Method and device for preparing metal powder

Abstract

The present invention relates to a method and apparatus for preparing metal powder, comprising the following steps: step (1), feeding a base material into a melting zone and a rotary atomizing unit, melting the end of the base material, ensuring centrifugal atomization through the rotary atomizing unit, obtaining atomized particles, and cooling and solidifying them during rapid movement; step (2), heating and melting the base material by immersing the end of the base material in an alkaline salt water electrolyte solution, wherein the electrolyte solution serves as an anode of an electrode, and the base material serves as a cathode connected to a circuit, generating a potential difference of 200 to 300 volts between the electrodes, thereby heating the surface of the base material; step (3), melting the end of the base material in the form of micro-discharge after power is applied, wherein the discharge is converted from electrolyte plasma; in the electrolyte flow, metal droplets at the end of the base material solidify into spherical particles and disperse. The present invention has a simple structure and an ingenious design, and can ensure high uniformity of powder size and minimize gas infiltration.

Description

Technical Field

[0001] The present invention belongs to the technical field of powder metallurgy, and in particular relates to a method and equipment for preparing metal powder. Background Art

[0002] ① The existing method for producing narrow-grained spherical powder from aluminum-nickel-based heat-resistant alloy (patent RU 2681022 C1) [1]. This method is divided into two stages. In the initial separation stage, the powder of a given particle size is separated from the initial powder material with a particle size of 5 to 150 μm; the subsequent subsequent stage is to separate the separated powder under a vacuum degree of 10 -6 ~10 -5 The target product is obtained by heating the steel to 800-900° C. at a heating rate of 15-20° C. / min and then performing vacuum heat treatment for 3-4 hours; and then performing plasma spheroidization.

[0003] After the initial separation, the remaining finer and coarser powders are mixed, pressed, and vacuum sintered to a relative density of 70-80%. The powder is then ground to recover the powder, and the initial separation and subsequent stages are repeated to obtain the target product. This method improves the quality of the target product by reducing the impurity content during the plasma spheroidization process of the powder.

[0004] This method can be used in the machinery manufacturing industry to manufacture heat-resistant nickel alloy components through additive manufacturing, hot pressing, laser cladding and other technologies. When pure, dispersed spherical powder is required, this method ensures the powder has high flowability and bulk density.

[0005] The disadvantage of this method for preparing narrow-particle-size spherical powder from aluminum-nickel heat-resistant alloy is that the implementation of the method requires multiple steps, which increases both energy consumption and powder production costs.

[0006] In addition, this plasma spheroidization powder process is carried out in an active gas (plasma) medium, and the obtained powder contains gas impurities and has large dispersion deviations, so this method is limited in industrial application.

[0007] ② Another existing method for preparing metal powder (patent RU2699479C1) [2]. This method is to disperse the material by discharging between two electrodes, one of which is a cathode made of a rod-shaped material with a diameter of 10≤d≤40mm; the electrolyte is used as the anode. The process parameters for preparing the powder are: the voltage between the electrodes is 500~650V, the discharge current is 1.5~3A, the distance between the cathode and the electrolyte is 2~10mm, and the whole process is carried out under atmospheric pressure. The proposed invention aims to solve the problem of preparing powder from the alloy Cr15Ni60. The method has the characteristics of low cost, low energy consumption and clean process environment. The method is to disperse the Cr15Ni60 alloy in an aqueous electrolyte, wherein the electrode voltage is 90~110V, the capacitance of the discharge capacitor is 58μF, and the pulse frequency is less than 120Hz.

[0008] The disadvantages of this existing method are as follows: the dispersion process is the result of a short-term localized discharge between the electrodes, which causes the conductive material to melt. Consequently, the high temperature in the discharge zone causes heating, melting, and partial evaporation of the metal, as well as the dissociation of water vapor. This method is achieved by overheating the metal and water, which leads to gas infiltration, metal loss, and the formation of defective micropowders.

[0009] The main problem to be solved by the present invention is to improve these disadvantages, that is, to eliminate the evaporation of the dispersed material and the gas infiltration, and to obtain a narrower particle size distribution.

