g, the outer diameter detection accuracy is ±0.001 mm, and the wall thickness detection accuracy is ±0.002 mm. The tensile tension is adjusted based on the detection results, and the tension fluctuation is controlled within ±2%. S5: Intermediate annealing is performed between the second and third drawing stages. The copper wire drawn in the second stage is placed in a continuous annealing furnace, and a nitrogen-hydrogen mixed protective atmosphere is introduced, with a hydrogen content of 7%. The annealing temperature is 370℃, the holding time is 50 minutes, the heating rate is 7℃ / min, and the cooling rate is 4℃ / min. After annealing, the Vickers hardness of the copper wire is controlled at 86HV. The atmosphere pressure inside the continuous annealing furnace is 0.14MPa. A zoned temperature control method is adopted, and the temperature fluctuations in the heating zone, holding zone, and cooling zone are controlled within ±5℃, ±2℃, and ±3℃, respectively. After annealing, the copper wire is cooled to room temperature with an inert gas flow rate of 14m / s. S6: The hollow copper wires that have undergone the third stage of stretching are sequentially subjected to ultrasonic cleaning and hot air drying. The cleaning solution is an ethanol-deionized water mixture with a volume ratio of 1:3, and the cleaning time is 14 minutes. The drying temperature is 90℃, and the drying time is 7 minutes. After drying, the hollow copper wires are inspected to obtain hollow copper wires with low resistance. The outer diameter of the hollow copper wires is 4mm, the wall thickness is 0.25mm, and the resistivity at room temperature is [not specified]. Tensile strength ≥320MPa, and oxidation weight gain ≤0.05g / m² after 100 hours of constant temperature oxidation at 300℃.

[0023] The hollow copper wires obtained in Examples 1 to 5 are compared with those obtained by conventional hollow copper wire drawing. The hollow copper wires obtained in Examples 1 to 5 are shown in the table below:

[0024] As can be seen from the table above, the hollow copper wire produced by this invention has significantly improved production efficiency and product performance.

