JPH04325607A - Production of metal powder - Google Patents

Abstract

PURPOSE:To obtain a flat-shaped metal powder having a large surface area by injecting the molten metal from the inner surface side of the liq. coolant layer formed on the inner surface of a cooling cylinder and colliding the unsolidified metal grain with the inner surface of the cylinder. CONSTITUTION:A pump 3 is operated to form a liq. coolant layer 21 which spirals down along the inner surface of a cooling cylinder 1 at high speed. An inert gas is introduced under pressure into a crucible 2 to inject the molten metal 22 in the crucible 2 against the inner surface of the coolant layer 21, and the molten metal is finely divided by the spiral flow. The finely divided metal is passed through the coolant layer 21, collided with the inner surface of the cylinder 1 or sleeve 6 and flattened. The flattened metal grain is cooled by the liq. coolant and solidified, and a flat-shaped metal powder is continuously produced.

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 metal powder by injecting molten metal into a swirling layer of cooling liquid.

0002

[Prior Art] Rapidly solidified metal powder has fine crystal grains and can contain supersaturated alloying elements. For example, an extruded material formed from rapidly solidified powder of aluminum or its alloy has It has exceptional material properties and is attracting attention as a material for mechanical parts.

[0003] A preferred method for producing the rapidly solidified metal powder is a rotating drum method. In this method, as shown in FIG. 2, a cooling liquid layer 62 is formed on the inner peripheral surface of a rotating cooling drum 61.
In this method, a molten metal flow is formed by the action of centrifugal force, and a molten metal flow is injected into the cooling liquid layer 62 to obtain finely divided metal powder that is rapidly solidified. In the figure, 63 is an injection crucible serving as a molten metal injection means, and a high frequency coil 64 for heating is attached to the outer peripheral surface of the crucible, and an injection nozzle 65 is provided on the lower side wall of the crucible. Molten metal 6 in the crucible 63
6 is injected from the nozzle 65 by injecting an inert gas 67 into the crucible 63 under pressure. When a certain amount of metal powder accumulates in the cooling drum 61, the rotation of the cooling drum 61 is stopped, the metal powder is collected together with the cooling liquid, and the metal powder is removed and dried. The method for producing such metal powder is described in Japanese Patent Publication No. 1-
It is disclosed in Japanese Patent No. 49769.

0004

However, the rotating drum method involves a so-called batch operation, resulting in poor productivity. Furthermore, since the injection of molten metal must be stopped during powder recovery, there is a problem in that the nozzle is likely to become clogged. In addition, in order to keep the cooling temperature constant, the temperature must be controlled by supplying and discharging the cooling liquid from the liquid level of the cooling liquid layer, but in this case, the liquid level is disturbed and the powder particle size and quality may vary. There is a problem in that it is easy to occur.

[0005] Furthermore, metal powders used as composite materials added to catalysts, synthetic resins, etc. are required to have a large surface area, but powders produced by the rotating drum method do not necessarily satisfy this requirement. An object of the present invention is to provide a method for producing metal powder that can continuously produce metal powder with a large surface area and stable quality.

[0006]

[Means for Solving the Problems] The method for producing metal powder of the present invention provides cooling liquid that is sprayed and supplied along the inner circumferential surface of a cooling cylinder and flows down while swirling along the inner circumferential surface of the cylinder. A liquid layer is formed, and molten metal is injected from the inner circumferential side of the coolant layer, and the coolant layer divides the metal particles. At the same time, the unsolidified metal particles are deformed by colliding with the inner circumferential surface of the cylinder, and are cooled and solidified to form a flat shape. The structure of the invention is to obtain a metal powder of . When flattening the unsolidified metal particles, a replaceable sleeve may be provided on the inner peripheral surface of the cooling cylinder, and the metal particles may be flattened by colliding with the sleeve.

[0007]

[Operation] The coolant that is spouted and supplied along the inner circumferential surface of the cooling cylinder flows down while swirling along the inner circumferential surface of the cylinder or the sleeve, and is almost constant due to the action of centrifugal force during swirling. Forms a thick cooling liquid layer. When molten metal is injected and supplied from the inner peripheral surface of this cooling liquid layer, the molten metal flow or droplets are separated by a swirling flow. By forming the coolant layer to be relatively thin, the separated metal particles reach the inner circumferential surface of the cylinder or the inner circumferential surface of the sleeve before solidifying due to the action of kinetic energy and centrifugal force caused by the injection. It collides with the inner circumferential surface, deforms, cools and solidifies, yielding a flat metal powder with a large surface area.

