JPH09232131A - Winding spacer for oxide superconductor wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin winding spacer for oxide superconductor wire which is durable to severe heat treatment and has sufficient insulating property without losing superconductive property of the oxide superconductor wire. SOLUTION: In winding an oxide superconductor wire manufactured by a metal cladding method, a winding spacer for oxide superconductor wire which is inserted between the oxide superconductor wires and removed after heat treatment is made of a material having a melting point of not lower than 900 deg.C, a solubility limit to Ag of not more than 0.3at% at temperatures not higher than 900 deg.C, and 0.2% durability of not less than 3MPa at 900 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a winding spacer, and more particularly to a winding spacer for an oxide superconducting wire produced by a metal coating method represented by the Ag sheath method.

[0002]

2. Description of the Related Art Metal coating method (powder-in-tube method)
Since the oxide superconducting wire produced by the method is often heat-treated at a higher temperature than the wire using Nb ₃ Sn, the chemical reaction between the metal to be coated and the oxide superconductor becomes a very important problem. For example, Bi-Sr-Ca-Cu-O-based oxide superconductors have high chemical reactivity at high temperatures, so oxide superconductors react with most metals other than noble metals such as Au and Ag to form oxides. The superconducting property will deteriorate. For this reason,
Considering the reactivity with the oxide superconductor, Ag and Ag alloys or Au and Au alloys are often selected as the coating metal.

A general heat treatment for oxide superconducting wire is performed at a high heat treatment temperature of 800 to 900 ° C. and in an oxygen atmosphere. In the case of long wires, etc., if the wires are in contact with each other, they will be fused during the heat treatment. Therefore, the wires may be sparsely wound at appropriate intervals, or ceramic paper (for example, alumina paper) or ceramic fibers. Measures are taken such as inserting a heat resistant material such as a braid (for example, a braid of alumina fiber or glass fiber) as a spacer between the wire rods.

At present, products using oxide superconducting wires (for example, coils) are often manufactured by a method of winding a wire and then subjecting it to heat treatment (so-called Wind & React method). However, even in this Wind & React method, since the heat treatment is performed at a high temperature in an oxygen atmosphere, a normal organic insulating material cannot be used,
A heat resistant material such as ceramic paper or ceramic fiber braid is used as the spacer.

[0005]

However, since the heat-resistant material such as ceramic paper or ceramic fiber braid has a weak binding force to the wire, the wire is likely to be deformed by heat expansion or the winding is easily loosened during the heat treatment. It has the drawback of For example, in a Ag-sheath tape of Bi-Pb-Sr-Ca-Cu-O-based superconductor, since blistering may occur at several points of the tape wire during heat treatment, handling of the tape wire after heat treatment and superconductivity May adversely affect characteristics. Further, in the case of a wire rod or coil wound around a bobbin with a solenoid, when the bobbin is erected and heat-treated, the winding may be loosened during the heat treatment, which causes a problem that the wire rods are fused or short-circuited.

When ceramics paper is used as a heat-resistant insulating material, it has an advantage that the thickness of the insulating layer can be reduced, but after heat treatment, the ceramics paper becomes very brittle and easily falls off. It has a drawback that the wire is short-circuited. Furthermore, the mechanical strength of ceramics paper is low,
Since it is not possible to apply tension to the wire during winding before heat treatment, it is difficult to tightly wind the wire.

When the ceramic fiber braid is used as the heat-resistant insulating material, the ceramic fiber braid has a higher mechanical strength and a better insulating property than the ceramic paper, so that the wire can be wound tightly. However, since the insulating layer becomes thicker, it is not possible to increase the winding density (wire material space factor) of the coil conductor, and the coil current density necessary for generating the magnetic field is low. Have

That is, in applied products such as coils and power supply / power transmission conductors produced by the above-described Wind & React method, it is not possible to use an organic insulating material under heat treatment conditions. In practical application of the wire, a thin insulating material that can withstand severe heat treatment (high temperature treatment in oxygen atmosphere) without impairing the superconducting properties of the oxide superconducting wire and has sufficient insulating properties Or, a reinforcing material (winding spacer) is required.

Therefore, the present invention has solved the above-mentioned problems and has a thin oxide superconducting material which can withstand severe heat treatment without impairing the superconducting characteristics of the oxide superconducting wire and has sufficient insulating characteristics. It is to provide a spacer for winding a wire.

[0010]

In order to solve the above-mentioned problems, the invention according to claim 1 inserts between oxide superconducting wires when winding the oxide superconducting wires produced by a metal coating method. In addition, in the winding spacer of the oxide superconducting wire that is removed after heat treatment, the melting point is 900 ° C or higher,
Solid solubility limit for Ag at 900 ° C or lower is 0.3 at
% Or less and 0.2% proof stress at 900 ° C is 3MP
It is made of a material having characteristics a or more.

