JP3534428B2 - Manufacturing method of oxide high temperature superconducting wire - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an oxide high temperature superconducting wire, and more particularly to an improvement for producing a high performance and longer oxide high temperature superconducting wire having excellent bending strain characteristics. It is a thing.

[0002]

2. Description of the Related Art In recent years, as a superconducting material exhibiting a higher critical temperature, a ceramic material, that is, an oxide high temperature superconducting material has been attracting attention.

Among them, yttrium type has a high critical temperature of about 90 K, bismuth type has a high temperature of 110 K, and thallium type has a high critical temperature of about 120 K, so that they are expected to be put into practical use.

As a method for obtaining a long oxide high-temperature superconducting wire using such an oxide high-temperature superconductor or an oxide high-temperature superconducting wire such as an oxide high-temperature superconducting pattern wired on an appropriate substrate. A method of producing an oxide high-temperature superconducting wire in which the raw material powder is covered with a metal sheath and then heat-treated to convert the raw material powder into a superconductor and the superconductor is covered with the metal sheath is known. Has been.

In order to apply the above-mentioned high-temperature oxide superconducting wire to cables and magnets, it is necessary to have a high critical current density in addition to a high critical temperature. In particular, not only must the required critical current density be ensured in the magnetic field used, but also a high critical current density under the strain used.

Therefore, in order to produce a long oxide high temperature superconducting wire which has excellent bending strain characteristics even after heat treatment and can secure a high critical current density even under the strain used, a raw material powder is used. After refilling a plurality of metal-coated superconducting wires covered with a metal sheath into a metal pipe and drawing it to reduce the diameter, a compressive load is applied to the metal pipe in the thickness direction. A method has been developed for producing a multifilamentary oxide superconducting wire by subjecting a raw material powder to a superconductor by subjecting it to a tape-like deformation by subjecting it to plastic working and subjecting it to heat treatment.

[0007]

However, in the above-mentioned manufacturing method, although an oxide multi-core superconducting wire having excellent strain characteristics can be obtained, a step of fitting a plurality of metal-coated superconducting wires into a metal pipe again is required. In order to take
As shown in (b), the metal coating 1 on the outermost periphery of the final wire
There was a tendency that the thickness of 0 increased and the occupation rate of the superconductor 20 in the entire cross section of the wire rod was kept low.

Further, the above-mentioned manufacturing method has a problem that the length of the finally obtained wire rod is limited by the starting length and the starting diameter of the metal pipe into which the metal-coated wire rod is fitted. Therefore, if a metal pipe with a larger starting length or starting diameter is used, the workability at the time of drawing a metal pipe in which a plurality of metal-coated wire rods are fitted by the extrusion processing method becomes large, and therefore the extrusion processing is performed. It was essential to use large-scale and expensive equipment.

The present invention has been made in order to solve the above-mentioned problems of the conventional manufacturing method, and has excellent strain characteristics during use, and the critical current density per total cross-sectional area of the wire is further improved. Another object of the present invention is to provide a method capable of easily producing a high-performance and long-length oxide multi-core superconducting wire with a simple device.

[0010]

A method of manufacturing an oxide high temperature superconducting wire according to the present invention comprises first preparing a plurality of wires in which an oxide superconductor or a raw material thereof is coated with a metal along a longitudinal direction. In the state of bundling a plurality of wire rods, the second step of joining the plurality of wire rods by adhering the metal coatings between the wire rods and the plastic working of the joined wire rods Third step of obtaining a long wire and fourth step of obtaining a multi-core superconducting wire in which a sintered oxide superconductor is formed along the longitudinal direction by subjecting the long wire to a heat treatment It is characterized by having and.

In the present invention, before the fourth step, a step of assembling a plurality of long wire rods obtained in the third step and a step of bundling the plurality of wire rods with each other are performed. The method may further include a step of joining the plurality of assembled wire rods by adhering the coatings together, and a step of subjecting the joined plurality of wire rods to plastic working to obtain a long wire rod.

In the present invention, bismuth (Bi), thallium (Tl), and yttrium (Y) are used as the superconductor and the raw material for the oxide superconductor in the first step.
Although it is possible to use a bismuth-based material, bismuth (B) is particularly preferable because of the ease of lengthening the wire and the high critical current density.
It is more preferable to use i) -based superconductor.

