Centrifugal atomization powder making device based on controllable airflow regulation and control and powder making method

Abstract

The invention belongs to the technical field of powder metallurgy, and particularly discloses a centrifugal atomization powder making device and method based on controllable airflow regulation, and the device comprises an atomization cabin, a vacuum control system, a bar driving unit, a plasma gun, a reverse airflow generation assembly, an inert gas supply system and a powder collector. The reverse airflow generation assembly comprises a plurality of nozzles which are uniformly distributed along the circumference of the bulkhead; according to the powder preparation method, molten metal atomization is achieved through electrode bar installation, vacuumizing and inert gas filling, electrode bar plasma melting and bar rotating propelling and reverse airflow jetting. Through the synergistic effect of'centrifugal force + controllable reverse airflow ', the diameter of the atomization cabin is reduced to be less than 2 m, the proportion of special-shaped powder is reduced to be less than 3%, the liquid drop cooling rate is increased by 1.5-2 times, high purity of powder, equipment miniaturization and process greenness are considered, the problems of low cooling efficiency, poor powder quality and the like of traditional centrifugal atomization are solved, and the method is suitable for industrial production. The method is suitable for preparing active metal high-end powder such as titanium alloy.

Description

Technical Field

[0001] This invention belongs to the field of powder metallurgy technology, specifically relating to a centrifugal atomization powder preparation device and method based on controllable airflow regulation. It is particularly suitable for the preparation of high-end powders of active metals such as titanium alloys and nickel-based high-temperature alloys, and can meet the stringent requirements of additive manufacturing and other fields for powder purity, morphology and microstructure. Background Technology

[0002] With the rapid iteration of high-end manufacturing technologies such as additive manufacturing and precision forming of high-performance components, metal powder, as a core raw material, directly determines the quality and reliability of the final product based on its performance indicators (such as oxygen content, sphericity, particle size distribution, and microstructure). This places more stringent requirements on powder production technology. Currently, the industry mainly relies on two technical routes for powder production: gas atomization and centrifugal atomization. However, these two technologies differ significantly in performance and application scenarios, making it difficult to simultaneously meet the comprehensive requirements of high purity, high quality, and high efficiency.

[0003] Among them, gas atomization technology dominates the low-to-mid-end powder production sector due to its large-scale advantages, with a single output of up to 300 kg / furnace and a metal recovery rate exceeding 90%. However, this technology relies on high-pressure gas directly impacting molten metal to achieve atomization, and its inherent defects prevent it from meeting high-end demands: on the one hand, the contact between the high-pressure gas flow and air inevitably leads to powder oxidation, with oxygen content typically reaching 200–800 ppm, severely weakening the mechanical properties of the formed parts; on the other hand, the airflow impact easily generates defects such as satellite powder and hollow powder, reducing powder flowability and bulk density, and the 0.02–0.24 m 3 The enormous gas consumption of / kg contradicts the current development trend of green manufacturing and low-carbon production.

[0004] In contrast, centrifugal atomization technology, which uses a high-speed rotating electrode rod to centrifuge molten metal into droplets, combined with a fully enclosed inert gas environment, exhibits unique advantages in purity and morphology control. For example, the oxygen content of the prepared nickel-based alloy powder can be controlled below 70 ppm, and the oxygen content of titanium alloy powder is below 200 ppm, with excellent powder sphericity, making it the preferred technology for powdering active metals such as titanium alloys and high-temperature alloys. However, this "purely mechanical atomization + natural cooling" mode faces three major technical bottlenecks that are difficult to overcome, severely restricting its widespread application in high-end fields:

[0005] First, the low cooling efficiency directly leads to redundant equipment volume and limited production efficiency: Since the droplets rely entirely on the natural cooling of the static inert gas in the chamber, they need to travel a flight path of 1.5 to 3 meters to complete the solidification. To meet this requirement, the diameter of the atomizing chamber generally exceeds 3 meters, which not only greatly increases the equipment cost and floor space, but also limits the amount of droplets that can be processed per unit time due to the long cooling cycle. The production efficiency is only 60% to 70% of that of gas atomization technology, which is difficult to adapt to the demand for large-scale high-end powders.

[0006] Second, insufficient cooling rate causes inherent shortcomings in powder microstructure and mechanical properties: In natural cooling mode, the cooling rate of droplets is much lower than that of gas atomization, resulting in coarse microstructure of solidified powder particles. This defect will directly affect the subsequent formed parts, causing a significant decrease in their key mechanical properties such as strength and toughness, which cannot meet the stringent requirements for material properties of structural parts such as aerospace engine blades and high-end medical implants.

[0007] Third, the lack of active control means leads to poor powder morphology consistency: Since the droplet movement is driven solely by centrifugal force, about 15% to 20% of the incompletely solidified droplets will spread irregularly during flight and eventually collide with the cabin wall to form irregular powder. This kind of irregular powder not only destroys the uniformity of particle size distribution, but also forms voids in additive manufacturing or causes stress concentration during sintering, which seriously deteriorates the stability of product quality and reduces the yield of qualified powder to below 80%.

