JPH0195413A - Manufacture of oxide superconducting wire - Google Patents

Abstract

PURPOSE:To enable obtaining a long-sized oxide superconducting wire of tape shape displaying uniform superconducting characteristics in a length-wise direction by feeding a material between metal tapes opposing each other, and subjecting the tapes to heat treatment in atmosphere containing oxygen via pressure molding. CONSTITUTION:The surface of a metal tape B opposite to another tape A is applied with the flame fused substance of a powder material D to the predetermined thickness before reaching a space between molding rolls 3 and 3. The powder of an oxide superconductor, a raw material powder containing an element constituting an oxide superconductor or the mixed powder thereof and the like are used as the powder material D. The metal tapes B and A are overlaid on each other via the flame fused substance and pressure molded with the molding rolls 3 and 3, thereby forming a laminated tape E. This laminated tape E is fed to the inside of a heat furnace 4 and subjected to heat treatment in atmosphere containing oxygen. According to the aforesaid process, oxygen feed can be efficiently made to the powder material D exposed at least from both length-wise edges of the laminated tape E. A long-sized superconducting wire C, therefore, can be manufactured, displaying uniform superconducting characteristics in a length-wise direction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing an oxide superconducting wire that can be used, for example, in magnet coils for nuclear magnetic resonance imaging devices, particle accelerators, and the like.

[Conventional technology]

Recently, various oxide-based superconductors are being discovered whose critical temperature for transitioning from a normal conducting state to a superconducting state is higher than the temperature of liquid nitrogen. Since such oxide superconductors can be used under much more advantageous conditions than conventional alloy-based or intermetallic compound-based superconductors that require the use of liquid helium for cooling, they are extremely promising for practical use. It is considered a superconducting material.

By the way, in order to manufacture an oxide superconducting wire equipped with such an oxide superconductor, for example, a raw material powder containing the elements constituting the oxide superconductor is filled into a noble metal vibrator such as silver, and then this noble metal pipe is A method is known in which the entire wire is subjected to diameter reduction processing and then heat treated in an oxygen atmosphere. According to this method, oxygen can be supplied to the oxide superconductor in the wire through the sheath made of a noble metal such as silver that has oxygen permeability during heat treatment, so it is possible to manufacture an oxide superconducting wire that exhibits good superconducting properties. there is a possibility.

[Problem that the invention seeks to solve]

However, in this method, the amount of oxygen that is directly supplied to the superconductor from the terminal portion of the superconducting wire is greater than the amount of oxygen that is supplied to the superconductor through the sheath portion made of a noble metal such as silver. Therefore, when obtaining a long superconducting wire, for example, the critical current (Ic) at the center of the superconducting wire
There may be a large difference between the Ic value and the Ic value at the terminal portion of the superconducting wire, making it difficult to obtain a long superconducting wire that exhibits uniform superconducting properties in the longitudinal direction. Incidentally, when the present inventors measured the IC value of the superconducting wire obtained by the above method, they found that the IC value at the end portion of the superconducting wire was about 1/2 to 1/3 of the Ic value at the central portion. We have obtained experimental results.

[Means for solving problems]

Therefore, in this invention, between the metal tapes facing each other,
By supplying a material consisting of at least one of an oxide superconductor and a raw material containing elements constituting the oxide superconductor, then press-molding it into a laminated tape, and then heat-treating it in an atmosphere containing oxygen. , oxygen is supplied to the material exposed from at least both side edge portions along the longitudinal direction of the laminated tape, so that a long tape-shaped oxide superconducting wire exhibiting uniform superconducting properties in the longitudinal direction can be manufactured.
I strained it.

The present invention will be described in detail below.

FIG. 1 shows an example of a manufacturing apparatus suitably used to carry out the manufacturing method of the present invention.

The manufacturing apparatus of this example is capable of manufacturing long, plate-shaped metal tapes A and I3 made of metals such as copper, nickel, and aluminum, and precious metals having oxygen permeability such as silver, platinum, and gold in the direction of arrow P in the figure. The tape-shaped superconducting wire C is manufactured continuously while traveling to U゛.This product is a delivery roll! ,
2, forming rolls 3.3, and heating furnace 4.

The metal tapes ASB are each sent out at a constant speed from the delivery rolls 112, and then sent between forming rolls 3 and 3 with both metal tapes A1B facing each other. The surface facing the tape A is coated with a sprayed material powder to a predetermined thickness by a thermal spraying device (not shown in this example) before reaching between the forming rolls 3.3.

Here, as the above-mentioned material powder, oxide superconductor powder, raw material powder containing elements constituting the oxide superconductor, or a mixed powder thereof is used. The above oxide superconductor may be AB-Cu-0 type or A-
B-Cu-0-X system (A is Sc, Y, La, Yb
Represents one or more elements of group ma of the periodic table, such as B (more e
, Sr, Ba etc.] Ming? Table 1 represents one or more Ha group elements, and X is F, Cff, Br.

