Nanopowder manufacturing method

Abstract

The present application relates to the technical field of nanopowder production, and more particularly, to a method for producing nanopowder. The present application discloses an apparatus for producing nanopowder, comprising an evaporator and an arc generator. The arc generator is drilled at the top of the evaporator, and an arc sheath gas passage is formed in the arc generator, with one end communicating with the inside of the evaporator and the other end communicating with the outside. When producing nanopowder using the apparatus, arc sheath gas is introduced into the apparatus and acts directly on the high-temperature core region of the arc, thereby improving the temperature gradient in the core region and directly reducing the concentration of vapor around the arc, thereby suppressing excessive collisions between atoms of the raw material and reducing the possibility of a rapid increase in the particle size of the nanoparticles. Under the assumption that the arc current is high and the yield is high, the nanopowder can be guaranteed to have a small particle size.

Description

[Technical Field]

[0001] TECHNICAL FIELD This application relates to the technical field of nanopowder production, and more particularly to a method for producing nanopowder. [Background technology]

[0002] Nanopowder generally refers to particles whose size is between that of atoms, molecules, and macromolecules. Their size is larger than that of atomic clusters, but smaller than that of ordinary fine powders. Currently, they are widely used in coatings, film coatings, and other fields to improve the surface performance of workpieces and achieve high-precision manufacturing. Nanopowder is typically required to have an average particle size of 100 nm or less, a narrow particle size distribution, and suitable spherical shape.

[0003] There are various methods for producing nanopowder. The DC arc plasma method, which is a gas evaporation method, is an ideal method for producing nanopowder. It uses an arc to generate high-energy plasma to heat and vaporize raw materials. The vapor then condenses and agglomerates to form nanoparticles. Nanopowder produced by the arc method has advantages such as high purity and good sphericity.

[0004] To improve the yield of nanopowder, the industry typically uses a method of increasing the arc current and inputting high energy. Increasing the arc current causes a large amount of raw material to evaporate in a short period of time, further increasing the vapor concentration. When the vapor becomes too saturated, the collisions between the raw material atoms become more intense, resulting in a rapid increase in the particle size of the nanopowder. Reducing the arc current produces nanopowder with a smaller particle size, but at a lower yield. Therefore, how to obtain nanopowder with a smaller particle size while ensuring high yield is an issue that the industry urgently needs to address. Summary of the Invention [Problem to be solved by the invention]

[0005] In order to obtain nanopowder with small particle size while ensuring high yield, the present application provides a method for producing nanopowder. [Means for solving the problem]

[0006] In a first aspect, the present application provides a nanopowder manufacturing apparatus, which uses the following technical means:

[0007] A nanopowder manufacturing apparatus comprising an evaporator, an arc generator, and a cooling and collecting chamber, wherein a supply pipe is drilled in the evaporator, and a main sheath gas inlet and outlet are installed horizontally, the outlet being connected to the cooling and collecting chamber, the arc generator is drilled at the top of the evaporator, a crucible is installed inside the evaporator, the arc generator is installed above the crucible, an arc sheath gas passage is formed in the arc generator, one end of the arc sheath gas passage is connected to the inside of the evaporator, and the other end is connected to the outside.

[0008] According to the above technical means, a main sheath gas inlet is formed horizontally in the evaporator, and an arc sheath gas passage is formed in the arc generator. When the arc generator is activated, the raw material on the crucible evaporates at high temperature and turns into vapor. Sheath gas is introduced into the evaporator through the main sheath gas inlet and the arc sheath gas passage. The arc sheath gas acts directly on the high-temperature core region created by the arc, thereby improving the temperature gradient in the core region and directly reducing the concentration of vapor around the arc, thereby suppressing excessive collisions between raw material atoms and reducing the possibility of a rapid increase in the particle size of nanoparticles. The main sheath gas assists the arc sheath gas in reducing the concentration of vapor, while blowing the formed nanoparticles into a cooling collection chamber.

[0009] From the above, the combination of arc sheath gas and main sheath gas can obtain nanopowder with small particle size at high arc current, thus overcoming the trade-off between high yield and small particle size of nanopowder.

[0010] Preferably, a plurality of auxiliary sheath gas inlets are further formed at the top of the evaporator.

[0011] According to the above technical means, auxiliary sheath gas is introduced into multiple auxiliary sheath gas inlets, and the auxiliary sheath gas is combined with the main sheath gas and the arc sheath gas to further reduce the concentration of the raw material vapor, thereby further reducing the possibility that the particle size of the nanopowder will be too large at high arc currents.

