JPH05190030A - Coated superconducting conductor - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a coated superconductor in which the insulating layer is prevented from peeling off from the outer surface of the superconducting conductor due to a load generated during coil fabrication. [Structure] A metal sheet 4 to which a high-strength insulator is bonded in advance is bonded to a normal conductor and a solder layer containing a superconductor 2 with a low melting point solder. [Effect] The shear strength of the insulating layer is increased, the joint strength between the insulating layer and the outer surface of the superconducting conductor is also increased, the insulating layer is not separated in the insulating layer during coil production, and the insulating layer is separated from the outer surface of the superconducting conductor. Is not peeled off, and the insulation function and cooling function can be secured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting conductor having therein a superconductor made of a superconducting material.

[0002]

2. Description of the Related Art A conventional coated superconducting conductor having a superconductor made of a superconducting material has an insulating layer formed on the outer peripheral surface of the superconducting conductor as described in, for example, Japanese Utility Model Publication No. 3-68317. Insulated. This insulating layer is formed by dip coating, electrodeposition coating, or the like. Immersion coating is a coating method in which a body to be coated is immersed in a coating solution of polyvinyl formal coating, pulled up, and then baked and dried. In addition, electrodeposition is performed by inserting electrodes into a water-based coating liquid such as a water-dispersible epoxy / acrylic resin varnish, a water-soluble polyimide resin varnish, a water-dispersible polyurethane resin varnish, or a non-hydrogen polyimide dispersion varnish. Is a coating method in which paint particles having a negative charge are moved toward the anode by the current of (1) to be deposited on the anode plate, and then pulled up, baked, and dried.

The superconducting material is not particularly limited, and metallic superconducting materials include niobium, titanium and niobium tin, and oxide superconducting materials include barium, yttrium, copper, oxygen and barium lanthanum.・ There are compounds with the composition of copper / oxygen, strontium / lanthanum / copper / oxygen, barium / scandium / copper / oxygen, calcium / lanthanum / copper / oxygen.

Further, a superconducting conductor is formed by providing a normal conductor layer made of copper, aluminum, silver or the like on the outer peripheral portion of the superconductor, and the resistance value becomes smaller when a part of the superconducting state is broken. An electric current flows to the normal conductor side of the outer peripheral portion, heat generation is suppressed to a minimum, and this calorific value is absorbed by a refrigerant such as liquid helium outside the normal conductor layer to prevent the destruction of the superconducting state from spreading to the whole. At this time, the heat absorption characteristics are improved by the insulating layer provided on the outer peripheral surface of the superconducting conductor.

A superconducting magnet is manufactured by winding this coated superconducting conductor in a coil shape by a bending machine or the like.

[0006]

When the above-mentioned coated superconducting conductor of the prior art is wound into a coil by a bending machine or the like, the insulating layer is sandwiched between the superconducting conductor and the roller of the bending machine. As a result, a shearing force acts between the insulating layer and the outer surface of the superconducting conductor, inside the insulating layer, and between the insulating layer and the roller of the bending machine. However, the shear strength of the insulating layer itself is small, and in the above coating method, the bonding strength between the insulating layer and the outer surface of the superconducting conductor is also small.
Therefore, there is a problem that the insulating layer is separated in the insulating layer at the time of manufacturing the coil, or the insulating layer is separated from the outer surface of the superconducting conductor, so that the insulating function and the cooling function are significantly deteriorated.

[0007]

In order to solve the above problems, a metal sheet coated with an insulator is thermally connected to the surface of a normal conductor or the surface of a solder layer.

[0008]

The superconducting conductor fused to the normal conducting conductor with solder melts at high temperature, so that the superconducting conductor and the polymer insulating material cannot be heat-treated at a high temperature at the same time. Therefore, in advance, a high-strength insulator is formed on the surface of the superconducting conductor by joining the superconducting conductor that has been welded to the normal conducting conductor with solder and the metal sheet that covers the insulator with a low melting point solder whose melting point is lower than the melting point of the solder. can do. The insulating material used here is polyimide, whose electrical and mechanical properties are hardly deteriorated even at the temperature at which the low melting point solder melts. Further, this polyimide has a mechanical strength of about 5 times that of conventional epoxy-based polymer materials, and therefore can withstand the load applied during coil fabrication.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows the overall structure of the superconductor. A normal conductor layer made of aluminum or copper, a superconductor made of a metal or oxide superconducting material, a solder layer made of lead and tin, a copper, nickel alloy or stainless steel sheet 4, and a polyimide The insulator 5 is made of a polymer insulating material.