A second aspect of the present invention is the winding spacer of the oxide superconducting wire according to the first aspect, which is made of Ni or a Ni-based alloy.

The reasons for limiting the above numerical values will be described below.

The reason for limiting the melting point to 900 ° C. or higher is that if the melting point is lower than 900 ° C., the superconducting wire may melt during heat treatment.

The reason why the solid solubility limit for Ag at 900 ° C. or lower is limited to 0.3 at% or less is that when the solid solubility limit for Ag at 900 ° C. or lower is larger than 0.3 at%, the solid solubility limit for Ag as the coating metal is increased. This is because a diffusion or a chemical reaction occurs and the superconducting property is deteriorated.

0.2% proof stress at 900 ° C. is 3 MPa
The reason for limiting the above is that if the 0.2% proof stress at 900 ° C. is less than 3 MPa, the internal pressure (2
This is because the mechanical strength against (~ 3 MPa) is insufficient and the wire cannot be wound tightly.

According to the above construction, the spacer for the winding of the oxide superconducting wire has a melting point of 900 ° C. or higher and 900 ° C.
The solid solution limit to Ag in the following is 0.3 at% or less,
Moreover, since a material having a 0.2% proof stress at 900 ° C. of 3 MPa or more is used, the oxide superconducting wire can withstand severe heat treatment without impairing the superconducting characteristics, and has sufficient insulating characteristics. In addition, it is possible to obtain a thin spacer for a winding of an oxide superconducting wire.

[0017]

Embodiments of the present invention will be described below.

The winding spacer of the present invention is provided by being inserted between the oxide superconducting wires produced by the metal coating method.

As the material of the winding spacer of the present invention,
Ni or a Ni-based alloy may be used. This Ni or N
Examples of the i-based alloy include forged Ni alloys (for example, Nickel 200, Nickel 201,
Nickel 270, Duranickel301, Monel 400, Monel R-405
, Monel K-500, Monel 502, Inconel 600, Inconel
625, Inconel 671, Inconel 690, Incoloy 800, I
ncoloy 801, Incoloy 825, DS Nickel, Hastelloy B
-2, Hastelloy C-4, Hastelloy C-276, Hastelloy G
, Hastelloy G-3, Hastelloy N, Hastelloy S, Has
telloy W, Hastelloy X, etc. Solid solution Ni-based forged superalloys (eg Hastelloy B,
Hastelloy B-2, Hastelloy C, Hastelloy C-4, Hast
elloy C-276, Hastelloy N, Hastelloy S, Hastello
y W, Hastelloy X, Inconel 600, Inconel 601, In
conel 604, Inconel 617, Inconel 625, NA-224, Ni
monic 75, RA-333, etc.) Precipitation hardening Ni-based forged superalloy (eg Astroloy,
D-979, IN-100, IN-102, Incoloy 901, Inconel 706
, Inconel 718, Inconel 751, Inconel X750, M25
2, Nimonic 80A, Nimonic 90, Nimonic 95, Nimonic 1
00, Nimonic 105, Nimonic 115, Nimonic 263, Pyr
omet 860, Refractory 26, Rene´ 41, Rene´ 95
, Rene´100, Udimet 500, Udimet 520, Udimet 630,
Udimet 700, Udimet 710, Uditemp AF2-1DA, Waspaloy
Etc.) Ni-based superalloys (eg B-1900, IN-100, IN-162,
IN-731, IN-738, IN-792, IN-939, Inconel 713, Inco
nel 713LC, M-22, MAR-M 200, MAR-M 246, MAR-M 24
7, MAR-M 421, MAR-M 432, MC-102, Nimocast 75,
Nimocast 80, Nimocast 90, Nimocast 242, Nimocast
263, NX 188 (DS), Rene´ 77, Rene´ 80, Rene´10
0, TAZ-8A, TRW-NASA VI A, Udimet 500, Udimet 70
0, Udimet 710, WAZ-20 (DS), etc.

The shape of the winding spacer of the present invention may be rod-shaped, tape-shaped, sheet-shaped or the like, but is not particularly limited, and is appropriately selected depending on the shape and winding method of the oxide superconducting wire. To be done.

The lower limit of the diameter or thickness of the winding spacer of the present invention is the oxidation formed on the surface of the winding spacer under the heat treatment condition of the oxide superconducting wire (in oxygen atmosphere, 800 to 900 ° C.). The thickness of the coating reaches 10 to 15 μm, and when the diameter or thickness of the winding spacer is less than 25 μm, the entire winding spacer becomes oxidatively corroded and becomes brittle.

The upper limit of the diameter or thickness of the winding spacer is such that when a winding spacer having a diameter or thickness larger than the diameter or thickness of the oxide superconducting wire is used, oxidation during winding is used. Since the space factor of the superconducting wire is reduced, it is desirable that the diameter or the thickness is approximately the same as the diameter or thickness of the oxide superconducting wire to be heat treated.

