A gradient copper channel resistant to electrochemical corrosion and its preparation method

Abstract

This invention discloses an electrochemical corrosion-resistant gradient copper channel wire and its preparation method, relating to the field of copper channel wire technology. Using high-purity electrolytic copper as the matrix, trace alloying components such as Ni, Sn, V, Mo, Nd, Gd, and In are compounded. A micro-alloyed copper billet is obtained through vacuum melting, horizontal continuous casting, and Conform continuous extrusion. After surface activation pretreatment, a three-stage stepped temperature control is used to achieve thermally induced in-situ gradient phase transformation. Then, a multi-pass low-temperature roll forming process with progressively decreasing deformation is used to create a dense gradient structure. Finally, a low-temperature stress-relieving stabilization treatment is performed to obtain the finished product. This invention relies on the synergistic effect of multiple elements to form a continuous, dense passivation gradient layer on the surface of the copper material, achieving both high conductivity and long-term corrosion resistance.

Description

Technical Field

[0001] This invention relates to the field of copper channel technology, and in particular to a gradient copper channel resistant to electrochemical corrosion and its preparation method. Background Technology

[0002] Cable trays are core conductive components in rail transit, new energy power generation, and industrial power distribution, and are used for extended periods in complex environments such as humidity, salt spray, and industrial acids and alkalis. While traditional pure copper cable trays offer excellent conductivity, they suffer from significant electrochemical corrosion and have a short lifespan in salt spray environments. Frequent replacements not only increase maintenance costs but can also lead to power outages and safety accidents.

[0003] Currently, methods to improve the corrosion resistance of copper tubing mainly include electroplating protective layers, chemical conversion coatings, and alloying modification. While electroplating with nickel, chromium, or other protective layers can isolate corrosive media to a certain extent, the adhesion between the plating layer and the substrate is poor, making it prone to defects such as peeling and porosity. During long-term use, corrosive media can easily penetrate into the substrate through these defects, causing localized corrosion. Chemical conversion coatings, such as passivation films, are relatively thin and have poor wear resistance, failing to meet the long-term protection requirements under complex working conditions. Traditional alloying modification, by adding one or more alloying elements to copper, can improve overall corrosion resistance, but it significantly reduces the conductivity of copper, making it difficult to balance conductivity and corrosion resistance.

[0004] Gradient structure metallic materials, with their differentiated structural advantages of surface corrosion resistance and matrix performance preservation, have become a new technological direction for resolving the contradiction between corrosion resistance and functionality in metallic materials. Current research on gradient copper alloy wires largely focuses on wear resistance and high-strength modification, with a lack of designs specifically for electrochemical corrosion-resistant gradient structures for electrical cable trays. Furthermore, existing gradient wires suffer from problems such as abrupt structural gradient changes, weak interlayer bonding, uneven gradient layer thickness, and poor manufacturing process stability. Abrupt gradient changes lead to internal stress concentration in the wire, making it prone to delamination and cracking during bending and use. Simultaneously, discontinuous potential gradients cannot effectively suppress electrochemical micro-cell reactions, making it difficult to adapt to the special working conditions of long-term energization, repeated bending, and corrosion within closed tanks.

[0005] For example, invention patent document CN120442984A discloses a high conductivity gradient copper alloy channel wire and its preparation method. The composition, by mass percentage, includes: Ag 0.3-0.6%, rare earth elements 0.01-0.1%, Co 0.05-0.15%, Ni 0.02-0.12%, Ba 0.01-0.03%, Nb 0.05-0.8%, Ta 0.01-0.05%, Re 0.003-0.007%, Hf 0.08-0.2%, Mg 0.2-0.6%, carbon nanotubes 0.01-0.05%, fullerenes 0.01-0.03%, with the balance being Cu and other unavoidable impurities. The rare earth elements are Ce, La, and Y mixed in a mass ratio of (1-2):1:(0.8-1.2). This channel wire exhibits excellent mechanical properties, fatigue resistance, corrosion resistance, and electrical conductivity. However, it relies on the composite doping modification of multiple rare metals, carbon nanotubes and fullerenes, which has a complex formula and extremely high raw material costs. Moreover, it is still an exogenous component gradient modification and does not change the corrosion defects of the interfacial galvanic cell. Summary of the Invention

[0006] To overcome the defects in the above-mentioned technologies, the present invention provides an electrochemical corrosion resistant gradient copper channel wire and its preparation method. The copper channel wire has excellent electrochemical corrosion resistance, good conductivity, and long service life.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is: a method for preparing an electrochemical corrosion-resistant gradient copper trench line, comprising the following steps: Step S1, Preparation of microalloyed copper billet: Homogeneous round ingots are prepared by vacuum induction melting and electromagnetic horizontal continuous casting. After removing the 0.1-0.3 mm surface segregation layer by milling, the ingots are sent to a nitrogen-protected annealing furnace for annealing treatment. Then, Conform continuous extrusion molding is used, with an extrusion roller speed of 7-9 r / min, a steady-state temperature of 820-840℃ in the deformation zone, and a discharge speed of 8-10 m / min to directly extrude rectangular cross-section copper semi-finished billets to obtain microalloyed copper billets. Step S2, Surface activation pretreatment: The surface of the micro-alloyed copper billet is subjected to nano-level mirror polishing, ultrasonic degreasing with anhydrous ethanol, and activation with dilute sulfuric acid to remove the surface oxide layer and processing defects. Step S3, Segmented thermally induced in-situ gradient phase transformation: Three-stage temperature control is adopted, relying on the self-organized segregation of the billet, to gradually generate a gradient from the surface to the inside. Step S4, Low strain gradient densification shaping: Multi-pass small deformation rolling is used to densify the multi-element phase transformation structure of the surface layer; Step S5, Low-temperature stress stabilization treatment: Hold at 320~340℃ for 0.8~1.2h, then air cool to obtain a gradient copper trench line resistant to electrochemical corrosion.

