JPS63137108A - Production of metal powder - Google Patents

Abstract

PURPOSE:To permit efficient production of metal powder having a small particles size by converting the molten metal flow dropping from a nozzle to film-like flow and blowing an atomizing medium uniformly thereto at the time of producing the metal powder by an atomization method. CONSTITUTION:The molten metal 1 in a tundish 2 falls when a stopper 5 is pulled up. The falling molten metal strikes against the top part of a molten metal dividing body 4, by which the molten metal is divided. The divided molten metals flow along the slope of a circular conical body and the molten metal TM which is columnar is changed to the film-like molten metal M. The molten metal flow converted to the thin film is rapidly cooled and splashed when the atomizing gas is directed and injected toward the tail part of the dividing body 4. The molten metal is, therefore, extremely finely divided by the atomization. The circumferential length of the tail part of the body 4 increase if the vertex of the body 4 is selected at a large angle. The film forming efficiency of the molten metal is thereby improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing metal powder by an atomization method, and in particular, a method for producing metal powder that has succeeded in efficiently producing atomized powder with a small particle size. It is about the method.

Although both gas and liquid can be used as the atomization medium used in the present invention, the following description will be made using a gas atomization method using gas as an example.

[Prior Art] The gas atomization method is a method of pulverizing falling molten metal by injecting gas onto the molten metal. By the way, in carrying out the gas atomization method, it has always been desired to increase the gas atomization efficiency, and in order to satisfy this demand, it is a prerequisite to increase the amount of falling molten metal.

However, if the amount of molten metal is increased, it is necessary to increase the amount of atomized gas accordingly, and there is also the disadvantage that the particle size of the atomized powder produced becomes larger.

[Problems to be Solved by the Invention] The present invention has been made in consideration of these circumstances, and aims to provide a method for efficiently producing atomized powder having a small particle size.

[Means for Solving the Problems] The method for manufacturing metal powder according to the present invention is to convert a columnar or band-shaped molten metal flow falling from a molten metal nozzle into a film-like molten metal flow when manufacturing metal powder by an atomization method. Converted,
The gist lies in spraying the atomizing medium evenly onto this film-like molten metal flow.

[Function] As described above, the present invention is characterized in that (1) a falling molten metal flow (columnar or band-like) is converted into a film-like molten metal flow, and (2) an atomizing medium is evenly sprayed onto this film-like molten metal flow. It has the following.

By converting into a film-like molten metal flow as in (1) above,
Compared to the case of columnar or band-shaped falling molten metal, the film is made wider and thinner, and as a result, the surface area can be increased. If it is sprayed evenly, even if the total amount of molten metal falling is large, it will form a thin film, so production efficiency can be improved without increasing the diameter of the product particles, and sufficiently fine atomized powder can be produced. It became possible to obtain large quantities. Moreover, in this case, the inconvenience of having to significantly increase the amount of atomized medium does not occur. Therefore, by carrying out configurations (1) and (2) of the present invention, sufficiently fine atomized powder can be efficiently mass-produced without using an unnecessarily large amount of atomizing medium. In other words, it is possible to reduce the amount of atomized medium (a+3)/the amount of atomized powder Ii (kg) when obtaining atomized powder of the same particle size.

Embodiments of the present invention will be described in detail below with reference to the drawings, but the embodiments are merely illustrative of the present invention and are not intended to limit the invention.

[Example 5] Fig. 1 is an explanatory view of a metal powder manufacturing apparatus suitable for applying the method of the present invention, and Fig. 2 is a perspective view showing the main parts. An annular gas atomizing nozzle 3 is provided at the lower part of the tundish 2 containing the molten metal 1, and a molten metal flow divider 4 is provided in the middle of the molten metal falling trajectory. Although the molten metal flow divider 4 of this embodiment has a conical shape, it may also be a polygonal pyramid.

The molten metal 1 in the tundish 2 falls by pulling up the stopper 5, hits the top of the molten metal flow divider 4, is divided, and flows along the slope of the cone. That is, the columnar molten metal TM is divided and dispersed in the circumferential direction, thereby changing into film-like molten metal flows M, M. At this time, if the atomizing gas is directed toward the bottom of the dividing body 4 and injected, the thin film of the molten metal flow is rapidly cooled and blown away, resulting in very fine atomization. Therefore, if the apex angle of the dividing body 4 is made larger, or if the dividing body 4 is made taller, the circumference of the bottom part of the dividing body 4 will be increased, and the efficiency of forming a film of the molten metal will be increased. The purpose of the present invention will be more effectively achieved.

