JPH0225006A - Manufacture of superconducting coil using explosive compression method - Google Patents

Abstract

PURPOSE:To prevent the deformation and wire disconnection of the title superconducting coil and to obtain the coil having excellent high critical current density by a method wherein a superconducting-oxide-powder-filled Ag composite wire is used for the coil, the coil is inserted into a cylindrical container together with a pressure medium, and the coil is explosion-compressed using an explosive. CONSTITUTION:Even number of large diameter cylinders 1 and small diameter cylinders 2, having different diameters respectively, are provided on the manufacturing device of a superconducting coil, said even number of cylinders 1 and 2 are vertically erected concentrically, and as a result, a plurality of gaps are formed between the inner surface and the outer surface of the cylinders 1 and 2. An explosive 6, a superconducting-oxide- filled coil 3, on which a superconducting-oxide-powder-filled Ag composite wire is wound, and a pressure medium 4 are filled up alternately into the above-mentioned plurality of gaps, and the explosive 6 is arranged on the inside of the cylinder having the smallest diameter and on the outside of the cylinder having the largest diameter among the even number of cylinders 1 and 2. By exploding said explosive 6 using a triggering device 7, the coil 3 is explosion-compressed and it is brought into the state of high density, and the high density coil is heat-treated in the atmospheric air or in an oxygen atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a superconducting coil having a high critical current density using an explosive compression method.

[Prior Art] In general, a compound having a perovskite structure consisting of a rare earth element containing Y (hereinafter, this element will be referred to as R), an alkaline earth metal, Cu, and oxygen (hereinafter, this compound will be referred to as R).
It is known that 77 beads that can be cooled with liquid nitrogen exhibit a superconducting phenomenon.

As a method for manufacturing a superconducting coil using the above R-based oxide powder, first, R2O3 powder, alkaline earth metal carbonate powder, and CuO powder, all of which have an average particle size of 10 mm or less, are used as raw material powders. Prepared, these raw material powders are blended into a predetermined composition, mixed, and fired at a temperature of 850 to 950°C in the air or oxygen atmosphere to produce an R-based oxide having a perovskite structure. The R-based oxide is ground to an average particle size of l〇- or less to obtain an R-based oxide powder, this R-based oxide powder is filled into an Ag tube, and both ends of the Ag tube filled with the R-based oxide powder are sealed. Thereafter, wire drawing processing such as swaging processing, groove rolling processing, or die processing is performed to obtain an R-type oxide powder-filled Ag composite wire with a diameter of 5 mm or less, and the above-mentioned R-type oxide powder-filled A
G composite wire is wound to form a coil of Ag composite wire filled with R-type oxide powder (hereinafter referred to as R-type oxide-filled coil), and the R-type oxide-filled coil is placed in air or oxygen atmosphere at a temperature of 900 to 950. R-type oxide superconducting coils were produced by heat treatment at ℃.

Furthermore, in recent years, Bi-Ca-Sr-Cu-0-based oxides (hereinafter referred to as Bi-based oxides) and TΩ-Ca
It has been discovered that -Ba-Cu-0-based oxides (hereinafter referred to as Tl-based oxides) exhibit superconductivity at temperatures above 77' which can be cooled with liquid nitrogen.

The above-mentioned Bi-based oxide is produced by first preparing raw material powders such as BiO powder, CaC0 powder, S r COa powder, and CuO powder, blending and mixing these raw material powders in a predetermined ratio, and heating the mixed powder at a temperature near It is produced by firing at a temperature in the range of 00 to 800°C in the atmosphere for 4 to 12 hours. Furthermore, the above Tg-based oxide includes raw material powder such as TΩ O powder, Ca COa powder, B a C
O3 powder and CuO powder are prepared, these raw material powders are blended in a predetermined ratio, mixed, and this mixed powder is heated to a temperature of 6
It is produced by performing a firing treatment at a temperature within the range of 00 to 700°C and maintained in the atmosphere for 4 to 12 hours.

