Preparation method of copper-silver alloy for high-strength and high-conductivity new energy wiring harness

Abstract

The invention relates to the technical field of metal material processing, and discloses a preparation method of a copper-silver alloy for a high-strength and high-conductivity new energy wire harness, which comprises the following steps: inhibiting segregation caused by copper-silver density difference and refining grains by using a rotating traveling wave magnetic field and a high-energy ultrasonic beam through magneto-acoustic double-field coupling rheological continuous casting. And then under a cryogenic environment, special modified polysiloxane-graphene hybrid conductive gel is matched for large-strain drawing, the gel keeps semi-solid lubrication at a low temperature, and a conductive channel is established. And finally, establishing an axial temperature gradient by utilizing the temperature difference between the cryogenic state of the wire rod and the contact electrode area, and applying a unipolar electric pulse to trigger the Thomson effect. According to the process, a Thomson heat flow item is used for correcting a Joule thermal field, and electron wind power is used for driving silver atoms to be directionally separated out along high-density dislocation while overheating softening of a copper matrix is restrained. The method effectively solves the problem that the strength conductivity is inverted due to solidification segregation and traditional heat treatment, and the comprehensive performance of the copper-silver alloy is synchronously improved.

Description

Technical Field

[0001] This invention relates to the field of metal material processing technology, specifically to a method for preparing a copper-silver alloy for high-strength, high-conductivity new energy wiring harnesses. Background Technology

[0002] Copper-silver alloys, with their excellent electrical conductivity and mechanical properties, have become the preferred material for high-end wire harnesses in fields such as new energy vehicles and aerospace. Current manufacturing techniques typically employ a combination of melting and continuous casting, cold working deformation, and aging heat treatment. Due to the density difference between copper and silver, the alloy melt is highly susceptible to gravity segregation during solidification, leading to uneven composition distribution within the cast billet. This segregation phenomenon is particularly severe in high-silver-content alloys, not only deteriorating the material's machinability but also causing performance fluctuations in the length direction of the finished wire.

[0003] In subsequent processing, the improvement of copper-silver alloy performance mainly relies on dislocation strengthening caused by cold deformation and second-phase strengthening precipitated during aging. To achieve high conductivity, traditional processes require aging heat treatment to induce the precipitation of dissolved silver atoms. However, the heat energy introduced by the heat treatment simultaneously drives the copper matrix in a high-energy state to recover and recrystallize, resulting in the annihilation of a large number of high-density dislocations generated by cold deformation. This matrix softening effect weakens the results of work hardening, causing the alloy strength and conductivity to exhibit an inverse relationship, making it difficult to simultaneously maximize both through traditional heat treatment methods. Furthermore, offline heat treatment processes disrupt the continuous production flow and make it difficult to precisely and dynamically control the heat flow distribution and microstructure evolution within the wire. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for preparing a copper-silver alloy for high-strength, high-conductivity new energy wire harnesses. This method solves the problem of how to eliminate solidification segregation and overcome the matrix softening effect caused by traditional heat treatment during the preparation of copper-silver alloy wires, thereby achieving a simultaneous improvement in material strength and conductivity.

