JPH10140215A - Method and apparatus for production of amorphous powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent contamination of a starting material at the time of production of an amorphous powder and to enable arbitrary regulation of rapid cooling conditions and flat state by a relatively simple apparatus. SOLUTION: A large amount of impulse current is applied to a wire shaped metallic starting material disposed in an atmosphere of a cooling medium of nonoxidizing gas, such as gaseous nitrogen, argon, and hydrogen, to form a molten part, and the molten part is scattered, in a state of high-speed fine grains, in the atmosphere by the wire explosion occurring in the inner part of the starting material by the application of the large amount of impulse current and the high-speed fine grains are allowed to collide against a cooling body 41. The starting material is strung between electrodes 23 and can keep its purity without causing contamination by a melting atmosphere as in the case of melting in a state of contact with a contamination source such as a crucible. Moreover, this starting material is scattered, in a state of high-speed fine grains, in the cooling atmosphere by the wire explosion and further allowed to collide with the surface of a cooling body, by which cooling conditions for making amorphous can bee easily obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of amorphous fine powder which can be suitably used, for example, for magnetic materials.

[0002]

2. Description of the Related Art In order to produce this amorphous powder, Int. Co., Ltd. replaces the conventional atomizing method in which a high-speed fluid impinges on and sprays a high-speed fluid onto a molten metal stream having a diameter of several mm.
J. Rapid Solidification 4
(1989) 181. Of molten alloy by gas spraying at high speed (300-1000 m / s) and colliding it with a cooling body rotating at high speed to obtain flattened amorphous powder, or February 1996 Foundation The super-quenching method disclosed in the “Amorphous / Nanostructure Control Process” presented at the forum “Prospects for Future Metallic Materials” hosted by the Next Generation Metals and Composites Research and Development Association (RIMCOF) is known. In this method, a molten metal stream that has been atomized collides with a water stream that rotates at a high speed in a cylindrical container, thereby simultaneously pulverizing and rapidly cooling the molten droplet.
Ultra-rapid cooling is achieved because the vapor film on the surface of the powder injected into the rotating water stream is instantaneously peeled off.

In any of the conventionally proposed methods for producing an amorphous powder, a starting material is used by dissolving and atomizing a metal as a starting material. There is a disadvantage that the composition of the starting material is limited due to segregation depending on the composition.

[0004]

The problem to be solved by the present invention is that the starting material is not contaminated during the production of the amorphous powder, and the production of the amorphous powder is performed by a relatively simple apparatus.
It is to be able to arbitrarily adjust the quenching condition and the flat state.

[0005]

According to the method for producing an amorphous powder of the present invention, a high impact current is applied to a starting material of a linear metal arranged in an atmosphere of a cooling medium to form a molten portion. In addition, the molten portion is scattered into the atmosphere in the form of high-speed fine particles due to a linear explosion generated inside the starting material by the application of a large impact current, and the high-speed fine particles collide with the cooling body.

[0006] A linear material as a starting material is several mm in length.
Those having a diameter of up to a diameter can be suitably used, and the cross-sectional shape thereof is not particularly limited. Further, as a form thereof, a thin tube filled with powder can be used.

As the scattering atmosphere, a non-oxidizing gas such as nitrogen, argon or hydrogen gas can be used.
Among them, hydrogen gas is desirable because it has a large heat absorption capacity and a high cooling capacity.

In the case of the present invention, since the starting material is wired between the electrodes and is not contaminated by the melting atmosphere as in the case where it is melted in contact with a contaminant source such as a crucible, its purity is high. In addition, high-speed fine particles are scattered in a cooling atmosphere in the form of high-speed particles due to a linear explosion, and further collide with the surface of the cooling body. Therefore, rapid cooling conditions for amorphization can be easily obtained. Then, the molten particles are recovered by the powder recovery unit without adhering to the cooling body.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As a cooling body for colliding scattered molten metal particles, the collision angle with respect to the particle collision direction is ± 45 degrees from the vertical position in consideration of the separation of the particles from the cooling surface. It can be adjusted to an angle of about °. Thereby, the flatness of the obtained particles can be controlled.