Further, silver or a silver alloy is preferably used as the metal for coating the oxide superconductor and the raw material thereof.

The metal-coated oxide high-temperature superconducting wire is heat-treated after being plastically worked into a rectangular tape shape by the gas adsorbed to the oxide superconductor and the powder of the raw material or the gas remaining in the metal coating in the manufacturing process. It may sometimes expand or partially rupture. When a wire rod that has undergone such expansion or partial rupture is used as a conductor of a magnet or a cable, the characteristics are deteriorated.

Therefore, in the first step of the present invention, in order to prepare a wire rod in which the oxide superconductor or the raw material thereof is coated with metal along the longitudinal direction, the oxide superconductor filled in the metal sheath is prepared. Alternatively, it is desirable that the raw material powder be subjected to sufficient deaeration by heat treatment or the like in advance. In addition, after filling the metal sheath with the oxide superconductor or the powder of the raw material thereof, the both sides of the metal sheath are covered and the gas remaining inside the metal sheath is sufficiently degassed by degassing by vacuum exhaust, Furthermore, it is desirable to seal both ends of the metal sheath to prevent re-adsorption of gas thereafter.

Further, it is desirable that the oxide superconductor or the powder of the raw material thereof, which is filled in the metal sheath, has an average particle size reduced to a submicron unit. As a result, the plastic workability of the wire can be improved.

In the step of joining a plurality of wire rods of the present invention, the type, the number and the arrangement of the wire rods to be bundled can be arbitrarily determined. For example, it is possible to assemble a plurality of metal-coated single-core wires in which the superconductor or its raw material is coated with a metal.

In this case, for example, as shown in FIG.
You may bundle only the single core strand 1 with the same ratio of a metal coating.

Further, single-core element wires having different ratios of metal coating may be combined and bundled. For example, as shown in FIG. 5, the processing characteristics can be improved by arranging an arbitrary number of single-core strands 3 having a large proportion of metal coating in the outermost peripheral portion.

However, in order to secure better working characteristics, the metal element wire 2 is provided as a part of the aggregate structure within a range in which the reduction of the occupation ratio of the superconductor in the final wire can be allowed, for example, as shown in FIG. As shown in FIG. 3 and FIG. 4, any number can be arranged at the outermost peripheral portion, the central portion, or any radial position.

Further, the metal-coated single-core wire and the metal-coated multicore wire may be combined and bundled. For example, in FIG.
As shown in, the metal-coated single-core wire 1 can be arranged in the central part and the metal-coated multi-core wire 4 can be arranged in an arbitrary number in the outermost peripheral part.

In FIGS. 1 to 6, the white portion indicates the metal coating and the black portion indicates the oxide superconductor. Here, an example in which 91 wire rods are bundled is illustrated, but the number of bundled wires is arbitrary.

In the step of joining a plurality of wire rods of the present invention, the cross-sectional shape of the wire rods to be bundled is processed into a hexagonal shape capable of surface contact from the point of adhering the metal coatings of the wire rods between the wire rods. However, the shape may be a circular shape that allows line contact, and is not particularly limited.

In the step of joining a plurality of assembled wire rods of the present invention, the method of joining a plurality of wire rods in a bundled state is not particularly limited, but a method of bonding metal coatings by thermal diffusion or a bundle A method of bonding by applying hot wire drawing processing to a plurality of wire rods can be applied.

In the step of joining a plurality of wire rods of the present invention, the degree of joining between the plurality of wire rods affects the plastic workability in the next step, the soundness of the shape of the superconducting filament in the final wire rod, and the superconducting properties.

For example, if the degree of joining between a plurality of wire rods is insufficient, and if a large stress is suddenly applied to the wire rod during wire drawing, the wire rods bundled during the wire cutting will be broken apart. Otherwise, wire breakage occurs and it becomes difficult to obtain a sound wire drawing material.

From the above, the extent to which the metal coatings are adhered to each other between the wire rods is such that at least the plurality of wire rods joined in the next step can withstand the drawing tension and undergo plastic working, and during wire drawing. It is required that the superconducting filaments are not damaged.

