REBCO high-temperature superconducting tape for high-field magnet and preparation method of REBCO high-temperature superconducting tape

Abstract

The invention provides an REBCO high-temperature superconducting strip for a high-field magnet and a preparation method thereof. The REBCO high-temperature superconducting strip comprises a strip body, the straightness of the strip body is smaller than or equal to 8 mm, the width of the strip body is 3-5 mm, and the edge of the strip in the width direction is of a smooth integral structure without cutting marks. The arching amplitude of the strip body is not larger than 0.3 mm when the strip body is naturally placed, the strip body is formed by dynamic strip passing plating, and the strip body is wound by no more than twenty times during plating. The arching amplitude of natural placement of the strip body is limited to be not larger than 0.3 mm, the edge of the strip in the width direction is of a smooth integral structure without cutting marks, and a strip product with the width ranging from 3 mm to 5 mm and better performance compared with a superconducting strip obtained through cutting in the prior art can be obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of superconducting tapes, and in particular to a REBCO high-temperature superconducting tape for high-field magnets and a preparation method thereof. Background Art

[0002] REBCO high-temperature superconducting tapes made of REBCO (Re is a rare earth element) are also called coated conductors. Compared with bismuth-based tapes, they have stronger current-carrying capacity, higher magnetic field performance and lower material cost, and have broader and better application prospects in many fields such as medicine, military, and energy. REBCO high-temperature superconducting tapes are also called coated conductors because REBCO, as the core of superconducting current carrier, is hard and brittle. Therefore, it is generally produced by a multi-layer coating process on a nickel-based alloy substrate. It is generally composed of a base tape, a buffer layer (transition layer), a superconducting layer, and a protective layer.

[0003] The role of the metal substrate is to provide excellent mechanical properties for the strip. The role of the transition layer is to prevent the mutual diffusion of elements between the superconducting layer and the metal substrate. On the other hand, the top transition layer needs to provide a good template for the epitaxial growth of the superconducting layer and improve the quality of grain arrangement. To prepare a coated conductor with excellent superconducting properties, the superconducting layer needs to have a consistent biaxial texture. Biaxial texture means that the grains have almost consistent arrangement in both the a / b axis and the c axis (the c axis is perpendicular to the a / b plane).

[0004] Since the alignment degree of REBCO film in the a / b axis direction (in-plane texture) is relatively difficult to achieve, and poor in-plane texture will seriously reduce the superconducting performance. Therefore, REBCO superconducting film needs to be epitaxially grown on a transition layer that already has biaxial texture and matching lattice. There are two mainstream technical routes for preparing and realizing biaxial texture: one is rolling-assisted biaxial texture base tape technology, and the other is ion beam assisted deposition technology.

[0005] There are many common technologies for preparing REBCO superconducting layers, including pulsed laser deposition, metal organic chemical vapor deposition, metal organic salt deposition, reactive co-evaporation, etc. The protective layer is mainly used to protect the superconducting film layer. Generally, a 0.5-5μm silver layer is plated on the front and back surfaces of the superconducting tape by magnetron sputtering or evaporation. In order to pursue lower material costs, the silver layer on the superconducting surface is usually set at 1-2μm, and the silver layer on the non-superconducting surface is usually set at 0.5-1μm. Then, according to the requirements of the specific application for the width of the tape, the 10-12mm tape is cut into 2-8mm. Finally, copper plating or subsequent packaging reinforcement treatment is carried out. The copper plating thickness of the subsequent packaged tape can be 1-10μm. For copper-plated reinforced tape, the copper plating thickness on one side is 10-30μm, and on both sides it reaches 20-60μm.

