Gas atomization device for metal powder preparation

Abstract

The invention discloses a gas atomization device for metal powder preparation, and belongs to the technical field of metal powder preparation. The device comprises a leakage bag, a flow guide pipe, a main atomization spraying disc, an auxiliary atomization spraying disc and a cylindrical baffle. The upper end of the flow guide pipe is connected with a bottom outlet of the leakage bag, the flow guide pipe is sleeved with the main atomization spraying disc which is connected to the center of the auxiliary atomization spraying disc, and the cylindrical baffle is fixed below the auxiliary atomization spraying disc. After flowing into the atomization area through the flow guide pipe, molten metal is impacted and broken into fine liquid drops by high-speed air flow generated by the main atomization spraying disc. High-pressure gas is introduced into the auxiliary atomization spraying disc to form a vertically-downward gas wall, and powder backmixing is jointly restrained by combining the cylindrical baffle. According to the main atomization spraying disc with the semi-LAVAL flow channel design, supersonic atomization airflow can be stably generated, and the fine powder yield is remarkably increased; the auxiliary atomization system effectively prevents fine powder from reflowing and bonding through a gas-solid double blocking mechanism, and the content of satellite powder and bonding powder is greatly reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal powder preparation, and particularly relates to a gas atomization device for metal powder preparation. BACKGROUND

[0002] Metal 3D printing technology usually takes spherical metal powder as raw material, melts the powder layer locally through a high-energy heat source, and solidifies layer by layer to form a part, and the comprehensive performance of the obtained part is largely determined by the physical properties of the powder raw material. Gas atomization (GA) is one of the main process means for preparing such metal powder at present, and the prepared powder has the characteristics of small particle size, uniform composition, good sphericity and excellent flowability, and has realized large-scale commercial production. The principle of gas atomization is to break the metal liquid stream by using high-speed airflow to form fine droplets, and the droplets gradually complete spheroidization and solidification during flight.

[0003] The existing gas atomization equipment is difficult to accurately control the airflow field in the atomization cavity, and a large vortex is easily generated inside and outside the atomization area. Small particle size powder is easy to follow the movement of the vortex and backflow, and thus re-enters the atomization area and collides with the liquid droplets in the atomization area, producing bonded powder or satellite powder, which ultimately affects the powder morphology and makes the powder flowability poor, thereby restricting its further application in the field of 3D printing. Figure 1 The nickel-based superalloy powder prepared by the device on the market has the characteristics of more bonded powder and poor flowability. In addition, improving the yield of high-quality fine powder suitable for 3D printing has become one of the key technical difficulties for promoting the wider application of this technology in the field of additive manufacturing.

[0004] Therefore, the prior art has defects and needs to be improved. SUMMARY

[0005] The present application provides a gas atomization device for metal powder preparation to solve the above problems.

[0006] In a first aspect, the application provides an aerosolization device for metal powder preparation, comprising a leakage package, a flow guide pipe, a main atomization nozzle, an auxiliary atomization nozzle and a cylindrical baffle, the leakage package is funnel-shaped, the upper end of the flow guide pipe is connected to the outlet at the bottom of the leakage package, and the lower end protrudes from the leakage package, the main atomization nozzle is sleeved outside the flow guide pipe and is connected to the middle position of the auxiliary atomization nozzle, and the cylindrical baffle is fixedly connected with the lower plate of the auxiliary atomization nozzle, the molten metal flows out from the outlet of the leakage package, enters the atomization area through the flow guide pipe, and the main atomization nozzle connected with high-pressure gas forms a high-speed airflow to impact the molten metal flowing out, so that large-size liquid droplets are broken into fine liquid droplets, and the auxiliary atomization nozzle is connected with high-pressure gas emitted vertically downward to form a gas wall between the periphery of the small liquid droplets and the inner side of the cylindrical baffle.

[0007] Optionally, the main atomization nozzle comprises a nozzle upper cover and a nozzle lower cover, the nozzle upper cover and the nozzle lower cover are fixed by being buckled, and a first annular air chamber is formed between the nozzle upper cover and the nozzle lower cover when they are connected.

[0008] Optionally, a first gas inlet is arranged on the outside of the main atomization nozzle, generally, the first gas inlet is bidirectional and opposite to the radial direction of the main atomization nozzle or multi-directional and uniformly distributed along the radial direction of the main atomization nozzle, and the gas outlet on the inside of the main atomization nozzle is arranged as a half-LAVAL type flow channel, high-pressure gas enters the first annular air chamber from the first gas inlet on the outside of the main atomization nozzle, and then flows through the nozzle of the half-LAVAL type flow channel, and the direction of the nozzle of the half-LAVAL type flow channel is opposite to the flow path of the molten metal.