[0008] The above analysis reveals that the core issue of the three major bottlenecks lies in the fact that traditional centrifugal atomization technology relies solely on centrifugal force for atomization, lacking an active control mechanism for the droplet cooling process and trajectory. It lacks both a directional airflow intervention structure for the molten region and a synergistic control logic for airflow and centrifugal force, resulting in an irreconcilable contradiction between cooling efficiency, equipment size, and powder quality. Therefore, developing a centrifugal atomization powder production technology that can simultaneously address low cooling efficiency, large equipment size, and poor powder consistency through the synergistic effect of controllable airflow and centrifugal force has become an urgent need in the current powder metallurgy field.

[0009] In view of this, the present invention is hereby proposed. Summary of the Invention

[0010] The purpose of this invention is to overcome the shortcomings of the prior art and provide a centrifugal atomization powder making device and method based on controllable airflow regulation. It is mainly used to solve the problems in the existing centrifugal atomization powder making technology, such as low cooling efficiency, large atomization chamber volume, limited production efficiency, coarse powder microstructure, and poor morphological consistency and low qualified yield caused by the irregular diffusion of unsolidified droplets due to the reliance on centrifugal force and natural cooling of droplets, so as to meet the requirements of high-end manufacturing for powder performance.

[0011] The objective of this invention is achieved through the following technical solution:

[0012] In a first aspect, the present invention provides a centrifugal atomization powder-making device based on controllable airflow regulation, comprising:

[0013] The atomizing chamber has a cylindrical shell structure.

[0014] A vacuum control system, which is connected to the atomization chamber via a vacuum pipeline;

[0015] A rod driving unit is connected to an electrode rod that is horizontally inserted into the atomization chamber, which is used to drive the electrode rod to rotate around its central axis and advance axially.

[0016] A plasma gun that extends into an atomizing chamber to generate a plasma flame to melt the end of the electrode rod;

[0017] A reverse airflow generating assembly is disposed inside the atomizing chamber and includes multiple nozzles evenly distributed along the circumference of the inner wall of the atomizing chamber for injecting a controllable inert gas airflow into the end region of the electrode rod.

[0018] An inert gas supply system is provided, wherein the inert gas supply system is connected to the atomizing chamber and the reverse airflow generating component respectively through gas supply pipelines, and is used to supply inert gas.

[0019] A powder collector, connected to the lower part of the atomization chamber, is used to collect the prepared metal powder.

[0020] Furthermore, the rod driving unit includes a rotary drive motor, a propulsion drive motor, and a push rod driven by the propulsion drive motor. The push rod is detachably connected to the electrode rod, and the central axis of the electrode rod coincides with the central axis of the plasma gun.

[0021] Furthermore, the number of nozzles is set to 12 to 36, the included angle between adjacent nozzles is 10° to 30°, and the spray direction of each nozzle is towards the end molten region of the electrode rod, so as to form an airflow field surrounding the molten region.

[0022] Preferably, there are 24 nozzles, with an included angle of 15° between any two adjacent nozzles, and the outlet diameter of each nozzle is 0.5mm to 2mm.

[0023] Furthermore, the inert gas supply system also includes a return gas pipeline connected to the atomization chamber, and both the return gas pipeline and the gas supply pipeline are equipped with airflow control valves to maintain the air pressure balance inside the chamber.

[0024] Secondly, the present invention also provides a centrifugal atomization powder preparation method based on controllable airflow regulation, wherein the centrifugal atomization powder preparation method uses the above-mentioned centrifugal atomization powder preparation device and includes the following steps:

[0025] Step 1, Installation and Preparation:

[0026] Install the electrode rod onto the push rod of the rod drive unit, ensuring that the electrode rod is coaxial with the plasma gun, and close and seal the atomization chamber.

[0027] Step 2: Environment Setup

[0028] Activate the vacuum control system to evacuate the atomizing chamber to <10. -3 After Pa, inert gas is then introduced into the atomization chamber through the inert gas supply system to the set pressure to form an inert protective atmosphere;

[0029] Step 3: Melting and Atomization

[0030] The plasma gun is activated to melt the end of the electrode rod. At the same time, the rod drive unit is activated to drive the electrode rod to rotate around its central axis at a set speed and advance axially. Simultaneously, the reverse airflow generator is activated to spray a controllable inert gas flow into the melting area at the end of the electrode rod through nozzles evenly distributed along the circumference. The molten metal is atomized into metal droplets by the synergistic effect of centrifugal force and reverse airflow.

[0031] Step 4: Powder Collection

[0032] The atomized metal droplets are cooled, solidified, and fall in the inert atmosphere of the atomization chamber and in the controlled inert gas flow jetted from the nozzle, and are collected by the powder collector.

[0033] Furthermore, in step 1, the electrode rod is made of steel, titanium alloy or nickel-based high-temperature alloy, with a diameter of 50mm to 80mm and a length of 300mm to 750mm.

[0034] Furthermore, in step 2, the inert gas supplied by the inert gas supply system is argon or helium with a purity of 99.99% or higher. After the inert gas is filled, the pressure in the atomization chamber is 0.1 MPa to 0.5 MPa.

[0035] Furthermore, in step 3, the heating power of the plasma gun is 30kW to 200kW.

[0036] Furthermore, in step 3, the rod driving unit drives the electrode rod to rotate around its central axis at a speed of 10000 r / min to 40000 r / min, and advances it along its axial direction at a speed of 0.1 mm / s to 1.0 mm / s.

[0037] Furthermore, in step 3, the airflow pressure injected by each nozzle is 0.3MPa to 1MPa, and the airflow pressure difference between each nozzle is controlled within ±0.05MPa to ensure the uniformity of the airflow field.