The Bi-based oxide or Tl-based oxide thus created is pulverized into Bii-based oxide powder or Tp-based oxide powder with an average particle size of 5 knots or less. After filling both ends of the Bi-based oxide powder product term Ag tube or the Tl-based oxide powder-filled Ag tube, they are wire-drawn to form a wire with a diameter of 5 mm or less. Bii
An oxide powder-filled Ag composite wire or a Tl-based oxide powder-filled Ag composite wire is used, and these Ag composite wires are wound to form a coil of BI-based oxide powder-filled Ag composite wire (hereinafter referred to as a BI-based oxide-filled coil) or Tg-based oxide powder-filled Ag composite wire. A coil of Ag composite wire filled with a Bi-based oxide (hereinafter referred to as a Tfi-based oxide-filled coil) is formed by heat-treating the Bi-based oxide-filled coil or the Tj7-based oxide-filled coil in air or an oxygen atmosphere. They were manufacturing oxide superconducting coils or 1g-based oxide superconducting coils. The heat treatment temperature of the Bi-based oxide superconducting coil is 830-87
0°C, and the heat treatment temperature of the Tj7-based oxide superconducting coil is 880 to 920°C.

[Problem to be solved by the invention]

However, the critical current density of the R-based oxide superconducting coil obtained by the above conventional manufacturing method is as high as 700.
A/cd, and B manufactured by conventional manufacturing methods
The critical current density of a J-based oxide superconducting coil is at most 1
00A/cJL, and furthermore, the 1g-based oxide superconducting coil obtained by the conventional manufacturing method has a maximum of 180A/cJL.
It has a critical current density of only about c.

At this level of critical current density, it cannot be used as a practical superconducting coil, so R-based oxide-filled coils,
Attempts have also been made to increase the packing density of superconducting oxide powder by applying explosive compression to a coil filled with Bl-based oxide or a coil filled with 1g-based oxide, thereby increasing the critical current density. When directly exploded and compressed,
The above-mentioned coil is deformed and loses its shape, and breaks occur at various places, resulting in the problem that it cannot be put to practical use as a coil to be incorporated into various industrial electrical equipment.

[Means to solve the problem]

Therefore, the present inventors conducted research to obtain a superconducting coil having an even higher critical current density that can be put to practical use, and as a result, the above R-based oxide filled coil, B
A superconducting oxide-filled coil such as an i-type oxide-filled coil or a 1g-type oxide-filled coil is inserted together with a pressure medium into a gap composed of a large-diameter cylinder and a small-diameter cylinder, and the outer side of the large-diameter cylinder and the small-diameter cylinder are The inventors have found that when explosives are simultaneously detonated inside the cylinder, the superconducting oxide-filled coil is densified without being deformed or cut, and a superconducting coil with an extremely high critical current density can be obtained. It is.

The present invention has been made based on this knowledge, and the method for manufacturing a superconducting coil by the explosive compression method of the present invention will be specifically explained below with reference to the drawings.

FIG. 1 is a cross-sectional elevational view showing the superconducting oxide-filled coil set in order to explosively compress the superconducting oxide-filled coil by the explosive compression method, and FIG. 2 is a cross-sectional elevational view showing the superconducting oxide-filled coil set. 1 is a cross-sectional plan view taken along the line ■-■ in FIG. 1 in a state where it is set for explosive compression.

1 and 2, 1 is a large diameter cylinder, 2 is a small diameter cylinder, 3 is a superconducting oxide filled coil, 4 is a pressure medium, and 5 is a small diameter cylinder.
is a cardboard container, 6 is an explosive, 7 is a detonator, and 8 is a lid.

The large-diameter cylinder 1 and the small-diameter cylinder 2 are preferably made of steel, a metal such as /1, or an alloy thereof, but are not limited to the above metals and alloys, and may be made of plastic, tempered glass, ceramics, cardboard, etc. It is also possible to use

The pressure medium 7 may be a fluid, but the average particle size is 1 to 1.00.
Powders that are difficult to solidify under explosive compression at 0 tm are preferred.

