JPH11126523A - Tape-like high temperature oxide superconductive wire material, manufacture and apparatus for manufacturing thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tape-like high temperature oxide superconductive wire material with high critical current density of high evenness by rolling while controlling an aspect ratio of the wire material and the cross-section surface area reduction ratio in manufacture of the metal-sheathed superconductive wire material. SOLUTION: A uniform an homogeneous superconductive wire material with high critical current density of high evenness is manufactured by processing a wire material having a round cross-section into a tape-like wire material by rolling with an aspect ratio of 12-23% and cross-section surface area reduction ratio of 22-37% in order to suppress uneven deformation in two different ways: one is expansion in width direction and the other is elongation in the longitudinal direction due to pressurizing: in rolling a wire material with a round cross-section produced by filling a metal pipe of such as silver or a silver alloy with precursor powders of the oxide superconductor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tape-shaped high-temperature oxide superconducting wire, and more particularly to a tape-shaped high-temperature oxide superconducting wire provided with a metal sheath having a uniform and high critical current density. The manufacturing apparatus is provided.

[0002]

2. Description of the Related Art Since high-temperature oxide superconducting wires exhibit a superconducting state at liquid nitrogen temperature, they are expected to be applied to wires for superconducting magnets, superconducting cables, and the like, and their development is being promoted. In particular, research and development have been conducted on tape-shaped high-temperature oxide superconducting wires using bismuth-based high-temperature oxide superconductors and provided with a metal sheath of silver or silver alloy, aiming for longer lengths and higher critical current densities. .

[0003] When manufacturing a tape-shaped high-temperature oxide superconducting wire provided with a metal sheath, a metal pipe such as silver or a silver alloy is filled with a precursor powder of an oxide superconductor, which is reduced in diameter, stretched, and processed. Powder-in-tube that bundles multiple cut pieces, fills metal pipes such as silver or silver alloy, reduces diameter, and stretches them
The properties such as critical current density are improved by finally processing a round cross-section wire obtained by a method or the like into a tape shape by roll rolling.

[0004]

However, when rolling a round cross-section wire to produce a tape-shaped high-temperature superconducting oxide wire, the wire has two types of width: widthwise expansion and longitudinal elongation accompanying rolling. In the former, the arrangement of the superconducting filaments is disturbed, and in the latter, the causes of non-uniformity such as the superconductor crystals becoming dense and sparse in the longitudinal direction and the bondability of the crystals are reduced, and as a result, the critical current density is reduced. .

An object of the present invention is to provide a tape-shaped high-temperature oxide superconducting wire having a good filament arrangement, excellent crystal uniformity and excellent crystal bonding properties, and exhibiting a uniform and high critical current density. is there.

Another object of the present invention is to provide a method and an apparatus for producing a tape-shaped high-temperature oxide superconducting wire having a uniform and high critical current density under preferable rolling conditions.

[0007]

According to the present invention, the aspect ratio of the wire is 12 to 23% and the reduction in area during rolling is 22 to 3%.
By processing a round cross-section wire into a tape-shaped wire at 7%, disorder of the arrangement of superconducting filaments in the cross-section of the roll-rolled wire is suppressed, uniformity of crystal direction and bonding of crystals are excellent, and high critical current is obtained. An object of the present invention is to provide a homogeneous tape-shaped high-temperature oxide superconducting wire having a density characteristic. That is, as shown in FIG. 1, the present invention is a tape-shaped high-temperature oxide superconducting wire 3 provided with a metal sheath comprising a superconducting filament 1 made of a high-temperature oxide superconducting material and a matrix 2 made of silver or a silver alloy.

[0008] The present invention further provides a method for producing the same. That is, in this method, a metal pipe such as silver or a silver alloy is filled with a precursor powder of an oxide superconductor, the diameter of the precursor powder is reduced, stretched, cut to a fixed size, and a plurality of the bundles are bundled. Alternatively, the method includes a step of filling a silver alloy pipe, reducing the diameter, and stretching to form a round wire, and finally processing the round wire into a tape by roll rolling.

In general, when a wire having a round cross section is roll-rolled, the shape of the wire after the roll-rolling, particularly the width dimension, is as follows:
Even if a certain roll gap is maintained, the width changes due to the mechanical properties of the wire to be processed, the friction between the wire and the roll surface, and the wire tension before and after roll rolling. In order to suppress the non-uniform deformation of the two types of deformation, it is important to simultaneously control the aspect ratio of the wire and the reduction in area during rolling. The present invention has been made based on such findings.

