Preparation method of high-surface-quality high-rrr profiled groove wire for superconducting wire

Abstract

The application belongs to the technical field of superconducting wires, and particularly relates to a preparation method of a high-surface-quality high-RRR profiled groove wire for superconducting wires. The preparation method comprises the following steps: 1) using copper as raw material, preparing a super-long copper wire blank through continuous casting; 2) performing online profiled skinning on the copper wire blank to obtain a profiled groove wire after skinning; 3) performing low-processing-rate shaping die finishing on the profiled groove wire after skinning to obtain a finished profiled groove wire; 4) performing fluid polishing on the finished profiled groove wire to obtain a polished profiled groove wire; and 5) sequentially performing online ultrasonic cleaning, online diameter measurement and eddy current flaw detection on the polished profiled groove wire. The application avoids the problems of RRR reduction, low surface quality and long production cycle existing in the preparation of profiled groove wires through traditional multi-pass cold working, and can stably obtain a high-performance profiled groove wire with a length of greater than or equal to 5000 m, an RRR of greater than or equal to 500 and a surface roughness Ra of less than or equal to 0.3 microns.

Description

Technical Field

[0001] This invention belongs to the field of superconducting wire technology, and particularly relates to a method for preparing high surface quality, high RRR profiled grooved wire for superconducting wire. Background Technology

[0002] Wire-in-channel (WIC) superconducting wires are high-copper-ratio superconducting wires obtained by inlay welding NbTi / Cu multi-core superconducting wires and copper channel wires. The fabrication method involves wrapping NbTi / Cu round wires within the grooves of copper channel wires, achieving a metallurgical bond through inlay welding. Due to their high copper ratio and low copper processing rate, they are widely used in the manufacture of superconducting magnets for magnetic resonance imaging (MRI) systems. The copper channel wire is a key raw material in the fabrication of high-copper-ratio superconducting wires. As a stabilizing matrix, it acts as a shunt when the superconductor experiences localized quenching, helping it recover its superconducting state. The stabilizing effect on the superconductor is generally evaluated by the RRR (Resistance Ratio) value of the WIC wire; a higher RRR value indicates better stability. The RRR value is the ratio of the room-temperature resistivity to the low-temperature resistivity of copper in the WIC wire.

[0003] The existing method for preparing copper channel wire involves multiple rolling and drawing processes on copper rods. The disadvantages are: the deformation caused by multiple cold working processes will reduce the RRR value, and the RRR can only be improved by increasing the RRR of the copper rod and intermediate annealing, resulting in poor stability and long processing cycle; the surface quality is unstable, and it is easy to produce local damage and surface roughness defects, which will affect the quality of inlay welding and the surface quality of the final superconducting wire, resulting in scrap. Summary of the Invention

[0004] The purpose of this invention is to solve the technical problems of low surface quality, difficulty in controlling RRR, numerous production processes, and long preparation cycle in the traditional multi-pass rolling and drawing process for preparing shaped grooved wires. To address this need in the field, this invention provides a method for preparing high surface quality and high RRR shaped grooved wires for superconducting wires.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] On one hand, the present invention provides a method for preparing high surface quality, high RRR (Rapid Reduction Ratio) grooved wire for superconducting wires, comprising the following steps:

[0007] 1) Using copper as raw material, ultra-long copper wire blanks are prepared by continuous casting;

[0008] 2) Perform online stripping on the copper wire blank to eliminate surface defects and obtain stripped shaped grooved wire;

[0009] 3) The peeled irregular groove line is finished by using a shaping mold to obtain the finished irregular groove line;

[0010] 4) Perform fluid polishing on the finished irregular groove line to eliminate surface roughness defects and obtain the polished irregular groove line;

[0011] 5) The polished irregular groove line is subjected to online ultrasonic cleaning, online diameter measurement and eddy current testing in sequence to obtain the final product.

[0012] Preferably, in step 1), the copper is high-purity copper with a purity of not less than 99.99%.

[0013] Preferably, in step 1), the equipment used for continuous casting consists of a melting and heat preservation module, a special-shaped crystallizer module, a multi-level zoned cooling module, and a traction module; the melting temperature is 1000-1250℃, and the drawing speed is 5-50m / min.

