JP7231159B2 - METAL POWDER MANUFACTURING DEVICE AND METHOD FOR MANUFACTURING METAL POWDER - Google Patents

Description

The present disclosure relates to a metal powder production apparatus for producing metal powder and a method for producing metal powder.

As a method for producing metal powder, an atomizing method is known, in which molten metal is dripped and pulverized into droplets, and the droplets are cooled to form metal powder. As the atomization method, a gas atomization method for pulverizing with high-pressure gas and a water atomization method for pulverizing with high-pressure water are known.

In addition, as a kind of gas atomization method, a combustion flame gas atomization method is known, in which molten metal is pulverized by a supersonic combustion flame (for example, Japanese Patent Application Laid-Open No. 2014-136807, International Publication No. 2012-157733). It is known that combustion flame gas atomization can break molten metal into fine droplets and form a finer metal powder than conventional gas atomization.

In the combustion flame gas atomizing method described in Patent Literatures 1 and 2, the concentratedly injected combustion flame becomes an ejected convergent flow of supersonic gas flow and is ejected directly below from the concentration point. At that time, an air flow following the gas flow is formed around the upstream portion of the jet convergent flow, but since the jet convergent flow is supersonic, there is a negative pressure portion around the upstream portion of the jet convergent flow, i.e. , areas with lower atmospheric pressure than the surrounding area are more likely to occur.

In particular, in a "confined type" metal powder manufacturing apparatus in which molten metal is suspended from the lower end of a hollow tube and a combustion flame is injected along the outer periphery of the lower end, the combustion flame injection means is positioned above the jet convergent flow. Since it is clogged, a negative pressure portion is likely to occur around the upstream portion of the ejected converging flow.

Such a negative pressure portion attracts the ejected convergent flow and repeats generation and disappearance, which may cause the ejected converged flow to fluctuate. In other words, the generation of the negative pressure portion may cause the jet convergent flow to oscillate and generate turbulence. As a result, the pulverization of the molten metal becomes unstable, and the particle size distribution of the formed metal powder deteriorates, making it impossible to obtain the desired particle size distribution.

Therefore, an object of the present disclosure is to provide a metal powder production apparatus and a metal powder production method that can suppress the fluctuation of the jet convergent flow and produce a stable jet convergent flow.

A metal powder manufacturing apparatus according to a first aspect includes a supply means for dropping molten metal, and a supersonic combustion flame is intensively injected from a combustion flame injection port to the molten metal hanging from the supply means, and the concentrated combustion It has combustion flame injection means for making a flame into an ejecting convergent flow and ejecting it directly below, and a stabilizing member for stabilizing the atmosphere around the upstream portion of the ejecting convergent flow.

According to the metal powder manufacturing apparatus according to the first aspect, it is possible to suppress the generation of negative pressure around the upstream portion of the focused jet flow, suppress the oscillation of the focused jet flow, and make it a stable focused jet flow. can be done. As a result, it is possible to provide a metal powder manufacturing apparatus capable of stably pulverizing molten metal, that is, capable of forming fine metal powder having a good particle size distribution.

The "upstream part of the jet convergent flow" referred to here is the part where the supersonic combustion flame concentrates to form the jet convergent flow, and the part containing the supersonic combustion flame just before the concentration. means Further, stabilizing the atmosphere specifically means suppressing the generation of a negative pressure portion, suppressing fluctuations in pressure in the atmosphere, and the like.

A metal powder production apparatus according to a second aspect is the metal powder production apparatus according to the first aspect, wherein the stabilizing member has a cylindrical portion that allows the jet convergent flow to pass from an upper end opening to a lower end opening, and A gap is provided between the upper end opening of the cylindrical portion and the combustion flame injection means, and is arranged around the upstream portion of the jet convergent flow.

According to the metal powder manufacturing apparatus according to the second aspect, since the gap is provided between the upper end opening of the cylinder and the combustion flame injection means, the atmosphere gas around the cylinder is drawn into the ejected convergent flow, It is possible to form an airflow that flows into the surroundings of the jetted focused flow from the upstream portion of the jetted focused flow to the upper end opening of the cylindrical portion. As a result, it is possible to suppress the generation of a negative pressure portion around the upstream portion of the jet converging flow, and to obtain a stable jet converging flow.

A metal powder production apparatus according to a third aspect is the metal powder production apparatus according to the first aspect, wherein the stabilizing member has a gas injection section for injecting gas around an upstream portion of the jet converging flow.

According to the metal powder manufacturing apparatus according to the third aspect, by injecting the gas from the gas injection part around the upstream portion of the jet convergent flow, it is possible to cause the airflow to flow into the upstream portion of the jet convergent flow. As a result, it is possible to suppress the generation of a negative pressure portion around the upstream portion of the jet converging flow, and to obtain a stable jet converging flow.

