JPH08190818A - Metal-coated multi-core superconducting wire and method for producing the same - Google Patents

Abstract

(57) [Abstract] [Purpose] Conductor structure and multi-core to achieve the same compactness of the core as in the case of single-core wire while reducing the diameter of the superconducting core by making the metal-coated high-temperature superconducting wire multi-core. To provide a method for manufacturing a conductor. [Structure] In a cross section in which the superconducting core is perpendicular to the conductor longitudinal direction, a matrix of m rows in the conductor width direction and n columns in the conductor thickness direction (m and n are integers of 1 or more, m + n ≧ 3) is formed. It is characterized by being arranged so as to be arranged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal-coated multicore superconducting wire which requires densification of a superconducting core by mechanical processing such as pressing and rolling, and a method for producing the same.

[0002]

2. Description of the Related Art Oxide superconductor (La / Ba) 2 CuO4
Since the discovery of -δ (where 2 and 4-δ are subscripts)
Many ceramic-based superconductors having a remarkably high critical temperature have been discovered as compared with conventional metal-based superconductors operated by liquid helium temperature. In particular, with regard to Y-based, Bi-based, Tl-based oxide superconductors whose critical temperature exceeds the liquid nitrogen temperature, active research and development are being carried out mainly for the realization of superconducting application equipment operating in liquid nitrogen. is there.

Application techniques of these high-temperature superconducting materials are roughly classified into wire rod forming techniques for use as superconducting cables and coils and thin film forming techniques for use as various superconducting devices. , The advancement of the former wire rod technology is indispensable. Many proposals have already been made as a form of converting a ceramic superconducting material into a wire rod, but as a typical one of them,
A metal-coated superconducting wire in which a metal is coated with a superconductor core,
Examples include wire rods made by applying the superconducting material on a metal sheet, or winding and laminating a laminated material and drawing the wire, tape-shaped wire rods coated with a superconducting material on a metal tape or tape-shaped ceramic substrate. To be As a metal used as a coating material or a substrate in these wire forming methods, silver or a silver alloy is mainly used because of its properties such as chemical inertness with the high temperature superconducting material and easiness of processing.

Further, as a conventional document relating to a tape-shaped multicore ceramics superconducting conductor, there is JP-A-4-277410. In this conductor, flat-shaped superconducting conductors are arranged in a flat-shaped metal body. However, the surface of the flat-shaped superconducting conductor and the surface of the metal body are not parallel to each other but are in a tape-like structure. A core ceramics superconducting conductor.

[0005]

Among the above wire forming methods, the metal coating method is easy to process and handle.
Although it is the most commonly used method, the grain boundaries of the superconducting core, which is a polycrystalline body, are used to enhance the current-transporting characteristics of the metal-coated superconducting wire, that is, the critical current (Ic) and critical current density (Jc). It is necessary to improve the bondability, the crystal orientation, etc., and for that purpose, the superconducting core must be densified in any case. In particular, the effect of densification of the superconductor on the values of Ic and Jc in the magnetic field, which is important when considering the application of the superconducting wire, is greater than that without the external magnetic field. One method of densification is the melt-solidification method, in which the superconducting core is densified by melting and recrystallizing it in the coating material, but due to chemical equilibrium, this method is not applicable to all compound systems. It is possible, and in that case, it is essential to densify the superconducting core by mechanical methods such as pressing and rolling. Particularly in the Tl system, the density of the superconducting core greatly influences its superconducting property.
Even in the Bi system, in which crystal orientation and densification by the solid-phase reaction method are relatively easy as compared with the 1-system, it is possible to obtain high superconducting properties without the mechanical densification step as long as the solid-phase reaction method is used. Have difficulty.

On the other hand, when considering the application of ceramics-based superconducting conductors in the field of energy, the loss due to the time change of current, voltage and magnetic field, that is, the problem of AC loss and the problem of magnetic stability such as flux jump. Cannot be neglected, and therefore, there is also a demand for thinning of the superconducting core by increasing the number of cores in these high-temperature superconducting conductors. At the same time, it is presumed that it is preferable to use a multi-core conductor for the ceramics-based superconductor in which the current transport characteristics are significantly deteriorated due to mechanical strain. Conventionally, when making a metal-coated high-temperature superconducting wire multicore, a method of filling a plurality of single-core metal-coated wire rods into a metal pipe and further making a multicore wire rod by a wire drawing process has been adopted. Without breaking the cross-section structure of the multi-conductor conductor, maintaining the same superconducting core ratio as the single-core wire rod, by rolling or pressing the densification of the core equivalent to the most densified single-core wire rod. It was very difficult to do.

Further, in order to overcome the problem of weak grain boundary bonding between superconducting crystal grains and to obtain high current transport characteristics in a magnetic field, to obtain a high degree of crystal orientation of the superconductor, The higher the smoothness of the interface between the superconducting core and the metal coating material, the more advantageous it is, but the conventional superconducting multi-core tape-shaped wire material is prepared by filling the metal-coated wire rod into a cylindrical metal pipe and rolling the drawn wire. In the method, since the number of superconducting cores laminated in the thickness direction of the tape-shaped wire and the thickness of the metal coating material sandwiched between the superconducting cores become uneven, the smoothness of the metal coating / superconducting core interface is There was a problem that it was inferior to the case of tape wire. The tape-shaped multi-core ceramics superconducting conductor described in JP-A-4-277410 does not consider the smoothness at all.