[0012] Preferably, an annular groove is formed at one end of the arc generator located inside the evaporator can, a strip-shaped passage is formed in the arc generator along its length, one end of the strip-shaped passage communicates with the outside and the other end communicates with the annular groove, and the annular groove and the strip-shaped passage together form an arc sheath gas passage.

[0013] According to the above technical means, the arc sheath gas enters the annular groove through the band-shaped passage and then diffuses through the annular groove to the high-temperature core region generated by the arc, and the annular groove can guide the arc sheath gas to diffuse uniformly around the high-temperature core region, further reducing the possibility of excessive collisions between atoms of the raw material resulting in excessively large particle sizes.

[0014] Preferably, the nanopowder manufacturing apparatus further includes an intake assembly, which includes an intake ring installed inside the evaporator, an intake pipe whose exhaust end is connected to the cooling and collecting chamber, and a connecting pipe connecting the intake ring and the intake pipe. The intake ring is located above the crucible, and a plurality of intake ports are installed on the inner ring of the intake ring. Two sealing frames are installed inside the intake pipe along the air flow direction, and a sealing gate is hingedly connected to the top of each sealing frame on the side away from the connecting pipe, and the sealing gate covers the opening of the sealing frame. A gas storage pipe is connected between the two sealing gates in the intake pipe. A sealing plug is slidably installed inside the gas storage pipe. A cylinder is installed at the end of the gas storage pipe away from the intake pipe, and the piston rod of the cylinder is drilled into the gas storage pipe and connected to the sealing plug.

[0015] According to the above technical means, the nanopowder formed by evaporation has a high temperature in the arc high-temperature core region, so the cooling rate is slow, the primary crystal grains grow large, and it is easy to form large particles. The intake assembly, in combination with the main sheath gas, can accelerate the nanopowder's departure from the arc high-temperature core region and reduce the particle growth of the nanopowder in the high-temperature core region.

[0016] In a second aspect, the present application provides a method for producing nanopowder, which uses the following technical means:

[0017] A nanopowder production method carried out in the nanopowder production apparatus, the method comprising: Step S1: placing a metal solid in a crucible and replacing the air in an evaporator with an inert gas; Step S2: start the power supply of the arc generator, adjust the arc current to 200-500A so that the arc voltage is 40-120V, and adjust the height of the arc generator, so that the metal solid evaporates into vapor under the high temperature action of the arc; The method includes step S3 of introducing an arc sheath gas into the evaporator at a flow rate of 100 to 500 cc / min according to the magnitude of the arc current, and introducing a main sheath gas into the evaporator at a flow rate of 500 to 1600 SLPM (standard liter per minute) to ensure that the average temperature inside the evaporator is 500 to 600 K, spraying steam with the arc sheath gas and the main sheath gas to diffuse it as nanopowder, mixing the nanopowder with the main sheath gas and sending it out of the evaporator through an outlet, thereby obtaining nanopowder with a particle size of 65 to 90 nm.

[0018] According to the above technical means, nanopowder is produced using the above nanopowder production device, and during the production process, the arc sheath gas directly acts on the high-temperature core region created by the arc, thereby directly reducing the concentration of vapor around the arc, thereby suppressing excessive collisions between atoms of the metal solid and reducing the possibility of a sudden increase in the particle size of the nanoparticles.

[0019] Preferably, the arc current is 400 to 500A.

[0020] Preferably, the arc voltage is 100 to 120V.

[0021] Preferably, the average temperature inside the evaporator is 550 to 600K.

[0022] Preferably, the arc sheath gas is obtained by mixing argon gas and hydrogen gas in a volume ratio of (8-10:1). [Effects of the Invention]

[0023] From the above, the present application has the following beneficial effects.