Analysis of roll rolling conditions in the production of the above-mentioned tape-shaped high-temperature oxide superconducting wire shows that the frictional force between the roll and the wire is the largest factor, and the method of performing roll rolling after applying a lubricant. The optimum roll rolling conditions are controlled by a roll rolling method in the intermediate state between non-lubricating and fully lubricating conditions, suppressing disorder in the arrangement of superconducting filaments, providing excellent crystal orientation uniformity and crystal bonding, and high criticality. A homogeneous tape-shaped high-temperature oxide superconducting wire having current density characteristics can be obtained.

More precise control of the amount of the lubricant to be applied is performed by providing a degreasing device and a lubricant applying device capable of adjusting the amount of the applied lubricant on the side where the round cross-section wire is supplied to the roll rolling mill, respectively. , The amount of lubricant applied to the wire rod is adjusted, and a roll rolling process can be used.

Further, more precise control of the lubricant application amount is as follows.
Provide a sensor to continuously measure the width of the tape-shaped wire obtained by roll rolling the round cross-section wire, or the width and thickness, calculate the area reduction rate by roll rolling with this measured value, lubricant It is possible to use a manufacturing device including a lubricant coating device for adjusting the amount of coating, and it is possible to manufacture a tape-shaped high-temperature oxide superconducting wire having a uniform and high critical current density.

[0013]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tape-shaped high-temperature oxide superconducting material provided with a metal sheath made of an oxide superconducting material and a matrix made of silver or a silver alloy, a method for producing the same, and an apparatus for producing the same. As the high-temperature oxide superconducting material, a high-temperature oxide superconducting material that promotes crystal orientation and improves crystal bonding by mechanical processing such as roll rolling is preferable, and is a high-temperature oxide superconducting material such as Bi-based or Tl-based. Can be applied.

In the present invention, the high-temperature oxide superconducting wire is prepared by mixing raw material powders in a predetermined amount and then repeating calcination and heat treatment as necessary to prepare a precursor of the oxide superconductor.
The obtained precursor powder is filled in a pipe serving as a metal sheath, processed into a fine wire, and the fine wires are bundled to form a superconducting wire having a round cross section of a multifilament filament.
The tube method is used. The high-temperature oxide superconducting wire provided with the metal sheath having a round cross section is processed into a tape-shaped high-temperature oxide superconducting wire made of filaments of the high-temperature oxide superconducting material provided with the metal sheath by roll rolling.

The high-temperature oxide superconducting wire of the present invention is composed of a composite material of a superconducting filament of a high-temperature oxide superconducting material and a matrix composed of a metal sheath. In the case of roll rolling, the matrix is processed and the superconducting filament is processed simultaneously. Is done. When a high-temperature oxide superconducting wire with a round cross section is roll-rolled, the higher the reduction in area of the wire, the higher the temperature of the high-temperature oxide superconducting material becomes. Roll rolling with a reduction in area of 22% or more can be used in order to improve superconducting properties such as current density.

On the other hand, the high temperature oxide superconducting wire of the present invention
High-temperature oxide Superconducting materials composed of superconducting filaments of a superconducting material with different mechanical strengths and a matrix composite made of a metal sheath.The mechanical strength and elongation are different from each other. Since the deformation of the superconducting material is small and the superconducting filaments in the longitudinal direction tend to be non-uniform, it is preferable to reduce the area reduction rate in order to suppress non-uniform processing. It is desirable to use a roll rolling process with a reduction in area of less than 37% because the superconducting properties are not impaired while suppressing the non-uniformity of the superconducting filament in the longitudinal direction. The reduction in area is in the range of 22 to 37%. It is desirable to choose.

Regarding the aspect ratio of a tape wire when roll-rolling from a round cross-section wire to a tape-shaped wire, the higher the aspect ratio, the higher the temperature of the high-temperature oxide superconducting material. In view of the improvement in superconducting properties such as critical current density, roll rolling with a surface reduction of 12% or more can be used.

On the other hand, when the aspect ratio of the wire is large,
Compared to the deformation of the matrix, the deformation of the oxide superconducting material is small and tends to be non-uniform, and the arrangement of superconducting filaments in the width direction is disturbed, and the superconducting properties are impaired. The aspect ratio is desirably 23% or less, and a roll rolling process with an aspect ratio of 12 to 23% can be used.