[0005] To achieve the above objectives, the present invention provides the following technical solution: The first aspect of this invention provides a method for preparing a copper-silver alloy for high-strength, high-conductivity new energy wiring harnesses. This method regulates the solidification structure, deformation structure, and precipitation kinetics of the copper-silver alloy through multi-physics field coupling, and includes the following steps: S1. Pure silver and electrolytic copper are used as raw materials by weight. They are melted in a vacuum induction melting furnace and then introduced into a continuous casting crystallizer. A rotating traveling wave magnetic field and a high-energy ultrasonic beam are simultaneously applied in the continuous casting crystallizer region to draw out the as-cast billet. During this process, the rotating traveling wave magnetic field drives the melt to generate macroscopic flow and suppresses the gravitational segregation of solute elements; the high-energy ultrasonic beam acts on the solidification front to generate cavitation effect, breaking the primary dendritic network and making the melt present a semi-solid rheological slurry state, thereby obtaining a uniformly structured as-cast billet. S2. The cast billet is placed in a cryogenic environment; before the first drawing pass, a modified polysiloxane-graphene hybrid conductive gel is coated on the surface of the cast billet; under the condition of maintaining the cryogenic environment, multiple consecutive drawing passes are performed to obtain the wire. During this process, the cryogenic environment suppresses the cross-slip and dynamic recovery of dislocations in the copper matrix, preserving high-density lattice distortion energy; the modified polysiloxane-graphene hybrid conductive gel maintains the interfacial conductive pathway and provides lubrication at low temperatures. S3. The cryogenically cooled wire is directly input into the electrode contact area to establish a temperature gradient along the wire's axial direction. A unipolar rectangular wave electrical pulse is applied to the wire using a rolling contact electrode. During this process, the temperature difference between the cryogenic wire and the electrode contact area is used to construct an axial temperature gradient field. When the pulse current flows through the conductor with the temperature gradient, endothermic or exothermic phenomena occur based on the Thomson effect, thereby correcting the temperature field dominated by Joule heating and regulating the energy distribution of the wire cross-section. Simultaneously, the pulse current induces silver atoms to migrate and desolvate along high-energy dislocation channels. S4. Cool, clean and rewind to obtain copper-silver alloy.

[0006] Further, in step S1, the raw materials include, by weight: 0.10 to 8.00 parts of pure silver and 92.00 to 99.90 parts of electrolytic copper.

[0007] Further, in step S1, the frequency of the rotating traveling wave magnetic field is 10 to 60 Hz, and the central magnetic induction intensity is 0.1 to 0.3 Tesla; the frequency of the high-energy ultrasonic beam is 19 to 25 kHz, the power density is 20 to 50 watts per square centimeter, and it is inserted into the liquid cavity to a depth of 10 to 30 mm through a high-temperature resistant ceramic amplitude transformer.

[0008] Furthermore, in step S2, the temperature of the cryogenic environment is -196°C to -150°C; the coating thickness of the modified polysiloxane-graphene hybrid conductive gel is 5 to 20 micrometers; and the area shrinkage per drawing pass is 15% to 25%.

[0009] Furthermore, in step S2, no natural reheating is performed at the exit of the final drawing die. The distance between the wire and the electrode contact area is controlled to be 50 to 150 mm, ensuring that the core temperature of the wire is below or equal to -100°C when it enters the electrode contact area. This setting aims to maintain the initial low-energy state and steep axial temperature gradient of the wire when it enters the electrical pulse treatment zone.

[0010] Furthermore, in step S3, the peak current density of the unipolar rectangular wave electrical pulse is 300 to 800 amperes per square millimeter, the frequency is 1 to 15 kilohertz, and the duty cycle is 10% to 30%.

[0011] Furthermore, in step S3, the direction of the temperature gradient points from the cryogenic end to the room temperature end; the current flow direction of the unipolar rectangular wave electric pulse is set to be the same as the movement direction of the wire. Under this configuration, Thomson heat is generated using the Thomson coefficient of the copper-silver alloy, and active intervention in the heat flow distribution inside the wire is achieved through the coupling of the current vector and the temperature gradient vector.

[0012] Furthermore, in step S3, while applying the unipolar rectangular wave electric pulse, tension is applied to the wire, the tension being 10%-30% of the wire's tensile strength. Under this tension, the contraction Lorentz force generated by the high-frequency, high-density current induces radial vibration in the wire, promoting dislocation unlocking and non-thermal diffusion of solute atoms.

[0013] Furthermore, in step S4, the solvent used for cleaning is a mixture of anhydrous ethanol and isopropanol in a volume ratio of 1:1.

[0014] Graphene oxide was dispersed in anhydrous ethanol, and 3-aminopropyltriethoxysilane was added and refluxed to obtain silane-based graphene. The silane-based graphene was added to vinyl-terminated polydimethylsiloxane and sheared and mixed, followed by the addition of hydrogen-containing silicone oil and isopropanol chloroplatinate solution; The modified polysiloxane-graphene hybrid conductive gel was obtained by vacuum degassing and curing at 100°C.