[0008] Preferably, the microalloyed copper billet in step S1 comprises the following components by mass percentage: Ni 0.08–0.12%, Sn 0.05–0.1%, V 0.005–0.03%, Mo 0.008–0.04%, Nd 0.02–0.05%, Gd 0.01–0.05%, In 0.01–0.04%, Ca 0.001–0.01%, W 0.003–0.02%, with the balance being electrolytic copper raw material.

[0009] Preferably, the purity of the electrolytic copper raw material is ≥99.9995%.

[0010] Preferably, the vacuum induction melting specifically refers to a melting vacuum degree ≤ 4 × 10⁻⁶. -3 Pa, heating rate 7-9℃ / min to 1270-1290℃ to melt electrolytic copper raw material, after complete melting, Ni-Sn master alloy, V, Mo, W ultrafine metal powder, Te-Cu master alloy, Nd-Gd mixed rare earth, metal Ca particles, metal In ingot are added in sequence; after all alloy components are added, the temperature is raised to 1480-1520℃, and 4-6Hz electromagnetic stirring is turned on for 22-28min; then the temperature is lowered to 1210-1240℃ and allowed to stand for 14-16min to remove composite oxide slag, with trace argon gas partial pressure 0.004-0.006MPa for protection throughout the process; finally, the casting temperature is controlled at 1205-1220℃.

[0011] Preferably, the electromagnetic horizontal continuous casting uses a high-purity graphite-lined water-cooled crystallizer with a cooling water inlet temperature of 21-23℃, an outlet temperature ≤38℃, and a cooling water pressure of 0.31-0.33MPa; the ingot traction speed is 65-80mm / min; a 4-8Hz rotating magnetic field is set inside the crystallizer with an excitation current of 260-360A; after exiting the crystallizer, the ingot is cooled by a 1.7-1.9m long water mist spray, and the temperature of the ingot exiting the cooling section is controlled at 280-330℃; a 110-130mm severely segregated section is removed from both ends of the ingot before milling.

[0012] Preferably, the annealing treatment is performed at a temperature of 500–510°C for 2.5–3 hours.

[0013] Preferably, the Conform continuous extrusion molding process is as follows: the extrusion cylinder is preheated at 348-352℃, the forming die is preheated at 428-432℃, and the extrusion ratio is 22:1; after extrusion, the material is cooled online by strong air to below 220℃ before being wound up.

[0014] Preferably, the three-stage temperature control in step S3 is as follows: the first stage is to keep the temperature at 570-590℃ for 1.5-2 hours to complete the synchronous enrichment of multiple elements and phase transformation incubation on the surface; the second stage is to keep the temperature at 450-470℃ for 3.5-4.5 hours to achieve stepless gradient self-organized diffusion; and the third stage is to keep the temperature at 310-330℃ for 1-1.5 hours to complete the passivation and shaping of rare earth grain boundaries.

[0015] Preferably, the multi-pass small deformation rolling process in step S4 adopts a progressively decreasing rolling process. The deformation amount of the first 3 passes is 1.8% to 2.2%, the deformation amount of the middle 3 to 6 passes is 1.2% to 1.8%, which realizes the dense reorganization of the phase transformation structure grains. The deformation amount of the last pass is controlled at 0.6% to 1.2%, which completes low-stress precision shaping. The rolling speed throughout the process is 5 to 8 m / min, and the rolling temperature is maintained in the low temperature temperature change range of 280 to 310℃.

[0016] Preferably, the cross-sectional thickness of the copper channel wire in step S5 is 1.5 to 5.0 mm, and the width is 5 to 20 mm.

[0017] Another object of the present invention is to provide an electrochemically resistant gradient copper channel wire manufactured using the above-described method for preparing an electrochemically resistant gradient copper channel wire.

[0018] Due to the application of the above technical solution, the present invention has the following beneficial effects: (1) The electrochemical corrosion resistant gradient copper channel wire and its preparation method disclosed in this invention use high-purity electrolytic copper as the matrix, and combine it with trace amounts of nickel, tin, vanadium, molybdenum and small amounts of rare earth, indium, calcium and other elements for micro-alloying control. During the production process, the trace alloying elements can be orderly enriched on the surface of the channel wire to form a stable corrosion resistant structure, while the core matrix still maintains high conductivity. This structure fundamentally improves the problem of electrochemical corrosion of pure copper channel wire in salt spray, acid and alkali and humid environments, while basically retaining the original conductivity of the material. It can meet the high conductivity power supply requirements of rail transit, industrial power distribution and other scenarios. The overall raw material and manufacturing costs are lower, and it is suitable for mass production.

[0019] (2) The electrochemical corrosion resistant gradient copper trench and its preparation method disclosed in this invention adopt a three-stage temperature-controlled thermally induced in-situ gradient phase transformation process. Relying on the self-organized diffusion segregation of microalloying elements in the material itself, a stepless gradient structure with continuous transition from the surface to the interior is formed through segmented control of high-temperature inoculation, medium-temperature uniform diffusion, and low-temperature grain boundary passivation. This structure does not have obvious interface and structural abrupt changes, effectively alleviating the problem of internal stress concentration in the material and improving the bending crack resistance; at the same time, it achieves continuous potential transition, greatly weakening the driving force of the micro-battery electrochemical reaction, thereby inhibiting electrochemical corrosion.

[0020] (3) The electrochemical corrosion resistant gradient copper channel and its preparation method disclosed in this invention adopt a multi-pass progressively decreasing deformation rolling process to achieve layered densification control of the gradient structure in the low-temperature range: moderate deformation in the early stage achieves phase transformation grain reorganization and densification, stable deformation in the middle stage ensures uniform gradient layer thickness, and micro-deformation in the later stage completes low-stress precision shaping. This process can effectively eliminate micro-pores and structural defects generated during the phase transformation process, so that the surface gradient corrosion resistant structure forms a metallurgical bond with the matrix, with tight interlayer bonding and no risk of delamination. At the same time, it effectively reduces residual stress during forming, significantly improves the wear resistance, fatigue resistance, and bending resistance of the channel, avoids protective damage and matrix corrosion caused by mechanical property failure, effectively extends the overall service life of the channel, and reduces equipment operation and maintenance replacement costs.

