A high-efficiency silver-based alloy spherical powder preparation atomization equipment

Abstract

The utility model relates to a kind of high-efficiency silver-based alloy spherical powder preparation atomization equipment, belong to non-ferrous metal powder preparation processing field.It is composed of smelting system, atomization system and solidification system from top to bottom;Rotary sealing disc is arranged in the smelting bin with spray nozzle quartz crucible and above it, and rotary sealing disc is connected on the quartz crucible with spray nozzle by screw thread;Rotary motor is connected on rotary sealing disc by center shaft, and rotary motor drives rotary sealing disc, and drives quartz crucible with spray nozzle high-speed rotation;Quartz crucible with spray nozzle is outside high-frequency coil, connects IGBT high-frequency power supply, and laser temperature detector is installed on one side;Flow guide pipe is installed at the bottom of quartz crucible with spray nozzle.The atomization equipment solves the problems such as low yield, brittle multi-element material spherical morphology difference and other problems in the preparation of silver-based alloy superfine powder.

Description

Technical Field

[0001] This utility model belongs to the field of non-ferrous metal powder preparation and processing, specifically relating to a high-efficiency silver-based alloy spherical powder preparation and atomization equipment. Background Technology

[0002] Metal atomization powder production is a powder preparation method that uses a rapidly moving fluid (atomizing medium) to impact or otherwise break down liquid metal or alloy into fine droplets, which are then condensed into solid powder. It is a core process in modern powder metallurgy and additive manufacturing. This technology ensures that the powder has the same homogeneous chemical composition as the molten alloy, and the rapid solidification process refines the powder's crystalline structure, eliminating macroscopic segregation of the second phase. Therefore, metal atomization powder production can precisely control the particle size distribution, sphericity, oxygen content, and flowability of the powder, directly determining the key performance characteristics of downstream products in aerospace, biomedicine, and electronic devices. With the surge in demand for 3D printing, powder metallurgy parts, and high-end coatings, atomization powder production technology is rapidly evolving towards higher purity, ultrafine particles, lower oxygen levels, and narrower particle size distributions.

[0003] Metal atomization powdering methods mainly include gas atomization (atomization of media such as water and oil or electrode induction melting), centrifugal atomization, ultrasonic atomization, and plasma atomization (PA). Gas atomization uses high-pressure inert gas (nitrogen / argon) to impact the molten metal stream through an annular nozzle, tearing it into micron-sized droplets, which are then cooled and solidified in a settling tower. Centrifugal atomization involves feeding the molten metal stream onto a high-speed rotating disk (≥90,000 rpm), where it is atomized into microdroplets under centrifugal force. Ultrasonic atomization uses an ultrasonic transducer (e.g., 40 kHz) to drive the tool head to vibrate, causing the surface molten metal to be "stripped" and atomized. Plasma atomization (PA) uses a high-temperature plasma jet (>10,000 K) to melt and atomize the metal wire. The advantages and disadvantages of the four metal atomization methods are shown in the table below.

[0004] Table 1. Advantages, disadvantages, and applicable fields of four metal atomization methods. Silver-based alloy powders are mostly multi-element alloys (such as AgCuInSn), containing a large number of intermetallic compounds. The melting points of these alloys are generally below 900℃, resulting in a relatively high powder density. Furthermore, the presence of the precious metal Ag increases the material's cost. Silver-based alloy powders are primarily used for packaging and soldering electronic vacuum devices, requiring extremely low oxygen content, narrow particle size distribution, high sphericity, and high single-pass collection efficiency. Currently, domestic manufacturers commonly use gas atomization to prepare silver-based alloy powders. While this meets the needs of mass production, the resulting powders suffer from poor sphericity, high oxygen content (≥500ppm), a wide particle size range, and a low proportion of fine powder (10~20μm), failing to meet the market demand for high-quality spherical silver-based alloy powders. Centrifugal atomization has problems such as low proportion of fine powder (10~20μm), high maintenance cost, and difficulty in preparing high-temperature powder (melting temperature greater than 500℃). Ultrasonic atomization and plasma atomization also have problems such as low efficiency and weak industrialization. Therefore, after comprehensive comparison of the above four metal atomization methods, none of them can meet the requirements for preparing silver alloy spherical powder. Utility Model Content

[0005] The purpose of this invention is to provide an efficient atomization equipment for preparing spherical silver-based alloy powder, which can efficiently prepare alloy powder with concentrated particle size distribution (D90 of 10~20μm), sphericity greater than 0.98, oxygen content less than 50ppm, and powder recovery rate of 99%. This atomization equipment solves the problems of low yield in the preparation of ultrafine silver-based alloy powder and poor spherical morphology of brittle multi-component materials.

