A gas-gas combined atomizing device for metal atomization

Abstract

The invention discloses a gas-gas combined atomizing device for metal atomization, comprising: a central nozzle for spraying out metal liquid; an air supply device for providing gas that does not react with air and metal liquid; a primary atomizer, which is arranged in a ring shape surrounding the central nozzle, and comprises a primary annular air intake device and a primary annular nozzle which are connected in sequence, the primary annular air intake device is connected to the air supply device, the primary annular nozzle is arranged at the bottom of the inner ring of the primary annular air intake device, and its spraying direction is arranged toward the outlet of the central nozzle, the gas sprayed from the primary annular nozzle collides with the metal liquid sprayed from the central nozzle, and an umbrella-shaped reflow zone is formed on the inner side of the collision area; a secondary atomizer, which is arranged at the bottom of the primary atomizer, and comprises a secondary air intake device and a secondary nozzle which are connected in sequence, the secondary air intake device is connected to the air supply device, the secondary nozzle is arranged at the bottom of the inner side of the secondary air intake device, and its spraying direction is arranged toward the umbrella-shaped reflow zone.

Description

Technical Field

[0001] The invention relates to the field of metal gas atomization, in particular to a gas-gas combined atomization device for metal atomization. Background Art

[0002] In the gas atomization powder making industry, close-coupled gas atomization is one of the most widely used powder making applications, mainly because the close-coupled gas atomization flow field has a unique and complex umbrella-shaped reflow zone, which is conducive to the film formation and initial crushing of the melt, thereby improving the atomization efficiency. However, due to the existence of the reflow zone, the solidified small spherical metal particles collide violently with the unsolidified large spherical particles, causing the small spherical metal particles to remelt and adhere to the surface of the large sphere to form satellite spheres; and due to the complex particle collision, the surface of the powder particles is not smooth, which greatly reduces the powder fluidity. In order to reduce costs and improve timeliness, most powder making industries mainly use non-vacuum atomization when processing metals in the atomization chamber. Due to the high-temperature metal solution in the non-vacuum gas atomization, the oxygen in the atomization process is easy to diffuse into the metal powder, which significantly increases the oxygen content of the metal alloy powder. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a gas-gas combined atomization device for metal atomization, which can reduce the reflux effect and increase the cooling rate during the atomization process, thereby reducing the collision of powder particles and the generation of satellite balls, and at the same time can reduce the oxygen content in the atomization chamber and improve the quality of metal powder.

[0004] The technical solution adopted in the embodiment of the present invention is: a gas-gas combined atomizing device for metal atomization, comprising: a central nozzle for spraying metal liquid; a gas supply device for providing gas that does not react with air and the metal liquid; a primary atomizer, the primary atomizer is arranged in a ring shape surrounding the central nozzle, the primary atomizer comprises a primary annular air inlet device and a primary annular nozzle connected in sequence, the primary annular air inlet device is connected to the gas supply device, and the primary annular nozzle is arranged at the bottom of the inner ring of the primary annular air inlet device , and its injection direction is set toward the outlet of the central nozzle, the gas ejected from the primary annular nozzle collides with the metal liquid ejected from the central nozzle, and an umbrella-shaped reflow zone is formed on the inner side of the collision area; a secondary atomizer, the secondary atomizer is arranged at the bottom of the primary atomizer, the secondary atomizer comprises a secondary air intake device and a secondary nozzle connected in sequence, the secondary air intake device is connected to the air supply device, the secondary nozzle is arranged at the bottom of the inner side of the secondary air intake device, and its injection direction is set toward the umbrella-shaped reflow zone.

[0005] The gas-gas combined atomizing device for metal atomization according to the embodiment of the present invention has at least the following beneficial effects:

[0006] 1. Before the metal alloy gas atomization process, a gas that does not react with air and metal liquid is introduced into the tightly coupled atomizing nozzle, and the air in the atomizing chamber is discharged through the secondary nozzle to reduce the oxygen content in the atomizing chamber, thereby improving the performance of the metal powder;

[0007] 2. The secondary nozzle impacts the umbrella-shaped reflow zone to change the gas flow direction in the umbrella-shaped reflow zone, thereby reducing the reflow effect during the atomization process and increasing the cooling rate, thereby reducing the collision of powder particles and the generation of satellite balls, thereby improving the performance of metal powders;

[0008] 3. When the secondary nozzle impacts the umbrella-shaped reflow zone, part of the airflow will impact the metal liquid along with the gas from the primary annular nozzle to improve the atomization efficiency;

[0009] 4. Adding a secondary atomizer on the basis of the existing atomizer makes the transformation simpler and low-cost.