From this point of view, more specifically, for example, a tape made of heat-resistant fibers by gathering a plurality of wire rods and then tightly bundling them, more specifically, a quartz glass tape By spirally winding while shifting in the longitudinal direction of the wire rod, in a mechanical contact state, by applying heat treatment at 500 to 800 ° C., the metal coatings covering the surface of each wire rod are thermally diffused, It is preferable to join a plurality of wires.

As a simpler method, after a plurality of wire rods are bundled, hot wire drawing is continuously performed to bond the wire rods with a fresh metal surface.
That is, by adopting this step, sufficient joining of the wire rods and plastic working of the joined wire rods are simultaneously performed.

In the present invention, the step of subjecting a plurality of joined wire rods to plastic working to obtain a long wire rod includes a wire drawing process for drawing a plurality of integrated wire rods into a long wire and a long wire drawing. Rolling processing for deforming the drawn multifilamentary wire into a rectangular tape shape can be included.

In the process of obtaining a long wire by applying the plastic working of the present invention, in order to densify and improve the orientation of the superconductor, it is rolled into a long multifilamentary wire which has been drawn. It is preferable to further heat-treat after processing and deforming into a rectangular tape shape. In this case, it is more preferable to repeat the rolling process and the heat treatment at least twice. However, when rolling a long multifilamentary wire,
From the viewpoint of improving superconducting properties and productivity in wire production, it is preferable to complete the rolling operation once.

Further, at least 1 to be applied to a long multifilamentary wire
In the rolling process for the second time, it is preferable that the ratio of the thickness reduction amount to the thickness of the wire rod before rolling, that is, the rolling reduction is 70% or more. By setting the rolling reduction of the rolling process to 70% or more, it is possible to perform the deformation process on the outermost peripheral portion of the metal-coated thin multi-core superconducting wire without causing the side portion to burst.

[0033]

In the method for producing an oxide high-temperature superconducting wire according to the present invention, a plurality of wires in which the oxide superconductor or the raw material thereof is coated with metal along the longitudinal direction are prepared, and the plurality of wires are bundled. In, the metal coatings are adhered between the wire rods. In the present invention, it is possible to integrally join a plurality of wire rods without taking the step of fitting a plurality of metal-coated wire rods in a metal pipe as in the conventional case.

In the present invention, when producing a metal-coated multi-core superconducting wire, there is no restriction on the length and the number of the wires to be bundled as in the conventional case. Therefore, the length of the final wire is not limited by the starting length and the starting diameter of the metal pipe as in the conventional case. In the present invention, a long wire can be manufactured arbitrarily according to the number and length of metal-coated superconducting wires to be joined.

As a result, it is possible to provide a long wire which cannot be obtained by the conventional method which is restricted by the starting length and the starting diameter of the metal pipe.

Further, in the method for producing a high-temperature oxide superconducting wire according to the present invention, when a plurality of wires are joined in the second step, a decrease in the occupation ratio of the superconductor in the final wire can be allowed, For example, as described above, it is possible to arrange, in a part of the bundled wires, a metal wire having excellent plastic working characteristics or a wire having a large proportion of the metal coating at any position and at any number. Therefore, it is possible to perform plastic working on a plurality of joined wire rods while ensuring good working characteristics without providing a thick metal coating on the outermost peripheral portion of the wire rod.

As a result, as shown in FIG. 7 (a), the thickness of the metal coating 10 at the outermost peripheral portion of the final wire is kept extremely thin, and the superconductor 2 occupies the entire cross section of the wire by that amount.
It is possible to obtain a metal-coated multi-core superconducting wire having an increased occupancy rate of 0. Therefore, even after the heat treatment, it is possible to further improve the critical current density per total cross-sectional area of the metal-coated multi-core superconducting wire having excellent bending strain characteristics, that is, the overall Jc.

Further, in the present invention, a plurality of wire rods obtained by the first to third steps can be bundled to produce a more multi-core oxide superconducting wire rod.

In this case, when the wires are bundled, the metal coatings are adhered between the wires without using a metal pipe as in the conventional case. Therefore, it is possible to perform plastic working together with the minimum necessary metal coating material without using an extra metal material when joining a plurality of wires.

