Metal powder processing apparatus, metal powder processing method

Abstract

The present invention provides a metal powder processing apparatus capable of suppressing the adhesion of fine particles to the particle surface of the processed powder after plasma processing, and a metal powder processing method using the same. [Solution] The plasma gun 12 ejects plasma P from a plasma nozzle 57, the plasma nozzle 57 is located in a depressurized chamber 11 in which the plasma P is generated, and the exhaust means 13 is located in the depressurized chamber 11 and has a suction opening 23 which reduces the pressure inside the depressurized chamber 11 to control the airflow inside the depressurized chamber 11 and sucks up fine particles floating inside the depressurized chamber 11. The plasma gun 12 has a plasma gas supply means 14 which supplies plasma gas and a metal powder supply means 15 which supplies metal powder Q1 with a carrier gas, and the metal powder Q1 is brought into contact with the plasma P to perform plasma treatment on the metal powder Q1 and generate treated powder Q2.

Description

Technical Field

[0001] The present invention relates to a metal powder processing apparatus for performing plasma processing on metal powder, and a metal powder processing method using the same.

Background Art

[0002] A metal 3D printer is known that melts metal powder by a laser or an electron beam and stacks it layer by layer to form a metal workpiece having an arbitrary three-dimensional shape. Such a metal 3D printer can manufacture metal parts with complex shapes that are difficult to mold with a mold or the like with high precision. As the metal powder that is a molding raw material used in such a metal 3D printer, metal powder mainly composed of spherical metal particles manufactured by a gas atomization method or the like is generally used.

[0003] As a method for manufacturing metal powder composed of spherical metal particles, a technique is widely known in which irregularly shaped metal powder is introduced into and passed through a thermal plasma, and the metal particles are spheroidized by surface tension. However, in the thermal plasma processing of metal powder using direct current plasma, high-frequency plasma, or the like, while the metal particles can be spheroidized and etched, fine particles that are by-products during the thermal plasma processing are generated. Since these fine particles have a smaller particle size than the metal particles, they float in the chamber of the plasma processing apparatus and adhere to the surface of the metal powder composed of the generated spherical metal particles.

[0004] It is considered that the fine particles generated during the thermal plasma processing adhere by overheating when the metal powder passes through the plasma and the high-temperature part directly below the plasma, and a part of it evaporates, and the evaporated metal gas re-condenses on the surface of the metal powder composed of the spherical metal particles after the plasma processing. Since these fine particles have high surface energy, they react with impurities such as oxygen and water in the chamber and are oxidized, and also increase the adhesion force between the particles. As a result, the fluidity, bulk density, purity, etc. of the particles decrease.

[0005] As a method for suppressing the generation of fine particles during plasma treatment of such metal powders, for example, Patent Document 1 discloses a method for producing metal powder consisting of low-oxygen spherical metal particles, in which a mixed gas of an inert gas with a purity of 99.9 vol% or higher and a hydrogen gas with a purity of 99.9 vol% or higher is used as the plasma gas, and DC thermal plasma treatment is performed with the hydrogen content of the mixed gas set to 0.5 to 20 vol%, thereby suppressing the adhesion of fine particles to the surface. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2004-062555 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, as described in Patent Document 1, simply using a mixed gas, which is a mixture of gases of specific components in a specific concentration ratio, as the plasma gas does not sufficiently suppress the adhesion of fine particles to the surface of metal powder particles after plasma treatment.

[0008] This invention has been made in view of the above background, and aims to provide a metal powder processing apparatus capable of suppressing the adhesion of fine particles to the particle surface of the processed powder after plasma processing, and a metal powder processing method using the same. [Means for solving the problem]

[0009] One embodiment of the metal powder processing apparatus comprises a plasma gun that ejects plasma from a plasma nozzle, a depressurization chamber in which the plasma nozzle is located and the plasma is generated, and an exhaust means in which a suction opening is located within the depressurization chamber to reduce the pressure inside the chamber and control the airflow inside the chamber, and to suck up fine particles floating inside the chamber. The plasma gun has a plasma gas supply means for supplying plasma gas and a metal powder supply means for supplying metal powder with a carrier gas. When performing the plasma processing, the internal pressure of the depressurization chamber is controlled to 15 kPa or less, and the metal powder is brought into contact with the plasma to perform plasma processing on the metal powder and produce processed powder.