[0014] Preferably, in step 2), the online profile stripping uses a cemented carbide profile stripping die, the purpose of which is to remove the surface defect layer and pre-form, and the stripping amount is 50-500μm; the cross section of the cemented carbide profile stripping die is conformal to the cross section of the high surface quality high RRR profiled groove wire used for superconducting wire.

[0015] Preferably, in step 3), the finishing rate of the shaping mold is 3-10%.

[0016] Preferably, in step 4), the fluid polishing is an abrasive suspension polishing method, wherein the suspension is a water-based suspension and the fluid pressure is 5-25 MPa; the abrasive is SiO2 micron-sized abrasive with a particle size of 1-10 μm and a concentration of 5-20 wt.% (mass percentage); the polishing time of the fluid polishing is 1-10 s, and the length of the polishing chamber of the fluid polishing is 1-5 m.

[0017] Preferably, in step 5), the online ultrasonic cleaning, online diameter measurement, and eddy current testing are performed online in real time on the production line.

[0018] Preferably, the continuous casting in step 1), the online irregular shape peeling in step 2), the mold finishing in step 3), the fluid polishing in step 4), the online ultrasonic cleaning, online diameter measurement and eddy current testing in step 5) are all performed online in real time on the production line.

[0019] On the other hand, a high surface quality, high RRR profiled grooved wire for superconducting wire is provided, which is prepared by the preparation method described in this invention. The high surface quality, high RRR profiled grooved wire for superconducting wire has a length ≥5000m, an RRR ≥500, and a surface roughness Ra ≤0.3μm. It has the advantages of high RRR, high filling, high surface quality, and the ability to continuously prepare ultra-long wires.

[0020] Preferably, the structure of the high surface quality high RRR grooved wire for superconducting wire is a U-shaped groove structure, a rectangular groove structure, or a special structure with multiple U-shaped grooves.

[0021] On another aspect, the present invention provides the application of the high surface quality, high RRR profiled grooved wire for superconducting wires in the preparation of Wirein channel type superconducting wires.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] This invention combines continuous casting with online profile stripping, low-processing-rate shaping and finishing, and fluid polishing processes. This avoids the problems of low surface quality, difficult RRR control, and long preparation cycle that exist in traditional multi-pass cold working for preparing profiled grooved wires. It significantly improves RRR and surface quality, and can stably produce high-performance profiled grooved wires with length ≥5000m, RRR ≥500, and surface roughness Ra ≤0.3μm. It has outstanding advantages such as high RRR, high filling, high and uniform surface quality, short process, and the ability to continuously prepare ultra-long wires. Attached Figure Description

[0024] Figure 1 This is a schematic flowchart illustrating a method for preparing high surface quality, high RRR profiled grooved wires for superconducting wires, provided in an embodiment of the present invention.

[0025] Figure 2 This is a cross-sectional schematic diagram of a U-shaped groove structure copper groove wire prepared in a method for preparing high surface quality and high RRR profiled groove wire for superconducting wires according to an embodiment of the present invention.

[0026] Figure 3 This is a cross-sectional schematic diagram of a rectangular groove structure copper groove wire prepared in a method for preparing high surface quality, high RRR profiled groove wire for superconducting wires according to an embodiment of the present invention.

[0027] Figure 4 This is a cross-sectional schematic diagram of a special structure copper groove wire prepared in a method for preparing high surface quality, high RRR profiled groove wire for superconducting wires according to an embodiment of the present invention. Detailed Implementation

[0028] 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.

[0029] In this embodiment of the invention, the residual resistivity ratio (RRR value) under 300K / 10K conditions is detected by measuring the resistance of the sample at 300K and 10K using the four-wire method. The ratio of the room temperature resistance measured at 300K to the low temperature resistance measured at 10K is the residual resistivity ratio. The average surface roughness Ra is detected by measuring it using a contact surface roughness measuring instrument.

