Performance-damage-free metal layer stripping method for REBCO strip superconducting joint

Abstract

The invention relates to a performance-damage-free metal layer stripping method for an REBCO strip superconducting joint, which comprises the following steps of: performing protection treatment on an REBCO strip so as to expose a to-be-stripped area; the REBCO strip is immersed in a silver nitrate solution, cleaned and dried; carrying out electrolysis by taking the REBCO strip as an anode and an inert conductive material as a cathode; and after the REBCO strip is cleaned and dried, the REBCO strip with the stripped metal layer is obtained. According to the method, a copper layer of a metal layer of the REBCO strip is replaced with silver particles through a replacement reaction, and the silver particles can be directly separated from the REBCO strip and are only partially attached to the silver layer; according to the method, the copper layer and the silver layer on the REBCO strip are stripped, then the silver layer on the REBCO strip is stripped through electrolysis, finally, the REBCO strip with the completely stripped metal layer is obtained, the superconducting performance (including critical current and n value) of the REBCO strip is protected while stripping of the copper layer and the silver layer is achieved, and a foundation is provided for subsequent superconducting connector preparation efficiently at low cost.

Description

Technical Field

[0001] The invention relates to the technical field of high-temperature superconducting tapes, and in particular to a metal layer stripping method for a REBCO tape superconducting joint without damaging performance. Background Art

[0002] Superconducting materials have obvious advantages in the application of high-voltage power due to their unique physical properties, including zero resistance effect, complete anti-magnetism, isotope effect, etc. 7-x The second-generation high-temperature superconducting tape REBCO tape, which uses rare earth elements (RE for rare earth elements, barium copper oxide, referred to as REBCO) as the core material, has a wider application prospect in many fields such as energy, transportation, and medical treatment because of its excellent current carrying capacity, magnetic field performance, mechanical properties, and use conditions in the liquid nitrogen temperature zone. It is worth noting that the REBCO superconducting phase is an oxide ceramic, so it is brittle and has a high hardness, so a multi-layer structure is required to ensure its stability in application. Usually, a multi-layer thin film structure is formed by a coating process on a nickel-based alloy substrate. The multi-layer thin film structure consists of a metal base tape, a buffer layer, a superconducting layer, and a metal layer (copper layer and silver layer). The metal base tape provides a template and enhances mechanical properties, the buffer layer plays the role of transmitting texture and chemical barrier, the superconducting layer bears the main current carrying capacity, and the metal layer is used for protection, diversion, etc.

[0003] With the continuous development of high-temperature superconducting materials, REBCO tapes have become excellent candidate materials for nuclear magnetic resonance magnets, fusion magnets, and accelerator magnets. However, due to the limitations of the REBCO tape production process, only single tapes with a length of less than 1 km can be produced, which cannot meet the requirements of large-scale applications. In order to extend the length of the REBCO tape and reduce the joint resistance in the superconducting magnet, the superconducting joint process of REBCO tapes is being vigorously developed at home and abroad. The patent with publication number CN111226322A discloses a superconducting joint using stripped ReBCO, providing two or more ReBCO tapes each having an exposed ReBCO region. A bridge is provided, the bridge comprising an exposed ReBCO layer and an oxygen-permeable liner on the exposed ReBCO layer. Each exposed ReBCO region is combined with the exposed ReBCO layer of the bridge by heating to a first temperature (T1) in an environment where the partial pressure of oxygen is low enough so that the minimum bonding temperature (TJ) of ReBCO is less than the melting point (TAg) of silver. Among them, metal layer stripping is an indispensable and critical step. Only by removing the copper and silver metal layers in the designated area without damaging the superconducting properties can high-performance REBCO tape superconducting joints be prepared.

[0004] Existing research usually uses pure chemical or pure physical methods to strip the metal layer of REBCO tape. The pure physical method mainly uses the difference in thermal properties between the multi-layer structure of the tape to delaminate the metal layer on the surface through long-term thermal shock, but this method is very likely to cause the superconducting performance of the tape to deteriorate or even completely damage it. The pure chemical method mainly uses acidic solutions or commercial etching solutions imported by foreign companies to strip the metal layer on the surface of the REBCO tape, but because REBCO superconductors are chemically sensitive to most inorganic solutions, especially acidic solutions, they are prone to cause the degradation of superconducting properties. Although professional etching solutions have little effect on superconducting properties, their costs are often high and the stripping time is long. Overall, the existing REBCO tape metal layer stripping processes are difficult to obtain REBCO tapes with completely exposed superconducting layers in designated areas at low cost and high efficiency. Summary of the invention

[0005] Based on this, the purpose of the present invention is to provide a method for stripping the metal layer of a REBCO tape superconducting joint without damaging the performance, which can completely strip the metal layer in the REBCO tape while ensuring that the superconducting performance of the REBCO tape is not degraded, thereby providing a basis for preparing high-performance REBCO tape superconducting joints.

