JPH04184820A - Manufacture of tape-shaped oxide superconductor - Google Patents

Abstract

PURPOSE:To efficiently produce an excellent tape-shaped oxide superconductor by a coat metal layer on a superconductor layer by the use of molten metal having a lower melting point than the melting starting temperature of an oxide superconductor constituting an oxide superconducting layer. CONSTITUTION:A metal sheet-shaped body 10 is made to run in one direction at a constant speed, then a specified amount of raw material for oxide superconductor 14 is discharged on one surface of the sheet-shaped body 10 from a dispenser 12 arranged at a higher position than the position where the body 10 travels, and it is rolled by a roller 16 positioned at the rear stage of the dispenser 12, whereby a raw material-coated layer for oxide superconductor with a specified thickness can be prepared. Namely, in forming such metal layer on the oxide superconductor layer, a sheet-shaped member 22 is travelled in a fixed direction at a constant speed, then a molten metal 28 heated 26 is supplied by a specified amount from a nozzle 24 positioned at a higher position than the position where the sheet-shaped member 22 onto the oxide conductor layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a tape-shaped oxide superconductor.

[Prior art] Oxide superconductors such as Y-Ba-Cu-0 series, B1-8r-Ca-Cu-0 series, and TI-Ba-Ca-Cu-0 series have Tc (critical temperature) of liquid. Because it exceeds the nitrogen temperature, it is expected to be used in a variety of applications. In particular, molding such oxide superconductors into various shapes is being considered.

For example, in order to mold an oxide superconductor into a bulk shape, a raw material for the oxide superconductor is first compressed into a desired shape and size, and then the resulting molded body is heat-treated.

In addition, as a method of forming an oxide superconductor into a linear body,
Conventionally, a metal sheath method has been used. In this method, raw materials for the oxide superconductor are filled into a metal pipe as a sheath material to create a composite billet, and then this composite billet is finished into the desired shape and dimensions by plastic processing, and then the oxide superconductor is An oxide superconducting wire is obtained by subjecting a raw material for body use to a heat treatment to react with an oxide superconductor.

Here, the raw material for the oxide superconductor is prepared, for example, as follows. First, primary raw material powders such as oxides, carbonates, etc. of the constituent elements of the oxide superconductor are blended to give a desired oxide superconductor composition, and mixed thoroughly.

Next, this mixed powder is calcined to obtain a calcined body, or
Alternatively, this mixed powder is heated and melted, and then rapidly cooled to obtain a lump. Next, the obtained pre-calcined body or block is pulverized to obtain a raw material for an oxide superconductor.

As the plastic working, extrusion, rolling, drawing, swaging, etc. are used depending on the shape of the linear object or tape-like object. By this plastic working, it is possible to easily manufacture a material having a circular, elliptical, rectangular, or tape-shaped cross section.

In addition, using this method, multiple wire bodies are bundled together, a multicore wire with a metal sheath on the outside, and multiple metal pipes with different diameters are arranged concentrically, and oxide superconducting is conducted in the gaps between the pipes. Prototype production of concentric cylindrical bodies formed by filling a solid body, or multilayer linear bodies in which metal layers and oxide superconductor layers are spirally arranged in cross section, is also being considered.

In this method, the heat treatment temperature for forming an oxide superconductor is determined by the type of raw material for the oxide superconductor used. For example, in the case of a Y-based oxide superconductor raw material, the temperature is 900 to 950°C, and in the case of a Bi-based oxide superconductor raw material, it is 850 to 900°C.

Metal materials used for the sheath material include Ag, Ag alloy, and Cu, which have excellent thermal conductivity and electrical conductivity.

A Cu alloy or the like is used. Among these, AgSAg alloys, which have excellent oxygen permeability, are particularly preferred.

When manufacturing a tape-shaped oxide superconductor using such a metal sheath method, a composite billet is created by filling a metal pipe with the oxide superconductor raw material, and the composite billet is subjected to plasticity mainly through rolling. Heat treatment is performed after processing.

[Problems to be Solved by the Invention] However, when the composite linear body obtained as described above is heat-treated under predetermined conditions to form an oxide superconductor, in the heat treatment process Gas is generated from the raw material, and a gap 34 is created between the sheath material 30 and the oxide superconductor 32 as shown in FIG. 3, resulting in deformation of the sheath material 30. As a result, the flexibility of the tape-shaped oxide superconducting conductor decreases, making it extremely difficult to handle.

In addition, as a tape-shaped oxide superconducting conductor, the appearance is Jc
There is a problem that the (critical current density) value decreases.

The present invention has been made in view of these points, and provides a tape-shaped oxide superconductor that can efficiently produce a tape-shaped oxide superconductor that can exhibit excellent superconducting properties while preventing the generation of voids. The purpose of the present invention is to provide a method for manufacturing a superconducting conductor.

