Nano metal powder classification device and nano metal powder classification method

Abstract

This invention relates to the field of nano-metal powder production technology, specifically disclosing a nano-metal powder classification device and a nano-metal powder classification method. The nano-metal powder classification device includes a classification wheel, a feed inlet, an electron emission assembly, and a carrier gas inlet. The carrier gas inlet is located on one side of the classification wheel. One end of the classification wheel is equipped with a drive assembly for driving the classification wheel to rotate. The other end of the classification wheel has a fine powder outlet. An electrode is located inside the classification wheel, positioned along its axis, forming an electrostatic field between the electrode and the classification wheel. The nano-metal powder classification method includes the following steps: P1, starting the classification wheel via a drive device, introducing gas through the carrier gas inlet, connecting the classification wheel and the electrode to a power source, and starting the electron emission assembly; P2, adding the nano-metal powder to be classified, and adjusting the rotational speed of the classification wheel and the voltage between the classification wheel and the electrode according to the target particle size. This invention improves the classification efficiency of nano-metal powders.

Description

Technical Field

[0001] This invention relates to the field of nano-metal powder production technology, and in particular to a nano-metal powder classification device and a nano-metal powder classification method. Background Technology

[0002] Nanoscale metal powders are widely used in fields such as electronic components, coatings, and plating to improve the surface properties of workpieces and achieve high-precision manufacturing. Typically, nanoscale metal powders are required to have a small average particle size, a narrow particle size distribution, and good spherical shape.

[0003] Common nanoscale metal powder manufacturing technologies include evaporation and condensation, electro-explosion, and radio frequency plasma vaporization, which produce metal powders with a wide particle size distribution, generally ranging from 0.01 to 2 μm. Therefore, to meet the high-precision industrial requirements, it is necessary to classify the metal powders according to their particle size in the post-processing stage.

[0004] To simplify processes and reduce wastewater treatment, dry classification methods are commonly used for nano-metal powders. In related technologies, a high-speed rotating classifying wheel is used to classify the powder. A circumferential flow field is formed around the high-speed rotating classifying wheel. Small-diameter nanoparticles are drawn through the circumferential flow field by the radial airflow and enter the center of the classifying wheel, where they are collected and used as the final product. Large-diameter nanoparticles undergo centrifugal motion under the influence of the circumferential airflow and are discarded or recycled. However, because nano-sized powders readily follow the airflow, the classification efficiency is affected, resulting in a lower median particle size after classification. d 50 Its size is approximately 0.9μm, which is insufficient to meet the high-precision industrial requirements. Summary of the Invention

[0005] To improve the classification efficiency of nano-metal powders, this invention provides a nano-metal powder classification device and a nano-metal powder classification method.

[0006] In a first aspect, the present invention provides a nano-metal powder classification device, which adopts the following technical solution:

[0007] A nano-metal powder classification device includes a classification wheel, a feed inlet, an electron emission component, and a carrier gas inlet. The carrier gas inlet is located on one side of the classification wheel. One end of the classification wheel is provided with a drive component for driving the classification wheel to rotate. The other end of the classification wheel is provided with a fine powder outlet. An electrode is provided inside the classification wheel and is located at the axis of the classification wheel. An electrostatic field is formed between the electrode and the classification wheel.

[0008] By adopting the above technical solution, the electron emission component applies an electric charge to the powder, and the gas introduced through the carrier gas inlet blows the nano-metal powder toward the classifying wheel. The classifying wheel rotates under the action of the drive component, causing the surrounding gas to rotate at high speed. When the powder approaches the classifying wheel, it moves around the periphery of the classifying wheel with the airflow on the one hand, and has a tendency to move toward the axis of the classifying wheel under the action of the airflow pressure difference on the other hand. The larger nano-metal powder particles are subjected to a large centrifugal force and are separated from the airflow during the circular motion, while the smaller powder particles follow the airflow into the interior of the classifying wheel and are finally discharged from the fine powder outlet.

[0009] When the electrodes and classifying wheel are connected to a power source, the particle size of the nano-metal powder can be further controlled by changing the polarity of the classifying wheel and the electrodes, as well as the magnitude of the voltage. When the classifying wheel is connected to the positive electrode and the electrode is connected to the negative electrode, the nano-metal powder is repelled by the electrode, and the direction of the electrostatic force is away from the axis of the classifying wheel. This prevents some powder particles that could originally enter the classifying wheel by airflow from passing through the classifying wheel, thus reducing the particle size of the classified nano-metal powder. Conversely, when the classifying wheel is connected to the negative electrode and the electrode is connected to the positive electrode, the electrostatic force is in the same direction as the airflow, the particle size of the classified powder increases, but the yield of nano-metal powder increases.

