High-current-carrying-density copper-clad aluminum slot wire WIC superconducting wire

Abstract

The invention belongs to the technical field of superconducting material processing, and discloses a preparation method of a high-current-carrying-density copper-clad aluminum slot wire WIC superconducting wire. According to the invention, the copper-clad aluminum rod is straightened, flattened, rolled and bent to obtain the thin-wall copper-clad aluminum slot line, so that the production efficiency is high and the production cost is low. The wall thickness of the copper-clad aluminum groove wire is only 0.10-0.20 mm, the proportion of the copper-clad aluminum groove wire in the wire is remarkably reduced, the high current density of the wire is ensured, meanwhile, the copper-clad aluminum groove wire can be evenly stressed in the groove machining process through the preparation method, even if the low-thickness design is adopted, it can still be ensured that the coating effect of a copper layer and the aluminum groove wire is even and compact, and the service life of the copper-clad aluminum groove wire is prolonged. And the welding quality is ensured. The prepared thin-wall copper-clad aluminum slot wire is of a structure with the square outside and the round inside, and the prepared copper-clad aluminum slot wire WIC is better in stability, suitable for batch production and wide in application prospect.

Description

Technical Field

[0001] This invention belongs to the field of superconducting material processing technology and relates to a high current-carrying-density copper-clad aluminum grooved wire WIC superconducting wire. Background Technology

[0002] Wire-in-channel (WIC) superconducting wire is a composite wire combining aluminum channel wire and superconducting round wire. This material not only possesses the zero-resistance characteristics of superconducting materials, enabling efficient and lossless current transmission, but also exhibits high strength, lightweight, and good stability due to its structure and material composition. It is primarily used in magnetic levitation transportation, energy, and communications, and is a key material in the manufacture of superconducting magnets for achieving efficient and stable levitation and propulsion of maglev trains.

[0003] Because aluminum is prone to oxidation, the oxide film formed on the aluminum surface during welding with the copper substrate of superconducting round wires affects the bonding strength and conductivity of the weld joint, increasing welding difficulty and reducing weldability. Copper-clad aluminum channel wire (WIC) can effectively solve this technical problem. Traditional WIC wire is made by drawing, rolling, and shaping aluminum rods into aluminum channel wires; after deoxidation treatment, a copper layer is electroplated onto the surface of the aluminum channel wires to obtain copper-clad aluminum channel wires; then, superconducting round wires are inlaid and welded to the copper-clad aluminum channel wires to obtain WIC superconducting wires.

[0004] Traditional methods for electroplating copper layers suffer from low production efficiency, making large-scale industrial production difficult. Furthermore, the high cost of electroplating equipment and chemical reagents, coupled with the need for centralized treatment of pollutants, further increases costs. Meanwhile, copper-clad aluminum channel wires typically have thick walls to ensure sufficient strength, allowing for the winding of lengths of tens of thousands of meters onto a single reel without deformation or breakage. However, the large cross-sectional area of ​​the copper-clad aluminum substrate results in low engineering current density in the produced WIC superconducting copper-clad aluminum channel wires, limiting their application range. Therefore, developing a high-efficiency, low-cost, and high-current-density method for manufacturing WIC superconducting copper-clad aluminum channel wires is of great significance. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for preparing high current-density copper-clad aluminum channel wire (WIC superconducting wire). This invention obtains thin-walled copper-clad aluminum channel wire by straightening, flattening, rolling, and bending copper-clad aluminum rods, resulting in high production efficiency and low production costs. The wall thickness of the copper-clad aluminum channel wire in this invention is only 0.10~0.20mm, significantly reducing the proportion of copper-clad aluminum channel wire in the wire material and ensuring high current density. Simultaneously, the preparation method provided by this invention ensures uniform stress distribution during channel processing, guaranteeing a uniform and dense coating effect between the copper layer and the aluminum channel wire even with a low-thickness design, thus ensuring welding quality. The thin-walled copper-clad aluminum channel wire prepared by this invention has an "outer square, inner round" structure, resulting in better stability of the prepared WIC wire material, suitable for mass production, and with broad application prospects.

