KR102397467B1 - Method for repairing defect of high temperature superconducting wire and method for fabricating high temperature superconducting wire - Google Patents

Abstract

Disclosed is a method for repairing defects of a high-temperature superconducting wire according to an embodiment of the present invention, comprising attaching a superconducting patch without a substrate to a defective portion of the high-temperature superconducting wire.

Description

Defect repair method of high-temperature superconducting wire and manufacturing method of high-temperature superconducting wire

The present invention relates to the field of superconducting wires. More specifically, the present invention relates to a method for repairing defects in a high-temperature superconducting wire and to a method for manufacturing a high-temperature superconducting wire having excellent properties.

Superconductivity refers to a phenomenon in which electrical resistance suddenly disappears when a certain type of metal or alloy is cooled to near absolute zero (0K: -273°), and current flows without any obstacles. The superconductor is a low temperature superconductor (LTS) such as NbTi and Nb3Sn, YBCO (Y-Ba-Cu-O), BSCCO (Bi-Sr-Ca-Cu-O), TCBCO (Tl-Ca-) Ba-Cu-O), HBCCO (Hg-Ba-Ca-Cu-O), such as high temperature superconductor (HTS: High Temperature Superconductor) (critical temperature 25K or more) is classified.

A low-temperature superconductor has a critical temperature of 25K or less, and has the property of becoming a superconductor in liquid helium. A low-temperature superconductor has advantages of being easy to process as a wire and having excellent current characteristics. However, the use of helium has a disadvantage in that the cooling cost increases. In contrast, the high temperature superconductor has a critical temperature of 25K or higher, and has advantages in that it uses liquid nitrogen as a refrigerant to reduce cooling costs and has great application potential.

High-temperature superconductors can be used as wire products for joists, and high-temperature superconducting wires are required to have uniform performance in the longitudinal direction. This is, for example, to achieve stability from the quench of a superconducting magnet formed by winding a high-temperature superconducting wire and high uniformity of the generated magnetic field.

In general, defects may occur during various thin film processes during the manufacturing process of the high-temperature superconducting wire. Defects formed in the high-temperature superconducting wire eventually lead to defects in the superconducting layer, resulting in deterioration of magnetic field properties including the current through the superconducting layer.

It reduces the uniformity of performance in the longitudinal direction of the high-temperature superconducting wire, and makes it difficult to joist the high-temperature superconducting wire.

For example, it is assumed that a superconducting wire having a critical current of 600A at a length of 1,000m was manufactured, but when the critical current in the longitudinal direction was measured after manufacturing, the critical current was lowered to 300A due to three local defects. lets do it.

At this time, the superconducting wire company sells the manufactured high-temperature superconducting wire as a 1,000m long superconducting wire with a critical current of 300A, or cuts the superconducting wire to remove three defective spots and has a critical current of 1,000A. It can only be sold as a short-length superconducting wire.

In addition, defects occurring in the superconducting wire do not only occur during the manufacturing process of the wire, but may also occur while a user who has purchased the joist superconducting wire performs a work process such as winding and a storage process.

Accordingly, there is a need for a method capable of effectively repairing defects occurring in the high-temperature superconducting wire rod.

As a prior document, Japanese Publication No. JP 2013-122822 (2013. 06. 20.) and the like may be referred to.

A defect repair method for a high-temperature superconducting wire and a method for manufacturing a high-temperature superconducting wire according to an embodiment of the present invention aim to obtain a high-temperature superconducting wire of a joist.

In addition, the method for repairing defects of a high-temperature superconducting wire and manufacturing a high-temperature superconducting wire according to an embodiment of the present invention aims to achieve uniformity of performance of the high-temperature superconducting wire.

In addition, the method for repairing defects of a high-temperature superconducting wire and manufacturing a high-temperature superconducting wire according to an embodiment of the present invention aims to repair defects in the high-temperature superconducting wire in such a way that the thickness of the high-temperature superconducting wire does not significantly increase.

