JPS6148577B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to provide a bright annealing method for heat-treating copper-coated composite materials such as superconducting wires in the atmosphere in a short time and easily.

The conventional method for annealing copper-coated composite materials is to use the following furnace.

(1) Matsufuru furnace or flowing air furnace (2) Nitrogen or argon atmosphere furnace (3) Reducing atmosphere furnace (4) Vacuum annealing furnace (5) Salt bath The above method (1) is simple, but the atmosphere Since it is in the atmosphere, there is a risk of copper oxidation. Therefore, a bisque firing process is required.

In addition, in methods (2) and (3) above, it is necessary to first replace the atmosphere with nitrogen, argon, or reducing gas, so this replacement takes a long time for parts with fine wires or complex uneven surfaces. Not only will it be incomplete, but it will also be incomplete. Furthermore, it is difficult to perform annealing work in a short time.

Furthermore, the methods (2), (3), and (4) above are difficult to manage in terms of equipment, and it is difficult to perform operations such as short-time annealing and rapid cooling (quenching).

Furthermore, in the methods (1), (2), (3) and (4), the radiant heat from the heat source to the material is not controlled, so the uniform heating of the material becomes poor due to the radiant heat.

In addition, the method (5) above has problems in that it is difficult to remove the salt as it penetrates into the small recesses of the material, and it is difficult to dispose of the waste solution in which the salt is dissolved in water or the like.

The present invention has been made as a result of intensive research aimed at improving these drawbacks, and as a result has discovered a heat treatment method that provides a copper-coated composite with an excellent bright surface. That is, the method of the present invention is characterized in that the surface of the copper-coated composite is coated with a lubricant, the outer periphery is further wrapped and sealed with copper foil, and then annealed in an atmospheric furnace and then water-cooled. It is something to do.

The reason why the surface of the copper-coated composite material is coated with lubricating oil in the method of the present invention is to prevent the copper-coated composite materials from adhering to each other, and because the lubricating oil decomposes at the annealing temperature and generates weakly reducing gas. .

The lubricants mentioned above include vegetable oil, mineral oil,
Any animal oil may be used as long as it has lubricating properties.

In addition, the reason for covering with copper foil in the method of the present invention is as follows.
This is to prevent radiant heat without directly heating the copper-coated composite material, to heat the composite material evenly, and to prevent decomposition gas from flowing into the furnace due to the lubricant. Furthermore, when cooling the composite material after annealing, it prevents local cooling and allows uniform cooling, and since the surface of the copper foil is covered with a copper oxide film, heat conduction during cooling is improved, and the cooling of the composite material is improved. can be promoted.

Note that the copper foil must be provided in such a way that there are no voids in the composite, and for this purpose it is necessary to wrap it by lap winding or the like. Also, the thickness of the copper foil is
The thickness is preferably about 15 to 30 μm; if it is too thick, the winding operation described above becomes stiff and cannot be wrapped sufficiently.

In addition, the copper-coated composite material in the present invention is Cu/Ta/
Any composite material whose exterior is coated with copper, such as CuSn/Nb, Cu/NbTi, or Cu/Fe, may be used.

In the present invention, the annealing temperature is 250 to 800°C and the annealing time is about 10 to 60 minutes.

Next, examples of the present invention will be described.

Example 1 A copper-coated composite material having an outer diameter of 15 mmφ and a length of 3 m was obtained by embedding 1200 Nb cores in a CuSn alloy, covering the outside with a Ta tube, and further covering the outside with copper. In order to make this composite material thinner, it was softened by intermediate annealing at every 60% processing rate. That is, a 10 mmφ composite material is annealed in the air at 600℃ for 30 minutes, and after removing the oxidized exterior with sandpaper, the penetration is approximately 15 mm.
%, die processing was performed using rapeseed oil as a lubricant up to a diameter of 6.7 mmφ. The composite after processing has a diameter of approximately 700mm.
It was a bunch of. This bundle was divided into two equal parts and annealed by the method of the present invention and the conventional method as follows.

Method of the present invention A bundle of composite materials with a diameter of 6.7 mm is attached to a spring with rapeseed oil lubricating oil attached, and a 20 μm thick bundle is attached to the outer periphery of the bundle.
After 1/2 lap winding with copper foil having a width of 60 mm, air annealing was performed at 600°C for 30 minutes in a Matsufuru furnace.
Afterwards, it was cooled with water and the copper foil was removed.

Conventional method A bundle of 6.7 mm composites was annealed in air at 600°C for 30 minutes in a Matsufuru furnace, and then cooled with water.

The properties of the copper-coated composites obtained by the method of the present invention and the conventional method were measured, and the results were as follows.

Method of the Invention The copper of the composite was not oxidized at all and had a bright surface. Also, 0.3mm depending on the die
Although the wire was machined to φ, no wire breakage occurred.

Conventional method The copper in the composite is oxidized and becomes a stronger film towards the inside, and when this was processed with a die, the wire broke three times due to uneven deformation resistance.

According to the method of the present invention, since the copper foil is densely provided on the surface of the composite, the following effects can be obtained.

(1) Since the copper foil shields radiant heat from the heat source, it has an excellent bright surface with no uneven annealing or uneven gloss.

(2) It is extremely easy to work with.

(3) The surface oxide film of copper foil improves thermal conductivity during heating or cooling, making it easy to control annealing time.

Claims (1)

[Claims] 1. Copper-coated composite material characterized in that the surface of the copper-coated composite material is coated with a lubricant, the outer periphery of the material is further covered and sealed with copper foil, and then annealed in an atmospheric furnace and then water-cooled. Method of annealing the material.