JP2000109320A - Metallic substrate for oxide superconductor and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a metallic substrate having a long size, homogeneity or a large area and having high mechanical strength and excellent smoothness with high productivity at a low cost by constituting the substrate of a metallic film layer having the recrystallization texture grown by contact with a superconducting film and a metallic base material having the yield strength higher than the yield strength thereof. SOLUTION: Ni and Al are alternately laminated and the metallic coating layer of Pt, Ag, etc., forming the recrystallization texture having excellent orientation controllability is formed thereon. This composite is worked as it is to an approximately long-sized tape form, flat planar form, etc. This worked body is rolled to a desired shape, such as a long-sized tape or flat plate, by subjected to the body to intermediate annealing. This molding is then annealed in an inert gaseous atmosphere, etc., and is further fired at need. As a result, the metallic substrate for flexible oxide superconductors which consists of the metallic coating layer 1 formed with the recrystallization texture grown by contact with the superconducting film and the metallic base material 3 of an intermediate metallic compound, 2, such as high-strength Ni3Al, and is preferably >=100 MPa in the yield stress value is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has excellent mechanical strength and is suitable for forming a long and homogeneous oxide superconducting wire or a large-area film device having a high critical current density and a critical current at a temperature of liquid nitrogen or higher. The present invention relates to a long or large-area metal substrate for an oxide superconductor excellent in mass productivity and cost and a method of manufacturing the same.

[0002]

_2. Description of the Related Art At present, as a material for a superconducting wire used at a liquid nitrogen temperature, YBa ₂ Cu ₃ O ₇ (hereinafter referred to as Y-12) is used.
3) or (Hg, Re) Ba ₂ Ca ₂ Cu ₃ Ox (hereinafter referred to as H
g-1223), (Hg, Re) Ba 2 Ca 1 Cu 2 Ox
(Hereinafter, Hg-1212) and the like are promising. High critical current densities (hereinafter, Jc) and critical currents (hereinafter, Ic) can be obtained in superconducting wires and film devices composed of polycrystals of these materials.
In order to obtain c), good electrical bonding at the crystal grain boundaries of the superconductor must be realized. Although there are some differences depending on the superconducting material, it is necessary to orient the superconducting crystal grains in the same direction in order to ensure good bonding at the crystal grain boundaries. In order to realize the crystal orientation of the superconductor, various orientation control substrates have been developed at present.

[0003] For example, Appl. Phys. Let
t. 60 (1992) pp769, IBAD (Ion-Beam-Assisted) on Hastelloy metal tape as a substrate for Y-123 wire.
-Yttrium-stabilized zirconia (YS) oriented in-plane by a special film formation method called Deposition.
Z) having an intermediate layer formed thereon is used. The Y-123 formed thereon due to the effect of the YSZ intermediate layer is also in-plane oriented, having a boiling point of liquid nitrogen of 77K and a self-magnetic field of 10 ⁶ A / c.
A high Jc of m2 and a critical current value of about 100 A are obtained.

[0004] Advances in Superco
nductivity VIII, Supplinger
-Verlag, Tokyo (1996) pp75
9, Yamazaki et al. Reported that a Y-123 wire was manufactured using a silver tape having a {110} <001> texture as a substrate. Since silver does not react with the superconductor and does not oxidize, Y-123 can be produced directly on a silver tape without forming an intermediate layer.

Similarly, Doi et al. In Advances in
Superconductivity VIII,
Supplinger-Verlag, Tokyo (1
996) pp903 describes a wire rod in which a Tl-1223 oxide superconductor is directly formed on a silver tape having a cubic texture. Due to the effect of the texture of silver, in-plane orientation of Y-123 and Tl-1223 is realized. Since these silver tapes having a texture suitable for crystal orientation can be formed only by rolling or subsequent heat treatment, they are effective in producing a long superconducting wire.

On the other hand, a single crystal substrate of a metal oxide such as strontium titanate and magnesium oxide is widely used as a substrate for a superconducting film-like device. However, it is difficult to increase the size of these single crystal materials by the current technology, and only a method of thermally connecting substrates of several cm square to increase the size is partially implemented.