[0021] (4) The electrochemical corrosion resistant gradient copper channel wire and its preparation method disclosed in this invention effectively solve common production problems such as ingot segregation, uneven structure, forming defects, and residual stress concentration through high-vacuum clean melting, magnetic field-assisted uniform continuous casting, precise temperature-controlled continuous extrusion, segmented gradient phase transformation shaping, and low-temperature stress stabilization treatment. The gradient copper channel wire prepared by this complete process has stable matching of corrosion resistance, electrical conductivity, and mechanical properties, high batch product consistency, and controllable quality, and can realize large-scale stable industrial production.

[0022] (5) The electrochemical corrosion resistant gradient copper channel wire and its preparation method disclosed in this invention, wherein the microalloyed copper billet comprises the following components by mass percentage: Ni 0.08-0.12%, Sn 0.05-0.1%, V 0.005-0.03%, Mo 0.008-0.04%, Nd 0.02-0.05%, Gd 0.01-0.05%, In 0.01-0.04%, Ca 0.001-0.01%, W 0.003-0.02%, with the balance being electrolytic copper raw material. Through the synergistic effect of each component, the microstructure, corrosion resistance, and mechanical properties of the copper channel wire are effectively optimized without sacrificing the high conductivity of the matrix. Ni and Sn can effectively increase the electrode potential of the copper matrix, weaken the tendency of electrochemical corrosion, and improve the overall resistance of the material to salt spray and acid and alkali corrosion. High-melting-point metal elements such as V, Mo, and W can refine the cast grains and purify the grain boundaries, suppress the problem of grain coarsening during high-temperature forming and heat treatment, and improve the structural stability and fatigue resistance of the material. Rare earth elements such as Nd and Gd can adsorb inclusions, eliminate microscopic defects in the matrix, passivate grain boundary corrosion channels, and significantly inhibit the penetration and diffusion of corrosive media along the grain boundaries. Trace amounts of In and Ca can further optimize the solid solution and segregation distribution of alloying elements, promote the uniform and continuous generation of subsequent thermally induced gradient phase transformation structures, and alleviate the performance inhomogeneity problem caused by component segregation. Each trace component performs its own function and works synergistically with each other, which not only avoids the drawback of traditional high-content alloy modification that significantly reduces conductivity, but also provides a reliable compositional basis for the stable forming of in-situ stepless gradient structures and long-term electrochemical corrosion resistance, so that the finished channel lines have excellent conductivity, corrosion resistance, and structural durability. Detailed Implementation

[0023] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0024] Example 1 A method for preparing an electrochemically resistant gradient copper trench line includes the following steps: Step S1, Preparation of microalloyed copper billet: Homogeneous round ingots are prepared by vacuum induction melting and electromagnetic horizontal continuous casting. After removing the 0.1mm surface segregation layer by milling, the ingots are sent to a nitrogen-protected annealing furnace for annealing. Then, Conform continuous extrusion molding is used with an extrusion roller speed of 7r / min, a steady-state temperature of 820℃ in the deformation zone, and a discharge speed of 8m / min to directly extrude rectangular cross-section copper semi-finished billets to obtain microalloyed copper billets. Step S2, Surface activation pretreatment: The surface of the micro-alloyed copper billet is subjected to nano-level mirror polishing, ultrasonic degreasing with anhydrous ethanol, and activation with dilute sulfuric acid to remove the surface oxide layer and processing defects. Step S3, Segmented thermally induced in-situ gradient phase transformation: Three-stage temperature control is adopted, relying on the self-organized segregation of the billet, to gradually generate a gradient from the surface to the inside. Step S4, Low strain gradient densification shaping: Multi-pass small deformation rolling is used to densify the multi-element phase transformation structure of the surface layer; Step S5, Low-temperature stress stabilization treatment: Hold at 320℃ for 0.8h, then air cool to obtain a gradient copper trench line resistant to electrochemical corrosion.

[0025] The microalloyed copper billet mentioned in step S1 comprises the following components by mass percentage: Ni 0.08%, Sn 0.05%, V 0.005%, Mo 0.008%, Nd 0.02%, Gd 0.01%, In 0.01%, Ca 0.001%, W 0.003%, with the balance being electrolytic copper raw material; the purity of the electrolytic copper raw material is ≥99.9995%.

[0026] The vacuum induction melting specifically refers to a melting vacuum degree ≤ 4 × 10⁻⁶. -3 Pa, heating rate 7℃ / min to 1270℃ to melt electrolytic copper raw material, after complete melting, Ni-Sn master alloy, V, Mo, W ultrafine metal powder, Te-Cu master alloy, Nd-Gd mixed rare earth, metal Ca particles, metal In ingot are added in sequence; after all alloy components are added, the temperature is raised to 1480℃, and 4Hz electromagnetic stirring is turned on for 22min; then the temperature is lowered to 1210℃ and left to stand for 14min to remove composite oxide slag, with trace argon gas partial pressure 0.004MPa for protection throughout the process; finally, the casting temperature is controlled at 1205℃.

[0027] The electromagnetic horizontal continuous casting uses a high-purity graphite-lined water-cooled crystallizer with an inlet water temperature of 21℃, an outlet water temperature ≤38℃, and a cooling water pressure of 0.31MPa. The ingot traction speed is 65mm / min, and a 4Hz rotating magnetic field with an excitation current of 260A is set inside the crystallizer. After exiting the crystallizer, the ingot is cooled by a 1.7m long water mist spray, and the temperature of the ingot exiting the cooling section is controlled at 280℃. A 110mm severe segregation section is removed from both the head and tail of the ingot before milling.