[0038] It should be noted that the atomizing chamber of this invention, with a diameter of less than 2 meters, can atomize molten metal into metal droplets and ultimately form high-quality metal powder. The core of this invention lies in the synergistic mechanism of centrifugal force and reverse airflow: From the perspective of droplet fragmentation, the centrifugal force generated by the high-speed rotation of the electrode rod first throws the molten metal at its end into an initial liquid film. Meanwhile, the reverse airflow generating component, through circumferentially distributed nozzles, sprays a directional and controllable inert gas flow into the molten area. This airflow not only forms a "secondary shear" on the initial liquid film, further breaking it into finer, more uniform droplets, thus avoiding the tendency of droplets to easily atomize due to centrifugal force alone, as is common in traditional centrifugal atomization. The issue of uneven size arises. From the perspective of cooling efficiency, the high-speed inert gas flow directly acts on the surface of the newly formed high-temperature droplets, forming forced convection heat transfer. Its heat transfer efficiency is far higher than the static natural cooling of traditional centrifugal atomization, significantly shortening the time required for droplet solidification, thus achieving full solidification without a long flight path. From the perspective of trajectory control, the uniform airflow field surrounding the molten region can flexibly guide the droplets, constraining the irregular diffusion of incompletely solidified droplets and reducing their probability of impacting the chamber walls. At the same time, the airflow drives the circulation of inert gas within the chamber, further ensuring stable cooling and shaping of the droplets within a short distance. In summary, this synergistic mode of "centrifugal force-driven atomization + reverse airflow-enhanced crushing and cooling" breaks through the technical limitations of traditional centrifugal atomization relying on long-distance natural cooling, achieving efficient and high-quality powder production with a short path.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The technical solution provided by this invention achieves the following breakthroughs while retaining the advantages of traditional centrifugal atomization through the synergistic effect of "centrifugal force + controllable reverse airflow":

[0041] Firstly, the equipment is miniaturized and the cost is reduced: Based on the reverse airflow generating component in the device (including 12 to 36 nozzles evenly distributed along the circumference of the inner wall of the atomizing chamber), the directional inert gas airflow output by it can regulate the flight trajectory of the droplets and enhance the cooling efficiency through forced convection heat transfer, so that the metal droplets can solidify without the long flight path of 1.5 to 3 meters in the traditional process. The diameter of the atomizing chamber is reduced from more than 3 meters to less than 2 meters, which greatly reduces the difficulty of equipment manufacturing and production costs.

[0042] Secondly, the powder morphology and consistency are improved: by regulating the inert gas supply system, the airflow pressure difference of each nozzle of the reverse airflow generation component is strictly controlled within ±0.05MPa, forming a uniform airflow field around the melting area at the end of the electrode rod. This airflow field can effectively constrain the trajectory of droplets, ensuring that the powder particles are fully solidified before impacting the inner wall of the atomization chamber. This completely solves the problem of 15% to 20% of unsolidified droplets impacting the chamber wall and forming irregularly shaped powder in the traditional process, reducing the proportion of irregularly shaped powder to below 3%, significantly improving the sphericity of the powder and batch consistency, and greatly increasing the yield of qualified powder, especially increasing the yield of fine-particle-size powder preparation.

[0043] Thirdly, microstructure and performance optimization: By optimizing the reverse airflow parameters (in conjunction with the inert gas supply system to precisely control the nozzle jet pressure, ranging from 0.3MPa to 1MPa), the droplet cooling rate is increased to 1.5 to 2 times that of traditional centrifugal atomization. The increased cooling rate increases the droplet supercooling, which in turn leads to a 30% to 50% refinement of the powder grain size. This effectively solves the shortcoming of coarse microstructure in traditional centrifugal atomization powder, not only improving the uniformity of powder microstructure, but also helping to improve the strength and toughness of subsequent formed parts by 15% to 30%, meeting the stringent requirements for material performance in aerospace, high-end medical and other fields.

[0044] In summary, during the powder preparation process, this invention first uses a vacuum control system to evacuate the atomization chamber to a vacuum level of <10. -3 The process involves removing air impurities using a pressure plate (Pa), followed by the introduction of argon or helium gas with a purity of over 99.99%, maintaining the high purity advantage of traditional centrifugal atomization (oxygen content <200ppm for titanium alloy powder and <70ppm for nickel-based alloy powder). Simultaneously, the directional action of the reverse airflow avoids the significant gas waste associated with traditional gas atomization, with the inert gas consumption per unit of powder produced being only 1 / 5 to 1 / 3 of that used in traditional gas atomization. Ultimately, through the coordinated operation of the device structure (such as the reverse airflow generating component and vacuum control system) and process parameters (such as airflow pressure and vacuum level), the process achieves a balance between equipment miniaturization, high powder quality, high production efficiency, and environmental friendliness, comprehensively overcoming the core bottlenecks of traditional powder production technology. Attached Figure Description

[0045] The accompanying drawings are incorporated in and form part of this specification, and together with the description serve to explain the principles of the invention.

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention 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.

[0047] Figure 1 This is a schematic diagram of the centrifugal atomizing powder-making device based on controllable airflow regulation according to the present invention.