[0006] To achieve the above object, the present invention adopts the following technical solutions: The present invention first provides a method for stripping a metal layer of a REBCO tape superconducting joint without damaging the performance, which comprises the following steps: S1. Protect the REBCO strip to expose the area to be peeled off; S2. The REBCO strip is immersed in a silver nitrate solution to remove the copper layer, washed, and dried; S3. electrolyzing the REBCO strip as an anode and an inert conductive material as a cathode to remove the silver layer; S4. After the REBCO tape is cleaned and dried, a REBCO tape with the metal layer peeled off is obtained.

[0007] The present invention first replaces the copper layer of the metal layer of the REBCO strip with silver particles through a replacement reaction, and the silver particles can be directly separated from the REBCO strip and only partially attached to the silver layer; then the silver layer on the REBCO strip is stripped by electrolysis, and finally a REBCO strip with a completely stripped metal layer is obtained. While realizing the stripping of the copper and silver metal layers, the method protects the superconducting properties (including critical current and n value) of the REBCO strip, and provides a basis for the subsequent preparation of superconducting joints efficiently and at low cost. The present invention adopts a process combining chemical methods and electrochemical methods, and has higher stability and repeatability.

[0008] As a further improvement of the above solution of the present invention, in step S1, the protective treatment method is: wrapping a sealing material around the non-peeling area of ​​the REBCO tape.

[0009] As a further improvement of the above solution of the present invention, the sealing material is at least one of polyvinyl chloride, polyethylene, and polyimide.

[0010] As a further improvement of the above solution of the present invention, in step S2, the concentration of the silver nitrate solution is 0.04-0.1 mol / L; and / or, the immersion time of the REBCO tape in the silver nitrate solution is 65-240 min; and / or, the temperature of the silver nitrate solution is controlled at 0-20° C. by an ice bath or a low-temperature water bath. Preferably, the concentration of the silver nitrate solution is 0.1 mol / L to obtain a REBCO tape sample with the best superconducting performance.

[0011] As a further improvement of the above solution of the present invention, in step S2, the cleaning is to place the REBCO tape in anhydrous ethanol for ultrasonic cleaning for 1-5 minutes; the use of anhydrous ethanol can prevent the superconducting layer from hydrolyzing; And / or, in step S2, the drying is natural drying at room temperature for 10-20 minutes.

[0012] As a further improvement of the above solution of the present invention, in step S3, the voltage of the electrolysis is 1-1.8V; and / or, the current of the electrolysis is 0.01-0.1A; and / or, the time of the electrolysis is 2-10min. Preferably, the voltage of the electrolysis is 1.4V to obtain a REBCO tape sample with the best superconducting performance.

[0013] As a further improvement of the above solution of the present invention, in step S3, the inert conductive material is graphite, silver or gold.

[0014] As a further improvement of the above solution of the present invention, in step S3, the distance between the REBCO strip and the inert conductive material is 1-10 cm, preferably 5 cm.

[0015] As a further improvement of the above solution of the present invention, in step S3, the electrolytic solution is a silver nitrate solution with a concentration of 0.02-0.06 mol / L; and / or, the temperature of the electrolytic solution is controlled at 0-20° C. by an ice bath or a low-temperature water bath. Preferably, the concentration of the silver nitrate solution is 0.04 mol / L to obtain a REBCO tape sample with the best superconducting performance.

[0016] As a further improvement of the above solution of the present invention, in step S4, the cleaning is to place the REBCO tape in anhydrous ethanol for ultrasonic cleaning for 1-5 minutes; And / or, in step S4, the drying is natural drying at room temperature for 10-20 minutes.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention first replaces the copper layer of the metal layer of the REBCO strip with silver particles through a replacement reaction. The silver particles can be directly separated from the REBCO strip and only partially attached to the silver layer; then the silver layer on the REBCO strip is stripped by electrolysis, and finally a REBCO strip with a completely stripped metal layer is obtained. This method protects the superconducting properties (including critical current and n value) of the REBCO strip while achieving the stripping of the copper and silver metal layers, and provides a basis for the subsequent preparation of superconducting joints with high efficiency and low cost. The present invention adopts a process combining chemical methods and electrochemical methods, which has higher stability and repeatability.

[0018] 2. When the present invention uses a silver nitrate solution to strip the copper layer, a silver nitrate solution with a concentration of 0.04-0.1 mol / L is used, which can avoid the long immersion time in a low-concentration solution, which causes the solution to corrode the superconducting layer and damage the superconducting performance; it can also avoid the solution corroding the superconducting layer too quickly in a high-concentration solution and damaging the superconducting performance. The use of a high-concentration solution also increases the cost and is unsafe; the temperature of the silver nitrate solution is controlled at 0-20° C. by an ice bath or a low-temperature water bath. The low-temperature environment can slow down the corrosion of the superconducting layer by the silver nitrate solution, and can protect the superconducting performance of the REBCO tape from being affected.