[0006] This invention designs an atomization equipment capable of preparing ultrafine metal powders. It achieves high-temperature atomization of silver-based alloy melts through high-frequency induction heating; utilizes a specially designed atomizing quartz crucible to achieve specific atomization angles and droplet sizes; employs a pulsed pressurization system to achieve jet acceleration and initial droplet fragmentation; utilizes a centrifugal rotation system to achieve centrifugal acceleration and secondary droplet fragmentation of the metal droplets; and utilizes a liquid nitrogen deep cooling and solidification system to achieve metal droplet cooling at extremely high degrees. The process involves boiling and cryogenic crushing, followed by solidification into spheres within a very short time. The entire atomization process avoids contact with air and other metal components, ensuring the purity, impurity content, and oxygen content of the silver-based alloy powder. Furthermore, the use of inert gas pressure, centrifugal atomization, and liquid nitrogen environment for crushing and solidification effectively ensures the particle size and sphericity of the powder, resulting in metal powders with excellent sphericity, ideal uniformity, extremely low oxygen content (<100ppm), and high fine powder yield (99% yield of 10~20μm powder). Moreover, this device boasts high production efficiency, eliminating the need for processing into rods; the molten metal is directly atomized to produce ultrafine powders, and continuous feeding is also possible to meet the needs of mass production.

[0007] To achieve the above objectives, this utility model includes the following technical solution: A high-efficiency atomization equipment for preparing spherical silver-based alloy powder comprises three parts: a melting system, an atomization system, and a solidification system. It mainly includes a high-frequency melting chamber, a quartz crucible with a nozzle, a rotating sealing disc and motor, a pulse power supply and high-pressure gas pipeline, a liquid nitrogen tank, a pressure relief valve, and a recovery gas pipeline. High-temperature silver-based alloy melt is obtained through high-frequency induction heating; a specific atomization angle and droplet size are achieved through a specially designed atomizing quartz crucible; a pulse pressurization system achieves jet acceleration and initial droplet fragmentation of the molten metal; a centrifugal rotation system accelerates the metal droplets and performs secondary droplet fragmentation; and a liquid nitrogen deep cooling solidification system enables boiling and cryogenic fragmentation of the metal droplets under extreme supercooling, solidifying them into spheres in a very short time.

[0008] A high-efficiency atomization equipment for preparing spherical silver-based alloy powder comprises, from top to bottom, a melting system, an atomization system, and a solidification system. The main components include a melting chamber, a rotary motor, a first pressure sensor, a gas booster, a high-speed solenoid valve, a high-pressure nitrogen cylinder, a pulse power supply, a central shaft, a rotating sealing disc, a quartz crucible with a nozzle, a high-frequency coil, a laser thermometer, silver-based alloy melt, a guide pipe, a second pressure sensor, a gas storage cylinder, a pressure relief valve and a vacuum pump, a liquid nitrogen tank, liquid nitrogen, an atomization chamber, and a backup tank. The silver-based alloy is heated and melted in the melting system. The alloy melt is then injected into the atomization system through the guide pipe. After atomization, the droplets enter the solidification system and condense to form spherical particles.

[0009] The melting system includes a melting chamber, a rotary motor, a central shaft, a rotary sealing disc, a quartz crucible with a nozzle, a high-frequency coil, a laser thermometer, and a flow guide tube. The rotary motor, central shaft, rotary sealing disc (containing cooling water), quartz crucible with a nozzle, and flow guide tube are arranged sequentially from top to bottom in the melting chamber, wherein the diameter of the flow guide tube is 0.5 mm.

[0010] The melting chamber is equipped with a quartz crucible with a nozzle and a rotating sealing disk on it. The rotating sealing disk is threaded onto the quartz crucible with the nozzle. A rotary motor is connected to the rotating sealing disk through a central shaft. The rotary motor drives the rotating sealing disk to rotate the quartz crucible with the nozzle at high speed. The quartz crucible with the nozzle has an external high-frequency coil connected to an IGBT high-frequency power supply. A laser thermometer is installed on one side for precise temperature measurement. A flow guide tube is installed at the bottom of the quartz crucible with the nozzle.

[0011] The aforementioned quartz crucible with a jet nozzle is made of high-strength quartz glass, with an outer diameter of 200 mm, a wall thickness of 5 mm, and a height of 500 mm. The upper end of the crucible is externally threaded for sealing with a rotating sealing disc. The bottom is arc-shaped and machined with jet nozzles, i.e., guide holes (oblique holes), with a diameter of 0.5 mm, totaling 24 holes arranged circumferentially, each with a circumferential diameter of 10 mm. The center line of the guide holes forms an angle of 11.31° with the central axis of the quartz tube (quartz crucible with jet nozzle). The guide tube is installed on the guide holes.

[0012] The rotating sealing disc is made of high-temperature alloy steel and is sealed to the quartz crucible with a nozzle. It has internal threads at the lower end and an inner diameter of 200mm. The rotating sealing disc is equipped with a cooling water pipe. The central shaft is connected to a rotating motor, and the lower end of the central shaft passes through the rotating sealing disc and is located above the quartz crucible with a nozzle. The central shaft has inlet and outlet high-pressure gas pipes that are connected to high-pressure gas pipelines, which can input high-pressure pulsed gas into the quartz crucible with a nozzle.

[0013] High-frequency melting is performed using an IGBT high-frequency power supply and a connected high-frequency coil. The frequency of the IGBT high-frequency power supply is 20kHz~250kHz. The high-frequency coil is a copper coil with cooling water. A laser thermometer can perform laser infrared temperature measurement with an accuracy of ±5℃. The rotational motor has a speed of 5000~15000rpm, with a set value of 10000~12000rpm. The casting mold is made of high-quality graphite.