[0010] According to some embodiments of the present invention, the first-level annular air intake device includes a first-level air intake pipe and a first-level annular air cavity connected in sequence, the first-level annular nozzle, the first-level air intake pipe is connected to the air supply device, the first-level annular nozzle is arranged at the bottom of the inner ring of the first-level annular air cavity, and its injection direction is arranged toward the central nozzle.

[0011] According to some embodiments of the present invention, the secondary atomizer includes a secondary air intake device and a secondary nozzle connected in sequence, the secondary air intake device includes a secondary air intake pipe and a secondary air cavity connected in sequence, the secondary air intake pipe is connected to the air supply device, the secondary nozzle is arranged at the bottom of the inner side of the secondary air cavity, and its injection direction is arranged toward the umbrella-shaped reflow zone.

[0012] According to some embodiments of the present invention, the first-stage annular nozzle is an annular Laval nozzle, and the Laval nozzle includes a contraction section and an expansion section, wherein the contraction section is used to accelerate the ejected gas to the speed of sound, and the expansion section is used to accelerate the gas reaching the speed of sound to supersonic speed.

[0013] According to some embodiments of the present invention, a throat is between the contraction section and the expansion section, and a diameter of the throat is in the range of 0.4 mm-1 mm.

[0014] According to some embodiments of the present invention, the contraction section forms a contraction angle with the vertical direction, and the contraction angle ranges from 3° to 7°.

[0015] According to some embodiments of the present invention, an expansion angle is formed between the expansion section and the contraction section, and the angle range of the expansion angle is 8°-12°.

[0016] According to some embodiments of the present invention, a first stabilization section is provided before the contraction section to stabilize the gas.

[0017] According to some embodiments of the present invention, a second stabilization section is provided after the expansion section to stabilize the gas.

[0018] According to some embodiments of the present invention, an extension line of the center line of the primary annular nozzle and an extension line of the center line of the central nozzle form a first angle α, and the range of the angle α is 20°-45°.

[0019] According to some embodiments of the present invention, an extension line of the center line of the secondary nozzle and an extension line of the center line of the central nozzle form a second angle β, and the range of the second angle β is 50°-75°.

[0020] According to some embodiments of the present invention, the secondary nozzle is an annular nozzle, and the nozzle diameter of the annular nozzle is 6-12 mm.

[0021] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0023] Figure 1 Schematic diagram of a gas-gas combined atomization device for metal atomization according to an embodiment of the present invention;

[0024] Figure 2 It is a cross-sectional schematic diagram of a gas-gas combined atomization device for metal atomization according to an embodiment of the present invention;

[0025] Figure 3 for Figure 2 A magnified schematic diagram of part A;

[0026] Figure 4 This is a powder morphology diagram obtained by an existing atomization device;

[0027] Figure 5 This is the powder morphology obtained in the present invention.

[0028] Reference numerals:

[0029] 100-center nozzle;

[0030] 200-first-stage atomizer; 210-first-stage air inlet device; 211-first-stage air inlet pipe; 212-first-stage annular air cavity; 220-first-stage annular nozzle; 221-contraction section; 222-expansion section; 223-first stable section; 224-second stable section;

[0031] 300-secondary atomizer; 310-secondary air intake device; 311-secondary air intake pipe; 312-secondary air cavity; 320-secondary nozzle;

[0032] γ-contraction angle; δ-expansion angle; α-first angle; β-second angle. DETAILED DESCRIPTION

[0033] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0034] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0035] In the description of the present invention, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood as not including the number itself, and "above", "below", "within" etc. are understood as including the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0036] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0037] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0038] Reference Figure 1 and Figure 2In some specific embodiments of the present invention, a gas-gas combined atomization device for metal atomization comprises:

[0039] A central nozzle 100 for spraying liquid metal;

[0040] Gas supply device to provide gas that does not react with air and metal liquid;

[0041] The primary atomizer 200 is arranged in an annular shape surrounding the central nozzle 100. The primary atomizer 200 includes a primary annular air inlet device 210 and a primary annular nozzle 220 which are connected in sequence. The primary annular air inlet device 210 is connected to the air supply device. The primary annular nozzle 220 is arranged at the bottom of the inner ring of the primary annular air inlet device 210, and its spraying direction is arranged toward the outlet of the central nozzle 100. The gas sprayed from the primary annular nozzle 220 collides with the metal liquid sprayed from the central nozzle 100, and an umbrella-shaped reflow zone is formed inside the collision area;

[0042] The secondary atomizer 300 is arranged at the bottom of the primary atomizer 200. The secondary atomizer 300 includes a secondary air intake device 310 and a secondary nozzle 320 which are connected in sequence. The secondary air intake device 310 is connected to the air supply device. The secondary nozzle 320 is arranged at the bottom of the inner side of the secondary air intake device 310, and its spraying direction is arranged toward the umbrella-shaped reflow zone.

[0043] Specifically, the implementation process is as follows:

[0044] The process flow of metal powder. In this embodiment, the gas that does not react with air and metal liquid is nitrogen. In addition to nitrogen, inert gases such as argon can also be used. Before the metal alloy gas atomization process, nitrogen is introduced into the tightly coupled atomizing nozzle, and the nitrogen enters the atomization chamber from the central nozzle 100, and the air in the atomization chamber is discharged through the secondary nozzle 320. After the air is exhausted, the secondary atomizer 300 is connected to the air supply device, and nitrogen with a lower pressure is introduced into the secondary atomizer 300, and nitrogen with a specified pressure is introduced into the primary atomizer 200, so that the nitrogen maintains a high speed and is ejected from the primary annular nozzle 220. The central nozzle 100 begins to drop metal liquid, which is broken up by the gas ejected from the primary annular nozzle 220 to form metal powder.

[0045] Before the metal powder is added to the secondary atomizer 300, during the process of the metal liquid being atomized by the gas ejected from the primary annular nozzle 220, the ejected gas will generate a backflow near the collision area, forming a unique umbrella-shaped backflow zone on the inner side of the collision area. In the umbrella-shaped backflow zone, the solidified small spherical metal particles and the unsolidified large spherical particles violently collide with each other, causing the small spherical metal particles to remelt and adhere to the surface of the large sphere to form satellite spheres. At the same time, due to the complex particle collisions, the surface of the powder particles is not smooth, thereby reducing the performance of the metal powder.

[0046] After the secondary atomizer 300 is added, the gas sprayed from the secondary atomizer 300 is aimed at the umbrella-shaped recirculation zone, disrupting the original airflow in the umbrella-shaped recirculation zone and making it impossible for the umbrella-shaped recirculation zone to form. At the same time, part of the gas sprayed from the secondary atomizer 300 will impact the metal liquid along with the gas from the primary annular nozzle 220, increasing the gas flow rate, thereby increasing the speed of metal atomization and improving the efficiency of atomization. Adding the secondary atomizer 300 to the existing atomizer makes the modification simpler and the cost lower.

[0047] Before the metal alloy gas atomization process, a gas that does not react with air and metal liquid is introduced into the tightly coupled atomizing nozzle, and the air in the atomization chamber is discharged through the secondary nozzle 320 to reduce the oxygen content in the atomization chamber, thereby improving the performance of the metal powder; the secondary nozzle 320 impacts the umbrella-shaped reflow zone to change the gas flow direction in the umbrella-shaped reflow zone, thereby reducing the reflow efficiency during the atomization process and increasing the cooling rate, thereby reducing the collision of powder particles and the generation of satellite balls, thereby improving the performance of the metal powder; when the secondary nozzle 320 impacts the umbrella-shaped reflow zone, part of the airflow will impact the metal liquid along with the gas of the primary annular nozzle 220 to improve the atomization efficiency.

