Nanopowder production method

Abstract

The present application relates to the technical field of nanopowder production, and more particularly to a nanopowder production method. A nanopowder production apparatus. The nanopowder production apparatus comprises an evaporation tank and an electric-arc generator, wherein the electric-arc generator penetrates the top of the evaporation tank; and the electric-arc generator is provided with an electric-arc sheath gas passage, one end of the electric-arc sheath gas passage being in communication with the interior of the evaporation tank, and the other end thereof being in communication with the outside. When the apparatus in the present application is used to prepare a nanopowder, an electric-arc sheath gas is introduced into the apparatus and directly acts on a high-temperature core area of an electric arc, so that the temperature gradient of the core area can be increased, and the concentration of vapor around the electric arc is directly reduced, thus inhibiting excessive collisions between raw-material atoms, and reducing the possibility of a sharp increase in the particle size of nanoparticles. On the premise of a relatively high arc current and a relatively high yield, a nanopowder is guaranteed to have a relatively small particle size.

Description

A method for producing nanopowder Technical Field

[0001] The present application relates to the technical field of nano powder production, and more specifically, to a method for producing nano powder. Background Art

[0002] Nanopowders typically refer to particles with sizes between atoms, molecules, and macroscopic substances. These particles are larger than atomic clusters but smaller than typical micropowders. They are currently widely used in coatings and other applications to improve surface properties and achieve high-precision manufacturing. Nanopowders are typically required to have an average particle size below 100 nm, a narrow particle size distribution, and a well-defined spherical shape.

[0003] There are various methods for producing nanopowders. The DC arc plasma method, a type of gas evaporation method, is ideal for producing nanopowders. This method uses an electric arc to generate high-energy plasma, heating the raw material and causing it to evaporate. The vapor then condenses and coalesces to form nanoparticles. Nanopowders produced using this method have the advantages of high purity and excellent sphericity.

[0004] To increase the yield of nanopowders, the industry typically adopts the method of increasing the arc current and inputting high energy. However, increasing the arc current causes a large amount of raw material to evaporate in a short period of time, thereby increasing the vapor concentration. When the vapor is oversaturated, collisions between raw material atoms intensify, causing the nanopowder particle size to increase sharply. Although reducing the arc current can produce nanopowders with smaller particle sizes, it will lead to a decrease in nanopowder yield. Therefore, how to obtain nanopowders with smaller particle sizes while ensuring high yields is an urgent problem that needs to be solved in the industry.

[0005] Summary of the Invention

[0006] In order to obtain nanopowder with smaller particle size while ensuring higher yield, the present application provides a nanopowder production method.

[0007] In a first aspect, the present application provides a nanopowder production device, which adopts the following technical solution:

[0008] A nanopowder production device comprises an evaporator, an arc generator, and a cooling collection chamber. The evaporator is provided with a feed pipe, and is horizontally provided with a main sheath gas inlet and a discharge port, the discharge port being connected to the cooling collection chamber. The arc generator is provided through the top of the evaporator, a crucible is provided inside the evaporator, and the arc generator is arranged above the crucible. The arc generator is provided with an arc sheath gas channel, one end of which is connected to the interior of the evaporator, and the other end is connected to the outside.

[0009] By adopting the above technical solution, a main sheath gas inlet is provided in the horizontal direction of the evaporation tank, and an arc sheath gas channel is provided on the arc generator. When the arc generator is started, the raw materials on the crucible evaporate into steam at high temperature, and sheath gas is introduced into the evaporation tank through the main sheath gas inlet and the arc sheath gas channel. The arc sheath gas directly acts on the high-temperature core area generated by the arc, which can increase the temperature gradient in the core area and directly reduce the vapor concentration around the arc, thereby suppressing excessive collisions between raw material atoms and reducing the possibility of a sharp increase in the particle size of the nanoparticles. The main sheath gas not only assists the arc sheath gas to reduce the vapor concentration, but also blows the formed nanoparticles into the cooling and collection chamber.

[0010] In summary, with the cooperation of arc sheath gas and main sheath gas, nanopowder with smaller particle size can be obtained at a higher arc current, which overcomes the contradiction between high yield of nanopowder and small particle size.

[0011] Preferably, the top of the evaporation tank is further provided with a plurality of auxiliary sheath gas inlets.