[0030] like Figure 1 As shown, this embodiment of the invention provides a method for preparing high surface quality, high RRR (Rapid Reduction Ratio) grooved wire for superconducting wires, comprising the following steps:

[0031] 1) Select high-purity copper with a purity of not less than 99.99% as raw material, and put it into a continuous casting equipment consisting of a melting and heat preservation module, a special-shaped crystallizer module, a multi-stage zoned cooling module and a traction module for continuous casting. The melting temperature is 1000-1250℃. The copper liquid is initially formed in the crystallizer and then solidified by precise temperature control through the multi-stage zoned cooling module. The ultra-long copper wire billet is continuously and stably drawn by the traction module at a drawing speed of 5-50m / min.

[0032] 2) The copper wire blank obtained in step 1) is subjected to a special-shaped stripping process through a special-shaped stripping die to obtain a long special-shaped grooved wire with the surface defect layer removed; the special-shaped stripping die is made of cemented carbide and its cross section is conformal to the cross section of the final special-shaped grooved wire (high surface quality high RRR special-shaped grooved wire for superconducting wires) and the stripping amount is 50-500μm.

[0033] 3) The stripped irregular grooved wire obtained in step 2) is subjected to a shaping die finishing process with a processing rate of 3-10%. The size of the shaping die matches the size of the final product (high surface quality high RRR irregular grooved wire for superconducting wire).

[0034] 4) The finished irregular groove obtained in step 3) is subjected to fluid polishing through a fluid polishing chamber mechanism. The fluid polishing is an abrasive suspension polishing method, using a water-based suspension with a fluid pressure of 5-25 MPa. SiO2 micron-sized abrasive with a particle size of 1-10 μm and an abrasive concentration of 5-20 wt.% is added to the suspension. The polishing time is 1-10 s, and the length of the fluid polishing chamber is 1-5 m, resulting in a surface roughness Ra ≤ 0.3 μm for the irregular groove.

[0035] 5) The polished shaped grooved wire obtained in step 4) is sequentially subjected to online ultrasonic cleaning, drying, laser diameter measuring instrument, and eddy current flaw detection equipment to obtain a finished shaped grooved wire with a clean surface and good quality (high surface quality, high RRR shaped grooved wire for superconducting wires); the ultrasonic cleaning temperature is 50-70℃, and the cleaning agent used is an environmentally friendly copper cleaning agent, which, by weight percentage, contains: sodium carbonate 40-50%, sodium metasilicate pentahydrate 15-20%, sodium citrate 20-25%, sodium gluconate 3-5%, isomeric alcohol oleic acid soap 2-4%, fatty alcohol polyoxyethylene ether 1-2%, alkyl glycoside 1-3%, and benzotriazole 0.05-1%; when using, dilute with deionized water to a concentration of 5-15%.

[0036] Example 1

[0037] High-purity copper with a purity of no less than 99.99% is selected as raw material and fed into a continuous casting equipment consisting of a melting and holding module, a special-shaped crystallizer module, a multi-stage zoned cooling module, and a traction module for continuous casting. The melting temperature is 1100℃. The copper liquid is initially formed in the crystallizer and then solidified with precise temperature control by the multi-stage zoned cooling module. The traction module continuously and stably draws ultra-long copper wire billets with a wire size of 3.40mm × 2.30mm at a drawing speed of 20m / min. The obtained copper wire billet undergoes a special-shaped peeling process using a special-shaped peeling die to obtain a long, special-shaped grooved wire with the surface defect layer removed. The special-shaped peeling die is made of cemented carbide, and its cross-section is conformal to the final special-shaped grooved wire cross-section. The die cross-section size is 3.15mm × 2.00mm (groove depth 0.90mm), and the peeling amount on one side is approximately 120μm. The peeled irregular groove is then finished using a shaping mold. The mold dimensions are 3.00mm × 1.90mm (groove depth 1.00mm), with a processing rate of 9%, resulting in a groove cross-sectional shape as shown. Figure 2 The image shows a copper groove with a U-shaped cross-section. The finished groove was then fluid-polished using a fluid polishing chamber. The fluid polishing method was abrasive suspension polishing, using a water-based suspension at a pressure of 10 MPa. SiO2 micron-sized abrasives (3 μm particle size, 8 wt.%) were added to the suspension. The polishing time was 3 seconds, and the polishing chamber length was 2.5 m, resulting in a surface roughness Ra ≤ 0.2 μm for the groove. After polishing, the groove was sequentially subjected to online ultrasonic cleaning and drying. The ultrasonic cleaning temperature was 60℃, the frequency was 40 kHz, the cleaning agent concentration was 8%, and the drying temperature was 65℃. The cleaned and dried groove was then subjected to online dimensional inspection and defect detection using a laser diameter gauge and eddy current testing equipment. The inspection results showed that the dimensional accuracy met the requirements and there were no obvious defects. The performance of the obtained grooved lines was tested. The measured residual resistivity (RRR value) under 300K / 10K conditions was 558, and the average surface roughness Ra was ≤0.2μm, which met the usage requirements.

