JPS6126707A - Production of metallic powder - Google Patents

Abstract

PURPOSE:To produce easily metallic powder which is pulverous and is quickly cooled to solidify at a high yield by passing quickly large electric current to a metallic wire rod to generate line explosion so that the metallic wire rod is made into fine metallic liquid drops and bringing the metallic liquid drops into contact with a cooling medium. CONSTITUTION:The metallic wire rod 4 is provided in a copper cylinder 1 which rotates at a high speed and is always thoroughly cooled by liquid or gas. Said rod is extended between two electrodes 2 and 3 provided at both ends in the axial center part of said cylinder. The rod 4 is subjected to line explosion by passing instantaneously the large current to the rod 4 via said electrodes 2, 3 while the cylinder 1 is rotated. The rod 4 is then made into the fine metallic liquid drops which scatter at a high speed, collide against the inside circumferential surface of the cylinder body 1 and are cooled quickly. The pulverous metallic powder having about <=25mum grain size is thus efficiently obtd. The above- mentioned method is effectively applicable particularly in the stage of producing the amorphous metallic powder.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method for producing metal powder, and more particularly to a method for producing rapidly solidified fine metal powder.

(b) Prior Art and Problems Conventionally, atomization methods, spray methods, cavitation methods, and the like have been proposed and put into practice as methods for producing metal powder.

In this type of conventional metal powder manufacturing method, the momentum of a gas or solid is transferred to a molten metal that has been brought into a molten state in advance to scatter it as minute droplets, and the droplets are cooled in flight or by other means. A method is adopted in which metal powder is made by contacting with a medium and cooling and solidifying it.

In such conventional methods, the molten metal is split into droplets and scattered by the moving gas or solid, but since there is a limit to the speed of the gas or solid, the droplets are There are limits to the degree of miniaturization of metal droplets, and there are also restrictions on the flight speed of metal droplets. Therefore, it is difficult to obtain a fine, rapidly solidified, homogeneous metal powder, and the particle size structure of the obtained metal powder is generally Fi25 to 10.
00 μm, especially particle size 25 μm.
It has the disadvantage that it is difficult to obtain fine rapidly solidified metal powder of micrometer or less in high yield.

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a method for producing metal powder that makes it possible to obtain fine, rapidly solidified metal powder at a high yield.

B) Structure and effect of the invention This invention basically involves suddenly passing a large current through a metal wire to generate a radiation explosion phenomenon in the metal wire and scattering the metal wire as a high-speed flow of fine metal droplets. The present invention relates to a method for producing metal powder, which comprises bringing the high-speed metal droplets into contact with a cooling medium to rapidly solidify them.

In the present invention, the metal wire is explosively melted by a large current flowing in an impulsive manner, and is scattered at high speed as fine droplets, which are rapidly solidified by a cooling medium. Therefore, according to the present invention, fine metal powder with a particle size of 25 μm or less can be easily obtained, and in particular, rapid cooling of the droplets is effectively achieved by forming a high-speed droplet flow. Therefore, the effect is remarkable when it is employed as a method for obtaining amorphous metal powder.

Here, as the cooling medium, a solid metal, a liquid such as water, or a cooled gas such as argon gas or nitrogen gas is used.

(Example-1) A wire with a diameter of 1.6 vx was placed between electrodes 2.3 provided at both ends of the shaft core of a low-temperature copper cylinder 1 with an inner diameter of 80 mm that rotates at high speed.
φ, length 80m, composition NiB1mBty, Fate
Crg&tzBto% N15sZray
, Co1. s#na, Tomi S! tsBtt metal wire 4 (see Fig. 1), rotate the cylinder 1, and
A switch 5 of the electric circuit as shown in the figure was activated to instantaneously pass a large current through the metal wire 4, causing the metal wire to become a bomb. Due to this wire explosion phenomenon, the polymetallic wire becomes fine metal droplets and scatters at high speed, collides with the inner peripheral surface of the copper cylinder 1 that is rotating at high speed around it, and is rapidly cooled, forming fine metal powder. Obtained. Preferably, the cylinder is kept sufficiently cooled by liquid or gas.

In addition, in this embodiment, the capacitance of the capacitor 6 of the circuit is set to 80
μF1 charging voltage was set to 13 KV.

The particle size structure of the metal powder obtained from the metal wires N i , , is B l is shown in FIG.

(Example-2) From the inlet 9 to the outlet 1 in the inner circumferential groove 7 of the cylindrical body 11 rotating at high speed
0 is filled with flowing water 8, and the inner diameter of the cylindrical water layer is 6011.
1Iφ, and the wire diameter was 1.1Iφ as in Example-1.
6 fins φ, length 80I111 composition N1yssLsBty
sCoas, 5Fnn, zltsBtt 5Niss
A metal wire 44 of Zrsy % FatmCr 2s4tmBto was wire bombed to obtain metal powder. In this Example-2, the fine metal droplets scattered at high speed by the radiation bombing phenomenon are rapidly cooled by the water layer around the cylindrical body, and the obtained metal powder has a pseudospherical shape. The metal structure exhibited an amorphous metal structure. Figure 5 shows hγ6Cr! The grain size structure of 5t12J metal wire is shown.

In addition, in the present invention, the electric energy applied to the metal wire may be sufficient to cause a radiation explosion phenomenon in the metal wire, but it is preferable that the electric energy applied to the metal wire be equal to the energy consumption per unit volume of the metal wire. It is desirable that the following conditions be satisfied.

Here, C: Capacity of the capacitor (Farad) V: Charging voltage (Vo, 1t) S: Cross-sectional area of the metal wire (difficulty 1: length of the metal wire) G: Mass of the metal wire C: Mass of the wire Specific heat at constant volume at the melting point θ2: Melting point of the wire θ3: Boiling point of the wire Also, in order to quickly cool and solidify the flying droplets, a cooling medium such as a liquid or solid should be placed near the metal wire. When using a cylindrical cooling medium as in the above embodiment, it is desirable that the relationship between the inner circumferential radius R of the cylinder and the diameter d of the metal wire be R = 15 to 25 d. .

As described above, when using the metal powder manufacturing method of the present invention, fine metal powder with a particle size of 25 μm or less can be obtained with a high yield, and is a particularly practical method for manufacturing fine amorphous metal powder. It has great industrial value.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing an example of an electric circuit used to carry out the method of the present invention, and FIG. 3 is a cross-sectional view showing another embodiment of the present invention. Figure, Figure 4, Figure 5
The figure shows the particle size structure of the metal powder obtained in the example. In the figure = 1... Cylindrical body 2... Electrode 3... Electrode 4.44... Metal wire 5... Switch 6...
・Condenser 7... Inner circumferential groove 8... Water layer Figure 1 Figure 2 (%) 1 ocDO~ (%) 1)

Claims (1)

[Scope of Claims] 1) Generating a wire bomb phenomenon by rapidly passing a large current through a metal wire so that the metal wire is melted and scattered as a high-speed flow of fine metal droplets; A method for producing metal powder, comprising rapid solidification of a stream by contacting it with a cooling medium. 2) The method for producing metal powder according to claim 1, wherein the cooling medium is a moving solid metal body. 3) The method for producing metal powder according to claim 1, wherein the cooling medium is water. 4) The method for producing metal powder according to claim 1, wherein the cooling medium is a cooled gas. 5) Manufacturing the metal powder according to any one of claims 1 to 4, wherein the metal wire is made of a metal material having a composition capable of forming an amorphous metal, and the metal powder is an amorphous metal powder. Method.