[0014] The atomization system includes a high-pressure gas pipeline, a pressure relief pipeline, and an atomization chamber. The atomization chamber is located below the quartz crucible with a nozzle. The silver-based alloy melt in the quartz crucible with a nozzle enters the atomization chamber through a guide pipe. The high-pressure gas flows along the high-pressure gas pipeline, through the hollow central axis, and into the quartz crucible with a nozzle. The pressure relief pipeline is located on the upper side wall of the atomization chamber and leads to the outside of the atomization chamber.

[0015] The high-pressure gas pipeline includes a high-pressure gas pipe, a first pressure sensor, a gas booster, a high-speed solenoid valve, a high-pressure nitrogen cylinder, and a pulse power supply. The first pressure sensor, gas booster, high-speed solenoid valve, and high-pressure nitrogen cylinder are sequentially connected to the high-pressure gas pipeline. The gas booster is connected to and controlled by the pulse power supply. The high-pressure gas is released from the high-pressure nitrogen cylinder, passes sequentially through the high-speed solenoid valve and the gas booster, and flows along the high-pressure gas pipeline, through the hollow central axis, into a quartz crucible with a nozzle.

[0016] The pulse power supply is a high-frequency square wave output with a frequency of 10~30kHz; the response time of the high-speed solenoid valve is ≤1ms and the pressure resistance is ≥10MPa; the high-pressure gas is high-purity nitrogen, and the output pressure of the gas booster is adjustable from 0 to 15MPa; the quartz crucible with a nozzle is equipped with a first pressure sensor with a range of 0~20MPa and an accuracy of ±0.5%FS.

[0017] The pressure relief pipeline includes a pressure relief pipe, a second pressure sensor, a gas storage cylinder, a pressure relief valve, and a suction pump. The second pressure sensor, gas storage cylinder, pressure relief valve, and suction pump are installed on the pressure relief pipe. The pressure relief valve and suction pump can be controlled to release the overpressurized inert gas inside the atomization chamber, achieving the purpose of pressure relief. An external pressure relief pipeline is located above the atomization chamber.

[0018] The pressure relief valve is equipped with a second pressure sensor with a range of 0~20MPa and an accuracy of ±0.5%FS.

[0019] The solidification system includes a liquid nitrogen tank, liquid nitrogen, and a backup tank. The liquid nitrogen tank is connected to the backup tank, and the liquid nitrogen is contained within the liquid nitrogen tank. The liquid nitrogen tank is located at the bottom of the atomization chamber, below the quartz crucible with the nozzle. The vertical distance between the end of the guide pipe and the liquid nitrogen surface in the liquid nitrogen tank is 0.5~1.5m (preferably 1.0m). The bottom of the liquid nitrogen tank is connected to a liquid nitrogen guide pipe, which in turn connects to the backup tank.

[0020] The liquid nitrogen pool has a diameter of 80~150mm, a depth of 0.5~1m, a liquid nitrogen temperature of -196℃, and a height of 1m from the flow guide hole of the quartz crucible with nozzle to the liquid nitrogen pool.

[0021] The silver-based alloy spherical powder of this utility model refers to an Ag-based alloy containing one or more of Cu, In, Sn, Ge, and Ni elements, with a melting temperature of 550℃~850℃. The Ag-based alloy contains 10~50 wt% Cu, 0~30 wt% In, 0~20 wt% Sn, 0~25 wt% Ge, 0~2 wt% Ni, and the balance Ag. The silver-based alloy is prepared in one specific alloy ratio by weight percentage, and the purity of the raw materials is 5N.

[0022] The silver-based alloy spherical powder described above has a particle size distribution D90 of 10~20μm, a sphericity greater than 0.98, an oxygen content of less than 50ppm, and a powder recovery rate of 99%.

[0023] The design principle of this utility model is as follows: 1. This utility model designs an atomization equipment consisting of three parts: a melting system, an atomization system, and a solidification system. It mainly includes a high-frequency melting chamber, a quartz crucible with a nozzle, a rotating sealing disc and motor, a pulse power supply and high-pressure gas pipeline, a liquid nitrogen tank, a pressure relief valve, and a recovery gas pipeline. High-temperature melting of silver-based alloy is achieved through high-frequency induction heating; a specific atomization angle and droplet size are achieved through a specially designed atomizing quartz crucible; a pulse pressurization system is designed to achieve jet acceleration and initial droplet fragmentation of the molten metal; a centrifugal rotation system is designed to achieve centrifugal acceleration and secondary droplet fragmentation of the molten metal; and a liquid nitrogen deep cooling solidification system is designed to achieve boiling and deep-cryogenic fragmentation of the molten metal droplets under extreme supercooling, solidifying them into spheres in a very short time.

