JPH04259203A - Manufacture of ceramic superconductor coil - Google Patents

Abstract

PURPOSE:To prevent defective insulation by a method wherein a composite linear body is formed by arranging a metal outside a ceramic superconductor, a layer composed of a metallic oxide is formed on the surface of the composite linear body, the composite linear body is molded to a desired-shape coil molded form, and the coil molded form is thermally treated. CONSTITUTION:The mixture of primary raw-material powder is calcinated, and the calcinated body is crushed to obtain the calcinated powder of a ceramic superconductor. The inside of a pipe made of Ag is filled with the calcinated powder, thus manufacturing a composite billet. The composite billet is swaging- worked, and rolling-worked, thus manufacturing a tape-shaped composite wire rod. The surface of the tape-shaped composite wire rod is coated with the paste of a metallic oxide, and the paste is dried and a binder in said paste is removed. The tape-shaped composite wire rod is wound on said Ag pipe spirally in thirty turns. Said spiral body is thermally treated, and said calcinated powder in said composite wire rod is changed into the ceramic superconductor.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a coil using a ceramic superconductor.

0002

[Prior art] Y-Ba-Cu-O system, Bi-Sr-C
Ceramic superconductors such as a-Cu-O series and Tl-Ba-Ca-Cu-O series have Tc (critical temperature) exceeding liquid nitrogen temperature, and are therefore expected to be applied to various high-temperature applications. In particular, molding such ceramic superconductors into various shapes is being considered. For example, when a ceramic superconductor is applied to a coil that generates a magnetic field, a ceramic superconducting wire body produced by a metal sheath method is conventionally used.

[0003] For example, a composite billet is prepared by filling a raw material for a ceramic superconductor into a metal pipe serving as a sheath material, and then this composite billet is finished into a desired shape and dimensions by plastic working, and then, As shown in FIG. 1, a ceramic superconducting wire body 10 is wound into a coil shape, and then this coiled body is subjected to heat treatment for reacting the ceramic superconductor raw material to the ceramic superconductor to obtain a ceramic superconductor coil 1. It is something.

[0004] As the metal material used for the metal sheath, Ag, Ag alloy, Cu, Cu alloy, etc. are used. Among these, Ag and Ag alloys, which have excellent oxygen permeability, are particularly preferred.

Conventional means such as extrusion, rolling, drawing, and swaging are used for plastic working. By this plastic working, it is possible to easily manufacture a material having a circular, elliptical, rectangular, or tape-shaped cross section.

In a so-called pancake-shaped coil as shown in FIG. 1, it is necessary that each layer be electrically insulated. Various methods can be considered for this purpose, but in general, the ceramic superconductor is used together with an insulating member made of Al2O3, epoxy resin, etc., which can be used in a cryogenic coolant such as liquid nitrogen or liquid helium in which the ceramic superconductor acts. is molded into a coil shape.

[0007]

However, in the conventional method as described above, since an insulating member is interposed between each layer, the overall size of the coil becomes large. Further, when using, for example, Al2 O3 fibers or non-woven fabric as an insulating member, if they are wound into a coil together with a ceramic superconductor, the Al2 O3 fibers or non-woven fabric may be displaced, resulting in poor insulation.

The present invention has been made in view of the above points, and provides a ceramic superconductor coil that exhibits excellent superconductor properties and can easily obtain a ceramic superconductor coil that can prevent insulation defects. The purpose is to provide a manufacturing method for.

[0009]

[Means for Solving the Problems] The present invention forms a composite linear body by arranging metal on the outside of a ceramic superconductor,
Next, a layer made of a metal oxide is formed on the surface of the composite linear body, then the composite linear body is molded into a coil molded body of a desired shape, and then a ceramic superconductor is formed into the coil molded body. Provided is a method for manufacturing a ceramic superconductor coil, which is characterized by subjecting a ceramic superconductor coil to heat treatment.

[0010] As the ceramic superconductor used here, any of Bi-based, Y-based, Tl-based, etc. can be used.

[0011] As the metal material used for the metal sheath, Ag, Ag alloy, Cu, Cu alloy, etc. are used. Among these, Ag and Ag alloys, which have excellent oxygen permeability, are particularly preferred.