FIG. 2 shows a superconductor 2 and a normal conductor layer 1 of FIG. 1 joined by a solder layer 3 to form a single lump, and a sheet 4 and an insulator 5 integrated with each other. The surface of the sheet 4 in contact with the sheet 4 and the solder layer 3 is plated with a low melting point solder having a melting point temperature lower than the melting point of the solder used in the solder layer 3. After the structure as shown in FIG. 1, the entire superconductor is heated to melt the low melting point solder plating. At this time, since the low melting point solder melts between the solder layer 3 and the sheet 4, the solder layer 3 and the sheet 4 are joined after the entire superconductor is cooled to room temperature.

The polyimide insulator 5 has a higher tensile strength than the epoxy insulator and has a strength five times or more that of epoxy. Therefore, even if a shearing force is applied to the polyimide insulator 5 by the roller of the bending machine, the polyimide insulator is less broken than in the conventional case. Further, since the polyimide insulator 5 and the sheet 4 are adhered to each other by melting the polyimide insulator at a high temperature and welding it to the surface of the sheet 4, high peel strength can be obtained. Therefore, the insulating layer is not separated in the insulating layer during manufacturing of the coil, and the insulator is not separated from the outer surface of the superconducting conductor.

The sheet 4 has a different thickness depending on the thermal conductivity of the material. For example, a suitable thickness is 160 μm or less for stainless steel and 1200 μm or less for copper-nickel alloy. This is determined by the relationship between the amount of heat released from the surface of the superconducting conductor and the thermal conductivity and thickness of the sheet. By forming a polyimide insulator on the surface of this sheet, an insulating function and a cooling function can be secured.

FIG. 3 shows another embodiment of the present invention. Figure 3
The superconductor 2 is contained in the normal conductive layer 1. The superconductor 1 is hardened by the solder layer 3 and does not move even when a magnetic stress is applied. Sheet 4
The insulator 5 and the insulator 5 are integrally formed into a tape shape. Further, low melting point solder is plated on each surface where the sheet 4 and the normal conductive layer 1 are joined. After wrapping the tape-shaped sheet 4 and the insulator 5 around the normal conductive layer 1, heating to a temperature at which the low melting point solder melts and then cooling to room temperature makes it possible to form an insulator having excellent mechanical strength. Become. Therefore, even when the coated superconducting conductor is wound into a coil by a bending machine or the like, the insulator is bonded to the surface of the superconducting conductor without peeling. Therefore, the superconducting conductor has an insulating function and a cooling function.

[0015]

According to the present invention, a metal sheet to which a high-strength insulator is joined and a normal-conducting layer or a solder layer containing a superconductor are connected by a low melting point solder, so that the superconducting conductor has a high-strength insulation. Can form a body. Therefore, when the coil is manufactured, the insulating layer is not separated in the insulating layer, and the insulating layer is not separated from the outer surface of the superconducting conductor, so that the insulating function and the cooling function can be secured.

[Brief description of drawings]

FIG. 1 is a sectional view of a coated superconducting conductor according to an embodiment of the present invention.

FIG. 2 is a perspective view of a coated superconducting conductor according to an embodiment of the present invention.

FIG. 3 is a perspective view of a coated superconducting conductor according to another embodiment of the present invention.

[Explanation of symbols]

1 ... Normal conductive layer, 2 ... Superconductor, 3 ... Solder layer, 4 ... Sheet, 5 ... Insulator.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsumi Muroi 502 Jinritsucho, Tsuchiura-shi, Ibaraki Prefecture Hiritsu Manufacturing Co., Ltd. Mechanical Research Laboratory

Claims (4)

[Claims] 1. A superconducting conductor having a normal conducting conductor arranged around a superconducting conductor and having an insulating layer on a cooling surface of the normal conducting conductor, wherein a metal sheet is arranged between the insulating layer and the normal conducting conductor. Characteristic coated superconducting conductor. 2. The coated superconducting conductor according to claim 1, wherein polyimide is used as a material of the insulating layer. 3. A superconducting conductor is welded to a normal conducting conductor with solder,
In the superconducting conductor having an insulating layer on the cooling surface of the normal conducting conductor or the solder layer, the coated superconducting device, wherein the metal sheet covering the insulating layer and the normal conducting conductor or the solder layer are welded with a low melting point solder. conductor. 4. The coated superconducting conductor according to claim 3, wherein polyimide is used as a material for the insulating layer.