JPH01254335A - Manufacture of aluminum stabilized superconducting wire rod - Google Patents

Abstract

PURPOSE:To obtain Al composite superconducting wire rod excellent in quenching resistance by heat-treating under a specified condition Al composite superconducting wire rod obtained by composing an Al pipe integrally with a superconducting wire rod, cold-working it with a specified area reduction ratio and then annealing it. CONSTITUTION:The surface of Cu-clad superconducting wire rod 1 fed out of an uncoiler 3 is passed through a polishing machine 4 and a washing machine 5. An Al pipe 2 extruded by an extruding machine 6 is filled with Ar gas, the Al pipe 2 containing the superconducting wire rod 1 is cooled in a cooling tank 7 and drawn by a drawing die 8 and the inner surface of the Al pipe 2 is tightly attached and complicated to the outer surface of the superconducting wire rod 1 to make an Al composite superconducting wire rod 9. This superconducting wire rod 9 is heat-treated at 150-450 deg.C and for 0.25-300hrs, then, worked at cold temperatures to area reduction ratio of >=40$% and annealed at 100-350 deg.C and for 0.5-300hrs.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing an aluminum stabilized superconducting wire.

[Conventional technology and its issues]

Currently, the superconducting wires in practical use are NbTi, Nb,
mm type is a composite of ultrafine multicore superconducting wires made by gathering and twisting superconducting wires such as Sn, V, Ga, etc., and a stabilizing metal.

The above-mentioned stabilizing metals prevent the so-called quench accident in which the superconducting wire undergoes some disturbance during use in liquid He and transfers to normal conductivity, causing the superconducting wire to deteriorate or burn out due to the Joule heat generated at this time. In order to effectively exert the above effect, it is necessary to increase the electrical and thermal conductivity between the superconducting wire and the stabilizing metal. It is necessary to join them.

Conventionally, Cu was mainly used as this stabilizing metal, but in recent years Cu has been found to have lower electrical resistance than Cu at extremely low temperatures and in strong magnetic fields.
11 has come into use.

By the way, there are methods for combining Affi with superconducting wires, such as twisting the superconducting wires and A1 wires together or soldering them, but both methods have the disadvantage of lacking stability in terms of quality and being inferior in productivity.

Another method of combining Affi with superconducting wire is to integrate the superconducting wire with Al in a container and extruding it, but this method requires extrusion at high temperatures to improve the bonding between Al and the superconducting wire. For this reason, there was a problem that the superconductor was exposed to high temperatures during extrusion and deteriorated, and that the thickness of Al was likely to be uneven.

[Means and actions to solve the problem]

The present invention was made in view of this situation, and its purpose is to provide a method for producing an A2 stabilized superconducting wire in which Al is tightly composited with a uniform thickness and has excellent superconducting properties.

That is, the present invention continuously supplies a surface-cleaned copper or copper alloy coated superconducting wire into a hot-extruded aluminum pipe whose inner diameter is larger than the outer diameter of the superconducting wire and whose interior is replaced with argon gas. Then, after cooling the aluminum pipe containing the superconducting wire to a predetermined temperature or lower, the aluminum pipe is integrally composited with the superconducting wire by reducing the area using a drawing die, and then the aluminum composite superconducting wire is formed into the aluminum composite superconducting wire. 0.2 at 150-450℃
After heat treatment for 5 to 300 hours and then cold working with an area reduction rate of 40% or more, 0.5 to 3
It is characterized by being annealed for 00 hours.

The reason why a superconducting wire coated with Cu or a Cu alloy is used in the present invention is that Cu easily interdiffuses with Al and bonding can be achieved at a relatively low temperature and in a short time. Also, replacing the inside of the Al pipe with Ar during extrusion is 1. This is to prevent oxidation of the inner surface of the +1 pipe and the surface of the superconducting wire, thereby improving the bonding properties between the two.

In the present invention, A2 whose inner diameter is larger than the outer diameter of the superconducting wire
The superconducting wire is encapsulated in the pipe, and then this Al
Since the pipe is drawn and the two are combined into one, 1,1
M is composited to a uniform thickness around the superconducting wire. The reason for drawing the Al pipe after cooling it to a predetermined temperature or lower in the above-mentioned drawing process is to prevent the superconducting wire from being heated and deteriorated by the high-temperature Al pipe during compositing, and to
This is to prevent seizure of the drawing die, and it is preferable to cool it to about 100'C or less.

In the present invention, the reason why the above-mentioned Al composite superconducting wire is heat-treated is to diffuse bond the inner surface of the A2 pipe and the surface of the superconducting wire, and the above-mentioned heat treatment conditions are set to 150-450°C, 10°C,
The reason for limiting the time to 25 to 300 hours is that the processing time is lower than 150℃ or even within the temperature range of 150 to 450℃.
．． If the time is shorter than 25 hours, the bonding performance will be poor because the diffusion will not be sufficient, and if the treatment temperature is higher than 450°C or the treatment time is longer than 300 hours, the diffusion layer will be formed too thick.
This is because the bondability is rather reduced. The thickness of the diffusion layer is approximately 0.5 to 4 μm within the conditions of the present invention.

In the present invention, the reason why cold working is performed after heat treatment is that the dislocation density of the superconductor that has been subjected to the above heat treatment is reduced, so cold working multiplies dislocations and increases magnetic flux movement. This is to enhance the blocking pinning effect, and the reason why the area reduction rate is limited to 40% or more is because the above effect is not sufficiently exhibited if it is less than 40%.

