JPH02103809A - low loss power electrical conductor - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] TECHNICAL FIELD This invention relates to low loss power electrical conductors.

[Conventional technology]

Superconducting materials have already been put into practical use in the form of superconducting magnets in high-energy particle accelerators, MRT-CT for medical diagnosis, physical property research equipment, and the like. The application fields of such superconducting materials are wide, and in the future, for example, superconducting materials will be used in generators, energy storage and conversion, linear motor cars, magnetic separation devices for resource recovery, nuclear fusion reactors, power transmission cables, and magnetic shielding materials. Furthermore, superconducting devices using the Josephson effect are expected to be applied to ultra-high-speed computers, infrared detectors, low-noise amplifiers, mixers, etc.

The magnitude of the industrial and social impact when these are fully put into practical use is immeasurable.

A typical superconducting material developed so far is Nb.
-Ti alloy, which is currently widely used as a wire for generating magnetic fields up to 9K. Tc of NbTi alloy
(critical temperature at which superconducting state exists) is 9.

Compound-based superconducting materials have been developed as superconducting materials with Tc' much higher than this Nb-Ti alloy, and currently Nb+Sn (Tc: 18 K) and V3
Ga (Tc: 15K) has been made into a wire rod and is in practical use. Furthermore, for Nb, Ge, a Tc of 23 has been obtained.

As described above, efforts have been made for many years to obtain superconducting materials with high Tc, but Tc23K is currently a major hurdle in conventional alloy-based and compound-based superconducting materials. That is, cooling superconducting materials with a Tc of 23 or less requires expensive liquid helium, which hinders the wide application of superconducting materials.

In 1986, Mr. Muller and his colleagues at the 18M Zurich Research Institute developed B.
Since the announcement that signs of superconductivity were observed in a-La-Cu-0-based composite oxides, competition to develop applications for oxide-based superconducting materials has accelerated. In other words, the Tc of superconducting materials in 1986 was around 40, but in the following year (1987)
As early as 2010, a Y-Ba-Cu-0 composite oxide superconducting material with a Tc exceeding 77K, which is the temperature of liquid nitrogen, was developed, and its Tc reached approximately 93K.

Furthermore, the development of superconducting materials has continued vigorously since then, and recently, the development of superconducting materials that exhibit superconducting phenomena at room temperature has been reported, although there are problems with stability and the like.

As mentioned above, with the discovery of a superconducting material that can be used at liquid nitrogen temperature (77 K), expectations for the practical application of superconducting materials in the above-mentioned application fields have been further increased.

Generally, Co or M is used as a conductor for electric wires.

As a means to reduce the power loss of an electric wire using Cu or M as a conductor, it is possible to increase the cross-sectional area of the electric wire, but this is not appropriate due to limitations in terms of economy and weight.

Moreover, as another means of reducing power loss, a method of cooling the conductor can be considered. Possible cooling means include water cooling, liquid nitrogen cooling, and the like.

Water cooling equipment is difficult to miniaturize and requires large-scale equipment. Moreover, the purpose of water cooling is not to heat the wires, and the cooling temperature is around room temperature. Liquid nitrogen (N2) is significantly more advantageous than liquid helium (He) in terms of cost. If a wire with Cu or M as a conductor is cooled with liquid nitrogen, the power loss will be reduced, but it will also reduce the power loss at about 17
Up to 10.

Therefore, in order to reduce power loss beyond the above-mentioned value, development of conductors and wire rods that apply the above-mentioned superconducting phenomenon are underway.

As conventional superconducting wires, techniques using chemical superconducting materials such as NbzSn and NbTi have been proposed.

This is a conductor made of several thousand ultra-thin wires of several tens of microns in which Nb3Sn is dispersed in a Cu matrix, which is then made into a wire rod.

However, since Tc of Nb3Sn is 18,
Since an expensive liquid 11e must be used for cooling, the cost is high, and it is not suitable for long-distance power transmission.

Next, the following superconducting wire using an oxide superconducting material with high Tc was proposed. This is a superconducting wire made by filling a silver sheath with oxide-based superconducting powder, then drawing the sheath filled with the powder, and then subjecting the resulting wire to heat treatment. .

According to this, it is possible to eliminate power loss by cooling with liquid nitrogen.

[Problem to be solved by the invention]

However, the above-mentioned conventional low-loss power wire has problems such as low bending strength when it is a bare wire, low cooling efficiency when the outer diameter metal is removed, and silver is expensive. be.

Therefore, an object of the present invention is to reduce power loss by Cu or Δ!
It is an object of the present invention to provide a low-loss electric conductor that can be manufactured by a relatively simple method and has a high cooling temperature, which is much less expensive than a single conductor and is advantageous in terms of cost.

