Supersonic gas atomization powder making nozzle with double Laval structures

Abstract

The invention discloses a supersonic gas atomization powder making nozzle of a double-Laval structure, and relates to the technical field of metal powder preparation, and the supersonic gas atomization powder making nozzle comprises a gas atomization nozzle; a gas containing cavity, a connecting opening, a Laval circular seam, a plurality of Laval hole channels and a gas inlet channel are arranged in the gas atomization nozzle. A liquid guide pipe is detachably arranged in the connecting port; the Laval circular seam and the Laval hole channel are obliquely arranged, so that the extension lines of the air outlet ends of the Laval circular seam and the Laval hole channel intersect with the extension line of the center line of the connecting port at intervals; the gas inlet channel is communicated with external high-pressure gas, so that the external high-pressure gas enters the second Laval hole channel to be subjected to secondary pressure crushing after the metal solution is subjected to primary pressure crushing in the Laval circular seam and then is discharged; through the synergistic effect of the Laval circular seams and the Laval pore channels, high-pressure airflow is accelerated to form supersonic airflow to crush the metal melt twice into fine liquid drops, the contact area with the airflow is increased, the impact crushing effect of the airflow on the metal melt is better, the energy loss is effectively reduced, and the fine powder collection rate is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of metal powder preparation, and in particular to a supersonic gas atomization powder making nozzle with a double Laval structure. Background Art

[0002] Gas atomization technology is one of the most cost-effective and widely used methods for the industrial production of metal powders. Its principle is to use the kinetic energy of a supersonic gas flow to impact the molten metal in the atomization zone, atomizing the molten metal into millimeter- or even nanometer-sized droplets, which ultimately cool and solidify into powder in an atomization furnace. Compared to other powder production processes, powders produced by atomization have advantages such as small particle size, good fluidity, and high dispersibility. Therefore, this process plays a key role in the additive manufacturing industry.

[0003] As the core component of vacuum induction melting gas atomization, the atomizing nozzle's structure is directly related to the atomization efficiency and the final powder particle size. With the application of powder materials in high-end fields such as military and medical industries, improving powder properties, increasing powder sphericity, and producing powders with small particle sizes have become the development trend of the atomization process. Under the current technological background, most gas atomizing nozzles adopt a gas single-flow ring straight hole or gas single-flow ring straight seam structure. The airflow angle is single, and the contact area between the airflow and the metal melt is small, which reduces the energy utilization rate of the high-speed airflow itself, making it difficult to achieve droplet refinement during the atomization process of the metal melt. The primary and secondary crushing are insufficient, and the atomization efficiency is low. Summary of the Invention

[0004] The main purpose of the present invention is to provide a supersonic gas atomization powder making nozzle with a double Laval structure, which is used to solve the problems of the existing gas atomization nozzle, such as a single airflow angle, a small contact area between the airflow and the metal melt, which makes it difficult to achieve droplet miniaturization during the atomization process of the metal melt, and insufficient primary and secondary crushing.

[0005] To achieve the above objectives, the present invention provides a supersonic aerosol powder-making nozzle with a double-Laval structure, comprising an aerosol nozzle; an air-containing cavity is provided in the aerosol nozzle; a connecting port of the aerosol nozzle is observed on the aerosol nozzle; a Laval annular seam is provided in the aerosol nozzle, communicating with the air-containing cavity and surrounding the connecting port in a circumferential direction; a plurality of groups of Laval channels are arranged at intervals on the aerosol nozzle, communicating with the air-containing cavity and surrounding the connecting port in a circumferential direction; and air inlet channels are staggered and oppositely provided on the aerosol nozzle; A detachable liquid guide tube is provided in the connecting port; the Laval annular seam and the Laval duct are both inclined so that the extension lines of the air outlet ends of the Laval annular seam and the Laval duct intersect with the extension line of the center line of the connecting port at intervals; The air inlet channel is connected to the external high-pressure gas, so that the external high-pressure gas can pressurize and crush the metal melt once through the Laval annular gap, then enter the second Laval channel for secondary pressurization and crushing, and then be discharged.

[0006] As a further improvement of the present invention, the air accommodating cavity is arranged around the connecting port, the axis of the air accommodating cavity coincides with the axis of the connecting port, and the side wall of the air accommodating cavity parallel to the axis of the connecting port is arc-shaped.