When the sleeve is attached to the inner circumferential surface of the cooling cylinder, the thickness of the cooling liquid layer can be easily adjusted by replacing sleeves with different wall thicknesses. The cooling state of the fragmented unsolidified metal particles and the degree of flattening can be easily controlled. At this time, since the cooling liquid layer is always formed by newly supplied cooling liquid, a constant temperature can be easily maintained. Therefore, there is no need to drain or supply cooling liquid from the liquid surface for temperature control, and the liquid level is not disturbed and remains in a stable state. Therefore, the molten metal injected into the cooling liquid layer is always injected into the cooling liquid layer under constant conditions, is divided, and is cooled and solidified at a constant temperature, so that the quality of the metal powder is stabilized.

Since the metal powder in the cooling liquid layer flows down while swirling together with the cooling liquid and is discharged from the lower end of the cylinder, continuous production of metal powder becomes possible.

0010

EXAMPLES First, an apparatus for carrying out the method for producing metal powder of the present invention will be described. FIG. 1 shows a metal powder manufacturing apparatus according to an embodiment, which includes a cooling cylinder 1 for forming a cooling liquid layer 21 on the inner peripheral surface, and a cooling cylinder 1 for injecting and supplying molten metal 22 to the cooling liquid layer 21. Injection crucible 2
and a pump 3 which is a means for supplying cooling liquid to the cylindrical body 1.

The cylinder 1 has a cylindrical shape, and a lid 5 having an opening 4 formed in the center for supplying molten metal to a cooling liquid layer 21 is attached to its upper end. A sleeve 6 for colliding and deforming the unsolidified metal particles separated by the cooling liquid layer 21 is detachably and replaceably attached to the lower inner circumferential surface with bolts. In the upper part, a plurality of discharge ports 8 of a coolant jet pipe 7 are opened at equal intervals from the tangential direction on the inner peripheral surface of the cylinder.
The tube axis direction is 0 to 20 with respect to the plane perpendicular to the cylinder axis.
It is set diagonally downward by about 1°. A cylindrical net 9 is connected to the lower end of the cylinder 1 as a liquid draining member, and a funnel 10 for collecting powder is attached to the lower end of the net 9. A cover 11 is provided around the.

The coolant jetting pipe 7 is connected to a tank 12 via a pump 3. Further, the bottom of the cover 11 is piped to a tank 12, and the cover 11 is connected to a tank 12.
The coolant recovered by 1 is returned to the tank 12 and used for circulation. The tank 12 is provided with a cooling liquid supply pipe for replenishment (not shown), and a cooler may be appropriately interposed within the tank or in the middle of the circulation flow path. Water is generally used as the coolant, but oil may also be used.

An injection crucible 2 serving as a molten metal injection means is provided on the top of the lid 5, and a heating induction coil 14 is wound around its outer periphery, and a nozzle hole 15 is formed at its bottom. It has been established. An inert gas such as Ar or N 2 and molten metal are pumped into the injection crucible 2 , and the molten metal 22 in the crucible 2 is injected into the cooling liquid layer 21 from the nozzle hole 15 . Incidentally, the injection crucible 2 is made of a refractory material such as graphite or silicon nitride.

To carry out the present invention, first, the pump 3 is operated to form a cooling liquid layer 21 flowing down on the inner peripheral surface of the cylinder 1 while swirling at high speed. That is, the coolant jetted from the coolant jet pipe 7 along the inner circumferential surface of the cylinder 1 flows down while swirling along the inner circumferential surface of the cylinder 1, overflows the sleeve 6, and flows downward. do. At this time, the cooling liquid layer 21 having a substantially constant thickness is easily formed on the inner circumferential surface of the sleeve 6 due to the action of centrifugal force during the rotation of the cooling liquid. To change the thickness of the coolant layer 21, the discharge amount and discharge pressure of the coolant may be adjusted, but it is also possible to replace the sleeve 6 with one with a different wall thickness while keeping the coolant discharge conditions constant. You can easily adjust the layer thickness by simply doing this.

Since the cooling liquid layer 21 is formed by constantly newly supplied cooling liquid, a constant temperature can be easily maintained. Therefore, there is no need to supply or discharge cooling liquid from the liquid level for temperature control, and the liquid level is less likely to be disturbed.
Excellent stability. Next, an inert gas such as Ar gas is pumped into the injection crucible 2 provided at the top of the cylinder 1, and the molten metal 22 in the crucible 2 is injected from the nozzle hole 15 toward the inner surface of the cooling liquid layer 21. The sleeve 6 is divided by the swirling flow, passes through the cooling liquid layer 21, and collides with the inner circumferential surface of the sleeve 6, thereby deforming it into a flat shape. The degree of deformation is adjusted by the rotation speed of the cooling liquid layer 21, the layer thickness, the injection temperature of the molten metal, the injection pressure, etc. However, the thickness of the cooling liquid layer 21 is
In order to prevent the unsolidified metal particles separated by the cooling liquid layer 21 from solidifying before contacting the inner circumferential surface of the sleeve, it is necessary to set the layer thickness to an appropriate value by taking into account the size of the separated particles, the temperature of the cooling liquid, etc. There is.