[0024] The nanopowder production apparatus of the present application includes an arc sheath gas passage, a main sheath gas inlet, and an auxiliary sheath gas inlet. The arc sheath gas is introduced into the apparatus through the arc sheath gas passage and can directly act on the high-temperature core region of the arc, thereby directly reducing the concentration of vapor around the arc, thereby preventing excessive collisions between source atoms and reducing the possibility of rapid growth of nanoparticle size. The main sheath gas and auxiliary sheath gas are introduced into the apparatus through the main sheath gas inlet and auxiliary sheath gas inlet, and the main sheath gas and auxiliary sheath gas combine with the arc sheath gas to further reduce the concentration of source vapor, while the formed nanopowder is blown into a cooling collection chamber. The combination of three sheath gases achieves the advantages of high yield and small particle size of nanopowder. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a schematic diagram of a nanopowder manufacturing apparatus according to the present invention; [Figure 2] 1 is a schematic diagram of the internal structure of an arc generator according to a first embodiment of the present application. [Figure 3] FIG. 10 is a schematic diagram of an intake assembly according to a second embodiment of the present application. [Figure 4] FIG. 4 is an enlarged view of part A in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0026] Currently, the industry generally uses a method of increasing the arc current and inputting high energy to improve the yield of nanopowder. Increasing the arc current causes a large amount of raw material to evaporate in a short period of time, further increasing the vapor concentration. When the vapor becomes too saturated, the collisions between the raw material atoms become more intense, causing the particle size of the nanopowder to increase rapidly. Reducing the arc current produces nanopowder with a smaller particle size, but the yield of nanopowder decreases.

[0027] Based on the above situation, the applicant has conducted in-depth research into the nanopowder manufacturing process and manufacturing equipment, aiming to find a method for producing nanopowder with small particle size, with the premise of improving yield. Initially, the applicant used a gas passage in the vessel wall to introduce cooling gas, lowering the average temperature of the evaporation chamber, widening the temperature gradient, causing the vapor to rapidly condense, suppressing the vapor concentration, and compressing the particle size. While this method has some effect, the introduced gas avoids the high-temperature core region caused by the arc, limiting the effect of suppressing the vapor concentration.

[0028] Based on this, the applicant modified a nanopowder manufacturing apparatus to form an arc sheath gas passage in the arc generator and introduce arc sheath gas into the apparatus through the arc sheath gas passage. The arc sheath gas acts directly on the high-temperature core region of the arc, directly reducing the concentration of vapor around the arc, thereby suppressing excessive collisions between atoms of the raw material and reducing the possibility of a sudden increase in the particle size of the nanoparticles. The flow rate of the arc sheath gas can be adjusted and controlled according to the magnitude of the arc current, thereby achieving the advantages of high yield and small particle size of the nanopowder.

[0029] Embodiment The present invention will be described in further detail below with reference to FIGS.

[0030] An embodiment of the present application discloses an apparatus for producing nanopowder.

[0031] Embodiment 1 As shown in Figure 1, the nanopowder manufacturing apparatus includes an evaporator 1, an arc generator 2, and a cooling collection chamber 3. The evaporator 1 is cylindrical, with its axis horizontal and both ends conical. A supply pipe 4 is drilled into the evaporator 1. A main sheath gas inlet 6 is installed horizontally at one end of the evaporator 1, and an outlet 5 is installed horizontally at the other end. Four auxiliary sheath gas inlets 7 are further formed at the top of the evaporator 1 and are used in combination with the main sheath gas inlet 6. The evaporator 1 has a double structure, with the inner layer filled with cold water, forming a water-cooled intermediate layer 11 that protects the apparatus and reduces the possibility of damage to the apparatus due to high temperatures.

[0032] As shown in FIG. 1, a crucible stand 8 is installed inside evaporator 1, and a crucible 9 is placed on crucible stand 8. Raw materials are placed on crucible 9, and an auxiliary heating induction coil 10 is further installed on the outer wall to assist in heating. As shown in FIGS. 1 and 2, an arc generator 2 is drilled into the top of evaporator 1, and one end of arc generator 2 close to the inside of evaporator 1 extends to just above crucible 9. Arc generator 2 forms an arc sheath gas passage 21, which is composed of an annular groove 212 and a strip-shaped passage 211. An annular groove 212 is formed at one end of arc generator 2 located inside evaporator 1, and strip-shaped passage 211 is formed along the length of arc generator 2, with one end connected to the outside and the other end connected to annular groove 212. The arc generator 2 is further provided with a cooling water passage 22 for protecting the arc generator 2, the cooling water passage 22 being installed along the length of the arc generator 2 and one end of which is connected to the outside.

[0033] Embodiment 2 The present embodiment differs from embodiment 1 in the following respects: As shown in Figures 1, 3 and 4, the nano-powder manufacturing apparatus of this embodiment further includes an intake assembly 12, which includes an intake ring 13, which is installed inside the evaporator 1 and located above the crucible 9, and the nano-powder manufacturing apparatus further includes an intake pipe 14 whose exhaust end communicates with the cooling and collecting chamber 3 and a communication pipe 15 that communicates between the intake ring 13 and the intake pipe 14, and five intake ports 16 are formed on the inner ring of the intake ring 13.