[0048] Figure 2 This is a flowchart of the centrifugal atomization powder preparation method based on controllable airflow regulation according to the present invention;

[0049] Figure 3 Photograph of GH4169 nickel-based superalloy powder prepared in Example 1 of this invention;

[0050] Figure 4 Photograph of 316L stainless steel powder prepared in Example 2 of this invention;

[0051] Figure 5 Photograph of Ti6Al4V titanium alloy powder prepared in Example 3 of this invention;

[0052] Figure 6 Photographs of 316L stainless steel powder prepared using the traditional plasma rotating electrode powder preparation method for comparison.

[0053] in:

[0054] 1 is the atomizing chamber; 2 is the vacuum control system; 3 is the rod drive unit; 4 is the electrode rod; 5 is the plasma gun; 6 is the reverse airflow generating assembly; 7 is the inert gas supply system; 8 is the powder collector; 61 is the nozzle. Detailed Implementation

[0055] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses consistent with some aspects of the invention as detailed in the appended claims.

[0056] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0057] Please see Figure 1The present invention provides a centrifugal atomization powder making device based on controllable airflow regulation, which mainly consists of an atomization chamber 1, a vacuum control system 2, a rod driving unit 3, an electrode rod 4, a plasma gun 5, a reverse airflow generating component 6, an inert gas supply system 7, and a powder collector 8. All the above components form a closed-loop working system with the atomization chamber 1 as the center. The vacuum control system 2 is connected to the flange interface at the top of the atomizing chamber 1 via a pressure-resistant vacuum pipeline to create a vacuum environment inside the chamber. The rod drive unit 3 is bolted to the steel structure support on the left side of the atomizing chamber 1, and its output push rod passes through the dynamic sealing assembly of the chamber wall (using a double-end mechanical seal with fluorinated oil as the sealing medium) and is coaxially connected to the electrode rod 4 inside the chamber. The plasma gun 5 extends into the chamber 1 through a reserved mounting hole on the right side, and the gun body is sealed to the chamber wall via a flange, with the center of the gun head aligned with the center of the end of the electrode rod 4. The reverse airflow generating assembly 6 is fixed to the inner side wall of the atomizing chamber 1 via a welded bracket, and its air inlet is connected to the external inert gas supply system 7 via a through-chamber gas pipe. The inert gas supply system 7 is connected to the external inert gas supply system 7 via two branch pipelines. The gas supply lines supply gas to the atomizing chamber 1 (filled with protective gas) and the reverse airflow generating component 6 (providing atomizing airflow). The powder collector 8 is connected to the conical discharge port at the bottom of the atomizing chamber 1 via a quick-release flange to achieve efficient powder collection. Meanwhile, one end of the return gas line of the inert gas supply system 7 is connected to the exhaust port of the atomizing chamber 1, and the other end is connected to the circulation inlet of the inert gas supply system 7, forming a gas circulation regulation path. Airflow control valves are installed on both the return gas line and the supply gas line of the inert gas supply system 7 (airflow control valves are also installed on the two branch lines of the supply gas line) to maintain stable air pressure in the atomizing chamber 1 and avoid pressure fluctuations in the chamber affecting the atomization effect, so as to ensure that all components work together to achieve the complete powder making process of "melting-atomization-collection".

[0058] Specifically, the atomizing chamber 1 of this invention is made of 304 stainless steel and has a cylindrical shell structure with an inner diameter of less than 2 meters. The side wall of the chamber is provided with an observation window and an inspection door. The bottom of the chamber has a conical transition structure to facilitate the collection of metal powder to the powder collector 8. The joints of the chamber are sealed with fluororubber sealing rings to ensure the vacuum level is maintained.

[0059] The vacuum control system 2 of this invention consists of a rotary vane vacuum pump and a molecular pump, and is connected to the top flange interface of the atomization chamber 1 via a DN50 304 stainless steel vacuum pipeline. The pipeline is equipped with a vacuum pressure gauge and a solenoid valve, which can evacuate the vacuum level in the atomization chamber 1 to <10. -3 Pa, which satisfies the need for impurity removal before the establishment of an inert atmosphere.

[0060] The rod driving unit 3 of this invention includes a rotary drive motor with a rated power of 5.5kW, a propulsion drive motor with a rated power of 2.2kW, and a stainless steel push rod with a diameter of 100mm. One end of the push rod is connected to the output shaft of the rotary drive motor through a flange, and the other end is detachably connected to the electrode rod 4 through a chuck. The coaxiality error between the push rod and the electrode rod 4 is ≤0.05mm. The propulsion drive motor drives the push rod to move axially through a ball screw, thereby achieving stable feeding of the electrode rod 4.

[0061] The electrode rod 4 of this invention is selected according to the material of the powder to be prepared, such as Ti6Al4V titanium alloy rod (diameter 50mm~80mm, length 300mm~750mm), GH4169 nickel-based high temperature alloy rod, etc. The surface of the rod is ultrasonically cleaned with anhydrous ethanol to remove surface oil and impurities.

[0062] The plasma gun 5 of this invention adopts a transfer arc plasma gun with a rated output power of 30kW to 200kW. The gun body is fixed to the sealing flange on the side wall of the atomization chamber 1 through a water cooling jacket. The center of its nozzle coincides with the central axis of the electrode rod 4. The initial distance between the nozzle outlet and the end of the electrode rod 4 is 15mm to 20mm. It can generate a plasma flame with a temperature of over 15000K, thereby achieving rapid melting of the end of the electrode rod 4.