These powders include, for example, AN OSiOMgO
, ZrO2 and other 23′ 2° oxide powders and composite oxide powders of these oxides, AD
Nitride powder such as H, T I N, S ta Nt, T I B 2, ZrB2. Boride powder such as MoB, carbide powder such as SiC, Tic, ZrC, WC,
Silicide powders such as MoSi2, Ti51, Zr51, etc., and solid solution powders such as carbonitride powders and carbonoboride powders are used.

Setting the superconducting oxide filled coil as shown in FIGS. 1 and 2 is performed as follows.

First, a cardboard container 5 is prepared, and a large-diameter cylinder 1 and a small-diameter cylinder 2 are vertically installed concentrically in the cardboard container 5, and a gap is formed between the large-diameter cylinder 1 and the small-diameter cylinder 2. A pressure medium 4 and a superconducting oxide filled coil 3 are inserted into the gap. After the pressure medium 4 is charged, it is preferable to vibrate it and fill it to a sufficiently high density.

A pressure medium 4 and a superconducting oxide filled coil 3 are placed in the above gap.
After charging, the ring-shaped lid 8 is put on.

It is preferable that the lid 8 is fixed to the large-diameter cylinder 1 and the small-diameter cylinder 2 with adhesive, adhesive tape, or the like.

After the lid 8 is closed, the cardboard container 5 is filled with an explosive 6, and is detonated by the detonator 7 to explode and compress the superconducting oxide-filled coil to high density without cutting or deforming it. By taking out the densified superconducting oxide-filled coil and heat-treating it in air or oxygen atmosphere, a superconducting coil with particularly excellent critical current density can be manufactured.

In Figures 1 and 2 above, two cylinders with different diameters (
Although one superconducting oxide-filled coil is explosively compressed using a large-diameter cylinder and a small-diameter cylinder, the present invention is not limited to this.
is a positive integer), it is possible to simultaneously explosively compress n superconducting oxide-filled coils with different diameters.

〔Example〕

Next, the present invention will be explained in more detail based on examples.

Example 1 As raw material powders, yttrium oxide (Y2O2) powder with an average particle size of 6 mm, barium carbonate (B a COa ) powder with an average particle size of 6 mm, and copper oxide (Cub) powder with an average particle size of 6 mm. These powders were prepared in a molar ratio of YO: BaCO3: CuO-1/2: 2:
3, and this mixed powder was calcined in the air at a temperature of 900°C for 12 hours to obtain a perovskite powder having a composition of Y Ba 2 Cu a Or. Compounds having a structure (hereinafter referred to as Y-based oxides) were produced, and these compounds were further ground to produce Y-based oxide powders having an average particle size of lJum.

Inner diameter: 20 mm x wall thickness = 1.5
An Ag tube with a diameter of 200 ya mm x length was filled with the material, and the filled Ag tube was swaged and then grooved to produce a Y-based oxide-filled Ag composite wire with a diameter of 2 m.

The above Y-based oxide-filled Agm composite wire is wound to have an inner diameter of 60
Two Y-based oxide-filled coils were prepared, one of which was inserted as shown in FIGS. 1 and 2, and explosive compression was performed.

The above explosive compression was carried out as follows.

First, a cardboard container 5 made of cardboard with a thickness of 0.5 am is prepared, and inside the cardboard container 5 there is an outer diameter near 5+a.
mX inner diameter near 0 + uX height: 110mm steel pipe large diameter cylinder 1, and outer diameter: 45nm x inner diameter: 40m + sX height: 110
Small-diameter cylinders 3 made of steel pipes 3 mm in diameter were vertically installed concentrically.

In the gap formed by the large-diameter steel pipe cylinder 1 and the small-diameter steel pipe cylinder 2, the Y-based oxide filled coil 3 with an inner diameter of 6h+m and the compressed SiC powder medium 4 with an average particle size of 2 μs are filled.
was charged and further vibrated to fill the SiC powder so that it was sufficiently dense, and then M8 was applied. The lid 8 was fixed to the steel pipe large diameter cylinder 1 and the steel pipe small diameter cylinder 2 with adhesive.