[0007]

The substrate used for the oxide superconducting wire comprises (a) superconducting orientation controllability, (b) resistance to reaction and oxidation, (c) flexibility, and (d) surface. Smoothness, (e) high mechanical strength, (f) easy lengthening,
(G) It must satisfy conditions such as low cost. In addition, the substrate of the oxide superconducting device includes (a) superconducting orientation controllability, (b) reaction resistance and oxidation resistance, and (c)
It must satisfy conditions such as surface smoothness, (d) high mechanical strength, (e) easy area enlargement, and (f) low cost.

In a wire rod substrate having a YSZ intermediate layer formed on a Hastelloy metal tape, YSZ is formed by a special vacuum film forming method.
Z is manufactured, and the substrate manufacturing speed is several tens cm / h.
And slow. Therefore, there is a problem that it is difficult to stably realize a length of several hundred meters to several kilometers that is originally required for a substrate of a superconducting wire. In addition, since the Hastelloy metal tape used for the substrate is as thick as 0.1 mm, there is a problem that the Jc of the superconductor is large, but the overall Jc including the substrate is as small as about 1/100 of Jc.

On the other hand, a silver wire substrate having a texture does not require an intermediate layer such as YSZ, and can be manufactured by relatively simple processing, so that it is easy to increase the length and the area. However, the biggest problem is the low mechanical strength of silver. For example, even if a long wire is obtained using a silver tape-shaped substrate, there is a possibility that the wire is broken due to the tension at the time of forming the coil because the yield stress of the substrate is small. Before that, when forming the superconductor, the substrate was 700-90.
Since silver is heated to 0 ° C., silver having a lower melting point and a lower yield stress at higher temperatures has a problem of melting or deforming.
The recrystallized texture is formed in a process in which the strain accumulated in the metal by the rolling is heated and released.

[0010] For this reason, even if a suitable texture is formed, there is an instability that a strain is applied after that, and when heated further, the texture changes to another texture which is not preferable as a substrate. When a substrate is used, bending distortion is frequently applied. Therefore, it is necessary to prevent the original texture from collapsing, but it is difficult with the current silver tape. Furthermore, there is a problem that silver, which is a noble metal, is expensive.

As one simple method for improving the mechanical strength of a metal substrate, it is conceivable to form a composite with a different metal having higher strength. It is well known that, when different kinds of metals are combined and machined, elements are diffused on a new surface generated at the interface between the two, and a strong composite is obtained. By applying heating, diffusion at the interface is further promoted and bonding strength is increased.

[0012] Metals having different hardnesses and deformation resistances have different hardnesses during the processing, so that normal processing cannot be performed. Therefore, the metal is often softened by annealing. However, most of the recrystallized texture of the silver substrate can be obtained by annealing at a stretch after adding an appropriate degree of processing by rolling. If annealing is performed during rolling or rolling is performed again after annealing, a texture completely different from the original texture is formed.

For this reason, there is a problem that even if the hardness of the metal to be combined with silver is significantly different during processing and processing becomes difficult, annealing for softening cannot be applied. When rolling is repeated without annealing, the soft silver eventually breaks or peels, and does not serve as a composite substrate. Further, the silver substrate having the recrystallized texture has crystal grains developed, and the irregularities at the crystal grain boundaries are large, and the problem remains in the smoothness of the substrate.

[0014] A large-area substrate can be produced also in the substrate of the superconducting film-shaped device by applying the current technology for producing a wire rod substrate. However, as in the case of the wire rod substrate, it is expected that the substrate will not necessarily have sufficient performance in terms of the production speed and mechanical strength.

As described above, none of the conventional wire rod substrates and the methods for producing the same satisfy the conditions (a) to (g) at the same time. Factors such as low cost are insufficient. The same applies to a conventional device substrate.

An object of the present invention is to provide a machine suitable for forming a long and homogeneous oxide superconducting wire having a high critical current density and a critical current at a temperature of liquid nitrogen or higher and a large-area film device. An object of the present invention is to provide a long or large-area metal substrate having high strength, hard to be broken, excellent in smoothness, excellent in mass productivity and cost, and a method of manufacturing the same.