As described above, the superconducting core of the metal-coated high-temperature superconducting wire is made multicore while maintaining the smoothness of the interface between the superconducting core and the metal-covering material, and the superconducting core is made equal to the single-core wire by a mechanical method. There was no densification technology.

The object of the present invention is to make the superconducting core of the metal-coated high-temperature superconducting wire multi-core while maintaining the smoothness of the interface between the superconducting core and the metal-covering material, and to make the core equivalent to that of the single-core wire. It is an object of the present invention to provide a metal-coated multicore superconducting wire having a conductor structure and a method for manufacturing the same.

[0010]

In order to achieve the above object, the first invention of the present application has a plurality of superconducting cores having a flat cross section and a flat cross section surrounding the superconducting cores and parallel to each other. A tape-shaped metal-coated multi-core superconducting wire having a coating material, wherein the superconducting core has a cross section perpendicular to the longitudinal direction of the superconducting wire, m rows in the width direction of the superconducting wire, the thickness direction of the superconducting wire. A matrix of n columns (where m and n are integers of 1 or more, and m + n ≧
It is characterized in that they are arranged in 3).

A second aspect of the present invention is a tape-shaped metal-coated multicore, comprising a plurality of superconducting cores each having a flat cross section and a covering material surrounding the superconducting cores and having a flat cross section whose surfaces are parallel to each other. A superconducting wire, in a cross section of the superconducting core perpendicular to the longitudinal direction of the superconducting wire, there are m rows in the width direction of the superconducting wire and n columns in the thickness direction of the superconducting wire (where m is 1 or more). And n is an integer of 2 or more, and they are arranged in the form of m + n ≧ 3).

A third invention is characterized in that, in the first invention or the second invention, the coating material is a metal or an alloy which is inactive in chemical reaction with the superconducting core.

The fourth invention is the first invention, the second invention or the third invention.
In the invention, the superconducting core is made of an oxide superconductor.

The fifth invention is the first invention, the second invention or the third invention.
In the invention, the superconducting core is made of an oxide superconductor, and the ratio of the cross-sectional area of the superconducting core to the cross-sectional area of the metal-coated multicore superconducting wire is 0.3 or more and 0.9 or less. .

According to a sixth invention, in the first or third invention, the superconducting core is made of an oxide superconductor, and the superconducting core is perpendicular to the longitudinal direction of the wire of the tape-shaped metal-coated multicore superconducting wire. 4 or more are arranged in a row in the width direction of the wire (m ≧ 4, n = 1), and the ratio of the cross-sectional area of the superconducting core to the cross-sectional area of the metal-coated multicore superconducting wire is 0.3. It is characterized in that it is not less than 0.9 and not more than 0.9.

In a seventh aspect of the invention, in the first or third aspect of the invention, the superconducting core is made of an oxide superconductor, and the superconducting core is perpendicular to the longitudinal direction of the wire of the tape-shaped metal-coated multicore superconducting wire. 3 or more are arranged in a line in the thickness direction of the wire (m = 1, n ≧ 3), and
The ratio of the cross-sectional area of the superconducting core to the cross-sectional area of the metal-coated multi-core superconducting wire is 0.3 or more and 0.9 or less.

An eighth aspect of the present invention is a filling step of filling a superconducting substance or a raw material thereof into a metal sheath which is inactive with respect to them, a wire drawing step of the sheath, and a metal obtained in the wire drawing step. A primary densification step of rolling a sheath wire, and a matrix of m rows in the conductor width direction and n columns in the conductor thickness direction in a cross section in which the conductor core made of the superconducting material or the raw material is perpendicular to the longitudinal direction of the wire. (Where m and n
Is an integer greater than or equal to 1, and an assembling step of covering a plurality of the sheath wires with an assembling metal sheet or bundling with an assembling metal wire so as to be arranged so as to form m + n ≧ 3),
A diffusion bonding heat treatment step of performing diffusion bonding between the sheath wire rods or between the sheath wire rods and the metal sheet for assembling, and a multifilamentary wire obtained by the diffusion bonding heat treatment step is rolled to have a flat cross section m rows. , A second densification step of forming a tape-shaped metal-coated multicore wire rod comprising n rows of conductor cores and a coating material that surrounds the conductor cores and has a flat cross-section with mutually parallel surfaces, In a cross section perpendicular to the conductor longitudinal direction, the superconducting core includes a conductor heat treatment step for firing and sintering the conductor core, and a repeating step of the second densification step and the firing heat treatment step. In the method for producing a metal-coated multi-core superconducting wire, a matrix of m rows and n columns in the conductor thickness direction is arranged.