[0019] 3. The present invention uses a silver nitrate solution with a concentration of 0.02-0.06 mol / L as the electrolyte, which can avoid the long electrolysis time in a low-concentration solution, and the superconducting layer is immersed in the solution for too long, which affects the stability of the superconducting performance; it can also avoid the solution corroding the superconducting layer too quickly in a high-concentration solution and damaging the superconducting performance; the electrolyte temperature is controlled at 0-20° C. by an ice bath or a low-temperature water bath, and the low-temperature environment can slow down the corrosion of the electrolyte on the superconducting layer, and can protect the superconducting performance of the REBCO tape from being affected.

[0020] 4. The electrolysis voltage of the present invention is controlled at 1-1.8V to avoid damage to the superconducting layer. This is because when the voltage parameter is high, the superconducting layer cannot remain stable in the electrolyte, but gradually dissolves in the solution under the action of the current; when the voltage is lower than 1V, the electrolysis time will be greater than 10 minutes, and the superconducting layer will be immersed in the solution for too long, which significantly affects the stability of the superconducting performance.

[0021] 5. The present invention uses only one solution (silver nitrate solution) to complete the stripping of the two metal layers, which is cheaper and safer than using multiple solutions or directly purchasing commercial etching solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A flow chart of a method for stripping a metal layer without damaging the performance of a REBCO tape superconducting joint proposed by the present invention; Figure 2 Figure 1 shows the superconducting performance test results of REBCO tape purchased for commercialization; Figure 3 This is a graph showing the superconducting performance test results of the REBCO tape obtained in Example 7 after the copper metal layer is completely stripped off; Figure 4 This is a graph showing the superconducting performance test results of the REBCO tape obtained in Example 7 with the metal layer in a partial area completely peeled off; Figure 5 This is a graph showing the superconducting performance test results of the REBCO tape obtained in Comparative Example 1, in which the metal layer in some areas is completely peeled off; Figure 6 This is a graph showing the superconducting performance test results of the REBCO tape obtained in Comparative Example 2, in which the metal layer in some areas is completely peeled off; Figure 7 This is a graph showing the superconducting performance test results of the REBCO tape obtained in Example 8 with the metal layer in a partial area completely peeled off; Figure 8 This is a graph showing the superconducting performance test results of the REBCO tape obtained in Example 9 with the metal layer in a partial area completely peeled off; Fig. 9 This is a graph showing the superconducting performance test results of the REBCO tape obtained in Comparative Example 3, in which the metal layer in some areas is completely peeled off; Fig.10 This is a graph showing the superconducting performance test results of the REBCO tape obtained in Example 10 with the metal layer in a partial area completely peeled off; Fig.11 This is a graph showing the superconducting performance test results of the REBCO tape obtained in Example 11 with the metal layer in a partial area completely peeled off; Fig.12 This is a graph showing the superconducting performance test results of the REBCO tape obtained in Comparative Example 5 in which the metal layer in some areas is completely peeled off. DETAILED DESCRIPTION

[0023] For ease of understanding of the present invention, the present invention will be described more fully below in conjunction with specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0025] Reference Figure 1 This embodiment provides a method for stripping a metal layer of a REBCO tape superconducting joint without damaging the performance, which includes the following steps: S1. Cut the commercially purchased REBCO tape to a predetermined size, and wrap a sealing material around the REBCO tape for protection to expose the area where the metal layer needs to be peeled off. In this embodiment, the sealing material is a polyimide tape. Of course, in other embodiments, the sealing material can also be polyvinyl chloride (PVC), polyethylene (PE) and other materials.

[0026] S2. Immerse the protected REBCO strip in a silver nitrate solution with a concentration of 0.04-0.1 mol / L. The temperature of the silver nitrate solution is controlled at 0-20°C by an ice bath or a low-temperature water bath. The copper metal layer on the surface of the REBCO strip is replaced with silver particles by a replacement reaction between silver nitrate and copper. After immersion for 65-240 minutes, take out the REBCO strip and put it into anhydrous ethanol for ultrasonic cleaning. After ultrasonic cleaning for 1-5 minutes, take out the REBCO strip and dry it naturally at room temperature for 10-20 minutes to obtain a REBCO strip with the copper metal layer completely peeled off. In this embodiment, the concentration of the silver nitrate solution is preferably 0.1 mol / L.

[0027] S3. Place the first bracket and the second bracket on both sides of the outside of the container, put the REBCO strip and the inert conductive material after the copper metal layer is completely stripped into the container and clamp them on the first bracket and the second bracket respectively, and keep the REBCO strip and the inert conductive material after the copper metal layer is completely stripped at a distance of 1-10 cm, inject a silver nitrate solution with a concentration of 0.02-0.06 mol / L into the container as an electrolyte, and control the electrolyte temperature at 0-20°C by ice bath or low-temperature water bath; then connect the REBCO strip and the inert conductive material after the copper metal layer is completely stripped to the positive and negative electrodes of the DC power supply respectively, and start the DC power supply for electrolysis. In this embodiment, the voltage of the DC power supply is 1-1.8V, the current is 0.01-0.1A, and the silver layer on the surface of the REBCO strip at the anode loses electrons to form silver ions that dissolve in the solution. At the same time, the silver ions in the solution obtain electrons to form silver on the inert conductive material at the cathode. After electrolysis for 2-10 minutes, a REBCO strip with the silver metal layer completely stripped off is obtained.