[0063] The reverse airflow generating component 6 of the present invention includes an annular airflow distribution pipe and 12 to 36 stainless steel nozzles 61 (preferably 24). The annular distribution pipe is fixed inside the atomizing chamber 1 by a bracket. The nozzles 61 are evenly distributed along the circumference of the distribution pipe, with an included angle of 10° to 30° (preferably 15°) between adjacent nozzles 61. The outlet diameter of the nozzles 61 is 0.5 mm to 2 mm, and the spray direction is all towards the melting area at the end of the electrode rod 4, forming a surrounding airflow field with a diameter of 50 mm to 80 mm.

[0064] The inert gas supply system 7 of this invention consists of an argon cylinder (purity ≥ 99.99%), a pressure reducing valve, and a mass flow controller. It is connected to the atomizing chamber 1 and the annular distribution pipe of the reverse airflow generating component 6 via two DN25 gas supply pipelines. Each pipeline is equipped with an airflow control valve, which can independently adjust the chamber filling pressure (0.1MPa~0.5MPa) and the nozzle airflow pressure (0.3MPa~1MPa), ensuring that the airflow pressure difference between each nozzle 61 is within ±0.05MPa. The return gas pipeline uses a DN32 stainless steel pipe, with one end connected to the exhaust port of the atomizing chamber 1 and the other end connected to the circulation inlet of the inert gas supply system 7. Preferably, in addition to the airflow control valve, this pipeline also includes a plate heat exchanger, a precision filter, and a pressure buffer tank. The plate heat exchanger cools the circulating gas to below 40°C, the precision filter removes micron-sized powder particles carried in the gas, and the pressure buffer tank effectively smooths out pipeline pressure pulsations, jointly maintaining the stability and cleanliness of the gas circulation.

[0065] The powder collector 8 of this invention consists of a three-stage cyclone separator and a bag filter. It is connected to the conical outlet at the bottom of the atomization chamber 1 through a feeding valve. An induced draft fan is provided between the separator and the dust collector. It can collect metal powders of different particle sizes through negative pressure, thereby improving the collection efficiency.

[0066] In addition, such as Figure 2 As shown, the present invention also provides a centrifugal atomization powder preparation method based on controllable airflow regulation, which uses the above-mentioned centrifugal atomization powder preparation device and specifically includes the following steps:

[0067] Step 1: Installation and Preparation

[0068] Install electrode rod 4 onto the push rod of rod drive unit 3: First, select electrode rod 4 of the corresponding specification according to the material of the powder to be prepared, and the surface of the rod needs to be ultrasonically cleaned with anhydrous ethanol to remove surface oil stains; then, insert one end of electrode rod 4 into the three-jaw chuck of push rod, and calibrate the central axis of electrode rod 4 and plasma gun 5 with laser coaxiality measuring instrument to ensure that the coaxiality error is ≤0.05mm, so as to avoid flame deviation during subsequent melting and atomization; after calibration, close the maintenance door of atomization chamber 1, check whether the fluororubber sealing ring at the chamber joint is intact, tighten the sealing bolts to ensure the chamber is airtight and prevent leakage during subsequent vacuuming or gas filling.

[0069] Step 2: Environment Setup

[0070] Start vacuum control system 2: First, turn on the rotary vane vacuum pump to perform a rough vacuum in atomizing chamber 1. When the vacuum pressure gauge shows that the pressure inside the chamber has dropped to 1-5 Pa, switch to the molecular pump for fine evacuation. Continue evacuating for 30-40 minutes until the vacuum level inside the chamber stabilizes at <10 Pa. -3 The process involves thoroughly removing air and impurities from the chamber; then closing the valve of the vacuum control system 2 and opening the airflow control valve of the inert gas supply system 7 leading to the atomization chamber 1 to fill the chamber with argon or helium of 99.99% purity or higher; monitoring the pressure in real time using the chamber pressure sensor, and closing the airflow control valve when the pressure reaches the set value of 0.1MPa to 0.5MPa (preferably 0.3MPa) to maintain the inert atmosphere in the chamber for 5 to 10 minutes to ensure that the residual air in the chamber is completely replaced, providing an oxygen-free protective environment for subsequent metal melting and preventing powder oxidation.

[0071] Step 3: Melting and Atomization

[0072] Start the plasma gun 5: First, turn on its water cooling system (cooling water flow rate ≥ 5L / min, inlet water temperature < 30℃). After the cooling cycle stabilizes, turn on the power of the plasma gun 5 and adjust the heating power to 30kW~200kW (adjust according to the electrode rod material, such as 30~120kW for titanium alloy and 120~200kW for nickel-based high-temperature alloy), generating a plasma flame with a temperature above 15000K. Heat the end of the electrode rod 4 until a stable molten metal area forms at the end. Simultaneously, start the rod drive unit 3: the rotary drive motor drives the electrode rod 4 to rotate around the central axis at a set speed of 10000r / min~40000r / min. The push drive motor drives the push rod through the ball screw at a speed of 0.1mm / s~1 The electrode rod 4 is advanced axially at a speed of 0.0 mm / s to ensure a continuous supply of metal to the molten area. Simultaneously, the reverse airflow generating component 6 is activated: the airflow control valve of the inert gas supply system 7 leading to this component is opened, and a controllable inert gas airflow is injected into the molten area at the end of the electrode rod 4 through multiple nozzles 61 evenly distributed along the circumference. The airflow pressure is adjusted to 0.3 MPa to 1 MPa, and the pressure difference between each nozzle 61 is controlled within ±0.05 MPa by multiple pressure sensors to form a uniform surrounding airflow field. At this time, the centrifugal force generated by the rotation of the electrode rod 4 throws the molten metal into an initial liquid film, and the reverse airflow performs "secondary shearing" on the liquid film. The two work together to break the molten metal into fine metal droplets with a diameter of 10 μm to 150 μm, achieving efficient atomization.