The metal particles deformed by the sleeve 6 are cooled and solidified by a cooling liquid, and flat metal powder is continuously manufactured. This powder has excellent quality stability because it is formed by a cooling liquid layer whose temperature and liquid level are stable. The metal powder in the cooling liquid layer 21 flows down over the sleeve 6 while swirling together with the cooling liquid, and enters the liquid draining net 9 from the lower end of the cylindrical body 1 . Here, the cooling liquid is scattered and discharged radially outward from the mesh body 9 by the action of centrifugal force, and metal powder with a small liquid content that is primarily removed is obtained.

Since the metal powder that has been primarily deliquified by the mesh body 9 and discharged from the funnel body 10 has a small liquid content, it is sequentially passed through a suitable deliquid device such as a centrifuge to quickly remove the liquid. is almost completely eliminated and is easily dried to form a product powder. In the above embodiment, the sleeve 6 was provided on the inner peripheral surface of the cooling cylinder 1, and the unsolidified metal particles that had passed through the cooling liquid layer 21 collided with the inner peripheral surface of the sleeve 6 and were deformed. 6 is not necessarily necessary,
The unsolidified particles may directly collide with the inner peripheral surface of the cylinder. In this case, the thickness of the coolant layer is adjusted by the discharge amount and discharge pressure of the coolant.

The shape of the cooling cylinder is not limited to the cylindrical shape as shown in the figure, but may also be, for example, a funnel shape with a circular cross section whose inner peripheral surface is an upwardly expanding paraboloid of revolution, or a truncated shape. The head may have an inverted conical shape. In the above embodiment, the molten metal 22 in the injection crucible 2 is injected from the nozzle hole 15 by applying a pressure medium to the nozzle hole 15, but without applying a pressure medium, the molten metal 22 itself is (self-weight)
The molten metal in the lower part of the injection crucible 2 may be pressurized by this method, and may be injected (spouted) from the nozzle hole 15. In this case, the axis of the cylinder 1 is slightly inclined with respect to the vertical direction, and the molten metal is spouted from the nozzle hole 15 directed vertically downward, and the molten metal falling by gravity is mixed with the cooling liquid formed on the circumferential surface of the cylinder. It is better to supply it to layers.

The present invention is of course applicable not only to the production of lightweight metal powders such as Al alloys and Mg alloys, but also to the production of metal powders such as iron and its alloys.

[0020]

[Effects of the Invention] As explained above, according to the method for producing metal powder of the present invention, the cooling liquid is jetted and supplied along the inner peripheral surface of the cylinder, and the cooling liquid is supplied along the inner peripheral surface of the cylinder or the sleeve. Since a cooling liquid layer is formed that flows downward while swirling, the inner peripheral surface of the cooling liquid layer to which molten metal is injected is stabilized and the temperature is maintained uniformly. Then, molten metal is injected into the cooling liquid layer, and the metal particles are deformed by colliding with the inner circumferential surface of the cylinder or the inner circumferential surface of the sleeve before solidification, so that rapidly solidified powder with stable quality and a flat shape with a large surface area is produced. It is produced continuously and there is no clogging of the injection nozzle.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view of a main part of a metal powder manufacturing apparatus according to an example.

FIG. 2 is an explanatory cross-sectional view of a main part of a conventional metal powder manufacturing apparatus.

[Explanation of symbols]

1 Cooling cylinder 2 Injection crucible (molten metal injection means) 3 Pump (
Coolant supply means) 6 Sleeve 7 Coolant jet pipe 9 Liquid draining net 21 Coolant layer 22 Molten metal

Claims (2)

[Claims] Claim 1: Forming a cooling liquid layer that flows down while swirling along the inner circumferential surface of a cooling cylinder, injecting molten metal from the inner circumferential side of the cooling liquid layer, and dividing the metal by the cooling liquid layer. A method for producing metal powder, characterized in that unsolidified metal particles are deformed by colliding against the inner peripheral surface of a cylinder, and then cooled and solidified to obtain flat-shaped metal powder. 2. A replaceable sleeve is provided on the inner circumferential surface of the cooling cylinder, a cooling liquid layer is formed that flows downward while swirling along the inner circumferential surface of the sleeve, and the inner circumferential surface of the cooling liquid layer is formed. Production of metal powder characterized by injecting molten metal from the side, dividing it by a cooling liquid layer, colliding and deforming unsolidified metal particles against the inner peripheral surface of a sleeve, cooling and solidifying them to obtain flat-shaped metal powder. Method.