JPH04206696A - Oxide super conductor magnetic shield cylinder-shaped body and manufacture thereof - Google Patents

Abstract

PURPOSE:To facilitate manufacture and enhance serviceability by laminating a middle layer on a divided substrate which constitutes a cylinder-shaped body to be jointed and connecting said body with a precious metal-made cylinder- shaped body, and further forming integrally an oxide superconducting layer on this cylinder-shaped laminated body. CONSTITUTION:Inconel which serves as a substrate is used in such a manner that it may be divided into parallel in the longitudinal direction of a cylinder- shaped body where four divided members 1 split into 4 sections are manufactured. A glass layer 2 is formed on each divided member 1, thereby manufacturing a divided laminated layer substrate 7. Then, a cylinder-shaped body 3 of Ag is prepared where the divided laminated layer substrate is wound around the cylinder-shaped body 3 so that the glass layer 2 may be connected with the Ag cylinder-shaped body 3, which constitutes a cylinder-shaped laminated layer body 10, combined with each flange 4 for the four divided members and by means of a bolt 6 and a nut 6. Furthermore, a bismuth oxide superconducting layer is formed on the Ag layer of the cylinder-shaped laminated body is formed so that the oxide superconducting layer cylinder-shaped body may be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic shielding cylindrical body using an oxide superconductor and a method for manufacturing the same.

[Prior Art] Conventionally, a space surrounded by a ferromagnetic material such as permalloy or ferrite has been used for magnetic shielding. Furthermore, in recent years, many magnetic shielding devices have been proposed that utilize the diamagnetic properties of superconductors, which have been actively researched and developed. For example, Japanese Patent Laid-Open No. 1-134998 proposes that a superconductor be placed at the innermost side of a magnetically shielded space.

Furthermore, in Japanese Patent Application No. 1-97197, the applicant proposed a magnetic shield tube having at least two layers in the order of substrate and superconducting layer from the magnetic source side for a magnetic source to be shielded.

[Problems to be Solved by the Invention] However, at present, practical magnetic shielding bodies are still in the development stage. In particular, for practical large magnetic shielding bodies, a substrate made of metal or the like is essential in order to maintain mechanical strength. It is also said that in order to obtain high magnetic shielding properties, it is necessary to obtain a superconductor by integral molding. However, as the size increases, it becomes difficult to integrally mold the oxide superconductor including the substrate, and the device also becomes larger, which is not desirable from an industrial perspective. In the prior art, it was difficult to uniformly laminate the substrates in order to create an integrally laminated substrate. Also, if non-uniform parts are introduced during lamination,
After the oxide superconductor layer is formed, stress is concentrated in that area,
There was a problem that the characteristics of the oxide superconductor deteriorated.

Furthermore, metal substrates and oxide superconductors, especially B1-3r
- Is it common practice to form an intermediate layer of noble metal or the like to prevent reaction with the Ca-Cu-0 superconductor, and then form an oxide superconducting layer on the intermediate layer? It is difficult to uniformly form a layer, and furthermore, to uniformly form an oxide superconducting layer on an intermediate layer, and therefore there is a possibility that excellent superconducting properties may not be obtained.

An object of the present invention is to provide a magnetic shielding body with excellent superconducting properties for magnetic shielding using an oxide superconductor, particularly a cylindrical oxide superconducting magnetic shielding body that has a wide range of applications, and a method for manufacturing the same. shall be.

[Means for Solving the Problems] That is, according to the present invention, there is a superconducting magnetic shield cylindrical body having a structure in which a substrate, an intermediate layer, a noble metal layer, a monoxide superconducting layer are arranged in this order, An oxide superconducting layer is integrally formed on a cylindrical laminate formed by bonding a divided laminated substrate in which an intermediate layer is laminated on a divided substrate that forms a cylindrical body by bonding and a noble metal cylindrical body formed in a cylindrical shape. An oxide superconducting magnetic shield cylindrical body is provided.

