JP3333276B2 - Method of manufacturing flux jump type current limiting member - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a process for the preparation of an oxide high-temperature superconducting material flux jump-type superconducting fault current limiter device for a member utilizing.

[0002]

2. Description of the Related Art The application of superconductors to power equipment has been studied for conventional metallic superconducting materials even before oxide superconductors were discovered. In particular, as an effective application field of power superconducting equipment, there is a demand for the development of a fault current limiter (current limiter) which suppresses a short circuit current in the event of an accident and reduces the duty of a circuit breaker.

Conventionally, current limiting devices, rectifiers, and reactors have been proposed as current limiting devices using metallic superconducting materials. However, the metal-based superconductor has a low electric resistance value in a normal conducting state, and requires a certain length or more in order to increase the normal conducting resistance, so that a large-sized device has to be provided.
In addition, since it is necessary to use the liquid helium at a high operating cost, there is a problem that the apparatus becomes large and expensive due to heat insulation and the like, and has not been put to practical use.

Therefore, in recent years, a current limiter using an oxide superconductor which has a high electric resistance in a normal conducting state and can maintain a superconducting state with liquid nitrogen at low cost has been studied. In addition, recently, a combined induction / resistance current limiter (Japanese Patent Laid-Open No. 2-105402: Helmut Dersch) has been proposed which combines a cylindrical jacket formed of an iron core, an induction coil, and an oxide superconductor. Have been. This method has the potential to reduce the size of the overall system due to its relatively simple configuration. The basic principle of the combined induction / resistance type current limiter is to shield the induced magnetic field generated when energized by the Meissner effect (complete diamagnetism).

The simple principle of operation of the combined inductive / resistance current limiter will be described with reference to the drawings. As shown in FIG. 1, the components are composed of three parts: a current induction coil 1, a high magnetic permeability yoke 3, and an oxide superconducting jacket shield 2 made by a cylindrical reaction sintering method. A current flows through the current-carrying induction coil, and at a normal current value, the cylindrical jacket is in a superconducting state, and the magnetic field generated by the current-carrying coil is completely shielded from the iron core by the Meissner effect. Therefore, the inductance of the whole system is low. However, if a short circuit occurs and excessive current flows through the current-carrying coil, the shielding characteristics of the jacket are broken, and the system behaves like a normal choke coil, limiting the short circuit. The above is the simple operation principle of the combined induction / resistance type current limiter. However, in this case, the principle of operation is a magnetic shield based on the Meissner effect, and in the case of the second type superconductor containing an oxide superconductor, when the Meissner effect is broken, the quantized magnetic flux enters the superconductor, and the superconducting state and the normal conduction The state is a mixed state where the states are mixed.
For this reason, if the Meissner state is simply broken, the magnetic field only enters the superconductor, and a sufficient current limiting effect cannot be expected. Further, the oxide superconducting jacket manufactured by the reaction sintering method is a polycrystalline body. As is generally well known, the oxide superconducting material has a crystal grain boundary acting as a weak bond, a magnetic flux easily enters and exits at the crystal grain boundary, and does not have a very high shielding property. From this, it seems that it is difficult to commercialize the combined induction / resistance current limiter using the fired polycrystalline oxide superconductor.

Independently of this, there has been proposed a current limiter applying the superconducting magnetic flux switching effect, which applies the unique principle of the type 2 superconductor [Electric Research Institute: Onishi et al., 4th of 1990]
Proceedings of the 3rd Spring Low Temperature Engineering and Superconductivity Society B1-14 (19
90), Electrotechnical Research Institute: Onishi et al., Proceedings of the 1991 IEEJ National Convention 938 (1991)]]. The principle of operation is to use the fact that the magnetic flux that has entered the superconductor increases due to the excess current flowing during a short circuit, and the magnetic flux in the superconductor jumps to the high-permeability iron core yoke. . Operating at liquid helium temperature using metal superconducting materials based on this principle has already been reported in the above references. This is due to the excellent shielding properties of metallic superconducting materials and the introduction of pinning sites where magnetic flux can jump at a certain constant magnetic field. Here, the current limiter to which the superconducting magnetic flux switching effect is applied is also referred to as a magnetic flux jump type current limiter due to its characteristics. The flux jump type current limiter utilizing metal superconductivity, which has already been developed, has to be relatively large as a system using liquid helium, and its economic merit is small at this stage.

