JPH0251402A - Process for forming film of precursor for oxide superconductor on carrier surface - Google Patents

Abstract

PURPOSE:To form efficiently a film of a precursor for an oxide superconductor on the surface of a carrier by ejecting flame with a specified angle from running direction and reverse direction of the carrier and depositing the precursor to the carrier. CONSTITUTION:In a process for forming a film of a precursor for an oxide superconductor by heating and reacting starting materials for the oxide superconductor fed into the flame and depositing formed precursor to a carrier running before the frame by the force of ejection of the flame, the flame is ejected with a specified angle to the surface of the carrier from running direction and reverse direction of the carrier. If the ejecting angle of the flame is <20 deg., the force of deposition of the precursor to the surface of the carrier decreases, so the adhesion to the surface of the carrier is insufficient. On the other hand, if the angle is >70 deg., the precursor collides with the carrier more violently causing scattering, so the yield of deposition becomes less, accordingly, it is preferred to set the angle at 20-70 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for efficiently forming an oxide superconductor precursor film on the surface of an adherend such as a substrate.

[Conventional technology]

In recent years, for example, Y-Ba, which exhibits superconductivity above liquid nitrogen temperature, has been developed.
-Cu-0 system (hereinafter abbreviated as Y system) or Bi-3r-C
Oxide superconductors such as a-Cu-0 type (hereinafter abbreviated as Bi type) have been discovered.

These oxide superconductors are much more economical than conventional metal-based superconductors such as Nb+Sn, which exhibit superconductivity at the temperature of liquid He, and are being considered for use in various fields.

By the way, the above-mentioned oxide superconductors are brittle and cannot be plastically worked like metal materials, and in order to process them into molded bodies, an oxide superconductor precursor is applied to the target adherend using a PVD method or a CVD method. A method of forming the film into a film is used.

However, the above-mentioned PVD method and CVD method have a drawback that the film formation rate is slow and the productivity is poor.

For this reason, the raw material for the oxide superconductor is supplied into the flame, and the raw material is oxidized or hydrolyzed in the flame to form an oxide superconductor precursor that travels in front of the flame. A flame-forming method in which the film is deposited on the surface of a substrate or the like is being considered.

In this flame film forming method, the raw material is supplied in the form of fine particles into an oxidizing flame and reacted, so that the raw material is quickly reacted to the oxide superconductor precursor, and at the same time, the reaction product of the precursor is Since it is sprayed onto the adherend using the jet force of the flame, it has good adhesion to the adherend.Furthermore, since the reaction can be carried out in the atmosphere, the equipment can be simplified, and it has excellent workability. There are advantages.

However, in the above-mentioned flame film forming method, as shown in FIG. It bounces off the surface. As a result, the oxide superconductor precursor 4 ejected together with the flame 1 is also thrown up and scattered. In addition to the low adhesion efficiency, a part of this scattered precursor 4 also flies up and scatters on the adherend 3.
The oxide@conductor precursor film 5 remains attached as a foreign substance and reduces the density and crystal orientation of the film 5. Furthermore, there is a problem that the superconducting properties of the oxide superconducting film body 5 are deteriorated by becoming the origin of film cranking.

Furthermore, when the flame is injected perpendicularly to the surface to be adhered, as shown in Figure 2, the deposition width of the precursor is wide, and the peak of the amount of deposition and the peak of the temperature of the surface to be adhered coincide in position. Therefore, there are many parts that are not heated by the flame after deposition, and the density of the formed film decreases. For this reason, there has been a problem in that even if a heat treatment is performed to form a superconductor after film formation, a superconductor having the desired high critical current density (hereinafter abbreviated as Jc) cannot be obtained.

[Means to solve the problem]

The present invention has conducted extensive research in view of the above circumstances, and has found that the adhesion rate of the oxide superconductor precursor to the surface of the adherend, the density and crystal orientation of the formed film, etc. It was found that the spraying angle of the spray onto the surface of the adherend, etc. significantly affects the spraying angle, etc., and as a result of further studies on this point, the present invention was achieved.

That is, in the method of the present invention, a raw material for an oxide superconductor is supplied into a flame, the raw material is heated and reacted, and then the generated oxide superconductor precursor is driven in front of the flame by the jet force of the flame. In the method of forming an oxide superconductor precursor film by depositing it on an adherend, the flame is injected at a predetermined angle to the surface of the adherend from a direction opposite to the traveling direction of the adherend. This is a characteristic feature.

In the method of the present invention, if the injection angle of the flame with respect to the surface of the adherend is less than 20 degrees, the adhesion force of the generated oxide superconductor precursor to the surface of the adherend decreases, and the adhesion force with the surface of the adherend decreases. On the other hand, if the temperature exceeds 70°, the precursor will strongly hit the adherend and scatter, reducing the adhesion rate.
It is preferable to set the angle in the range of 70°, particularly in the range of 30° to 60″.

In the method of the present invention, the raw materials for the oxide superconductor include, for example, Bi-based superconductors such as Bi, Sr, and Ca.
, Cu, for example, acetate, nitrate, halide, or organometallic compound.

In the method of the present invention, each of the above raw material substances is weighed in a predetermined amount, dissolved in a solvent such as water to form a solution, and this /8 liquid is atomized using an ultrasonic nebulizer, or the above raw material substances are weighed in a predetermined amount. The mixed powder is directly vaporized by electromagnetic induction microwave heating and then supplied into the flame.

In the method of the present invention, a multi-tube burner is mainly used to generate the flame, and the atomized or vaporized raw material can be air, 0.5 oz. , N, , Ar, or the like, and ejected from the center tube of the multi-tube burner, this is preferable because uniform supply into the flame can be achieved.

