JPH01134818A - Manufacture of aluminum stabilized superconductive wire material - Google Patents

Abstract

PURPOSE:To obtain an Al stabilized supercoductive wire material by supplying a copper or copper alloy covered superconductive wire whose surface is cleaned into an Al pipe whose inside is displaced with Al gas and decreasing the surface after cooling into a room temperature and then applying processing at 250-350 deg.C for 0.5-30hours. CONSTITUTION:The surface of a copper covered superconductive wire 1 sent out from a coil 3 is processed with a polishing machine 4 and a cleaner 5, and the superconductive wire 1 is supplied into an Al pipe 2 pushed out from a hollow core axis 11 in an extruder 6. The pipe 2 is filled with Ar gas and the Al pipe which includes the superconductive wire 1 is cooled in a cooling bath 7 and throttled with a die 8 so as to tightly contact the outside of the conductor 1 with the inside of the pipe 2. Thereafter, it is processed at 250-350 deg.C, for 0.5-30hours. According to this constitution, Al is complexed uniformly in thickness and a dispersed layer is formed by heating and since the heat treatment is executed at low temperature for short time, the dislocation inside the superconductor is kept in high density and high superconductivity can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing an aluminum stabilized superconducting wire.

[Conventional technology and its problems]

The superconducting wire currently in practical use is NbT! , Nb*
Generally, superconducting wires are made by combining ultrafine multicore superconducting wires made by gathering and twisting superconducting wires such as S, 1, Vs G-, etc., and a stabilizing metal.

The above-mentioned stabilizing metal prevents the so-called quench accident in which the superconducting wire undergoes some disturbance during use in liquid H0 and transitions to normal conductivity, and the superconducting wire deteriorates or burns out due to the Joule heat generated at this time. In order to effectively exert the above effect, it is necessary to increase the thermal conductivity between the superconducting wire and the stabilizing metal. In addition, it is necessary to bond tightly.

Conventionally, Cu has been mainly used as this stabilizing metal, but in recent years, Cu has been used as the stabilizing metal, but in recent years A metal has been used, which has a lower electrical resistance than Cu under extremely low temperature and strong magnetic fields.
l is starting to be used.

By the way, in order to combine Al into superconducting wire, superconducting wire and A
There are methods of twisting the l wires and soldering them,
All of them had the disadvantage of lacking stability in terms of quality and being inferior in productivity.

There is also a method of integrating superconducting wire with A2 in a container and extruding it at high temperature, but with this method, it is difficult to composite A2 to a uniform thickness, and in order to improve the bondability of both, it is necessary to extrude at high temperature. There was a problem in that the superconductor would deteriorate if released.

[Means for solving problems]

The present invention was made in view of this situation, and its purpose is to provide a method for manufacturing an affiffed superconducting wire in which A2 has a uniform thickness and is tightly composited.

That is, the present invention continuously supplies a surface-cleaned Cu or 01 alloy coated superconducting wire into an extruding AJ pipe whose inner diameter is larger than the outer diameter of the superconducting wire and whose interior is replaced with argon gas. , then Aj containing this superconducting wire
After cooling the two pipes to room temperature, they are subjected to area reduction processing using a drawing die to bring the outer surface of the superconducting wire into close contact with the inner surface of the Al pipe, and then the pipes are heated at a temperature of 250 to 350°C to reduce the area by 0.5 to
It is characterized by heat treatment for 30 hours.

In the present invention, the heat treatment after adhesion is carried out at 250 to 350°C.
, 0.5 to 30 hours is the reason why the processing temperature is lower than 250°C, or even within the temperature range of 250 to 350°C, if the processing time is shorter than 0.5 hours, sufficient diffusion will not be achieved, resulting in poor bonding properties. On the contrary, if the treatment temperature is higher than 350° C. or the treatment time is longer than 30 hours, dislocations within the superconductor decrease and the superconducting properties deteriorate.

In the present invention, the reason why the superconducting wire is coated with Cu or a Cu alloy is that Cu easily diffuses into Al and bonding is achieved at a relatively low temperature and in a short time, so there is little risk of deterioration of superconducting properties.

Although any extruder can be used in the present invention, a ram-based joint extruder or a conform extruder is suitable because it can extrude a long material. The latter type of extruder extrudes material using the frictional force between a rotating grooved wheel and a shoe block placed and fixed on the groove, and is particularly suitable for extruding small-sized long materials.