When an oxide superconductor is applied to a magnetic flux jump type current limiter, it is possible to utilize liquid nitrogen, which is inexpensive and has a relatively simple cooling system, so that the size can be reduced. There is a great potential to do so. However, the shielding characteristics of the oxide superconductor at the temperature of liquid nitrogen greatly depend on the material manufacturing method. A superconducting material produced by a usual sintering method is a polycrystalline body, and includes a crystal grain boundary which is a weak bond that inhibits a superconducting shielding current flowing through the entire superconductor. Therefore, it is known that the critical current density between superconducting grains is as low as several tens of A / cm ² under a magnetic field of 77K and 1T. This is significantly smaller than the critical current density value (10 ⁴ to 10 ⁶ A / cm ² ) required for practical use. From the results examined so far, it has been found that a polycrystalline body such as a sintered body can only shield an external magnetic field of about several tens to several hundreds of gauss ("IEEE Transactions onmagnetics" Vol. 25,
No. 2, March 1989, p.2506-2510). It has been considered that an oxide superconductor cannot be used for a strong magnetic field shield used for a current limiter because a shielding current flowing through the entire shield body is small. In addition, the magnetic flux in the superconductor must jump above a certain magnetic field, which must control the critical current density value by controlling pinning sites in the superconductor. Such control was impossible with a superconducting material using a conventional sintering method.

As described above, in order to utilize an oxide superconductor for a magnetic flux jump type current limiter, a material having excellent shielding characteristics must be used, particularly for high power and medium power applications. Therefore, a flux jump type current limiter using an oxide superconductor has not been realized.

[0009]

Accordingly, the present inventors have:
Recognizing that it is important to develop a cylindrical superconducting member with high shielding characteristics at liquid nitrogen temperature in order to incorporate and operate an oxide superconductor in a flux jump type current limiter, We have been keenly studying a method that allows a sufficient superconducting shielding current to flow through the entire shield body and controls a shield value that causes a magnetic flux jump by controlling a critical current value, and can easily and inexpensively implement the shield value.

[0010] From the above, it can be seen that the shield current has a shielding characteristic of 0.3 T or more at the temperature of liquid nitrogen, the critical current density value can be controlled so that the magnetic flux jump value can be controlled, and the magnetic flux jump type current limiter can be incorporated. It is an object to provide an oxide superconducting member having a cylindrical shape, and a flanged shield member for improving shielding efficiency.

[0011]

Means for Solving the Problems The present inventors have intensively studied to develop an oxide superconducting material excellent in critical current density characteristics and shielding characteristics. Especially YB
By manufacturing an a ₂ Cu ₃ O _7-x- based oxide superconducting material by a melting method, a material having a critical current density higher by two orders of magnitude or more than that of a conventional sintering method has been successfully developed. Based on the technology cultivated in the material development process, we discovered that the above problem could be solved by producing a precursor with a cylindrical shape with a lid on one side and growing crystals from the side with the lid. Thus, the present invention has been completed.

That is, as a member for the flux jump type superconducting current limiting device, the superconducting member is a REBa ₂ Cu ₃ O _7-x type (R
E: a rare-earth element containing Y and a combination thereof) and a superconducting material in which RE ₂ BaCuO ₅ is finely dispersed. In order to improve the current-limiting characteristics of the magnetic field shield, the hollow superconducting material member is made of a single crystal grain, and REBa ₂ C
u ₃ The amount of RE ₂ BaCuO ₅ in O _7-x is preferably a <br/> This 40% or less. From our experimental findings so far,
By changing the charge composition, REBa ₂ Cu ₃ O _7-x
The amount of the fine and uniformly dispersed RE ₂ BaCuO ₅ therein can be controlled,
It has been found that the critical current density can be controlled by changing the amount of E ₂ BaCuO ₅ . Specifically, REBa
The amount of RE ₂ BaCuO ₅ in ₂ Cu ₃ O _7-x is 0% to 40%
When the feed composition is changed such that the%, the critical current density varies linearly from 10,000 A / cm ² to 30,000 A / cm ^2. According to the simplest critical state model, the maximum magnetic field shielding property is proportional to the critical current density. Therefore, REBa ₂ Cu ₃ O
By changing the amount of RE ₂ BaCuO ₅ in _7-x , it is possible to control the shield characteristics.

