JPH0225005A - Manufacture of superconducting coil using explosive compression method - Google Patents

Abstract

PURPOSE:To simultaneously obtain a plurality of superconducting coils of high critical current density having different diameters by a method wherein a coil on which superconducting-oxide- powder-filled composite wire is wound, and a pressure medium are inserted between pipes and a mandrel, the coil is brought into the state of high density by the explosion of the explosive filled between the pipes, and the coil is heat-treated in the atmospheric air or in an oxygen atmosphere. CONSTITUTION:An even number of first tube 2 and a second tube 3, having the external shape smaller than the inside diameter of cylindrical outside mold 1, and a mandrel 5, having the diameter smaller than the inside diameter of the smallest tube among said even number of tubes, are provided in the manufacturing device of a superconducting-oxide-filled coil. Said mandrel 5 and the even number of tubes 2 and 3 are concentrically inserted into the cylindrical external mold 1. A large diameter superconducting-oxide-powder-filled coil 4, a small diameter superconducting-oxide-powder-filled coil 4', and pressure mediums 7 and 7' are inserted between the mandrel 5 and the tube 3, between the tubes 2 and 3, and also between the 2 and the cylindrical outside mold 1 respectively. An explosive 9 is filled between the tubes 2 an 3, and the coils 4 and 4' are simultaneously brought into the state of high density respectively by the explosion of the explosive 9.

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.

[Conventional technology]

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 these oxides exhibit superconductivity at a temperature of 77°K, which can be cooled with liquid nitrogen.

As a method for manufacturing a superconducting coil using the above R-based oxide powder, first, as raw material powders, R2O3 powder, alkaline earth metal carbonate powder, and CuO powder, all of which have an average particle size of 10 m or less, are prepared. These raw material powders are blended into a predetermined composition, mixed, and fired at a temperature of 2850 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 10- or less to obtain an R-based oxide powder, and this R-based oxide powder is filled into an Ag tube.
After sealing both ends of this R-based oxide powder-filled Ag tube, wire drawing processing such as swaging processing, groove rolling processing, or die processing is performed to create an R-based oxide powder-filled Ag composite wire with a diameter of 51 mm or less. Then, the above R-type oxide powder-filled Ag composite wire is wound to form a coil of R-type oxide powder-filled Ag composite wire (hereinafter referred to as R-type oxide-filled coil).
The R-type oxide superconducting coil was manufactured by heat-treating the R-type oxide-filled coil at a temperature of 900 to 950° C. in air or oxygen atmosphere.

Furthermore, in recent years, Bi-Ca-Sr-Cu-0-based oxides (hereinafter referred to as Bi-based oxides) and T, Q-
It has been discovered that Ca-Ba-Cu-0-based oxides (hereinafter referred to as τΩ-based oxides) exhibit superconductivity at temperatures of 77° or higher, which can be cooled with liquid nitrogen.

The above-mentioned Bj-based oxide is first prepared by using BiO powder, CaCOs powder, SrCOa powder, and CuO powder as raw material powders.
By preparing O powder, blending and mixing these raw material powders in a predetermined ratio, and baking this mixed powder under conditions of holding it in the air for 4 to 12 hours at a temperature within the range of 00 to 800°C. Created. Furthermore, the above Tl-based oxidized proboscis is made of raw material powder such as TlO powder, CaCOs powder, B
a COs powder and CuO powder are prepared, these raw material powders are blended in a predetermined ratio, mixed, and this mixed powder is heated in the air at a temperature in the range of 600 to 700°C for 4 to 12 minutes.
It is created by performing the firing process of time retention F and 1j.

