JPH01133306A - Oxide superconducting coil - Google Patents

Abstract

PURPOSE:To make it possible to form a coil shaped conductive path even if there is no plasticity in an oxide superconductor and an electrically insulating layer, by forming it such that a coil element alternates with an electrically insulating layer and as an laminating substance in which coil elements are spirally adjacent to each other by a conductive material filled in a slit in the electrically insulating layer through the electrically insulating layer. CONSTITUTION:An electrically insulating layer 4 and a coil element 3 are alternately laminated using the coil element 3 serving as a molding 1 of an oxide superconductor with a silver layer 2 formed and an aluminum sintered body as an electrically insulating layer. When they are laminated, it is arranged that the right end part of a slit 5a of a coil element 3a positioned above the electrically insulating layer 4a is adjacent to the left end part of a slit 5b of a coil element 3b positioned beneath it through the electrically insulating layer 4a. After the lamination, silver 7 is filled in the slit of each electrically insulating layer 4a to connect, the coil elements by the silver. After a while, the whole is covered with an epoxy resin 8 to be integrated and then, a superconductive coil 9 is provided.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention relates to a superconducting coil using an oxide superconductor formed into a ring shape having slits.

(Prior Art) In recent years, it has been announced that layered perovskite-type oxides based on Ba-La-Cu-0 may have a high critical temperature, and since then, research on oxide superconductors has been carried out in various places. (Z, Phys, B Condensed Mat
ter64, 189-193 (1986)), among which defective perovskite type (LnBa Cu O type) with oxygen defects represented by Y-Ha-Cu-0 system (
δ represents oxygen defect, 231-δ is usually 1 or less, Ln is Y, La, Sc, Nd, Sl
l, Eu, Gd, 0■, ■0, Er, Tn, 'i
'b and at least one element selected from Lu, B
Oxide superconductors, in which a can be partially replaced with S, etc., are attracting attention as very promising materials because they exhibit a critical temperature of 90°C or higher, which is higher than liquid nitrogen (Phys,
Rev, Lett, Vol, 58 No. 9,908
-910).

By the way, various types of coils have been studied for alloy-based or intermetallic compound-based superconductors, and they have already been put into practical use in NMR and rotating electric machines, but the oxide superconductors mentioned above are brittle crystalline. Since it is an oxide and has poor flexibility, it is difficult to obtain a wire or tape with good flexibility.

In addition, this oxide superconductor is weak against mechanical stress,
If the wire is distorted beyond a certain value, the superconducting properties will deteriorate or disappear, making it difficult to obtain a desired current density when winding the wire, making it extremely difficult to apply it to coils.

(Problems to be Solved by the Invention) As described above, it is difficult to obtain a wire with excellent flexibility using an oxide superconductor and to obtain a desired current density during winding. Manufacturing coils using oxide superconductors has been extremely difficult.

The present invention was made to solve these problems, and an object of the present invention is to provide an oxide superconductor coil free from the above problems.

[Structure of the Invention] (Means for Solving the Problems) That is, the oxide superconductor coil of the present invention is formed into a ring shape having a stabilizing material layer on at least both sides and having slits extending in the radial direction. A plurality of coil elements made of an oxide superconductor are laminated with an electrical insulating layer interposed therebetween, and the coil elements are electrically connected in a spiral manner through the electrical insulating layer, and these are connected by an electrically insulating reinforcing material. It is characterized by being integrated.

Although various oxide superconductors can be used in the present invention, the use of a perovskite-type oxide superconductor containing a rare earth element, which has a high critical temperature, has a particularly large practical effect.

The oxide superconductor containing a rare earth element and having a perovskite structure may be one that can realize a superconducting state, such as LnBa2Cu3O7-.

