JPH0653037A - Oxide superconductor current lead - Google Patents

Abstract

PURPOSE:To reduce heat amount permeating from a metal sheath oxide superconductor and reinforce the strength of oxide superconductive bulk conductor, by arranging a ceramic body for reinforcement in the length direction of the oxide superconductor. CONSTITUTION:In a current lead 11 wherein a single layer ceramics body for reinforcement is arranged on an oxide superconductor, a rod type ceramics body 13 for reinforcement is made to engage with the inside of a pipe type oxide superconductor 12. In a current lead 21, a penetrating hole 24 for a refrigerant path is formed at the center of a ceramics body 23 for reinforcement in a pipe type oxide superconductor 22. In a multilayered current lead 31, oxide superconductors 32, 34 and 36 are made to concentrically alternately engage with ceramics bodies 33, 35. A ceramics body 37 is made to engage with the center. Thereby the penetrating heat amount into the current lead is reduced, large strength of the lead is obtained, apparatus stability is realized, and the lead is prevented from being bent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a magnet, a coil,
The present invention relates to an oxide superconducting current lead for supplying electric power to a power application conductor or the like from outside.

[0002]

2. Description of the Prior Art Oxide superconductors are made into wire rods and conductors,
Attempts have been made to use them as magnets, coils and various power application conductors. In particular, so-called oxide high-temperature superconductors represented by yttrium-based, bismuth-based, and thallium-based materials are known as preferable materials for power application conductors because they have a critical temperature exceeding liquid nitrogen temperature. Further, in addition to the long wire as described above, application to a current limiter or a current lead is also considered as a conductor with a short and large current capacity.

The most common method for producing a long wire is to fill the powder of these oxide superconductors in a metal sheath material such as silver and reduce the diameter of the so-called powder-in-tube. The law is known. By this method, a single-core round wire or tape, a multi-core or multi-layer round wire or tape has already been produced, and trial manufacture of conductors for coils and cables has begun.

However, when the method of producing a long wire is applied to the production of a short current lead, there is a problem that the high thermal conductivity of the coating metal has an adverse effect. That is,
The invasion of heat transmitted through the metal part impairs the stability of the device connected to the current lead and increases the evaporation amount of liquid helium, which is a cooling medium of the device.

Conventionally, a copper conductor has been used as a current lead, but in this case, the amount of penetration and Joule heat is 1
Since it was ~ 1.2 W / kA, the oxide superconducting current lead of the metal sheath was 0.9-1.0 W in comparison with this.
The amount of heat entering can be reduced up to / kA.

[0006]

In the conventional current lead using the copper conductor, the total amount of intrusion and generated heat is 1 W or more per 1 kA. Further, in the current lead using the metal sheath oxide superconductor, although the amount of intruding heat is slightly reduced, there is not much difference from the case of using the copper conductor, and the merit of the superconducting current lead cannot be obtained so much.

On the other hand, it is possible to use an oxide superconducting bulk conductor for the current lead in which the amount of heat entering is reduced by not providing a metal sheath, but in this case, the oxide superconducting conductor is fragile and therefore breaks during use. There was a risk of

Therefore, an object of the present invention is to provide an oxide superconductor current lead in which the amount of heat entering the metal superconducting oxide superconductor is reduced and the strength of the oxide superconducting bulk conductor is reinforced.

[0009]

In order to solve the above-mentioned problems, the present invention comprises an oxide superconductor and a reinforcing ceramic body arranged in the length direction of the oxide superconductor. An oxide superconducting current lead is provided.

The present invention also provides an oxide superconducting current flow lead having a through hole for a refrigerant passage in the length direction of a composite composed of an oxide superconductor and a reinforcing ceramics body.

The reinforcing ceramic body used for the oxide superconducting current lead of the present invention may have either a single-core structure or a multi-core structure. In the case of the single core structure, the structure may be a structure in which the reinforcing ceramics body is arranged in a single layer, or a structure in which the oxide superconductor and the reinforcing ceramics body are arranged in multiple layers.