[0006] On the one hand, the present invention provides a method for preparing high current-density copper-clad aluminum trench wire WIC superconducting wire, specifically including the following steps: S1: The copper-clad aluminum rod is straightened and flattened to obtain a copper-clad aluminum flat strip. It is then rolled in three passes, annealed online, cooled, and passivated to obtain a flat, irregularly shaped, soft copper-clad aluminum flat strip with the plane facing upwards.

[0007] Furthermore, the volume percentage of copper in the copper-clad aluminum rod is 5%~10%. The straightening process ensures that the original bending and twisting of the copper-clad aluminum rod are completely eliminated, allowing it to enter the rolling mill straight and smoothly, with the straightening degree not exceeding 1%. The annealing temperature is 200~350℃. The passivating agent used in the passivation treatment is RSB607, with a concentration of 5%~10%, the passivating agent solution temperature is 50±5℃, and the immersion distance is 1~2m.

[0008] Furthermore, the thickness of the thinnest part of the irregularly shaped soft copper-clad aluminum flat strip is 0.15~0.30mm. The soft irregularly shaped copper-clad aluminum flat strip must be flat during the wiring process. No obvious unevenness is allowed in a single layer of flat strip to avoid damage or deformation of the copper-clad aluminum flat strip, which would affect subsequent processing.

[0009] Furthermore, the irregularly shaped soft copper-clad aluminum flat strip conductor has a flat upper surface and a continuous wave-like shape composed of concave and convex arcs below. The length of the flat surface is 1.01 to 1.05 times the circumference of the NbTi / Cu composite circular wire, and the angle of the convex arc is 90°. The formula for calculating the radius (R) is as follows: In the formula, d1 is 1.01 to 1.05 times the diameter of the superconducting circular wire, and h is the thickness of the thinnest part of the irregular soft copper-clad aluminum flat strip. The concave arc parameters can be calculated by using the geometric constraint relationship of the circular arc transition based on the above-mentioned convex arc angle, convex arc radius, and thinnest part thickness.

[0010] S2: The irregularly shaped soft copper-clad aluminum flat strip is passed through the bending machine and the forming concave cam group in sequence to obtain the thin-walled copper-clad aluminum channel wire. The thin-walled copper-clad aluminum channel wire is passed through the fluxing machine and the liquid solder bath. Then, the superconducting round wire and the thin-walled copper-clad aluminum channel wire are passed through the pre-bonding mold and the inlay mold in sequence. Welding is performed at the inlay mold to obtain the high current carrying density copper-clad aluminum channel wire WIC superconducting wire.

[0011] Furthermore, the thin-walled copper-clad aluminum channel is a rounded pentagon with missing apex corners. The wall thickness of the rounded pentagon with missing apex corners is 0.10~0.20mm, the bending angle of the two bottom corners is 120°, and the bending angle of the two corners on both sides of the apex corner is 90°.

[0012] Furthermore, flux is added to the welding machine. This invention does not specifically limit the type of flux, and those skilled in the art can use conventional flux.

[0013] Furthermore, the temperature of the liquid solder is 260~450℃, the pre-bonding mold is immersed in the liquid solder, and the bending angle of the two corners on both sides of the apex of the thin-walled copper-clad aluminum channel line by the pre-bonding mold is 100°. The total processing volume of the pre-bonding mold and the inlay mold is 10%~20%, and the welding speed is 20~120m / min. After the liquid solder reaches the set temperature, the superconducting round wire and the thin-walled copper-clad aluminum channel line are passed through the pre-bonding mold.

[0014] Furthermore, the superconducting round wire is a copper-based superconducting round wire. This invention does not specifically limit the type of copper matrix for the copper-based superconducting round wire. Those skilled in the art can use oxygen-free copper, deoxidized copper, pure copper, copper alloys, etc. as the copper matrix.