Bi-based oxide or T, 17 created in this way
The oxide is pulverized into Bi-based oxide powder or 1g-based oxide powder with an average particle size of 5- or less, and these Bi-based oxide powder or Tl-based oxide powder are filled into Ag tubes. After sealing both ends of the Bi-based oxide powder-filled Ag tube or Tl-based oxide powder-filled Ag tube, these are wire-drawn to form a Bi-based oxide powder-filled Ag composite wire or Tl-based oxide powder with a diameter of 5 or less. These Ag composite wires are wound to form a coil of Bi-based oxide powder-filled Ag composite wire (hereinafter referred to as Bi-based oxide-filled coil) or a coil of Tl-based oxide-filled Ag composite wire (hereinafter referred to as Bi-based oxide-filled coil). , referred to as a Ti-based oxide-filled coil), and heat-treating the Bi-based oxide-filled coil or Ti-based oxide-filled coil in air or oxygen atmosphere to produce a Bi-based oxide superconducting coil or a 1g-based oxide superconducting coil. was manufacturing. The heat treatment temperature of the Bi-based oxide superconducting coil is 830-87
0°C, and the heat treatment temperature of the 1g-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/c- level, B manufactured by conventional manufacturing method
The critical current density of an i-based oxide superconducting coil is at most 1
00A/cjL, and the TfI-based oxide superconducting coil obtained by the conventional manufacturing method has a maximum of 18OA.
It has a critical current density of only about /cd.

At this level of critical current density, it cannot be used as a practical superconducting coil, so R-based oxide-filled coils,
Attempts have been made to increase the packing density of superconducting oxide powder by subjecting Bi-based oxide-filled coils or Ti-based oxide-filled coils to explosive compression, thereby increasing the critical current density. When subjected to direct explosive compression, the above coil deforms and loses its coil shape;
There was a problem in that the coils were broken at various places and could not be put to practical use as coils for use in 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 TJ7-type oxide-filled coil is inserted together with a pressure medium between the cylindrical outer mold and the tubes, between the tubes and between the tubes, and between the tubes and the mandrel. Then, by filling an explosive between the tubes and detonating the explosive, the superconducting oxide-filled coil can be explosively compressed and densified without deformation or cutting. They found that a superconducting coil obtained by heat-treating a superconducting oxide-filled coil in the air or an oxygen atmosphere has an extremely high critical current density.

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. FIG. 1 is a cross-sectional plan view taken along line n-■ in FIG.

In FIGS. 1 and 2, 1 is a cylindrical outer mold, 2 is a first tube, 3 is a second tube, 4 is a large diameter superconducting oxide-filled coil,
4' is a small diameter superconducting oxide filled coil, 5 is a mandrel,
6 is a substrate, 7 is a pressure medium, 8 is a lid, 9 is an explosive, and 10 is a detonator.

As the cylindrical outer mold 1, a thick cylindrical mold or a cylindrical reinforced concrete mold is used, but a cylindrical mold with a bottom or a concrete mold may also be used. In the case of a bottomed case, there is no need to use the substrate 6. Further, the cylindrical outer mold 1 may be formed by providing a hole in a rock.

It is preferable to use steel pipes for the first pipe 2 and the second pipe 3. However, the material is not limited to steel pipes, and other metals or alloys, plastic pipes, tempered glass pipes, ceramic pipes, cardboard pipes, etc. can also be used.

The outer diameter of the first tube 2 is smaller than the inner diameter of the cylindrical outer mold 1, and the outer diameter of the second tube 3 is smaller than the inner diameter of the first tube 2. Furthermore, Mandrel 5 is
It is made of a round rod of metal or alloy, or a round rod of ceramics, and its outer diameter needs to be smaller than the inside diameter of the second tube 3.

The pressure medium 7 may be a fluid, but has an average particle size of 1 to 1
, 000- powder that is difficult to solidify by explosive compression is preferred. These powders include, for example, 110
23'2' oxide powder such as StOMgO, ZrO2 and composite oxide powder of these oxides, A,
l! Nitride powder such as N, T I N, S ta Ni, TiB ZrB2. Boride powder such as MoB, carbide powder such as 2' Sic, TtC, ZrC, WC, Mo
Si2. Silicide powders such as TiSi and ZrSi, and solid solution powders such as carbonitride powders and carbonoboride powders are also used.

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

First, the substrate 6 is placed, and the cylindrical outer mold 1 is placed thereon. Inside the cylindrical outer mold 1 placed above, a first tube 2,
The second pipe 3 and the mandrel 5 are inserted and installed concentrically.