A defect repair method of a high-temperature superconducting wire according to an embodiment of the present invention,

In the defect repair method of a high-temperature superconducting wire, the method may include attaching a superconducting patch without a substrate to a defective portion of the high-temperature superconducting wire.

The high-temperature superconducting wire may include a first protective layer, and the attaching may include attaching a superconducting patch to the first protective layer at a defective portion of the high-temperature superconducting wire.

The high-temperature superconducting wire may further include a second protective layer positioned outside the first protective layer, and the attaching may include: removing the second protective layer; and attaching a superconducting patch to the first protective layer at a defective portion of the high-temperature superconducting wire.

The defect repair method of the high-temperature superconducting wire may further include depositing the second protective layer on the high-temperature superconducting wire to which the superconducting patch is attached.

The depositing of the second passivation layer includes the second passivation layer such that the thickness of the second passivation layer at the point where the superconducting patch is attached is smaller than the thickness of the second passivation layer at the point where the superconducting patch is not attached. Depositing a protective layer may be included.

The first protective layer and the protective layer of the superconducting patch attached to the first protective layer may be made of silver, and the second protective layer may be made of copper.

The defect repair method of the high-temperature superconducting wire may further include determining a defective portion of the high-temperature superconducting wire based on at least one of a hall probe and a 4-point probe.

The high-temperature superconducting wire may include a first-generation high-temperature superconducting wire or a second-generation high-temperature superconducting wire.

A method of manufacturing a high-temperature superconducting wire according to another embodiment of the present invention,

A method for manufacturing a high-temperature superconducting wire, the method comprising: generating a preliminary superconducting wire including a substrate, a buffer layer, a superconducting layer, and a first protective layer; determining a defect site in the preliminary superconducting wire; attaching a superconducting patch having no substrate to the determined defect region; and depositing a second protective layer on the preliminary superconducting wire to which the superconducting patch is attached.

The depositing of the second passivation layer includes the second passivation layer such that the thickness of the second passivation layer at the point where the superconducting patch is attached is smaller than the thickness of the second passivation layer at the point where the superconducting patch is not attached. Depositing a protective layer may be included.

Some effects that can be achieved by the defect repair method for a high-temperature superconducting wire and the method for manufacturing a high-temperature superconducting wire according to an embodiment of the present invention are as follows.

i) High-temperature superconducting wire rods of joists can be obtained.

ii) Performance uniformity of high-temperature superconducting wire can be achieved.

iii) The thickness of the high-temperature superconducting wire may not be significantly increased.

However, the effects that can be achieved by the method for repairing defects of a high-temperature superconducting wire and the method for manufacturing a high-temperature superconducting wire according to an embodiment of the present invention are not limited to those mentioned above, and other effects not mentioned are as follows. From the description, it will be clearly understood by those of ordinary skill in the art to which the present invention pertains.

1 is a view showing a general high-temperature superconducting wire.
2(a) and 2(b) are views for explaining a general method of bonding a high-temperature superconducting wire.
3 is a diagram illustrating a superconducting patch used in an embodiment of the present invention.
4 is a view showing a high-temperature superconducting wire repaired according to an embodiment of the present invention.
5(a) to 5(d) are views for explaining a defect repair method of a high-temperature superconducting wire according to another embodiment of the present invention.
6(a) to 6(c) are views for explaining a method of manufacturing a high-temperature superconducting wire according to an embodiment of the present invention.

Since the present invention can have various changes and can have various embodiments, specific embodiments are illustrated in the drawings and will be described in detail through the detailed description. However, this is not intended to limit the present invention to specific embodiments, and it should be understood that the present invention includes all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

Meanwhile, in the present specification, 'high-temperature superconducting wire' means second-generation high-temperature superconducting wire unless otherwise specified, and 'defective part' of high-temperature superconducting wire is the upper or lower surface of the high-temperature superconducting wire where the defect is located. means

Hereinafter, exemplary embodiments according to the technical spirit of the present invention will be described with reference to the drawings.

1 is a view showing a general high-temperature superconducting wire 10. As shown in FIG.

Referring to FIG. 1 , a typical high-temperature superconducting wire 10 may include a substrate 11 , a buffer layer 13 , a superconducting layer 15 , and protective layers 17 and 19 .

