JPH02204309A - Production of film of precursor of oxide superconductor - Google Patents

Abstract

PURPOSE:To keep the amt. of mist of a soln. of starting material fed into a flame invariable and to improve the quality of a film by continuously measuring the level of the soln. in an ultrasonic atomizer and controlling the flow rate of a carrier gas in accordance with the measured level. CONSTITUTION:A soln. 1 of starting material for an oxide superconductor is poured into an ultrasonic atomizer 2 and atomized. The resulting mist 3 is continuously fed into a flame 6 with a carrier gas through a burner 5. The level of the soln. 1 in the atomizer 2 is continuously measured with a float 11, etc., and transduced into an electric signal. This signal is sent to a flow rate controller and the flow rate of the carrier gas is controlled. The mist 3 is brought into a chemical reaction and a produced precursor 8 of the oxide superconductor is stuck on a substrate 7 travelling in front of the flame 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing an oxide superconductor precursor film.

(Prior Art and its Problems) Recently, as is well known, an oxide superconductor that can be used at liquid nitrogen temperatures has been discovered, and research into the application of this new superconductor is being actively conducted at home and abroad.

However, since such oxide superconductors are brittle, it is difficult to process them into wire rods, etc., and special processing methods such as powder sintering are being researched. However, this powder sintering method requires a long manufacturing process, and it is difficult to manufacture long materials.

For this reason, the raw material for oxide superconductors is dissolved in a solvent, this solution is atomized and supplied into a flame, and the flame causes a chemical reaction to form a precursor for oxide superconductors. A spray heating reaction method has been proposed in which a film is deposited on a substrate placed in front of the substrate.

This method is highly productive because the process is short and the reaction rate is fast, and it is said that long materials can be easily produced by running the substrate and continuously depositing the oxide superconductor precursor on it. There are advantages.

However, according to this manufacturing method, there is a problem in that the properties of the obtained oxide superconductor precursor film deteriorate over time, especially when manufacturing a long material.

[Means and effects for solving the problem] In view of the above situation, the present invention has conducted intensive research and has determined that the cause of the deterioration of the properties of the oxide superconductor precursor film produced by the spray heating reaction method over time has been determined by the present invention. As the raw material solution in the sonic atomizer decreases, the amount of atomized raw material solution supplied into the flame decreases, and the drop in flame temperature due to evaporation of the solution in the flame decreases, resulting in an increase in flame temperature and a predetermined level. It was discovered that this phenomenon occurs because the oxide superconductor precursor material is decomposed when heated above the temperature, and the present invention was completed after further research into improving this phenomenon.

That is, in the present invention, a predetermined amount of a raw material that can be made into an oxide superconductor is dissolved in a solvent, this raw material solution is put into an ultrasonic atomizer to atomize it, and this atomized raw material solution is placed on a carrier gas and a burner is turned on. In a method for producing an oxide superconductor precursor film, the atomized raw material solution is chemically reacted by being continuously supplied into a flame through a flame, and the produced oxide superconductor precursor is deposited on a substrate placed in front of the flame, By continuously detecting the liquid level of the raw material solution, converting it into an electric signal and transmitting it to a carrier gas flow rate controller, and controlling the flow rate of the carrier gas in conjunction with the liquid level of the raw material solution, This method of producing an oxide superconductor precursor film is characterized in that the amount of the atomized raw material solution supplied into the flame is kept constant.

In the method of the present invention, for example, the liquid level of the raw material solution in an ultrasonic atomizer is continuously detected by a method such as magnetically or optically, and this is converted into an electric signal, which is used to control the flow rate of the carrier gas. The flow rate of the carrier gas is increased to compensate for the decrease in the amount of atomized raw material solution generated due to the reduction of the raw material solution in the ultrasonic atomizer by transmitting the information to the controller (MFC).
Since the amount of atomized raw material solution supplied into the flame is always constant, the heating temperature by the flame is maintained at a predetermined temperature from then on, thereby producing a high-quality oxide superconductor precursor film with an appropriate composition. It is something that can be formed. In addition, in the method of the present invention, when the raw material solution is replenished, the amount of atomized raw material solution supplied into the flame can be kept constant by controlling the flow rate of the carrier gas to be low. In addition, in the method of the present invention, the increase or decrease of carrier gas has almost no effect on the flame temperature, Vf! This was done with recognition.

In the method of the present invention, the substrate is made of a material that is non-reactive to the extent that heating contact with the raw material does not substantially cause harm and is highly heat resistant, such as a noble metal such as Ag, Au, or PL, or a noble metal such as MgO, ZrO, or BaAL. (L, Fe, Ni, Co or alloys thereof coated with ceramics such as BaZr0., metals such as Ag, ceramics such as MgO, such as stainless steel (SUS), Fe-Ni system,
Ni-Cu alloy, Ni-Cr-Fe alloy, or Aj!
Materials such as □03, glass, AlN5BN, S i C, and C are used.

In the method of the present invention, raw materials that can be used as oxide superconductors include oxides generated during the manufacturing process of oxide superconductors, such as Y-Ba-Cu-0-based oxide superconductors. 0. ,Bao,CuO1BaCuO,
, YBaCuOs, YBazCulO, etc.
Any substance can be used as long as it is blended and mixed so that the atomic ratio of :Ba:Co becomes t:Z:a.

In addition, the oxide superconductor precursor film obtained by atomizing the above-mentioned raw material into a solution and heating it with flame refers to the oxide superconductor precursor film that is obtained by subjecting it to a predetermined heat treatment in an oxygen-containing atmosphere.
By replenishing t and adjusting the crystal structure, it becomes an oxide electromotive conductor.

