JP2573961B2 - Superconducting wire manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a superconducting magnet coil and a superconducting wire used for power transfer, and more particularly to a superconducting material using an oxide superconductor as a superconductor.

"Prior art" In recent years, the critical temperature (Tc) at which the transition from the normal conducting state to the superconducting state has a high value equal to or higher than the liquid nitrogen temperature has been made.
So-called AB-Cu-O system such as O system (where A is Y, L
a, Ce, Yb, Sc, Er, etc. Periodic Table III
Represents an alkaline earth metal element such as Ba, Sr, etc.), ABC
Various oxide superconductors such as u-OX (where X represents a halogen element such as F and Cl) are being discovered.
These oxide-based superconductors have higher critical temperatures than conventional alloy-based or intermetallic compound-based superconductors, and some exhibit superconductivity at liquid nitrogen temperature or higher. Have been.

"Problems to be Solved by the Invention" However, these oxide-based superconductors that are currently obtained are extremely poor in workability, and are extruded or reduced in diameter to produce long wires. Even trying to get
There is a problem that it is difficult to obtain a long wire rod because troubles such as disconnection are likely to occur.

[Object of the Invention] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method capable of producing a long superconducting wire having an extremely high oxide-based critical temperature.

"Means for Solving the Problems" The present invention manufactures a superconducting wire as follows. That is, the outer peripheral portion of the core wire is coated with an oxide superconductor, the core wire is subjected to a heat treatment by immersing the core wire in a molten metal, and then the core wire is pulled out of the molten metal, and the The molten metal adhered to the outer peripheral portion is cooled and solidified to form a metal coating layer on the outer peripheral portion.

`` Function '' The superconductor provided on the outer periphery of the core wire is sintered and fixed to the core wire by the heat of the molten metal, and a metal coating layer is formed on the outer periphery of the superconductor, so that a long superconducting wire can be manufactured. Become.

Embodiment An embodiment of the present invention will be described below with reference to FIG. FIG. 1 shows an example of production for producing a superconducting wire by the method of the present invention. First, prior to the description of the embodiment, the manufacturing apparatus shown in FIG. 1 will be described.

In the figure, reference numeral 1 denotes a powder supply unit. Powder supply unit 1
Has a cylindrical shape, and is configured to extrude the powder A to the front end side by a screw (not shown) arranged inside. Holes 2 and 3 are formed at the tip of the powder supply unit 1 and open on the upper and lower surfaces thereof, so that the core wire B can be inserted therein. A molding die 4 having an axis oriented vertically is provided at the tip of the powder supply unit 1.
Is attached. The molding die 4 is a cylindrical one made of ceramics, and is for molding the powder A supplied from the powder supply unit 1 into a cylindrical shape.

A heating furnace 5 is arranged above the forming die 4. The heating furnace 5 heats the formed powder A so that the powder A
For hardening to a certain extent. A crucible 6 is disposed above the heating furnace 5. Crucible 6
A through-hole 7 is formed in the center of the bottom of, and the powder A is inserted into the through-hole 7. Also, the through hole 7
A seal member 8 is attached to the outer edge of the. The seal member 8 prevents the molten metal C in the crucible 6 from leaking from a gap between the through hole 7 and the powder A.

A cover 9 is attached to the upper end opening of the crucible 6, and the inside is filled with an inert gas. Note that reference numeral 10 in the figure is a through hole for inserting the superconducting wire D. Further, a heating furnace 11 is arranged on the outer peripheral side of the crucible 6. The heating furnace 11 includes a crucible 6
The metal charged therein is melted to form a molten metal C.

Next, a method of manufacturing the superconducting wire D using the above-described manufacturing apparatus will be described. In this example, a silver wire is used as the core wire B and silver is used as the metal used as the melt C, and Y-Ba-Cu-
An O-based superconducting wire D is manufactured.

