JPS6119010A - Method of producing superconductive wire with solder - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for manufacturing a superconducting wire, in which a superconducting wire is successively assembled and soldered into a housing made of oxygen-free copper having high mechanical strength.

Generally, compound superconducting wires manufactured by the bronze method or the in-situ method are subjected to high-temperature and long-term heat treatment in the final step of the composite material in order to form a compound superconductor. As a result, the wire was completely annealed and its mechanical strength was significantly reduced, making it unsuitable for use as a winding wire for a magnet for high magnetic fields. Therefore, by soldering a stabilizing material of oxygen-free copper of IA to 1/2 hard material to the Nb5SnHi conductive wire obtained by heat treatment, the required characteristics as a multi-winding wire were satisfied. However, in this case, a clean copper surface is required in order to minimize the dullness of the stabilizing material by soldering and to prevent a decrease in the thermal conductivity of the surface of the wire used as a winding wire. Conventionally, this soldering has been done by sandwiching a solder tape between the superconducting wire and the stabilizing material and continuously heating and soldering, or by placing solder in molten metal to prevent solder from adhering to the surface of the part where soldering is avoided. This is a non-soldering process in which a film is formed, and the parts that require soldering are partially coated with flux and immersed in molten solder to perform soldering.

However, in the former method, id occurs due to poor degassing when joining with the housing, and when heated in a furnace in a non-oxidizing atmosphere (・X・Ar + N2, etc.), heat conduction is poor and long-term processing is required. In the latter method, it is difficult to treat the non-solder parts and the flux in the soldered parts, and the solder pools in the joint parts. However, there was a problem in that the flux attacked the non-soldered parts, causing solder to adhere to these parts. In addition, since molten metal is used, there is a problem in that the oxide formed on the surface of the molten metal is rolled into the soldering surface and becomes a so-called gate that is not in contact with the soldering surface.

Furthermore, the latter method has the advantage that the Cu base material is less dull because it allows the Cu base material and the superconducting wire at room temperature to pass through a solder bath for a short time and solder by rapidly heating only the surface portion. Otherwise, the above-mentioned inconvenience may occur.

The reason for soldering only the bonded parts and not coating the other parts with copper-based stabilizing material is that if the entire surface of the stabilizing material is soldered, the solder film will not provide thermal conductivity. This is because the cooling effect of the superconductor is significantly reduced. Therefore, it is only necessary to solder only the minimum necessary portion of the stabilizing material.

As a result of extensive research in view of the current situation, the present invention has discovered a method for bonding superconducting wires and stabilizing materials without applying solder to surfaces other than those to be bonded. be.

That is, in the method of the present invention, a superconducting wire is assembled into a housing of a stabilizing material and soldered to join.Soldering is a superconducting wire manufacturing method in which a surface of the stabilizing material other than the surface to be joined is subjected to an oxidation treatment. After the oxidizing film is provided, the superconducting wire and the stabilizing material are immersed in a flux that does not attack the oxidizing film, and the parts other than the oxidizing film are soldered. .

The method of the present invention involves immersing a stabilizing material with a copper oxide coating on the non-bonding surface together with a superconducting wire in flux, then passing it through a preheating furnace and immersing it in a solder bath to simultaneously solder the oxygen-free steel. Since this is a method of incorporating superconducting wires into the housing, it is necessary that the copper oxide coating on the non-bonded surfaces is not attacked by flux, and for this purpose, the thickness of the copper oxide coating must be approximately 0.8 to 1.5 μm. It is limited to. The reason is that after soldering, the oxidized steel coating is as thin as 0.8μ.
There is a risk that solder may adhere to the surface here and there.
In addition, when the copper oxide film on the surface of the copper base material becomes thicker than 1.5 μm, powdery copper oxide is formed, which becomes powdery foreign matter and sometimes gets caught up in the solder adhesion layer during soldering, creating a gate. It is something. In addition, it is preferably 1.0 to 1.4μ.

Also, the flux is used for soldering the Cu stabilizer and superconducting wire.
L must exhibit sufficient functionality, and for this purpose, a water-soluble flux with a specific gravity in the range of 0.82 to 0.85 is preferably used, such as 0683.

Further, the present invention can be applied to both compound superconducting wires and alloy superconducting wires. Next, examples of the method of the present invention will be described.

As shown in the example drawings, a Cu profiled material 1 with a U-shaped cross section and a convex shape C
Partially oxidize 3゜3' on each of the u-shaped members 2,
A CuO film of 1.0±0.2 μ(t) was formed. On the other hand, the superconducting wire is placed between Cu shaped members 1 and 2, passed through a water-soluble flux solution whose specific gravity is adjusted to 0.83 to 0.84, and passed through a preheater to remove the solvent in the flux. At the same time as the removal, the U superconducting wire is preheated, and the whole is placed in a molten solder at 250°C. At the same time, it is held down with a graphite mold, and the integrated superconducting wire slides inside the graphite mold and is transferred to a cooling zone, where the solder solidifies and composites. It was done. The surface of the superconductor was in good condition with no solder adhesion.

As detailed above, according to the method of the present invention, when a superconducting wire is incorporated into a stabilizing material of a copper base material, the superconducting wire and the stabilizing material can be easily joined without reducing the conductivity of the stabilizing material. It is extremely useful industrially as it improves workability.

[Brief explanation of the drawing]

The drawing is a cross-sectional view showing an example of a mold material for manufacturing a superconducting wire by soldering according to the present invention. 1... U-shaped profiled material, 2... Convex profiled profile, 3.
3'... Oxide film.

Claims (1)

[Claims] (1) In a method for manufacturing a soldering superconducting wire in which a superconducting wire is assembled into a stabilizing material and joined by soldering, the surface of the stabilizing material other than the surface to be joined is subjected to an oxidation treatment. After forming an oxidizing film, the superconducting wire and the stabilizing material are immersed in a flux that does not corrode the oxidizing film, and the parts other than the oxidizing film are soldered. Method of manufacturing superconducting wire. (2) Specific gravity as flux: 0.
The method for manufacturing a soldered superconducting wire according to claim 1, characterized in that a water-soluble flux having a molecular weight of 82 to 0.85 is used. (3) The method for manufacturing a soldered superconducting wire according to claim 1, characterized in that the thickness of the oxidizing film is 0.8 to 1.5 μm.