Furthermore, a divided laminated substrate is produced in which an intermediate layer is laminated on a divided substrate configured to form a cylindrical body by bonding, and after the noble metal cylindrical body is produced, the noble metal cylindrical body and the A cylindrical laminate is produced by joining the divided laminate substrates,
Next, a method for producing an oxide superconducting magnetic shielding cylindrical body is provided, which comprises forming an oxide superconducting layer on the noble metal layer of the cylindrical laminate.

The present invention will be explained in detail below.

In the magnetic shielding cylindrical body of the present invention, the oxide superconducting layer of the cylindrical body 4 may be placed inside or outside.
In particular, when it is desired to obtain a low magnetic field space inside the magnetic shield cylinder, it is recommended to arrange the substrate in this order from the magnetic source side to be shielded, then the intermediate layer, the noble metal layer, and the monoxide superconducting layer, or in the internal space of the magnetic shield cylinder. This is preferable because it can eliminate the influence of magnetic noise of the substrate and intermediate carcass caused by vibration. Also bottomed,
It can be bottomless or bottomless. In fact, it is preferable to use a cylindrical body with a bottom because it provides a higher magnetic shielding effect than a cylindrical body with the same length and without a bottom. Further, 1. The outer shape of the cylindrical body is not particularly limited, and may be appropriately selected from a cylinder, a square cylinder, a polygonal cylinder, etc. according to the purpose of use and conditions of use.

The structure of the superconducting magnetic shield cylindrical body of the present invention is such that a substrate, an intermediate layer, a noble metal layer, a monoxide superconducting layer are arranged in this order. This means that in the substrate-oxide superconductor layer configuration,
If a metal substrate that can maintain the mechanical strength of the oxide superconductor at a high temperature up to the firing temperature of the oxide superconductor is used as the substrate, then when it is fired in direct contact with the oxide superconductor layer,
This is because noble metals react violently with oxide superconductors during firing, reducing the obtained superconducting properties.On the other hand, noble metals, which react less with oxide superconductors and avoiding deterioration of superconducting properties, are This is because, if the mechanical strength of the oxide superconductor is to be maintained, the thickness of the noble metal substrate becomes thicker, which poses a problem in terms of cost. Furthermore, when ceramics are used as a substrate, there is a problem in that it is difficult to obtain a large substrate. Therefore, the configuration of the superconducting magnetic shielding cylindrical body of the present invention is such that it can be used as a substrate up to the firing temperature of the oxide superconductor.
Using materials that can maintain the mechanical strength of oxide superconductors,
A noble metal layer is placed between the substrate and the oxide superconducting layer to prevent a reaction between the substrate and the oxide superconducting layer, and the base metal layer and the substrate are heated to an extremely low temperature such as liquid nitrogen at a temperature lower than the firing temperature of the oxide superconductor. It consists of arranging an intermediate layer that is capable of adhesion in a temperature range up to temperature.

The substrate used in the present invention may be any material as long as it can maintain the mechanical strength of the oxide superconductor, such as ceramics such as zirconia and titania, or 5US430.5US.
310.5US304. Metals such as Inconel, Incoloy, and Hastelloy can be used. The thickness of the board is
There are no particular restrictions.

Further, the intermediate layer of the present invention only needs to be placed between the substrate and the noble metal and have a function of bonding the substrate and the noble metal. For example, glass, various ceramics, metal paste, noble metal paste, etc. can be used. In this case, it is particularly preferable to arrange the intermediate layer between the substrate and the noble metal layer not entirely but partially, for example, in a striped, dotted, lattice, or random manner (see Fig. 1(b). )reference).

The partial arrangement of the glass layer is such that the entire magnetic shield body, including the oxide superconducting layer formed on the noble metal layer, is used during cooling and heating cycles that repeat between extremely low temperatures such as liquid nitrogen and room temperature to develop superconducting properties. This is suitable because it can alleviate the thermal shock experienced by the magnetic field and maintain stable magnetic shielding properties.