[0010] Furthermore, one embodiment of the metal powder processing method is a metal powder processing method using the metal powder processing apparatus described above, comprising: a plasma processing step of introducing the metal powder into the plasma to produce the processed powder in which the metal powder particles are spherically formed; a fine particle suction step of sucking up the fine particles, which are by-products generated in the plasma processing step, using the exhaust means; and an airflow control step of reducing the pressure inside the depressurized chamber using the exhaust means to control the airflow inside the depressurized chamber. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a metal powder processing apparatus capable of suppressing the adhesion of fine particles to the particle surface of the processed powder after plasma processing, and a metal powder processing method using the same. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram showing a metal powder processing apparatus according to one embodiment of the present invention. [Figure 2] This is an enlarged cross-sectional view of the main part of the plasma gun. [Figure 3] This is a schematic diagram illustrating the positional relationship between the plasma nozzle of the plasma gun and the suction opening of the exhaust mechanism. [Figure 4] This is an SEM image showing the verification results. [Modes for carrying out the invention]

[0013] The following description of this embodiment will be made in detail with reference to the drawings as appropriate. The drawings used in the following description may be enlarged for convenience in order to clearly illustrate the features of the present invention, and the dimensional ratios of each component may differ from those in reality. The materials, dimensions, etc., exemplified in the following description are examples only, and the present invention is not limited to them; it can be modified as appropriate within the scope of achieving its effects.

[0014] (Metal powder processing equipment) Figure 1 is a schematic diagram showing a metal powder processing apparatus according to one embodiment of the present invention. The metal powder processing apparatus 10 of this embodiment includes a vacuum chamber 11, a plasma gun 12 positioned above the vacuum chamber 11, an exhaust means 13, a plasma gas supply means 14, a metal powder supply means 15, a DC current supply means 16, an observation means 17, and a powder recovery unit 18 for recovering the processed powder.

[0015] The pressure reducing chamber 11 is formed from a pressure-resistant vessel, and a grounding wire 21 is connected to one end of it. Furthermore, a suction opening 23 is provided on the upper circumferential surface of the decompression chamber 11, where the end of the exhaust pipe 22 constituting the exhaust means 13 opens inside the decompression chamber 11. In addition, a viewport 28 connected to the observation means 17 is provided on the circumferential surface of the decompression chamber 11. A vacuum gauge 29 for measuring the internal pressure is also connected to the decompression chamber 11.

[0016] The exhaust means 13 includes an exhaust pipe 22, a pressure reducing pump 24, a first filter 25, a second filter 26, and a flow rate control valve 27. One end of the exhaust pipe 22 opens into the pressure reducing chamber 11 as a suction opening 23.

[0017] The first filter 25 and the second filter 26 are filters that capture the fine particles generated in the reduced-pressure chamber 11 and sucked from the suction opening 23. The first filter 25 has a larger mesh size than the second filter 26, captures fine particles with a relatively large particle size with the first filter 25, and captures fine particles with a smaller particle size than this with the second filter 26.

[0018] The plasma gas supply means 14 includes a plasma gas source 31, a flow rate regulator 32, and a plasma gas pipe 33 having one end connected to the plasma gun 12. As the plasma gas supplied from the plasma gas source 31, for example, any one of rare gases such as He, Ne, Ar, and Xe, a mixed gas of two or more rare gases, or a mixed gas in which hydrogen, nitrogen, methane, etc. are mixed as additive gases other than rare gases in the rare gas or the mixed gas of two or more rare gases at a ratio of 4.0 volume% (vol%) or less is used. In this embodiment, a mixed gas composed of Ar + H2 (4 volume%) is used as the plasma gas.