[0015] This gel system maintains flexibility and provides a stable conductive interface in cryogenic environments through the chemical bonding of silane-based graphene and polysiloxane, preventing frost formation and insulation on the wire surface.

[0016] Furthermore, the viscosity of the vinyl-terminated polydimethylsiloxane is 1000 to 5000 mPa·s; the hydrogen content of the hydrogen-containing silicone oil is 0.5 to 1.0% by weight. The graphene oxide sheets have a diameter of 0.5 to 5 micrometers.

[0017] This invention provides a method for preparing a copper-silver alloy for high-strength, high-conductivity new energy wiring harnesses. It has the following beneficial effects: 1. This invention introduces a rotating traveling wave magnetic field and a high-energy ultrasonic beam during the continuous casting crystallization stage. The magnetic field stirring effect is used to suppress the gravitational segregation of silver elements, and the ultrasonic cavitation effect is used to break the primary dendrites, thereby obtaining a rheological slurry structure with uniform composition. This process improves the processing rheology of high silver content alloys, effectively reduces the phenomenon of wire breakage in subsequent deep cryogenic drawing caused by internal structural defects, and ensures the consistency of the mechanical properties of the finished wire.

[0018] 2. This invention uses a modified polysiloxane-graphene hybrid conductive gel as a cryogenic processing medium. By utilizing the low-temperature resistance of polysiloxane and the conductive network constructed by graphene, it overcomes the insulation failure problem caused by the crystallization and brittleness of conventional lubricating oil in cryogenic environments. This material maintains stable interfacial lubrication and conductive pathways in environments below -150℃, avoiding arc burns on the surface of high-speed moving wires caused by contact resistance fluctuations when high-energy electrical pulses are introduced.

[0019] 3. This invention utilizes the temperature difference between the cryogenic wire and the electrode contact area to establish an axial temperature gradient. By controlling the direction of the pulse current to trigger the Thomson effect, the Thomson heat flow term is used to correct the Joule heat distribution of the wire cross section. This method suppresses the recovery softening of the copper matrix due to overheating, while using the non-thermal effect of the pulse current to promote the directional precipitation of silver atoms along dislocation channels, thereby improving the conductivity of the copper-silver alloy while maintaining high work hardening strength. Detailed Implementation Example Example

[0020] This embodiment provides a method for preparing a copper-silver alloy for high-strength, high-conductivity new energy wiring harnesses. The specific steps are as follows: S1, Magnetoacoustic Dual-Field Coupled Rheological Continuous Casting Weigh out 4.00 parts pure silver and 96.00 parts electrolytic copper by weight. Place the raw materials in a vacuum induction melting furnace and melt them uniformly at a vacuum of 5 Pa and a temperature of 1200℃. Introduce the melt into a continuous casting crystallizer and simultaneously apply a rotating traveling wave magnetic field and a high-energy ultrasonic beam to the crystallizer region.

[0021] The frequency of the rotating traveling wave magnetic field was set to 35 Hz, and the central magnetic induction intensity was 0.2 T; the frequency of the high-energy ultrasonic beam was 22 kHz, and the power density was 35 W / cm². 2 The amplitude transformer is inserted into the liquid cavity to a depth of 20 mm. A cast billet with a diameter of Φ16 mm is obtained by traction at a speed of 200 mm / min. S2, Cryogenic Large Strain Gradient Pulling The as-cast billet obtained in step S1 was placed in a liquid nitrogen spray system to establish a cryogenic environment at -173°C. Before the first drawing pass, the modified polysiloxane-graphene hybrid conductive gel obtained in Example A was uniformly coated on the surface of the billet, with the coating thickness controlled at 12 mm. .