[0017]

An object of the present invention is to provide a superconducting film comprising a metal coating layer having a recrystallized texture for growing in contact with a metal, and a metal base material having a higher yield stress than the metal coating layer. This is achieved by providing a metal substrate for an oxide superconductor characterized by the above. In particular, a remarkable effect is obtained when the metal coating layer is an FCC metal or an alloy thereof and the metal base material is an intermetallic compound or a precipitation hardening metal.

The metal substrate for an oxide superconductor according to the present invention comprises a step of assembling each metal constituting a metal base material, a step of forming a composite of the metal base material assembly with a metal coating layer, and an outline of the composite. A primary forming step of processing into a shape, a step of rolling the primary formed body without annealing in the middle, a step of annealing the rolled formed body for recrystallization in an inert atmosphere or vacuum, and a metal base material. It is obtained by adopting a manufacturing method including a firing step for forming.

By using the metal substrate for an oxide superconductor of the present invention, a Y-123 wire, a Hg-1223 wire, and a device for electric power and electronics can be obtained.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, among the elements required for a substrate, orientation controllability, reaction resistance and oxidation resistance are provided by a metal coating layer having a recrystallized texture, and the flexibility and mechanical properties are improved. As for the mechanical strength, a composite substrate made of only a metal provided by a metal base material having higher mechanical strength is supplied. A typical example of the metal substrate for an oxide superconductor according to the present invention is shown in FIGS. 1 (a) and 1 (b).

Between the upper and lower metal coating layers 1 having a recrystallization texture, a metal base material 3 made of an intermetallic compound 2 grown in a layer form is embedded. As the metal coating layer, $ 10
0｝ <001>, {110｝ <001>, and even ｛hk
Silver or platinum which forms a recrystallization texture such as 0 集合 <001>. These metal coating layers 1 have the effect of aligning the crystal axes of the individual crystal grains in a certain direction when the superconducting polycrystalline layer grows on the substrate. It is already known that the above-mentioned recrystallization texture is formed in silver, but we have conducted intensive studies on other metals and found that similar recrystallization texture can be obtained in platinum. In addition to the above, it was confirmed that the composition exhibited better orientation controllability than silver.
Since platinum has a melting point of 1770 ° C., which is higher than that of silver at 961 ° C., even when a recrystallized texture is formed, the crystal grains do not grow as large as silver and have excellent smoothness as a substrate.

On the other hand, the metal base material is, for example, Ni ₃ Al,
NiAl, Ni ₂ Al ₃ , NiAl ₃ , NiAl ₃ + bor
on and a mixture thereof, and further, Ni ₃ (Al, Cr),
Ni ₃ (Al, Ti), Ni ₃ (Al, Nb), Ni ₃ (AlM
n), Co ₃ Ti, Pt ₃ In, Pt ₃ Al, Pt ₃ Ga,
An intermetallic compound generally referred to as A ₃ B, such as Pt ₃ Ga + boron, and a mixture thereof.

These compounds are 200 to 600 M at room temperature.
It shows a high yield stress of Pa. Since the recrystallized texture is formed by annealing a rolled metal at several hundred degrees Celsius, its yield stress is, for example, 60 to 80 MPa for platinum and 40 to 80 MPa for silver.
It is smaller than 50 MPa and 100 MPa. However, by incorporating the metal base material, the yield stress as a substrate can be made 100 MPa or more at room temperature. In particular, many intermetallic compounds increase the yield stress as the temperature becomes higher. Therefore, the yield stress increases rather in a high temperature state at the time of forming the superconductor, so that disconnection or fusing of the substrate does not occur.

The substrate structure of the present invention can stably maintain the original texture even with respect to bending strain applied when the substrate is used. This is because the metal base material takes on the mechanical strength of the substrate, so that the thickness of the coated metal itself can be significantly reduced, and therefore, even if the same bending is applied, the strain generated in the coated metal is reduced. As a result, the recrystallized texture can be kept stable.

Although silver and platinum, especially platinum are particularly expensive as compared with other metals, the use of the above-mentioned metal base material can reduce the amount of noble metal used per unit area, thereby reducing the cost of the substrate. Can be reduced.