FIG. 1A shows the structure of a current lead in which a reinforcing ceramic body is arranged in a single layer on an oxide superconductor. The current lead 11 is a pipe-shaped oxide superconductor 12
This is a structure in which a rod-shaped reinforcing ceramics body 13 is fitted inside. In the case of this structure, it is possible to provide a through hole for the refrigerant passage, and the current lead of this structure is shown in FIG.
It shows in (b). The current lead 21 has a structure in which a through hole 24 for a refrigerant passage is provided at the center of a rod-shaped reinforcing ceramic body 23 fitted inside a pipe-shaped oxide superconductor 22.

An example of a current lead having a structure in which an oxide superconductor and a reinforcing ceramic body are arranged in multiple layers is shown in FIGS. 1 (c) and 2 (a). The current lead 31 shown in FIG.
Is a pipe-shaped oxide superconductor 32, 34 and 36,
This is a structure in which the pipe-shaped reinforcing ceramics bodies 33 and 35 are concentrically alternately and sequentially combined, and a rod-shaped reinforcing ceramics body 37 is fitted in the center. Figure 2
The current lead 41 shown in (a) has a structure in which an oxide superconductor 42 and a reinforcing ceramics body 43 are spirally arranged. Further, the current leads 31 and 41 may have a structure in which a through hole for the refrigerant passage is provided, and the current leads of this structure are shown in FIGS. 2 (b) and 2 (c). Figure 2 (b)
The current lead 51 shown in (1) has a structure in which the rod-shaped ceramic body 37 of the current lead 31 is processed into a pipe shape to provide a through hole 58 for the refrigerant passage. Also,
The current lead 61 shown in FIG. 2C has a structure in which a through hole 64 for a refrigerant passage is provided at the center of a spirally arranged oxide superconductor 62 and a reinforcing ceramic body 63.

In the above-described single-core current lead, in the case of the single-layer structure, the oxide superconductor is arranged outside the reinforcing ceramic body, and also in the case of the multi-layer structure, the outermost layer is the oxide. It is preferably a superconductor.

An example of a current lead having a multi-core structure is shown in FIGS. 3 and 4. The current lead 71 shown in FIG. 3 (a) has a structure in which an oxide superconductor 72 is used as a matrix and rod-shaped reinforcing ceramics bodies 73 are arranged in the length direction thereof. 81 is a structure in which the reinforcing ceramic body 82 is used as a matrix and rod-shaped oxide superconductors 83 are similarly arranged in the length direction thereof. As described above, any material of the oxide superconductor or the reinforcing ceramics body can be used as the matrix, but from the viewpoint of cooling efficiency of the oxide superconducting lead, the oxide superconductor is exposed on the outer surface. Is desirable. Furthermore, the oxide superconductor and the reinforcing ceramics body must be continuous in the length direction of the conductor.

It is also possible to make a current lead having a plurality of through holes for a refrigerant passage by making the diameter of the through holes smaller and increasing the number of the holes. FIG. 4 shows an example of the current lead of this structure. The current lead 10 shown in FIG.
1 is a structure in which seven rod-shaped reinforcing ceramic bodies 103 are fitted with the oxide superconductor 102 as a matrix.
This is a structure in which one refrigerant passage through hole 104 is provided. On the other hand, the current lead 111 shown in FIG. 4B has a structure in which a reinforcing ceramic body 112 is used in a matrix, rod-shaped oxide superconductors 113 are fitted, and three through holes 114 for refrigerant passages are similarly provided. Is.

The various structures described above can be appropriately selected according to the desired strength and the like.

The proportion of the reinforcing ceramic body contained in the current lead of the present invention is preferably 5 to 99%, more preferably 20 to 90% in terms of cross-sectional area with respect to the oxide superconductor. This is because if it is less than 5%, the desired strength cannot be obtained, and if it exceeds 99%, the properties of the conductor deteriorate.

It is preferable that the complex oxide superconducting current lead having these structures further has one or more through holes as a coolant passage in the length direction thereof.

The proportion of the cross-sectional area of the through hole is preferably about 2 to 90% of the cross-sectional area of the current lead, more preferably 10%.
~ 85%. This is because if it is less than 2%, sufficient cooling efficiency cannot be obtained, and if it exceeds 90%, the characteristics of the current lead are deteriorated.