On the other hand, in the conventional method, it is necessary to use a metal pipe every time the wire rods are bundled in order to have multiple cores. In the conventional method, the diameter of the assembled wire increases due to the metal pipe each time the multi-core process is repeated, which makes processing difficult. Therefore, in the conventional method, the thickness of the metal coating on the outermost peripheral portion of the wire is increased by the amount of the metal pipe used, and the workability is inevitably increased.

On the other hand, in the method of the present invention, since no metal pipe is used at all, it is possible to obtain an oxide superconducting wire having a multi-core structure with a low workability and without increasing the thickness of the metal coating.

As described above, according to the present invention, it is not necessary to use a large-scale and expensive apparatus to perform a predetermined plastic working on a plurality of joined wire rods as in the conventional method, and it is easier and cheaper. This can be easily realized even by using the device.

[0043]

【Example】

Example I Example 1 Bi ₂ O ₃ , PbO, SrCO ₃ , CaCO ₃ and C
Using uO, Bi: Pb: Sr: Ca: Cu = 1.8
These were blended so that the composition ratio was 0: 0.40: 2.01: 2.21: 3.02. This blended powder was heated in air at 700 ° C. for 12 hours and then at 80 ° C.
Heat treatment was performed at 0 ° C. for 8 hours. Reduced pressure atmosphere 1 Torr
In, the heat treatment was performed at 760 ° C. for 8 hours. After each heat treatment, pulverization was performed. The powder obtained through such heat treatment was further pulverized by a ball mill to obtain a powder having an average particle size of submicron. This powder was degassed by heat treatment at 760 ° C. for 10 minutes in a reduced pressure atmosphere.

After degassing, the obtained powder was filled in a silver pipe having an outer diameter of 6 mm and a thickness of 0.75 mm, the lid was covered with a grooved silver jig, and then vacuum was applied at 2 × 10 ⁻⁵ Torr for 10 hours. After pulling, both ends were electron beam welded. After this silver pipe was drawn to a diameter of 2.91 mm, it was drawn with regular hexagonal soybean having an opposite side length of 2.44 mm. This obtained the wire material.

Sixty-one hexagonal wire rods obtained as described above were tightly bundled and spirally wound with quartz glass fibers for close contact, and then in air, at 800 ° C.
After heat treatment for 10 hours, the silver coating was diffusion bonded and integrated.

The wire thus obtained was drawn once to a diameter of 1.02 mm at a cross-section reduction rate of about 20.7%. The workability was good without breaking during wire drawing.

Further, the drawn wire obtained was processed into a flat tape having a thickness of 0.255 mm by one flat roll rolling operation, and then heat-treated at 845 ° C. for 50 hours in the atmosphere. After that, one more flat roll rolling operation resulted in 0.22
It was processed into a rectangular tape having a thickness of 2 mm. The width of the tape material was 2.70 mm. Furthermore, after performing a heat treatment at 840 ° C. for 50 hours in the atmosphere, the critical current of the entire length was measured in a state of being immersed in liquid nitrogen, and the specific resistance was 10 ^−13.
It was 36.0 A in terms of Ω · m definition.

Example 2 A powder was prepared as in Example 1. However, in Example 2, the powder was not degassed. Using such powder, a multi-core superconducting wire is manufactured in the same manner as in Example 1,
The superconducting property was evaluated.

When the critical current of the entire length was measured in the state of being immersed in liquid nitrogen, the specific resistance was ^10.sup.-13 .OMEGA..multidot.m.
It was 0A.

Example 3 A powder was prepared in the same manner as in Example 1. For this powder,
Degassing was performed by heat treatment at 800 ° C. for 10 minutes in a reduced pressure atmosphere.

In Example 3, the obtained powder was filled in a silver pipe having an outer diameter of 6 mm and a thickness of 0.75 mm, and then vacuum evacuation and sealing of both ends of the pipe were not performed.

After such a silver pipe was drawn to a diameter of 2.91 mm, it was further drawn with regular hexagonal soybean having a length of the opposite side of 2.44 mm. Then, a multifilamentary wire was prepared in the same manner as in Example 1 and evaluated for superconducting properties.