System〈δ represents an oxygen defect and is usually a number of 1 or less, Ln is Y,
La, Sc, Nd5Si, Eu, Gd, D
Defect perovskite type, 5r having oxygen defects such as y,
Examples include oxides having a perovskite type in a broad sense, such as a layered perovskite type such as -La-Cu-0 type. Rare earth elements are also broadly defined, and include Sc, Y, and E.
Y-Ba-C as a representative system including the u system
In addition to the u-0 series, Y can be changed to Eu, Dy, Ho, Er,
System substituted with rare earth elements such as Tn, Yb, Lu, etc., 5C-
Examples include Ba-Ctl-0 system, 5r-La-Cu-0 system, and systems in which S' is replaced with Ba or Ca.

The oxide superconductor used in the present invention is manufactured, for example, as shown below.

First, the constituent elements of the perovskite oxide superconductor, such as Y, Ba, and Cu, are thoroughly mixed. When mixing, Y
Oxides such as O-CuO can be used as raw materials, and compounds such as carbonates, nitrates, and hydroxides that are converted to oxides after firing may also be used as these oxides. The elements constituting the perovskite oxide superconductor are basically mixed in a stoichiometric composition, but oxalate etc. obtained by coprecipitation method etc. may be used.
There is no problem even if there is a slight deviation due to manufacturing conditions, etc. For example, in the Y-Ba-Cu-0 system, the standard composition is Ba 2 not and Cu 3 layer 01 for Y f mol, but in practice, Y For 1 mol, Ba 2±0.
611101, Cu. A deviation of about 3±0.2 mol is not a problem.

After mixing the above-mentioned raw materials, they are calcined and pulverized into a desired shape, and then fired at about 850 to 980°C. Calcination is not necessarily necessary; it is preferable that the calcination and firing be performed in an oxygen-containing atmosphere where sufficient oxygen can be supplied. After firing into a desired shape, it is heat-treated in an oxygen-containing atmosphere to impart superconducting properties. The above heat treatment is usually performed at 600° C. or lower while slowly cooling.

The oxide superconductor thus obtained has oxygen defects δ
Oxygen-deficient perovskite structure (LnBa2C
u3O7. (δ is usually 1 or less)).

Incidentally, Ba can be replaced with at least one of S and Ca, and furthermore, a part of Cu can be replaced with Ti, V, Cr, and Hn.
, Fe, C01N1, Zn, etc. can also be substituted.

The amount of substitution can be set as appropriate within a range that does not reduce the superconducting properties, but too much substitution will reduce the superconducting properties, so it is set to 80no1% or less, and more practically 20no1 or less.

In addition, the stabilizing material used in the present invention includes: (1) Current bypass when the superconducting state of the oxide superconductor is destroyed for some reason and a local normal conducting part is created; (2) Local current bypass that occurs in the case of Because it is required to have a cooling effect to quickly dissipate heat generated by heat, materials with excellent electrical and thermal conductivity and large specific heat, such as copper, silver, gold, or their compounds, should be used. is preferable, and the stabilizing material layer may be provided only on the upper and lower surfaces of the ring-shaped molded product, but in order to improve the bypass effect, it may be provided on other sides of the upper and lower surfaces of the molded product. Ceramics such as alumina and magnesia, or electrically insulating polymeric compounds such as epoxy resin and other synthetic resins can be used. As a reinforcing material to integrate the laminate of the coil element and the electrical insulating layer as a whole, an electrically insulating adhesive polymer compound such as epoxy resin or other synthetic resin, or an electrically insulating material can be used. A jig or container consisting of the following can be used.

The oxide superconductor coil of the present invention is manufactured using the above-mentioned materials, for example, by the following method.

First, the oxide superconductor is ground into oxide superconductor powder using a known means such as a ball mill, and then compression molded into a ring shape having slits extending in the radial direction using a pressure press or the like. The molded product is fired at 850-980° C. for 1-50 hours in an oxygen-containing atmosphere. After baking, 6
The superconducting properties are improved by slowly cooling the temperature below 00°C at a rate of about 1°C/min.

After slow cooling, the surface of the molded product is coated with a stabilizing material.

