JPH01265414A - Manufacture of oxide superconductive wire rod - Google Patents

Abstract

PURPOSE:To enhance superconductive property and increase production efficiency by electrostatically sticking, on a linear base and heat-treating formed powder which is made by solving a raw material in a solvent, then atomizing and heat-reacting the solution. CONSTITUTION:Solution 2 which is made by solving chemical compounds each containing composing elements of oxide superconductor is set in a supersonic nebulizer in an electrostatical adhesion reactor and then atomized. Atomized substance 5 is selected by a particle diameter selecting DMA4 supplied into a reaction furnace 7 which has been heated to a defined temperature. The atomized substance 5 is heated in the reaction furnace 7 by a heating device 8 and reacted into the oxide superconductive powder. Simultaneously the powder formed by a electrostatic field generated by a pipe-shaped electrode 9 and the linear base 10 is electrocharged and collected and on stuck base and finally wound on a coiler 11 to manufacture an oxide superconductive wire rod. The powder is so speedily and densely stuck on the linear base 10 that a fine formation of oxide superconductive layer is possible by electrocharging thus formed powder and sticking it on the linear base 10.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for manufacturing an oxide superconducting wire.

(Prior art) In recent years, LaSr Cu, o,
-δ, YBazCusOt-δ, B15rCaCu, O
Oxide superconductors represented by chemical formulas such as K have been discovered.

These oxide superconductors are much more economical than conventional metal superconductors which exhibit superconductivity at liquid He temperatures because they become superconducting above the liquid N2 temperature, and their use in various fields is being considered.

By the way, the above-mentioned oxide superconductors cannot be processed plastically like metal materials because they are bent, and powder metallurgy is mainly used to process them into plates, wires, etc. For example, by pre-sintering the raw material powder, A method is used in which the calcined powder is formed into a calcined powder, the calcined powder is coated on a substrate, or filled into an Ag tube or the like and stretched, and then heated and sintered in an atmosphere containing O2.

[Problem to be solved by the invention]

In the above powder metallurgy method, plasma spraying, paste coating, etc. are used to coat and mold the calcined powder onto the substrate, but the former has poor adhesion efficiency, and the latter takes a long time to dry. There was a problem in that the superconducting body required for this process became porous and the superconducting properties deteriorated.

Another problem with the method of filling calcined powder into Ag tubes, etc. is that it is difficult to fill the tube with calcined powder continuously and at a high density, which tends to cause variations in properties in the longitudinal direction, especially in long materials such as wire rods. was there.

[Means to solve the problem]

The present invention has been made in view of this situation, and its purpose is to provide a method for efficiently manufacturing an oxide superconducting wire with excellent properties.

That is, in the present invention, compounds containing each of the constituent elements of an oxide superconductor are dissolved in a predetermined M solvent, and this solution is atomized and supplied to a reactor heated to a predetermined temperature to cause a reaction. The oxide superconductor powder is made into an oxide superconductor powder, the oxide superconductor powder produced by creating an electric field in the reactor is charged, and the charged powder is attached to a charged linear substrate on a collecting electrode. It is characterized by being subjected to heat treatment as well as heat treatment.

In the present invention, the compound containing each of the constituent elements of the oxide superconductor is, for example, YBa2Cu.

Examples of superconductors of 01-δ (δ #0.1 to 0.3) include acetates, nitrates, halides, and organometallic compounds of Y, Ba, and Cu, respectively.

In the present invention, the method for atomizing the above compound is as follows:
For example, a method may be used in which each of the above compounds is dissolved in a solvent such as water and atomized using an ultrasonic nebulizer or the like.

As a method for continuously supplying the above-mentioned atomized material to the flame, it is preferable to convey the atomized material in a carrier gas such as air, O2, N2, Ar, etc., since the amount of the atomized material to be supplied can be easily controlled.

In the present invention, methods such as electric resistance heating, high frequency induction heating, and burner heating are particularly suitable as heating methods for causing the atomized material to undergo a thermal reaction with the oxide superconductor powder.