Represents one or more halogen group elements of the 1st class. ) are used. The composition ratio of each element in such an oxide superconductor varies depending on the element used, the type of oxide superconductor, etc., but for example, in Y-Ba-Cu-0 series, the element weight ratio Yl, Ba 2. Cu 3,0 7, and Y-Ba-Cu-0-F type Y-Ba-Cu-0-F based element weight ratio Y 1. Ba 2. Cu3.0 7. It is assumed to be F'2.

In addition, as the raw material powder containing the elements constituting the oxide superconductor, powders of Ha group elements of the periodic table and m-th group elements of the periodic table are used.
A mixed powder consisting of a group A element powder and a copper oxide powder, a powder obtained by calcining this mixed powder, a mixed powder consisting of the above mixed powder and a calcined powder, etc. are used. The powders used in Ha group of the periodic table include Be, Sr, Mg, B
Compound powders or alloy powders such as carbonate powders, oxide powders, chloride powders, sulfide powders, and fluoride powders of each element of a and Ra are used. Also, periodic table number rll
Group a element powders include Sc, Y, La, Ce, Pr,
Nd.

Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, T
Compound powders or alloy powders such as oxide powders, carbonate powders, chloride powders, sulfide powders, and fluoride powders of the elements m, Yb, and Lu are used. Furthermore, as copper oxide powder, CuO, CuyO, Cu30t, CUao
Copper oxide powder such as y is used.

The mixing ratio of these powders is determined so that the above-mentioned oxide superconductor can be obtained when this mixed powder is heat treated in a subsequent step. Further, the mixing ratio in the mixture of the above-mentioned mixed powder and the above-mentioned oxide superconductor powder is not particularly limited, and may be determined as appropriate in consideration of the characteristics of the obtained oxide superconductor. .

Next, the metal tape B coated with the sprayed material powder and the other metal tape A are overlapped with the sprayed material in between, and are pressure-formed by forming rolls 3.3 to form a laminated layer. It is called Tape E. Since this laminated tape E is made by sandwiching the material powder between the metal tapes A and B, the material powder D h< ing.

Next, this laminated tape E is sent into the heating furnace 4 on the downstream side and is heat-treated in an atmosphere containing oxygen. The conditions for this heat treatment are determined depending on the type of material powder sandwiched between the laminated tapes E, the characteristics required of the resulting superconducting wire C, and the like. For example, if the material powder is a raw material powder containing elements constituting an oxide superconductor, the temperature is 800 to 1100°C, 1
~100 hours, and if the material powder is an oxide superconductor powder, the crystal transformation temperature is 400~600℃, i
It is approximately 100 hours. The oxygen-containing atmosphere for this heat treatment is determined depending on the type of oxide superconductor in the superconducting wire C, but usually oxygen gas or a mixed gas of oxygen gas and halogen gas is used.

Then, by heat treatment in such an oxygen-containing atmosphere, oxygen is directly supplied to the material powder exposed from both side edge portions along the longitudinal direction of the laminated tape E, so that the material powder is transferred to the raw material body. If it is a powder, the material powder does not exhibit good superconducting properties because the elements of group Ma of the periodic table, the group Ha of the periodic table, the copper element, and oxygen react with each other and do not exhibit good superconducting properties. It becomes a synthetic oxide superconductor,
Moreover, if the material powder is already an oxide superconductor powder, its superconducting properties will be further improved.

Therefore, by such heat treatment, the laminated tape E becomes a superconducting wire C exhibiting good superconducting properties.

This superconducting wire C is in the form of a tape as shown in FIG. 2, in which an oxide superconductor layer F is formed between metal tapes A and B facing each other.

Next, the superconducting wire C obtained by such heat treatment is sent further downstream by a feed roll 5.5, and then wound onto a winding roll (not shown).

According to such a manufacturing method, a material powder consisting of at least one of an oxide superconductor and a raw material containing an element constituting the oxide superconductor is supplied between the metal tapes A13 facing each other, and then After pressure forming with forming roll 3.3 to obtain a laminated tape E, this laminated tape E
Since the heat treatment was performed in an atmosphere containing oxygen, oxygen can be efficiently supplied to the material powder exposed from at least both side edge portions along the longitudinal direction of the laminated tape E, so that it is uniform in the longitudinal direction. A long superconducting wire C that does not exhibit superconducting properties can be manufactured.