In the present invention, the reason why annealing treatment is performed after cold working is that the AIV has a higher electrical resistance due to cold working.

This is to reduce the electrical resistance and restore the stabilizing function by annealing the composite layer. The above annealing treatment conditions are 10
The reason for limiting the temperature to 0 to 350°C and 0.5 to 300 hours is as follows.
Affected if the treatment temperature is lower than 100℃ or the treatment time is shorter than 0.5 hours even within the temperature range of 100 to 350℃
i The electrical resistance of the composite layer is not sufficiently reduced, and the processing temperature is 3.
This is because if the temperature is higher than 50° C. or the treatment time is longer than 300 hours, dislocations within the superconductor decrease and the superconducting properties deteriorate.

In the present invention, any extruder can be used to extrude the A2 pipe, but a ram-based extrusion 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 manufacturing an Al-stabilized superconducting wire according to the present invention, and FIG. 2 is an explanatory diagram of the main parts of a conform extruder used in the same embodiment.

In the figure, 1 is a CuWI-covered NbTi superconducting wire, 2 is an Af pipe with a purity of 99.994%, and 3 is an uncoiler.
After the surface of the coated superconducting wire 1 is polished and cleaned by the polishing machine 4 and cleaning 815, an A having an inner diameter of 3°0 m and an outer diameter of 6.55 m is extruded from the hollow mandrel 11 of the extrusion 106.
Supplying the above Cu-coated superconducting wire 1 into the j2 vibe 2,
The inside of this A2 pipe 2 is filled with Ar gas through a gas vibrator (not shown), and this superconducting wire l
After cooling the Affi pipe 2 containing the aluminum pipe 2 to room temperature in the cooling tank 7, the Al vibe 2 is cut into a shape with an outer diameter of 5 by the drawing die 8.
．． The inner surface of the Affi vibe 2 is closely combined with the outer surface of the superconducting wire 1 by drawing until it becomes 35 mm, forming an Al composite superconductor v.
It was wound up on coiler 10 as A9.

After heat treating the AN composite superconducting wire 9 obtained in this manner under various conditions, cold working is performed at various area reduction ratios, and then the above cold worked Affi ifi
The composite superconducting wire is annealed under various conditions to produce Afif.
It was made into an f-type superconducting wire. Incidentally, FIGS. 3A to 3C show cross-sectional views of the wire rod in each of the above steps. Figure A shows a state in which Cu-coated superconductor f11 is included in Affi vibe 2.
A diagram showing a state in which the inner surfaces of the vibrator 2 are in close contact with each other, and FIG.

For each AP-stabilized superconducting wire produced in this manner, the bonding properties between the Cu-coated superconducting wire and the Al vibe were measured by ultrasonic flaw detection, and the critical current density (
JC) was measured. Also, A2 stabilizing material IOK and 300K
The electrical resistance (PR) was measured, and the residual resistance ratio (RRR), which indicates the stabilizing function of the An stabilizing material, was determined by the following formula.

RRR=E, 300 K/E, 10 K The results are shown in Table 1 along with the manufacturing conditions.

Table 1 * λ defective in mating mackerel.

As is clear from Table 1, the product produced by the method of the present invention (N.

Nos. 1 to 17) all exhibit high values of JC value and RRR value, and are also excellent in bondability between the Al stabilizing material and the superconducting wire.

On the other hand, those whose heat treatment conditions are outside the limited range (1B
, 19.26.2B, 29) have poor bonding properties between the stabilizing material and the superconducting wire, and those with a cold working area reduction rate of less than 40% (22, 23, 27-29) have poor bondability between the stabilizing material and the superconducting wire. Since there are few dislocations, Jc shows a low value. Also, those whose annealing conditions are outside the limited range (20, 21, 24, 27, 29) are A
l The electrical resistance of the stabilizing material is not sufficiently reduced, or the dislocations within the superconductor are reduced too much, and RRR or J shows a low value.

In this example, an A2 stabilized superconducting wire with a circular cross section was explained, but the method of the present invention can also be applied to a wire formed into a rectangular wire as shown in Fig. 3-2 by box rolling or the like after cold working. It is something.

[Effects] As described above, according to the method of the present invention, a superconducting wire with a high dislocation density has high conductivity. Since the stabilizing material is tightly composited with a uniform thickness, properties such as quench resistance and Jc are improved. It is possible to produce an AI-stabilized superconducting wire with excellent properties, and it has a significant industrial effect.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of an embodiment of the method for producing an A1 stabilized superconducting wire of the present invention, Fig. 2 is an explanatory diagram of the main parts of an extruder, and Fig. 3 is a cross section of the A2 stabilized superconducting wire at each step. It is an explanatory diagram. l...Cu coated superconducting wire, 2...Al vibe, 6
...Extruder, 8...Squeezing die, 9...Af
i composite superconducting wire. Figure 2 Figure 3

Claims (1)

[Claims] A surface-cleaned copper or copper alloy coated superconducting wire is continuously fed into a hot-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 the above-mentioned After cooling the aluminum pipe containing the superconducting wire to a predetermined temperature or lower, the aluminum pipe is integrally composited with the superconducting wire by reducing the area with a drawing die, and then the aluminum composite superconducting wire is Stable aluminum characterized by heat treatment at 450°C for 0.25 to 300 hours, then cold working with an area reduction of 40% or more, and then annealing at 100 to 350°C for 0.5 to 300 hours. A method for manufacturing superconducting wire.