The noble metal layer formed on the intermediate layer is made of gold, silver, etc., and it is particularly preferable to use inexpensive silver. The thickness of the noble metal layer may be any thickness that can prevent the reaction between the oxide superconductor and the substrate or intermediate layer. In particular, the thickness of the intermediate layer and the noble metal layer is adjusted according to the thermal expansion coefficient, elastic modulus, and mechanical strength of the oxide superconducting layer, the noble metal layer, the intermediate layer, and the substrate, and the thickness of the oxide superconducting layer and the substrate. It may be selected as appropriate to reduce the thermal stress generated in the oxide superconducting layer. When placing the intermediate layer partially, the thickness of the intermediate layer should be 50 to 250p.
m, the thickness of the noble metal layer is preferably 50 to 700 gm. If the thickness of the intermediate layer is outside this range,
Thermal stress generated in the oxide superconductor layer exceeds the mechanical strength of the oxide superconductor, causing cracks in the oxide superconductor layer when it is cooled to an extremely low temperature using liquid nitrogen or the like.

In addition, if the thickness of the noble metal layer is less than 501 Lm, the above-mentioned function as a relaxation material cannot be obtained, and if the thickness exceeds 700 km, the thermal expansion of the oxide superconducting layer and the noble metal layer is greater than the function as the relaxation material. In some cases, the thermal stress due to the difference becomes dominant, and the effect as a relaxation material is not particularly improved, which is undesirable because it causes an increase in cost.

The oxide superconductor in the present invention is not particularly limited, and includes, for example, M-Ba-Cu-0 Kenhokuai, Mayuka, Sc, Y, La, Eu, Gd, Er, Y.
b, a rare earth oxide superconductor having a multilayer perovskite structure containing one or more rare earth elements selected from lanthanides such as Lu, and for example Bi25r2Ca, Cu2
Any oxide superconductor such as a bismuth-based (Bi-based) superconductor having a composition represented by 0x or Bl 2 Sr 2 Ca 2 Cu 30x may be used.

The superconducting magnetic shielding cylindrical body of the present invention has the structure of the substrate-intermediate layer-noble metal layer monoxide superconducting layer as described above,
Furthermore, the substrate and intermediate layer constituting the cylindrical body are not integrally formed, but the cylindrical body is constructed by combining and bonding divided laminated substrates in which the intermediate layer is laminated on the divided substrate, and the noble metal layer is formed in advance into a cylindrical shape. 1. to form a cylindrical laminate together with the divided laminate substrates. Furthermore, the oxide superconducting layer is formed integrally. In this case, the dividing manner and shape of the divided substrates can take various forms.

For example, FIGS. 1 and 2 show typical examples of how the substrate is divided and the shape of the divided substrates. FIG. 1(a) shows a method of dividing a bottomless cylindrical body, in which the divided laminated substrates 7 shown in FIG. 1(b) are combined and joined, and the cylindrical body is divided into four parts parallel to the axial direction. This is the mode of doing so.

2(a) to 2(d) show an embodiment in which the bottomed cylindrical body is divided parallel to the axial direction, and FIG. 2(a) shows an embodiment in which the cylindrical part and the bottom part are continuously divided and formed. , (b) is an embodiment in which the cylindrical portion and the bottom portion are formed and divided separately, and (C) is an embodiment in which the cylindrical portion and the bottom portion are formed separately and only the cylindrical portion is divided.

Note that FIG. 2(d) shows a cylindrical body having two openings with different inner diameters.

In the present invention, the manner in which the substrate is divided is determined by the purpose of use of the various magnetic shielding cylinders, the conditions of use, the types of the intermediate layer, the noble metal layer, and the oxide superconducting layer, and the joining of the divided bodies as described below. A suitable embodiment can be appropriately selected depending on the method and the like.

