JPH07120582B2 - Manufacturing method of superconducting coil by explosive compression method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a superconducting coil having a high critical current density using an explosive compression method.

[Conventional technology]

Generally, a compound having a perovskite structure composed of a rare earth element containing Y (hereinafter, this element is represented by R), an alkaline earth metal, Cu and oxygen (hereinafter, this compound is referred to as an R-based oxide) is a liquid nitrogen. It is known to exhibit superconductivity at 77 ° K, where it can be cooled.

As a method for producing a superconducting coil using the above R-based oxide powder, first, as raw material powder, R ₂ O ₃ powder having an average particle diameter of 10 μm or less, carbonate powder of alkaline earth metal, and CuO A powder is prepared, these raw material powders are mixed in a predetermined composition, mixed, and fired at a temperature of 850 to 950 ° C. in the air or an oxygen atmosphere to produce an R-based oxide having a perovskite structure. The R-based oxide is crushed to have an average particle size of 10 μm or less to form R-based oxide powder, and the R-based oxide powder is filled in an Ag tube, and both ends of the R-based oxide powder-filled Ag tube are sealed. After that, wire drawing such as swaging, groove roll processing, or die processing is performed to obtain an R-based oxide powder-filled Ag composite wire having a diameter of 5 mm or less. Wrap R type oxide powder filled Ag composite wire (Hereinafter referred to as “R-based oxide-filled coil”), the R-based oxide-filled coil was heat-treated at a temperature of 900 to 950 ° C. in the air or an oxygen atmosphere to produce an R-based oxide superconducting coil. .

Furthermore, in recent years, Bi-Ca-Sr-Cu-O-based oxides (hereinafter referred to as Bi-based oxides) and Tl-Ca-Ba-Cu-O-based oxides (hereinafter referred to as Tl-based oxides) are liquid nitrogen. Coolable 77 ° K
It was discovered that it exhibits superconductivity at the above temperatures.

First, the Bi-based oxides are Bi ₂ O ₃ powder and CaC as raw material powders.
O ₃ powder, SrCO ₃ powder and CuO powder are prepared, these raw material powders are mixed in a predetermined ratio and mixed, and the mixed powder is kept in the atmosphere at a temperature of 700 to 800 ° C. for 4 to 12 hours. It is created by firing under the conditions. Further above Tl
The system oxides are Tl ₂ O ₃ powder, CaCO ₃ powder, Ba as raw material powder.
CO ₃ powder and CuO powder are prepared, these raw material powders are mixed in a predetermined ratio and mixed, and this mixed powder is heated at a temperature of 600 to 70.
It is prepared by carrying out a firing treatment in which the temperature is kept in the range of 0 ° C. for 4 to 12 hours in the atmosphere.

The Bi-based oxide or Tl-based oxide thus prepared is crushed to obtain a Bi-based oxide powder or Tl-based oxide powder having an average particle size of 5 μm or less.
Fill each of the Tl-based oxide powders into Ag tubes and
After sealing both ends of a Bi-based oxide powder-filled Ag tube or Tl-based oxide powder-filled Ag tube, these are wire-drawn to have a diameter of 5 mm or less and Bi-based oxide powder-filled Ag composite wire or Tl-based oxide. As a powder-filled Ag composite wire, these Ag composite wires are wound, and a Bi-based oxide powder-filled Ag composite wire coil (hereinafter referred to as Bi-based oxide-filled coil) or a Tl-based oxide-filled Ag composite wire coil (hereinafter, referred to as Tl-based oxide-filled coil) and the above Bi-based oxide-filled coil or
A Bi-based oxide superconducting coil or a Tl-based oxide superconducting coil was manufactured by heat-treating a Tl-based oxide-filled coil in the air or an oxygen atmosphere. The heat treatment temperature of the Bi-based oxide superconducting coil is 830 to 870 ° C, and the heat treatment temperature of the Tl-based oxide superconducting coil is 880 to 920 ° C.

[Problems 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 700 A / c at a high value.
The critical current density of the Bi-based oxide superconducting coil produced by the conventional manufacturing method is about 100 A / cm ² at most, and the Tl-based oxide superconducting coil obtained by the conventional manufacturing method is about m ^2. The coil has a critical current density of up to about 180 A / cm ² .

With this level of critical current density, it cannot be put to practical use as a superconducting coil.
Attempts have also been made to increase the packing density of superconducting oxide powder by subjecting a Bi-based oxide-filled coil or a Tl-based oxide-filled coil to explosive compression, thereby improving the critical current density. When it is directly explosively compressed, the coil is deformed so that the coil does not have the shape of the coil, cutting occurs at various places, and there is a problem that it cannot be put to practical use as a coil to be incorporated into various industrial electric devices.