A large-diameter superconducting oxide-filled coil 4 having a diameter smaller than the inner diameter of the cylindrical outer mold 1 and larger than the outer diameter of the first tube 2 is placed between the cylindrical outer mold 1 and the first tube 2 in a powder form. A small-diameter superconducting oxide-filled coil 4', which is charged together with the pressure medium 7 and has a diameter smaller than the inner diameter of the second pipe and larger than the diameter of the mandrel, is connected to the second pipe 3 and the mandrel 5.
During this period, the powder pressure medium 7 is charged. It is preferable that the powder pressure medium is packed more densely by applying vibration or the like.

After the large-diameter superconducting oxide-filled coil 4, the small-diameter superconducting oxide-filled coil 4', and the powdered pressure medium 7 are inserted in this way, the lid 8 is placed. This lid 8 is provided to separate the powder pressure medium 7 from the explosive 9 to be filled next, and depending on the conditions, it may be possible to carry out the operation without the lid 8.

After filling the superconducting oxide-filled coils 4, 4' and the powdered pressure medium 7 and closing the lid 8, an explosive 9 is filled between the first tube 2 and the second tube 03. The explosive 9 is preferably filled to the extent that it bulges on top of the cylindrical outer mold. The charged explosive 9 is detonated by a detonator IO. When the explosive charged between the first tube 2 and the second tube 3 explodes, the large-diameter superconducting oxide-filled coil 4 and the small-diameter superconducting oxide-filled coil 4' buried in the powder pressure medium 7 is uniformly exploded and compressed from its surroundings without being cut or deformed, and the superconducting oxide powder filled in the coil is compressed to a higher density. In particular, the device used in this invention can explode and compress superconducting oxide-filled coils of different diameters in a single explosion. In addition, in FIGS. 1 and 2 above, two tubes, the first tube 2 and the second tube 3, are used, but the number of tubes is not limited to this, and the third tube and the fourth tube are used. An even number of tubes, such as a tube, a fifth tube, and a sixth tube (not shown), are charged into a cylindrical outer mold, and two or more superconducting oxide-filled coils of different diameters are exploded in one explosion. It can be explosively compressed and densified.

〔Example〕

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

Example 1 As a raw material powder, yttrium oxide (Y2O2) with an average particle size of 6ZU11
Prepare barium carbonate (BaCO3) powder with an average particle size of 6 and copper oxide (Cub) powder with an average particle size of 6ura, and mix these powders in a molar ratio of YO: BaCO3: CuO- 1/2: 2:
This mixed powder is calcined in the atmosphere at a temperature of 900°C for 12 hours to form a compound having a composition of YBa2Cu3O7 and a perovskite structure (hereinafter referred to as , referred to as Y-based oxide), and further pulverize these compounds to obtain an average particle size of 1
．． A 3m Y-based oxide powder was produced.

The above Y-based oxide powder was mixed with inner diameter: 20 m + *X wall thickness = 1.
A 5 mm × length = 200 mm Ag tube 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 mm.

The above Y-based oxide-filled Ag composite wire is wound to have an inner diameter of 9
0mm large diameter Y-based oxide filled coil and inner diameter: lOI
A small-diameter Y-based oxide-filled coil of IIm was fabricated.

On the other hand, as the cylindrical outer mold 1, a steel cylindrical mold with outer diameter: 180 am x inner diameter: 100 mm x height: 130 m + * is prepared, and this steel cylindrical mold is attached to a steel plate substrate 6 as shown in FIG. Then, inside the above steel cylindrical mold, install the first pipe 2 made of steel pipe with outer diameter: 80 mm x inner diameter near 5 x height: 110 m, outer diameter: 30 mm x inner diameter: 26 u + x height. S:llO+sm
A second pipe 3 made of steel pipe 3, and a mandrel 5 made of round steel bar with a diameter of 28 mm x height = 11 mm are charged and installed concentrically.

Although it is preferable that the steel cylindrical mold, the first tube 2, the second tube 3, and the mandrel 5 be installed exactly concentrically, it is sufficient to install them almost concentrically.