A metal powder manufacturing apparatus according to a fourth aspect is the metal powder manufacturing apparatus according to the first aspect, wherein the stabilizing member ejects the stabilizing member from an upper end opening spaced apart from the combustion flame ejecting means. It has a tubular portion into which the converged flow flows, and has a fluid ejection port on the inner surface of the tubular portion that ejects fluid to flow downward along the inner surface.

According to the metal powder manufacturing apparatus according to the fourth aspect, since the gap is provided between the upper end opening of the cylindrical portion and the combustion flame injection means, the atmosphere gas around the cylindrical portion is released by the flow of the fluid into the upper end opening. The airflow can be drawn into the cylindrical portion from the upstream portion of the jetted converged flow to the upper end opening of the cylindrical portion to flow the airflow around the jetted converged flow. As a result, it is possible to suppress the generation of a negative pressure portion around the upstream portion of the jet converging flow, and to obtain a stable jet converging flow.

In addition, in the metal powder manufacturing apparatus according to the fourth aspect, since the atmosphere gas around the cylinder can be strongly drawn into the cylinder by the flow of the fluid, the position of the cylinder is changed from the upstream part to the downstream part of the ejected convergent flow. It can also be arranged in a staggered position, i.e. around the jetting focused stream below the focal point of the combustion flame.

A metal powder production apparatus according to a fifth aspect is the metal powder production apparatus according to the fourth aspect, in which a plurality of fluid ejection ports are opened in the circumferential direction of the inner peripheral surface.

With such a fluid ejection port, the atmospheric gas around the cylinder is turned into a spiral airflow and drawn into the cylinder, and the airflow that flows in a spiral from around the upstream part of the jet convergent flow to the upper end opening of the cylinder is generated. can be formed. As a result, it is possible to further suppress the generation of a negative pressure portion around the upstream portion of the jet converging flow, and the position of the jet converging flow can be made constant by the spiral airflow, making it possible to make the jet converging flow more stable.

A metal powder production apparatus according to a sixth aspect is the metal powder production apparatus according to the fourth aspect or the fifth aspect, in which a liquid can be ejected as the fluid.

According to the metal powder manufacturing apparatus according to the sixth aspect, the temperature of the atmosphere gas drawn into the cylindrical portion can be easily lowered. As a result, it is possible to rapidly cool the pulverized droplets by making a stable ejected focused flow, improve the particle size distribution, and easily form an amorphous metal powder. It can be a powder production device.

Here, in the metal powder manufacturing apparatus according to the sixth aspect, the cylindrical portion may be inclined with respect to the jet convergent flow, and the jet convergent flow rushes into the liquid in the cylindrical portion, and the droplets are formed by the liquid. Direct cooling may also be possible. In this case, the liquid flow is preferably a swirling flow, for example, in order to increase the cooling efficiency of the droplets. By doing so, it is possible to more rapidly cool the pulverized droplets, improve the particle size distribution, and make it possible to easily form a more amorphous metal powder. can be a device.
In addition, if the cylindrical portion is tilted too much, the ejected convergent flow may become unstable. Therefore, it is preferable to keep the tilting angle small, preferably within 30 degrees with respect to the jet convergent flow.

A metal powder production apparatus according to a seventh aspect is the metal powder production apparatus according to the second aspect or the fourth aspect, wherein the stabilizing member has a length from the upper end opening to the lower end opening of the cylindrical portion of 10 mm. It is characterized by the above.

In the metal powder production apparatus according to the seventh aspect, since the length from the upper end opening to the lower end opening of the cylindrical portion is set to 10 mm or more, the particle size distribution can be made uniform compared to the case where it is set to less than 10 mm. can be done.

A metal powder production apparatus according to an eighth aspect is the metal powder production apparatus according to the second aspect or the fourth aspect, wherein the gap is 5 mm or more.

In the metal powder manufacturing apparatus according to the eighth aspect, since the gap provided between the upper end opening of the cylindrical portion and the combustion flame injection means is set to 5 mm or more, the predetermined particle size is smaller than the case where the gap is set to less than 5 mm. can be stably and efficiently produced.

In addition, in the method for producing metal powder according to the ninth aspect, a supersonic combustion flame is intensively injected into the drooping molten metal, the combustion flame is made into a jet convergent flow and jetted directly below, and the jet convergent flow is jetted. Atmosphere is allowed to flow in around the upstream section.