[0012] The method for producing the composite linear body is a conventionally used method, for example, first, primary raw material powder such as oxides, carbonates, etc. of constituent elements of the ceramic superconductor is mixed with a desired composition of the ceramic superconductor. Mix thoroughly. Next, this mixed powder is calcined to obtain a calcined body. Next, the obtained calcined body is pulverized to obtain a ceramic superconductor raw material. Alternatively, the mixed powder may be heated and melted and then rapidly cooled to obtain a calcined mass, which may be crushed to be used as a ceramic superconductor raw material. The ceramic superconductor raw material obtained in this way is used as it is, or after being compacted and sintered, it is filled into a metal pipe to form a composite billet. Then, this composite billet is plastically worked into a desired shape and desired dimensions to produce a composite linear body.

[0013] For plastic working, conventional processing means such as extrusion, rolling, drawing, swaging, etc. are used depending on the shape of the linear body, tape-like body, etc. Therefore, by plastic working, the cross-sectional shape of the ceramic superconducting conductor can be made into any shape such as circular, elliptical, polygonal, rectangular, or tape-shaped.

[0014] The metals of the metal oxide include Al, Cu, Mg, Zr, Ti, Y, and
Ca or an alloy thereof can be used.

Methods for forming a metal oxide layer on the surface of a composite linear body include, for example, a method in which a metal oxide is made into a paste and is applied directly to the surface of the composite linear body and then dried; A method of plating and depositing metal on the surface of a linear body and oxidizing this metal, and a method in which a double pipe is used as a metal sheath in advance to produce a composite linear body,
Examples include a method in which only the outer tube is oxidized.

[0016] The thickness of the metal oxide is not particularly limited, but
In order to make it easier to mold the composite linear body into a coil shape,
It is preferable that it be as thin as possible, on the order of several hundred μm.

[0017] When forming the linear body into a coil shape, it is preferable to attach terminals 12 for supplying current to both ends of the composite linear body 10 in advance, as shown in FIG.

[0018] The temperature of the heat treatment for converting the ceramic superconductor raw material into a ceramic superconductor is selected depending on the type of the ceramic superconductor raw material.

[0019]

[Operation] The method for manufacturing a ceramic superconductor coil of the present invention involves forming a composite linear body by placing metal on the outside of a ceramic superconductor, and forming a layer made of metal oxide on the surface of the composite linear body. The composite linear body is formed into a coil molded body of a desired shape, and the coil molded body is subjected to heat treatment to form a ceramic superconductor.

Therefore, the metal oxide layer formed on the composite linear body reliably insulates each layer of the ceramic superconductor coil. Therefore, it is possible to prevent insulation failure due to displacement of the insulating member that occurs in a ceramic superconducting coil in which an insulating member is simply interposed between each layer of the ceramic superconducting coil.

Furthermore, since the metal oxide layer is extremely thin, ranging from several μm to several hundred μm in thickness, it contributes to miniaturization of the ceramic superconductor coil.

[0022]

[Examples] Examples of the present invention will be explained in detail below.

Examples 1 to 7 Bi2O3, SrCO3, CaCO3, CuO
The primary raw material powders were blended in a molar ratio of 2:2:1:2 and thoroughly mixed. This mixture was pre-sintered in the atmosphere at 800° C. for 20 hours, and the obtained pre-sintered body was pulverized to obtain a pre-sintered powder of a ceramic superconductor.

[0024] Next, this calcined powder was divided into seven pieces with an outer diameter of 7 mm.
Seven composite billets were prepared by filling each Ag pipe with a diameter of 4 mm and an inner diameter of 4 mm. These seven composite billets were each swaged and then rolled to produce a tape-shaped composite wire with a width of about 5 mm and a thickness of 0.15 mm.

[0025] On the surface of each of these seven tape-shaped composite wires, a metal oxide paste prepared in advance as shown in Table 1 was applied to a thickness of 0.05 mm, and then dried to remove the binder in the paste. did.

Each of these seven tape-shaped composite wires was wound into a coil with 30 turns on an Ag pipe having an outer diameter of 5 mmφ and an inner diameter of 4 mmφ. Current terminals were attached in advance to both ends of each tape-shaped composite wire. After that, each coiled body was heated at 850°C and 50°C in the atmosphere.
Ceramic superconductor coils (Examples 1 to 7) of the present invention were produced by subjecting the pre-sintered powder in the composite wire to a ceramic superconductor by subjecting it to heat treatment for several hours.

