JPS6156848B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in superconducting magnets, and particularly to an insulating layer made of an insulating material provided around the outer periphery of an unreacted superconducting composite wire.

Conventionally, a reactive superconducting composite wire 1 coated with an insulating coating for forming a superconducting magnet is, for example, a composite wire 1 in which a plurality of filaments 3 made of niobium are embedded in a carrier metal 2 made of a CuSn alloy matrix, as shown in FIG. An insulating layer 4 is provided by wrapping an insulating material such as glass roving around the outer periphery of the reactive superconducting composite wire.

After winding this composite wire 1 around a winding frame, a diffusion heat treatment is performed to form a compound superconductor 5 at the interface between the carrier metal 2 and the filament 3, as shown in FIG. A compound superconducting magnet can be obtained using this method.

However, this diffusion heat treatment temperature is usually 600 to 900
℃, the insulating layer, that is, the glass fiber, is easily softened, and this softened glass melts and flows out, resulting in a structure in which the insulating layers that are in contact with each other are extruded and removed, as shown in Figure 2, and the winding is completed. The wires come into contact only at the carrier metal 2. Therefore, an electrical short circuit occurs and a superconducting magnet cannot be formed.

Contrary to the above, if the insulating layer of the composite wire is made of an insulating material with a high melting point that does not soften at all at the diffusion heat treatment temperature, the composite wires will not be fused to each other at all, so after the diffusion heat treatment This is a major problem as the windings of the magnet move for some reason, causing the superconducting magnet to become sluggish and unstable.

As a result of intensive research aimed at improving these drawbacks, the present invention has developed a superconducting magnet in which the insulating layer provided around the outer periphery of the unreacted superconducting composite wire is formed of an insulating material that does not soften or flow out even when subjected to diffusion heat treatment. This is what I found. That is, the present invention includes a carrier metal containing a metal element (A) having a lower internal melting point among the constituent elements of the superconducting compound, and a filament of a metal element (B) having a higher internal melting point among the constituent elements of the superconducting compound. After winding an unreacted superconducting composite wire with an insulating layer provided with an insulating layer on the outer periphery of a plurality of embedded unreacted superconducting composite wires, diffusion heat treatment is performed to form a compound superconductor at the interface between the filament and the carrier metal. In the superconducting magnet, the insulating layer is formed of a glass fiber layer containing 10 to 90% by volume of an insulating material having a softening temperature higher than the diffusion heat treatment temperature, or a glass fiber layer having a softening point higher than the diffusion heat treatment temperature. It is formed by alternately providing layers of insulating material.

An example of the present invention will be explained in detail based on the drawings. As shown in Fig. 3, an insulating tape made by blending quartz with 50% by volume of glass fibers around the outer periphery of an unreacted superconducting composite wire in which a plurality of filaments 3 made of niobium are embedded in a carrier metal 2 made of a CuSn alloy matrix. 6 was wound to obtain a non-superconducting composite wire 7 with an insulating layer. This composite wire 7 is wound around a winding frame and approximately
When diffusion heat treatment was performed at 700°C, as shown in Fig. 4, only the glass in the tape 6 softened and melted during the diffusion heat treatment and penetrated into the voids of the winding, but quartz did not melt at the diffusion heat treatment temperature. does not soften and maintains its shape before heat treatment, so it has excellent insulation properties.

In addition to the above-mentioned quartz, alumina, boron oxide, etc. can be used as the substance having a softening point higher than the diffusion heat treatment temperature in the present invention.

The reason for limiting the amount of the high melting point insulating material to the glass fiber is from 10 to 90% by volume.If it is less than 10%, it may be a material that does not soften at the carrier metal 2 and diffusion heat treatment temperature in the low temperature region after combustion treatment. It has the same effect as glass fiber alone, and there is a risk of it softening and flowing out. Moreover, if it exceeds 90%, the amount of glass is extremely small, so the amount of fusion due to softening of the glass decreases, which may cause movement or loosening of the winding wire.

Further, as an insulating layer in the present invention, a glass fiber layer such as a glass fiber tape is wound around the outside of the glass fiber layer, and an insulating material having a softening point higher than the diffusion heat treatment temperature, such as a quartz fiber tape, is wound around the outer side of the glass fiber layer, and both of these layers are alternately provided. may be formed. In this case, the thickness of the glass tape and the quartz tape is not particularly limited, but it is preferable that the ratio of the glass tape thickness to the quartz tape thickness be 90:10 to 10:90.

As detailed above, according to the present invention, the insulating layer provided on the outer periphery does not melt due to the diffusion heat treatment, and the compound superconducting wires are easily fused to each other via the insulating layer, so that the compound superconducting wire does not move or loosen. It has remarkable effects such as producing a superconducting magnet that can be used safely for a long period of time without causing any damage.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a conventional unreacted superconducting composite wire with an insulating layer, FIG. 2 is a partially enlarged sectional view showing an example of a conventional superconducting magnet, and FIG. 3 is an insulating layer according to the present invention. FIG. 4 is a cross-sectional view showing an example of an unreacted superconducting composite wire, and FIG. 4 is a partially enlarged cross-sectional view showing an example of the superconducting magnet of the present invention. DESCRIPTION OF SYMBOLS 1... Unreacted superconducting composite wire with insulating layer, 2... Carrier metal, 3... Filament, 4... Insulating layer, 5... Compound superconductor, 6... Insulating layer, 7...
...Insulating layer unreacted superconducting composite wire.

Claims (1)

[Claims] 1. After winding an unreacted superconducting wire that is composited and provided with an insulating layer on the outer periphery in order to form a compound superconductor at the interface of at least two types of metal substrates by a diffusion reaction,
In the superconducting magnet subjected to the diffusion heat treatment,
The insulating layer is formed of a glass fiber layer containing 10 to 90% by volume of an insulating material having a softening temperature higher than the diffusion heat treatment temperature, or a glass fiber layer and an insulating material layer having a softening point higher than the diffusion heat treatment temperature. A superconducting magnet characterized in that it is formed by alternately providing and.