[0015] Furthermore, the main function of the pre-bonded mold is to press the superconducting round wire into the thin-walled copper-clad aluminum groove wire and pre-form it, so as to avoid the problems of poor stability and insufficient coating caused by direct forming.

[0016] S3: High current density copper-clad aluminum channel wire WIC superconducting wire is characterized by surface and deep welding defects using a particle detector and eddy current flaw detector to ensure that the number of surface solder nodules and deep solder joint defects does not exceed 1 per 1000m.

[0017] On the other hand, the present invention claims protection for a high current-density copper-clad aluminum grooved wire WIC superconducting wire, which is prepared by the above-described method.

[0018] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages: (1) In this invention, after preparing the copper-clad aluminum rod into an irregularly shaped soft copper-clad aluminum flat strip, it is bent online to obtain a thin-walled copper-clad aluminum channel profile with an "outer square and inner circle" shape. Further surface finishing is then performed to obtain a thin-walled copper-clad aluminum channel with high dimensional accuracy. This channel is then simultaneously inlaid and welded with a copper-based superconducting round wire using liquid solder to obtain a high current-density copper-clad aluminum channel WIC superconducting wire. The preparation method provided by this invention can obtain thin-walled copper-clad aluminum channel wire through simple straightening, flattening, rolling, and bending, resulting in high production efficiency and requiring simple equipment with low production costs. The "outer square and inner circle" thin-walled copper-clad aluminum channel structure provided by this invention has better stability than copper-clad aluminum channel wire processed from U-shaped copper-clad aluminum channel wire, making it more suitable for mass production. The outer contour of the thin-walled copper-clad aluminum channel wire of this invention facilitates centering and positioning during processing, while the inner circular channel body ensures more uniform radial stress during copper layer cladding. The thin-walled design allows the copper layer to tightly adhere to the copper substrate superconducting circular wire, resulting in a gap-free and void-free interface. This leads to a more balanced stress distribution under thermal cycling / vibration, reducing the likelihood of copper layer peeling or cracking. In contrast, U-shaped copper-clad aluminum channel wires are prone to insufficient cladding and uneven thickness on the open side. Stress concentration at the opening during thermal cycling and long-term vibration can easily cause copper layer warping and interface peeling, resulting in poor stability. This invention limits the planar length of the irregularly shaped soft copper-clad aluminum flat strip to 1.01 to 1.05 times the circumference of the NbTi / Cu composite circular wire. Within this range, it effectively prevents the problem of localized superconducting wire accumulation.

[0019] (2) The wall thickness of the copper-clad aluminum channel wire of the present invention is 0.10~0.20mm, which significantly reduces the cross-sectional area ratio of the copper-clad aluminum substrate compared to traditional processes. Due to the uniform stress distribution of the copper-clad aluminum channel wire during the processing of the channel wire by the preparation method of the present invention, the low thickness of the copper-clad aluminum channel wire can ensure that there is no aluminum leakage during the processing. This not only ensures uniform copper coating and improves welding quality, but also significantly reduces the proportion of the copper-clad aluminum channel wire in the wire, ensuring high current density of the wire. The thickness of the U-shaped copper-clad aluminum channel wire prepared by the existing process is usually greater than 0.45mm. Since the proportion of the aluminum substrate in the WIC superconducting wire is large, the engineering current density is low. The copper-clad aluminum channel wire prepared by the present invention with a smaller wall thickness can significantly improve the engineering current density of the wire. The present invention also pre-forms the copper substrate superconducting round wire into the thin-walled copper-clad aluminum channel wire by pressing it into the thin wall, avoiding the problems of poor stability and insufficient coating caused by direct forming. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1This is a schematic cross-sectional view of an irregularly shaped, soft copper-clad aluminum flat strip. The labels in the attached diagram are as follows: 1 represents the thinnest part, 2 represents the convex arc, 3 represents the concave arc, 4 represents copper, and 5 represents aluminum.

