JPS6361363B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to an electrode device used in an apparatus for producing ultrafine metal particles such as ferromagnetic metals and alloys.

2. Description of the Related Art Conventionally, there is a device shown in FIG. 1 that utilizes arc discharge as a device for producing ultrafine metal particles such as ferromagnetic material.

That is, the electrode support rack 2 is placed inside the sealed container 1.
An electrode 3' such as tungsten for the cathode fixed to the tip of the container 1 is inserted, and ultrafine metal particles are placed on the upper surface of the copper hearth 4 for the anode, which forms the bottom of the container 1, facing the electrode 3' for the cathode. A metal material 5 to be manufactured is placed thereon.

After the inside of the container 1 is made into a mixed gas atmosphere of an inert gas such as argon or helium and pure hydrogen gas, or a pure hydrogen gas atmosphere, pure tungsten or tritanium prepared by adding 1 to 2 weight percent of thorium to tungsten is prepared. The voltage between the cathode electrode 3' formed by the metal material 5 and the metal material 5 placed on the anode copper hearth is set to 10 to 100 V, and arc discharge is performed between the electrode 3' and the metal material 5 to create an arc column. Form 6. Then, under appropriate conditions depending on the atmospheric gas, the arc column 6 is connected to the metal material 5.
Since the smoke is concentrated at one point on the surface of the metal, the temperature near that point becomes extremely high, and a large amount of ultrafine metal particles are generated, forming a smoke stream 7. Thereafter, this smoke stream 7 is cooled by the atmospheric gas and becomes ultrafine metal particles.

By the way, since the electrode 3' is water-cooled by the electrode support rack 2, the temperature of the portion in contact with the electrode support rack 2 is approximately 100° C. or lower. Furthermore, the tip of the cathode electrode 3', where the arc column 6 is generated, reaches a high temperature of about 3300°C. That is, electrode 3'
has a temperature gradient of 100 to 3300℃.

However, when the metal material 5 is an iron-nickel alloy (containing 10% by weight of nickel), the melting point of the iron-nickel alloy is approximately
The temperature is 1500℃, and the boiling point is about 2800℃.

Therefore, the generated smoke stream 7 of ultrafine metal particles is generated at the time of arc generation at the tip of the electrode 3'.
It does not adhere to areas in the temperature range of 2800°C to 3300°C because the temperature is too high. Even if ultrafine metal particles adhere to the electrode 3' portion above the tip, which is below 1500° C., the temperature is too low to form an alloy.

That is, the ultrafine metal particles of the iron-nickel alloy forming the metal material adhere to the electrode 3' and form an alloy only in the electrode portion within the temperature range of 1500 to 2800°C.

In this way, when ultrafine metal particles adhere to the electrode 3' and form an alloy, the melting point of the electrode 3' decreases,
The electrode 3' wears out and deteriorates, and in extreme cases it has the disadvantage of melting off.

FIG. 2 is a side view showing the electrode used in this device after discharge.

In addition, when an iron-cobalt alloy (containing 30% by weight of cobalt) is used as the metal material 5, its melting point is approximately 1500%.
℃, and the boiling point is about 2900℃, which is almost the same as the case of iron-nickel alloy.

Further, unless the arc column 6 is discharged perpendicularly to the metal material 5, its shape cannot be narrowed down to an inverted triangle, and a large amount of ultrafine metal particles will not be generated.
Therefore, in order to generate a large amount of ultrafine metal particles, the cathode as a discharge electrode must be arranged perpendicularly to the metal material 5.

The present invention has been made in view of the above-mentioned points, and its purpose is to prevent the wear and tear of the electrodes due to the attachment of ultrafine metal particles generated during arc discharge to the electrodes. The object of the present invention is to provide an electrode device for a manufacturing apparatus for ultrafine metal particles, which guarantees a long service life and is optimal for the mass production of high-quality, high-density magnetic recording media.

A first embodiment of the present invention will be described below with reference to FIG.

In this embodiment, the same parts shown in FIG. 1 are designated by the same reference numerals.