As the substrate 11 , a conventional substrate for manufacturing a superconducting wire, such as a metal substrate or a ceramic substrate, may be used. For example, the substrate 11 may be a metal substrate including nickel or a nickel alloy.

The buffer layer 13 is interposed between the substrate 11 and the superconducting layer 15 to provide crystallographic orientation to the subsequent superconducting layer 15 and at the same time to prevent diffusion of the metal material from the substrate 11 during the process. acts as a layer for The buffer layer 13 may be formed of at least one material selected from the group consisting of ZrO2, CeO2, YSZ, Y2O3, and HfO2. The buffer layer 13 may be formed as a single layer or a plurality of layers depending on the use and manufacturing method of the superconducting product.

The superconducting layer 15 may be made of a superconducting material including a rare earth element. For example, RE123 superconducting material typified by YBa2Cu3O7 may be used. In addition, a Bi-based superconducting material may be used as the superconducting layer 15 .

The protective layers 17 and 19 may be made of a conductive metal. The protective layers 17 and 19 may be attached to at least a portion of the outer periphery of the substrate 11 , the buffer layer 13 , and the superconducting layer 15 . The protective layers 17 and 19 may increase the mechanical strength of the superconducting wire 10 while improving overcurrent characteristics of the superconducting wire 10 .

The passivation layers 17 and 19 may include a first passivation layer 17 and a second passivation layer 19 . The first passivation layer 17 may be made of a first material (eg, silver (Ag)), and the second passivation layer 19 may be made of a second material (eg, copper (Cu)). there is.

In general, in the case of the substrate 11, the thickness is about 50 μm to 100 μm, the buffer layer 13 has a thickness within about 0.2 μm, and the superconducting layer 15 has a thickness of about 1 μm. , the first protective layer 17 has a thickness of less than about 2 μm, and the second protective layer 19 has a thickness of about 20 μm. That is, the thickness of the substrate 11 occupies more than half of the total thickness of the high-temperature superconducting wire 10 .

2(a) and 2(b) are views for explaining a method of bonding a general high-temperature superconducting wire 10. As shown in FIG.

When the high-temperature superconducting wire 10 is cut to remove the defective portion generated in the high-temperature superconducting wire 10, the length of the high-temperature superconducting wire 10 is inevitably shortened. Accordingly, in order to joist the high-temperature superconducting wire 10 , a method of bonding two or more high-temperature superconducting wires 10 to each other is required.

2(a) and 2(b) show a lab joint method. As shown in FIG. 2(a), any one high-temperature superconducting wire 10a and another high-temperature superconducting wire ( 10b) is attached with solder 20, or, as shown in FIG. 2(b), after arranging two high-temperature superconducting wires 10c and 10d in a line, two high-temperature superconducting wires 10c, Another high-temperature superconducting wire 10e may be attached to the upper portion of 10d) with solder 20 .

However, according to the method shown in FIGS. 2(a) and 2(b), the thickness of the joint portion of the finally produced high-temperature superconducting wire 10 is very large, and a step is generated in the thickness as a whole, so that the mechanical strength may be weakened, and cause a winding error during magnet winding, which may aggravate the error of the designed magnetic field.

Therefore, in the present invention, in repairing defects of the high-temperature superconducting wire 10 or manufacturing the high-temperature superconducting wire 10, a high-temperature superconducting patch in which the substrate 11 is not present is used to improve the thickness of the high-temperature superconducting wire 10. to prevent a significant increase in

3 is a diagram illustrating an exemplary superconducting patch 30 used in one embodiment of the present invention.

The superconducting patch 30 illustrated in FIG. 3 includes only the superconducting layer 15 and the protective layers 17 and 19 , and may include a portion of the buffer layer 13 in some cases. The passivation layers 17 and 19 may include a first passivation layer 17 and a second passivation layer 19 . Depending on the embodiment, the protective layers 17 and 19 may include only one of the first protective layer 17 and the second protective layer 19, and in another embodiment, the superconducting patch 30 ), only one of the first protective layer 17 and the second protective layer 19 may be present on the upper portion, and both the first protective layer 17 and the second protective layer 19 may be present on the lower portion. . The first passivation layer 17 may be made of a first material (eg, silver), and the second passivation layer 19 may be made of a second material (eg, copper).

