JPH02265116A - Manufacture of superconductive material - Google Patents

Abstract

PURPOSE:To obtain a linear superconductive material of NbC group compound at a low cost by depositing a black carbon coat on the surface of a Nb substrate by sputtering, etc., to give an element circuit, etc., fine process by a precise control-available laser in an in active atmosphere. CONSTITUTION:A carbon layer 2 of thickness 1mum or more is deposited on a Nb substrate 1 by a ring technique to prepare a composite structure 100. Next, the composite structure 100 is fixed on an X-Y table 110 in a reaction room under an argon atmosphere, e.g. to irradiate a YAG laser 120 while moving the X-Y table to an (X) direction or a (Y) direction at a preset speed in either cases. As a result, a preset width of simulated pattern 3 of a circuit for NbC compound is created on the surface of the composite structure 100. It is thus possible to obtain a linear NbC group compound superconductive material of inexpensiveness and excellence.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to N1) C blocking compound superconducting materials, particularly linear N
1) A method for producing a C-blocking compound superconducting material.

[Conventional technology]

Among compounds that exhibit superconductivity, only N1)3SII and V3Ga, which have an A15 type crystal structure, have been put into practical use. However, there are many crystal structure monsters called types that have excellent properties, and among them, the raw materials for N1) C-based compounds are relatively cheap, so it is important to establish an excellent manufacturing method. It is expected that practical application will progress.

However, conventionally, linear N1)C monomonocarbon superconducting materials have been manufactured using metallurgical methods, which have not allowed for the precision and fine control necessary for manufacturing electronic devices. In this specification, 'NbC-based gold compound is NbC-based gold compound.
1) In addition to C, a part of Nb in N1) C is replaced with another metal (M)
Also includes (Nb, M)C substituted with .

Although it is possible to conduct current through a superconductor with zero electrical resistance, there are limits to this in terms of temperature, magnetic field, and current density.
If this value is exceeded, electrical resistance appears.

Its limits are the superconducting critical temperature (Tc) and the upper critical magnetic field (H
c2) is called critical current density (Jc). Nb
For 3S n and V3Ga, Tc is the absolute temperature of 18.
0 degrees and 15.1 degrees, Hc2 is 21.5 Tesla and 22. O tesla, used in superconducting application equipment such as nuclear fusion reactors and particle accelerators that require strong magnetic fields. On the other hand, Tc and HO2 of NbC are respectively 11 and OK
and about 7 Tesla, and can be applied to superconducting power transmission, small AC superconducting equipment, superconducting electronics, etc. that do not require strong magnetic fields. It is desired to develop a manufacturing method that allows on-site, precise, and fine control.

Generally, Jc increases as TO and Hc2 become higher or as the microstructure becomes finer. To increase TO and HO2, the elemental composition ratio (Nb:5n-3:1 of Nb3Sn,
V of V3Ga: Ga=3:1, N1) N of C
In the case of b:C1:1 ratio, (Nb, M)C, (Nll
, M): C-1: 1) is achieved accurately, and the crystal structure is preferably cubic (a structure in which the lattice constants of the y-axes, y-axes, and y-axes are equal).

N 1) In 3S n and V, Ga,! When a complex made of copper-tin alloy niobium or copper-gallium alloy and vanadium is heat-treated, the target N b 3 S 11 or V3Ga is formed at the interface between copper-tin alloy and niobium or copper-gallium alloy and vanadium. is generated.

Conventionally, N1) C-based superconducting linear materials have been typically produced as follows. That is, a ternary niobium-nickel-carbon alloy is melted using niobium and a nickel-carbon alloy as raw materials. This ternary alloy can be processed hot in the air, and when processed into a tape, Nb in nickel 7 trix
A superconducting material in which C particles are connected and dispersed in a linear manner is obtained. Alternatively, if a niobium-nickel alloy is cold-worked into a tape shape, placed in carbon powder, and heated in the atmosphere, a carburizing reaction occurs, and N forms at the grain boundaries in the nickel-niobium alloy.
1) A network of C is formed. However, N1)C
In this case, such metallurgical methods do not provide a precise 1:1 ratio and cubic crystal structure. In addition, in order to achieve a ratio of 1:1, heat treatment at a high temperature is required, which causes problems such as coarsening of the microstructure and reduction of Jc.