[0009] Optionally, the half-LAVAL type flow channel comprises a converging channel, a throat and a diverging channel connected in sequence, one end of the converging channel with a relatively large diameter is connected with the first annular air chamber and gradually converges to the throat, and the diverging channel gradually expands from the end close to the throat to the gas outlet end.

[0010] Optionally, the inlet diameter of the converging channel is d1, the diameter of the throat is d2, and the diameter of each section of the converging channel is D1(x), which satisfies the following relationship:

[0011]

[0012] Wherein, l1 is the length of the converging channel, x is the length of the D1(x) diameter from the inlet diameter d1, a is the atomization cone angle of the nozzle upper cover, and k(a) is a shape parameter affected by the atomization cone angle.

[0013] Optionally, the outlet diameter of the diverging channel is d3, and the diameter of each section of the diverging channel is D2(x), which satisfies the following relationship:

[0014]

[0015] wherein, l2 is the length of the expansion channel, x is the length from the inlet diameter d1 to the diameter D2(x), a is the atomizing cone angle of the upper cover of the spray disc, g(a) is the shape parameter affected by the spray angle.

[0016] Optionally, the auxiliary atomizing spray disc comprises an upper plate and a lower plate, air passages are formed in one end of the upper plate close to the lower plate and in one end of the lower plate close to the upper plate, a second annular air chamber is formed between the upper plate and the lower plate when they are connected, a second air inlet is formed in one end of the upper plate away from the lower plate, and a second air outlet is formed in one end of the lower plate away from the upper plate, and the air outlet direction of the second air outlet is perpendicular to the lower plate.

[0017] Optionally, four second air inlets are arranged, and the number of the second air outlets is n, which satisfies the following relationship:

[0018] (n x d()≤k x (4 x D()

[0019] wherein, k is a flow coefficient, D is the diameter of the second air inlet, and d is the diameter of the second air outlet.

[0020] Optionally, the ratio of the diameter to the height of the cylindrical baffle is 1:6-1:1, and the diameter of the cylindrical baffle is 1:5-1:3 of the inner diameter of the atomizing pulverizer.

[0021] Compared with the prior art, the above technical solution provided by the embodiments of the present application has the following advantages:

[0022] The embodiments of the present application set the main atomizing spray disc, and high-pressure gas is used to exert strong impact and crushing effect on the molten metal, which is conducive to producing small metal droplets. Meanwhile, the auxiliary atomizing spray disc and the cylindrical baffle are arranged, which form a high-pressure gas wall in the periphery and direct downward, so as to constrain the atomizing range of the droplets and make the atomizing range more concentrated, and the fine powder backmixing phenomenon is greatly inhibited, the upward situation of the residual powder caused by air flow backflow is effectively prevented, and the residual powder is prevented from returning to the high-temperature atomizing area.

[0023] The atomizing device of this invention, in its first aspect, effectively suppresses the back-mixing phenomenon of fine powders by combining an auxiliary airflow with a cylindrical baffle. Specifically, a cylindrical baffle is installed above the airflow recirculation vortex zone inside the atomizing can. This baffle physically intercepts fine metal powders that are not collected in time, preventing them from entering the main atomizing area and colliding and adhering with the unsolidified molten metal droplets. The cylindrical baffle acts as a first-level isolation barrier, blocking most of the returning fine powder; while the downward high-speed airflow generated by the auxiliary atomizing spray disc forms a second gaseous barrier, further blocking the rise of residual powder. Furthermore, the baffle also converges and extends the auxiliary airflow, enhancing its downward stability and expanding the air curtain protection range, thereby significantly reducing the content of satellite powder and binder powder.

[0024] Secondly, the atomizing device of this invention provides a main atomizing nozzle with a semi-Laval flow channel design. The main atomizing nozzle adopts a split design including an upper cover and a lower cover. The Laval flow channel can stably generate a uniform supersonic atomized airflow by precisely expanding and accelerating the airflow. This high-speed airflow can exert a stronger abrasive force on the molten metal flow, thereby generating fine metal droplets more efficiently and significantly improving the yield of fine-particle-size powders (e.g., -53μm to -15μm), providing more powders of the required specifications for high-value-added applications such as 3D printing. Attached Figure Description

[0025] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0028] Figure 1 The morphology of commercially available nickel-based high-temperature alloy powders is shown.