[0048] Reference Figure 1 and Figure 2 In some specific embodiments of the present invention, the first-stage annular air intake device 210 includes a first-stage air intake pipe 211 and a first-stage annular air cavity 212 which are connected in sequence, the first-stage air intake pipe 211 is connected to the air supply device, and the first-stage annular nozzle 220 is arranged at the bottom of the inner ring of the first-stage annular air cavity 212, and its injection direction is set toward the central nozzle.

[0049] Reference Figure 1 and Figure 2 In some specific embodiments of the present invention, the secondary atomizer 300 includes a secondary air intake device 310 and a secondary nozzle 320 connected in sequence, the secondary air intake device 310 includes a secondary air intake pipe 311 and a secondary air cavity 312 connected in sequence, the secondary air intake pipe 311 is connected to the air supply device, and the secondary nozzle 320 is arranged at the bottom of the inner side of the secondary air cavity 312, and its injection direction is set toward the umbrella-shaped reflow zone.

[0050] Reference Figure 3 In some specific embodiments of the present invention, the first-stage annular nozzle 220 is an annular Laval nozzle, which includes a contraction section 221 and an expansion section 222. The contraction section 221 is used to accelerate the ejected gas to the speed of sound, and the expansion section 222 is used to accelerate the gas reaching the speed of sound to supersonic speed.

[0051] Specifically, the gas is accelerated by the Laval tube so that the gas velocity ejected from the first-stage annular nozzle 220 can reach supersonic speed. The supersonic atomized metal has high atomization efficiency, fine powder particle size, and narrow particle size distribution. The powder itself has a high condensation rate, and the smaller the powder particle size, the faster the powder condensation rate. At the same time, the supersonic airflow also has a better condensation rate for the powder, reducing the probability of the powder sphericity being reduced due to collision, adhesion, deformation, etc.

[0052] Under normal working conditions, the airflow is subsonic when passing through the contraction section 221, reaches sonic speed when passing through the throat, and becomes supersonic when entering the expansion section 222 until the exit. According to the differential expression of the mass continuity equation of the airflow unit in the Laval tube: ρuA=(ρ+dρ)(u+du)(A+dA) is a constant, where ρ is density, u is fluid velocity, and A is cross-sectional area; according to the relationship between airflow velocity and flow channel cross-sectional area, there is a formula: where M is the Mach number of the airflow. It can be seen from the formula that when the subsonic flow is M<1, if du>0, then dA<0; if du<0, then dA>0. The above shows that when the subsonic airflow accelerates along the streamline of the Laval tube, the cross-sectional area of ​​the fluid must gradually decrease; when the supersonic flow is M>1, if du>0, then dA>0; if du<0, then dA<0. The above shows that when the supersonic airflow accelerates along the streamline of the Laval tube, the cross-sectional area of ​​the fluid must increase slowly, so the supersonic flow is exactly the opposite of the subsonic flow. In summary, the best effect is when the Mach number M of the airflow at the throat is 1.

[0053] Reference Figure 3 In some specific embodiments of the present invention, a throat is located between the contraction section 221 and the expansion section 222, and the diameter of the throat is in the range of 0.4 mm-1 mm.

[0054] Reference Figure 3 In some specific embodiments of the present invention, the contraction section 221 forms a contraction angle γ with the vertical direction, and the contraction angle γ ranges from 3° to 7°.

[0055] Reference Figure 3 In some specific embodiments of the present invention, an expansion angle δ is formed between the expansion section 222 and the contraction section 221, and the angle range of the expansion angle δ is 8°-12°.

[0056] Specifically, the powder particle size can be made to reach 10-20 μm.

[0057] Reference Figure 3 In some specific embodiments of the present invention, a first stabilizing section 223 is provided before the contraction section 221 to stabilize the gas. The gas in the Laval tube will have a large turbulence when entering the tube, and the first stabilizing section 223 can reduce the turbulence and make the flow rate of the ejected gas higher.

[0058] Reference Figure 3 In some specific embodiments of the present invention, a second stabilizing section 224 is provided after the expansion section 222 to stabilize the gas. The gas in the Laval tube will also have turbulence during the ejection stage, and the second stabilizing section 224 can reduce the turbulence and make the ejected gas flow faster.

