JPH01151298A - Superconducting electromagnetic shield body - Google Patents

Abstract

PURPOSE:To make a perfect magnetic shielding possible, by forming a shield layer on which a number of superconductive lines comprising an oxide superconductor are closely arranged in a parallel, on an outer surface of a substrate. CONSTITUTION:A first shield layer 4 comprising a number of closely arranged superconductive lines 3 is formed on a surface of a substrate 2 and a substrate 2 is provided on the shield layer 4 and a second shield layer 4a which is the same as the shield layer 4 is formed on the substrate 2 and a substrate 2 is provided on the shield layer 4a. A superconductor 5 in the superconductive line 3 becomes a perfect diamagnetic by the Meissner effect by cooling the shield body 1 below a critical temperature of the used superconductor 5. Since all superconductive lines 3 are arranged in parallel and the center of the shield layer 4a is positioned above a contact part between the superconductive lines 3 of the shield layer 4, it is possible to perfectly prevent the passage of magnetism from occurring. As a result, a perfect electromagnetic shield can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a superconducting electromagnetic shielding body capable of complete electromagnetic shielding.

"Prior Art and its Problems" It is generally known that precision instruments such as computers and magnetic recording devices are easily affected by externally induced magnetic fields. Therefore, in order to prevent electromagnetic waves from entering the device, the device is covered with an electromagnetic shield.

Conventionally, as such an electromagnetic shielding body, for example, a shield plate made of permalloy material, a double shield plate, a triple shield plate made of permalloy, copper, and permalloy, etc. are used.

However, such an electromagnetic shielding body cannot completely prevent electromagnetic waves from entering the device, and the electromagnetic shielding effect thereof has been dissatisfied.

Therefore, in order to solve the above problem, attempts have been made to create a superconducting electromagnetic rolled body using a superconductor as the material of the shield body.

By the way, in recent years, so-called A superconductors such as the Y-B a-Cu-0 system, etc., whose critical temperature (Tc) for transitioning from a normal conductive state to a superconducting state is higher than the liquid nitrogen temperature, have been developed.
-B -Cu-0 system (A is Y, La, Ce.

P r, Nd, P a+, E u, G d, T b, S
LIl, D y, Ho, E r, 'r m.

Indicates group I elements of the periodic table such as Yb, Lu, Sc, etc., and B indicates elements of group II of the periodic table such as Ba, Sr, Mg, Ca, Ra, Be, etc.
A variety of superconducting materials are being discovered, including group a elements. Attempts have also been made to create superconducting electromagnetic shielding bodies that can achieve complete magnetic shielding using such oxide-based superconductors.

The present invention aims to provide a superconducting electromagnetic shielding body that includes an oxide-based superconductor, is capable of complete magnetic shielding, and has high mechanical strength.

"Means for Solving the Problems" A superconducting electromagnetic shielding body according to the present invention has at least one shielding layer formed of a large number of superconducting wires each including an oxide superconductor closely paralleled on the outer surface of a base body. It was formed into layers and used as a means to solve the problem.

Embodiment FIGS. 1 and 2 are diagrams showing an embodiment of the present invention, and reference numeral 1 in the figures represents a superconducting electromagnetic shield (hereinafter abbreviated as shield). This shielding body l has a first shielding layer 4 formed by forming a large number of superconducting wires 3 closely arranged in parallel on the surface of a substrate 2, and a substrate 2 is provided on the first shielding layer 4. , a second shield layer 4a equivalent to the first shield layer 4 is formed on this substrate 2, and the substrate 2 is provided on this second shield layer 4a.

As the material of the substrate 2, metal materials such as silver, copper, aluminum, silver alloy, copper alloy, stainless steel, and ceramics such as alumina are used.

Further, the superconducting wire 3 constituting the shield layer 4 is formed by covering the outer periphery of a round bar-shaped superconductor 5 made of an oxide superconductor with a metal sheath 6, as shown in FIG. As this superconductor 5, A such as Y-B a-Cu-0 is used.
-B -Cu-0 system (A is Y, La, Ce,
Pr, Nd, Pm, Eu, Gd, Tb, Sm, Dy.

1-1o, Er, Tm, Yb, Lu, Sc, etc., represent IHa group elements of the periodic table, B is Ba, Sr, Mg, Ca,
An oxide superconductor such as Ra, Be, etc. representing elements of group 11a of the periodic table) is used. In addition, the material of the metal sheath 6 is Ag5CLI% Aus P tST I
Metal materials such as NA llAg alloy, Cu-Ni alloy, and stainless steel are preferably used. The superconducting wires 3 in the shield body l are all arranged in parallel, and the center of the second shield Q 4 a is located above the contact portion between the superconducting wires 3 of the first shield layer 4. It is located in

When this shield body 1 is cooled to a temperature below the critical temperature of the superconductor 5 used, the superconductor 5 in the superconducting wire 3 becomes completely diamagnetic due to the Meissner effect. All the superconducting wires 3 are arranged in parallel, and a second superconducting wire is placed above the contact portion of each superconducting wire 3 of the first shield layer 4.
Since the center of the shield layer 4a is located at the center of the shield layer 4a, the passage of magnetism can be completely prevented.