[0010] By controlling the combined force of aerodynamics and electrostatics, and according to the particle size requirements during production, it is possible not only to obtain smaller nano-metal powder particles, but also to increase the yield of coarse powder, and to achieve more precise and convenient classification of powder particles, thus effectively improving the classification efficiency of nano-metal powder.

[0011] Optionally, the electrostatic field voltage between the grading wheel and the electrode is 100-2000V.

[0012] By adopting the above technical solution, when the classifying wheel is connected to the positive terminal of the power supply and the electrode is connected to the negative terminal, reducing the electrostatic field voltage will weaken the electrostatic force on the nano-metal powder facing away from the axis of the classifying wheel, thereby increasing the particle size of the classified powder, but increasing the yield of nano-metal powder. By adjusting the electric field voltage, the particle size of the powder can be classified more accurately and conveniently.

[0013] Optionally, the rotational speed of the grading wheel is 10,000-22,000 rpm.

[0014] By adopting the above technical solution, reducing the rotation speed of the classifying wheel will weaken the centrifugal force on the nano-metal powder opposite to the axis of the classifying wheel, thereby increasing the particle size of the classified powder, but increasing the yield of nano-metal powder. By adjusting the rotation speed of the classifying wheel, the particle size of the powder can be classified more accurately and conveniently.

[0015] Optionally, the gas pressure introduced through the carrier gas inlet is 0.2-1.0 MPa.

[0016] Optionally, the gas flow direction of the carrier gas inlet is directed towards the stager wheel.

[0017] By adopting the above technical solution, the gas introduced through the carrier gas inlet not only blows the nano-metal powder that needs to be classified toward the classifying wheel, but also breaks up the agglomerated nano-metal powder. Increasing the gas pressure introduced through the carrier gas inlet can increase the yield of nano-metal powder while maintaining the particle size of the product.

[0018] Optionally, the grading wheels are provided in two or more, all of which are arranged in a circle and whose axes intersect.

[0019] By adopting the above technical solution, when multiple classifying wheels work simultaneously, the output can be increased without affecting the particle size.

[0020] Secondly, the present invention provides a method for classifying nano-metal powders, comprising the following steps:

[0021] P1. Start the classifier wheel through the drive component, introduce gas through the carrier gas inlet, turn on the power between the classifier wheel and the electrode, and start the electron emission component.

[0022] P2. Add the nano-metal powder to be classified, and adjust the speed of the classifying wheel and the voltage between the classifying wheel and the electrode according to the target particle size.

[0023] Optionally, in P1, the pressure of the gas introduced into the carrier gas inlet is kept constant by a circulating fan.

[0024] In summary, the present invention has at least one of the following beneficial technical effects:

[0025] By controlling the combined force of aerodynamics and electrostatics, and according to the particle size requirements during production, it is possible not only to obtain smaller nano-metal powder particles, but also to increase the yield of coarse powder, and to achieve more accurate and convenient classification of powder particles, thus effectively improving the classification efficiency of nano-metal powder.

[0026] By adjusting the electrostatic field voltage and the speed of the classifier wheel, the particle size and yield of the nano-metal powder products can be changed, enabling more precise and convenient classification of powder particles.

[0027] The gas introduced through the carrier gas inlet not only blows the nano-metal powders that need to be classified toward the classifying wheel, but also breaks up the agglomerated nano-metal powders. Increasing the gas pressure introduced through the carrier gas inlet can increase the yield of nano-metal powders while maintaining the particle size of the product.

[0028] When multiple classifiers work simultaneously, production can be increased without affecting particle size. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of a nano-metal powder classification device in Embodiment 1 of the present invention.

[0030] Figure 2 yes Figure 1 Enlarged view of point A in the middle.

[0031] Figure 3 This is a schematic diagram of the structure of the grading wheel, electrode and air guide tube in Embodiment 2 of the present invention.

[0032] Figure 4 This is a schematic diagram of the installation of the grading wheel in Embodiment 3 of the present invention.

[0033] Figure 5 This is an 8000x SEM image of the nano-metal powder before grading in Application Example 1 of this invention.

[0034] Figure 6 This is an 8000x SEM image of the graded nano-metal powder from Application Example 1 of this invention.

[0035] Explanation of reference numerals in the attached diagram: 1. Charge chamber; 2. Gas inlet; 3. Connection outlet; 4. Feed inlet; 5. Feed pipe; 6. High-voltage electron gun; 7. Classification chamber; 8. Connection inlet; 9. Coarse powder outlet; 10. Carrier gas inlet; 11. Carrier gas pipe; 12. Fine powder outlet; 13. Air guide tube; 14. Classifying wheel; 15. Mounting shaft; 16. Motor; 17. Electrode. Detailed Implementation

[0036] The following is in conjunction with the appendix Figure 1-6 The present invention will be described in further detail below.

[0037] This invention discloses a nano-metal powder classification device.

[0038] Example 1

[0039] Reference Figure 1 A nano-metal powder classification device includes a charging chamber 1, with a gas inlet 2 on one side of the charging chamber 1, the axis of which coincides with the horizontal axis of the charging chamber 1. A connecting outlet 3 is located on the side of the charging chamber 1 away from the gas inlet 2, the axis of which also coincides with the horizontal axis of the charging chamber 1. A feed inlet 4 is located on one side of the gas inlet 2, and a feed pipe 5 is inserted into the feed inlet 4. The end of the feed pipe 5 located inside the charging chamber 1 is inclined away from the gas inlet 2, and the outer wall of the feed pipe 5 is sealed to the side wall of the charging chamber 1.

[0040] A plurality of electron emission components are arranged around the periphery of the charging chamber 1. In this embodiment, the electron emission components are high-voltage electron guns 6, which are mounted on the outer wall of the charging chamber 1 via ball mounts. The emitting end of the high-voltage electron gun 6 penetrates the side wall of the charging chamber 1 and extends into the charging chamber 1, facing away from the gas inlet 2. The plurality of high-voltage electron guns 6 are evenly arranged around the circumference of the charging chamber 1, and the vector sum of the plurality of high-voltage electron guns 6 coincides with the horizontal axis of the charging chamber 1. In this embodiment, there are two high-voltage electron guns 6, which are symmetrically arranged along the horizontal axis of the charging chamber 1.

[0041] A grading chamber 7 is provided on one side of the charging chamber 1, and a connection inlet 8 is provided on one side of the grading chamber 7. The connection outlet 3 communicates with the connection inlet 8, so that the interior of the charging chamber 1 is connected to the interior of the grading chamber 7. The inner diameter of the connection outlet 3 is equal to the inner diameter of the connection inlet 8, and the axis of the connection outlet 3 coincides with the axis of the connection inlet 8. The charging chamber 1 and the grading chamber 7 are detachably connected. In this embodiment, the charging chamber 1 and the grading chamber 7 are connected by a flange. In other embodiments, they can also be connected by threads, snap-fits, or other methods.

[0042] A coarse powder outlet 9 is provided at the bottom of the classification chamber 7, and the axis of the coarse powder outlet 9 coincides with the vertical axis of the classification chamber 7. A plurality of carrier gas inlets 10 are evenly arranged around the bottom periphery of the classification chamber 7, and the axes of the carrier gas inlets 10 intersect the vertical axis of the classification chamber 7. In this embodiment, there are two carrier gas inlets 10, which are symmetrically arranged along the vertical axis of the classification chamber 7. A carrier gas pipe 11 is inserted into each carrier gas inlet 10, with one end of the carrier gas pipe 11 inside the classification chamber 7 inclined away from the coarse powder outlet 9, and the outer wall of the carrier gas pipe 11 is sealed to the side wall of the classification chamber 7.

[0043] Reference Figure 1 and Figure 2 A fine powder outlet 12 is provided on one side of the classification chamber 7, located above the connecting inlet 8, with its axis parallel to the axis of the connecting inlet 8. An air guide duct 13 is inserted into the fine powder outlet 12, horizontally positioned, and its outer wall is sealed to the side wall of the classification chamber 7. A classifying wheel 14 is rotatably connected to the end of the air guide duct 13 furthest from the fine powder inlet, with the axis of the air guide duct 13 coinciding with the axis of the classifying wheel 14, and the air guide duct 13 passing through one end of the classifying wheel 14.