[0073] Step 4: Powder Collection

[0074] The atomized metal droplets, within the inert atmosphere of the atomization chamber 1, are propelled downwards by a controllable high-speed airflow ejected from nozzle 61 and by gravity. During this movement, forced convection heat exchange occurs with the inert gas inside the chamber (the heat exchange efficiency is 1.5 to 2 times that of traditional natural cooling), and cooling and solidification are completed in just 8 to 15 seconds, forming solid metal powder. Subsequently, the induced draft fan of the powder collector 8 is activated, and the negative pressure is adjusted to -0.01 MPa to -0.03 MPa, guiding the solid powder with the airflow into the three-stage cyclone separator. The separator classifies the powder according to its particle size: fine powder of 10μm to 45μm is collected by the subsequent bag filter, coarse powder of 45μm to 150μm settles in the separator, and large powder particles >150μm are separated in the first-stage separator. After the powder making process is completed, the plasma gun 5, the rod drive unit 3 and the reverse airflow generator 6 are turned off. After the temperature in the atomization chamber 1 drops to room temperature, the feed valve of the powder collector 8 is opened to collect metal powders of different particle size ranges, thus completing the entire powder making process.

[0075] To further verify the effectiveness of the present invention, the following specific experiments were conducted:

[0076] Example 1

[0077] This embodiment uses the centrifugal atomization powder preparation device provided by the present invention to prepare GH4169 nickel-based high-temperature alloy powder. The specific preparation process is as follows:

[0078] 1) Fix the GH4169 nickel-based high-temperature alloy electrode rod 4 with a diameter of 80mm and a length of 550mm onto the push rod of the rod drive unit 3, ensuring that the electrode rod 4 is coaxial with the plasma gun 5, and close and seal the atomization chamber 1.

[0079] 2) Activate vacuum control system 2 to evacuate atomizing chamber 1 to a vacuum level of <10. -3 After Pa, a leak rate test is performed. Once it is confirmed that the equipment pressure rise rate is stably below 0.03 Pa / min, argon gas with a purity of ≥99.99% is then introduced into the atomization chamber 1 through the inert gas supply system 7 to make the pressure in the atomization chamber 1 0.5 MPa, thus forming an inert protective atmosphere.

[0080] 3) The plasma gun 5 is activated to melt the end of the electrode rod 4, with the melting heating power set to 200kW. Simultaneously, the rod drive unit 3 is activated, driving the electrode rod 4 to rotate around its central axis at a speed of 10000r / min and advance axially at a constant speed of 0.1mm / s. At the same time, the reverse airflow generating component 6 is activated, spraying a controllable inert gas flow into the melting area at the end of the electrode rod 4 through 24 nozzles 61 evenly distributed along the circumference. The outlet diameter of each nozzle is 2mm, the airflow pressure is set to 1MPa, and the airflow pressure difference between each nozzle 61 is controlled within ±0.05MPa. That is, the reverse airflow generating component 6 forms a uniform surrounding airflow field in the atomization chamber 1, which, together with the centrifugal force generated by the rotation of the electrode rod 4, atomizes the molten metal into fine and controllable metal droplets.

[0081] 4) The atomized metal droplets are cooled, solidified, and fall in the inert atmosphere within the atomization chamber 1 and in the controllable inert gas flow ejected from the nozzle 61. They are then collected by the powder collector 8, yielding GH4169 nickel-based superalloy powder. The final microstructure of the GH4169 nickel-based superalloy powder is shown in the image below. Figure 3 As shown.

[0082] Example 2

[0083] This embodiment uses the centrifugal atomization powder preparation device provided by the present invention to prepare 316L stainless steel powder. The specific preparation process is as follows:

[0084] 1) Fix the 316L stainless steel electrode rod 4 with a diameter of 60mm and a length of 750mm onto the push rod of the rod drive unit 3, ensuring that the electrode rod 4 is coaxial with the plasma gun 5, and close and seal the atomization chamber 1.

[0085] 2) Activate vacuum control system 2 to evacuate atomizing chamber 1 to a vacuum level of <10. -3 After Pa, a leak rate test is performed. Once it is confirmed that the equipment pressure rise rate is stably below 0.03 Pa / min, helium with a purity of ≥99.99% is then introduced into the atomization chamber 1 through the inert gas supply system 7 to make the pressure in the atomization chamber 1 0.3 MPa, thus forming an inert protective atmosphere.

[0086] 3) The plasma gun 5 is activated to melt the end of the electrode rod 4, with the melting heating power set to 120kW. Simultaneously, the rod drive unit 3 is activated, driving the electrode rod 4 to rotate around its central axis at a speed of 25000r / min and advance axially at a constant speed of 0.6mm / s. At the same time, the reverse airflow generating component 6 is activated, spraying a controllable inert gas flow into the melting area at the end of the electrode rod 4 through 24 nozzles 61 evenly distributed along the circumference. The outlet diameter of each nozzle is 1mm, the airflow pressure is set to 0.6MPa, and the airflow pressure difference between each nozzle 61 is controlled within ±0.05MPa. That is, the reverse airflow generating component 6 forms a uniform surrounding airflow field in the atomization chamber 1, which, together with the centrifugal force generated by the rotation of the electrode rod 4, atomizes the molten metal into fine and controllable metal droplets.