[Means for Solving the Problems]

Therefore, the inventors of the present invention have conducted research to obtain a superconducting coil having a higher critical current density that can be put to practical use, and as a result, the above R-based oxide-filled coil, Bi-based oxide-filled coil or Tl A superconducting oxide-filled coil, such as a system oxide-filled coil, is charged with a pressure medium into a gap composed of a large-diameter cylinder and a small-diameter cylinder, and an explosive is exploded simultaneously outside the large-diameter cylinder and inside the small-diameter cylinder. Therefore, it has been found that the above-mentioned superconducting oxide-filled coil can be densified without deformation or cutting, and a superconducting coil having an extremely high critical current density can be obtained.

The present invention has been made on the basis of such knowledge, and hereinafter, a method for manufacturing a superconducting coil by the explosion compression method of the present invention will be specifically described with reference to the drawings.

FIG. 1 is a sectional elevation view showing a state in which the superconducting oxide-filled coil is set to explosively compress the superconducting oxide-filled coil by the explosive compression method, and FIG. 2 is a superconducting oxide-filled coil. FIG. 2 is a plan view of the II-II cross section in FIG.

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, 5
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 a metal such as steel or Al or an alloy thereof, but are not limited to the above metals and alloys, and plastic, tempered glass, ceramics, cardboard, etc. are used. It is also possible.

The pressure medium 7 may be a fluid, but the average particle size is 1 to 1,000 μm.
The powder which is hard to be solidified by explosive compression of is preferable. As these powders, for example, Al ₂ O ₃ , SiO ₂ , MgO, oxide powders such as ZrO ₂ and complex oxide powders of these oxides, AlN, TiN, nitride powders such as Si ₃ N ₄ , T,
iB ₂ , ZrB ₂ , boride powder such as MoB, carbide powder such as SiC, TiC, ZrC, WC, silicide powder such as MoSi ₂ , TiSi, ZrSi, and others, carbonitride powder, carbon boride powder, etc. Solid solution powder is used.

The setting of the superconducting oxide-filled coil as shown in FIGS. 1 and 2 is performed as follows.

First, a cardboard container 5 is prepared, 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. The pressure medium 4 and the superconducting oxide-filled coil 3 are placed in the above-mentioned space. After the pressure medium 4 is charged, it is preferable that the pressure medium 4 be vibrated and filled so as to have a sufficiently high density.

A pressure medium 4 and a superconducting oxide-filled coil 3 are provided in the void.
After loading, the ring-shaped lid 8 is placed. The lid 8 is
It is preferable to fix the large diameter cylinder 1 and the small diameter cylinder 2 with an adhesive agent or an adhesive tape.

After covering the lid 8, the cardboard container 5 is filled with the explosive 6 and exploded by the detonator 7 to explodely compress and densify the superconducting oxide-filled coil without cutting and deforming the explosive compression. The superconducting oxide-filled coil thus densified is taken out and heat-treated in the air or an oxygen atmosphere, whereby a superconducting coil having a particularly high critical current density can be manufactured.

In FIG. 1 and FIG. 2, one superconducting oxide-filled coil is explosively compressed by using two cylinders having different diameters (a large-diameter cylinder and a small-diameter cylinder), but it is not limited to this. However, in the present invention, 2n pieces (however, n
Is a positive integer), it is possible to explode and compress n superconducting oxide-filled coils having different diameters at the same time.

〔Example〕

Next, the present invention will be described more specifically based on examples.

Example 1 As raw material powders, yttrium oxide (Y ₂ O ₃ ) powder having an average particle size: 6 μm, barium carbonate (BaCO ₃ ) powder having an average particle size: 6 μm, and copper oxide (CuO) powder having an average particle size: 6 μm , And mix these powders in a molar ratio of Y ₂ O ₃ : BaCO ₃ : CuO = 1/2: 2: 3, and mix them. : Calcination at 900 ° C for 12 hours is carried out to produce a compound having a composition of YBa ₂ Cu ₃ O ₇ and having a perovskite structure (hereinafter referred to as Y-based oxide), and further crushing these compounds. Then, a Y-based oxide powder having an average particle diameter of 1.3 μm was produced.

The above Y-based oxide powder, inner diameter: 20mm × wall thickness: 1.5mm × length:
A 200 mm Ag tube was filled, and the filled Ag tube was swaged and then groove-rolled to produce a Y-based oxide-filled Ag composite wire having a diameter of 2 mm.

Two Y-based oxide-filled coils with an inner diameter of 60 mm were made by winding the above Y-based oxide-filled Ag composite wire, and one of them was inserted as shown in FIGS. gave.

The explosive compression was carried out as follows.

