JPH0222163A - Production of diamagnetic material and diamagnetic material - Google Patents

Abstract

PURPOSE:To obtain a diamagnetic material having excellent strength and dimensional accuracy by coating powder or granule of superconducting material with a covering material, packing the coated material into a mold, melting the covering material, cooling and solidifying. CONSTITUTION:A powder or granular raw material is primarily ground, mixed, calcined, secondarily ground, mixed and sintered to give powder or granule (A) of superconducting material containing Y or Bi. Then the component A and (B) a covering material (e.g., fluororesin) are fed from a feeder 19 to a treating chamber 3 of a bottomed cylindrical casing 4, the casing 4 is rotated by a driving gear 5 through a revolving shaft 2, the component A is coated with the component B, the raw material is pressed against the inner peripheral face 4a of the casing, pulverized by grinding pieces 9a relatively rotating based on the casing 4, simultaneously blended by raking pieces 9b while stirring, sent by air flow and recovered by a collector 15 to give a diamagnetic raw material. Then the raw material is packed into a mold, heated to melt the component B and cooled to solidify the component B.

Description

DETAILED DESCRIPTION OF THE INVENTION: Industrial Application Field The invention relates to a method for producing a diamagnetic material to form a molded product from a finely powdered raw material, and a diamagnetic material obtained by the method.

[Prior art] Conventionally, P V
By mixing binders such as A, molding the mixture, and sintering the molded product, we manufacture diamagnetic materials in appropriate shapes suitable for the purpose, such as those for bearings that utilize the Meissner effect. jko.

[Problem to be solved by the invention]

However, since the calcined fine powder raw material is molded with a binder and then sintered, the heat shrinkage and thermal distortion associated with sintering are large, and it is difficult to maintain the precision of the shape and dimensions of the diamagnetic material, making it complicated. The drawback is that it is not possible to industrially manufacture diamagnetic material with a specific shape.

The purpose of the present invention is to easily ensure the accuracy of the shape and dimensions of diamagnetic materials, and to easily mass-produce even diamagnetic materials with complex shapes. The object of this invention is to make the means for achieving this advantageous in terms of the performance, strength, and production efficiency of the diamagnetic material.

[Means to solve the problem]

The characteristic means of the first invention is to sinter a fine powder raw material of a superconductor to produce a granular material of a superconducting material, and to coat the granular material of a superconducting material with a coating material. The covered granules of superconducting material are filled into a mold and heated to melt the coating material, and then the granules of superconducting material in the mold and the coating material are cooled to remove the coating. The purpose is to make molded products by cooling and hardening materials, and its functions are as follows.

[For production]

In other words, by sintering the fine powder raw material before molding to create sufficiently heat-shrinked superconducting material powder, and by creating a molded product by heat-melting and cooling hardening the coating material, heat-shrinkable The shape and dimensions of the diamagnetic material can be easily and reliably adjusted to a predetermined value by sufficiently suppressing heat distortion and thermal distortion, and diamagnetic materials with complex shapes can be easily mass-produced.

[Means to solve the problem]

The characteristic means of the second invention is to sinter a fine powder raw material of a superconductor to produce a Y-containing superconducting powder, and coat the superconducting powder with a melting point of 450°C or less. The powder of the superconducting material covered with the coating material is filled into a mold and heated at 550°C or less to thermally melt the coating material, and then the superconducting material in the mold is The purpose of this method is to cool the powder and granular material and the coating material, and to cool and harden the coating material to produce a molded product, and its function is as follows.

[For production]

In other words, it is necessary to sinter the fine powder raw material before molding to create a powdered material of Y-containing superconducting material, and to have a melting point of 450°C.
By heating the superconducting material powder covered with the following coating material at 550 degrees Celsius or less, and creating a molded product by heating and melting the coating material and cooling and hardening, thermal shrinkage and thermal distortion can be sufficiently suppressed. The shape and dimensions of the diamagnetic material can be easily and reliably made into a predetermined shape, and diamagnetic materials with complex shapes can be easily mass-produced.

To explain further, the powder of the superconducting material is sufficiently heat-shrinked during the sintering process before molding, and the heating temperature for molding is 550°C, which is sufficient for heating and melting the low-melting point coating material.
or less, and at that heating temperature, the crystal structure of the Y-containing superconducting material does not change to a tetragonal crystal structure that loses superconductivity,
It is maintained as an orthorhombic crystal that exhibits superconductivity, and therefore thermal shrinkage and thermal distortion during molding can be sufficiently suppressed.
Moreover, the superconductivity of the Y-containing superconducting material can be maintained well.