FIG. 3 shows another example of a manufacturing apparatus suitably used for carrying out the manufacturing method of the present invention. The manufacturing equipment of this example includes a delivery roll 6 for feeding reinforcing tape G made of a material with high mechanical strength such as 5US (stainless steel) between metal tapes A and B, and a material on both sides of the tape G. A thermal spraying device 7 for applying a powder spray material is provided. If this manufacturing device is used, it is possible to reinforce the laminated tape E or the superconducting wire C by feeding the reinforcing tape G sent out by the feeding roll 6 between the metal tapes A13, and also to reinforce the laminated tape E or the superconducting wire C using the thermal spraying device 7. Reinforcement tape G with sprayed material applied on both sides
By feeding the metal tapes A and B between the metal tapes A and B,
In between, material powder can be easily and efficiently supplied. In this case, as shown in FIG. 4, a superconducting wire C having two oxide superconductor layers F between the metal tapes ASB can be manufactured.

In the above two embodiments, sprayed material powder was used as the material to be supplied between the metal tapes A13, but the material is not limited to this, and for example, oxalate of the element constituting the two oxide superconductors mentioned above It is also possible to use a slurry obtained by precipitating by a coprecipitation method. Further, as a method for supplying the material to the surface of the metal tape, a thin film forming method such as a CVD (chemical vapor deposition) method, a sputtering method, or an M[3E (molecular beam epitaxy) method] may be used.

Furthermore, the above material powder is used as it is for metal tape A%B.
In the case where the metal tape A1B is supplied between the two, it is desirable to use a metal tape having, for example, a U-shaped cross section or a circular cross section, respectively. FIG. 5 shows an example of a superconducting wire C manufactured using metal tapes A and B having a U-shaped cross section. When manufacturing such a superconducting wire C, by slightly increasing the amount of material powder supplied between the metal tapes A and B, it is possible to reduce the volume of the material powder due to pressure forming. A gap is formed between metal tapes A and B,
Material powder can be exposed to the outside.

In this manufacturing method, since the metal tapes A and B are U-shaped in cross section, it is possible to reduce the amount of material powder spilling out from the gap formed between the metal tapes A and B. Since a relatively large amount of material powder can be held between the layers, a superconducting wire C having a large oxide superconductor layer F can be manufactured. Therefore, in this case,
There is an advantage that a superconducting wire C that can flow a large current can be manufactured.

Examples are shown below.

〔Example〕

A tape-shaped superconducting wire was produced using the production apparatus shown in FIG. The metal tape has a thickness of 0.2cm and a width of 10mm.
The material powder used was Y, 0. A mixed powder consisting of powder and BaC0 powder and powder and CuO powder was used. Next, this mixed powder was supplied between the metal tapes mentioned above, and then pressure-molded with forming rolls to a thickness of 13 mm.
No. 11 laminated tape was obtained. Next, this laminated tape is introduced into a heating furnace and the laminated tape is heated to 900°C in an oxygen atmosphere.
After heat treatment for 24 hours, the wire was slowly cooled to 400° C., and then cooled to room temperature to obtain the desired tape-shaped superconducting wire.

When the critical current density (Jc) of this superconducting wire was measured at liquid nitrogen temperature (77K), it was found to be 700A/CJI.
''.For comparison, a superconductor was obtained by filling a silver pipe with the above mixed powder, reducing the diameter of the entire silver pipe, and heat-treating it at 900°C for 24 hours in an oxygen atmosphere. When I measured Jc for the line in 7.7, it was 200
~300A/Cff2.

〔Effect of the invention〕

As explained above, according to the present invention, at least one of the raw material bodies exposed from at least both side edge portions along the longitudinal direction of the laminated tape and containing an oxide superconductor and an element constituting the oxide superconductor Since oxygen can be efficiently supplied to the material made of the material, it is possible to manufacture a long tape-shaped superconducting wire that exhibits uniform superconducting properties in the longitudinal direction.

The superconducting wire manufactured by this manufacturing method has a high critical current (IC) value and a large critical current density ( Jc) value. Furthermore, since this superconducting wire is manufactured by laminating flexible metal tapes, it can be suitably used, for example, in magnetic coils for nuclear magnetic resonance imaging devices, particle accelerators, and the like.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an example of a manufacturing apparatus suitably used in carrying out the manufacturing method of the present invention, and FIG.
The first superconducting wire manufactured by the manufacturing method of the present invention
FIG. 3 is a schematic configuration diagram showing another example of a manufacturing apparatus suitably used in carrying out the manufacturing method of the present invention, and FIG. 4 is a perspective view showing an example of the manufacturing method of the present invention. FIG. 5 is a perspective view showing a third example of a superconducting wire manufactured by the manufacturing method of the present invention. A, B... Metal tape, C... Oxide superconducting wire, D... Material powder, E... Laminated tape, F... Oxide superconductor layer.

Claims (1)

[Claims] A material consisting of at least one of an oxide superconductor and a raw material containing elements constituting the oxide superconductor is supplied between the metal tapes facing each other, and then pressure-formed to form a laminated tape, and then oxygen is removed. A method for producing an oxide superconducting wire, the method comprising heat-treating in an atmosphere containing oxide superconducting wire.