As the oxide superconductor used in the present invention,
So-called high temperature superconductors with high critical temperature are suitable,
Lanthanum-based, yttrium-based (rare earth-based), bismuth-based, thallium-based, lead-based, or the like can be used depending on the structure of the current lead, the desired capacity, and the like.

The raw materials for these high-temperature superconductors are Y
₂ O ₃ , BaCO ₃ , CuO, Bi ₂ O ₃ , PbO, S
A plurality of oxide powders such as rCO ₃ and CaCO ₃ can be appropriately selected and used.

The reinforcing ceramics that can be used in the present invention include most oxide-based structural ceramics such as alumina-based, zirconia-based, silica-based, and magnesia-based ceramics, and are characterized by high strength and heat resistance. Certain nitride-based structural ceramics such as silicon nitride or carbide-based structural ceramics such as silicon carbide can also be applied. Zirconia-based ceramics are particularly preferable. Furthermore, machinable ceramics that are a composite of various oxide-based and non-oxide-based ceramics that have been often used in recent years can also be applied.

A method of manufacturing the above current lead will be described below.

The raw material oxide powders are mixed at a predetermined ratio, calcined at a predetermined temperature and for a predetermined time, and then pulverized into a calcined powder. CIP molding into a rod shape or a pipe shape with a size.

An oxide superconductor is completed by subjecting the obtained molded body to heat treatment at a predetermined temperature and for a period of time.
If necessary, heating and heat treatment can be further performed. In the case of producing a current lead having a multi-core structure, after forming the oxide superconductor into a rod shape, a predetermined number of through holes having a predetermined diameter are provided.

As the reinforcing ceramic body, for example, yttria-stabilized zirconia (YSZ) is used, which is carved into a predetermined shape such as a rod shape or a pipe shape, and fitted into the above-mentioned oxide superconductor to obtain an electric current. You can get a lead.

In the case of a multi-core current lead having a reinforcing ceramic body as a matrix, a rod-shaped ceramic body is provided with a through hole having a predetermined diameter, and an oxide superconductor formed to fit the hole. It can be manufactured by fitting.

Further, in the case of a current lead having a structure in which an oxide superconductor and a reinforcing ceramic body are spirally arranged,
Each can be manufactured by mixing predetermined raw material powders, laminating them into a two-layered sheet, winding them so that the oxide superconductor is on the outside, and molding.

[0030]

In the oxide superconducting current lead of the present invention, a ceramic having a strength higher than that of the oxide superconductor and a thermal conductivity lower than that of the high-strength material such as metal is used. Are arranged continuously. Therefore, the strength of the oxide superconducting current lead can be increased without impairing the characteristics of the oxide superconducting current lead, that is, the amount of heat generated and the amount of heat entering can be reduced, and the practical characteristics can be improved.

Further, in the oxide superconducting current lead of the present invention, one or more through holes may be provided in the lengthwise direction as a refrigerant passage, which allows cooling without impairing the characteristics of the oxide superconducting lead. The efficiency can be increased.

[0032]

EXAMPLES Hereinafter, the present invention will be described more specifically by showing examples of the present invention.

(Example 1) Powders of Y ₂ O ₃ , BaCO ₃ and CuO were used as raw materials for an oxide superconductor,
These powders were blended and mixed so as to have a composition of YBa ₂ Cu ₃ O _7-x to prepare a mixed powder. The obtained mixed powder is calcined in the atmosphere at 850 ° C. for 6 hours, and then pulverized into a calcined powder, which is CIP molded to have an outer diameter of 10 mm and a wall thickness of 1
A pipe having a length of 200 mm and a length of 200 mm was produced. The obtained pipe is heat-treated in the atmosphere at 950 ° C for 10 hours and then at 2 ° C.
It was gradually cooled at a speed of about 1 / min to obtain an oxide superconductor.

A rod made of YSZ (yttria-stabilized zirconia) was used as the reinforcing ceramics, and it was carved into a length of 200 mm with a diameter suitable for the inner diameter of the superconductor and fitted into the superconductor pipe. The composite conductor 11 shown in FIG. 1A was obtained.

