JP5141370B2 - Acicular metal powder manufacturing apparatus, acicular metal powder manufacturing method, and acicular metal powder - Google Patents

Description

  The present invention relates to an acicular metal powder production apparatus, an acicular metal powder production method, and an acicular metal powder.

When a needle-like metal (short metal fiber) having a length of about several mm is added to a ceramic material, a resin material, or the like, a high-strength composite material without significant increase in weight can be realized. Such composite materials are used in a wide variety of fields such as aviation, space, and transportation.
Moreover, since short metal fibers are excellent in conductivity in the longitudinal direction, such composite materials are also used as electromagnetic shielding materials.

By the way, the short metal fibers as described above are conventionally manufactured by a method of processing a block-like or belt-like metal material into fine needle-like particles by a cutting method.
Patent Document 1 discloses a method of cutting a metal material into a needle shape by applying a cutting tool having a plurality of outer blades on a circumferential surface to the metal material while rotating.
Here, in the method by cutting, it is necessary to prepare a metal material of a certain size. However, since the metal material having a special crystal structure such as an amorphous metal cannot produce a bulk material having a certain size, the above-described cutting process cannot be applied.

In the case of an amorphous metal, a metal foil having a thickness of about several tens of μm can be produced. However, the manufacturing process requires a great deal of labor and cost, and the production efficiency is extremely poor. Furthermore, since there is a limit to reducing the size of the cutting tool, it is difficult to produce fine needle-like particles having an outer diameter of about several μm.
Due to the problems described above, conventionally, fine needle-like particles of amorphous metal could not be efficiently produced.

Japanese Patent Laid-Open No. 9-183021

  An object of the present invention is to provide an acicular metal powder production apparatus and an acicular metal powder production method capable of efficiently producing fine acicular particles of amorphous metal, and an amorphous metal fine article produced by the production apparatus. The object is to provide acicular metal powder.

The above object is achieved by the present invention described below.
The needle-shaped metal powder manufacturing apparatus of the present invention has a cylindrical body that holds a coolant flow generated by swirling the coolant along the inner wall surface;
A molten metal supply unit for dropping or ejecting a molten metal having a composition that can be converted into an amorphous metal by rapid solidification into a coolant flow in the cylindrical body;
The cylindrical body is provided with a concave portion in which the inner wall surface is partially recessed,
By dropping or ejecting the molten metal toward the concave portion, the molten metal is deformed into a needle shape by the water flow of the cooling liquid flow, and is rapidly cooled and solidified to obtain the needle-shaped powder of the amorphous metal. It is characterized by.
Thereby, the fine acicular particle | grains of an amorphous metal can be manufactured efficiently.

In the manufacturing apparatus of the acicular metal powder of the present invention, the concave portion is preferably a groove.
Thereby, the probability that a molten metal will be caught in a recessed part can be raised. As a result, the molten metal can be deformed into a needle shape with a high probability, and finally, it is possible to prevent the recovery of particles that are nearly spherical without being deformed into a needle shape.
In the acicular metal powder manufacturing apparatus of the present invention, it is preferable that the groove is provided so that the formation direction thereof is parallel to the swirl direction of the coolant flow.
Thereby, the resistance of the coolant flow with respect to the groove is suppressed, and wear of the groove can be prevented.

In the acicular metal powder manufacturing apparatus of the present invention, it is preferable that the groove has a shape in which the width gradually decreases as the depth of the groove increases.
Since the groove width varies depending on the depth of such a groove, the molten metal easily enters and gets caught regardless of the size of the molten metal. Thereby, since a molten metal can be fixed over a long period of time, a more elongate acicular metal powder can be manufactured.

In the manufacturing apparatus of the acicular metal powder of the present invention, the average depth of the groove is preferably 50 μm to 3 mm.
Thereby, the molten metal of the magnitude | size comparable as the depth of a groove | channel can be capture | acquired reliably.
In the needle-shaped metal powder manufacturing apparatus of the present invention, a plurality of the grooves are formed in parallel,
The average interval between the grooves is preferably 100 μm to 20 mm.
Thereby, a groove | channel with sufficient width | variety is required and sufficient density, and the probability that a molten metal will be capture | acquired by a groove | channel can be raised more.

In the acicular metal powder manufacturing apparatus of the present invention, it is preferable that the protrusion formed between the plurality of grooves has a curved protrusion in its cross-sectional shape.
Since the ridges having such a shape are unlikely to obstruct the flow of the cooling liquid flow, it is possible to prevent the cooling liquid flow rate from being lowered by the ridges and to prevent the cooling capacity of the cooling liquid flow from being lowered. .
In the apparatus for producing acicular metal powder according to the present invention, the vicinity of the inner wall surface of the cylindrical body is preferably made of a material having a hardness higher than that of the amorphous metal.
Thereby, abrasion of the inner wall surface and recessed part of a cylindrical body can be reduced.

In the acicular metal powder production apparatus of the present invention, the acicular metal powder production apparatus uses a fluid jet that scatters the molten metal by colliding with the molten metal before the molten metal is dropped or ejected. It is preferable to have a nozzle for spraying.
Thereby, a finer acicular metal powder can be manufactured. Further, since the molten metal can be cooled by both the fluid jet and the coolant flow, the cooling rate can be improved. Thereby, even the molten metal of a metal material with low amorphous formation ability can be amorphized reliably.

