JPH0215513A - Oxide superconductive line material excellent in stability and its manufacture - Google Patents

Abstract

PURPOSE:To seek to improve electric stability by interposing Ag powder sintered body between an Ag tube and a Bi-Ca-Sr-Cu-O oxide powder sintered body. CONSTITUTION:Bi-Ca-Sr-Cu-O oxide (Bi oxide) powder is molded into a compact 3, and the compact 3 is put in the center of an Ag tube 1, and also Ag powder is charged into between the compact 3 and the Ag tube 1, whereby an Ag compound tube is made, which is processed to extend and is sintered as an Ag compound wire. The compact 3 can be obtained by making, for example, Bi oxide 3 powder into pressed powder substance through press formation, or extruding the Bi oxide 3 powder after adding binder to it so as to temporarily bake it. Hereby, racks never occur at the Bi oxide sintered body 3 after sintering treatment, and since the Ag tube 1 and the Ag powder sintered body 2 are constituted of the same Ag metal, enough electric coupling is done, and superconductive characteristics can be stabilized.

Description

Detailed Description of the Invention [Industrial Application Field] This invention provides B1-Ca-5r-Cu with excellent stability.
The present invention relates to a -0 series or Tl-Ca-Ba-Cu-0 series oxide superconducting wire and a method for producing the same.

[Conventional technology]

In recent years, B1-Ca-Sr-Cu-0-based oxides (hereinafter referred to as Bi-based oxides) and Tl-Ca-Ba-
Cu-0-based oxides (hereinafter referred to as Tl-based oxides) are extremely 1!
It was discovered that it exhibits a strange phenomenon.

The above Bi-based oxide is first prepared using B 1203 as a raw material powder.
SrCO3 powder, CaCO3 powder, SrCO3 powder and Cu
O powder is prepared, and these raw material powders are blended in a predetermined ratio.

It is produced by mixing and firing the mixed powder at a temperature in the range of 700 to 800° C. in the atmosphere for 12 hours. Furthermore, the above-mentioned Tl-based oxide uses Tl203 powder and CaCO3 powder as raw material powder.

Ba CO5 powder and CuO powder are prepared, these raw material powders are blended and mixed in a predetermined ratio, and this mixed powder is subjected to a firing treatment for 8 hours in the air at a temperature within the range of 600 to 700°C. Especially created.

The Bi-based oxide or Tl-based oxide thus created is pulverized to obtain an anti-systemic oxide powder or Tl-based oxide powder with an average particle size of 5 μm or less, and the Bi-based oxide powder or Tl-based oxide powder is Fill an Ag tube with oxide powder,
After sealing both ends of this Ag tube, wire drawing processing such as swaging processing, groove rolling processing, or die processing is performed to obtain an Ag composite wire, and the drawn Ag composite wire is placed in air or oxygen atmosphere. Then, a Bi-based oxide superconducting wire or a Tl-based oxide super-tlL4 wire was manufactured by sintering. Sintering treatment of the Bi-based oxide superconducting wire 1! The temperature is 830-880℃,
The sintering temperature of Tl-based oxide superconducting wire is 870-92
It is 0°C. Through the above-mentioned sintering process, the powder particles filled in the Ag tube are bonded at grain boundaries, making it easier for current to flow.

[Problem to be solved by the invention]

However, the Ag composite wire filled with Bi-based oxide powder or Tl-based oxide powder obtained by the above-mentioned wire drawing process was heated at a temperature of 2850 to 850° C. in air or oxygen atmosphere, respectively.
When the sintering process is performed at 80°C or 870-920°C, the Bi-based oxide powder or Tl-based oxide powder filled in the above-mentioned Ag composite wire.

Since the Ag tube does not shrink during sintering, a gap is created between the Ag tube of the outer sheath of the superconducting wire and the sintered Bi-based oxide powder sintered body or the Tl-based oxide powder sintered body, Sufficient electrical connection between the Ag tube and the oxide powder sintered body cannot be obtained, the flow of electricity from the Ag tube to the oxide powder sintered body is not stable, and the oxide powder There is a problem in that cracks occur during sintering shrinkage, making it impossible to obtain a stable oxide superconducting wire.

[Means to solve the problem]

Therefore, the inventors of the present invention conducted research to solve these problems.

It was discovered that an oxide superconducting wire in which a Ag powder sintered body is interposed between an Ag tube and an oxide powder sintered body has excellent stability with no variation in superconducting properties.

This invention was made based on this knowledge.

(1) An oxide superconducting wire in which a sintered Ag powder is interposed between an Ag tube and a sintered Bi-based oxide powder, and a method for manufacturing the same.

and (2) an oxide superconducting wire in which a sintered Ag powder is interposed between an Ag tube and a sintered Tl-based oxide powder, and a method for producing the same.

Includes items that have the following characteristics.

To manufacture the above oxide superconducting wire.

First, prepare an Ag tube, Ag powder, Bi-based oxide powder, or Tl-based oxide powder.