According to the metal powder manufacturing method according to the ninth aspect, the atmosphere around the upstream portion of the jet converging flow is stabilized to suppress the occurrence of a negative pressure portion around the upstream portion of the jet converging flow. can be suppressed, and a stable jet convergent flow can be obtained. As a result, a metal powder production method capable of stably pulverizing a molten metal, that is, forming a metal powder having a good particle size distribution can be provided.

According to the metal powder production apparatus and the metal powder production method according to the present disclosure, it is possible to form a fine metal powder having a stable jet convergent flow and a good particle size distribution. have

BRIEF DESCRIPTION OF THE DRAWINGS It is a conceptual diagram which shows the metal powder manufacturing apparatus which is 1st Embodiment of this invention. FIG. 2 is a conceptual diagram showing a metal powder manufacturing apparatus according to a second embodiment of the present invention; FIG. 3 is a conceptual diagram showing a metal powder manufacturing apparatus according to a third embodiment of the present invention; FIG. 5 is a cross-sectional view showing a cylindrical portion and a nozzle of a metal powder manufacturing apparatus according to a fourth embodiment of the present invention;

[First embodiment]
A metal powder production apparatus 10 according to a first embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 1, the metal powder manufacturing apparatus 10 of the present embodiment includes supply means 12 for supplying the molten metal M, and combustion flame injection means 14 for pulverizing the molten metal M to generate droplets Mmp. there is In the metal powder manufacturing apparatus 10, the supply means 12 and the combustion flame injection means 14 are arranged in an open space (eg, in the atmosphere).

The supply means 12 has a container 16 for containing the molten metal M, and a high-frequency coil 18 for heating and melting a metal material to form the molten metal M is arranged on the outer peripheral side of the container 16 . The supply means 12 has a pouring nozzle 20 that communicates with the inside of the container 16 at the center below the bottom surface of the container 16 so that the molten metal M stored inside the container 16 can hang down from the pouring nozzle 20. ing.

At the center of the combustion flame injection means 14, a conical hollow tube portion 22, which is positioned below the supply means 12 and allows the molten metal M to hang down, extends downward. The combustion flame injection means 14 is provided with an annular combustion chamber 24 and a combustion flame injection port 28 for injecting combustion flame 26 . It surrounds the outer circumference.

The combustion flame injection means 14 of this embodiment mixes air and kerosene, which is a hydrocarbon, in the combustion chamber 24, for example, and combusts the mixture, and then goes downward and inward from the combustion flame injection port 28 to inject the combustion flame. The combustion flame 26 can be jetted along the circumference of the port 28 without gaps. The combustion flame 26 has a temperature higher than the melting point of the molten metal M and is jetted as a supersonic gas flow.

The combustion flame injection means 14 is of a confined type, and can inject the combustion flame 26 obliquely downward from the combustion flame injection port 28 below the supply means 12. surrounds the dripping stream Ma of the molten metal M supplied from the pouring nozzle 20, and is concentrated and injected at one point of the dripping stream Ma (hereinafter referred to as a concentration position SP where the combustion flame 26 concentrates on the dripping stream Ma). I am making it possible.

In addition, the combustion flame injection means 14 can intensively inject the combustion flame 26 along the outer periphery of the drooping stream Ma of the molten metal M supplied from the pouring nozzle 20 without gaps and at a uniform injection pressure. The injected combustion flame 26 is allowed to concentrate and collide with the concentrated position SP of the dripping stream Ma.

Furthermore, the combustion flame injection means 14 can inject the combustion flame 26 intensively at a supersonic speed, and the concentrated combustion flame 26 becomes a substantially linear jet convergent flow 34 whose spread is suppressed, and concentrates. It is designed so that it can be ejected vertically downward from the position SP.

Here, when the combustion flame 26 collides with the concentrated position SP of the drooping stream Ma, the molten metal M is pulverized to form atomized metal powder in a molten state, that is, droplets Mmp. (Hereinafter, this pulverization is referred to as primary pulverization.) Then, the ejected convergent flow 34 containing the droplets Mmp maintains a supersonic speed or a high speed close to supersonic speed, and moves along the extension line of the axis CLc of the combustion flame injection means 14. flow down

Since the droplets Mmp generated by the primary pulverization are a liquid having mass, inertial force works and the flowing velocity is lower than that of the ejected convergent flow 34 which is gas. Therefore, in the process of flowing down, the jet convergent flow 34 with a high relative speed pulls the falling droplets Mmp, receives a force that causes them to be torn off, and is re-pulverized into fine particles. (Hereinafter, this pulverization is referred to as secondary pulverization.)