To manufacture this shield body 1, first, a superconducting wire 3 is created. This superconducting wire 3 is placed in a metal sheath 6 with A-
It is created by filling the B-Cu-0 superconductor powder or a sintered body obtained by sintering this powder, then reducing the diameter of this metal sheath 6, and then heat-treating this wire. Note that the metal sheath of the wire rod after diameter reduction processing may be removed, the exposed powder compact is heat-treated to form a superconducting wire, and then a metal coating may be applied to the outer periphery of the superconducting wire.

In order to produce a bipedal A-B-Cu-0 system superconductor, first, a compound powder of an element of group A of the periodic table, a compound powder of a group IIa element of the periodic table, and a copper oxide powder are Mix uniformly to make a mixed powder with a mixing ratio of
This mixed powder is heated at 500 to 1000° C. for 1 to several tens of hours to obtain a calcined powder. Next, this calcined powder is compacted to form a compact, and then this compact is heated in an oxygen-containing atmosphere at 700 to 1000°C for about 1 to 100 hours, and then crushed to create a superconducting powder. . The powder compaction treatment, heat treatment and pulverization treatment may be repeated multiple times as desired. By the above operations, A-
13-Cu-0 based superconducting powder is created.

In addition, when inserting a rod-shaped sintered body made of sintered superconducting powder into the metal sheath 6, the superconducting powder is compacted into a round rod shape and then heated at 700 to 1000°C in an oxygen-containing atmosphere for several hours. A sintered body is obtained by performing a sintering process.

Next, this superconducting powder or its sintered body is filled into the metal sheath 6 to create a composite body. Next, this composite is subjected to a diameter reduction process to obtain a wire rod having a desired wire diameter. This diameter reduction process is preferably performed by forging using a rotary swaging device, so that the density of the compacted body within the metal sheath 6 is 75% or more of the theoretical density (porosity or 0% state). It is done.

Next, the wire rod that has undergone diameter reduction processing is subjected to heat treatment.

This heat treatment is preferably carried out in an oxygen atmosphere at a temperature of 800 to 110
This is carried out by heating to 0° C. for about 1 to several tens of hours and then slowly cooling to room temperature. In addition, here, during the slow cooling process, 40
Transformation of the crystal structure of the oxide superconductor from tetragonal to orthorhombic may be promoted by holding the oxide superconductor at a temperature in the range of 0 to 600° C. for a predetermined period of time. In addition, when heat treatment is performed after removing the metal sheath 6 from the wire rod that has undergone diameter reduction processing, the wire rod that has undergone diameter reduction processing is immersed in an appropriate solution that can dissolve the metal sheath 6, such as an aqueous nitric acid solution. After soaking and removing the metal sheath 6, the exposed powder compact is subjected to the same heat treatment as described above to form a superconducting core wire, and then this superconducting core wire is subjected to a coating treatment to form a metal coating. As a method for producing this metal coating, methods such as electroplating, melt plating, and solder plating are used.

Next, the long superconducting wire created in this way is cut into a certain length to obtain a large number of superconducting wires 3. next,
On the surface of the substrate 2, a large number of superconducting wires 3 are arranged closely in parallel in the vertical or horizontal direction of the substrate 2, and each superconducting wire 3 is bonded to the substrate 2 using solder or the like. . As a result, a laminate in which a shield layer 4 in which a large number of superconducting wires 3 are arranged in parallel is formed on the surface of the substrate 2 is obtained.

Next, the two laminates created in this way are stacked one on top of the other with the shield layer 4 side faces facing each other, and the substrate 2 is interposed between these faces, and then a joining method such as soldering or welding is applied. Join by. Through the above operations, shield body 1 is created.

In the above manufacturing method, instead of the superconducting wire 3, the metal sheath 6 is filled with the calcined powder and then a superconducting wire is used which is subjected to diameter reduction processing, and a large number of superconducting wires are attached to the substrate 2. The substrate 2 and each superconducting wire are arranged in parallel and bonded in the state shown in FIG. The shield body 1 may be manufactured by causing a reaction in the calcined powder therein to generate a superconductor.