In the acicular metal powder manufacturing apparatus of the present invention, the amorphous metal is preferably a Fe—Si—Cr alloy or a Fe—Si—B alloy.
Since these alloys are composed of inexpensive components and have a relatively high amorphous forming ability, the molten metal has an appropriate viscosity, and the molten metal can be reliably stretched. For this reason, a more elongate acicular metal powder can be manufactured efficiently.

In the needle-shaped metal powder manufacturing apparatus according to the present invention, a flight path of the molten metal when the molten metal is dropped or ejected toward the coolant flow is configured to be inclined with respect to the axis of the cylindrical body. It is preferable that
As a result, the molten metal that has fallen or ejected collides against the inner wall surface of the cylindrical body and a relatively wide range of the coolant flow formed on the inner wall surface. As a result, the falling point of the molten metal can be dispersed, and the cooling efficiency of the molten metal by the cooling liquid flow is enhanced, and the molten metal is caught in a wide range of grooves, thereby increasing the production efficiency of the acicular metal powder. Can do.

The method for producing acicular metal powder according to the present invention uses a cylindrical body having a concave portion in which an inner wall surface is partially recessed, and swirls the coolant along the inner wall surface of the cylindrical body. A process of generating a cooling liquid flow and cooling or solidifying the molten metal by scattering or ejecting a molten metal having a composition that can become an amorphous metal by rapid solidification to the cooling liquid flow. Have
The molten metal is rapidly cooled and solidified while being deformed into a needle shape by dropping or ejecting the molten metal toward the concave portion provided on the inner wall surface of the cylindrical body.
Thereby, the fine acicular particle | grains of an amorphous metal can be manufactured efficiently.

The acicular metal powder of the present invention is an acicular metal powder whose main material is amorphous metal,
It is manufactured using the manufacturing apparatus of the acicular metal powder of this invention, It is characterized by the above-mentioned.
Thereby, fine acicular particles are obtained.
In the acicular metal powder of the present invention, the acicular metal powder preferably has an average outer diameter of 2 to 200 μm and an average length of 10 μm to 10 mm.
Such needle-shaped metal powders are sufficiently thin and long in outer diameter, and therefore have a large surface area, which is particularly effective for applications that utilize this (for example, metal powders for fillers and electromagnetic shielding materials). It is.

The acicular metal powder of the present invention preferably has an aspect ratio of 5 to 100.
Such a needle-shaped metal powder is thin and long, and therefore has a particularly large surface area. For this reason, when such a metal powder is used as a filler, for example, the metal powder can be spread over a wide range in the composite material. Thereby, a wide range in the composite material can be reinforced without a significant increase in weight. Further, the needle-shaped metal powder having the aspect ratio as described above is easily entangled with each other when gathered together. For this reason, the probability of contacting each other increases, and for example, the thermal conductivity and conductivity of the composite material can be further increased.

The acicular metal powder production apparatus, acicular metal powder production method, and acicular metal powder of the present invention will be described in detail below with reference to the accompanying drawings.
<First Embodiment>
First, a first embodiment of an apparatus for producing acicular metal powder (a method for producing acicular metal powder) of the present invention will be described.
The acicular metal powder production apparatus and acicular metal powder production method of the present invention are an apparatus and a method for producing fine acicular metal powder composed of amorphous metal.

FIG. 1 is a schematic view (longitudinal sectional view) showing a first embodiment of the needle-shaped metal powder manufacturing apparatus of the present invention, and FIG. 2 is a partially enlarged view of the needle-shaped metal powder manufacturing apparatus shown in FIG. . In the following description, the upper side in FIG. 1 is referred to as “upper” and the lower side is referred to as “lower”.
A metal powder production apparatus 1 (acoustic metal powder production apparatus of the present invention) 1 shown in FIG. 1 is a molten metal 32 obtained by melting a metal material as a raw material, and an inner wall surface of a cylindrical body (cylindrical body) 2. An apparatus for producing a metal powder by cooling and solidifying the molten metal 32 while splashing the molten metal 32 by the water flow by bringing it into contact with a water flow (cooling liquid flow) generated by swirling water (cooling liquid) along the line 20. is there.
Such a metal powder manufacturing apparatus 1 has a cylindrical body 2 configured so that water flows down along the inner wall surface 20, and stores molten metal, toward the water flow formed inside the cylindrical body 2, And a supply unit (tundish) 3 for supplying molten metal.

The cylindrical body 2 has a cylindrical shape, and is installed such that its axial direction is inclined by about 10 to 30 ° with respect to the vertical direction. A lid 21 having an opening 210 is attached to the upper end of the cylindrical body 2. On the other hand, the lower end of the cylindrical body 2 is a funnel portion 22 whose inner diameter and outer diameter gradually decrease downward.
A discharge port 231 of a pipe 23 that supplies water to the inside of the cylindrical body 2 is opened on the inner wall surface 20 at the upper part of the cylindrical body 2. The pipe 23 is disposed in a direction in which the tube axis direction in the vicinity of the discharge port 231 is along the tangential direction of the inner peripheral surface of the cylindrical body 2 and is orthogonal to the axis line of the cylindrical body 2. ing. Thereby, the water discharged from the discharge port 231 of the pipe 23 forms a swirling flow (cooling liquid flow) that flows down according to gravity while rotating at a high speed along the inner wall surface 20 of the cylindrical body 2.

