JPH02239521A - Manufacture of bi oxide superconducting wire having high critical current density - Google Patents

Abstract

PURPOSE:To continuously and simply manufacture a Bi type oxide superconducting wire of excellent critical current density by rolling a metal sheath BiSrCaCuO oxide powder filler wire material by means of a heating roll, the wire material obtained by charging BiSrCaCuO oxide powder in a metal pipe and then performing drawing treatment. CONSTITUTION:Mixed powders consisting of Bi2o3PbO, SrCO3, CaCO3 and CuO are each burned in atmosphere and then the Bi oxide thus obtained by burning is crushed. The Bi oxide powder obtained is put in an Ag pipe and both ends of the Ag complex pipe are sealed by press working, and thereafter the powder is swaged to reduce the diameter of the wire, and then a channeled roll treatment is applied, thereby fabricating an Ag sheath Bi oxide powder filler wire. The wire 3 is rolled by a heating roll 1. The heating roll 1 is held at temperatures from 800 to 850 deg.C by a sheath heater 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a B'-based oxide superconducting wire having a high critical current density.

[Conventional technology]

Currently, BLSrCa is a Bi-based oxide superconducting wire.
CuO-based oxide superconducting wire and BiPbSrCaCu
O-based oxide superconducting wires are known. The above B i S
The rcacuo-based oxide superconducting wire is BiSrCaC
A silver pipe is filled with uO-based oxide powder and subjected to wire drawing processes such as swaging, groove roll processing, and die processing.
The Ag-sheathed BiSrCaCuO-based oxide powder-filled wire was further heated to a temperature of 750 to 870°C, lO to
It was manufactured by sintering under conditions of holding for 200 hours. The manufacturing method of the BiPbSrcacuO-based oxide superconducting wire is also the same as the manufacturing method of the BiSrCaCuO-based oxide superconducting wire, except that a BiPbSrCaCuO-based oxide powder in which part of 81 of the BiSrcacuO-based oxide is replaced with PB is used. It can be manufactured as follows. In the Bl-based oxide superconducting wire manufactured in this way, since the crystal grains of the 81-based oxide powder are generally scale-shaped, when the wire drawing process is performed, the C plane is oriented in the longitudinal direction of the wire. It is also known that they tend to align in parallel.

[Three problems to be solved by the invention] The above BiSrCaCuO-based oxide has a critical temperature of 105
'K phase (hereinafter referred to as f%Te phase) and critical temperature 28
Two phases, 01 phase (hereinafter referred to as low Tc phase), coexist, and a part of 81 of the BiSrCaCuO-based oxide is
It has become possible to stably obtain high TejiJ by substituting with b.

However, the Bl-based oxide superconducting wire has an extremely low critical current density Jc compared to the known Y-based oxide superconducting wire. The appearance of a Bl-based oxide superconducting wire having a density Jc has been desired.

[Means for Solving the Problem] Therefore, the present inventors have conducted research to develop a B1-based oxide superconducting wire having an even better critical current density Je. , critical current density Jc is achieved by rolling with heated rolls maintained at a temperature range (800 to 850°C) where Bl-based oxide easily causes grain growth.
They obtained the knowledge that it is possible to significantly improve the

This invention was made based on this knowledge, and the present invention was made based on this knowledge, and it is possible to use a conventional metal sheath B1-based oxide powder-filled Aijl material.
This method is characterized by a method for producing a BI-based oxide superconducting wire, which is rolled using heated rolls maintained at a temperature of 800 to 850°C.

As mentioned above, the Bl-based oxide powder of the metal sheathed B1-based oxide powder-filled wire obtained by filling a metal pipe with Bfi-based oxide powder and subjecting it to wire drawing has a C-plane in the longitudinal direction of the wire to some extent. However, when this is batch-sintered as in the past, the crystals of the Bi-based oxide powder grow in the same direction and lose their orientation. However, when the metal sheath B1-based oxide powder-filled wire rod is rolled with a heated roll maintained at a temperature of 800-850°C as in the present invention, the BI-based oxide powder is densely packed and at the same time It is considered that the crystals of the oxide powder grow only in the longitudinal direction of the wire, and therefore the critical current density Jc is significantly improved.

