KR20060120279A - Mgb2 superconducting multifilamentary wires and films using nb-ti superconductor as a tube and a substrate - Google Patents

Abstract

Provided are a MgB2 superconducting multifilamentary wire and film using a Nb-Ti superconductor, which show superconductivity of NbTi and MgB2 at a temperature of 9K or lower and that of MgB2 at a temperature of 9K-39K. The MgB2 superconducting multifilamentary wire comprises: a tube(200) formed of a Nb-Ti superconductor; and filaments(100) incorporated into the tube and formed of MgB2. The MgB2 superconducting film comprises: a substrate formed of a Nb-Ti superconductor; and a layer deposited on the substrate and formed of MgB2. In the wire and film, the MgB2 includes MgB2 powder, Mg+B powder, MgB2+X powder or Mg+B+X powder, wherein X is a element for increasing flux pinning effect or reducing porosity of MgB2, and includes Fe, Ti, Nb, V or W.

Description

MgB2 superconducting wire and film using Nb-Ti-based superconductor as tube and substrate {MGB2 SUPERCONDUCTING MULTIFILAMENTARY WIRES AND FILMS USING NB-TI SUPERCONDUCTOR AS A TUBE AND A SUBSTRATE}

The present invention relates to a superconducting wire and a film, and in detail, the present invention relates to a superconducting wire, wherein the Nb-Ti-based superconductor is a tube in a powder in tube method, and the filament is MgB2; In the superconducting film, the Nb-Ti-based superconductor is used as a substrate, and the deposited material is MgB2;

The present invention relates to an MgB2 ultrafine core wire and a film using a Nb-Ti-based superconductor as a tube and a substrate.

Superconductors have been focused on the development of superconductors since their discovery.

A well-known Nb-Ti-based superconducting material was discovered in the 1960s, and in the 1970s, the so-called ultra-fine core wires filled with filaments of this material in many Cu matrices It was developed and became the mainstream of practical superconducting wire because it is electrically stable.

The practical Nb-Ti-based superconducting filament wire is cold-drawn with high strength and then heat-treated at a temperature of 300 to 400 ° C. to deposit a fine Ti phase in the Nb-Ti alloy to obtain a critical current density (Jc). The manufacturing method has been greatly developed, such as raising the critical current density Jc again by increasing the drawing after the aging heat treatment. However, in the case of the Nb-Ti system, since the superconducting critical temperature is too low around 9K, wide commercialization is difficult because it can be used only in an expensive liquid helium state.

4 is a cross-sectional structural view of the Nb-Ti-based superconductor ultra fine core wire, and as shown in FIG. 4, the superconducting wire is a tubular covering the superconducting filament 10 and the superconducting filament 10 which are generally formed of ultra fine core wires. It consists of the shielding metal 30 which coats the outer shape of the web 20 and the conducting wire.

On the other hand, MgB2 has been studied a lot since the discovery of superconductivity by professor akimuzu in 2001, but it is too much to say that it has entered the commercialization stage.

In the case of film, it has not yet escaped the vacuum process such as PLD, and various cases of making tape or wire are introduced, but it is 10 to 100 times higher than that of film. The critical current density is about twice as low, and many tasks remain until the commercialization stage of MgB2.

MgB2 is very brittle even though it is simply a biatomic intermetallic compound consisting of Magnesium and Boron, so it is possible to make wires or tapes by direct method, ie rolling or drawing. It is impossible.

Therefore, a powder filling method (Powder in Tube, abbreviated PIT) technique is widely used to make a superconducting wire using MgB2.

One of the important factors is the choice of the metal to be used as the tube.

In other words, due to the high affinity of Mg with oxygen, reactivity with other materials, high melting point of B, etc., there is a great difficulty in selecting a tube material, and various forms of research such as Fe, Nb, Cu, and stainless steel have been conducted. It is hard to say that it is still satisfactory.

In the case of a film, it has not yet escaped from vacuum processes such as ion beam assisted deposition (ABAD) and pulse laser deposition (PLD), and in the case of a substrate, it is limited to a single crystal such as Al ₂ O ₃ . It is true.

Substrate using metals necessary for the manufacture of joists has been tried with various metals such as Ni, Fe, stainless steel, Nb, etc., but it is not satisfactory. As with wires, Mg's affinity for high oxygen and high volatility Due to the high melting point of B, there is a great difficulty in selecting a substrate material, and many tasks remain until the commercialization of MgB2 film.

1 to 3 are cross-sectional structural diagrams of MgB2 ultrafine core wires using a Nb-Ti superconductor as a tubing according to the present invention. And a barrier layer 400 such as Nb between the shielding metal 300 and the tube 200 or between the tube 200 and the MgB2 filament 100. It can be configured to include more

4 is a cross-sectional structural view of a Nb-Ti-based superconducting multicore wire. A tubing 200 covering the superconducting filament 100 and the superconducting filament 100 and a shielding metal 300 covering the outer shape of the conductive wire. It is composed.

4 to 9 are cross-sectional structural diagrams of MgB2 superconducting films using the Nb-Ti-based superconductor according to the present invention.