The divided substrates of the substrates divided as described above are combined and joined to form a cylindrical body. There are various ways to join these divided substrates.

For example, FIG. 3 shows a typical mode of joining. In FIG. 3(a), a flange is provided on the board divided body l, and the flange 4 is joined with nuts 5 and bolts 6, and in FIG. 3(b), the joined parts 8 of the divided bodies are butted together. If the substrate is metal, it can be joined by welding or the like, and if it is ceramic, it can be joined by a known method such as glass bonding.

In the present invention, the intermediate layer is formed on the divided substrates of the above-mentioned substrates before bonding them to the cylindrical body.

The intermediate layer formed on the divided substrates can take various forms depending on the manner of joining the divided substrates. For example, in FIG. 3, the intermediate layer is composed of a partially bonded glass layer 2, and in FIG. do. Furthermore, FIG. 3(b) shows an embodiment of a divided laminated substrate 7 in which an intermediate glass layer 2 is formed on each divided substrate l, in the case where the substrate is not provided with a flange.

Next, FIGS. 1(c) to 1(e) show the formation of the noble metal layer. For example, in FIG. 1(c), the thickness is 300 to 50
A silver cylindrical body 3 is produced by overlapping or butting and welding silver foils of 0 JLm, and is supported by a core material made of various materials until it is joined to the divided laminated substrate.

The above silver foil welding method is as shown in Figure 1(d).
Extend one Ag layer onto the other Ag layer, overlap the Ag layers to make a double layer, and connect the contact point 9 between the tip of the upper Ag layer and the lower Ag layer by welding or using Ag paste, or
Alternatively, as shown in FIG. 1(e), the Ag layer is joined at the contact point 9 by welding or using Ag paste. When bonding using Ag paste, after applying the Ag paste,
Baking is performed at approximately 800° C. to 900° C. to complete the bonding. Further, in order to form an oxide superconducting layer on the Ag intermediate layer, it is preferable to smooth the welded part and the Ag paste applied part by using a grinder or the like after joining.

In FIG. 1, the divided laminated substrate 7 is wrapped around the silver cylindrical body 3 produced as described above and assembled, and then fired at a glass melting temperature to form a glass layer of the divided laminated substrate 7. After joining 2 and the silver cylindrical body 3, each divided laminated substrate 7 is joined by flanging or welding to form a cylindrical laminate.

In Fig. 3(b), when welding the metal substrate and the noble metal layer, if the melting points of the metal substrate and the noble metal layer are significantly different, when welding the high melting point material side, the low melting point material may partially melt. In such cases, it is not necessarily necessary to weld the faces of the joint cross sections, and it is sufficient to use tactile welding or the like, as long as the mechanical strength for practical use is satisfied.

The oxide superconducting magnetic shielding cylindrical body of the present invention is produced by integrally forming a layer of the oxide superconductor on a substrate, an intermediate layer, and a noble metal layer configured as a cylindrical laminate as described above. - The intermediate layer has a structure of one noble metal layer and one oxide superconducting layer. The oxide superconducting layer may be formed on the noble metal layer by any known method such as coating by spraying, doctor blade method, or the like. Usually, a spray coating method is used, and after coating, it is fired at about 800 to 1150°C to form an oxide superconducting layer. The thickness of the oxide superconducting layer is not particularly limited, and may be appropriately selected depending on the superconducting properties and superconducting material necessary to obtain a practically effective magnetic shielding ability.