The flow velocity and shape of the jet convergent flow 34 are determined by, for example, the pressure in the combustion chamber 24 and the shapes of the hollow tube portion 22 and the combustion flame injection port 28 . Further, the crushing ability is determined by the ratio of the discharge amount of the molten metal M discharged from the hollow tube portion 22 per unit time to the flow of the jet convergent flow 34 . That is, as the amount of the molten metal M discharged into the jet converging flow 34 increases, the crushing energy per unit volume of the molten metal M decreases, and the crushing becomes insufficient.
On the other hand, the discharge amount of the molten metal M from the hollow tube portion 22 is determined by the dead weight of the molten metal M due to the height of the liquid surface and the air pressure acting on the molten metal M in the container 16 (for example, the environment in which the container 16 is placed). (or the pressure within the pressure vessel if the vessel 16 is located in a pressure vessel (not shown in FIG. 1)) and the lower portion of the combustion flame jet 28. In addition to the pressure, it is determined by the pressure (negative pressure) generated by the entraining flow generated by the ejection of the combustion flame 26 .
The pressure generated by the ejection of the combustion flame 26 is measured by placing a pressure sensor at the entrance of the hole 16a of the vessel 16 communicating with the pouring nozzle 20 in the normal state where the vessel 16 is empty, and discharging the molten metal M at the entrance. It is obtained by measuring the pressure in the This pressure is called top pressure. However, since the top pressure generated by the ejection of the combustion flame 26 greatly depends on the combustion conditions, the ejection amount of the molten metal M and the pulverization energy cannot be controlled completely independently. was considered difficult. Especially in the production method of the present disclosure, in which the combustion flame 26 is intensively injected, pulverization continues for a long time in a high temperature range, so it is important to control the jet convergent flow 34 that affects the secondary pulverization. The top pressure in this embodiment can be controlled so as to be 1.2 times or more the top pressure in the case where the cylindrical portion 36 is not provided.
Therefore, it is possible to increase the discharge amount of the molten metal M discharged from the hollow tube portion 22 as compared with the case where the cylindrical portion 36 is not provided.

(Stabilizing member)
Below the combustion flame injection means 14, as a stabilizing member for stabilizing the atmosphere around the upstream portion of the ejected converging flow 34, a cylindrical portion 36 having a constant diameter is arranged coaxially with the axis line CLc of the combustion flame injection means 14. . The tubular portion 36 is arranged at a constant distance from the lower surface of the combustion flame injection means 14, and an annular gap S1 is provided between the upper end of the tubular portion 36 and the lower surface of the combustion flame injection means 14. . The inner diameter of the cylindrical portion 36 is determined so as to provide an annular gap S2 between the combustion flame 26 and the ejected convergent flow 34 .
It should be noted that the cylindrical portion 36 is preferably arranged between the combustion flame injection means 14 and a portion to which the gas or liquid for cooling the droplets Mmp is supplied.

The length L of the cylindrical portion 36 is the length from the upper end opening to the lower end opening of the cylindrical portion 36, as shown in FIG. The length L of the cylindrical portion 36 is preferably 10 mm or more. If the length L is less than 10 mm, the effect of making the particle size distribution uniform by the cylindrical portion 36 may not be obtained. The lower limit of the length L is preferably 15 mm, more preferably 20 mm. On the other hand, although the upper limit of the length L is not particularly limited, by limiting the length to a certain length, it is possible to prevent the droplets Mmp from adhering to the lower end opening of the cylindrical portion 36 and solidifying.
The jet converging flow 34 is a substantially linear flow whose spread is suppressed, but tends to spread slightly as it moves away from the lower surface of the combustion flame injection means 14 . Therefore, if the cylindrical portion 36 is too long, the droplets Mmp contained in the divergent ejected convergent flow 34 may adhere to the inner surface of the lower side of the cylindrical portion 36 and solidify. In this case, when the metal powder manufacturing apparatus 10 is operated continuously for a long time, the flow passage area of the lower end opening gradually narrows, and the effect of uniforming the particle size distribution may not be obtained. The upper limit of the length L of the tubular portion 36 is preferably 300 mm, more preferably 100 mm, still more preferably 80 mm, and even more preferably 60 mm.

The inner diameter (R2 in FIG. 1) at the upper end of the cylindrical portion 36 communicates with the combustion chamber 24 and is the minimum diameter of the opening of the combustion flame injection port 28 formed below the combustion flame injection means 14 (R2 in FIG. 1). R1) is preferably 1.5 times or more. If it is less than 1.5 times, the scattering droplets Mmp adhere to the inside of the cylindrical portion 36 and are likely to solidify. Twice or more is more preferable. Considering the general width of the jet convergent flow 34 formed by the combustion flame injection means 14, it is preferable that the inner diameter R2 at the upper end of the cylindrical portion 36 is 30 mm or more.
Although the upper limit of the inner diameter of the cylindrical portion 36 is not particularly limited, if the inner diameter exceeds 10 times the minimum diameter R1 of the opening, the effect of the present disclosure by arranging the cylindrical portion 36 may be diminished. Therefore, it is preferable to make it 10 times or less. For example, the inner diameter R2 of the tubular portion 36 is preferably 500 mm or less.