First, a silver ingot is charged into the crucible 6 and heated in a heating furnace.
The ingot is melted by step 11 to obtain a molten metal C. In this case, a dummy material is inserted into the through hole 7 so that the molten metal C does not flow out of the through hole 7 of the crucible 6. On the other hand, core B
Is inserted into the forming die 4 so that the upper end thereof coincides with the upper end surface of the forming die 4, and the powder of the Y—Ba—Cu—O-based superconductor is filled in the powder supply unit 1. in this case,
A high viscosity binder is added to powder A to make powder A into a paste.

This superconductor powder A is composed of Y ₂ O ₃ powder, BaO powder, and C
The powder obtained by uniformly mixing the uO powder at a predetermined ratio and then performing a heat treatment is used. This heat treatment condition is 600 ~ 1100 ℃
For about one to several tens of hours. When heat treatment is performed on the mixed powder obtained by mixing the above-mentioned raw material powders, it is preferable that the mixed powder is compacted into a compact, and the compact is subjected to a heat treatment and then subjected to a pulverizing treatment. The atmosphere during the heat treatment is preferably an oxidizing atmosphere such as a mixed gas of an oxygen gas and an inert gas such as an argon gas, or a mixed gas containing a halogen gas in the mixed gas. In addition, the raw material of the Y-Ba-Cu-O-based superconductor is not limited to the oxide of each element, and may be, for example, a carbonate, a chloride, a fluoride, a bromide, a nitrate, an oxalate, or the like of each element. Can also be used.

Next, the screw of the powder supply unit 1 is rotated to turn the powder A
Is supplied into the molding die 4. Then, the powder A is pushed upward inside the forming die 4 and is formed into a cylindrical shape on the outer peripheral portion of the core wire B. Then, the core wire B is moved upward together with the powder A at the same time when the powder A exits from the molding die 4. Next, when the powder A reaches the heating furnace 5, the powder A is heated to harden the powder A to some extent. Next, the powder A is inserted into the crucible 6 from the through hole 7 and immersed in the molten metal C. At this time, the dummy material is raised together with the powder A. Here, since the powder A is baked and hardened, its deformation, loss of the surface layer, and the like are prevented, and the liquid tightness between the powder A and the sealing member 8 is ensured. Then, add powder A to the molten metal temperature (about 1100
(° C.) for several tens minutes to several hours, and the superconductor E is fixed to the surface of the core material B by sintering.

Next, the superconductor E is lifted up from the molten metal C. Then, the molten metal adheres to the outer peripheral portion of the pulled-up superconductor E with a constant film thickness. Then, the adhered molten metal is gradually cooled and solidified by the ambient temperature in the cover 9,
A superconducting wire D is obtained by forming a metal coating layer F. The coating layer F secures the strength of the superconducting wire D and becomes a current conductor when the superconducting state shifts from the superconducting state to the normal conducting state for some reason during use in the superconducting state or when the superconductor E is cut off, This is to prevent various accidents caused by interruption of the current.

At this time, the ambient temperature in the cover 9 and the superconductor E
It is possible to appropriately set the pulling speed of the superconductor E from a state in which the powder A is simply sintered to a condition such that the structure of the superconductor E becomes a single crystal. The inside of the cover 9 is desirably adjusted to a predetermined temperature by a temperature adjusting mechanism so that an appropriate slow cooling temperature can be obtained. Thus, the superconducting wire D is continuously pulled up to obtain a long superconducting wire D.

The superconducting wire D thus obtained exhibited a critical temperature of 90 to 95K, and had good superconductivity. And
According to the above manufacturing method, since the powder A is formed on the outer peripheral portion of the core wire B by the forming die 4, it is possible to manufacture the superconducting wire D having an arbitrary wire diameter by appropriately selecting the inner diameter of the forming die 4. is there. Further, since the core wire B is provided inside the powder A and the metal coating layer F is formed on the outer peripheral portion of the superconductor E, the mechanical strength is secured. Therefore, it is possible to manufacture an extremely long superconducting wire D without cutting it during the handling. In addition, since a series of processes of forming the powder A, heating, and forming the coating layer F are continuously performed, the superconducting wire D can be efficiently manufactured.