[0029] Figure 2 This is a cross-sectional view of the gas atomizing device for metal powder preparation, molten metal, a first screw, and a second screw, as described in this application.

[0030] Figure 3 This is a cross-sectional view of the main atomizing spray disc of this application.

[0031] Figure 4 for Figure 3 Enlarged view of point B in the middle.

[0032] Figure 5 for Figure 2 Enlarged view of point A in the middle.

[0033] Figure 6 The morphology of the nickel-based high-temperature alloy powder prepared by the apparatus of the present invention is shown.

[0034] Explanation of reference numerals in the attached figures:

[0035] 1. Molten metal; 2. Slotted container; 3. Guide tube; 4. Main atomizing spray disc; 5. Auxiliary atomizing spray disc; 6. Cylindrical baffle; 7. Spray disc upper cover; 8. Spray disc lower cover; 9. First annular air chamber; 10. First air inlet; 11. Semi-LAVAL type flow channel; 13. Upper plate; 14. Lower plate; 15. Second annular air chamber; 16. Second air inlet; 17. Second air outlet; 18. First screw hole; 19. First through hole; 20. First screw; 21. Second screw hole; 22. Second through hole; 23. Second screw; 24. First annular groove; 25. Second annular groove; 26. O-ring seal; 111. Contraction channel; 112. Throat; 113. Expansion channel. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0037] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0038] For ease of description, spatial relative terms may be used in the text to describe the relative position or movement of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "below," "above," "front," "back," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure. For example, if the device in the figure undergoes a positional flip, orientation change, or change of motion, these directional indications will change accordingly. For instance, an element described as "below other elements or features" or "below other elements or features" will subsequently be oriented "above other elements or features" or "above other elements or features." Therefore, the example term "below" can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or in other directions), and the spatial relative descriptors used in the text will be interpreted accordingly.

[0039] To address the technical problems in the prior art, this application provides a gas atomization device for metal powder preparation. This device, through the setting of a main atomizing spray disc and a cylindrical baffle, applies a strong impact and crushing effect to the molten metal using high-pressure gas, which is beneficial for producing fine metal droplets. Simultaneously, by setting an auxiliary atomizing spray disc, a downward-facing high-pressure gas wall is formed around the device, constraining the atomization range of the droplets and making the atomization range more concentrated. This also significantly suppresses the back-mixing of fine powders, effectively preventing residual powder from rising due to airflow recirculation and preventing it from returning to the high-temperature atomization zone.

[0040] The first aspect effectively suppresses the back-mixing of fine powders by combining auxiliary airflow with a cylindrical baffle. Specifically, a cylindrical baffle is installed above the airflow recirculation vortex zone inside the atomizing can. This baffle physically intercepts fine metal powders that are not collected in time, preventing them from entering the main atomization area and colliding and adhering with the unsolidified metal droplets. The cylindrical baffle acts as the first-level isolation barrier, blocking most of the returning fine powder; while the downward high-speed airflow generated by the auxiliary atomizing nozzle forms a second gaseous barrier, further blocking the rise of residual powder. Furthermore, the baffle also converges and extends the auxiliary airflow, enhancing its downward stability and expanding the air curtain protection range, thereby significantly reducing the content of satellite powder and binder powder.

[0041] Secondly, the atomizing device of this invention provides a main atomizing nozzle with a semi-Laval flow channel design. The main atomizing nozzle adopts a split design including an upper cover and a lower cover. The Laval flow channel can stably generate a uniform supersonic atomized airflow by precisely expanding and accelerating the airflow. This high-speed airflow can exert a stronger abrasive force on the molten metal flow, thereby generating fine metal droplets more efficiently and significantly improving the yield of fine-particle-size powders (e.g., -53μm to -15μm), providing more powders of the required specifications for high-value-added applications such as 3D printing.

[0042] Figures 2-5 This application provides an embodiment of a gas atomizing device for preparing metal powder, used to atomize molten metal 1 into small droplets. The device includes a funnel-shaped diffuser 2, a guide tube 3, a main atomizing spray disc 4, an auxiliary atomizing spray disc 5, and a cylindrical baffle 6. The funnel-shaped diffuser 2 has one end connected to the outlet at the bottom of the diffuser 2, and the other end protruding from the diffuser 2. The main atomizing spray disc 4 is fitted outside the guide tube 3 and connected to the middle of the auxiliary atomizing spray disc 5. The other end of the guide tube 3 communicates with the interior of the auxiliary atomizing spray disc 5. The cylindrical baffle 6 is fixedly connected to the end of the auxiliary atomizing spray disc 5 away from the main atomizing spray disc 4. Both the main atomizing spray disc 4 and the auxiliary atomizing spray disc 5 are connected to high-pressure gas equipment.