[0010] ③ The existing "Method for producing ultrafine metal powder or metal alloy powder" (patent RU2588931C1) [3]. This invention relates to powder metallurgy and is used to produce metal powder with a particle size of 10 to 2000 μm. The method is implemented by feeding a metal rod into a chamber and melting its surface in an argon plasma arc generated by a plasma generator. The rod is melted and dispersed in the plasma stream, and then the metal droplets cool and condense in a powder collection hopper.

[0011] When producing powder, the plasma generator's DC current is 100 to 500 A, and the distance between the end of the metal rod and the plasma generator nozzle outlet is 30 to 120 mm, which allows for controlled powder particle size. The metal rod can be made of titanium, silicon, molybdenum, copper, titanium alloys, nickel alloys, cobalt alloys, or tool steel.

[0012] A drawback of this existing method is uneven heating of the workpiece, resulting in a wide range of powder particle size distribution. Small droplets overheat and partially evaporate, while large droplets cool into irregular shapes. This results in increased variation in powder particle size and compositional heterogeneity, reducing powder quality. This method also increases energy consumption for heating the material to melt, powder size screening, and secondary processing.

[0013] The main problem addressed by this invention is to improve these shortcomings, namely, to reduce heating costs and the cost of secondary processing of powders that are too small or too large in diameter. Furthermore, the proposed method uses controlled heating, which eliminates the costs associated with evaporation and overheating, and reduces the likelihood of large droplets and irregularly shaped powders.

[0014] The method proposed in this invention utilizes electrolytic plasma heating of the parent metal. Connecting the parent metal to the circuit with its cathode creates conditions for increased thermal power and a faster heating rate. This also creates conditions for forming a thin molten layer on the surface of the parent metal and dispersing it into nearly identical droplets, allowing these droplets to rapidly crystallize in a liquid (an aqueous solution of an alkaline salt).

[0015] These important features of the proposed method ensure high efficiency of base material melting, improve the quality of micropowder, and reduce raw material and energy consumption.

[0016] ④ The closest to the proposed invention is the “Method and apparatus for producing metal powder by centrifugal atomization” (patent RU2645169C2) [4], which is considered a prototype. The method comprises: feeding the base material into a rotary atomization unit and entering the melting zone, the plasma flow melts the end of the base material, and the rotary atomization unit ensures the centrifugal atomization of the molten layer and obtains dispersed molten droplet particles, which move rapidly in the gas and solidify. The feeding device of the base material is an atomization unit consisting of a hollow cylinder, which consists of two parts, and the two parts are made of different materials. The first part is a working section, which is made of powdering material; the second part is a cooling section, whose material has a higher thermal conductivity than the powdering material of the first part. When the base material is fed into the atomization unit, its end is aligned with the end of the atomization unit in a vertical plane. The method is achieved by using a plasma flow to heat and melt the end of the base material and the working part of the atomization unit. The dispersed material is separated from the base material by centrifugal force, forming a stable profile and a molten layer at the end.

[0017] The original method can use parent materials made of different alloys, thus expanding the application range of this technology.

[0018] The disadvantages of this prototyping method include: low heating power density, resulting in uneven heating and slow heating at the ends of the parent material. The uneven thickness of the melt layer at the ends of the parent material leads to the formation of dispersed particles of various sizes, resulting in a final powder size deviation ranging from 20 to 2500 μm. The low heating rate of the parent material limits the melting rate at the ends, causing the entire parent material to be heated, complicating the cooling system and complicating equipment reliability. Energy losses in the plasma generator result in low plasma heating efficiency and a limited generator lifespan.

[0019] In view of the above technical problems, improvements need to be made. Summary of the Invention

[0020] The present invention aims to overcome the above-mentioned deficiencies in the prior art and to provide a method and apparatus for preparing metal powder, thereby ensuring uniformity of powder size and minimal gas infiltration.

