JPH07118413B2 - 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 .

If it has such a critical current density, it cannot be put to practical use as a superconducting coil, and in order to put it to practical use, the appearance of a superconducting coil having an even higher critical current density has been desired.

[Means for Solving the Problems]

Then, the inventors of the present invention have conducted research to manufacture a superconducting coil having a further excellent high critical current density, and as a result, the above R-based oxide-filled coil, Bi-based oxide-filled coil or Tl-based oxide-filled coil has been obtained. After inserting the coil into a mandrel, charging it with a pressure medium into a cylindrical container, exploding and compressing it, and densifying the entire coil, and then heat treating it in the air or oxygen atmosphere, superconductivity with extremely high critical current density We have obtained the knowledge that a coil can be obtained.

The present invention has been made on the basis of such findings, in which the R-based oxide-filled coil, the Bi-based oxide-filled coil or the Tl-based oxide-filled coil is placed in a cylindrical container having a mandrel and the shaft of the mandrel. And the coil are charged together so that the center lines of the coils substantially coincide with each other, and the cylindrical container having the mandrel charged with the coil and the pressure medium is explosively compressed to explodely compress the coil. It is characterized by a method for producing a superconducting coil by heat-treating an explosively compressed coil in the air or an oxygen atmosphere.

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 according to the present invention. 1 is a cylinder, 2 is an end plug, 3 is a mandrel, 4 is a cap, 5 is a superconducting oxide-filled coil, and 6 is It is a pressure medium.

The cylindrical container shown in FIG. 1 is assembled as follows.

First, the end plug 2 having the hole 7 having the same diameter as the mandrel 3 is attached to the bottom of the cylinder 1. End plug 2 above
Can be attached to the cylinder 1 by appropriate means such as driving, screwing, welding, and bonding. The material of the cylinder 1 is metal, plastic, glass, ceramic, wood,
It can be made of cardboard or the like.

The round rod-shaped mandrel 3 to which the superconducting oxide-filled coil 5 is attached is loaded into the cylindrical container having the hole 7 formed in the bottom in this way. The superconducting oxide-filled coil 5
Is preferably mounted so that the center line of the coil 5 coincides with the axis of the mandrel 3, but some deviation is allowed. To fix the superconducting oxide-filled coil 5 to the mandrel 3, two pores having the same diameter as the diameter of the superconducting oxide-filled coil 5 are provided on the side surface of the mandrel, and the two pores are provided. Alternatively, both ends of the superconducting oxide-filled coil 5 may be attached by inserting it, or alternatively, both ends of the superconducting oxide-filled coil 5 may be fixed to the mandrel 3 with an adhesive, an adhesive tape, or the like.

One end of the mandrel 3 with the superconducting oxide filling coil 5 is inserted into the hole 7 of the end plug 2 and then the pressure medium 6 made of solid powder is filled in the cylindrical container. The solid powder is preferably SiC powder, Al ₂ O ₃ powder, or other ceramic powder, and the particle size of the solid powder is an average particle size of 1 to 1.
1000 μm is preferable.

The filled solid powder pressure medium 6 is vibrated to be densely filled, and then the hole 8 having the same diameter as the mandrel 3 is provided.
With the cap 4 having the above, the mandrel 3 is inserted into the hole 8 and the lid is closed.

The cylindrical container of FIG. 1 thus obtained is charged into a cardboard container 9 as shown in FIG.
After being charged, the detonator 11 explodes and compresses. Incidentally, a plastic explosive may be used instead of the powder explosive. In this case, the cardboard container 9 is unnecessary.

As shown in FIG. 1, the pressure medium to be filled is preferably a powder that is hard to solidify by explosive compression, for example, a solid powder such as SiC or Al ₂ O _3, but if the container is sufficiently sealed, A fluid can also be used as the pressure medium 6'as shown in FIG.

The explosive-compressed superconducting oxide-filled coil 5 is taken out of the explosive-compressed device, and the explosive-compressed superconducting oxide-filled coil 5 is heat-treated in the air or in an oxygen atmosphere to obtain a critical current density An excellent superconducting coil can be manufactured.

In order to uniformly explode and compress the superconducting oxide-filled coil 5 by the explosive compression, the superconducting oxide-filled coil 5 is loaded into the cylinder 1 so that the axis of the mandrel 3 and the center line of the superconducting oxide-filled coil coincide with each other. . However, the centerlines do not have to be perfectly coincident and some deviations are possible. That is, when the cylinder 1 is detonated in a state of being surrounded by the powder explosive 10, the shock wave directed from the cylinder 1 toward the center is reflected by the mandrel 3, and the shock pressure is applied also from the inside of the superconducting oxide-filled coil 5. It is considered that the density of the superconducting oxide powder with which the coil 5 is filled is increased.
Therefore, when the axis line of the mandrel 3 and the center line of the superconducting oxide-filled coil 5 are greatly deviated, unevenness occurs in the explosion compression from the inside of the coil 5, and a superconducting coil having a sufficiently high critical current density is obtained. I can't get it.

Therefore, it is preferable that the mandrel 3 is also attached so that the axis of the mandrel 3 coincides with the axis of the cylinder 1, but some deviation may occur.

The solid powder used as the pressure medium is Al ₂ O ₃ , SiO ₂ , MgO, Zr.
O _{2 and} other oxide powders or their composite oxide powders, Al
N, TiN, nitride powder such as Si ₃ N ₄ , TiB ₂ , ZrB ₃ , boride powder such as MoB, TiC, SiC, ZrC, carbide powder such as WC or solid solution powder of these carbides, MoSi ₂ , TiSi, It is possible to use a silicide powder such as ZrSi, or a solid powder such as carbonitride, carbon silicide, or carbon boride.

