CN211455985U - Superconducting tape - Google Patents
Superconducting tape Download PDFInfo
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- CN211455985U CN211455985U CN201922245127.0U CN201922245127U CN211455985U CN 211455985 U CN211455985 U CN 211455985U CN 201922245127 U CN201922245127 U CN 201922245127U CN 211455985 U CN211455985 U CN 211455985U
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Abstract
The utility model discloses a superconducting tape, which comprises at least two superconducting bare belts, wherein the surfaces of the superconducting bare belts are covered with silver coatings; the welding parts adjacent to the superconducting bare belt are attached, the adjacent silver coating layers are oppositely arranged, and the welding parts adjacent to the superconducting bare belt are welded through welding flux; the solder comprises nano metal, and the volume resistivity of the solder is 10‑8Ω·m magnitude and below; the free surface of the superconducting bare belt is coated with a metal layer. The utility model discloses well welded joint department has better mechanical properties, easily welds simultaneously.
Description
Technical Field
The utility model relates to a superconducting material field, concretely relates to superconducting tape.
Background
With the wide research and application of superconducting technology in many fields, the requirement for the length of superconducting tapes is higher and higher, the length of the superconducting tapes cannot meet the actual requirement at present, the situation of superconducting tape welding becomes trend, and many domestic units also develop researches to different degrees.
The jointless quality is the best for superconducting tapes, but in view of the limited length of superconducting tapes currently produced, the lower the yield of the tapes, and in practice, if longer tapes are required, only the manner of intermediate joints is adopted. The welding process of the superconducting material comprises soft soldering, diffusion welding and superconducting welding. Wherein, the diffusion welding requires higher temperature and pressure, and the requirement on the uniformity of the superconducting tape is higher; the superconducting welding can realize an unobstructed joint, but the process is more complex, and only a few people are researching at present. Conventional soldering methods are relatively simple, but are difficult to achieve low joint resistance values. Therefore, it is required to search for a superconducting tape having good mechanical properties at a welded joint and being easily welded.
Disclosure of Invention
The to-be-solved technical problem of the utility model is to provide a superconducting tape, its welded joint department has better mechanical properties, easily welds simultaneously.
In order to solve the technical problem, the utility model provides a superconducting strip, which comprises at least two superconducting bare belts, wherein the surfaces of the superconducting bare belts are covered with silver coatings; the welding parts adjacent to the superconducting bare belt are attached, the adjacent silver coating layers are oppositely arranged, and the welding parts adjacent to the superconducting bare belt are welded through welding flux; the solder comprises nano metal, and the volume resistivity of the solder is 10-8Omega m magnitude and below; liberation of said bare superconducting tapeThe bread is covered with a metal layer.
Furthermore, the particle size of the nano metal is 20-100 nm.
Further, the thermal conductivity of the solder is greater than or equal to 70W/K.m.
Further, the concentration of the nano-metal in the solder is greater than or equal to 85%.
Further, the solder is coated on the surface of the silver coating layer, and the coating thickness of the solder is less than 50 μm.
Furthermore, the welding end of the welding bare belt is arranged in a round angle mode.
Further, the nano metal comprises nano silver, nano silver alloy, nano gold or nano gold alloy.
The utility model has the advantages that:
sequentially welding adjacent superconducting bare belts, and then coating a metal layer on the outer parts of the welded superconducting bare belts to form superconducting belts with required lengths; the welding parts of the adjacent superconducting bare belts are jointed, and the adjacent superconducting bare belts can be welded through welding flux; when the adjacent superconducting bare belts are welded and fixed, the silver coatings coated on the surfaces of the superconducting bare belts are oppositely arranged, namely, the silver coatings of the adjacent welding bare belts are bonded by welding flux so as to connect the two adjacent superconducting bare belts; and after the welding is finished, coating a metal layer on the outer part of the superconducting bare belt to obtain the superconducting belt material.
Drawings
Fig. 1 is an overall schematic view of the present invention;
fig. 2 is a schematic diagram of the welding of adjacent bare superconducting tapes in the present invention.
The reference numbers in the figures illustrate: 1. a metal layer; 2. a superconducting bare tape; 3. welding flux; 4. and a silver coating.
