JPH07296654A - Manufacture of oxide superconductor - Google Patents

Abstract

PURPOSE:To improve plastic processability togetherwith a mechanical strength and superconductive characteristics, in manufacture of a superconductive wire rod in which a base material, such as a sheath material, is used. CONSTITUTION:A silver copper alloy added with titanium is used as a base material. Critical current density is increased in a range containing 0.05-90 atom % Cu and 0.01-0.4 atom % Ti.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a composite wire of oxide superconductor.

[0002]

2. Description of the Related Art Conventionally, various studies have been made on oxide superconductors such as Y and Bi series in order to improve superconducting properties, particularly critical current density Jc properties, and various manufacturing processes have been conducted so far. Ways are being sought.

For example, a composite processing method in which a raw material powder of an oxide is filled in a pure silver pipe and a plastic working and a sintering process is performed, or a paste-like oxide is applied on a pure silver base, dried and then heat treated. The doctor blade method is known.

Among them, the composite wire processing method is regarded as a promising method for manufacturing a Bi-based oxide superconductor wire. In this manufacturing method, a pure silver sheath is filled with a raw material oxide calcined in the air, and a thin wire having various cross-sectional shapes is obtained by plastic working. This is a method in which a thin wire is rolled into a tape shape and subjected to high-temperature sintering heat treatment to produce a superconducting wire.

However, although these conventional methods are promising for improving the critical current density Jc characteristics by using pure silver as a base material such as a sheath material, the pure silver material is generally used for its mechanical properties. Low strength. When a pure silver material is compounded with a raw material powder such as an oxide and processed, irregular deformation in the length direction called sausaging and uneven thickness in the cross section of the wire material occur, causing agglomeration and disconnection of the oxide layer. It has the drawback of being easy to do.

There is also a problem that the interface between the pure silver base material and the oxide layer is not sufficiently matched. These are the causes of variations in superconducting properties, deterioration of critical current density Jc properties, and deterioration of reliability.

The composite wire processing method, which is regarded as a promising method for manufacturing an oxide superconducting wire, also has a drawback that the silver of the sheath material is softened by the high temperature heat treatment at 800 to 900 ° C. The softened silver sheath material easily becomes plastically deformed at the time of winding the superconducting magnet at room temperature, which causes a technical problem that irreversibly deteriorates the superconducting characteristics.

In order to improve such a problem of mechanical strength, it has been attempted to add a reinforcing material in the past, but in this case, when the reinforcing material is added, the critical current density per wire is increased. There is a problem that Jc decreases. This is an obstacle to reducing the size and weight of superconducting equipment.

[0009]

The present invention has been made in view of the above circumstances, and solves the drawbacks of the conventional method for producing a superconducting wire using pure silver as a base material such as a sheath material. It is an object of the present invention to provide a method for manufacturing an oxide superconducting wire, which can improve the plastic workability as well as the mechanical strength and the superconducting property.

[0010]

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a method for producing an oxide superconducting wire for producing a composite comprising a substrate and an oxide superconducting material, wherein: Provided is a method for producing an oxide superconducting wire, which comprises using a silver-copper alloy to which titanium is added.

In the present invention, when a silver-copper alloy is used as the base material of the oxide superconducting wire, the content of copper in the alloy is preferably 0.05 to 90 atom%. Moreover, Ti can be mentioned as an element added to the silver-copper alloy base material. It is necessary to properly select the type of element to be added and the amount to be added.

0.005 to 1.0 atomic% of Ti on a silver-copper alloy base material
The addition of the above, compared with the case of using pure silver as the base material, the equivalent or more effect in the critical current characteristics is observed,
At 01 to 0.5 atom%, the critical current density Jc is 1.2 times or more (0.01 to 0.4 atom%) compared with the case of using pure silver as the base material.
In the above, the effect that the critical current density becomes more than double) is recognized.

0.01 to 0.5 atomic% of Ti on a silver-copper alloy base material
By adding, the mechanical strength and plastic workability are significantly improved in addition to the improvement of the superconducting property.

By using a silver-copper alloy to which an element such as titanium is added as a base material such as a tube material or a base material, the mechanical strength is improved, and in the case of a composite processed material, the wire material has a uniform cross-sectional shape. Become. The compatibility with the raw material powder such as an oxide that becomes an oxide superconductor is improved, and the oxide layer is uniformly deformed in the length direction and the cross section of the wire. For this reason, it is possible to prevent nodulation and disconnection of the oxide layer, which cannot be avoided in the past.

[0015]

EXAMPLES The following will describe the method for producing an oxide superconducting wire of the present invention in more detail with reference to examples.

(Example) Various Bi-based high Tc crude Ag groups and
An AgCu-based sheath tape was produced and the superconducting critical current value Ic was compared.

Powders of Bi2O3, PbO, SrCO3, CaCO3 and CuO were added to B
i: Pb: Sr: Ca: Cu = 1.8: 0.4: 2: 2.1: 3, so that the ratio is mixed, calcined at 820 ℃ for 20 hours, crushed, and then 500 ℃ in vacuum, 4
Heat treatment was performed for a time to obtain a raw material powder.