FIG. 3 is a perspective explanatory view of the main parts of another metal powder manufacturing apparatus applied to carry out the method of the present invention. In FIG. 2, a slit type annular gas atomizing nozzle 7 is used, but a round hole type one is used in this device. A large number of round holes 9 are formed along the circumferential direction of the lower surface of the gas atomizing nozzle 8, and pencil-shaped atomized gas is ejected.

Figures 4(a) and 4(b) are perspective explanatory views of the main parts of yet another metal powder manufacturing apparatus applied to the implementation of the method of the present invention.

To explain (a), the rod-shaped gas atomizing nozzle 10.10 is of a type in which the atomizing gas forms a V-shaped film surface in cross section, and therefore a linear slit S is formed on the lower surface of the gas atomizing nozzle. On the other hand (b
) is of the type that uses a plurality of pencil-shaped atomizing gas groups to form a film surface having a square cross section.Therefore, a plurality of nine groups C are formed on the lower surface of the gas atomizing nozzles 11 and 11. On the other hand, the soluble fragment 4 is (a) and (
In both cases b), triangular prisms are arranged horizontally, and in (a) a band-shaped molten metal stream 12 is falling, and in (b) a plurality of columnar molten metal streams 13 are falling. , both are divided at the top of the triangular prism-shaped molten metal flow divider 4.4, flow down along the two slopes 4a and 4b, form a divided film-like molten metal flow M, and then fall from both skirts. . Therefore, atomizing gas is injected onto this falling thin film to obtain atomized particles.

The present inventors carried out the method of the present invention using high-melting point alloys such as superalloys (mp: max. 450°C) and iron alloys (mp: max. 550°C), and found that fine powder of the above-mentioned high-melting point alloys We confirmed that it can be manufactured efficiently. An example in the case of a Ni-based superalloy is shown in Table 1 below, comparing it with a conventional example and taking into account various conditions.

Furthermore, the above-mentioned molten metal flow divider must be able to 1) prevent the separation of the molten metal flow in the form of a membrane as much as possible, 2) have low reactivity with the molten metal deposition or deposition of the molten metal flow, and 2) be able to prevent wear and tear due to the molten metal flow in the membrane form. It is required that there be less In order to meet these requirements, it is possible to construct the molten metal flow divider using ceramics such as Al2O3 or ZrO3, or to form the divider using a metal that can prevent heat shock cracking and seizure damage as a base, and to improve its surface. An example of this is coating ceramics such as AI, O, or ZrO.

In addition, in order to prevent wear and tear of the dividing body due to temperature rise, it is recommended to add an operation that gives the dividing body a rotational motion.

The above-described molten metal flow divider is a conversion means for converting a columnar or band-shaped molten metal flow into a film-like molten liquid, and examples of such a conversion means include the film-form molten metal forming container shown in FIGS. 5 and 6. It can also be adopted.

That is, the conversion means shown in FIG.
A slit 12a is provided in the container 12) above the gas atomizing nozzle.
When the molten metal is dropped into 2 as shown by the arrow, the film-like molten metal flow falls from the slit 12a of the film-like molten metal forming container 12. The thickness, width, etc. of this film-like molten metal flow can be freely adjusted by changing the size of the slit. Therefore, it is easy to make the film-like molten metal flow into a wide thin film, and by injecting atomizing gas into such a film-like molten metal flow, it is possible to simultaneously achieve finer atomized powder and mass production.

The film-like molten metal forming container 13 shown in FIG. 6 is designed to be able to form a more uniform film-like molten metal flow than the film-like molten metal forming container 12 described above, and has pores in the metal melt falling surface. Make a large number of slits, first disperse the molten metal to some extent, then open slit 1.
Since it is discharged from 3a, the film-like molten metal flow can be made extremely uniform.

[Effects of the Invention] Since the present invention is configured as described above, it is possible to provide a method that can efficiently produce a large amount of metal powder with a small particle size.

[Brief explanation of the drawing]

Figures 1 to 4 (a) and (b) are explanatory diagrams of a metal powder manufacturing apparatus to which the method of the present invention is applied, and Figures 5 and 6 are perspective views of a film-like molten metal flow forming container according to the present invention. It is an explanatory diagram. 1... Molten metal 2... Tandish 3.
... Gas atomizing nozzle (molten metal nozzle) 4... Molten metal flow divider

Claims (1)

[Claims] In producing metal powder by the atomization method, a columnar or band-like molten metal flow falling from a molten metal nozzle is converted into a film-like molten metal flow, and an atomizing medium is evenly sprayed onto this film-like molten metal flow. Method for producing metal powder.