[0024] 2. The main process of this utility model's high-efficiency silver-based alloy spherical powder preparation device is as follows: the silver-based alloy is rapidly melted using high-frequency induction heating to achieve a high liquid temperature; under the drive of a high-speed motor, the rotating disk securely rotates the quartz crucible at high speed, ensuring the uniformity of the silver-based multi-element alloy composition; a gas booster controlled by a pulse power supply delivers high-pressure nitrogen from an inert gas cylinder to the quartz crucible at a certain frequency, causing the molten alloy liquid to be pressurized by the high-pressure nitrogen in the quartz crucible, flowing through the guide hole at a certain velocity, and sprayed into the liquid nitrogen pool as droplets at a specific angle, gaining a certain centrifugal acceleration, and undergoing secondary breakage due to centrifugal force; the high-temperature atomized droplets, upon contact with the liquid nitrogen surface in the liquid nitrogen pool, undergo a violent phase transition from "film boiling" to "nuclear boiling" due to extreme supercooling, causing the liquid nitrogen to rapidly vaporize and generate high-pressure nitrogen explosion, tearing the silver-based alloy droplets into smaller fragments; in the liquid nitrogen environment, the silver-based alloy droplets are broken down within milliseconds (approximately 10... - 3 s) Under the influence of surface tension, the droplets shrink into a near-spherical shape and then deposit at the bottom of the liquid nitrogen pool. The advantage of this preparation method is that the silver-based alloy melt, under the action of high-frequency pulsed gas, initially has a uniform droplet size. Through external centrifugation and "boiling + deep cooling" breakup, the droplets are broken into 10~20μm droplets multiple times. Under the influence of liquid nitrogen and surface tension, they solidify and shrink into spheres very quickly. Therefore, the droplet breakup is uniform, resulting in powder with a uniform and concentrated particle size.

[0025] The aforementioned atomization device can harvest spherical alloy powder with a particle size of 10-20 μm, achieving a powder recovery rate of 99%. Throughout the atomization process, there is no contact with air or other metal components, ensuring the purity, impurity content, and oxygen content of the silver-based alloy powder. Furthermore, the use of inert gas pressure, centrifugal atomization, liquid nitrogen environment crushing, and solidification effectively ensures the particle size and sphericity of the powder, resulting in metal powder with excellent sphericity, ideal uniformity, extremely low oxygen content (<100 ppm), and high fine powder yield (99% yield of 10-20 μm powder).

[0026] The beneficial effects of this utility model are as follows: The atomizing device developed in this invention differs from traditional gas atomization, centrifugal atomization, ultrasonic atomization, and plasma atomization preparation devices in that it does not use airflow to break up molten metal, thus avoiding a large particle distribution range and low sphericity due to airflow turbulence; nor does it come into contact with other external factors such as centrifugal discs, ultrasonic devices, or high-temperature ion impacts, which could lead to powder contamination. It also avoids the powder solidification process being affected by external gases, preventing collisions, satellite spheres, agglomeration, and multi-sphere adhesion, reducing the risk of powder being drawn in by high-pressure gases, and lowering the risk of gas explosions in confined spaces.

[0027] The silver-based alloy spherical powder prepared by the atomization device of this invention has excellent sphericity and ideal uniform particle size. By changing the melt temperature, gas injection pressure, centrifugal speed, etc., the powder particle size range can be precisely controlled. In addition, the oxygen content of the powder is extremely low (<100ppm) and the fine powder yield is high (10~20μm powder yield reaches 99%).

[0028] The silver-based alloys prepared by the atomization device of this invention generally refer to Ag-based alloys containing one or more of Cu, In, Sn, Ge, and Ni elements, with a solid-liquid phase temperature range of 550℃ to 850℃. They cover all conventional silver-based alloy products, such as AgCu28 eutectic alloy, AgCu28Ni2 alloy, AgCu27In10 alloy, AgCu30Sn10 alloy, AgCu22.4In13Sn7 alloy, AgCu42Ge5 alloy, etc.

[0029] This utility model designs and provides a novel atomization equipment, accompanied by complete design schematics. It clearly defines the requirements for key device selection and provides detailed data on core parameters, meeting the needs of actual industrial production. Furthermore, this device boasts high production efficiency; it eliminates the need for processing into rods, directly atomizing molten metal to prepare ultra-fine powder. It also allows for continuous feeding, meeting the demands of mass production. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the cryogenic crushing high-efficiency atomization equipment in Example 1; Figure 2 Electron micrograph of the silver-based alloy spherical powder prepared in Example 1; Figure 3 The particle size distribution curve of the silver-based alloy spherical powder prepared in Example 1.

[0031] Explanation of key figure labels: 1-Smelting chamber 1, 2-Rotary motor, 3-First pressure sensor, 4-Gas booster 4, 5-High-speed solenoid valve, 6-High-pressure nitrogen cylinder, 7-Pulse power supply, 8-Central shaft, 9-Rotary sealing disc, 10-Quartz crucible with nozzle, 11-High-frequency coil, 12-Laser thermometer, 13-Silver-based alloy melt, 14-Guide pipe, 15-Second pressure sensor, 16-Gas storage cylinder, 17-Pressure relief valve and vacuum pump, 18-Liquid nitrogen pool, 19-Liquid nitrogen, 20-Atomization chamber, 21-Spare pool. Detailed Implementation

