JPH07102307A - Flake powder material manufacturing method - Google Patents

Abstract

(57) [Summary] [Purpose] To enable efficient production of quenched flake powder material without requiring special materials and specifications for refractories and rolls. When a flake-like powder material is produced by rapidly cooling a molten metal or alloy, the molten metal is caused to flow out from a substantially circular molten metal nozzle 3 arranged in a lower portion of a molten metal storage container 4, and an atomizing nozzle oppositely arranged. The gas jet on the flat plate is jetted from 2 toward the molten metal flow flowing out from the molten metal nozzle 3 to generate a droplet stream having a high density in the rotation axis direction of the cylindrical roll 1 arranged on the outflow side of the molten metal nozzle 3. Then, the generated droplet flow is collided with the surface of the cylindrical roll 1 and rapidly cooled to obtain a flaky powder material. [Effect] Quenched powder material can be efficiently manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a flake-like powder by dropping a molten metal material of a metal or an alloy onto a cooled solid surface, and particularly to a metal having a fine structure by rapid solidification by cooling. The present invention relates to a method for producing a flake powder material suitable for producing a powder or an alloy powder.

[0002]

2. Description of the Related Art As a method for producing a quenched material of metal or alloy, the following quenching casting method, roll cooling method, atomizing method and two-stage cooling method are known.

The quenching casting method is a method of casting a molten metal as a raw material in an ingot case and cooling it. To obtain a powder, the cast material should be made as thin as possible, and the ingot case should have good thermal conductivity such as copper alloy. A material is used, a water cooling jacket or the like is provided inside the ingot case to suppress a temperature rise, and the ingot case is downsized to improve productivity.

In the roll cooling method, a molten alloy material (melt) as a raw material is jetted from a melt nozzle onto a rotating metal roll, or is supplied between rotating twin rolls to be cooled to produce a quenched ribbon. Is. Here, the rolls are usually water cooled and rotate at high speed.

The atomizing method is a method in which a spray medium is sprayed onto a molten metal material as a raw material which has been made to flow in a small diameter or a thin plate, and the powder is produced by cooling. High-pressure water or gas is used as the atomizing medium in consideration of the degree of oxidation of the alloy and the degree of contamination (Japanese Patent Laid-Open No. 2-198620, Japanese Patent Laid-Open No. 4-210409, etc.).

The two-stage cooling method is a method in which the atomizing method and the roll cooling method are combined, and the molten metal of the raw material alloy is made into droplets by gas atomization, and the droplets are sprayed onto a conical rotating roll and rapidly cooled. This is a method for producing flake-like powder (Japanese Patent Laid-Open No. 64-75607, etc.).

[0007]

However, the quality, stability, and economical efficiency of the powders obtained by any of the conventional methods are insufficient, and each has the following problems.

Although the quenching casting method has a higher cooling rate than the general ingot method, it has a limit in thinning the casting thickness, and the average cooling rate of the cast material is at most tens of degrees Celsius.
/ sec. With this value, depending on the alloy system, segregation could not be resolved, and as a result, the desired performance could not be exhibited in many cases. In addition, a step of crushing the ingot is required to obtain the powder material, and a large crusher is required for that purpose, which is also a problem in terms of economy.

It is known that, among the roll cooling methods, the single roll method has a high cooling rate and can produce an amorphous ribbon material. However, in order to stably produce a thin strip, it is necessary to form a molten pool called a paddle on the roll. In order to maintain this paddle in a stable and proper state, the gap between the molten metal nozzle and the roll, the exit slit size of the molten metal nozzle, and the molten metal It is necessary to properly control the injection direction and the like. However, since this control range is actually narrow, it is often difficult to find and maintain the proper state of the paddle.