(action, effect)
Next, the operation, functions and effects of the metal powder manufacturing apparatus 10 of this embodiment will be described.

The procedure for producing the metal powder Msp by the metal powder production apparatus 10 is as follows. First, a metal material is put into the container 16 and heated and melted by the high frequency coil 18 to produce the molten metal M. As shown in FIG. At this time, a valve (not shown) closes the hollow pipe portion 22 leading from the inside of the container 16 to the combustion flame injection port 28 so that the molten metal M does not hang down the hollow pipe portion 22 .

Next, the supersonic combustion flame 26 is injected from the combustion flame injection port 28 of the combustion flame injection means 14, the valve (not shown) of the container 16 is opened, and the molten metal M in the container 16 is discharged from the pouring nozzle 20. It is made to flow out vertically downward as a vertical flow Ma.
As a result, the supersonic combustion flame 26 is intensively injected to the concentrated position SP of the downstream flow Ma, the supersonic combustion flame 26 collides with the concentrated position SP of the downstream flow Ma, and the downstream flow Ma is supersonic combustion. The collision energy of the flame 26 causes primary pulverization to generate atomized fine droplets Mmp.

In the present embodiment, the combustion flame injection means 14 can pulverize (primary pulverize) the downflow Ma while heating it with a high-temperature, supersonic combustion flame 26, that is, while reducing the viscosity of the downflow Ma. . By injecting the supersonic combustion flame 26 intensively, the high impact energy of the supersonic combustion flame 26 can pulverize the drooping stream Ma. As a result, the drooping stream Ma can be easily pulverized, and fine droplets Mmp can be obtained.

Then, the combustion flame 26 concentratedly injected at the centralized position SP of the vertical flow Ma flows down in a straight line from the centralized position SP as an ejected convergent flow 34 whose spread is suppressed due to the characteristics of the supersonic gas flow. At that time, the droplets Mmp generated in the form of a mist by the primary pulverization of the combustion flame 26 flow vertically downward together with the ejected converging flow 34 while maintaining a supersonic speed or a high speed close to it.

In the metal powder production apparatus 10 of the present embodiment, the combustion flame injection means 14 can cause the droplets Mmp to flow down together with the high-temperature, high-speed ejected convergent flow 34 . That is, by heating the ejected converged flow 34, the viscosity of the droplet Mmp can be reduced while flowing down, and a relative velocity difference can be generated between it and the supersonic ejected converged flow 34 to allow it to flow down. As a result, the droplets Mmp can be easily secondary pulverized, and finer droplets Mmp can be generated.
The droplets Mmp made fine by the secondary pulverization are then cooled to become fine metal powder Msp.

By the way, if the cylindrical portion 36 is not provided, the air flow may become stagnant around the upstream portion of the jet converging flow 34, generating a negative pressure portion that creates an unstable atmosphere. It may be attracted to an unstable negative pressure portion, and cause the ejected convergent flow 34 to oscillate while repeating generation and disappearance of negative pressure. In the combustion flame gas atomization method, the molten droplets Mmp are finely divided by secondary pulverization by the supersonic jet focused flow 34. Therefore, if the jet focused flow 34 becomes unstable, the secondary pulverization will vary, resulting in particle size. Poorly distributed metal powder Msp may be produced.