Incidentally, in order to obtain such an effect, it is conceivable to simply stir and mix a low melting point substance similar to that of the coating material into the superconducting material powder and then heat and cool it to form it as described above. However, since the mixing becomes non-uniform and it is practically impossible to disperse the low melting point substance evenly and in appropriate amounts over a large amount of the superconducting material powder, the superconducting material in the molded product is The distribution of the powder and granules is uneven, and the Meissner effect is due to the B-sha of the molded product.

There are different drawbacks, and the disadvantage is that parts of the superconductor powder and granules tend to be insufficiently bonded with low melting point substances, resulting in strength defects. Therefore, there is a drawback that the heating and melting treatment time tends to be long.

However, as in the second invention, if each powder or granule of the superconducting material is covered with a coating material, the distribution of the superconducting material and the coating material can be reliably uniformized during molding, and the coating material can be applied evenly. Moreover, it can be dispersed in appropriate amounts, the Meissner effect is stably exhibited throughout the product, and molded products with excellent strength can be manufactured easily and reliably and efficiently by speeding up the heating and melting process of the coating material.

[Means to solve the problem]

The characteristic means of the third invention is to sinter a fine powder raw material of a superconductor to produce powder of a B1-containing superconducting material, and coat the powder of the superconducting material with a melting point of 800°C or less. The superconducting material covered with the coating material is filled into a mold and heated at 800°C or less to melt the coating material, and then the superconducting material in the mold is The purpose of this method is to cool the powder and granular material and the coating material, and to cool and harden the coating material to produce a molded product, and its function is as follows.

[For production]

In other words, similarly to the second invention, producing a powder of a Bi-gold-containing superconducting material that has been sufficiently heat-shrinked by sintering before forming;
In addition, powdered superconducting material covered with a coating material with a melting point of 800°C or less is heated at a temperature below 800°C where good superconductivity is exhibited, and the coating material is heated to melt and cooled to harden to form a molded product. By manufacturing the diamagnetic material, heat shrinkage and thermal distortion can be sufficiently suppressed, the shape and dimensions of the diamagnetic material can be easily and reliably made into a predetermined shape, and diamagnetic materials with complex shapes can be easily mass-produced.

Furthermore, for the same reason as in the second invention, the Meissner effect can be stably exhibited throughout the entire body, and molded products with excellent strength can be produced easily and reliably and efficiently by speeding up the heating and melting process of the strength material. Can be manufactured well.

[Effects of the invention] As a result, the accuracy of the shape and dimensions of the diamagnetic material can be easily and reliably improved, and diamagnetic materials with complex shapes can be easily mass-produced.
A method for producing a diamagnetic material which is excellent in terms of Meissner effect and strength can be produced easily, reliably and efficiently, and which is extremely excellent overall has been obtained.

By using this manufacturing method, we can produce a diamagnetic material that has the optimal shape and dimensions depending on the application, exhibits an excellent Meissner effect, is highly reliable in terms of strength, and has an extremely high overall performance at a sufficiently low cost. now available.

〔Example〕

Next, examples will be shown.

As shown in Figure 1, 1 min of powdery raw material for superconductor is weighed, the weighed powdery raw material is subjected to primary pulverization and mixing treatment in a dry grinding mixer, and the fine powdery raw material obtained through the second pulverization and mixing treatment. The powdery raw material obtained by the calcining process is subjected to secondary pulverization and mixing treatment using a dry grinding and mixing device, and the fine powdery raw material obtained by the secondary pulverization and mixing process is sintered to produce Y or Bi. Create powder and granular material of superconducting material containing

Calcination treatment is generally performed by heating at about 400°C for about 2 hours, then heating at about 900°C for about 4 hours for superconducting materials containing Y, and heating at about 800°C for about 16 hours for superconducting materials containing B1. .

For superconducting materials containing Y, the sintering process is generally performed at a temperature of 900 to 9
After heating at about 30°C for about 12 hours, it is slowly cooled at about 100°C/hr, then heated at about 520°C for about 5 hours, and then slowly cooled at about 100°C/hr. In addition, a superconducting material containing B1 is heated at 800 to 890°C for 70 to 200 hours and then slowly cooled.

An appropriate amount of the coating material is added to the granular material of the superconducting material, and the mixture is coated using a dry grinding and mixing device to produce a diamagnetic material material in which the granular material of the superconducting material is covered with the coating material.

The coating material is selected from suitable materials such as fluororesin, resin powder, Cu(7) fine powder, flakes, and the like. However, when using a diamagnetic material, choose one that does not become brittle at low temperatures, does not come into contact with the superconducting material, and does not contain water.The mixing ratio of the coating material should be from a few percent to several tens of percent. It is.