As a method for charging the oxide superconductor powder produced in the present invention, in addition to the electric field charging method, a diffusion charging method or the like can be applied.

In the present invention, the oxide superconductor powder produced by heating with a flame includes, for example, Y-Ba-Cu-0 based oxide superconductors such as YBa, Cu, 0. Although it is a complex oxide represented by the chemical formula -δ, the above oxide superconductor also contains a complex oxide with a composition deficient in oxygen, and this powder is heated to a specified temperature in an oxygen-containing atmosphere. The treatment further improves the superconducting properties.

In the method of the present invention, a block-shaped substrate or the like may be used as the substrate, but the effect is particularly exhibited when the oxide superconductor powder is continuously attached to a long linear substrate.

[Effect]

The oxide superconductor raw material is dissolved in a solvent to form a solution, and this solution is atomized and heated to generate a fine oxide superconductor powder.The generated powder is then charged in an electric field, and this charge is Since the powder is electrostatically deposited onto the linear substrate charged with the dust collecting electrode, the generated powder is deposited on the substrate at a high yield, at high speed, and with high density.

〔Example〕

The present invention will be explained in detail below using examples.

Example 1 FIG. 1 is a schematic explanatory diagram of a charged adhesion type reaction apparatus showing an example of an apparatus for carrying out the method of the present invention.

The charged adhesion type reaction device includes an ultrasonic nebulizer 3 for atomizing the raw material solution 2, and a carrier gas control MFC (Mass-Fl) for transporting the atomized material 5.

w-Controller) 1. DMA for particle size selection of the atomized material 5 (Differential-Mob
ity-Analyzer) 4. It consists of a reaction furnace 7 for heating and reacting the selected atomized material 5 to oxide superconductor powder. A pipe-shaped electrode 9 for generating an electric field for charging the powder and a charged linear base 10 are arranged as dust collecting electrodes for adhering the charged powder.

In this example, Y (CH) was used as the starting material.

COO)3 ・4 Ht○, Ba (C1-!3COO
)! - An oxide superconductor powder having a YBa, cu, o, -δ composition was produced using H2O and Cu (CH,Coo)z.HzO.

Each of the above starting materials has an atomic ratio of Y:Ba:Cu of 11
: Weigh it so that it is 3, dissolve it in water and make YBa2
An aqueous solution having a composition of Cu and a concentration of 0.03 mol/l was prepared.

The above aqueous solution was set in the ultrasonic nebulizer 3 of the charged adhesion type reactor shown in FIG.
The atomized material 5 is atomized at a speed of n, and then this atomized material 5 is placed on the 02 air stream flowing in from the MFCI at a flow rate of IO3LM to DMA.
The atomized material 5 having a particle size of 4 μm or less was selected by the DMA 4 and supplied into the reactor 7.

The atomized material 5 supplied into the reactor 7 is heated by the heating element 8 and reacts to form an oxide superconductor powder, and
An electric field is generated between the pipe-shaped electrode 9 incorporated in the reactor 7 and the linear substrate 10 running inside the reactor 7 to charge the powder, which is then collected and deposited on the substrate 10 to a thickness of 200 mm. Then, it was wound on coiler 11. The linear substrate 10 is made of B572 No. 6002 (0.5 + nnφ).
ASTM) Ni alloy was preheated to 550°C in a preheating furnace 6 and moved through the furnace 7 at a speed of 10 cm/min.

The linear substrate 10 is grounded on the side of the coiler 11 and connected to the Co1d terminal of a high voltage power source 12 with a DC voltage of 30 kV to serve as a dust collection electrode, while the Hot terminal of the high voltage power source a12 is connected to the pipe-shaped electrode 9. , this results in an electric field charging strength of 10kv
/cra was generated.

Example 2 B i (C6H706) 7H as starting material
20, S r (C6H*06)z ・3H20, Ca
(C6H,○,)2.5 H,O and Cu (CaHq
B was prepared in the same manner as in Example 1 using Oa)z ・2HtO.
An oxide superconductor powder having a composition of 15rCaCu,O was produced.