[0028] The annealing treatment is performed at a temperature of 500℃ for 2.5 hours. The Conform continuous extrusion molding process is as follows: the extrusion cylinder is preheated at 348℃, the forming die is preheated at 428℃, and the extrusion ratio is 22:1. After extrusion, the material is cooled online to below 220℃ by strong air and then wound up. The three-stage temperature control in step S3 is as follows: the first stage is held at 570℃ for 1.5 hours to complete the simultaneous enrichment of multiple elements and phase transformation inoculation on the surface; the second stage is held at 450℃ for 3.5 hours to achieve stepless gradient self-organized diffusion; and the third stage is held at 310℃ for 1 hour to complete the passivation and shaping of rare earth grain boundaries.

[0029] In step S4, the multi-pass small deformation rolling process adopts a progressively decreasing rolling process. The deformation amount of the first 3 passes is 1.8%, the deformation amount of the middle 3 to 6 passes is 1.2%, which realizes the dense reorganization of the phase transformation structure grains, and the deformation amount of the last pass is controlled at 0.6%. The rolling speed is 5m / min throughout the process, and the rolling temperature is maintained in the low temperature change range of 280℃. In step S5, the cross-sectional thickness of the copper groove line is 1.5mm and the width is 5mm.

[0030] An electrochemically resistant gradient copper channel wire manufactured using the above-mentioned method for preparing an electrochemically resistant gradient copper channel wire.

[0031] Example 2 A method for preparing an electrochemically resistant gradient copper trench line includes the following steps: Step S1, Preparation of microalloyed copper billet: Homogeneous round ingots are prepared by vacuum induction melting and electromagnetic horizontal continuous casting. After removing the 0.15mm surface segregation layer by milling, the ingots are sent to a nitrogen-protected annealing furnace for annealing. Then, Conform continuous extrusion molding is used with an extrusion roller speed of 7.5r / min, a steady-state temperature of 825℃ in the deformation zone, and a discharge speed of 8.5m / min to directly extrude rectangular cross-section copper semi-finished billets to obtain microalloyed copper billets. Step S2, Surface activation pretreatment: The surface of the micro-alloyed copper billet is subjected to nano-level mirror polishing, ultrasonic degreasing with anhydrous ethanol, and activation with dilute sulfuric acid to remove the surface oxide layer and processing defects. Step S3, Segmented thermally induced in-situ gradient phase transformation: Three-stage temperature control is adopted, relying on the self-organized segregation of the billet, to gradually generate a gradient from the surface to the inside. Step S4, Low strain gradient densification shaping: Multi-pass small deformation rolling is used to densify the multi-element phase transformation structure of the surface layer; Step S5, Low-temperature stress stabilization treatment: Hold at 325℃ for 0.9h, then air cool to obtain a gradient copper trench line resistant to electrochemical corrosion.

[0032] The microalloyed copper billet mentioned in step S1 comprises the following components by mass percentage: Ni 0.09%, Sn 0.06%, V 0.01%, Mo 0.01%, Nd 0.03%, Gd 0.02%, In 0.02%, Ca 0.003%, W 0.006%, with the balance being electrolytic copper raw material; the purity of the electrolytic copper raw material is ≥99.9995%.

[0033] The vacuum induction melting specifically refers to a melting vacuum degree ≤ 4 × 10⁻⁶. -3The electrolytic copper raw material was melted at 1275℃ with a heating rate of 7.5℃ / min. After complete melting, Ni-Sn master alloy, V, Mo, W ultrafine metal powder, Te-Cu master alloy, Nd-Gd mixed rare earth, metallic Ca particles, and metallic In ingot were added sequentially. After all alloy components were added, the temperature was raised to 1490℃ and electromagnetic stirring was started at 4.5Hz for 24 minutes. Then, the temperature was lowered to 1220℃ and allowed to stand for 14.5 minutes to remove the composite oxide slag. A trace amount of argon gas with a partial pressure of 0.0045MPa was used for protection throughout the process. Finally, the casting temperature was controlled at 1210℃.

[0034] The electromagnetic horizontal continuous casting uses a high-purity graphite-lined water-cooled crystallizer with an inlet cooling water temperature of 21.5℃, an outlet cooling water temperature ≤38℃, and a cooling water pressure of 0.32MPa. The ingot traction speed is 70mm / min, and a 5Hz rotating magnetic field with an excitation current of 280A is set inside the crystallizer. After exiting the crystallizer, the ingot undergoes a 1.8m long secondary water mist spray cooling process, with the ingot exiting the cooling section at a temperature controlled at 290℃. 115mm of severely segregated sections are removed from both ends of the ingot before milling. The annealing treatment is performed at a temperature of 503℃ for 2.7 hours. The Conform continuous extrusion molding process is as follows: the extrusion cylinder preheating temperature is 349℃, the forming die preheating temperature is 429℃, and the extrusion ratio is 22:1. After extrusion, the material is cooled online to below 220℃ by strong air cooling before being coiled.

[0035] The three-stage temperature control in step S3 is as follows: the first stage is a 575℃ holding temperature for 1.7h to complete the synchronous enrichment of multiple elements and phase transformation incubation on the surface; the second stage is a 455℃ holding temperature for 3.8h to achieve stepless gradient self-organized diffusion; the third stage is a 315℃ holding temperature for 1.2h to complete the passivation and shaping of rare earth grain boundaries; the multi-pass small deformation rolling in step S4 adopts a progressively decreasing rolling process, with the deformation amount of the first 3 passes being 1.9%, the deformation amount of the middle 3 to 6 passes being 1.4%, to achieve dense reorganization of the phase transformation structure grains, and the deformation amount of the last pass being controlled at 0.8%; the rolling speed throughout is 6m / min, and the rolling temperature is maintained in the low temperature change range of 290℃; the cross-sectional thickness of the copper groove line in step S5 is 2.5mm, and the width is 8mm.

[0036] An electrochemically resistant gradient copper channel wire manufactured using the above-mentioned method for preparing an electrochemically resistant gradient copper channel wire.