[0044] A mounting shaft 15 is coaxially connected to the end of the classifying wheel 14 furthest from the air guide duct 13. One end of the mounting shaft 15 is fixedly connected to the classifying wheel 14, and the other end of the mounting shaft 15 passes through the classifying chamber 7 and extends outside the classifying chamber 7. The outer wall of the mounting shaft 15 is sealed to the side wall of the classifying chamber 7. A drive assembly is provided on one side of the classifying chamber 7. In this embodiment, the drive assembly is a motor 16, and the drive shaft of the motor 16 is coaxially connected to the mounting shaft 15.

[0045] Reference Figure 2 An electrode 17 is provided inside the classifying wheel 14, and the axis of the electrode 17 coincides with the axis of the classifying wheel 14. In this embodiment, the electrode 17 is sleeved on the air guide duct 13, and the electrode 17 is fixedly connected to the air guide duct 13. In other embodiments, the electrode 17 may also be the air guide duct 13 itself. The connection between the classifying wheel 14 and the air guide duct 13 is insulated, and the connection between the classifying wheel 14 and the electrode 17 is insulated. The classifying wheel 14 is connected to one pole of the power supply, and the electrode 17 is connected to the other pole of the power supply. In this embodiment, the classifying wheel 14 is connected to the positive pole of the power supply, and the electrode 17 is connected to the negative pole of the power supply.

[0046] The implementation principle of a nano-metal powder classification device according to an embodiment of the present invention is as follows: the nano-metal powder to be classified enters the charging chamber 1 through the feed inlet 4, and the gas entering the charging chamber 1 through the gas inlet 2 blows the nano-metal powder toward the connecting outlet 3. During the movement of the nano-metal powder with the airflow, a negative charge is applied under the action of the high-voltage electron gun 6.

[0047] After entering the classification chamber 7, the nano-metal powder falls. Gas entering the chamber 7 through the carrier gas inlet 10 collides with the powder, dispersing it and simultaneously blowing it towards the classification wheel 14. Driven by the motor 16, the classification wheel 14 rotates at high speed. As the powder approaches the wheel, it is simultaneously subjected to aerodynamic and electrostatic forces. Larger nano-metal powder particles experience greater centrifugal force, detaching from the airflow and falling during their circular motion. Powder particles that are dispersed by the gas rise again, while even larger particles or those that cannot be dispersed exit from the coarse powder outlet 9 at the bottom of the classification chamber 7. Smaller powder particles follow the airflow into the classification wheel 14, where they are repelled by the electrode 17. The electrostatic force they experience is directed away from the axis of the classification wheel 14, preventing some powder particles that would otherwise have entered the wheel 14 by airflow from passing through, thus reducing the particle size of the classified nano-metal powder. Finally, the screened nano-metal powder exits the classification chamber 7 along with the gas from the fine powder outlet 12.

[0048] Example 2

[0049] The difference between Example 2 and Example 1 is that the positions of electrode 17 and air duct 13 are different.

[0050] Reference Figure 3 One end of the air guide duct 13 is flush with the side wall of the classifier wheel 14. The electrode 17 is cylindrical, and the end of the electrode 17 away from the air guide duct 13 is fixedly connected to the classifier wheel 14. The connection between the electrode 17 and the classifier wheel 14 is insulated.

[0051] Example 3

[0052] The difference between Example 3 and Example 1 is that the number of grading wheels 14 is different.

[0053] Reference Figure 4 There are several classifying wheels 14, which are evenly arranged around the vertical axis of the classifying chamber 7, and the axes of the several classifying wheels 14 intersect at the vertical axis of the classifying chamber 7. In this embodiment, there are three classifying wheels 14, and the air guide ducts 13 of the three classifying wheels 14 are interconnected, with one air guide duct 13 penetrating through the side wall of the classifying chamber 7. In other embodiments, the several classifying wheels 14 can also be installed on different horizontal planes.

[0054] Application Example 1

[0055] A method for classifying nano-metal powders, implemented in a nano-metal powder classification device according to Example 1 above, includes the following steps:

[0056] S1. Argon gas is introduced into the charging chamber 1 and the classification chamber 7 through gas inlet 2 and carrier gas inlet 10 to replace the air in the system.

[0057] S2. Start motor 16 to drive grader wheel 14 and adjust the speed of grader wheel 14 to the maximum speed of 22000rpm;

[0058] S3. Adjust the pressure of argon gas introduced into the carrier gas inlet 10 to 0.6MPa, and use a circulating fan to keep the gas pressure and flow rate constant;

[0059] S4. Connect the power supply between the classifier wheel 14 and the electrode 17 to start the high-voltage electron gun 6;

[0060] S5. Add nano-metal powder to feed pipe 5, as per [reference]. Figure 5 In this application example, the nano-metal powder has a median particle size. d 50 1.90μm, maximum particle size d max Using 3.70μm silver powder, the rotation speed of the classifying wheel 14 is maintained at 22000rpm, and the voltage between the classifying wheel 14 and the electrode 17 is adjusted to 200V until the predetermined output is achieved.

[0061] Reference Figure 6 The median particle size of the nano-metal powder obtained in Example 1 was determined by laser particle size analyzer. d 50 The maximum particle size is 0.20 μm. d max The particle size is 0.55 μm, and the yield is 2 kg / h.

[0062] Application Example 2

[0063] The difference between Application Example 2 and Application Example 1 is that in Application Example 2, the grader wheel 14 is connected to the negative terminal of the power supply, and the electrode 17 is connected to the positive terminal of the power supply.

[0064] Upon testing, the median particle size of the nano-metal powder obtained in Example 2 was determined. d 50 The maximum particle size is 0.64 μm. d max The particle size was 0.81 μm, and the yield was 9 kg / h.

[0065] As can be seen from Application Examples 1-2, when the classifying wheel 14 is connected to the positive terminal of the power supply and the electrode 17 is connected to the negative terminal, the nano-metal powder is repelled by the electrode 17, and the direction of the electrostatic force is away from the axis of the classifying wheel 14. This prevents some powder that could originally enter the classifying wheel 14 by airflow from passing through it, significantly reducing the particle size of the classified nano-metal powder. However, when the classifying wheel 14 is connected to the negative terminal of the power supply and the electrode 17 is connected to the positive terminal, the electrostatic force is in the same direction as the airflow, and the particle size of the classified powder is significantly increased. The advantage is a substantial increase in the yield of classified nano-metal powder.

[0066] Application Example 3

[0067] The difference between Application Example 3 and Application Example 1 is that in Application Example 3, the voltage between the grading wheel 14 and the electrode 17 is 100V.

[0068] Upon testing, the median particle size of the nano-metal powder obtained in Example 3 was determined. d 50 The maximum particle size is 0.28 μm. d max The particle size was 0.64 μm, and the yield was 3.5 kg / h.

[0069] Application Example 4

[0070] The difference between Application Example 4 and Application Example 1 is that in Application Example 4, the voltage between the grading wheel 14 and the electrode 17 is 2000V.

[0071] Upon testing, the median particle size of the nano-metal powder obtained in Example 4 was determined. d 50 The maximum particle size is 0.08 μm. d max The particle size is 0.15 μm, and the yield is 0.2 kg / h.

[0072] Application Example 5

[0073] The difference between Application Example 5 and Application Example 1 is that in Application Example 5, the rotational speed of the grading wheel 14 in step S5 is 15000 rpm.

[0074] Upon testing, the median particle size of the nano-metal powder obtained in Example 5 was determined. d 50 The maximum particle size is 0.52 μm. d max The thickness is 0.68 μm, and the yield is 7 kg / h.

[0075] Application Example 6

[0076] The difference between Application Example 6 and Application Example 1 is that in Application Example 6, the rotational speed of the grading wheel 14 in step S5 is 10,000 rpm.

[0077] Upon testing, the median particle size of the nano-metal powder obtained in Example 6 was determined. d 50 The maximum particle size is 0.72 μm. d max The particle size was 0.81 μm, and the yield was 7.4 kg / h.

[0078] As can be seen from Application Example 1 and Application Examples 3-6, reducing the power supply voltage and the rotation speed of the classifier wheel 14 will weaken the force on the nano-metal powder opposite to the axis of the classifier wheel 14, thereby increasing the particle size of the classified powder, but increasing the yield of nano-metal powder.

[0079] Application Example 7

[0080] The difference between Application Example 7 and Application Example 1 is that in Application Example 7, the gas pressure at the carrier gas inlet 10 in step S3 is 0.4 MPa.

[0081] Upon testing, the median particle size of the nano-metal powder obtained in Example 7 was determined. d 50 The maximum particle size is 0.22 μm. d max The particle size was 0.54 μm, and the yield was 1.2 kg / h.

[0082] Application Example 8

[0083] The difference between Application Example 8 and Application Example 1 is that in Application Example 8, the gas pressure at the carrier gas inlet 10 in step S3 is 0.2 MPa.

[0084] Upon testing, the median particle size of the nano-metal powder obtained in Example 8 was determined. d 50 The maximum particle size is 0.21 μm. d max The particle size was 0.54 μm, and the yield was 0.8 kg / h.

[0085] As can be seen from Application Example 1 and Application Examples 7-8, when the gas pressure introduced into the carrier gas inlet 10 decreases, the gas's effect on breaking up agglomerated nano-metal powder decreases, making it difficult for the agglomerated powder to pass through the classifier wheel 14, thus affecting the yield of nano-metal powder.

[0086] Application Example 9

[0087] The difference between Application Example 9 and Application Example 1 is that Application Example 9 is implemented in a nano-metal powder classification device of Example 3 above.

[0088] Upon testing, the median particle size of the nano-metal powder obtained using Example 9 was determined. d 50 The maximum particle size is 0.21 μm. d max The particle size was 0.55 μm, and the yield was 6.3 kg / h.

[0089] As can be seen from Application Examples 1 and 9, configuring multiple classifiers 14 can significantly increase the yield of nano-metal powder without affecting the particle size of the powder after classification.

[0090] Comparative Application Example 1

[0091] The difference between Comparative Application Example 1 and Application Example 1 is that in Comparative Application Example 1, there is no power supply between the grading wheel 14 and the electrode 17.

[0092] Upon testing, the median particle size of the nano-metal powder obtained in Application Example 1 was compared. d 50 The maximum particle size is 0.43 μm. d max The thickness is 0.78 μm, and the yield is 5 kg / h.

[0093] Combining application examples 1-2 and comparative application example 1, it can be seen that by introducing an electric field, the classification of nano-metal powders is controlled by the synergistic control of the electric field and aerodynamic forces. Depending on the target particle size, it is possible to obtain nano-metal powders with smaller particle sizes, and when producing nano-metal powders with larger particle sizes, it is also possible to significantly increase the powder yield, narrow the particle size distribution range, and improve the classification efficiency of nano-metal powders.

[0094] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A nano-metal powder classification device, comprising a classification chamber (7), characterized in that: The invention also comprises a feed port (4) and an electron emission component. A classifying wheel (14) is provided in the classifying chamber (7). A driving component is provided at one end of the classifying wheel (14). The driving component is used to drive the classifying wheel (14) to rotate. An electrode (17) is provided in the classifying wheel (14). The electrode (17) is located at the axis of the classifying wheel (14). An electrostatic field is formed between the electrode (17) and the classifying wheel (14). The axis of the classifying wheel (14) is arranged horizontally. A carrier gas inlet (10) and a fine powder outlet (12) are provided in the classifying chamber (7). The carrier gas inlet (10) is located below the classifying wheel (14). The gas flow direction of the gas introduced into the carrier gas inlet (10) intersects with the vertical axis of the classifying chamber (7).

2. A nano metal powder classification device according to claim 1, characterized in that: The electrostatic field voltage between the classifying wheel (14) and the electrode (17) is 100-2000V.

3. The nano metal powder classification device according to claim 1, characterized in that: The rotation speed of the classifying wheel (14) is 10000-22000 rpm.

4. The nano metal powder classification device according to claim 1, characterized in that: The pressure of the gas introduced into the carrier gas inlet (10) is 0.2-1.0 MPa.

5. The nano metal powder classification device according to claim 1, characterized in that: Two or more classifying wheels (14) are provided, and all the classifying wheels (14) are arranged in a circle, and the axes of the classifying wheels (14) intersect.

6. A nano-metal powder classification method for the nano-metal powder classification device according to claim 1, characterized in that: The following steps are involved: P1. Start the classifying wheel (14) through the driving assembly, introduce gas through the carrier gas inlet (10), connect the classifying wheel (14) and the electrode (17) to a power source respectively, and start the electron emission assembly; P2. Add the nano-metal powder to be classified, adjust the rotation speed of the classification wheel (14) and the voltage between the classification wheel (14) and the electrode (17) according to the target particle size.

7. The nano metal powder classification method according to claim 6, characterized in that: In P1, the pressure of the gas introduced into the carrier gas inlet (10) is kept constant by a circulating fan.

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