A method for synergistically regulating mechanical properties and conduction properties of copper and noble metal wire rods

Abstract

The application provides a method for synergistically regulating mechanical properties and conductive properties of copper and noble metal wire rods, which comprises the following steps: step 1, melting electrolytic copper and / or noble metal in a smelting furnace, the smelting temperature is 50-100 DEG C higher than the melting point of the metal, smelting for 10-40 min to obtain a melt; step 2, pouring the melt into a crystallizer or a casting mold, and cooling and solidifying by controlling process parameters to obtain a single crystal continuous casting rod blank and a rod blank with typical directional solidification structure; and step 3, performing multi-pass drawing or rolling deformation on the rod blank, and simultaneously realizing ultra-fine and ultra-precision continuous deformation by controlling parameters such as deformation pass quantity, drawing speed or rolling speed, and intermediate annealing node, so that the mechanical properties and the conductive properties are synergistically regulated. When the wire diameter is refined to 20 microns, the strength reaches 600-1600 MPa, and the conductivity can reach 50-106 % IACS.

Description

Technical Field

[0001] This invention belongs to the field of copper and precious metal wire preparation technology, specifically relating to a method for synergistic regulation of the mechanical and conductive properties of copper and precious metal wires. Background Technology

[0002] As a key conductor material for digital and analog signal transmission, high-performance copper and precious metal wires are widely used in aerospace instrumentation microfilaments, nuclear-grade sensor resistance wires, integrated circuit bonding wires, audio and video transmission lines, active wire harnesses for medical devices, and various electronic components.

[0003] With the rapid development of aerospace, nuclear power engineering, integrated circuits, audio and video transmission, and consumer electronics, higher requirements are being placed on the mechanical and conductive properties of copper and precious metal wires. These requirements include extremely fine wire diameters (≤20μm), ultra-high precision (±0.3μm), and extremely strong tensile strength (continuous drawing exceeding 400,000 meters without breakage). Simultaneously, some key construction projects require high-fidelity audio and video transmission, demanding single-crystal copper wires with diameters of 20-100μm; copper-silver alloy wires for active wiring harnesses in endoscopic diagnostic instruments require diameters ≤16μm and strengths ≥1000MPa; and resistance temperature coefficient fluctuations for resistance wires used in nuclear-grade sensors must be ≤±4×10⁻⁶. -6 ℃ -1 .

[0004] However, the fabrication process of copper and precious metal wires involves numerous deformation passes, high strain rates, and complex deformation microstructure evolution. Furthermore, beyond achieving ultra-fine, ultra-precise, continuous, and stable deformation, how to further modify process parameters to synergistically control the mechanical and conductive properties of micro-wires is a crucial issue that urgently needs to be addressed in the production of high-performance copper and precious metal wires.

[0005] Domestic manufacturing processes for copper and precious metal wires can basically meet the needs of low- to mid-range applications, but high-performance copper and precious metal wires mainly rely on imports. How to integrate key process parameters from billet preparation to machining deformation and intermediate annealing, and combine these with comprehensive requirements for mechanical and thermal properties, to adjust and optimize process parameters, thereby improving the microstructure of the wires and meeting the high reliability performance requirements of high-end copper and precious metal wires, has become a major bottleneck problem for my country in this field.

[0006] Existing copper and precious metal wires cannot meet the strength and conductivity requirements.

[0007] Therefore, there is a need to provide an improved technical solution that addresses the shortcomings of the existing technology. Summary of the Invention

[0008] The purpose of this invention is to provide a method for synergistic regulation of the mechanical and conductive properties of copper and precious metal wires, and the wires prepared using this method, so as to solve the problem that the wires currently prepared cannot simultaneously meet the high standards of mechanical and conductive properties.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] A method for synergistically controlling the mechanical and electrical conductivity properties of copper and precious metal wires, the method comprising the following steps:

[0011] Step 1: Melt electrolytic copper and / or precious metals in a smelting furnace at a temperature 50-100°C above the metal melting point for 10-40 minutes to obtain a melt.

[0012] Step 2: The melt is injected into the crystallizer or mold and cooled and solidified by controlling the process parameters to obtain a single-crystal continuous casting rod billet or a rod billet with a typical directional solidification structure.