[Means for Solving the Problems] The present invention involves coating a metal sheet with a raw material for an oxide superconductor, subjecting it to a predetermined heat treatment to form an oxide superconductor layer, and then coating the metal sheet with a raw material for an oxide superconductor. A tape-shaped oxidation method comprising forming a coating metal layer on the superconductor layer using a melt of a metal having a melting point lower than the melting start temperature of the oxide superconductor constituting the oxide superconductor layer. A method for manufacturing a superconducting conductor is provided.

Here, as a method for coating a metal sheet with a raw material for an oxide superconductor, for example, as shown in FIG.
A metal sheet-like body 10 is made to travel in one direction at a constant speed, and a certain amount is applied onto one surface of the sheet-like body 10 from a dispenser 12 installed at a higher position than the position where the sheet-like body 10 is traveling. The raw material 14 for oxide superconductor is discharged by the roller 16 installed at the rear stage of the dispenser 12.
A method for obtaining a coating layer of a raw material for an oxide superconductor having a predetermined thickness by rolling the oxide superconductor at a predetermined thickness can be mentioned. Furthermore, in this method, instead of discharging and supplying the oxide superconductor raw material 14 from the dispenser 12, a melt of the oxide superconductor raw material may be discharged from the dispenser 12 and supplied. Alternatively, the oxide superconductor raw material coating layer may be formed by applying a paste obtained by sufficiently kneading the oxide superconductor raw material and a binder onto the sheet-like body.

As the metal used for the sheet-like body, a metal having poor reactivity with the oxide superconductor is used.

Such metals include Ag SA u s P t ,
Alternatively, alloys thereof are preferred.

The temperature of the heat treatment for converting the oxide superconductor raw material coated on one side of the sheet-like body into an oxide superconductor and simultaneously removing the gas generated when the oxide superconductor raw material transforms into an oxide superconductor is For example, in the case of Y-based raw material for oxide superconductor, the temperature is 900 to 950°C, and in the case of Bi-based raw material for oxide superconductor, it is 850 to 900°C. In addition, when using a paste obtained by sufficiently kneading the raw material for an oxide superconductor and a binder, it is preferable to perform a binder removal treatment in the heat treatment step.

It is preferable that the sheet-shaped body provided with the oxide superconductor layer by running is wound up within an allowable bending range that does not adversely affect the oxide superconductor layer.

As a method for forming a metal layer on an oxide superconductor layer,
For example, as shown in FIG. 2, a sheet-like body 22 provided with an oxide superconductor layer 20 is run in one direction at a constant speed,
Heating means 26 such as a heater is supplied in advance from a nozzle 24 installed at a higher position than the position where the sheet-like body 22 travels.
By supplying a constant amount of the metal melt 28 heated and melted onto the oxide superconductor layer, a predetermined thickness is obtained. A method for obtaining a gold horse layer is mentioned.

In this case, in order to prevent the oxide superconductor from melting due to the temperature of the metal melt 28 when the metal melt 28 is supplied onto the oxide superconductor layer 20, the temperature is lower than the temperature at which the oxide' superconductor starts melting. It is also necessary to choose a metal that has a high melting point. The temperature at which an oxide superconductor begins to melt is
Although it differs depending on the type of oxide superconductor, the temperature is, for example, 840°C in the case of a Bi-based oxide superconductor, and 950°C in the case of a Y-based oxide superconductor. Further, the metal used as the metal melt 28 needs to be selected from a metal that has poor reactivity with the oxide superconductor. However, by supplying the metal melt 28 onto the oxide superconductor layer 20 and then rapidly cooling it,
Reaction between the metal in the metal melt 28 and the oxide superconductor can be prevented.

As such a metal, an alloy or the like is used in which Ag or Au5Pt is used as a base metal and other metals are added to lower the melting point. The metals added include Pb, Sn
S In5SbSBtq, alloys thereof, and the like can be used. Further, when adopting a method of supplying the metal melt 28 onto the oxide superconductor layer 20 and then rapidly cooling it,
A1 alloys such as A1-Ag and AI-8iSAM-Cu alloys can be used as the metal of the metal melt.

[Function] According to the method for manufacturing a tape-shaped oxide superconductor of the present invention, an oxide superconductor layer is first formed on a metal sheet, and then a coating metal layer is formed on the superconductor layer. is formed.

Since the obtained oxide superconductor layer is in contact with the outside world, gas generated from the oxide superconductor raw material during heat treatment to make the oxide superconductor raw material into an oxide superconductor is sufficiently released to the outside world. can do.

Therefore, the formation of voids due to gas generation can be prevented, and as a result, an oxide superconducting conductor without deformation can be manufactured.

C Example Examples of the present invention will be specifically described below.