[0021] In order to achieve the above object, the technical solution adopted by the present invention includes the following steps:

[0022] Step (1) feeding the base material into the melting zone and the rotary atomizing unit, melting the end of the base material and ensuring that it is centrifugally atomized by the rotary atomizing unit, obtaining atomized particles, and cooling and solidifying them during rapid motion;

[0023] In step (2), the heating and melting of the base metal is achieved by immersing the end of the base metal in an alkaline salt water electrolyte solution, with the electrolyte solution acting as the anode of the electrode and the base metal acting as the cathode connected to the circuit to generate a potential difference of 200 to 300 volts between the electrodes, thereby heating the surface of the base metal;

[0024] Step (3) is to melt the end of the base material in the form of micro-discharge after power is applied, and the discharge is converted from electrolyte plasma; in the electrolyte flow, the metal droplets at the end of the base material solidify into spherical particles and disperse; at the same time, the horizontal position of the electrolyte is determined according to the desired powder particle size.

[0025] As a preferred embodiment of the present invention, the electrode voltage of 200 to 300 V is controlled according to the radiation temperature of the heating layer on the surface of the cathode base material: when the radiation temperature is 100 to 150°C higher than the melting temperature of the base material, it is adjusted to 200 V; when the radiation temperature is close to the melting point of the base material, a control signal is issued to adjust the voltage to 300 V.

[0026] As a preferred solution of the present invention, the end of the base material is immersed in a flowing alkaline salt solution.

[0027] As a preferred solution of the present invention, the dispersion and spheroidization of the molten metal are achieved in a flowing electrolyte, and the flow direction of the electrolyte is from below the anode to the surface of the workpiece.

[0028] As a preferred solution of the present invention, the powder particles generated by melt dispersion are carried away by the flowing electrolyte and deposited in the groove of the electrolyte discharge channel under the action of gravity.

[0029] A device for producing metal powder, comprising: a vertical spindle with a base material fixing device, a melting chamber at the end of the base material, a rotating spindle and a mechanism for longitudinally moving the base material; a current collector connected to an electric circuit via a cathode mounted on the spindle; a chamber for plasma heating the base material with electrolyte, the chamber being an electrically insulated cone with a conductor at its bottom and holes for the electrolyte to pass through, the conductor at the bottom of the chamber being connected to the electric circuit via an anode; the top of the conical chamber being flush with the end face of the base material; and a hydraulic system for directing the electrolyte flow through the anode to the end of the base material, the process gap between the base material walls, and an annular groove for collecting powder.

[0030] As a preferred embodiment of the present invention, the electrode in the conical chamber has a hole and a photoresistor sensor, the former is used to supply electrolyte, and the latter is used to record radiation from the heated surface of the base material and generate a signal for controlling the electrolyte plasma potential.

[0031] As a preferred solution of the present invention, the hydraulic system that supplies the electrolyte to the end of the base material through the anode adopts an electrolyte radiator to ensure that the temperature is stable in the range of 40 to 60°C.

[0032] As a preferred embodiment of the present invention, the hydraulic system for supplying the electrolyte comprises a chamber for gravity sedimentation, separation of the powder by particle size and its output from the apparatus.

[0033] As a preferred solution of the present invention, the main shaft is installed on a frame, and a water tank is installed at the lower part of the frame. The water tank is equipped with a water pump, a pressure-bearing pipe and a heat exchanger for cooling the electrolyte.

[0034] The beneficial effects of the present invention are:

[0035] 1. The present invention has a simple structure and ingenious design, which can ensure high uniformity of powder size and minimum gas infiltration.

[0036] 2. According to this method, the melting, dispersion and cooling schemes are selected to ensure the spheroidization and rapid crystallization of the powder in the protected medium, reduce gas infiltration and ensure that the powder has a suitable shape.

[0037] 3. The selected dispersion scheme of small-volume base material can produce powder in small batches and can be quickly adjusted to produce different types of powders and powders with different compositions. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a diagram of the equipment for preparing powder according to the present invention.

[0039] Figure 2 This is a microscopic surface morphology photo of the FeAlNi powder taken by a scanning electron microscope in the present invention.

[0040] Figure 3It is a FeAlNi particle size columnar distribution diagram drawn by the present invention based on electron microscope data.

