JP3154246B2 - Extruded billet for AC 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 an extruded billet for an AC superconducting wire used for producing an AC superconducting multifilamentary wire.

[0002]

2. Description of the Related Art Generally, a superconducting wire used for a superconducting magnet or the like has a composite multi-core structure in which a large number of superconducting filaments are compounded in a matrix of a metal such as pure Cu or pure Al having a low specific resistance and a high thermal conductivity. It has. When the superconducting filament undergoes a normal conduction transition, this matrix bypasses the current caused by the voltage generated at both ends of the portion, and quickly exchanges the heat generated in that portion with a coolant, such as liquid helium, to superconducting filament. It is said to be a stabilizing metal because it has the role of maintaining the cooling state of the metal. Further, in order to enhance the stability of the superconducting wire, a large amount of stabilizing metal is arranged in the center portion, the outer layer portion, or the like of the superconducting wire.

[0003] As a method of manufacturing the above-mentioned superconducting wire, a method is generally known in which a stabilizing metal and a number of superconducting wires are inserted into a sheath made of a normal metal, and extrusion and stretching are performed on the wires. ing. By the way, when a superconducting wire is used in an AC application field, it is known that the following three types of AC losses occur. That is, there are three types: hysteresis loss occurring in the superconducting filament, coupling loss occurring between the superconducting filaments, and eddy current loss occurring in the stabilizing metal.

In order to reduce the hysteresis loss, it is necessary to make the superconducting filament extremely fine. To reduce the coupling loss, the superconducting filaments adjacent to each other with a stabilizing metal interposed therebetween are separated by a metal having a large specific resistance. It is known that it is effective to separate the stabilizing metal arranged at the center portion and the like with a barrier, and to reduce the eddy current loss by dividing the stabilizing metal with the barrier.

Therefore, as an extruded billet for an AC superconducting wire, as shown in FIG.
A stabilizing metal 7 composed of a pure Cu tube divided into six by a plate-shaped barrier 9 composed of a metal such as a u alloy is 10 wt% Ni.
-A tubular sheath 13 made of a metal such as a Cu alloy, and a tubular barrier 10 made of a metal such as a 10 wt% Ni-Cu alloy is further inserted inside the sheath.
And a tube made of a metal such as a 10 wt% Ni-Cu alloy into which a stabilizing metal 8 divided into four parts by a plate-like barrier 12 made of a metal such as a 10 wt% Ni-Cu alloy disposed at the center is inserted. A metal layer such as pure Cu on the outer peripheral portion of a rod made of a superconducting material such as Nb-Ti and a 10 wt%
An extruded billet 14 for an AC superconducting wire in which a predetermined number of superconducting wires having a regular hexagonal cross section formed with a metal layer such as a Ni-Cu alloy were filled was formed. The extruded billet 14 for an AC superconducting wire formed as described above is subjected to an HIP treatment as necessary, and then subjected to extrusion or stretching to produce a superconducting wire in which a superconducting substance is ultrafine in a filament shape.

The superconducting wire according to the present invention refers to an extruded billet for an AC superconducting wire that has been subjected to an extrusion process and then subjected to a stretching process, or an intermediate process thereof. A bar or a bar formed by forming one or more layers of a metal such as a stabilizing metal or a Ni—Cu alloy having a higher specific resistance than the stabilizing metal on the outer periphery thereof. Further, in the present invention, a superconducting filament bundle and a stabilizing metal are separated from each other, and a metal such as a Cu—Ni alloy having a higher specific resistance than the stabilizing metal dividing the stabilizing metal (the stabilizing metal is interposed therebetween). Excluding metals such as Cu-Ni alloys having a large specific resistance for separating adjacent superconducting filaments) is referred to as a barrier. Further, when the billet is assembled, it becomes the outermost layer of the billet, and the superconducting element wire and the stabilizing metal The plate or tube forming the tube and the tube into which the plate or tube forming the barrier is inserted are referred to as a sheath.

[0007]

In the extruded billet for AC superconducting wire having the above-mentioned conventional configuration, the barrier 11 or 11
It is inevitable that a gap is generated at the boundary between the tube forming the superconducting wire and the superconducting wire arranged at the superconducting wire arrangement location 6, and furthermore, not only the gap but also the mismatch of the boundary caused by the gap. As a result, the arrangement of the superconducting wires was disturbed, and as a result, a gap was easily formed between superconducting wires not at the boundary.

When the billet is subjected to HIP processing and extrusion, the superconducting wire, the stabilizing metal and the barrier are deformed so as to fill the above-mentioned voids. The distribution amount of the metal such as the stabilizing metal and the Cu-Ni alloy formed on the outer periphery of the filament fluctuates, and finally, the critical current value of the superconducting wire decreases and fluctuates. Further, the breakage of the superconducting filament has caused the superconducting wire itself to break.