When the critical current of the entire length was measured in the state of being immersed in liquid nitrogen, the specific resistance was ^18.sup.-13 .OMEGA.m.
It was 0A.

Example 4 A powder was prepared in the same manner as in Example 1. However, in Example 4, a coarse powder having an average particle size of 5 μm was obtained by shortening the ball mill crushing time after performing heat treatment at 760 ° C. for 8 hours in a reduced pressure atmosphere of 1 Torr in the air. Using such a powder, the opposite side length was 2.4 in the same manner as in Example 1.
When we tried to wire-draw a 61-core wire rod with 61 hexagonal-shaped wire rods of 4 mm integrated at a cross-section reduction rate of 20.7%, we started to break from a diameter of 5.83 mm and a diameter of 1.02 m.
The wire could not be drawn up to m.

Example 5 (Conventional Example) The powder obtained in the same manner as in Example 1 was used in a reduced pressure atmosphere.
After degassing by heat treatment at 60 ℃ for 10 minutes, outer diameter is 6m
m, 0.75 mm thick silver pipe filled, diameter 2.9
After wire drawing was performed to 1 mm, wire drawing was further performed with regular hexagonal soybean having opposite sides of 2.44 mm. This obtained the wire material.

With respect to the hexagonal wire rod thus obtained, 61 pieces were again filled in the silver pipe,
Wire drawing is performed up to a diameter of 20.6 mm, and the temperature is 800 ° C in the atmosphere
A heat treatment was applied for 10 hours at 10 ° C. to diffusion-bond the silver coating.
The cross-section reduction rate of the wire thus obtained is about 2
Wire drawing was performed at 0.7% to a diameter of 1.02 mm.

Further, the drawn wire material was processed into a flat tape having a thickness of 0.255 mm by one flat roll rolling operation, and then heat-treated in the air at 845 ° C. for 50 hours. After that, it was further processed into a flat tape having a thickness of 0.222 mm by one flat roll rolling operation. The width of the tape material is 2.7
It was 0 mm. Furthermore, after performing a heat treatment at 840 ° C. for 50 hours in the air, the critical current of the entire length was measured in a state of being immersed in liquid nitrogen, and the specific resistance was 16.4 A as defined by 10 ⁻¹³ Ω · m.

The multifilamentary superconducting wires obtained in Examples 1, 2, 3, and 5 described above were embedded in an epoxy resin and the cross-sectional areas of silver and superconductor (hereinafter abbreviated as S _Ag and S _sc , respectively). Was measured by image processing to calculate the critical current density of the superconductor (hereinafter abbreviated as Jc) and the critical current density of the entire superconducting wire (hereinafter abbreviated as Jc), and the results are shown in Table 1.

[0059]

[Table 1]

As is clear from Table 1, Examples 1 to 5
From the results of the above, compared with the case where the metal-coated wire rod is re-fitted to the silver pipe, in the case where the silver coating of the metal-coated wire rod is integrated by diffusion bonding, the occupancy ratio of the silver coating in the final wire is suppressed to be small. It can be seen that the occupation rate of the superconductor is further increased. The overall Jc of the multifilamentary superconducting wire of Example 1 is more than twice the overall Jc of the multifilamentary superconducting wire of Example 5 (conventional example), and it can be seen that more than twice the current can flow in the same space.

When the method of diffusing and joining the silver coatings of the metal-coated wire rods to integrate them is adopted, the thickness of the metal coating that covers the outermost peripheral portion of the wire rod becomes thin. When the gas remaining in the superconducting powder and the metal coating is sufficiently degassed as in Example 1, expansion or partial rupture of the tape material does not occur during sintering after rolling. It can be seen that the superconducting property can be further improved.

Further, from the results of Examples 1 to 4, it is understood that if the average particle size of the superconducting powder to be filled is made finer to the submicron unit, good wire drawability can be secured.

Example II Example 1 A powder obtained by degassing in the same manner as in Example 1 of Example I was used to obtain an outer diameter of 68 mm and a thickness of 8.5 m as shown in FIG.
It was filled in a silver container of m and capped. Furthermore, 2 × 10 ^-5 T
After vacuuming at orr for 10 hours, both ends were electron beam welded.