In this shield body I, the oxide superconductor forming the shield layer 4 becomes completely diamagnetic due to the Meissner effect at a temperature below its critical temperature (Tc) and in a magnetic field below its critical magnetic field (Ha). Therefore, electromagnetic waves can be completely blocked by the shield layer 4, and complete electromagnetic shielding is possible. Therefore, by using this shield l, it is possible to completely block electromagnetic waves, so it is possible to completely prevent electromagnetic waves from entering into precision equipment such as computers and magnetic recording devices, and also to prevent electromagnetic waves from emitting from magnets and various magnetic field generators. can completely confine electromagnetic waves.

Further, in this shield body 1, the shield layer 4 is constructed by arranging a large number of superconducting wires 3 in close proximity in parallel, so that the electromagnetic shielding effect of the shield layer 4 can be made uniform. Further, since the electromagnetic shielding effect can be made uniform, even a shield body with a large area can be easily produced.

Moreover, this shield body l has each shield layer 4゜4ah<
Since it is sandwiched and protected by the JL board 2, the shield layer 4
．． 4a is unlikely to be damaged.

4 and 5 are views showing a modification of the previous embodiment, and the shield body 7 shown in FIG. 4 has a first shield layer 4 formed on the surface of the substrate 2. A second shield layer 4a is formed on the first shield layer 4, and a substrate 2 is provided on the second shield layer 4a. The shield body 8 shown in FIG. 5 is constructed by forming a first shield layer 4 on the surface of a substrate 2, and forming a second shield layer 4a on this first shield layer 4. These shield bodies 7.8 are the shield bodies shown in FIG. Similarly, complete magnetic shielding can be achieved by cooling the superconductor 5 below its critical temperature, and since the number of substrates 2 is smaller than the number of shield bodies 1, manufacturing can be facilitated.

FIG. 6 is a diagram showing another embodiment of the shield body according to the present invention, and reference numeral 11 in the figure indicates the shield body. This shield body 11 is constructed by forming a shield layer 12 on the surface of a substrate 2, in which a large number of superconducting wires 12 are arranged in parallel in close contact with each other. This superconducting wire 12 is a round wire-shaped superconductor 14 of AB-Cu-0 system, as shown in FIG.

Since this shield body 11 does not have a metal sheath 8 around the outer periphery of the superconducting wires 12 used, by arranging each superconducting wire 12 closely in parallel, a complete magnetic shielding effect can be achieved even with only one shield layer 13. is now available.

This shield body 11 is constructed by arranging a large number of superconducting wires 12 in close contact with each other in parallel on the surface of a substrate 2 along the vertical or horizontal direction of the substrate 2, and then using solder or the like to attach each superconducting wire 3 to the substrate. It is created by joining 2.

Similar to the superconducting wire 3 of the previous embodiment, this superconducting wire 12 is made into a composite by filling a metal sheath with superconducting powder or a sintered body thereof, and then subjected to diameter reduction processing using a rotary swaging device. Next, the metal sheath of this wire is clarified in a suitable solution that can dissolve the metal sheath, such as an aqueous nitric acid solution, the metal sheath is removed, and the exposed compact is heat treated. Ru. This heat treatment is preferably performed in an oxygen atmosphere at a temperature of 800 to 1
This is carried out by heating to 100° C. for about 1 to several tens of hours and then slowly cooling to room temperature. Note that it is also possible to promote the transformation of the crystal structure of the oxide superconductor from a tetragonal product to an orthorhombic one by holding the temperature in a temperature range of 400 to 600°C for a predetermined time during the slow cooling process. good.

FIG. 8 shows a modification of the superconducting wire 12 used in the shield body 11 according to this example. A superconductor 14 is provided around the outer periphery of a core wire 16 made of a high-tensile wire such as glass fiber, ceramic fiber, or carbon fiber. This superconducting wire 15 is
Since the structure includes the core wire 16 at the center, the mechanical strength of the shield layer can be increased.

With the shield body 11 of this example, it is possible to obtain a complete magnetic shielding effect as in the previous embodiment, and since only one shield layer 13 is required, the shield body 11 of the previous embodiment is different from that of the previous embodiment. The manufacturing process can be simplified.

In addition, the shield body of this invention can take the following embodiments.

(1) In each of the above embodiments, the plate-shaped substrate 2 was used as the base of the shield 1, but the base can have any shape such as a picture shape or a cylindrical shape.

(2) In each of the above embodiments, the shield layer 4 is formed on one surface of the substrate 2, but an adhesive layer may be provided on the opposite side of the substrate 2 to the surface on which the shield layer 4 is formed. Good. In this case, the adhesive layer makes it possible to attach the shield body l directly to the outer wall surface of a precision VL device such as a computer or magnetic recording device, making it possible to improve the efficiency of work for setting up an electromagnetic shield. becomes.