And for superconducting materials containing Y: the melting point is 450
A coating material with a temperature below 300°C is used.

Furthermore, for superconducting materials containing Bi, the melting point is 800°C.
Hereinafter, a coating material having a temperature of 400° C. or lower is preferably used.

Note that the melting point of Cu decreases as it becomes finer powder or flakes.
When the thickness is on the order of 0-2 μm, sintering is performed at 200-400°C. Therefore, it is used in the form of fine powder or thin slices of a thickness suitable for a predetermined melting point.

The diamagnetic raw material may be obtained by heat-sealing a large number of fine powder or flaky coating materials (B) to a superconducting material powder (8) by grinding, as shown in Figure 2 (A). As shown in FIG. 2(b), a thin layer of the coating material (B) may be formed on the entire surface of the superconducting material powder (A) by thermal fusion through grinding.

Next, the diamagnetic raw material is filled into a mold and heated, and the coating material (B
) is thermally melted, and then the superconducting material powder (A
) and the coating material (B), and the coating material (B) is cooled and hardened to produce a diamagnetic molded product.

For superconducting materials containing Y, the heating temperature of the diamagnetic raw material filled in the mold is such that the crystal structure of the powder (A) of the superconducting material does not change to a tetragonal crystal structure and exhibits superconductivity. The superconductor powder (8) and the coating material (B) are melted to a sufficient degree for molding.
The temperature should be selected appropriately depending on the type of B), and set at 550° C. or lower for superconductors containing Y. In addition, for superconducting materials containing Bi, the melting temperature is 80℃ lower than 850℃.
Set below 0℃.

The above-described grinding and mixing device will now be described in detail with reference to FIGS. 3 and 4.

A bottomed cylindrical casing (4) forming a processing chamber (3) is concentrically attached to the upper end of a vertical rotating shaft (2) attached to a base (1), and an electric motor (5a) and a variable speed Machine (5b
), etc., is interlocked with the lower end of the rotating shaft (2), and the casing (4) is driven at high speed so that the powdery raw materials inside the casing (4) are pressed against the inner circumferential surface (4a) of the casing by centrifugal force. The casing (4) is designed to rotate and to obtain an appropriate centrifugal force depending on the properties of the raw material.
The rotation speed of the rotor is adjustable.

The casing (4) is surrounded by a cover (7), a fan (12) is connected to the bottom of the casing (4), and the cover (7) is surrounded by a fan (12).
) is configured to suck outside air through an intake port (13) formed in the casing (4) and cool the casing (4) with the sucked outside air;
In addition, a conveyance channel (
10) is configured to be introduced as a gas for transporting fine powder raw material. In addition, the fine powder raw material is transferred from the processing chamber (3) to the cover (7).
) side, the upper center of the casing (4) is opened to form an overflow outlet (11) for the raw material.

While fixed to the upper end of the rotating shaft (2) and the fellow rotating shaft (Ba), a conical part (8C) is formed at the upper center and a clever support (Bb) is provided inside the casing (4). be.

A grinding piece (9a) that compresses and shears the raw material in cooperation with the inner circumferential surface (4a) of the casing, and a scraping piece (9b) that stirs, mixes and disperses the raw material are placed in an appropriate direction in the rotational direction of the casing (4). They are arranged at intervals and attached to the tip of the support (Ba) and placed in the processing chamber (3).

The grinding piece (9a) has an inclined surface formed so that the gap with the casing (4) becomes narrower in the direction of rotation of the casing (4), and the scraping piece (9b) is attached to the casing (4). ) is formed in a wedge-like or comb-like shape such that the gap between the casing (4) becomes wider in the direction of rotation of the casing (4), and its working surface gradually becomes wider.

The rotating shaft (Ba) is interlocked with the drive device (5), and the grinding pieces (9a) and the scraping member rob) are rotated relative to the casing (4) at a constant speed difference, and the grinding pieces (9a) are rotated. The structure is such that agitation and mixing can be performed using the fine grains and scraping pieces (9b).

Inside the rotating shaft (3a): 2. Support (Bb), grinding piece (9a)
), a passage (27) is formed through which a heating or cooling medium flows into the scraping piece (9E]), and a rotary joint) is formed.
(24) connects the passage (27) to the medium storage tank (2).
6).

A pipe (14) is provided in the center of the cover (7) to form a path (6) for supplying the raw material from the feeder (19) toward the conical portion (Bc) of the support (Bb). An air blower (1
8) is connected to the path (6), and a jacket (25) is provided around the cover (7) to allow heating or cooling medium from the tank (26) to pass therethrough.

