JPH043998A - magnetic shield plate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a magnetic shield plate, and particularly to a magnetic shield plate that has high strength, can be manufactured at low cost, and has an excellent magnetic shielding effect.

[Conventional technology]

Fields that detect weak magnetism, such as the biomagnetic measurement field that diagnoses diseases based on the magnetism generated by the human body, the magnetic exploration field that searches for mineral resources based on the magnetism generated from rocks, or the field of weak voltage and weak current. In the field of amplifiers, geomagnetism existing in the environment of the object to be detected or the environment of the detector, magnetism generated from various electrical equipment, etc.
In other words, this causes a decrease in the detection accuracy of external magnetism or weak magnetism.

Therefore, in order to accurately measure weak magnetism, it is necessary to completely shield these external magnetisms.

Generally used magnetic shield plates for shielding external magnetism are made of a ferromagnetic material with high magnetic permeability. This magnetic shield plate is effective in reducing relatively strong external magnetism to the earth's magnetic level based on the principle that since ferromagnetic materials easily transmit magnetism, it is difficult for external magnetism to penetrate into the interior surrounded by the magnetic shield plate. However, for example, when measuring weak magnetism such as biomagnetism, it is not very effective when it is necessary to reduce external magnetism to less than 1/100,000 of earth's magnetism. This is because ferromagnetic materials have a residual magnetism phenomenon.

Therefore, a superconducting magnetic shield plate that utilizes the superconducting phenomenon has been developed as a magnetic shield plate that has particularly excellent magnetic shielding effects. This superconducting magnetic shield plate utilizes the Meissner effect of superconducting materials, that is, the diamagnetic effect of superconducting materials that completely eliminates external magnetism.

If this superconducting magnetic shield plate is used, absolute zero magnetic field can be obtained in the space surrounded by the cover.

However, conventional superconducting magnetic shield plates are made of metal superconducting substances such as lead and niobium, and require cooling with liquid helium, which is economically disadvantageous. For this reason, there have been extremely few practical examples of superconducting magnetic shield plates made of metal superconducting materials.

In recent years, Y, Ba2Cu, 0. With the development of oxide superconducting materials such as, it became possible to use liquid nitrogen, which is cheaper than liquid helium.

Conventional oxide superconducting articles include a silver substrate and a coating of Y-Ba-Cu-0-based or B1-5r-Ca-Cu-0-based superconducting material formed on the surface of the substrate. Something is known.

The reason why silver was used for the substrate is that silver does not react with the oxide superconducting substance during the heat treatment of the film, and good superconducting properties can be obtained.

However, the above-mentioned silver substrate and the Y-Ba-Cu-0 based or B15r-based
When a magnetic shield plate is manufactured using an oxide superconducting article comprising a coating of a Ca-Cu-0-based superconducting material, the following problems occur. That is, silver substrates have low strength and are expensive, so it has been difficult to use them as magnetic shield plates.

Therefore, in order to solve the above-mentioned problem, as shown in FIG. 3, a silver intermediate layer 2 is formed on the surface of a copper substrate 1.
It is conceivable to form a coating 3 of superconducting material on the surface of the intermediate layer 2. Hereinafter, this will be referred to as the comparison technique.

However, the above-mentioned comparison techniques have the following problems. That is, during the heat treatment of the film 3, the copper of the substrate 1 and the silver of the intermediate layer 2 are alloyed, and the heat treatment of the film 3 cannot be performed. That is, the coating 3 is converted into a superconducting material coating by heating it to a temperature of about 900°C, but the alloy layer produced by alloying the copper of the substrate 1 with the silver of the intermediate layer 2 The melting point is approximately 780° C., which is significantly lower than the heating temperature of the coating 3. Therefore, when the coating 3 is heated, the alloy layer melts and the coating 3 cannot be heat-treated, making it impossible to obtain good superconducting properties.

Therefore, an object of the present invention is to provide a magnetic shielding plate that has high strength, can be manufactured at low cost, and can provide excellent magnetic shielding effects.