[0019] The metal powder supply means 15 includes a carrier gas source 35, a flow rate regulator 36, a metal powder feeder 37, and a metal powder pipe 38 having one end connected to the plasma gun 12. The carrier gas supplied from the carrier gas source 35 is a powder transport medium that transports the metal powder supplied by the metal powder feeder 37 toward the plasma gun 12. Such a carrier gas may be, for example, any one of rare gases such as He, Ne, Ar, and Xe or a mixed gas of two or more rare gases. In this embodiment, Ar is used as the carrier gas.

[0020] The metal powder feeder 37 stores the metal powder composed of amorphous particles that are the objects to be processed, and conveys the metal powder Q1 by the carrier gas flow supplied from the carrier gas source 35. The metal powder may be amorphous particles of a metal other than Pt, Au, Ag, and Cu. In this embodiment, an Ni alloy powder is used as the metal powder Q1.

[0021] The DC current supply means 16 includes a DC power supply 41 and DC wiring 42 that supplies the DC current generated by the DC power supply 41 to the plasma gun 12. The DC power supply 41 can be a DC unipolar pulse power supply, a DC bipolar pulse power supply, or the like.

[0022] The observation means 17 includes a spectrometer 43, a probe head 44, and an optical fiber 45 connecting them. The probe head 44 receives the synchrotron radiation of plasma P emitted from the plasma gun 12 into the decompression chamber 11 via a viewport 28 provided in the decompression chamber 11. The spectrometer 43 spectrally analyzes the synchrotron radiation of plasma P and monitors the plasma P.

[0023] The powder recovery unit 18 includes a recovery container 46 for recovering treated powder Q2, which consists of spherical metal particles formed by plasma treatment of amorphous metal powder, and a cooler 47 for cooling the recovery container 46.

[0024] The recovery container 46 is configured to have a variable distance from the tail flame Pe along the injection direction L of the plasma P. Specifically, the recovery container 46 is positioned to be movable within the decompression chamber 11 along the injection direction L of the plasma P.

[0025] In the metal powder processing apparatus 10 of this embodiment, the metal powder Q1 is processed by heating with plasma P. Because the pressure in the reduced pressure chamber 11 is low, the cooling rate by convection is low, and the shape of the metal powder becomes unstable even when separated from the plasma P, which is the heat source. Therefore, the distance between the plasma P and the recovery container 46 needs to be long enough for the heated amorphous metal powder Q1 to cool sufficiently and for processed powder Q2 consisting of spherical metal particles to be formed. In this embodiment, the recovery container 46 is positioned in the reduced pressure chamber 11 such that the distance between the opening top surface of the recovery container 46 and the tail flame portion Pe of the plasma P is 80 cm or more.

[0026] Furthermore, the cooler 47 prevents the recovery container 46 from overheating due to the plasma P. The cooler 47 may be, for example, a water-cooled cooling device that circulates water on the outer surface of the recovery container 46.

[0027] Figure 2 is an enlarged cross-sectional view of the main part of the plasma gun. The plasma gun 12 comprises an anode 52, a cathode 53, a plasma gas channel 54 formed between the anode 52 and the cathode 53, and a metal powder channel 55 formed in the cathode 53 and which is a channel for metal powder Q1 transported by a carrier gas. The lower end face of the plasma nozzle 57 faces into the depressurized chamber 11.

[0028] Furthermore, the metal powder flow channels 55 shown in Figure 2 are arranged at equal or unequal intervals within the cathode 53 so as to surround the anode 52 which is arranged coaxially, and one or more flow channels may be connected to one or more outlets. In addition, the metal powder flow channels 55 may be annular in shape and may be arranged to allow introduction into the plasma outside the cathode.

[0029] The anode 52 and cathode 53 are connected to the DC wiring 42 of the DC current supply means 16. The plasma gas channel 54 is connected to the plasma gas piping 33 of the plasma gas supply means 14. The metal powder channel 55 is connected to the metal powder piping 38 of the metal powder supply means 15. In this embodiment, the end opening 55a of the metal powder channel 55 is an internal type, formed inward from the plasma injection port 57.

[0030] In this configuration, the plasma gun 12 generates an arc portion P1 that constitutes the plasma P by applying a DC plasma current between the anode 52 and cathode 53 to the plasma gas, and radiates it into the depressurized chamber 11 from the end opening 55a.