Further, the side opposite to the discharge port 231 of the pipe 23 is connected to the tank 5 storing water. A pump 232 is provided in the middle of the pipe 23. By operating the pump 232, the water stored in the tank 5 can be sucked up and supplied to the inside of the cylindrical body 2 through the pipe 23.
Further, the inner wall surface 20 between the discharge port 231 and the funnel portion 22 of the cylindrical body 2 has a ring-shaped reduced diameter protruding from the inner wall surface 20 so that the inner diameter of the cylindrical body 2 is partially reduced. A portion 24 is provided. The diameter-reduced portion 24 reduces the flow velocity of the swirling flow by blocking water discharged from the discharge port 231. As a result, water stays above the reduced diameter portion 24 and a water layer 241 having a thickness corresponding to the height of the reduced diameter portion 24 is formed. Further, the water that has passed over the reduced diameter portion 24 flows downward.

The reduced diameter portion 24 can be removed from the cylindrical body 2 and replaced. Therefore, the thickness of the water layer 241 can be adjusted by appropriately using the reduced diameter portion 24 having a desired height.
Moreover, the reduced diameter part 24 can adjust the installation position up and down.
Further, the wall portion between the reduced diameter portion 24 and the funnel portion 22 of the cylindrical body 2 is constituted by a net-like body 26. Since the mesh body 26 has a large number of holes, the water flowing down inside the cylindrical body 2 flows out of the cylindrical body 2 through the mesh body 26.
Furthermore, the cover 4 is provided outside the mesh body 26 so as to surround the mesh body 26. The cover 4 has a bottomed cylindrical shape, and is configured to receive water flowing from the mesh body 26 to the outside of the cylindrical body 2.

A discharge port 41 is provided at the bottom end of the cover 4 for collecting water discharged from the cylindrical body 2 and discharging it from the cover 4. The water collected from the discharge port 41 is returned to the tank 5. Thereby, the water in the tank 5 can be used repeatedly.
A molten metal supply unit 3 is provided above the cylindrical body 2.

The molten metal supply unit 3 has a bottomed cylindrical shape, and stores therein a molten metal 32 obtained by melting a raw material of metal powder to be manufactured. In the present invention, a metal material having a composition that becomes an amorphous metal when solidified is used as a raw material.
A coil 33 for heating the molten metal supply unit 3 is wound around the outer periphery of the molten metal supply unit 3. By energizing the coil 33 and heating the molten metal supply unit 3, the raw material is melted and the temperature of the molten metal stored in the molten metal supply unit 3 is not lowered.

A through hole 31 is provided at the bottom of the molten metal supply unit 3. The molten metal 32 is discharged from the through hole 31 so as to pass through the opening 210 of the cylindrical body 2.
In addition, the molten metal supply part 3 can introduce | transduce an inert gas in the inside, and can adjust an internal pressure by adjusting the introduction amount of an inert gas. By adjusting the internal pressure of the molten metal supply unit 3 in this way, the discharge amount of the molten metal 32 that is pushed out and discharged from the through hole 31 can be controlled.

  Further, in the molten metal supply unit 3 shown in FIG. 1, the extension of the axis of the through hole 31 is located in the water layer 241 formed in the cylindrical body 2. Thereby, the molten metal 32 discharged from the through hole 31 falls along the axis of the through hole 31 and collides with the water layer 241. As a result, the molten metal 32 is scattered (divided) by the water force of the water layer 241 and is rapidly cooled. The molten metal 32 falls below its melting point and solidifies. In this way, metal powder is generated in the aqueous layer 241.

Moreover, in the metal powder manufacturing apparatus 1 shown in FIG. 1, the thickness is increased by being dammed by the water layer 241. The damped water layer 241 has a lower flow velocity, so that the molten metal 32 continues to contact the water layer 241 for a longer time. As a result, even the molten metal 32 having a large heat capacity can be sufficiently cooled.
Further, on the inner wall surface 20 of the cylindrical body 2, a plurality of annular grooves 271 are provided on the extension line of the axis of the through hole 31 as shown in FIG. 2.

The groove 271 is formed along the circumferential direction of the inner wall surface 20. That is, the formation direction of the groove 271 is provided so as to be substantially parallel to the rotational direction of the swirl flow.
The plurality of grooves 271 are provided at predetermined intervals along the axial direction of the cylindrical body 2.
The cross-sectional shape of the groove 271 shown in FIG. 2 is such that the groove width is accelerated and narrowed as the groove becomes deeper.
On the other hand, between the plurality of grooves 271 protrude relative to the groove 271, and the plurality of protruding portions are respectively annular ridges 28.

Next, the manufacturing method of the acicular metal powder of this invention is demonstrated.
In the method for producing acicular metal powder of the present invention, the molten metal 32 is dropped toward the water layer (cooling liquid flow) 241 generated by swirling the cooling liquid along the inner wall surface 20 of the cylindrical body 2 or This is a method having a step of cooling and solidifying while spattering the molten metal 32 by ejecting.
According to such a method, as described above, a fine needle-like metal powder made of an amorphous metal can be produced.
Hereinafter, this manufacturing method will be described in detail.