[0012] By adopting the above technical solution, auxiliary sheath gas is introduced into several auxiliary sheath gas inlets, and the auxiliary sheath gas cooperates with the main sheath gas and the arc sheath gas to further reduce the raw material vapor concentration, thereby further reducing the possibility of the nanopowder having too large a particle size under high arc current.

[0013] Preferably, an annular groove is provided at one end of the arc generator located inside the evaporation tank, and a strip channel is provided on the arc generator along its own length direction, one end of the strip channel is connected to the outside, and the other end is connected to the annular groove, and the annular groove and the strip channel together constitute the arc sheath gas channel.

[0014] By adopting the above technical solution, the arc sheath gas enters the annular groove through the strip channel, and then diffuses into the high-temperature core area generated by the arc through the annular groove. The annular groove can guide the arc sheath gas to diffuse evenly around the high-temperature core area, further reducing the possibility of excessive collisions between raw material atoms leading to excessive particle size.

[0015] Preferably, the nanopowder production equipment also includes an air intake assembly, which includes an air intake ring arranged inside the evaporator, an air intake pipe whose air outlet end is connected to the cooling collection chamber, and a connecting pipe connecting the air intake ring and the air intake pipe, the air intake ring is located above the crucible, and a plurality of air intake ports are provided on the inner ring of the air intake ring, and two sealing frames are provided inside the air intake pipe along the direction of air flow, and a sealing door is hinged on the top side of each sealing frame away from the connecting pipe, and the sealing door covers the opening of the sealing frame, and an air storage pipe is connected between the two sealing doors on the air intake pipe, and a sealing plug is slidingly provided inside the air storage pipe, and a cylinder is provided at the end of the air storage pipe away from the air intake pipe, and the piston rod of the cylinder passes through the air storage pipe and is connected to the sealing plug.

[0016] By adopting the above technical solution, the nano-powder formed by evaporation in the high-temperature core area of ​​the arc has a high temperature and a low cooling rate, and the grains grow once, which easily forms large particles; and the suction component can cooperate with the main sheath gas to accelerate the nano-powder to leave the high-temperature core area of ​​the arc and reduce the particle growth of the nano-powder in the high-temperature core area.

[0017] In a second aspect, the present application provides a method for producing nanopowders, which adopts the following technical solution:

[0018] A method for producing nanopowder, which is implemented in the aforementioned nanopowder production equipment, comprises the following steps:

[0019] S1, placing the metal solid on the crucible and using inert gas to replace the air in the evaporation tank;

[0020] S2, start the arc generator power supply, adjust the arc current to 200-500A, and adjust the arc generator height so that the arc voltage is 40-120V. The metal solid evaporates into steam under the high temperature of the arc;

[0021] In step S3, arc sheath gas is introduced into the evaporator at a flow rate of 100-500 cc / min depending on the arc current; main sheath gas is introduced into the evaporator at a flow rate of 500-1600 SLPM to ensure an average temperature in the evaporator of 500-600 K. The steam is blown by the arc sheath gas and the main sheath gas, diffused into nanopowder, and the nanopowder leaves the evaporator through the discharge port under the entrainment of the main sheath gas, obtaining a nanopowder with a particle size of 65-90 nm.

[0022] By adopting the above technical solution and using the above nanopowder production equipment to produce and prepare nanopowder, during the preparation process, the arc sheath gas directly acts on the high-temperature core area generated by the arc, directly reducing the steam concentration around the arc, thereby inhibiting excessive collisions between metal solid atoms and reducing the possibility of a sharp increase in the particle size of the nanoparticles.

[0023] Preferably, the arc current is 400-500A.

[0024] Preferably, the arc voltage is 100-120V.

[0025] Preferably, the average temperature in the evaporation tank is 550-600K.

[0026] 0020. Preferably, the arc sheath gas is prepared by compounding argon and hydrogen in a volume ratio of (8-10):1.

[0027] In summary, this application has the following beneficial effects:

[0028] The present application discloses a nano powder production device, comprising an arc sheath gas channel, a main sheath gas inlet, and an auxiliary sheath gas inlet. Arc sheath gas is introduced into the interior of the device through the arc sheath gas channel, which can directly act on the high-temperature core area of ​​the arc, directly reducing the vapor concentration around the arc, thereby inhibiting excessive collisions between raw material atoms and reducing the possibility of a sharp increase in the particle size of nanoparticles; main sheath gas and auxiliary sheath gas are introduced into the device through the main sheath gas inlet and the auxiliary sheath gas inlet. The main sheath gas and auxiliary sheath gas can cooperate with the arc sheath gas on the one hand to further reduce the raw material vapor concentration, and on the other hand, can blow the formed nano powder into a cooling collection chamber. The three sheath gases work together to make the nano powder have the advantages of high yield and small particle size. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG1 is a schematic structural diagram of the nanopowder production equipment in this application.