A ninth aspect of the present invention is a filling step of filling a superconducting substance or a raw material thereof into a metal sheath which is inactive with respect to them, a wire drawing step of the sheath, and a metal obtained in the wire drawing step. A primary densification step of rolling a sheath wire, and a matrix of m rows in the conductor width direction and n columns in the conductor thickness direction in a cross section in which the conductor core made of the superconducting material or the raw material is perpendicular to the longitudinal direction of the wire. (M is an integer of 1 or more, and n is an integer of 2 or more) so that the metal sheets for assembling are sandwiched between the rows of the m pieces of the sheath wire so that n is arranged.
The assembly step of stacking and assembling in stages, the diffusion joining heat treatment step of performing diffusion joining between the sheath wire rods or between the sheath wire rods and the assembling metal sheet, and the multiple joining heat treatment step The core wire is rolled into a flat cross section with m rows,
A second densification step of forming a tape-shaped metal-coated multi-core wire rod, which comprises an n-row conductor core and a covering material that surrounds the conductor core and has a flat cross-section with mutually parallel surfaces,
Firing of the conductor core, a firing heat treatment step for sintering,
In a cross section perpendicular to the conductor longitudinal direction, including a repeating step of the secondary densification step and the firing heat treatment step,
A method for producing a metal-coated multicore superconducting wire, characterized in that superconducting cores are arranged in a matrix of m rows in the conductor width direction and n columns in the conductor thickness direction.

A tenth aspect of the present invention is a filling step of filling a superconducting substance or a raw material thereof into a primary metal sheath which is inactive with respect to a chemical reaction with them, and a primary wire drawing process of drawing the primary metal sheath. In a primary densification step of rolling the metal sheath wire obtained in the wire drawing step, and in a cross section in which the conductor core made of the superconducting material or the raw material is perpendicular to the longitudinal direction of the wire, m rows in the conductor width direction. , A matrix of n columns in the conductor thickness direction (m and n are integers of 1 or more, and m + n
An assembling step of filling and bundling a plurality of the sheath wires into an assembling metal sheath so that they are arranged in a manner of ≧ 3).
The secondary wire drawing step of drawing the multifilamentary wire obtained in the assembling step, the diffusion joining heat treatment step of performing diffusion joining between the sheath materials, and the multifilamentary wire obtained in the diffusion joining heat treatment step Rolled to form a tape-shaped metal-coated multi-core wire having m rows and n columns of conductor cores having a flat cross section and a covering material having a flat cross section that surrounds the conductor cores and has mutually parallel surfaces. A cross section perpendicular to the conductor longitudinal direction, which includes a secondary densification step, a firing heat treatment step for firing and sintering the conductor core, and a repeating step of the secondary densification step and the firing heat treatment step. In the above method, the superconducting cores are arranged in a matrix having m rows in the conductor width direction and n columns in the conductor thickness direction, and arranged.

An eleventh aspect of the invention is a filling step of filling a superconducting substance or a raw material thereof into a metal sheath which is inactive with respect to their chemical reaction, and a primary wire drawing process of the sheath.
In a cross section where the conductor core made of the superconducting substance or the raw material is perpendicular to the longitudinal direction of the wire, a matrix of m rows in the conductor width direction and n columns in the conductor thickness direction (m and n are integers of 1 or more, m + n ≧ 3) so that the plurality of the sheath wires are packed and bound in a metal sheath for assembling, and the multifilamentary wire obtained in the assembling process is drawn. Secondary wire drawing step, diffusion bonding heat treatment step for performing diffusion bonding between sheath materials, and multifilamentary wire rod obtained by the diffusion bonding heat treatment step is rolled to have a flat cross section in m rows and n columns of conductors. A densification step of forming a tape-shaped metal-coated multi-core wire having a core and a covering material having a flat cross-section that surrounds the conductor core and is parallel to each other, and firing and sintering the conductor core. And a calcination heat treatment step for the second densification step and the calcination heat treatment In a cross section perpendicular to the longitudinal direction of the conductor, the superconducting cores are arranged in a matrix of m rows in the conductor width direction and n columns in the conductor thickness direction. It is a method for manufacturing a core superconducting wire.

A metal-coated multi-core superconducting secondary wire formed by compounding at least one tape-shaped metal-coated multi-core superconducting element wire is spirally formed on the outer or inner circumference of a cylindrical or round wire former. A metal-coated multi-core superconducting wire having a configuration in which the tape-shaped metal-coated multi-core superconducting element wire comprises a plurality of superconducting cores and a covering material surrounding the superconducting core, the superconducting core being the tape. In a cross section perpendicular to the longitudinal direction of the metal-coated multicore superconducting wire, a matrix of m rows in the conductor width direction and n columns in the conductor thickness direction (m and n are integers of 1 or more, m + n ≧ 3) is formed. A metal-coated multifilamentary superconducting wire arranged in the same manner may also be used.

[0022]

According to the present invention, in a multi-core metal-coated superconducting wire, the superconducting cores separated by the metal coating are pressed,
In the densification process such as rolling, the superconducting cores do not come into contact with each other and receive uniform pressure, so the same densification as in the case of the single core wire is realized and the thickness of the superconducting core is reduced. Since the smoothness of the interfaces parallel to each other in the coated metal-superconducting core is maintained above, the crystal orientation is improved, and at the same time, the bending strain resistance and electromagnetic stability of the current transport characteristics are improved due to the multi-core structure.