[0022] Figure 2 This is a schematic diagram of the cross-section of a thin-walled copper-clad aluminum channel.

[0023] Figure 3 This is a schematic diagram of a cross-section of a superconducting circular wire. The labels in the attached diagram are as follows: 6 represents the copper matrix, and 7 represents the superconducting phase.

[0024] Figure 4 This is a schematic diagram of the cross-section of a high current-density copper-clad aluminum channel wire (WIC superconducting wire). Detailed Implementation

[0025] The technical solution of the present invention will be described below with reference to embodiments. However, the present invention is not limited to the following embodiments. Unless otherwise specified, the experimental methods and detection methods described in each embodiment are conventional methods; unless otherwise specified, the reagents and materials can be purchased commercially. Unless otherwise specified, the percentages in the following embodiments refer to mass percentages.

[0026] The calculation method for the processing amount of the present invention is: (S1-S2) / S1, where S1 is the cross-sectional area of ​​the wire before processing and S2 is the cross-sectional area of ​​the wire after processing.

[0027] The preparation method of high current-density copper-clad aluminum channel wire (WIC) superconducting wire includes the following steps: S1: The copper-clad aluminum rod is straightened and flattened to obtain a copper-clad aluminum flat strip. It is then rolled in three passes, annealed online, cooled, and passivated to obtain a flat, irregularly shaped, soft copper-clad aluminum flat strip with the plane facing upwards.

[0028] Furthermore, the volume percentage of copper in the copper-clad aluminum rod is 5%~10%. The straightening process ensures that the original bending and twisting of the copper-clad aluminum rod are completely eliminated, allowing it to enter the rolling mill straight and smoothly, with the straightening degree not exceeding 1%. The annealing temperature is 200~350℃. The passivating agent used in the passivation treatment is RSB607, with a concentration of 5%~10%, the passivating agent solution temperature is 50±5℃, and the immersion distance is 1~2m.

[0029] Furthermore, the thickness of the thinnest part of the irregularly shaped soft copper-clad aluminum flat strip is 0.15~0.30mm. The soft irregularly shaped copper-clad aluminum flat strip must be flat during the wiring process. No obvious unevenness is allowed in a single layer of flat strip to avoid damage or deformation of the copper-clad aluminum flat strip, which would affect subsequent processing.

[0030] Furthermore, the irregularly shaped soft copper-clad aluminum flat strip conductor has a flat upper surface and a continuous wave-like shape composed of concave and convex arcs below. The length of the flat surface is 1.01 to 1.05 times the circumference of the NbTi / Cu composite circular wire, and the angle of the convex arc is 90°. The formula for calculating the radius (R) is as follows: In the formula, d1 is 1.01 to 1.05 times the diameter of the NbTi / Cu composite circular wire, and h is the thickness of the thinnest part of the irregular soft copper-clad aluminum flat strip. The concave arc parameters can be calculated by using the geometric constraint relationship of the circular arc transition based on the above-mentioned convex arc angle, convex arc radius, and thinnest part thickness.

[0031] S2: The irregularly shaped soft copper-clad aluminum flat strip is passed through the bending machine and the forming concave cam group in sequence to obtain the thin-walled copper-clad aluminum channel wire. The thin-walled copper-clad aluminum channel wire is passed through the fluxing machine (with flux added) and the liquid solder bath. Then, the superconducting round wire and the thin-walled copper-clad aluminum channel wire are passed through the pre-bonding mold and the inlay mold in sequence. Welding is performed at the inlay mold to obtain the high current carrying density copper-clad aluminum channel wire WIC superconducting wire.

[0032] Furthermore, the thin-walled copper-clad aluminum channel is a rounded pentagon with missing apex corners. The wall thickness of the rounded pentagon with missing apex corners is 0.10~0.20mm, the bending angle of the two bottom corners is 120°, and the bending angle of the two corners on both sides of the apex corner is 90°.