[0041] Figure numerals: frame 1, bracket 2, main shaft 3, motor 4, belt 5, roller 6, air floating support 7, radial air floating bearing 8, axial air floating bearing 9, first pipeline 10, collector 11, pressurizing device 12, first conductor 13, inverter 14, water tank 15, water pump 16, pressure pipe 17, heat exchanger 18, isolation chamber 19, conical chamber-collector 20, second conductor 21, shell 22, groove 23, partition 24, metal cover 25, distributor 26, second pipeline 27, sliding bracket 28, motor 29, sensor 30, base material 31, clamp 32, plasma layer 33. DETAILED DESCRIPTION

[0042] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0043] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0044] The present invention relates to a method for preparing metal powder, comprising the following steps:

[0045] Step (1) feeding the base material into the melting zone and the rotary atomizing unit, melting the end of the base material and ensuring that it is centrifugally atomized by the rotary atomizing unit, obtaining atomized particles, and cooling and solidifying them during rapid motion;

[0046] Step (2) heating and melting the base metal by immersing the end of the base metal in an alkaline salt water electrolyte solution, with the electrolyte solution acting as the anode of the electrode and the base metal acting as the cathode connected to the circuit to generate a potential difference of 200 to 300 volts between the electrodes to heat the surface of the base metal;

[0047] In step (3), the end of the base material is melted in the form of micro-discharge after the current is passed, and the discharge is converted from electrolyte plasma; in the electrolyte flow, the metal droplets at the end of the base material solidify into spherical particles and disperse; at the same time, the position of the electrolyte liquid level can be adjusted and determined according to the size of the particle dispersion layer at the end of the workpiece.

[0048] The heating and melting of the base material is achieved by immersing the end of the base material in an alkaline salt electrolyte solution. The electrolyte solution is the electrode anode, and the base material is the cathode connected to the circuit to generate a potential difference of 200 to 300V between the electrodes.

[0049] The end of the base metal is immersed in an alkaline salt solution flow. The micro-discharge current converted by the electrolyte plasma will heat the surface of the base metal (cathode) until it melts. This feature has been applied to the electrolytic plasma heat treatment process of metal workpieces.

[0050] The dispersion of the melt and the spheroidization of the metal droplets are achieved in the electrolyte flow, which flows from the anode to the surface of the base material. The method of producing metal powder by centrifugal atomization of the base material also has the following characteristics: the metal droplets in the electrolyte (alkaline salt solution) are spheroidized and melted and atomized, and the electrolyte liquid level is controllably adjusted by the size of the dispersion layer at the end of the base material. This ensures that the powdered material particles dispersed after spheroidization and rapid cooling have a narrow particle size distribution. This ensures that the dispersed micropowder has high quality, nanocrystalline structure and the lowest oxygen content.

[0051] The use of the present invention can ensure high quality of the powder product and economical energy consumption for heating and melting the parent material.

[0052] The method for producing nanocrystalline, highly active alloy powders involves melting and dispersing the surface layer of a rotating base metal using centrifugal force. The microdischarge process is activated in the plasma layer between the base metal and the liquid electrode (electrolyte). The microdischarge generates shock waves in the liquid layer of the metal alloy, shattering microdroplets and separating them from the bulk base metal under the action of centrifugal force. The density of the alkaline salt solution is much lower than that of the base metal, allowing the dispersed droplets to be separated from the base metal and rapidly cooled in an electrolyte at a temperature of 40 to 60°C. The proposed method ensures rapid melting of the base metal surface layer and disperses this layer into tiny droplets, which are then instantaneously cooled in a flowing coolant (electrolyte) stream.

[0053] The powder particles generated by the dispersion of the molten base material are carried away by the flow of the electrolyte and deposited in the groove of the electrolyte discharge channel under the action of gravity.

[0054] The equipment for producing metal powder by centrifugal atomization of a base material comprises: a vertical spindle with a base material fixing device, a melting chamber at the end of the base material, a rotating spindle and a longitudinal movement mechanism of the base material, a plasma heater, a powder output and particle size separation system, a feeding and recycling system of a transmission medium; a collector is mounted on the spindle and is connected to an electric circuit via a cathode; a chamber for electrolyte plasma heating of the base material, the chamber being a cone with electrical insulation, an electrode at the bottom of the chamber being connected to an electric circuit via an anode, and its top being located at the level of the end of the base material; a hydraulic system for supplying electrolyte via the anode to the process gap between the end of the base material, the base material wall and an annular groove for collecting the powder.