[0006] Strong magnetic fields can provide rare extreme experimental conditions for cutting-edge research in multiple disciplines such as physics, materials, chemistry, and life sciences. The development of high-field magnets is of great significance for promoting scientific development. The development of high-field magnets has also promoted the development of high-temperature superconducting tapes. The high-field magnet based on REBCO high-temperature superconducting tapes has now reached 26.4T, exceeding the limit of low-temperature superconducting magnets such as NbTi-Nb3Sn, see "26T 35mm all-GdBa2Cu3O7–x multi-width no insulationsuperconducting magnet". In 2019, Wang Qiuliang's team from the Institute of Electrical Engineering of the Chinese Academy of Sciences inserted REBCO high-temperature superconducting magnets into the 17T background field generated by the low-temperature superconducting wire to wind a high-field magnet of 32.35T, breaking the world record for the magnetic field strength of all-superconducting magnets, see "World record 32.35tesla direct-current magnetic field generated with an all-superconducting magnet". In 2019, the U.S. High Magnetic Field Laboratory generated a 45.5T magnetic field strength on an existing 31T resistive magnet, breaking the world record for steady-state magnetic field strength, "45.5-tesla direct-current magnetic field generated with a high-temperature superconducting magnet". In 2023, the Institute of Plasma Physics of the Chinese Academy of Sciences broke the world record for high-field magnets based on REBCO high-temperature superconducting tapes, reaching 26.8T, see "26.86-tesla direct-current magnetic field generated with an all-REBCO superconducting magnet".

[0007] Currently, the commercial high-field magnets using REBCO high-temperature superconducting tapes are mainly used for high-resolution nuclear magnetic resonance (NMR) for biological structure analysis. The existing Ascend 1.1GHz model adopts the HTS / LTS hybrid magnet mode, with a standard aperture of 54mm and a central magnetic field strength of 25.9T. The development of this magnet is aimed at meeting the increasing scientific needs of scientists for sensitivity and higher resolution in the process of studying larger molecular weight proteins, functional disorder and macromolecular complexes. The 1.2GHz high-resolution protein NMR data was launched, and the magnetic field strength of the magnet reached more than 28T. It can be obtained from Figure 1 As can be seen in the figure, there is a huge difference in the clarity of imaging in the nuclear magnetic resonance spectrometer with and without high-temperature superconductivity.

[0008] When high-field magnets approach their limits, the strips are usually subjected to huge electromagnetic stress. Many magnets are damaged before quenching because the local strips cannot withstand such large stress. The U.S. High Field Laboratory dissected an inserted magnet based on REBCO high-temperature superconducting strips that was damaged during operation in a 31T magnetic field and found that the critical current of most of the strips had undergone overall degradation, such as Figure 2 As shown in the figure. The black line is the performance of the superconducting tape before use, and the blue line is the performance of the superconducting tape after the magnet is damaged. After the superconducting tape is unfolded, it can be seen that it has been greatly distorted, as shown in the figure below. Figure 3 As shown. After analysis, the National High Field Laboratory of the United States believes that in the high radial magnetic field area, the cracks at the edge of the REBCO high-temperature superconducting tape are the main cause of the final magnet damage, because the cracks are easy to expand under the action of the Lorentz force and eventually become a bottleneck point, such as Figure 4 shown.

[0009] Breaking through the limits of human magnetic fields is of great significance. As the most promising way to achieve controlled fusion energy generation, the Tokamak magnetic confinement nuclear fusion device highly relies on strong magnetic fields to confine high-temperature plasma to produce fusion reactions. Its unit volume fusion power density is proportional to the fourth power of the magnetic field strength (P∝B 4 ), therefore, increasing the magnetic field strength of the superconducting magnet system can very efficiently increase the fusion power density per unit volume and greatly reduce the size of the tokamak fusion device, greatly reducing the engineering difficulty of the entire system, and is expected to significantly accelerate the development of commercially available controlled nuclear fusion technology. It is equally important in the field of high-energy particle accelerators. For the next generation of the muon collider designed by the European Organization for Nuclear Research (CERN), it is even proposed that the material should work at 55T (which humans have not yet achieved). In order to improve the performance of the device or save costs, the increase in the magnetic field has become inevitable.