[0022] Keep the wire in a cryogenic environment and perform multiple continuous drawing passes, with the area shrinkage rate set at 20% for each pass, until the final wire diameter is drawn; S3, Dynamic aging based on thermoelectric coupling of the Thomson effect No natural reheating is performed at the exit of the final drawing die. The distance from the die exit to the electrode contact area is controlled to be 100mm. Infrared temperature monitoring shows that the core temperature of the wire when it enters the electrode contact area is about -140℃, thus establishing a temperature gradient along the wire axis.

[0023] A unipolar rectangular wave electrical pulse is applied to the moving wire using a rolling contact electrode. The pulse parameters are set as follows: peak current density 550 A / mm². 2 Frequency 8kHz, duty cycle 20%, single pulse duration 100 The current flow direction is set to be the same as the wire movement direction. Simultaneously, an online tension equivalent to 20% of the wire's tensile strength is applied to the wire via a tension roller. S4, Post-processing After passing through the pulse treatment zone, the wire enters a cooling tube filled with high-purity nitrogen to cool to room temperature. The surface gel residue is cleaned using a 1:1 volume ratio of anhydrous ethanol and isopropanol mixture, and finally wound up with a tension of 3.0 N. Example

[0024] This embodiment provides a method for preparing a copper-silver alloy for high-strength, high-conductivity new energy wiring harnesses. The specific steps are as follows: S1, Magnetoacoustic Dual-Field Coupled Rheological Continuous Casting Weigh out 0.10 parts by weight of pure silver and 99.90 parts by weight of electrolytic copper. The smelting process is the same as in Example 1. A rotating traveling wave magnetic field and a high-energy ultrasonic beam are applied to the crystallizer region. The frequency of the rotating traveling wave magnetic field is set to 10 Hz, and the central magnetic induction intensity is 0.1 T; the frequency of the high-energy ultrasonic beam is 19 kHz, and the power density is 20 W / cm². 2 The amplitude transformer is inserted into the liquid cavity to a depth of 10 mm. A cast billet is obtained by traction at a speed of 100 mm / min.

[0025] S2, Cryogenic Large Strain Gradient Pulling The cast billet was placed in a cryogenic chamber at an ambient temperature controlled at -150°C. The conductive gel obtained in Example A was coated onto the surface of the billet, with the coating thickness controlled at 5 mm. Continuous drawing is performed in a cryogenic environment, with a reduction in area of ​​15% per pass.

[0026] S3, Dynamic aging based on thermoelectric coupling of the Thomson effect After the final drawing pass, the distance from the die exit to the electrode contact area is controlled at 50mm to ensure that the core temperature of the wire enters the electrode contact area ≤−100℃. A unipolar rectangular wave electrical pulse is applied with the following parameters: peak current density 300A / mm². 2 Frequency 1kHz, duty cycle 10%, single pulse duration 20 The current flow direction is set to be the same as the wire movement direction. At the same time, an online tension equivalent to 10% of its tensile strength is applied to the wire.

[0027] S4, Post-processing The process steps are the same as in Example 1, except that the winding tension is set to 1.0 N. Example

[0028] This embodiment provides a method for preparing a copper-silver alloy for high-strength, high-conductivity new energy wiring harnesses. The specific steps are as follows: S1, Magnetoacoustic Dual-Field Coupled Rheological Continuous Casting Weigh out 8.00 parts by weight of pure silver and 92.00 parts by weight of electrolytic copper. The smelting process is the same as in Example 1. A rotating traveling wave magnetic field and a high-energy ultrasonic beam are applied to the crystallizer region. The frequency of the rotating traveling wave magnetic field is set to 60 Hz, and the central magnetic induction intensity is 0.3 T; the frequency of the high-energy ultrasonic beam is 25 kHz, and the power density is 50 W / cm². 2 The amplitude transformer is inserted into the liquid cavity to a depth of 30 mm. A cast billet is obtained by traction at a speed of 300 mm / min. S2, Cryogenic Large Strain Gradient Pulling The cast billet was placed in a liquid nitrogen immersion bath at an ambient temperature controlled at -196°C. The conductive gel obtained in Example A was coated onto the surface of the billet, with a coating thickness controlled at 20 mm. Continuous drawing is performed in a cryogenic environment, with a reduction in area of ​​25% per pass. S3, Dynamic aging based on thermoelectric coupling of the Thomson effect After the final drawing pass, the distance from the die exit to the electrode contact area is controlled at 150mm to ensure that the core temperature of the wire enters the electrode contact area ≤−100℃. A unipolar rectangular wave electrical pulse is applied with the following parameters: peak current density 800A / mm². 2 Frequency 15kHz, duty cycle 30%, single pulse duration 200 The current flow direction is set to be the same as the wire movement direction. Simultaneously, an online tension equivalent to 30% of the wire's tensile strength is applied. S4, Post-processing The process steps are the same as in Example 1, except that the winding tension is set to 5.0 N.