Further, the refractory used for the molten metal nozzle must be sufficiently resistant to thermal shock due to the temperature difference between the molten metal and the cooled roll and mechanical shock caused by rotation of the roll. Moreover, when a molten metal containing an active component that is easily oxidized is supplied, the appropriate state of the refractory material, particle size and firing conditions differ depending on the alloy type of the molten metal to be supplied. Therefore, refractory parts such as molten metal nozzles that require special shape devises have to be searched by trial and error in order to create those that have sufficient thermal shock resistance, and it takes a lot of time and cost. There was also a problem that it required.

Further, among the roll cooling methods, in the twin roll method, refractory materials called side dams are generally installed at both ends of the twin rolls to form a molten metal pool between the twin rolls, and the molten metal flows out to the side of the rolls. It is necessary to prevent that. However, this side dam also has the same problems as the refractory of the melt nozzle of the single roll method, and in addition, it can sufficiently withstand the reaction with the melt, erosion, and wear due to the rolling surface of the roll, and it can be rolled during operation. It is quite difficult to find and maintain a material and structure for each steel type that can hold the molten metal between the rolls while maintaining good contact with the rolls even if the surface condition of the steel changes. There is.

The atomization method is a method suitable for producing powder, but when the raw material alloy contains a large amount of active metals and components that are easily oxidized and it is necessary to suppress the production of oxides and the like, atomization is performed. An inert gas such as argon or nitrogen must be used as the medium. When such an inert gas is used as the atomizing medium, the cooling rate of the powder becomes relatively small as compared with the roll cooling method, and a sufficient rapid cooling effect cannot be obtained.

The two-stage cooling method is a method in which atomization and roll cooling are combined as a method for solving the problem that a sufficient rapid cooling effect cannot be obtained in the gas atomizing method. That is, it is a method of forming a quenching material by forming molten droplets of the raw material alloy into droplets by gas atomization and spraying the droplets onto a conical rotating roll. However, according to this two-stage cooling method, when the atomized droplet collides with the rotating cone,
Since there is a difference in distance from the melt nozzle between the top and the periphery,
The cooling rates are very different. That is, what collides with the top portion is rapidly solidified by the solid contact with the roll, but at the peripheral portion, it is almost solidified before the collision and is in a gradually cooled state. Due to this difference in cooling rate, segregation of elements and a difference in the state of existence of the second phase occur, and the performance of the produced powder tends to vary. Further, the droplets that have collided with the top portion are thinly deformed, and are removed by the rotating cone to be rapidly cooled and solidified, so that they become flakes. On the other hand, the droplets that collide with the peripheral portion are close to spherical because they collide after being cooled and solidified by gas cooling. Therefore, the generated quenching powder is widely distributed from a spherical shape to a flat shape.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a quench flake powder material efficiently without requiring a special material or specification for a refractory or a roll. It is to be able to manufacture well.

[0015]

Here, the present inventors
The present invention has been completed by finding that the above-mentioned object can be achieved and the problems can be solved by improving the two-stage cooling method.

That is, the method for producing a flake powder material according to the present invention is a method for producing a powder material by rapidly cooling a molten metal or alloy, and the molten metal is arranged in a substantially circular shape at the bottom of the molten metal container. The molten metal outflow process of flowing out from the molten metal nozzle, and the flattened gas jet is jetted from the atomizing nozzle arranged opposite to the molten metal flow flowing out of the molten metal nozzle, and the cylindrical roll of the cylindrical roll arranged on the outflow side of the molten metal nozzle It includes a droplet flow generation step of generating a droplet flow having a high density in the rotation axis direction, and a powder generation step of colliding the generated droplet flow with the surface of a cylindrical roll to rapidly cool it to obtain a flake powder material. It is characterized by

In the droplet flow generating step, even if a gas jet, which is flat and has a flattened jet gas flow rate per unit width from the central portion to the peripheral portion, is jetted from the atomizing nozzle in a facing manner. Good.

Further, heating means is provided in the molten metal container and the molten metal nozzle, the temperature of the inner wall of the molten metal container and the outer wall of the molten metal nozzle is controlled to a predetermined value in the molten metal outflow step, and the gas jet is generated in the molten droplet flow generation step. The gas jet may be jetted so that the relationship between the inner diameter Dn of the molten metal nozzle and the jetting gas flow rate Qg in the directions opposite to each other satisfies the following equation.