[0034] As shown in Figures 1, 3 and 4, two sealing frames 17 are installed inside the intake pipe 14 along the air flow direction, and a sealing gate 18 covering the opening of the sealing frame 17 is hingedly connected to the top of the sealing frame 17 on the side away from the connecting pipe 15. A gas storage pipe 19 is connected between the two sealing gates 18 in the intake pipe 14, and a sealing plug 20 is slidably installed inside the gas storage pipe 19. A cylinder 21 is installed at the end of the gas storage pipe 19 away from the intake pipe 14, and a piston rod 22 of the cylinder 21 is drilled in the gas storage pipe 19 and fixedly connected to the sealing plug 20. An air vent 23 is formed in the side wall of one end of the gas storage pipe 19 close to the cylinder 21.

[0035] Example 1 The nano-powder production method carried out by the nano-powder production apparatus of the first embodiment is performed in accordance with the following steps S1 to S3.

[0036] In S1, the raw material nickel ingot is placed in the crucible, the arc generator is adjusted to the specified height, the vacuum pump is started, and the pressure in the evaporator is increased to 10 -4 The pressure is reduced to 0.06 Pa (A), and argon gas is introduced to restore the pressure to 0.06 MPa (A). This process is repeated three times to ensure that the air in the evaporator is replaced with argon gas, an inert gas.

[0037] In step S2, the power supply for the arc generator is turned on, generating an arc between the arc generator and the raw material, increasing the arc current to 200A, and adjusting the height of the arc generator so that the arc voltage is 40V. The nickel ingot, the main raw material, evaporates into steam due to the high temperature of the arc.

[0038] In step S3, sheath gas is introduced into the evaporator through the main sheath gas inlet, auxiliary sheath gas inlet, and arc sheath gas passage. The arc sheath gas flow rate is adjusted according to the magnitude of the arc current. In this example, the arc sheath gas flow rate is 100 cc / min. The main sheath gas flow rate is 500 SLPM, and the auxiliary sheath gas flow rate is 100 SLPM to ensure an average temperature inside the evaporator of 500 K. The main and auxiliary sheath gases are both pure argon gas, while the arc sheath gas is a mixture of argon and hydrogen gases in an 8:1 volume ratio. The arc sheath gas diffuses the metal vapor, reducing the vapor concentration around the arc high-temperature core. The blown-off metal vapor flows downward along the horizontal axis of the evaporator due to the blowing of the main and auxiliary sheath gases. During this process, the metal vapor gradually condenses to form nanometal powder, which then flows into the cooling and collection chamber with the aid of the airflow.

[0039] Example 2 The nanopowder manufacturing method performed in the nanopowder manufacturing apparatus of embodiment 1 differs from Example 1 in that the volume ratio of argon gas to hydrogen gas in the arc sheath gas is different, and in this example, the volume ratio of argon gas to hydrogen gas is 10:1.

[0040] Example 3 The nanopowder manufacturing method performed in the nanopowder manufacturing apparatus of embodiment 1 differs from Example 1 in that the volume ratio of argon gas to hydrogen gas in the arc sheath gas is different, and in this example, the volume ratio of argon gas to hydrogen gas is 9:1.

[0041] Examples 4-5 The nanopowder production method carried out in the nanopowder production apparatus of embodiment 1 differs from embodiment 1 in that the arc current, arc voltage, arc sheath gas flow rate, main sheath gas flow rate, auxiliary sheath gas flow rate, and average temperature inside the evaporator are different, as specifically shown in Table 1 below.

[0042] [Table 1]

[0043] Example 6 The nano-powder production method, which differs from that of Example 4 in that it is carried out in the nano-powder production apparatus of Example 2, is carried out in accordance with the following steps S1 to S3.

[0044] In S1, the raw material nickel ingot is placed in the crucible, the arc generator is adjusted to the specified height, the vacuum pump is started, and the pressure in the evaporator is increased to 10 -4 The pressure is reduced to 0.06 Pa (A), and argon gas is introduced to restore the pressure to 0.06 MPa (A). This process is repeated three times to ensure that the air in the evaporator is replaced with argon gas, an inert gas.