[Means to solve the problem]

This invention includes a copper substrate, a first intermediate layer of platinum formed on the surface of the substrate, a second intermediate layer of silver formed on the surface of the first intermediate layer, and the second intermediate layer formed on the surface of the first intermediate layer. Ln-Ha-Cu-0 system or B1-5r-C formed on the surface of the layer
It is characterized in that it consists of a coating of an a-Cu-0-based superconducting material (Ln represents a rare earth element).

Next, one embodiment of the magnetic shield plate of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing one embodiment of the magnetic shield plate of the present invention.

As shown in FIG. 1, the magnetic shield plate of the present invention includes a copper substrate 4, a platinum first intermediate layer 5 formed on the surface of the substrate 4, and a platinum first intermediate layer 5 formed on the surface of the first intermediate layer 5. silver second
Ln- formed on the surfaces of the intermediate layer 6 and the second intermediate layer 6
It consists of a coating 7 of a Ba-Cu-0-based or B15r-Ca-Cu-0-based superconducting material (wherein Ln represents a rare earth element).

In this way, by forming the second intermediate layer 6 of silver on the surface of the substrate l via the first intermediate layer 5 of platinum, the copper of the substrate 1 and the second intermediate layer, which are generated during the heat treatment of the coating 7, are removed. Alloying of 6 with silver is prevented.

Therefore, by heat-treating the coating 7, the coating 7 can be converted into a coating having good superconducting properties. That is, an excellent magnetic shielding effect can be obtained.

〔Example〕

Next, the present invention will be explained in more detail with reference to examples.

As shown in Figure 2, inner diameter 20mm, length 100mm
.

Platinum powder having an average particle size of 26 to 44 μm is sprayed onto the surface of a copper cylindrical substrate 4 with a wall thickness of 1.0 mm by a known electroplating method to form 2.
A first intermediate layer 5 having a thickness of μm was formed.

Next, silver powder having an average particle size of 26 to 44 μm is sprayed onto the surface of the first intermediate layer 5 by a known electroplating method, as shown in the figure. A second intermediate layer 6 having a thickness of 20μ0 was formed.

Then, on the surface of the second intermediate layer 6, powder of YIBazCusO□-2 having an average particle size of 26 to 44 μl was applied.
By spraying using a known plasma spraying method, a coating 7 made of YIBa2CLlx07-1 having a thickness of 100 μ- was formed on the surface of the second intermediate layer 6, as shown in the figure.

Next, the substrate 1 on which the intermediate layer 2 and the coating 3 have been formed in this way is heated to a temperature of 900°C for 30 minutes in an electric furnace in which the internal atmosphere is maintained in an oxygen atmosphere.
Heated for a minute.

Then, the substrate 4 on which the superconducting material film 7 was formed in this manner was slowly cooled to room temperature in an electric furnace.

As a result of examining the cylindrical magnetically rolled plate manufactured in this way, it was found that the surface of the substrate 4 had good superconducting properties through the first intermediate layer 5 of platinum and the second intermediate layer 6 of silver. , Jc (critical current density) at 77K is 90OA/c
It was found that a coating 7 made of m2 Y, Ba2Cu, 07-, was formed, and an excellent magnetic shielding effect was obtained.

〔Effect of the invention〕

As explained above, according to the present invention, the strength is high;
It can be manufactured at low cost and provides useful effects such as excellent magnetic shielding effect.

Figure 1

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a magnetic shield plate of the present invention, FIG. 2 is a perspective view of a cylindrical magnetic shield plate of the present invention, and FIG. 3 is a magnetic shield plate of a comparative technology. FIG. In the drawings: 1.4 substrate, 2 intermediate layer, 3.7 coating, 5 first intermediate layer, 6 second intermediate layer. Figure 2

Claims (1)

[Claims] (1) a copper substrate, a first intermediate layer of platinum formed on the surface of the substrate, a second intermediate layer of silver formed on the surface of the first intermediate layer, and the second intermediate layer Ln-Ba-Cu-O system or Bi-Sr-Ca-C formed on the surface of
1. A magnetic shielding plate comprising a coating of a u-O-based superconducting material (Ln represents a rare earth element).