Dn <20 · Qg Dn: Molten metal nozzle inner diameter (mm) Qg: Injection gas flow rate (Nm ³ / sec)

[0020]

According to the present invention, a stream of droplets having an appropriate size is produced from a molten metal or alloy stream by gas atomization and is injected onto a cylindrical roll (cooling roll) to produce a flake-like rapidly solidified material. .

In the method for producing a metal or alloy powder according to the present invention, a quenched flake powder material of a metal or an alloy containing an active metal can be efficiently produced, and a refractory material having a special specification (such as a twin roll method) ( For example, impact resistance, wear resistance,
Excellent in high strength, the surface layer is dense to increase wear resistance, and the inside of the main body is compact without using refractory materials such as functionally graded materials that are relatively porous to increase thermal shock resistance. Can be manufactured with various equipment.

The gas atomizing nozzle crushes the raw material molten metal stream supplied from the bottom of the molten metal container into a size suitable for rapid cooling.
It is split and the crushing flow is sprayed into a shape that spreads in a substantially flat plate shape in the axial direction of the cylindrical roll. By performing the flat spray, a droplet stream having a high density is generated in the direction of the rotation axis of the cylindrical roll. By colliding the generated droplet flow with the surface of the rotating cylindrical roll, it is possible to uniformly cool the raw material melt on the cylindrical roll, and the heat load of the roll is also uniformed and averaged. Therefore, the objective can be achieved with the minimum device capacity.

When the surface temperature of the cylindrical roll becomes almost constant by internal water cooling or the like, the cooling rate of the flaky substance which is cooled by closely contacting with the surface of a low temperature solid such as the cylindrical roll is the cooling rate of the flakes. Mostly determined by thickness.
Therefore, by generating flakes of uniform thickness, the cooling rate can be the same, so that the flake-shaped powder material has the same internal structure and the same degree of segregation, and has uniform characteristics and no fluctuation. can do.

As the structure of the atomizing nozzle, the atomizing nozzles are arranged so that the facing direction thereof coincides with the axis of the roll, and the gas jet has a flat plate shape, and the gas flow rate per unit width gradually decreases from the central portion to the peripheral portion. It is desirable to have a structure in which the jetting gas jets are made to face each other.

This is because when the gas flow rate is high in the central part and low in the peripheral part, the upward backflow generated by the collision of the gas jets is strongest in the central part and gradually decreases toward the peripheral part. The droplet flow that has flowed down to the central portion of the gas flows from the central portion of the gas jet toward the peripheral portion. As a result, the droplet flow is also carried to the peripheral portion by this gas flow, and the droplet flow that collides with the peripheral portion of the cylindrical roll becomes larger than that in the central portion.

Here, as the atomizing nozzle of the quenching powder manufacturing apparatus, the flat plate jet nozzles 21 and 22 shown in FIGS. 3 and 4 based on the method of the present invention, and the linear nozzle 2 shown in FIG. The FeSiB material having the chemical composition shown in Table 1 was sprayed and rapidly cooled using the generally used annular nozzle 22a shown in FIG. The main operating conditions are as shown in Table 2.

As a result of the operation, in the flat plate jet nozzles 21 and 22 and the linear nozzle 2 based on the method of the present invention, no particular abnormality was recognized in the cylindrical roll even after the operation was finished.
Conventionally used annular nozzle for comparison
In 22a, although the FeSiB material was slightly welded to the center of the cylindrical roll, it was partially observed. Therefore, it has been found that the annular nozzle in which the spray is concentrated in a limited range of the cylindrical shape is not suitable for combination with the droplet cooling by the cylindrical roll.

[0028]

[Table 1]

[0029]

[Table 2]

In order to produce flakes of uniform thickness,
The container that stores the molten metal and the molten metal nozzle that supplies the molten metal to the atomizing nozzle are equipped with an electric heating device to heat the molten metal, and the temperature of the molten metal in the molten metal storage container and the temperature of the molten metal nozzle are controlled to specified values. By spraying so that the relationship between the inner diameter Dn of the molten metal nozzle in the direction in which the gas jets face each other and the injection gas flow rate Qg satisfy Eq. (1), droplets of a constant temperature are injected onto the roll, A flake-like powder with a constant thickness and consequently a constant cooling rate is produced.

The thickness of the flakes produced by the method of the present invention is almost determined by the size, temperature, and velocity of the droplets (particles in a molten state) immediately before the droplets (molten particles) collide with and deform on the cylindrical roll. By making the amount the same for each droplet, it is possible to produce a flaky powder with a similar cooling rate. The temperature of the droplets may be the same as the temperature of the molten metal in the storage container if the injection state is the same, and the temperature may be controlled so as to maintain a predetermined value from the start to the end of atomization.

Further, the size of the droplet is determined by the interaction between the molten metal stream and the jet gas. Therefore, in order to obtain a droplet group of uniform size, the relation between the momentum of the gas jet acting on the molten metal flow and the mass and flow rate of the molten metal, and It is desirable that the molten metal flow forms are the same.

Further, in order to make uniform the velocity of the droplet just before it is deformed by colliding with the cylindrical roll, it is important to deform / split the droplet stream in the same form. For this purpose, it is desirable that the size of the molten metal flow be sufficiently smaller than that of the gas flow, and that the splitting of the molten metal flow into droplets be performed in one step. On the contrary, when the molten metal flow size is large, the surface and the inside of the molten metal flow have different splitting forms from the molten metal flow to the droplets. That is, in this case, the melt stream is split into droplets in multiple stages inside the melt stream, and the momentum of the jet gas per unit melt mass changes. As a result, the generated droplets have large variations in size and shape.

From these facts, it is understood that the following procedure is required to obtain a flake material having a uniform thickness. That is, by sufficiently reducing the size of the molten metal stream according to the gas flow rate, the splitting of the molten metal stream into droplets by gas injection is performed in one step, and the droplet size becomes uniform and the droplet cylinder The impact velocity on the shaped roll is also made uniform, and the thickness of the flake powder generated by the impact on the cylindrical roll can be made uniform.

The alloys whose components are shown in Table 1 above are shown in Table 2 below.
When the powder is produced under the operating conditions shown in Fig. 3, when the flat plate jet nozzle 21 shown in Fig. 3 is used, and in Fig. 2, a front view from the gas injection side is shown. The thickness of the flaky powder produced when was used was investigated. Generated powder has an inside diameter of about 30 mm and height
Insert it into a 15 mm vinyl chloride cylinder with a bottom, hold it on a vibrating table with a vibration frequency of about 100 Hz for about 10 seconds, align the direction of the foil pieces, then pour resin to solidify and observe the cross section for observation. did. The average value of the thickness of the powder material, Tav, was calculated from the data of about 500 data collected for each sample from the micrograph by image processing.
And the standard deviation σ when fitted to the normal distribution was obtained.
The flat gas jet nozzle 21 has an average value Tav of 45 μm and a standard deviation σ of 1.8, showing a relatively narrow range of distribution, but the linear nozzle 2 has an average powder thickness Tav of 41 μm.
The standard deviation σ was 1.3, and it was found that flaky powder having a very narrow distribution was obtained with the linear nozzle 2.

As a result of further various studies, it was found that, as shown in FIG. 6, the wall thickness distribution of the flake powder is determined by the ratio between the melt nozzle diameter and the jet gas flow rate. These wall thickness distributions are obtained by producing flaky powder under the above-mentioned conditions.