[0045] In step S2, the power supply for the arc generator is turned on, generating an arc between the arc generator and the raw material, increasing the arc current to 500A, and adjusting the height of the arc generator so that the arc voltage is 120V. The nickel ingot, the main raw material, evaporates into steam due to the high temperature of the arc.

[0046] In step S3, sheath gas is introduced into the evaporator through the main sheath gas inlet, auxiliary sheath gas inlet, and arc sheath gas passage. The arc sheath gas flow rate is adjusted according to the magnitude of the arc current. In this example, the arc sheath gas flow rate is 500 cc / min. The main sheath gas flow rate is 1600 SLPM, and the auxiliary sheath gas flow rate is 600 SLPM to ensure an average temperature inside the evaporator of 600 K. Both the main and auxiliary sheath gases are pure argon gas, while the arc sheath gas is a mixture of argon and hydrogen gases in an 8:1 volume ratio. The arc sheath gas diffuses the metal vapor, reducing the vapor concentration around the arc high-temperature core. Some of the blown-off metal vapor flows downward along the horizontal axis of the evaporator due to the blowing of the main and auxiliary sheath gases. During this process, the metal vapor gradually condenses to form nanometal powder, which then enters the cooling and collection chamber with the aid of the airflow.

[0047] While the main sheath gas is being introduced, the intake assembly is started, i.e., the cylinder is started, and the cylinder drives the sealing plug to move upward, creating negative pressure. Some of the nanopowder around the intake ring (arc high temperature core region) enters the intake ring through the intake port, and then through the connecting pipe into the intake pipe, located between the two sealing gates. When the cylinder drives the sealing plug to move downward, the sealing gate closer to the connecting pipe closes and the sealing gate farther from the connecting pipe opens. Under the action of air pressure, the nanopowder leaves the intake pipe through the sealing gate farther from the connecting pipe and enters the cooling collection chamber.

[0048] This example is implemented in the nanopowder manufacturing apparatus of embodiment 2, and by using an intake assembly in combination with a main sheath gas and an auxiliary sheath gas, the movement of nanopowder away from the arc high-temperature core region is accelerated and particle growth in the high-temperature core region of the nanopowder is reduced.

[0049] Comparative Example Comparative Example 1 The nanopowder production method performed in the nanopowder production apparatus of embodiment 1 is similar to the operation steps of Example 5, but differs from Example 5 in that in step S3, only the main sheath gas and auxiliary sheath gas are introduced into the evaporator, and no arc sheath gas is introduced.

[0050] Performance Test The yields of the nanopowder manufacturing methods of Examples 1 to 6 and Comparative Example 1 and the particle sizes of the nanopowder manufactured by the methods were measured and are specifically shown in Table 2 (Performance Test) below.

[0051] [Table 2]

[0052] As can be seen from Table 2, the particle size of the nanopowders produced by the manufacturing methods of the examples of the present application was all less than 100 nm, meeting the requirements for use of nanopowders. Examples 4-5 had much larger yields than Examples 1-3, and the particle size of the nanopowders was close to that of Examples 1-3. Examples 4-5 had yields close to that of Comparative Example 1, but the particle size of the nanopowders produced in Examples 4-5 was much smaller than that of Comparative Example 1.

[0053] The reasons for this are as follows: In the manufacturing process of Examples 4 and 5, the arc current was large, and the flow parameters of the arc sheath gas, main sheath gas, and auxiliary sheath gas were adjusted in combination to adjust and control the concentration of the metal vapor, reducing the concentration of the metal vapor and suppressing excessive collisions of metal atoms, thereby preventing the particle size of the metal powder from becoming uncontrollably large and producing nanopowder with a small particle size at a high yield. In contrast, in Comparative Example 1, the arc sheath gas was not introduced, so the concentration of the metal vapor was too high, which could lead to excessive collisions of metal atoms and further increase the particle size of the nanopowder.

[0054] The present application discloses that different sheath gas component combinations and different sheath gas flow parameters can achieve different system functions and meet the manufacturing needs of multiple types of nanopowder, including but not limited to nanocopper powder.