[0025] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A hollow copper wire with low resistance, characterized in that, The hollow copper wire is prepared by multiple stretching passes using a composite modified copper-based material as raw material. The composite modified copper-based material consists of the following components by weight percentage: 98.50%–99.70% high-purity electrolytic copper, 0.05%–0.30% silver, 0.001%–0.01% rare earth element composite, 0.02%–0.08% transition metal reinforcing phase, 0.01%–0.05% nano-conductive reinforcing phase, and 0.10%–0.20% antioxidant coating precursor, with the balance being unavoidable impurities. The rare earth element composite is a lanthanum-cerium-yttrium ternary alloy with a lanthanum, cerium, and yttrium weight ratio of 3:2:1; the transition metal reinforcing phase is a zirconium-niobium-titanium composite powder, in which zirconium accounts for no less than 50% by weight and niobium to titanium has a weight ratio of 1:1.2; the nano-conductive reinforcing phase is a carbon nanotube-graphene composite powder modified with silane coupling agent KH550, with a carbon nanotube to graphene mass ratio of 4:1 and the modified powder surface hydroxyl content of 0.8–1.2 mmol / g; the antioxidant coating precursor is a tetrabutyl titanate-silane coupling agent KH560-ethanol mixture system, with a tetrabutyl titanate to KH560 molar ratio of 1:0.8 and the amount of ethanol added being 3–5 times the mass of tetrabutyl titanate; The manufacturing process of hollow copper wire includes the following steps: S1: High-purity electrolytic copper is crushed into copper particles with a particle size of 5-10 mm, ultrasonically cleaned for 15-20 minutes, and then placed in a vacuum drying oven and dried at 120-150℃ for 2-3 hours. Silver blocks are processed into silver foil with a thickness of 0.5-1 mm. Rare earth element composites are crushed into particles with a particle size of 1-2 mm. The transition metal strengthening phase is ball-milled to a particle size of 50-100 nm. The nano-conductive strengthening phase is added to ethanol and ultrasonically dispersed for 30-40 minutes to form a dispersion with a mass concentration of 5%-8%. The components of the antioxidant coating precursor are mixed in proportion and stirred at 40-50℃ for 60-90 minutes to prepare a stable precursor solution. S2: Add the pretreated copper granules to the vacuum induction melting furnace and evacuate to a vacuum level. The temperature is raised to 1150–1200℃ to completely melt the copper particles. After holding at this temperature for 20–30 minutes, silver foil, rare earth element composite, and transition metal reinforcing phase are added sequentially. The stirring speed is 300–400 r / min, and the stirring time is 15–20 minutes. Then, the nano-conductive reinforcing phase dispersion is sprayed into the melt through a high-pressure atomizing nozzle at an atomization pressure of 1.2–1.5 MPa, while stirring at a high speed of 500–600 r / min for 10–15 minutes. The molten composite copper liquid is then poured into a hollow mold preheated to 300–350℃. The inner diameter of the mold is 20–30 mm, the wall thickness is 5–8 mm, the casting speed is 0.8–1.2 kg / min, and the cooling rate is controlled at 80–100℃ / min. After complete solidification, the mold is demolded to obtain a hollow copper billet. S3: Place the prepared hollow copper billet in a plasma spraying equipment, use argon as the protective gas, and spray the anti-oxidation coating precursor solution onto the inner and outer surfaces of the hollow copper billet. The spraying temperature is 200-250℃, and the coating thickness is controlled to be 5-10μm. After spraying, keep it at 280-300℃ for 1-2 hours to allow the precursor to fully solidify and form an anti-oxidation transition layer. S4: Employs a vertical multi-head wire drawing machine equipped with a dual-cavity die with a gradually decreasing inlet angle. The inlet angle of the die gradually decreases from 18° to 12°, and the outlet angle is 3-4°. The inner hole of the die is coated with a DLC (diamond-like carbon) coating with a thickness of 3-5μm. Before wire drawing, the hollow copper billet is preheated at 80-100℃. Simultaneously, a high-pressure atomization lubrication system is used to spray oil-based lubricant at a pressure of 1.0-1.2MPa into the die inlet. The lubricant particle size is ≤5μm. The wire drawing process adopts segmented speed control. The first stage of drawing speed is 6-8m / s, with a single-pass surface reduction rate of 15%-18%; the second stage of drawing speed is 12-15m / s, with a single-pass surface reduction rate of 20%-22%; and the third stage of drawing speed is 18-20m / s, with a single-pass surface reduction rate of 23%-25%. After each stage of drawing is completed, the outer diameter and wall thickness of the hollow copper wire are detected in real time using a laser diameter gauge and an ultrasonic thickness gauge. S5: Intermediate annealing is performed between the second and third drawing stages. The copper wire that has been drawn in the second stage is placed in a continuous annealing furnace and a nitrogen-hydrogen mixed protective atmosphere is introduced, wherein the hydrogen content is 5% to 8%, the annealing temperature is 350 to 400℃, the holding time is 40 to 60 minutes, the heating rate is 5 to 8℃ / min, the cooling rate is 3 to 5℃ / min, and the Vickers hardness of the copper wire after annealing is controlled at 80 to 90 HV. S6: The hollow copper wire that has been stretched in the third stage is subjected to ultrasonic cleaning and hot air drying in sequence. The cleaning solution is a mixture of ethanol and deionized water with a volume ratio of 1:

3. The cleaning time is 10 to 15 minutes, the drying temperature is 80 to 100℃, and the drying time is 5 to 8 minutes. After drying, the hollow copper wire is tested as a finished product to finally obtain hollow copper wire with low resistance.

2. The hollow copper wire with low resistance according to claim 1, characterized in that, The high-purity electrolytic copper has a purity of not less than 99.995%, wherein the weight content of impurity elements meets the following requirements: iron ≤ 0.0005%, lead ≤ 0.0003%, tin ≤ 0.0002%, sulfur ≤ 0.0001%, oxygen ≤ 0.0005%, the individual content of other impurity elements ≤ 0.0001%, and the total impurity content ≤ 0.005%. The high-purity electrolytic copper has a grain size of 50-80 μm and a conductivity ≥ 101% IACS.