Next, this silver container was subjected to hydrostatic extrusion at a room temperature to a diameter of 30 mm by using a hydrostatic extruder having an extrusion force of 400 tons. Then, after wire drawing to a diameter of 2.91 mm, wire drawing was further performed with regular hexagonal soybean having an opposite side length of 2.44 mm to obtain a 110 m long hexagonal superconducting element wire.

With respect to the hexagonal wire rods thus obtained, 61 wires were tightly bundled, and quartz glass fibers were spirally wound around them to make them adhere to each other.
Using a continuous heat treatment furnace, heat treatment is performed in the air at 800 ° C so that the net heat treatment time of each part of the wire is 10 hours,
The silver coating was diffusion bonded and integrated. The wire rod thus obtained had a cross-section reduction rate of about 20.7% once and a diameter of 1.
Wire drawing was performed up to 02 mm. There was no breakage during wire drawing, and workability was good. In this way, a 42-km single-length multicore superconducting wire was produced.

Further, after the drawn wire material was processed into a flat tape having a thickness of 0.255 mm by one flat roll rolling operation,
Twenty-two pieces of 100m material are cut out at 2km intervals and 845 in the atmosphere
A heat treatment was performed at 50 ° C. for 50 hours. After that, when the full-length critical current was measured in a state of being immersed in liquid nitrogen, 22 average critical currents were 11. with a specific resistance of 10 ⁻¹³ Ω · m.
The standard deviation was 0A and the standard deviation was 1A.

After that, it was further processed into a flat tape having a thickness of 0.222 mm by one flat roll rolling operation. The width of the tape material was 2.70 mm. Then, in the atmosphere 84
After performing a heat treatment at 0 ° C. for 50 hours, the full-length critical current was measured while immersed in liquid nitrogen.
22 average critical current is 33.0 with 0 ^-13 Ω · m definition
A, the standard deviation was 2A, showing uniform characteristics. Table 2 shows Jc, which is the quotient of the critical current determined by the definition of the specific resistance of 10 ^-13 Ω · m, divided by the cross-sectional area of the superconductor and the quotient of the overall wire, which is the quotient Jc. .

Example 2 Using a 42-km single-length multi-core superconducting wire produced by the same method as in Example 1, rolling with a flat roll was attempted according to the following pass schedule.

In Example 2, the wire-drawn material was processed into a thickness of 0.408 mm in the first flat roll rolling operation, and further rolled into a thickness of 0.255 mm in the second flat roll rolling operation. Then, heat treatment was performed at 840 ° C. for 50 hours in the atmosphere. 0.2 in one flat roll rolling operation
It was processed into a rectangular tape having a thickness of 22 mm. After that, heat treatment was performed at 840 ° C. for 50 hours in the atmosphere. The full-length critical current in the state of being immersed in liquid nitrogen was measured. Specific resistance 1
Table 2 also shows Jc, which is the quotient of the critical current determined by the definition of 0 ⁻¹³ Ω · m, divided by the cross-sectional area of the superconductor and Jc, which is the quotient divided by the cross-sectional area of the superconducting wire.

Example 3 Using a 42-km single-length multi-core superconducting wire produced by the same method as in Example 1, rolling was performed by flat roll work according to the following pass schedule.

In Example 3, the drawn wire material was processed into a thickness of 0.612 mm by the first flat roll rolling operation. At this time, cracking was observed on the side of the rectangular tape. Furthermore, after rolling to 0.367 mm in the second flat roll rolling work to 0.225 mm in the third flat roll rolling work, heat treatment was carried out at 845 ° C. for 50 hours in the atmosphere. Then, it was further processed into a flat tape having a thickness of 0.222 mm by one flat roll rolling operation. The width of the tape material was 2.70 mm. After that, heat treatment was performed at 840 ° C. for 50 hours in the atmosphere. By measuring the critical current of the full length in the state of being immersed in liquid nitrogen, and dividing the critical current determined by the specific resistance of 10 ^-13 Ω · m by the cross-sectional area of the superconductor, Jc and the cross-sectional area of the superconducting wire. The total Jc, which is the quotient obtained by dividing, is also shown in Table 2.