[0055] The electrode (anode) in the conical chamber has a hole and a photoresistor sensor. The former is used to supply electrolyte, and the latter is used to record the temperature from the heated surface of the base material and generate a signal for controlling the electrolyte plasma potential; the hydraulic system that supplies the electrolyte through the anode to the end of the base material adopts an electrolyte radiator to ensure that the temperature is stable in the range of 40 to 60 ° C.

[0056] The hydraulic system for supplying electrolyte includes a chamber for gravity sedimentation, separating the powder according to particle size and outputting it from the equipment; the main shaft 3 is installed on the frame 1, and a water tank 15 is installed at the bottom of the frame 1, which has a water pump 16, a pressure pipe 17 and a heat exchanger 18 for cooling the electrolyte.

[0057] The method proposed in this invention achieves this by heating the base metal using an electrolyte plasma. Connecting the base metal to an electrical circuit using the cathode of a power supply creates conditions for increased thermal power and a high heating rate. This also allows for the formation of a thin molten layer on the base metal surface, the dispersion of this layer into nearly identical droplets, and the rapid crystallization of these droplets in a liquid (an aqueous alkaline salt solution). Increasing the base metal rotational speed results in smaller metal droplets separating from the base metal, resulting in a more dispersed powder particle size (see Table 1).

[0058] The important features of the proposed method are high productivity, high quality of the powder obtained, and low material and energy costs for powder production. The essence of the invention can be illustrated by the apparatus diagram, Figure 1 This is a full view of the equipment for making powder. Figure 2 The surface morphology of FeAlNi powder was obtained using a scanning electron microscope. Figure 3 It is a particle size distribution histogram of FeAlNi established based on electron microscope data.

[0059] According to the present invention, the method of producing micropowders is achieved by immersing the end of the parent material in an alkaline salt solution (electrolyte), which flows through the holes in the electrode, connected to the circuit by the anode. The parent material is connected to the circuit through the cathode.

[0060] The direction of electrolyte flow from the anode to the cathode aligns with the direction of motion of the charged particles in the electrolyte. Simultaneously, a thin molten layer atomizes and metal droplets spheroidize within the electrolyte. These droplets then detach from the end face of the base metal under the pressure generated by centrifugal force and micro-discharge. Particles in the base metal's dispersed layer are swept away by the electrolyte flow and, under gravity, settle in the troughs of the electrolyte discharge channel. This rapidly cools the dispersed alloy particles and separates them by size in the troughs of the electrolyte discharge channel.

[0061] In summary, this method can produce high-quality micropowders within a narrow particle size range, which is determined by the power density and the rotation speed of the base material.

[0062] For example, the diameter of the nickel-based matrix is ​​50 mm. The end of the matrix is ​​immersed 2 to 3 mm below a layer of electrolyte solution (12% Na2CO3). The matrix is ​​connected to the cathode via a current collector and to an energy converter circuit with a power output of less than 60 kW and an output voltage of 200 to 300 V.

[0063] The base metal heating control system features a photoresistor sensor that receives radiation from the molten layer and sends a signal when the radiation reaches a specified upper limit, reducing the electrode voltage to stabilize the heating process. This control system ensures the formation and dispersion of a thin molten layer on the end face of the base metal, ultimately resulting in a powder with a narrow particle size distribution.

[0064] The mechanical part of the equipment is a vertical spindle with a controllable rotation speed between 1500 and 5000 rpm. It also has electrical contacts to provide power for the atomization of the base metal. The system for delivering electrolyte to the chamber where the base metal is heated by electrolytic plasma consists of an electrically insulating container (tank) with a built-in 250W centrifugal pump. The electrolyte is supplied to the end of the base metal (cathode) via the anode and circulated coolant (electrolyte). The base metal is dispersed between the tank and the chamber and separated by particle size.

