JPH01281612A - Manufacture of oxide superconducting wire material - Google Patents

Abstract

PURPOSE:To improve superconducting characteristics and bending workability by feeding continuously a molten liquid of a raw material oxide as a superconductor and covering the surface of a travelling metal filament with the liquid and then applying heat treatment thereto at the predetermined temperature in an atmosphere containing an oxygen. CONSTITUTION:A powdered raw material oxide as a superconductor is filled in an alloy crucible and heated with a high-frequency coil 1, therebybeing changed to a molten liquid. Then, the molten liquid 4 of the raw material oxide is heated up to the predetermined temperature, and there after fed to the entire one side surface of a metal filament 6 running below the crucible 2 via a nozzle 5 screwed to the bottom of the crucible 2, thereby depositing a raw oxide layer 9 in various thickness and obtaining a wire material 8. According to the aforesaid construction, an oxide superconductor layer of high density and adhesion is formed on the surface of the metal filament 6. Consequently, it becomes easy to form an oxide superconducting wire material 8 having high superconducting characteristics and bending workability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing an oxide superconducting wire used for power cables, magnets, power storage links, magnetic shields, etc.

(Prior art and its problems) In recent years, (Ln+-xsr,)CuOj, (Ln,-
, Bax)zcuoa, LnBaxCu30q, L n
B a, -.

Oxide superconductors with a layered perovskite structure of Sr, Cu, O, etc. (wherein Ln is Y, Sc, or a rare earth element) have been discovered.

These oxide super-1 conductors become superconducting at temperatures higher than liquid N, so they are much more economical than conventional metal superconductors that exhibit superconductivity at liquid He temperatures, and their use in various fields is being considered. There is.

By the way, the above-mentioned oxide superconductors are brittle and cannot be plastically worked like metal materials, and powder metallurgy is mainly used to form them into wire rods and the like. This powder metallurgy method involves, for example, supplying raw material powder onto the surface of one metal strip or between two metal strips and rolling it to a desired thickness, or filling raw material powder into an Ag pipe or the like. A method is used in which the material is stretched and then heated and sintered in an oxygen-containing atmosphere.

However, the linear bodies obtained by such a method all had a low relative density of about 70 to 90%, and had extremely low superconducting properties such as critical current density (hereinafter abbreviated as J).

Furthermore, among the methods mentioned above, in which the raw material powder is applied to the metal strip, it is difficult to supply the raw material powder thinly and uniformly, and the adhesion to the metal strip is poor, so it is recommended to use it by winding it into a coil shape. In such cases, there are problems such as cracks occurring in the oxide superconductor layer or peeling of the oxide superconductor layer from the metal strip.

[Means to solve the problem]

The present invention was made in view of the above situation, and an object of the present invention is to provide a method for manufacturing an oxide superconducting wire having excellent superconducting properties and bending workability.

That is, in the present invention, a melt of a raw material oxide to become a superconductor is continuously supplied and deposited on the surface of a running metal strip, and then it is heat-treated at a predetermined temperature in an oxygen-containing atmosphere. It is characterized by this.

In the present invention, the raw material oxide that becomes a superconductor is Y +
A composite oxide having a composition of 20 g of B a z Cu , which becomes an oxidized ll1l superconductor by heat treatment at a predetermined temperature in an oxygen-containing atmosphere.

Any heating method such as high frequency induction heating, electric resistance heating, infrared heating, etc. can be applied to melt the raw material oxide (hereinafter abbreviated as raw material oxide) that becomes the superconductor.

In the case of Y-Ba-Cu-0 system (hereinafter abbreviated as Y system), a Pt or 21 alloy crucible is suitable for the crucible used to hold the melt of the above-mentioned raw material oxide; -3
For the r-Ca-Cu-0 system (hereinafter abbreviated as Bt system), crucibles made of CaO, MgO, etc. in addition to PT or PT alloy are applicable.

In the present invention, a metal strip made of Cu, Cu alloy, Ag, Ag alloy, SUS, etc. is used for supplying the raw material oxide melt.

In the present invention, the melt of the raw material oxide is deposited on the surface of the metal strip, in addition to being deposited on the entire surface of one side, as shown in FIG. It is possible to take any form of attachment depending on the application, such as attaching a plurality of stripes 9 to the surface of the metal strip 6 at intervals.

In the present invention, the deposition thickness of the raw material oxide melt varies depending on the nozzle exit size, the melt head in the crucible, the distance between the metal strip and the nozzle, the melt temperature, the running speed of the metal strip, etc. By selecting the above conditions, a thin raw material oxide layer with a uniform thickness can be deposited.

In the present invention, the adhesion between the metal strip and the raw material oxide layer depends on mutual thermal diffusion at the initial stage of deposition, and the metal strip is preheated to 40°C or higher before being coated. When they are attached to each other, the above-mentioned diffusion is promoted and the adhesion between the two is further improved. However, if the preheating temperature is too high, if the metal strip is made of a base metal such as Cu or a Cu alloy, the surface may be oxidized and the adhesion may be reduced.