[0032] Example 1: Cryogenic Crushing and High-Efficiency Atomization Equipment like Figure 1 As shown, the cryogenic crushing high-efficiency atomization equipment of this utility model consists of three parts from top to bottom: a melting system ⅰ, an atomization system ⅱ, and a solidification system ⅲ. It includes a melting chamber 1, a rotary motor 2, a first pressure sensor 3, a gas booster 4, a high-speed solenoid valve 5, a high-pressure nitrogen cylinder 6, a pulse power supply 7, a central shaft 8, a rotating sealing disc 9, a quartz crucible with a nozzle 10, a high-frequency coil 11, a laser thermometer 12, a silver-based alloy melt 13, a guide pipe 14, a second pressure sensor 15, a gas storage cylinder 16, a pressure relief valve and a vacuum pump 17, a liquid nitrogen pool 18, liquid nitrogen 19, an atomization chamber 20, and a spare pool 21. The silver-based alloy is heated and melted in the melting system ⅰ. The silver-based alloy melt 13 is injected into the atomization system ⅰⅰ through the guide pipe 14. After atomization, the droplets enter the solidification system ⅰⅰⅰ and condense to form spherical particles.

[0033] The melting system i includes a melting chamber 1, a rotary motor 2, a central shaft 8, a rotary sealing disc 9, a quartz crucible with a nozzle 10, a high-frequency coil 11, a laser thermometer 12, and a flow guide pipe 14, etc. The rotary motor 2, the central shaft 8, the rotary sealing disc 9 (containing cooling water), the quartz crucible with a nozzle 10, and the flow guide pipe 14 are arranged from top to bottom in the melting chamber 1, wherein the diameter of the flow guide pipe is 0.5 mm.

[0034] The melting chamber 1 is equipped with a quartz crucible 10 with a nozzle and a rotating sealing disk 9 on it. The rotating sealing disk 9 is threadedly connected to the quartz crucible 10 with a nozzle. The rotary motor 2 is connected to the rotating sealing disk 9 through a central shaft 8. The rotary motor 2 drives the rotating sealing disk 9 to drive the quartz crucible 10 with a nozzle to rotate at high speed. The quartz crucible 10 with a nozzle has an external high-frequency coil 11 connected to an IGBT high-frequency power supply. A laser thermometer 12 is installed on one side for accurate temperature measurement. The flow guide tube 14 is installed at the bottom of the quartz crucible 10 with a nozzle.

[0035] The quartz crucible 10 with a nozzle is made of high-strength quartz glass, with an outer diameter of 200 mm, a wall thickness of 5 mm, and a height of 500 mm. The upper end of the crucible is externally threaded to seal against the rotating sealing disc 9. The bottom is arc-shaped and machined with nozzles, i.e., guide holes (oblique holes), with a diameter of 0.5 mm. There are 24 such holes arranged circumferentially, with a circumferential diameter of 10 mm. The center line of the guide holes forms an angle of 11.31° with the central axis of the quartz tube (quartz crucible 10 with nozzle). The guide tube 14 is installed on the guide holes.

[0036] The rotating sealing disc 9 is made of high-temperature alloy steel, with internal threads at the lower end and an inner diameter of 200mm, and is sealed to fit with the quartz crucible 10 with a nozzle. The rotating sealing disc 9 is equipped with a cooling water pipeline. The central shaft 8 is connected to the rotating motor 2, and the lower end of the central shaft 8 passes through the rotating sealing disc 9 and enters the upper part of the quartz crucible 10 with a nozzle. The central shaft 8 is equipped with inlet and outlet high-pressure gas pipelines, which are connected to high-pressure gas pipelines, and can input high-pressure pulse gas into the quartz crucible 10 with a nozzle.

[0037] High-frequency melting is performed using an IGBT high-frequency power supply and a high-frequency coil 11 connected to it. The power of the IGBT high-frequency power supply is 20kHz~250kHz. The high-frequency coil 11 is a copper coil with cooling water. The laser thermometer 12 can perform laser infrared temperature measurement with an accuracy of ±5℃. The rotation speed of the rotary motor 2 is 5000~15000rpm, and the set value is 10000~12000rpm.

[0038] The atomization system ii includes a high-pressure gas pipeline, a pressure relief pipeline, and an atomization chamber 20. The atomization chamber 20 is located below the quartz crucible 10 with a nozzle. The silver-based alloy melt 13 in the quartz crucible 10 with a nozzle enters the atomization chamber 20 through the guide pipe 14. The high-pressure gas flows along the high-pressure gas pipeline, through the hollow central axis 8, and into the quartz crucible 10 with a nozzle. The pressure relief pipeline is located on the upper side wall of the atomization chamber 20 and leads to the outside of the atomization chamber 20.

[0039] The high-pressure gas pipeline includes a high-pressure gas pipe, a first pressure sensor 3, a gas booster 4, a high-speed solenoid valve 5, a high-pressure nitrogen cylinder 6, and a pulse power supply 7. The first pressure sensor 3, gas booster 4, high-speed solenoid valve 5, and high-pressure nitrogen cylinder 6 are sequentially connected to the high-pressure gas pipe. The gas booster 4 is connected to and controlled by the pulse power supply 7. High-pressure gas is released from the high-pressure nitrogen cylinder 6, passes sequentially through the high-speed solenoid valve 5 and the gas booster 4, travels along the high-pressure gas pipeline, through the hollow central axis 8, and enters the quartz crucible 10 with a nozzle.