FIG. 2 shows an example of a method for manufacturing a metal substrate for an oxide superconductor according to the present invention. The method includes a metal base material assembling step, a metal base material aggregate and a composite step of coating metal,
It comprises a primary forming step, a rolling step, a recrystallization annealing step, and a firing step. In the first aggregation process, for example, FIG.
As shown in (a), when the metal base material is a Ni ₃ Al intermetallic compound, a nickel sheet 4 and an aluminum sheet 5 constituting the intermetallic compound are wound around a metal rod 6 to obtain an aggregate 7.

In the subsequent compounding step shown in FIG. 2 (b), the preceding aggregate 7 is inserted into the coated metal pipe 8 where a recrystallized texture suitable for controlling the orientation of the oxide superconductor is obtained, and is placed at a predetermined position. Deploy. One of the features of the manufacturing method of the present invention is that the material to be incorporated into the coated metal is not the metal base material having high mechanical strength itself, but the metal constituting the material. For example, the yield stress at room temperature of the A ₃ B intermetallic compound is about 2
The yield stress of the metal itself constituting these components is generally 100 MPa or less, which is close to that of platinum or silver.

By constructing such an aggregated material, it is possible to easily work without intermediate annealing in the primary forming step and the rolling step of FIG. Compared with the related art, the present invention can simplify the manufacturing process and reduce the product cost. In the primary forming step, when a long tape-shaped substrate for a wire is obtained, the tape-shaped body 9 is formed by extrusion, drawing, swaging, or the like.

On the other hand, when a wafer-shaped substrate having a large area is to be obtained, the wafer is roughly shaped into a shape by forging, pressing or the like.
In the rolling step shown in FIG. 2D, both the long tape-shaped substrate and the wafer-shaped substrate are processed into a final shape and thickness by rolling, and are processed into the metal substrate 10 to have final dimensions.

The metal substrate 10 is treated with N _{2 in the} recrystallization annealing step.
The metal coating layer 1 is heated under an inert atmosphere gas such as Al or Ar or under vacuum and has a recrystallized texture as shown in FIG.
1 is formed. The desired recrystallized texture can be obtained even with oxygen or air. However, in order to improve the smoothness of the surface of the coating layer and to suppress the oxidation of the nickel sheet 4 and the aluminum sheet 5, an inert atmosphere gas or vacuum is used. It is preferable to carry out below.

Also in this recrystallization annealing step, the nickel sheet 4 and the aluminum sheet 5 partially react to form an intermetallic compound 12, but in the firing step, the intermetallic compound 12 and the metal coating layer 11 react. It is completed to form a high-strength metal base material 13. At this time, the atmosphere does not affect the metal base material formed by oxygen or air. The obtained substrate is heated at the time of forming the superconductor. If the metal base material can sufficiently react during the heating, the final firing step can be omitted.

(Comparative Example 1) A study was made on the formation of a composite of platinum and stainless steel having sufficient mechanical strength as a metal base material. For the compounding, a method of incorporating a stainless steel round bar or pipe into a platinum pipe and drawing and rolling to integrate it was adopted. Table 1 shows dimensions and processing conditions of each metal material used. Here, the orientation controllability of the superconducting film is ultimately borne by the recrystallization texture of the silver coating layer.
The processes of drawing and rolling were all performed cold without performing intermediate annealing. In the case of this substrate structure, the stainless steel as the base material has no particular restriction on the texture because its main role is to reduce the amount of platinum used and to improve the substrate strength. For this reason, those which were annealed in a vacuum and sufficiently softened before assembling were used.
The one incorporating the stainless steel round bar could not be pulled out.

On the other hand, in the case where the stainless steel pipe was incorporated, a large bending was found in the drawn material from about 4.7 mmφ, and the drawing process had to be finally terminated at 4.5 mmφ.

[0034]

[Table 1]

Next, the 4.5 mmφ embedded material obtained by drawing was cold-rolled. Since there is a great difference in hardness and ductility between platinum and stainless steel, and since annealing is not performed after drawing, it is expected that the bonding property at the interface between platinum and stainless steel is weak. In order to enable normal rolling, a method of rolling a sample between stainless steel sheets of the same kind was adopted. However, even with such considerations, the platinum layer was separated from the stainless steel base material at the stage of about 130 mm thickness.