[0028] In this embodiment, the material of the first bracket and the second bracket is polyvinyl chloride (PVC), and the inert conductive material is silver. Of course, in other embodiments, the material of the first bracket and the second bracket can also be graphite or glass fiber, and the inert conductive material can also be graphite or gold. In this embodiment, the concentration of the silver nitrate solution is preferably 0.04 mol / L.

[0029] S4. The REBCO tape with the silver metal layer completely peeled off is placed in anhydrous ethanol for ultrasonic cleaning. After ultrasonic cleaning, the REBCO tape with the silver metal layer completely peeled off is placed in a dryer to remove the sealing material on the surface of the REBCO tape, thereby obtaining a REBCO tape with the metal layer completely peeled off in some areas.

[0030] Next, the effect of the concentration of silver nitrate solution on the superconducting properties of REBCO tape after the copper layer was stripped off was investigated.

[0031] Example 1 S1. Cut the commercially purchased REBCO tape (purchased from Shanghai Superconducting Technology Co., Ltd., batch ST2309-512, which is prepared by physical vapor deposition (PVD)) to 100 mm, and wrap a polyimide tape around the REBCO tape for protection, so as to expose a 10 mm area in the middle where the metal layer needs to be peeled off.

[0032] S2. Under low light conditions, the protected REBCO tape was immersed in a silver nitrate solution with a concentration of 0.02 mol / L. The temperature of the silver nitrate solution was controlled at 10°C by a low-temperature water bath. After 600 minutes, the REBCO tape was taken out and placed in anhydrous ethanol for ultrasonic cleaning. After ultrasonic cleaning for 2 minutes, the REBCO tape was taken out and dried at room temperature for 10 minutes to obtain a REBCO tape with the copper metal layer completely peeled off.

[0033] The superconducting performance of the commercially purchased REBCO tape (batch ST2309-512) was tested using a superconducting performance testing system, and the critical current of the commercially purchased REBCO tape was measured to be 154.5 A, and the n value was 27.2.

[0034] The superconducting performance of the REBCO tape obtained in this embodiment after the copper metal layer is completely stripped off is tested using a superconducting performance testing system, and the critical current of the REBCO tape after the copper metal layer in a partial area of ​​this embodiment is completely stripped off is measured to be 150.5A, and the n value is 28. It can be seen that the superconducting performance of the REBCO tape after the copper metal layer in a partial area of ​​this embodiment is completely stripped off is slightly degraded. This may be due to the long immersion time under low concentration conditions, which causes the solution to corrode the superconducting layer.

[0035] Example 2 This embodiment adopts the same implementation method as that of Embodiment 1, and the difference from Embodiment 1 is that in this embodiment, in step S2, the concentration of the silver nitrate solution is 0.04 mol / L, and the soaking time is 240 min.

[0036] The superconducting performance of the REBCO tape obtained in this embodiment after the copper metal layer is completely stripped off is tested using a superconducting performance testing system, and it is measured that the critical current of the REBCO tape after the copper metal layer in a partial area of ​​this embodiment is completely stripped off is 152.9A, and the n value is 27. It can be seen that the superconducting performance of the REBCO tape after the copper metal layer in a partial area of ​​this embodiment is completely stripped off is not significantly degraded.

[0037] Example 3 This embodiment adopts the same implementation method as that of Embodiment 3, and the difference from Embodiment 3 is that in this embodiment, in step S2, the concentration of the silver nitrate solution is 0.1 mol / L, and the soaking time is 120 min.

[0038] The superconducting performance of the REBCO tape after the copper metal layer of the embodiment is completely stripped off is tested by using a superconducting performance testing system, and the critical current of the REBCO tape after the copper metal layer of a part of the embodiment is completely stripped off is measured to be 155.1A, and the n value is 27.6. It can be seen that the superconducting performance of the REBCO tape after the copper metal layer of a part of the embodiment is completely stripped off is not obviously degraded, and is basically consistent with the original tape.

[0039] From the results of the above Examples 1-3, it can be seen that when the concentration of the silver nitrate solution for soaking the strip is 0.1 mol / L, the superconducting properties of the REBCO strip after the copper metal layer in some regions is completely stripped off are basically the same as those of the REBCO strip without the copper layer stripped off; when the concentration of the silver nitrate solution is 0.02 mol / L, the superconducting properties of the REBCO strip after the copper metal layer in some regions is completely stripped off are slightly degraded, which may be due to the long soaking time at low concentration; and considering that further increasing the concentration does not improve the performance and increases the cost, and high concentration solutions are unsafe, the concentration of the silver nitrate solution for soaking the strip to strip the copper layer is controlled at 0.04-0.1 mol / L. In order to obtain the sample with the best superconducting performance, the concentration of the silver nitrate solution is preferably 0.1 mol / L.