[0023]

EXAMPLE FIG. 1 is a sectional view showing a conductor structure when a tape-shaped metal-coated multi-core superconducting wire according to the present invention is produced. This superconducting wire is a tape-shaped metal-coated multi-layered metal having 25 superconducting cores 1 having a flat cross section and a covering 2 having a flat cross section that surrounds the superconducting core 1 and is parallel to each other. A core superconducting wire, wherein the superconducting cores 1 are arranged in a matrix of 5 rows in the width direction of the superconducting wire and 5 columns in the thickness direction of the superconducting wire in a cross section perpendicular to the longitudinal direction of the superconducting wire. There is. Here, the intervals between the superconducting cores 1 are the same, and the intervals between the flat upper and lower surfaces of the covering material 2 and the superconducting cores 1 located at the outermost side are also formed in the outside city area. With this configuration, in the multicore metal-coated superconducting wire, the superconducting cores separated by the metal-covering material do not come into contact with each other during the densification process such as pressing and rolling, and each superconducting core has a uniform pressure. Therefore, the same densification as in the case of the single core wire is realized, the thickness of the superconducting core is reduced, and the smoothness of the interface parallel to the coated metal-superconducting core is maintained.

Example 1 Mo: Ba: Sr: Ca: Cu = 1.6: 0.4:
Oxides of the constituent elements, which were weighed to be 2.0: 3.0, that is, BaO, SrO, CaO, CuO were crushed for 30 minutes by a Likai machine, and the mixture was put into an alumina crucible and kept in air at 900 ° C. It was baked for 15 hours. The obtained powder was crushed for 30 minutes by a raikai machine, put in an alumina crucible again, and fired in air at 900 ° C. for 15 hours. To the precursor powder thus obtained, Tl2O3 was added to Tl: Ba:
Sr: Ca: Cu = 2.0: 1.6: 0.4: 2.0:
It was added so as to be 3.0, and further mixed for 30 minutes by a liquor machine. The obtained superconductor raw material powder is molded into pellets and put into an alumina crucible with a lid, and the mixture is placed in air at 870 ° C.
What was baked for 10 hours was crushed for 30 minutes with a liquor machine to obtain a superconductor powder. The superconducting critical temperature Tc of the pellets before pulverization was 113K, and the crystal phase of the superconductor powder obtained by powder X-ray diffraction measurement was Tl ₂ Ba ₂ Ca ₂ C.
It was a single phase of u ₃ O _x .

Subsequently, the outer diameter is 6 mm and the inner diameter is 5 with one end sealed.
A silver pipe with a diameter of 0.7 mm is filled with this superconductor powder, the other end is sealed, and surface reduction processing is performed by drawing using a draw bench to obtain a silver-coated single core wire with an outer diameter of 0.7 mm and 1.0 mm. It was A part of the silver-coated single core wire with an outer diameter of 1.0 mm is cut out and subjected to roll rolling, and a width of 2.5 mm,
A 0.2 mm thick tape-shaped silver-coated single-core wire was obtained (FIG. 2).

From the remaining silver-coated single-core wire having an outer diameter of 1.0 mm, 19 pieces having the same length are cut out and bundled, and an outer diameter of 6 mm,
After inserting it into a silver pipe with an inner diameter of 5 mm, sealing both ends, and making a 19-core wire rod with an outer diameter of 1.3 mm by the same drawing process, a roll rolling process made it 3.5 mm wide and 0.2 m thick.
m tape-shaped silver-coated 19-core wire was obtained (FIG. 3).

Further, a silver-coated single-core wire having an outer diameter of 0.7 mm is roll-rolled to form a tape-shaped wire having a width of 0.8 mm and a thickness of 0.4 mm.
It was covered with a silver tape having a thickness of 50 μm and wound around an alumina cylinder whose surface was coated with alumina powder while binding, and heat-treated in an oxygen stream at 800 ° C. for 30 minutes to perform silver diffusion bonding. The obtained aggregated wire having a width of about 2.5 mm and a thickness of about 1.0 mm is rolled to a thickness of 0.2 mm by width-constraining roll rolling, and then subjected to diffusion bonding heat treatment at 800 ° C. in an oxygen stream for 30 minutes. went. After that, the cross-section reduction rate is about 2
Width-restricted roll rolling is performed while sandwiching the annealing for 20 minutes at 300 ° C for each 0% processing, and the width is 3.0 m.
A 6-core tape-shaped wire having a thickness of m and a thickness of 0.1 mm was obtained, and a test piece having a length of 300 mm was cut out from the wire. This is pasted with silver paste and three layers are laminated, and then 600 in an oxygen stream.
What was heat-treated for 30 minutes at ℃ was rolled again, and tape-shaped silver coating with a width of 3.5 mm and a thickness of 0.2 mm 1
An 8-core wire was obtained (Fig. 4).

The structures of the cross sections of the single-core, 19-core and 18-core tape-shaped wire rods obtained above, which are perpendicular to the longitudinal direction of the wire rods, are schematically shown in FIGS. 2, 3 and 4. Samples obtained by pressing test pieces cut out from these tape-shaped wire rods at a pressure of 10 t / cm ² , heat-treating them in an oxygen stream at 840 ° C. for 2 hours, and then performing the same heat treatment as the press of 12 t / cm ^2. About the critical current density Jc at 77K
Was measured. As a result, the critical current density per core cross-sectional area of single-core, 19-core and 18-core tape-shaped wire rods, core J
c is 9000 A / cm ² without an external magnetic field,
It was 6000A / cm ² and 8500A / cm ^2.
Further, the reduction rate of the core Jc at 77 K when a bending strain of 0.5% is applied to each tape-shaped wire and at an external magnetic field of zero is 0.3, 0.8 and 0.8, respectively, and is 2700
^{A / cm 2, 4800A / cm} 2 and 6800A / cm
^{Was 2} .