The mechanical strength of the winding spacer of the present invention is
If it is lower than Ag, which is the surface sheath of the oxide superconducting wire, the deformation of the wire and the slack of the winding during heat treatment cannot be restricted, so at least the mechanical strength of Ag (0.2% proof stress of Ag at 900 ° C). Is about 1 MPa).

The 0.2% proof stress of the winding spacer of the present invention at 900 ° C. is 3 MPa or more because an internal pressure of 2-3 MPa may be generated in the oxide superconducting wire during the heat treatment. Is desirable.

The winding spacer of the present invention is Y-Ba-Cu-O.
System, Ln-Ba-Cu-O system (Ln is lanthanum element), Bi-Pb-Sr
-Ca-Cu-O system, Tl-Pb-Ba-Sr-Ca-Cu-O system, Hg-Ba-Sr-Ca-Cu
It is applicable to all oxide superconductors such as -O type, and its type does not matter.

Further, the winding spacer of the present invention can be applied to an oxide superconducting wire produced by a metal coating method. As a coating metal for this oxide superconducting wire,
(A) Ag or Ag alloy, (b) Ag or Ag
The outside of the alloy is coated with an Ag alloy having a different composition, another metal, an oxide, or a composite of a metal and an oxide,
(C) Inside the Ag or Ag alloy, A with different composition
g alloy, other metal, oxide, or composite in which metal and oxide are arranged, (d) Ag or Ag alloy having different composition inside Ag, other metal, oxide, or metal And (e) a composite of a metal and an oxide is arranged.
Au or Au alloy, (f) Au or Au alloy coated on the outside with an Au alloy having a different composition, another metal, an oxide, or a complex of a metal and an oxide, (g)
Au or Au alloy with different composition arranged inside Au or Au alloy, (h) Au or Au alloy with different composition inside Au or Au alloy Examples thereof include alloys, other metals, oxides, and those in which a complex of metal and oxide is arranged.

The conductor structure of the oxide superconducting wire to which the winding spacer of the present invention is applied has a single-core structure, a multi-core structure, a single-layer structure, a multi-layer structure, or a combination thereof. There is no particular limitation such as a combination or a combination with another.

The conductor shape of the oxide superconducting wire to which the winding spacer of the present invention is applied is rod-shaped, tape-shaped, pipe-shaped, or a laminated or composite of these. It is not particularly limited to.

[0029]

【Example】

(Example 1) (Bi, Pb) ₂ Sr ₂ Ca ₂ Cu prepared in advance
_{A 3} O _x oxide superconducting powder with an outer diameter of 6 mm and an inner diameter of 4 mm
After filling the g pipe, the Ag pipe was cold drawn to produce an Ag sheath rod material having an outer diameter of 1 mm. Next, this Ag sheath rod material was cold-rolled to produce an Ag sheath tape having a thickness of 0.12 mm and a width of 3 mm. Nine pieces of this Ag sheath tape having a length of about 2 m are cut out, and each Ag has an outer diameter of 30 mm and a height of 5 mm.
It was wrapped around a bobbin. At this time, in Sample 1-A, no spacer was sandwiched between the Ag bobbin and the Ag sheath tape and between the Ag sheath tape.

In Sample 1-B, alumina paper (thickness 70 μm, width 4 mm) was sandwiched as a spacer between the Ag bobbin and the Ag sheath tape and between the Ag sheath tape.

Sample 1-C was an alumina fiber braid (thickness 0.5 m) as a spacer on the outside of the Ag sheath tape.
m) and covered it.

In Sample 1-D, a Ni tape (thickness: 50 μm, width: 4 mm) was sandwiched and wound as a spacer between the Ag bobbin and the Ag sheath tape and between the Ag sheath tape.

In Sample 1-E, Inconel 601 tape (thickness: 50 μm, width: 4 mm) was inserted as a spacer between the Ag bobbin and the Ag sheath tape and between the Ag sheath tape.

In Sample 1-F, Inconel 671 tape (thickness: 50 μm, width: 4 mm) was inserted as a spacer between the Ag bobbin and the Ag sheath tape and between the Ag sheath tape.

In Sample 1-G, Inconel 718 tape (thickness: 50 μm, width: 4 mm) was inserted as a spacer between the Ag bobbin and the Ag sheath tape and between the Ag sheath tape.

Sample 1-H is Hastelloy C-276 tape (thickness 50 μm, width 4 mm) as a spacer between an Ag bobbin and an Ag sheath tape and between Ag sheath tapes.
Caught in and caught up.

In Sample 1-I, Hastelloy G tape (thickness: 50 μm, width: 4 mm) was inserted as a spacer between the Ag bobbin and the Ag sheath tape and between the Ag sheath tape.