[0040] The pulse power supply 7 outputs a high-frequency square wave with a frequency of 10~30kHz; the high-speed solenoid valve 5 has a response time of ≤1ms and a pressure resistance of ≥10MPa; the high-pressure gas is high-purity nitrogen, and the gas booster output pressure is adjustable from 0 to 15MPa; the quartz crucible 10 with a nozzle is equipped with a first pressure sensor 3 with a range of 0~20MPa and an accuracy of ±0.5%FS.

[0041] The pressure relief pipeline includes a pressure relief pipe, a second pressure sensor 15, a gas storage cylinder 16, a pressure relief valve, and a vacuum pump 17. The pressure relief pipe is equipped with the second pressure sensor 15, the gas storage cylinder 16, the pressure relief valve, and the vacuum pump 17. By controlling the pressure relief valve and the vacuum pump 17, the overpressurized inert gas inside the atomizing chamber 20 can be released, achieving the purpose of pressure relief. An external pressure relief pipeline is located above the atomizing chamber 20.

[0042] The pressure relief valve is equipped with a second pressure sensor 15, with a range of 0~20MPa and an accuracy of ±0.5%FS.

[0043] The solidification system iii includes a liquid nitrogen tank 18, liquid nitrogen 19, and a backup tank 21. The liquid nitrogen tank 18 is connected to the backup tank 21, and the liquid nitrogen 19 is contained in the liquid nitrogen tank 18. The liquid nitrogen tank 18 is located at the bottom of the atomization chamber 20, below the quartz crucible 10 with the nozzle. The vertical distance between the end of the guide pipe 14 and the liquid nitrogen surface in the liquid nitrogen tank 18 is 0.5~1.5m, preferably 1.0m. The bottom of the liquid nitrogen tank 18 is connected to a liquid nitrogen guide pipe, which is connected to the backup tank 21.

[0044] The liquid nitrogen pool 18 has a diameter of 80~150mm, a depth of 0.5~1m, and a liquid nitrogen temperature of -196℃. The height from the flow guide hole of the quartz crucible 10 with the nozzle to the liquid nitrogen pool 18 is 1m.

[0045] High-frequency melting consists of an IGBT high-frequency power supply and a copper coil (with cooling water). The high-frequency power supply is 20kHz~250kHz. Laser infrared thermometry, with an accuracy of ±5℃; The rotary motor has a speed of 5000~15000rpm, and the set value is 10000~12000rpm; The pulse power supply outputs a high-frequency square wave with a frequency of 10~30kHz. High-speed solenoid valve response time ≤1ms, pressure resistance ≥10MPa; The high-pressure gas is high-purity nitrogen, and the gas booster output pressure is adjustable from 0 to 15 MPa. The quartz crucible is equipped with a pressure sensor with a range of 0~20MPa and an accuracy of ±0.5%FS; The liquid nitrogen pool has a diameter of 80~150mm, a depth of 0.5~1m, a liquid nitrogen temperature of -196℃, and a height of 1m from the quartz crucible guide hole to the liquid nitrogen pool. The pressure relief valve is equipped with a pressure sensor with a range of 0~20MPa and an accuracy of ±0.5%FS.

[0046] The formation and breakage process of silver-based alloy powder during atomization is as follows: ① For the initial crushing, pulsed high-pressure jetting of molten silver-based alloy droplets; ② This refers to the secondary crushing process, where silver-based alloy molten droplets are split off under centrifugal acceleration. ③ This refers to the silver-based alloy molten droplets that break apart due to "film boiling" under extreme supercooling. ④ This is a cryogenic crushing process. The rapid vaporization of liquid nitrogen generates high-pressure nitrogen gas explosion, which then achieves "nuclear boiling" and splits into silver-based alloy molten droplets; these droplets shrink into near-spherical powders due to surface tension.

[0047] Example 2: Preparation of silver-based alloy spherical powder The main process of this high-efficiency silver-based alloy spherical powder preparation method is as follows: alloy preparation, high-frequency induction melting, pulsed pressurized umbrella-shaped injection, boiling crushing + ultra-fast solidification, and ultrasonic vibration sieving.

[0048] (1) Prepare raw materials Select 5N Ag and Cu blocks to prepare AgCu28 alloy with a melting point of 779℃, Cu content of 28 wt%, and Ag balance; feed 15 kg of material, of which 10.8 kg is Ag and 4.2 kg is Cu. (2) Preparation of alloy ingot blanks Alloy ingots were prepared using a vacuum medium-frequency induction furnace. All the raw materials weighed in step I were placed into an alumina crucible; the furnace lid was closed, and a vacuum was drawn to 10°C. -1 Pa, turn on vacuum medium frequency induction heating, heating power 25KW; after the metal material is completely melted, cool down to the refining temperature of 900℃, hold for 12min, and cast into a high-temperature graphite mold; after cooling to room temperature, take samples to test the alloy composition and impurities, and obtain an ingot billet with a diameter of 120mm.