Example 2 A superconducting powder synthesized by the same process as in Example 1 was filled in a silver pipe having an outer diameter of 6 mm and an inner diameter of 5 mm which was sealed at one end, and the other end was sealed and pulled out using a draw bench. By processing, the metal-coated single-core wire obtained by surface-reducing to an outer diameter of 0.7 mm is divided into 7 parts, and an outer diameter of 3.6 mm and an inner diameter of 3.4.
A mm silver pipe was flatly crushed and inserted into a flat silver pipe in a horizontal row to seal both ends. The cross-sectional structure of the wire rod at this point is schematically shown in FIG. Subsequently, this was rolled to a width of 5 mm and a thickness of 0.4 mm by width-constrained roll rolling, and then further rolled by ordinary roll to form a width of 6 mm in which seven superconductor cores were arranged in a row in the width direction, Thickness 0.2
mm tape-shaped 7-core wire rod was produced and cut into several test pieces (a) having a length of 30 mm (not shown).

On the other hand, for comparison, the following procedure is used to make the final core ratio (that is, the ratio of the cross-sectional area of the superconductor core to the cross-sectional area of the cross section perpendicular to the longitudinal direction of the wire) substantially equal. It was produced by a method of incorporating the core wire into a commonly used cylindrical pipe. That is, the same superconducting powder as in Example 1 was used, with an outer diameter of 6 mm and an inner diameter of 5.5 m.
m into a silver pipe, seal the other end, and reduce the outer diameter to 1.65 mm by drawing using a drawbench to divide the metal-coated single-core wire into 7 equal parts and bundle them. It was inserted into a silver pipe having an outer diameter of 6 mm and an inner diameter of 5 mm to seal both ends. 2.5m outer diameter by the same drawing process
m 7-core wire rod was produced. The cross-sectional structure of the wire rod at this point is schematically shown in FIG. Rolled to a width of 6m
A tape-shaped 7-core wire having a thickness of m and a thickness of 0.2 mm was cut out, and several test pieces for comparison (b) having a length of 30 mm were cut out from this.

Here, a tape-shaped 7-core wire test piece (a)
The core ratios of (b) and (b) were 46% and 48%, respectively. Further, the obtained test pieces (a) and (b) were heat-treated in an oxygen stream at 845 ° C. for 2 hours to obtain a test piece (a ′) and a comparative test piece (b ′). The core Jc at 77K of the test pieces (a ') and (b') is 330 and 315A, respectively.
Was / cm ² . Further, with respect to the test pieces (a) and (b), cold press and heat treatment in an oxygen atmosphere were conducted for 3 times while increasing the pressure of the press at 5, 10 and 15 t / cm ² each time.
Repeated times, test pieces (a ″) and (b ″) were obtained. The heat treatment conditions here were all 845 ° C. and 2 hours. Core J at 77K of test pieces (a ″) and (b ″)
c is 19000 A / cm ² and 15000 A / cm, respectively
cm ² . When observing the cross-sectional structures of both, the superconductor cores were independent in the test piece (a ″), but in the test piece (b ″), the superconductor cores overlapped in the tape thickness direction. Many contact points were seen. In order to avoid the destruction of the cross-sectional structure of the comparative test piece (b ″), the final cold pressing pressure must be reduced to 10 t / cm ² or less, and in this case, the core Jc at 77K is Remained below 6000 A / cm ² .

Example 3 Oxides of the constituent elements, that is, SrO, CaO and Cu, were weighed so that the molar ratio was Sr: Ca: Cu = 2: 2: 3.
O was crushed for 30 minutes with a liquor mixer, and the mixture was put in an alumina crucible and fired in air at 900 ° C. for 15 hours. After crushing the obtained powder for 30 minutes with a raikai machine,
It was again placed in an alumina crucible and calcined in air at 900 ° C. for 15 hours. The precursor powder thus obtained is spread with Bi ₂ O ₃ and PbO and Bi: Pb: Sr: Ca: Cu = 1.8:
0.25: 2: 2: 3 was added, and the mixture was further mixed for 30 minutes with a liquor machine. The obtained superconductor raw material powder was put into an alumina crucible and fired in air at 800 ° C. for 10 hours, and then pulverized for 30 minutes with a raikai machine to obtain a superconductor powder. 6mm outer diameter and 5m inner diameter with one end sealed
A silver pipe of m was filled with this superconductor powder, the other end was sealed, and surface reduction was performed by drawing using a draw bench to obtain a silver-coated single-core wire having an outer diameter of 1.5 mm.
7 pieces with the same length are cut out and bundled, and the outer diameter is 6 m
After inserting into a silver pipe with an inner diameter of 5 mm and an inner diameter of 5 mm to seal both ends and making a 7-core wire rod with an outer diameter of 1.5 mm by the same drawing process, a width of 3.0 mm and a thickness of 0.2 m are obtained by roll rolling.
m tape-shaped silver-coated 7-core wire was obtained (FIG. 7).

