JPH05171228A - Production of spherical particle of metal and centrifugal spraying device - Google Patents

Abstract

PURPOSE:To produce spherical particles of metals, etc., having large grain sizes by supplying a molten metal from a nozzle to the top part of the projecting walls on a rotary disk rotating at a high speed and centrifugally spraying this molten metal, thereby cooling the metal. CONSTITUTION:The projecting walls 2 having the height of 0.02 to 0.5 times the diameter of the rotary disk 1, the thickness of 0.02 to 0.2 times the diameter of the rotary disk and the length of the same size as the diameter are provided at one or >=2 points to the direction of the diameter on the rotary disk. This rotary disk 1 is rotated at a high speed and the melt 4 of the metal (La, Ce, Fe, Co, etc.) or the alloy is dropped toward the center of the peak parts of these projecting walls from above via the molten metal nozzle 3. The molten metal flow is, therefore, splashed in the form of the large liquid drops which are then cooled by a cooling gas. Thus, the spherical particles of the metal, alloy or metal oxide of the large grain sizes ranging from about 100 to 2000mu in grain size are obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing spherical particles of a metal, an alloy or a metal oxide, which are useful as a regenerator material for a magnetic refrigerator, a spherical powder for powder metallurgy and the like, and a centrifugal spraying device therefor. ..

[0002]

2. Description of the Related Art Rotating consumable electrode method, gas atomizing method, water atomizing method, centrifugal atomizing method and the like are known as methods for spheroidizing a metal or alloy. However, although fine spherical powders having a particle size of 500 μm or less can be produced by these methods, it has been difficult to obtain spherical powders having a relatively large particle size of 2,000 to 500 μm.

[0003]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention focuses on the centrifugal atomization method, and
The present invention seeks to provide a method and apparatus for making spherical particles of alloys or metal oxides.

[0004]

Means for Solving the Problems The present inventors have found that these problems can be solved by improving the rotating disk shape of the centrifugal atomization method, and studied the various conditions to complete the present invention. The gist is to supply a molten metal or alloy from a molten metal nozzle to the top of the convex wall of a rotating disk having a convex wall that rotates at high speed, centrifugally spray the metal, and cool the metal.
A method for producing spherical particles of an alloy or metal oxide, and a height of 0.02 to 0.5 times the diameter of the rotating disk, a thickness of 0.02 to 0.2 times the diameter of the rotating disk and a convex wall of the same length as the diameter of the rotating disk. The centrifugal spraying device is characterized in that one or more rotating disks arranged in the diameter direction are rotated at high speed.

The present invention will be described in detail below. In the normal centrifugal atomization method, a molten metal or alloy is continuously dripped at the center of a heat-resistant rotating disk, and the centrifugal force of the disk rotating at high speed causes the molten metal film to spread evenly on the disk. It becomes droplets and is sprayed and scattered in the direction of the cutting line, and is solidified by an alternating current or a co-current cooling gas to produce spherical powder. In this method, the droplets are sprayed as a kind of suspended droplets and are obtained. There is an upper limit on the size of droplets, and therefore, there is also an upper limit on the size of spherical powder obtained by solidification, which is usually 500 μm.
It was m or less. Therefore, in the present invention, in order to obtain a spherical powder having a large particle size of 500 to 2,000 μm, it has been found that it is sufficient to cut the molten metal stream at a high speed to generate a large droplet in a size close to a desired particle size.

This will be described with reference to FIG. 1 (a). The rotating disk 1 has a convex wall 2 having the same length as the diameter in the diametrical direction, and the metal from the molten metal nozzle 3 toward the center of the convex wall. Alternatively, when the alloy melt 4 is flowed down, the melt flow is continuously cut by the convex wall that rotates at high speed, and becomes large droplets that scatter in the cutting line direction from the circumferential edge of the disk. If this is cooled by an alternating current or a co-current cooling gas, solidified metal or alloy spherical particles are obtained, and in the case of an easily oxidizable metal or alloy in an oxidizing atmosphere such as air, spherical particles of metal oxide are obtained. Be done. The particle size range of the spherical particles obtained by this method is about 100 to 2,000 μm, and the shape reaches close to 99% in terms of aspect ratio by photographic judgment.

The greatest feature of the present invention is that the rotating disk is provided with a convex wall. The material, size, and number of this convex wall must be appropriately selected according to the type of metal, alloy, and metal oxide to be treated, but heat-resistant steel, heat-resistant alloy, ceramics, etc. of the same quality as the rotating disk should be used as the disk. It may be adhered, welded, screwed, or molded simultaneously with the rotating disk in a mold.
It is recommended that the height is about 0.02 to 0.5 times the diameter of the rotating disk and the thickness is about 0.02 to 0.2 times the diameter of the rotating disk in order to prevent deformation and vibration of the disk due to high speed rotation under high temperature.
The number of the convex walls may be one with the same length as the diameter in the diameter direction of the disk, but two or more may be provided depending on the conditions.
FIG. 1B is a top view in the case of one convex wall, and FIG. 1C is a top view in the case of two convex walls. It is desirable that the molten metal supply point be such that the tip of the molten metal is at the center of the rotating disk. It may be separated from the center by the thickness of the convex wall, but in that case, the yield of the spherical particles obtained is slightly deteriorated. When the tip of the molten metal nozzle is lower than the top of the convex wall by 1 cm or less, the tip of the molten metal flow may be solidified with the upper part of the rotating disk.
It is desirable that the height is at least cm. As the cooling gas, an inert gas such as Ar, He or N ₂ is usually used, but the metal oxide spherical particles can be obtained by using the oxygen-containing gas.