[0033] Furthermore, the temperature of the liquid solder is 260~450℃, the pre-bonding mold is immersed in the liquid solder, and the bending angle of the two corners on both sides of the apex of the thin-walled copper-clad aluminum channel line by the pre-bonding mold is 100°. The total processing volume of the pre-bonding mold and the inlay mold is 10%~20%, and the welding speed is 20~120m / min. After the liquid solder reaches the set temperature, the superconducting round wire and the thin-walled copper-clad aluminum channel line are passed through the pre-bonding mold.

[0034] Furthermore, the superconducting round wire is a copper-based superconducting round wire. This invention does not specifically limit the type of copper matrix for the copper-based superconducting round wire. Those skilled in the art can use one of oxygen-free copper, deoxidized copper, or copper alloy as the copper matrix.

[0035] Furthermore, the main function of the pre-bonded mold is to press the superconducting round wire into the thin-walled copper-clad aluminum groove wire and pre-form it, so as to avoid the problems of poor stability and insufficient coating caused by direct forming.

[0036] S3: High current density copper-clad aluminum channel wire WIC superconducting wire is characterized by surface and deep welding defects using a particle detector and eddy current flaw detector to ensure that the number of surface solder nodules and deep solder joint defects does not exceed 1 per 1000m.

[0037] Example 1 This embodiment provides a method for preparing high current-density copper-clad aluminum trench wire (WIC) superconducting wire, which specifically includes the following steps: S1: A copper-clad aluminum rod with a diameter of 1.30 mm and a copper volume ratio of 5% is straightened (straightening degree not less than 1%) and flattened to obtain a 3.58×0.30 mm copper-clad aluminum flat strip. This strip is then rolled in three passes to obtain a shaped copper flat strip with a length of 3.58 mm, a minimum thickness of 0.15 mm, a concave radius of 0.37 mm, an angle of 73.5°, a convex radius of 0.32 mm, and an angle of 90°. This strip is then annealed online (annealing temperature 200℃), cooled, and passivated. Passivation is performed using RSB607 with a concentration of 5% and a solution temperature of 50±5℃, with an immersion distance of 1 m, resulting in a flat, soft-state copper-clad aluminum flat strip with the plane facing upwards. Figure 1 ).

[0038] S2: The irregularly shaped soft copper-clad aluminum flat strip is passed sequentially through a bending machine and a forming concave cam assembly to obtain a thin-walled copper-clad aluminum groove with a side length of 1.34mm, a wall thickness of 0.10mm, a radius of 0.32mm, a bending angle 1 of 120°, and a bending angle 2 of 90°. Figure 2 The thin-walled copper-clad aluminum channel wire is passed through a flux machine (with added flux) and a liquid Sn0.7Cu solder bath. The soldering temperature is set to 260℃. After the soldering temperature reaches the set temperature, a 1.10mm diameter copper-based NbTi superconducting round wire is inserted. Figure 3 The thin-walled copper-clad aluminum channel wire is immersed in liquid solder and pre-bonded with a mold. The bending angle of the pre-bonded mold is 100°. Then, it is inserted with a 1.29×1.29mm inlay mold. The processing amount is 10%. Welding is performed at the inlay mold at a welding speed of 120m / min to obtain a 1000m high current-density copper-clad aluminum channel wire WIC superconducting wire with a rounded square cross-section.

[0039] S3: High current-density copper-clad aluminum channel wire WIC superconducting wire ( Figure 4 The surface solder nodules of the wire were characterized using a particle detector, and deep solder joint defects were characterized using an eddy current flaw detector. The test results showed that the particle signal representing solder nodules was 0, and the number of eddy current signals representing deep solder joint defects was also 0. The copper-clad aluminum channel wire used in the WIC superconducting wire of this invention has a thickness of 0.1 mm, and the copper-clad aluminum matrix accounts for a small proportion of the wire, significantly improving the engineering current density of the wire.