[0043] When the gas atomizing device for metal powder preparation is working, molten metal 1 flows out from the outlet of the sluice box 2. The main atomizing spray disk 4 forms a high-speed airflow to impact the outflowing molten metal 1, causing large droplets to be broken into fine droplets. The auxiliary atomizing spray disk 5 forms a high-pressure gas wall around the droplets. The cylindrical baffle 6 is located around the high-pressure gas wall, forming a physical barrier. The main atomizing spray disc 4 applies a strong impact and crushing effect to the molten metal 1 using high-pressure gas, which is beneficial for producing fine and uniform metal droplets and improving the yield of fine-particle-size powder. The auxiliary atomizing spray disc 5 forms a downward-facing high-pressure gas wall around the periphery, which constrains the atomization range of the droplets and makes the atomization range more concentrated. At the same time, it greatly suppresses the back-mixing phenomenon of fine powder and effectively prevents the residual powder from rising due to the backflow of airflow, preventing it from returning to the high-temperature atomization zone. The cylindrical baffle 6 can physically connect the returning fine metal powder, preventing it from colliding and sticking with the unsolidified metal droplets, thereby reducing the generation rate of adhesive powder or satellite powder, which would affect the morphology of the powder and reduce the possibility of poor powder flowability. Its interaction and cooperation with the high-pressure gas wall effectively suppresses the back-mixing phenomenon of fine powder and helps to significantly reduce the content of adhesive powder and satellite powder.

[0044] Furthermore, the main atomizing spray disc 4 includes an upper cover 7 and a lower cover 8. The upper cover 7 and the lower cover 8 are fastened together, specifically by snap-fit ​​connection, or by welding or threaded connection on the basis of snap-fit ​​connection to make the connection more stable, including but not limited to these, and other fixing methods can also be used to achieve the connection between the two. When the upper cover 7 and the lower cover 8 are connected, a first annular air chamber 9 is formed between them.

[0045] Please see Figure 3 The main atomizing spray disk 4 has a first air inlet 10 on its outer side. Generally, the first air inlet 10 is bidirectional and opposite along the radial direction of the main atomizing spray disk 4, or multidirectional and evenly distributed along the radial direction of the main atomizing spray disk 4. The air outlet on the inner side of the main atomizing spray disk 4 is set as a semi-LAVAL type flow channel 11, which is an annular slit nozzle with a semi-LAVAL shape. This structure enables the airflow to achieve supersonic acceleration, forming a stable, concentrated, and high-speed airflow, significantly enhancing the breaking efficiency of the molten metal flow. One end of the semi-LAVAL type flow channel 11 is connected to the first annular air chamber 9, and the other end is opposite to the flow path of the molten metal 1. The semi-LAVAL type flow channel 11 has a diameter that gradually decreases and then gradually increases, which can achieve precise expansion and acceleration of the flowing airflow. This is conducive to generating a stable and uniform super-factor atomized airflow and has a stronger breaking ability on the molten metal flow. This can more effectively impact larger molten metal droplets into smaller molten metal droplets, which is conducive to increasing the output ratio of fine particle size powder, so as to provide more high-specification powder for high value-added applications such as 3D printing. Figure 6 The nickel-based high-temperature alloy powder prepared by the device of the present invention has the characteristics of good powder sphericity, less binder powder, and good flowability. Specifically, the semi-LAVAL type flow channel 11 includes a contraction channel 111, a throat 112, and an expansion channel 113 connected in sequence. The end of the contraction channel 111 with a larger diameter is connected to the high-pressure gas equipment and gradually contracts towards the throat 112. The expansion channel 113 gradually expands from the end near the throat 112 towards the outlet end.

[0046] Furthermore, the inlet diameter of the contraction channel 111 is d1, the diameter of the throat 112 is d2, and the diameter of each segment of the contraction channel 111 is D1(x), which satisfies the following relationship:

[0047]

[0048] Wherein, l1 is the length of the contraction channel 111, and the value of l1 is 4d2≤<10d2; x is the length of the inlet diameter d1 at the D1(x) orifice; α is the atomizing cone angle of the spray disc cover 7, and its value ranges from 28° to 58°; k(α) is the shape parameter affected by the atomizing cone angle, which satisfies the formula k(α)=0.5·(1+0.06α).