As described above, it is not always necessary to rotate the cooling body as in the prior art, and the structure of the apparatus is simplified accordingly.

Further, in order to completely cool the scattered high-speed molten metal particles, the distance of the raw material to the surface of the cooling body depends on the magnitude of the large impact current and the cooling atmosphere. When the cross section is circular, it is desirably 30 to 60 times the average diameter.

According to the present invention, a thin flat amorphous powder having a long diameter aspect ratio of 150 to 200 and a film thickness of 0.5 to 2 μm is obtained.

[0013]

【Example】

Embodiment 1 FIG. 1 shows an apparatus for carrying out the method for producing an amorphous powder of the present invention. This apparatus has a closed vessel 1 capable of flowing an atmosphere gas having a large heat absorption capacity such as hydrogen.
A support portion 2 for the linear raw material, a power supply unit 3 for supplying the linear raw material, a cooling unit 4 for cooling the scattered raw material, and a powder collecting unit 5 for collecting the scattered raw material. Having. As the atmosphere gas, a gas such as hydrogen, nitrogen, or argon can be used. Among them, hydrogen gas is convenient because its cooling effect is large.

The support portion 2 for the linear raw material is provided with a wire 2 supplied by a wire hopper 21 located at the top of the closed container.
2 comprising an electrode 23 supporting

The power supply unit 3 comprises an inter-electrode distance adjusting mechanism 31 located outside the closed vessel, a coaxial output cable 32 supported by the mechanism, and an electrode 23 receiving an energized output from the cable 32.

The cooling body part 4 has a cooling body 41 in which the collision angle of the molten particles and the vaporized particles generated by the discharge explosion by the application of the high impact current applied to the wire 22 is adjusted.
Having.

Further, a powder collecting section 5 is provided at the lowermost end of the lower inner surface of the closed container inclined in a funnel shape so that the cooling powder dropped from the surface of the cooling body can be easily collected.
One.

FIG. 2 shows details of the support portion 2 and the cooling body portion 4 of the linear raw material shown in FIG. 1 in which the molten portion of the raw material is scattered in the form of high-speed fine particles and impinges on the surface of the cooling body. FIG. 3 is a diagram showing a cross section taken along line AA of FIG.

As shown in FIG. 2, the cooling body 41 is formed of a thermally conductive plate material such as a copper plate, and has upper and lower inner surfaces 42,
43 to 45 ° or less with respect to the horizontal plane, that is,
Melted and scattered matter 24 from the wire 22 supported between the electrodes 23
Is formed so that the collision angle with the inner surfaces 42 and 43 of the cooling body is 45 ° or less. Further, in FIG.
2 and the distance D between the inner surfaces 42 and 43 which are the collision surfaces of the cooling body
Is adjusted to be 30 to 60 times the diameter d of the wire 22. Note that the heat conductivity of the cooling body 41 is large,
In order to further improve the releasability of the colliding powder, it is preferable to form a titanium nitride film having high thermal conductivity and poor wettability with metal on the surface of the copper cooling body among ceramics. Reference numeral 44 denotes a cooling pipe arranged on the outer surface of the cooling body 41 in order to enhance the cooling performance of the cooling body 41.

In this device, the material, dimensions, and
The linear raw material 22 is discharged and exploded under the discharge explosion conditions set by the size of the powder particles to be produced, and the resulting molten particles and vaporized 0.1 to 100 μm
The scattered particles of about a degree fly at a high speed of 300 to 1000 m / sec, collide obliquely with the cooling body 41 having the inclined collision surface, are rapidly cooled, and become flattened amorphous powder.
Further, by adjusting the collision angle with the cooling body 41, the flatness of the particles can be arbitrarily controlled.