[0087] 4) The atomized metal droplets are cooled, solidified, and fall in the inert atmosphere within the atomization chamber 1 and the controllable inert gas flow ejected from the nozzle 61. They are then collected by the powder collector 8, yielding 316L stainless steel finished powder. The final microstructure of the 316L stainless steel finished powder is as follows: Figure 4 As shown.

[0088] Example 3

[0089] This embodiment uses the centrifugal atomization powder preparation device provided by the present invention to prepare Ti6Al4V titanium alloy powder. The specific preparation process is as follows:

[0090] 1) Fix the Ti6Al4V titanium alloy electrode rod 4 with a diameter of 50mm and a length of 300mm onto the push rod of the rod drive unit 3, ensuring that the electrode rod 4 is coaxial with the plasma gun 5, and close and seal the atomization chamber 1.

[0091] 2) Activate vacuum control system 2 to evacuate atomizing chamber 1 to a vacuum level of <10. -3 After Pa, a leak rate test is performed. Once it is confirmed that the equipment pressure rise rate is stably below 0.03 Pa / min, argon gas with a purity of ≥99.99% is then introduced into the atomization chamber 1 through the inert gas supply system 7 to make the pressure in the atomization chamber 1 0.1 MPa, thus forming an inert protective atmosphere.

[0092] 3) The plasma gun 5 is activated to melt the end of the electrode rod 4, with the melting heating power set to 30kW. Simultaneously, the rod drive unit 3 is activated, driving the electrode rod 4 to rotate around its central axis at a speed of 40,000 r / min and advance axially at a constant speed of 1 mm / s. At the same time, the reverse airflow generating component 6 is activated, spraying a controllable inert gas flow into the melting area at the end of the electrode rod 4 through 24 nozzles 61 evenly distributed along the circumference. The outlet diameter of each nozzle is 0.5 mm, the airflow pressure is set to 0.3 MPa, and the airflow pressure difference between each nozzle 61 is controlled within ±0.05 MPa. That is, the reverse airflow generating component 6 forms a uniform surrounding airflow field in the atomization chamber 1, which, together with the centrifugal force generated by the rotation of the electrode rod 4, atomizes the molten metal into fine and controllable metal droplets.

[0093] 4) The atomized metal droplets are cooled, solidified, and fall in the inert atmosphere within the atomization chamber 1 and in the controllable inert gas flow ejected from the nozzle 61. They are then collected by the powder collector 8, yielding Ti6Al4V titanium alloy powder. The final microstructure of the Ti6Al4V titanium alloy powder is shown in the image below. Figure 5 As shown.

[0094] Comparative Example

[0095] In this comparative example, the raw material is 316L stainless steel bar. The only difference between this comparative example and Example 2 is that this comparative example uses a traditional plasma rotating electrode powder-making device, and no reverse airflow is introduced during the process. That is, it does not include the step of starting the reverse airflow generating component 6 in step 3) of Example 2. All other process parameters are the same. The microstructure of the final 316L stainless steel powder is as follows. Figure 6 As shown.

[0096] pass Figures 3 to 5Microscopic observation revealed that the three metal powders prepared in this invention all exhibited highly spherical characteristics. The powder particles had rounded outlines, smooth surfaces without obvious depressions or adhesions, and did not contain satellite powder (small particles attached to the surface of large particles), flaky powder (flat particles), or fibrous powder (slender and irregular particles) commonly found in traditional powder preparation. According to Image-Pro Plus image analysis software, the proportion of irregularly shaped powders in all three powders was <3% (2.1% for GH4169 powder, 1.7% for 316L stainless steel powder, and 2.5% for Ti6Al4V titanium alloy powder), and the sphericity (the ratio of the particle's projected area to the area of ​​its circumcircle) was over 95%. This result confirms the core function of the "reverse airflow generating component" of the present invention: the uniform airflow field sprayed by multiple circumferentially distributed nozzles can form a "flexible guiding constraint" and "rapid cooling" for the molten droplets thrown out by centrifugal force, avoiding the irregular diffusion of unsolidified droplets and their impact on the chamber wall. At the same time, the "secondary shearing" effect of the airflow on the liquid film can reduce droplet morphology defects, ultimately achieving the preparation of powder with high sphericity.

[0097] In contrast, the comparative example (316L stainless steel powder prepared by a traditional plasma rotating electrode powder preparation device) Figure 6 The microstructure of the two powders exhibits significant differences: due to the absence of reverse airflow intervention during powder preparation, the droplet movement is driven solely by the centrifugal force generated by the rotation of the electrode rod, resulting in random droplet flight trajectories (some droplets diffuse towards the chamber wall due to insufficient centrifugal force). Furthermore, the cooling process is static natural cooling (without forced convection heat transfer), which easily leads to problems such as droplet adhesion forming satellite powder and uneven cooling due to droplet impact on the chamber wall forming flaky powder. Statistical analysis using the same method showed that the proportion of irregularly shaped powder in the comparative powder was as high as 8%–15% (average 11.3%), with a sphericity of only 82%–88% (average 85.6%), and the powder surface exhibited obvious oxidation color (due to local oxygen content fluctuations during natural cooling). This further highlights the technical advantages of the "centrifugal force + controllable reverse airflow" synergistic design of this invention.