In this way, nine pancake coils were produced. Next, the nine pancake coils were heat-treated at 840 ° C. for 20 hours in air. After that, these nine heat-treated pancake coils are rolled (Ag sheath (Bi, Pb) ₂ Sr ₂ Ca ₂ Cu ₃ O _X superconducting tape wire material is characterized in that the heat treatment and rolling are repeated. It was loosened for the purpose.

When the Ag sheath (Bi, Pb) ₂ Sr ₂ Ca ₂ Cu ₃ O _X superconducting tape wire material was unraveled, the fusion between the wire materials, the handling property, and the blistering of the wire material were evaluated. Table 1 shows the results.

[0040]

[Table 1]

As shown in Table 1, in Sample 1-A, Ag
The bobbin, the Ag sheath tape wire, and the Ag sheath tape wire could not be unraveled because they were fused together, and when they were forcibly unraveled, the Ag sheath tape wire was broken.

In Sample 1-B, part of the alumina paper was missing during the heat treatment, and the Ag sheath tape wire rods in that part were fused together. Further, when the Ag sheath tape wire rod in the fused portion was forcibly unraveled, the Ag sheath tape wire rod was bent due to a large strain. Further, blistering was observed in a part of the Ag sheath tape wire.

In Sample 1-C, since the Ag sheath tape wire was not fused with each other, the pancake coil could be easily unraveled. However, when the Ag sheath tape wire was removed from the alumina fiber braid, the Ag sheath tape wire was removed. The shape of the tape wire has largely collapsed. Further, blistering was observed in a part of the Ag sheath tape wire.

In Samples 1-D to 1-I, since the Ag sheath tape wire rods are not fused to each other, the pancake coil can be easily unraveled, and the Ag sheath tape wire rod is not blown up and is sound. It was a state. This time,
A black oxide film was formed on the surfaces of the Ni tape, Inconel 601 tape, Inconel 671 tape, Inconel 718 tape, Hastelloy C-276 tape, and Hastelloy G tape.

That is, from the experimental results of Example 1, Ni
Tape, Inconel 601 Tape, Inconel 671 Tape, In
conel 718 tape, Hastelloy C-276 tape, and Ha
By inserting the winding spacer made of stelloy G tape between the oxide superconducting tape wire rods, the oxide superconducting tape wire rods do not fuse to each other, and the oxide superconducting tape wire rod and the winding spacer do not fuse, Further, it is possible to suppress the thermal expansion of the oxide superconducting tape wire.

(Example 2) In the same manner as in Example 1, an Ag sheath (Bi, Pb) ₂ Sr ₂ Ca having a thickness of 0.12 mm and a width of 3 mm was used.
₂ Cu ₃ O _X tape was prepared. 10 pieces of this Ag sheath tape are cut out with a length of about 3 m, and each has an outer diameter of 60 m.
Two layers were wound in the form of a solenoid coil at a pitch of about 6 mm on an alumina bobbin having a diameter of m, an inner diameter of 50 mm and a height of 100 mm. At this time, in Sample 2-A, the Ag sheath tape was wound around the alumina bobbin, and no spacer was wound around the solenoid winding layer (between the first layer and the second layer) and the outer side of the second layer. .

Sample 2-B was prepared by winding an Ag sheath tape around an alumina bobbin, and using alumina paper (thickness) as a spacer on the outer side of the solenoid winding layer (between the first and second layers) and the second layer. 70 μm, width 4 mm) was sandwiched at a pitch of about 3 mm and wound.

In Sample 2-C, an Ag sheath tape covered with an alumina fiber braid (thickness 0.5 mm) as a spacer was wound around an alumina bobbin.

Sample 2-D was prepared by winding an Ag sheath tape around an alumina bobbin and using Ni tape (thickness) as a spacer on the outer side of the solenoid winding layer (between the first and second layers) and the second layer. 50μm, width 4mm) about 3
I caught it at a pitch of mm.

In Sample 2-E, an Ag sheath tape was wrapped around an alumina bobbin, and Inconel 600 tape (thickness) was used as a spacer on the outer side of the solenoid winding layer (between the first and second layers) and the second layer. 50 μm wide, 4 m wide
m) was pinched and caught at a pitch of about 3 mm.

Sample 2-F was prepared by winding an Ag sheath tape around an alumina bobbin and using Inconel 604 wire (outer) as a spacer on the outer side of the solenoid winding layer (between the first and second layers) and the second layer. (Diameter 0.1 mm) was wound at a pitch of about 0.1 mm so as to be tightly wound.

Sample 2-G was prepared by winding an Ag sheath tape around an alumina bobbin and using Inconel 617 tape (thickness) as a spacer on the outer layer between the solenoid winding (between the first and second layers) and the second layer. 50 μm wide, 4 m wide
m) was pinched and caught at a pitch of about 3 mm.