[0007] As a further improvement of the present invention, a partition is provided between the connecting port and the air containing cavity, and the connecting port passes through the partition.

[0008] As a further improvement of the present invention, the distance from the end of the Laval annular seam connected to the air-containing cavity to the center of the connecting port is greater than the distance from the end of the Laval annular seam away from the air-containing cavity to the center of the connecting port.

[0009] As a further improvement of the present invention, the Laval annular gap includes a shrinkage ring, a throat ring, and an expansion ring that are sequentially interconnected; the ratio of the axial length of the shrinkage ring to the shrinkage ring inlet width is 1:1-3:1; the ratio of the shrinkage ring inlet width to the throat ring width is 1:1-4:1; and the ratio of the expansion ring outlet width to the throat ring width is in the range of 1:1-3:1.

[0010] As a further improvement of the present invention, the Laval channel includes a contraction section, a throat section, and an expansion section that are sequentially interconnected, and a plurality of Laval channels are arranged in circumferential intervals with the axis of the connecting port as the center of the circle.

[0011] As a further improvement of the present invention, the ratio of the throat section length to the expansion section length is 1:1-1:2; the ratio of the throat section cross-sectional area to the expansion section bottom area is 1:1-1:4.

[0012] As a further improvement of the present invention, the angle formed by the extension line of the center line of the expansion section and the central axis of the connecting port is the atomizing spray angle; and the angle range of the atomizing spray angle is 12°-34°.

[0013] A method for using a supersonic atomization powder making nozzle with a double Laval structure comprises the following steps: Step 1: Install the guide tube into the connecting port of the aerosol nozzle; Step 2: Connect the first air inlet pipe and the second air inlet pipe to external high-pressure gas cylinders respectively; Step three: Place the metal in a furnace, heat and melt it, and then pour it into the guide tube. The molten metal flows out through the small hole at the bottom of the guide tube. The outflowing molten metal is impacted and broken by the supersonic gas flow field flowing out of the Laval annular gap at the bottom of the atomizing nozzle. The supersonic gas flowing out of the Laval channel then breaks it into fine molten droplets and gradually solidifies into metal powder.

[0014] The beneficial effects of the present invention are embodied in: 1. Through the synergistic effect of the Laval annular gap and the Laval channel, the Laval annular gap will break the metal melt into smaller droplets for the first time by forming a supersonic airflow after acceleration, and the Laval channel will break the metal melt into fine droplets for the second time by forming a supersonic airflow after acceleration, providing full breakage of supersonic airflow at different angles; the aerosol nozzle can stably deliver supersonic airflow to the powder spraying area, which not only improves the stability and uniformity of the airflow, but also ensures that the airflow can maintain low energy loss during high-speed flow, thereby realizing efficient airflow utilization. By optimizing the design of the gas channel, the atomizing nozzle can more efficiently utilize the airflow energy, reduce the downtime caused by unstable airflow or energy loss, effectively extend the working time of the aerosol nozzle, and improve the reliability and stability of the equipment; the metal powder prepared by the aerosol nozzle has the advantages of fine particle size, high sphericity and good fluidity.

[0015] 2. The synergistic effect of the Laval annular gap and the Laval channel expands the range of high-speed airflow, and the area of ​​action of the airflow on the molten metal is wider. The parallel arrangement of the Laval channels effectively improves space utilization and increases the contact area with the airflow. The airflow has a better impact and crushing effect on the molten metal, effectively reducing energy loss and improving the fine powder collection rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the overall structure of a supersonic gas atomization powder making nozzle with a double Laval structure according to the present invention; Figure 2 This is a schematic cross-sectional view of a supersonic gas atomization powder making nozzle with a double Laval structure according to the present invention; Figure 3 The invention discloses a supersonic gas atomizing powder making nozzle with double Laval structure. Figure 2 A schematic diagram of the enlarged structure of the middle figure; Description of reference numerals: 1. Aerosol nozzle; 2. Air chamber; 3. Connecting port; 4. Laval annular gap; 401. Contraction ring; 402. Throat ring; 403. Expansion ring; 5. Laval channel; 501. Contraction section; 502. Throat section; 503. Expansion section; 6. Air inlet channel; 601. First air inlet pipe; 602. Second air inlet pipe; 7. Liquid guide tube; 8. Partition; 9. Atomizing spray angle. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. In the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0018] See also Figure 1 、 2 The present invention provides a supersonic aerosol powder making nozzle with a double Laval structure, comprising an aerosol nozzle 1, an air accommodating cavity 2 provided in the aerosol nozzle 1, a connecting port 3 of the aerosol nozzle 1 being observed on the aerosol nozzle 1, a Laval annular seam 4 communicating with the air accommodating cavity 2 and surrounding the connecting port 3 in a circumferential direction, a plurality of Laval channels 5 communicating with the air accommodating cavity 2 and surrounding the connecting port 3 in a circumferential direction are arranged at intervals on the aerosol nozzle 1, an air inlet channel 6 is staggered and oppositely provided on the aerosol nozzle 1, a liquid guide tube 7 is detachably provided in the connecting port 3, the Laval annular seam 4 and the Laval channel 5 are inclinedly arranged so that the extension lines of the air outlet ends of the Laval annular seam 4 and the Laval channel 5 intersect with the extension line of the center line of the connecting port 3 at intervals; the air inlet channel 6 is connected to the external high-pressure gas so that the external high-pressure gas pressurizes and crushes the metal melt once in the Laval annular seam 4 and then enters the Laval channel 5 for secondary pressurization and crushing before being discharged.