[0013] Step 3 involves multi-pass drawing or rolling deformation of the billet. By controlling parameters such as the number of deformation passes, drawing speed or rolling speed, and intermediate annealing nodes, the mechanical properties and conductivity of the micro-material are synergistically regulated while achieving continuous deformation of the micro-material to achieve ultra-fine and ultra-precise properties.

[0014] In the method for synergistic regulation of the mechanical and conductive properties of copper and precious metal wires as described above, preferably, in step 2, the temperature of the crystallizer is controlled at 0-50°C above the metal melting point, and the temperature of the casting mold is controlled at 15-25°C.

[0015] In the method for synergistic control of the mechanical and conductive properties of copper and precious metal wires as described above, preferably, in step 2, the crystallizer includes a hot-type horizontal continuous casting crystallizer or a cold-type vertical continuous casting crystallizer, and the mold is an internally circulating water-cooled copper mold. Process parameters include the dredger rod traction speed and the mold temperature. When using a hot-type horizontal continuous casting crystallizer, the dredger rod traction speed is 10-80 mm / min; when using a cold-type vertical continuous casting crystallizer, the dredger rod traction speed is 80-160 mm / min; when using crucible casting, the copper mold temperature is controlled by circulating water cooling.

[0016] In the method for synergistic control of the mechanical and electrical properties of copper and precious metal wires as described above, preferably, the deformation speed in step 3 is 1000-1600 m / min when using drawing deformation, and 10-20 m / min when using rolling deformation.

[0017] In the method for synergistic control of the mechanical and electrical properties of copper and precious metal wires as described above, preferably, the number of deformation passes in step 3 is 90-150 when using drawing deformation and 10-30 when using rolling deformation.

[0018] In the method for synergistic regulation of the mechanical and electrical properties of copper and precious metal wires as described above, preferably, the precious metals in step 1 mainly include: platinum-based, gold-based, silver-based, palladium-based, and rhodium-based alloys.

[0019] In the method for synergistic control of the mechanical and conductive properties of copper and precious metal wires as described above, preferably, in step 3, the intermediate annealing nodes are: the first node is when the wire diameter is 1.15-1.30 mm, and the second node is when the wire diameter is 0.02-0.18 mm.

[0020] In the method for synergistic control of the mechanical and conductive properties of copper and precious metal wires as described above, preferably, the annealing temperature of the first node is 150-250℃, and the holding time is 5-10min.

[0021] In the method for synergistic control of the mechanical and conductive properties of copper and precious metal wires as described above, preferably, the annealing temperature of the second node is 150-250℃, and the holding time is 10-30min.

[0022] A method for synergistically regulating the mechanical and conductive properties of copper and precious metal wires is used to prepare the wires, wherein the wires are prepared using the above-mentioned method for synergistically regulating the mechanical and conductive properties of copper and precious metal wires.

[0023] Beneficial effects:

[0024] This invention discloses a method for synergistically controlling the mechanical and conductive properties of copper and precious metal wires. The method achieves the preparation of copper and precious metal wires by controlling the initial solidification structure and the continuous deformation structure, resulting in copper and precious metal wires with excellent mechanical and conductive properties. The conductive properties of the wires can be reflected by their electrical conductivity. By rationally designing the melting temperature, crystallizer temperature, and mold temperature, and controlling the deformation speed (drawing speed, rolling speed) and the number of deformation passes, multi-pass deformation of the copper and precious metal rods is achieved, with a total deformation pass count exceeding 90 passes. The resulting copper and precious metal wires have a diameter as fine as 20 μm and a strength of 600-1600 MPa. By applying annealing treatment at specific deformation points in the wire, the conductive properties of the copper and precious metal wires are significantly improved without significantly affecting the wire strength, achieving a conductivity of 50-106% IACS.

[0025] By controlling the original solidification structure during the casting process, single-crystal continuous casting rod blanks and rod blanks with typical directional solidification structures were obtained. Based on this, key process parameters during deformation were further controlled to achieve synergistic regulation of the mechanical and electrical conductivity properties of copper and precious metal wires. The prepared copper and precious metal wires exhibit excellent mechanical and electrical conductivity properties. Attached Figure Description

[0026] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Wherein:

[0027] Figure 1 This is a microstructure diagram of the copper-based rod blank of Embodiment 1 of the present invention;

[0028] Figure 2 The microstructure images obtained by transmission electron microscopy analysis from the copper-based rod blank to the copper-based wire rod stage in Embodiment 1 of the present invention are as follows: (a is the microstructure image of the copper-based rod blank with a wire diameter of 8 mm, b is the microstructure image of the wire with a wire diameter of 0.51 mm, and c is the microstructure image of the copper-based wire rod with a wire diameter of 0.05 mm).