[0049] Furthermore, the outlet diameter of the expansion channel 113 is d3, and the diameter of each segment of the expansion channel 113 is D2(x), which satisfies the following relationship:

[0050]

[0051] Where l2 is the length of expansion channel 113, x is the distance from the inlet diameter d1 at the D2(x) orifice, α is the atomizing cone angle of the spray disc cover 7, which ranges from 28° to 58°, and g(α) is the shape parameter affected by the spray angle, g(α) = -0.5·(0.02α+5.22).

[0052] Please see Figure 5 The auxiliary atomizing spray disc 5 includes an upper plate 13 and a lower plate 14. Air passages are provided at the end of the upper plate 13 near the lower plate 14 and at the end of the lower plate 14 near the upper plate 13. When the upper plate 13 and lower plate 14 are connected, a second annular air chamber 15 is formed between them. A second air inlet 16 is provided at the end of the upper plate 13 away from the lower plate 14, and a second air outlet 17 is provided at the end of the lower plate 14 away from the upper plate 13. The air outlet direction of the second air outlet 17 is perpendicular to the lower plate 14. The upper plate 13 and lower plate 14 are fixedly connected. A cylindrical baffle 6 is fixedly connected to the lower plate 14, and the second air outlet 17 is located inside the cylindrical baffle 6. The second air inlet 16 is connected to a high-pressure gas device, and the high-pressure gas forms a vertically downward high-pressure gas wall through the second air inlet 16, the second annular air chamber 15, and the second air outlet 17. Preferably, four second air inlets 16 are provided and evenly distributed along the axial direction.

[0053] As one embodiment, the number of air outlets 17 is n, which satisfies the following relationship:

[0054] (n×d()≤k×(4×D()

[0055] Where k is the flow coefficient, specifically ranging from 0.1 to 0.5, D is the diameter of the second air inlet 16, and d is the diameter of the second air outlet 17. In one specific embodiment, the number of second air outlets 17 is 80-120, evenly distributed in multiple concentric circles, with a diameter of 0.5-3 mm. The diameter of the second air inlet 16 is 6-16 mm, resulting in a denser high-pressure gas wall with higher protective strength.

[0056] Please continue reading. Figure 5The upper plate 13 and the lower plate 14 are connected by threads. A first screw hole 18 is provided on the lower plate 14 near the second air inlet 16 of the second annular air chamber 15. A first through hole 19 is provided on the upper plate 13 corresponding to the first screw hole 18. An external first screw 20 passes through the first through hole 19 and connects to the first screw hole 18. A second screw hole 21 is provided on the lower plate 14 at the other end of the second annular air chamber 15 away from the first screw hole 18. A second through hole 22 is provided on the upper plate 13 corresponding to the second screw hole 21. An external second screw 23 passes through the second through hole 22 and connects to the second screw hole 21. The upper plate 13 and the lower plate 14 are connected by threads, which provides a more stable connection and facilitates disassembly and assembly. Furthermore, a first annular groove 24 is provided on the lower plate 14 between the first screw hole 18 and the air chamber 15, and a second annular groove 25 is provided on the lower plate 14 between the second screw hole 21 and the second annular air chamber 15. O-rings 26 are provided in both the first annular groove 24 and the second annular groove 25. This arrangement greatly increases the sealing performance of the second annular air chamber 15, preventing the gas in the second annular air chamber 15 from escaping from a position other than the second air outlet 17. This helps to ensure that the emitted high-pressure gas has sufficient pressure so that the high-pressure gas wall has a better protective effect.

[0057] Preferably, the cylindrical baffle 6 is made of a high-temperature resistant alloy material, such as 310S stainless steel or INCONEL series high-temperature alloy, to have strong toughness and long service life. Its inner surface is mirror polished to reduce the adhesion of powder on the inner surface and to ensure that blocked powder can slide smoothly to the collection point. The height of the cylindrical baffle 6 is 200-1200mm, the thickness is 3-8mm, and the ratio of its diameter to its height is 1:6-1:1. The diameter of the cylindrical baffle 6 is 1:5-1:3 of the inner diameter of the atomizing powder generator.

[0058] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0059] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0060] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0061] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0062] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0063] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. The illustrative expressions of the above terms in this specification should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0064] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Since these modifications and variations fall within the scope of the claims and their equivalents, this application also intends to include these modifications and variations.