Further, the remaining silver-coated single core wire having an outer diameter of 1.5 mm is further drawn to a wire having an outer diameter of 1.0 mm, and then roll-rolled to give a width of 3.0 mm and a thickness of 0.1 mm. A tape-shaped silver-coated single-core wire was obtained. From this, a test piece having a length of 300 mm was cut out. This is laminated with silver paste to form five layers, which are then placed in an oxygen stream of 60
Rolled on what was heat treated at 0 ° C for 30 minutes, tape-shaped silver coating with width 3.5mm and thickness 0.2mm 5
A core wire was obtained (Fig. 8). Since it is made thinner in this way, it tends to be flat, and since five of these are laminated and rolled, it is likely to be flat in the end.

The structure of the 5-core and 7-core tape-shaped wire rods obtained above in a cross section perpendicular to the longitudinal direction of the wire rod is schematically shown in FIG.
And, as shown in FIG. 8, these tape-shaped wire rods are subjected to heat treatment in air at 840 ° C. for 48 hours three times by sandwiching cold roll rolling, to obtain tape-shaped superconducting wire rods, which have a critical current density Jc at 77K. It was measured. The critical current densities per core cross-sectional area of the 7-wire and 5-core tape-shaped wire rods, and the core Jc are 9000 A / c respectively when no external magnetic field is applied.
m ² and 8000 A / cm ² , and 1200 A / c when a magnetic field of 0.1 T parallel to the tape surface was applied.
m ² and 2500 A / cm ² .

Example 4 A superconducting powder synthesized by the same process as in Example 3 was filled in a silver pipe having an outer diameter of 6 mm and an inner diameter of 5 mm with one end sealed, and the other end was sealed and drawn to obtain an outer diameter. 0.
Rolled to a thin line up to 4 mm, width 1.2
A metal-coated single-core tape wire having a thickness of 0.1 mm and a thickness of 0.10 mm was obtained. This tape wire is arranged side by side on a stainless steel bobbin with an outer diameter of 300 mm with an alumina sheet wound on the surface, and the thickness is 0.03 mm between the uppermost layer, the lowermost layer and the interlayer.
While sandwiching the gold tape of 4 above, it was wound while being laminated with 4 layers and heat-treated in air at 835 ° C. for 10 hours. The cross-sectional structure of the wire before heat treatment is schematically shown in FIG. In the figure, 4 indicates a gold tape. By using the gold tape in this way, the adhesion strength between layers can be made higher than that of the silver tape. Gold from the beginning
Processing is limited because it is hard with a silver alloy, but as in the present embodiment, it is possible to perform processing satisfactorily since gold-silver alloy coating is performed through a gold tape after making it sufficiently thin with silver coating. The high strength advantage of silver alloys is obtained. And after heat treatment,
After rolling the assembled 16-core wire rod, it was wound again on a bobbin and the same heat treatment was performed for 50 hours. The cold rolling and heat treatment as described above are repeated twice more, and finally the width is 5
A multifilamentary tape wire having a thickness of 0.2 mm and a thickness of 0.2 mm was obtained.

Ten multifilamentary tape wire rods obtained as described above were arranged on the surface of a stainless steel pipe having an outer diameter of 30 mm, and 200
It was spirally wound at a pitch of mm, and both ends were soldered to copper electrodes to prepare a collective conductor. This is shown in FIG. In the figure, 10 is a core material (stainless steel pipe), 11 is a silver electrode, and 12 is a solder. A direct current of 200 A or more could be passed through this conductor in liquid nitrogen in a superconducting state.

Example 5 A multi-core tape wire produced by the same process as in Example 4 before final heat treatment was laminated with a magnesia tape on a silver ring having an outer diameter of 30 mm and a width of 5 mm to form a pancake. Then, a pancake coil was produced by winding. Current terminals using silver tape were provided on the innermost and outermost circumferences of the coil, and voltage measuring terminals using silver wires were provided at several points on the tape wire between the current terminals. That is, in the figure, 5 is a silver ring, 6 is a metal-coated superconducting multi-core tape wire, 7 is a magnesia sheet, 8 is a current terminal (silver tape), and 9 is a voltage measurement terminal (silver wire).

This coil was heat-treated in air at 835 ° C. for 50 hours. The appearance of the coil is schematically shown in FIG. This coil has a superconducting state of 15 A in liquid nitrogen.
The above direct current was allowed to flow, and this Ic value was equivalent to that of a short sample having a length of 30 mm or less which was cut out from the wire before the final heat treatment and subjected to the same final heat treatment. On the other hand, in the short sample, I
When a similar pancake coil having a superconducting core having the same composition and having a thickness of 0.2 mm and having a thickness of 0.2 mm was prepared, the Ic was reduced to less than half that of the short sample. It is considered that such a difference is due to the effect of improving bending strain resistance by increasing the number of cores.