[1] First, a metal material having a composition that becomes an amorphous metal when solidified is prepared.
Next, this metal material is put into the supply unit 3 of the metal powder manufacturing apparatus 1, and the coil 33 is energized to melt the metal material by high frequency induction heating. As a result, the molten metal 32 is stored in the molten metal supply unit 3.
Here, the amorphous metal has an irregular atomic arrangement and contains almost no crystal structure or crystal grain boundary inside. For this reason, unlike the crystalline metal, deformation due to dislocations and breakage starting from the crystal grain boundary hardly occur, and the hardness and toughness are high.
Such an amorphous metal is produced by rapidly cooling a raw material from a molten state as described later. In the state where the raw material is melted, the atoms of the raw material are arranged in a disordered state in the liquid state, but when this is rapidly cooled, the molten metal is solidified while maintaining the disordered atomic arrangement. In this way, an amorphous metal is produced.

  Examples of the metal material having a composition that can become an amorphous metal when solidified include, for example, Fe—Si—B, Fe—Si—Cr, Fe—B, Fe—PC—, Fe—Co—Si—B. Fe-Si-B-Nb-based, Fe-based alloys such as Fe-Zr-B-based, Ni-Si-B-based, Ni-based alloys such as Ni-P-B-based, Co-Si-B-based Co-based alloys such as Further, the metal material to be used may be a metal material having a composition that can be a so-called “metal glass” in which a supercooled liquid state described later is relatively stable. In the present specification, the term “amorphous metal” includes metal glass.

  Among such metal materials, Fe—Si—B alloys or Fe—Si—Cr alloys are preferably used. Since these alloys are composed of inexpensive components and have a relatively high amorphous forming ability, the molten metal 32 has an appropriate viscosity, and the molten metal 32 can be reliably stretched. For this reason, a more elongated metal powder can be manufactured efficiently. In addition, since these alloys are relatively excellent in magnetic properties and weather resistance, metal powders applicable to applications utilizing these properties can be obtained.

  [2] Next, the molten metal 32 stored in the molten metal supply unit 3 is dropped from the through hole 31. As a result, the dropped molten metal 32 falls along the axis of the through hole 31 and collides with the water layer 241 as described above. As a result, the molten metal 32 is scattered (divided) by the water force of the water layer 241 and is rapidly cooled. Further, the molten metal 32 that has been scattered and formed into droplets penetrates the water layer 241 with the momentum of the drop, and reaches the groove 271 provided on the inner wall surface 20 of the cylindrical body 2. The molten metal 32 that has reached the groove 271 is fixed to the inner wall surface 20 of the cylindrical body 2 by partly entering the groove 271 and being caught. In addition, although the groove | channel 271 may be a mere cone-shaped hole (concave part), the probability that the molten metal 32 will be caught can be raised by being an elongate groove | channel like this embodiment. As a result, the molten metal 32 can be deformed into a needle shape with a high probability, and finally, it is possible to prevent recovery of particles having a nearly spherical shape without being deformed into a needle shape.

Various states are conceivable as the state in which the molten metal 32 is caught in the groove 271. One example is shown in FIG.
FIG. 3 is a schematic view for explaining a process in which the metal powder is manufactured in the acicular metal powder manufacturing apparatus shown in FIG.
A part of the droplet of the molten metal 32 reaching the groove 271 enters the groove 271 as shown in FIG.

Here, since the water layer 241 is swirling at a high speed, a part of the molten metal 32 caught in the groove 271 is pulled by the water force of the swirling flow (water layer 241). Although the molten metal 32 is rapidly cooled by contact with the water layer 241, since it has not solidified, the molten metal 32 is elongated by being pulled by the water layer 241, as shown in FIG. As a result, the molten metal 32 becomes particles having an elongated needle shape.
Thereafter, the molten metal 32 in the form of needles is further pulled by the water force of the water layer 241 and detached from the groove 271. As a result, the molten metal 32 flows down below the cylindrical body 2 together with the water layer 241. At the same time, the molten metal 32 is cooled by the water layer 241 and solidifies.

  The amorphous metal becomes a “supercooled liquid” state during the cooling period from the molten state to solidification. In this supercooled liquid state, the molten metal 32 is in a liquid state having an appropriate viscosity. In this state, the shape of the molten metal 32 can be easily changed based on an appropriate viscosity while maintaining a disordered atomic arrangement. Therefore, the droplet of the molten metal 32 easily enters the groove 271 and is caught, and is easily stretched by the water force of the water layer 241. As a result, the molten metal 32 is surely changed to a needle shape while maintaining its amorphous state, and then becomes a needle-like metal powder by solidifying.

Further, in the supercooled liquid state, since it does not include a non-uniform structure such as lattice defects or segregation, a homogeneous amorphous metal powder can be easily manufactured.
The above process is performed in an extremely short time. As a result, acicular powder composed of amorphous metal can be efficiently produced.
The specific cooling rate until the molten metal 32 is cooled and solidified is about 10 ⁵ to 10 ⁸ K / sec. By setting the cooling rate within the above range, each atom in the molten metal 32 is regularly arranged and prevented from crystallizing, and the molten metal 32 is prevented from solidifying remarkably quickly. Sufficient time can be ensured for 32 to be stretched under supercooled liquid conditions. That is, if the cooling rate is within the above range, acicular amorphous metal powder can be reliably produced.

  The flow rate of the swirling flow (water layer 241) is preferably about 5 to 100 m / sec, more preferably about 10 to 70 m / sec. If the flow rate of water is within the above range, the cooling rate of the molten metal 32 can be within the above range. In addition, when the flow rate of water exceeds the upper limit, the flow rate of water becomes too fast, and the inner wall surface 20 of the cylindrical body 2 may be worn due to friction with water.