Reference numeral 3 denotes a cathode electrode made of tungsten or tritanium, and this electrode 3 is arranged in the same direction as the arc column 6 so that the arc column 6 is generated vertically from the tip of the metal material 5. It is formed of an electrode main body 3A, a heat generating electrode body 3B bent at right angles to the end of the electrode main body 3A, and an electrode support body 3C formed at the end of the heat generating electrode body 3B.
The electrode support 3C is disposed outside the area of the smoke stream 7 of ultrafine metal particles generated from the metal material 5. Reference numeral 2 denotes an electrode support rack, which supports and fixes the electrode support 3C and cools the electrode support.

The first embodiment of the present invention has the above-described configuration, and when arc discharge is performed between the cathode electrode 3 and the metal material 5 on the anode copper hearth 4, the metal material 5
Ultrafine metal particles generated from the smoke stream 7 rise. This smoke stream 7 is then cooled by atmospheric gas and collected by a filter (not shown) to produce ultrafine metal particles.

When an iron-nickel alloy is used as the metal material 5, as mentioned above, the melting point of the iron-nickel alloy is approximately
1500℃, the boiling point is about 2800℃, and among electrodes 3,
Only the portion in the temperature range of 1500°C to 2800°C is alloyed with the ultrafine metal particles of the iron-nickel alloy.

Here, the electrode main body 3A has a diameter of about 6 mm,
The length is 20mm or less, and during arc discharge, the entire
Since the temperature ranges from 2800 to 3300℃, metal materials 5
Even within the area of the smoke flow 7 of ultrafine metal particles generated from the ultrafine metal particles, the ultrafine metal particles do not adhere.

Further, the heating electrode body 3B has a diameter of 2 mm and a length of 40 mm.
mm, and during arc discharge of about 200A,
The whole building reaches a temperature range of 2,800 to 3,300 degrees Celsius due to the Joule heat. Therefore, similarly to the electrode main body 3A described above, ultrafine metal particles do not adhere.

Further, by forming the heating electrode body 3B as short as possible, unnecessary voltage drop can be reduced and energy loss due to Joule heat can be reduced.

The electrode support body 3C has a diameter of, for example, 5 mm, the contact area with the electrode support frame 2 is 100°C or less, and the contact area with the heating electrode body is approximately 280°C.
It's getting to ℃.

That is, point a in the figure is the temperature point at about 1500°C, and point b in the figure is the temperature point at about 2800°C.
The electrode support 3C in the area between points a and b is in a temperature range where it is easy to alloy with ultrafine metal particles, but since this area is outside the area of the smoke flow 7, it cannot easily form an alloy with ultrafine metal particles. No alloying occurs.

That is, it is clear that when discharge is performed under the same conditions, ultrafine metal particles do not adhere to the electrode 3' as shown in FIG. 3 compared to the conventional electrode 3' as shown in FIG.

Moreover, since the electrode main body 3A of the electrode 3 is oriented in the vertical X direction with respect to the metal material 5, the arc column 6 is also generated in the vertical X direction. In addition, since the discharge occurs in a mixed gas atmosphere of hydrogen gas and an inert gas such as argon or helium, or in a pure hydrogen gas atmosphere, the arc column 6 self-contracts and its shape becomes an inverted triangle as shown in FIG. Narrow down and concentrate on one point. Therefore, the temperature in the vicinity becomes very high and a large amount of ultrafine metal particles are generated from the metal material 5, so that the amount of ultrafine metal particles recovered increases.

Furthermore, when an iron-cobalt alloy is used as the metal material 5, its melting point is approximately 1500°C and its boiling point is approximately
2900°C, and has almost the same effect as the iron-nickel alloy mentioned above.

In addition to the above embodiments, the metal material 5 may also be aluminum, titanium, tantalum, iron, nickel, cobalt, iron-nickel, cobalt alloy, or the like.

What is shown in FIG. 4 is a second embodiment of the present invention, and in this embodiment, the electrode support 3C is bent upward in the axial direction. Also in this configuration, the electrode support 3C in the portion between point a and point b is located outside the area of the smoke flow 7, so that deterioration of the electrode can be prevented.