The large-diameter Y-based oxide-filled coil is placed between the steel cylindrical mold that is the cylindrical outer mold 1 and the first steel pipe 2, and between the second steel pipe 3 and the mandrel 5. 4 and a small diameter Y-based oxide filled coil 4',
SiC powder having an average particle diameter of 2 μs was filled, and the container was further vibrated so that the SiC powder was sufficiently dense, and then the lid 8 was placed. The lid 8 may be made of cardboard.

The above-mentioned SiC powder is one of the most preferred powders as a pressure medium because it is difficult to solidify even when explosively compressed and is easy to handle.

After filling the above SiC powder and making M8, explosive (detonation speed:
2.300 m/sec) 9 is filled between the first steel pipe 2 and the second steel pipe 3, and is detonated by the detonator IO, causing the large diameter Y-based oxide filled coil 4 and the small diameter Y-based oxide filled coil 4 to explode. The material-filled coil 4' was simultaneously explosively compressed.

The large-diameter Y-type oxide-filled coil 4 and the small-diameter Y-type oxide-filled coil 4' that were explosively compressed were taken out and heat-treated in a furnace in an oxygen atmosphere at a temperature of 920°C and held for 24 hours to make the diameter larger. A Y-based oxide superconducting coil and a small-diameter Y-based oxide superconducting coil were fabricated, and the superconducting properties of these superconducting coils were measured and are shown in Table 1.

Example 2 As raw material powder, Bi with average particle size: 10- or less
Prepare O powder, Ca COa powder, S r COa powder, and CuO powder, and convert these powders into 0 powder:
53.4%, Ca COs powder: 11.5r COa
Powder: 1G, 9% and CuO powder: (more than % by weight)
This mixed powder was combined and mixed in the air at a temperature of 12%, S 18.2%, and then fired at 800°C for 12 hours to form a Bi-based oxide. The Bi-based oxide obtained by the firing process was then pulverized to produce a Bi-based oxide powder having an average particle size of 5 μs.

The above Bi-based oxide powder was heated to an inner diameter of 20 mm x wall thickness of 1.
5m+s
g A composite wire was produced.

The above Bi-based oxide-filled Ag composite wire is wound with an inner diameter of 9
Zero dragon's large diameter Bi-based oxide filled coil and inner diameter 210m
A small-diameter Bi-based oxide-filled coil of m was fabricated.

Example 1 The large diameter Bi-based oxide filled coil and the small diameter Bi-based oxide filled coil were charged as shown in FIG.
After explosive compression was carried out under exactly the same conditions as above, the coils were taken out and heat treated in an oxygen atmosphere at a temperature of 850°C for 15 hours.
We fabricated an oxide superconducting coil.

Next, the superconducting properties of these superconducting coils were measured, and the results are shown in Table 1.

Example 3 Raw material powders include 1g203 powder, Ca COa powder, and B a CO3 with an average particle size of 10 tln or less.
Prepare powder and CuO powder, and add 1g2 of these powders.
03 powder: 35.4%, Ca COa powder: 15.
5%, B a COa powder: 3 [1,6% and Cu
O powder: Blend and mix to have a composition of 18.5% (or more by weight), and then sinter this mixed powder in an oxygen atmosphere at a temperature of 800°C for 10 hours.
7g obtained by preparing oxide powder and firing it
The Tll-based oxide was pulverized to produce a Tll-based oxide powder with an average particle size of 5 nm.

Inner diameter: 20mm x Wall thickness: 1
．． A 5 mm × length + 200+++ proverbial Ag tube was filled with the material, and the filled Ag tube was swaged and then grooved to produce a Tl-based oxide-filled Ag composite wire with a diameter of 211 Il.

The inner diameter of the above Tl-based oxide-filled Ag composite wire is:
90mm large diameter Tl-based oxide filled coil and inner diameter: 1
A small-diameter Tfi-based oxide-filled coil with a diameter of 0 cm was fabricated.

The large-diameter Tl-based oxide-filled coil and the small-diameter Tg-based oxide-filled coil were charged as shown in FIG.
After explosive compression was carried out under exactly the same conditions as above, the coils were taken out and heat treated in an oxygen atmosphere at a temperature of 900°C for 3 hours to form large-diameter T, 17-based oxide superconducting coils and small-diameter T.
A g-based oxide superconducting coil was fabricated.