From these results, when the molten metal is sprayed by the linear nozzle and then collided with a cylindrical diameter roll to generate flake powder, in order to suppress the variation in the wall thickness distribution of the flake powder, the diameter of the melt nozzle should be reduced. It was found that the relationship between Dn and the jetted gas flow rate Qg should satisfy the following equation (1).

Dn <20 · Qg (1) Dn: Inner diameter of molten metal nozzle
(mm) Qg: Injection gas flow rate (Nm ³ / sec)

[0039]

EXAMPLE FIG. 1 is a schematic configuration diagram of an example of a quenching powder production apparatus for carrying out the method of the present invention for producing a flake powder from an alloy material containing an active ingredient by a combination of a gas atomizing method and a roll cooling method. is there. In FIG. 1, the quenching powder manufacturing apparatus includes a cylindrical tank 6 having a funnel-shaped lower part, a molten metal storage container 4 and a cylindrical roll 1 arranged vertically inside the tank 6, and a cylindrical roll 1. And a pair of atomizing nozzles 2 arranged to face each other.

A powder recovery bottle 7 is attached to the bottom of the tank 6, and a vacuum suction port 8 and an exhaust gas discharge port 10 are opened on the side surface of the tank 6. The vacuum suction port 8 is connected to a vacuum pump (not shown), and the exhaust gas discharge port 10 is connected to an equipment exhaust duct (not shown). A high pressure gas introduction pipe 9 connected to the atomizing nozzle 2 is inserted on the side surface of the tank 6. Further, a baffle 5 is arranged in the rotation direction of the cylindrical roll 1 in the tank 6. The upper part of the baffle 5 is slightly curved inward. The baffle 5 is provided to prevent flake-like powder scattered from the cylindrical roll 1 from adhering to the inner wall of the tank 6. By providing the baffle 5, the steel type can be changed only by cleaning or replacing the baffle 5. Further, the reason why the upper part is curved inward is to capture not only the horizontal direction but also the flaky powder scattered obliquely upward.

The molten metal storage container 4 is a bottomed cylindrical container lined with an ordinary refractory material.
A raw material molten metal whose components are adjusted by a molten metal container maintaining an inert atmosphere is supplied from a vacuum melting furnace (not shown). At the center of the bottom surface of the molten metal storage container 4, a molten metal nozzle 3 for supplying the molten metal to the cylindrical roll 1 is provided. As shown in FIG. 2, the melt nozzle 3 has a substantially circular cross section. The molten metal storage container 4 and the molten metal nozzle 3 have heaters 11,
A thermocouple 13 for measuring the temperature of the molten metal is inserted in the molten metal storage container 4, and a thermocouple (not shown) is inserted in the nozzle wall of the molten metal nozzle 3. A temperature controller 14 is connected to the heaters 11 and 12 and the thermocouple 13, and controls the molten metal temperature to a predetermined temperature.

The cylindrical roll 1 is a water-cooled roll. The rotating shaft 1a of the cylindrical roll 1 is a hollow shaft, and cooling water for water-cooling the roll 1 flows inside in the direction indicated by ⇒ (white arrow).

The atomizing nozzle 2 is a linear nozzle type, and ejects a long flat plate-like inert gas in the axial direction of the cylindrical roll 1 from the obliquely upper side toward the center with respect to the molten metal flowing out from the molten metal nozzle 3. Is arranged to get.

Further, as shown in FIG. 2, the atomizing nozzle 2 has the ejection ports 2a which are gradually widened from both ends to the central part, and the gas flow rate per unit width is from the central part to the peripheral part. A flat plate-like inert gas that gradually decreases toward the nozzle is ejected.

In this quenching powder manufacturing apparatus, first, the tank 6 is evacuated before starting the operation, and then the inert gas is filled into the tank 6 until the required pressure is reached, if necessary. The molten metal in the molten metal storage container 4 flows downward through the molten metal nozzle 3 from a small hole at the bottom. A high-pressure inert gas is supplied to the atomizing nozzle 2 and is injected from the injection port 2a toward the molten metal stream to generate a droplet group. The droplets collide with the cylindrical roll 1 to be deformed, adhere to the roll surface, cool, and become flakes. The generated flake-like quenched powder material is desorbed from the cylindrical roll 6 by the centrifugal force, hits the baffle 5 and is accumulated in the powder recovery bottle 7 at the bottom of the tank 6.