[0037] Example 3 A method for preparing an electrochemically resistant gradient copper trench line includes the following steps: Step S1, Preparation of microalloyed copper billet: Homogeneous round ingots are prepared by vacuum induction melting and electromagnetic horizontal continuous casting. After removing the 0.2mm surface segregation layer by milling, the ingots are sent to a nitrogen-protected annealing furnace for annealing. Then, Conform continuous extrusion molding is used with an extrusion roller speed of 8r / min, a steady-state temperature of 830℃ in the deformation zone, and a discharge speed of 9m / min to directly extrude rectangular cross-section copper semi-finished billets to obtain microalloyed copper billets. Step S2, Surface activation pretreatment: The surface of the micro-alloyed copper billet is subjected to nano-level mirror polishing, ultrasonic degreasing with anhydrous ethanol, and activation with dilute sulfuric acid to remove the surface oxide layer and processing defects. Step S3, Segmented thermally induced in-situ gradient phase transformation: Three-stage temperature control is adopted, relying on the self-organized segregation of the billet, to gradually generate a gradient from the surface to the inside. Step S4, Low strain gradient densification shaping: Multi-pass small deformation rolling is used to densify the multi-element phase transformation structure of the surface layer; Step S5, Low-temperature stress stabilization treatment: Hold at 330℃ for 1 hour, then air cool to obtain a gradient copper trench line resistant to electrochemical corrosion.

[0038] The microalloyed copper billet mentioned in step S1 comprises the following components by mass percentage: Ni 0.1%, Sn 0.08%, V 0.015%, Mo 0.025%, Nd 0.035%, Gd 0.03%, In 0.025%, Ca 0.006%, W 0.012%, with the balance being electrolytic copper raw material; the purity of the electrolytic copper raw material is ≥99.9995%.

[0039] The vacuum induction melting specifically refers to a melting vacuum degree ≤ 4 × 10⁻⁶. -3 Pa, heating rate 8℃ / min to 1280℃ to melt electrolytic copper raw material, after complete melting, Ni-Sn master alloy, V, Mo, W ultrafine metal powder, Te-Cu master alloy, Nd-Gd mixed rare earth, metal Ca particles, metal In ingot are added in sequence; after all alloy components are added, the temperature is raised to 1500℃, and 5Hz electromagnetic stirring is turned on for 25min; then the temperature is lowered to 1225℃ and left to stand for 15min to remove composite oxide slag, with trace argon gas partial pressure 0.005MPa for protection throughout the process; finally, the casting temperature is controlled at 1212℃.

[0040] The electromagnetic horizontal continuous casting uses a high-purity graphite-lined water-cooled crystallizer with an inlet water temperature of 22℃, an outlet water temperature ≤38℃, and a cooling water pressure of 0.32MPa. The ingot traction speed is 73mm / min, and a 6Hz rotating magnetic field with an excitation current of 320A is set inside the crystallizer. After exiting the crystallizer, the ingot is cooled by a 1.8m long water mist spray, and the temperature of the ingot exiting the cooling section is controlled at 310℃. A 120mm severe segregation section is removed from both the head and tail of the ingot before milling. The annealing treatment is performed at a temperature of 505℃ for 2.8 hours.

[0041] The Conform continuous extrusion molding process is as follows: the extrusion cylinder is preheated at 350°C, the forming die is preheated at 430°C, and the extrusion ratio is 22:1; after extrusion, the material is cooled online to below 220°C by strong air and then wound up; the three-stage temperature control in step S3 is as follows: the first stage is held at 580°C for 1.8 hours to complete the simultaneous enrichment of multiple elements on the surface and phase transformation inoculation; the second stage is held at 460°C for 4 hours to achieve stepless gradient self-organized diffusion; the third stage is held at 320°C for 1.3 hours to complete the passivation and shaping of rare earth grain boundaries.

[0042] In step S4, the multi-pass small deformation rolling process adopts a progressively decreasing rolling process. The deformation amount of the first 3 passes is 2%, the deformation amount of the middle 3 to 6 passes is 1.5%, which realizes the dense reorganization of the phase transformation structure grains. The deformation amount of the last pass is controlled at 0.9%, which completes the low-stress precision shaping. The rolling speed throughout the process is 6.5m / min, and the rolling temperature is maintained in the low temperature change range of 300℃. The cross-sectional thickness of the copper groove line in step S5 is 3.5mm and the width is 13mm.

[0043] An electrochemically resistant gradient copper channel wire manufactured using the above-mentioned method for preparing an electrochemically resistant gradient copper channel wire.

[0044] Example 4 A method for preparing an electrochemically resistant gradient copper trench line includes the following steps: Step S1, Preparation of microalloyed copper billet: Homogeneous round ingots are prepared by vacuum induction melting and electromagnetic horizontal continuous casting. After removing the 0.25mm surface segregation layer by milling, the ingots are sent to a nitrogen-protected annealing furnace for annealing. Then, Conform continuous extrusion molding is used with an extrusion roller speed of 8.5r / min, a steady-state temperature of 835℃ in the deformation zone, and a discharge speed of 9.5m / min to directly extrude rectangular cross-section copper semi-finished billets to obtain microalloyed copper billets. Step S2, Surface activation pretreatment: The surface of the micro-alloyed copper billet is subjected to nano-level mirror polishing, ultrasonic degreasing with anhydrous ethanol, and activation with dilute sulfuric acid to remove the surface oxide layer and processing defects. Step S3, Segmented thermally induced in-situ gradient phase transformation: Three-stage temperature control is adopted, relying on the self-organized segregation of the billet, to gradually generate a gradient from the surface to the inside. Step S4, Low strain gradient densification shaping: Multi-pass small deformation rolling is used to densify the multi-element phase transformation structure of the surface layer; Step S5, Low-temperature stress stabilization treatment: Hold at 335℃ for 1.1h, then air cool to obtain a gradient copper trench line resistant to electrochemical corrosion.