In addition, each of the above starting materials are Bi:Sr:Ca:CU
B15rCaCu,
The composition is 0.1 mol/! A concentrated solution was used.

In this embodiment, a pipe-shaped electrode 9 for generating an electric field is used.
The same reactor as shown in Fig. 1 was used, except that the electrode was replaced with a plate-shaped electrode, and a die and welding machine for forming the tape-shaped substrate into a tubular body after powder deposition were placed between the roller 13 and the coiler 11. An oxide superconducting wire was manufactured using this method.

The solution containing the raw material dissolved therein is placed in the ultrasonic nebulizer 3 of the reaction apparatus shown in FIG.
Atomized at a speed of 0 cc/min, and then this atomized material 5
was transported to the DMA 4 on the 02 air flow flowing in from the MFCI at a flow rate of 20 SLM, and the atomized material 5 of 7 μ or less was selected by the DMA 4 and supplied into the reactor 7.

The atomized material 5 supplied into the reactor 7 is heated and reacted to form oxide superconductor powder, and travels in the reactor 7 with a plate-shaped electrode incorporated in the reactor 7. An electric field is generated between the tape-shaped substrates to charge the powder, and the powder is collected and deposited on the substrate to a thickness of 100 nm.Then, after passing through a guide roller 13, the tape is rolled into a pipe shape with a die using a roller-type high-frequency welding machine. The ends were welded to form a tubular body with a core diameter of 1.12 mm and an outer diameter of 2.26 mm, which was wound around a coiler 11.

Note that the tape-shaped substrate has a size of 300 nt×10 (t)
Copper alloy B572 A11ay 706 (AST
M) preheated to 750°C in preheating furnace 6 at 15c+n/mi.
The inside of the furnace 7 was run at a speed of n. The DC voltage of the high-voltage electric a12 was set to 25 kV to generate an electric field charging strength of 9 kV/cm.

Comparative Example I A calcined powder of YB az Cu ; l Oo was filled into an Ag pipe with an outer diameter of 6 cylinders and an inner diameter of 5 mm.
The wire was then cold drawn to 900' in an 02 air stream
After heating at C20H, heat up to 300'C at 2°C/min.
An oxide superconducting wire was obtained by slow cooling at a speed of .

The relative density J and durability of each of the oxide superconducting wires obtained in this way were investigated.Durability was determined by passing a current of 80% of JC in liquid N2 and JC after one week. The results are shown in Table 1.

Chapter 1 Table *Measured using the 4-terminal method in liquid nitrogen (77K).

As is clear from Table 1, the method of the present invention (Example 1.2
) has a higher relative density than the comparative method product (Comparative Example 1),
Both Je and durability are excellent.

This is because in the method of the present invention, fine oxide superconductor powder is charged and adhered to the substrate, so that the oxide superconductor layer is formed densely.

In addition, the characteristics of the comparison method product are low because the grain size of the calcined powder is coarse and uneven, and it is difficult to fill the upper Ag tube with the calcined powder, resulting in a low density of the oxide superconductor layer. This is because impurities were mixed in during the pulverization and classification of the powder.

(Effects) As described above, according to the method of the present invention, an oxide superconducting wire with excellent properties can be efficiently produced, and therefore, a remarkable effect is produced industrially.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram of a charged adhesion type reaction apparatus showing an example of an apparatus for carrying out the method of the present invention. 2...? PI liquid, 5... Atomized body, 7... Reactor, 10... Linear substrate.

Claims (1)

[Claims] A predetermined amount of a compound containing each of the constituent elements of an oxide superconductor is dissolved in a solvent, and this solution is atomized and supplied to a reactor heated to a predetermined temperature to react, and the atomized material is converted into an oxide. In addition to forming superconductor powder, the oxide superconductor powder produced by creating an electric field in the reactor is electrically charged, and this charged powder is attached to a charged linear substrate on a dust collecting electrode and heat-treated. A method for producing an oxide superconducting wire, characterized by: