JPH07118414B2 - 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 a superconducting phenomenon at 77 ° K which 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 an average particle size of 10 μm or less to form an R-based oxide powder, 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, Bi-based oxides) and Tl-Ca-Ba-Cu-O-based oxides (hereinafter, 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.
Each of the Tl-based oxide powders was filled in an Ag tube and
After closing both ends of the Ag tube or the Tl-based oxide powder-filled Ag tube filled with Bi-based oxide powder, wire drawing is performed on these ends and the diameter is 5 mm or less. 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 coil in which a system oxide-filled coil is loaded into a cylindrical container together with a pressure medium and explosively compressed can be filled with superconducting oxide powder at high density without deformation or cutting, resulting in an extremely high critical current density. It was found that a superconducting coil having

The present invention has been made based on such findings, wherein the R-based oxide-filled coil, the Bi-based oxide-filled coil or the Tl-based oxide-filled coil is charged into a cylindrical container together with a pressure medium, By explodingly compressing the cylindrical container charged with the coil and the pressure medium, the coil is explosively compressed and densified, and then the explosively compressed and densified coil is exposed to air or oxygen atmosphere. It is characterized by the method of manufacturing a superconducting coil by the explosive compression method of heat treatment.

A method of 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 partial cross-sectional explanatory view of a cylindrical container used for explosive compression of a coil by the explosive compression method of the present invention. In FIG. 1, 1 is a cylindrical container, 2 is a pressure medium (solid powder), 3
Is a superconducting oxide filled coil, and 4 is a lid of a cylindrical container.

Cylindrical container made of metal or alloy such as steel or Al 1
Is filled with a pressure medium 2 which is hard to be solidified by explosive compression, for example, SiC powder, Al ₂ O ₃ powder, TiN powder, etc., and at the same time, the superconducting oxide filling coil 3 is placed near the center of the cylindrical container. Charge. The average particle size of the powder used for the pressure medium 2 which is hard to solidify by explosive compression is 1
˜1000 μm is preferable, and it is more preferable to insert the coil 3 together with the superconducting oxide-filled coil 3 and then apply vibration or the like to more densely fill the coil. The cylindrical container 1 is not limited to the above metal or alloy, and may be made of plastic, glass, ceramic, cardboard, or the like.

As shown in FIG. 1, a cylindrical container 1 filled with a superconducting oxide-filled coil 3 and a pressure medium 2, vibrated, and covered with a lid 4 is loaded into a cardboard container 7 as shown in FIG. After the explosive 8 is further filled, it is explosively compressed by the detonator 9. By explosively compressing the cylindrical container 1, the superconducting oxide-filled coil 3 charged in the cylindrical container 1 is uniformly explosive-compressed without being cut or deformed, and the superconducting oxide filled in the coil 3 is oxidized. The material powder is compressed more densely.

As the pressure medium, it is easier to use solid powder as shown in FIG. 1, but if the lid 4 of the cylindrical container 1 is sufficiently sealed, water is used as shown in FIG. It is also possible to fill a fluid such as oil or the like as the pressure medium 2 '.
In that case, the end portion of the linear portion 5 of the superconducting oxide-filled coil 3 is attached to the chuck 6 provided in the central portion on the back side of the lid 4,
The superconducting oxide-filled coil 3 may be placed in the cylindrical container 1 filled with the fluid pressure medium 2 ′ so as to be located near the center of the cylindrical container 1.

The superconducting oxide-filled coil 3 is taken out from the cylindrical container 1 that has been explosively compressed in the state shown in FIG. 3 and heat-treated in the air or in an oxygen atmosphere to produce a superconducting coil having a high critical current density.

As the powder that is hard to be solidified by the above-mentioned explosive compression, specifically, oxide powders such as Al ₂ O ₃ , SiO ₂ , MgO and ZrO ₂ or composite oxide powders thereof, nitrides such as AlN and Si ₃ N ₄ are used. Powder, boride powder such as TiB ₂ , ZrB ₃ , MoB, carbide powder such as TiC, SiC, ZrC, WC or solid solution powder of these carbides, silicide powder such as MoSi ₂ , TiSi, ZrSi, other carbonitride It is possible to use solid powders of charcoal silicide, carbon boride, and the like.

〔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 of 6 μm, barium carbonate (BaCO ₃ ) powder having an average particle size of 6 μm, and copper oxide (CuO) powder having an average particle size of 6 μm And mixing these powders in a molar ratio of Y ₂ O ₃ : BaCO ₃ : CuO = 1/2: 2: 3, and mixing them. : Calcinated at 900 ℃ for 12 hours, YBa ₂ Cu
A compound having a composition of ₃ O ₇ and having a perovskite structure (hereinafter referred to as a Y-based oxide) was prepared, and these compounds were pulverized to prepare a Y-based oxide powder having an average particle diameter of 1.3 μm. did.

The above Y-based oxide powder, inner diameter: 20mm × wall thickness: 1.5mm × length:
It was filled in a 200 mm Ag tube, 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.

The Y-type oxide-filled Ag composite wire was wound to produce two Y-type oxide-filled coils having an inner diameter of 12 mm, and one of them was placed in the cylindrical container shown in FIG. 1 and subjected to explosive compression.

The explosive compression was carried out as follows.