It can be seen that the substrate 11 is not present in the superconducting patch 30 shown in FIG. 3 . That is, since the substrate 11 is removed from the structure of the high-temperature superconducting wire 10, it can be seen that the thickness thereof is very thin. The manufacturing method of the superconducting patch 30 shown in FIG. 3 is disclosed in Korean Publication No. 10-2014-0067495 (Applicant: Korea Electrotechnical Research Institute), and the content of Korean Publication No. 10-2014-0067495 is this Reference is made in the specification.

4 is a view showing a high-temperature superconducting wire 10 repaired according to an embodiment of the present invention.

4, when defects d1 and d2 exist in the high-temperature superconducting wire 10, the high-temperature superconducting wire 10 is formed by attaching the superconducting patch 30 to the surface of the high-temperature superconducting wire 10. Defects d1 and d2 can be repaired. In attaching the high-temperature superconducting wire 10 and the superconducting patch 30 to each other, the protective layer of the high-temperature superconducting wire 10 and the protective layer of the superconducting patch 30 can be directly attached without using solder. Accordingly, a decrease in electrical resistance between the high-temperature superconducting wire 10 and the superconducting patch 30 and an increase in thickness due to an additional bonding medium may be reduced.

The superconducting patch 30 provides a bypass path for the current flowing in the high-temperature superconducting wire 10 at the location where the defects d1 and d2 are generated, thereby uniformly maintaining the characteristics of the high-temperature superconducting wire 10 .

In addition, referring to FIG. 4 , the layers in which the defects d1 and d2 exist may be different. When the superconducting patch 30 is attached to the high temperature superconducting wire 10 , the high temperature superconducting wire 10 . It can be attached so as to cover the upper surface of the point where the major defects d1 and d2 are located.

Meanwhile, before attaching the superconducting patch 30 to the high-temperature superconducting wire 10 , the operation of selecting the superconducting patch 30 to be attached to the high-temperature superconducting wire 10 may be preceded. For example, if the critical current of the high-temperature superconducting wire 10 is lowered due to the defects d1 and d2, the superconducting patch 30 having a critical current characteristic higher than the critical current of the high-temperature superconducting wire 10 should be selected. will be.

5(a) to 5(d) are diagrams for explaining a defect repair method of the superconducting wire 10 according to another embodiment of the present invention.

As described above, the protective layers 17 and 19 of the high-temperature superconducting wire 10 and the protective layers 17 and 19 of the superconducting patch 30 include a first protective layer 17 made of silver and a second protective layer 17 made of copper. A protective layer 19 may be included, and in attaching the superconducting patch 30 to the high-temperature superconducting wire 10 , it is preferable that the first protective layers 17 made of silver are attached to each other. This is because bonding between the first protective layers 17 made of silver is performed by a relatively simple method without a special medium, and silver (Ag) has high electrical conductivity and excellent chemical stability. Accordingly, it is possible to reduce the electrical resistance between the high-temperature superconducting wire 10 and the superconducting patch 30 and at the same time reduce the increase in thickness due to an additional bonding medium.

In attaching the first protective layer 17 of the high-temperature superconducting wire 10 made of silver and the first protective layer 17 of the superconducting patch 30 to each other, an attachment method through heat treatment, silver paste An attachment method using a silver complex compound or an attachment method using a silver complex compound may be used.