〔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 the powders. : Calcinated at 900 ℃ for 12 hours, YBa ₂ Cu
A compound having a composition of ₃ O ₇ and having a perovskite structure was prepared, and further, these compounds were crushed to obtain an average particle diameter:
An R-based oxide powder of 1.3 μm was produced.

The above R-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 prepare an R-based oxide-filled Ag composite wire having a diameter of 2 mm.

The R-type oxide-filled Ag composite wire was wound to produce two R-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, a steel cylinder 1 with an outer diameter of 30 mm, an inner diameter of 26 mm, and a length of 108 mm 1.
A cylindrical end plug 2 having a hole with a diameter of 8 mm and an outer diameter of 26 mm and a thickness of 5 mm was formed in the bottom of the cylinder 1.
The prepared R-based oxide-filled coil 5 was temporarily attached to the hole 7 of the end plug 2 with an adhesive. Diameter: 8 mm x length: 110 mm
Insert one end of the steel mandrel 3 of the above, then, in the space between the cylinder 1 and the mandrel 3, the average particle diameter: SiC of 2 μm
After filling the powder and further filling it by vibrating it sufficiently, Al cap 4 having a hole 8 with a diameter of 8 mm at the center is
The mandrel 3 was capped so that the tip of the mandrel 3 could enter the hole 8 of the cap 4. The cap 4 has a thickness of 5 mm and an outer diameter of 30 mm.

As shown in FIG. 3, the cylindrical container shown in FIG. 1 in which the R-based oxide-filled coil 5 is thus loaded has a thickness of:
Charge into a 0.5 mm cardboard container, then powder explosive: 200 g (explosion speed
(2,300 m / sec), and then explosive compressed by the detonator 11.

The R-type oxide-filled coil was taken out from the explosively-compressed cylindrical container, and the R-oxide-filled coil that was explosively-compressed and the R-type oxide-filled coil that was not subjected to explosive compression were both placed in an oxygen atmosphere at a temperature of 920 ° C. The R-type oxide superconducting coil of Example 1 which was heat-treated under the conditions of holding for 24 hours and subjected to explosive compression and the R-type oxide superconducting coil of Comparative Example 1 which was not subjected to explosive compression were manufactured. The characteristics 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% (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:
After filling a 200 mm Ag tube and swaging the filled Ag tube, Groove roll processing was performed to prepare a Tl-based oxide-filled Ag composite wire having a diameter of 2 mm.

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, and one of them was placed in the apparatus shown in FIG. 1 and subjected to explosive compression under exactly the same conditions as in Example 1 and then taken out and not subjected to the above explosive compression.
With Tl-based oxide-filled coil, in oxidizing atmosphere, temperature: 9
Heat-treated under conditions of holding at 00 ℃ for 15 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

〔The invention's effect〕

From the results shown in Table 1, superconducting oxide powder-filled Ag composite wires were formed into coils, and the coils were subjected to explosive compression and then heat-treated in air or oxygen atmosphere to obtain Examples 1 to 3 of the present invention. The superconducting coil has a remarkably excellent critical current density as compared with the superconducting coils of Comparative Examples 1 to 3 which are not subjected to explosive compression, and shows a critical current density for practical use. By incorporating it, it has an excellent industrial effect.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional explanatory view showing a state where a cylindrical container used for explosive compression of the present invention is filled with a coil and a solid powder pressure medium, and FIG. 2 is filled with the coil and a fluid pressure medium in the cylindrical container. FIG. 3 is a partial cross-sectional explanatory view showing a state in which the cylinder container of FIG. 1 is filled with a powder explosive in a cardboard container. 1 ... Cylinder, 2 ... End plug, 3 ... Mandrel, 4 ... Cap, 5 ... Superconducting oxide filled coil, 6 ... Pressure medium (solid powder), 6 '... Pressure medium (fluid), 7 ... Hole, 8 ...
Hole, 9 ... cardboard container, 10 ... powder explosive, 11 ... 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 City, Kumamoto Prefecture Hirai Heights 401 (56) Reference JP-A-1-112709 (JP, A) JP-A-63-287010 (JP, A) Special Kai 64-9861 (JP, A) JP-A-63-222063 (JP, A)

Claims (8)

[Claims] 1. A superconducting coil by an explosive compression method, in which a coil (hereinafter referred to as a coil) obtained by winding a superconducting oxide powder-filled Ag composite wire is densified by explosive compression and then heat-treated in air or oxygen atmosphere. In the manufacturing method, a mandrel having an outer diameter smaller than the inner diameter of the coil, a pressure medium, and a cylindrical container are prepared, and the coil is pressed while the mandrel is inserted in the centerline direction of the coil. Superconductivity by explosive compression method characterized in that the coil is explosively compressed and densified by explosively compressing the cylindrical container filled with the medium and the coil inserted through the mandrel and the pressure medium. Coil manufacturing method. 2. The explosion according to claim 1, wherein the coil and the mandrel are filled in the cylindrical container so that the center line of the coil, the axis of the mandrel and the axis of the cylindrical container coincide with each other. Manufacturing method of superconducting coil by compression method. 3. The method for producing a superconducting coil according to claim 1, wherein the pressure medium is a powder having an average particle size of 1 to 1000 μm which is not 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 method for producing a superconducting coil by the explosion compression method according to claim 1, wherein the mandrel is made of metal or ceramics. 6. 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. 7. The superconducting oxide powder is Bi-Ca-Sr-Cu.
The superconducting coil manufacturing method according to claim 1, wherein the superconducting coil is an -O-based oxide powder. 8. 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.