As described above, when manufacturing a tape-shaped high-temperature oxide superconducting wire provided with a metal sheath by roll rolling, non-uniformity in the superconducting filament in the longitudinal direction and disorder in the arrangement in the width direction are reduced. In order to improve the superconductivity and obtain a uniform high-temperature superconducting wire, it is necessary to control both the reduction ratio of the roll rolling and the aspect ratio of the wire.
% And a wire rod having an aspect ratio of 12 to 23%, a tape-shaped high-temperature oxide superconducting wire having a high critical current density can be obtained.

When a round cross-section wire of a high-temperature oxide superconducting wire provided with a metal sheath is roll-rolled and processed into a tape-shaped wire, the width of the round cross-section wire and the elongation in the longitudinal direction are reduced with the roll pressure. Even if two types of deformation occur and maintain a constant roll gap, the mechanical properties of the wire to be processed,
Due to the friction between the wire and the roll surface, the wire tension before and after the roll rolling, and the like, the width of the tape-shaped wire and the state of deformation in the longitudinal direction change. Analysis of the roll rolling conditions of the high-temperature oxide superconducting wire showed that the frictional force between the roll and the wire was the largest factor for the deformation behavior of the wire with a round cross section. By adjusting the amount of lubricant applied by the coating device and performing rolling in the intermediate state between non-lubricated and fully lubricated, the width and longitudinal deformation state of the wire rod is controlled, and the reduction ratio of roll rolling and tape By controlling the aspect ratio of the filamentous wire, a tape-shaped high-temperature oxide superconducting wire having excellent superconducting characteristics such as critical current density characteristics can be produced.

As the lubricant, liquid lubricants such as rapeseed oil, mineral oil, alcohols such as ethanol, and powdered lubricants such as graphite, molybdenum oxide, and metal soap can be used. Among these lubricants, liquid lubricants can be used. Lubricant is easy to adjust the coating amount and uniform application, is suitable for uniform processing of the wire, and when using soft silver or silver alloy as the metal sheath, roll-rolling the surface of the tape strip wire This has a favorable effect, for example, such that processing scratches due to the above are hardly left.

When a wire having a round cross section is bitten into a rolling roll during roll rolling, a compressive force is gradually applied to the wire as it enters the roll from the roll entrance, and plastic deformation occurs in the longitudinal direction and width of the wire. In the case of roll rolling, as the compression force increases, the ratio of the deformation in the width direction to the deformation in the longitudinal direction tends to increase. For this reason, when the rolling amount of the roll is increased, when the amount of deformation in the width direction increases, the amount of lubricant is increased to reduce the frictional force in order to reduce the compressive force. Can be adjusted. On the other hand, when the amount of reduction is small, the amount of deformation in the width direction tends to be small, and the compression force is adjusted by reducing the amount of the lubricant so as to increase the frictional force, and the length and width of the wire are reduced. The deformation behavior can be adjusted.

In the present invention, as shown in FIG. 2, a degreasing device 6 and a lubricant applying device 7 capable of adjusting the amount of applied lubricant are provided on the side where the round cross-section wire 4 is supplied to the roll rolling mill 5, respectively. Can be mounted in order of direction. Preliminary cleaning of the surface of the round wire with a degreasing device makes it possible to uniformly and stably control the amount of lubricant applied to the round wire in the next lubricant application process. This is a preferable method as a method for producing a long high-temperature oxide superconducting wire.

Further, according to the present invention, a dimension measuring sensor 8 for continuously measuring the width or width and thickness of a tape-shaped wire obtained by roll-rolling a round-section wire 4 is shown in FIG.
As shown in the figure, the reduced area ratio and the aspect ratio are calculated based on the measured values, and the amount of the lubricant applied can be adjusted by the application amount adjusting means provided in the lubricant application device. The width of the tape-shaped wire obtained by the sensor, or the reduction ratio of the roll-rolling process and the aspect ratio of the tape-shaped wire are calculated from the measured values of the width and the thickness, and the tape-shaped tape with excellent superconducting characteristics such as critical current density characteristics By controlling the amount of lubricant adhering to the round cross-section wire by feedback control so as to converge to the optimum conditions of the area reduction ratio of the roll rolling process and the aspect ratio of the tape-shaped wire that can obtain the high-temperature oxide superconducting wire of uniform This is a preferable method as a method for producing a uniform, long, high-performance, high-temperature oxide superconducting wire because it can be stably controlled and can perform stable roll rolling of a long wire.

