JPH01103409A - Manufacture of superconducting molded body - Google Patents

Abstract

PURPOSE:To obtain an superconductor having an arbitrary form by a method wherein the title method is constituted of a process manufacturing slurry by agitating and mixing up an inorganic powdery body and organic fiber with each other, a process manufacturing a superconducting preliminary body by forming paper of slurry and a process sintering the same after molding the same into a predetermined form. CONSTITUTION:It is necessary that an inorganic material is of an inorganic composite of barium oxide/copper oxide and a powdery body having a particle diameter of 0.05mum-1mm. An organic fiber to be mixed up with the organic material is of a synthetic fiber or synthetic pulp or an animal fiber comprised of a thermoplastic or thermosetting synthetic high molecule such as a natural cellulose fiber or polyolefin. As for a mixture ratio between the inorganic material and organic fiber, it is necessary that the former and latter are 70wt.%-99wt.% and 1wt.%-30wt.% respectively. It is preferable that predetermined quantities of the inorganic material and organic materials are agitated and mixed up with each other under water at a time. Then an superconducting preliminary body in a sheetlike state made through a wet paper making method by making use of the mixture as raw materials is fired at the sintering temperature or higher of inorganic substance within oxidizing atmosphere, a superconductor in an arbitrary form can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for manufacturing a superconductor molded body, and particularly to a method for manufacturing a superconductor molded body using papermaking technology.

<Prior art><Problems to be solved by the invention> At present, substances that become superconductors at a practical level, that is, at high temperatures above the boiling point of liquid nitrogen, have compositions such as yttrium oxide, barium oxide, and copper oxide. It is an inorganic material made of substances. To produce a superconducting molded body from these inorganic materials, a binder such as glycerin is added to the inorganic material, the mixture is solidified, and then sintered to obtain a superconducting bulk material, or By sputtering or other means such as the above-mentioned inorganic material,
The method of producing a thin film-like superconductor by integrating it on a target, or the former method of mixing and binding inorganic materials and then sintering them, is simple, but it is relatively difficult for practical purposes. It is difficult to manufacture glue with a large area, and it is also not easy to mold or grind it into an arbitrary shape. In addition, although a uniform superconducting thin film can be obtained by the latter method, it is difficult to adjust the thickness to a level of μm or more, and it is impossible to obtain a sheet with a large area. It cannot be molded into any shape.

In any case, the current problem is that it is difficult to obtain a superconductor having an arbitrary shape that is suitable for practical use.

Means for Solving the Problems> In view of the above situation, the present invention has been developed as a result of intensive research, and has been developed to contain 70% to 99% by weight of inorganic powder that provides superconductivity and 30% to 1% by weight of organic fibers that can be made into paper. % by weight and a predetermined amount of a papermaking aid to be added as needed, stirring and mixing in water to produce a slurry, and using the mixture in water as a raw material, making paper from the slurry by a wet papermaking method. a step of manufacturing a flexible sheet-like superconducting device, and a step of forming the sheet-like superconducting device into a predetermined shape, and then sintering the inorganic material contained therein in an oxidizing atmosphere. This is a method for producing a superconductor characterized by the following. Note that during molding, applications such as gluing the sheet and making it thicker by laminating the sheet are of course permissible.

The present invention will be explained in more detail below.

The inorganic materials used in the present invention are inorganic composites such as indium oxide, barium oxide, and copper oxide, but are not limited to these, and any inorganic material that provides superconductivity can be used. be. However, these inorganic materials are powders with a particle size of 0.05 μm to 1 mm,
It is necessary that the powder preferably has a particle size of 0.1 μm to 200 μm. The reason for this is that during sheet formation by wet papermaking, these inorganic particles are too small to contain O, OS.
If the particle size is less than μm, the yield of the particles in the paper making process will be poor, and conversely, if the particle size is too large and exceeds 200 pm, the weight of the particles will become large and it will not be possible to obtain a uniformly dispersed suspension state of inorganic particles during paper making. It is.

The organic fibers to be mixed with the inorganic substance that provides superconductivity include wood, cotton, straw, hemp, etc., which are commonly used in the paper manufacturing industry.
Natural cellulose fibers made from bamboo, etc., synthetic fibers made from thermoplastic or thermosetting synthetic polymers such as polyolefins, polyesters, polyamides, acrylic resins, fluororesins, polyvinyl alcohol, phenolic resins, synthetic pulps, animal fibers, etc. However, it is not limited to what is exemplified here.