Further, as a method of manufacturing a flux jump type current limiting device member according to the present invention, a plurality of raw material powders of REBa ₂ Cu ₃ O _7-x type superconducting material are mixed and formed into a cylindrical shape with a hole at one end. When the unopened upper surface is in a semi-molten state, after growing by aligning the crystal orientation by a seeding method using a RE-based seed crystal in which rare earth is substituted, the upper surface including the crystal growth start part is hollowed out by drilling. It is characterized in that a shield member of a single crystal grain is produced.

Further, in the magnetic flux jump type superconducting current limiting device, it is preferable that a flange-shaped shield member shape is added to both ends of the hollow shield member by processing or joining after molding to reduce a loss due to a leakage magnetic field. .

If an oxide superconductor cylindrical member having a high critical current density and a small number of crystal grain boundaries can be manufactured so that the above-mentioned high shielding characteristics can be obtained at the temperature of liquid nitrogen, the device can be operated as a current limiter. The required shielding characteristics can be obtained. In addition, since the center is already hollow at the time of crystal growth, there is no fear that cracks or the like will be introduced by drilling later. Therefore, higher shielding characteristics can be obtained.

[0016]

In the present invention, a single granular REBa ₂ Cu ₃ O _7-x (123 phase) in which REBa ₂ CuO ₅ (211 phase) is finely dispersed is used as a flux jump type superconducting current limiting member. Here, the term “single-granular” means that since the present member manufacturing method is basically a peritectic reaction, even if it is a single crystal as a whole, it contains a fine 211 phase remaining unreacted therein, Expressed as one crystal grain. The critical temperature of this 123 phase is 90 K or more, and it is in a superconducting state at liquid nitrogen temperature. A high critical current density is obtained by finely dispersing the non-superconducting phase 211 phase in the 123 superconducting phase. Have been obtained. Such materials are prepared by a melting method, for example, QMG (Qench and Melt Growth).
h) and a modified QMG method. (QMG method: Japanese Patent Application No. 63-137664, Japanese Patent Application No. 63-261607, improved QMG method: Japanese Patent Application No. 4-5)
5203)

The basic composition used here is RE ₂ O ₃ , Cu
Oxide and Ba oxide have different metal element ratios (RE: B
a: Cu) in atomic percent (10:60:30),
It is assumed that the composition is in a region surrounded by points (10:20:70) and (50:20:30). In the above mixture,
0.001 wt% to 1.0 wt% of a Pt or Rh powder or a compound of Pt or Rh is added and kneaded. The mixed powder that has been sufficiently kneaded is press-formed with a cylindrical mold,
After the isostatic pressing, the precursor is punched out by a drilling machine or the like so that the center portion does not protrude from one side to the other side to produce a precursor. There is also a method that makes it possible to omit the hollowing step. Pressure molding is performed with a mold 4 as shown in FIG. 2, and if necessary, isostatic pressing is performed to produce a precursor of the oxide superconductor. By doing so, the hollowing step can be omitted. Similarly, in a mold 5 as shown in FIG. 3, the mixed and kneaded powder is introduced into a tube-shaped soft pipe 6, a columnar rod is inserted into the center, and isostatic pressing is performed. By such a method, an oxide superconducting precursor having a closed cylindrical shape on one side is produced.