First, prepare a cardboard container 5 made of cardboard with a thickness of 0.5 mm. Inside the cardboard container 5, the outer diameter: 75 mm × inner diameter: 70 mm × height: 110 mm large diameter cylinder 1 made of steel pipe, and the outer Diameter: 45 mm x Inner diameter: 40 mm x Height: 110 mm Steel pipe small diameter cylinder 3
Were vertically installed concentrically.

The Y-based oxide-filled coil 3 having an inner diameter of 60 mm and the SiC powder compression medium 4 having an average particle diameter of 2 μm were charged in the space formed by the steel pipe large-diameter cylinder 1 and the steel pipe small-diameter cylinder 2 and further vibrated. Was added to fill the SiC powder sufficiently densely, and then the lid 8 was closed. The lid 8 was fixed to the steel pipe large diameter cylinder 1 and the steel pipe small diameter cylinder 2 with an adhesive.

Then, the cardboard container 5 is filled with an explosive 6 and the explosive 6 is placed outside the steel pipe large-diameter cylinder 1 and inside the steel pipe small-diameter cylinder 2 to explode it with a detonator 7, and
The system oxide-filled coil 3 was explosion-compressed and densified.

Both the Y-oxide-filled coil that has been densified by explosion compression and the Y-oxide-filled coil that is not explosion-compressed are heat-treated in an oxygen atmosphere at a temperature of 920 ° C. for 24 hours to perform explosion compression. The produced Y-type oxide superconducting coil (Example 1) and the Y-type oxide superconducting coil not subjected to explosive compression (Comparative Example 1) were prepared, and the superconducting characteristics of these two types of superconducting coils were measured. The results are shown in Table 1.

Example 2 As a raw material powder, Bi ₂ O _{3 having an} average particle size of 10 μm or less was used.
Prepare powder, CaCO ₃ powder, SrCO ₃ powder and CuO powder,
These powders are Bi ₂ O ₃ powder: 53.4%, CaCO ₃ powder: 11.5%,
SrCO ₃ powder: 16.9% and CuO powder: 18.2% (above weight%)
To obtain a Bi-based oxide, which is then subjected to a firing treatment in the atmosphere at a temperature of 800 ° C. for 12 hours to prepare a Bi-based oxide, which is then obtained by the firing treatment. The obtained Bi-based oxide was pulverized to produce a Bi-based oxide powder having an average particle diameter of 5 μm.

The above Bi-based oxide powder, inner diameter: 20 mm × wall thickness: 1.5 mm × length:
Fill a 200 mm Ag tube, swage this Ag tube, and then groove roll it.
A Bi-based oxide-filled Ag composite wire was prepared.

Wrap the above Bi-based oxide-filled Ag composite wire and the inner diameter: 60 mm of B
Two i-based oxide-filled coils were produced, and one of them was set as shown in FIGS.
After performing explosive compression under exactly the same conditions as above, take it out, along with the Bi-based oxide-filled coil that is not subjected to explosive compression,
A Bi-based oxide superconducting coil that was heat-treated in an oxygen atmosphere at a temperature of 850 ° C. for 15 hours and was subjected to explosive compression (Example 2) and a Bi-based oxide superconducting coil that was not subjected to explosive compression (Comparative Example 2) ) Was prepared, the superconducting characteristics of these superconducting coils were measured, and the results are shown in Table 1.

Example 3 As a raw material powder, Tl ₂ O _{3 having an} average particle size of 10 μm or less was used.
Prepare powder, CaCO ₃ powder, BaCO ₃ powder and CuO powder,
These powders, Tl ₂ O ₃ powder: 35.4%, CaCO ₃ powder: 15.5%,
BaCO ₃ powder: 30.6% and CuO powder: 18.5% (above wt%)
The mixed powder is mixed and mixed, and the mixed powder is fired in an oxygen atmosphere at a temperature of 800 ° C. for 10 hours to prepare a Tl-based oxide powder, which is then fired. The resulting Tl-based oxide was pulverized to produce a Tl-based oxide powder having an average particle size of 5 μm.

The above Tl-based oxide powder, inner diameter: 20 mm × wall thickness: 1.5 mm × length:
Fill a 200 mm Ag tube, swage this Ag tube, and then groove roll it.
A Tl-based oxide-filled Ag composite wire was prepared.