□Example 1 A sheet material 10 having a width of 0.5 mm was placed in the apparatus shown in FIG.
, an Ag sheet with a thickness of 0.1 mm was set. In the dispenser 12, a predetermined amount of raw material powder is mixed,
The pre-fired powder of Bi25rz CaCu20x was prepared by calcining this and pulverizing the calcined body.
It was caulked and loaded. A sheet made of Ag is run, and a fixed amount of calcined powder is discharged from the dispenser 12 onto the sheet made of Ag, and the powder is rolled to a thickness of 0.15 μl by a roller 16 placed after the dispenser 12. A composite sheet was prepared. Next, this composite sheet was heated at 850°C.
The calcined powder was heat-treated for 50 hours to form a Bi-based oxide superconductor.

At this time, gas generated when the calcined powder becomes an oxide superconductor was sufficiently removed. Furthermore, this composite sheet was wound around a bobbin having an outer diameter of 1 m.

Next, the obtained composite sheet was set in the apparatus shown in FIG. The nozzle 24 is loaded with Ag-Pb alloy,
It was heated to a molten state using a heater. The composite sheet is run, and Ag-Pb is applied from the nozzle 24 onto the composite sheet.
A metal layer having a thickness of 0.25 m was formed by supplying the melt. In this way, the tape-shaped Bi-based oxide superconducting conductor of Example 1 was produced.

The obtained tape-shaped Bi-based oxide superconducting conductor of Example 1 was examined for Jc (critical current density) and the presence or absence of deformation of the sheath material. The results are shown in Table 1 below. In addition, J
c was measured at liquid nitrogen temperature and zero magnetic field. Also,
The presence or absence of deformation of the superconducting conductor was determined visually.

Examples 2 to 8, Comparative Example 1 The tapes of Examples 2 to 8 and Comparative Example 1 were prepared in the same manner as in Example 1, except that each coating metal shown in Table 1 was used instead of Ag-Pb as the coating metal. A Bi-based oxide superconductor was fabricated.

Jc of the obtained tape-shaped oxide superconducting conductors of Examples 2 to 8 and Comparative Example 1 and presence or absence of deformation of the sheath material were examined in the same manner as in Example 1. The results are also listed in Table 1 below.

Comparative Example 2 A composite billet was prepared by filling the pre-sintered powder of Bi25r2CaCu20x used in Example 1 into an Ag vibrator having an outer diameter of 10 fins and an inner diameter of 8 m.phi. The obtained composite billet was subjected to groove roll rolling and flat roll rolling to produce a composite tape wire having a width of 1.0 mm and a thickness of 0.4 fin. The obtained composite tape wire was heated at 850°C and 50°C in the atmosphere.
A tape-shaped Bi-based oxide superconducting conductor of Comparative Example 2 was obtained by performing heat treatment for a period of time.

The Jc of the obtained tape-shaped Bi-based oxide superconducting conductor of Comparative Example 2 and the presence or absence of deformation of the sheath material were examined in the same manner as in Example 1. The results are also listed in Table 1 below.

Table 1 As is clear from Table 1, the tape-shaped Bi-based oxide superconducting conductors (Examples 1 to 8) obtained by the method of the present invention all exhibited excellent superconducting properties, and moreover, There was no deformation in the material. On the other hand, the tape-shaped Bi-based oxide superconductor (Comparative Example 1) obtained using a coating metal having a melting point higher than the melting start temperature (840°C) of the raw material for Bi-based oxide superconductor has a Jc value of It is low and light. Further, the tape-shaped Bi-based oxide superconductor (Comparative Example 2) obtained by the conventional method had a low Jc value and had deformation in the sheath material.

[Effects of the Invention] As explained above, the method for manufacturing a tape-shaped oxide superconducting conductor of the present invention efficiently produces a tape-shaped oxide superconducting conductor that can exhibit excellent superconducting properties while preventing the generation of voids. can be manufactured. The tape-shaped oxide superconductor thus obtained can be used as a conductor for cables, magnets, current leads, etc.

[Brief explanation of the drawing]

FIGS. 1 and 2 are schematic explanatory diagrams showing one embodiment of the method according to the present invention, and FIG. 3 is an explanatory diagram showing a conventional tape-shaped oxide superconducting conductor. 10.22... Sheet-shaped body, 12... Dispenser, 14... Raw material for oxide superconductor, 16... Roller, 20... Oxide superconductor layer, 24... Nozzle, 26... Heating means, 28... Metal melt, 30...
-Sheath material, 32...Oxide superconductor, 34...Void. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] A raw material for an oxide superconductor is coated on a metal sheet, a predetermined heat treatment is performed on the material to form an oxide superconductor layer, and then the oxide superconductor constituting the oxide superconductor layer is coated. A method for manufacturing a tape-shaped oxide superconductor, comprising forming a coating metal layer on the superconductor layer using a melt of a metal having a melting point lower than a melting start temperature.