First, Fig. 5 (a) shows the high-temperature superconducting wire 10, as shown in Fig. 5 (a). Two defects d1 and d2 may be formed in the high-temperature superconducting wire 10 . The positions of the defects d1 and d2 in the high-temperature superconducting wire 10 may be determined based on at least one of a hall probe and a 4-point probe. Since the Hall probe and the 4-needle method are instruments and methods utilized in the art, a detailed description thereof will be omitted herein. The positions and numbers of the defects d1 and d2 shown in FIG. 5( a ) are only examples, and the number and positions of the defects may be variously changed. FIG. 5(a) shows that the defect d1 is located in the superconducting layer 15 and the defect d2 is located in the buffer layer 13. The defect d1 is based on at least one of a Hall probe and a quaternary method , d2), it may be difficult to determine in which layer the actual defects d1 and d2 exist. Instead, by checking in which area of the entire area of the upper surface of the high-temperature superconducting wire 10 in the longitudinal direction the properties of the superconducting wire are deteriorated, it can be recognized that a defect has occurred in at least one of the lower layers of the confirmed area. there is.

Next, referring to FIG. 5B , the second protective layer 19 at the position where the superconducting patch 30 is to be attached is removed from the high temperature superconducting wire 10 . Next, as shown in FIG. 5C , the superconducting patch 30 is attached to the surface of the first protective layer 17 . When the second protective layer 19 made of copper is present on the superconducting patch 30 before attaching the superconducting patch 30 to the first protective layer 17 , the second protective layer 19 of the superconducting patch 30 is ) may be removed.

Finally, as shown in FIG. 5(d), a second protective layer 19 is deposited on the surface of the high-temperature superconducting wire 10 to which the superconducting patch 30 is attached. At this time, the thickness t1 of the second protective layer 19 at the point where the superconducting patch 30 is attached is the same as the thickness t1 at the point where the superconducting patch 30 is not attached so that a step does not occur in the high-temperature superconducting wire 10 . It is made to be smaller than the thickness t2 of the second protective layer 19 .

In the high-temperature superconducting wire 10 shown in Fig. 5(d), since the superconducting patch 30 is attached to the upper portion of the position where the defects d1 and d2 are generated, the uniformity of the performance of the high-temperature superconducting wire 10 is can be achieved.

6(a) to 6(c) are diagrams for explaining a method of manufacturing a superconducting wire 630 according to an embodiment of the present invention.

First, as shown in FIG. 6A , a preliminary superconducting wire 610 including a substrate 11 , a buffer layer 13 , a superconducting layer 15 , and a first protective layer 17 is generated.

Next, the positions of the defects d1 and d2 generated in the preliminary superconducting wire 610 are determined based on at least one of a hall probe and a 4-point probe, and in FIG. As shown, the superconducting patch 30 is attached to the surface of the position where the defects d1 and d2 occur. When the second protective layer 19 made of copper is present on the superconducting patch 30 before attaching the superconducting patch 30 to the first protective layer 17 , the second protective layer 19 of the superconducting patch 30 is ) may be removed.

Finally, as shown in FIG. 6(c), a second protective layer 19 is deposited on the surface of the high-temperature superconducting wire 630 to which the superconducting patch 30 is attached. At this time, the thickness t1 of the second protective layer 19 at the point where the superconducting patch 30 is attached so as not to cause a step difference in the high-temperature superconducting wire 630 is the same as the thickness t1 at the point where the superconducting patch 30 is not attached. It is made to be smaller than the thickness t2 of the second protective layer 19 .

On the other hand, the above-described defect repair method of the high-temperature superconducting wire and the method of manufacturing the high-temperature superconducting wire may be applied to the first-generation high-temperature superconducting wire.

A general first-generation high-temperature superconducting wire includes a normal conductor and a bundle of superconducting filaments included in the normal conductor along the longitudinal direction of the normal conductor. The normal conductor corresponds to the first protective layer of the second-generation high-temperature superconducting wire, and may be made of silver (Ag). The superconducting filament bundle may be composed of BSCCO 2223 or BSCCO 2212. A second protective layer made of copper may be attached to the surface of the normal conductor.

When a defect occurs in the first-generation high-temperature superconducting wire, the second protective layer is removed, the superconducting patch is attached to the defective part, and the second protective layer is attached to the surface of the superconducting patch and the normal conductor. Defect repair becomes possible.