Wrap the above Tl-based oxide-filled Ag composite wire and the inner diameter: 60 mm of T
Two l-type oxide-filled coils were prepared, one of which was placed in the apparatus shown in FIG. 1, subjected to explosive compression under the exact same conditions as in Example 1, and then taken out, and the above explosive compression was not applied.
Temperature: 9 in oxygen atmosphere with Tl-based oxide-filled coil
Heat-treated under conditions of holding at 00 ℃ for 3 hours and subjected to explosive compression
Tl-based oxide superconducting coils (Example 3) and Tl-based oxide superconducting coils not subjected to explosive compression (Comparative Example 3) were prepared, and the superconducting characteristics of these superconducting coils were measured. The results are shown in Table 1. It was

In addition, in the first to third embodiments, the case where two cylinders of the large diameter cylinder and the small diameter cylinder are used is shown. However, the number of the above cylinders is not limited to the above embodiment, and any diameters different from each other may be used. A plurality of superconducting oxide-filled coils can be simultaneously explosively compressed and densified using an even number of cylinders.

〔The invention's effect〕

When the superconducting oxide powder-filled Ag code wire is used as a coil, and the coil is loaded together with a pressure medium into a cylindrical container and explosively compressed, the explosive compression can be performed without deformation and cutting of the coil. Example 1 of the present invention obtained by heat-treating the above in air or oxygen atmosphere
The superconducting coil of No. 3 is Comparative Examples 1 to 3 which are not subjected to explosive compression.
Compared with the superconducting coil of, the critical current density is particularly excellent, and since it has a high critical current density that is practically used, the superconducting coil obtained by the manufacturing method of the present invention is
It greatly contributes to the development of industry. Further, according to the present invention, since a large number of coils having different diameters can be explosively compressed at the same time, a large number of excellent superconducting coils can be supplied at a low cost, and an excellent effect is obtained economically. .

[Brief description of drawings]

FIG. 1 is a sectional elevation view showing a state in which a superconducting oxide-filled coil is set between cylinders having different diameters for explosive compression, and FIG. 2 is a sectional view taken along line II-II of FIG. 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

Front page continuation (72) Inventor Hideki Tonda 4-2 Higashimachi, Kumamoto-shi, Kumamoto 6-201 Higashimachi Minami House (201) (72) Kazuki Takashima 1000-10 Yasukubomoto-cho, Kumamoto-shi, Kumamoto 401 (56) References JP-A 1-1112709 (JP, A) JP-A 63-287010 (JP, A) JP-A 64-9861 (JP, A) JP-A 63-222063 (JP, A)

Claims (7)

[Claims] 1. An even number of cylinders having different diameters are prepared, and the even number of cylinders are erected vertically in a concentric circle to form a plurality of voids formed by the inner surface and the outer surface of the even number of cylinders. The plurality of voids are filled with explosives, a coil obtained by winding a superconducting oxide powder-filled Ag composite wire (hereinafter referred to as a coil) and a pressure medium alternately, and among the even number of cylinders. Explosives are placed inside the cylinder having the smallest diameter and outside the cylinder having the largest diameter, and the explosive is exploded to compress and densify the coil. A method for manufacturing a superconducting coil by explosive compression, which is characterized by heat treatment in the air or an oxygen atmosphere. 2. A large-diameter cylinder and a small-diameter cylinder having an outer diameter smaller than the inner diameter of the large-diameter cylinder are prepared, the large-diameter cylinder is erected vertically, and the small-diameter cylinder is provided at the center of the large-diameter cylinder. Standing vertically, while filling the coil and the pressure medium in the void formed by the inner surface of the large-diameter cylinder and the outer surface of the small-diameter cylinder, and disposing the explosive on the outside of the large-diameter cylinder and the inside of the small-diameter cylinder, Explosion-compressing and densifying the coil by detonating explosive from the outside of the large-diameter cylinder and the inside of the small-diameter cylinder, and heat-treating the explosively-compressed and densified coil in air or oxygen atmosphere. A method for manufacturing a superconducting coil by the explosion compression method according to claim 1. 3. The pressure medium has an average particle diameter of 1 to 1,000 μm.
2. The method for producing a superconducting coil by the explosion compression method according to claim 1, wherein the powder is a powder which is hard to be solidified by the explosion compression. 4. The explosive compression method according to claim 1, wherein the superconducting oxide powder is a compound powder having a perovskite structure composed of a rare earth element containing Y, an alkaline earth metal, Cu and oxygen. Manufacturing method of superconducting coil. 5. The above-mentioned superconducting oxide powder is Bi-Ca-Sr-Cu.
3. The method for producing a superconducting coil by the explosion compression method according to claim 1, wherein the superconducting coil is an -O-based oxide powder. 6. The superconducting oxide powder is Tl-Ca-Ba-Cu.
3. The method for producing a superconducting coil by the explosion compression method according to claim 1, wherein the superconducting coil is an -O-based oxide powder. 7. The method for manufacturing a superconducting coil by the explosion compression method according to claim 1, wherein the pressure medium is a fluid.