[0038] Example 2

[0039] High-purity copper with a purity of no less than 99.99% is selected as raw material and fed into a continuous casting equipment consisting of a melting and holding module, a special-shaped crystallizer module, a multi-stage zoned cooling module, and a traction module for continuous casting. The melting temperature is 1100℃. The copper liquid is initially formed in the crystallizer and then solidified with precise temperature control by the multi-stage zoned cooling module. The traction module continuously and stably draws ultra-long copper wire billets with a wire size of 11.00mm × 6.40mm at a drawing speed of 25m / min. The obtained copper wire billet undergoes a special-shaped peeling process using a special-shaped peeling die to obtain a long, special-shaped grooved wire with the surface defect layer removed. The special-shaped peeling die is made of cemented carbide, and its cross-section is conformal to the final special-shaped grooved wire cross-section. The die cross-section dimensions are 10.20mm × 5.80mm (groove width 6.96mm, groove depth 2.85mm), with a peeling amount of approximately 300-400μm per side. The peeled irregular groove is then finished using a shaping mold. The mold dimensions are 10.00mm × 5.65mm (groove width 7.10mm, groove depth 2.95mm), with a processing rate of 10%. The resulting groove cross-sectional shape is as follows: Figure 3 The image shows a copper groove line with a rectangular cross-section. The finished irregularly shaped groove line undergoes fluid polishing via a fluid polishing chamber. The fluid polishing method is abrasive suspension polishing, using a water-based suspension at a pressure of 15 MPa. SiO2 micron-sized abrasive particles (3 μm particle size) are added to the suspension at a concentration of 10 wt.%, with a polishing time of 3 seconds and a chamber length of 3 meters. This results in a surface roughness Ra ≤ 0.2 μm for the irregularly shaped groove line. After polishing, the irregularly shaped groove line is sequentially subjected to online ultrasonic cleaning and drying. The ultrasonic cleaning temperature is 60℃, the frequency is 40 kHz, the cleaning agent concentration is 8%, and the drying temperature is 65℃. The cleaned and dried groove line is then subjected to online dimensional inspection and defect detection using a laser diameter gauge and eddy current testing equipment. The inspection results show that the dimensional accuracy meets the requirements and there are no obvious defects. The performance of the obtained grooved lines was tested. The measured residual resistivity ratio (RRR value) under the conditions of 300K / 10K was 589, and the average surface roughness Ra was ≤0.2μm, which met the usage requirements.