[0055] The specific embodiments are merely illustrative of the present application and do not limit the present application. After reading this specification, a person skilled in the art may make modifications to the present embodiment as necessary without making any creative contribution thereto, but within the scope of the claims of the present application, they will be protected by patent law. [Explanation of symbols]

[0056] 1 evaporator 2. Arc Generator 21 Arc sheath gas passage 211 Belt-shaped passage 212 Annular groove 22 Cooling water passage 3. Cooling collection chamber 4 Supply pipe 5 Outlet 6 Main sheath gas inlet 7 Auxiliary sheath gas inlet 8 Crucible stand 9 Crucible 10 Auxiliary heating induction coil 11 Water-cooled intermediate layer 12 Intake Assembly 13 Intake ring 14 Intake pipe 15 Communication pipe 16 Air intake 17 Sealing frame 18 Sealed Gate 19 Gas storage pipe 20 sealing plug 21 cylinders 22 Piston rod 23 Ventilation hole

Claims

1. A nanopowder production method carried out in a nanopowder production apparatus, comprising: The nanopowder manufacturing apparatus includes an evaporator (1), an arc generator (2), and a cooling and collecting chamber (3). The evaporator (1) is provided with a supply pipe (4) and a main sheath gas inlet (6) and an outlet (5) arranged horizontally, the outlet (5) communicating with the cooling and collecting chamber (3). The arc generator (2) is provided at the top of the evaporator (1). A crucible (9) is installed inside the evaporator (1). The arc generator (2) is installed above the crucible (9). An arc sheath gas passage (21) is formed in the arc generator (2). One end of the arc sheath gas passage (21) is connected to the inside of the evaporator (1) and the other end is connected to the outside. The nanopowder manufacturing apparatus further includes an intake assembly (12), which includes an intake ring (13) installed inside the evaporator (1), an intake pipe (14) whose exhaust end is connected to the cooling and collecting chamber (3), and a communication pipe (15) connecting the intake ring (13) and the intake pipe (14). The intake ring (13) is located above the crucible (9), and a plurality of intake ports (16) are installed in the inner ring of the intake ring (13). Two sealing frames (17) are installed inside the intake pipe (14) along the air flow direction, and each of the sealing frames (17) has a connecting pipe (15). A sealing gate (18) is hingedly connected to each of the tops of the gas intake pipes (17) on the side remote from the communicating pipe (15), and the sealing gate (18) covers the opening of the sealing frame (17). A gas storage pipe (19) is connected between the two sealing gates (18) in the intake pipe (14). A sealing plug (20) is slidably installed inside the gas storage pipe (19). A cylinder (21) is installed at the end of the gas storage pipe (19) remote from the intake pipe (14), and a piston rod (22) of the cylinder (21) is drilled into the gas storage pipe (19) and connected to the sealing plug (20). The method for producing nanopowder comprises: Step S1: placing a metal solid in a crucible (9) and replacing the air in an evaporator (1) with an inert gas; Step S2: start the power supply of the arc generator (2), adjust the arc current to 200-500A so that the arc voltage is 40-120V, and adjust the height of the arc generator (2), so that the metal solid evaporates into vapor under the high temperature action of the arc; a step S3 of introducing an arc sheath gas into the evaporator (1) at a flow rate of 100 to 500 cc / min according to the magnitude of the arc current, introducing a main sheath gas into the evaporator (1) at a flow rate of 500 to 1600 SLPM so as to ensure that the average temperature inside the evaporator (1) is 500 to 600 K, spraying vapor with the arc sheath gas and the main sheath gas to diffuse it as nanopowder, mixing the nanopowder with the main sheath gas and sending it out of the evaporator (1) through an outlet (5), thereby obtaining nanopowder with a particle size of 65 to 90 nm.

2. 2. The method for producing nanopowder according to claim 1, wherein an auxiliary sheath gas inlet (7) is further formed at the top of the evaporator (1).

3. 2. The method for producing nanopowder according to claim 1, wherein an annular groove (212) is formed at one end of the arc generator (2) located inside the evaporator (1), a strip-shaped passage (211) is formed in the arc generator (2) along its length, one end of the strip-shaped passage (211) is connected to the outside and the other end is connected to the annular groove (212), and the annular groove (212) and the strip-shaped passage (211) together form an arc sheath gas passage (21).

4. 2. The method for producing nanopowder according to claim 1, wherein the arc current is 400 to 500 A.

5. 2. The method for producing nanopowder according to claim 1, wherein the arc voltage is 100 to 120V.

6. 2. The method for producing nanopowder according to claim 1, wherein the average temperature in the evaporator (1) is 550-600K.

7. 2. The method for producing nanopowder according to claim 1, wherein the arc sheath gas is obtained by mixing argon gas and hydrogen gas in a volume ratio of (8-10):1.

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