JPS6362111A - Manufacture of nbti based compound superconductive alloy wire - Google Patents

Abstract

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

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing a NbTi-based compound superconducting alloy rim material that can be cooled to an extremely low temperature and can be cooled to an extremely low temperature to reduce electrical resistance to zero and allow a flow of 1 to flow. It is.

[Conventional technology]

Conventionally, as shown in Fig. 2, the method for manufacturing NbTi-based compound superconducting alloy binding materials involves inserting an NbTi rod into a copper tube and reducing the cross-section of the tube as one piece.
Wire rods with a diameter of several to several tens are cut, bundled into tens to thousands of pieces, and sealed in a copper container by electron beam welding.
This is extruded through hot extrusion at several hundred degrees Celsius into a rod shape with a diameter of several hundred degrees, then rolled and drawn.

It is manufactured through cross-sectional reduction processes such as wire drawing and swaging, and heat treatment to increase the critical current value by precipitation of the high-temperature β phase to the low-temperature α phase. The assembly diameter of NbTi filaments in the alloy assembly at the product stage is several tens of micrometers or less, but in recent years, magnetic field uniformity has become important for applications such as superconducting accelerators, so diameters of several tens of micrometers or less have been The filament diameter is becoming more demanding.

As mentioned above (the manufactured Nbτ1 compound alloy wire rod is
Depending on the application of various superconducting devices, the wire is made into one or more composite wires to accommodate the specified current capacity, formal insulation or glass insulation is applied, the wire is wound as a coil, and the wire is cooled to an extremely low temperature with liquid helium. I! By passing a large current in a state of zero ffi resistance, for example, nuclear fusion, accelerators, magnetic resonance medical diagnostic equipment, superconducting air levitation trains, etc.
Used as fi field generating arsenite.

[Problem that the invention seeks to solve]

However, in the above-mentioned method for producing NbTi-based compound superconducting alloy wire, the temperature is 250 to 5 degrees Celsius during or after the hot extrusion process and cross-section reduction process at several hundred degrees Celsius.
In the heat treatment process at 00°C.

T1 in the NbTi alloy and O in the stabilized copper undergo a diffusion reaction, forming an intermetallic compound of 0uTi.
NbTi is formed at the interface between the filament and the stabilizing steel. If this compound is formed into a shape g2 having a size close to the diameter of a flat filament, it will cause the filament to break or the wire itself to break in the cross-section reduction process, which will eventually cause a decrease in the critical current value.

and <K, ld for a wire with a filament diameter of several μm or less.
The presence or absence of the formation of the 0uTi compound has a great influence on the extensibility of the wire.

This invention was made in order to solve this problem, and it is an Nt
An object of the present invention is to provide a method for manufacturing a Tii compound superconducting alloy wire.

[Means for solving problems]

The method for producing a NbTi-based compound superconducting alloy binding material of the present invention includes the steps of arranging a NbTi-based compound as a superconducting alloy and O as a stabilizing metal in parallel, reducing the cross-section of this composite, and during the cross-sectional reduction processing step. At least one of these processing steps.

The present invention is characterized in that a step of heat-treating the cross-sectionally reduced composite is performed by applying a solid lubricating film treatment to the surface of the NbTi compound before the cross-sectionally reducing process.

[Effect]

The solid lubricating coating treatment on the NbTi surface in this invention is performed by treating NbTi and Ou during the heating process during manufacturing.
The diffusion reaction at the interface with 0uT1 is suppressed to prevent the growth of intermetallic compounds.

[Embodiments of the invention]

A NbTi rod with a diameter of 10flK was heated to 380″CK in the air.
It was heated to form a 1.5 μm oxide layer on the surface of the NbTi rod. This NbTi rod was placed in a container containing carbon powder, and heated at 1300° C. for 5 hours in a vacuum furnace to form a coating layer of carbide containing Nt)O on the surface of the NbTi rod. The coated NbTi core is covered with a steel pipe and cold-drawn as a single piece, resulting in NbTtl with a wire diameter of 1.24 and an NbTi core diameter of 0.89.
ou A single core wire was produced.

NbTi/(lu single core wire was straightened and straightened, and after cutting, 730 pieces were collected at the east exit, outer diameter 49n, inner diameter 4
It is housed in a copper container with two dragons, and the front and rear ends of the first one are closed with copper members.
The connections were welded using an electron beam.