[0049] (3) Preparation of silver-based alloy spherical powder by atomization Powder preparation was carried out using the cryogenic crushing high-efficiency atomization equipment described in Example 1. 5N Ag and Cu blocks were weighed according to the designed component ratio and placed into a quartz crucible with a nozzle. The crucible was then secured with a rotating sealing plate. The high-frequency melting chamber was closed and evacuated to 10°C. -1Pa; turn on heating, heating power 120kHz, observe that the billet is completely melted, cool down to 1100℃, hold for 5min, and turn on atomization. First, the centrifugal motor is turned on to drive the rotating sealing disc, which in turn drives the quartz crucible to rotate at high speed. When the rotation speed reaches 10,000 rpm, the pulse power supply is turned on with a pulse frequency of 20 kHz. The pulse high-pressure gas enters the quartz crucible along the pipeline with a gas pressure of 1 MPa. The molten metal alloy liquid flows from the bottom guide hole of the quartz crucible. Under the action of the pulse high-pressure gas, the alloy solution passes through the guide hole and becomes liquid particles, thus achieving primary liquid crushing. Then, under the dual action of rotational centrifugal force and pulse pressure, secondary crushing is completed. The droplet velocity is 210 m / s, the angle is 11.31°, and the centrifugal speed is 10,000 rpm. The liquid is sprayed into the atomization chamber and falls into the liquid nitrogen pool below. The liquid nitrogen pool has a diameter of 100 mm and a depth of 1 m. According to the Weber number formula (1), the surface tension coefficient (σ) of AgCu28 melt is 1100 N / m, and the fluid density (ρ) is 8.5 kg / m³. 3 The characteristic flow velocity is 210 m / s, the characteristic length is 1.02 m, and the We value is 347. Under extreme temperature difference, it undergoes instantaneous third boiling and breakup; and under the influence of supercooling and surface tension, it undergoes cryogenic breakup, with the broken droplets rapidly solidifying into metallic spherical particles; accompanied by an increase in air pressure inside the atomization chamber, once the air pressure exceeds 10... 3 At pressure relief valve 1, high-purity nitrogen gas enters the storage chamber via the recovery gas pipeline and can be recycled. After atomization is complete, stop the rotary motor and pulse power supply. After the remaining liquid nitrogen in the liquid nitrogen tank is transferred to the backup tank, collect the silver-based alloy powder. Using ultrasonic vibration, the powder is passed through 20μm and 10μm sieves to obtain spherical alloy powder with a particle size range of 10-20μm, achieving a collection rate of 99.5%. Electron micrographs of the powder are shown below. Figure 2 As shown, the ratio of major to minor axis is <1.1, and the sphericity is 98%. The particle size distribution is as follows: Figure 3 As shown, the D90 of the silver-based alloy spherical powder is ≤10.9μm.

[0050] The chemical composition, Weber number, oxygen content, particle size distribution, sphericity, and collection rate of the silver-based alloy spherical powder prepared in Example 2 were tested, and the comprehensive experimental data are shown in Table 2.

[0051] Table 2 Experimental Data Electron micrographs of the silver-based alloy spherical powder prepared according to Example 2 using the atomization equipment of Example 1 of this utility model show that the powder has a high degree of sphericity, a particle size of about 10 μm, and a metastable microstructure on the solidified surface of the powder. The crystals are ultrafine and uniformly distributed.

[0052] This invention relates to a high-efficiency atomization equipment for preparing spherical silver-based alloy powder. The atomization equipment consists of three parts: a melting system, an atomization system, and a solidification system. It mainly includes a high-frequency melting chamber, a quartz crucible with a nozzle, a rotating sealing disc and motor, a pulse power supply and high-pressure gas pipeline, a liquid nitrogen tank, a pressure relief valve, and a recovery gas pipeline. Silver-based alloys generally refer to Ag-based alloys containing one or more of Cu, In, Sn, Ge, and Ni elements, with an alloy melting temperature of 550℃~850℃. The preparation method mainly includes alloy preparation, high-frequency induction melting, pulsed pressurized umbrella-shaped spraying, boiling (cryogenic) crushing + ultra-fast solidification, and ultrasonic vibration sieving. This device can efficiently prepare alloy powder with a concentrated particle size distribution (D90 of 10~20μm), a sphericity greater than 0.98, an oxygen content less than 50ppm, and a powder recovery rate of 99%. This atomization equipment solves the problems of low yield and poor spherical morphology in the preparation of ultra-fine silver-based alloy powder.

[0053] The above embodiments only illustrate the silver-based alloy spherical powder of this utility model. In the above technical solution of this utility model, the alloy ratio and key parameters of the preparation method of the silver-based alloy spherical powder can be freely selected within the specified range, and will not be listed one by one here. Therefore, the technical solutions contained in the above description should be regarded as illustrative and not used to limit the patent application of this utility model.

Claims

1. A high-efficiency atomization equipment for preparing silver-based alloy spherical powder, characterized in that: The system comprises, from top to bottom, a melting system, an atomization system, and a solidification system. The silver-based alloy is heated and melted in the melting system. The molten alloy is then injected into the atomization system via a guide pipe. After atomization, the droplets enter the solidification system and condense to form spherical particles. The melting system includes a melting chamber, a rotary motor, a central shaft, a rotary sealing disc, a quartz crucible with a nozzle, a high-frequency coil, a laser thermometer, and a guide pipe. The melting chamber contains, from top to bottom, a rotary motor, a central shaft, a rotary sealing disc, a quartz crucible with a nozzle, and a guide pipe. Inside the melting chamber is a quartz crucible with a nozzle and a rotary sealing disc, which is threaded onto the crucible. The rotary motor is connected to the rotary sealing disc via the central shaft, driving the rotary sealing disc to rotate the quartz crucible with a nozzle at high speed. An external high-frequency coil is mounted on the quartz crucible with a nozzle, connected to an IGBT high-frequency power supply, and a laser thermometer is installed on one side. The guide pipe is installed at the bottom of the quartz crucible with a nozzle.