[Problem to be solved by the invention]

The present invention is an inexpensive N1) C that can be expected to be applied to superconducting power transmission, small AC superconducting equipment, superconducting electronics, etc.
The purpose of the present invention is to provide a method for manufacturing superconducting linear materials of basic compounds with precise and fine control.

[Means to solve the problem]

As a result of intensive research to overcome the problem described in 1.
By combining technology based on lasers with relatively low output energy that can be precisely controlled and thin film production technology such as sputtering, and applying it to the production of superconducting materials of N1) C-based compounds, the following effects will occur. I investigated.

■ If a black carbon film is attached to the surface of the substrate to be irradiated with the laser using a thin film generation technique such as sputtering, the laser energy can be efficiently absorbed.
The high temperature required for C production can be obtained.

■ By using a laser that can be precisely controlled, the laser output, laser beam diameter, substrate movement speed, etc. can be adjusted.
It is possible to microfabricate element circuits and the like.

(2) The use of a laser enables rapid heating to the formation temperature l\ and rapid cooling from the formation temperature, making it possible to obtain a cubic N1)C compound with an accurate composition ratio of Nb:C=1:1.

The present invention was completed based on these findings.

That is, the gist of the present invention is to form a composite by depositing a carbon layer with a thickness of 1 μIn or more on at least a region of a substrate containing Nb or a Nb-based alloy on the surface; and in an inert atmosphere, while irradiating the surface of the carbon layer with a laser beam, the laser beam and the composite are relatively moved along the surface of the carbon layer, thereby controlling the area of the substrate. to N1
) A method for producing a superconducting material, comprising the step of forming a C-based superconducting compound in a linear form along a substrate surface.

In the present invention, the carbon layer deposited on the region containing Nb or Nl>based alloy on the surface of the substrate is irradiated with a laser to efficiently absorb energy, thereby forming a bond between this region and the carbon layer. An extremely local and rapid diffusion reaction is caused to form an NbC-based gold compound superconducting material.

N1) As a substrate for generating a C-based compound, for wire rods, use a malleable and ductile Nb simple metal, an N+)-based alloy with other elements added to it, or Hastelloy, Inconel, stainless steel, titanium alloy, etc. Corrosion resistance and heat resistance A material that does not have Nb or Nb base alloy deposited is suitable. The above Nb-based alloys include Ti, Ta, V, W, Mo, and R.
It is desirable that a total of 15 atomic % or less of one or more elements selected from the group consisting of e, Os, Hf, and Zr be incorporated, with the remainder consisting of Nb and inevitable impurities. The alloying element content is within a range that allows plastic working of Nb into a wire without deteriorating its workability and improves superconducting properties.

In addition to these metal substrates for devices, Nb or Nb-based alloys are deposited on inorganic compounds such as alumina, zirconia, sapphire, boron nitride, and silicon nitride as substrates for generating N1) C-based compounds. What you did is appropriate.

The region containing Nb or a Nb-based alloy on the surface of the substrate includes a layer of Nb having a thickness of 500 μIll or less, and Ti.

Ta, V, W, R,e, Os, H
It is preferable that layers of one or more elements selected from the group consisting of Zr, f, and Zr, each having a thickness of 20 μIll or less, are alternately and sequentially laminated. The growth rate of the NbC-based gold compound can be increased by alternately stacking the Nb layer and the metal layer to the above thickness on the substrate using a thin film formation technique such as sputtering.

The upper limit of the thickness of the Nb layer and other element layers in the stack is set so that sufficient diffusion occurs between these layers during laser irradiation.
This is the limit for achieving a ratio of b:C=1:1, obtaining high Tc and Hc2 as a precise cubic crystal structure by rapid heating and rapid cooling, and forming a fine microstructure to obtain a large Jc. Other elements selected are N1
) It increases the production rate of C group compounds.

For details, refer to N
A carbon layer is deposited onto the region comprising the Nb- or Nb-based alloy by conventional methods such as sputtering to form a composite. The carbon layer efficiently absorbs laser energy and at the same time acts as a carbon source for the generated NbC-based gold compound.

The thickness of the carbon layer needs to be 1 μm or more. This is to compensate for the loss so that even if carbon is lost due to reaction with oxygen remaining in the atmosphere during laser irradiation, sufficient carbon can be supplied.