Next, the cardboard container 5 is filled with explosives 6, and the explosives 6 are placed outside the large-diameter cylinder 1 made of steel pipe and inside the small-diameter cylinder 2 made of steel pipe, and detonated by the detonator 7.
The system oxide-filled coil 3 was explosively compressed and densified.

Both the Y-type oxide-filled coil that has been densified by explosive compression and the Y-type oxide-filled coil that is not explosively compressed are heat-treated in an oxygen atmosphere at a temperature of 920°C for 24 hours to achieve explosive compression. A Y-based oxide superconducting coil (Example 1) subjected to detonation and a Y-based oxide superconducting coil not subjected to explosive compression (Comparative Example 1) were fabricated, and the superconducting properties of these 28 types of superconducting coils were measured. It is shown in Table 1.

Example 2 As the raw material powder, B with an average particle size of 10 um or less was used.
i O powder, Ca CO3 powder, S r COs powder, and CuO powder are prepared, and these powders are mixed with Bi2O3
Powder: 53.4%, Ca COa powder: 11.5%
, S r C03 powder: 1B, 9% and CuO powder: 18.2% (by weight), mixed, and this mixed powder was placed in the atmosphere at a temperature of 800°C.
, a Bi-based oxide was created by firing under conditions of holding for 12 hours, and then the Bi-based oxide obtained by this firing was pulverized to obtain a Bi-based oxide powder with an average particle size of 5 uI. Manufactured.

The above Bi-based oxide powder was mixed with inner diameter: 20+++m x wall thickness:
A 1.5 mm x length: 200 mm Ag tube was filled, and the filled Ag tube was swaged and then groove rolled to produce a Bi-based oxide-filled Ag composite wire with a diameter of 2'+m.

The above Bi-based oxide-filled Ag composite wire was wound to form a wire with an inner diameter of 26 mm.
Two Bi-based oxide-filled coils of 011Il were prepared, one of them was set as shown in FIGS. 1 and 2, and after being explosively compressed under exactly the same conditions as in Example 1, it was taken out and the above With a Bi-based oxide-filled coil that is not subjected to explosive compression, in an oxygen atmosphere, temperature: 850°C, 15
A Bi-based oxide superconducting coil (Example 2) that was heat-treated under time-holding conditions and subjected to explosive compression (Example 2) and a Bi-based oxide superconducting coil that was not subjected to explosive compression (Comparative Example 2) were fabricated, and the superconductivity of these superconducting coils was The properties were measured and the results are shown in Table 1.

Example 3 As a raw material powder, each has an average particle size of 10 m or less, 1 g
203 powder, Ca CO3 powder, B a COa powder, and CuO powder were prepared, and these powders were divided into Ti10 powder: 35.4%, Ca COa powder: 15.5%,
B a COs powder: 30.6% and CuO powder:
Blend and mix to have a composition of 18.5% (or more by weight), and add this mixed powder in an oxygen atmosphere at a temperature of 80
The Tl-based oxide powder was prepared by firing at 0°C and maintained for 10 hours, and the Tl-based oxide obtained by the firing was pulverized to form a Tl-based oxide with an average particle size of 5 pores. A powder was produced.

Inner diameter: 20m + sx wall thickness: 1
．． A 5 mm x length: 200 mm Ag tube was filled, and the filled Ag tinib was swaged and then groove rolled to form a T, 11-based oxide-filled Ag tube with a diameter of 2 fins.
A composite wire was produced.

The above Tg-based oxide-filled V4Ag q composite wire was wound to make two 1g-based oxide-filled coils with an inner diameter of 60 mm, and one of them was inserted into the device shown in Fig. 1, which was exactly the same as in Example 1. After being subjected to explosive compression under the following conditions, the Tg series was taken out and heat treated in an oxygen atmosphere at a temperature of 900°C for 3 hours, together with the Tfi-based oxide-filled coil that was not subjected to the above explosive compression. An oxide superconducting coil (Example 3) and a Tfi-based oxide superconducting coil not subjected to explosive compression (Comparative Example 3) were produced, and the superconducting properties of these superconducting coils were measured. The results are shown in Table 1.