Paper-making aids that may be added as necessary include starch, vegetable gum, paper strength enhancers made of organic polymers such as polyacrylamide, and polyamide epichlorohydrin;
Dispersants such as polyacrylates, phosphates, and sulfonates, flocculants such as polyacrylamide, epoxidized polyamide, and polyethyleneimine, and those that function as retention improvers, including those exemplified above. It is not limited to.

A method for mixing the inorganic material, organic fibers, and paper-making aid added if necessary is to stir and mix predetermined amounts of the inorganic material, organic fiber, and paper-making aid simultaneously in water.

The thus obtained inorganic material, organic fibers, and papermaking aids added as needed are used as raw materials to make paper to a predetermined thickness using an ordinary wet paper machine. A mixed sheet-like superconducting device is obtained. In this case, the thickness of the sheet-like superconducting device can be arbitrarily controlled by optimizing the raw material supply amount, the raw material concentration in water, the paper making speed, etc.

The sheet-like superconducting device thus obtained has a shape in which inorganic particles are uniformly dispersed between intertwined organic fibers, as shown in the cross-sectional view of FIG. In other words, the inorganic particles are scattered and held in the network structure in which the organic fibers constituting the paper web are entangled.

If a thickness that cannot be made into paper is required, a plurality of these sheets may be combined and integrated by appropriate means such as gluing or laminating.

The mixing ratio of the powdered inorganic material and the organic fiber needs to be 70% to 99% by weight of the former and 1% to 30% by weight of the latter. That is, when the inorganic material is less than 70% by weight, the paper-making properties are improved, but the sheet after sintering does not exhibit superconductivity. If the content of the inorganic material is more than 99% by weight and the content of the organic fiber is less than 1% by weight, the strength in a wet web state will decrease, making papermaking impossible. If the amount of inorganic material is less than 70% by weight and the amount of organic fiber is more than 30% by weight, the sintered sheet will no longer exhibit superconductivity. The exact reason is unknown, but as the proportion of organic fibers increases, impurity ions in the sheet, especially monovalent cations such as Na"K+, increase in the sheet.
It is speculated that this is because these interact with the conduction electrons that cause superconductivity, or because spaces are created between the inorganic powders during sintering.

The sheet-like superconducting device obtained in the above process is highly flexible, extremely easy to handle, and has appropriate strength, which is the property of an aggregate of organic fibers, so it can be shaped into any shape. Can be molded.

However, in the present invention, when the ratio of the inorganic material that imparts superconductivity increases, the flexibility of the sheet-like superconducting device inevitably decreases, and depending on the object to be molded, it may become impossible to mold it. In this case, by adding moisture to the sheet, sufficient flexibility for molding can be obtained. After forming a sheet-like flexible superconducting preparatory body into a predetermined shape, it is fired in an oxidizing atmosphere until the inorganic powder contained in the superconducting preparatory body that provides superconductivity is sintered, and then Cool slowly until it reaches ambient temperature. Calcining in an oxidizing atmosphere is an essential condition for obtaining an inorganic oxide that becomes a superconductor. In addition, when cooling, slow cooling is preferable because if the sheet is rapidly cooled after sintering, the sheet will contract rapidly, resulting in large internal distortions and cracking or deformation of the sheet.

<Example> Hereinafter, the present invention will be specifically explained using examples.

Example 1 Commercially available superconducting inorganic material (manufactured by Furuuchi Chemical Co., Ltd., trade name Superfine 12300: - Yttrium oxide
A mixture of barium carbonate and copper oxide) is placed in a porcelain container.
Fired at 850°C for 1 hour in a high-temperature firing furnace in an oxidizing atmosphere,
It was slowly cooled to obtain a calcined powder. This calcined powder was ground in a mortar to obtain a powder having a particle size of 100 μm or less.