[0072]

[Table 2]

As is clear from the results shown in Table 2, the rolling work for transforming the drawn circular wire into the shape of a rectangular tape is one
The rolling reduction ratio (%) = (t ₀ −t ₁ ) / t ₀ × 100, where t ₀ and t ₁ are the thicknesses of the wire before and after the flat roll rolling operation. It can be seen that the superconducting wire of Example 1 having a defined rolling reduction of more than 70% has good workability and exhibits a high critical current density.

Example III A powder prepared by the same method as in Example 1 of Example I described above and degassed was filled in a silver pipe having an outer diameter of 6 mm and a thickness of 0.75 mm to form a groove. 2 x 1 after covering with a silver jig
After vacuuming at 0 ^-5 Torr for 10 hours, both ends were electron beam welded. After wire drawing to a diameter of 2.91 mm, wire drawing was performed with regular hexagonal soybean having a length of opposite sides of 2.44 mm to obtain a wire rod.

With respect to the hexagonal wire rod thus obtained, seven wires are tightly bundled, and a glass fiber made of quartz is spirally wound around the wire rods to be closely adhered to each other.
A heat treatment was performed at 800 ° C. for 10 hours in the atmosphere, and the silver coating was diffusion-bonded and integrated. The wire rod thus obtained was drawn once to a diameter of 2.91 mm at a cross-section reduction rate of about 20.7%, and then the opposite side length was 2.44.
Wire drawing was performed with a regular hexagonal soybean of mm. Further, 7 hexagonal-shaped 7-core wires obtained by drawing are tightly bundled again, and glass fibers made of quartz are spirally wound around them to make them adhere to each other.
Heat treatment was applied for a period of time, and the silver coating was diffusion bonded and integrated. The wire rod thus obtained is drawn once to a diameter of 1.02 mm at a cross-section reduction rate of about 20.7%,
A 49-core wire rod was produced. This 49-core wire was processed into a flat tape having a thickness of 0.255 mm by one flat roll rolling operation, and then heat-treated at 845 ° C. for 50 hours in the atmosphere. After that, 0.222 in one flat roll rolling operation.
It was processed into a rectangular tape having a thickness of mm. The width of the tape material was 2.70 mm. Furthermore, in the atmosphere, 840 ℃, 50
After heat treatment for a period of time, the critical current of the entire length was measured while immersed in liquid nitrogen, and the specific resistance was 10 ⁻¹³ Ω.
It was 36.0 A by m definition. Jc, which is the quotient of the critical current divided by the cross-sectional area of the superconductor, is 15,000 A / cm ² ,
Overall Jc, which is the quotient of the critical current divided by the cross-sectional area of the superconducting wire, showed good characteristics of 6,000 A / cm ² .

[0076]

As described above, the use of the method for producing an oxide high temperature superconducting wire according to the present invention provides good bending strain characteristics during use and further improves the critical current density per wire. Thus, it becomes possible to easily produce a high-performance and long-length oxide high-temperature superconducting wire with a simple device.

Therefore, the method of the present invention can be effectively used for producing a long oxide high-temperature superconducting wire applied to, for example, bus bars, superconducting cables, superconducting magnets, and current leads to superconducting magnets.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an assembly configuration in which a plurality of metal-coated wires are assembled in a step included in the method for manufacturing an oxide high temperature superconducting wire according to the present invention.

FIG. 2 is a diagram showing an example of an assembly structure in which a plurality of metal-coated wires are assembled in a step included in the method for producing an oxide high temperature superconducting wire according to the present invention.

FIG. 3 is a diagram showing an example of an assembly structure in the case of assembling a plurality of metal-coated wires in the steps included in the method for producing an oxide high temperature superconducting wire according to the present invention.

FIG. 4 is a diagram showing an example of an assembly structure in the case of assembling a plurality of metal-coated wires in the steps included in the method for producing an oxide high temperature superconducting wire according to the present invention.

FIG. 5 is a diagram showing an example of an assembly structure in the case of assembling a plurality of metal-coated wires in the steps included in the method for producing an oxide high temperature superconducting wire according to the present invention.