The metal to which the present invention is applied is La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, T containing Y as a rare earth metal.
Fe, Co, Ni, Al, Si, Cr, M as m, Yb and Lu, transition metals, etc.
n, Zn, Zr, Nb, Rh, Ag, Sn, Sb, Au, Pb is a metal selected from among these, by supplying one or more of these as a raw material, these metals, and these Alloys consisting of two or more of them, and spherical particles of their oxides are obtained. Of the above, rare earth metals and transition metals are preferred because of their versatility and ease of production.

[0009]

EXAMPLES Hereinafter, the embodiments of the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto. (Example 1) Melt 2,000 g of Er ₃ Ni alloy ingot, and use a rotating disk 1 with a convex wall 2 as shown in FIG.
Centrifugal spraying was performed at 950 ° C. Rotating disk: 36mmφ × 10mmT
, Convex wall: 3mmH x 10mmT x 36mmL, Molten nozzle diameter:
3 mmφ, rotating disk rotation speed: 10,000 rpm, cooling gas atmosphere: Ar 1 atm, as a result, particle size 2,000-5
380 g of 00 μm spherical particles were obtained.

(Example 2) 2,000 g of Tb 85-Fe 15 wt% alloy ingot was melted, and centrifugal spraying was performed at a molten metal temperature of about 1,000 ° C. using a rotating disk 1 with a convex wall 2 as shown in FIG. It was Rotating disk: 36mmφ × 10mmT, convex wall: 3mmH × 8mm
T × 36mmL, Molten Nozzle Diameter: 3mmφ, Rotating Disc Rotation Speed:
As a result of carrying out under the conditions of 7,500 rpm and cooling gas atmosphere: Ar 1 atm, 250 g of spherical particles having a particle diameter of 2,000 to 500 μm were obtained.

Example 3 Tb 85-Fe 15 wt% alloy ingot 2,000 g was melted, and the treatment was carried out under the same conditions as in Example 2 except that the rotating disc rotation speed was 5,000 rpm.
890 g of spherical particles of 000 to 500 μm were obtained.

(Example 4) 2,000 g of Pb 98-Sb 15 wt% alloy ingot was melted, and centrifugal spraying was performed at a molten metal temperature of about 480 ° C. using a rotating disk 1 with a convex wall 2 as shown in FIG. It was
Rotating disk: 36 mmφ x 10 mmT, convex wall: 2 mmH x 8 mmT x
36mmL, Molten Nozzle Diameter: 3mmφ, Rotating Disk Rotation Speed: 8,000
As a result of carrying out under the conditions of 0 rpm, cooling gas atmosphere: Ar 1 atm, 420 g of spherical particles having a particle diameter of 2,000 to 500 μm were obtained.

(Embodiment 5) La metal ingot (2,000 g) was melted, and a rotary disk 1 with a convex wall 2 as shown in FIG. 1 was used.
Centrifugal spraying was performed at a melt temperature of about 980 ° C. Rotating disk: 36 mm
φ × 8mmT, convex wall: 10mmH × 6mmT × 36mmL, melt nozzle diameter: 3mmφ, rotating disk rotation speed: 7,000rpm, cooling gas atmosphere: Ar 1atm, the result was particle size 2,000
510 g of spherical particles of ˜500 μm were obtained.

(Example 6) Dissolving 2,000 g of Al pellets,
Centrifugal spraying was performed at a molten metal temperature of about 800 ° C. using a rotating disk 1 with a convex wall 2 as shown in FIG. Rotating disk: 36mmφ × 10mm
T, convex wall: 3 mmH x 8 mmT x 36 mmL, melt nozzle diameter:
3 mmφ, rotating disk rotation speed: 8,000 rpm, cooling gas atmosphere:
Ar + O ₂ 40 vol% 1atm As a result, the particle size
280 g of spherical alumina (Al ₂ O ₃ ) particles of 2,000 to 500 μm were obtained.

(Comparative Example) As a result of treating under the same conditions as in Example 1 except that centrifugal spraying was carried out by the conventional centrifugal spraying apparatus having no convex wall shown in FIG. 2, spherical particles having a particle diameter of 2,000 to 500 μm were found. Only 5g was obtained.

[0016]

Industrial Applicability According to the present invention, a spherical powder having a high sphericity of a metal, an alloy, or a metal oxide having a particle diameter of about 2000 to 500 μm can be produced with a good yield by a centrifugal atomization method, and its industrial utility is extremely high. high.

[Brief description of drawings]

FIG. 1A is a side view illustrating an example of an embodiment of the present invention. (B) is the same top view. FIG. 6C is a top view showing another embodiment of the present invention.

FIG. 2 is a side view showing a conventional centrifugal spraying device.

[Explanation of symbols]

 1 rotating disk 2 convex wall 3 molten metal nozzle 4 molten metal

Claims (2)

[Claims] 1. A metal, an alloy or a metal, characterized in that a melt of a metal or an alloy is supplied from a melt nozzle to the top of the convex wall of a rotating disk having a convex wall rotating at a high speed, centrifugally sprayed and cooled. Method for producing spherical particles of oxide. 2. A convex wall having a height of 0.02 to 0.5 times the diameter of the rotating disk, a thickness of 0.02 to 0.2 times the diameter of the rotating disk, and a length equal to the diameter of one or two diametrical directions of the rotating disk. A centrifugal spraying device, characterized in that the rotating disk provided above is rotated at high speed.