JP3088830B2 - Reforming method of oxide superconductor molded body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reshaping a molded article made of an oxide superconductor used for shielding magnetic fields and the like.

[0002]

2. Description of the Related Art In recent years, Y-Ba-Cu-O, Bi-
(Pb) -Sr-Ca-Cu-O system, Tl-Ba-Ca
Oxide superconductors having a critical temperature (Tc) exceeding the liquid nitrogen temperature, such as a -Cu-O system, have been found, and application research on cables, conductors for magnets, magnetic shielding materials, and the like has been actively promoted. The above-mentioned magnetic shielding material is used to shield magnetism generated from a magnet installed in an MRI (Magnetic Resonance Computed Tomography Diagnostic Device) or a magnetic levitation train, and the superconductor repels the magnetic field. The Meissner effect is used. The Meissner effect of this superconductor has a higher shielding ability than a conventional iron plate that generates an induced current in the iron plate and absorbs the magnetic field. Therefore, the weight and shielding of the magnetic field shielding device by reducing the thickness of the superconductor layer are reduced. The space can be expanded. In addition, since the oxide superconductor exhibits superconductivity at the temperature of liquid nitrogen, there is an advantage that the cooling cost is lower than that of a metal-based superconductor requiring expensive liquid He.

[0003] Since the above-mentioned oxide superconductor is brittle, to process it into a magnetic shielding material or the like, for example, a raw material powder such as an oxide superconductor or a precursor that can be formed into an oxide superconductor is compacted. It has been carried out by a method of molding into a bulk compact, heating and sintering the compact at a high temperature and subjecting it to heat treatment so that the raw material powder reacts with the oxide superconductor.

[0004]

However, since the above-mentioned compacted body of the oxide superconductor is heated to a temperature high enough to partially melt in the heating and sintering step, the compacted body of the human body magnetism measuring apparatus is particularly required. In a large-sized apparatus, it is extremely difficult to maintain the original shape of the compact. For this reason, a method has been proposed in which a raw material powder is applied in a layered form on a metal mold material having a predetermined shape in advance and subjected to predetermined heat sintering and heat treatment to produce an oxide superconductor molded body. However, in this method, there are problems that the weight of the oxide superconductor molded body increases, making it difficult to handle, and leading to an increase in cost. In the case of a large molded body, a method of assembling the divided molded bodies of the oxide superconductor with each other has been proposed,
The molded article obtained by this method cannot prevent the invasion of magnetic flux from the butted portion, and is inferior in the magnetic field shielding ability.

[0005]

SUMMARY OF THE INVENTION The present invention has been made as a result of intensive studies in view of the above circumstances, and an object of the present invention is to produce an oxide superconductor having a desired size and excellent superconductivity. An object of the present invention is to provide a method for easily reshaping a feature. That is, the present invention, the oxide superconductor manufactured by the molded body, on the mold material A having a predetermined shape, with intervening directly or unreactive sheet over preparative, placing the double several closely arranged to further on a plurality of oxide superconductor manufactured molded body group disposed near <br/> contact this,
Directly or nonreactive sheet over preparative is interposed, by placing the mold material B of the same shape as the mold material A, and constituting an integrated body of the oxide superconductor manufactured by the molded body and the mold material, the stack By heating to a high temperature to soften the oxide superconductor molded body, a load is applied to the softened oxide superconductor molded body, and the oxide superconductor molded body is molded into mold material A and mold material B. And pressure molding between them.

[0006] In the method of the present invention, the oxide superconductor molded product is a material obtained by subjecting a predetermined heat treatment of a raw material powder compact or a heat-sintered compact of the compact to be an oxide superconductor. It refers to a molded body of a substance that reacts with the oxide superconductor when applied, or a molded body of the oxide superconductor. In addition, the raw material powder that can be made into the oxide superconductor is an oxide superconductor powder, an intermediate until it reacts with the oxide superconductor by performing a predetermined heat treatment, for example, an oxide superconductor constituent element Or a powder of an oxide-deficient composite oxide or an alloy of the above constituent elements. In order to compact the raw material powder into a desired shape, besides a method of directly compacting the raw material powder by a uniaxial pressing method, a CIP process, or the like, a method of kneading the raw material powder using a binder to form a slurry. And a method of molding the same.

The present invention will be specifically described below with reference to the drawings.
I do. Fig. 1 (a) and (b) are powder compacts of the oxide superconductor of the present invention.
Process explanatory view showing an example of an embodiment of a method for reshaping a formed body
It is. A plurality of small plate-shaped sintered bodies 11 of oxide superconductors are arranged on a plate-shaped SUS mold member A with a silver sheet 2 in a state where the sides thereof are abutted in a plane shape. Form material B made of SUS over silver body 11 through silver sheet 2
The plate 3 is heated and pressurized to a temperature at which the plate-shaped sintered body 11 softens, and the plate-shaped sintered body 11 is expanded by expanding the area. Plate-shaped sintered body 1
1 mutual sides to each other coalesce joining one piece of (Zuro).