[0031] Furthermore, a halo portion P2 is formed around this arc portion P1. Then, when metal powder Q1 is supplied into the arc portion P1 of the plasma P from the end opening 55a of the metal powder flow channel 55, the particles of this metal powder Q1 melt and become spherical due to surface tension, and treated powder Q2 consisting of spherical metal particles is generated.

[0032] In this embodiment, the plasma gun 12 has the end opening 55a of the metal powder channel 55 formed inside the plasma nozzle 57. However, it is also possible to use an external plasma gun in which the end opening of the metal powder channel is formed outside the plasma nozzle to supply metal powder to the plasma ejected from the plasma nozzle.

[0033] Figure 3 is a schematic diagram illustrating the positional relationship between the plasma nozzle of the plasma gun and the suction opening of the exhaust mechanism. In this embodiment, the plasma gun 12 and the suction opening 23 are positioned within the decompression chamber 11 such that the angle θ between a first virtual line R1 extending from the center of the plasma nozzle 57 of the plasma gun 12 along the plasma P ejection direction L and a second virtual line R2 extending from the center of the plasma nozzle 57 toward the center of the suction opening 23 of the exhaust means 13 is in the range of 19° to 61°.

[0034] At the same time, the plasma gun 12 and the suction opening 23 are positioned within the decompression chamber 11 such that the distance D from the intersection point X of the first virtual line R1 and the third virtual line R3, which extends from the center of the suction opening 23 in a direction perpendicular to the first virtual line R1, is between 58 mm and 87 mm.

[0035] By arranging the plasma nozzle 57 and suction opening 23 of the plasma gun 12 in the positional relationship described above within the decompression chamber 11, fine particles can be efficiently sucked out from within the decompression chamber 11, preventing them from adhering to the surface of the processed powder Q2.

[0036] The fine particles generated during plasma treatment of metal powder Q1 are produced when the vapor of metal powder Q1, heated and vaporized in the center of the plasma P, cools and re-solidifies near the tail flame Pe of the plasma P. These fine particles have an average particle diameter of 0.1 μm or more and less than 10 μm, and because of their small mass, they tend to accumulate in the reduced pressure chamber 11, forming a fine particle atmosphere.

[0037] On the other hand, the processed powder Q2 produced has an average particle size of 10 μm to 300 μm, which is larger than fine particles. Therefore, due to the mass difference, the processed powder Q2 falls through the reduced pressure chamber 11 according to gravity. However, there is a concern that fine particles may adhere to the surface of the processed powder Q2 as it passes through the fine particle atmosphere described above.

[0038] Therefore, in the metal powder processing apparatus 10 of this embodiment, a suction opening 23 of the exhaust means 13 is provided near the plasma P generation area within the reduced pressure chamber 11, thereby generating an airflow around the plasma P toward the suction opening 23. With this configuration, fine particles generated during the processing of metal powder Q1 with plasma P are classified and aspirated from the reduced pressure chamber 11. As a result, processed powder Q2 consisting of spherical metal particles without any fine particle adhesion to the surface can be obtained.

[0039] In particular, by arranging the plasma nozzle 57 and suction opening 23 of the plasma gun 12 in the positional relationship described above, an airflow directed towards the suction opening 23 can be effectively formed around the plasma P, thereby enhancing the effect of suppressing the adhesion of fine particles to the surface of the treated powder Q2.

[0040] Furthermore, in the metal powder processing apparatus 10 of this embodiment, the characteristics of the airflow towards the suction opening 23 around the plasma P are also controlled by controlling the internal pressure in the reduced pressure chamber 11 to 15 kPa or less.

[0041] Generally, if the internal pressure in the decompression chamber 11 is high, the airflow becomes viscous, and fine particles and larger metal particles are easily affected by the airflow. However, by lowering the internal pressure in the decompression chamber 11 to a low pressure of 15 kPa or less, the airflow changes from viscous to molecular. In such a molecular flow, small particles are affected by the airflow, but larger metal powder particles are more susceptible to gravity and fall through the decompression chamber 11 according to gravity. In this way, by lowering the internal pressure in the decompression chamber 11 to 15 kPa or less, the fine particles and the processed powder Q2 can be separated more efficiently.