[0040] Example 3

[0041] High-purity copper with a purity of no less than 99.99% is selected as raw material and fed into a continuous casting equipment consisting of a melting and holding module, a special-shaped crystallizer module, a multi-stage zoned cooling module, and a traction module for continuous casting. The melting temperature is 1100℃. The copper liquid is initially formed in the crystallizer and then precisely solidified by the multi-stage zoned cooling module. The traction module continuously and stably draws ultra-long copper wire billets with a wire size of 8.15mm × 6.60mm at a drawing speed of 15m / min. The obtained copper wire billet undergoes a special-shaped peeling process using a special-shaped peeling die to obtain a long, shaped grooved wire with the surface defect layer removed. The special-shaped peeling die is made of cemented carbide, and its cross-section is conformal to the final shaped grooved wire cross-section. The structure is as follows: Figure 4 The illustrated groove structure features a unique U-shaped groove on each side of its height. The mold cross-section measures 7.80mm × 6.25mm (groove depth 1.40mm), with a single-side peeling amount of approximately 180μm. The peeled groove undergoes a finishing process using a shaping mold measuring 7.50mm × 6.00mm (groove depth 1.5mm), with a processing rate of 10%. The finished groove is then fluid-polished using a water-based abrasive suspension at a pressure of 10MPa. The suspension contains 3μm SiO2 micron-sized abrasive particles at a concentration of 15wt.%, with a polishing time of 10s and a polishing chamber length of 3m, resulting in a surface roughness Ra ≤ 0.2μm for the groove. After polishing, the irregularly shaped grooved lines were sequentially subjected to online ultrasonic cleaning and drying. The ultrasonic cleaning temperature was 60℃, the frequency was 40kHz, the cleaning agent concentration was 10%, and the drying temperature was 65℃. Next, the cleaned and dried grooved lines underwent online dimensional inspection and defect detection using a laser diameter gauge and eddy current testing equipment. The inspection results showed that the dimensional accuracy met the requirements and there were no obvious defects. Performance testing of the resulting grooved lines showed that the measured residual resistivity (RRR value) under 300K / 10K conditions was 541, and the average surface roughness Ra ≤ 0.2μm, meeting the usage requirements.

[0042] The embodiments described above are some, but not all, of the embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but rather to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art through related deductions and substitutions based on the inventive concept, without inventive effort, are within the scope of protection of the present invention.

Claims

1. A method for preparing high surface quality, high RRR (Rapid Reduction Ratio) shaped grooved wire for superconducting wires, characterized in that, Includes the following steps: 1) Using copper as raw material, ultra-long copper wire blanks are prepared by continuous casting; 2) Perform online stripping on the copper wire blank to obtain stripped shaped grooved wire; 3) The peeled irregular groove line is finished by using a shaping mold to obtain the finished irregular groove line; 4) Perform fluid polishing on the finished irregular groove line to obtain the polished irregular groove line; 5) The polished irregular groove line is subjected to online ultrasonic cleaning, online diameter measurement and eddy current testing in sequence to obtain the final product.

2. The preparation method according to claim 1, characterized in that, In step 1), the copper is high-purity copper with a purity of not less than 99.99%.

3. The preparation method according to claim 1, characterized in that, In step 1), the equipment used for continuous casting consists of a melting and holding module, a special-shaped crystallizer module, a multi-stage zoned cooling module, and a traction module; the melting temperature is 1000-1250℃, and the drawing speed is 5-50m / min.

4. The preparation method according to claim 1, characterized in that, In step 2), the online profile stripping uses a cemented carbide profile stripping die, and the stripping amount is 50-500μm; the cross section of the cemented carbide profile stripping die is conformal to the cross section of the high surface quality high RRR profiled grooved wire used for superconducting wire.

5. The preparation method according to claim 1, characterized in that, In step 3), the finishing rate of the shaping mold is 3-10%.

6. The preparation method according to claim 1, characterized in that, In step 4), the fluid polishing is an abrasive suspension polishing method, the suspension is a water-based suspension, and the fluid pressure is 5-25 MPa; the abrasive is SiO2 micron-sized abrasive with a particle size of 1-10 μm and a concentration of 5-20 wt.%; the polishing time of the fluid polishing is 1-10 s, and the length of the polishing chamber of the fluid polishing is 1-5 m.

7. The preparation method according to claim 1, characterized in that, In step 5), the online ultrasonic cleaning, online diameter measurement, and eddy current testing are performed online in real time on the production line.

8. A high surface quality, high RRR profiled grooved wire for superconducting wires, characterized in that, The superconducting wire is prepared by the preparation method according to any one of claims 1-7, and the length of the high surface quality high RRR profiled grooved wire is ≥5000m, the RRR is ≥500, and the surface roughness Ra is ≤0.3μm.

9. The high surface quality, high RRR profiled grooved wire for superconducting wires according to claim 8, characterized in that, The structure of the high surface quality, high RRR grooved wire for superconducting wire is a U-shaped groove structure, a rectangular groove structure, or a special structure with multiple U-shaped grooves.

10. The application of the high surface quality, high RRR profiled grooved wire for superconducting wires as described in claim 8 or 9 in the preparation of wire inchannel type superconducting wires.

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