Sample 2-H was prepared by winding an Ag sheath tape around an alumina bobbin and using Hastelloy B-2 tape as a spacer on the outer side of the solenoid winding layer (between the first and second layers) and the second layer. (50 μm thickness, 4 m width
m) was pinched and caught at a pitch of about 3 mm.

Sample 2-I was obtained by winding an Ag sheath tape around an alumina bobbin and using Hastelloy N tape (thickness) as a spacer on the outer side of the solenoid winding layer (between the first layer and the second layer) and the second layer. 50 μm wide, 4 m wide
m) was pinched and caught at a pitch of about 3 mm.

In Sample 2-J, an Ag sheath tape was wrapped around an alumina bobbin, and Hastelloy N tape (thickness) was used as a spacer on the outer side of the layers (between the first layer and the second layer) and the second layer of the solenoid winding. 50 μm wide, 4 m wide
m) was pinched and caught at a pitch of about 3 mm.

In this way, 10 solenoid winding coils were produced. Next, heat treatment was carried out at 840 ° C. for 20 hours in the air with these 10 solenoid coils wound up. Then, these heat-treated 10 solenoid coils are rolled (Ag sheath (Bi, P
b) ₂ Sr ₂ Ca ₂ Cu ₃ O _X superconducting tape wire is characterized by repeated heat treatment and rolling. ) Unraveled for.

When the Ag sheath (Bi, Pb) ₂ Sr ₂ Ca ₂ Cu ₃ O _X superconducting tape wire was unraveled, the winding was loosened, the wires were fused with each other, the handling property, and the blistering of the wire were evaluated. . Table 2 shows the results.

[0058]

[Table 2]

As shown in Table 1, in Sample 2-A, the winding was slackened during the heat treatment, so that the winding drooped and the Ag sheath tape wire rods were fused to each other. A of the fused part
Forcibly unraveling the sheath tape wire, Ag
The sheath tape wire was broken. In addition, blistering was observed on a part of the Ag sheath tape wire.

In Sample 2-B, a part of the alumina paper was missing during the heat treatment and the winding was slackened, so that the winding drooped down and the Ag sheath tape wire rods in that portion were fused together. Further, when the Ag sheath tape wire rod in the fused portion was forcibly unraveled, the Ag sheath tape wire rod was bent due to a large strain. Further, blistering was observed in a part of the Ag sheath tape wire.

In the sample 2-C, the winding was slackened and drooped down, but since the Ag sheath tape wire rods were not fused to each other, the solenoid coil was easily unraveled. But,
When the Ag sheath tape wire rod was pulled out from the alumina fiber braid, the shape of the Ag sheath tape wire rod collapsed greatly. Further, blistering was observed in a part of the Ag sheath tape wire.

In Samples 2-D to 2-J, the winding was not loosened and the initial shape was maintained. Further, since the Ag sheath tape wire rods were not fused to each other, the solenoid coil could be easily unraveled, and further, the Ag sheath tape wire rod was in a healthy state without any blistering. At this time, Ni tape, Inconel 600 tape, Inconel 604
Wire, Inconel 617 tape, Hastelloy B-2 tape,
A black oxide film was formed on the surface of Hastelloy N tape and Hastelloy X tape.

That is, from the experimental results of Example 1, Ni
Tape, Inconel 600 Tape, Inconel 604 Wire, In
conel 617 tape, Hastelloy B-2 tape, Hastelloy
By inserting a winding spacer consisting of N tape and Hastelloy X tape between the oxide superconducting tape wires, the winding spacer does not loosen because the winding spacer has a large binding force. The wire rods are not fused with each other, the oxide superconducting tape wire rods and the winding spacers are not fused with each other, and furthermore, the expansion of the oxide superconducting tape wire rods can be suppressed.

(Example 3) Bi ₂ Sr ₂ prepared in advance
Ca ₁ Cu ₂ O _X oxide superconducting powder with an outer diameter of 6 mm and an inner diameter of 5 m
After filling the Ag pipe of m, the Ag pipe was cold drawn to prepare an Ag sheath rod material having an outer diameter of 1 mm. Next, this Ag sheath rod material was cold-rolled to produce an Ag sheath tape having a thickness of 0.12 mm and a width of 3 mm. Five pieces of this Ag sheath tape are cut out with a length of about 3 m, and each has an outer diameter of 30 mm and a height of 5 mm.
It was wound around a bobbin made of Ag. At this time, Sample 3-A
No spacer was inserted between the Ag bobbin and the Ag sheath tape and between the Ag sheath tape.

In Sample 3-B, alumina paper (thickness 70 μm, width 4 mm) was sandwiched between the Ag bobbin and the Ag sheath tape and between the Ag sheath tape as a spacer.

Sample 3-C is a glass fiber braid (thickness 0.5 mm) as a spacer on the outside of the Ag sheath tape.
I covered it and got involved.