[0065] When the 300-volt high voltage is applied, a plasma layer begins to form on the end surface of the parent material, and micro-discharges occur within this layer. Centrifugal force and the discharge voltage cause the molten layer on the parent material's surface to atomize and disperse. The heating and melting of the thin layer generates radiation, which is captured by a photoresistor sensor and converted to a 200-volt voltage. At 200 volts, the heating intensity decreases, and the radiation level on the surface also decreases. The voltage is then switched back to 300 volts to precisely control the heating temperature and form a thin molten layer on the parent material's surface.

[0066] The base metal rotates at 3000 rpm, and discharge activates the melt layer, dispersing the base metal surface to form a fine powder with a narrow particle size distribution of 30 to 100 μm. The controlled movement of the base metal ensures the stability of the heating process and the dispersion of the melt layer, improving powder production efficiency and reducing the energy consumption required for dispersion.

[0067] The optimal processing technology is: the depth of the base material end immersed in the electrolyte is 2 to 3 mm, and the electrolyte flow rate is 0.5 m 3 / h, voltage is 200~300V.

[0068] The melting process of the surface layer at the end of the parent material and the dispersion process of the melt are continuous. According to the intensity of the characteristic radiation and the electrical signal of the sensor, the heating is controlled by changing the voltage between the electrodes; therefore, changing the voltage between the electrodes can enhance the dispersion process and produce powders with different particle sizes. This method is achieved by electrolyte plasma heating. Unlike the plasma heating of the prototype method, electrolyte plasma heating has high efficiency and a heating power density of up to 10 4 W / cm 2 .

[0069] According to the process requirements, the heating voltage and power density can be increased to ensure the dispersion of refractory materials and produce powders of various particle sizes; the electrolyte temperature is controlled in the range of 40-60°C, which is most suitable for the cooling process of electrolyte plasma and melt dispersed particles.

[0070] Specifically, a method and apparatus for producing metal powder is described, which produces metal powder by centrifugally atomizing a molten layer on a base material. Key features of the apparatus include a vertical spindle with a base material fixture, a melting chamber at the end of the base material, a mechanism for rotating the spindle and longitudinally moving the base material, and a plasma heater.

[0071] The apparatus comprises: a spindle 1 equipped with a current collector connected to an electrical circuit via a cathode; and a chamber 2 for performing electrolyte plasma heating on a base material. The base material is an electrically insulated cone with an electrode connected to its bottom and a hole for electrolyte flow. The electrode is connected to the electrical circuit via an anode. The top of the conical chamber is located on the flat surface of the base material end.

[0072] A hydraulic system ensures electrolyte flow through the anode to the end of the base metal, the process gap between the base metal and the electrolyte, and the annular trough for collecting powder. Based on the signal from the temperature sensor at the end of the base metal, the vertical movement of the spindle and chamber is set according to the size of the melt dispersion layer. A photoresistor sensor is placed in the electrolyte flow and measures the thermal radiation from the end of the base metal along the electrode axis. The heating rate of the base metal end is controlled based on the value of the conductive signal, ensuring narrow particle size dispersion, cooling, and separation of the metal droplets.

[0073] Figure 1 Shown is a diagram of the equipment used to implement the proposed method.

[0074] Figure 2 This is a microscopic photograph of FeAlNi powder taken with a scanning electron microscope. The dispersion process speed was 1000 r / min.

[0075] Figure 3This is a histogram of FeAlNi particle size distribution based on electron microscope data. The dispersion process speed is 1000 r / min.

[0076] Figure 2 A scanning electron micrograph shows the morphology of FeAlNi powders, obtained at a speed of 1000 rpm. The dispersed particles demonstrate a spherical shape and high surface roughness, which is attributed to the high cooling rate of the material in the coolant. The higher surface area of ​​the roughened surface allows for rapid heating of the dispersed particles during subsequent coating or component manufacturing.

[0077] Figure 3 This is a graph of FeAlNi particle size distribution based on electron microscope data. The dispersion process was performed at a speed of 1000 rpm. Even at this low speed, the deviation in powder diameter is very low, with the proportion of powder with a particle size of 400-700μm reaching 80%.