Technical challenge

Therefore, the object of the present invention is an invention developed in view of the above-mentioned problems of the prior art,

The present invention relates to a superconducting wire and a film. Specifically, the present invention relates to a superconducting wire, wherein the Nb-Ti-based superconductor is a tube in a powder in tube method, and the filament is MgB2, and Nb in a superconducting film. To provide a MgB2 superconducting ultrafine core wire and a film using a Nb-Ti-based superconductor as a tubing and a substrate, wherein the Ti-based superconductor is used as a substrate and the material to be deposited is composed of MgB2. It is done.

Accordingly, an object of the present invention is to provide an MgB 2 ultrafine core wire and a film using a Nb-Ti-based superconductor having a superconducting critical temperature of 39K as a tube and a substrate.

Technical solution

In order to achieve the above object, the present invention is a superconducting wire, the superconducting MgB2 charged with a Nb-Ti-based superconductor as a tube as a filament;

In the superconducting film, the Nb-Ti-based superconductor is used as a substrate, and the deposited material is MgB2;

MgB2 ultrafine core wire and film using Nb-Ti-based superconductor as a tubing and a substrate, characterized in that the technical features.

The superconducting wire and the film are preferably MgB2 ultrafine core wire and film using a Nb-Ti-based superconductor as a tubing and a substrate, characterized in that it further comprises a copper alloy shielding metal.

And the superconducting wire and the film further include a barrier layer such as Nb between the sealing metal and the Nb-Ti superconductor and between the Nb-Ti superconductor and MgB2. It is preferable to be a MgB 2 ultrafine core wire and a film using the as a tube and a substrate.

Favorable effect

Using the Nb-Ti-based superconductor already commercialized according to the present invention as a tubing and a substrate, the superconductivity of NbTi + MgB2 appears at 9 K or less, the critical temperature of the Nb-Ti-based superconductor, and from 9 K to 39 K. MgB2 superconducting wires and films using Nb-Ti-based superconductors, which are MgB2 superconductors, are used for tubing and substrates.

Best Mode for Carrying Out the Invention

Hereinafter, the present invention will be described with reference to the accompanying drawings.

MgB2 ultrafine core wire using Nb-Ti superconductor as tubing;

1 to 3 are cross-sectional structural diagrams of MgB2 ultrafine core wires using a Nb-Ti-based superconductor as a tubing according to the present invention.

As shown in the figure, the present invention is composed of a superconducting Nb-Ti-based tubing 200, an MgB2 filament 100, and a copper alloy shielding metal 300, and also the shielding metal 300. ) May further include a barrier layer 400, such as Nb, between the tube 200 and the tube 200 and the MgB 2 filament 100.

As shown in FIG. 4, the superconducting wire generally includes a tubing 200 covering the superconducting filament 100 and the superconducting filament 100 and a shielding metal 300 covering the outer shape of the conducting wire.

In the present invention, the superconducting filament 100 is composed of MgB2, the tub 200 is composed of Nb-Ti-based superconductor, and its shielding metal 300 is composed of copper alloy.

The MgB2 is known to be 39K, the largest superconducting critical temperature of the non-oxide superconductor.

In addition, Nb-Ti is also a well-known superconducting metal having a critical temperature of about 9K. As a drawing process for making Nb-Ti-based superconducting wires is widely known and developed in the related art, Nb-Ti-based superconducting is generally used. Lines are widely used.

The present invention uses the Nb-Ti-based superconductor, which was used as a conventional superconducting filament, as the tub 200, and the filament 100 charged therein is referred to as MgB2.

At this time, the MgB2 charged is composed of MgB2 powder (powder), Mg + B powder (powder), MgB2 + X powder (powder), Mg + B + X powder (powder), etc.

X is an element to increase the flux pinning effect or reduce the porosity of MgB2.

Accordingly, the drawing process for making superconducting wires can be used as it is, the Nb-Ti-based superconducting ultra fine core wire method, which is widely known and developed in the related art, and the critical temperature of the produced superconducting wires can be raised to 39K. .

Meanwhile, the superconducting wire of the present invention may be formed between the copper alloy shielding metal 300 and the tub 200 as shown in FIG. 2 or as shown in FIG. 3. It is characterized in that it further comprises a barrier layer (400-a, 400-b) such as Nb between the 200.

MgB2 superconducting film using Nb-Ti based superconductor as substrate;

4 to 9 are cross-sectional structural diagrams of MgB2 superconducting films using the Nb-Ti-based superconductor according to the present invention.

As shown in the figure, the present invention is largely composed of an Nb-Ti-based superconductor substrate, an MgB2 electrodeposition material, a shielding material, and the like, and between the shielding material and the substrate or between the substrate and the electrodeposition material MgB2. It may further comprise a barrier layer such as Nb.

As shown in FIG. 8, a superconducting film is generally composed of a superconducting material electrodeposited with a substrate and a buffer layer for reducing the reactivity between the substrate and the superconducting material and increasing alignment.

In the present invention, the deposited superconducting material is made of MgB2, the substrate is made of Nb-Ti-based superconductor, and the buffer layer is made of YSZ, Al2O3, or the like.