NUKP that has been beaten in advance with a heater to a degree of beating of 40SR
(softwood unbleached kraft valve) and the calcined powder,
The weight ratio of calcined powder/NUKP (raw material mixture ratio of sheet-like superconducting device in Table 1) is 70/30.80/20.9
0/10 and 9515, each was stirred and mixed in water using an archer, and a paper strength enhancer polyamide epichlorohydrin resin (manufactured by Showa Kobunshi Co., Ltd., trade name Polyfix 301) was added to each. 1% by weight of pulp,
Flocculant (polyacrylamide resin, manufactured by Sanyo Chemical Industries, Ltd.,
Product name Sunfloc A H-200P) to raw material 0.5
% by weight was added to obtain papermaking raw materials for sample numbers 1 to 4. The solid content concentration of each sample at this time was 0.5% by weight,
In addition, each raw material weighed 1000 g. This raw material for papermaking is made into paper using a 200++ uw Ford linear machine, with a basis weight of 500 g/rrf and a thickness of approximately 500 pm.
A sheet-like superconducting device was obtained. These sheets have a high yield of calcined powder of 95% or more and have sufficient handling strength.

These sheets were cut into strips with a width of 15+wm and a length of 200mm, and then twisted into a strand shape to create a strip. Furthermore, twist two of these strands together,
A twisted wire shown in Figure 2 was created.

In this work, sheets with an inorganic content of 80% or more lacked flexibility, so they were cut into strips and immersed in water to give them flexibility, then twisted together, and then dried and formed.

These twisted wires were fired at 950° C. for 1 hour in an oxidizing atmosphere and then gradually cooled to atmospheric temperature to obtain sintered twisted wires (sample numbers 1 to 4).

These sintered twisted wires were cooled with liquid nitrogen and
When the Meissner effect was determined using a permanent magnet having a magnetic force of 000 Gauss, the results shown in Table 1 were obtained.

Furthermore, the first step was to determine electrical resistance in cryogenic conditions using the four-terminal method.
The results shown in the table were obtained, superconducting phenomena were observed in sample numbers 1 to 4, and superconducting twisted wires were obtained.

Example 2 A commercially available superconducting inorganic material (manufactured by Furuuchi Chemical Co., Ltd., trade name Superfine 1230 G) was fired at 850°C for 1 hour in an oxidizing atmosphere, and the calcined powder obtained by slow cooling was ground in a mortar. The mixture was crushed to form a powder with a particle size of 100 μm or less, and a dry weight of 1800 g was weighed. In addition, 100 g of dry weight rayon fiber (manufactured by Koshisha Co., Ltd., product name: Cell Cut) with a fiber length of 5 mm and a fiber diameter of 3 denier, a fiber length of 3 mm% and a fiber diameter of 1
．． 5 denier PVA fiber (manufactured by Kuraray Co., Ltd., product name: VBP)
105-1) was weighed in a dry weight of 100 g, each was put into a container filled with water, and mixed and stirred using an agitator.

Next, cationic starch (manufactured by Daiwa Chemical Industries, Ltd., trade name Tsukudyne 70) was added at 2% based on the raw material, and polyacrylamide resin (manufactured by Sanyo Chemical Industries, Ltd., trade name Sunfloc AH-200P) was added as a coagulant at 0.5% based on the raw material. % of the inorganic calcined powder/organic fiber was added to obtain a papermaking raw material with a blending ratio of inorganic calcined powder/organic fiber of 90/10.

This raw material for papermaking was made into paper using a Fordrinier type paper machine of 2001, with a basis weight of 800g/rrr and a thickness of 800μ.
A sheet-like superconducting device of m was obtained. This sheet has a width of 10
+am, cut into strips with a length of 400 mm, softened the sheet by soaking in water, and then bent it 180 degrees from the center with a radius of curvature of 10 mm as shown in Figure 3.
It was molded into a shape that simulates a rectangular wire for a transformer. During molding, this sheet-like superconducting device was given flexibility through water immersion treatment, so it was flexible and did not cause any problems.

This rectangular linear molded product was fired in an oxidizing atmosphere at 950° C. for 1 hour, and then slowly cooled to obtain a sintered molded product (sample number 5).

This molded product was strongly sintered, and as shown in Table 1, the results showed the Meissner effect and the superconductivity phenomenon where the electrical resistance becomes zero in the extremely low temperature range.

Fixation Example 3 A commercially available superconducting inorganic material (manufactured by Furuuchi Chemical Co., Ltd., trade name: Super Fine 1230 G) was fired at 850°C for 1 hour in an oxidizing atmosphere, and the calcined powder obtained by slow cooling was heated in a mortar. The powder was ground to a powder with a particle size of 100 μm or less, and a dry weight of 1800 g was weighed.