  Incidentally, as described above, the cross-sectional shape of the groove 271 shown in FIG. 2 is such that the width of the groove is accelerated and narrowed as the groove becomes deeper. Since the groove width of such a groove 271 differs depending on the depth thereof, the molten metal 32 easily enters and gets caught regardless of the size of the molten metal 32. Moreover, the molten metal 32 can be more reliably fixed because the width of the groove is acceleratingly narrowing. Thereby, since the molten metal 32 can be fixed over a longer period of time, a more elongated needle-like metal powder can be produced.

Moreover, it is preferable that the average depth of the groove | channel 271 is about 50 micrometers-3 mm, and it is more preferable that it is about 100 micrometers-2 mm. By setting the average depth of the grooves 271 within the above range, the molten metal 32 having the same size as the depth of the grooves 271 can be reliably captured.
If the average depth of the grooves 271 is smaller than the lower limit value, the grooves 271 are too shallow, so that the molten metal 32 is hardly caught. On the other hand, if the average depth of the groove 271 is larger than the upper limit value, the groove 271 is too deep, so that the molten metal 32 enters and cannot easily escape. In this case, the molten metal 32 cannot be removed from the groove 271 due to the swirling flow (water layer 241), and the groove 271 may be filled with the molten metal 32.

On the other hand, the average width of the grooves 271 is preferably about the same as the depth, that is, about 50 μm to 3 mm, more preferably about 100 μm to 2 mm. When the average width of the groove 271 is within the above range, the molten metal 32 having the same size as the width of the groove 271 can be reliably captured as described above.
Further, as described above, the inner wall surface 20 of the cylindrical body 2 is provided with a plurality of grooves 271 along the axial direction of the cylindrical body 2 at predetermined intervals.
At this time, the average interval between the grooves 271 is preferably about 100 μm to 20 mm, and more preferably about 200 μm to 10 mm. If the average interval between the grooves 271 is within the above range, the grooves 271 having sufficient width and sufficient density are provided, and the probability that the molten metal 32 is captured by the grooves 271 is further increased. Can do.

That is, if the average interval between the grooves 271 is less than the lower limit value, the probability that the molten metal 32 enters the groove 271 is remarkably reduced, and there is a possibility that the molten metal 32 cannot be stretched into a needle shape. On the other hand, if the average interval between the grooves 271 exceeds the upper limit, the width of the grooves 271 must be narrowed, so that the molten metal 32 may not enter.
Further, as described above, the ridges 28 are formed between the plurality of grooves 271, but the curved ridges are formed in the cross-sectional shape of the ridges 28 shown in FIG. 2. Since the ridges 28 having such a shape are unlikely to hinder the flow of the water layer 241, it is possible to prevent the flow rate of the water layer 241 due to the ridges 28 from decreasing. As a result, it is possible to prevent the cooling capacity of the water layer 241 from decreasing.

By the way, since the swirling flow flows on the inner wall surface 20 of the cylindrical body 2 at a very high speed, the inner wall surface 20 is ground by water, the molten metal 32 contained therein, and the solidified product (metal powder) of the molten metal 32. Will wear out. In particular, the protruding portion such as the ridge 28 has a remarkable progress of wear.
When the ridges 28 are worn, there is a possibility that they are mixed as impurities in the metal powder from which the ridges 28 are cut. In addition, since the depth and width of the groove 271 change with time, the manufacturing conditions of the needle-shaped metal powder to be manufactured change. As a result, the shape characteristics of the acicular metal powder may become unstable.

On the other hand, when the cross-sectional shape of the ridge 28 has a curved protrusion, the water layer 241 passes through the ridge 28 smoothly, and thus the ridge 28 is less likely to be worn. Therefore, the manufacturing conditions of the acicular metal powder can be kept constant over time, and variations in the shape characteristics of the acicular metal powder can be suppressed.
As described above, since the formation direction of each groove 271 is parallel to the turning direction of the water layer 241, the resistance of the water layer 241 to the groove 271 is suppressed, and the wear of the groove 271 can be prevented. it can.

  Moreover, as a constituent material of the cylindrical body 2, stainless steel, carbon steel, a titanium alloy etc. are mentioned, for example. Among these, the cylindrical body 2 is preferably made mainly of stainless steel. Stainless steel has high weather resistance and can prevent the occurrence of significant rust even when exposed to water for a long time. For this reason, it can prevent that an impurity mixes in the acicular metal powder finally obtained.

  Further, the vicinity of the inner wall surface 20 is preferably made of a material having a hardness higher than that of an amorphous metal formed by solidifying the molten metal 32. Examples of the high hardness material include cemented carbide, tungsten or an alloy thereof, Molybdenum or its alloy is mentioned. By using such a high-hardness material, the wear of the grooves 271 and the ridges 28 described above can be reduced. Such a high hardness material can be formed on the surface of the inner wall surface 20 by a film forming method such as various plating methods or various thermal spraying methods.

Further, in order to reduce the above-described wear, a surface treatment for increasing the hardness may be performed in the vicinity of the inner wall surface 20. Examples of such surface treatment include nitriding treatment.
The needle-shaped metal powder generated as described above is fluidized in the cylindrical body 2 in a state of being suspended in water, and is filtered by the mesh body 26. Then, the needle-shaped metal powder flows down in the funnel portion 22 and is collected from the lower end of the cylindrical body 2. On the other hand, the water that has passed through the mesh body 26 and has flowed out of the cylindrical body 2 is collected by the cover 4 and returned to the tank 5.