On the other hand, in the metal powder manufacturing apparatus 10 of the present embodiment, jetting and converging fuel is jetted and converged around the upper portion of the jetting and converging flow 34 from the annular gap S1 formed between the upper end of the cylindrical portion 36 and the lower surface of the combustion flame injection means 14 . By introducing the airflow C (air around the metal powder manufacturing apparatus 10) so as to draw in the flow 34, generation of a negative pressure portion around the upstream portion of the jet focused flow 34 is suppressed, and the jet is focused. The airflow, or atmosphere, around the upstream portion of stream 34 can be stabilized.
Moreover, it is preferable to form a gap (width w shown in FIG. 1) between the upper end opening of the cylindrical portion 36 and the lower surface of the combustion flame injection means 14 . The width w of the gap is preferably 5 mm or more. As will be described later, the particle size of the metal powder Msp can be controlled. That is, fine metal powder Msp having a predetermined particle size can be mass-produced stably, efficiently, and at low cost. The lower limit of the width w of the gap is preferably 7 mm, more preferably 10 mm.
Further, the width w of the gap is preferably 0.1 times or more the inner diameter (R2 shown in FIG. 1) at the upper end of the cylindrical portion 36 within the above range. If it is less than 0.1 times, the jet converging flow 34 may oscillate due to the occurrence of negative pressure, and turbulence may occur, as in the confined metal powder manufacturing apparatus described above. be. As a result, the pulverization of the molten metal M becomes unstable, and the particle size distribution of the formed metal powder Msp deteriorates, which may make it impossible to obtain the desired particle size distribution.
On the other hand, if the upper limit of the width w of the gap exceeds 10 times the inner diameter R2 of the cylindrical portion 36, similarly, a negative pressure portion that creates an unstable atmosphere may be generated. For example, the upper limit of the width w of the gap is preferably 600 mm, and the inner diameter R2 of the tubular portion 36 is preferably 600 mm or less. This upper limit is more preferably 500 mm or less, more preferably 300 mm or less, even more preferably 200 mm or less, and even more preferably 100 mm or less.

As a result, it is possible to form a stable ejecting convergent flow 34 by suppressing the oscillation, enabling stable secondary pulverization of the droplets Mmp, and obtaining a fine metal powder Msp having a good particle size distribution. becomes possible.

According to the metal powder manufacturing apparatus 10 of the present embodiment, since the hollow tube portion 22 from which the molten metal M hangs down extends toward the combustion flame injection port 28, the molten metal M hangs down from the hollow tube portion 22. The distance to the primary pulverization by the combustion flame 26 is shortened, and the primary pulverization is stable. Therefore, stable primary pulverization and stable secondary pulverization make it possible to obtain a metal powder Msp with a better particle size distribution.

In addition, in the metal powder manufacturing apparatus 10 of the present embodiment, water is sprayed toward the ejected convergent flow 34 below the cylindrical portion 36 to rapidly cool the droplets Mmp finely divided by the secondary pulverization, The droplets Mmp pulverized into fine particles may be immersed in a stream of water to be quenched. This makes it possible to obtain amorphous Msp.

In addition, in the present embodiment, it is desirable that the cylindrical portion 36 has a circular cross section, but the cross section is not limited to this. Note that the inner diameter of the cylindrical portion 36 in the case of a non-circular shape is the smallest circle that is coaxial with the central portion of the ejected converged flow 34 and is in contact with the inner diameter of the cylindrical portion 36 when viewed in the direction in which the ejected converged flow 34 is ejected. Let the diameter of the circle be the inner diameter. Furthermore, although the cylindrical portion 36 has a constant diameter in the axial direction, it may have a shape in which the diameter gradually increases in one direction of the axis.

[Second embodiment]
A metal powder manufacturing apparatus 10 according to a second embodiment of the present invention will be described with reference to FIG. In addition, the same code|symbol is attached|subjected to the same structure as 1st Embodiment, and the description is abbreviate|omitted.

As shown in FIG. 2, in the metal powder manufacturing apparatus 10 of the present embodiment, a gas injection section 38 is arranged below the combustion flame injection means 14 as a stabilizing member for stabilizing the atmosphere around the upstream portion of the ejected converging flow 34. It is
The gas injection part 38 has a nozzle 42 for injecting gas from a gas injection port 40 at the tip. The nozzle 42 of this embodiment is formed in an annular shape so as to surround the upstream portion of the jet converging flow 34 and extends radially with respect to the axis of the jet converging flow 34 . In addition, the gas injection port 40 is continuously formed in the circumferential direction. From the gas injection port 40 , the gas G is jetted toward the center of the jet convergent flow 34 in a direction perpendicular to the axis of the jet convergent flow 34 . The gas G ejected from the gas injection port 40 may be air, or may be an inert gas such as argon gas, nitrogen gas, or hydrogen gas, which does not contain oxygen, or a reducing gas.

In this embodiment, by ejecting the gas G from the gas injection port 40 around the upstream portion of the jet converging flow 34, the air flow around the upstream portion of the jet converging flow 34 can be stabilized, and a negative pressure portion is generated. can be suppressed more reliably.

As a result, in the metal powder manufacturing apparatus 10 of the present embodiment, as in the first embodiment, the oscillation of the jet converged flow 34 can be suppressed, and the stable jet convergent flow 34 can be formed. Stable secondary pulverization becomes possible, and fine metal powder Msp having a good particle size distribution can be obtained.

