JPH0645864B2 - Method of forming ceramic layer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for forming a ceramic layer by spraying a ceramic powder, which will be an oxide-based superconductor, on a substrate.

"Prior Art" In the near term, various oxide-based superconductors have been found that show a high critical temperature (Tc) at which a normal-conducting state changes to a superconducting state above liquid nitrogen temperature.

As a method of manufacturing a superconductor made of such an oxide superconducting material, for example, a method of spraying a powdery superconducting material onto a substrate to form a superconductor layer is known.

[Problems to be Solved by the Invention] However, in such a thermal spraying method, even when thermal spraying is performed in a reduced pressure atmosphere, for example, a forming layer having a sufficiently high theoretical density and being dense and having high mechanical strength is obtained. However, there has been a problem that the theoretical density is not sufficient to obtain sufficient superconducting properties, particularly in the case of producing a superconductor layer.

"Means for Solving the Problem" Therefore, in the method for forming a ceramic layer of the present invention, in spraying ceramic powder such as oxide-based superconductor powder,
The above problems were solved by charging the ceramic powder to either positive or negative polarity and charging the substrate to the opposite polarity to the ceramic powder.

Hereinafter, the method for forming a ceramic layer of the present invention will be described based on an example in which it is applied to the formation of an oxide-based superconductor layer.

First, a substrate 1 is prepared as shown in FIG.
Is connected to the positive electrode side of the DC power supply 2 and the DC power supply 2
The negative electrode side is grounded, so that the substrate 1 is positively charged. Here, as the substrate 1, simple metals, alloys, ceramics, glass and the like are used, but those which are easily charged are more preferably used.

Next, the substrate 1 is preheated and heated to 400 to 550 ° C., and then superconducting powder is sprayed on the surface of the substrate 1 in an electron-rich atmosphere.

Here, the superconductor means the general formula AB-Cu-O (however,
A is the periodic table of Y, Sc, La, Yb, Er, Ho, Dy, etc.
IIIa group element, Bi, Sb etc. periodic table group Vb element and Tl, In etc. periodic table group IIIb group element shows one or more kinds, B is Sr, Ba, Ca etc. periodic table group At least one of the IIa group elements is shown. ) Refers to an oxide-based superconductor. Specific examples of such superconductors include Y-Ba-Cu-O system and Bi-Sr-C.
a-Cu-O system, Tl-Ba-Ca-Sr-Cu-O system, Nd-
Examples thereof include Sr-Ce-Cu-O system. As a method for producing the superconductor powder, for example, in the case of producing a Y-Ba-Cu-O-based superconductor, Y ₂ O ₃ powder, BaCO ₃ powder, and CuO powder are used as Y: Ba: Cu = The mixture is mixed in a ratio of 1: 2: 3 (molar ratio), and treatments such as calcination, pulverization, main calcination, and pulverization are sequentially performed to obtain Y ₁ Ba ₂ Cu ₃ Ox (where x =
7-δ, a method for obtaining a superconductor powder represented by a composition ratio of 0 ≦ δ ≦ 5) or an organic compound containing the elements A, B, and C in the above general formula as a vapor phase source, and these are desired. The organic matter in the gas phase source is instantly decomposed by high heat so that the ratio becomes high, and the A, B and C elements in the material are excited in high heat to be gasified, further sublimated and heated and pulverized. A method of using superconductor powder or the like is adopted.

Further, a plasma spraying method under reduced pressure is preferably adopted for the spraying of the superconductor powder. Here, about 100 Torr or less is suitable as the decompression condition at the time of the above treatment, and the oxygen atmosphere is suitable as the decompression atmosphere. Further, the plasma spraying method is a method in which, for example, a spray gun 3 is used to discharge and spray a melt of superconductor powder, which is generated in direct current plasma generated by heat exchange between a direct current arc and plasma gas, or by high frequency induction. In this method, a superconducting powder is introduced into the high-frequency plasma gas by a carrier gas, and the powder is melted and sprayed onto the substrate 1. Here, oxygen is preferably used as the carrier gas, but an inert gas such as argon or nitrogen may also be used.

In order to create an electron-rich atmosphere, for example, the first
As shown in the figure, a large amount of thermoelectrons are generated on the cathode 5 by being heated by the heater 4 and run toward the facing anode 6, so that the electron rich forms the electron shower 7 of the atmosphere. Then, if the above-mentioned superconductor powder is introduced into and passed through such an electron shower 7, the superconductor powder is negatively charged.

According to such a thermal spraying method, the superconductor powder is made to collide with the positively charged substrate 1 in a negatively charged state, so that the superconductor powder and the substrate 1 are attracted to each other by the Coulomb force, so that the superconductor powder becomes high in speed. It collides with the substrate 1 and strongly adheres to the substrate 1 to increase the theoretical strength of the forming layer up to about 99.9%, so that sufficient mechanical strength can be obtained and a forming layer having excellent superconducting properties can be obtained. .

Note that, in the above example, the example in which thermionic electrons are emitted as the method of generating the electron shower 7 is shown, but other methods such as the method of emitting photoelectrons may be adopted.

Further, in the above example, the substrate 1 was positively charged and the superconductor powder was negatively charged, but conversely, the substrate 1 may be negatively charged and the superconductor powder may be positively charged.

Further, in the above example, the oxide-based superconductor powder was used as the ceramic powder, but the present invention is not limited to this, and another ceramic powder may be used to form the ceramic layer.

"Effects of the Invention" As described above, the method for forming a ceramic layer of the present invention, when the ceramic powder is sprayed to form the ceramic layer on the substrate, the ceramic powder is charged to either positive or negative polarity, and Because the substrate is charged with the opposite polarity to the ceramic powder, the ceramic powder and the substrate are attracted by the Coulomb force, causing the ceramic powder to collide with the substrate at high speed, thereby strongly adhering and theoretical strength of the forming layer. And a ceramic layer having sufficient mechanical strength can be obtained.

Further, if this method is applied to the formation of the oxide-based superconductor layer, it is possible to produce a ceramic layer having sufficient mechanical strength and excellent superconducting properties.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram for explaining an example of the method for forming a ceramic layer of the present invention. 1 ... Substrate, 2 ... DC power supply, 7 ... Electron shower.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoichi Hasegawa 1-5-1 Kiba, Koto-ku, Tokyo Fujikura Electric Wire Co., Ltd. (72) Masayuki Tan Tan 1-5-1, Kiba, Koto-ku, Tokyo Fujikura Electric Wire Co., Ltd.

Claims (1)

[Claims] 1. When spraying ceramic powder to form a ceramic layer on a substrate, the ceramic powder is charged to either positive or negative polarity, and the substrate is charged to the opposite polarity to the ceramic powder. Method of forming ceramic layer.