In the bottomed cylindrical body of the present invention, it is preferable that the continuous portion between the cylindrical portion and the bottom portion be formed with a curved portion and an obtuse angle portion in the axial cross section of the cylindrical body. If the bottom and cylinder part are curved or continuous at an acute or right angle instead of an obtuse angle, it can be used as a magnetic shield during cooling and heating cycles that repeat between extremely low temperatures and room temperature, such as liquid nitrogen to develop superconducting properties. This is undesirable because the thermal shock that it receives causes stress to concentrate in that part, causing cracks and the like, which significantly deteriorates the magnetic shielding properties. Further, it is preferable that the radius of curvature R of the curved portion is 5■■ or more. If R<511@, as a magnetic shield, stress will be concentrated in that part due to thermal shock during repeated cooling and heating cycles between extremely low temperatures such as liquid nitrogen and room temperature to develop superconducting properties, resulting in cracks, etc. This is undesirable because it significantly deteriorates the magnetic shielding characteristics. Furthermore, it is preferable for the same reason as above to connect the members constituting the bottom of the cylindrical body at obtuse angles.

In addition, in the bottomed cylindrical body of the present invention, if the cylindrical body has two openings with different inner diameters as shown in FIG. This is preferable because it provides a magnetically shielded cylindrical body having the following characteristics.

[Example] Hereinafter, the present invention will be explained in detail with reference to Examples.

However, the present invention is not limited to the following examples.

(Example 1) FIG. 1 is an explanatory diagram showing an example of the divided form of the substrate cylindrical body of the present invention. As shown in Figure 1(a), the inner diameter is lOO, the diameter is 450, and the length is 450.
Four divided bodies 1 were manufactured by using Inconel as a substrate in the manner shown in FIG. Each divided body 1 was provided with flanges 4 for joining at two locations at the divided joint portion. First, each divided body 1
The surface was treated with sand blast, and then masked with paper tape to form the intermediate glass layer 2 in a lattice pattern with intervals of 30 mm, sprayed with a glaze glass slurry for enamel, and heated at 800 to 900°C. After firing for 1 hour, a lattice-shaped glass layer 2 with a thickness of 100 m was formed on each divided body 1 except for the flange 4, thereby producing a divided laminated substrate 7.

Next, an Ag cylindrical body 3 having an outer diameter of Looms was produced by butt welding Ag foils with a wall thickness of 300 pm, and this was reinforced and supported by a metal core material.

Next, the split laminated substrate 7 whose intermediate glass layer has already been baked is wrapped around the Ag cylindrical body 3 and assembled.
Heating at 850-900°C for 1 hour, glass layer 2 and A
The cylindrical body 3 of g was joined.

After that, a glass layer 2 and a silver cylindrical body 3 were laminated and formed.
Align the flanges 4 of each divided body and bolt 6
and fixed with nuts 5 in the manner shown in FIG. 3(a) to form a cylindrical laminate 9.

A slurry containing Bi25r2CaCu20X was spray-coated onto the Ag layer of the cylindrical laminate lO obtained as described above, and partially melted at 875 to 900°C for 30 minutes in an oxygen atmosphere, and then heated to 850°C. Cooling rate 1'
The mixture was slowly cooled at a rate of C/min and crystallized at 850°C for 15 hours. Thereafter, the atmosphere was changed to nitrogen, and heat treatment was performed at 450 to 700° C. for 10 hours to form an fli-based oxide superconducting layer with a thickness of 250 m, thereby obtaining an oxide superconducting cylinder.

The obtained oxide superconducting cylindrical body had a good appearance according to visual observation, and also had good thermal cycle evaluation. These results are shown in Table 1.

In the thermal cycle evaluation, the oxide superconducting cylindrical body was immersed in liquid nitrogen, and after the temperature of the entire cylindrical body reached the liquid nitrogen temperature, the temperature was maintained for 30 minutes to measure the magnetic shielding ability. after that,
One cycle consists of taking out the cylinder from liquid nitrogen, leaving it at room temperature, holding it for 30 minutes after the entire cylinder reaches room temperature, immersing it in liquid nitrogen again, holding it, measuring magnetic shielding ability, taking it out to room temperature, The cycle of standing and holding was repeated 5 times, and the magnetic shielding performance of the first and fifth cooling/heating cycles was compared using the following formula, and 80% or more was given as 0150% or more was given as △, and less than 50% was given as X.

