JPS6144362B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a compound superconducting wire with excellent superconducting properties and productivity.

Conventionally, compound-based superconducting wires include, for example,
Products in which a superconducting compound layer such as Nb ₃ Sn or V ₃ Ca is formed in a normal conducting metal have been put into practical use.

As a method for manufacturing these compound superconducting wires, for example, the following method has been conventionally performed, but here, the case of forming a Nb ₃ Sn layer will be described as an example.

() Numerous insertion holes are drilled in the Cu-Sn alloy matrix, and a core Nb rod is inserted into these holes to form a composite. The bronze method then involves reducing the area of this composite to make it into a thin wire, and then heat-treating it to form a Nb ₃ Sn layer on the surface of the Nb rod.

() After melting an alloy of Cu with Nb and Sn added, the resulting ingot is processed to reduce its area and made into fine wires, and then heat-treated to form a continuous fibrous Nb ₃ Sn layer in the conductor. , the TSUEI method, in which current is passed through the proximity effect.

() An ingot obtained by melting and quenching an alloy containing Cu and Nb is processed to reduce its area and become a thin wire, so that Nb is distributed inside the wire in the form of continuous fibers. Next, after Sn is attached to the surface of this thin conductor, heat treatment is performed to diffuse this Sn and form an Nb ₃ Sn layer on the surface of the fibrous Nb using the IN SITU method.

However, since all of these methods require surface reduction processing such as extrusion and drawing, they have the drawback of complicated processes and low productivity. In particular, the bronze method described in () above has poor workability for Cu-Sn alloys, and the critical current value deteriorates significantly with strain. Furthermore, in the Zei method (), there is little deterioration of the critical current value with respect to strain, but considering the flexibility of the Cu-based alloy, the limit for the addition amount of Nb is 10 atomic % and the limit for Sn is 5 atomic %. Therefore, the critical current value (Jc) of the entire superconductor (overall) is one to two orders of magnitude smaller than that of the bronze method, which is not practical. In addition, the in-situ method in () is Cu-
Since Nb alloy is used, it has good flexibility and the amount of Nb added can be reduced.
The critical current value is comparable to the bronze method because it allows up to 30 atom%, but the Sn adhesion process, Sn melting,
There are drawbacks such as shedding and the fact that it takes a long time to generate the Nb ₃ Sn layer.

The present invention was made in view of the above points, and by directly forming the alloy liquid forming the superconducting wire into a thin tape, it is possible to improve productivity by omitting complicated surface reduction processing, and to improve productivity by forming superconducting layers such as Nb and Sn. We have developed a method for manufacturing compound superconducting wires with improved characteristics by expanding the upper limit of the amount of forming elements added.

That is, the present invention injects an alloy liquid made of the elements constituting the superconducting wire from the nozzle into a container having a nozzle onto a high-speed rotating roll by inert gas pressure, rapidly cools it, and forms it into a tape shape. The first invention provides a method for manufacturing a compound superconducting wire, which is characterized in that the wire is then heat-treated to form a superconductor layer.

Furthermore, the present invention allows a composite liquid consisting of elements constituting the superconducting wire body and a normal conductive metal melt serving as a stabilizing material, which are placed in separate containers each having a nozzle, to be passed through each of the nozzles under inert gas pressure. Spraying the mixture separately onto each roll of a pair of high-speed rotating rolls and rapidly cooling each roll, and joining each of the formed tapes into a single tape by bringing them into close contact between the rolls and diffusion bonding,
A second invention provides a method for manufacturing a compound superconducting wire, which is characterized in that the wire is then heat-treated to form a superconductor layer.

The present invention will be explained in detail below.

The compound superconducting wire according to the present invention has a structure in which a superconducting compound is contained in a matrix of normal conducting metals such as Cu and Al. In the present invention, superconducting compounds include, for example, Nb ₃ Sn, Nb ₃ Al,
Examples include A-15 type compounds such as Nb ₃ (Al, Ge), V ₃ Ga, Nb ₃ Ga, Nb ₃ Ge, and V ₃ Si. In addition, Cu
NbCN when using Ni or Ni alloy instead of
Alternatively, it can be applied to the case of producing a superconducting compound such as a V ₂ (Hf, Zr) compound using a V alloy.

First, as shown in FIG. 1, an alloy liquid 3 made of elements constituting a compound superconducting wire is poured into a container 2 made of a quartz tube or the like and having a nozzle 1 at its tip.

That is, this alloy liquid 3 is an alloy of a normal conducting metal and an element that forms a superconducting compound. For example, Cu is used as the normal conducting metal and Cu is used as the superconducting compound.
When forming Nb ₃ Sn, it becomes a melt of Cu--Nb--Sn alloy. In this case, the amount of Nb and Sn added is Nb60
atomic%, Sn up to 30 atomic% is allowed. In addition, in order to enhance the cooling effect of these alloy liquids 3, P, C,
A small amount of B, Si, etc. may be added.

The composite liquid 3 may be heated and melted in the container 2 using an electric furnace or a high frequency furnace, or the melted liquid in another container may be heated and melted in the container 2 having the nozzle 1.
You can move it inside.