Next, these precursors are placed in a furnace with an opening facing down, and a partial melting temperature (about 10 when rare earth element is Y) is set.
(100 ° C.) or more, about 1100 ° C. After heating, the furnace temperature was cooled to 900 ° C. at a cooling rate of 5 ° C./h,
At that time, a seed crystal in which rare earth sites are substituted at 1030 ° C. (Japanese Patent Application No. 2-402204, Japanese Patent Application No. 2-29925)
Is placed on top of the precursor, and crystal growth is performed so that the entire precursor becomes single crystal grains.

By the above-described method, the production of a cylindrical oxide superconducting member having a uniform crystal orientation and a small number of crystal boundaries is achieved. In order to make this a member for a magnetic flux jump type current limiter, the upper part of the seeding is processed to produce a cylindrical member. As a result, it is possible to shield several thousand gauss or more, which has conventionally been able to show only a few tens of gauss of shielding characteristics at liquid nitrogen temperature due to weak coupling at the crystal grain boundary.

In addition, by adjusting the starting materials,
By changing the amount and size of RE ₂ BaCuO ₅ in Ba ₂ Cu ₃ O _7-x , it becomes possible to control the critical current density value of the current limiter member. This applies to the current limiting device that the critical current density value changes due to the addition of platinum and the control of the starting composition described in the above-described improved QMG method. Conventionally, these methods have been used to create a high critical current density value.On the contrary, in the case of a current limiter, the 211 phase is controlled to cause a magnetic flux jump at an arbitrary magnetic field value, and the critical current is controlled. Applicable to lower density values.

Further, as a flux jump type current limiter member, flange-shaped shields are provided at both ends of the superconducting cylindrical shape so as to prevent the steady-state impedance from increasing due to a leakage magnetic field from a coiled transmission line wound outside the cylinder. , Further high shielding characteristics can be obtained. This flange-shaped shield body is processed and added to the precursor before partial melting, or a flange-shaped member manufactured by the same method after the cylindrical shape is manufactured is replaced with a rare earth element to reduce the melting point of the REB.
Even if a ₂ Cu ₃ O _7-x is inserted as a solder between the flange-shaped member and the cylindrical member, and heated and joined to a temperature equal to or higher than the melting temperature of the solder and equal to or lower than the melting temperature of the member, a flange having excellent shielding properties is provided. It is possible to produce the attached member.

The cross-sectional shape of the above-mentioned cylindrical member is circular, polygonal, and the shape of the flange-shaped member is free, such as circular or polygonal.

[0023]

EXAMPLES (Example 1) A cylindrical flux jump type current limiting member having an outer diameter of about 20 mm, an inner diameter of about 8 mm, and a height of about 40 mm was manufactured by the method described below. In this member, Y ₂ BaCuO ₅ is finely dispersed, and YBa ₂ Cu ₃ O _7-x (Y-123) and Y ₂ BaCuO ₅ are dispersed.
_{5 A} single crystal granular bulk current limiter member having a molar ratio of (Y-211) of 7: 3. In the case of this example, the crystal C axis was set to be parallel to the axis of the cylinder.

Hereinafter, a method for producing a member for a bulk current limiter, a bulk component obtained, a dispersion state of Y-211 and a method for obtaining a cylindrical shape will be described in detail. The following commercially available powders,
_{Y 2 O 3, Ba 2 O} , BaCuO 2, CuO, using PtO _2, these Y-123 and Y-211 are in a molar ratio of 7: 3
And Pt were weighed so that 0.5 wt%, after about 1 hour kneaded in an automatic kneader was formed form using diameter 20 mm, die into a cylindrical shape height 40 mm. Further, the molded powder was vacuum-sealed in a rubber bag, and a load of ² t / cm ² was applied by a cold isostatic press to prepare a precursor. It was subjected to drilling working, leaving 10mm from the top drill diameter 8mm from the bottom of the cylindrical shape precursor. Thus obtained one end perforated cylindrical shape precursor in a box furnace was, after heated to about 1100 ° C., at a heat treatment pattern of cooling at a cooling rate 5 ° C. / h until a furnace temperature 900 ° C., Y from partial melting state Heat treatment was performed so that -123 grew. During this heat treatment, Sm
A seed crystal of -123 was placed inside the box furnace at the center of the upper surface of the columnar precursor in a partially molten state such that the cleavage plane (ab plane) was in contact with it. Take out at room temperature after this heat treatment,
It was transferred to an oxygen atmosphere tubular furnace and subjected to an oxygen addition treatment at 600 ° C. for 20 hours.