In addition, since the collect | recovered acicular metal powder is in the state suspended in water, only acicular metal powder can be collect | recovered by drying this.
According to the above method, it is not necessary to prepare a block-like or strip-like (bulk) amorphous metal (metal glass) as in the conventional method. Can be produced efficiently.

Moreover, since it does not accompany cutting like the past, it can prevent that an impurity mixes in metal powder when a cutting tool wears. Further, conventionally, when producing a fine metal powder, it was necessary to prepare cutting tools of various sizes according to the size (length) and thinness (outer diameter). Therefore, the trouble of preparing such a cutting tool can be saved.
Further, the metal powder produced according to the present invention is made of an amorphous metal and has a needle-like elongated shape. This metal powder is a needle-like metal powder produced by a conventional method. It is finer than that.

  Such acicular metal powder (the acicular metal powder of the present invention) becomes a reinforcing material (filler) that reinforces these materials by being dispersed in a material such as a ceramic material or a resin material. That is, a composite material containing acicular metal powder in a ceramic material or a resin material is excellent in mechanical strength and wear resistance. Further, this composite material has excellent thermal conductivity, conductivity, electromagnetic wave shielding properties, nonflammability and the like derived from the acicular metal powder.

  Moreover, since the acicular metal powder of this invention is comprised with the amorphous metal, it is excellent in the soft magnetic characteristic compared with the metal powder comprised with the crystalline metal. For this reason, the acicular metal powder of the present invention or the composite material containing this powder includes, for example, a core of various electromagnetic parts such as a noise filter, a choke coil, a transformer, a rotation sensor, a magnetic field sensor, a displacement sensor, a distance sensor, and a stress sensor. It is suitably used as a core for various sensors such as a torque sensor and a strain sensor, and a shoplifting prevention tag.

  Further, according to the present invention, although it varies depending on various conditions such as the composition of the molten metal 32, the conditions of the water layer 241 (flow velocity, the thickness of the water layer), the depth and width of the grooves 271, and the arrangement density, A needle-like metal powder having an average outer diameter of about 2 to 200 μm and an average length of about 10 μm to 10 mm can be obtained. Such metal powders are sufficiently thin and elongated in outer diameter, and therefore have a large surface area, which is particularly effective for applications (for example, fillers, metal powders for electromagnetic shielding materials, etc.) that take advantage of this. .

  Moreover, according to this invention, although it changes with various conditions, as an example, the acicular metal powder whose aspect-ratio is about 5-100 can be obtained. Since such metal powder is thin and long, the surface area is particularly large. For this reason, for example, when metal powder is used as the filler, the elongated filler can be spread over a wide range in the composite material. Thereby, a wide range in the composite material can be reinforced without a significant increase in weight. Further, the needle-like metal powder having the aspect ratio as described above is easily entangled with each other when gathered together. For this reason, the probability of contacting each other increases, and for example, the thermal conductivity and conductivity of the composite material can be further increased.

In the metal powder manufacturing apparatus 1 shown in FIG. 1, the flight path of the molten metal 32 when the molten metal 32 falls is inclined with respect to the axis of the cylindrical body 2. Thereby, the dropped molten metal 32 collides with the inner wall surface of the cylindrical body 2 and a relatively wide range of the water layer 241 formed on the inner wall surface. As a result, the falling points of the molten metal 32 can be dispersed, the cooling efficiency of the molten metal 32 can be increased, and the molten metal 32 can be caught in a wide range of grooves 271 to increase the production efficiency of acicular metal powder. Can do.
Note that the shape of the groove 271 provided in the inner wall surface 20 of the cylindrical body 2 may be, for example, as shown in FIG.

The groove 271 shown in FIG. 4 has such a shape that the cross-sectional shape of the groove 271 narrows at a certain rate as the groove becomes deeper. That is, the cross-sectional shape of the groove 271 is a so-called “V-shape”.
The groove 271 is not necessarily a groove, and may be, for example, a conical or pyramidal concave portion (hole).

Second Embodiment
Next, 2nd Embodiment of the manufacturing apparatus (the manufacturing method of acicular metal powder) of the acicular metal powder of this invention is described.
FIG. 5 is a schematic view (longitudinal sectional view) showing a second embodiment of the needle-shaped metal powder production apparatus of the present invention. In the following description, the upper side in FIG. 5 is referred to as “upper” and the lower side is referred to as “lower”.
Hereinafter, although the second embodiment will be described, the description will focus on the differences from the first embodiment, and the description of the same matters will be omitted.
The metal powder manufacturing apparatus 1 according to the present embodiment is the same as that of the first embodiment except that the shape and position of the grooves are different.

  In FIG. 5, the through hole 31 of the molten metal supply unit 3 has an axial extension located in a groove 272 formed by the inner wall surface 20 of the cylindrical body 2 and the wall surface 242 of the ring-shaped reduced diameter portion 24. ing. As a result, the molten metal 32 discharged from the through-hole 31 reaches the groove 272 and gets caught after being scattered by the water force of the water layer 241. As a result, similarly to the first embodiment, the molten metal 32 is elongated and a long and narrow needle-like metal powder can be manufactured.