Using this apparatus, an amorphous powder of an Fe-3B-2Si-0.5C alloy was obtained under the following discharge explosion conditions.

Wire diameter 1.0 mm, length 90 mm Atmosphere gas Argon Distance between electrodes 80 mm Distance between wire and cooling body Approx. 20 mm Capacitance 100 μF Charging voltage 10 kV Collision angle 30 ° The recovered powder has a particle diameter of 1 μm or less. 30% of things,
Particles having a particle diameter of 1 μm or more and 5 μm or less and having a particle size composition of 70%, and an aspect ratio of about 180 were obtained. No characteristic peak was observed from the X-ray analysis pattern of this powder, confirming that the powder was amorphous powder.

Example 2 Using the same apparatus as in Example 1, an amorphous powder of an Fe-44Ni-8Mo-4B alloy was obtained under the following discharge explosion conditions.

Wire diameter 0.9 mm, length 65 mm Atmosphere gas Nitrogen distance between electrodes 55 mm Distance between wire and cooling body Approximately 15 mm Capacitance 80 μF Charging voltage 6.5 kV Collision angle 20 ° The recovered powder has a particle diameter of 1 μm More than 20%
The powder had an aspect ratio of about 200. From the X-ray diffraction pattern, no characteristic peak was observed, and it was confirmed that the powder was amorphous.

Example 3 Using the same apparatus as in Example 1, an amorphous powder of an Fe-21Co-3B-0.5Si alloy was obtained under the following discharge explosion conditions.

Wire diameter 0.9 mm, length 65 mm Atmospheric gas Nitrogen Distance between wire and electrode 55 mm Distance between wire and cooling body Approx. 20 mm Capacitor capacity 80 μF Charging voltage 6 kV Collision angle 40 ° The recovered powder has a particle diameter of 1 μm or less. 50%, 1μ
50% of those with m of 5 m or less and an aspect ratio of about 1
It was 50. Further, it was confirmed from the X-ray diffraction pattern that the film was amorphous.

[0027]

【The invention's effect】

(1) Since no crucible for dissolving the starting materials is used, there is no risk of contamination of impurities from the crucible.

(2) Since a wire obtained by extrusion press sintering, which is one of the powder metallurgy processes, can be used,
The alloy composition as a starting material can be selected more widely than in the prior art. (3) The size of the particles can be appropriately controlled by controlling the discharge energy.

(4) The shape and flatness of the particles can be appropriately controlled by making the collision angle between the collision cooling body and the particles variable.

(5) An amorphous powder suitable for a magnetic material having a large aspect ratio and a small demagnetizing coefficient is obtained.

[Brief description of the drawings]

FIG. 1 shows an apparatus for carrying out the method for producing an amorphous powder of the present invention.

FIG. 2 shows details of a support portion and a cooling body portion of the linear raw material shown in FIG.

FIG. 3 shows a cross section taken along line AA of FIG. 2;

DESCRIPTION OF SYMBOLS 1 Closed container 2 Supporting part for linear raw material 21 Wire hopper 22 Wire 23 Electrode 24 Melted scattered substance 3 Power supply part 31 Distance control mechanism between electrodes 32 Coaxial output cable 4 Cooling part 41 Cooling body 42 43 Upper and lower inner surfaces of cooling body 44 Cooling pipe 5 Powder recovery unit 51 Collection container

Claims (3)

[Claims] 1. A high-impact current is applied to the linear starting material to form a molten portion, and the molten portion is scattered in high-speed fine particles by an explosion generated inside the linear starting material.
A method for producing an amorphous powder, comprising colliding this with a cooling body surface. 2. The method for producing an amorphous powder according to claim 1, wherein the application of the high impact current is performed in an atmosphere gas having a high cooling capacity. 3. A closed raw material supporting portion for a linear raw material, a power supply unit for the linear raw material, a cooling unit for cooling the scattered raw material, and a powder collecting unit for collecting the scattered raw material. And an apparatus for producing amorphous powder.