[0098] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention.

[0099] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A centrifugal atomization powder-making device based on controllable airflow regulation, characterized in that, include: Atomizing chamber (1), wherein the atomizing chamber (1) has a cylindrical shell structure; Vacuum control system (2), which is connected to atomization chamber (1) through vacuum pipeline; Rod driving unit (3), the rod driving unit (3) is connected to an electrode rod (4) that is horizontally inserted into the atomizing chamber (1), for driving the electrode rod (4) to rotate around its central axis and advance along the axial direction; Plasma gun (5), which extends into atomization chamber (1) to generate a plasma flame to melt the end of the electrode rod (4); A reverse airflow generating assembly (6) is disposed inside the atomizing chamber (1) and includes multiple nozzles (61) evenly distributed along the circumference of the inner wall of the atomizing chamber (1) for injecting a controllable inert gas flow into the end region of the electrode rod (4). An inert gas supply system (7) is connected to the atomizing chamber (1) and the reverse airflow generating assembly (6) respectively through a gas supply pipeline, and is used to supply inert gas; Powder collector (8), which is connected to the lower part of the atomization chamber (1), is used to collect the prepared metal powder.

2. The centrifugal atomizing powder-making device based on controllable airflow regulation according to claim 1, characterized in that, The rod driving unit (3) includes a rotary drive motor, a propulsion drive motor and a push rod driven by the propulsion drive motor. The push rod is detachably connected to the electrode rod (4), and the central axis of the electrode rod (4) coincides with the central axis of the plasma gun (5).

3. The centrifugal atomizing powder-making device based on controllable airflow regulation according to claim 1, characterized in that, The number of nozzles (61) is set to 12 to 36, the included angle between adjacent nozzles (61) is 10° to 30°, and the spray direction of each nozzle (61) is towards the end melting area of ​​the electrode rod (4) to form an airflow field around the melting area.

4. The centrifugal atomizing powder-making device based on controllable airflow regulation according to claim 1, characterized in that, The inert gas supply system (7) also includes a return gas pipeline, which is connected to the atomization chamber (1). Both the return gas pipeline and the gas supply pipeline are equipped with airflow control valves to maintain the air pressure balance inside the chamber.

5. A centrifugal atomization powder preparation method based on controllable airflow regulation, characterized in that, The centrifugal atomizing powder-making apparatus according to any one of claims 1 to 4 includes the following steps: Step 1: Installation and Preparation Install the electrode rod (4) on the push rod of the rod drive unit (3), ensure that the electrode rod (4) is coaxial with the plasma gun (5), close the atomization chamber (1) and seal it; Step 2: Environment Setup The vacuum control system (2) is activated to evacuate the atomizing chamber (1) to a vacuum level of <10. -3 After Pa, inert gas is then introduced into the atomization chamber (1) through the inert gas supply system (7) to the set pressure to form an inert protective atmosphere; Step 3: Melting and Atomization The plasma gun (5) is activated to melt the end of the electrode rod (4). At the same time, the rod driving unit (3) is activated to drive the electrode rod (4) to rotate around its central axis at a set speed and advance along the axis. At the same time, the reverse airflow generating component (6) is activated to spray a controllable inert gas flow into the melting area at the end of the electrode rod (4) through nozzles (61) evenly distributed along the circumference. The molten metal is atomized into metal droplets by the synergistic effect of centrifugal force and reverse airflow. Step 4: Powder Collection The atomized metal droplets are cooled, solidified and fall in the inert atmosphere in the atomization chamber (1) and the controlled inert gas flow jetted by the nozzle (61), and are collected by the powder collector (8).

6. The centrifugal atomization powder preparation method based on controllable airflow regulation according to claim 5, characterized in that, In step 1, the electrode rod (4) is made of steel, titanium alloy or nickel-based high-temperature alloy, with a diameter of 50mm to 80mm and a length of 300mm to 750mm.

7. The centrifugal atomization powder preparation method based on controllable airflow regulation according to claim 5, characterized in that, In step 2, the inert gas supplied by the inert gas supply system (7) is argon or helium with a purity of 99.99% or higher. After the inert gas is filled, the pressure in the atomization chamber (1) is 0.1MPa to 0.5MPa.

8. The centrifugal atomization powder preparation method based on controllable airflow regulation according to claim 5, characterized in that, In step 3, the heating power of the plasma gun (5) is 30kW to 200kW.

9. The centrifugal atomization powder preparation method based on controllable airflow regulation according to claim 5, characterized in that, In step 3, the rod driving unit (3) drives the electrode rod (4) to rotate around its central axis at a speed of 10000 r / min to 40000 r / min, and advances it along its axial direction at a speed of 0.1 mm / s to 1.0 mm / s.

10. The centrifugal atomization powder preparation method based on controllable airflow regulation according to claim 5, characterized in that, In step 3, the airflow pressure injected by each nozzle (61) is 0.3MPa to 1MPa, and the airflow pressure difference between each nozzle (61) is controlled within ±0.05MPa to ensure the uniformity of the airflow field.

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