[0010] At present, all REBCO high-temperature superconducting tape manufacturers on the market produce 12mm wide superconducting tapes. Although 12mm wide superconducting tapes can be used directly in high fields to effectively avoid edge cracks, such wide superconducting tapes are difficult to withstand the shielding current effect under high fields. The problem of shielding current effect under high fields can be found in "Multifilamentary coated conductors for ultra-high magnetic field applications". Therefore, the current application units of high-field magnets generally accept a tape width of 3-4mm. Therefore, in response to the rigidity requirements of high magnetic fields, REBCO high-temperature superconducting tape manufacturers, under the leadership of the US High Field Laboratory, have begun to try to use laser slitting to cut 12mm width into 4mm width, such as Figure 5The American High Field Laboratory also conducted detailed experiments to compare the cuts of laser cutting by various mainstream manufacturers, and began to study the impact of laser cutting process on high field magnets, such as Figure 6 This includes the use of state-of-the-art magneto-optical equipment to study the mechanism of mechanical action of laser slitting cuts under tensile stress, such as Figure 7 As shown. It can be said that the entire industry is making 12mm wide strips, and then using laser cutting to avoid edge cracks to break through the human magnetic field limit. However, whether using ultraviolet or infrared laser cutting, the cut cracks are always different from the original superconducting tape material, such as Figure 8 As shown, it more or less affects the use of superconducting tapes. Summary of the invention

[0011] In view of the defects in the prior art, the object of the present invention is to provide a REBCO high temperature superconducting tape for high field magnets and a preparation method thereof.

[0012] A REBCO high-temperature superconducting tape for high-field magnets provided by the present invention comprises a tape body, wherein the straightness of the tape body is less than or equal to 8 mm, the width of the tape body is 3 mm to 5 mm, the edge of the tape in the width direction is a smooth integral structure without cutting marks; the amplitude of the natural arch of the tape body is no more than 0.3 mm.

[0013] Preferably, the magnetic field strength range of the high-field magnet made of the strip body is greater than or equal to 20 Tesla.

[0014] Preferably, the straightness of the strip body is 6 mm, and the width of the strip body is 4 mm.

[0015] According to the present invention, a method for preparing a REBCO high-temperature superconducting tape for a high-field magnet is provided, and the preparation method comprises the following steps: Step S1, cutting the metal substrate into strip materials of target width; Step S2, plating a buffer layer of target width on the strip material; Step S3, plating a seed layer of target width on the buffer layer of the strip material; Step S4, plating a cap layer of target width on the seed layer of the strip material; Step S5, plating a superconducting layer of target width on the cap layer of the strip material; Step S6, plating a silver protective layer of target width on the superconducting layer of the strip material; Step S7, plating a copper protective layer of target width on the silver protective layer of the strip material.

[0016] Preferably, step S1, cutting the Hastelloy substrate into strip materials of target width; Step S2, using a roll-to-roll magnetron sputtering coating device to coat a buffer layer of a target width on the strip material; Step S3, using a roll-to-roll ion beam assisted deposition (IBAD) or ion beam assisted evaporation (IBE) or inclined substrate deposition (ISD) device to plate a seed layer of a target width on the buffer layer of the strip material; Step S4, using roll-to-roll magnetron sputtering (MS) or pulsed laser deposition (PLD) equipment to deposit a cap layer of target width on the seed layer of the strip material; Step S5, using a roll-to-roll metal organic salt deposition (MOD) method, metal organic chemical vapor deposition (MOCVD) method, pulsed laser deposition (PLD) method, or reactive co-evaporation (RCE) coating device to plate a superconducting layer of a target width on the cap layer of the strip material; Step S6, using a roll-to-roll evaporation or magnetron sputtering coating device to plate a silver protective layer of target width on the superconducting layer of the strip material; Step S7: using electrochemical copper plating or roll-to-roll evaporation or magnetron sputtering coating equipment to plate a copper protective layer of target width on the silver protective layer of the strip material.

[0017] Preferably, the roll-to-roll structure comprises a drum and a pulley, the pulley is used for reeling and unreeling, and the strip material is rolled around the drum and the drum is lifted up.

[0018] Preferably, the roller is provided with spaced protrusions, the strip material is wound around the protrusions, and the width of the protrusions allows the width of the strip material to be covered.

[0019] Preferably, the roll-to-roll structure further comprises a spacing comb, and any one of the strip materials passes through the spacing comb.

[0020] Preferably, the strip body is plated by dynamic strip-walking at a certain temperature, and the strip body is wound for no more than twenty times during the plating.

[0021] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention limits the natural arch of the strip body to no more than 0.3 mm, and the edge of the strip in the width direction is a smooth overall structure without cutting marks, so as to obtain a strip product with a width of 3 mm to 5 mm with better performance than the superconducting strip obtained by cutting in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings: Figure 1 This is a diagram showing the effect of whether there is high-temperature superconducting imaging in a nuclear magnetic resonance spectrometer in the background technology; Figure 2 The background technology is to reflect the critical current effect diagram of the strip; Figure 3 This is a diagram showing the effect of superconducting tape after unfolding in the background technology; Figure 4 This is a rendering of the effect of the cracks on the edge of the REBCO strip that mainly reflect the effect of the magnet performance in the background technology; Figure 5 The data diagram mainly embodies laser cutting in the background technology to cut 12mm width into 4mm width; Figure 6 This is a diagram showing the effect of the laser cutting process on the high field magnet in the background technology; Figure 7 It is a mechanism effect diagram of the mechanical effect of the laser cutting cut under the tensile stress in the background technology; Figure 8 This is a comparison effect diagram that mainly reflects the difference between the cracks cut by ultraviolet and infrared lasers and the original superconducting tape material in the background technology; Fig. 9 This is a schematic diagram of a roll-to-roll tape conveying device mainly embodied in the present invention; Fig.10 This is a schematic diagram of a roller that mainly embodies the present invention; Fig.11 This is a schematic diagram of a roller mainly embodied in the present invention; Fig.12 This is a schematic diagram of a spacer comb mainly embodied in the present invention; Fig.13 It is a schematic diagram of the amplitude of the natural arching of the strip body according to the present invention. DETAILED DESCRIPTION

[0023] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0024] like Fig. 9 , Fig.10 , Fig.11 , Fig.12 as well as Fig.13As shown, a REBCO high-temperature superconducting tape for high-field magnets provided by the present invention includes a tape body, the straightness of the tape body is less than or equal to 8 mm, the width of the tape body is 3 mm to 5 mm, and the edge of the tape in the width direction is a smooth overall structure without cutting marks. The superconducting tape of the present application is directly plated by dynamic tape walking. Compared with the technical solution of first producing a 12 mm wide superconducting tape and then cutting it to form a superconducting tape with a width of 3 mm to 5 mm in the prior art, the edge of the tape produced in the present application in the width direction is a smooth overall structure without cutting marks.

[0025] The roll-to-roll coating method in the prior art can increase the coating area of ​​the target material on the strip, such as Fig. 9 As shown. These coating methods involve the coating of buffer layers, seed layers, cap layers, superconducting layers, and protective layers. Under the premise of ensuring the efficiency of strip coating: if the width of the roll-to-roll coated strip is small, the number of windings of the strip is large. For example, the width of the roll-to-roll coated strip in the prior art is 12 mm, and the number of windings is 10. Under the premise of ensuring the efficiency of strip coating, the strip with a width of 4 mm is directly plated, and the number of windings will reach 30. The tape tension is directly increased by 3 times, and because the strip width is reduced by 3 times, the tensile force that the strip can bear is reduced by 3 times, and the difference between one in and one out is 9 times. Since the superconducting tape itself is very thin, only 30μm-50μm, it has to go through high temperatures of several hundred degrees when it is made superconducting, which can easily cause the strip to deform and fail to meet the application requirements. Therefore, it is almost impossible for engineers in this field to directly produce a 4mm strip by roll-to-roll dynamic coating in the prior art.