[0030] FIG2 is a schematic diagram showing the internal structure of the arc generator in Example 1 of the present application.

[0031] FIG3 is a schematic diagram of an air intake assembly according to Example 2 of the present application.

[0032] FIG4 is an enlarged view of portion A in FIG3 .

[0033] Explanation of the accompanying symbols: 1. Evaporation tank; 2. Arc generator; 21. Arc sheath gas channel; 211. Strip channel; 212. Annular groove; 22. Cooling water channel; 3. Cooling collection chamber; 4. Feed pipe; 5. Discharge port; 6. Main sheath gas inlet; 7. Auxiliary sheath gas inlet; 8. Crucible platform; 9. Crucible; 10. Induction auxiliary heating coil; 11. Water-cooled interlayer; 12. Inhalation assembly; 13. Inhalation ring; 14. Inhalation pipe; 15. Connecting pipe; 16. Inhalation port; 17. Sealing frame; 18. Sealing door; 19. Gas storage pipe; 20. Sealing plug; 21. Cylinder; 22. Piston rod; 23. Vent. DETAILED DESCRIPTION

[0034] Currently, to increase nanopowder production, the industry typically employs methods such as increasing arc current and inputting high energy. However, increasing arc current causes a large amount of raw material to evaporate in a short period of time, which in turn increases vapor concentration. When the vapor becomes oversaturated, collisions between raw material atoms intensify, causing the nanopowder particle size to increase dramatically. While reducing arc current can produce smaller nanopowders, it also results in lower nanopowder production.

[0035] Based on the above situation, the applicant conducted extensive research on nanopowder production processes and equipment, aiming to develop a method for producing small-particle nanopowders while increasing production. Initially, the applicant employed a method in which gas channels were installed in the vessel wall to introduce cooling gas into the interior. This approach lowered the average temperature of the evaporation chamber, widened the temperature gradient, caused the vapor to condense suddenly, suppressed vapor concentration, and compressed the particle size. While this method was effective, the effect of suppressing vapor concentration was limited because the introduced gas avoided the high-temperature core area generated by the arc.

[0036] Based on this, the applicant further modified the nanopowder production equipment, opening an arc sheath gas channel on the arc generator and introducing arc sheath gas into the equipment through the arc sheath gas channel. The arc sheath gas directly acts on the high-temperature core area generated by the arc, directly reducing the vapor concentration around the arc, thereby inhibiting excessive collisions between raw material atoms and reducing the possibility of a sharp increase in the particle size of the nanoparticles. The flow rate of the arc sheath gas can be adjusted according to the arc current, so that the nanopowder has the advantages of high yield and small particle size.

[0037] Example

[0038] The present application is further described in detail below with reference to Figures 1-4.

[0039] The embodiment of the present application discloses a nano powder production device.

[0040] Example 1

[0041] Referring to Figure 1, a nanopowder production device includes an evaporator 1, an arc generator 2, and a cooling collection chamber 3. The evaporator 1 is cylindrical, with its axis in a horizontal state and its two ends tapered. A feed pipe 4 is provided through the evaporator 1. A main sheath gas inlet 6 is provided horizontally at one end of the evaporator 1, and a discharge port 5 is provided horizontally at the other end. Four auxiliary sheath gas inlets 7 are also provided on the top of the evaporator 1 for use in conjunction with the main sheath gas inlet 6. The evaporator 1 has a double-layer structure, with the inner layer filled with cold water to form a water-cooled interlayer 11, which is used to protect the equipment and reduce the possibility of damage to the equipment at high temperatures.