FIG. 5 shows another modification, in which the electrode support 3C is bent at an arbitrary angle with respect to the heating electrode 3B and supported on an electrode support rack.

What is shown in FIG. 6 is a fourth embodiment of the present invention,
In this embodiment, unlike the first embodiment in which the heat generating electrode body 3B is bent at right angles to the electrode body 3A, the heat generating electrode body 3B is bent at an arbitrary angle with respect to the electrode body 3A. By doing so and moving the electrode support 3C away from the smoke flow 7, ultrafine metal particles generated from the metal material 5 are prevented from adhering to the electrode support 3C.

Moreover, what is shown in FIG. 7 is a fifth embodiment of the present invention, and in this embodiment, the electrode support is bent downward and supported by a lower electrode support frame.

Moreover, what is shown in FIG. 8 is a sixth embodiment, in which two heating electrode bodies 3B are bent laterally, and two
It has a book electrode support 3C and two electrode support frames 2. In this case, the current flowing through one heating electrode body is halved, so in order to generate heat up to 2800° C. or higher, the cross-sectional area of the heating electrode body 3B must be halved. In other words, the diameter must be made smaller.

Moreover, the one shown in FIG. 9 is a seventh embodiment, which has two heat generating electrode bodies and has a structure in which two electrode supports 3B are bent upward in the axial direction.

In addition, in any of the above embodiments, the electrode main body 3A, the heat generating electrode body 3B, and the electrode support body 3C of the electrode are integrally formed of the same material, but the electrode main body 3
It goes without saying that A, the heating electrode body 3B, and the electrode support body 3C may be formed separately from tungsten or tritanium.

Furthermore, in the embodiments shown in FIGS. 8 and 9, 2
Although the electrode main body 3A is supported by the electrode supports 3B, three or more electrode supports may be used.

As described above, in the present invention, the portion of the electrode support 3C that is above the melting point and below the boiling point of the metal material, to which ultrafine metal particles generated from the metal material easily adhere, is arranged outside the area of the smoke flow 7 of the ultrafine metal particles. This prevents the electrode from being worn out and deteriorated due to the ultrafine metal particles of the metal material 5 adhering to the electrode, thereby ensuring a long service life. For this reason, when the metal material is ferromagnetic, it is optimal for mass production of high-quality, high-density magnetic recording media.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a conventional apparatus for producing ultrafine metal particles, FIG. 2 is a side view showing an electrode used in this apparatus after discharge, and FIG. 3 is a diagram showing a first embodiment of the present invention. 4 is a side view showing the second embodiment, FIG. 5 is a side view showing the third embodiment, and FIG. 6 is a side view showing the fourth embodiment. FIG. 7 is a side view similarly showing the fifth embodiment, FIG. 8 is a side view similarly showing the sixth embodiment,
FIG. 9 is a side view similarly showing the seventh embodiment. 1... Container, 2... Electrode support rack, 3... Electrode,
3A... Electrode main body, 3B... Heat generating electrode body, 3C...
... Electrode support, 4 ... Copper hearth, 5 ... Metal material, 6 ... Arc column, 7 ... Smoke flow.

Claims (1)

[Claims] 1. In an electrode device in an apparatus for producing ultrafine metal particles of a metal material by causing arc discharge, an electrode main body disposed in the same direction as the arc column so as to order the arc column in the vertical direction; One or more heating electrode bodies formed at the end of the electrode main body and having a reduced diameter and generating heat by Joule heat, and one or more electrode supports formed at the end of the heating electrode body. , consisting of one or more electrode support racks for supporting and fixing the electrode support and cooling the electrode support, and disposed inside the smoke flow area of ultrafine metal particles generated from the metal material. The temperature range of the heating electrode body is
An apparatus for producing ultrafine metal particles, characterized in that the temperature is above the melting point and below the boiling point of the metal material, and the electrode support is disposed outside a smoke flow region of the ultrafine metal particles generated from the metal material. Electrode device.