The superconductor manufactured as described above has a critical current density of 3 in a vibration sample type magnetometer (VSM) measurement.
× 10 ⁴ A / cm ² , and showed a critical temperature of 92 K from AC susceptibility measurement. The upper and lower surfaces and side surfaces of the cylindrical bulk with one end perforated were polished and observed with a polarizing optical microscope and a secondary electron scanning microscope (SEM). As a result, no grain boundaries were observed. When the crystal axis direction was measured on the upper and lower surfaces by Laue X-ray diffraction, it was found that the column longitudinal direction was parallel to the c-axis direction. That is, it was found by seeding that the entire cylinder with one end hole was formed of single crystal grains. When energy dispersive X-ray component analysis was performed, the matrix was Y: Ba: Cu = 0.98: 2.
The atomic ratio was 02: 2.97. The average particle size of the 211 phase, which is a peritectic reaction residue, is 1 μm, and 0.5 to 5 μm.
And the volume fraction was about 27%. The central part of the upper surface of the single-crystal-grained bulk obtained in this manner was cut with a diamond grindstone, a hole having a diameter of 8 mm was formed in the center part, and the whole was penetrated to form a hollow cylinder having both ends open. Hereinafter this is referred to as member A.

For the sake of comparison, a polycrystalline bulk member B was produced in exactly the same manufacturing process except that no seed crystal was used. The upper and lower surfaces and a part of the side surface of the member B were polished and observed with a microscope, and it was found that the member B was made of polycrystal having an average crystal grain size of about 5 mm. Evaluation of the shielding characteristics of the flux jump type current limiting member obtained as described above
The member A was placed in the bore of the superconducting solenoid magnet, and the shielding characteristics were evaluated. FIG. 4 shows the results at the liquid nitrogen temperature. The result of the polycrystalline member B for comparison is also shown on the same drawing. In the case of the member B, almost no shielding effect was observed as shown in FIG. 8, indicating that the magnetic field was gradually penetrating. On the other hand, according to the shield characteristic 7 of the member of the present invention, it is understood that the external magnetic field is shielded with high efficiency up to 0.4 T, which sufficiently satisfies the function as the flux jump type current limiting member.

In the case of the cylindrical member of the flux jump type current limiter, it is essential that the magnetic field breaks through the shield and enters the inside only when an excessive current flows, thereby increasing the inductance as a whole. In the case of, it is clear that the magnetic field enters the inside of the member from a certain magnetic field and cannot be used.

In the case where the processing method of the precursor was changed, that is, a method in which the mold itself was used to prepare a precursor having a single-ended hole, a rod was inserted into a tube, and the rod was removed after hydrostatic pressure treatment, and the precursor was fabricated in a single-ended hole. In this case, the same result as in the present example was obtained. As is clear from this, in order to produce a cylindrical member of the flux jump type current limiter, it is important to perform seeding and make the entire member from a single grain. It could be confirmed.

Further, Y ₂ O ₃ , BaO ₂ , BaCuO ₂ , C
uO and PtO ₂ were used and these were Y-123 and Y-21.
1 is a molar ratio of 9: 1 and 10: 0 and Pt is 0.5 w
The sample was weighed so as to be t%, and the critical current density of a sample manufactured in the same manner as in the above-described manufacturing method was measured. The critical current density of a 9: 1 molar ratio sample is 1.5 × 10 ⁴ A / cm ² , and the critical current density of a 10: 0 molar ratio sample is 0.9 × 10 ⁴ A / cm ^2.
A / cm ² . The critical current density value can be controlled by controlling the starting powder mixture ratio. By controlling the critical current density value, the magnetic field shield characteristics can be controlled, so that it was found that the method can be applied to the manufacture of a flux jump type current limiter member.