[0042] Referring to FIG1 , a crucible platform 8 is provided inside the evaporator 1 , on which a crucible 9 is placed for placing raw materials. An induction heating coil 1 for auxiliary heating is also provided on the outer wall of the crucible 9 . Referring to FIG1 and FIG2 , an arc generator 2 is provided through the top of the evaporator 1 , with the end of the arc generator 2 near the interior of the evaporator 1 extending directly above the crucible 9 . The arc generator 2 is provided with an arc sheath gas channel 21 , which is composed of an annular groove 212 and a strip-shaped channel 211 . The annular groove 212 is provided at the end of the arc generator 2 located inside the evaporator 1 . The strip-shaped channel 211 extends along the length of the arc generator 2 , with one end communicating with the outside and the other end communicating with the annular groove 212 . The arc generator 2 is also provided with a cooling water channel 22 for protecting the arc generator 2 . The cooling water channel 22 is provided along the length of the arc generator 2 , with one end communicating with the outside.

[0043] Example 2

[0044] The difference between this embodiment and embodiment 1 is that, referring to FIG1 , FIG3 and FIG4 , this embodiment provides a nanopowder production device, further comprising an air intake assembly 12 , the air intake assembly 12 comprising an air intake ring 13 , the air intake ring 13 being disposed inside the evaporation tank 1 and above the crucible 9 , and further comprising an air intake pipe 14 whose air outlet end is connected to the cooling collection chamber 3 , and a connecting pipe 15 connecting the air intake ring 13 and the air intake pipe 14 ; the inner ring of the air intake ring 13 is provided with five air intake ports 16 ;

[0045] Referring to Figures 1, 3 and 4, two sealing frames 17 are provided inside the intake pipe 14 along the direction of air flow, and a sealing door 18 for covering the opening of the sealing frame 17 is hinged on the side of the top of the sealing frame 17 away from the connecting pipe 15; an air storage pipe 19 is connected to the intake pipe 14 between the two sealing doors 18, and a sealing plug 20 is slidably provided in the air storage pipe 19, and a cylinder 21 is provided at one end of the air storage pipe 19 away from the intake pipe 14, and a piston rod 22 of the cylinder 21 passes through the air storage pipe 19 and is fixedly connected to the sealing plug 20, and a vent 23 is provided on the side wall of the air storage pipe 19 close to one end of the cylinder 21.

[0046] Application Example 1

[0047] A method for producing nanopowder is implemented in the nanopowder production equipment of Example 1 and is carried out according to the following steps:

[0048] S1, place the raw nickel ingot in the crucible, adjust the arc generator to the set height, start the vacuum pump, and reduce the pressure of the evaporation tank to 10 -4 Pa (A), argon gas was introduced to restore the pressure to 0.06 MPa (A), and this process was repeated three times to ensure that the air in the evaporation tank was replaced by inert gas argon.

[0049] S2, start the arc generator power supply, establish an arc between the arc generator and the raw material, increase the arc current to 200A, and adjust the height of the arc generator so that the arc voltage is 40V. The main raw material nickel ingot evaporates into steam under the high temperature of the arc;

[0050] S3, sheath gas is introduced into the evaporator through the main sheath gas inlet, auxiliary sheath gas inlet and arc sheath gas channel, and the arc sheath gas flow rate is adjusted according to the arc current. In this application example, the arc sheath gas flow rate is 100cc / min. At the same time, the main sheath gas flow rate is adjusted to 500SLPM and the auxiliary sheath gas flow rate is adjusted to 100SLPM to ensure that the average temperature in the evaporator is 500K. Among them, the main sheath gas and auxiliary sheath gas are both pure argon, and the arc sheath gas is prepared by mixing argon and hydrogen in a volume ratio of 8:1. The arc sheath gas causes the metal vapor to diffuse, reducing the vapor concentration around the high-temperature core area of ​​the arc. The blown metal vapor moves downstream along the horizontal axis of the evaporator under the blowing of the main sheath gas and auxiliary sheath gas. During this period, the metal vapor gradually condenses to form nano-metal powder, which enters the cooling collection chamber under the action of the airflow.

[0051] Application Example 2

[0052] A nanopowder production method is implemented in the nanopowder production equipment of Example 1. The difference from Application Example 1 is that the volume ratio of argon and hydrogen in the arc sheath gas is different. In this application example, the volume ratio of argon and hydrogen is 10:1.

[0053] Application Example 3

[0054] A nanopowder production method is implemented in the nanopowder production equipment of Example 1. The difference from Application Example 1 is that the volume ratio of argon and hydrogen in the arc sheath gas is different. In this application example, the volume ratio of argon and hydrogen is 9:1.