Sample 3-D is Inconel 625 tape (thickness 50 μm, width 4 m) as a spacer between Ag sheath tapes.
m) was caught and caught.

Sample 3-E is a Hastelloy W tape (thickness 50 μm, width 4 m) as a spacer between Ag sheath tapes.
m) was caught and caught.

In this way, five pancake coils were produced. By then an electric furnace these five pancake coil, the Ag sheath _{Bi 2 Sr 2 Ca 1 Cu 2} O X superconducting tape, characteristic partial melting - Xu cooling heat treatment was performed in air. That is, from room temperature to 884 ° C, 300 ° C / h
The temperature is raised at a rate of r and kept at 884 ° C. for 10 minutes. Then, it is gradually cooled from 884 ° C. to 834 ° C. at a rate of 5 ° C./hr, held at 834 ° C. for 1 hr, and then cooled to room temperature.

Table 3 shows the specifications (wire length, coil inner diameter, coil outer diameter, number of turns, wire rod space factor) of these five heat-treated pancake coils.

[0071]

[Table 3]

As shown in Table 3, out of the five heat-treated pancake coils, four excluding sample 3-A had no problem in appearance. However, in Sample 3-A, Ag
It was confirmed that the sheath tape wires were fused and integrated by heat treatment and did not function as a coil. Therefore, in the subsequent experiments, except for sample 3-A, 4
This was done with book samples 3-B to 3-E.

A current lead of Ag was soldered to both ends of each of the four coils (Samples 3-B to 3-E), and voltage lead wires were attached to the coils at positions such that the distance between the voltage leads was 2 m. Soldered. Next, each coil was impregnated in an epoxy resin, which was used as a coil sample for evaluation.

For the evaluation, the critical current value (I _C ) in liquid helium (4.2 K) was measured by the usual four-terminal method. The threshold value was 1 μV / cm. In addition, the magnetic field generated at the center of the coil at this time was measured using a Hall element. Table 4 shows the measurement results.

[0075]

[Table 4]

As shown in Table 4, in Sample 3-B, a central magnetic field of 1,430 G should be generated in calculation,
The measured value was only 950G. Therefore, when the sample 3-B was disassembled and investigated, it was found that a part of the alumina paper was missing during the heat treatment or during the handling of the coil after the heat treatment, and the wires were short-circuited. In the sample 3-C, the central magnetic field (740 G) was almost as calculated.
However, it was found that a high central magnetic field cannot be generated because the space factor of the wire is small (11%).

In Samples 3-D and 3-E, the central magnetic fields (1,490G, 1,470, respectively) almost as calculated were obtained.
It was found that G) occurred, that there was no short circuit between the wire rods, and that it had secondary sufficient insulation properties.

That is, as is clear from the results of Example 3, the coil produced by the Wind & React method was
By using the winding spacer made of nel 625 tape and Hastelloy W tape, it has withstands severe heat treatment (high temperature and oxygen atmosphere), has sufficient insulation, and
An oxide superconducting wire having a high space factor for the wire can be obtained.

Example 4 In order to evaluate the mechanical strength of the winding spacer, an experiment was conducted using the following seven types of spacers as samples.

Sample 4-A: Alumina paper (thickness 70 μm
m, width 10 mm) Sample 4-B: Alumina fiber braid (thickness 0.5 mm,
Width 10 mm) Sample 4-C: Ni tape (thickness 50 μm, width 10 mm) Sample 4-D: Ni tape (thickness 20 μm, width 10 mm) Sample 4-E: Inconel 690 tape (thickness 50 μm, width 1)
0 mm) Sample 4-F: Inconel 690 tape (thickness 20 μm, width 1
0 mm) Sample 4-G: Inconel 690 wire (outer diameter 0.3 mm) Each sample (Samples 4-A to 4-G) was subjected to the same heat treatment as in Example 3, and with respect to the sample after the heat treatment. A tensile test was performed to measure 0.2% proof stress (yield stress). Here, the reason why 0.2% proof stress is selected as the evaluation is 0.
This is because the 2% proof stress value and the strain amount at which the superconducting properties of the oxide superconducting wire begin to deteriorate are almost the same. That is, 0.
The spacer having a large 2% proof stress is suitable as a reinforcing material for the oxide superconducting wire. Table 5 shows the measurement results of the tensile test.

[0081]

[Table 5]

As shown in Table 5, in the sample 4-A, the spacer was extremely brittle due to the heat treatment.
The% yield strength could not be measured. In the sample 4-B, since the alumina fiber braid was very stretchable, the 0.2% proof stress value could not be measured at a small displacement amount (corresponding to the strain amount).