[0029] Comparative example: Comparative Example 1 Compared with Example 1, the difference is that in step S1, no rotating traveling wave magnetic field and high-energy ultrasonic beam are applied, and only conventional vacuum induction melting and traction continuous casting are performed. The remaining steps and parameters are the same as in Example 1.

[0030] Comparative Example 2 Compared with Example 1, the difference is that in step S3, the state of the wire entering the electrode contact area is changed. After the wire comes out of the cryogenic drawing die, it first passes through the natural warming section to restore its temperature to room temperature, and then enters the electrode contact area to be subjected to the same electrical pulse and tension as in Example 1. That is, at this time, there is no temperature gradient caused by cryogenics in the axial direction of the wire. The remaining steps and parameters are the same as in Example 1.

[0031] Comparative Example 3 Compared with Example 1, the difference is that in step S2, ordinary industrial drawing oil (mainly composed of mineral oil and extreme pressure additives) is used instead of modified polysiloxane-graphene hybrid conductive gel for coating, and the remaining steps and parameters are the same as in Example 1.

[0032] Comparative Example 4 Compared with Example 1, the difference is that the online electrical pulse processing in step S3 is cancelled, and the wire drawn in step S2 is placed in a tubular annealing furnace for offline aging heat treatment. The heat treatment process is to hold at 350°C for 2 hours, and then cool it to room temperature with the furnace. The remaining steps and parameters are the same as in Example 1.

[0033] Test example: Test Example 1: Comprehensive Test of Mechanical and Electrical Properties 1. Experiment Description This test aims to determine the mechanical strength, plastic deformation capacity, and electrical conductivity of copper-silver alloy wires obtained under different preparation process conditions. The test subjects include wires prepared in Examples 1 to 3, and wires prepared in Comparative Examples 1 to 4. The specific testing equipment and operating procedures are as follows: An electronic universal testing machine equipped with a 1kN force sensor was used for testing. The sampling length was 250mm, and the gauge length was set to 200mm. At room temperature (25±2℃), the specimen was vertically fixed to the upper and lower clamps, and a tensile load was applied at a constant rate of 2mm / min until the specimen fractured. The system automatically recorded the maximum load force and the gauge length elongation after fracture, and calculated the tensile strength and elongation at fracture accordingly. Five specimens were tested for each set of parameters, and the arithmetic mean was taken as the final result. Using a high-precision DC digital bridge (measurement range) Measurements were performed with an accuracy of 0.05%. A 1000mm long wire sample was cut and placed in a 20℃ constant temperature oil bath for equilibration for 30 minutes. The DC resistance of the sample was measured using the four-terminal method. The volume resistivity was calculated based on the sample diameter and length, and converted to a percentage value (%IACS) relative to the International Standard for Annealed Copper (IACS). Five samples were tested for each set of parameters, and the arithmetic mean was taken.

[0034] 2. Experimental Results The mechanical and electrical performance test data of each group of samples are shown in Table 1.