Example 2 A flanged shape was produced in the same manner as in Example 1. The following commercially available powders, Y ₂ O ₃ , BaO ₂ , BaCuO ₂ , CuO,
Using PtO ₂ , these were weighed so that the molar ratio of Y-123 and Y-211 was 7: 3 and the Pt was 0.5 wt%, and kneaded with an automatic kneader for about 1 hour. was formed shape using a mold into a cylindrical shape is 40 mm. Further, the molded powder was vacuum-sealed in a rubber bag, and a load of ² t / cm ² was applied by a cold isostatic press to produce a precursor. Drill 8mm in diameter from the bottom of this columnar precursor to 1
Drilling was performed leaving 0 mm. Further, cutting was performed so that both ends had a flanged shape as shown in FIG. The thus-obtained flange-shaped single-end perforated cylindrical precursor was subjected to a heat treatment in a box furnace in the same heat treatment pattern as in Example 1 so that Y-123 grew from a partially molten state. During this heat treatment, Sm-123
Was placed at the center of the upper surface of the columnar precursor in a partially molten state inside the box-shaped furnace so that the cleavage plane (ab plane) was in contact therewith. After this heat treatment, it was taken out at room temperature, transferred to an oxygen atmosphere tubular furnace, and subjected to an oxygen addition treatment at 600 ° C. for 20 hours.

In order to further form a current limiting device, the center of the upper surface of the obtained single-grained bulk with a flanged shape is cut with a diamond grindstone, and the center is 8 mm in diameter.
And a flanged hollow cylinder with both ends opened. When a coil was wound between the flanges of this member and the shielding properties were evaluated, it was confirmed that compared to the non-flanged member, the magnetic field leakage from both ends of the cylinder was small, and good shielding properties were obtained up to 0.42T. Was.

(Example 3) After a cylindrical flux jump type current limiting member was manufactured in the same manner as in Example 1, a magnetic field was leaked to both ends of the cylindrical shape by using a joining method as described below. A collar made of Y-123 for prevention was added. That is, the following commercially available powder, Y ₂ O ₃ ,
BaO ₂ , BaCuO ₂ , CuO, and PtO ₂ were used, and these were prepared by mixing Y-123 and Y-211 in a molar ratio of 7: 3 and Pt.
Is adjusted to 0.5 wt%, and about 1 wt.
After kneading for a time, the mixture was molded into a cylindrical shape having a diameter of 25 mm and a height of 40 mm using a mold. Further, the molded powder was vacuum-sealed in a rubber bag, and a load of ² t / cm ² was applied by a cold isostatic press to produce a precursor. The cylindrical precursor was drilled from the bottom with a drill having a diameter of 8 mm, leaving 10 mm from the top, to produce a member precursor C. Furthermore, outer diameter 30m
A disk-shaped flange precursor D having a thickness of 5 mm and a thickness of 5 mm was produced by the above-described method. One end perforated cylindrical shape precursor C and discotic flange precursor D obtained in this way in a box furnace, in the same heat treatment pattern in Example 1, such as Y-123 are grown from the partially melted state Heat treatment was performed. During this heat treatment 1030
A seed crystal of Sm-123 is placed at the center of the upper surface of the columnar precursor in a partially molten state inside the box furnace at about 0 ° C. at the cleavage plane (a
b side) was placed so that it might contact. After the heat treatment, the members C and D were taken out at room temperature, transferred to an oxygen atmosphere tubular furnace, and subjected to an oxygen addition treatment at 600 ° C. for 20 hours.