[0078] like Figure 1 As described above, the equipment for producing metal powder by centrifugal atomization of a base material is composed as follows: a frame 1, on which a bracket 2 with a main shaft 3 is fixed. The rotation of the main shaft is driven by a motor 4 and a belt 5. The roller 6 in the main shaft is installed on an air-floating support 7. The support has a radial air-floating bearing 8 and an axial air-floating bearing 9. Air is supplied to the support through a first pipe 10. A copper-graphite current collector 11 is installed on the surface of the roller 6 of the main shaft 3, and is spring-pressurized by a pressure device 12. The first wire 13 (negative pole) from the inverter 14 is connected to the current collector.

[0079] A water tank 15 is mounted below the frame 1, equipped with a water pump 16, a pressure pipe 17, and a heat exchanger 18 for cooling the electrolyte. A conical chamber-collector 20, made of a non-conductive material, is attached to an isolation chamber 19 within the water tank, through which the electrolyte flows. The chamber-collector is coaxial with the main shaft and has a metal or graphite anode at its bottom, which is connected to the current converter 14 via a second lead 21 (positive electrode).

[0080] The chamber is housed in a metal housing 22, the lower portion of which faces a trough 23 with a separator 24 for collecting and separating the powder. The separator is positioned above the trough, perpendicular to the electrolyte flow. A metal cover 25 with a neutral gas annular distributor 26 is fixed to the top of the chamber; the gas is supplied via a second pipe 27.

[0081] The spindle assembly 3 is mounted on a sliding bracket 28, which can move along a guide rail perpendicular to the electrolyte level, driven by a motor 29. In the conical chamber - the concentrator 20, a sensor 30 is mounted coaxially with the parent material to detect the radiation amount (heat flow) of the molten layer and issue a control signal.

[0082] Electrolyte is supplied via a pressure pipe through an anode with a through hole and a conical chamber collector 20 to the end of a base metal 31, which is secured to the spindle assembly's shaft 6 by a dedicated fixture 32. Ultimately, current flows from the anode through the electrolyte to the cathode base metal, forming a plasma layer 33 at its end, which enables micro-discharge. The discharge energy of plasma layer 33 melts and activates the base metal end, forming a thin molten layer.

[0083] The specific implementation of the present invention is:

[0084] A test platform is built to verify the effectiveness of the proposed method, such as Figure 1 .

[0085] Example 1:

[0086] The metal powder is produced by centrifugal atomization of a base metal. The base metal is a nickel-based alloy with a diameter of 50 mm. The end of the base metal is immersed 2 to 3 mm below a layer of electrolyte solution (12% Na2CO3 solution). The base metal is connected via the cathode to a power converter circuit with a power output of no more than 60 kW and an output voltage of 200 to 300 V.

[0087] In Example 1, the following parameters are set: the base material rotation speed is in the range of 1000 to 3000 r / min.

[0088] During the experiment, the dispersion of the powder and the percentage of qualified spherical powder were purposefully controlled.

[0089] The test results are shown in Table 1.

[0090] Table 1

[0091]

[0092] Experiments show that as the workpiece rotation speed increases, the dispersion of powder particle size decreases significantly. At a rotation speed of 1000 r / min, the obtained particle size is 200-800 μm, and at a rotation speed of 3000 r / min, the particle size is 20-100 μm. The qualified rate of powder increases with the increase of workpiece rotation speed, reaching 98% at a rotation speed of 3000 r / min.

[0093] Example 2:

[0094] The method (method of heating the end of the base material by electrolyte plasma until it melts) was compared with the prototype method (method and device for producing metal powder by centrifugal atomization) (patent RU 2645169C2) [4].

[0095] The comparative experiments all used nickel-based alloy workpieces with the same dispersion conditions, but the linear speed of the parent material was reduced by 30% and the power of the plasma heating system was lower.

[0096] The experimental results are shown in Table 2.

[0097] Table 2

[0098]

[0099] Compared to the prototype method, the proposed method produced powder with a more uniform particle size and finer particles, achieving the same yield and a 98% pass rate. A comparison of the two process parameters revealed that the proposed method was more economical than the prototype method. During the powder production process, it reduced energy consumption by 80% compared to the prototype method.

[0100] The proposed method can produce finer powders at a lower linear speed of the base material.