[0035] Table 1: Test Data Recording Table for Mechanical and Electrical Conductivity Properties of Copper-Silver Alloy Wire Group Silver content (wt%) Tensile strength (MPa) Elongation after fracture (%) Conductivity (%IACS) Remark Example 1 4 912.4 3.2 81.5 intermediate parameters Example 2 0.1 545.8 12.6 96.2 Low silver high conductivity Example 3 8 1285.3 1.8 68.4 Goldin High Strength Comparative Example 1 4 834.6 2.1 77.3 Non-magnetic acoustic dual field Comparative Example 2 4 768.2 4.5 83.1 Pulse after temperature recovery (no temperature gradient) Comparative Example 3 4 865.1 2.8 79.2 Ordinary oil lubrication (unstable contact) Comparative Example 4 4 423.5 18.4 91.6 Offline heat treatment 3. Results Analysis The data differences between Example 1 and Comparative Example 1 indicate that applying a physical field during the solidification stage has a decisive impact on the final wire properties. Comparative Example 1 lacks the effects of a rotating traveling wave magnetic field and a high-energy ultrasonic beam, resulting in lower tensile strength and conductivity compared to Example 1. This is because the macroscopic flow driven by the rotating magnetic field suppresses the gravitational segregation of silver, while the ultrasonic cavitation effect breaks up primary dendrites in the solid-liquid two-phase region, forming a uniformly distributed semi-solid rheological structure. This uniform initial microstructure reduces stress concentration points during subsequent drawing and provides a uniform matrix environment for subsequent precipitation processes, thereby improving the overall performance of the wire.

[0036] The comparison between Example 1 and Comparative Examples 2 and 4 reveals the role of the temperature gradient field and the electrical pulse coupling mechanism. Comparative Example 4, using conventional offline heat treatment, achieved high conductivity but a significant decrease in tensile strength, indicating that the matrix underwent recovery and recrystallization, resulting in a loss of work hardening effect. Although Comparative Example 2 employed electrical pulse treatment, the axial temperature gradient was eliminated because the wire naturally reheated before entering the electrode region, leading to a lower tensile strength than in Example 1. This confirms that in Example 1, a steep temperature gradient was established through cryogenic drawing and non-reheating transfer. , and pulse current density vector The interaction excites the Thomson effect. This effect produces endothermic or exothermic flow terms. The Joule thermal field was modified to suppress the overheating and softening of the copper matrix, while the high-energy electron wind drove the silver atoms to precipitate directionally along the dislocation channels.

[0037] The data from Examples 1 to 3 show a regular distribution with varying silver content, verifying the applicability of the process under different compositions. Even under the high silver content conditions of Example 3, the wire maintained extremely high strength (>1200 MPa) through the control of segregation by the magnetoacoustic dual field and the dynamic intervention of heat flow by the Thomson effect, and the conductivity did not deteriorate drastically. In contrast, Comparative Example 3, lacking a dedicated conductive medium for cryogenic environments, experienced unstable contact resistance leading to fluctuations in electrical pulse energy transfer efficiency, resulting in poor consistency in its performance data. Furthermore, the balance point between strength and conductivity was lower than that of Example 1, indicating that a stable electrothermal interface is crucial for achieving this process.

[0038] Test Example 2: Processing Stability and Surface Quality Test 1. Experiment Description This test case aims to examine the processing stability and final surface quality of wires under different process conditions during continuous cryogenic drawing and electrical pulse treatment. The tests cover Examples 1 to 3, as well as Comparative Examples 1 and 3. The specific test procedures are as follows: Continuous production tests were conducted on a cryogenic drawing unit, with the final output wire diameter set at 0.15 mm. For each experiment, 100 kg of cast billet was continuously fed for processing, and the number of wire breaks occurring during the entire drawing and subsequent electrical pulse processing was recorded. If a wire break occurred, the break point was recorded, and production continued after re-threading the die until the raw material was exhausted. Ten samples, each 100 mm in length, were randomly cut from each group of finished wires. The circumferential surface of the wires was scanned and observed using a metallographic microscope at 50x and 200x magnification. The number of visible defects per unit length (meter) was counted, including microcracks, pits, and electrolytic corrosion spots. During the drawing process, the state of the lubricating medium coating on the wire surface is observed through a viewing window set in the cryogenic chamber. The physical morphology of the medium is recorded in an environment of -150℃ to -196℃ to determine whether there is solidification, brittle peeling, or adhesion failure.