〔Example〕

Next, the method of the present invention will be explained in detail using examples.

Embodiment 1 FIG. 1 is an explanatory view of a main part showing an embodiment of the method of manufacturing an oxide superconductor precursor film according to the present invention.

In the figure, 1 is a raw material solution, 2 is an ultrasonic atomizer for atomizing the raw material solution 1, 3 is an atomized raw material solution, and 4 is spray heating for chemically reacting the atomized raw material solution 3 into a precursor substance. It is a reactor.

Starting materials include Y (CHsCOO)s' 4Hid, Ba
(CHsCOO)t-HzOlCu (CHsCOO)
Using i・H and O, each compound is converted into Y:Ba:Cu=1
: Weigh it so that the ratio is 2:3, and add it to water with YBa and Cu.
, was dissolved at 0.04 mol/l, and acetic acid corresponding to 5% by volume of the total was added thereto to obtain a raw material solution 1. Next, this raw material solution 1 was placed in an ultrasonic atomizer 2 and atomized. ,
This atomized raw material solution 3 was passed through N8 at a flow rate of 0.601/win.
It is carried in a gas flow into a burner 5 installed in a spray heating reaction device 4, heated by an oxyhydrogen flame 6 formed in front of the burner 5, and chemically reacted into an oxide superconductor precursor. The precursor is supplied from the uncoiler 17.
0.2 tm"×5" heated to 900°C by a heating device (not shown) running at a speed of 0.
An oxide superconductor precursor film 8 having a thickness of 100 μm was formed by adhering it onto the PT tape 7 .

In the above, the flow rate of N8 gas was automatically controlled as described below. That is, a magnetic float 11, which has a floating ball 9 and a rod-shaped part 10 containing a magnet, is floated on the raw material solution l in the ultrasonic sprayer 2, and the rod-shaped part 10 of this float 11 is attached above the ultrasonic sprayer 2. The current flowing through the coil 12 changes as the position of the float rod-shaped portion 10 rises and falls. and transmits it to the MFC as a carrier gas flow rate correction signal.
The gas flow rate was automatically controlled in conjunction with the liquid level of the raw material solution 1.

Then, the oxide superconductor precursor film 8 deposited on the PT tape 7 was heated to 400°C with O! The precursor film 8 was passed through a heating reactor 13 in an airflow atmosphere to chemically react the oxide superconductor film to form an oxide superconductor 14.Then, the oxide superconductor 14 was transferred to a molten resin tank 15.
Then, it was passed through a baking furnace 16 and coated with a resin to perform moisture-proofing treatment, and then wound around a coiler 27.

In this way, the operation was continued for 5 hours to produce 3 m of Y-based oxide superconducting conductor.

Comparative Example 1 An oxide superconducting conductor was manufactured by the same method as in Example 1 except that the flow rate of N2 gas was kept constant.

For each oxide superconducting conductor obtained in this way, three locations were sampled in the longitudinal direction to determine the critical temperature (T,
) and critical current density (Jc) were measured. The result is the first
Shown in the table.

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

As is clear from Table 1, the products produced by the method of the present invention showed high values of Tc and Jc over the entire length.

On the other hand, in the comparative method product, Tc and Jc decreased over time. This is because the flow rate of the carrier gas was kept constant, even though the raw material solution in the ultrasonic atomizer decreased over time and the amount of atomized raw material solution generated decreased accordingly. This is because the amount supplied into the flame decreased, and as a result, the flame temperature rose, and the precursor film was heated to a predetermined temperature or higher and decomposed.

In Example 1, a magnetic method was used to convert the liquid level of the raw material solution into an electrical signal, but other methods such as an optical method as shown in FIG. 2 may also be used. In this optical method, a plurality of receivers and light emitting elements 18 and 19 are arranged facing each other above the ultrasonic atomizer 2, and the receiver,
The upper part of the float 21 suspended in the raw material solution 1 is positioned between the light emitting elements 18 and 19, and changes in the amount of light received due to the vertical movement of the float 21 are transmitted as electrical signals to the MFC via the CPU to control the carrier gas flow rate. It is something.

[Effects] As described above, according to the method of the present invention, a high-quality oxide superconductor precursor film can be obtained over the entire length, and this precursor film can be subjected to a prescribed heat treatment in an oxygen-containing atmosphere. Therefore, it can be made into an oxide superconducting conductor having excellent superconducting properties such as Tc and Je, and has a remarkable industrial effect.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the main parts showing one embodiment of the method of the present invention;
The figure is a partial explanatory diagram of the vicinity of an ultrasonic atomizer showing another embodiment of the method of the present invention. l... Raw material solution, 2... Ultrasonic atomizer, 3...
- Atomized raw material solution, 4... Spray heating reaction device, 5.
... Burner, 6... Oxyhydrogen flame, 7... Substrate,
8... Oxide superconductor precursor film, 11.21
...Float, 12...Electric coil, 14
...Oxide superconductor.

Claims (1)

[Claims] A predetermined amount of a raw material that can be made into an oxide superconductor is dissolved in a solvent, and this raw material solution is placed in an ultrasonic atomizer to atomize it,
This atomized raw material solution is placed on a carrier gas and continuously fed into a flame via a burner to cause a chemical reaction in the atomized raw material solution, and the generated oxide superconductor precursor is deposited on a substrate placed in front of the flame. In the method for producing an oxide superconductor precursor film, the liquid level of the raw material solution is continuously detected, and this is converted into an electrical signal and transmitted to a carrier gas flow rate controller to control the flow rate of the carrier gas. A method for producing an oxide superconductor precursor film, characterized in that the amount of the atomized raw material solution supplied into the flame is maintained constant by controlling it in conjunction with the liquid level of the solution.