[0040] Example 2 This embodiment provides a method for preparing high current-density copper-clad aluminum trench wire (WIC) superconducting wire, which specifically includes the following steps: S1: A copper-clad aluminum rod with a diameter of 2.40 mm and a copper volume ratio of 10% is straightened (straightening degree not exceeding 1%) and flattened to obtain a copper-clad aluminum flat strip of 6.28 × 0.56 mm. After three rolling passes, a shaped copper flat strip with a length of 6.28 mm, a minimum thickness of 0.3 mm, a concave arc radius of 0.62 mm, an angle of 72.2°, a convex arc radius of 0.59 mm, and an angle of 90° is obtained. The strip is then annealed online (annealing temperature 350℃), cooled, and passivated. The passivation is performed using RSB607 with a concentration of 10% and a solution temperature of 50±5℃, with an immersion distance of 2 m, to obtain a shaped soft copper-clad aluminum flat strip with the plane facing upwards.

[0041] S2: The irregularly shaped soft copper-clad aluminum flat strip is passed sequentially through a bending machine and a forming concave cam assembly to obtain a thin-walled copper-clad aluminum channel wire with a side length of 2.40mm, a wall thickness of 0.20mm, a radius of 0.59mm, a bending angle 1 of 120°, and a bending angle 2 of 90°. The thin-walled copper-clad aluminum channel wire is then passed through a flux machine (with flux added) and a liquid Sn2.5Cu solder bath. The soldering temperature is set to 450℃. After the soldering temperature reaches the set temperature, a copper-based NbTi superconducting round wire with a diameter of 1.95mm and the thin-walled copper-clad aluminum channel wire are pre-bonded by immersing them in liquid solder using a pre-bonding mold with a bending angle 1 of 100°. Subsequently, they are passed through an inlay mold with a size of 2.20×2.20mm and a processing amount of 20%. Welding is performed at the inlay mold at a welding speed of 20m / min to obtain a 1000m high current-density copper-clad aluminum channel wire WIC superconducting wire with a rounded square cross-section.

[0042] S3: The high current-density copper-clad aluminum channel wire WIC superconducting wire is characterized for surface solder nodule defects using a particle detector and for deep solder joint defects using an eddy current flaw detector. The test results show that the particle signal representing solder nodule defects is 0, and the number of eddy current signals representing deep solder joint defects is 1. The copper-clad aluminum channel wire used in the WIC superconducting wire of this invention has a thickness of 0.2 mm, and the copper-clad aluminum matrix accounts for a small proportion of the wire, significantly improving the engineering current density of the wire.

[0043] Example 3 This embodiment provides a method for preparing high current-density copper-clad aluminum trench wire (WIC) superconducting wire, which specifically includes the following steps: S1: A copper-clad aluminum rod with a diameter of 1.80 mm and a copper volume ratio of 8% is straightened (straightening degree not exceeding 1%) and flattened to obtain a copper-clad aluminum flat strip of 5.47 × 0.43 mm. After three rolling passes, a shaped copper flat strip with a length of 5.47 mm, a minimum thickness of 0.2 mm, a concave arc radius of 0.60 mm, an angle of 74.4°, a convex arc radius of 0.45 mm, and an angle of 90° is obtained. The strip is then annealed online (annealing temperature 300℃), cooled, and passivated. The passivation uses RSB607 with a concentration of 10% and a solution temperature of 50±5℃, with an immersion distance of 2 m, to obtain a shaped soft copper-clad aluminum flat strip with the plane facing upwards.

[0044] S2: The irregularly shaped soft copper-clad aluminum flat strip is passed sequentially through a bending machine and a forming concave cam assembly to obtain a thin-walled copper-clad aluminum channel wire with a side length of 2.04mm, a wall thickness of 0.15mm, a radius of 0.45mm, a bending angle 1 of 120°, and a bending angle 2 of 90°. The thin-walled copper-clad aluminum channel wire is then passed through a flux machine (with flux added) and a liquid Sn2.5Cu solder bath. The soldering temperature is set to 300℃. After the soldering temperature reaches the set temperature, a copper-based NbTi superconducting round wire with a diameter of 1.72mm and the thin-walled copper-clad aluminum channel wire are pre-bonded by immersing them in liquid solder using a pre-bonding mold with a bending angle 1 of 100°. Subsequently, they are passed through an inlay mold with dimensions of 1.91×1.91mm and a processing allowance of 15%. Welding is performed at the inlay mold at a welding speed of 80m / min to obtain a 1000m high current-density copper-clad aluminum channel wire WIC superconducting wire with a rounded square cross-section.

[0045] S3: The high current-density copper-clad aluminum channel wire WIC superconducting wire is characterized for surface solder nodules using a particle detector and for deep solder joint defects using an eddy current flaw detector. The test results show that the particle signal representing solder nodules is 0, and the number of eddy current signals representing deep solder joint defects is also 0. The copper-clad aluminum channel wire used in the WIC superconducting wire of this invention has a thickness of 0.15mm, and the copper-clad aluminum matrix accounts for a small proportion of the wire, significantly improving the engineering current density of the wire.

[0046] Example 4 This embodiment provides a method for preparing high current-density copper-clad aluminum trench wire (WIC) superconducting wire, which specifically includes the following steps: S1: A copper-clad aluminum rod with a diameter of 2.20 mm and a copper volume ratio of 10% is straightened (straightening degree not exceeding 1%) and flattened to obtain a copper-clad aluminum flat strip of 6.15 × 0.51 mm. After three rolling passes, a shaped copper flat strip with a length of 6.15 mm, a minimum thickness of 0.25 mm, a concave arc radius of 0.65 mm, an angle of 73.7°, a convex arc radius of 0.54 mm, and an angle of 90° is obtained. The strip is then annealed online (annealing temperature 350℃), cooled, and passivated. The passivation is performed using RSB607 with a concentration of 10% and a solution temperature of 50±5℃, with an immersion distance of 2 m, to obtain a shaped soft copper-clad aluminum flat strip with the plane facing upwards.

[0047] S2: The irregularly shaped soft copper-clad aluminum flat strip is passed sequentially through a bending machine and a forming concave cam assembly to obtain a thin-walled copper-clad aluminum channel wire with a side length of 2.36mm, a wall thickness of 0.2mm, a radius of 0.54mm, a bending angle 1 of 120°, and a bending angle 2 of 90°. The thin-walled copper-clad aluminum channel wire is then passed through a flux machine (with flux added) and a liquid Sn2.5Cu solder bath. The soldering temperature is set to 400℃. After the soldering temperature reaches the set temperature, a copper-based NbTi superconducting round wire with a diameter of 1.87mm and the thin-walled copper-clad aluminum channel wire are pre-bonded by immersing them in liquid solder using a pre-bonding mold with a bending angle 1 of 100°. Subsequently, they are passed through an inlay mold with a size of 2.15×2.15mm and a processing amount of 17%. Welding is performed at the inlay mold at a welding speed of 100m / min to obtain a 1000m high current-density copper-clad aluminum channel wire WIC superconducting wire with a rounded square cross-section.

[0048] S3: The high current-density copper-clad aluminum channel wire WIC superconducting wire is characterized for surface solder nodule defects using a particle detector and for deep solder joint defects using an eddy current flaw detector. The test results show that the particle signal representing solder nodule defects is 0, and the number of eddy current signals representing deep solder joint defects is also 0. The copper-clad aluminum channel wire used in the WIC superconducting wire of this invention has a thickness of 0.2 mm, and the copper-clad aluminum matrix accounts for a small proportion of the wire, significantly improving the engineering current density of the wire.