[0039]

EFFECTS OF THE INVENTION According to the present invention, a core Jc higher than that obtained by using a conventional multi-core method in which a plurality of single-core metal-coated wire rods are filled in a metal pipe and further drawn into a multi-core wire rod. In addition, the bending strain resistance and electromagnetic stability of the transport current characteristics are improved as compared with the case of simply bundling single-core wires.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a conductor structure of a tape-shaped wire obtained by the present invention.

FIG. 2 is a cross-sectional view of a comparative single core tape-shaped wire in Example 1.

FIG. 3 is a cross-sectional view of a comparative 19-core tape-shaped wire in Example 1.

FIG. 4 is a cross-sectional structural formula view of an 18-core tape-shaped wire according to the present invention which is perpendicular to the longitudinal direction of the wire.

FIG. 5 is a schematic view of a conductor cross-sectional structure (a structure of a cross section perpendicular to the longitudinal direction of the wire) of the tape-shaped 7-core wire according to the present invention before rolling in Example 2.

FIG. 6 is a schematic diagram of a conductor cross-sectional structure (a structure of a cross section perpendicular to the longitudinal direction of the wire) of a comparative tape-shaped 7-core wire before rolling in Example 2.

FIG. 7 is a schematic view of a structure of a cross section of a comparative 7-core tape-shaped wire, which is perpendicular to the longitudinal direction of the wire.

FIG. 8 is a schematic view of a structure of a cross section of a five-core tape-shaped wire rod in Example 3 perpendicular to the longitudinal direction of the wire rod.

FIG. 9 is a schematic view of a structure of a cross section of the multifilamentary tape-shaped wire rod in Example 4 perpendicular to the longitudinal direction of the wire rod.

FIG. 10 is a perspective view of an assembly conductor obtained by winding the multi-core tape-shaped wire of Example 4 around a stainless pipe.

FIG. 11 is a perspective view of a pancake coil according to a fifth embodiment.

[Explanation of symbols]

 1 superconducting core 2 metal coating 3 silver coating 4 gold tape 5 silver ring 6 metal coating superconducting multi-core tape wire 7 magnesia sheet 8 current terminal (silver tape) 9 voltage measurement terminal (silver wire) 10 core material 11 Silver electrode 12 solder

Front Page Continuation (72) Inventor Kazuhide Tanaka 7-1 Omika-cho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi Research Laboratory

Claims (11)

