JPH0226879A - Superconducting material - Google Patents

Abstract

PURPOSE:To obtain a superconducting material having superior superconducting characteristics such as transition temp. of superconductivity, etc., and having moreover high strength by coating a reinforcing material with a superconducting ceramic material consisting of a compound oxide having a specified compsn. contg. Bi, Pb, Sr, Ca and Cu. CONSTITUTION:A terget superconducting material is obtd. by coating a reinforcing material consisting of a carbon material, ceramic material, metallic material, glass material, etc., with a superconducting ceramic material expressed by the formula. The coating is performed by, for example, carrying out sputtering in oxidizing atmosphere to a target comprising a molded body of each oxide of Bi, Pb, Sr, Ca and Cu, or of powder of carbonates, etc., of each metal, as their precursor, to coat thus the reinforcing material with each oxide or carbonate of the element at the same time. Then, superconducting coating is formed by causing solid phase reaction of each oxide or precursor by calcining said coating layer for each reinforcing material. Suitable thickness of the superconductive coating is 0.1-100mum.

Description

[Detailed Description of the Invention] (Field of Industrial Application) This invention not only has high superconducting properties such as superconducting transition temperature, but also has high strength, and is suitable for use in nuclear fusion reactors, magnetohydrodynamic generators, accelerators, electric motors, and power generators. Materials for magnet coils in rotating electrical equipment such as machines, magnetic separators, magnetic levitation trains, magnetic levitation vehicles, nuclear magnetic resonance tomography diagnostic equipment, magnetic propulsion ships, electron beam exposure equipment, single crystal manufacturing equipment, various experimental equipment, etc. Also suitable as power transmission lines, energy storage, transformers, rectifiers,
Suitable for applications where power loss is a problem, such as phase modulators, and
The present invention relates to a superconducting material suitable as an element such as a Josephson element or a 5QLJID element, and also suitable as an infrared detection device, a magnetic shielding material, etc.

(Conventional technology) Conventionally, Nb, which is a compound-based superconducting material, has been used as a superconducting material.
3Sn and V3Ga are known. These are linear or tape-shaped, but have low strength. Also, the superconducting transition temperature is 18KSV for Nb33n.
It is as low as 15 at 3Ga.

On the other hand, JP-A-55-124907 describes a superconducting material made of carbon fibers coated with NbN. Although this superconducting material has superior strength compared to the above-mentioned compound-based materials, its superconducting transition temperature is still low at 18.

NbTi is also used as an alloy superconducting material, but although it has excellent strength, its superconducting transition temperature is 11, which is also low.

Roughly, PbMo6S8 is included. This is called the Chevrel type, but the superconducting transition temperature is only 15.3K. Also, like compound-based materials, its strength is low.

In addition, there is a B i -8r-Ca-Cu-0 system superconducting material, which has a superconducting transition temperature of about 110°C, but due to the presence of at least three superconducting phases, the resistance is low. In order to increase the temperature at which the temperature becomes zero to 100 or higher, a long heat treatment is required, which is not practical.

(Problems to be Solved by the Invention) The purpose of the present invention is to solve the above-mentioned problems of conventional superconducting materials, and to provide not only excellent superconducting properties such as superconducting transition temperature, but also high strength. The object of the present invention is to provide a superconducting material that can be manufactured relatively easily.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a superconducting material characterized in that a reinforcing material is coated with a superconducting ceramic material represented by the following general formula. provided.

(B IP b) (S rl-q Caq) x
i-p p CU, O7 However, O < p < 0.8 0.3 < q < 0.8 1 x x 3 1 < V < 3 3 < z < 5 The superconducting material of this invention A reinforcing material made of wood,
A coating made of a superconducting ceramic material (hereinafter referred to as superconducting coating) is formed on the reinforcing material.

A coating made of a metal such as copper, silver, or aluminum may be roughly formed on the superconducting coating, but this is for the purpose of making the superconducting properties more stable and is not necessarily necessary.

As the reinforcing material, various forms such as tape, sheet, foil, plate, fiber, and wire can be used. There are various cross-sectional shapes, including circular, oval, square, vertical, and gourd shapes. The thickness and thickness may be arbitrary. The reinforcement may be hollow. If it is hollow,
During use, a refrigerant such as liquid helium or liquid nitrogen can be flowed into the hollow part.