[0065] The above description describes specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A gas atomizing device for preparing metal powder, used to disperse molten metal into small droplets, characterized in that: The device includes a funnel-shaped diffuser, a guide tube, a main atomizing spray disc, an auxiliary atomizing spray disc, and a cylindrical baffle. The diffuser is funnel-shaped. The upper end of the guide tube is connected to the outlet at the bottom of the diffuser, and the lower end protrudes from the diffuser. The main atomizing spray disc is sleeved on the outside of the guide tube and connected to the middle position of the auxiliary atomizing spray disc. The cylindrical baffle is fixedly connected to the lower plate of the auxiliary atomizing spray disc. The molten metal flows out from the outlet of the diffuser, enters the atomization zone through the guide tube, and the main atomizing spray disc, which is connected to high-pressure gas, forms a high-speed airflow that impacts the outflowing molten metal, breaking large droplets into fine droplets. The auxiliary atomizing spray disc is connected to high-pressure gas emitted vertically downwards, forming a gas wall between the outer periphery of the small droplets and the inner side of the cylindrical baffle.

2. The gas atomizing device for metal powder preparation according to claim 1, characterized in that: The main atomizing spray disc includes an upper cover and a lower cover. The upper cover and the lower cover are fastened together and fixed. When the upper cover and the lower cover are connected, a first annular air chamber is formed between them.

3. The gas atomizing device for metal powder preparation according to claim 2, characterized in that: The main atomizing spray disk has a first air inlet on its outer side. Generally, the first air inlet is bidirectional and opposite to each other along the radial direction of the main atomizing spray disk or multidirectional and evenly distributed along the radial direction of the main atomizing spray disk. The air outlet on the inner side of the main atomizing spray disk is set as a semi-LAVAL type flow channel. High-pressure gas enters the first annular air chamber from the first air inlet on the outer side of the main atomizing spray disk, and then flows through the semi-LAVAL type flow channel nozzle. The direction of the semi-LAVAL type flow channel nozzle is opposite to the flow path of the molten metal.

4. The gas atomizing device for metal powder preparation according to claim 3, characterized in that: The semi-LAVAL type flow channel includes a contraction channel, a throat, and an expansion channel connected in sequence. The end of the contraction channel with a larger diameter is connected to the first annular air chamber and gradually contracts towards the throat. The expansion channel gradually expands from the end near the throat towards the end of the air outlet.

5. The gas atomizing device for metal powder preparation according to claim 4, characterized in that: The inlet diameter of the contraction channel is d1, the throat diameter is d2, and the diameter of each segment of the contraction channel is D1(x), which satisfy the following relationship: Where l1 is the length of the contraction channel, x is the distance from the inlet diameter d1 at the D1(x) orifice, α is the atomizing cone angle of the spray disc cover, and k(α) is the shape parameter affected by the atomizing cone angle.

6. The gas atomizing device for metal powder preparation according to claim 5, characterized in that: The outlet diameter of the expansion channel is d3, and the diameter of each segment of the expansion channel is D2(x), which satisfies the following relationship: Where l2 is the length of the expansion channel, x is the distance from the inlet diameter d1 at the D2(x) orifice, α is the atomizing cone angle of the spray disc cover, and g(α) is the shape parameter affected by the spray angle.

7. The gas atomizing device for metal powder preparation according to claim 1, characterized in that: The auxiliary atomizing spray disc includes an upper plate and a lower plate. Air passages are provided at the end of the upper plate near the lower plate and at the end of the lower plate near the upper plate. When the upper plate and the lower plate are connected, a second annular air chamber is formed between them. A second air inlet is provided at the end of the upper plate away from the lower plate, and a second air outlet is provided at the end of the lower plate away from the upper plate. The air outlet direction of the second air outlet is perpendicular to the lower plate.

8. The gas atomizing device for preparing metal powder according to claim 7, characterized in that: There are four second air inlets and n second air outlets, which satisfy the following relationship: (n×d()≤k×(4×D() Where k is the flow coefficient, D is the diameter of the second air inlet, and d is the diameter of the second air outlet.

9. The gas atomizing device for preparing metal powder according to claim 7, characterized in that: The ratio of the diameter to the height of the cylindrical baffle is 1:6 to 1:1, and the diameter of the cylindrical baffle is 1:5 to 1:3 of the inner diameter of the atomizing powder furnace.

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