A large peeling of the platinum layer from the tip of the rolled sample was observed, and the subsequent peeling of the platinum layer was observed as wrinkles. After rolling, only the platinum layer was cut off and annealed at 700 ° C. for 1 hour in air, and then the X-ray pole figure was measured. However, since the rolling ratio was not sufficient, the recrystallization texture suitable for controlling the orientation of the superconductor was obtained. No formation was observed.

(Embodiment 1) An embodiment of the present invention will be described below.

First, a nickel sheet 4 and an aluminum sheet 5 are wrapped around a metal rod 6 such as a silver rod to form an aggregate 7, and a nickel sheet 4A is wound around the inner and outer peripheral sides of the aggregate 7 to form a nickel sheet. Pipe 8 outside 4A
For example, the assembly was inserted into a platinum pipe and the end was sealed to produce an assembly having the cross section of FIG. The thickness ratio of the sheet was set to Ni: Al = 2: 1 to match the stoichiometric composition of Ni ₃ Al. Further, a nickel sheet 4A is wrapped around a portion in contact with the silver bar and platinum to prevent silver and platinum from directly contacting aluminum having a low melting point and easily reacting.

Table 2 shows the dimensions of each constituent material. afterwards,
The outer diameter was reduced to 3 mm by drawing. Further, it was processed into a tape shape having a thickness of 50 μm and a width of 10 mm by cold rolling. During the drawing and the rolling, the tape could be processed relatively easily without any annealing.
At this stage, the thickness of the platinum layer is about 5 microns, which is 71% compared to the case where all 50-micron thick tapes are made of platinum.
Is reduced. For this rolled tape,
A recrystallization annealing at 700 ° C. for 1 hour in air was performed.

[0040]

[Table 2]

At the end of the tape where nickel and aluminum were exposed, aluminum was oxidized by air. However, as can be seen from FIG. 4 of a cross-sectional photograph of the inside of the metal base material, no oxidation occurred inside. In addition, it can be seen from FIG. 5A that the layered nickel and aluminum partially react with each other. FIG. 6 shows a (200) X-ray pole figure of platinum in the metal coating layer. The two symmetrical peaks indicate that the platinum layer is suitable for the superconductor orientation.
10 <<001> indicates that a recrystallized texture is formed. FIG. 7 is a metal microscope photograph of the platinum layer surface 14 which is a metal coating layer. No large platinum crystal growth was observed on the surface, indicating that the surface had a smooth surface. Thereafter, annealing at 850 ° C. for 1 hour corresponding to the conditions for forming a superconductor was performed in air, and a tensile test was performed. In addition, 15 is a flaw of unevenness.

As a result, the yield stress was 175 MPa. A photograph of a cross section of the metal base material 13 at that time is shown in FIG. 8, and as shown by the composition distribution in FIG. 5B, almost the target Ni ₃ Al is formed in a layer. In the layered structure, the aluminum sheet 5 between the nickel sheets 4 is recessed from the nickel sheet 4.

(Embodiment 2) As a second embodiment of the present invention, a case is described in which silver is used for the coating layer and Ni ₃ Al with boron is used for the metal base material. The steps of assembling the metal base material and combining with the coating metal are almost the same as those in the first embodiment. An aluminum sheet to which 0.1 mol% of boron was added was used. Table 3 shows the constituent dimensions of the composite.

[0044]

[Table 3]

In this embodiment, the hydrostatic extrusion method and the drawing method were employed in the primary molding step because of the large outer diameter of the composite. The diameter was reduced in one step to an outer diameter of 6.7 mm by extrusion. Thereafter, the diameter was further reduced to an outer diameter of 3 mm by a drawing process to obtain a round bar having a length of 5 m. This round bar is repeatedly rolled in an atmosphere of 110 ° C. to finally have a width of 10 mm,
A tape having a thickness of 50 microns and a length of 70 m was obtained. Here, the reason why the rolling is performed at 110 ° C. is not to soften the work material but to obtain a suitable texture. 110
It has been confirmed that the hardness of the rolled material does not change at all at a low temperature of about ° C. This was continuously passed through a tubular electric furnace set at 700 ° C. for a residence time of 1 hour to carry out recrystallization annealing. The atmosphere was in the air.