[0025]

【Example】

(Example _{1) Bi 2 O 3, PbO} , SrCO 3, CaC
O ₃ and CuO powder were converted to Bi: Pb: Sr: Ca: C
It mixed so that it might become the composition ratio of u = 1.8: 0.4: 2: 2: 3. The obtained mixture was subjected to heat treatment for temporary sintering and pulverization three times to obtain a powder as a precursor of the oxide superconductor. The obtained powder was filled in a silver pipe having an outer diameter of 15 mm and an inner diameter of 13 mm. The silver pipe filled with the powder was drawn to 1.02 mmφ. Further, 61 such wires were bundled, filled in a silver pipe, and reduced in diameter and drawn to produce a multi-core, high-temperature oxide superconducting wire having a round cross section by a powder-in-tube method. Further, the constant temperature oxide superconducting wire having the round cross section was roll-rolled to prepare a tape-shaped wire. The aspect ratio Rasp of the wire, which is the ratio of the width to the thickness of the tape-shaped wire, is 9 to 27, and the area reduction rate R
(Red) = (1- (cross-sectional area after rolling) / (cross-sectional area before rolling)) was roll-rolled in the range of 0.18 to 0.59 to prepare a single-length 100 m-class tape wire.

As a superconducting property of the obtained tape-shaped wire, a critical current density Jc in liquid nitrogen was measured by a four-terminal method. The critical current density standardized by the measured maximum critical current density Jc (max) is defined as Jc / Jc (max), and the relationship between the area reduction R (red), the aspect ratio R (asp), and Jc / Jc (max) is defined. As shown in FIG. The critical current density varies depending on the roll rolling processing conditions, and Jc / Jc
The measurement data of (max) ≧ 0.9 is represented by ○, Jc / Jc (m
ax) The measurement data of <0.9 is indicated by x. The critical current density is R (asp) = 12-23 and R (red) = 2
At 0 to 40%, Jc / Jc (max) ≧ 0.9, and a tape-shaped wire having uniform characteristics was obtained. On the other hand, as a comparative example, the critical current density is reduced under conditions such that the aspect ratio of the tape wire is too small or too large, or the area reduction rate of the roll rolling is too large or too small. The current density fluctuated greatly.

(Embodiment 2) Bi as in Embodiment 1
The powders of ₂ O ₃ , PbO, SrCO ₃ , CaCO ₃ and CuO were mixed, and the obtained mixture was repeatedly subjected to temporary sintering and pulverization, and the obtained precursor powder of the oxide superconductor was filled in a silver pipe. A silver pipe filled with powder is set to 1.02 mm
The wire was drawn to φ, 61 wires were bundled, filled in a silver pipe, and a wire having a round cross section was produced by diameter reduction and wire drawing. In addition, when the round cross-section wire is roll-rolled, ethanol is used as a lubricant, and the amount of lubricant attached to the surface of the wire is adjusted in advance by a lubricant coating device. A wire was produced.

Similarly, when the critical current density of this tape wire in liquid nitrogen was measured, the normalized critical current density Jc / Jc (max) was found to have an aspect ratio R (as
p) = 12 to 23 and area reduction R (red) = 20 to 40
%, Jc / Jc (max) ≧ 0.9, and after adjusting the amount of lubricant adhering to the surface of the round cross-section wire with an oil application device in advance, by performing roll rolling,
Even with a long tape wire having a single length of 200 m, a uniform long tape wire having excellent characteristics could be obtained.

Further, a degreasing device and a lubricant applying device capable of adjusting the amount of lubricant are mounted on the side where the above-mentioned round cross-section wire is supplied to the roll mill in the order of the progress of the wire, respectively. The critical current density of the tape-shaped wire rod prepared by adjusting the amount of the agent and roll-rolling was measured in the same manner. Aspect ratio R (asp) = 12 to
The critical current density normalized at 23 and the reduction ratio R (red) = 20 to 40% is Jc / Jc (max) ≧ 0.
As a result, a tape wire having a uniform length of 95 and excellent characteristics was obtained.