The metal sheath is preferably Ag, Cu, or an alloy thereof because it is easy to process, but is not limited to these metals, and stainless steel or the like may also be used.

In addition, the metal sheath B1-based oxide powder-filled wire rod is
In addition to the Bl-based oxide powder-filled wire with a circular cross section, it may also be a ribbon-shaped wire obtained by further parallel roll rolling a Bi-based oxide powder-filled wire with a circular cross section.

When the heating temperature range of the heating roll is less than 800°C,
The bond between the particles of the BI-based oxide powder is also weak, and rolling takes too much time, which is not preferable.

On the other hand, if the temperature range of the heating roll exceeds 850°C,
Critical temperature: low T of 80'K in high Tc phase of 105'K
C phase, and even lower temperature 6 to 2 (1" K phase) appear, which is undesirable. Therefore, the temperature range of the heating roll is 800
The temperature was set at ~850°C.

Note that the metal sheath Bl-based oxide powder-filled wire rod may be rolled not only once but multiple times using the heating roll.

〔Example〕

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

As a raw material powder, Bi20 with a particle size of 10 or less is used in both cases.
3 powder, pbo powder, S r CO 3 powder, Ca
CO s powder and CuO powder are prepared, these raw material powders are blended and mixed so that the composition shown in Table 1 is obtained, and the obtained mixed powder is individually heated in the atmosphere under the conditions shown in Table 1. After firing, the Bi-based oxides obtained by the firing were pulverized to produce Bi-based oxide powders having particle sizes shown in Table 1.

These Bl-based oxide powders were prepared with an inner diameter of 5+n, a wall thickness of 20,
5. Length: 200+* Fill the Ag pipe with Bl
A Agffl joint pipe filled with oxide powder was prepared, and this A
g After sealing both ends of the composite pipe by press working,
The diameter is reduced by swaging and then grooved to reduce the diameter to l. 7 ■ 1. Ag sheath thickness: 0
An Ag-sheathed B1-based oxide powder-filled iJli wire rod having dimensions of , 2 mm was fabricated.

The Ag-sheathed B1-based oxide powder-filled wire rod produced in this way was rolled in the atmosphere with a heating roll 1 as shown in FIG. 1, and the rolling conditions are shown in Table 1. The heating roll 1 has a sheathed heater 2 provided inside the drum, and the sheathed heater 2 is connected to conductive sliding members 4 provided on both sides of the heating roll 1. Electric power is supplied from the slider 5 to the sheathed heater 2 through the conductive sliding material 4, and by heating the sheathed heater 2, the temperature of the heating roll 1 is raised to 800°C.
The temperature is maintained at ~850°C.

A B-
The critical current density Jc of the 1-type oxide superconducting wire was measured in liquid nitrogen, and the measurement results are shown in Table 1. 'm
Values marked with a chestnut in Table 1 indicate values outside the conditions of the present invention.

From the results in Table 1, it can be seen that the Bl-based oxide superconducting wire manufactured according to the conditions of the present invention has an excellent critical current density.

〔Effect of the invention〕

According to the present invention, a Bl-based oxide superconducting wire having an excellent critical current density can be easily and continuously manufactured, so that extremely excellent results can be obtained in practice.

Claims (2)

[Claims] (1) Metal sheath BiSr obtained by filling a metal pipe with BiSrCaCuO-based oxide powder and subjecting it to wire drawing.
The CaCuO-based oxide powder-filled wire rod was heated at a temperature of 800 to 8
A method for producing a Bi-based oxide superconducting wire having a high critical current density, the method comprising rolling with heated rolls maintained at 50°C. (2) Metal sheath Bi obtained by filling a metal pipe with BiPbSrCaCuO-based oxide powder and subjecting it to wire drawing.
A PbSrCaCuO-based oxide powder-filled wire rod was heated at a temperature of 8
1. A method for producing a Bi-based oxide superconducting wire having a high critical current density, the method comprising rolling the wire using heated rolls maintained at 00 to 850°C.