The composite billet thus produced was heated to 500°C and hot extruded into a bar with an outer diameter of 18 tm.

This was subjected to cold drawing and heat treatment at 375°C for 10 hours twice in the middle of this process to produce NbTi, which is shown in the cross-sectional view of an embodiment of the present invention in FIG. 1 with a final wire diameter of 0.25n.
We fabricated superconducting alloy wire rods based on compound superconducting alloys.

In the figure, (1) is a NbTi/Ou single core wire, and (2) is a stabilized steel. This wire rod could be easily processed without producing any interruption lines during the drawing process. The copper portion of this wire was dissolved and removed using an acid such as nitric acid, and a scanning electron microscope revealed that no OuTi compound was formed on the surface of the filament due to heating.

The critical current density of the NtlTi-based compound superconducting alloy wire manufactured by the above process was measured.

At 4.2x, under a 5T magnetic field 285 OA/+j
.

1750A/+1 under 7T magnetic field! Very good current characteristics were obtained.

The method of coating the NbTi-based compound surface of this invention is not limited to the above-mentioned embodiments.
A method of forming NbN on the surface of NbTi using K when a rod is heated at 800~t's o o C in N2 or a mixed gas such as N2 and A2 @ 121
A plasma generation part is provided in the reaction tube using NgQ, j2 and 0Ii4 gas as carrier gas, and IJbT is placed in this part.
i. A method of arranging rods and depositing a NbO film on the surface;
(3) A method of accumulating NbQM by the method of 12) above using Nbo12, OH4, and NH3 as carrier gas, 141 Nt+O, NbN.

NbCN A method in which fine powders of graphite and molybdenum disulfide are mixed with volatile solvents such as carbon tetrachloride, alcohol, and gasoline, and the mixture is attached to the surface of the NbTi rod and dried.

(5) In the above (4), NbTi salary fi-2
Any method such as heating the NbTi surface to 50 to 450" to form a thin oxide layer to form a coating is also effective in preventing the formation of 0uTi intermetallic compounds in the method for producing a thin oxide layer of NbTi-based compound superconducting alloy, which is the object of this invention. In addition, physical vapor deposition, chemical vapor deposition, and plasma spraying of the above-mentioned materials can all be used in the present invention.

In addition, although the NbTi binary alloy has been explained as a superconducting alloy in the above embodiments, Mb-Ti -1Ta -
It can be widely applied to the production of NbTi-based compound superconducting alloy wires such as Nb-Ti-Zr.

〔Effect of the invention〕

As explained above, this invention uses Nb as a superconducting alloy.
A Ti-based compound and Ou as a stabilizing metal are placed side by side,
A step of reducing the cross-section of this composite, and a step of heat-treating the composite subjected to the cross-section reduction at least one of during and after the cross-section reducing step, wherein the MbTi before the cross-section reduction is By applying a process of treating the surface of the compound with a solid lubricating film,
0 observed at the interface between NbTi'-based compound and stabilized copper
It is possible to obtain a method for producing a NbTi-based compound superconducting alloy assembly in which uTi metal-based metal formation can be prevented, extensibility is improved, and critical current reduction is prevented.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a NbTL-based compound superconducting alloy wire according to a simple embodiment of the present invention, and Figure 2 is a cross-sectional view of a conventional Nt+Ti alloy wire.
FIG. 2 is a manufacturing process diagram of a superconducting alloy wire rod based on a superconducting compound. In the figure, (1) is a NbT1/Ou single core wire, +
21 is stabilized copper.

Claims (3)

[Claims] (1) A process in which a NbTi-based compound as a superconducting alloy and Cu as a stabilizing metal are arranged side by side, and the cross-section of this composite is reduced, and at least one of the cross-section reduction process and after this process is performed. A method for producing a NbTi-based compound superconducting alloy wire, characterized in that a step of heat treating the reduced composite is performed, and a step of applying a solid lubricating film treatment to the NbTi-based compound surface before the cross-section reduction processing is performed. (2) The coating on the NbTi surface is NbCNbN and NbCN
N according to claim 1, which is at least one of
A method for producing a bTi-based compound superconducting alloy wire. (3) The coating treatment is performed by adhering and drying a mixture of fine powder of at least one of NbC, NbN, NbCN graphite, and molybdenum disulfide in a volatile solvent to the surface of the NbTi-based compound, or NbTi as described in Section 2
A method for manufacturing a superconducting alloy wire rod.