*The surface of the carbon layer is irradiated with a laser beam while the above composite and the laser beam are moved relative to each other along the surface of the carbon layer in an inert atmosphere.

As the inert atmosphere, a vacuum of about 0.1 atm or less or an atmosphere to which an inert gas is added at a partial pressure of about 0.1 to 3 atm can be used.

As the inert gas, argon gas is advantageous in practice because it is inexpensive. By relatively moving the composite and the laser beam along the carbon layer surface, the laser beam irradiation spot on the carbon layer surface moves linearly. This relative movement can be easily achieved by fixing one of the complex and the laser beam and moving the other, depending on the equipment used. Of course, if it is necessary to form a superconducting material in a complicated pattern, both the composite and the laser beam can be moved and the laser beam irradiation point can be placed on the surface of the carbon layer with a trajectory along the above pattern. may be moved. The energy of the laser beam efficiently absorbed by the carbon layer is transmitted to the Nb or Nb-based alloy (layer) below the irradiation point, and to other metals if laminated with them. By heating the layers rapidly and locally, diffusion between the layers occurs rapidly. As a result, N1) C-based compound superconducting material is generated on the substrate along the locus of the laser irradiation point. The area added by the laser irradiation point is rapidly cooled by heat transfer to the surrounding area immediately after passing. Therefore, since unnecessary diffusion does not occur, the achieved Nb:C (or (Nb, M):C) ratio is accurately maintained up to room temperature, and coarsening of the crystal structure is also prevented. This results in excellent superconducting properties (Tc,
Linear NlIClIC with Hc2, Jc)
A substance is a compound.

In the following, the invention will be explained in more detail by means of examples with reference to the accompanying drawings.

Example 1 According to the method of the present invention, a NbC-based gold compound superconducting material was fabricated as a pseudo pattern of an element circuit on an Nb substrate.

As shown in FIG. 1(a), a Nb substrate 1 (thickness 0.1
A composite body 100 was prepared by depositing a carbon layer 2 with a thickness of 10 μm on the carbon layer 2 (mm x width 30 I x length 50 mm) using a normal sputtering method.

Next, as shown in FIG. 1(d), this composite 100
Fix it on an XY table pull 10 in a reaction chamber with an argon atmosphere of 1 atm. Move the X-Y table in the X direction or Y direction.
A 40 watt YAG laser (beam diameter 50 μm) was
) Do not irradiate 120. As a result, as shown in FIGS. 1(b) and 1(c), a simulated circuit pattern 3 of the N)+C compound with a width of approximately 50 μ'n was generated on the surface of the composite 100. Its superconducting properties are Tc =10.1K,
Hc2=7T, Jc=1.5X 105A/
c+n2 (OT, 4.2K). In this way, it is possible to fabricate a pattern of a superconducting compound circuit, which is necessary for applying NbC compounds to superconducting elements and the like.

Example 2 According to the present invention, a tape-shaped N1)C-based compound superconducting material was produced on a substrate having a layer of N1)-based alloy deposited on a Hastelloy substrate.

As shown in FIG.
A tape-shaped composite 200 was prepared by depositing a 5 μm thick carbon layer 23 by sputtering on the substrates (21, 22) on which a 5 μm thick Nb-5at%Ta alloy layer 22 was deposited by sputtering.

Next, as shown in FIG. 2(d), this composite 200 was fixed around the edge of a rotating wheel 210 in a reaction chamber with an argon atmosphere of 0.5 atmospheres. While winding with the wheel 211, rotating the wheel 210 at 1 m+n/sec,
70 Watt YAG laser (beam diameter 100μm)
)220 was irradiated. As a result, as shown in FIGS. 2(b) and (C), a (Nb, Ta)C compound 24 having a width of approximately 100 μI11 was formed on the surface of the composite 200 (the length of the composite 200 was approximately 10 m). Figure 2(e)
The state of production is shown in an Auger photograph (magnification: 200). Its superconducting property is Tc = 10.3I(, Hc2
=6.3T, Jc=4X106A/c
m2 (OT, 4.2K), and is promising as a wire material for superconducting power transmission due to the rapid heating and cooling effects of laser irradiation.
It showed extremely excellent Jc characteristics. Since the present invention is a method that can be easily extended and scaled up, it has become possible to produce a N1) C compound tape wire with excellent properties.