[Third embodiment]
A metal powder manufacturing apparatus 10 according to a third embodiment of the present invention will be described with reference to FIG. In addition, the same code|symbol is attached|subjected to the same structure as embodiment mentioned above, and the description is abbreviate|omitted.

As shown in FIG. 3, in the metal powder manufacturing apparatus 10 of the present embodiment, a cylindrical portion 36 and a gas injection portion 38 are provided as stabilizing members for stabilizing the atmosphere around the upstream portion of the jet converging flow 34 .

The nozzle 42 is provided on the upper side of the cylindrical portion 36 and has a tip portion protruding into the cylindrical portion 36 . The tip portion of the nozzle 42 is directed downward, and the gas G can be injected from the gas injection port 40 along the jet convergent flow 34 that hangs down.

In this embodiment, since the outer peripheral side of the airflow flowing along the suspended jet convergent flow 34 is covered with the cylindrical portion 36, the jet convergent flow 34 can be formed in a more stable manner.

[Fourth Embodiment]
A metal powder manufacturing apparatus 10 according to a fourth embodiment of the present invention will be described with reference to FIG. In addition, the same code|symbol is attached|subjected to the same structure as embodiment mentioned above, and the description is abbreviate|omitted.

As shown in FIG. 4 , in the metal powder manufacturing apparatus 10 of this embodiment, a plurality of (four in this embodiment) nozzles 44 extending along the tangential direction of the cylindrical portion 36 are arranged in the circumferential direction of the cylindrical portion 36 . placed at intervals.

Gas G can be jetted from the nozzle 44 along the inner peripheral surface of the cylindrical portion 36 . Thus, by forming a swirling flow of the gas G so as to surround the focused jet flow 34 inside the cylindrical portion 36, the suspended focused jet flow 34 can be stably disposed at the center of the swirling flow.

[Experimental result 1]
The relationship between the length L of the cylindrical portion 36 and the particle size distribution of the obtained metal powder Msp is shown below.
In this embodiment, the metal powder manufacturing apparatus 10 of FIG. 1 was used.
The molten metal M of the supply means 12 has an alloy composition of FeSiCrC system.
The minimum diameter R1 of the opening of the combustion flame injection port 28 was set to 25 mm.
The cylindrical portion 36 shown in FIG. 1 was used as a stabilizing member. The tubular portion 36 is made of SUS304 material and has a cylindrical shape with an inner diameter of 46 mm and an outer diameter of 50 mm. Moreover, the length L from the upper end opening to the lower end opening was 20 mm, 40 mm, and 60 mm (Sample Nos. 1, 2, and 3).
The width w of the gap between the upper end opening of the cylindrical portion 36 and the lower surface of the combustion flame injection means 14 is No. 1 and 2, 10 mm; 3, it is set to 20 mm.
The volume distribution (median diameter: D10, D50, D90) of the particle size of the obtained metal powder Msp was measured using a laser diffraction/scattering particle size distribution analyzer (model MT3300) manufactured by Microtrack.
Table 1 shows the measurement results. In addition, the numerical value of (D90-D10)/D50, which represents the variation in particle size, is also shown. The smaller the numerical value, the smaller the variation.
As the length of the cylindrical portion 36 increases, the particle size of the obtained metal powder Msp increases. Also, the numerical value of (D90-D10)/D50 is the same as that of No. The numerical value of 1 (2.3) is small.
Since the metal powder manufacturing apparatus 10 of the present embodiment intensively injects the supersonic combustion flame 26 from the combustion flame injection port 28 into the molten metal M, the apparatus tends to be large-scaled, and adjustment of the injection speed and the combustion temperature is difficult. It can get difficult. However, even with such a metal powder manufacturing apparatus 10, the particle size of the metal powder Msp can be controlled by changing the shape of the cylindrical portion 36. FIG. That is, fine metal powder Msp having a predetermined particle size can be mass-produced stably, efficiently, and at low cost.