Example 8 A composite billet obtained in the same manner as in Example 1 was drawn to produce a linear body having an outer diameter of 0.5 mmφ and a round cross section. The surface of this round linear body is electroplated with Cu to a thickness of 0.
It was coated to a thickness of 2 mm. Next, this round linear body was oxidized at 600° C. in the atmosphere to convert Cu on the surface to CuO to form a CuO layer.

Next, this was placed in a ceramic jig for 30 minutes.
Wrapped with a turn. Note that current terminals were attached in advance to both ends of each tape-shaped composite wire. After that, each coiled body was heated at 850°C for 5 minutes in the atmosphere.
A ceramic superconductor coil (Example 8) of the present invention was produced by performing heat treatment for 0 hours to convert the pre-sintered powder in the composite wire into a ceramic superconductor.

Example 9 A composite billet obtained in the same manner as in Example 1 was prepared with an outer diameter of 7.8 m.
mφ and inserted into an Al pipe with an inner diameter of 7.2 mmφ. This composite billet was swaged and then rolled to produce a tape-shaped composite wire with a width of about 5 mm and a thickness of 0.15 mm. This tape-shaped composite wire was heat-treated in an electric furnace controlled at 600°C to convert Al to Al2O.
3 to form an Al2O3 layer.

[0030] This tape-shaped composite wire was wound into a coil shape with 30 turns on an Ag pipe having an outer diameter of 5 mmφ and an inner diameter of 4 mmφ. Note that current terminals were attached in advance to both ends of each tape-shaped composite wire. Thereafter, each coiled body was heat-treated at 850°C for 50 hours in the atmosphere to turn the pre-sintered powder in the composite wire into a ceramic superconductor, thereby producing a ceramic superconductor coil (Example 9) of the present invention. did.

Comparative Example A tape-shaped composite wire material obtained in the same manner as in Example 1 was used together with Al2O3 as an insulating member, with an outer diameter of 5 mmφ and an inner diameter of 4 m.
It was wound into a coil with 30 turns on an mφ Ag pipe. Note that current terminals were attached in advance to both ends of each tape-shaped composite wire. Thereafter, a conventional ceramic superconductor coil (comparison) was fabricated by subjecting each coiled body to heat treatment at 850° C. for 50 hours in the atmosphere to turn the pre-sintered powder in the composite wire into a ceramic superconductor.

For the ceramic superconducting coils of Examples 1 to 9 and Comparative Example, Ic (critical current) in liquid nitrogen and liquid helium, and the respective generated magnetic fields in Ic were investigated. The results are shown in Table 1 below. In addition,
Ic was measured by immersing a ceramic superconductor coil in liquid nitrogen or liquid helium and passing a current through both terminals.

[0033]

[Table 1] As is clear from Table 1, the ceramic superconductor coils (Examples 1 to 9) obtained by the method of the present invention all have high critical current values and each generate a large magnetic field. Moreover, insulation was provided between all layers of the coil. On the other hand, the ceramic superconductor coil obtained by the conventional method (comparative example) has a low critical current value.
The magnetic field generated in each case was also small, approximately half that of the example, and poor insulation was observed at two locations in the center of the coil.

[0034]

[Effects of the Invention] As explained above, according to the method of manufacturing a ceramic superconductor coil of the present invention, it is possible to easily obtain a ceramic superconductor coil that exhibits excellent superconducting properties and can prevent insulation defects. Moreover, it can contribute to miniaturization of ceramic superconductor coils.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing a ceramic superconductor coil.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1... Ceramic superconductor coil, 10... Ceramic superconducting wire body, 12... Terminal.

Claims (1)

[Claims] 1. A composite linear body is formed by arranging a metal on the outside of a ceramic superconductor, a layer made of a metal oxide is formed on the surface of the composite linear body, and then a metal oxide layer is formed on the surface of the composite linear body. 1. A method for manufacturing a ceramic superconductor coil, comprising: molding a body into a molded body having a desired shape, and then subjecting the molded body to heat treatment to form a ceramic superconductor.