[0101] The proposed method is more efficient than the prototype method and is both feasible and versatile for producing small batches of high-quality powders. In embodiments, finer powders can be produced at lower rotational speeds compared to the prototype method. Furthermore, the proposed method can produce rapidly quenched powders with nanocrystalline structures and narrow particle size distributions, which can be used in additive manufacturing and thermal spray processes.

[0102] The above description of the disclosed embodiments will enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one 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 present invention. Therefore, the present invention is not limited to the embodiments shown herein, but is to be embodied in the widest possible manner consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing metal powder, characterized in that: The following steps are involved: Step (1) feeding the base material into the melting zone and the rotary atomizing unit, melting the end of the base material and ensuring that it is centrifugally atomized by the rotary atomizing unit, obtaining atomized particles, and cooling and solidifying them during rapid motion; In step (ii), the heating and melting of the base metal is achieved by immersing the end of the base metal in an alkaline salt water electrolyte solution, with the electrolyte solution acting as the anode of the electrode and the base metal acting as the cathode connected to the circuit to generate a potential difference of 200 to 300 volts between the electrodes, thereby heating the workpiece surface; Step (3) is to melt the end of the base material in the form of micro-discharge after power is applied, and the discharge is converted from electrolyte plasma; in the electrolyte flow, the metal droplets at the end of the base material solidify into spherical particles and disperse. At the same time, the position of the electrolyte level is determined according to the size of the dispersed layer of particles at the end of the base material.

2. The method for producing metal powder according to claim 1, wherein: The electrode voltage of 200-300V is controlled according to the radiation intensity of the heating layer on the surface of the cathode base material: when the radiation temperature is 100-150℃ higher than the melting temperature of the alloy, it is adjusted to 200V; when the radiation temperature is close to the melting point of the alloy, a control signal is issued to adjust the voltage to 300V.

3. The method for producing metal powder according to claim 1, wherein: Immerse the end of the parent material in a stream of alkaline salt solution.

4. The method for producing metal powder according to claim 1, wherein: The dispersion of the melt and the spheroidization of the metal droplets are achieved in the electrolyte flow, and the direction of the electrolyte flow is from under the anode to the surface of the base material.

5. The method for producing metal powder according to claim 1, wherein: The powder particles produced by melt dispersion are carried away by the electrolyte flow and deposited in the groove of the electrolyte discharge channel under the action of gravity.

6. An apparatus for producing metal powder, characterized in that: include: A vertical spindle (3) with a base material fixing device, a melting chamber at the end of the base material, a rotating spindle (3) and a longitudinal movement mechanism of the base material (31); a collector (11) connected to a circuit via a cathode is mounted on the spindle (3); a chamber (20) for performing electrolyte plasma heating on the base material, the chamber (20) is a cone with electrical insulation, an electrode at the bottom of the chamber is connected to the circuit via an anode, the chamber has a hole for passing the electrolyte, an electrode at the bottom of the chamber (20) is connected to the circuit via an anode, and the electrode is connected to the circuit via the anode; the top of the conical chamber is located at the level of the base material end; a hydraulic system is used to flow the electrolyte through the anode to the base material end, the process gap between the base material walls, and the annular groove for collecting powder.

7. The device for producing metal powder according to claim 6, characterized in that: The electrodes in the conical chamber are provided with holes and photoresistor sensors (30), the former for supplying electrolyte and the latter for recording radiation from the heated surface of the parent material and generating signals for controlling the electrolyte plasma potential.

8. The device for producing metal powder according to claim 6, characterized in that: The hydraulic system that supplies electrolyte to the end of the base material through the anode uses an electrolyte radiator to ensure that the temperature is stable in the range of 40 to 60°C.

9. The device for producing metal powder according to claim 6, characterized in that: The hydraulic system for supplying the electrolyte contains chambers for gravity sedimentation, separating the powder by particle size and exporting it from the device.

10. The device for producing metal powder according to claim 6, characterized in that: The main shaft (3) is mounted on a frame (1). A water tank (15) is mounted at the lower portion of the frame (1). The water tank (15) is provided with a water pump (16), a pressure-bearing pipe (17), and a heat exchanger (18) for cooling electrolyte.

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