[0049] Comparative Example 1 The preparation method of this comparative example copper-clad aluminum channel wire WIC superconducting wire is the same as that in Example 1, except that in S2, the thin-walled copper-clad aluminum channel wire is replaced with a 0.45mm U-shaped copper-clad aluminum channel wire prepared from a 0.56mm copper-clad aluminum flat strip. Because the U-shaped copper-clad aluminum channel wire is thicker, the engineering current density of the prepared copper-clad aluminum channel wire WIC superconducting wire is significantly lower than that of the high current-carrying-density copper-clad aluminum channel wire WIC superconducting wire of this invention.

[0050] As described above, the basic principles, main features, and advantages of the present invention have been well described. The above embodiments and specifications are merely descriptions of preferred embodiments of the present invention, and the present invention is not limited to the above embodiments. Various changes and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit and scope of the present invention should fall within the protection scope defined by the present invention.

Claims

1. A method for preparing a high current-density copper-clad aluminum channel wire WIC superconducting wire, characterized in that, include: Copper-clad aluminum rods are prepared into irregularly shaped soft copper-clad aluminum flat strips, which are then bent and formed into thin-walled copper-clad aluminum grooves by a bending machine and a forming concave cam assembly. The superconducting round wire is placed on the thin-walled copper-clad aluminum groove wire, and the high current carrying density copper-clad aluminum groove wire WIC superconducting wire is obtained by pre-bonding mold and embedding mold. The irregularly shaped soft copper-clad aluminum flat strip has a flat surface on top and a continuous wave shape composed of concave and convex arcs on the bottom.

2. The method for preparing high current-density copper-clad aluminum channel wire WIC superconducting wire according to claim 1, characterized in that, The thickness of the thinnest part of the irregularly shaped soft copper-clad aluminum flat strip is 0.15~0.30mm; The length of the plane is 1.01 to 1.05 times the circumference of the composite circle, and the angle of the convex arc is 90°; The formula for calculating the radius of the convex arc is: d1 is 1.01 to 1.05 times the diameter of the superconducting circular wire, and h is the thickness at the thinnest point of the irregular soft copper-clad aluminum flat strip.

3. The method for preparing high current-density copper-clad aluminum channel wire WIC superconducting wire according to claim 1, characterized in that, The thin-walled copper-clad aluminum channel is a rounded pentagon with missing apex corners; The angle of the bottom two corners of the rounded pentagon with missing apex is 120° after bending, and the angle of the two corners on either side of the apex is 90° after bending.

4. The method for preparing high current-density copper-clad aluminum channel wire WIC superconducting wire according to claim 1, characterized in that, The copper volume percentage of the copper-clad aluminum rod is 5% to 10%. The copper-clad aluminum rod is straightened and flattened to obtain a copper-clad aluminum flat strip, which is then rolled in three passes to obtain the irregular soft copper-clad aluminum flat strip.

5. The method for preparing high current-density copper-clad aluminum channel wire WIC superconducting wire according to claim 1, characterized in that, The thin-walled copper-clad aluminum channel line before the pre-bonding mold also passes through a fluxing machine and a solder bath, in which liquid solder is placed, which is liquid Sn0.7Cu solder or liquid Sn2.5Cu solder; The pre-bonded mold is immersed in liquid solder; The temperature of the liquid SnCu solder is 260~450℃.

6. The method for preparing high current-density copper-clad aluminum channel wire WIC superconducting wire according to claim 3, characterized in that, The pre-assembled mold bends the bottom two corners of the rounded pentagon that is missing its top corner to 100°.

7. The method for preparing high current-density copper-clad aluminum channel wire WIC superconducting wire according to claim 1, characterized in that, The total processing volume of the pre-bonded mold and the inlay mold is 10% to 20%.

8. The method for preparing high current-density copper-clad aluminum channel wire WIC superconducting wire according to claim 1, characterized in that, Welding is performed at the inlay mold at a speed of 20~120m / min.

9. The method for preparing high current-density copper-clad aluminum channel wire WIC superconducting wire according to claim 1, characterized in that, The superconducting circular wire is a copper-based superconducting circular wire.

10. A high current-density copper-clad aluminum channel wire WIC superconducting wire, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 9.

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