[0045] The microalloyed copper billet mentioned in step S1 comprises the following components by mass percentage: Ni 0.11%, Sn 0.09%, V 0.025%, Mo 0.03%, Nd 0.045%, Gd 0.04%, In 0.03%, Ca 0.008%, W 0.018%, with the balance being electrolytic copper raw material; the purity of the electrolytic copper raw material is ≥99.9995%.

[0046] The vacuum induction melting specifically refers to a melting vacuum degree ≤ 4 × 10⁻⁶. -3 The electrolytic copper raw material was melted at 1285℃ with a heating rate of 8.5℃ / min. After complete melting, Ni-Sn master alloy, V, Mo, W ultrafine metal powder, Te-Cu master alloy, Nd-Gd mixed rare earth, metallic Ca particles, and metallic In ingot were added sequentially. After all alloy components were added, the temperature was raised to 1510℃ and a 5.5Hz electromagnetic stirrer was turned on for 27 minutes. Then the temperature was lowered to 1235℃ and allowed to stand for 15.5 minutes to remove the composite oxide slag. A trace amount of argon gas with a partial pressure of 0.0055MPa was used for protection throughout the process. The final casting temperature was controlled at 1218℃.

[0047] The electromagnetic horizontal continuous casting uses a high-purity graphite-lined water-cooled crystallizer with an inlet cooling water temperature of 22.5℃, an outlet cooling water temperature ≤38℃, and a cooling water pressure of 0.33MPa. The ingot traction speed is 78mm / min, and a 7Hz rotating magnetic field with an excitation current of 350A is set inside the crystallizer. After exiting the crystallizer, the ingot undergoes a 1.9m long secondary water mist spray cooling process, with the ingot exiting the cooling section at a temperature controlled at 320℃. 125mm of severely segregated sections are removed from both ends of the ingot before milling. The annealing treatment is performed at a temperature of 508℃ for 2.9 hours. The Conform continuous extrusion molding process is as follows: the extrusion cylinder preheating temperature is 351℃, the forming die preheating temperature is 431℃, and the extrusion ratio is 22:1. After extrusion, the material is cooled online to below 220℃ by strong air cooling before being coiled.

[0048] The three-stage temperature control in step S3 is as follows: the first stage is a 585℃ holding temperature for 1.9h to complete the synchronous enrichment of multiple elements and phase transformation incubation on the surface; the second stage is a 465℃ holding temperature for 4.3h to achieve stepless gradient self-organized diffusion; the third stage is a 325℃ holding temperature for 1.4h to complete the passivation and shaping of rare earth grain boundaries; the multi-pass small deformation rolling in step S4 adopts a progressively decreasing rolling process, with the deformation amount of the first 3 passes being 2.1%, the deformation amount of the middle 3 to 6 passes being 1.7%, to achieve dense reorganization of the phase transformation structure grains, and the deformation amount of the last pass being controlled at 1.1%, to complete low-stress precision shaping; the rolling speed throughout is 7.5m / min, and the rolling temperature is maintained in the low-temperature temperature change range of 305℃; the cross-sectional thickness of the copper groove line in step S5 is 4.0mm, and the width is 18mm.

[0049] An electrochemically resistant gradient copper channel wire manufactured using the above-mentioned method for preparing an electrochemically resistant gradient copper channel wire.

[0050] Example 5 A method for preparing an electrochemically resistant gradient copper trench line includes the following steps: Step S1, Preparation of microalloyed copper billet: Homogeneous round ingots are prepared by vacuum induction melting and electromagnetic horizontal continuous casting. After removing the 0.3mm surface segregation layer by milling, the ingots are sent to a nitrogen-protected annealing furnace for annealing. Then, Conform continuous extrusion molding is used with an extrusion roller speed of 9r / min, a steady-state temperature of 840℃ in the deformation zone, and a discharge speed of 10m / min to directly extrude rectangular cross-section copper semi-finished billets to obtain microalloyed copper billets. Step S2, Surface activation pretreatment: The surface of the micro-alloyed copper billet is subjected to nano-level mirror polishing, ultrasonic degreasing with anhydrous ethanol, and activation with dilute sulfuric acid to remove the surface oxide layer and processing defects. Step S3, Segmented thermally induced in-situ gradient phase transformation: Three-stage temperature control is adopted, relying on the self-organized segregation of the billet, to gradually generate a gradient from the surface to the inside. Step S4, Low strain gradient densification shaping: Multi-pass small deformation rolling is used to densify the multi-element phase transformation structure of the surface layer; Step S5, Low-temperature stress stabilization treatment: Hold at 340℃ for 1.2h, then air cool to obtain a gradient copper trench line resistant to electrochemical corrosion.

[0051] The microalloyed copper billet mentioned in step S1 comprises the following components by mass percentage: Ni 0.12%, Sn 0.1%, V 0.03%, Mo 0.04%, Nd 0.05%, Gd 0.05%, In 0.04%, Ca 0.01%, W 0.02%, with the balance being electrolytic copper raw material; the purity of the electrolytic copper raw material is ≥99.9995%.

[0052] The vacuum induction melting specifically refers to a melting vacuum degree ≤ 4 × 10⁻⁶.-3 Pa, heating rate 9℃ / min to 1290℃ to melt electrolytic copper raw material, after complete melting, Ni-Sn master alloy, V, Mo, W ultrafine metal powder, Te-Cu master alloy, Nd-Gd mixed rare earth, metal Ca particles, metal In ingot are added in sequence; after all alloy components are added, the temperature is raised to 1520℃, and 6Hz electromagnetic stirring is turned on for 28min; then the temperature is lowered to 1240℃ and left to stand for 16min to remove composite oxide slag, with trace argon gas partial pressure 0.006MPa for protection throughout the process; finally, the casting temperature is controlled at 1220℃.