When the cross section was observed, it was confirmed that the composition was almost Ni ₃ Al. In this embodiment, since the final layer thickness of nickel and aluminum is thinner than that in Embodiment 1, it is considered that Ni ₃ Al was formed even at a lower 700 ° C. When a tensile test was performed on the tape, the yield stress was about 150 MPa. It was also found that the elongation was improved in the stress-strain diagram as a characteristic by the addition of boron. This was the same even when the Al molarity of Ni ₃ Al was slightly reduced. When the (220) X-ray pole figure of the obtained tape was measured, it was confirmed that {100} <001> recrystallization texture was formed. The ratio of the intensity of {100} <001> was 98%.

FIG. 9 shows that the tape was subjected to various bending strains,
Curve 16 shows the {100} <001> intensity when heated at 0 ° C. for 30 minutes. Curve 16 is a characteristic diagram of the bending strain of a conventional silver substrate. Curve 17 for a 50 micron thick tape of silver alone is also shown. Curve 17 is a characteristic diagram of the bending strain of the substrate according to the present invention. It can be seen that disturbance of the texture due to bending strain is greatly suppressed. This is considered to be the effect of reducing the thickness of the silver layer due to the composite.

Example 3 After the same rolling process as in Example 2, the tape was replaced with air and recrystallization annealing was performed in a nitrogen atmosphere at the same temperature and time. Fig. 1 shows a photograph of the surface of the silver coating layer.
0 is shown. FIG. 1 is compared with FIG.
It can be seen that the surface in annealed in nitrogen shown in FIG.

Example 4 A slurry containing nickel particles having an average particle diameter of 20 μm was applied to an aluminum sheet having the same size as in Example 1. After the sheet was dried, the weight was measured, and the application and drying were repeated again so as to obtain a predetermined nickel amount corresponding to the molar ratio of Ni ₃ Al. The obtained sheet was wound around a metal rod, and thereafter a tape-like substrate was produced in the same manner as in Example 1.

When the inside of the tape was observed, it was confirmed that a metal base material having a composition ratio corresponding to Ni ₃ Al, although a part of the inside of the layer contained voids. Yield stress by tensile test is about 1
It was 10 MPa.

(Example 5) As a fifth example of the present invention, a wafer-like substrate having platinum as a metal coating layer and Pt ₃ Al as a metal base material was manufactured. Platinum sheets and aluminum sheets of 5 cm × 20 cm square were alternately laminated to a thickness of about 2 mm so that the molar ratio of Pt: Al became 3: 1. 7cm slightly larger on the top platinum sheet
A nickel sheet of 22 cm square and 20 microns thick was overlaid as a diffusion barrier for aluminum. Further, a platinum plate having a size of 5 cm × 20 cm and a thickness of 1 mm was placed thereon as a coating metal.

After thick-welding the four corners of the laminate, the laminate was cold worked by a forging press until the entire thickness became half. Thereafter, the thickness is uniformly 0.5 m by a cold rolling mill.
The rolling was repeated in the minor axis direction of the sample until the value reached m. The obtained rolled substrate was subjected to recrystallization annealing at 700 ° C. for 1 hour in a muffle furnace in a high-purity argon atmosphere. At this time,
Heating was performed while applying a light load so that the substrate was not deformed during firing. The obtained substrate had a size of about 25 cm square. The peripheral burrs and excess nickel sheet for the barrier were cut off to obtain a 24.5 cm square wafer-like substrate.

The properties of the platinum coating layer were almost the same as in Example 1. Due to the effect of the nickel sheet laminated at the time of molding, no contamination of the platinum layer with aluminum was recognized. In addition, a layered structure having the same composition ratio as Pt ₃ Al having a yield stress at room temperature of 600 MPa was confirmed in the metal base material bonded to the lower portion of the platinum layer. A hard large-area wafer-like substrate was obtained despite its thickness of about 0.5 mm.

(Example 6) First, an aluminum sheet and a nickel sheet were wound around a silver bar so that the nickel sheet came to the outer periphery. Thereafter, this was inserted into a nickel pipe having a thickness of 0.2 mm, and the end was sealed to produce an assembly.