[0059] Reference Figure 3 In some specific embodiments of the present invention, an extension line of the center line of the primary annular nozzle 220 and an extension line of the center line of the central nozzle 100 form a first angle α, and the range of the first angle α is 20°-45°.

[0060] Reference Figure 3 In some specific embodiments of the present invention, an extension line of the center line of the secondary nozzle 320 and an extension line of the center line of the central nozzle 100 form a second angle β, and the range of the second angle β is 50°-75°.

[0061] Reference Figure 3 In some specific embodiments of the present invention, the secondary nozzle 320 is an annular nozzle, and the nozzle diameter of the annular nozzle is 6-12 mm.

[0062] The comparative test data of the present invention and the existing atomization device are provided:

[0063] In this example, FeCoNi alloy solution is sprayed from an atomizing device at a temperature of 1550° C. The inner diameter of the guide nozzle is 4.8 mm, the atomizing gas is nitrogen, and the atomizing pressure is 5.5 MPa.

[0064] The powder morphology obtained by the existing atomization device is as follows Figure 4 As shown;

[0065] The powder morphology obtained by the present invention is as follows Figure 5 As shown;

[0066] By comparison, it can be seen that, compared with the powder produced by the ordinary atomizing device, the powder produced by the atomizing device of the present invention has a smooth surface and greatly reduced satellite balls, thereby greatly improving the powder performance.

[0067] Of course, the present invention is not limited to the above-mentioned embodiments, and those skilled in the art may make equivalent modifications or substitutions without violating the spirit of the present invention, and these equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A gas-gas combined atomizing device for metal atomization, characterized in that: include: A central nozzle (100) for spraying liquid metal; A gas supply device for providing gas that does not react with air and the metal liquid; A primary atomizer (200), the primary atomizer (200) being arranged in an annular shape surrounding the central nozzle (100), the primary atomizer (200) comprising a primary annular air intake device (210) and a primary annular nozzle (220) which are connected in sequence, the primary annular air intake device (210) being connected to the air supply device, the primary annular nozzle (220) being arranged at the bottom of the inner ring of the primary annular air intake device (210), and its spraying direction being arranged toward the outlet of the central nozzle (100), the gas sprayed from the primary annular nozzle (220) collides with the metal liquid sprayed from the central nozzle (100), and an umbrella-shaped reflow zone is formed inside the collision zone; A two-stage atomizer (300), the two-stage atomizer (300) being arranged at the bottom of the one-stage atomizer (200), the two-stage atomizer (300) comprising a two-stage air intake device (310) and a two-stage nozzle (320) which are connected in sequence, the two-stage air intake device (310) being connected to the air supply device, the two-stage nozzle (320) being arranged at the bottom of the inner side of the two-stage air intake device (310), and the spraying direction of the two-stage nozzle is arranged toward the umbrella-shaped reflow zone; The first-stage annular nozzle (220) is an annular Laval nozzle, the Laval nozzle comprising a contraction section (221) and an expansion section (222), the contraction section (221) is used to accelerate the ejected gas with a certain initial velocity to the speed of sound, and the expansion section (222) is used to accelerate the gas reaching the speed of sound to the supersonic speed; A throat is formed between the contraction section (221) and the expansion section (222), and the diameter of the throat is in the range of 0.4 mm to 1 mm; The contraction section (221) forms a contraction angle γ with the vertical direction, and the contraction angle γ is in the range of 3°-7°; An expansion angle δ is formed between the expansion section (222) and the contraction section (221), and the angle range of the expansion angle δ is 8°-12°; A first stabilizing section (223) is provided before the contraction section (221) to stabilize the gas; A second stabilization section (224) is provided after the expansion section (222) to stabilize the gas; An extension line of the center line of the primary annular nozzle (220) and an extension line of the center line of the central nozzle (100) form a first angle α, and the range of the first angle α is 20°-45°; An extension line of the center line of the secondary nozzle (320) and an extension line of the center line of the central nozzle (100) form a second angle β, and the range of the second angle β is 50°-75°.

2. The gas-gas combined atomizing device for metal atomization according to claim 1, characterized in that: The secondary nozzle (320) is an annular nozzle, and the nozzle diameter of the annular nozzle is 6-12 mm.

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