[0026] Specifically, the surface of the superconducting tape must be flat and not deformed. If the tape is deformed, it cannot be wound into a flat pancake coil. The natural arch of the tape body is no more than 0.3 mm. Furthermore, the present application limits the magnetic field strength range of the high-field magnet made of the tape body to be greater than or equal to 20 Tesla, and the superconducting tape of the present application is made by roll-to-roll dynamic tape plating.

[0027] like Fig.13As shown, preferably, the straightness of the strip body is 6mm, the width of the strip body is 4mm, and the amplitude of the natural arch of the strip body is not more than 0.3mm. The strip body is plated by dynamic tape walking at a certain temperature, and the winding of the strip body during plating does not exceed twenty times. The certain temperature refers to 780℃ to 790℃. Further, the total thickness of the strip is preferably less than 50 microns, and the base tape thickness is preferably less than 30 microns. The temperature of superconducting tape plating has a certain influence on the performance of the strip. In the conventional scheme, the higher the plating temperature of the strip within the window temperature, the higher the current. Therefore, the conventional scheme will choose the highest possible plating temperature during plating. The present application selects 780℃ to 790℃ because when the present application directly plates a strip with a width of 4mm, there are certain requirements for the mechanical properties of the dynamic tape. If the plating temperature of the strip is too high, it will cause the mechanical properties of the strip to collapse.

[0028] The present invention also provides a method for preparing a REBCO high-temperature superconducting tape for a high-field magnet, which is used to prepare the above-mentioned thin tape with a width of 3 mm to 5 mm. The preparation method comprises the following steps: Step S1, cutting a metal substrate into strip materials of target width. Specifically, cutting a Hastelloy substrate into strip materials of target width.

[0029] Step S2, coating a buffer layer of a target width on the strip material. Specifically, coating a buffer layer of a target width on the strip material using a roll-to-roll magnetron sputtering coating device.

[0030] Step S3, coating a seed layer of target width on the buffer layer of the strip material. Specifically, coating a seed layer of target width on the buffer layer of the strip material using a roll-to-roll ion beam assisted deposition (IBAD) or ion beam assisted evaporation (IBE) or inclined substrate deposition (ISD) device.

[0031] Step S4, coating a cap layer of target width on the seed layer of the strip material. Specifically, coating a cap layer of target width on the seed layer of the strip material using a roll-to-roll magnetron sputtering (MS) or pulsed laser deposition (PLD) device.

[0032] Step S5, coating a superconducting layer of target width on the cap layer of the strip material. Specifically, coating a superconducting layer of target width on the cap layer of the strip material using a roll-to-roll metal organic salt deposition (MOD) or metal organic chemical vapor deposition (MOCVD) or pulsed laser deposition (PLD) or reactive co-evaporation (RCE) coating device.

[0033] Step S6, coating a silver protective layer of target width on the superconducting layer of the strip material. Specifically, coating a silver protective layer of target width on the superconducting layer of the strip material by roll-to-roll evaporation or magnetron sputtering coating equipment.

[0034] Step S7, plating a copper protective layer of target width on the silver protective layer of the strip material. Specifically, plating a copper protective layer of target width on the silver protective layer of the strip material by electrochemical copper plating or roll-to-roll evaporation or magnetron sputtering coating equipment.

[0035] More specifically, the roll-to-roll structure includes a drum and a pulley. The pulley is used to reel in and out the roll. The strip material is wound around the drum and the drum is lifted up. The drum is provided with a gap protrusion. The strip material is wound on the protrusion. The width of the protrusion allows the width of the strip material to be covered. The roll-to-roll structure also includes a spacing comb. Any strip material passes through the spacing comb. This ensures the stability of the mechanical properties of the strip with a width of 3mm to 5mm during the roll-to-roll dynamic tape plating process. It ensures that the amplitude of the natural arch of the strip body is no more than 0.3 mm, and the edge of the strip in the width direction is a smooth overall structure without cutting marks.