First, prepare a copper bottomed cylindrical container 1 having an outer diameter of 30 mm, an inner diameter of 26 mm, and a length of 108 mm, and place the Y-based oxide-filled coil having the inner diameter of 12 mm near the center of the cylindrical container. After filling with SiC powder having an average particle size of 2 μm and further applying vibration to fill the SiC powder so as to be sufficiently dense, the lid 4
Did. The lid 4 does not necessarily have to be provided and can be implemented without the lid.

As shown in FIG. 3, the cylindrical container 1 shown in FIG. 1 having the Y-based oxide-filled coil 3 incorporated therein is placed in a cardboard container 7 made of cardboard having a thickness of 0.5 mm, and then powdered. Explosives 8
(Explosion speed of 2,300 m / sec) is charged with 200 g, and then the detonator 9
It caused an explosion and was compressed.

The Y-based oxide-filled coil is taken out from the explosion-compressed cylindrical container 1, and the Y-oxide-filled coil that is explosion-compressed and the Y-oxide-filled coil that is not explosion-compressed are
Both of them were heat-treated in an oxygen atmosphere at a temperature of 920 ° C. for 24 hours, and were subjected to explosive compression in a Y-based oxide superconducting coil (Example 1) and non-explosive-compressed Y-based oxide superconducting coil (Comparative Example). 1) was prepared, the superconducting characteristics of these two types of superconducting coils were measured, and the results are shown in Table 1.

Example 2 As the 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 to a diameter of 2 mm.
A Bi-based oxide-filled Ag composite wire was prepared.

Wrap the above Bi-based oxide-filled Ag composite wire and have an inner diameter of 12 mm B
Two i-based oxide-filled coils were produced, one of which was placed in the apparatus shown in FIG. 1, subjected to explosive compression under exactly the same conditions as in Example 1, and then taken out, and the above explosive compression was not applied.
With Bi-based oxide-filled coil, temperature: 8 in oxygen atmosphere
Heat-treated under conditions of holding at 50 ℃ for 15 hours and subjected to explosive compression
Bi-based oxide superconducting coils (Example 2) and Bi-based oxide superconducting coils not subjected to explosive compression (Comparative Example 2) were prepared, and the superconducting characteristics of these superconducting coils were measured. The results are shown in Table 1. Indicated.

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% (hereinafter 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 to a diameter of 2 mm.
A Tl-based oxide-filled Ag composite wire was prepared.

Wrap the above Tl-based oxide-filled Ag composite wire and the inner diameter: 12 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 coil (Example 3) and Tl-based oxide superconducting coil not subjected to explosive compression (Comparative Example 3) was prepared and the superconducting characteristics of these superconducting coils were measured. The results are shown in Table 1.

〔The invention's effect〕

When a superconducting oxide powder-filled Ag composite wire is made into a coil, and this coil is loaded together with a pressure medium into a cylindrical container and explosively compressed, it can be explosively compressed without deformation and cutting of the coil. The superconducting coils of Examples 1 to 3 of the present invention obtained by heat-treating the coil in the air or oxygen atmosphere are Comparative Example 1 in which explosive compression is not applied.
The superconducting coil obtained by the manufacturing method of the present invention greatly contributes to the development of industry because it has a particularly high critical current density as compared with the superconducting coils of 3 and has a high critical current density that is practically used. To do.

[Brief description of drawings]

FIG. 1 is a partial sectional view of an embodiment of a cylindrical container used for explosive compression of a coil of the present invention, and FIG. 2 is used for explosive compression of a coil of another embodiment when a fluid is used as a pressure medium. Fig. 3 is a partial cross-sectional view of the cylindrical container, Fig. 3 is an explanatory view showing a state where the cylindrical container of Fig. 1 is filled with explosives in order to explosively compress it, 1: cylindrical container 2: pressure medium (solid powder ) 2 ': Pressure medium (fluid) 3: Superconducting oxide-filled coil 4: Lid, 5: Linear part 6: Chuck, 7: Cardboard container 8: Explosive, 9: Detonator

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location H01B 13/00 565 D (72) Inventor Hideki Tonda 4-2 Higashimachi, Kumamoto-shi, Kumamoto Prefecture 6-201 ( 72) Inventor Kazuki Takashima 1000-10 Yasukubohonmachi, Kumamoto-shi, Kumamoto 401 Hirai Heights 401 (56) Reference 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. A coil obtained by winding a superconducting oxide powder-filled Ag composite wire (hereinafter referred to as a coil) is charged into a cylindrical container together with a pressure medium, and the cylindrical container containing the coil and the pressure medium is charged into the cylindrical container. Superconducting coil by explosive compression method, characterized in that the coil is explosively compressed and densified by explosive compression, and then the explosively compressed and densified coil is heat-treated in air or oxygen atmosphere. Manufacturing method. 2. The method for producing a superconducting coil by the explosion compression method according to claim 1, wherein the coil is inserted so as to be located at or near the center of the cylindrical container. 3. The method for producing a superconducting coil by explosive compression according to claim 1, wherein the pressure medium is a powder having an average particle diameter of 1 to 1000 μm which is hard to be solidified by explosive compression. 4. The method for producing a superconducting coil according to claim 1, wherein the pressure medium is a fluid. 5. 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. Superconducting coil manufacturing method. 6. The superconducting oxide powder is Bi-Ca-Sr-Cu.
The method for producing a superconducting coil by the compression method according to claim 1, wherein the superconducting coil is an -O-based oxide powder. 7. The superconducting oxide powder is Tl-Ca-Ba-Cu.
The superconducting coil manufacturing method according to claim 1, wherein the superconducting coil is an -O-based oxide powder.