[0019] After the airflow ejected from the common atomizing nozzle 1 contacts the metal melt, the high-speed airflow has a single ejection angle and a short contact time with the metal melt, and the contact area between the high-speed airflow and the metal melt is small. It is difficult to perform a secondary crushing on the already crushed metal melt after the metal melt is crushed once, resulting in a larger particle size of the metal melt after atomization, low utilization rate of the high-speed airflow, low atomization efficiency, and insufficient crushing.

[0020] In this embodiment, the aerosol nozzle 1 is a disc-shaped structure, and the connecting port 3 is located at the center of the top of the aerosol nozzle 1, which is used to plug in the liquid guide tube 7. The upper part of the liquid guide tube 7 is a cylindrical tube and the lower part is a conical tube. The upper part of the interior of the connecting port 3 is cylindrical and the lower part is conical. After the liquid guide tube 7 is inserted into the connecting port 3, the liquid guide tube 7 can be limited.

[0021] Preferably, the connection port 3 has a diameter of 18 mm and is used to place the guide tube, and the diameter of the conical tube is 3-5 mm.

[0022] In this embodiment, the air chamber 2 is arranged around the connecting port 3, the axis of the air chamber 2 coincides with the axis of the connecting port 3, and the staggered air inlet channels 6 flow along the air chamber 2 to avoid high-speed airflow convection collision and energy consumption caused by high-speed airflow.

[0023] In this embodiment, a high-speed airflow enters the air-containing cavity 2 through the air inlet channel 6, and part of the high-speed airflow is accelerated by the Laval annular gap 4 to form a supersonic airflow. The supersonic airflow of the metal melt falling from the liquid guide tube 7 is broken up once, and then broken up again by the supersonic airflow formed after being accelerated by the Laval channel 5.

[0024] In summary, the supersonic aerosolizing powder making nozzle with a double Laval structure in the above embodiment is connected with the air inlet channel 6 through an external high-pressure air pump during the aerosolizing process of the metal melt, and the high-speed gas is introduced into the air chamber 2. The staggered air inlet channels 6 ensure the supply of high-speed gas while avoiding the mutual impact and energy consumption of high-speed gas. The high-speed airflow in the air chamber 2 is discharged in two paths. One path is discharged from the Laval annular seam 4. The Laval annular seam 4 pressurizes the high-speed airflow to form a supersonic airflow to crush the metal melt dripping in the liquid guide tube 7; the other path is discharged from the Laval channel 5. The Laval channel 5 pressurizes the high-speed airflow to form a supersonic airflow to crush the metal melt dripping in the liquid guide tube 7; The metal melt that has been crushed by the airflow removed by the Laval annular gap 4 is subjected to secondary crushing, and high-speed airflows at different angles are provided to fully crush the metal melt, thereby realizing the miniaturization of the metal melt; since the airflow channel of the Laval structure has excellent fluid mechanics properties, it can quickly accelerate the gas to a supersonic state. The Laval annular gap 4 and the Laval channel 5 work together to stably deliver supersonic airflow to the powder spraying area, which not only improves the stability and uniformity of the airflow, but also ensures that the airflow can maintain low energy loss during high-speed flow, thereby realizing efficient airflow utilization; the atomizing nozzle can utilize airflow energy more efficiently, reducing downtime caused by airflow instability or energy loss.