In samples 4-C to 4-G, a black oxide film was formed on the surface of all samples, but sample 4
In -D and Sample 4-F, since the thickness of the tape was thin, the entire tape was oxidatively corroded and thus extremely brittle, and the 0.2% proof stress value could not be measured. Sample 4
In -C, 4-E, and 4-G, high 0.2% proof stress values were obtained, and it was found that they have sufficient strength as a reinforcing material for the oxide superconducting wire.

That is, as is clear from the results of Example 4, the Ni tape, the Inconel 690 tape, and the Incone
l 690 wire winding spacer can withstand severe heat treatment (high temperature and oxygen atmosphere), has sufficient mechanical strength, and is suitable as a reinforcing material for oxide superconducting wire. In particular, it is suitable for a coil winding spacer manufactured by the Wind & React method.

(Example 5) Bi ₂ Sr ₂ prepared in advance
Ca ₁ Cu ₂ O _X oxide superconducting powder with an outer diameter of 6 mm and an inner diameter of 5 m
m Ag-0.015 wt% Mg-0.015 wt% Ni alloy pipe was filled, and then the Ag pipe was cold drawn to produce an Ag sheath rod material having an outer diameter of 1 mm. Next, this Ag sheath rod material was subjected to cold rolling to prepare an Ag-Mg-Ni alloy sheath tape having a thickness of 0.12 mm and a width of 3 mm. Five pieces of this Ag-Mg-Ni alloy sheath tape are cut out with a length of about 3 m, and each has an outer diameter of 30 mm and a height of 5 m.
m Ag bobbin. At this time, sample 5-A
Alumina paper (thickness 70 μm, width 4 mm) as a spacer was sandwiched between the Ag-Mg-Ni alloy sheath tapes and wound.

Sample 5-B is Inconel 706 tape (thickness 50 μm) as a spacer between Ag-Mg-Ni alloy sheath tapes.
m, width 4 mm).

Sample 5-C was an Inconel 751 tape (thickness: 50 μm) as a spacer between Ag-Mg-Ni alloy sheath tapes.
m, width 4 mm).

Sample 5-D is a Hastelloy S tape (thickness: 50 μm) as a spacer between Ag-Mg-Ni alloy sheath tapes.
m, width 4 mm).

Sample 5-E is Hastelloy C-4 tape (50 μm in thickness) as a spacer between Ag-Mg-Ni alloy sheath tapes.
m, width 4 mm).

In this way, five pancake coils were produced. Subjected to gradual cooling heat treatment in air - then by an electric furnace of these five pancake coil, the Ag-Mg-Ni alloy sheath _{Bi 2 Sr 2 Ca 1 Cu 2} O X superconducting tape, characteristic partial melting It was That is, from room temperature to 884 ° C is 30
The temperature is raised at a rate of 0 ° C./hr and kept at 884 ° C. for 10 minutes. After that, from 884 ℃ to 834 ℃, 5 ℃ / hr
After slowly cooling at a rate of 1 hour and holding at 834 ° C. for 1 hour, the furnace is cooled to room temperature.

Table 6 shows the specifications (wire length, coil inner diameter, coil outer diameter, number of turns, wire rod space factor) of these five heat-treated pancake coils.

[0092]

[Table 6]

Next, the same experiments as in Example 3 were conducted on the pancake coils of Samples 5-A to 5-E, and the critical current value and the central magnetic field were measured.

In Sample 5-A, short-circuiting occurred between the wire rods in the coil, and the central magnetic field was generated only for about half of the calculated value. It was found that in Samples 5-B to 5-E, the central magnetic field was generated almost according to the calculated value, there was no short circuit between the wires, and the secondary wires had sufficient insulation.

That is, as is clear from the results of Example 5, the Inco
With a winding spacer made of nel 706 tape, Inconel 751 tape, Hastelloy S tape, and Hastelloy C-4 tape, it can withstand severe heat treatment (high temperature and oxygen atmosphere) and has sufficient insulation. In addition, an oxide superconducting wire having a high wire space factor can be obtained.

Example 6 Tl ₂ (Ba,
Sr) ₂ Ca ₂ Cu ₃ O _X oxide superconducting powder was filled in an Au-5wt% Pd pipe having an outer diameter of 6 mm and an inner diameter of 4 mm, and then A
The u-5 wt% Pd pipe was cold drawn to prepare an Au-Pd alloy sheath rod material having an outer diameter of 1 mm. next,
This Au-Pd alloy sheath rod material was cold-rolled to produce an Au-Pd alloy sheath tape having a thickness of 0.12 mm and a width of 3 mm. Six pieces of this Au-Pd alloy sheath tape are cut out with a length of about 3 m, and each has an outer diameter of 60 mm and an inner diameter of 50 m.
Two layers were wound around a bobbin made of alumina having a height of 100 mm and a height of 100 mm in a solenoid coil shape at a pitch of about 6 mm. This time,
Sample 6-A was prepared by winding an Au-Pd alloy sheath tape around an alumina bobbin and using alumina paper (thickness) as a spacer outside the solenoid winding layer (between the first and second layers) and the second layer. 70μm, width 4mm) about 3m
I caught it at a pitch of m.