In addition, the fibrous reinforcing material reduces the penetration of magnetic flux into the superconducting coating, suppressing heat generation, slowing down the penetration speed to suppress the amount of heat generated per unit time, and further increasing the cooling effect, making it superconducting. In order to stabilize the properties, it is preferable that the fiber bundle is made of ultrafine single fibers. For example, a bundle of single fibers having a thickness of about 4 to 10 um can be used. In this case, a superconducting coating is formed on each single fiber.

The reinforcing material only needs to be made of a material that can withstand the temperatures described below, and the following materials can be used as the reinforcing material.

Carbon-based materials: polyacrylonitrile-based carbon, pitch-based carbon, etc.

Ceramic materials: alumina, sapphire, alumina-silica, magnesia, partially stabilized zirconia, zirconia, ittria, lanthania, silicon carbide, silicon nitride, titanium carbide, niobium nitride, boron nitride, alkali titanate, lead potassium silicate, titanium Strontium oxide, titanium boride, zirconium boride, etc. Ceramics made of titanium, silicon, carbon, and oxygen (for example, Tyrano M fiber manufactured by Ube Industries, Ltd.), etc.

Metallic materials: w, cu, cr, MOLNl, V, Nb,
Y, Zr, B, Ag, pt etc. Alloys containing at least one of these metals as a main component (for example, 55-59% N+, 1a-12% Mo, 0.04-0.15% C alloys), etc.

Glass materials: E glass, S glass, etc.

Among these materials, metal may have an amorphous structure. Moreover, the materials mentioned above can also be used in combination for the reinforcing material. For example, polyacrylonitrile carbon coated with silicon carbide can be used.

By the way, as mentioned above, the superconducting material of the present invention is formed by forming a superconducting coating on a reinforcing material, and the method for forming the superconducting coating includes, for example, the method described below. be. Note that the thickness of the superconducting coating is approximately 0.1 to 100 μm, although it depends on the application. Also,
Silver or gold may be dispersed as a binder.

Now, the first method targets a molded body of powder such as B i , PbSSr, Ca, and Cu oxides, or carbonates made with their precursors, and transforms it into a reinforcing material by sputtering in an oxidizing atmosphere. This is a method in which a coating of oxides of each of the above elements or their precursors is formed at the same time, and then the reinforcing material is fired to cause a solid phase reaction between the oxides and their precursors to form a superconducting coating. However, the coatings of each oxide or its precursor may be formed separately and sequentially.

The second method uses sputtering like the first method, but this method uses targets that have undergone an in-phase reaction of each oxide or its precursor, or that have undergone a certain degree of solid-phase reaction. use. That is, in this method, first, powders of BPb, Sr, Ca, and Cu oxides and their precursors are mixed, lightly calcined to cause a slight solid phase reaction, and then pulverized. After repeating firing and crushing as necessary, mold into the desired target shape, and
A second firing is performed to cause an in-phase reaction between each oxide and its precursor, and this is used as a target. Thereafter, a superconducting coating is formed in the same manner as in the first method.

The third method is the sol-gel method. The advantage of this method is that alkoxides of Bi, Pb, Sr, Ca, and Cu are gelled and adhered to the reinforcing material, and then fired to form a superconducting coating. In addition to alkoxides, various soluble salts can also be precipitated as hydroxides and the like by appropriate conditions, such as raising the DH.

A fourth method is to apply B to the reinforcing material by chemical vapor deposition.
This is a method in which a coating of oxides of Pb, Sr, Ca, and Cu or their precursors is formed and then fired to form a superconducting coating. When using precursors, volatile raw materials are used, such as acetylacetone, hexafluoroacetylacetone, trifluoroacetylacetone, dipivaloylmethane, thenoyltrifluoroacetone, fluoroacetate, etc. β-diketone complexes such as yltrifluoroacetone can be used.

The fifth method is the so-called atomization method. This method is B
ib Pb% Sr, a compound containing Ca and CLJ,
For example, inorganic acid salts such as nitrates and sulfates of these elements,
This is a method in which a solution of acetic acid salts such as stearates and naphthenates is atomized, brought into contact with a high-temperature reinforcing material, and roughly fired to form a superconducting coating. As a method of atomizing, for example, a spray method, a method of vibrating the solution at high frequency using a diaphragm made of a piezoelectric element, etc. can be used.

The sixth method is to add a thickener to a nitric acid aqueous solution of B r, pb, sr, ca, and Qu, coat the reinforcing material with this, and then immerse it in an oxalic acid aqueous solution to co-precipitate each element. This method involves firing the material to form a superconducting coating. The thickener may be any thickener as long as it decomposes during baking, and polyethylene glycol, polypropylene glycol, cellulose, vinyl acetate, polyvinyl alcohol, starch, gum arabic, and the like can be used.