The collector (15) and the exhaust fan (16) are connected to the flow path (1) in that order.
0), and a rotary feeder (17) is provided at the outlet of the collector (15) to collect the fine powder raw material.

In short, the casing (4) is rotated at high speed, and the powdery raw material from the feeder (19) is delivered to the inner peripheral surface of the casing (
4a) by centrifugal force, and the crushed pieces (9) rotating relative to the casing (4) are added to the raw material layer formed by the pressing
a) and the scraping piece (9b), the grinding piece (9a) finely pulverizes the raw material, and the scraping piece (9b) stirs and mixes the raw material, making it sufficiently fine and uniformly mixed. The fine powder raw material is transported by air current and collected by the collector (15).

[Another example]

Next, another embodiment will be described.

The raw materials can be appropriately selected in terms of type, mixing ratio, particle size, etc. Depending on the raw materials, the calcination treatment and the secondary pulverization and mixing treatment may be performed multiple times. Further, depending on the raw materials, the calcination treatment and the secondary pulverization and mixing treatment may be omitted, and the sintering treatment may be performed after the secondary pulverization and mixing treatment.

The specific configuration of the dry grinding and mixing device can be changed as appropriate. For example, the rotational axis of the casing (4) may be tilted or turned sideways, or the grinding pieces (9a) and scraping pieces (9b) may be placed in the casing (4). The grinding piece (9a) and the scraping piece (9b) can be biased by fluid pressure or a spring within a range where they do not come into contact with each other, or the rotation of the grinding piece (9a) and the scraping piece (9b) can be stopped.
It is possible to appropriately change the shape, material, number of installations, etc., or to configure the collector (15) to return and supply the fine powder to the casing (4) so as to perform batch processing.

How to set the temperature conditions in the calcination treatment and sintering treatment can be appropriately selected depending on the type of raw material.

The coating material can be appropriately selected in terms of type, melting point, and mixing ratio.

The apparatus used in the coating process can be appropriately selected from known coating apparatuses, and may be, for example, a spray drying system, a fluidized drying system, a mixed granulation system, or the like.

The purpose and shape of the diamagnetic material are not limited.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a flow sheet;
Figure 2 (1) ('J') is a conceptual diagram of the raw material, Figure 3 is a conceptual diagram of the grinding and mixing device, and Figure 4 is a sectional view taken along the line ■-■ in Figure 3. (A) ...Superconducting powder, (B)...
...Covering material.

Claims (6)

[Claims] 1. The fine powder raw material of the superconductor is sintered to produce a superconducting material powder (A), the superconducting material powder (A) is coated with a coating material (B), and the coating material ( The superconducting material powder (A) covered with B) is filled into a mold and heated to melt the coating material (B), and then the superconducting material powder (A) covered with the superconducting material in the mold is heated. (A) and coating material (
A method for manufacturing a diamagnetic material in which a molded product is produced by cooling B) and cooling and hardening the coating material (B). 2. By sintering fine powder raw material of superconductor containing Y, Y
The superconducting material powder (A) is coated with a coating material (B) having a melting point of 450°C or less, and the superconducting material powder (A) is coated with the coating material (B). The superconducting material powder (A) is filled into a mold and heated at 550°C or lower to form the coating material (A).
B) is thermally melted, and then the superconducting material powder (A) in the mold and the coating material (
A method for manufacturing a diamagnetic material in which a molded product is produced by cooling B) and cooling and hardening the coating material (B). 3. By sintering the fine powder raw material of superconductor containing Bi,
A granular material (A) of a superconducting material containing Bi is produced, and the granular material (A) of the superconducting material is coated with a coating material (B) having a melting point of 800°C or less. The covered superconducting material powder (A) is filled into a mold and heated at 800°C or less to form the covering material (A).
B) is thermally melted, and then the superconducting material powder (A) in the mold and the coating material (
A method for manufacturing a diamagnetic material in which a molded product is produced by cooling B) and cooling and hardening the coating material (B). 4. A diamagnetic raw material obtained by covering powder (A) of a superconducting material with a coating material (B) is heated in a mold to coat the coating material (B).
) A diamagnetic material formed by hot-melting and then cooling and hardening. 5. Powder (A) of Y-containing superconducting material has a melting point of 450
A diamagnetic material formed by molding a diamagnetic material material covered with a coating material (B) at a temperature of 550.degree. 6. Powder (A) of Bi-containing superconducting material has a melting point of 80
A diamagnetic material formed by molding a diamagnetic raw material covered with a coating material (B) at a temperature of 0° C. or lower, heating the coating material (B) in a mold to a temperature of 800° C. or lower to melt the coating material, and then cooling and hardening the material.