Note that, in the above embodiment, Y was used as the IIIa group metal element, and Ba was used as the alkaline earth metal element, but instead of Y, La, Ce, Pr, Nd, Pm, Eu, Gd, Tb, Dy, Ho, Sm, E
Periodic Table III such as r, Tm, Tb, Lu, Sc etc.One or more metal elements selected from Group a metal elements may be used, instead of Ba, Sr, Be, Mg, Ca, Ra etc. One or more metal elements selected from the above alkaline earth metal elements may be used.

Further, the material of the core wire B is not limited to silver, and for example, a noble metal wire such as copper, gold, and platinum, a piano wire,
Stainless steel wire, ceramic fiber, carbon fiber, etc. may be used. Further, in the above embodiment, the superconducting wire D is drawn upward, but may be drawn downward. In this case, the heat treatment of the powder A by the heating furnace 5 is unnecessary.

(Production Example) A superconducting wire including a Y-Ba-Cu-O-based superconductor was produced based on the method of the present invention.

A silver wire having a diameter of 100 μm was used as a core wire of the superconducting wire, and silver was used as a material of a molten metal to be a coating layer of the superconducting wire. The superconductor powder A includes Y ₂ O ₃ and Ba.
O and CuO powder were uniformly mixed at a ratio of Y: Ba: Cu = 1: 2: 3 (molar ratio). Heat treatment for an hour, then 0.5μ
A material obtained by mixing a PVA-based paste with the powder obtained by pulverizing to a size of about m to 5 μm and kneading it into a paste was used.

Using these materials, a superconducting wire was manufactured by an apparatus having the same configuration as that shown in FIG. The manufacturing conditions at this time are as follows: the inner diameter of the molding die 4 is 1 μm, the moving speed of the core wire B and the powder A is 1 m / hr, and the heating temperature of the powder A by the heating furnace 5 is 1 μm.
000 ° C., the temperature of the molten metal C was 1100 ° C., and the dimension from the liquid level of the molten metal C to the upper end of the cover 9 was 100 cm.

As a result, a 400 μm thick Y-Ba-C
A superconducting wire D in which a u-O-based superconductor E is formed and a silver coating layer F having a thickness of 1 mm is formed on the outer periphery of the superconductor E
Could be manufactured continuously.

As a result of measuring the critical temperature (Tc) of the superconducting wire D manufactured as described above, Tc = 90 to 95K and excellent superconducting characteristics were exhibited.

[Effects of the Invention] As described above, in the method for manufacturing a superconducting wire according to the present invention, the outer periphery of the core wire is covered with an oxide-based superconductor, and the core wire is immersed in a molten metal to form the superconductor. The superconductor is sintered and fixed to the surface of the core wire by applying heat treatment, and then the core wire is pulled out of the molten metal, and a metal coating layer is formed on the outer periphery of the superconductor. Can be manufactured without causing any trouble such as cutting.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a manufacturing apparatus for carrying out an example of a method for manufacturing a superconducting wire according to the present invention. A: powder, B: core wire, C: molten metal, D: superconducting wire, E: superconductor, F: coating layer.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masayuki Tan 1-5-1, Kiba, Koto-ku, Tokyo Fujikura Electric Wire Co., Ltd. (72) Inventor Hiroshi Yamanouchi 1-5-1, Kiba, Koto-ku, Tokyo Fujikura Electric Wire (56) References JP-A-63-259926 (JP, A)

Claims (2)

(57) [Claims] An outer peripheral portion of a core wire is coated with an oxide superconductor, and the core wire is immersed in a molten metal to perform a heat treatment on the superconductor, and then the core wire is drawn out of the molten metal. A method for producing a superconducting wire, comprising cooling and solidifying a molten metal adhered to an outer peripheral portion of a superconductor to form a metal coating layer on the outer peripheral portion. 2. A method for manufacturing a superconducting wire according to claim 1, wherein a gradual cooling process is performed on a portion of said core wire pulled up from the molten metal.