Example 3 As in Examples 1 and 2,
The powders of Bi ₂ O ₃ , PbO, SrCO ₃ , CaCO ₃ and CuO were mixed, and the resulting mixture was repeatedly pre-sintered and pulverized, and the obtained precursor powder of the oxide superconductor was filled in a silver pipe. . The silver pipe filled with the powder was
It was drawn to a diameter of mmφ, and 61 such wires were bundled and filled in a silver pipe, and a wire with a circular cross section was produced by reducing the diameter and drawing.
Furthermore, when this round wire is roll-rolled, a sensor for continuously measuring the width or width and thickness of the tape-shaped wire after the roll-rolling of the round cross-section wire is provided, and the measured value is used to apply a lubricant. The tape wire was manufactured while adjusting the lubricant amount of the apparatus, thereby manufacturing a single-length 1000 m class tape wire.

Similarly, when the critical current density of this tape wire was measured in liquid nitrogen, the critical current density was R (a
sp) = 12 to 23 and R (red) = 20 to 40%, Jc / Jc (max) ≧ 0.9, and the width, or width and thickness of the tape-shaped wire after roll-rolling the round cross-section wire By providing a sensor that continuously measures the length of the tape and making the tape wire while adjusting the lubricating oil amount of the oil applicator based on the measured value, a uniform length with excellent characteristics even for a single-length 1000m class tape wire A long tape wire was obtained.

[0032]

As described above, in the production method according to the present invention, when a round cross-section wire is roll-rolled, the tape wire has an aspect ratio of 12 to 23% and a reduction in rolling area of 22 to 37%. When rolling a round cross-section wire into a tape-shaped wire by roll rolling, it reduces homogeneity of superconducting filament arrangement, improves crystal orientation, and is excellent in crystal bonding, and has a high critical current density characteristic as superconductivity. A high temperature oxide superconducting wire can be obtained.

Further, in order to achieve a preferable roll rolling process, a method of controlling the amount of lubricant on the surface of the wire rod, or a width or width of a rolled tape-shaped wire rod in order to more precisely control lubricant application. By providing a sensor that continuously measures the thickness, calculating the area reduction rate with this measured value and adjusting the lubricant amount of the lubricant application device,
A tape-shaped high-temperature oxide superconducting wire having a uniform and high critical current density can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view in which a part of a tape-shaped metal sheath high-temperature oxide superconducting wire is cut away.

FIG. 2 is a view schematically showing an apparatus for producing a tape-shaped metal sheath high-temperature oxide superconducting wire.

FIG. 3 is a diagram showing a relationship between a standardized critical current density, a wire rod asmect ratio, and a wire area reduction rate.

[Explanation of symbols]

 1: superconducting filament 2: matrix 3: tape-shaped metal sheath high-temperature oxide superconducting wire 4: round cross-section wire 5: roll rolling machine 6: degreasing device 7: lubricant applying device 8: dimension measuring sensor 9: wire supplying device 10: Wire winding device

Claims (5)

[Claims] 1. A tape-shaped high-temperature oxidizing method wherein a round cross-section wire of a metal sheath high-temperature oxide superconducting wire is roll-rolled at a reduction ratio of 22 to 27% and an aspect ratio of the wire is 12 to 23%. Superconducting wire. 2. A round wire having a metal-sheathed high-temperature oxide superconducting wire is roll-rolled into a tape-shaped wire having an aspect ratio of 12 to 23% and a reduction in area of 22 to 37% during rolling. A method for producing a tape-like high-temperature oxide superconducting wire, comprising: 3. The method for producing a tape-like high-temperature oxide superconducting wire according to claim 2, wherein a lubricant is applied to the surface of the wire having a round cross section in advance and then roll-rolled. 4. A roll rolling mill, wherein a degreasing device and a lubricant applying device are respectively mounted on a side where the round cross-section wire is supplied to the roll rolling mill in the traveling direction of the wire. 1. An apparatus for producing a tape-shaped high-temperature oxide superconducting wire, comprising: an application amount adjusting means for adjusting an application amount of a lubricant adhered to a tape. 5. A sensor for continuously measuring the width or width and thickness of the tape-shaped wire after the rolled wire having the round cross section is provided, and the measured value is used as a lubricant application amount by a lubricant application device. 5. The method according to claim 4, wherein
3. The apparatus for producing a tape-shaped high-temperature oxide superconducting wire according to claim 1.