Next, an inert gas such as argon gas or helium gas is blown into the container 2 from the side opposite to the side where the nozzle 1 is provided, and onto one roll 4a of the twin rolls 4a and 4b provided below the nozzle 1. Joint financial liquid 3
Inject. The twin rolls 4a, 4b rotate at high speed, and the composite liquid 3 sprayed onto the surface is rapidly cooled and solidified into a tape shape.Then, the tape 5 is passed between the pressurized twin rolls 4a, 4b. It is designed to be pulled out downwards.

In this case, the composite liquid 3 injected from the nozzle 1
The outer circumferential position of the roll 4a where the twin rolls 4 contact
The angle θ between the contact points of a and 4b is determined by the cooling rate of the alloy liquid 3. That is, the combined liquid 3 injected onto the roll 4a is rapidly cooled, and the twin rolls 4a,
It is necessary that at least the surface has been cooled to a solidified state by the time it reaches the contact point 4b. Therefore, this θ takes into account the temperature of the alloy liquid 3, the amount of injection, and the temperature, outer diameter, and rotational speed of the roll 4a, and the surface of the alloy liquid 3 solidifies before it reaches the contact point between the twin rolls 4a and 4b. However, θ is usually determined so that the cooling rate is 10 ⁴ to 10 ⁵ ° C./sec.

By rapidly cooling the alloy liquid 3 in this manner, a tape 5 is obtained in which elements constituting a superconducting compound such as Nb are continuously precipitated in the form of fibers in a normal-conducting metal matrix.

The tape 5 thus obtained is then heat treated to produce a superconducting compound. This heat treatment
This is done by heating at 550 to 900°C for several hours to several hundred hours. For example, in tape 5 in which fibrous Nb was precipitated in a Cu-Sn matrix, heat treatment was performed to improve the Nb surface as shown in Figure 2.
A Nb ₃ Sn superconducting compound layer 6 is generated, and a compound superconducting wire 7 through which current flows due to the proximity effect is obtained.
This example is suitable for manufacturing a compound superconducting wire 7 for small current use, and will be described below in a case where it is suitable for manufacturing a compound superconducting wire for large current use.

Twin rolls 4 rotating at high speed as shown in Figure 3
Two containers 2a to 2b having nozzles 1a and 1b are arranged above a and 4b. One container 2a is filled with an alloy liquid 3 consisting of elements constituting the compound superconducting wire, and the other container 2b is filled with a stabilizing material.
Add normal conductive metal melt 8 such as Cu or Al.

Next, the nozzles 1a and 1b of each of the containers 2a and 2b are
Inert gas is blown into each roll 4 provided below the nozzles 1a and 1b.
The alloy metal liquid 3 and the normal conductive metal melt 8 are injected onto a and 4b. The composite metal liquid 3 and the normal conductive metal melt 8 sprayed onto the surfaces of the twin rolls 4a and 4b are rapidly cooled and formed into tape shapes, respectively, and then passed between the pressurized rolls 4a and 4b. The tapes 5a and 5b are joined and formed into a single tape 5'.

In this case, the angle θ between the outer circumferential position of one roll 4a with which the composite metal liquid 3 injected from the nozzle 1a contacts and the contact point of the twin rolls 4a and 4b, and the normal conductive metal liquid injected from the nozzle 1b. The angle θ' between the outer peripheral position of the other roll 4b with which the liquid 8 contacts and the contact point of the twin rolls 4a, 4b is
The cooling rate is determined so that the temperature at which both the tapes 5a and 5b are diffusion bonded is reached by the time the tape 8 is rapidly cooled and reaches between the contact points. Normally, this cooling temperature is preferably in the range of Tm x (0.5 to 0.95), where Tm is the solidification temperature. For example, if the normal conductive metal tape 5b is Cu, it is 600 to 1000°C, and if it is Al, it is 400 to
It is desirable to cool the tape to 600 DEG C. At this temperature, both tapes 5a and 5b are bonded by diffusion to form one tape 5'. In addition, the tape 5a obtained by rapidly cooling the alloying liquid 3 is similarly rapidly cooled to the temperature for diffusion bonding, so that it is incorporated into the normal conductive matrix.
Elements that make up superconducting compounds, such as Nb, precipitate in continuous fibers.

Next, the tape 5′ joined in this way
By heat-treating, a superconducting compound layer 6 through which current flows due to the proximity effect is formed, and as shown in FIG. A compound superconducting wire 7' for electric current can be obtained.

Next, examples of the present invention will be described.

Example 1 As shown in FIG.
An alloy consisting of 15 atomic % Sn and the balance Cu was added and melted by heating in an argon gas atmosphere. Next, blow argon gas into this composite liquid 3,
The mixture was sprayed onto a roll 4a rotating at a high speed of 2000 r.p.m. and rapidly cooled to form a tape 5 having a thickness of 50 μm and a width of 1 mm.

Next, this tape 5 was heat-treated at 700° C. for 60 hours to produce a compound superconducting wire 7 in which a continuous fibrous Nb ₃ Sn superconducting compound layer 6 was formed in a Cu--Sn matrix as shown in FIG.