The thickness ratio of the sheet was set to Ni: Al = 2: 1 in order to match the stoichiometric composition of Ni ₃ Al. Also, extra nickel sheet is wrapped around the part in contact with the silver bar,
The structure prevents direct contact with aluminum. Except for the nickel pipe, the dimensions of each constituent material are the same as in Table 2. Thereafter, the outer diameter was reduced to 3 mm by drawing. Furthermore, the thickness is 50 microns and the width is 1 by cold rolling.
It was processed into a 0 mm tape shape. This rolled tape was subjected to recrystallization annealing at 900 ° C. for 1 hour in high-purity argon. At this time, the nickel coating layer showed a {100} <001> recrystallization texture. Thereafter, baking for forming Ni ₃ Al was performed at 1300 ° C. for a short time of 10 minutes.

Of the finally obtained tape-shaped substrates, 10
m was set in a continuous conveyance device, and barium nitrate, calcium nitrate, copper nitrate and rhenium oxide were added to the region heated to 700 ° C. in the air at a metal molar ratio of Re: Ba: Ca: Cu =
A mist having a particle diameter of about 10 μm generated from an aqueous solution dissolved to have a ratio of 0.2: 2: 2: 3 was sprayed.
An amorphous layer having a thickness of about 2 μm was formed over the entire length of the substrate at a transport speed of 0.8 m / h. The metal composition of this amorphous layer matched the metal composition of the aqueous solution used.

While continuously transporting the substrate on which the amorphous layer is formed into a pressurized reactor heated to 830 ° C. at 3 atm of argon, an argon carrier gas containing mercury vapor having an equilibrium vapor pressure of 400 ° C. is brought into contact. Was. After reacting for a residence time of 30 minutes, the surface was measured with an X-ray diffractometer. The amorphous layer is Hg-1 by contact with mercury vapor.
223 was the main phase, and it was confirmed that the superconducting film was slightly mixed with the Hg-1212 phase.

When the X-ray pole figure was measured, Hg
It was confirmed that a so-called in-plane alignment film was formed in which the c-axis of -1223 was perpendicular to the substrate surface and the a-axis was aligned in the longitudinal direction of the substrate. Jc of 1m of prepared Hg-based superconducting wire
Was 500,000 A / cm 2 when measured in liquid nitrogen. The highest Jc in the distribution of Jc measured at 2 cm intervals was 1,000,000 A / cm 2.

[0059]

As described above, according to the present invention, a metal substrate is formed by inserting an assembly into a coated metal pipe and cold rolling it into a desired shape. A metal coating layer and an intermetallic compound are formed on a metal substrate in an annealing step. The metal coating layer and the intermetallic compound firmly adhere to each other to form a metal base material.

As a result, high orientation controllability, surface smoothness, high mechanical strength, and high mass production can be achieved with respect to a long tape-shaped metal substrate or a large-area wafer-shaped metal substrate having flexibility for an oxide superconductor. And low cost can be simultaneously provided. Further, by using the substrate of the present invention, a long and homogeneous oxide superconducting wire or a large-area film device having a high critical current density (Jc, overall Jc) and a critical current at a temperature of liquid nitrogen or higher can be formed. There is also an effect.

[Brief description of the drawings]

FIGS. 1A and 1B are schematic perspective views showing an example of a metal substrate for an oxide superconductor of the present invention.

FIGS. 2A to 2F are schematic perspective views showing a manufacturing process sequence of a metal substrate for an oxide superconductor of the present invention.

FIG. 3 is a cross-sectional view showing a photograph of a cross-section of a composite material during a tape-shaped metal substrate manufacturing process according to one embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a photograph of lamination of a metal base material in a tape-shaped metal substrate manufacturing process.

FIGS. 5A and 5B are characteristic diagrams showing a composition distribution of a metal base material of a tape-shaped metal substrate.

FIG. 6 is an X-ray pole figure of the metal coating layer of the tape-shaped metal substrate.

FIG. 7 is a plan view by a photograph of the surface of a metal coating layer of the tape-shaped metal substrate.

FIG. 8 is a sectional view by a photograph showing a section of a metal base material of the tape-shaped metal substrate.

FIG. 9 is a view showing a bending strain resistance characteristic of a recrystallized texture in a tape-shaped metal substrate according to another embodiment of the present invention.