The present invention uses a Nb-Ti based superconductor, which was used as a filament in a conventional superconducting line, as a substrate, and sets the superconductor deposited thereon as MgB2.

The deposited MgB2 is composed of one or two of MgB2, B, Mg + B, MgB2 + X, Mg + B + X, where X is flux pinning effect such as Nb, Ta, Ti, Fe, and W. To increase or decrease the porosity of MgB2.

Deposition techniques include all deposition techniques such as Pulse Laser Deposition (PLD), Electro Deposition (ED), Chemical Vapor Deposition (CVD), Electro-Phoretic Deposition (EPD), MB, IBAD, and sol gel. Is available.

The superconducting MgB2 film made as described above is finally subjected to a superconducting MgB2 film by performing heat treatment under an Mg atmosphere or an inert gas atmosphere at a temperature between 600 and 950 ° C.

The superconducting film may further include a barrier layer such as Nb between the shielding material and the substrate as shown in FIG. 9 or between the MgB2 and the substrate as shown in FIG. 7. have.

In addition, to improve the flux pinning effect and alignment of the MgB2, two or more buffer layer layers may be used, and point defects on the substrate or on the buffer layer layer may be used. Point defects and columnar defects can be formed to increase the flux pinning effect.

Embodiment for Invention

In the case of multicore;

There are many ways to make a microcore, but if only one of them is introduced,

First, holes in the rod-like Nb-Ti-based superconductor are dug in the longitudinal direction, and therein, a powder sufficiently mixed in a ratio of Mg and B in a molar ratio of 1: 2 is charged. This drawing is repeated to produce a long joule-shaped wire. Cut long joists of equal length and pile them together. It is then placed in a shielding metal, which is a copper alloy, to continue drawing again to the desired dimensions.

Finally, heat treatment is performed at 600-950 ° C volatile gas atmosphere for one to two hours. This is the MgB2 superconducting ultrafine core wire using the final NbTi superconductor shown in FIG. 1 as a tube.

For film;

First, the NbTi superconducting plate is processed to be suitable for use as a substrate. On top of that, electrodeposit the boron using the various electrodeposition techniques described above. Electrodeposit magnesium on boron so that the electrodeposited boron and molar ratio is 2: 1. In order to prevent reactivity of the copper shielding metal with MgB 2 and NbTi, Nb is electrodeposited, and finally, the copper shielding metal is electrodeposited on the entire film. When the heat treatment is performed for one to two hours in a 600-950oC inert gas atmosphere, it becomes an MgB 2 superconducting film using the NbTi superconductor shown in FIG. 10 as a substrate.

Claims (9)

In superconductivity and film, Tubing of Nb-Ti-based superconductors; MgB2 charged into the tubule as a filament; MgB2 ultra fine core wire using a Nb-Ti-based superconductor as a tubing, characterized in that the configuration. In the superconducting film, Nb-Ti based superconductor as substrate; A superconductor deposited on the substrate as MgB2; MgB2 superconducting film using a Nb-Ti-based superconductor as a substrate, characterized in that the configuration. The Nb-Ti according to claim 1 or 2, wherein the MgB2 is MgB2 powder, Mg + B powder, MgB2 + X powder, Mg + B + X powder, or the like. MgB2 superconducting film using MgB2 ultrafine core wire and Nb-Ti-based superconductor as substrates. X is an element for increasing flux pinning effects of Fe, Ti, Nb, V, W, or reducing porosity of MgB2. According to claim 1, 2, 3 and the superconducting wire and the film is MgB2 ultra fine core and Nb-Ti-based superconductor using a Nb-Ti-based superconductor as a tubing, characterized in that further comprises a copper alloy shielding (shielding) metal MgB2 superconducting film using the substrate. 5. The MgB2 using Nb-Ti-based superconductor as a tubing according to claim 4, wherein the superconducting wire and the film further comprise a barrier layer such as Nb between the copper alloy shielding metal and the tubing. MgB2 superconducting film using ultra fine core wire and Nb-Ti based superconductor as substrate. The Nb-Ti-based superconductor according to claim 1, 2, 3, 4, or 5, wherein the superconducting wire and the film further comprise a barrier layer such as Nb between the MgB2 and Nb-Ti. MgB2 superconducting film using MgB2 ultra fine core wire using Bro and Nb-Ti type superconductor as substrate. The superconducting wire and the film of claim 5, wherein the superconducting wire and the film further include a barrier layer such as Nb between the copper alloy shielding metal and the tube, and a barrier layer such as Nb between MgB2 and Nb-Ti. MgB2 superconducting film using an Nb-Ti-based superconductor as a tubule and a Ng-Ti-based superconductor as a substrate. The superconducting film of claim 2, 3, 4, 5, 6, or 7, wherein the superconducting film comprises one or more layers of a buffer layer between the MgB 2 and the NbTi substrate. MgB2 superconducting film using a system superconductor as a substrate. MgB2 ultrafine using Nb-Ti-based superconductors as tubing, characterized in that columnar defects were formed by scanning neutrons in the first, second, third, fourth, fifth, sixth, seventh and eighth terms. MgB2 superconducting film using core wire and Nb-Ti-based superconductor as substrate.

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