〔Effect of the invention〕

As explained above, according to the present invention, a linear NbC-based gold compound superconducting material can be used.

Furthermore, the following technical and economic effects can be expected by the present invention.

■ Since laser energy is absorbed extremely efficiently by the carbon layer on the surface, there is no need for expensive, large-capacity carbon dioxide lasers that consume large amounts of power, and small-capacity YA lasers are not required.
G laser etc. can be used.

- Since a YAG laser can be used, relatively inexpensive and non-toxic quartz glass can be used for the laser introduction window.

■ By using a small-capacity laser that is easy to control, we can continuously deposit an NbC-based gold compound conductive phase on a substrate with a precise shape and position that can be applied not only to wires but also to devices. can be generated.

■ Since it is generated under rapid heating and cooling conditions, it has a fine crystal structure and a large Jc can be obtained.

■ Since it is a combination of laser and thin film technology, there is a degree of freedom in selecting the reaction atmosphere, making it simple and easy to scale up.

[Brief explanation of drawings]

FIGS. 1(a) to 1(d) are diagrams showing an example of manufacturing an N1) C-based compound superconducting material using an Nb substrate according to the present invention, in which (a> is a composite before laser irradiation) (b) and (c) are a plan view and a side view, respectively, showing the composite after laser irradiation, and (d) is a perspective view showing the laser irradiating the composite fixed on a table. 2(a) to 2(e) show an example of manufacturing a N1) C-based compound superconducting material using a substrate having a layer of Nb-based alloy deposited on a Hastelloy substrate according to the present invention. In the figure, (a> is a cross-sectional view of the composite before laser irradiation, (b) and (C) are respectively a plan view and a cross-sectional view of the composite after laser irradiation, and (, I) is a cross-sectional view of the composite before laser irradiation. A side view showing the rolled tape-shaped composite being wound around the other wheel while being irradiated with a laser, and (e) is the result of cutting a part of the composite surface shown in (b) into EPM eighths. It is a metal structure photograph showing 1... N l) substrate, 2... carbon layer, 3...
・NbC-based gold compound superconducting material 00...Composite, 21...Hastelloy substrate, 22-Nb-5at%Ta alloy layer, 23...
Carbon layer, 24...N1) C-based compound superconducting material, ZOO...
complex. O/

Claims (1)

[Claims] 1. A step of producing a composite by depositing a carbon layer with a thickness of 1 μm or more on a region of a substrate having at least a region containing Nb or a Nb-based alloy on the surface; In an active atmosphere, while irradiating the surface of the carbon layer with a laser beam, the laser beam and the composite are moved relative to each other along the surface of the carbon layer, thereby injecting NbC into the region of the substrate. 1. A method for producing a superconducting material, comprising the step of generating a base superconducting compound in a linear form along a substrate surface. 2. The method according to claim 1, wherein the substrate is made of Nb or a Nb-based alloy. 3. The method of claim 1, wherein the substrate is fabricated by depositing a layer containing Nb or a Nb-based alloy on a substrate of a corrosion-resistant and heat-resistant alloy to form the region. 4. The corrosion-resistant and heat-resistant alloy is Hastelloy, Inconel,
4. A method according to claim 3, characterized in that the material is selected from the group consisting of stainless steel and titanium alloys. 5. The substrate has Nb or Nb on an inorganic compound base.
2. The method of claim 1, wherein the region is formed by depositing a layer comprising a base alloy. 6. The method of claim 5, wherein the inorganic compound is selected from the group consisting of alumina, zirconia, sapphire, boron nitride and silicon nitride. 7. The Nb-based alloy is Ti, Ta, V, W, Mo, R
Claims 1 to 6, characterized in that it contains a total of 15 atomic % or less of one or more elements selected from the group consisting of e, Os, Hf, and Zr, with the remainder consisting of Nb and inevitable impurities. The method according to any one of the above. 8. The region of the substrate is made of Nb with a thickness of 500 μm or less
and layers each having a thickness of 20 μm or less of one or more elements selected from the group consisting of Ti, Ta, V, W, Re, Os, Hf, and Zr are sequentially stacked. 8. A method according to any one of claims 1 to 7, characterized in that: