JPH04106809A - Superconductor - Google Patents

Abstract

PURPOSE:To obtain a superconductor which can be covered with a thin enameled insulating layer at a low cost by joining a stabilizing metal and an Nb-Ti alloy superconducting wire with a brazing filler metal whose melting point is specified. CONSTITUTION:Stabilizing metal 3 and Nb-Ti alloy superconducting wire 1 are joined with a brazing filler metal 2 whose melting point is of 320 deg.C-620 deg.C. By using Zn as the brazing filler metal 2 for example, the wire 1 is heated and joined, and thereafter, it is bake coated with formal 4 at 300 deg.C. The melting point of Zn is 420 deg.C and higher than the temperature at which the formal 4 is bake coated on the wire 1, so that the brazing filler metal 2 is not molten and therefore, their joinability is good. If the temperature exceeds 620 deg.C, the characteristics of Nb-Ti alloy superconducting wire 1 are deteriorated by heat at the time of joining with the barzing filler metal. It is thereby possible to apply enameled insulation at a low cost and thin the insulating covering layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a superconducting conductor in which a stabilizing metal and a superconducting wire are joined using a brazing material.

[Conventional technology and its issues]

For NbTi and Nb5Sn superconducting conductors used in MRr, etc., the stabilizing metal and the superconducting wire 9 are separated for reasons such as low-temperature stabilization, reduction of reinforcement cost, increase in unit length as a conductor, and stable production of conductors with a large Cu ratio. Manufactured in
A superconducting conductor with a structure in which both are joined using a brazing material is used.

Conventionally, this brazing filler metal contains Sn30-50wt% balance P
Solder consisting of B was used.

However, this conventional solder has a melting point of 183°C to 220°C.
Because the temperature is low, insulation is used as an insulating coating after bonding, which reduces the current density of the entire superconducting conductor due to the increase in the insulating layer, and the magnetic field uniformity due to variations in the number of turns when winding around the magnet. Furthermore, there were problems such as a decrease in the amount of water and an increase in manufacturing costs.

For this reason, there is a strong desire to develop a superconducting conductor with a structure in which a stabilizing metal and a superconducting wire are bonded, which has a thin insulating layer (and which can be coated with an inexpensive enamel insulating layer).

[Means to solve the problem]

The present invention was developed as a result of intensive studies in view of the above situation, and the invention of claim 1 provides a superconducting conductor having a structure in which a stabilizing metal and a Nb-Ti alloy superconducting wire are joined using a brazing material, A superconducting conductor characterized in that a brazing material having a melting point of 320° C. to 620° C. is used, and the invention according to claim 2 is a superconducting conductor having a structure in which a stabilizing metal and a Nb3Sn compound superconducting wire are joined using a brazing material. , the melting point is 3
This is a superconducting conductor characterized by using a brazing material having a temperature of 20'C or higher.

(Function) The present invention has a processing temperature of 28
By using a brazing filler metal with a melting point higher than 0°C to 300°C, we have developed a superconducting conductor with an enamel insulation coating that has a thin and inexpensive insulation layer.

In the first invention, the melting point of the brazing material is 320°C to 620°C.
The reason for this limitation was that if the melting point was less than 320°C, the filler metal would melt during the enamel insulation coating;
This is because, if the temperature exceeds 100%, the properties of the NbTi alloy superconducting wire will deteriorate due to heat when joining with the brazing material.

In the second invention, the melting point of the brazing filler metal is set to 320° C. or higher, and the upper limit is not limited only to the lower limit.

This is because the Sn compound superconducting wire does not suffer from characteristic deterioration due to heat, unlike the Nb-Ti alloy superconducting wire.

Further, as the superconducting wire in the present invention, NbTi alloy,
An alloy-based or compound-based multicore structure monolith klA (that is, a strand before twisting), a formed stranded wire, or the like is used.

〔Example〕

The present invention will be explained in more detail below with reference to Examples.

Example 1 As shown in FIG. 1(a), the thickness is 2.00 mm and the width is 4.0 mm. OOm
Nb-Ti alloy superconducting wire 1 with a thickness of 4.00 mm and a width of 8
．． It was embedded in the stabilizing source 3 of OO Kenkaku, and heat-bonded using Zn as the brazing material 2. Thereafter, Formal 4 was baked and coated at 300°C. The melting point of Zn was 420° C., which was higher than the baking coating temperature of formal, so the brazing filler metal 2 did not melt and the bondability was good.

Comparative Example 1 For comparison, the same superconducting conductor as in Example was manufactured using a Pb-Sn alloy whose melting point was adjusted to 250°C, 1285°C, and 310°C as a brazing material, and the same superconducting conductor as in Example 1 was formalized. However, in both cases, the filler metal melted and the joints were defective.

Example 2 The same superconducting conductor as in Example 1 was manufactured using silver solder whose melting point was adjusted to 605° C., and formal was baked and coated in the same manner as in Example 1.

Comparative Example 2 As a comparison, the same superconducting conductor as in Example 1 was manufactured using silver solder whose melting point was adjusted to 625° C. and 635° C., and formal was baked and coated in the same manner as in Example 1.

Conventional example For comparison, Pb-Sn whose melting point was adjusted to 200°C
The same superconducting conductor as in Example 1 was manufactured using the alloy,
The insulation was then covered with Kapton tape.

For the superconducting conductors of Examples 1 and 2, Comparative Example 2, and Conventional Example obtained in this way, the current was gradually increased in liquid He (4,2'K) with a magnetic field of 5 T applied. When the resistance reaches IQ-II ΩΩ, the critical tf
L density Jc was measured for a short product with a length of 1 m. The results are shown in Table 1. The cost required for the insulation coating is also listed in Table 1.

〔Effect of the invention〕

As described above, according to the present invention, enamel insulation, which is an inexpensive insulation, is possible, and the insulation coating layer can be made thinner, so that the critical current density J of the entire conductor can be reduced.

can be improved, and has a significant industrial effect.

[Brief explanation of drawings]

FIG. 1 is a structural diagram showing an example of a superconducting conductor according to the present invention. 1... Superconducting wire, 2... Brazing metal, 3... Stabilized copper, 4... Formal.

Claims (1)

[Claims] 1) A superconducting conductor having a structure in which a stabilizing metal and a Nb-Ti alloy superconducting wire are joined using a brazing material, the melting point of which is 32.
A superconducting conductor characterized by using a brazing material having a temperature of 0°C to 620°C. 2) A superconducting conductor having a structure in which a stabilizing metal and a Nb_3Sn compound superconducting wire are joined using a brazing material, characterized in that a brazing material having a melting point of 320° C. or higher is used.