JPS61231143A - Manufacture of stabilizing material for composite superconductor - Google Patents

Abstract

PURPOSE:To manufacture a stabilizing material for composite superconductor having superior mechanical strength by CONSTITUTION:The pure Al rod with >=99.9wt% purity is coated with the Al alloy containing 0.2-0.6% each of Mg and Si. Then the.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for producing a stabilizing material for a composite superconducting conductor.

<Conventional technology and its problems> For large superconducting magnets used in nuclear fusion, energy storage, etc., it is essential to use large-capacity conductors in order to generate a high magnetic field by reducing inductance in order to protect the magnet. .

In addition, the superconducting stabilization design of these large magnets reduces the heat generated by cooling (G) rather than the heat generated when a part of the conductor has a normal conduction transition (R)! A cryostatic stabilization method is used to increase (Q) so that the normal conducting part returns to the superconducting state without propagating.

The above heat generation (G) and cooling heat fi (Q) are expressed by the following equations.

That is, G=ρ/5-IL (1) Q=p
-h (2) However, (2) Current value ρ: Resistivity of the stabilizing material S Cross-sectional area of the stabilizing material p: Cooling surface area h: Heat flux between the conductor and helium.

From this equation, for a superconducting conductor, ρ is reduced, s, p
, h must be increased.

Of these, p and h are roughly determined by the dimensions and shape of the conductor, and if S is increased, the magnet becomes larger, which is a problem in terms of cost.

Therefore, as a stabilizing material for a superconducting conductor, it is necessary that the resistivity ρ is small, and pure copper is usually used.

However, when aluminum is used as a stabilizing material, stability is poor especially in high magnetic fields. In order to achieve sufficient stability, a large amount of heat is required, reducing the current density and increasing the magnet size.

This is because the temporary electrical resistance increases significantly with the magnetic field due to the magnetoresistance effect, so that the thermal conductivity decreases with the electrical resistance.

In short, the disadvantage of FE is that the resistivity increases with an increase in the magnetic field, that is, the magnetoresistive effect is large, and for this reason, it is desirable to use high-purity N, which has a small magnetoresistive effect, as a stabilizing material. ing. However, high-purity N has the disadvantage of low mechanical strength, particularly low fatigue strength, which poses a major problem in pulsed magnets where electromagnetic force is repeatedly applied to the conductor.

<Means for Solving the Problems> The present invention was obtained as a result of studies to solve the above-mentioned conventional defects.

That is, this invention uses a pure Al rod with a purity of 99.9% by weight or more and an N containing 0.2 to 0.6% by weight of Mg and Si, respectively.
After coating with alloy and forming into final shape, heat at 150℃ or higher, 190℃
The present invention provides a method for producing a stabilizing material for a composite superconducting conductor, which is characterized by heat treatment at a temperature of 1 hour or more and 70 hours or less at a temperature of 0.degree. C. or lower.

<Effect> The present invention will be explained below with reference to the drawings.

In Figure 1, 1 is 0.2 to 0.6% of -1SL, respectively.
This is high-purity N that coats the containing N alloy layer 2.

As shown in the cross-sectional structure of FIG. 1, this invention uses an N material coated with an N alloy on a collective conductor as a stabilizing material. Here, the N alloy-coated high-purity N is produced by extruding a composite billet prepared by placing a high-purity N rod in an N-alloy tube, or by composite wire drawing of an N-alloy pipe and a high-purity N rod.

In addition, 3 in FIG. 1 is Nb Ti or Nb, S
This is a Tl ultrafine multicore superconducting wire.

In this invention, the N alloy that is the material of the N alloy layer covering the outer periphery of the high purity N rod has a SL of 1 and an SL of 0.2 to 0.
It is characterized by containing 6% of M, and this is to increase the strength of M without reducing the electrical resistance.

The content of this -1SL in the N alloy is 0.2 to 0.6%.
This is because if it is less than 0.2%, it is insufficient to increase mechanical strength, and if it is more than 0.6%, it will cause a large increase in electrical resistance, rough processing, and deteriorate workability. This is because it is not desirable.

In addition, to show another example of the stabilizing material according to the present invention, as shown in FIG. It is coated with layer 2. This can be done by extruding composite billets, or by extruding N alloy pipes, high purity N pipes, or
It can also be produced by composite wire drawing of T and superconducting conductors.

<Example> This invention will be explained below with reference to Examples.

Outer diameter 70 made of N alloy with the composition shown in Table 1 below,
Put a 99.92% N rod into the tube, and add the same N to the top and bottom.
A lid made of an alloy was placed on the tube, the inside of the N alloy tube was evacuated in a vacuum chamber, and then the lid was electron beam welded to produce a composite billet.

This was processed using a hydrostatic extruder for 30. Extruded to ψ. Here, the N alloy coverage is 15%.

Next, the extruded material was stretched and rolled to produce two 3 x 16 m-sized plates and one 5 x 10 mJ plate, and heat treated under the conditions shown in Table 1.

These plate materials and a separately manufactured 5 x 5 mta m
-T, a large-capacity superconducting conductor was obtained by adhesively bonding ultrafine multicore superconducting wires with solder (Pb-Sn eutectic alloy).

Note that Sn was electroplated in advance on the surface of the N alloy layer to enable solder bonding.

On the other hand, 8! according to this invention! M4 diameter M alloy coated high purity M
The fatigue strength of the rod was investigated by rotating bending fatigue test. Furthermore, the electrical resistivity was measured at 4 and 2K. The results are shown in Table 1.

In addition, compared to the 99.92% M bar measured for comparison,
It was observed that the electrical resistivity was reduced and the fatigue strength was also significantly improved.

Table 1 <Effects of the Invention> As described above, the method for producing the stabilizing material of the present invention uses 0.2 to 0.6 SL of each SL as a stabilizing material for superconducting composite conductors.
This method uses a high-purity M rod coated with an N alloy containing % of N, and has a greater ability to stabilize superconductivity than that normally used as a stabilizing material for superconductivity.

This is because N is used, which has a lower electrical resistivity than Go at extremely low temperatures, especially in high magnetic fields, and also because the electrical resistance of high-purity M is reduced by heat treatment after forming it into the final shape. be.

Additionally, fatigue cranks in normal stabilized materials occur on the surface of the material and propagate internally.

In this invention, the outer circumference of the material is 1, and the Sj is 0.2 to 0.6%.
By coating it with the added N alloy, we were able to improve its fatigue resistance.

[Brief explanation of drawings]

FIG. 1 is a sectional structural view showing an example of a stabilizing material made by the method of the present invention, and FIG. 2 is a plan view showing another example of the present invention.

Claims (1)

[Claims] A pure Al rod with a purity of 99.9% by weight or more is mixed with Mg and Si.
For use in composite superconducting conductors, which is coated with an Al alloy containing 0.2 to 0.6% by weight of each of Method of manufacturing stabilizing material.