In addition, the appearance evaluation was conducted to evaluate the non-uniformity of the glass joint.

Insufficient steel welding was designated as b.

(Hereinafter, blank space) (Examples 2 to 15) Cylindrical bodies with eaves or without bottom shown in Table 1 were prepared by measuring the dimensions of each cylinder, the material of the substrate, the number of divisions, the joining form, and the A of the intermediate layer.
Each oxide superconducting magnetic shield cylindrical body was obtained in the same manner as in Example 1, with the thickness of the g layer and the bonding form shown in Table 1, and the external appearance and thermal cycle evaluation were performed.

The results are shown in Table 1.

(Comparative Examples 1 to 10) Each oxide superconducting magnetic shielding cylindrical body shown in Table 1 was obtained in the same manner as in Example 1 except that the cylindrical substrate was integrally formed, and the external appearance and thermal cycle evaluation were conducted. I did it. The results are shown in Table 1.

As is clear from the above examples and comparative examples, the oxide superconducting magnetic shield cylindrical body formed using the divided substrate of the present invention has a uniform oxide superconducting layer, etc., and has a better appearance than the comparative example. It can be seen that both the cooling and heating cycle evaluations are excellent.

[Effects of the invention] Since the oxide superconducting magnetic shielding cylindrical body of the present invention is formed by dividing the substrate, it is easy to manufacture even a large cylindrical body, and each layer can be bonded uniformly. As a result, the resulting cylindrical magnetic shield is stable, extremely practical, and industrially useful.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the divided form of the bottomless substrate cylindrical body of the present invention, FIG. 2 is a schematic diagram showing an example of the divided form of the gardened base cylindrical body, FIG. 3 is an explanatory cross-sectional view showing one embodiment of bonding a substrate and an intermediate layer of the present invention. ■...Divided body of one substrate, 2...Glass layer (intermediate layer) 3
... Silver cylindrical body, 4 ... Flange, 5 ... Nut 6 ... Bolt, 7 ... Divided laminated board, 8 ... Joint part 9 ... Contact, 10 ... Cylindrical laminate

Claims (7)

[Claims] (1) A superconducting magnetic shielding cylindrical body, which has a structure in which a substrate, an intermediate layer, a noble metal layer, and an oxide superconducting layer are arranged in this order, and the intermediate layer is placed on a divided substrate that forms a cylindrical body by bonding. An oxide characterized by being constructed by integrally forming an oxide superconducting layer on a cylindrical laminate formed by bonding a divided laminated substrate laminated with a cylindrical noble metal cylindrical body. Superconducting magnetic shield cylindrical body. (2) The oxide superconducting magnetic shield cylindrical body according to claim 1, wherein the joints of the divided bodies are parallel to the axial direction of the cylindrical body. (3) The oxide superconducting magnetic shield cylindrical body according to claim 1, wherein the substrate is metal and the intermediate layer is ceramic. (4) The cylindrical body is a cylindrical body with a bottom, and the cylindrical part and the bottom part have a curved part with a radius of curvature of 5 mm or more and/or are connected at an obtuse angle. oxide superconducting magnetic shielding cylinder. (5) The oxide superconducting magnetic shielding cylindrical body according to claim 4, wherein the members constituting the bottom of the cylindrical body are connected at an obtuse angle. (6) Claims 1 to 6, wherein the substrate is metal, the intermediate layer is glass, and the glass layer is partially disposed on the substrate.
5. The oxide superconducting magnetic shielding cylindrical body according to any one of 5. (7) After producing a divided laminated substrate in which an intermediate layer is laminated on a divided substrate configured to form a cylindrical body by bonding, and producing a noble metal cylindrical body, the precious metal cylindrical body and the An oxide superconducting magnetic shielding cylindrical body characterized in that a cylindrical laminate is produced by bonding divided laminated substrates, and then an oxide superconducting layer is formed on a noble metal layer of the cylindrical laminate. Production method.