10 (a) and (b) are plan views of photographs showing the surface of a metal coating layer on a tape-shaped metal substrate according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Metal coating layer, 2 ... Intermetallic compound, 3 ... Metal base material, 4
... nickel sheet, 5 ... aluminum sheet, 6 ... metal bar, 7
... Assembly, 8 ... Pipe, 9 ... Schematic tape, 10 ...
Metal substrate, 11: metal coating layer, 12: intermetallic compound, 1
3. Metal base material.

Continued on the front page (72) Inventor Hiroyuki Akada 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Tetsuo Fujiwara 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Hitachi, Ltd. Hitachi Research Laboratories (72) Inventor Shigeo Nagaya 20-1, Kitakanyama, Odaka-cho, Midori-ku, Nagoya-shi, Aichi F-term in Chubu Electric Power Co., Inc. 4G047 JA04 JB06 JC20 KB04 KB14 KB17 KD10 5G321 AA01 AA04 BA01 BA07 CA03 CA04 CA18 CA20 CA27 DB26

Claims (14)

[Claims] 1. A metal substrate on which an oxide superconducting film is formed in close contact, a metal coating layer having a recrystallized texture grown by contacting the superconducting film, and a metal mother having a higher yield stress than the metal coating layer. A metal substrate for an oxide superconductor characterized by comprising: 2. The metal substrate for an oxide superconductor according to claim 1, wherein a yield stress value of the entire metal substrate is 100M.
A metal substrate for an oxide superconductor characterized by being larger than Pa. 3. The metal substrate for an oxide superconductor according to claim 1, wherein the metal substrate for an oxide superconductor is a flexible long tape shape. 4. A metal substrate for an oxide superconductor according to claim 1, wherein the metal substrate for an oxide superconductor is in a hard wafer shape. 5. The oxide superconductor metal substrate according to claim 1, wherein the metal coating layer is formed of FC
A metal substrate for an oxide superconductor, which is a C metal or an alloy thereof. 6. The oxide superconductor according to claim 1, wherein the metal base material is an intermetallic compound or a precipitation hardening metal. For metal substrate. 7. The metal substrate for an oxide superconductor according to claim 5, wherein the metal coating layer of the metal substrate for an oxide superconductor according to claim 5 is one of FCC metals, particularly Pt, Ag or an alloy thereof. 8. The oxide superconductor according to claim 6, wherein the metal base material of the metal substrate for an oxide superconductor is an A ₃ B intermetallic compound, particularly Ni ₃ Al or a compound of Ni and Al. For metal substrate. 9. The metal substrate for an oxide superconductor according to claim 1, wherein said metal coating layer is made of Pt.
A metal substrate for an oxide superconductor, wherein the metal base material is boron-added or Ni-rich Ni ₃ Al. 10. A step of assembling each metal constituting the metal base material, a step of compounding the metal base material aggregate with a metal coating layer, a primary forming step of processing the composite into a general shape, Rolling the compact without annealing in the middle, annealing the roll compact in an inert atmosphere or vacuum for recrystallization, and further comprising a firing step for forming a metal base material. A method for producing a metal substrate for an oxide superconductor, which is characterized in that: 11. The method for manufacturing a metal substrate for an oxide superconductor according to claim 10, wherein the step of assembling the metal base material comprises winding together a metal sheet constituting the metal base material, and A method for manufacturing a metal substrate for an oxide superconductor, wherein the step of compounding the material and the metal coating layer comprises placing the rolled sheet assembly in a metal coating material pipe. 12. A metal for an oxide superconductor, comprising an oxide superconducting wire formed by closely contacting a YBa ₂ Cu ₃ O ₇ superconducting film on the metal substrate for an oxide superconductor according to claim 3. substrate. 13. The metal substrate for an oxide superconductor according to claim 3, wherein the metal coating layer is Ni, and the metal base material is boron-added or Ni-rich Ni ₃ Al, and A metal substrate for an oxide superconductor, which is an oxide superconducting wire formed by closely attaching an Hg-based superconducting film. 14. A metal substrate for an oxide superconductor, wherein the metal substrate for an oxide superconductor is a device for power and electronics formed by closely attaching an oxide superconducting film on the metal substrate for an oxide superconductor according to claim 4. .