The crucible used in the present invention is equipped with a nozzle at the bottom for supplying the melt of the raw material oxide, but if this nozzle part is structured so that it can be separated from the crucible body, it is possible to eliminate the need to replace the crucible. The deposition form of the raw material oxide can be easily changed, and the cost of parts can be reduced.

[Effect]

In the present invention, since the raw material oxide is supplied as a melt to the surface of the metal strip and deposited, a thin and uniform layer of the raw material oxide can be formed with high density and good adhesion. The oxide superconducting wire obtained by heat treatment has excellent superconducting properties, bending workability, etc.

〔Example〕

The present invention will be explained in detail below using examples.

Embodiment 1 FIG. 1 is an explanatory diagram of essential parts showing an example of an apparatus for carrying out the present invention. The above device consists of a crucible 2 around which a high frequency coil 1 is arranged for melting the raw material oxide, and a steel guide roll 3 with a diameter of 50 cm for guiding the metal strip to which the melt of the raw material oxide is deposited. 3' and a preheater 7 for preheating the metal strip.

In this example, Y2O2, BaCO5, and CuO powders were used as raw materials. These powders were blended and mixed to give the desired composition, then pre-sintered by heating with 920" C2OH in the air, and then pulverized and classified to form a superconductor. This raw material oxide was put into a crucible 2 made of PL-20%Rh alloy, and heated by a high frequency coil 1 to form a melt.

Next, the melt 4 of the raw material oxide is heated to 1.300°C, and then a nozzle 5 with a width of 10 cm and a thickness of 0.2
The raw material oxide layer 9 is supplied to the entire surface of one side of the metal strip 6 of tm.
The wire rods 8 were made by coating the wires in various thicknesses.

In the above, the material of the metal strip 6 was varied, and the deposition thickness of the raw material oxide layer 9 was varied depending on the exit size of the nozzle 5, the distance between the metal strip 6 and the nozzle 5, and the running speed of the metal strip 6. .

Comparative Example 1 The same raw material oxide used in Example 1 was used with an outer diameter of 8 mm and an inner diameter of 6 W.
This was filled into a PT pipe and cold-rolled into a ribbon shape to form a wire rod.

Each wire rod thus obtained was heated to 900°C in an oxygen stream.
The critical temperature (T, ), J, and bending workability of each of the oxide superconducting wires thus obtained were measured.The results showed the adhesion thickness of the raw oxide layer, The relative density and manufacturing conditions are also shown in Table 1.

As is clear from Table 1, the products produced using the method of the present invention (1 to 7) have higher relative densities than the products produced using the comparative method (8, 9), and Tc, J
It has excellent superconducting properties such as c and also good bending workability.

Among the comparison method products, No. 8 had a low preheating temperature of the metal strip, so the adhesion between the metal strip and the raw material oxide layer was reduced.
Further, in No. 9, since the oxide was used in the form of powder, the relative density was low and the superconducting properties of Tc and Jc were deteriorated, and furthermore, the oxide superconductor layer was thick, so the bending workability was also poor.

In this example, since the raw material oxide melt was supplied while the metal strip 6 was stretched between the guide rolls 3 and 3', the distance between the nozzle and the metal strip was kept constant from beginning to end, and the coating thickness of the raw material oxide was We were able to reduce the variation in size. In addition, since the guide roll 3' on the exit side was cooled by passing water inside, the metal strip 6 was cooled by contacting this roll 3', and the cooling of the raw material oxide melt 4 was promoted, and the speed of the metal strip 6 was increased. It was done.

Although the Y-Ba-Cu-0 based superconductor has been described above, the method of the present invention can also be applied to superconductors whose main components are other alkaline earth metals, rare earth elements, copper and oxygen, and B1-5r-Ca-
Needless to say, it can also be applied to superconductors such as Cu-0 series and Tl-Ba-Ca-Cu~0 series.

[Effects] As described above, according to the method of the present invention, a thin oxide superconductor layer with high density and excellent adhesion is formed on the surface of the metal strip, resulting in an oxide superconducting wire with excellent superconducting properties and bending workability. It can be easily produced and has remarkable industrial effects.

[Brief explanation of the drawing]

Fig. 1 is an explanatory view of the main parts showing an example of an apparatus for carrying out the present invention, and Fig. 2 A is a plan view and a cross-sectional view showing an example of the deposition form of the raw material oxide layer on the surface of the metal strip, respectively. It is a diagram. l... High frequency coil, 2... Crucible, 3.3'
... Guide roll, 4... Melt of raw material oxide,
5... Nozzle, 6... Metal strip, 7... Preheater, 8... Oxide superconducting wire, 9... Raw material oxide layer. Patent Applicant Agent Patent Attorney Yu Lead Dust - Figure 1 Figure 2

Claims (1)

[Claims] It is characterized by continuously supplying and depositing a melt of raw material oxide that will become a superconductor onto the surface of a running metal strip, and then heat-treating it at a predetermined temperature in an oxygen-containing atmosphere. Method for manufacturing oxide superconducting wire.