[0040] Next, the effect of the temperature of the silver nitrate solution on the superconducting properties of the REBCO tape after the copper layer was stripped off was investigated.

[0041] Example 4 S1. Cut the commercially purchased REBCO tape (purchased from Shanghai Superconducting Technology Co., Ltd., batch ST2306-78, which is prepared by physical vapor deposition (PVD)) to 100 mm, and wrap a polyimide tape around the REBCO tape for protection, so as to expose a 10 mm area in the middle where the metal layer needs to be peeled off.

[0042] S2. Under low light conditions, the protected REBCO tape was immersed in a 0.1 mol / L silver nitrate solution. The temperature of the silver nitrate solution was controlled at 0°C by an ice bath. After 180 minutes, the REBCO tape was taken out and placed in anhydrous ethanol for ultrasonic cleaning. After ultrasonic cleaning for 2 minutes, the REBCO tape was taken out and dried at room temperature for 10 minutes to obtain a REBCO tape with the copper metal layer completely peeled off.

[0043] The commercially purchased REBCO tape (batch ST2306-78) was tested for superconducting performance using a superconducting performance test system. The test results are as follows: Figure 2 As shown, from Figure 2 It can be seen that the critical current of the commercially available REBCO strip is 191.0 A and the n value is 28.8.

[0044] The superconducting performance of the REBCO tape obtained in this embodiment after the copper metal layer is completely stripped off is tested using a superconducting performance testing system, and the critical current of the REBCO tape after the copper metal layer in a partial area of ​​this embodiment is completely stripped off is measured to be 189.8A, and the n value is 31.7. It can be seen that the superconducting performance of the REBCO tape after the copper metal layer in a partial area of ​​this embodiment is completely stripped off is not significantly degraded.

[0045] Example 5 This embodiment adopts the same implementation method as that of Embodiment 4, and the difference from Embodiment 4 is that in this embodiment, in step S2, the temperature of the silver nitrate solution is controlled at 20° C. by a low-temperature water bath, and the immersion time is 105 min.

[0046] The superconducting performance of the REBCO tape obtained in this embodiment after the copper metal layer is completely stripped off is tested using a superconducting performance testing system, and the critical current of the REBCO tape after the copper metal layer in a partial area of ​​this embodiment is completely stripped off is measured to be 188.1A, and the n value is 31.2. It can be seen that the superconducting performance of the REBCO tape after the copper metal layer in a partial area of ​​this embodiment is completely stripped off is not significantly degraded.

[0047] Example 6 This embodiment adopts the same implementation method as that of Embodiment 5, and the difference from Embodiment 5 is that in this embodiment, in step S2, the temperature of the silver nitrate solution is controlled at 30° C. by a low-temperature water bath, and the immersion time is 65 minutes.

[0048] The superconducting performance of the REBCO tape obtained in this embodiment after the copper metal layer is completely stripped off is tested using a superconducting performance testing system, and it is measured that the critical current of the REBCO tape after the copper metal layer in a partial area of ​​this embodiment is completely stripped off is 186.0A, and the n value is 30.7. It can be seen that the superconducting performance of the REBCO tape after the copper metal layer in a partial area of ​​this embodiment is completely stripped off is slightly degraded.

[0049] From the results of the above Examples 4-6, it can be seen that when the temperature of the silver nitrate solution is controlled at 0°C by an ice bath, although the immersion time is increased to 180 minutes, the superconducting performance of the sample remains stable, which indicates that the low temperature environment may slow down the corrosion of the solution on the superconducting layer; when the temperature of the silver nitrate solution is controlled at 30°C by heating in a water bath, although the immersion time is shortened to 65 minutes, the superconducting performance of the sample is slightly degraded, which indicates that the high temperature environment may aggravate the corrosion of the solution on the superconducting layer; and the superconducting performance at temperatures below 20°C is not degraded. In order to ensure the stability of the superconducting performance, when the ambient temperature is higher than 20°C, an ice bath or a low-temperature water bath should be used to lower the temperature of the silver nitrate solution to reduce the corrosion of the silver nitrate solution on the superconducting layer.

[0050] Next, the effect of electrolyte concentration on the superconducting properties of REBCO tape during metal layer peeling was investigated.

[0051] Example 7 This embodiment provides a method for stripping a metal layer of a REBCO tape superconducting joint without damaging the performance, which includes the following steps: S1. Cut the commercially purchased REBCO tape (purchased from Shanghai Superconducting Technology Co., Ltd., batch ST2306-78, which is prepared by physical vapor deposition (PVD)) to 100 mm, and wrap a polyimide tape around the REBCO tape for protection, so as to expose a 10 mm area in the middle where the metal layer needs to be peeled off.

[0052] S2. Under low light conditions, the protected REBCO tape was immersed in a 0.1 mol / L silver nitrate solution. The temperature of the silver nitrate solution was controlled at 10°C by a low-temperature water bath. After 120 minutes, the REBCO tape was taken out and placed in anhydrous ethanol for ultrasonic cleaning. After ultrasonic cleaning for 2 minutes, the REBCO tape was taken out and dried at room temperature for 10 minutes to obtain a REBCO tape with the copper metal layer completely peeled off.