[0055] Application Examples 4-5

[0056] A nanopowder production method is implemented in the nanopowder production equipment of Example 1. The differences from Application Example 1 are that the arc current, arc voltage, arc sheath gas flow rate, main sheath gas flow rate, auxiliary sheath gas flow rate, and average temperature in the evaporation tank are different, as shown in Table 1 below:

[0057] Table 1

[0058] Application Example 6

[0059] A method for producing nanopowder, which differs from Application Example 4 in that the method is implemented in the nanopowder production equipment of Example 2 and is carried out according to the following steps:

[0060] S1, place the raw nickel ingot in the crucible, adjust the arc generator to the set height, start the vacuum pump, and reduce the pressure of the evaporation tank to 10 -4 Pa (A), argon gas was introduced to restore the pressure to 0.06 MPa (A), and this process was repeated three times to ensure that the air in the evaporation tank was replaced by inert gas argon.

[0061] S2, start the arc generator power supply, establish an arc between the arc generator and the raw material, increase the arc current to 500A, and adjust the height of the arc generator so that the arc voltage is 120V. The main raw material nickel ingot evaporates into steam under the high temperature of the arc;

[0062] S3, sheath gas is introduced into the evaporator through the main sheath gas inlet, auxiliary sheath gas inlet and arc sheath gas channel, and the arc sheath gas flow rate is adjusted according to the arc current. In this application example, the arc sheath gas flow rate is 500cc / min. At the same time, the main sheath gas flow rate is adjusted to 1600SLPM and the auxiliary sheath gas flow rate is adjusted to 600SLPM to ensure that the average temperature in the evaporator is 600K. Among them, the main sheath gas and auxiliary sheath gas are both pure argon, and the arc sheath gas is prepared by compounding argon and hydrogen in a volume ratio of 8:1. The arc sheath gas causes the metal vapor to diffuse, reducing the vapor concentration around the high-temperature core area of ​​the arc; a part of the blown metal vapor moves downstream along the horizontal axis of the evaporator under the blowing of the main sheath gas and auxiliary sheath gas, during which the metal vapor gradually condenses to form nano-metal powder, which enters the cooling collection chamber under the action of the airflow.

[0063] At the same time as the main sheath gas is introduced, the suction component is started, that is, the cylinder is started. The cylinder drives the sealing plug to move upward to form a negative pressure. A part of the nanopowder around the suction ring (the high-temperature core area of ​​the arc) enters the suction ring through the suction port, and then enters the suction pipe through the connecting pipe and is located between the two sealing doors. When the cylinder drives the sealing plug to move downward, the sealing door close to the connecting pipe is closed, and the sealing door away from the connecting pipe is opened. Under the action of air pressure, the nanopowder leaves the suction pipe through the sealing door away from the connecting pipe and enters the cooling collection chamber.

[0064] This application example is implemented in the nanopowder production equipment of Example 2. By using the suction component in conjunction with the main sheath gas and auxiliary sheath gas, the nanopowder is accelerated to leave the high-temperature core area of ​​the arc and the particle growth of the nanopowder in the high-temperature core area is reduced.

[0065] Application comparison

[0066] Comparative Application Example 1

[0067] A nanopowder production method is implemented in the nanopowder production equipment of Example 1. The operating steps are similar to those of Application Example 5. The difference from Application Example 5 is that in step S3, only the main sheath gas and the auxiliary sheath gas are introduced into the evaporation tank, and the arc sheath gas is not introduced.

[0068] Performance Testing

[0069] The yield of the nanopowder production method corresponding to Examples 1-6 and Comparative Example 1 and the particle size of the nanopowder obtained by the method were tested, as shown in the following table:

[0070] Table 2. Performance test

[0071] As can be seen from Table 2, the nanopowders produced according to the preparation methods of the application examples of this application all have a particle size of less than 100 nm, meeting the requirements for the use of nanopowders. Specifically, the yield of application examples 4-5 was much greater than that of application examples 1-3, and the particle size of the nanopowders was similar to that of application examples 1-3. The yield of application examples 4-5 was similar to that of comparative application example 1, but the particle size of the nanopowders produced in application examples 4-5 was much smaller than that of comparative application example 1.