[0039] 2. Experimental Results The processing stability and surface quality test data of each group of samples are shown in Table 2.

[0040] Table 2: Record of Continuous Processing Stability and Surface Quality Testing Group Number of wire breaks (times / 100kg) Surface defect density (number of defects / m²) Main Defect Types Description of the state of cryogenic media Example 1 1 0.8 Minor scratches Black gel-like consistency, adheres tightly without peeling. Example 2 0 0.4 No obvious defects Black gel-like consistency, with good fluidity. Example 3 2 1.5 shallow microcracks Black gel-like substance, which extends with the wire. Comparative Example 1 6 12.3 Horizontal cracks, slag inclusion pits Black gel-like substance, fits normally Comparative Example 3 9 28.6 Dense electrolytic craters, burns White crystalline solid substance, peeling off in brittle flakes. 3. Results Analysis The high breakage frequency and high surface defect density of Comparative Example 1 indicate that the microstructure homogeneity of the initial cast billet is crucial for subsequent high-strain processing. Comparative Example 1, lacking a rotating traveling wave magnetic field and high-energy ultrasonic beam, resulted in macroscopic segregation of solute elements and coarse dendritic networks within the cast billet. Under the high stress of cryogenic drawing, these microstructure inhomogeneities became stress concentration sources, inducing the initiation and propagation of transverse cracks, ultimately leading to breakage. In contrast, Examples 1 to 3 obtained a homogenized rheological slurry microstructure through multiphysics melting, reducing the risk of fracture during processing. Even under the high silver content conditions of Example 3, a lower breakage level was maintained.

[0041] The experimental results of Comparative Example 3 confirm the necessity of a dedicated interface medium in the cryogenic-electric pulse coupling process. Ordinary drawing oil undergoes a glass transition or crystallization in cryogenic environments below -150°C, forming a brittle insulating layer that peels off from the wire surface, resulting in the wire being in a dry friction state and poor contact with the electrode. When a high-energy electric pulse is introduced, the presence of the insulating layer causes drastic fluctuations in contact resistance, inducing localized micro-arc discharges and forming dense electro-erosion pits and burn points on the wire surface. This directly leads to an extremely high breakage rate and unacceptable surface quality.

[0042] The modified polysiloxane-graphene hybrid conductive gels used in Examples 1 to 3 utilize the low glass transition temperature of the polysiloxane segments to maintain semi-solid flexibility and lubrication under cryogenic conditions. Simultaneously, the dispersed silanized graphene in the gel network constructs stable conductive channels, ensuring low-resistance ohmic contact between the rolling electrode and the high-speed moving wire. This stable interface state allows high-density pulsed current to be uniformly introduced into the wire, stimulating the expected Thomson effect and electroplastic effect without causing interfacial arc damage, thus ensuring the continuous and stable fabrication of high-strength, high-conductivity copper-silver alloy wires.

Claims

1. A method for preparing a copper-silver alloy for high-strength, high-conductivity new energy wiring harnesses, characterized in that, Includes the following steps: S1. Pure silver and electrolytic copper are taken as raw materials by weight, melted in a vacuum induction melting furnace and then introduced into a continuous casting crystallizer; a rotating traveling wave magnetic field and a high-energy ultrasonic beam are simultaneously applied in the continuous casting crystallizer area to draw out the cast billet. S2. Place the cast billet in a cryogenic environment; before the first drawing pass, coat the surface of the cast billet with a modified polysiloxane-graphene hybrid conductive gel; and perform multiple consecutive drawing passes to obtain a wire while maintaining the cryogenic environment. S3. Directly input the wire in a cryogenic state into the electrode contact area to establish a temperature gradient along the axial direction of the wire; apply a unipolar rectangular wave electrical pulse to the wire by rolling the contact electrode; S4. Cool, clean and rewind to obtain copper-silver alloy.