In the method of the present invention, the flame fuel gas contains H.

Any gas can be used, such as gas, butane gas, natural gas, etc.

In the method of the present invention, the oxide superconductor precursor synthesized by an oxidation reaction or hydrolysis reaction using a flame is a composite oxide consisting of YBa, Cu, and O for Y-based oxide superconductors. This composite oxide becomes an oxide superconductor by subjecting it to a predetermined heat treatment in an oxygen-containing atmosphere.

[Effect]

In the method of the present invention, since the flame is applied to the surface of the adherend at a predetermined angle, the flame impinges on the adherend surface is weakened, and as a result, the oxide superconductor precursor reacts and is produced within the flame. The scattering of the substance on the adherend surface is reduced, and as shown in Figure 1, the position between the peak of the amount of the precursor substance adhered to the adherend surface and the peak of the surface temperature of the adherend is increased. If a deviation occurs, and in this state the adherend is moved in the opposite direction to the flame injection direction, that is, in the direction of the arrow shown in the figure, the above precursor will be supplied while the surface temperature of the adherend is low. Therefore, the amount of adhesion increases due to the so-called thermophoresis effect. Further, as the adherend moves, the entire film of the precursor material is heated at the peak temperature of the flame, so that the density and crystal orientation of the formed film are improved.

〔Example〕

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

FIG. 1A is an explanatory view of one embodiment of the method of forming an oxide superconductor precursor film on a substrate according to the method of the present invention.

In the figure, 1 is a flame, 2 is a multi-tube burner in which the raw material is ejected from a central tube, and H2 and 0□ are supplied from an outer layer tube to generate flame 1, and 3 is a 0.5''X10
It is a substrate made of YSZ (Y-stabilized zirconia) of mm'X100IIIn'.

In this example, nitrates of Bi, Sr, Ca, and Cu were used as raw materials for the oxide superconductor, and each nitrate was weighed so that the atomic ratio of Bi:Sr:Ca:Cu was Ill:2. This is dissolved in a nitric acid aqueous solution, this aqueous solution is atomized by an ultrasonic nebulizer (not shown), and then this atomized body is conveyed through the pipe by an Ar air flow and introduced into the burner 2. The above-mentioned atomized material is poured into H2 and 0.0 from the central tube. was supplied into a flame 1 consisting of:

The burner 2 is arranged so that its long sleeve is at an angle of 45 degrees with respect to the surface of the substrate 3, and while the substrate 3 is moved in the direction of the arrow at a speed of 2 m/win, the burner 2 is
A finely powdered oxide superconductor precursor 4 heated and synthesized by the flame 1 ejected from the substrate 3 was ejected and deposited on the surface of the substrate 3 together with the flame 1 at an angle of 45° to form the precursor film 5 .

In the above, the distance between the tip of burner 2 and the surface of substrate 3 is 40
+++n.

Comparative Example 1 The substrate 3 was prepared in the same manner as in Example 1, except that the burner 2 was arranged perpendicularly to the surface of the substrate 3 and the flame 1 was applied perpendicularly to the surface of the substrate 3, as shown in FIG. An oxide superconductor precursor film was formed on the surface.

The oxide superconductor precursor film on each substrate thus obtained was subjected to heat treatment at 860°C for 24 hours in an oxygen atmosphere, and the film thickness, density, crystal orientation, and
The critical temperature (TC) and critical current density (J,) were measured. The results are shown in Table 1.

As is clear from Table 1, the product produced using the method of the present invention (12) has a thicker film than the products produced using the comparative method (3, 4), and has excellent superconducting properties such as J6.

The reason for the thick film thickness of the product manufactured by the method of the present invention is that since the flame was injected obliquely to the substrate surface, the flame hit the substrate surface weakened and there was less scattering of the ejected oxide superconductor precursor; This is because a large amount of the precursor is supplied while the temperature is low, and the amount of the precursor adhered to the substrate surface increases due to the thermophoresis effect. The reason for the excellent superconducting properties is thought to be that the entire formed film is heated at the peak temperature of the flame and becomes highly dense.

In this embodiment, a Bi-based oxide superconductor has been described, but the method of the present invention can also be applied to other oxide superconductors such as a Y-based one to obtain similar effects.

〔effect〕

As described above, according to the method of the present invention, an oxide superconductor precursor film with high density and excellent crystal orientation and crystal structure can be efficiently formed on the surface of an adherend. The method of the present invention has significant industrial effects, such as the fact that by heat-treating the film at a predetermined temperature, it can be made into an oxide superconductor film with excellent superconducting properties of J.

[Brief explanation of the drawing]

Figures 1A and 2A are explanatory views of an embodiment of the method of forming an oxide superconductor precursor film according to the present invention and the conventional method, respectively. FIG. 3 is an explanatory diagram showing the adhesion amount distribution of the precursor and the fundamental degree distribution of the precursor. 1...Flame, 2...Burner, 3...Substrate,
4... Ejected oxide superconductor precursor, 5...
- Formed oxide superconductor precursor film.

Claims (1)

[Claims] A raw material for an oxide superconductor is supplied into a flame, the raw material is heated and reacted, and the generated oxide superconductor precursor is deposited on an adherend running in front of the flame by the jet force of the flame. A method for forming an oxide superconductor precursor film on the surface of an adherend, characterized in that the flame is injected at a predetermined angle to the surface of the adherend from a direction opposite to the traveling direction of the adherend. A method of forming an oxide superconductor precursor film.