[0053] S3. Place a first bracket and a second bracket made of polyvinyl chloride on both sides of the outside of the container, put the REBCO strip and the silver electrode after the copper metal layer is completely stripped into the container and clamped and fixed on the first bracket and the second bracket respectively, and make the REBCO strip and the silver electrode after the copper metal layer is completely stripped 5 cm apart, inject a silver nitrate solution with a concentration of 0.04 mol / L into the container, and control the temperature of the silver nitrate solution at 10°C through a low-temperature water bath; then connect the REBCO strip and the inert conductive material after the copper metal layer is completely stripped to the positive and negative electrodes of the DC power supply, respectively, and start the DC power supply for electrolysis. In this embodiment, the voltage of the DC power supply is 1.4V, the current is 0.01-0.03A, and the power-on time is 5min, and the REBCO strip after the silver metal layer is completely stripped is obtained.

[0054] S4. The REBCO tape after the silver metal layer is completely peeled off is placed in anhydrous ethanol for ultrasonic cleaning. After ultrasonic cleaning for 2 minutes, the REBCO tape after the silver metal layer is completely peeled off is taken out and dried at room temperature for 10 minutes, and the polyimide tape on the surface of the REBCO tape is removed to obtain a REBCO tape with the metal layer completely peeled off in some areas.

[0055] The commercially purchased REBCO tape (batch ST2306-78) was tested for superconducting performance using a superconducting performance test system. The test results are as follows: Figure 2 As shown, from Figure 2 It can be seen that the critical current of the commercially available REBCO strip is 191.0 A and the n value is 28.8.

[0056] After the polyimide tape is removed from the REBCO tape after the copper metal layer is completely peeled off in step S2 of this embodiment, the superconducting performance is tested using a superconducting performance testing system. The test results are as follows: Figure 3 As shown, from Figure 3 It can be seen that the critical current of the REBCO tape after the copper metal layer is completely stripped off is 190.8A, and the n value is 29.1. It can be seen that the REBCO tape after the copper metal layer is completely stripped off in this embodiment does not show obvious superconducting performance degradation, which is basically consistent with the original tape.

[0057] The REBCO tape obtained in step S4 of this embodiment with the metal layer completely peeled off in some areas is tested for superconducting performance using a superconducting performance testing system. The test results are as follows: Figure 4 As shown, from Figure 4 It can be seen that the critical current of the REBCO tape with the metal layer completely stripped off in some areas is 190.9 A, and the n value is 30.7. It can be seen that the REBCO tape with the metal layer completely stripped off in some areas of this embodiment does not show obvious superconducting performance degradation.

[0058] Comparative Example 1 This comparative example adopts the same implementation method as Example 7, and the difference from Example 7 is that in step S4 of this comparative example, the concentration of the silver nitrate solution used is 0.02 mol / L, and the electrolysis power-on time is 10 min.

[0059] The REBCO tape obtained in step S4 of this comparative example with the metal layer completely peeled off in some areas was tested for superconducting performance using a superconducting performance testing system. The test results are as follows: Figure 5 As shown, from Figure 5 It can be seen that the critical current of the REBCO tape with the metal layer completely stripped off in some areas is 186.2A, and the n value is 30.1. It can be seen that the superconducting performance of the REBCO tape with the metal layer completely stripped off in some areas of this comparative example is slightly degraded.

[0060] Comparative Example 2 This comparative example adopts the same implementation method as Example 7, and the difference from Example 7 is that in step S4 of this comparative example, the concentration of the silver nitrate solution used is 0.06 mol / L, and the electrolysis power-on time is shortened to 3 min.

[0061] The REBCO tape obtained in step S4 of this comparative example with the metal layer completely peeled off in some areas was tested for superconducting performance using a superconducting performance testing system. The test results are as follows: Figure 6 As shown, from Figure 6 It can be seen that the critical current of the REBCO tape with the metal layer completely stripped off in some areas is 187.8A, and the n value is 29.9. It can be seen that the superconducting performance of the REBCO tape with the metal layer completely stripped off in some areas of this comparative example also slightly degrades.

[0062] From the results of Example 7 and Comparative Examples 1-2, it can be seen that when the concentration of the silver nitrate solution used as the electrolyte is 0.04 mol / L, the superconducting properties of the REBCO tape with the metal layer completely stripped off in some areas are basically the same as those of the REBCO tape with the metal layer not stripped off, while when the concentration of the silver nitrate solution is 0.02 mol / L and 0.06 mol / L, the superconducting properties of the REBCO tape with the metal layer completely stripped off in some areas are slightly degraded. This may be due to the long electrolysis time at low concentrations and the faster speed of solution erosion of the superconducting layer at high concentrations. In order to obtain samples with the best superconducting properties, the electrolyte concentration should preferably be 0.04 mol / L.

[0063] Next, taking the electrolyte concentration of 0.04 mol / L as an example, the effect of electrolysis voltage on the superconducting properties of REBCO tape during metal layer peeling was explored.