Two sets of current leads were produced by connecting the five composite conductors thus obtained to the tips of copper conductors.

Example 2 Powders of Bi ₂ O ₃ , PbO, SrCO ₃ , CaCO ₃ and CuO were used as raw materials for the oxide superconductor, and these powders were mixed at a molar ratio of Bi:
Pb: Sr: Ca: Cu = 1.6: 0.4: 2: 2: 3
And mixed in the same manner as in Example 1 to prepare a mixed powder. The obtained mixed powder is heated in the air at 800 ° C. and 50
Calcination under the condition of time, then crushing into calcination powder, C
IP molding and each outer diameter is 14mm, 10mm, 6
mm, wall thickness 1 mm, length 200 mm 3 pipes were produced. The obtained pipe was heat-treated in the atmosphere at 850 ° C. for 50 hours, further CIP was performed, and then heat-treated again under the same conditions to obtain three oxide superconducting pipes.

As the reinforcing ceramics, the same YSZ rods as in Example 1 were used, and the outer diameters were 12 mm and 8 m, respectively, so as to be combined with the above oxide superconducting pipe.
m, 4 mm, wall thickness 1 mm, length 200 mm 3 pipes
This was made. By alternately fitting the obtained ceramic pipes and the above oxide superconducting pipes one after another, as shown in FIG.
The composite conductor 51 shown in (b) was obtained.

A through hole 58 for a refrigerant passage having a diameter of 2 mm is formed at the center of the composite conductor 51.

Two sets of current leads were produced by connecting the three composite conductors thus obtained to the tips of copper conductors.

Example 3 The same powder as in Example 2 was used as the raw material for the oxide superconductor, and the mixed powder was mixed and mixed in the same molar ratio as the mixed powder in Example 2 to prepare a mixed powder.
The obtained mixed powder was calcined in the atmosphere at 800 ° C. for 50 hours, and then pulverized into a calcined powder, which was CIP molded to prepare a rod having an outer diameter of 10 mm and a length of 200 mm. The obtained molded body is heat-treated in the atmosphere at 850 ° C. for 50 hours,
After further performing CIP, heat treatment was performed again under the same conditions to obtain an oxide superconductor. Seven through holes having a diameter of 2 mm were provided in the length direction of the obtained rod-shaped oxide superconductor. One of the through holes was provided at the center, and the remaining six holes were provided so as to be concentric.

As the composite ceramics, the same YSZ rod as in Example 1 was used, and the outer diameter was 2 mm and 200 m so as to match the diameter of the hole provided in the oxide superconductor.
Machined to a length of m, excluding the center of the oxide superconductor 6
The composite conductor 91 shown in FIG. 3C was obtained by inserting the composite conductor 91 into the individual holes.

In the center of the completed multi-core type composite conductor 91, a 2 mm through hole 94 for the refrigerant passage is formed.

Five composite conductors thus obtained were connected to the tips of copper conductors to prepare two sets of current leads.

(Comparative Example 1) The same powder as in Example 1 was used, and the mixed powder mixed and mixed so as to have the same composition as in Example 1 was calcined, pulverized and calcined under the same conditions. Got the powder.
The obtained calcined powder is CIP-molded to have an outer diameter of 10 mm and a length of 2
A 00 mm rod was made. The obtained molded body was heat treated in the same manner as in Example 1 and then gradually cooled to obtain an oxide superconductor.

Five conductors consisting of only the oxide superconductor thus obtained were connected to the tips of the copper conductors to prepare two sets of current leads.

(Comparative Example 2) The same raw material powder as in Example 2 was used, and the mixed powder mixed and mixed so as to have the same molar ratio as in Example 2 was calcined and pulverized under the same conditions, A calcined powder was obtained. The obtained calcined powder was CIP-molded to produce a pipe having an outer diameter of 10 mm, an inner diameter of 8 mm, and a length of 200 mm. The obtained pipe was heat-treated in the same manner as in Example 2, further CIP-treated, and then heat-treated again to obtain an oxide superconductor.

Five conductors consisting of only the oxide superconductor thus obtained were connected to the tips of the copper conductors to prepare two sets of current leads.