2. The high-efficiency silver-based alloy spherical powder preparation atomization equipment according to claim 1, characterized in that: The aforementioned quartz crucible with nozzles is made of high-strength quartz glass; the upper end of the crucible is externally threaded to seal with the rotating sealing disc; the bottom is arc-shaped and machined with nozzles, i.e., guide holes, a total of 24, which are distributed in a circle, with the center line of the guide holes forming an angle of 11.31° with the central axis of the quartz tube.

3. The high-efficiency silver-based alloy spherical powder preparation atomization equipment according to claim 1, characterized in that: The rotating sealing disc is made of high-temperature alloy steel and is sealed to the quartz crucible with a nozzle. The lower end is threaded. The rotating sealing disc is equipped with a cooling water pipe. The central shaft is connected to a rotating motor, and the lower end of the central shaft passes through the rotating sealing disc and is located above the quartz crucible with a nozzle. The central shaft is equipped with inlet and outlet high-pressure gas pipes, which are connected to high-pressure gas pipelines, allowing high-pressure pulsed gas to be input into the quartz crucible with a nozzle.

4. The high-efficiency silver-based alloy spherical powder preparation atomization equipment according to claim 1, characterized in that: The frequency of the IGBT high-frequency power supply is 20kHz~250kHz; the high-frequency coil is a copper coil with cooling water; the laser thermometer can perform laser infrared temperature measurement with an accuracy of ±5℃; the rotation speed of the rotary motor is 5000~15000rpm, and the set value is 10000~12000rpm.

5. The high-efficiency silver-based alloy spherical powder preparation atomization equipment according to claim 1, characterized in that: The atomization system includes a high-pressure gas pipeline, a pressure relief pipeline, and an atomization chamber. The atomization chamber is located below the quartz crucible with a nozzle. The silver-based alloy melt in the quartz crucible with a nozzle enters the atomization chamber through a guide pipe. The high-pressure gas flows along the high-pressure gas pipeline, through the hollow central axis, and into the quartz crucible with a nozzle. The pressure relief pipeline is located on the upper side wall of the atomization chamber and leads to the outside of the atomization chamber.

6. The high-efficiency silver-based alloy spherical powder preparation atomization equipment according to claim 5, characterized in that: The high-pressure gas pipeline includes a high-pressure gas pipe, a first pressure sensor, a gas booster, a high-speed solenoid valve, a high-pressure nitrogen cylinder, and a pulse power supply. The first pressure sensor, the gas booster, the high-speed solenoid valve, and the high-pressure nitrogen cylinder are sequentially installed and connected on the high-pressure gas pipe. The gas booster is connected to and controlled by the pulse power supply. The high-pressure gas pipeline is connected to one side of the central shaft. High-pressure gas is released from the high-pressure nitrogen cylinder and passes sequentially through the high-speed solenoid valve and the gas booster. It then travels along the high-pressure gas pipeline, through the hollow central shaft, and into a quartz crucible with a nozzle.

7. The high-efficiency silver-based alloy spherical powder preparation atomization equipment according to claim 5, characterized in that: The pressure relief pipeline includes a pressure relief pipe, a second pressure sensor, a gas storage cylinder, a pressure relief valve, and a vacuum pump. The second pressure sensor, the gas storage cylinder, the pressure relief valve, and the vacuum pump are installed on the pressure relief pipe. The pressure relief valve and the vacuum pump can be controlled to release the inert gas in the atomization chamber after overpressure, thereby achieving the purpose of pressure relief.

8. The high-efficiency silver-based alloy spherical powder preparation atomization equipment according to claim 6, characterized in that: The pulse power supply is a high-frequency square wave output with a frequency of 10~30kHz; the high-speed solenoid valve has a response time ≤1ms and a pressure resistance ≥10MPa; the high-pressure gas is high-purity nitrogen, and the gas booster output pressure is adjustable from 0~15MPa; the first pressure sensor has a range of 0~20MPa and an accuracy of ±0.5%FS; the second pressure sensor has a range of 0~20MPa and an accuracy of ±0.5%FS.

9. The high-efficiency silver-based alloy spherical powder preparation atomization equipment according to claim 8, characterized in that: The solidification system includes a liquid nitrogen tank, liquid nitrogen, and a backup tank. The liquid nitrogen tank is connected to the backup tank, and the liquid nitrogen is contained in the liquid nitrogen tank.

10. The high-efficiency silver-based alloy spherical powder preparation atomization equipment according to claim 9, characterized in that: The liquid nitrogen pool has a diameter of 80~150mm, a depth of 0.5~1m, a liquid nitrogen temperature of -196℃, and the height from the flow guide hole of the quartz crucible with nozzle to the liquid nitrogen pool is 0.5~1.5m.

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