For coating, plating methods such as electroplating and electroless plating, vapor deposition methods such as ion blating, sputtering, and vacuum evaporation methods, thermal spraying methods, and the like can be used.

In this way, m layers of high-quality coil elements and electrical insulator layers are alternately formed. The shape of the electrical insulator layer is preferably the same as that of the coil elements, but any shape may be used as long as it has a slit for connecting the coil elements and is sufficiently shaped to insulate other parts. It may be.

When laminating, after lamination, the slits in the electrical insulator layer are filled with a normal conductive metal such as copper or silver, a normal conductive substance such as a normally conductive polymer compound such as polyacetylene or polypyrrole, an oxide superconductor, or an oxide by heat treatment. When filled with a substance that becomes a superconductor, adjacent coil elements are connected in a spiral manner via an electrical insulating layer.

After lamination, the above-mentioned double-conductor material is placed in the slit of the electrical insulator layer.
The coil elements are connected by filling with an oxide superconductor or a substance that becomes an oxide superconductor through heat treatment, and then the whole is coated with an electrically insulating adhesive polymer compound to form a coil element and an electrically insulating layer. to integrate. Alternatively, a hole may be bored through the entire structure and the entire structure may be integrated using a jig made of an electrically insulating material.
The laminate may be integrated as a whole by tightly accommodating the laminate in a container made of an electrically insulating material.

In addition, when connecting between coil elements, if an oxide superconductor or a substance that becomes an oxide superconductor by heat treatment is filled, heat treatment is performed as necessary after filling.

In addition, when using a refrigerant, if necessary,
Oxide Iti! Small holes may be formed in the conductor coil to improve cooling efficiency.

In order to obtain the oxide fl conductor coil of the present invention, a ring-shaped molded product made of an oxide superconductor is fired,
The slow cooling process can be carried out even after the molded product is coated with a stabilizing material to form a coil element. Also, the coil element and the electrical insulating layer are laminated, and the slits of the electrical insulating material are filled with a normal conducting substance or an oxide superconducting material. Alternatively, the material may be filled with a substance that becomes an oxide B conductor through heat treatment. In these cases, various materials can be selected for the stabilizing material, the electrical insulating layer, and the material for connecting between the coil elements, depending on the differences in thermal conditions caused by different manufacturing methods.

(Function) In the oxide superconductor coil of the present invention, the coil elements and the electrical insulating layers are arranged alternately and adjacent to each other via the electrical insulating layer due to the conductive material filled in the slits in the electrical insulating layer. Since the coil elements are formed as a laminate with spirally connected coil elements, a coil-shaped conductive path is formed even if the oxide superconductor and the electrical insulator layer are not visible.

In addition, since the coil element is coated with a stabilizing material, even if the superconducting state of the oxide superconductor is destroyed for some reason and a localized normal conductive area is created, the stabilizing material will still function as a current bypass. In addition, localized heat generation is quickly dissipated to prevent propagation of the normal conductive portion, so damage to the coil can be avoided. Furthermore, since the entire structure is integrated with a polymer compound, jig, or container, the coil will not be damaged due to stress generated toward the inside or outside of the coil when electricity is applied! ! This improves the stability of the coil.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

Example First, YO powder 0.5 molX, BaCO3 powder 2
After thoroughly mixing 101% CuO powder and 31101% CuO powder, and baking this mixture in the air at 900°C for 12 hours,
The fired product was ground in a ball mill to obtain an oxide superconductor powder. Next, this oxide superconductor powder was crushed into powders with an outer diameter of 30 mm and an inner diameter of 1 mm using a pressure press, as shown in Figure 1. (Inn, compression molded into a ring-shaped molded product 1 having a thickness of 0.1111 and having a slit 1a with a width of 11III extending in the radial direction at one location.The molded product 1 was fired at 980° C. for 24 hours in an oxygen-containing atmosphere. After that, reduce the temperature below 600℃ by 1℃/
Superconducting by slow cooling at a rate of 1 minute! Improve your sexuality and then
The upper and lower surfaces of the molded product 1 are coated with silver using the ion blating method, and as shown in FIG. Ta.