In Examples 1 to 3, two cylinders, a large-diameter cylinder and a small-diameter cylinder, are used, but the number of cylinders is not limited to the above example, and any number of cylinders with different diameters can be used. Multiple superconducting oxide-filled coils can be explosively compressed simultaneously using an even number of cylinders to densify them.

〔Effect of the invention〕

When a superconducting oxide powder-filled Ag composite wire is made into a coil, the coil is charged into a cylindrical container with a pressure medium, and explosively compressed, the explosively compressed coil can be explosively compressed without deforming or breaking the coil. Example 1 of the present invention obtained by heat treating in air or oxygen atmosphere
~3 superconducting coils are Comparative Example 1~ which is not subjected to explosive compression
The superconducting coil obtained by the manufacturing method of the present invention has a particularly superior critical current density, and has a critical current density high enough for practical use, compared to the superconducting coil of No. 3.
It greatly contributes to the development of industry. Furthermore, according to this invention, it is possible to explosively compress a large number of coils with different diameters at the same time, so it is possible to supply a large number of excellent superconducting coils at low cost, resulting in excellent economical effects. .

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional elevational view showing a superconducting oxide-filled coil set between cylinders of different diameters for explosive compression, and FIG. 2 is a cross-sectional view taken along line nn in FIG. 1. 1: Large diameter cylinder 2: Small diameter cylinder 3: Superconducting oxide filled coil 4: Pressure medium 5: Cardboard container 6: Explosive
7: Detonator 8: Lid application amount Mitsubishi Metals Corporation

Claims (7)

[Claims] (1) Prepare an even number of cylinders with different diameters, and form a plurality of voids composed of the inner and outer surfaces of the even number of cylinders by vertically standing the even number of cylinders concentrically, and Explosives and superconducting oxide powder filled Ag
A coil obtained by winding a composite wire (hereinafter referred to as a coil) and a pressure medium are alternately filled, and the inside of the cylinder with the smallest diameter among the even number of cylinders and the outside of the cylinder with the largest diameter are filled alternately. Explosives are placed in the coil, the coil is explosively compressed and densified by detonating the explosive, and the coil densified by the explosive compression is heat treated in air or an oxygen atmosphere. A method for manufacturing superconducting coils by compression. (2) Prepare a large-diameter cylinder and a small-diameter cylinder having an outer diameter smaller than the inner diameter of the large-diameter cylinder, stand the large-diameter cylinder vertically, and place the small-diameter cylinder vertically in the center of the large-diameter cylinder. and filling the void formed by the inner surface of the large-diameter cylinder and the outer surface of the small-diameter cylinder with the coil and pressure medium, and placing an explosive on the outside of the large-diameter cylinder and the inside of the small-diameter cylinder, The coil is explosively compressed and densified by detonating an explosive from the outside of the cylinder and the inside of the small diameter cylinder, and the coil densified by the explosive compression is heat-treated in air or an oxygen atmosphere. A method for manufacturing a superconducting coil by the explosive compression method according to claim 1. (3) The above pressure medium has an average particle size of 1 to 1,000 μm.
The method for manufacturing a superconducting coil by the explosive compression method according to claim 1, wherein the powder is difficult to solidify by explosive compression. (4) The superconducting oxide powder contains a rare earth element containing Y,
3. The method for producing a superconducting coil by an explosive compression method according to claim 1 or 2, wherein the powder is a compound powder having a perovskite structure consisting of an alkaline earth metal, Cu, and oxygen. (5) The superconducting oxide powder is Bi-Ca-Sr-C
3. The method for producing a superconducting coil by an explosive compression method according to claim 1 or 2, wherein the u-O based oxide powder is used. (6) The superconducting oxide powder is Tl-Ca-Ba-C
3. The method for producing a superconducting coil by an explosive compression method according to claim 1 or 2, wherein the u-O based oxide powder is used. (7) The method of manufacturing a superconducting coil by an explosive compression method according to claim 1, wherein the pressure medium is a fluid.