Here, in FIG. 5, the angle of the groove 272 formed by the inner wall surface 20 of the cylindrical body 2 and the wall surface 242 of the reduced diameter portion 24 is 90 °. This angle is not particularly limited, but is preferably about 20 to 100 °, and more preferably about 30 to 90 °. By making the angle of the groove 272 within the above range, the swirling flow (water layer 241) from the vertically upper side to the lower side of the cylindrical body 2 can flow down without stagnation. As a result, it is possible to suppress a significant decrease in cooling capacity due to the water layer 241 stagnating.
Also in the present embodiment as described above, the same operations and effects as in the first embodiment can be obtained.

<Third Embodiment>
Next, a third embodiment of the acicular metal powder production apparatus (acicular metal powder production method) of the present invention will be described.
FIG. 6 is a schematic view (longitudinal sectional view) showing a third embodiment of the production apparatus for acicular metal powder of the present invention. In the following description, the upper side in FIG. 6 is referred to as “upper” and the lower side is referred to as “lower”.
In the following, the third embodiment will be described. The description will focus on the differences from the first embodiment, and the description of the same matters will be omitted.

The metal powder manufacturing apparatus 1 according to the present embodiment is the same as that of the first embodiment except that a nozzle that ejects a fluid jet toward the molten metal 32 is provided.
The metal powder manufacturing apparatus 1 shown in FIG. 6 has two nozzles 6 that eject a fluid jet 61. These nozzles 6 are inserted into the opening 210 of the lid 21 of the cylindrical body 2 from above. Then, the extension line of the axis of each nozzle 6 intersects the extension line of the axis of the through hole 31 of the molten metal supply unit 3 at one intersection 62 as shown in FIG.

  In the metal powder manufacturing apparatus 1 having such a configuration, the molten metal 32 dropped from the through hole 31 collides with the fluid jet 61 ejected from each nozzle 6 at the intersection 62. As a result, the molten metal 32 is divided into fine droplets 63, and the droplets 63 collide with the water layer 241 and are further divided. That is, the molten metal 32 is pulverized through primary division by the fluid jet 61 and secondary division by the water layer 241. For this reason, according to this embodiment, a finer metal powder can be manufactured compared with the said 1st Embodiment. At the time of collision with the water layer 241, the molten metal 32 collides in a more finely divided state, so that the contact area between the molten metal 32 and the water layer 241 increases, and the cooling rate of the molten metal 32 is further improved. Can be achieved. For this reason, the molten metal 32, which is a metal material having a low amorphous forming ability, can be reliably cooled and made amorphous.

Further, by appropriately setting the fluid type and flow rate of the fluid jet 61, the powder characteristics such as the particle size and particle size distribution of the metal powder can be easily controlled.
The fluid jet 61 ejected from the nozzle 6 includes a liquid jet such as water, a gas jet such as air, nitrogen gas, and argon gas.
Further, the number of nozzles 6 is not particularly limited, and may be three or more. When three or more nozzles 6 are used, it is preferable that the extended lines of the axes of all the nozzles 6 pass through the intersection 62. Further, it is preferable that the arrangement of the nozzles 6 in the horizontal direction is point-symmetric about the intersection 62. Thereby, the molten metal 32 can be uniformly scattered without unevenness.

Also in the present embodiment as described above, the same operations and effects as in the first embodiment can be obtained.
As mentioned above, although the manufacturing apparatus of the acicular metal powder of this invention, the manufacturing method of acicular metal powder, and the acicular metal powder were demonstrated based on suitable embodiment, this invention is not limited to these.
For example, each part which comprises the manufacturing apparatus of acicular metal powder can be substituted with the thing of the arbitrary structures which can exhibit the same function. Moreover, arbitrary components may be added.
Moreover, in the manufacturing method of acicular metal powder, arbitrary processes can also be added as needed.

1. Production of acicular metal powder (Example 1)
First, raw materials were weighed so that each of the following elements was contained in the following contents, and a mixture of the raw materials was melted to obtain a molten metal.
<Composition of raw materials>
・ Si: 7.5% by mass
・ B: 3.8% by mass
・ Cr: 2.3 mass%
・ C: 0.5% by mass
-Fe: remainder Next, the obtained molten metal was pulverized using the manufacturing apparatus of the acicular metal powder shown in FIG. 1, and the acicular metal powder was obtained.
In addition, the formation conditions of the groove | channel provided in the manufacturing apparatus of acicular metal powder are as follows.

<Groove formation conditions>
・ Average depth of grooves: 500 μm
・ Average width of grooves: 500 μm
・ Average spacing of grooves: 1mm
・ Shape of protrusion: Curved shape ・ Component material of cylindrical body: Stainless steel

(Example 2)
An acicular metal powder was obtained in the same manner as in Example 1 except that the apparatus for producing acicular metal powder shown in FIG. 5 was used.
(Example 3)
An acicular metal powder was obtained in the same manner as in Example 1 except that the apparatus for producing acicular metal powder shown in FIG. 6 was used.

(Comparative Example 1)
A metal powder was obtained in the same manner as in Example 1 except that the raw materials were changed to the following. A metal material having the following composition does not become an amorphous metal even when rapidly solidified.
<Composition of raw materials>
・ Si: 3% by mass
Fe: remainder (Comparative Example 2)
A metal powder was obtained in the same manner as in Example 1 except that the molten metal was dropped on the inner wall surface of the cylindrical body of the acicular metal powder manufacturing apparatus shown in FIG. .