2. The method for preparing a high-strength, high-conductivity copper-silver alloy for new energy wiring harnesses according to claim 1, characterized in that, In step S1, the raw materials include, by weight, 0.10 to 8.00 parts of pure silver and 92.00 to 99.90 parts of electrolytic copper.

3. The method for preparing a high-strength, high-conductivity copper-silver alloy for new energy wiring harnesses according to claim 1, characterized in that, In step S1, the frequency of the rotating traveling wave magnetic field is 10 to 60 Hz, and the central magnetic induction intensity is 0.1 to 0.3 Tesla; the frequency of the high-energy ultrasonic beam is 19 to 25 kHz, the power density is 20 to 50 watts per square centimeter, and it is inserted into the liquid cavity to a depth of 10 to 30 mm through a high-temperature resistant ceramic amplitude transformer.

4. The method for preparing a high-strength, high-conductivity copper-silver alloy for new energy wiring harnesses according to claim 1, characterized in that, The preparation method of the modified polysiloxane-graphene hybrid conductive gel includes: dispersing graphene oxide in anhydrous ethanol, adding 3-aminopropyltriethoxysilane and refluxing to obtain silane-based graphene; adding the silane-based graphene to vinyl-terminated polydimethylsiloxane for shear mixing, followed by adding hydrogen-containing silicone oil and isopropanol chloroplatinate solution; and curing at 100°C after vacuum degassing to obtain the modified polysiloxane-graphene hybrid conductive gel.

5. The method for preparing a high-strength, high-conductivity copper-silver alloy for new energy wiring harnesses according to claim 1, characterized in that, The viscosity of the terminal vinyl polydimethylsiloxane is 1000 to 5000 mPa·s; the hydrogen content of the hydrogen-containing silicone oil is 0.5 to 1.0% by weight; and the sheet diameter of the graphene oxide is 0.5 to 5 micrometers.

6. The method for preparing a high-strength, high-conductivity copper-silver alloy for new energy wiring harnesses according to claim 1, characterized in that, In step S2, the temperature of the cryogenic environment is -196°C to -150°C; the coating thickness of the modified polysiloxane-graphene hybrid conductive gel is 5 to 20 micrometers; and the area shrinkage per drawing pass is 15% to 25%.

7. The method for preparing a high-strength, high-conductivity copper-silver alloy for new energy wiring harnesses according to claim 1, characterized in that, In step S2, natural reheating is not performed at the exit of the last drawing die. The distance between the wire and the electrode contact area is controlled to be 50 to 150 mm to ensure that the core temperature of the wire is below or equal to -100°C when it enters the electrode contact area.

8. The method for preparing a copper-silver alloy for high-strength, high-conductivity new energy wiring harness according to claim 1, characterized in that, In step S3, the peak current density of the unipolar rectangular wave electric pulse is 300 to 800 amperes per square millimeter, the frequency is 1 to 15 kilohertz, and the duty cycle is 10% to 30%.

9. The method for preparing a high-strength, high-conductivity copper-silver alloy for new energy wiring harnesses according to claim 1, characterized in that, In step S3, the direction of the temperature gradient is from the cryogenic end to the room temperature end; the current flow direction of the unipolar rectangular wave electric pulse is set to be the same as the movement direction of the wire, and the Thomson coefficient of the copper-silver alloy is used to generate Thomson heat to correct the temperature distribution of the wire cross section.

10. The method for preparing a high-strength, high-conductivity copper-silver alloy for new energy wiring harnesses according to claim 1, characterized in that, In step S3, while applying the unipolar rectangular wave electric pulse, tension is applied to the wire, the tension being 10% to 30% of the wire's tensile strength. The contraction Lorentz force generated by the pulse current induces radial vibration in the wire. In step S4, the solvent used for cleaning is a mixture of anhydrous ethanol and isopropanol in a volume ratio of 1:1.