[0009]

SUMMARY OF THE INVENTION The present invention has been made intensively in view of the above circumstances, and its purpose is to perform HIP processing,
It is an object of the present invention to provide an extruded billet for an AC superconducting wire in which the occurrence of breakage of the superconducting filament due to abnormal deformation of the superconducting filament during extrusion and stretching is reduced and excellent superconducting properties are obtained. That is, what is provided by the present invention is an extruded billet for an AC superconducting wire constituted by inserting a barrier made of a superconducting wire, a stabilizing metal and a metal having a higher specific resistance than the stabilizing metal into a sheath made of a normal metal. in a bar material having a superconducting wire which is inserted into the sheath, the stabilizing metal, and the barrier over metal is a regular hexagon cross-sectional shape of all the same size,
The barrier over metal is extruded billet AC superconducting wire, characterized in that in contact with at least two or more hexagonal sides.

[0010]

In the billet according to the present invention, the stabilizing metal and the barrier to be inserted into the sheath are all formed of rods having a regular hexagonal cross-sectional shape having the same dimensions as the superconducting wire. There are no voids at the boundary with the metal or barrier. Therefore, the superconducting wire, the stabilizing metal or the barrier does not deform so as to fill the voids even after the subsequent steps of HIP processing, extrusion and stretching, and the superconducting filament is deformed due to the deformation of the superconducting wire. The occurrence of deformation and breakage and breakage of the superconducting wire is minimized.

In the superconducting element wire according to the present invention, for example, N
A two-layer structure in which a stabilizing metal made of pure Cu or the like is formed on the outer periphery of a rod made of a superconducting material such as b-Ti, or a 10% Ni-Cu alloy having a higher specific resistance on the outer periphery. There is a three-layer structure having a metal formed thereon, and as a stabilizing metal, pure C having a low specific resistance and a high thermal conductivity is used.
u or pure Al metal can be used. As a barrier,
A metal such as a 10 wt% Ni-Cu alloy, a 30 wt% Ni-Cu alloy, a 1 wt% Mn-Cu alloy, a 5 wt% Si-Cu alloy, or the like is used.

In the extruded billet for AC superconducting wire according to the present invention, since the superconducting filament is hardly broken, the breakage of the superconducting wire is reduced and the stretchability is good. For this reason,
The extruded billet for AC superconducting wires according to the present invention has recently become ultrafine because the superconducting filament can be easily made ultrafine and the sheath can be filled with as many superconducting wires as possible without gaps between the superconducting wires. It is particularly suitable for the production of AC superconducting wires that tend to be multicore.

Furthermore, the extruded billet for an AC superconducting wire according to the present invention has a complicated structure because the stabilizing metal and the barrier are formed by a combination of a bar having the same hexagonal cross-sectional shape as the superconducting wire. An extruded billet for an AC superconducting wire can be easily formed, and the arrangement of the superconducting wires, the stabilizing metal, and the barrier in the superconducting wire can be designed to an arbitrary configuration optimal in design.

[0014]

The present invention will be described below in detail with reference to examples. Example First, a superconducting element wire was prepared as follows. Outer diameter 210m
m, a tube made of 10% Ni-Cu alloy having an inner diameter of 191 mm,
A tube made of pure Cu having an outer diameter of 190.5 mm and an inner diameter of 161 mm is inserted, and 50 wt% N having a diameter of 160.5 mm is further inserted therein.
An extruded billet was formed by inserting a b-Ti alloy round bar. This is subjected to extrusion processing after HIP processing, further to rolling processing to form a regular hexagonal cross section, and then to drawing processing, and the opposite side length of 1.
A 5 mm superconducting element wire was manufactured. A bar made of pure Cu and a bar made of a 10% Ni-Cu alloy having the same cross-sectional shape as the superconducting wire were prepared as a stabilizing metal and a barrier, respectively.

Next, as shown in FIG. 1, a superconducting wire disposition portion 1 a in a 10% Ni—Cu alloy tube having an outer diameter of 210 mm and an inner diameter of 190 mm serving as a sheath (as shown in FIG. The above-mentioned superconducting element wire is placed in a stabilizing metal disposition portion 2a (a portion having an outer diameter of approximately 190 mm, an inner diameter of 155 mm and a shape having an inner diameter of approximately 55 as shown in FIG. ), A bar material serving as a stabilizing metal is placed at the barrier arrangement location 3a (3 m width).
(a part shown by m)), a bar material serving as a barrier was inserted and arranged. At this time, FIG.
, The superconducting wire 1b, the stabilizing metal 2b, and the barrier 3b are filled in the superconducting wire 1b, the stabilizing metal disposing portion 2a, and the barrier disposing portion 3a, respectively, so that there is no void. Extruded billets 5 for AC superconducting wires were formed by arranging a predetermined number.