[0029] Figure 3 This is a schematic diagram of the internal dislocation morphology and electron transport state of the copper-based rod blank to copper-based wire at different drawing deformation stages of the present invention;

[0030] Figure 4 The drawn state microstructure obtained by transmission electron microscopy analysis of the copper-based alloy wire prepared in Comparative Example 1 of the present invention without intermediate annealing (a, b, c are the morphologies during the drawing process, a is the wire diameter of 7.8 mm; b is the wire diameter of 5.37 mm; c is the wire diameter of 2.95 mm). Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0032] The present invention will now be described in detail with reference to embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other.

[0033] The present invention provides a method for synergistic regulation of the mechanical and conductive properties of copper and precious metal wires, which mainly includes the control of the original solidification structure and the continuous deformation structure.

[0034] The control of the original solidification structure is mainly reflected in the preparation of the billet during the smelting, crystallization and traction processes, forming a single-crystal continuous casting billet and a billet with a typical directional solidification structure; the control of the continuous deformation structure is mainly reflected in the billet processing process, through the precise control of parameters such as deformation speed, deformation pass number and intermediate annealing node, to regulate the internal microstructure characteristics of copper-based wire rods, generate micro-strip structures parallel to the wire axis, and achieve synergistic improvement of the strength and conductivity of the wire rod.

[0035] This invention provides a method for synergistically controlling the mechanical and electrical properties of copper and precious metal wires, comprising the following steps:

[0036] (1) Regulation of the original coagulated structure

[0037] Step 1: Melt electrolytic copper and / or precious metals in a smelting furnace at a temperature 50-100°C above the melting point (e.g., pure copper has a melting point of 1100°C, so the smelting temperature is 1150-1250°C; pure platinum has a melting point of 1800°C, so the smelting temperature is 1850-1900°C) for 10-30 minutes (e.g., 15 minutes, 20 minutes, 35 minutes) to obtain the melt.

[0038] In a specific embodiment of the present invention, the electrolytic copper block is high-purity copper with a copper content of Cu≥99.95wt%.

[0039] The precious metals in step 1 mainly include: platinum-based, gold-based, silver-based, palladium-based, and rhodium-based alloys.

[0040] Step 2: Pour the melt into a crystallizer or mold, and cool and solidify it by controlling the process parameters to obtain a single-crystal continuous casting rod billet or a rod billet with a typical directional solidification structure.

[0041] In a specific embodiment of the present invention, the temperature of the crystallizer is controlled 0-50°C above the metal melting point (for example, the melting point of pure copper is 1100°C, and the crystallizer temperature is 1100-1150°C); the mold temperature is controlled at 15-25°C. The crystallizer includes a hot-type horizontal continuous casting crystallizer or a cold-type vertical continuous casting crystallizer, and the mold is an internally circulating water-cooled copper mold.

[0042] In specific embodiments of the present invention, when using hot-mold horizontal continuous casting, the traction speed of the dummy bar is 10-80 mm / min (e.g., 20 mm / min, 40 mm / min, 60 mm / min); when using cold-mold vertical continuous casting, the traction speed of the dummy bar is 80-160 mm / min (e.g., 100 mm / min, 120 mm / min, 140 mm / min).

[0043] During the traction process of the ingot rod, the shape and position of the solid-liquid interface at the solidification front determine the morphology of the solidification structure. This invention controls the shape and position of the solid-liquid interface at the solidification front by adjusting the combination of melting temperature, crystallizer temperature, and traction speed, thereby producing single-crystal continuous casting rod blanks and rod blanks with typical directional solidification structures, such as… Figure 1 As shown (forming a single crystal structure growing along the axial direction of the rod blank), the preparation of this solidified structure is the prerequisite and key to achieving synergistic control of subsequent mechanical and electrical properties.

[0044] (2) Regulation of continuous deformation structures

[0045] Step 3 involves multi-pass drawing or rolling deformation of the billet. By controlling parameters such as the number of deformation passes, drawing speed, rolling speed, and intermediate annealing nodes, ultra-fine and ultra-precise continuous deformation is achieved, while mechanical properties and conductivity are synergistically regulated.