〔Example〕

The present invention will be explained in detail below using examples.

FIG. 1 is an explanatory diagram of an embodiment of the method for producing an Al-stabilized superconducting wire of the present invention, and FIG. 2 is an explanatory diagram of the main parts of a conform extruder used in the same embodiment. The Cu-coated superconducting wire 2 is an Al pipe. After polishing and cleaning the surface of the Cu-coated superconducting wire 1 with an outer diameter of 1.8011 Il sent out from the uncoiler 3 by a polisher 4 and a washer 5, the wire is extruded from the hollow mandrel 11 of the extruder 6 with an inner diameter of 3. OOm, the above Cu-coated superconducting wire 1 is supplied into a /l pipe 2 with an outer diameter of 6.55 m, and this A2
A gas pipe (not shown) is inserted into the inside of pipe 2.
R gas is blown in to fill the AIl pipe 2, and the AIl pipe 2 containing the superconducting wire l is cooled in a cooling tank 7, and then the A2 pipe 2 is drawn with a drawing die 8 until the outer diameter becomes 5° and 35m. ! The inner surface of the pipe 2 was brought into close contact with the outer surface of the superconducting wire 1, and the superconducting wire 9 was wound around a coiler 10. The superconducting wire 9 thus obtained was heat-treated at various temperatures. The thickness of the diffusion layer produced by the heat treatment is about 0.5 to lpm within the conditions of the present invention.

FIG. 3 shows cross-sectional views of the wire in each of the above steps. Figure A shows a state in which the Cu-coated superconducting wire is enclosed in an A2 pipe, and the opening in the figure shows a state in which the outer surface of the Cu-coated superconducting wire and the inner surface of the /l pipe are brought into close contact by drawing.

For each of the Al-stabilized superconducting wires produced in this way, the bondability between the Cu-coated superconducting wire and the A2 pipe was measured by ultrasonic flaw detection, and the critical current density (Jc) was also measured in liquid He. .

The results are shown in Table 1 along with the manufacturing conditions.

Table 1 Since then, bondability is good ○, poor ×.

As is clear from Table 1, the products manufactured using the method of the present invention (1 to 7) all showed high Jc values and good bonding properties.
Those in which the heat treatment conditions were outside the limited range (8 to 12) showed low Jc values due to poor bonding between the superconducting wire and the A2 pipe or a decrease in dislocations within the superconductor.

In the above embodiments, a round wire was described, but the same results as for a round wire can be obtained even when the wire is rolled into a rectangular wire as shown in FIG. 3 by box rolling or the like.

〔effect〕

As described above, according to the present invention, in compounding /l as a stabilizing metal to a Cu-coated superconducting wire, the A2 pipe is processed to reduce its area and is closely bonded, so A2 is compounded to a uniform thickness, and The heat treatment forms a diffusion layer, creating a tight bond and improving quench resistance. Furthermore, since the heat treatment is performed at a relatively low temperature and in a short time, dislocations within the superconductor are held at a high density, resulting in high superconducting properties. obtained, and exhibits remarkable industrial effects.

[Brief explanation of the drawing]

FIG. 1 shows Aj! of the present invention. FIG. 2 is an explanatory view of the main part of an extruder, and FIGS. 3A to 3C are cross-sectional views of each step of the /l stabilized superconducting wire. 1...Cu coated superconducting wire, 2...A2 pipe, 6...
...Extruder, 8...Squeezing die, 9...Affi
FF superconducting wire. Patent applicant Furukawa Electric Co., Ltd. Figure 2 A
l＼Figure 3

Claims (1)

[Claims] A surface-cleaned copper or copper alloy coated superconducting wire is continuously fed into an extruded aluminum pipe whose inner diameter is larger than the outer diameter of the superconducting wire and whose interior is replaced with argon gas, and then this superconducting wire is After the aluminum pipe containing the superconducting wire was cooled to room temperature, it was subjected to area reduction processing using a drawing die so that the outer surface of the superconducting wire and the inner surface of the aluminum pipe were brought into close contact with each other.
A method for producing an aluminum stabilized superconducting wire, characterized by heat treatment for 5 to 30 hours.