Detailed Description
The present invention is further described with reference to the following drawings and specific embodiments so that those skilled in the art can better understand the present invention and can implement the present invention, but the embodiments are not to be construed as limiting the present invention.
Referring to fig. 1 and 2, an embodiment of a superconducting tape according to the present invention includes at least two bare superconducting tapes 2 and a silver coating layer 4 coated on the surface of the bare superconducting tapes 2, and the bare superconducting tapes are formed by sequentially welding adjacent bare superconducting tapes 2 and then coating the outer portion of the bare superconducting tapes 2 with a metal coating layer 1 to form a superconducting tape having a desired length. The welding parts of the adjacent superconducting bare tapes 2 are attached, and the adjacent superconducting bare tapes 2 can be welded by the welding material 3. When the adjacent superconducting bare belts 2 are welded and fixed, the silver coatings 4 coated on the surfaces of the superconducting bare belts 2 are oppositely arranged, namely, the silver coatings 4 of the adjacent welding bare belts are bonded by the welding flux 3 to connect the two adjacent superconducting bare belts 2. And after welding is finished, coating the metal layer 1 on the outer part of the superconducting bare belt 2 to obtain the superconducting belt material.
The welding mode of the superconductive bare belt in the prior art mainly comprises the welding processes of a superconductive material, such as soft soldering, diffusion welding and superconductive welding. The diffusion welding requires higher temperature and pressure, and the requirement on the uniformity of the superconducting tape is higher; the superconducting welding can realize an unobstructed joint, but the process is more complex, and only a few people are researching at present. The common soldering process has strict requirements on the welding process in the process of welding the superconducting bare belt, and meanwhile, the resistivity of the solder is generally 10-7Omega m magnitude and above. The temperature range of the solder is small in the process of soldering, and the solder with high temperature needs to be selected when the superconducting bare belts are welded because the superconducting bare belts need to be subjected to a soldering packaging process after being welded. However, the lattice structure of the superconducting layer is easily changed at high temperature, so that the superconducting material may lose the superconducting property due to oxygen loss in the soldering process, thereby narrowing the temperature range of solder selection. Meanwhile, the difficulty of the welding process is increased, and the preparation of the superconducting tape is not easy.
The solder 3 contains nano metal, and the volume resistivity of the solder 3 is 10-8The omega m is in order of magnitude and below, so when the solder 3 is used for welding, the resistivity of a welding joint is lower than that of the soldering solder 3 in the prior art, and the conductivity of the bare belt body is improved.
Further, the solder 3 has a thermal conductivity of 70W/K.m or more, so that heat transfer can be performed rapidly during soldering, and loss of superconducting properties of the superconducting tape due to local overheating can be prevented. In addition, the use of the solder 3 containing the nano metal can prevent the soldering from using the flux to cause environmental and weldment pollution.
In this embodiment, the nano metal includes nano silver, nano silver alloy, nano gold, or nano gold alloy, because silver and gold have excellent thermal conductivity and electrical conductivity, the nano metal in this embodiment is selected from nano silver or nano silver alloy. Meanwhile, the solder 3 is coated on the surface of the silver coating 4 of the superconducting bare belt 2, and nano silver or nano silver alloy is easier to bond with nano silver particles of the superconducting bare belt 2 in the welding process; and the melting temperature of the sintered nano silver or nano alloy is close to the melting point of the nano material, so that the mechanical strength of the welding joint can be improved by utilizing the nano silver or nano silver alloy for welding. Solder 3 containing nano silver or nano silver alloy, wherein the specific resistance of the solder 3 can reach 10-8Omega.m or less, and the resistance of the welding joint obtained after the nano silver is sintered can reach 10 under the condition of ensuring the process condition-9Omega m or less. Meanwhile, by using the solder 3 containing nano silver or nano silver alloy, in the process of sintering and welding the two superconducting bare belts 2 with the silver coating 4 of the superconducting bare belt 2, the welding interface has high tissue density and small gaps, so that the resistance of the welding joint is lower, and the performance of the superconducting belt material at the joint is improved. Further, the concentration of nano silver or nano silver alloy in the solder 3 is 85% or more to increase the mechanical strength at the soldered joint. Of course, the nano-metal may also include other nano-particles with low resistivity and high thermal conductivity.