[0025] Therefore, the Laval annular gap 4 and the Laval channel 5 perform a secondary pressure crushing on the metal melt after the primary pressure crushing, thereby increasing the contact time and contact area between the high-speed airflow and the metal melt. Under the coordinated crushing impact of the Laval annular gap 4 and the Laval channel 5, the shortcomings of large gas velocity attenuation, excessively high operating temperature, and large energy loss are effectively solved, the particle size distribution of the metal powder is narrowed, the fine powder collection rate is improved, and the particle size and performance requirements of the additive manufacturing technology for the metal powder particles are met.

[0026] Based on the above embodiments, see Figure 2 A partition 8 is provided between the connecting port 3 and the air-containing cavity 2. The connecting port 3 passes through the partition 8. The air-containing cavity 2 is located in the circumferential direction of the partition 8. The side wall of the air-containing cavity 2 parallel to the axis of the connecting port 3 is arc-shaped. After the high-speed airflow enters the air-containing cavity 2, the arc-shaped inner wall of the air-containing cavity 2 can buffer and guide the high-speed airflow and reduce the loss. The partition 8 separates the Laval annular seam 4 from the connecting port 3, so that the high-speed airflow in the air-containing cavity 2 is discharged along the Laval annular seam 4 and the Laval channel 5.

[0027] Preferably, the air inlet channel 6 includes a first air inlet pipe 601 and a second air inlet pipe 602 arranged opposite to each other at both ends of the aerosol nozzle 1, and there is a distance between the axis of the first air inlet pipe 601, the second air inlet pipe 602 and the axis of the connecting port 3, so that the two groups of air inlet channels 6 are staggered.

[0028] Preferably, the arc radius of the air-containing cavity 2 is 40 mm to 50 mm, and the remaining wall surfaces are designed as straight lines.

[0029] Based on the above embodiments, see Figure 2 、 3 The distance from the end of the Laval annular seam 4 connected to the air chamber 2 to the center of the connecting port 3 is greater than the distance from the end of the Laval annular seam 4 away from the air chamber 2 to the center of the connecting port 3, so that the Laval annular seam 4 is inclined and its extension line intersects with the extension line of the axis of the connecting port 3.

[0030] Preferably, the Laval annular gap 4 has a conical or funnel-shaped outer structure, so that the high-speed airflow in the air chamber 2 can be squeezed and converged toward the axial direction of the connecting port 3, so that the high-speed airflow collides with the dripping metal melt and breaks it into fine molten droplets.

[0031] For further information, see Figure 3The Laval annular gap 4 includes a shrinking ring 401, a throat ring 402, and an expansion ring 403 that are interconnected in sequence. The ratio of the axial length of the shrinking ring 401 to the inlet width of the shrinking ring 401 is 1:1-3:1, the ratio of the inlet width of the shrinking ring 401 to the width of the throat ring 402 is 1:1-4:1, and the ratio of the outlet width of the expansion ring 403 to the width of the throat ring 402 is in the range of 1:1-3:1; the shrinking ring 401 is designed using the quintic curve method, the width of the throat ring 402 is 1-3 mm, and the expansion ring 403 is designed using the Fuchs method. The ratio of the width of the expansion ring 403 to the width of the throat ring 402 is determined by the Mach number Ma designed in the production plan. According to the principles of aerodynamics, the air flow velocity at the air inlet can reach supersonic speed, which can cause a single impact and crush the metal melt.

[0032] In one embodiment, based on the above embodiment, see Figure 3 The Laval channel 5 includes a contraction section 501, a throat section 502, and an expansion section 503 that are sequentially connected to each other. The Laval channel 5 is arranged in multiple groups at intervals along the circumferential direction with the axis of the connecting port 3 as the center of the circle.

[0033] Preferably, the number of Laval channels 5 is 15-25 to avoid the air channel gap from being too large and causing missing space when the air is blown out from the Laval channels 5, while controlling the total outlet area of ​​the air channel to ensure the air flow velocity. The supersonic gas blown out from multiple groups of Laval channels 5 surrounds the axis of the connecting port 3 and hits the metal melt from different directions, thereby improving the refinement efficiency of the metal melt.