[Claims] 1. A plurality of superconducting cores having a flat cross section,
A tape-shaped metal-coated multi-core superconducting wire comprising a covering material having a flat cross-section that surrounds the superconducting core and is parallel to each other, the superconducting core being perpendicular to the longitudinal direction of the superconducting wire. In the cross section, m rows are arranged in the width direction of the superconducting wire and n columns are arranged in the thickness direction of the superconducting wire (where m and n are integers of 1 or more, and m + n ≧ 3). A metal-coated multifilamentary superconducting wire which is characterized in that 2. A plurality of superconducting cores having a flat cross section,
A tape-shaped metal-coated multi-core superconducting wire comprising a covering material having a flat cross-section that surrounds the superconducting core and is parallel to each other, the superconducting core being perpendicular to the longitudinal direction of the superconducting wire. In the cross section, a matrix of m rows in the width direction of the superconducting wire and n columns in the thickness direction of the superconducting wire (where m is an integer of 1 or more, n is an integer of 2 or more, and m
A metal-coated multifilamentary superconducting wire characterized in that they are arranged in the form of + n ≧ 3). 3. The metal-coated multicore superconducting wire according to claim 1, wherein the coating material is a metal or an alloy which is inactive in chemical reaction with the superconducting core. 4. The metal-coated multicore superconducting wire according to claim 1, 2 or 3, wherein the superconducting core is made of an oxide superconductor. 5. The superconducting core according to claim 1, 2 or 3, wherein the superconducting core is made of an oxide superconductor, and the ratio of the cross-sectional area of the superconducting core to the cross-sectional area of the metal-coated multicore superconducting wire is 0.3 or more and 0.9 or more. The following is a metal-coated multi-core superconducting wire. 6. The wire according to claim 1, wherein the superconducting core is made of an oxide superconductor, and the superconducting core is a tape-shaped cross section of the metal-coated multicore superconducting wire perpendicular to the longitudinal direction of the wire. Four or more are arranged in a row in the width direction (m ≧ 4, n = 1), and the ratio of the cross-sectional area of the superconducting core to the cross-sectional area of the metal-coated multicore superconducting wire is 0.3.
A metal-coated multifilamentary superconducting wire characterized by being 0.9 or more. 7. The wire according to claim 1, wherein the superconducting core is made of an oxide superconductor, and the superconducting core is a tape-shaped cross section of the metal-coated multi-core superconducting wire perpendicular to the longitudinal direction of the wire. Three or more pieces are arranged in a line in the thickness direction (m = 1, n ≧ 3), and the ratio of the cross-sectional area of the superconducting core to the cross-sectional area of the metal-coated multicore superconducting wire is 0.
A metal-coated multifilamentary superconducting wire characterized by being 3 or more and 0.9 or less. 8. A filling step of filling a superconducting substance or its raw material into a metal sheath which is inactive with respect to a chemical reaction with them, a wire drawing step of the sheath, and a metal sheath wire rod obtained in the wire drawing step. In the primary densification step of rolling, and in a cross section in which the conductor core made of the superconducting substance or the raw material is perpendicular to the longitudinal direction of the wire, a matrix of m rows in the conductor width direction and n columns in the conductor thickness direction (here, , M and n are integers of 1 or more, and a plurality of the sheath wires are covered with a metal sheet for assembling or bundled with a metal wire for assembling so as to be arranged so as to form m + n ≧ 3). Forming step, diffusion joining heat treatment step of performing diffusion joining between the sheath wire rods or between the sheath wire rods and the assembling metal sheet, and the multifilamentary wire rod obtained by the diffusion joining heat treatment step is rolled to obtain a flat cross section. Shape m rows, n columns conductor core A second densification step of forming a tape-shaped metal-coated multifilamentary wire having a flat cross-section covering material surrounding the conductor core and parallel to each other, and for firing and sintering the conductor core In the cross section perpendicular to the conductor longitudinal direction, the superconducting core has m rows in the conductor width direction and n in the conductor thickness direction. A method for producing a metal-coated multicore superconducting wire, which comprises arranging in a matrix of rows. 9. A filling step of filling a superconducting substance or its raw material into a metal sheath which is inactive in chemical reaction with them, a wire drawing step of the sheath, and a metal sheath wire obtained in the wire drawing step. In the primary densification step of rolling and in a cross section in which the conductor core made of the superconducting substance or the raw material is perpendicular to the longitudinal direction of the wire, a matrix of m rows in the conductor width direction and n columns in the conductor thickness direction (where m is 1 or more, n is an integer of 2 or more) so that the metal sheets for assembling are sandwiched between the rows of the m pieces of the sheath wire so as to be stacked in n stages,
An assembling step of assembling, a diffusion joining heat treatment step of performing diffusion joining between the sheath wire rods or between the sheath wire rod and the assembling metal sheet, and rolling of the multifilamentary wire rod obtained in the diffusion joining heat treatment step Then, a tape-shaped metal-coated multi-core wire rod is provided, which has a conductor core of m rows and n columns having a flat cross section and a covering material having a flat cross section that surrounds the conductor core and is parallel to each other. A secondary densification step, a firing heat treatment step for firing and sintering the conductor core, and a repeating step of the second densification step and the firing heat treatment step, in a cross section perpendicular to the conductor longitudinal direction. A method for producing a metal-coated multi-core superconducting wire, comprising arranging the superconducting cores in a matrix of m rows in the conductor width direction and n columns in the conductor thickness direction. 10. A filling step of filling a superconducting substance or a raw material thereof into a primary metal sheath which is inactive in chemical reaction with them, a primary wire drawing step of drawing the primary metal sheath, and the wire drawing. In a primary densification step of rolling the metal sheath wire obtained in the step, and in a cross section in which the conductor core made of the superconducting substance or the raw material is perpendicular to the longitudinal direction of the wire, m rows in the conductor width direction, conductor thickness An assembly in which a plurality of the sheath wires are packed and bound in a metal sheath for assembly so that they are arranged in a matrix of n columns in the direction (m and n are integers of 1 or more, m + n ≧ 3) Of the multi-filamentary wire obtained in the assembling step, the diffusion drawing heat treatment step of performing diffusion joining between the sheath materials, and the diffusion joining heat treatment step. Multi-filamentary wire is rolled to have a flat cross section with m rows and n columns Secondary densification step of forming a tape-shaped metal-coated multifilamentary wire comprising a conductor core and a covering material that surrounds the conductor core and has a flat cross-section with mutually parallel surfaces, and firing the conductor core , A firing heat treatment step for sintering, and a repeating step of the secondary densification step and the firing heat treatment step, in a cross section perpendicular to the conductor longitudinal direction, the superconducting core has m rows in the conductor width direction, A method for producing a metal-coated multicore superconducting wire, comprising arranging a matrix of n columns in the conductor thickness direction. 11. A filling step of filling a superconducting substance or its raw material into a metal sheath which is inactive with respect to these chemical reactions, a primary wire drawing step of the sheath, and the superconducting substance or its raw material. The conductor cores are arranged in a matrix of m rows in the conductor width direction and n columns in the conductor thickness direction (m and n are integers of 1 or more, m + n ≧ 3) in a cross section perpendicular to the longitudinal direction of the wire. As described above, the assembling step of filling and bundling the plurality of the sheath wires into the assembling metal sheath, the secondary wire drawing step of drawing the multifilamentary wire obtained in the assembling step, and the sheath. A diffusion-bonding heat treatment step of performing diffusion bonding between materials, a multicore wire rod obtained by the diffusion-bonding heat treatment step and being rolled to have a flat cross-section of m rows and n columns, and a conductor core surrounding and surrounding each other. With a flat cross-section covering material whose surfaces are parallel A step of densifying the obtained tape-shaped metal-coated multi-core wire, a calcination heat treatment step for calcination and sintering of the conductor core, a secondary densification step and a repeating step of the calcination heat treatment step. A method for producing a metal-coated multicore superconducting wire, comprising arranging the superconducting cores in a matrix of m rows in the conductor width direction and n columns in the conductor thickness direction in a cross section perpendicular to the conductor longitudinal direction.