[0042] As a modification of this embodiment, in the embodiment shown in Figure 1, the metal powder processing apparatus 10 is installed such that the plasma nozzle 57 of the plasma gun 12 and the recovery container 46 are spaced apart vertically (vertical arrangement). However, the metal powder processing apparatus can also be installed such that the plasma nozzle 57 of the plasma gun 12 and the recovery container 46 are spaced apart horizontally, for example (horizontal arrangement).

[0043] Furthermore, in the embodiment shown in Figure 1, the recovery container 46 is positioned so that its center coincides with the extension of the first imaginary line R1 extending from the plasma nozzle 57 of the plasma gun 12. However, the center of the recovery container 46 does not necessarily have to coincide with the extension of the first imaginary line R1. For example, the recovery container 46 can be positioned at any location that is off the extension of the first imaginary line R1 extending from the plasma nozzle 57 of the plasma gun 12.

[0044] The effects of the metal powder processing apparatus configured as described above, and a metal powder processing method using the metal powder processing apparatus of this embodiment will be explained. When using the metal powder processing apparatus 10 of the above-described embodiment to convert amorphous metal powder Q1 into spherical processed powder Q2 by plasma treatment, plasma gas is supplied from the plasma gas source 31 of the plasma gas supply means 14 to the plasma gun 12 via the plasma gas piping 33. The plasma gas may be, for example, a mixed gas consisting of Ar + H2 (4 volume% (vol%)).

[0045] Furthermore, a DC plasma current is applied from the DC current supply means 16 to the anode 52 and cathode 53 of the plasma gun 12 via the DC wiring 42. The plasma gas supplied from the plasma gas channel 54 of the plasma gun 12 forms plasma P, which is ejected from the plasma nozzle 57 into the depressurized chamber 11 by the application of this DC plasma current.

[0046] Furthermore, a carrier gas is supplied from the carrier gas source 35 of the metal powder supply means, and after the metal powder Q1 is drawn up by the metal powder feeder 37, this metal powder Q1 is supplied to the plasma gun 12 via the metal powder piping 38. The carrier gas can be, for example, Ar or He, and the metal powder Q1 can be Ni alloy powder.

[0047] The metal powder Q1 supplied from the metal powder channel 55 of the plasma gun 12 is introduced into the arc portion P1 of the plasma P through the end opening 55a of the metal powder channel 55. As a result, the irregularly shaped particles of metal powder Q1 are melted by the plasma P, and when the metal droplets are cooled and re-solidified near the tail flame portion Pe of the plasma P, they become spherical due to surface tension, and treated powder Q2 consisting of spherical metal particles is generated (plasma treatment step S1).

[0048] Simultaneously with the plasma treatment process S1, the decompression pump 24 of the exhaust means 13 is operated to suck up the fine particles generated in the decompression chamber 11 through the exhaust pipe 22 via the suction opening 23 (fine particle suction process S2).

[0049] During plasma treatment of metal powder Q1, when the vapor of metal powder Q1 heated and vaporized in the center of the plasma P is cooled and re-solidified near the tail flame Pe of the plasma P, fine particles smaller in size than the generated treated powder Q2 are produced. By sucking and removing these fine particles generated in the reduced pressure chamber 11 through the suction opening 23, it is possible to prevent the fine particles from adhering to the surface of the treated powder Q2, which consists of spherical metal particles, and to obtain treated powder Q2 consisting of spherical metal particles without any adhering fine particles.

[0050] The fine particles sucked in from the suction opening 23 by the decompression pump 24 are captured by a first filter 25 formed upstream of the decompression pump 24, with relatively larger particles being captured first, and then by a second filter 26 downstream, with smaller particles being captured.