The seventh method is to spray each oxide of Bi, Pb, Sr, Ca, and Cu on the reinforcing material separately or simultaneously, and then
This is a method of firing.

In the first to seventh methods described above, the firing temperature is 700°C.
~900°C. However, the first, second, fourth,
In the fifth and seventh methods, sintering may not be necessary if the reinforcing material is coated with or adhered to the oxide, etc. at a temperature of 600 to 9 oo'c. Hey,
The firing time is about 1 to 40 hours, preferably about 1Q to 20 hours, and more preferably about 13 to 17 hours.

The firing atmosphere is usually air, but an appropriate oxygen partial pressure,
For example, the atmosphere can be such that oxygen is at 0.1 atm and argon is at 0.9 atm, or it can be a non-oxidizing atmosphere. Further, pressure can be applied during firing. Furthermore, oxygen may escape during firing, and in that case, some oxygen vacancies will be included, but this is okay. If the amount of oxygen vacancies is large, oxygen can be replenished by methods such as ion implantation.

(Example) Example 1 Containing 2.5 mol% of ittria as a reinforcing material, thickness 2
A partially stabilized zirconia tape with a diameter of 0 μm and a width of 5 mm was prepared.

Next, while continuously feeding the tape-shaped partially stabilized zirconia, a precursor coating of a superconducting coating was formed by sputtering. Targets include Bi2O3, P
The powders of bO, SrCO3, CaCO3 and CuO are
i:Pb:Sr:Ca:CIJ is 2:0.4:1.5:
After mixing at a ratio of 1.5:2, it was fired at 800°C for 20 hours to cause a slight in-phase reaction, powdered again, the mixture was molded into a target shape, and further heated at 840°C for 2
Those fired for 0 hours were used and placed on both sides of the running path of the tape-shaped partially stabilized zirconia. After sputtering, the precursor coating together with the partially stabilized zirconia tape was calcined in oxygen at 820'C for 1 hour and slowly cooled at a rate of 100'C/hour.

Thus, on both sides of the tape-shaped partially stabilized zirconia, (B' 0.84P bO,1B>(S
ro, 35CaO, 65> 2.3 Cu1.4 o
A superconducting material having a superconducting coating of No. 5 was obtained. The superconducting transition temperature of this superconducting material was 90°C. Also,
The tensile strength was also very high at 110k(]/mm2.

Example 2 As a reinforcing material, a carbon fiber bundle (single fiber thickness near μm, number of single fibers: 3000) was sufficiently defibrated into a tape shape. In addition, target Toshiteha, B12O3
, PbO, SrCO3, CaCO3 and CuO powder with Bi:Pb:3r:Ca:Cu of 120, 2:
After mixing at a ratio of 1:1:2, sintering at 750'C for 10 hours to cause a slight solid phase reaction, powder again, molding the mixture into a target shape, and roughly heating at 840'C.
The material obtained by firing for 20 hours was used. Using these tape-shaped carbon fiber bundles and targets, each single fiber of the tape-shaped carbon fiber bundles was coated with a precursor in the same manner as in Example 1,
After baking for 10 minutes at 830°C in rough oxygen, 10
It was slowly cooled at a rate of 0'C/hour, and each single fiber was coated with (B' 0.85PbO, 15) (srO, 5caO) with a thickness of 2 μm.
, 5 > 1.7 A superconducting material coated with a superconducting coating of Cu1.705.7 was obtained.

The superconducting transition temperature of this superconducting material was 80. Moreover, the tensile strength was very high at 150 KMmm2.

Example 3 In Example 2, the reinforcing material was changed to one in which each single fiber of the carbon fiber bundle was coated with 0.3 μm thick SiC.

SiC coating thermally decomposes methyltrichlorosilane,
This was done by introducing H2 as a carrier gas into a 1300'C furnace and simultaneously passing the carbon fiber bundle used in Example 11 through the furnace.

The obtained (B i P b ) (S rO
,50,830,17C8□,5) The superconducting transition temperature of the superconducting material having a superconducting coating of 1.7 Cu1.705.7 was 80. Moreover, the tensile strength was also very high at 150 k(]/mm2.

Example 4 In Example 2, the reinforcing material was changed to an alumina fiber bundle. This consists of fine particulate α-alumina and the same amount of A.
It was obtained by a slurry method using a basic aluminum chloride aqueous solution containing l2O3, and the Al2O3 composition ratio was 9.
9% or more, the single fiber diameter is 20 μm, and the number of single fibers is ]000.