2. Evaluation 2.1 Appearance The metal powders obtained in the respective Examples and Comparative Examples were observed with a scanning electron microscope (SEM).
FIG. 7 shows an observation image of the metal powder obtained in Example 1 as a representative. All of the metal powders obtained in each example had very long needles as shown in FIG.
When the average outer diameter and average length of the metal powder were estimated from the observed image, the average outer diameter was 10 μm and the average length was 1 mm. The average aspect ratio was 50.
On the other hand, the metal powder obtained in each comparative example was nearly spherical and did not have a needle shape.

2.2 Crystal structure The metal powder obtained in each of the above examples was subjected to crystal structure analysis by X-ray diffraction. As a result, no sharp peak was observed in the X-ray diffraction spectrum of any metal powder. From this, it was confirmed that each metal powder was composed of an amorphous metal.

It is a mimetic diagram (longitudinal sectional view) showing a 1st embodiment of a manufacturing device of acicular metal powder of the present invention. It is the elements on larger scale of the manufacturing apparatus of the acicular metal powder shown in FIG. It is a schematic diagram for demonstrating the process in which a metal powder is manufactured in the manufacturing apparatus of the acicular metal powder shown in FIG. It is the other structural example of the groove | channel with which the manufacturing apparatus of the acicular metal powder concerning 1st Embodiment is provided. It is a schematic diagram (longitudinal sectional view) showing a second embodiment of the acicular metal powder production apparatus of the present invention. It is a schematic diagram (longitudinal sectional view) showing a third embodiment of the needle-shaped metal powder production apparatus of the present invention. 2 is an observation image of the metal powder obtained in Example 1 by a scanning electron microscope.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Metal powder manufacturing apparatus 2 ... Cylindrical body 20 ... Inner wall surface 21 ... Cover body 210 ... Opening part 22 ... Funnel part 23 ... Piping 231 ... Discharge port 232 ... Pump 24 ... Shrink Diameter 241 ... Water layer 242 ... Wall surface 26 ... Reticulated body 271, 272 ... Groove 28 ... Projection 3 ... Molten metal supply part 31 ... Through hole 32 ... Molten metal 33 ... Coil 4 ... ... Cover 41 ... Discharge port 5 ... Tank 6 ... Nozzle 61 ... Fluid jet 62 ... Intersection 63 ... Droplet

Claims (14)

A cylindrical body that holds the coolant flow generated by swirling the coolant along the inner wall surface;
A molten metal supply unit for dropping or ejecting a molten metal having a composition that can be converted into an amorphous metal by rapid solidification into a coolant flow in the cylindrical body;
The tubular body is provided with a groove in which the inner wall surface is partially recessed,
By dropping or ejecting the molten metal toward the groove , the molten metal is deformed into a needle shape by the water flow of the cooling liquid flow and rapidly cooled and solidified to obtain the needle powder of the amorphous metal. An apparatus for producing acicular metal powder, characterized in that   The said groove | channel is a manufacturing apparatus of the acicular metal powder of Claim 1 provided so that the formation direction may become in parallel with the turning direction of the said cooling fluid flow.   The said groove | channel is the manufacturing apparatus of the acicular metal powder of Claim 1 or 2 which has comprised the shape which a width | variety reduces gradually as the depth of the said groove | channel becomes deep.   4. The apparatus for producing acicular metal powder according to claim 1, wherein the groove has an average depth of 50 μm to 3 mm. A plurality of the grooves are formed in parallel,
5. The apparatus for producing acicular metal powder according to claim 1, wherein an average interval between the grooves is 100 μm to 20 mm.   The apparatus for producing acicular metal powder according to claim 5, wherein the protrusion formed between the plurality of grooves has a curved protrusion in its cross-sectional shape.   The apparatus for producing acicular metal powder according to any one of claims 1 to 6, wherein the vicinity of the inner wall surface of the cylindrical body is made of a material having a hardness higher than that of the amorphous metal.   The needle-shaped metal powder manufacturing apparatus includes a nozzle for ejecting a fluid jet that scatters the molten metal by colliding with the molten metal before the molten metal is dropped or ejected. The manufacturing apparatus of the acicular metal powder in any one of 1 thru | or 7.   The said amorphous metal is a manufacturing apparatus of the acicular metal powder in any one of Claim 1 thru | or 8 which is a Fe-Si-Cr type | system | group alloy or a Fe-Si-B type | system | group alloy.   The flight path of the molten metal when the molten metal is dropped or ejected toward the coolant flow is configured to be inclined with respect to the axis of the cylindrical body. The manufacturing apparatus of the acicular metal powder of description. A cylindrical body having a groove whose inner wall surface is partially recessed is used, and a cooling liquid flow is generated by swirling the cooling liquid along the inner wall surface of the cylindrical body. A step of cooling and solidifying the molten metal with a composition that can be converted into a metal by dropping or ejecting the molten metal toward the cooling liquid flow,
A needle-like shape that rapidly cools and solidifies the molten metal into a needle shape by dropping or ejecting the molten metal toward the groove provided on the inner wall surface of the cylindrical body. A method for producing metal powder. An acicular metal powder mainly composed of amorphous metal,
An acicular metal powder produced using the acicular metal powder production apparatus according to any one of claims 1 to 10.   The acicular metal powder according to claim 12, wherein the acicular metal powder has an average outer diameter of 2 to 200 µm and an average length of 10 µm to 10 mm.   The acicular metal powder according to claim 12 or 13, wherein the acicular metal powder has an aspect ratio of 5 to 100.

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