[0051] Furthermore, in the particulate suction process S2, the internal pressure in the decompression chamber 11 is controlled to, for example, 15 kPa or less, and the suction opening 23 of the exhaust means 13 is provided near the plasma P generation area in the decompression chamber 11, thereby controlling the airflow in the decompression chamber to generate an airflow around the plasma P toward the suction opening 23 (airflow control process S3).

[0052] This airflow control process S3 generates an airflow that allows the fine particles generated in the reduced pressure chamber 11 to flow towards the suction opening 23 without re-adhering to the surface of the treated powder Q2, thereby producing treated powder Q2 consisting of spherical metal particles without any adhering fine particles.

[0053] In this way, the processed powder Q2, which consists of spherical metal particles generated in the vacuum chamber 11, is placed at the bottom of the vacuum chamber 11 and falls into a recovery container 46 that is cooled by a cooler 47 for collection.

[0054] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Examples]

[0055] The effects of the metal powder processing apparatus and metal powder processing method of the present invention were verified. For verification, the metal powder processing apparatus 10 of the embodiment described above was used. As the metal powder, Ni-based superalloy powder with a particle size range of 15 μm to 45 μm was used, and DC thermal plasma treatment was performed.

[0056] Table 1 summarizes the processing conditions for Examples 1 and 2 and Comparative Examples 1 to 7, as well as whether or not fine particles were attached to the treated powder consisting of spherical metal particles. Comparative Example 7 is an example in which plasma treatment was not performed. Furthermore, SEM images of the treated powder particles from Example 2, Comparative Example 2, and Comparative Example 7 are shown in Figure 4.

[0057] [Table 1]

[0058] According to the verification results shown in Table 1 and Figure 4, in Examples 1 and 2, where the internal pressure of the vacuum chamber was 15 kPa or less, spherical particles without any fine particle adhesion to the surface were obtained. However, in Comparative Examples 1 to 6, where the internal pressure of the vacuum chamber was set to a high pressure exceeding 15 kPa, and in Comparative Example 7, where plasma treatment was not performed, fine particle adhesion was observed on the particle surface. Therefore, the effectiveness of this embodiment has been confirmed.

[0059] The key points that can be understood from the above disclosures are as follows: [Configuration 1] A plasma gun that ejects plasma from a plasma nozzle, A depressurized chamber is provided, in which the plasma injection port is located and the plasma is generated inside, The vacuum chamber is provided with a suction opening, and the vacuum chamber is depressurized to control the airflow within the vacuum chamber, and an exhaust means is provided to suck in airborne particles within the vacuum chamber. The plasma gun comprises a plasma gas supply means for supplying plasma gas and a metal powder supply means for supplying metal powder using a carrier gas. When performing plasma processing, the internal pressure of the depressurized chamber is controlled to 15 kPa or less. A metal powder processing apparatus that brings the metal powder into contact with the plasma to perform the plasma treatment on the metal powder and produce a processed powder. [Configuration 2] The metal powder processing apparatus according to configuration 1, wherein the angle between a first imaginary line extending from the center of the plasma nozzle along the plasma ejection direction and a second imaginary line extending from the center of the plasma nozzle toward the center of the suction opening is in the range of 19° to 61°, and the distance from the first imaginary line to the intersection point of a third imaginary line extending from the center of the suction opening in a direction perpendicular to the first imaginary line is 58 mm to 87 mm. [Configuration 3] A metal powder processing apparatus according to configuration 1 or 2, wherein a powder recovery unit for recovering the processed powder is provided at the lower part of the depressurized chamber along the direction of plasma injection, and the distance between the tail flame of the plasma and the powder recovery unit is configured to be variable. [Structure 4] The metal powder processing apparatus according to any one of configurations 1 to 3, wherein the fine particles are generated when the metal powder is subjected to the plasma treatment, and have an average particle diameter of 0.1 μm or more and less than 10 μm. [Composition 5] The processed powder has an average particle size of 10 μm or more and 300 μm or less, as described in any one of configurations 1 to 4 of the metal powder processing apparatus. [Composition 6] A metal powder processing apparatus according to any one of configurations 1 to 5, wherein a filter for capturing the fine particles is formed downstream of the suction opening. [Composition 7] The metal powder processing apparatus according to any one of configurations 1 to 6, wherein the metal powder is an alloy powder containing Ni. [Structure 8] The metal powder processing apparatus according to any one of configurations 1 to 7, wherein the plasma gas is a noble gas containing one or more of He, Ne, Ar, and Xe, or a mixed gas obtained by mixing the noble gas with an additive gas other than the noble gas in a proportion of 4.0% by volume or less. [Composition 9] A method for processing metal powder using a metal powder processing apparatus described in any one of configurations 1 to 8, A plasma treatment step of introducing the metal powder into the plasma to produce the treated powder in which the metal powder particles are spherically formed, A particulate suction step in which the particulates, which are by-products generated in the plasma processing step, are sucked up by the exhaust means, A metal powder processing method comprising: an airflow control step of reducing the pressure inside the depressurized chamber by the exhaust means and controlling the airflow inside the depressurized chamber. [Explanation of Symbols]