Obtained (B!043P bO,17>(S
r o, 5CaO, 5 > 1.7 Cu1.705.7
The superconducting transition temperature of a superconducting material with a superconducting coating is
It was in 1982. Furthermore, the tensile strength was as high as 100,100k.

Example 5 In Example 2, the reinforcing material was changed to a hollow carbon fiber electrolytically plated with silver. The thickness of carbon fiber is 17μ
m, the diameter of the hollow part is about 6 μm. Further, the thickness of the silver plating was about 3 μm, and a fiber bundle consisting of 3000 such carbon fibers was used.

The obtained (B!043Pb□, 17)(Sr□, 5C
The superconducting transition temperature of a superconducting material with a superconducting coating of aO,5>1.67Cu1.705.7 was found to be 86. Furthermore, the tensile strength was as high as about 70 kmMmm2.

Example 6 The carbon fiber bundle used in Example 2 was used as a reinforcing material, and the carbon fiber bundle was treated with TiCl2 gas at 700'C.
Each single fiber was coated with TiB2 with a thickness of 0.3 μm by reaction precipitation by passing it through a mixed gas of BCl3 gas and hydrogen gas.

Next, the carbon fiber bundle in which each single fiber was coated with TiB2 was made into a tape shape, and each single fiber was coated with a precursor by the above-mentioned fifth method, the so-called atomization method. That is, as a solution of the compound, 2 mmol of 81 (NO3)3
・5H20, Q, 5 mmol Pb (NO3)2, 2 mmo+ Sr (NO3) 2, 3 mm01 Ca (NO3)2 ・4H20, 3 mmol C
Using a mixed solution of U (NO3)2 3H20, 3 mm 0 liter 1 wt% aqueous nitric acid solution, and 110 ml water,
This was sprayed from both sides of the tape-shaped carbon fiber bundle while running it in an atmosphere at 450°C. Spraying was performed using a spray nozzle with a nozzle diameter of Q and 3 mm, using oxygen gas as a carrier gas.

Next, the carbon fiber bundle formed by coating each single fiber with a precursor was fired in air at 830°C for 3 minutes, and then heated at 100°C/
Then, each single fiber was coated with 10 μm thick (B
I □, BIP t)o, tg>(S '0.4 C
A superconducting material with a superconducting coating of aO,6>2Cu1.2504.4 was obtained. The superconducting transition temperature of this superconducting material was 92. Also, the tensile strength is 50KM
It was mm2.

Example 7 The carbon fiber bundle used in Example 2 was used as a reinforcing material, and the carbon fiber bundle was passed through a mixed gas of NbCl5 gas, nitrogen gas, and hydrogen gas at 700'C to undergo reaction precipitation. Each single fiber was coated with NbN with a thickness of 0.3 μm.

Next, using a carbon fiber bundle in which each single fiber was coated with NbN, each single fiber was coated with the precursor in the same manner as in Example 6. As a solution of the compound, 3 mmol of Bi (N
o:+)3・5H20 and 1mmol(7)Pb (N
O3)2 and 3mm01 Sr (NO3)2 and 5
Ca (NO3)2 of mm01 ・4H20 and 6mm
o l cu (No: 3) 2.3H20 and 5ml
A mixed solution of 61% by weight nitric acid aqueous solution and 200 mm 1 of water was used.

Obtained (B lo, B3P bo, 17) (
S r o, 5CaO, 5 > 1.7 Cu1.705
．． A superconducting material with a superconducting coating of No. 6 was obtained. The superconducting transition temperature of this superconducting material was found to be 83. Also,
The tensile strength is 48 KO/mm2 (teti) ivy.

(Effects of the Invention) The superconducting material of the present invention has a high superconducting transition temperature, as shown in the Examples, although the mechanism is not clear.

Additionally, it has excellent strength due to the use of reinforcing materials.

In general, unlike the conventional B1-3r-Ca-CU-O-based superconducting material mentioned above, it does not require long heat treatment.
It can be manufactured relatively easily.

Claims (1)

[Scope of Claims] A superconducting material characterized in that a reinforcing material is coated with a superconducting ceramic material represented by the following general formula. (Bi_1_-_pPb_p) (Sr_1_-_qCa
＿q)_xCu_yO_z However, 0<p<0.80 0.3<q<0.8 1<x<3 1<y<3 3<z<6