FIG. 6 is a diagram showing an example of an assembly structure in which a plurality of metal-coated wires are assembled in a step included in the method for producing an oxide high temperature superconducting wire according to the present invention.

FIG. 7 (a) is a diagram showing a sectional structure of a wire rod manufactured according to the method of the present invention before rolling, and FIG. 7 (b) is a diagram showing a sectional structure of a wire rod manufactured according to a conventional method before rolling. Is.

FIG. 8 is a cross-sectional view showing the structure of a metal container used in an example according to the present invention.

[Explanation of symbols]

1,3 Metal coated single core wire 2 metal wire 4 Metal-coated multi-core wire 10 metal coating 20 Superconductor In each drawing, the same reference numerals indicate the same or corresponding parts.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenichi Sato, 1-3 1-3 Shimaya, Konohana-ku, Osaka, Sumitomo Electric Industries, Ltd. (56) Reference JP-A-63-279511 (JP, A) ( 58) Fields investigated (Int.Cl. ⁷ , DB name) H01B 12/00-13/00

Claims (8)

(57) [Claims] 1. A first step of preparing a plurality of wire rods in which an oxide superconductor or a raw material thereof is coated with a metal along a longitudinal direction, and between the wire rods in a state in which the plurality of wire rods are bundled. A second step of joining the plurality of wire rods by adhering the metal coatings together, a third step of subjecting the joined plurality of wire rods to plastic working to obtain a long wire rod, And a fourth step of obtaining a multifilamentary superconducting wire in which a sintered oxide superconductor is formed along the longitudinal direction by subjecting a lengthy wire to a heat treatment. 2. A step of collecting a plurality of long wire rods obtained in the third step before the fourth step, and a step of bundling the plurality of wire rods with each other, wherein the metal is provided between the wire rods. The method further comprising: a step of joining the plurality of assembled wire rods by adhering the coatings together, and a step of subjecting the joined plurality of wire rods to plastic working to obtain a long wire rod. Manufacturing method of oxide high-temperature superconducting wire. 3. The method for producing an oxide high temperature superconducting wire according to claim 1, wherein in the step of joining a plurality of wires, the adhesion of the metal coatings is realized by thermal diffusion of metal. 4. The step of degassing the powder of the oxide superconductor or the raw material thereof, wherein the first step fills the metal tube with the powder of the oxide superconductor or the raw material of the degassed oxide superconductor. A step of covering the both ends of the metal tube filled with the oxide superconductor or the powder of the raw material thereof with a lid to evacuate the inside of the metal tube, and then sealing both ends of the metal tube; The method for producing an oxide high-temperature superconducting wire according to claim 1, further comprising the step of subjecting the formed metal tube to plastic working to obtain a long wire. 5. A step of subjecting the joined plurality of wire rods to plastic working to obtain a long wire rod, a step of subjecting the joined plurality of wire rods to a wire drawing work to obtain a long wire rod, The method according to claim 1 or 2, further comprising: a step of rolling the wire rod that has been drawn to a long length to deform it into a rectangular tape shape; and a step of heat-treating the wire rod that has been deformed into a rectangular tape shape. 2. The method for producing an oxide high temperature superconducting wire according to 2. 6. A step of subjecting a plurality of the joined wire rods to plastic working to obtain a long wire rod, by rolling the wire rod that has been drawn to a long length and deforming it into a rectangular tape shape. The method for producing an oxide high temperature superconducting wire according to claim 5, wherein the step of heat treating the wire deformed into the rectangular tape shape is repeated a plurality of times. 7. In the step of subjecting the wire rod drawn into a long shape to a rolling process to deform it into a rectangular tape shape,
The rolling process is completed by one rolling operation.
Or the manufacturing method of the oxide high temperature superconducting wire of Claim 6. 8. In the step of subjecting a plurality of joined wire rods to plastic working to obtain a long wire rod, at least the first deformation work into a rectangular tape shape reduces the thickness with respect to the thickness of the wire rod before rolling. The method for producing an oxide high-temperature superconducting wire according to claim 6 or 7, which is carried out by a rolling process in which the amount ratio is 70% or more.