The critical current value Ic and overall critical current density Jc of the superconducting wire 7 obtained in this way were measured. In an external magnetic field of 4 Tesla (Tesla), Ic =
50A, Jc=1×10 ³ A/mm ² , and external magnetic field 7
For Tesla, excellent values of Ic = 28A and Jc = 5.6×10 ² A/mm ² were obtained. Also, this tape-shaped superconducting wire 7
When the material was wound around a 4 mmφ rod and measured in the same manner, no deterioration of the critical current value was observed and stable characteristics were obtained even against strain.

Example 2 Nb30 atomic% and Sn15 pre-dissolved by high frequency
%, the balance being Cu, and a normal conducting metal melt 8 consisting of Cu are placed in a pair of quartz tube containers 2 having nozzles 1a and 1b as shown in FIG.
A and 2b were placed separately, and further heated and melted in an electric furnace in an argon atmosphere.

Next, 1.5 atmospheres of argon gas is blown into the containers 2a and 2b, and this gas pressure causes the nozzles 1a and 1 to open.
The mixture is sprayed onto twin rolls 4a and 4b arranged below the rollers 4a and 4b rotating at 2000 r.p.m., quenched, and formed into a tape. Both tapes 5 obtained in this way
A and 5b are brought into close contact between the twin rolls 4a and 4b, and are diffusion bonded to form a single tape 5', which is pulled out downward. Next, this tape 5' was heat-treated at 700°C for 60 hours to form an intermittent fibrous Nb ₃ Sn superconducting compound layer 6 in the Cu--Sn matrix as shown in Fig. 4.A stabilizing material was added to the tape 5a. A compound superconducting wire 7' composed of a normal conducting metal (Cu) tape 5b
was manufactured.

The critical current values of the superconducting wire 7' obtained in this way were measured. At an external magnetic field of 4 Tesla, Ic = 47 A, Jc = 4.7 × 10 ² Amm ² , and at 7 Tesla, Ic =
26A, Jc=2.6×10 ² A/mm ² . In addition, the way the voltage was generated at the Ic value in the critical current measurement of this superconducting wire was gradual and stable.

As explained above, according to the method for manufacturing a compound superconducting wire according to the present invention, the alloy liquid made of the elements constituting the superconducting wire is rapidly cooled and directly formed into a tape shape, so that the area reduction process is performed as in the conventional method. or annealing,
It is extremely productive as it does not require complicated processes such as adhesion of Sn.

Furthermore, according to the present invention, since the alloy liquid is directly formed into a tape shape, elements constituting the superconducting compound such as Nb and Sn can be formed without considering wire breakage or flexibility during area reduction processing as in the conventional method. The upper limit of the amount added can be greatly expanded, and as a result, the amount of superconducting compound produced can be increased, making it possible to improve the critical current density by one to two orders of magnitude.

In addition, the rapidly cooled ingot obtained by the conventional in-situ method only accounts for about 10% of the total, even at the point where the cooling rate is fast enough for practical use.
Although it is low at about 1000°C/sec, the method of the present invention has various effects such as excellent superconducting properties because the entire molten alloy is rapidly cooled and 100% of the molten alloy is put into practical use.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the outline of an apparatus for manufacturing a compound superconducting wire according to the method of the present invention, FIG. 2 is a perspective view of a compound superconducting wire manufactured using the apparatus shown in FIG. 1, and FIG. An explanatory diagram showing the outline of a device for manufacturing a compound superconducting wire composited with a normal-conducting metal tape as a stabilizing material by different methods, and FIG. 4 is a perspective view of a compound superconducting wire manufactured using the device shown in FIG. 3. It is a diagram. 1, 1a, 1b... Nozzle, 2, 2a, 2b... Container, 3... Combined liquid, 4a, 4b... Roll, 5,
5', 5a, 5b...Tape, 6...Superconducting compound layer, 7,7'...Compound superconducting wire, 8...Normal conducting metal melt.

Claims (1)

[Scope of Claims] 1. A method for manufacturing a superconducting wire consisting of a matrix of normal conducting metal and a superconducting compound, in which an alloy liquid consisting of elements constituting the superconducting wire placed in a container having a nozzle is heated under inert gas pressure. A method for producing a compound superconducting wire, comprising: injecting the compound superconducting wire through the nozzle onto a high-speed rotating roll, rapidly cooling it to form a tape shape, and then heat-treating the tape to form a superconducting compound layer. 2. In a method for manufacturing a superconducting wire consisting of a matrix of normal conducting metal and a superconducting compound, a composite liquid consisting of the elements constituting the superconducting wire body and a normal conducting compound serving as a stabilizing material are placed in separate containers with a nozzle. The metal melt is separately injected onto each roll of a pair of high-speed rotating rolls using inert gas pressure through the respective nozzles and quenched, and the formed tapes are brought into close contact between the rolls and diffusion bonded. 1. A method for manufacturing a compound superconducting wire, which comprises joining the wire into a single tape, and then heat-treating the wire to form a superconducting compound layer.