[0053] The electromagnetic horizontal continuous casting uses a high-purity graphite-lined water-cooled crystallizer with an inlet cooling water temperature of 23℃, an outlet cooling water temperature ≤38℃, and a cooling water pressure of 0.33MPa. The ingot traction speed is 80mm / min, and an 8Hz rotating magnetic field with an excitation current of 360A is set inside the crystallizer. After exiting the crystallizer, the ingot undergoes a 1.9m long secondary water mist spray cooling process, with the ingot exiting the cooling section at a temperature controlled at 330℃. 130mm of severely segregated sections are removed from both ends of the ingot before milling. The annealing treatment is performed at 510℃ for 3 hours. The Conform continuous extrusion molding process is as follows: the extrusion cylinder preheating temperature is 352℃, the forming die preheating temperature is 432℃, and the extrusion ratio is 22:1. After extrusion, the material is cooled online to below 220℃ by strong air cooling before being coiled.

[0054] The three-stage temperature control in step S3 is as follows: the first stage is held at 590℃ for 2 hours to complete the synchronous enrichment of multiple elements and phase transformation incubation on the surface; the second stage is held at 470℃ for 4.5 hours to achieve stepless gradient self-organized diffusion; the third stage is held at 330℃ for 1.5 hours to complete the passivation and shaping of rare earth grain boundaries; the multi-pass small deformation rolling in step S4 adopts a progressively decreasing rolling process, with the deformation amount of the first 3 passes being 2.2%, the deformation amount of the middle 3 to 6 passes being 1.8%, to achieve dense reorganization of phase transformation grains, and the deformation amount of the last pass being controlled at 1.2%, to complete low-stress precision shaping; the rolling speed throughout is 8m / min, and the rolling temperature is maintained in the low temperature change range of 310℃; the cross-sectional thickness of the copper groove line in step S5 is 5.0mm, and the width is 20mm.

[0055] An electrochemically resistant gradient copper channel wire manufactured using the above-mentioned method for preparing an electrochemically resistant gradient copper channel wire.

[0056] Comparative Example 1 An electrochemical corrosion resistant gradient copper channel and its preparation method are basically the same as those in Example 5, except that an equal amount of V is used instead of Mo.

[0057] Comparative Example 2 An electrochemical corrosion resistant gradient copper channel and its preparation method are basically the same as those in Example 5, except that an equal amount of Mo is used instead of V.

[0058] Comparative Example 3 A gradient copper trench line resistant to electrochemical corrosion and its preparation method are basically the same as those in Example 5, except that an equal amount of Nd is used instead of In.

[0059] Comparative Example 4 A gradient copper trench line resistant to electrochemical corrosion and its preparation method are basically the same as those in Example 5, except that an equal amount of In is used instead of Nd.

[0060] Comparative Example 5 A gradient copper channel resistant to electrochemical corrosion and its preparation method are basically the same as those in Example 5, except that the three-stage temperature control is not used, but the channel is directly kept at 500°C for 8 hours.

[0061] Comparative Example 6 A gradient copper channel line resistant to electrochemical corrosion and its preparation method are basically the same as those in Example 5, except that instead of using multiple small deformation roll forming, the deformation is done in one pass with a deformation amount of 13.2%.

[0062] To further illustrate the beneficial technical effects of the electrochemical corrosion-resistant gradient copper trench lines prepared by the present invention, relevant performance tests were conducted on the electrochemical corrosion-resistant gradient copper trench lines involved in Example 5 and Comparative Examples 1-6. The test results are shown in Table 1, and the test methods are as follows: (1) Conductivity test: The test shall be conducted in accordance with GB / T351-2019; (2) Neutral salt spray resistance test: The neutral salt spray test was conducted in accordance with GB / T 10125-2021 (5% NaCl solution, 35℃, continuous spraying for 1300 hours, spray volume of 2mL / 80 (cm)). 2 •h), observe the corrosion on the sample surface.

[0063] (3) Electrochemical corrosion resistance: Referring to GB / T 24196-2009 "Electrochemical test method for corrosion of metals and alloys - guideline for potentiostatic and potentiodynamic polarization measurement", the potentiodynamic polarization electrochemical corrosion performance test of each group of copper alloy tank line samples was carried out using the classic three-electrode test system. The test tank line sample was used as the working electrode, the saturated calomel electrode as the reference electrode, and the platinum sheet electrode as the auxiliary electrode. The test medium was a neutral sodium chloride solution with a mass fraction of 3.5% at 25℃. After the open circuit potential of the system stabilized, the polarization curve was tested at a constant scan rate of 10mV / min. The scan range was ±70mV relative to the stable open circuit potential. The core electrochemical parameters such as the self-corrosion potential and corrosion current density of the sample were obtained by fitting and analysis.

[0064] Table 1. Test results of electrochemical corrosion resistant gradient copper cable performance

[0065] As shown in Table 1, Example 5, using the micro-element microalloying compounding, three-stage thermally induced in-situ gradient phase transformation, and multi-pass progressively decreasing deformation low-temperature rolling synergistic process of the present invention, produced gradient copper grooves with a surface conductivity of 98.3% IACS, significantly higher than that of the comparative examples. After 1300 hours of neutral salt spray testing, the sample surface showed no pitting corrosion or oxidation discoloration, and the surface passivation film remained intact and continuous. Its self-corrosion potential was -0.126V (vs SCE), the most positive among all samples, with the lowest thermodynamic corrosion tendency, and a corrosion current density of only 0.061μA / cm. 2 The corrosion kinetics dissolution rate was the slowest. Compared with Comparative Examples 1-4, which only replaced single alloying elements such as V, Mo, Nd, and In, Comparative Example 5, which eliminated the segmented gradient heat treatment, and Comparative Example 6, which used single-pass large deformation rolling, all groups of samples showed simultaneous deterioration phenomena such as decreased conductivity, increased salt spray corrosion defects, negative shift of self-corrosion potential, and increased corrosion current density. This proves that the alloy composition matching, segmented gradient temperature control, and graded small deformation rolling process specified in this invention can work together to improve the material's comprehensive performance in resisting neutral salt spray and electrochemical corrosion while ensuring high conductivity.