The above Bi-based oxide powder or Tl-based oxide powder is molded into a molded body.

The compact was inserted into the center of the Ag tube, and the Ag powder was filled between the compact and the Ag tube to create an Ag composite tube.

The above-mentioned Ag composite tube was wire-drawn to produce an Ag composite wire.

Then, the Ag composite wire is obtained by sintering the Ag composite wire.

The above molded body is Bi-based oxide powder or Tl: $,
A compact obtained by press-molding oxide powder, or
A calcined body obtained by adding a binder to an 81-based oxide powder or a Tl-based oxide powder, extrusion molding, and then calcining may be considered, but the above-mentioned molded body is not limited to these. The shape of is.

A cylindrical one with a relatively long length and a circular cross section is preferable;
The cross-sectional shape is not limited to a circle, but may be a polygon such as a quadrangle, a pentagon, a hexagon, or any other arbitrary shape.

The average particle size of the 1 g powder is preferably in the range of 1 to 200 μm, and the average particle size of the B1-based oxide powder used to mold the compact is preferably in the range of 1 to 10 μm. Good results can be obtained if the average particle size of the oxide powder is within the range of 1 to 10 μm.

By sintering the Ag composite wire.

The Ag powder, Bi-based oxide powder, and Tl-based oxide powder filled in the Ag composite wire are bonded at grain boundaries.

It becomes an oxide superconducting wire.

A schematic cross-sectional view of a nonaoxide superconducting wire obtained by this manufacturing method is shown in FIGS. 1 and 2.

In FIG. 1, 1 is an Ag tube, 2 is an Ag powder sintered body, 3 is a Bi-based oxide powder sintered body, and 4 is a gap. Since 3' in FIG. 2 is completely the same as in FIG. 1 except that 3' is a TL-based oxide powder sintered body, explanations of the other symbols in FIG. 2 will be omitted.

The oxide superconducting wire has the cross-sectional structure shown in FIGS. 1 and 2 above.

+1) Even if the 81-based oxide powder or the Tl-based oxide powder shrinks during sintering of the Ag composite wire.

The Ag powder existing on the outer periphery of these oxide powders is also sintered and shrunk at the same time, and the Bi-based oxide powder or Tl-based oxide powder is sintered and shrunk while receiving the shrinkage force of the Ag powder, and after the sintering process. No cracks occur in the Bi-based oxide sintered body 3 or the T4 oxide sintered body 3' existing inside the oxide superconducting wire.

(2) The B1-based oxide powder, the Tl-based oxide powder, and the Ag powder undergo sintering shrinkage during the sintering process of the Ag composite tube. Although a gap occurs between the Ag tube 1 and the Ag powder sintered body 2, since the Ag tube 1 and the Ag powder sintered body 2 are made of the same Ag metal, sufficient metallurgical and Electrical connections are made.

(3) At the boundary between the Bi-based oxide powder sintered body 3 or the Tl-based oxide powder sintered body 3' and the Ag powder sintered body 2, the oxide powder and Ag powder are in mixed contact with each other. The anchor effect is working and there is sufficient electrical connection.

Therefore, the superconducting properties are considered to be stable.

〔Example〕

Next, the present invention will be specifically explained based on examples.

(1) Examples 1 to 5 and Comparative Examples 1 to 5 raw material powders were Bi2O powder with an average particle size of 10μ or less;
Prepare CaCO3 powder, SrCO3 powder and CuO powder, and convert these powders into B12O3 powder: 53,4
%, CaCO3 powder: 11.5%, SrC
O5 powder: 16.9- and CuO powder 2-18.25k
(more than % by weight) and mixed, and this mixed powder was fired in the air at a temperature of 200°C for 12 hours to create a Bi-based oxide. The Bi-based oxide obtained by this firing treatment was pulverized to produce Bi-based oxide powder having an average particle size of 5 μm.

This Bi-based oxide powder was subjected to isostatic press molding.

A round rod-shaped green compact having a diameter of 180 m and a length of 180 m was molded.

On the other hand, inner diameter: SWX wall thickness = 1B x length: λg of 200U
Ag powder with a diameter of 20 μm and an average particle diameter of 20μ is prepared, and the round bar-shaped green compact is charged into the center of the Ag tube, and the Ag powder is placed between the round bar-shaped green compact and the Ag tube. A hAg composite tube was prepared by filling the tube with powder. After both ends of the Ag composite tube were sealed by press working, the Ag composite tube was wire drawn to create an Ag composite wire with an outer diameter of 2 mm.

The above Ag composite wire was heated in an oxygen atmosphere at a temperature of 850°C.
, and sintered under the conditions of holding for 15 hours to produce a Bi-based oxide superconducting wire of the present invention. B of this invention under exactly the same conditions
A total of five B1-based oxide superconducting wires were prepared, and the superconducting properties of these five B1-based oxide superconducting wires were measured, and the results are shown in Table 1 as Examples 1 to 5.