[0072] This may be because: in the production process of Application Example 4-5, the arc current is relatively high, and the flow parameters of the arc sheath gas, main sheath gas and auxiliary sheath gas are adjusted to regulate the concentration of the metal vapor, thereby reducing the metal vapor concentration and suppressing excessive collisions of metal atoms, thereby avoiding the uncontrolled enlargement of the metal powder particle size. At a higher output, a nanopowder with a smaller particle size is obtained; while in Application Comparative Example 1, no arc sheath gas is introduced, which may lead to an excessively high metal vapor concentration and excessive collisions of metal atoms, which in turn leads to a larger particle size of the nanopowder.

[0073] This application can achieve different system functions through different sheath gas component combinations and different sheath gas flow parameters to match the production needs of various nanopowders, including but not limited to nano copper powders.

[0074] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A method for producing nanopowder, characterized in that: The method is implemented in a nano powder production device, which comprises an evaporator (1), an arc generator (2) and a cooling collection chamber (3); a feed pipe (4) is provided on the evaporator (1); a main sheath gas inlet (6) and a discharge port (5) are provided on the evaporator (1) in a horizontal direction; the discharge port (5) is communicated with the cooling collection chamber (3); the arc generator (2) is provided on the top of the evaporator (1); a crucible (9) is provided inside the evaporator (1); the arc generator (2) is arranged above the crucible (9); an arc sheath gas channel (21) is provided on the arc generator (2); one end of the arc sheath gas channel (21) is communicated with the inside of the evaporator (1), and the other end is communicated with the outside; The nano powder production equipment also includes an air intake component (12), the air intake component (12) including an air intake ring (13) arranged inside the evaporation tank (1), an air intake pipe (14) whose air outlet end is connected to the cooling collection chamber (3), and a connecting pipe (15) connecting the air intake ring (13) and the air intake pipe (14), the air intake ring (13) is located above the crucible (9), a plurality of air intake ports (16) are arranged on the inner circle of the air intake ring (13), and two sealing frames (17) are arranged inside the air intake pipe (14) along the air flow direction, each of which is provided with a plurality of air intake ports (16). A sealing door (18) is hingedly connected to one side of the top of the sealing frame (17) away from the connecting pipe (15), and the sealing door (18) covers the opening of the sealing frame (17). An air storage pipe (19) is connected between the two sealing doors (18) on the air intake pipe (14), and a sealing plug (20) is slidably arranged inside the air storage pipe (19). A cylinder (21) is arranged at one end of the air storage pipe (19) away from the air intake pipe (14), and a piston rod (22) of the cylinder (21) passes through the air storage pipe (19) and is connected to the sealing plug (20); The method comprises the following steps: S1, placing a metal solid on a crucible (9), and replacing the air in an evaporation tank (1) with an inert gas; S2, start the power supply of the arc generator (2), adjust the arc current to 200-500A, and adjust the height of the arc generator (2) so that the arc voltage is 40-120V, and the metal solid evaporates into steam under the high temperature of the arc; S3, according to the arc current, arc sheath gas with a flow rate of 100-500cc / min is introduced into the evaporation tank (1); main sheath gas with a flow rate of 500-1600SLPM is introduced into the evaporation tank (1) to ensure that the average temperature in the evaporation tank (1) is 500-600K; the steam is blown by the arc sheath gas and the main sheath gas to diffuse into nanoparticles. The powder, nano powder, is entrained by the main sheath gas and leaves the evaporation tank (1) through the discharge port (5), thereby obtaining a nano powder with a particle size of 65-90 nm.

2. A method for producing nanopowder according to claim 1, characterized in that: The top of the evaporation tank (1) is also provided with an auxiliary sheath gas inlet (7).

3. A method for producing nanopowder according to claim 1, characterized in that: An annular groove (212) is provided at one end of the arc generator (2) located inside the evaporation tank (1); a strip-shaped channel (211) is provided on the arc generator (2) along its length direction; one end of the strip-shaped channel (211) is connected to the outside, and the other end is connected to the annular groove (212); the annular groove (212) and the strip-shaped channel (211) together constitute an arc sheath gas channel (21).

4. A method for producing nanopowder according to claim 1, characterized in that: The arc current is 400-500A.

5. A method for producing nanopowder according to claim 1, characterized in that: The arc voltage is 100-120V.

6. A method for producing nanopowder according to claim 1, characterized in that: The average temperature in the evaporation tank (1) is 550-600K.

7. A method for producing nanopowder according to claim 1, characterized in that: The arc sheath gas is prepared by compounding argon and hydrogen in a volume ratio of (8-10):1.

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