[Means to solve the problem]

The present invention is characterized in that Cu or M is used as a matrix, and oxide-based superconducting material particles having a particle size in the range of 0.1 to 100 mμ are uniformly dispersed in the matrix at a volume percentage in the range of 30 to 80%. It is something that you have.

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is an enlarged sectional view showing one embodiment of the electrical conductor of the present invention.

As shown in FIG. 1, oxide-based superconducting material particles 2 are uniformly dispersed in a Cu matrix 1.

Matrix 1 is a good conductor and has low resistance.
It is preferable to use Cu or M, which allows the superconducting material particles to be uniformly dispersed.

Next, the oxide-based superconducting material to be dispersed, the particle size, and
The volume ratio will be described below.

Oxide-based superconducting material: As the oxide-based superconducting material, a Tc higher than 77, for example the B15rCaCuzOx system, should be used. The reason for this is that liquid nitrogen (N
This is because 2) is used. Liquid nitrogen (N2) temperature is 7
7, and although the temperature is higher than that of liquid helium, it is cheaper and advantageous in terms of cost.

Particle size of superconducting substance: The particle size of the superconducting substance is 0.1 to 100 mμ. If the particle size is less than 0.1 mμ, Tc and Jc may deteriorate due to reaction with the matrix. On the other hand, the particle size is 1
If it exceeds 00 mp, uniform mixing becomes difficult and superconducting performance deteriorates due to grain boundary effects.

Therefore, the particle size of the superconducting material should be limited to a range of 0.1 to 100 mp.

Volume ratio of superconducting material: The volume ratio of superconducting material to the matrix is 30 to 80%
shall be. When the volume fraction is less than 30%, the effect of lowering the resistance decreases and the amount of liquid nitrogen consumed becomes large. on the other hand,
If it exceeds 80%, the flexibility decreases and it becomes impossible to make it into a wire.

Therefore, the volume fraction of the superconducting material should be limited to a range of 30 to 80%.

[For production]

For example, a low-loss power electrical conductor of the present invention with a Cu matrix is cooled to 77 K with liquid nitrogen (N2),
When a current is applied, the resistance of the Cu matrix is about 1/10 of that at room temperature, and the superconducting material dispersed in the matrix becomes superconducting.

Therefore, the resistance of the conductor of the present invention is much lower than that of a conductor made of pure Cu.

The increase or decrease in the resistance of the conductor depends on the volume fraction of the superconducting material dispersed in the matrix, and the higher the volume fraction, the lower the resistance.

〔Example〕 Next, the present invention will be explained with reference to examples.

Cu powder and old 5rCaC with particle size 10mμ or 80mμ
u20. The powder was mixed and pressed into powder.

Next, the obtained compact was subjected to cold isostatic pressure treatment (CIP) (
2,000 atm), then warm wire drawing process and wire diameter IM
I got a lead wire.

A coil 3 obtained by coiling this conducting wire as shown in FIG. 2 was immersed in liquid nitrogen 5 filled in a container 4. Then, apply 20OA AC or DC to each coil, and conductor 1
The consumption rate of liquid nitrogen (N2) per m was measured, and the relationship with the volume fraction of the superconducting material is shown in Figure 3.

In Figure 3, A is the particle size of the superconducting material 80 U, the current is AC3011z, B is the particle size of the superconducting material 10 mμ, the current is AC 30 Hz, C is the particle size of the superconducting material 10 mμ,
Current indicates DC.

As shown in Figure 3, the volume fraction of the superconducting material is 30 to 80.
%, it can be seen that the consumption rate of liquid nitrogen (N2) is low.

(Effects of the Invention) Since the present invention is configured as described above, it produces the following useful effects.

(1) Power loss can be significantly reduced by cooling with liquid nitrogen.

(2) It can be applied to many uses such as electric wires, power transmission cables, and strong electromagnet windings.

(3) Cooling is performed using liquid nitrogen, which is advantageous in terms of cost.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view showing one embodiment of the present invention, and FIG.
The figure is a cross-sectional view showing a coil made of the conductor of this invention immersed in liquid nitrogen. Figure 3 shows the consumption rate of liquid nitrogen per meter of conductor and the volume fraction of superconducting material when a current of 20 OA is passed through the conductor. It is a graph showing the relationship between In the drawings...Cu. ...superconducting material particles, ...coil, ...container, 5...liquid nitrogen.

Claims (1)

[Claims] 1 Cu is used as a matrix, and in the matrix there are particles with a particle size of 0.
．． A low-loss power electrical conductor characterized in that oxide-based superconducting material particles having a size of 1 to 100 mμ are uniformly dispersed at a volume fraction of 30 to 80%. 2 Al is used as a matrix, and the particle size is 0 in the matrix.
．． A low-loss power electrical conductor characterized in that oxide-based superconducting material particles having a size of 1 to 100 mμ are uniformly dispersed at a volume fraction of 30 to 80%.