[0046] In a specific embodiment of the present invention, the deformation speed in step 3 is 1000-1600 m / min (e.g., 1000 m / min, 1200 m / min, 100 m / min) when using drawing deformation; and 10-20 m / min (e.g., 10 m / min, 15 m / min, 20 m / min) when using rolling deformation. The number of deformation passes is 90-150 (e.g., 100 passes, 110 passes, 120 passes, 130 passes, 140 passes) when using drawing deformation; and 10-30 when using rolling deformation. The final wire diameter can be as fine as 20 μm.

[0047] In a specific embodiment of the present invention, a first annealing treatment is performed when the wire diameter is 1.15-1.30mm (e.g., 1.18mm, 1.2mm, 1.25mm), and a second annealing treatment is performed when the wire diameter is 0.02-0.18mm (e.g., 0.05mm, 0.1mm, 0.12mm, 0.14mm, 0.16mm).

[0048] In a specific embodiment of the present invention, the temperature of the first annealing treatment is 150-250℃ (e.g., 160℃, 180℃, 200℃, 220℃, 240℃), and the holding time is 5-10 min (e.g., 6 min, 7 min, 8 min, 9 min). The temperature of the second annealing treatment is 150-250℃ (e.g., 160℃, 180℃, 200℃, 220℃, 240℃), and the holding time is 10-30 min (e.g., 15 min, 20 min, 25 min).

[0049] The annealing process in this invention involves heating the wire by energizing a drawing machine.

[0050] In this process, the deformation heat treatment parameters determine the microstructure of the wire and ultimately affect its mechanical and electrical properties. This invention, through precise control of the deformation heat treatment process parameters, including adjustments to the number of deformation passes, deformation speed, and intermediate annealing points, allows the wire's microstructure to undergo phased changes, ultimately forming a micro-ribbon structure parallel to the wire's axis. This achieves a synergistic improvement in the wire's strength and conductivity, resulting in copper and precious metal wires with performance meeting the requirements of high-end applications and stable quality.

[0051] The specific control mechanism for the synergistic regulation of the mechanical and electrical properties of copper and precious metal wires in this invention is as follows:

[0052] In terms of mechanical property control: by rationally designing the annealing nodes, annealing temperature and holding time during the deformation process, and controlling the drawing speed or rolling speed, multiple drawing or rolling passes of the bar billet can be achieved. The total number of drawing deformation passes is 90-150, or the total number of rolling passes is 10-30, resulting in wire diameters as fine as 20μm and strengths of 600-1600MPa.

[0053] The essence of mechanical property control lies in the precise regulation of the phased changes in wire strength caused by dislocation and grain boundary interactions. The microstructure characteristics of the wire differ at different deformation stages. As the number of deformation passes and the amount of wire deformation increase, the wire diameter continuously decreases, and the characteristic microstructures sequentially follow: polycrystalline / monocrystalline structure → dislocation generation and entanglement → dislocation cells → microbands and microshear bands → layered structure → twinned structure (e.g., ...). Figure 2 (As shown). Significant differences exist in the mechanical properties of wires with different microstructures. The formation of microstrips and twinned structures corresponds to the two most obvious points of change in mechanical properties. By identifying the stages of microstructural changes, key process parameters during deformation can be controlled, including the number of deformation passes, deformation speed, and annealing time, thereby obtaining different types of microstructures and ultimately achieving the regulation of the mechanical properties of the wire.

[0054] In terms of conductivity control: by applying annealing treatment at specific deformation nodes of the wire, the conductivity of copper and precious metal wires can be significantly improved without significantly affecting the wire strength. The conductivity of the wire can reach 50-106% IACS.

[0055] The key to controlling conductivity lies in the precise control of the internal microstructure of the wire. The conductivity of a wire is mainly related to its axial grain boundary density and dislocation morphology. Polycrystalline / single-crystal rod blanks have lower grain boundary densities, higher conductivity, and better conductivity. However, as deformation progresses, different types of interface structures, such as dislocations, dislocation cells, and microstrips, are successively generated, increasing the axial interface density of the wire. These interface structures cause scattering during electron transport, leading to a decrease in conductivity. (e.g.) Figure 3(As shown in the low deformation stage). However, as the deformation further increases, the microstrip structure gradually distributes along the wire axis, the interface density inside the microstrip decreases, and the microstrip structure becomes an effective channel for electron transport along the axis, resulting in a gradual increase in conductivity (e.g., ...). Figure 3 (Large deformation stage); if the wire is annealed during this stage, the conductivity of the wire can be further improved (e.g., Figure 3 Annealed microfilaments in the middle.

[0056] Regarding the synergistic control of mechanical and thermal properties: The mechanical and thermal properties of copper and precious metal wires exhibit phased changes, and these properties are not independent but closely interconnected. Therefore, by controlling the original solidification structure, single-crystal continuous casting billets and billets with typical directional solidification structures can be obtained. Based on this, further control of the deformation structure allows for the synergistic control of the mechanical and thermal properties of copper and precious metal wires.

[0057] Example 1

[0058] This embodiment provides a method for synergistically controlling the mechanical and electrical conductivity properties of copper and precious metal wires, comprising the following steps:

[0059] (1) Regulation of the original coagulated structure

[0060] Electrolytic copper (Cu≥99.95%) was melted in a smelting furnace at a temperature of 1200℃ for 30 minutes. After the surface of the melt became mirror-like, it was allowed to stand for 3 minutes. Then, the melt was poured into a horizontally placed crystallizer. The billet was drawn out from the tail of the crystallizer by a hot-type horizontal continuous casting method at a traction speed of 60 mm / min and a crystallizer temperature of 1100℃. Pure copper billets with a wire diameter of 16 mm were obtained.

[0061] (2) Regulation of continuous deformation structures

[0062] The pure copper rod blank was drawn in 147 passes on a drawing machine at a speed of 1500 m / min. The first annealing was performed when the wire diameter reached 1.15 mm at 160°C for 8 minutes. The second annealing was performed when the wire diameter reached 50 μm at 150°C for 30 minutes. Finally, the wire was drawn again to obtain a pure copper wire with a diameter of 22 μm.

[0063] The pure copper rod blank obtained in this embodiment was subjected to metallographic observation, and the microstructure image is shown below. Figure 1 As shown; transmission electron microscopy analysis was performed when the rod blank was drawn to wire diameters of 0.51 mm and 50 μm, and the results were as follows. Figure 2 The microstructure diagram shown.

[0064] from Figure 1 As can be seen from this, the grains of the pure copper rod blank are distributed in a banded pattern along the axial direction of the rod blank. Figure 2 As can be seen, the types of internal microstructures of the wire differ at different drawing stages. With the increase of deformation, the types of characteristic microstructures successively appear as follows: polycrystalline / monocrystalline structure → dislocation generation and entanglement → dislocation cells → microstrips and microshear bands → layered structure → twinned structure.

[0065] Tensile strength and conductivity tests were performed on the pure copper wire in this embodiment. Tensile strength was tested using the GB / T 228.1-2010 standard on a Japanese SHIMADZU AG-I250KN precision universal testing machine. Conductivity was tested using a TX-300A intelligent metallic conductor resistivity meter with temperature compensation, set to a 25°C environment. The sample length was not less than 400 mm, and each sample was measured five times, with the average value taken. The unit used was the international annealed Cu standard %IACS.

[0066] Ultimately, the tensile strength of the pure copper wire in this embodiment is 671 MPa, and the conductivity is 104.00% IACS.

[0067] Example 2

[0068] This embodiment provides a method for synergistically controlling the mechanical and electrical conductivity properties of copper and precious metal wires, comprising the following steps:

[0069] (1) Regulation of the original coagulated structure

[0070] Electrolytic copper blocks (Cu≥99.95%) were melted in a melting furnace at a temperature of 1180℃ for 20 minutes. After the surface of the melt became mirror-like, it was allowed to stand for 3 minutes. Then, the melt was poured into a vertically placed crystallizer and continuously cast by cold vertical casting. The dummy rod was drawn out from the tail of the crystallizer at a speed of 90 mm / min and a temperature of 1100℃ to obtain a pure copper rod with a wire diameter of 8 mm.

[0071] (2) Regulation of continuous deformation structures

[0072] The pure copper rod blank was drawn in 140 passes on a drawing machine at a speed of 1200 m / min. The first annealing was performed when the wire diameter reached 1.20 mm at 180°C for 8 minutes. The second annealing was performed when the wire diameter reached 180 μm at 180°C for 20 minutes. Finally, the wire was drawn again to obtain a pure copper wire with a diameter of 100 μm.

[0073] The pure copper wire prepared in this embodiment was tested for tensile strength and conductivity using the same testing method as in Example 1. The tensile strength of the wire was 609 MPa and the conductivity was 102.18% IACS.

[0074] Example 3

[0075] The difference between this embodiment and Embodiment 2 lies in the control of the original solidification structure in step (1). 20% Ag element was added, the melting temperature was changed to 1250℃, the melting time to 40 min, the crystallizer temperature to 1120℃, and the traction speed of the dummy bar to 100 mm / min. A copper-based rod blank with a diameter of 8 mm was prepared, and in step (2), it underwent 150 drawing passes to obtain a wire with a diameter of 20 μm. Other methods and steps are the same as in Embodiment 1 and will not be repeated here.

[0076] The filament prepared in this embodiment was tested for tensile strength and conductivity using the same testing method as in Example 1. The tensile strength of the filament was 1682 MPa and the conductivity was 54.40% IACS.

[0077] Example 4

[0078] The difference between this embodiment and Embodiment 1 lies in the control of the original solidification structure in step (1). The melting temperature was changed to 1150℃, the melting time to 30min, the crystallizer temperature to 1120℃, and the traction speed of the dummy bar to 50mm / min. A copper-based rod blank with a diameter of 16mm was prepared, and in step (2), it was drawn 137 times to obtain a copper-based wire with a diameter of 50μm. Other methods and steps are the same as in Embodiment 1 and will not be repeated here.

[0079] The pure copper wire prepared in this embodiment was tested for tensile strength and conductivity using the same testing method as in Example 1. The tensile strength of the wire was 655 MPa and the conductivity was 104.48% IACS.

[0080] Example 5

[0081] The difference between this embodiment and Embodiment 2 lies in the control of the continuous deformation structure in step (2). The drawing speed is changed to 1000 m / min, and 148 drawing passes are performed. When the wire diameter is 1.20 mm, the first annealing is performed at a temperature of 170°C for 9 min. When the wire diameter is 50 μm, the second annealing is performed at a temperature of 210°C for 20 min. Finally, drawing continues to obtain a pure copper wire with a diameter of 20 μm. Other methods and steps are the same as in Embodiment 2 and will not be repeated here.

[0082] The copper-based wire prepared in this embodiment was tested for tensile strength and conductivity using the same testing method as in Example 1. The tensile strength of the wire was 700 MPa and the conductivity was 106.00% IACS.

[0083] Compare with Example 1

[0084] The difference between this comparative example and Example 1 is as follows: Electrolytic copper blocks (Cu≥99.95%) were melted in a melting furnace at a melting temperature of 1300℃ for 40 minutes. After the surface of the melt became mirror-like, it was allowed to stand for 2 minutes. Then, the melt was poured into a vertically placed crystallizer. The billet was drawn out from the tail of the crystallizer by a hot-dip horizontal continuous casting method at a traction speed of 100 mm / min and a crystallizer temperature of 1200℃, thus obtaining a copper-based billet with a wire diameter of 16 mm. Everything else was the same as in Example 1 and will not be repeated here.

[0085] The pure copper rod blank was drawn in 110 passes on a drawing machine at a speed of 1800 m / min. Without intermediate annealing, the wire diameter was drawn to 130 μm, after which further drawing was difficult.

[0086] The tensile strength and conductivity were tested using the same test method as in Example 1. The tensile strength of the copper-based wire was 546 MPa and the conductivity was 98.40% IACS.

[0087] Compare with Example 2

[0088] The difference between this comparative example and Example 2 is as follows: Electrolytic copper blocks (Cu≥99.95%) were melted in a melting furnace with 4% Ag added. The melting temperature was 1100℃ for 30 minutes. After the surface of the melt became mirror-like, it was allowed to stand for 3 minutes. Then, the melt was poured into a horizontally placed crystallizer. The billet was drawn out from the tail of the crystallizer by a hot-dip horizontal continuous casting method at a traction speed of 50 mm / min and a crystallizer temperature of 1050℃, thus obtaining a copper-based billet with a wire diameter of 16 mm. Everything else was the same as in Example 2 and will not be repeated here.

[0089] The rod blank was subjected to 130 drawing passes on a drawing machine at a speed of 2000 m / min. Without intermediate annealing, it was difficult to draw further after reaching a wire diameter of 204 μm. The microstructure during the drawing deformation stage is as follows: Figure 4 As shown, a, b, and c represent the morphology during the drawing process. The diameter of wire a is 7.8 mm; the diameter of wire b is 5.37 mm; and the diameter of wire c is 2.95 mm. The figure shows that no banded structure parallel to the axial direction was formed inside.

[0090] The tensile strength and conductivity were tested using the same test method as in Example 1. The tensile strength of the wire was 510 MPa and the conductivity was 98.60% IACS.

[0091] Comparative Examples 1 and 2 illustrate that excessively high or low melting and crystallization temperatures of the electrolytic copper ingot will affect the subsequent drawing process, and the drawing speed will also affect the final wire diameter. The combined effects of melting temperature, crystallization temperature, dummy bar traction speed, deformation speed, number of deformation passes, and intermediate annealing nodes will influence the wire diameter and significantly affect its mechanical and electrical properties.

[0092] In summary, this invention provides a method for synergistically controlling the mechanical and electrical properties of copper and precious metal wires. This method achieves the preparation of copper and precious metal wires by controlling the initial solidification structure and the continuous deformation structure, resulting in copper and precious metal wires with excellent mechanical and electrical properties. By rationally designing the melting temperature, crystallizer temperature, and mold temperature, and controlling the deformation rate and intermediate annealing points, multi-pass deformation of the copper and precious metal billet is achieved, with a total of over 90 deformation passes. The resulting copper and precious metal wires have a diameter as fine as 20 μm and a strength of 600-1600 MPa. By applying annealing treatment at specific deformation points in the wire, the electrical conductivity of the copper and precious metal wires is significantly improved without significantly affecting the wire strength, reaching a conductivity of 50-106% IACS.

[0093] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for synergistically controlling the mechanical properties and conductivity of copper and precious metal wires, characterized in that, The method includes the following steps: Step 1: Melt electrolytic copper and / or precious metals in a smelting furnace at a temperature 50-100°C above the metal melting point for 10-40 minutes to obtain a melt. Step 2: Pour the melt into the crystallizer or mold, and cool and solidify it by controlling the process parameters to obtain a single-crystal continuous casting rod billet or a rod billet with a typical directional solidification structure. Step 3: Perform multi-pass drawing or rolling deformation on the billet. By controlling the number of deformation passes, drawing speed or rolling speed and intermediate annealing node parameters, the continuous deformation of the wire and the coordinated regulation of mechanical properties and conductivity can be achieved. In step 2, the crystallizer includes a hot-type horizontal continuous casting crystallizer and a cold-type vertical continuous casting crystallizer, and the mold is an internally circulating water-cooled copper mold. The process parameters include the traction speed of the dummy bar and the temperature control of the mold. When using a hot-type horizontal continuous casting crystallizer, the traction speed of the dummy bar is 10-80 mm / min. When using a cold-type vertical continuous casting crystallizer, the traction speed of the dummy bar is 80-160 mm / min. When using a crucible mold, the temperature of the copper mold is controlled by circulating water cooling. In step 3, the deformation speed is 1000-1600 m / min when using drawing deformation and 10-20 m / min when using rolling deformation. The number of deformation passes in step 3 is 90-150 when using drawing deformation and 10-30 when using rolling deformation. In step 3, the intermediate annealing nodes are as follows: the first node is for a wire diameter of 1.15-1.30 mm, and the second node is for a wire diameter of 0.02-0.18 mm. The annealing temperature of the first node is 150-250℃, and the holding time is 5-10 min. The annealing temperature of the second node is 150-250℃, and the holding time is 10-30 min.

2. The method for synergistic control of the mechanical and conductive properties of copper and precious metal wires as described in claim 1, characterized in that, In step 2, the temperature of the crystallizer is controlled at 0-50°C above the metal melting point, and the temperature of the mold is controlled at 15-25°C.

3. The method for synergistic control of the mechanical and conductive properties of copper and precious metal wires as described in claim 1 or 2, characterized in that, The precious metals in step 1 mainly include: platinum-based, gold-based, silver-based, palladium-based, and rhodium-based alloys.

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