[0060] 10…Metal powder processing equipment 11…Decompression Chamber 12…Plasma gun 13... Exhaust means 14…Means of supplying plasma gas 15...Metal powder supply means 16…DC current supply means 18...Powder recovery section 23...Suction opening 52...Anode 53...Cathode 54…Plasma gas flow path 55…Metal powder channel Q1…Metal powder Q2…Processed powder

Claims

1. A plasma gun that ejects plasma from a plasma nozzle, A depressurized chamber is provided, in which the plasma injection port is located and the plasma is generated inside, The vacuum chamber is provided with a suction opening, and the vacuum chamber is depressurized to control the airflow within the vacuum chamber, and an exhaust means is provided to suck in airborne particles within the vacuum chamber. The plasma gun comprises a plasma gas supply means for supplying plasma gas and a metal powder supply means for supplying metal powder using a carrier gas. When performing plasma processing, the internal pressure of the depressurized chamber is controlled to 15 kPa or less. A metal powder processing apparatus that brings the metal powder into contact with the plasma to perform the plasma treatment on the metal powder and produce a processed powder.

2. The metal powder processing apparatus according to claim 1, wherein the angle between a first imaginary line extending from the center of the plasma nozzle along the plasma ejection direction and a second imaginary line extending from the center of the plasma nozzle toward the center of the suction opening is in the range of 19° to 61°, and the distance from the first imaginary line to the intersection point of a third imaginary line extending from the center of the suction opening in a direction perpendicular to the first imaginary line is 58 mm to 87 mm.

3. A metal powder processing apparatus according to claim 1 or 2, wherein a powder recovery unit for recovering the processed powder is provided at the lower part of the depressurized chamber along the direction of plasma injection, and the distance between the tail flame of the plasma and the powder recovery unit is configured to be variable.

4. The metal powder processing apparatus according to claim 1 or 2, wherein the fine particles are generated when the metal powder is subjected to the plasma treatment, and have an average particle diameter of 0.1 μm or more and less than 10 μm.

5. The metal powder processing apparatus according to claim 1 or 2, wherein the processed powder has an average particle size of 10 μm or more and 300 μm or less.

6. The metal powder processing apparatus according to claim 1 or 2, wherein a filter for capturing the fine particles is formed downstream of the suction opening.

7. The metal powder processing apparatus according to claim 1 or 2, wherein the metal powder is an alloy powder containing Ni.

8. The metal powder processing apparatus according to claim 1 or 2, wherein the plasma gas is a noble gas containing one or more of He, Ne, Ar, and Xe, or a mixed gas obtained by mixing the noble gas with an additive gas other than the noble gas in a proportion of 4.0% by volume or less.

9. A method for processing metal powder using the metal powder processing apparatus described in claim 1 or 2, A plasma treatment step of introducing the metal powder into the plasma to produce the treated powder in which the metal powder particles are spherically formed, A particulate suction step in which the particulates, which are by-products generated in the plasma processing step, are sucked up by the exhaust means, A metal powder processing method comprising: an airflow control step of reducing the pressure inside the depressurized chamber by the exhaust means and controlling the airflow inside the depressurized chamber.

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