Also, it has the same shape as coil element 3 and the slit width is 5n.
An alumina sintered body of n was used as an electrical insulator layer, and electrical insulators M4 and coil elements 3 were alternately laminated as shown in FIG. When stacking, the right edge of the slit 5a of the coil element 3a located above the electrical insulator layer 4a and the left edge of the slit 5b of the coil element 3b located below it via the electrical insulator 7114a, They were arranged adjacent to each other through the slit 6a of the electrical insulator layer 4a. After lamination, silver 7 is filled into the slit of each electrical insulator layer to connect each coil element with silver 7, and then the whole is coated with epoxy resin 8 to be integrated, forming an oxide superconductor coil 9. I got it.

The critical current density of this oxide superconductor coil is 200
A/aa, critical temperature was 90.

In the oxide superconductor coil of the present invention, in order to integrate the laminate of the coil element and the electrical insulator layer, a hole is drilled through the oxide superconductor coil 10 as shown in FIG. The oxide superconductor coil 10 may be fixed with a jig 11 made of an insulating material, and small holes 12 for cooling may be formed in the oxide superconductor coil 10 as necessary to increase cooling efficiency. In FIG. 4, the same members as in FIG. 3 are given the same reference numerals as in FIG. 3.

[Effects of the Invention] As explained above, according to the present invention, it is difficult to obtain a wire rod that has excellent flexibility and can obtain a desired current density during winding. Using,
A superconducting coil can be obtained.

[Brief explanation of the drawing]

1 to 3 are diagrams showing an example of the procedure for obtaining an oxide superconductor coil of the present invention, in which FIG. 1 is a perspective view of a ring-shaped molded product made of an oxide superconductor, and FIG. 3 is a partially cutaway view of a coil element, and FIG. 3 is a partially cutaway view of an oxide superconductor coil. Further, FIG. 4 is a partially cutaway view showing one method for integrating the coil element and the electrical insulating layer. 1... Ring-shaped molded product 1a of oxide superconductor... Slit in the molded product 2... Silver layer 3...・・Coil element 4・・・・・・
... Electrical insulator layers 5a, 5b ... Coil element slit 6a ...
...Slit 7 in the electrical insulator layer...
Silver 8...Epoxy resin 9.10...Oxide superconductor coil 11...Jig Applicant: Toshiba Corporation Patent attorney Satoshi Suyama - No. Figure 2 Figure 3

Claims (7)

[Claims] (1) A plurality of coil elements made of a ring-shaped oxide superconductor having stabilizing material layers on at least both sides and slits extending in the radial direction are laminated with an electrical insulator layer interposed therebetween, and An oxide superconductor coil characterized in that the coil elements are electrically connected in a spiral manner through an electrically insulating layer and are integrated by an electrically insulating reinforcing material. (2) The oxide superconductor coil according to claim 1, wherein the stabilizing material layer is made of copper, silver, gold, or a compound thereof. (3) The oxide superconductor according to claim 1 or 2, wherein the electrical connection is made by a normal conducting substance or an oxide superconductor filled in the slit of the electrical insulator. coil. (4) The oxide superconductor according to any one of claims 1 to 3, wherein the reinforcing material is an electrically insulating adhesive polymer compound, a jig, or a container. coil. (5) The oxide superconductor according to any one of claims 1 to 4, wherein the oxide superconductor is a perovskite-type oxide superconductor containing a rare earth element. coil. (6) The oxide superconductor contains Ln element (Ln is at least one element selected from rare earth elements), Ba and C
The oxide superconductor coil according to any one of claims 1 to 5, characterized in that it contains u in an atomic ratio of substantially 1:2:3. (7) The oxide superconductor is LnBa_2Cu_3O_7
The oxide superconductor coil according to any one of claims 1 to 6, characterized in that it has an oxygen-deficient perovskite structure represented by _-_δ (δ represents an oxygen defect).