The grain diameter of the nano metal in the solder 3 is 20-100 nm, and the grain diameter of the nano particles is finally determined by a specific preparation process. When the particle size of the nano metal is less than 20nm, intermolecular aggregation is easy to form, so that the conductivity of the nano metal material is reduced, and the uniformity of the metal particles generally cannot meet the requirement. When the particle size of the nano metal is more than 100nm, the surface active property of the nano metal is not sufficient to lower the sintering temperature much. In addition, nanoparticles can be filled in nano or micron materials with larger particles, so that the nano or micron materials form a conduction mechanism of a seepage theory, a tunneling effect theory and a field emission effect theory, and the resistivity is reduced.
After being aligned and fixed, the two welding parts are placed at the temperature of 100-300 ℃ and kept at 15min-45min, so that the nano silver or the nano silver alloy is sintered at low temperature when the two superconducting bare belts 2 are welded, and the melting point reaches the temperature of the melting point of the nano material after sintering, so that the process temperature in the subsequent packaging process is not required to be considered, the requirement of the welding process is reduced, and the preparation of the superconducting belt material is facilitated.
The solder 3 coated on the welding part of the to-be-welded superconducting bare tape 2 is less than 50 μm thick, and when the solder 3 is more than 50 μm thick, the bending performance of the superconducting tape and the resistance of the welding joint are affected.
And (3) performing fillet treatment on the welding end of the superconducting bare belt 2 to be welded so as to reduce welding stress at the joint after welding and improve the mechanical strength at the joint of the welding machine.
In the application, two superconductive bare belts 2 are used as welding bodies during welding to obtain welded bare belts; the superconducting tape is prepared by coating the metal layer 1 on the outside of the bare tape body. The present application thus differs from the prior art in the way welding is performed with finished strip.
The welding of the bare superconducting tape 2 is different from the welding of the finished tape in many ways, first, it is structurally different. As shown in fig. 1 and fig. 2, the welding of the bare superconducting tapes 2 is actually the welding between silver coatings 4 with the surface thickness of 2um-3um on the two bare superconducting tapes 2, and the bare tape body obtained after the welding needs to be coated with a metal layer 1 to form the superconducting tape. The strip welding is in fact a welding between two metal strips, which directly after welding results in the desired superconducting strip. Secondly, the two methods have different process conditions during welding. The bonding between the nanometer metal and the silver coating 4 molecules can be realized only by placing the welding parts of the two pressed and fixed superconducting bare belts 2 at the temperature of 100-300 ℃ for 15-45 min without applying pressure during the welding of the superconducting bare belts 2, so that the welding of the superconducting bare belts 2 can be finished under the conditions of low temperature and no pressure, the requirements on the process conditions are lower, and the preparation of the superconducting tapes is convenient. And the finished belt needs to apply pressure during welding, so that the requirements on the process conditions are more severe. Further, the two have different effects of obtaining a welded joint. After the two superconducting bare belts 2 are welded to obtain a bare belt body, the superconducting belt is obtained by coating the metal layer 1. Since the solder joints are coated in the metal layer 1, the solder joints are not visible, and the appearance of the superconducting tape is beautified. Meanwhile, the nano silver or the nano silver alloy is bonded with the silver coating layer 4 molecules, so that the mechanical strength of a welding joint is improved, and the strength of the welding joint is similar to that of a single superconducting strip; the thickness of the superconducting tapes at the joint is only less than 1.5 times of the thickness of a single superconducting tape. The thickness of the superconducting tape welded by the finished tape at the welding joint is 2 times larger than that of the single superconducting tape; and the mechanical strength of the welded joint is mainly determined by the strength of the welding surface, so that the strength of the welded joint is lower compared with that of a single superconducting tape.
In the application, the welding part of the two superconductive bare belts 2 which are pressed and fixed is kept at the temperature of 100-300 ℃ for 15-45 min, so that the nano metal and the molecules of the silver coating 4 are bonded. When the temperature is less than 100 ℃, the melting point of the solder 3 itself is not reached, and sintering of the solder 3 and the silver plating layer 4 cannot be achieved. When the temperature exceeds 300 ℃, the superconducting layer is easily broken, so that the performance of the superconducting tape is degraded. In addition, the welding parts of the two superconducting bare belts 2 coated with the welding flux 3 can be aligned and fixed and then placed in a fixing clamp, and then the fixing clamp is placed at the temperature of 100-300 ℃ and kept for 15-45 min. The use of the fixing jig can ensure the uniformity of the coating thickness and sintering maintaining thickness of the solder 3 to ensure the mechanical strength at the solder joint.