Experimental Example FeSiB whose chemical composition is shown in Table 1
Using the materials, first, the powder manufacturing apparatus shown in FIG. 1 was operated under the conditions shown in Table 2, and the effect of quenching with or without the cylindrical roll was investigated. The results of judging the characteristics of the produced powder by X-ray diffraction are shown in Table 3.

Amorphous powder was produced by the method of the present invention, which is a combination of the atomizing method and the roll cooling method. However, even though the atomizing nozzle alone has a large gas flow rate as the atomizing medium, it is regarded as an amorphous powder. The crystalline powder was mixed. Therefore, it was found that a sufficiently quenched powder material can be obtained by adding cooling by a cylindrical roll to the atomizing nozzle.

[0048]

[Table 3]

Using the apparatus shown in FIG. 1, quenching materials for hydrogen storage alloys whose chemical components are shown in Table 4 were produced under the operating conditions shown in Table 5. Here, the molten metal storage container 4 and the tank 6 are under the same pressure, and no pressure is applied to the molten metal surface.
At this time, the melt nozzle 3 has an inner diameter of 3.3 mm and 4.8 mm
And the thickness of the flake powder produced by changing the injection gas amount for each of them was measured by the method of embedding / cross-section observation.

As a result, as shown in FIG. 6, when the ratio of the diameter of the molten metal nozzle to the flow rate of the injected gas is less than about 20, the standard deviation of the thickness of the foil side is reduced, and the flake shape with a small variation in thickness is obtained. It was found that a powder was obtained.

[0051]

[Table 4]

Further, in order to investigate the change in the powder characteristics due to the variation in the thickness of the produced flake powder, the same standard deviation of the powder thickness as the one with the standard deviation of 1.3 was used.
700 samples in Ar atmosphere for the flaky powder sample
After heat treatment at ℃ × 10Hr, light crushing was performed with a coffee mill crusher purged with Ar gas, and fine powder that passed through a JIS standard sieve with an opening of 149 μm was collected by a low tap shaker. FIG. 7 shows the results of measuring the pressure-composition isotherm (PCT measurement) as specified in JIS-H-7201.

Sample A with a powder thickness standard deviation of 1.3
In ((▲, △)), a clear plateau region is recognized,
It is judged that the stability of hydrogen absorption / desorption or the voltage stability when used in batteries etc. is excellent, while the standard deviation of the powder thickness is 2.1 for sample B (indicated by ● and ○). In addition to having almost no plateau, the storage amount was lower than that of Sample A. From these facts, when the cooling rate is uniform, proper solution treatment can be carried out by heat treatment, so that the characteristics can be made uniform and improved, and it is judged to be extremely effective as an industrial manufacturing means.

In order to clarify the difference in effect from the conventional two-stage cooling method, the atomizing nozzle 2 is changed from the linear nozzle to the annular nozzle 22a shown in FIG. 5 by the device shown in FIG. Then, the cylindrical roll 1 was changed to a conical roll to produce alloys having the components shown in Table 4 and quenching materials under the conditions shown in Table 6.

[0055]

[Table 6]

It has been clarified from photography that the molten metal spray from the atomizing nozzle diffuses into a conical shape having an apex angle of about 13 °. And the center line of the molten metal spray is
It is 15 mm away from the axis of a conical roll with an apex angle of 45 °, a bottom radius of 150 mm, and a height of 181 mm, and the droplets sprayed in a conical shape are all located at positions where they collide with the conical roll if they go straight. ing.