[0064] Example 8 This embodiment adopts the same implementation method as that of Embodiment 7, and the difference from Embodiment 7 is that in this embodiment, the voltage of the DC power supply used in step S4 is 1V, and the electrolysis power-on time is 8 minutes.

[0065] The REBCO tape obtained in step S4 of this embodiment with the metal layer completely peeled off in some areas is tested for superconducting performance using a superconducting performance testing system. The test results are as follows: Figure 7 As shown, from Figure 7 It can be seen that the critical current of the REBCO tape with the metal layer completely stripped off in some areas is 189.5A, and the n value is 30.0. It can be seen that the superconducting performance of the REBCO tape with the metal layer completely stripped off in some areas of this embodiment has not shown obvious decline, which indicates that when the electrolysis voltage is 1V, the superconducting performance of the REBCO tape is well protected.

[0066] Example 9 This embodiment adopts the same implementation method as that of Embodiment 7, and the difference from Embodiment 7 is that in this embodiment, the voltage of the DC power supply used in step S4 is 1.8V, and the electrolysis power-on time is 4 minutes.

[0067] The REBCO tape obtained in step S4 of this embodiment with the metal layer completely peeled off in some areas is tested for superconducting performance using a superconducting performance testing system. The test results are as follows: Figure 8 As shown, from Figure 8 It can be seen that the critical current of the REBCO tape with the metal layer completely stripped off in some areas is 189.9 A, and the n value is 29.0. It can be seen that the superconducting performance of the REBCO tape with the metal layer completely stripped off in some areas of this embodiment has not shown obvious decline, which indicates that when the electrolysis voltage is 1.8 V, the superconducting performance of the REBCO tape is well protected.

[0068] Comparative Example 3 This comparative example adopts the same implementation method as Example 7, and the difference from Example 7 is that in this comparative example, the voltage of the DC power supply used in step S4 is 2.6V, and the electrolysis power-on time is 3min.

[0069] The REBCO tape obtained in step S4 of this comparative example with the metal layer completely peeled off in some areas was tested for superconducting performance using a superconducting performance testing system. The test results are as follows: Fig. 9 As shown, from Fig. 9 It can be seen that the critical current of the REBCO tape with the metal layer completely stripped off in some areas is 180.2A, and the n value is 26.1. It can be seen that the superconducting performance of the REBCO tape with the metal layer completely stripped off in some areas of this comparative example is significantly degraded.

[0070] Comparative Example 4 This comparative example adopts the same implementation as Example 7, and the difference from Example 7 is that in this comparative example, the voltage of the DC power supply used in step S4 is 10 V. After 2 minutes of power-on, it is found that the superconducting layer gradually dissolves in the solution and completely loses the superconducting performance. This indicates that when the voltage parameter is high, the superconducting layer cannot remain stable in the electrolyte, but gradually dissolves in the solution under the action of the current. It can be seen that high voltage has a great damage to the superconducting performance of the REBCO tape.

[0071] From the results of Examples 8-9 and Comparative Examples 3-4, it can be seen that when the electrolysis voltage is 2.6V or above, the superconducting performance of the REBCO tape will be damaged. To ensure the stability of the superconducting performance, the electrolysis voltage should be controlled at 1-1.8V because the voltage of the DC power supply fluctuates by about 0.2V. When the voltage is lower than 1V, the electrolysis time will be greater than 10 minutes, and the superconducting layer will be immersed in the solution for too long, which significantly affects the stability of the superconducting performance.

[0072] Next, taking the electrolyte concentration of 0.04 mol / L and the electrolysis voltage of 1.4 V as an example, the effect of electrolyte temperature on the superconducting properties of REBCO tape during metal layer peeling was explored.

[0073] Example 10 This embodiment adopts the same implementation method as that of Embodiment 7, and the difference from Embodiment 7 is that in this embodiment, in step S4, the temperature of the silver nitrate solution is controlled at 0° C. by an ice bath, and the electrolysis power-on time is 10 min.

[0074] The REBCO tape obtained in step S4 of this embodiment with the metal layer completely peeled off in some areas is tested for superconducting performance using a superconducting performance testing system. The test results are as follows: Fig.10 As shown, from Fig.10 It can be seen that the critical current of the REBCO tape with the metal layer completely stripped off in some areas is 190.5 A, and the n value is 29.6. It can be seen that the superconducting performance of the REBCO tape with the metal layer completely stripped off in some areas of this embodiment has not declined, which indicates that the solution at 0°C corrodes the superconducting layer slowly.

[0075] Embodiment 11 This embodiment adopts the same implementation method as that of Embodiment 7, and the difference from Embodiment 7 is that in this embodiment, in step S4, the temperature of the silver nitrate solution is controlled at 20° C. by water bath heating, and the electrolysis power-on time is 4 minutes.