[0066] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. Any modifications, equivalent substitutions and improvements 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 preparing an electrochemically resistant gradient copper channel, characterized in that, Includes the following steps: Step S1, Preparation of microalloyed copper billet: Homogeneous round ingots are prepared by vacuum induction melting and electromagnetic horizontal continuous casting. After removing the 0.1-0.3 mm surface segregation layer by milling, the ingots are sent to a nitrogen-protected annealing furnace for annealing treatment. Then, Conform continuous extrusion molding is used, with the extrusion roller speed of 7-9 r / min, the steady-state temperature of the deformation zone of 820-840℃, and the discharge speed of 8-10 m / min to directly extrude rectangular cross-section copper semi-finished billets to obtain micro-alloyed copper billets; Step S2, Surface activation pretreatment: The surface of the micro-alloyed copper billet is subjected to nano-level mirror polishing, ultrasonic degreasing with anhydrous ethanol, and activation with dilute sulfuric acid to remove the surface oxide layer and processing defects. Step S3, Segmented thermally induced in-situ gradient phase transformation: Three-stage temperature control is adopted, relying on the self-organized segregation of the billet, to gradually generate a gradient from the surface to the inside. Step S4, Low strain gradient densification shaping: Multi-pass small deformation rolling is used to densify the multi-element phase transformation structure of the surface layer; Step S5, Low-temperature stress stabilization treatment: Hold at 320~340℃ for 0.8~1.2h, then air cool to obtain a gradient copper trench line resistant to electrochemical corrosion.

2. The method for preparing electrochemical corrosion resistant gradient copper trench lines according to claim 1, characterized in that, The microalloyed copper billet mentioned in step S1 comprises the following components by mass percentage: Ni 0.08–0.12%, Sn 0.05–0.1%, V 0.005–0.03%, Mo 0.008–0.04%, Nd 0.02–0.05%, Gd 0.01–0.05%, In 0.01–0.04%, Ca 0.001–0.01%, W 0.003–0.02%, with the balance being electrolytic copper raw material; the purity of the electrolytic copper raw material is ≥99.9995%.

3. The method for preparing the electrochemical corrosion-resistant gradient copper trench line according to claim 1, characterized in that, The vacuum induction melting specifically refers to a melting vacuum degree ≤ 4 × 10⁻⁶. -3 Pa, heating rate 7-9℃ / min to 1270-1290℃ to melt electrolytic copper raw material, after complete melting, Ni-Sn master alloy, V, Mo, W ultrafine metal powder, Te-Cu master alloy, Nd-Gd mixed rare earth, metal Ca particles, metal In ingot are added in sequence; after all alloy components are added, the temperature is raised to 1480-1520℃, and 4-6Hz electromagnetic stirring is turned on for 22-28min; then the temperature is lowered to 1210-1240℃ and allowed to stand for 14-16min to remove composite oxide slag, with trace argon gas partial pressure 0.004-0.006MPa for protection throughout the process; finally, the casting temperature is controlled at 1205-1220℃.

4. The method for preparing electrochemical corrosion resistant gradient copper trench lines according to claim 1, characterized in that, The electromagnetic horizontal continuous casting uses a high-purity graphite-lined water-cooled crystallizer. The cooling water inlet temperature is 21-23℃, the outlet temperature is ≤38℃, and the cooling water pressure is 0.31-0.33MPa. The ingot traction speed is 65-80mm / min. A 4-8Hz rotating magnetic field is set inside the crystallizer, and the excitation current is 260-360A. After exiting the crystallizer, the ingot is cooled by a 1.7-1.9m long water mist spray. The temperature of the ingot exiting the cooling section is controlled at 280-330℃. A 110-130mm severely segregated section is removed from both ends of the ingot before milling.

5. The method for preparing electrochemical corrosion resistant gradient copper trench lines according to claim 1, characterized in that, The annealing process is performed at a temperature of 500–510°C for 2.5–3 hours.

6. The method for preparing the electrochemical corrosion-resistant gradient copper trench line according to claim 1, characterized in that, The Conform continuous extrusion molding process is as follows: the extrusion cylinder is preheated at 348-352℃, the forming die is preheated at 428-432℃, and the extrusion ratio is 22:1; after extrusion, the material is cooled online to below 220℃ by strong air cooling before being wound up.

7. The method for preparing the electrochemical corrosion-resistant gradient copper trench line according to claim 1, characterized in that, The three-stage temperature control in step S3 is as follows: the first stage is to keep the temperature at 570-590℃ for 1.5-2 hours to complete the synchronous enrichment of multiple elements and phase transformation incubation on the surface; the second stage is to keep the temperature at 450-470℃ for 3.5-4.5 hours to achieve stepless gradient self-organized diffusion; and the third stage is to keep the temperature at 310-330℃ for 1-1.5 hours to complete the passivation and shaping of rare earth grain boundaries.

8. The method for preparing the electrochemical corrosion-resistant gradient copper trench line according to claim 1, characterized in that, In step S4, the multi-pass small deformation rolling process adopts a progressively decreasing rolling process. The deformation amount of the first 3 passes is 1.8% to 2.2%, the deformation amount of the middle 3 to 6 passes is 1.2% to 1.8%, which realizes the dense reorganization of the phase transformation structure grains. The deformation amount of the last pass is controlled at 0.6% to 1.2%, which completes the low-stress precision shaping. The rolling speed throughout the process is 5 to 8 m / min, and the rolling temperature is maintained in the low temperature temperature change range of 280 to 310℃.

9. The method for preparing the electrochemical corrosion-resistant gradient copper trench line according to claim 1, characterized in that, The cross-sectional thickness of the copper channel wire mentioned in step S5 is 1.5 to 5.0 mm, and the width is 5 to 20 mm.

10. An electrochemically resistant gradient copper channel wire manufactured using the method for preparing an electrochemically resistant gradient copper channel wire according to any one of claims 1-9.

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