Next, the superconducting properties of these superconducting coils were measured, and the results are shown in Table 1.

When compared with the conventional superconducting coil shown, it can be seen that it has an extremely superior critical current density.

In addition, in these Examples 1 to 3, two of the first pipe and the second pipe
Although the case where two steel pipes are charged into a cylindrical outer mold is shown, the number of pipes is not limited to the above example and is generally two.
If n tubes (where n is a positive integer) are used, 20-1 superconducting oxide-filled coils can be explosively compressed simultaneously.

〔Effect of the invention〕

According to this invention, a plurality of superconducting coils having different diameters and having extremely high critical current densities that can be put to practical use can be simultaneously produced, which greatly contributes to the development of industry.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional elevational view showing a superconducting oxide-filled coil set in a cylindrical outer mold for explosive compression; Figure 2 is a cross-sectional view taken along line nn in Figure 1; Shape outer mold 2: TS tube 3: Second tube 4: Large diameter superconducting oxide filled coil 4': Small diameter superconducting oxide filled coil 5: Mandrel 6: Substrate 7; Pressure body 8: Lid

Claims (9)

[Claims] (1) Prepare a cylindrical outer mold, an even number of tubes having an outer diameter smaller than the inner diameter of the cylindrical outer mold, and a mandrel with a smaller diameter than the inner diameter of the smallest tube among the even number of tubes. , the even number of tubes and the mandrel are inserted concentrically into the cylindrical outer mold, between the mandrel and the tube, between the tubes and the tube, and between the tube and the cylindrical outer mold, Superconducting oxide powder filling A
g A coil obtained by winding a composite wire (hereinafter referred to as a coil) and a pressure medium are inserted so that the coil is embedded in the pressure medium, and an explosive is filled between the tubes. , by an explosive compression method characterized by explosively compressing and densifying the coil by detonating the explosive, and then heat-treating the coil that has been explosively compressed and densified in air or an oxygen atmosphere. Manufacturing method for superconducting coils. (2) a cylindrical outer mold; a first pipe having an outer diameter smaller than the inner diameter of the cylindrical outer mold; a second pipe having an outer diameter smaller than the inner diameter of the first pipe; and the second pipe. Prepare a mandrel with a smaller diameter than the inner diameter of and inserting the coil and pressure medium between the second pipe and the mandrel, respectively, so that the coil is embedded in the pressure medium,
According to the explosive compression method according to claim 1, further comprising: filling an explosive between the first tube and the second tube, and detonating the explosive to explosively compress the coil to increase its density. Manufacturing method for superconducting coils. (3) The method for manufacturing a superconducting coil by an explosive compression method according to claim 1 or 2, wherein the cylindrical outer mold is a cylindrical mold. (4) The method for manufacturing a superconducting coil by the explosive compression method according to claim 1 or 2, wherein the cylindrical outer mold is a cylindrical reinforced concrete mold. (5) The pressure medium has an average particle size of 1 to 1.000 μm.
3. The method for producing a superconducting coil by the explosive compression method according to claim 1, wherein the powder is difficult to solidify by explosive compression. (6) The superconducting oxide powder includes a rare earth element containing Y,
6. The method for producing a superconducting coil by an explosive compression method according to claim 1, 2, 3, 4, or 5, wherein the powder is a compound powder having a perovskite structure consisting of an alkaline earth metal, Cu, and oxygen. (7) The superconducting oxide powder is Bi-Ca-Sr-C
Claim 1, characterized in that the powder is a u-O based oxide powder.
A method for producing a superconducting coil by the explosive compression method according to 2, 3, 4 or 5. (8) The superconducting oxide powder is Tl-Ca-Ba-C
Claim 1, characterized in that the powder is a u-O based oxide powder.
A method for producing a superconducting coil by the explosive compression method according to 2, 3, 4 or 5. (9) The method for manufacturing a superconducting coil by an explosive compression method according to claim 1 or 2, wherein the pressure medium is a fluid.