Sample 6-B was prepared by winding an Au-Pd alloy sheath tape around an alumina bobbin and using a Ni wire as a spacer between the solenoid winding layers (between the first and second layers) and the second layer. (Outer diameter 0.1 mm) was wound at a pitch of about 0.1 mm so as to be tightly wound.

In Sample 6-C, an Au-Pd alloy sheath tape was wrapped around an alumina bobbin, and Inconel X750 was used as a spacer between the solenoid winding layers (between the first and second layers) and the second layer. Wire (outer diameter 0.1 mm)
Was wound at a pitch of about 0.1 mm so as to be tightly wound.

Sample 6-D was obtained by winding an Au-Pd alloy sheath tape around an alumina bobbin and using Hastelloy B as a spacer on the outer side between the solenoid winding layers (between the first and second layers) and the second layer. Wire (outer diameter 0.1 mm)
Was wound at a pitch of about 0.1 mm so as to be tightly wound.

Sample 6-E was prepared by winding an Au-Pd alloy sheath tape around an alumina bobbin and using Hastelloy C as a spacer on the outer side of the solenoid winding layer (between the first and second layers) and the second layer. Wire (outer diameter 0.1 mm)
Was wound at a pitch of about 0.1 mm so as to be tightly wound.

Sample 6-F was prepared by winding an Au-Pd alloy sheath tape around an alumina bobbin, and using Hastelloy G as a spacer between the solenoid winding layers (between the first and second layers) and the second layer. -3 wire (outer diameter 0.1m
m) was wound at a pitch of about 0.1 mm so as to be tightly wound.

In this way, six solenoid wound coils were produced. Next, heat treatment was performed at 870 ° C. for 10 hours in an oxygen atmosphere in a state where these six solenoid winding coils were erected. Then, these heat-treated 6 solenoid coils are rolled (Au-Pd alloy sheath).
The Tl ₂ (Ba, Sr) ₂ Ca ₂ Cu ₃ O _X superconducting tape wire is characterized in that the heat treatment and rolling are repeated. ) Unraveled for.

As a result, in Sample 6-A, a part of the alumina paper was missing and the winding was slackened during the heat treatment, so that the winding drooped and the Au-Pd alloy sheath tape wire rods were fused together. It was When the Au-Pd alloy sheath tape wire in the fused portion was forcibly disentangled, a large strain was applied to the Au-Pd alloy sheath tape wire and it was bent.

In Samples 6-B to 6-F, the winding was not loosened, and the initial shape was maintained. Also, since there is no fusion of Au-Pd alloy sheath tape wires, the solenoid coil could be easily unraveled. At this time, Ni wire, Inconel X750 wire, Hastelloy B wire, Hast
A black oxide film was formed on the surface of elloy C wire and Hastelloy G-3 wire.

That is, from the experimental results of Example 6, Ni
Wire, Inconel X750 Wire, Hastelloy B Wire, Ha
By inserting a winding spacer consisting of stelloy C wire and Hastelloy G-3 wire between the oxide superconducting tape wires, the winding spacer has a large binding force and the winding does not loosen The superconducting tape wire rods do not fuse, and the oxide superconducting tape wire rod and the winding spacer do not fuse.

In the present embodiment, the two types of winding of the winding spacer are used: solenoid winding and pancake winding, but the winding method is not limited to this.

By using the winding spacer of the present invention in an oxide superconducting wire produced by a metal coating method, it can be applied to a coil or a power feeding / power transmitting conductor.

[0108]

In summary, according to the present invention, the following excellent effects are exhibited.

(1) The winding spacer of the present invention is
By inserting between oxide superconducting wires produced by a metal coating method typified by the sheath method, a wire oxide is not deformed during heat treatment, and a sound oxide superconducting wire without winding slack is obtained. You can

(2) By using the winding spacer of the present invention in the Wind & React method, a high-performance coil or a power-feeding / power-transmitting conductor which does not deteriorate in superconducting properties and has excellent mechanical strength can be obtained. Obtainable.

Claims (2)

[Claims] 1. A winding spacer for an oxide superconducting wire, which is inserted between the oxide superconducting wires and withdrawn after heat treatment when winding an oxide superconducting wire produced by a metal coating method. , Melting point above 900 ° C, 900
A spacer for a winding wire of an oxide superconducting wire, which is made of a material having a solid solution limit of 0.3 at% or less with respect to Ag at ℃ or below and a 0.2% proof stress at 900 ℃ of at least 3 MPa. . 2. A Ni or Ni-based alloy as claimed in claim 1.
A spacer for a winding of the above described oxide superconducting wire.