(Comparative Example 3) Outer diameter 10 produced in Example 1
Two sets of current leads were prepared by using five copper rods having an outer diameter of 5 mm and a length of 200 mm instead of the mm composite oxide superconductor.

Each of the composite oxide superconducting current leads prepared in Examples 1 to 3 and Comparative Examples 1 to 3 was connected to an NbTi superconductor immersed in liquid helium, and a current of 1000 A was applied to measure the temperature and evaporate the helium. The heat of penetration was calculated from

The bending strength of the oxide superconductor portion of each of the composite oxide superconducting current leads produced in Examples 1 to 3 and Comparative Examples 1 and 2 was measured by JI using an Instron type tester.
Measured by a measuring method according to SR1601-1981,
The results are shown in Table 1 below together with the amount of heat of penetration.

[0051]

[Table 1] As is clear from Table 1, all of the current leads of the present invention (Examples 1 to 3) have an intrusion heat amount of 0.52 W / kA or less and a bending strength of 75.0 MPa or more.
On the other hand, in Comparative Examples 1 and 2, the intrusion heat amount is 0.52 W / kA or less, which is equivalent to that of the example, but the bending strength is only about 25% of that of the example. Further, it can be seen that in Comparative Example 3, the amount of heat entering is twice or more that of the current lead of the present invention.

[0052]

As described above in detail, the current lead of the present invention has a small amount of heat entering and a high strength.

Therefore, it is possible to maintain the stability of the device and avoid breakage during use.

[Brief description of drawings]

FIG. 1A is a diagram showing a structure of a current lead of Example 1. FIG. (B) The figure which shows the other structure of the current lead of this invention. (C) The figure which shows the other structure of the current lead of this invention.

FIG. 2A is a diagram showing another structure of the current lead of the present invention. (B) The figure which shows the structure of the current lead of Example 2. (C) The figure which shows the other structure of the current lead of this invention.

FIG. 3A is a diagram showing another structure of the current lead of the present invention. (B) The figure which shows the other structure of the current lead of this invention. (C) The figure which shows the structure of the current lead of Example 3.

FIG. 4A is a diagram showing another structure of the current lead of the present invention. (B) The figure which shows the other structure of the current lead of this invention.

[Explanation of symbols]

11 ... Current lead, 12 ... Oxide superconductor, 13 ... Reinforcing ceramic body 21 ... Current lead, 22 ... Oxide superconductor, 23 ... Reinforcing ceramic body 24 ... Refrigerant passage through hole, 31 ... Current lead, 32 ... oxide superconductor 33 ... reinforcing ceramic body, 34 ... oxide superconductor 35 ... reinforcing ceramic body, 36 ... oxide superconductor 37 ... reinforcing ceramic body, 41 ... current lead, 42
... Oxide superconductor 43 ... Reinforcing ceramics body, 51 ... Current lead, 52
... oxide superconductor 53 ... reinforcing ceramic body, 54 ... oxide superconductor 55 ... reinforcing ceramic body, 56 ... oxide superconductor 57 ... reinforcing ceramic body, 58 ... refrigerant passage through hole, 61 ... current lead 62 ... Oxide superconductor, 63 ... Reinforcing ceramic body 64 ... Refrigerant passage through hole, 71 ... Current lead, 72 ... Oxide superconductor 73 ... Reinforcing ceramic body, 81 ... Current lead 82 ... Reinforcing ceramic body, 83 ... Oxide superconductor,
91 ... Current lead 92 ... Oxide superconductor, 93 ... Reinforcing ceramics body 94 ... Refrigerant passage through hole, 101 ... Current lead, 102
... Oxide superconductor 103 ... Reinforcing ceramics body, 104 ... Refrigerant passage through hole 111 ... Current lead, 112 ... Reinforcing ceramic body 113 ... Oxide superconductor, 114 ... Refrigerant passage through hole.

Claims (2)

[Claims] 1. An oxide superconducting current lead comprising an oxide superconductor and a reinforcing ceramic body arranged in the length direction of the oxide superconductor. 2. The oxide superconducting current lead according to claim 1, which has a through hole for a refrigerant passage in a length direction.