In addition, in manufacturing the first-generation high-temperature superconducting wire, a preliminary superconducting wire including a normal conductor and a bundle of superconducting filaments is produced, then the superconducting patch is attached to the defect location, and a second protective layer is formed on the surface of the superconducting patch and the normal conductor. By attaching it, it becomes possible to manufacture a first-generation high-temperature superconducting wire.

The defect repair method and the method for manufacturing a high-temperature superconducting wire according to an embodiment of the present invention can obtain a high-temperature superconducting wire of a joist and achieve uniformity of performance of the high-temperature superconducting wire. In addition, the defect repair method of the high temperature superconducting wire and the method of manufacturing the high temperature superconducting wire according to an embodiment of the present invention can repair defects in the superconducting wire in such a way that the thickness of the high temperature superconducting wire does not significantly increase.

Although embodiments of the present invention have been described with reference to the accompanying drawings, those of ordinary skill in the art to which the present invention pertains will realize that the present invention may be embodied in other specific forms without changing the technical spirit or essential features thereof. you will understand Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

10: general high-temperature superconducting wire
11: Substrate
13: buffer layer
15: superconducting layer
17: first protective layer
19: second protective layer
20: Solder
30: Superconducting patch
610: preliminary superconducting wire
630: high temperature superconducting wire

Claims (10)

A method for repairing defects in a high-temperature superconducting wire including a substrate, a buffer layer, a superconducting layer and a first protective layer, the method comprising:
directly attaching the protective layer surface of the superconducting patch in which the substrate does not exist without solder on the first protective layer at the defective portion of the high-temperature superconducting wire including the substrate made of metal or ceramic; and
depositing a second protective layer on the high-temperature superconducting wire to which the superconducting patch is attached;
In the attaching step, the first protective layer of the high-temperature superconducting wire of a conductive metal and the protective layer surface of the superconducting patch are electrically connected by a heat treatment attachment method, a paste attachment method, or an attachment method using a complex compound.
In the step of depositing the second passivation layer, the thickness of the second passivation layer at the point where the superconducting patch is attached is smaller than the thickness of the second passivation layer at the point where the superconducting patch is not attached. A method for repairing defects in a high-temperature superconducting wire by depositing a second protective layer.
delete According to claim 1,
The high-temperature superconducting wire is
Further comprising the second protective layer positioned on the first protective layer,
The attaching step is
and attaching the superconducting patch on the first protective layer by removing the second protective layer positioned on the first protective layer at the defective portion of the high-temperature superconducting wire. method of repairing defects.
delete delete 4. The method of claim 3,
The first protective layer and the protective layer of the superconducting patch attached to the first protective layer are made of silver,
The second protective layer is a defect repair method of a high-temperature superconducting wire, characterized in that made of copper.
According to claim 1,
The defect repair method of the high-temperature superconducting wire is,
The method for repairing defects of a high-temperature superconducting wire according to claim 1, further comprising: determining a defective portion of the high-temperature superconducting wire based on at least one of a hall probe and a 4-point probe.
According to claim 1,
The high-temperature superconducting wire is
A defect repair method of a high-temperature superconducting wire, comprising a first-generation high-temperature superconducting wire or a second-generation high-temperature superconducting wire.
A method for manufacturing a high-temperature superconducting wire, the method comprising:
generating a preliminary superconducting wire including a substrate, a buffer layer, a superconducting layer, and a first protective layer, wherein the substrate is made of metal or ceramic;
determining a defect site in the preliminary superconducting wire;
attaching the protective layer surface of the superconducting patch in which the substrate does not exist directly to the determined defect region without solder; and
depositing a second protective layer on the preliminary superconducting wire to which the superconducting patch is attached;
In the attaching step, the first protective layer of the high-temperature superconducting wire of a conductive metal and the protective layer surface of the superconducting patch are electrically connected by a heat treatment attachment method, a paste attachment method, or an attachment method using a complex compound.
In the step of depositing the second passivation layer, the thickness of the second passivation layer at the point where the superconducting patch is attached is smaller than the thickness of the second passivation layer at the point where the superconducting patch is not attached. A method for manufacturing a high-temperature superconducting wire, comprising depositing a second protective layer. delete

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