The process for preparing the superconducting tape comprises:
s01, performing fillet treatment on the welding end of the superconducting bare belt to be welded to reduce welding stress at the joint after welding and improve mechanical strength at the joint of the welding machine;
s02, cleaning the surface of the superconducting bare tape to be welded, and drying; in the embodiment, the surfaces of the two superconducting bare belts can be cleaned by using alcohol or phosphoric acid solution so as to keep the welding position clean and improve the mechanical strength of the welding joint;
s1, coating solder on the welding part of the to-be-welded superconducting bare tape, wherein the solder is coated on the surface of a silver-plated layer of the superconducting bare tape; the solder comprises nano metal and has volume resistivity of 10-8Omega m magnitude and below; the thermal conductivity of the solder is greater than or equal to 70W/K.m; the particle size of the nano particles in the solder is 20-100 nm; the concentration of the nano metal in the solder is more than or equal to 85 percent;
s2, aligning and fixing the two welding parts, and then keeping the two welding parts at the temperature of 100-300 ℃ for 15-45 min to obtain a bare belt body;
and S3, coating a metal layer on the outer part of the bare belt body.
The above-mentioned embodiments are merely preferred embodiments for fully illustrating the present invention, and the scope of the present invention is not limited thereto. Equivalent substitutes or changes made by the technical personnel in the technical field on the basis of the utility model are all within the protection scope of the utility model. The protection scope of the present invention is subject to the claims.
Claims (6)
1. A superconducting tape is characterized by comprising at least two superconducting bare tapes, wherein the surfaces of the superconducting bare tapes are covered with silver coatings; the welding parts adjacent to the superconducting bare belt are attached, the adjacent silver coating layers are oppositely arranged, and the welding parts adjacent to the superconducting bare belt are welded through welding flux; the solder comprises nano metal, and the volume resistivity of the solder is 10-8Omega m magnitude and below; the free surface of the superconducting bare belt is coated with a metal layer.
2. The superconducting tape according to claim 1, wherein the nano metal has a particle size of 20 to 100 nm.
3. The superconducting tape of claim 1, wherein the solder has a thermal conductivity of 70W/K-m or more.
4. The superconducting tape of claim 1, wherein the solder is coated on the surface of the silver plating layer and the solder is coated to a thickness of less than 50 μm.
5. The superconducting tape of claim 1, wherein the welded ends of the welded bare tapes are rounded.
6. The superconducting tape of claim 1, wherein the nano-metal comprises nano-silver, a nano-silver alloy, nano-gold, or a nano-gold alloy.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922245127.0U CN211455985U (en) | 2019-12-13 | 2019-12-13 | Superconducting tape |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922245127.0U CN211455985U (en) | 2019-12-13 | 2019-12-13 | Superconducting tape |
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| CN211455985U true CN211455985U (en) | 2020-09-08 |
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| CN201922245127.0U Active CN211455985U (en) | 2019-12-13 | 2019-12-13 | Superconducting tape |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112992420A (en) * | 2021-02-23 | 2021-06-18 | 东北大学 | Double-core superconducting tape with superconducting film packaged inwards |
| CN114221191A (en) * | 2022-01-06 | 2022-03-22 | 中国科学院电工研究所 | Connecting method of second-generation high-temperature superconducting tapes and connecting superconducting wire |
-
2019
- 2019-12-13 CN CN201922245127.0U patent/CN211455985U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112992420A (en) * | 2021-02-23 | 2021-06-18 | 东北大学 | Double-core superconducting tape with superconducting film packaged inwards |
| CN114221191A (en) * | 2022-01-06 | 2022-03-22 | 中国科学院电工研究所 | Connecting method of second-generation high-temperature superconducting tapes and connecting superconducting wire |
| CN114221191B (en) * | 2022-01-06 | 2023-12-01 | 中国科学院电工研究所 | Connection method of second-generation high-temperature superconducting tape and connection superconducting wire |
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