[0034] Furthermore, the ratio of the length of the throat section 502 to the length of the expansion section 503 is 1:1-1:2; the ratio of the cross-sectional area of ​​the throat section 502 to the bottom area of ​​the expansion section 503 is 1:1-1:4. The throat section 502 has a prismatic structure, and the expansion section 503 has a pyramidal structure. According to the principles of aerodynamics, the air flow velocity at the air inlet can reach supersonic speed, which can cause secondary impact on the metal melt to break it into fine molten droplets and gradually solidify into metal powder.

[0035] Furthermore, the angle formed by the extension line of the center line of the expansion section 503 and the central axis of the connecting port 3 is the atomizing spray angle 9. The angle range of the atomizing spray angle 9 is 12°-34°, which can expand the range of high-speed airflow, and the area of ​​action of the gas on the metal solution is wider. The uniform arrangement of the gas channels effectively improves the space utilization rate, improves the limitations of the single airflow nozzle, and improves the atomization efficiency.

[0036] In one embodiment, based on the above embodiment, see Figure 1-Figure 3 The present invention provides a method for producing a supersonic aerosol powder making nozzle with a double Laval structure, comprising the following steps: Step 1: Install the guide tube into the connecting port 3 of the aerosol nozzle 1; Step 2: Connect the first air inlet pipe 601 and the second air inlet pipe 602 to the external high-pressure gas cylinder respectively; Step 3: Place the metal in a furnace, heat it, and melt it, then pour it into the guide tube. The molten metal flows out through the small hole at the bottom of the guide tube. The molten metal is impacted and broken by the supersonic gas flow field flowing out of the Laval annular gap 4 at the bottom of the atomizing nozzle 1. The supersonic gas flowing out of the Laval channel 5 then breaks it into fine molten droplets and gradually solidifies into metal powder.

[0037] In the implementation of the present invention, the angle between the airflow jet and the axis is 30°, the diameter Φ of the guide tube installation port is 18mm, the inner diameter of the guide tube is 3-5mm, the raw material is high-purity copper, the smelting temperature is 1400°C, the atomizing gas is nitrogen, and the atomizing pressure is 3MPa. After atomization, the prepared powder is screened using standard analytical methods to determine the powder particle size. The proportion of high-purity copper powder with a particle size less than 150μm is 78%, the proportion of powder particles with a diameter below 50μm is 30%, and the average particle size D50 of the powder is 48μm. This double-Laval structure supersonic gas atomization powder production nozzle is suitable for atomizing all metal and alloy melts with a melting point below 1600°C. This feature makes the atomizer widely applicable in the field of metal powder preparation and can meet the atomization requirements of different metal materials.

[0038] In the present invention, the working principle is as follows: (1) After the raw material high-purity copper block is melted into a high-temperature liquid in a vacuum furnace, the high-temperature liquid is poured into the guide tube using a pouring device, and the high-temperature fluid flows out to form a high-temperature liquid flow; (2) The guide tube is placed in the connecting port 3 in the middle of the atomizing nozzle 1, and applies an atomizing airflow to the high-temperature liquid flow, so that the atomizing airflow flushes the high-temperature liquid flow, and the high-temperature liquid is atomized to form droplets; (3) A Laval annular gap 4 is provided in the atomizing nozzle to form a high-speed airflow, which carries the droplets and causes the air film wrapped around the surface of the droplets to rupture; (4) Multiple Laval channels 5 in the form of Laval pipes are provided outside the annular gap 4 of the atomizing nozzle to form a high-speed asymmetric airflow. Through the multi-directional airflow, the metal liquid flow is more evenly broken up, which can significantly reduce the particle size range of the powder; (5) The droplets are cooled in a high-speed asymmetric airflow to form spherical powders.