NBKP that has been beaten in advance with a beater to a degree of freeness of 40SR
(Softwood bleached kraft pulp) was collected in an amount of 200 g, and both were put into a test machine for testing and mixed by stirring. Polyamide epichlorohydrin resin (manufactured by Showa Kobunshi Co., Ltd., trade name Polyfix 301) was added as a paper strength agent in an amount of 1% by weight based on the pulp.5 Polyacrylamide resin (manufactured by Sanyo Kasei Kogyo Co., Ltd., trade name Sunfloc AH) was added as a coagulant. -200
P) was added in an amount of 0.5% by weight based on the raw material to obtain a papermaking raw material having a raw material concentration of 1% by weight.

Using this raw material, paper was made using a 2001IIll+ Fordrinier paper machine with a thickness of 1 mm and a basis weight of 1000.
A long sheet-like superconducting device was obtained by continuously forming a sheet of g/rd. Apply starch glue (manufactured by Yamato Co., Ltd., product name Yamato Glue T-100) to one side of this sheet,
Wrap the round wood with an outer diameter of 50 mm + φ around 10 times in the length direction, and glue the sheets together to make a sheet with a thickness of 10 mm and an inner diameter of 5.
A cylindrical shaped object with a diameter of 0 mm and a height of 200 mm was created.

Visual inspection after molding revealed that the molded product had no defects such as cracks or distortion.

This cylindrical molded product was fired in an oxidizing atmosphere at 950° C. for 1 hour using a firing furnace, and slowly cooled to obtain a cylindrical sintered product (sample number 6). This molded product is as shown in Figure 1 (the Meissner effect is observed), and the relationship between temperature and potential resistance as shown in Figure 4 (electrical resistance was measured in the circumferential direction).
As can be seen, the superconducting transition temperature is 91, and the e temperature rise is 8
It's on 4th.

From these results, it can be seen that the cylindrical molded product shown in this example is a superconductor.

Comparative Example A sintered twisted wire for comparison was obtained in the same manner as in Example 1, except that the weight ratio of calcined powder/NUKP, which is the raw material mixing ratio of the paper sheet, was changed to 50,150 and 60/40.

The sample numbers at this time were 7 for the former and 8 for the latter in terms of weight ratio. As shown in Table 1, the properties of the obtained sintered twisted wire were such that no Meissner effect was observed and it was impossible to obtain a superconductor.

<Effects of the Invention> As shown in the examples above, a sheet-shaped superconductor was produced using a conventional wet paper-making method using a mixture of organic fibers that can be made into paper in advance and an inorganic substance that imparts superconductivity as raw materials. Because the material is highly flexible, it can be formed into any shape, and the present invention, in which it is fired in an oxidizing atmosphere at a temperature higher than the temperature at which inorganic materials sinter, can be formed into any shape. It provides a conductor.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a sheet (superconducting preform) before sintering according to the present invention, showing the state in which inorganic particles that become a superconductor are dispersed in the mesh structure of organic fibers. It is. FIG. 2 shows the shape of the sintered twisted wire of Example 1, and FIG. 3 shows the shape of the rectangular wire simulator for a transformer in Example 2. FIG. 4 shows the temperature -
Shows the relationship between electrical resistance.

Claims (1)

[Claims] 1) 70% to 99% by weight of inorganic powder that provides superconductivity, and 30% to 1% by weight of organic fibers that can be made into paper;
A process of producing a slurry by stirring and mixing in water with a predetermined amount of a paper auxiliary agent added as necessary, and a process of making paper from the slurry using a wet papermaking method to produce a flexible sheet-like superconducting material. Production of a superconductor molded body, comprising the steps of: manufacturing the superconductor molded body, and molding the sheet-like superconducting device into a predetermined shape, and then sintering the inorganic material contained therein in an oxidizing atmosphere. Method. 2) Organic fiber materials include natural cellulose fibers, synthetic pulp made of synthetic polymers, synthetic fibers, and animal fibers.
or a mixture of two or more, the method for producing a superconductor molded body according to claim 1. 3) A patent claim characterized in that the papermaking aid is made of an organic synthetic polymer and has one or more of the functions of a paper strength enhancer, a dispersant, a flocculant, and a retention aid. A method for producing a superconductor molded body according to item 1.