After the billet was subjected to the HIP treatment, the billet was extruded at an extrusion ratio of 16, and further processed to a diameter of 0.7 mm by repeating stretching and annealing. As the workability, the number of disconnections of the superconducting wire that occurred from the time of drawing to a diameter of 8 mm to the time of drawing to a diameter of 0.7 mm was recorded. As a result, the number of disconnections was one. Length 10 from superconducting wire processed to 0.7mm diameter
A piece of about 00 mm is collected at 30 places,
And the 10% Ni-Cu alloy were dissolved to obtain the ratio of the volume of the dissolved pure Cu and the volume of the 10% Ni-Cu alloy to the volume of the superconducting filament. became.

When the critical current density of the superconducting wire manufactured as described above was measured at 20 points, it was found that 4.2.
The average value was 3006 A / mm ² and the standard deviation was 10 A / mm ² in K and 5T magnetic fields.

COMPARATIVE EXAMPLE As shown in FIG. 3, 10% N having a thickness of 2.8 to be a barrier 9
A pure Cu tube having an outer diameter of 189.5 mm and an inner diameter of 155 mm serving as a stabilizing metal 7 divided into six parts by an i-Cu alloy plate is connected to an outer diameter 210 mm and an inner diameter 190 mm serving as a sheath 13.
Of 10% Ni-Cu alloy. Further, an outer diameter of 154.5 mm and an inner diameter of 14
A 9 mm 10% Ni-Cu alloy tube is inserted, and a barrier 10 and a 10 wt% Ni-Cu
A 2.8 mm thick plate-like barrier 12 made of Cu alloy
1 having a diameter of 60 mm and an inner diameter of 54.5 mm into which a round bar made of pure Cu having a diameter of 54 mm serving as the divided stabilizing metal 8 is inserted.
An extruded billet for an AC superconducting wire is filled by filling the same superconducting wire as that manufactured in the above-described embodiment in the superconducting wire disposing portion 6 formed between the barrier 11 and a tube 11 made of a 0 wt% Ni-Cu alloy. 14 was assembled.

The billet 14 assembled as described above was subjected to the same processing as in the embodiment, and was finally stretched to a diameter of 0.7 mm. At this time, the number of disconnections of the superconducting wire generated after stretching to 8 mm in diameter was recorded after stretching to 8 mm in the same manner as in the example, and as a result,
The number of disconnections was 11. From a superconducting wire processed to a diameter of 0.7 mm, pieces having a length of about 1000 mm are collected at 30 places, and pure Cu and a 10% Ni-Cu alloy are dissolved with nitric acid, thereby dissolving pure Cu with respect to the volume of the superconducting filament. When the volume ratio of the 10% Ni-Cu alloy was determined, the average was 2.97 and the standard deviation was 0.05. When the critical current density was measured at 20 points in the same manner as in the example, the average value was 28 in a 4.2K, 5T magnetic field.
The standard deviation was 65 A / mm ² and the standard deviation was 25 A / mm ² .

[0020]

As described above, the extruded billet for an AC superconducting wire according to the present invention reduces the abnormal deformation of the superconducting filament in the HIP processing, the extrusion processing and the stretching processing, so that the occurrence of breakage of the superconducting filament is reduced and It is possible to provide a superconducting wire that facilitates ultrafine filaments and has high critical current density and high characteristics. In addition, since the occurrence of disconnection of the superconducting wire itself is reduced, excellent workability with high production yield can be realized, and billet of any structure can be easily formed by simply changing the combination of superconducting wire and stabilizing metal and barrier. Therefore, it is possible to easily cope with the production of an AC superconducting wire whose structure tends to be complicated recently. As described above, the present invention contributes to improving the performance of a magnet or the like using an AC superconducting wire and reducing the manufacturing cost, and makes a remarkable contribution to industry.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of an extruded billet for an AC superconducting wire of the present invention.

FIG. 2 is an enlarged view of a portion A in FIG. 1;

FIG. 3 is a cross-sectional view of a conventional extruded billet for AC superconducting wire.

[Description of Signs] 1a Superconducting wire placement location 1b Superconducting wire 2a Stabilized metal placement location 2b Stabilized metal 3a Barrier placement location 3b Barrier 4 Sheath 5 Extruded billet for AC superconducting wire 6 Superconducting wire placement location 7 Stabilized metal Reference Signs List 8 Stabilized metal 9 Barrier 10 Barrier 11 Barrier 12 Barrier 13 Sheath 14 Extruded billet for AC superconducting wire

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) H01B 13/00 563 H01B 12/10 ZAA JICST file (JOIS)

Claims (1)

(57) [Claims] An extruded billet for an AC superconducting wire comprising a superconducting wire, a stabilizing metal, and a barrier made of a metal having a higher specific resistance than the stabilizing metal inserted into a sheath made of a normal metal. superconductor element to be inserted within a stabilizing metal, and bars of the barrier over metal has a regular hexagon cross-sectional shape of all the same size, the bus <br/> metal for the rear over at least two or more An extruded billet for an AC superconducting wire, which is in contact with hexagonal sides.