[0076] The REBCO tape obtained in step S4 of this embodiment with the metal layer completely peeled off in some areas is tested for superconducting performance using a superconducting performance testing system. The test results are as follows: Fig.11 As shown, from Fig.11It can be seen that the critical current of the REBCO tape with the metal layer completely stripped off in some areas is 189.1A, and the n value is 29.1. It can be seen that the superconducting performance of the REBCO tape with the metal layer completely stripped off in some areas of this embodiment has not shown obvious decline, but compared with Examples 7 and 10, the superconducting performance of the REBCO tape with the metal layer completely stripped off in some areas of this embodiment is slightly lower.

[0077] Comparative Example 5 This comparative example adopts the same implementation method as Example 7, and the difference from Example 7 is that in this comparative example, in step S4, the temperature of the silver nitrate solution is controlled at 30° C. by water bath heating, and the electrolysis power-on time is 3 minutes.

[0078] The REBCO tape obtained in step S4 of this comparative example with the metal layer completely peeled off in some areas was tested for superconducting performance using a superconducting performance testing system. The test results are as follows: Fig.12 As shown, from Fig.12 It can be seen that the critical current of the REBCO tape with the metal layer completely stripped off in some areas is 186.2A, and the n value is 26.3. It can be seen that the superconducting performance of the REBCO tape with the metal layer completely stripped off in some areas of this comparative example has slightly degraded.

[0079] From the results of the above Examples 10-11 and Comparative Example 5, it can be seen that when the temperature of the silver nitrate solution is controlled at 0°C by an ice bath, although the electrolysis time is increased to 10 minutes, the superconducting performance of the sample remains stable, which indicates that the low temperature environment may slow down the corrosion of the solution on the superconducting layer; when the temperature of the silver nitrate solution is controlled at 30°C by heating in a water bath, although the electrolysis time is shortened to 3 minutes, the superconducting performance of the sample is slightly degraded, which indicates that the high temperature environment may aggravate the corrosion of the solution on the superconducting layer; and the superconducting performance at temperatures below 20°C is not degraded. In order to ensure the stability of the superconducting performance, when the ambient temperature is higher than 20°C, an ice bath or a low-temperature water bath should be used to lower the electrolyte temperature to reduce the corrosion of the electrolyte on the superconducting layer.

[0080] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0081] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for stripping a metal layer of a REBCO tape superconducting joint without damaging the performance, characterized in that: It includes the following steps: S1. Protect the REBCO strip to expose the area to be peeled off; S2. The REBCO strip is immersed in a silver nitrate solution, washed, and dried; S3. The REBCO strip is used as an anode and an inert conductive material is used as a cathode for electrolysis; S4. After the REBCO tape is cleaned and dried, a REBCO tape with the metal layer peeled off is obtained.

2. The method for stripping a metal layer without damaging the performance of a REBCO tape superconducting joint according to claim 1, characterized in that: In step S1, the protective treatment method is: wrapping a sealing material around the non-peeling area of ​​the REBCO tape.

3. The method for stripping the metal layer of a REBCO tape superconducting joint without damaging the performance of the joint according to claim 2, characterized in that: The sealing material is at least one of polyvinyl chloride, polyethylene and polyimide.

4. The method for stripping a metal layer without damaging the performance of a REBCO tape superconducting joint according to claim 1, characterized in that: In step S2, the concentration of the silver nitrate solution is 0.04-0.1 mol / L; and / or the immersion time of the REBCO strip in the silver nitrate solution is 65-240 min; and / or the temperature of the silver nitrate solution is controlled at 0-20°C.

5. The method for stripping the metal layer of a REBCO tape superconducting joint without damaging the performance of the joint according to claim 1, characterized in that: In step S2, the cleaning is to place the REBCO tape in anhydrous ethanol and ultrasonically clean it for 1-5 minutes; And / or, in step S2, the drying is natural drying at room temperature for 10-20 minutes.

6. The method for stripping the metal layer of a REBCO tape superconducting joint without damaging the performance of the joint according to claim 1, characterized in that: In step S3, the voltage of the electrolysis is 1-1.8V; and / or, the current of the electrolysis is 0.01-0.1A; and / or, the time of the electrolysis is 2-10min.

7. The method for stripping the metal layer of a REBCO tape superconducting joint without damaging the performance of the joint according to claim 1, characterized in that: In step S3, the inert conductive material is graphite, silver or gold.

8. The method for stripping a metal layer without damaging the performance of a REBCO tape superconducting joint according to claim 1, characterized in that: In step S3, the distance between the REBCO tape and the inert conductive material is 1-10 cm.

9. The method for stripping a metal layer without damaging the performance of a REBCO tape superconducting joint according to claim 1, characterized in that: In step S3, the electrolytic solution is a silver nitrate solution with a concentration of 0.02-0.06 mol / L; and / or the temperature of the electrolytic solution is controlled to be 0-20°C.

10. The method for stripping a metal layer without damaging the performance of a REBCO tape superconducting joint according to claim 1, characterized in that: In step S4, the cleaning is to place the REBCO tape in anhydrous ethanol for ultrasonic cleaning for 1-5 minutes; And / or, in step S4, the drying is natural drying at room temperature for 10-20 minutes.

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