[0039] In summary, the present invention provides two sets of air jets in the aerosol nozzle 1. Under the coordinated crushing impact of the Laval channel 5 and the Laval annular gap 4, the shortcomings of large gas velocity attenuation, excessively high operating temperature, and large energy loss are effectively solved, the particle size distribution of the metal powder is narrowed, the fine powder collection rate is improved, and the particle size and performance requirements of the additive manufacturing technology for the metal powder particles are met.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A supersonic gas atomization powder making nozzle with a double Laval structure, characterized by: The invention comprises an aerosol nozzle (1); an air-containing cavity (2) is provided in the aerosol nozzle (1); a connecting port (3) of the aerosol nozzle (1) is observed on the aerosol nozzle (1); a Laval annular seam (4) is provided in the aerosol nozzle (1) and is communicated with the air-containing cavity (2) and surrounds the connecting port (3) in a circumferential direction; a plurality of Laval ducts (5) are arranged at intervals on the aerosol nozzle (1) and are communicated with the air-containing cavity (2) and surround the connecting port (3) in a circumferential direction; and air inlet channels (6) are staggered and oppositely provided on the aerosol nozzle (1); A detachable liquid guide tube (7) is provided in the connecting port (3); the Laval annular seam (4) and the Laval duct (5) are both arranged at an angle so that the extension lines of the air outlet ends of the Laval annular seam (4) and the Laval duct (5) intersect with the extension lines of the center line of the connecting port (3) at intervals; The air inlet channel (6) is connected to the external high-pressure gas, so that the external high-pressure gas can pressurize and crush the metal melt once through the Laval annular gap (4) and then enter the second Laval channel (5) for secondary pressurization and crushing before being discharged.

2. The supersonic gas atomization powder making nozzle with a double Laval structure according to claim 1, characterized in that: The air accommodating cavity (2) is arranged around the connecting port (3), the axis of the air accommodating cavity (2) coincides with the axis of the connecting port (3), and the side wall of the air accommodating cavity (2) parallel to the axis of the connecting port (3) is in an arc shape.

3. The supersonic gas atomization powder making nozzle with a double Laval structure according to claim 2, characterized in that: A partition (8) is provided between the connecting port (3) and the air-containing cavity (2), and the connecting port (3) passes through the partition (8).

4. The supersonic gas atomization powder making nozzle with a double Laval structure according to claim 3, characterized in that: The distance from the end of the Laval annular seam (4) communicating with the air-containing cavity (2) to the center of the connecting port (3) is greater than the distance from the end of the Laval annular seam (4) away from the air-containing cavity (2) to the center of the connecting port (3).

5. The supersonic gas atomization powder making nozzle with a double Laval structure according to claim 4, characterized in that: The Laval annular gap (4) comprises a shrinking ring (401), a throat ring (402), and an expansion ring (403) which are sequentially connected to each other; the ratio of the axial length of the shrinking ring (401) to the inlet width of the shrinking ring (401) is 1:1-3:1; the ratio of the inlet width of the shrinking ring (401) to the width of the throat ring (402) is 1:1-4:1; and the ratio of the outlet width of the expansion ring (403) to the width of the throat ring (402) is in the range of 1:1-3:

1.

6. The supersonic gas atomization powder making nozzle with a double Laval structure according to claim 5, characterized in that: The Laval channel (5) comprises a contraction section (501), a throat section (502), and an expansion section (503) which are sequentially connected to each other. The Laval channel (5) is arranged in multiple groups at intervals along the circumferential direction with the axis of the connecting port (3) as the center of the circle.

7. The supersonic gas atomization powder making nozzle with a double Laval structure according to claim 6, characterized in that: The ratio of the length of the throat section (502) to the length of the expansion section (503) is 1:1-1:2; and the ratio of the cross-sectional area of ​​the throat section (502) to the bottom area of ​​the expansion section (503) is 1:1-1:

4.

8. The supersonic gas atomization powder making nozzle with a double Laval structure according to claim 7, characterized in that: The angle formed by the extension line of the center line of the expansion section (503) and the center axis of the connection port (3) is the atomization spray angle (9); the angle range of the atomization spray angle (9) is 12°-34°.

9. A method for using a double-Laval supersonic atomization powder making nozzle according to any one of claims 1 to 8, comprising the following steps: Step 1: Install the guide tube into the connecting port (3) of the aerosol nozzle (1); Step 2: Connect the first air inlet pipe (601) and the second air inlet pipe (602) to external high-pressure gas cylinders respectively; Step three, placing the metal in a furnace, heating and melting it, and then pouring it into the guide tube. The molten metal flows out along the small hole at the bottom of the guide tube. The molten metal is impacted and broken by the supersonic gas flow field flowing out from the Laval annular gap (4) at the bottom of the aerosol nozzle (1). The supersonic gas flowing out of the Laval channel (5) then breaks it into fine molten droplets and gradually solidifies into metal powder.

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