[0036] It should be noted that the roll-to-roll structure of the present application may include two rollers, one of which is located at the bottom and the other is located at the top, and the roller located at the bottom is lifted up. The roll-to-roll structure of the present application may also use one roller and one roller group, and the roller is located at the bottom and lifted up. With the lifted roller, the straightness of the strip body can be improved.

[0037] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0038] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A REBCO high temperature superconducting tape for high field magnets, characterized in that: It comprises a strip body, the straightness of the strip body is less than or equal to 8 mm, the width of the strip body is 3 mm to 5 mm, and the edge of the strip in the width direction is a smooth overall structure without cutting marks; The natural arching amplitude of the strip body is no more than 0.3 mm.

2. The REBCO high temperature superconducting tape for high field magnets according to claim 1, characterized in that: The magnetic field strength range of the high-field magnet made of the strip body is greater than or equal to 20 Tesla.

3. The REBCO high temperature superconducting tape for high field magnets according to claim 1, characterized in that: The straightness of the strip body is 6 mm, and the width of the strip body is 4 mm.

4. A method for preparing a REBCO high temperature superconducting tape for high field magnets, characterized in that: A method for preparing a REBCO high temperature superconducting tape for a high field magnet according to any one of claims 1 to 3 comprises the following steps: Step S1, cutting the metal substrate into strip materials of target width; Step S2, plating a buffer layer of target width on the strip material; Step S3, plating a seed layer of target width on the buffer layer of the strip material; Step S4, plating a cap layer of target width on the seed layer of the strip material; Step S5, plating a superconducting layer of target width on the cap layer of the strip material; Step S6, plating a silver protective layer of target width on the superconducting layer of the strip material; Step S7, plating a copper protective layer of target width on the silver protective layer of the strip material.

5. The method for preparing a REBCO high temperature superconducting tape for a high field magnet according to claim 4, characterized in that: Step S1, cutting the Hastelloy substrate into strip materials of target width; Step S2, using a roll-to-roll magnetron sputtering coating device to coat a buffer layer of a target width on the strip material; Step S3, using a roll-to-roll ion beam assisted deposition (IBAD) or ion beam assisted evaporation (IBE) or inclined substrate deposition (ISD) device to plate a seed layer of a target width on the buffer layer of the strip material; Step S4, using roll-to-roll magnetron sputtering (MS) or pulsed laser deposition (PLD) equipment to deposit a cap layer of target width on the seed layer of the strip material; Step S5, using a roll-to-roll metal organic salt deposition (MOD) method, metal organic chemical vapor deposition (MOCVD) method, pulsed laser deposition (PLD) method, or reactive co-evaporation (RCE) coating device to plate a superconducting layer of a target width on the cap layer of the strip material; Step S6, using a roll-to-roll evaporation or magnetron sputtering coating device to plate a silver protective layer of target width on the superconducting layer of the strip material; Step S7: using electrochemical copper plating or roll-to-roll evaporation or magnetron sputtering coating equipment to plate a copper protective layer of target width on the silver protective layer of the strip material.

6. The method for preparing a REBCO high temperature superconducting tape for a high field magnet according to claim 5, characterized in that: The roll-to-roll structure comprises a drum and a pulley, wherein the pulley is used for reeling in and out the roll, and the strip material is rolled around the drum and the drum is lifted up.

7. The method for preparing a REBCO high temperature superconducting tape for a high field magnet according to claim 5, characterized in that: The roller is provided with spaced protrusions, the strip material is wound around the protrusions, and the width of the protrusions allows the width of the strip material to be covered.

8. The method for preparing a REBCO high temperature superconducting tape for a high field magnet according to claim 5, characterized in that: The roll-to-roll structure further comprises a spacing comb, and any one of the strip materials passes through the spacing comb.

9. The method for preparing a REBCO high temperature superconducting tape for a high field magnet according to claim 5, characterized in that: The strip body is plated by dynamic strip-walking at a certain temperature, and the strip body is wound in no more than twenty passes during the plating process.

Images