[Experimental result 2]
The relationship between the particle size distribution of the metal powder Msp and the width w of the gap between the upper end opening of the cylindrical portion 36 and the lower surface of the combustion flame injection means 14 is shown below.
In this embodiment, the metal powder manufacturing apparatus 10 of FIG. 1 was used.
As the molten metal M of the supply means Msp, one having an alloy composition of FeSiCrC system was used.
The minimum diameter R1 of the opening of the combustion flame injection port 28 was set to 25 mm.
The cylindrical portion 36 shown in FIG. 1 was used as a stabilizing member. The cylindrical portion 36 is made of SUS304 material, has a circular cross section in the horizontal direction of the drawing, and has an inner diameter of 60 mm at the upper end opening and 80 mm at the lower end opening. Moreover, the length L from the upper end opening to the lower end opening was set to 230 mm.
In the present embodiment, the lower end side of the cylindrical portion 36 is inserted into a cylindrical cooling case (not shown) extending in the same direction as the cylindrical portion 36, and water is sprayed onto the jet converging flow 34. The structure is such that the droplet Mmp can be cooled.
The volume distribution (median diameter: D10, D50, D90) of the particle size of the obtained metal powder Msp was measured using a laser diffraction/scattering particle size distribution analyzer (model MT3300) manufactured by Microtrack.
Table 2 shows the measurement results. In addition, the numerical value of (D90-D10)/D50, which represents the variation in particle size, is also shown.
When the gap width w is in the range of 20 mm to 60 mm, the numerical value of (D90-D10)/D50 tends to decrease as the gap width increases. That is, by changing the width w of the gap, the particle size of the metal powder Msp can be controlled, and fine metal powder Msp having a predetermined particle size can be mass-produced stably, efficiently, and at low cost.

[Other embodiments]
An embodiment of the present invention has been described above, but the present invention is not limited to the above, and can of course be implemented in various modifications without departing from the gist of the present invention. is.

In the third embodiment, gas is injected from the nozzle 42, but liquid such as water may be injected from the nozzle 42 as well. As a result, the temperature of the atmosphere gas drawn into the cylindrical portion 36 can be easily lowered, and the pulverized droplets Mmp can be rapidly cooled by forming a stable jet convergent flow 34, and the particle size distribution can be improved. It is possible to improve and easily form an amorphous metal powder Msp.

Alternatively, the cylindrical portion 36 may be arranged at an angle with respect to the jet converging flow 34, and the jet converging flow 34 may be plunged into the liquid in the cylindrical portion 36 so that the droplets Mmp can be directly cooled by the liquid. In this case, in order to increase the cooling efficiency of the droplets Mmp, it is preferable that the liquid flow be a swirling flow, for example, like the nozzle 42 shown in the fourth embodiment. By doing so, the pulverized droplets Mmp can be cooled more rapidly, the particle size distribution can be improved, and a more amorphous metal powder Msp can be easily formed. If the cylindrical portion 36 is tilted too much, the jet convergent flow 34 may become unstable. Therefore, it is preferable to keep the tilting angle small, preferably within 30 degrees with respect to the jet converging flow 34 .

A chamber for sucking and recovering the metal powder Msp, a suction device, or the like may be arranged below the metal powder manufacturing apparatus 10 .

The disclosure of Japanese Patent Application No. 2018-026916 filed on February 19, 2018 is incorporated herein by reference in its entirety.
All publications, patent applications and technical standards mentioned herein are to the same extent as if each individual publication, patent application and technical standard were specifically and individually noted to be incorporated by reference. incorporated herein by reference.

Claims (10)

supply means for dripping molten metal;
Combustion flame injection means for intensively injecting supersonic combustion flame from a combustion flame injection port into the molten metal hanging down from the supply means, and for ejecting the concentrated combustion flame as an ejection convergence flow directly below;
a stabilizing member for stabilizing the atmosphere around the upstream portion of the ejected focused flow;
A metal powder manufacturing device having a The stabilizing member has a cylindrical portion through which the jet converging flow passes through a lower end opening. 2. The metal powder manufacturing apparatus according to claim 1, arranged around the upstream portion of the jet focused flow. 2. The metal powder manufacturing apparatus according to claim 1, wherein said stabilizing member has a gas injection section for injecting gas around an upstream portion of said ejected convergent flow. The stabilizing member has a tubular portion which is arranged with a gap from the combustion flame injection means and allows the jet convergent flow to pass through a lower end opening, and ejects a fluid onto the inner surface of the tubular portion to 2. A metal powder production apparatus according to claim 1, having a fluid ejection port that flows downward along the inner surface. 5. The metal powder manufacturing apparatus according to claim 4, wherein a plurality of said fluid ejection ports are opened in the circumferential direction of said inner surface. 6. The metal powder manufacturing apparatus according to claim 4, wherein liquid can be ejected as said fluid. 5. The metal powder manufacturing apparatus according to claim 2, wherein the stabilizing member has a length of 10 mm or more from the upper end opening to the lower end opening of the cylindrical portion. 5. The metal powder manufacturing apparatus according to claim 2, wherein said gap is 5 mm or more. A supersonic combustion flame is intensively injected into the drooping molten metal, and the combustion flame is formed into an ejected convergent flow and ejected directly below. A method for producing metal powder, wherein the combustion flame is spouted in a state. 10. The method for producing metal powder according to claim 9, wherein said stabilizing member causes an airflow to flow around an upstream portion of said ejected focused flow.

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