(3) In each of the above embodiments, the superconducting wires 3, 12, 15 were circular in cross section, but the shape of the superconducting wires is not limited to this, and for example, as shown in FIG. A superconducting wire 23 having a metal sheath 22 on the outer periphery of a superconductor 21 is laminated as shown in FIG. 9 to constitute a shield layer 24, and this shield layer 24 is formed on a substrate 2 to form a shield body 25. It's good as well.

[Manufacturing example]

A shield body using a Y-B a-Cu-0 based superconductor was manufactured. First, Y t Os and [3a C
O3 and CuO are Y2Ba:Cu=1:2:
3 (this), the mixed powder was heated at 700℃ to 1
The powder was calcined for 2 hours to obtain a calcined powder, which was then compacted into a rod shape, heated in an oxygen atmosphere at 900° C. for 24 hours, and then crushed to produce a superconducting powder. Next, this superconducting powder was filled into a cylindrical metal sheath with an outer diameter of 10 au and an inner diameter of 7 mm, and forged several times using a rotary swaging device to obtain a wire rod with an outer diameter of 0° and 8 rn. The compaction density of the powder compact in this wire was 83% of the theoretical density (state with 0% porosity). Next, this wire rod is immersed in a nitric acid aqueous solution to remove the metal sheath, and then the exposed powder compact is heated in an oxygen atmosphere at 900°C for 24 hours, and then slowly cooled to room temperature at -100°C. A long superconducting core wire was obtained by applying this process. Next, this superconducting core wire was immersed in molten solder to form a metal coating on the surface to obtain a superconducting wire. Next? Cut the superconducting wire here to length lx
A large number of superconducting wires were obtained. Next, a large number of superconducting wires were arranged closely in parallel on a copper substrate with a thickness of 1+ nm, a length of 1111 mm, and a width of 1 m, and then welded and fixed to the substrate using the solder layer on the surface of the superconducting wires. , and a laminate. Next, the two laminates created in this way were placed one on top of the other with the superconducting wire side faces facing each other, with the substrate sandwiched between each face, and then heated to about 300°C. Each laminate was joined by welding superconducting wire solder.

Through the above operations, a shield body having a structure similar to that shown in FIG. 1 was obtained.

As a result of examining this shield body, it was found that it exhibited excellent magnetic shielding effect due to the Meissner effect at liquid nitrogen temperature. Therefore, it was confirmed that it has sufficient practicality as a magnetic shield.

"Effects of the Invention" As explained above, in the shield body according to the present invention, the oxide-based superconductor forming the shield layer is heated at a temperature below its critical temperature (Tc) and under a critical magnetic field (Hc). Since it exhibits complete diamagnetic property due to the Meissner effect in a magnetic field, the shield layer can completely block electromagnetic waves, making a perfect electromagnetic nord possible. Therefore, by using this shielding body, it is possible to completely block electromagnetic waves, so it is possible to completely prevent electromagnetic waves from entering the inside of precision equipment such as computers and magnetic recording devices, and also to prevent electromagnetic waves emitted from magnets and various magnetic field generators. It can completely confine electromagnetic waves.

In addition, this shield body has a shield layer composed of a large number of superconducting wires arranged closely in parallel, so the electromagnetic shielding effect of the shield layer can be made uniform, and magnetic leakage due to poor formation of the superconductor can be prevented. It can be prevented. In addition, the electromagnetic shielding effect can be made uniform, so
Even a shield body with a large area can be easily produced.

[Brief explanation of the drawing]

1 and 2 are views showing one embodiment of the shield body of the present invention, in which FIG. 1 is a cross-sectional view of the shield body, FIG. 2 is a perspective view thereof, and FIG. 3 is the same as that in FIG. FIG. 4 and FIG. 5 are cross-sectional views showing a modification of the shield shown in FIG. 1, and FIG. 6 is a cross-sectional view of a superconducting wire used in the shield shown in FIG. 7 is a sectional view of a superconducting wire used in the shield body shown in FIG. 6, FIG. 8 is a sectional view showing a modification of the superconducting wire shown in FIG. 7, and FIG. 9 is a sectional view of a superconducting wire used in the shield body shown in FIG. 1 is a sectional view of a shield body showing an application example of the shield body of the present invention, and FIG. 1O is a sectional view of a superconducting wire used in the shield body shown in FIG. 1.7, 8, 11.25... Shield body (superconducting electromagnetic shield body), 2... Substrate, 3, 12, 15.23
...Superconducting wire, 4, 4a, 13.24... Shield layer.

Claims (1)

[Claims] 1. A superconducting electromagnetic shield, characterized in that at least one shield layer formed of a large number of superconducting wires each comprising an oxide superconductor closely paralleled is formed on the outer surface of a base.