Superconducting tape homogenization treatment method, superconducting tape and current limiter

Abstract

The present invention provides a method for homogenizing a superconducting tape, a superconducting tape and a current limiter, comprising: a critical current detection step: performing critical current detection on the superconducting tape to obtain corresponding critical current distribution data; a difference determination step: obtaining the difference between the critical current value of each part of the superconducting tape and the minimum critical current value of the superconducting tape according to the critical current distribution data; an etching step: etching the corresponding part according to the difference of each part of the superconducting tape, thereby reducing the critical current value of the corresponding part. The present invention smoothes the critical current value of the entire superconducting tape by etching, thereby avoiding the influence of uneven quenching of the superconducting tape caused by the impact current on the current limiter composed of the superconducting tape.

Description

Technical Field

[0001] The present invention relates to the field of superconducting technology, and in particular to a method for homogenizing a superconducting tape, a superconducting tape and a current limiter. Background Art

[0002] The second generation superconducting tape is generally produced by a multi-layer coating process on a nickel-based alloy substrate because its ReBCO, which is the core of the superconducting current carrier, is hard and brittle. Therefore, it is also called a coated conductor. The second generation superconducting tape is generally composed of a base tape, a buffer layer (transition layer), a superconducting layer and a protective layer. The role of the metal substrate is to provide excellent mechanical properties for the tape. On the one hand, 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 arrangement quality of the YBCO grains. To prepare a coated conductor with excellent superconducting performance, the superconducting layer needs to have a consistent biaxial texture. Biaxial texture refers to the grains having almost consistent arrangement in both the a / b axis and the c axis (the c axis is perpendicular to the a / b plane). Since the degree of arrangement of the YBCO film in the a / b axis direction (in-plane texture) is relatively difficult to achieve, poor in-plane texture will seriously reduce the superconducting performance. Therefore, it is necessary to epitaxially grow the YBCO superconducting film on the transition layer that already has biaxial texture and matching lattice. There are two mainstream technical routes for preparing biaxial texture, one is rolling-assisted biaxial texture base tape technology, and the other is ion beam assisted deposition technology. There are many common technologies for preparing ReBCO superconducting layers, including pulsed laser deposition, metal organic chemical vapor deposition, reactive co-evaporation, etc. The protective layer is mainly used to protect the superconducting film layer, and generally a 1-5um silver layer is plated on the surface of the superconducting tape.

[0003] However, these superconducting tapes still have many weaknesses due to the limitations of their own materials or manufacturing processes. In particular, when they are applied to specific superconducting application devices, these materials need to go through joint production, coil winding, epoxy impregnation, vacuum casting during processing. In application, they need to be rapidly cooled and heated, undergo a large number of hot and cold cycles, and are subject to stress caused by large magnetic fields, impacts of large currents, and other complex working conditions. It can be said that the performance of superconducting tapes that have been purely initially protected by silver is far from meeting the working conditions of actual superconducting tape applications, especially electrical and mechanical properties. Therefore, on this basis, the common practice is to perform surface copper plating, that is, electroplating a 1-80um copper layer on the surface of the already silver-plated superconducting tape.

[0004] The superconducting tape strengthened by electroplating can adapt to some application environments, but it still cannot meet the requirements for many superconducting application conditions, especially the tape of superconducting resistance type current limiter. The main consideration is that the tape has a large resistance after quenching. It must be able to resist a certain mechanical impact. At this time, the protective layer uses a material with high thermal conductivity, high strength, and high resistance, such as stainless steel. Therefore, it is necessary to use stainless steel materials to encapsulate and strengthen the superconducting tape, that is, to use a stainless steel coating tape to achieve a comprehensive coating treatment of the superconducting tape through a hot dip plating process. According to the encapsulation-enhanced superconducting tape described in patent document CN201710416026.8, it has multiple advantages: for example, the surface oxidation resistance, processability, and fatigue resistance of the superconducting tape are greatly enhanced, the delamination stress resistance will be greatly enhanced, the tensile stress resistance will be greatly enhanced, the steady-state overcurrent resistance will be greatly enhanced, and the transient overcurrent resistance will be greatly enhanced.

[0005] The superconducting resistor type current limiter has a high uniformity requirement for the superconducting tape, because every meter of tape in the entire current limiter needs to be able to evenly withstand the short-circuit impact current. If there is a large deviation in the performance of the tape, it is bound to cause a part of the superconducting tape to only undertake a small work, and a large amount of impact current will be squeezed to the other part of the superconducting tape, increasing their burden. If a small section of the tape in the entire current limiter cannot withstand such an impact, the entire current limiter will be burned.

[0006] However, it is not easy to make the critical current of a second-generation high-temperature superconducting material uniform during the manufacturing process. Due to the complex process, the critical current of a strip often changes greatly with the fluctuation of some process parameters. This will cause great trouble in the application process. Summary of the invention

[0007] In view of the defects in the prior art, the object of the present invention is to provide a method for homogenizing a superconducting tape, a superconducting tape and a current limiter.

[0008] A method for homogenizing a superconducting tape provided by the present invention comprises:

[0009] Critical current detection step: performing critical current detection on the superconducting tape to obtain corresponding critical current distribution data;

[0010] A difference determination step: obtaining, according to the critical current distribution data, a difference between the critical current value of each part of the superconducting tape and an acceptable minimum value of the critical current of the superconducting tape;

[0011] Etching step: etching corresponding parts according to the difference between the parts of the superconducting tape, thereby reducing the critical current value of the corresponding parts.

[0012] Preferably, the etching direction is to etch line segments along the width direction on the surface of the superconducting layer.