On the other hand, the above Bi-based oxide powder was mixed with the above inner diameter = 8 mm x wall thickness:
1IEllX Length: 200H Ag tube is filled to create an Ag composite tube, both ends of this Ag composite tube are sealed by press processing, and then wire drawn, and outer diameter:
A 2M Ag composite wire was created, and then this Ag1 composite wire was sintered in a m-accumulated atmosphere at a temperature of 850°C and held for 15 hours to create five conventional B1-based oxide superconducting wires. . The conductive properties of these five conventional oxide superconducting wires were measured, and the results are shown in Table 1 as Conventional Examples 1 to 5.

S1 Table Examples 6 to 10 and Comparative Examples 6 to 10 As raw material powder, all of them had T with an average particle size of 10μ weight or less
l203 powder, CaCO3 powder, BaCO3 powder, and CuO powder are prepared, and these powders are
, Powder: 35.4%, CaCO3 powder: l 5
．． 5%, BaCO3 powder 30.6% and Cu
T
The T-based oxide powder obtained by preparing and firing the T
The L-based oxide was pulverized to produce a Tl-based oxide powder having an average particle size of 5 μm.

This Tl-based oxide powder was subjected to isostatic press molding.

A round bar-shaped compacted powder body with a diameter of 180 mm and a length of 180 mm was molded.

On the other hand, an Ag tube with an inner diameter of 8 µm x a wall thickness of 1 µm x a length of 200 µm and an Ag powder with an average particle size of 220 μm were prepared, and the round bar-shaped green compact was charged into the center of the Ag tube, The Ag powder was filled between the round rod-shaped green compact and the Ag tube to create an Ag composite tube.

After sealing both ends of the above Ag composite tube by press working, the above Ag composite tube was wire drawn, and the outer diameter was 4:2t.
An Ag composite wire of m was prepared.

The above Ag composite wire was heated in an oxygen atmosphere at a temperature of 900'.
The oxide superconducting wire of the present invention was produced by sintering under the conditions of holding C for 3 hours. under exactly the same conditions.

A total of five Tl-based oxide superconducting wires were created, and these five
The superconducting properties of the Tl-based oxide superconducting wires were measured, and the results are shown in Table 2 as Examples 6 to 10.

On the other hand, the Tl-based oxide powder was
1mX length: Fill the 20011E Ag tube and
G Composite tube is created, both ends of this Ag composite tube are sealed by press processing, and then wire drawn to obtain an outer diameter of 2.
A 1 m Ag composite wire was created, and then this Ag composite wire was sintered in an oxygen atmosphere at a temperature of 900° C. for 3 hours to create five conventional Tl-based oxide superconducting wires. The superconducting properties of these five conventional Tl-based oxide superconducting wires were measured, and the results are referred to as Conventional Examples 6 to 10! @2 Shown in table.

WI2 Table [Effect of the invention] From the results in Tables 1 and 2, it is clear that the conventional 81 series and T
The A-based oxide superconducting wire has variations in the measurement results of its superconducting properties and does not exhibit stable superconducting properties, whereas the B1-based or Tl-based acid oxide superconducting wire of the present invention has almost constant superconducting properties. Since it exhibits stable superconducting properties, it is possible to provide an excellent superconducting wire that is industrially reliable.

[Brief explanation of the drawing]

74JJ1 and 2 are schematic cross-sectional views of the oxide superconducting wire of the present invention. l...Ag tube. 2...Ag powder sintered body. 3...B1-based oxide powder sintered body, 3'...Tlt oxide powder sintered body. 4... Gap.

Claims (4)

[Claims] (1) Ag tube and Bi-Ca-Sr-Cu-O system oxide (hereinafter referred to as Bi
A stable oxide superconducting wire comprising a powder sintered body (referred to as a Bi-based oxide), characterized in that an Ag powder sintered body is interposed between the Ag tube and the Bi-based oxide powder sintered body. Oxide superconducting wire with excellent properties. (2) An Ag composite tube consisting of an Ag tube, a Bi-based oxide powder compact filled in the Ag tube, and Ag powder interposed between the Ag tube and the Bi-based oxide powder compact. 2. The method according to claim 1, wherein the Ag composite tube is wire-drawn to obtain an Ag composite wire, and the Ag composite wire is then sintered in the air or an oxygen atmosphere. A manufacturing method for oxide superconducting wire. (3) Ag tube and Tl-Ca-Ba-Cu-O-based oxide (hereinafter referred to as Tl
A stable oxide superconducting wire comprising a powder sintered body (referred to as Tl-based oxide), characterized in that an Ag powder sintered body is interposed between the Ag tube and the Tl-based oxide powder sintered body. Oxide superconducting wire with excellent properties. (4) An Ag composite tube consisting of an Ag tube, a Tl-based oxide powder compact filled in the Ag tube, and Ag powder interposed between the Ag tube and the Tl-based oxide powder compact. 4. The method according to claim 3, wherein the Ag composite tube is wire-drawn to obtain an Ag composite wire, and the Ag composite wire is then sintered in the air or an oxygen atmosphere. A manufacturing method for oxide superconducting wire.