In order to further form a current limiter member, the center of the upper surface of the obtained single-grained single crystal bulk (C) was cut with a diamond grindstone, and a hole having a diameter of 8 mm was formed in the center. The whole was penetrated to form a hollow cylinder having both ends opened.
Similarly, the center of the two disk-shaped members D was cut with a diamond grindstone, and a hole having a diameter of 8 mm was formed in the center. In order to join these two members without impairing the shield characteristics,
The bBa ₂ Cu ₃ O _7-x sintered powder was inserted between members as solder, heated to 980 ° C. in a box furnace, and cooled to room temperature. By doing so, the solder is partially melted, and the member does not melt, so the solder part takes over the crystal orientation of the member,
Bonding without grain boundaries was achieved. When a coil was wound between the flanges of the flanged shaped member manufactured in this way and the shielding characteristics were evaluated, the magnetic field leakage from both ends of the cylinder was smaller than that of the frameless shape member, similar to Example 2. It was confirmed that good shield characteristics were obtained.

[0034]

As described above, the present invention realizes a flux jump type current limiter which has been theoretically possible but not feasible with an oxide superconductor. The present invention provides a magnetic flux jump type current limiting member capable of performing a current limiting operation particularly at the temperature of liquid nitrogen, and has an extremely large industrial effect.

[Brief description of the drawings]

FIG. 1 is a diagram showing basic components of a magnetic flux jump type current limiting device.

FIG. 2 is a cross-sectional view of a mold for producing the precursor of the present invention.

FIG. 3 is a sectional view of a rubber tube type for producing the precursor of the present invention.

FIG. 4 is a graph showing the magnetic shield characteristics of the magnetic flux jump type superconducting current limiter member of the present invention and the magnetic shield characteristics of a member not subjected to seeding.

FIG. 5 shows an example of a precursor of the flanged flux jump type current limiting member of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Induction coil composed of copper winding 2 Hollow superconducting magnetic shield 3 High magnetic permeability core 4 Mold 5 Mold 6 Rubber tube

──────────────────────────────────────────────────続 き Continuing on the front page (72) Kazuhiro Kumagawa, 1-4-1 Umezono, Tsukuba, Ibaraki Pref. Inside the Electronic Technology Research Laboratory (72) Masamoto Tanaka 1618 Ida, Nakahara-ku, Kawasaki, Kanagawa Japan Made in Japan Nippon Steel Corporation Advanced Technology Research Center (72) Innovative Technology (72) Inventor Katsuyoshi Miyamoto Katsura Miyamoto 1618 Ida Nakahara-ku, Kawasaki City, Kanagawa Prefecture Nippon Steel Corporation Advanced Technology Laboratory (72) Inventor Mitsuru Morita 1618 Ida Nakahara-ku, Kawasaki City, Kanagawa Prefecture New Nippon Steel Corporation Advanced Technology Laboratory (72) Inventor Eiichi Teshima Ida Nakahara-ku, Kawasaki City, Kanagawa Prefecture 1618 Shin Nippon Steel Corporation Advanced Technology Laboratory (72) Inventor Keiichi Kimura Ida, Nakahara-ku, Kawasaki City, Kanagawa Prefecture 1618 Shin Nippon Steel Corporation Advanced Technology Research Laboratories (72) Inventor Seiki Takebayashi 1618 Ida Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Nippon Steel Corporation Advanced Technology Research Laboratory Examiner Katsuhiro Kobayashi (56) References JP JP-A-2-105402 (JP, A) JP-A-2-153803 (JP, A) JP-A-5-145128 (JP, A) JP-A-5-137300 (JP, A) JP-A-6-335160 (JP JP-A-5-24908 (JP, A) JP-A-4-15811 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02H 9/02

Claims (1)

(57) [Claims] The present invention relates to a method for producing a REBa ₂ Cu ₃ O _7-x superconducting material.
A number of raw material powders were mixed and formed into a cylindrical shape with a hole at one end
Later, when the unopened upper surface is in a semi-molten state,
By aligning the crystal orientation using a seeding method
And then drill the top surface including the crystal growth start
A hollow cylindrical single crystal granular shield member
Flux jump type current limiting member characterized by producing
Production method. (Where RE is Nd, Sm, Eu, Gd, D
a group consisting of y, Y, Ho, Er, Tm, Yb, Lu
One or more selected elements)