[0013] Preferably, the etching method is to etch from one layer of the superconducting tape toward the other side, or to etch from both sides of the tape toward the middle.

[0014] Preferably, the etching is performed by laser etching or mechanical etching.

[0015] Preferably, after the etching step, the method further comprises coating the superconducting tape with a protective layer;

[0016] The protection layer includes a copper layer.

[0017] Preferably, a packaging layer is further arranged on the periphery of the protective layer.

[0018] Preferably, the etching position is located in the superconducting layer of the superconducting tape.

[0019] Preferably, the etching step further comprises: after etching, returning to the critical current detection step until the difference between the critical current value after the corresponding part is reduced and the lowest critical current value is within a preset range.

[0020] A superconducting tape provided by the present invention is prepared by adopting the above-mentioned superconducting tape homogenization treatment method.

[0021] A current limiter provided according to the present invention comprises a plurality of superconducting tapes connected in parallel or in series, and the critical current values ​​of the plurality of superconducting tapes are within a preset deviation range.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The invention makes the critical current value of the whole superconducting tape smooth by etching, thereby avoiding the influence of uneven quenching of the superconducting tape caused by the impact current on the current limiter composed of the superconducting tape. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] 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:

[0025] Figure 1 is the critical current value of a strip material in an embodiment of the present invention;

[0026] Figure 2 It is a schematic diagram of the strip after etching of the present invention;

[0027] Figure 3 It is a schematic diagram of the effect of mechanical etching;

[0028] Figure 4 This is a schematic diagram of the effect of laser etching;

[0029] Figure 5 Schematic diagram of the critical current of the superconducting tape before etching;

[0030] Figure 6 Schematic diagram of the critical current of the superconducting tape after etching. DETAILED DESCRIPTION

[0031] 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.

[0032] The present invention provides a method for homogenizing a superconducting tape, comprising:

[0033] Critical current detection steps: Figure 1 As shown, the critical current of the superconducting tape is detected to obtain the corresponding critical current distribution data. Under normal circumstances, there will be a certain deviation in the critical current values ​​between different positions of the superconducting tape.

[0034] Difference determination step: According to the critical current distribution data, the difference between the critical current value of each part of the superconducting tape and the acceptable minimum value of the critical current of the superconducting tape is obtained. For example, if the tape is required to be 100A±10A, we can take 100A as the target and etch to 100A, and ignore 90A.

[0035] Etching steps: According to the difference between each part of the superconducting tape, such as Figure 2 As shown, etching is performed on the corresponding part, thereby reducing the critical current value of the corresponding part. The superconducting tape will reduce the critical current value of the corresponding part due to etching, so that the critical current value of each part of the entire superconducting tape is within a preset deviation range.

[0036] In order to ensure the effect after etching, after etching, the critical current detection step is returned until the difference between the critical current value after the corresponding part is reduced and the lowest critical current value is within a preset range.

[0037] Etching can be done using Figure 3 Mechanical etching or Figure 4 The laser etching shown includes etching from one layer of the superconducting tape to the other side, or etching from both sides of the tape to the middle.

[0038] by Figure 5 Taking the critical current value of the unetched superconducting tape as an example, after etching the superconducting tape according to the above method, the critical current value obtained is as follows Figure 6 shown.

[0039] After the etching step, the method further includes plating a protective layer on the superconducting tape. The protective layer may be a copper layer, and a packaging layer is disposed on the periphery of the protective layer for packaging.

[0040] Although the superconducting tape prepared by the present invention reduces the critical current value of the superconducting tape as a whole, it can make the critical current value of the entire superconducting tape smooth and controllable. The current limiter made of superconducting tapes with multiple critical current values ​​within the preset deviation range can effectively avoid damage caused by impact current.

[0041] 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.

[0042] 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 method for homogenizing a superconducting tape, characterized in that: include: Critical current detection step: performing critical current detection on the superconducting tape to obtain corresponding critical current distribution data; A difference determination step: obtaining, according to the critical current distribution data, a difference between the critical current value of each part of the superconducting tape and an acceptable minimum value of the critical current of the superconducting tape; Etching step: etching corresponding parts according to the difference between the parts of the superconducting tape, thereby reducing the critical current value of the corresponding parts.

2. The method for homogenizing a superconducting tape according to claim 1, characterized in that: The etching direction is to etch line segments along the width direction on the surface of the superconducting layer.

3. The method for homogenizing a superconducting tape according to claim 2, characterized in that: The etching method is to etch from one layer of the superconducting tape to the other side, or to etch from both sides of the tape to the middle.

4. The method for homogenizing a superconducting tape according to claim 1, characterized in that: The etching is performed by laser etching or mechanical etching.

5. The method for homogenizing a superconducting tape according to claim 1, characterized in that: After the etching step, the method further comprises coating the superconducting tape with a protective layer; The protection layer includes a copper layer.

6. The method for homogenizing a superconducting tape according to claim 5, characterized in that: A packaging layer is also arranged on the periphery of the protective layer.

7. The method for homogenizing a superconducting tape according to claim 1, characterized in that: The etching position is located at the superconducting layer of the superconducting tape.

8. The method for homogenizing a superconducting tape according to claim 1, characterized in that: The etching step further includes: after etching, returning to the critical current detection step until the difference between the critical current value after the corresponding part is reduced and the acceptable minimum value of the critical current is within a preset range.

9. A superconducting tape, characterized in that: The superconducting tape is prepared by the homogenization treatment method of claim 1.

10. A current limiter, characterized in that: The method comprises a plurality of superconducting tapes according to claim 9 connected in parallel or in series, wherein critical current values ​​of the plurality of superconducting tapes are within a preset deviation range.

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