In the method of the present invention, an arbitrary material such as a metal material such as SUS and ceramics having excellent heat resistance is used as a mold material for pressing the oxide superconductor compact.
Further, when material before Symbol type material is a material which reacts with the oxide superconductor manufactured moldings, silver or a noble metal or yttrium-stabilized zirconium oxide of platinum or the like between the mold material and the oxide superconductor manufactured molded body A material that is not reactive with the oxide superconductor such as (YSZ) is interposed. When the non-reactive material to be interposed is a soft material, the forming process is performed gently, and the quality is further improved. In the method of the present invention, the pressure at the time of molding an oxide superconductor manufactured molded body is applied by the own weight of the mold material Ru placed on the oxide superconductor manufactured molded body, further type of this <br / > It is also possible to increase the compression pressure by placing a weight on the material. The method of the present invention is applied to the reshaping of any oxide superconductor formed body including the above-described Bi-based, Y-based, and Tl-based oxide superconductors.

[0009]

According to the method of the present invention, a molded article made of an oxide superconductor is
An integrated body is formed by sandwiching between two molds having the same shape, and the integrated body is heated to a temperature at which the oxide superconductor softens, and the softened oxide superconductor molded body is compressed between the molds , before Symbol
Since molded into the same shape as the mold material, it is reshaped in a good shape without warpage or irregularities. Also, since the molded body made of oxide superconductor is pressed against the mold material during the reshaping process, the surface is smoothed,
Moreover the shaped body bubbles in the molded product because it is compressed from both sides at a high temperature is discharged from the side surface by moving diffused in the molded body, the oxide superconductor manufactured by reshaping body obtained high density It will be. In addition, defects such as nests and cracks of the molded body disappear during compression remolding.

[0010] If the molding material is a material in contact with the reaction with the oxide superconductor, because interposing a non-reactive sheet over preparative therebetween, without such an oxide superconductor is deteriorated, and before
Since the carboxy over door is the case of the soft is made slowly compression,
The resulting reshaped product made of oxide superconductor has higher quality. In the present invention, a plurality of molded bodies made of oxide superconductor are arranged in contact with each other, and the molded bodies in contact with each other are molded with two mold members.
From the direction, heating it to the softening temperature of the oxide superconductor, compressing it between the molds, expanding the area of each of the compacts, joining and joining the sides of the adjacent compacts together Therefore, the thickness and composition of the joint can be equalized, and a high-quality joint can be formed.

[0011]

The present invention will be described below in detail with reference to examples. Example _{1 Bi 2 O 3, SrCO 3} , CaCO 3, a raw material powder of CuO, etc.
Bi: Sr: Ca: Cu has an atomic ratio of 2: 2: 1: 2.
After mixing and mixing so that
Pre-fired by heating at 850 ° C. for 4 hours to obtain a pre-fired body
Was ground into calcined powder. Next, this calcined powder is 80 mm
× 80mm × 2mm and press-mold into a plate
Heat the body in an oxygen atmosphere at 905-910 ° C for 10 minutes
After sintering and the furnace temperature dropped to 700 ° C,
The obtained oxide superconductor was formed into a plate-like molded product. Next
Each of the four oxide superconductor plate-shaped molded products was cut into a flat shape on each side surface, and was arranged in a square shape on a 0.2 mm-thick silver sheet at intervals of 2 mm each. A silver sheet having a thickness of 0.2 mm is placed over the group of plate members made of oxide superconductor, and a plate member made of SUS is placed above and below to form an integrated body, and the integrated body is placed in a furnace. 885 ° C
It was heated and held for 10 minutes. During the heating and holding, each oxide superconductor molded body is pressed by its own weight of the SUS plate-shaped material, the area is enlarged, the side surfaces are united and joined, and a 164 mm square plate-shaped body is formed. was gotten. Next, this bonded plate-shaped body was subjected to a heat treatment at 850 ° C. for 12 hours in the atmosphere to produce a plate-shaped formed body made of a Bi-based oxide superconductor.

[0012] was measured in this way was a liquid nitrogen temperature of the obtained Bi-based oxides superconductors made molded body (77K) critical current density in the absence of a magnetic field (Jc). The results are shown in Table 1 together with main production conditions and quality levels.

[0013]

[Table 1]

[0014] As is apparent from Table 1, the present invention method goods (No 1) is a high junction strength of the four oxide superconductor manufactured molded body, and Ri der quality good contains no bubbles , J
c was a high value.

[0015]

As described above , according to the method of the present invention, it is possible to easily reshape a large-sized, high-quality oxide superconductor molded article having excellent superconducting properties, which is remarkably advantageous in industry. To play.

[Brief description of the drawings]

FIG. 1 is a process explanatory view showing an example of an embodiment of a joint integral molding method of the present invention.

[Explanation of symbols]

 1,11 Oxide superconductor plate-like molded body 2 Silver sheet 3 Aggregate A, B Metal mold

Claims (1)

(57) [Claims] A molded article made of an oxide superconductor is formed into a predetermined shape .
On the mold material A, with intervening directly or unreactive sheet over preparative, placed in proximity placing multiple <br/> several further plurality of oxide superconductor made that proximity arrangement of this Direct or non-reactive on the compacts
With intervening sexual sheet over preparative, by placing the mold material B of the same shape as the mold material A, and constituting an integrated body of the oxide superconductor manufactured by the molded body and the mold material, heating the integrated body to a high temperature soften the oxide superconductor manufactured by molding of said Te, by applying a load to the oxide superconductor manufactured molded body softening, the oxide superconductor manufactured molded body
A method for reshaping a molded body made of an oxide superconductor, comprising press-molding between a mold material A and a mold material B.