The powder produced had various shapes, from flake-like to almost spherical. This powder was heat-treated at 700 ℃ × 10Hr in Ar atmosphere in the same manner as described above, then lightly crushed with a coffee mill crusher purged with Ar gas, and opened with a low-tap shaker.
The fine powder passing through a JIS standard sieve of 149 μm was collected. The results of measuring the pressure-composition isotherm (PCT measurement) as specified in JIS-H-7201 are shown in FIG. 7 as Sample C (indicated by ■ and □).

As described above, in Sample A, a clear plateau region was observed, and it was judged that the stability of the inhalation / release of hydrogen or the stability when used in a battery or the like was excellent. The sample C generated in the comparative example has almost no plateau region, and also has a lower occlusion amount than the sample A, and a lower value than the sample B.
As can be seen from this result and the variation in powder shape (the mixture of the spherical powder and the flaky powder), Sample C had a non-uniform cooling rate and poor properties.

[0059]

As is apparent from the above description, according to the method of the present invention, a quenching powder material in which the solidification structure of a hydrogen storage alloy, a magnet alloy or the like containing a large amount of rare earth metal is made fine and uniform, or amorphized. It can be manufactured efficiently. In particular, it is possible to spray a molten metal stream as a group of flat droplets by gas atomization and spray it onto a high-speed rotating cylindrical roll to produce a flake-like quenching material,
Unlike the roll cooling method, the refractory does not require special specifications and materials, so it has excellent device reliability and quality stability of the produced powder.

[Brief description of drawings]

FIG. 1 is a schematic view of a quenching powder manufacturing apparatus based on the method of the present invention.

FIG. 2 is a front view of a gas injection side of an atomizing nozzle of a linear nozzle type.

FIG. 3 is a schematic view showing an atomizing nozzle of a slit nozzle type.

FIG. 4 is a schematic view showing an atomizing nozzle of a circular hole nozzle type.

FIG. 5 is a schematic view showing a conventional atomizing nozzle.

FIG. 6 is a relationship diagram of standard deviation of flake thickness and nozzle diameter / gas flow rate.

FIG. 7: PC of samples with different standard deviations of flake thickness
It is a T curve.

[Explanation of symbols]

1: Cylindrical roll 2: Atomizing nozzle 3: Molten metal nozzle 4: Molten metal storage container 11: Molten metal container heater 12: Molten metal nozzle heater 13: Molten water temperature thermocouple 14: Temperature control device

Claims (3)

[Claims] 1. A method for producing a flake-like powder material by rapidly cooling a molten metal or alloy, comprising the step of flowing the molten metal through a substantially circular molten metal nozzle arranged at the bottom of the molten metal container, A flat plate gas jet is jetted from the atomizing nozzles facing each other toward the molten metal flow that has flowed out of the molten metal nozzle, and the molten metal having a high density in the rotation axis direction of the cylindrical roll disposed on the outflow side of the molten metal nozzle. Flake shape characterized by including a droplet flow generation step of generating a droplet flow and a powder generation step of causing the generated droplet flow to collide with the surface of the cylindrical roll and rapidly cooling to obtain a flake powder material. Method of manufacturing powder material. 2. In the droplet flow generating step, a gas jet having a flat plate shape and a jetting gas flow rate per unit width thereof gradually decreasing from a central portion to a peripheral portion is jetted oppositely from the atomizing nozzle. Item 2. A method for producing a flaky powder material according to Item 1. 3. The molten metal container and the molten metal nozzle are provided with heating means, in the molten metal outflow process, the temperature of the molten metal in the molten metal container and the molten metal nozzle is controlled to a predetermined value, and in the molten droplet flow generation process. The flaky powder according to claim 1, wherein the gas jet is jetted so that the relationship between the inner diameter Dn of the molten metal nozzle in the direction in which the gas jets face each other and the jetting gas flow rate Qg satisfies the following equation (1). Material manufacturing method. Dn <20 ・ Qg ・ ・ ・ (1) Dn: Inner diameter of molten metal nozzle
(mm) Qg: Injection gas flow rate (Nm ³ / sec)