3. The hollow copper wire with low resistance according to claim 1, characterized in that, In the rare earth element complex, the purity of lanthanum is not less than 99.9%, the purity of cerium is not less than 99.9%, and the purity of yttrium is not less than 99.95%. The rare earth element complex is added as follows: lanthanum, cerium, and yttrium are mixed in a weight ratio of 3:2:1, then melted at 800-900℃ for 20-30 minutes under an inert atmosphere, cooled, and crushed to a specified particle size. The inert atmosphere is argon, and the gas purity is ≥99.999%.

4. The hollow copper wire with low resistance according to claim 1, characterized in that, In the transition metal strengthening phase, the purity of zirconium is not less than 99.9%, the purity of niobium is not less than 99.9%, and the purity of titanium is not less than 99.8%. The ball milling treatment of the transition metal strengthening phase is carried out in a planetary ball mill with a ball-to-material ratio of 20:1, a ball milling speed of 300-400 r / min, and a ball milling time of 4-6 hours. Anhydrous ethanol is added as a dispersant during the ball milling process, and the amount of dispersant is 10%-15% of the total mass of the transition metal powder. After ball milling, the phase is dried in a vacuum drying oven at 60-80℃ for 2-3 hours to remove the dispersant.

5. A hollow copper wire with low resistance according to claim 1, characterized in that, The carbon nanotubes in the nano-conductive reinforcing phase are single-walled carbon nanotubes with a diameter of 1–3 nm, a length of 5–10 μm, and a purity ≥98%; the graphene is single-layer graphene with a sheet diameter of 0.5–2 μm and a purity ≥99%; the amount of silane coupling agent KH550 added is 3%–5% of the total mass of the carbon nanotube-graphene composite powder. The modification process is as follows: the carbon nanotube-graphene composite powder and KH550 are added to ethanol, stirred and reacted at 60–70 °C for 2–3 hours, followed by centrifugation and vacuum drying at 80–100 °C for 4–6 hours.

6. The preparation process of hollow copper wire with low resistance according to claim 1, characterized in that, In S2, the induction coil frequency of the vacuum induction melting furnace is 200-300kHz and the power is 50-80kW; a vibration crystallization device is used during the casting process, with a vibration frequency of 50-60Hz and an amplitude of 0.1-0.2mm. Vibration promotes the escape of bubbles in the melt and reduces the porosity defects inside the billet. The porosity of the hollow copper billet is ≤0.01%, the outer diameter tolerance of the hollow copper billet is ±0.2mm, and the wall thickness tolerance is ±0.1mm.

7. The preparation process of hollow copper wire with low resistance according to claim 1, characterized in that, In S3, the plasma arc voltage of the plasma spraying equipment is 60-80V, the current is 150-200A, and the spraying distance is 100-150mm; the surface roughness Ra of the anti-oxidation transition layer is ≤0.2μm, and the bonding strength with the hollow copper blank is ≥50MPa.

8. The preparation process of hollow copper wire with low resistance according to claim 1, characterized in that, In S4, the oil-based lubricant is composed of the following components: hydrotreated mineral oil, zinc dialkyl dithiophosphate, benzotriazole, polyoxyethylene castor oil, and polydimethylsiloxane; the kinematic viscosity of the lubricant at 40°C is 20-30 mm² / s, the flash point is ≥200°C, the acid value is ≤0.5 mg KOH / g, the outer diameter detection accuracy is ±0.001 mm, the wall thickness detection accuracy is ±0.002 mm, and the tensile tension is adjusted based on the detection results, with tension fluctuation controlled within ±2%.

9. The manufacturing process of hollow copper wire with low resistance according to claim 1, characterized in that, In S5, the furnace atmosphere pressure of the continuous annealing furnace is 0.12 to 0.15 MPa, and a zoned temperature control method is adopted. The temperature fluctuations of the heating zone, the holding zone, and the cooling zone are controlled within ±5℃, ±2℃, and ±3℃, respectively. The annealed copper wire is cooled to room temperature with inert gas, and the cooling gas flow rate is 10 to 15 m / s.

10. The preparation process of hollow copper wire with low resistance according to claim 1, characterized in that, In S6, the outer diameter of the hollow copper wire is 0.5–5 mm, the wall thickness is 0.05–0.5 mm, and the resistivity at room temperature is [missing information]. Tensile strength ≥320MPa, and oxidation weight gain ≤0.05g / m² after 100 hours of constant temperature oxidation at 300℃.

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