Raw material powder is 10 mm in outer diameter, 7 mm in inner diameter, and 100 mm in length
Pure Ag tube, Ag-10at% Cu-0.01at% Ti tube, Ag-10% Cu-0.03at%
Ti tube, Ag-10at% Cu-0.04at% Ti tube, Ag-10atCu-0.1at% T
The i-tube and the Ag-10at% Cu-0.5at% Ti tube were packed, and both ends were sealed with silver stoppers.

The filled tube is swaged and processed by round wire drawing to an outer diameter of 1.1 mm, and the final thickness is obtained with a flat roll.
Rolling was performed up to 0.25 mm. A sample having a length of about 200 mm was cut out from each of the obtained tapes.

Each sample was heated to a maximum temperature of 830 ° C. at a temperature rising rate of about 20 ° C./hour and then sintered for 100 hours.
Then, the tape is 0.15 mm thick at room temperature with a flat roll.
To 830 ° C. for 50 hours to obtain a wire rod sample. The results of measuring the superconducting characteristics of each wire rod sample are shown in FIGS. 1 and 2.

FIG. 1 is a correlation diagram showing a magnetic field-critical current value curve of a wire rod sample in an example of the present invention. In the figure, the reference numeral 1 is a curve of a conventional pure Ag tape of a comparative example, and 2 and 3 are Ag-10at% Cu-0.03at% Ti tape and Ag-10at% Cu-0.01 which are examples of the present invention. It is a curve of at% Ti tape. It can be seen that even if the external magnetic field changes, the critical current density Jc is about twice or more that of the comparative example.

FIG. 2 shows the correlation between the amount of Ti added to the Ag-10at% Cu alloy base sheath tape (the Cu amount is constant at 10at%) and the critical current value Ic (4.2K, 14T in the example of the present invention). ) Is shown. From the attached references: Ag-C without Ti
In the case of u alloy sheath tape, the critical current value Ic is about 25A, whereas the addition of a small amount of Ti of about 0.1at% or less significantly improves the Ic, and especially the addition of 0.03at% gives an Ic of 55A. It was The critical current density Jc at this time is about 6 × 10 ⁴ A / c
It was m ² . Further, when the Ti addition amount was increased, the critical current value Ic decreased, and when 0.5 at% was added, it became about 30A.

FIG. 3 is a correlation diagram showing the external magnetic field-susceptibility of the wire sample in the example of the present invention. The symbols in the figure are 1-pure Ag tape, 2-Ag-10at% Cu-0.03at% Ti tape, and 3-Ag-10at% Cu-0.01at% Ti tape. The larger the history curve of the magnetic susceptibility, the smaller the deterioration of the superconducting property with respect to the external magnetic field and the better the orientation of the superconducting crystal.

FIG. 4 shows the hardness of the base material of each wire rod sample. Compared with pure Ag tape, Ag-10at% Cu-0.
It can be understood that the 01at% Ti tape and the Ag-10at% Cu-0.03at% Ti tape are superior in mechanical strength because of their higher Vickers hardness.

[0025]

As described above, the mechanical strength and superconducting properties of the base material are improved by the method for producing an oxide conductive wire of the present invention.

[Brief description of drawings]

FIG. 1 is a correlation diagram showing a magnetic field-critical current value curve of a wire rod sample.

Figure 2: Ti added to Ag-10at% Cu alloy base sheath tape
It is a correlation diagram of quantity and critical current value Ic.

FIG. 3 is a correlation diagram showing an external magnetic field-susceptibility of a wire rod sample.

FIG. 4 is a chart showing the Vickers hardness of the base material of each wire rod sample.

[Explanation of symbols]

 1 Curve of pure Ag tape 2 Curve of Ag-10at% Cu-0.03at% Ti tape 3 Curve of Ag-10at% Cu-0.01at% Ti tape

Front page continuation (72) Inventor Fumiaki Matsumoto 1-2-1 Sengen, Tsukuba-shi, Ibaraki Science and Technology Agency, Institute for Materials Research (72) Inventor Hiroshi Maeda 1-2-1 Sengen, Tsukuba-shi, Ibaraki (72) Inventor Tomoyuki Yanagiya 63-30 Yuhigaoka, Hiratsuka-shi, Kanagawa Sumitomo Heavy Industries, Ltd. Hiratsuka Research Laboratory (72) Inventor Masayuki Ishizuka 63-30, Yuhigaoka, Hiratsuka-shi, Kanagawa No. Sumitomo Heavy Industries, Ltd. Hiratsuka Laboratory

Claims (1)

[Claims] 1. A method for producing an oxide superconducting wire for producing a composite comprising an oxide superconductor and a base material, wherein the base material contains 0.05 to 90 atomic% of copper and Ti is 0.01 to 0.4.
A method for producing an oxide superconductor, which is a silver-copper alloy formed by adding at%.