Preparation system of micron-sized metal powder
By combining micro-mixing, atomization nucleation, and solution growth processes, the problems of high cost, numerous impurities, and low yield in the production of micron-sized metal powders in traditional methods have been solved. This enables the preparation of micron-sized metal powders at low cost, in large batches, and with controllable morphology, and is suitable for the preparation of powders with specific morphologies and multi-component composites.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- THE 718TH RES INST OF CHINA STATE SHIPBUILDING CORP
- Filing Date
- 2025-12-31
- Publication Date
- 2026-05-19
AI Technical Summary
Existing technologies struggle to achieve controllable morphology and monodispersity of micron-sized metal powders in low-cost, high-volume production. Traditional methods suffer from high energy consumption, numerous impurities, and low yield.
By employing a combination of micro-mixing, atomization nucleation, and solution growth processes, the micro-mixer enables rapid and uniform mixing of metal precursors and reducing agents, while the atomization device forms micron-sized droplets as independent reactors. Combined with laminar flow or electric field control of the nucleation process, precise control of powder composition, morphology, and size is achieved.
It enables low-cost, high-volume production of micron-sized metal powders, which have the advantages of controllable morphology, uniform size, and continuous production. It is particularly suitable for the preparation of powders with specific morphologies and multi-component composites.
Smart Images
Figure CN122057901A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of advanced powder material preparation technology, specifically relating to a preparation system for micron-sized metal powders. Background Technology
[0002] Micron-sized metal powders have important applications in electronic pastes, 3D printing, catalysis, and medicine. Traditional methods for preparing micron-sized metal powders have many limitations. Among them, chemical reduction methods have simple equipment, low cost, and controllable morphology, but the products contain trace impurities and have a dispersed particle size distribution; gas atomization methods have high sphericity and are suitable for mass production, but have high energy consumption and cannot produce specific morphologies; ball milling methods have wide applicability, high output, and low cost, but low efficiency and introduce impurities; vapor deposition methods have high purity and narrow particle size distribution, but low output, high cost, and are not suitable for large-scale production.
[0003] Currently, micron-sized metal powders prepared by a single method cannot meet the practical production customization requirements such as low cost, large batch, controllable morphology, and monodispersity. Therefore, there is an urgent need to develop a more comprehensive method for preparing metal powders. Summary of the Invention
[0004] This invention provides a system for preparing micron-sized metal powders. Through an innovative combination of micro-mixing, atomization nucleation, and solution growth processes, it achieves precise control over the powder composition, morphology, and size, while also offering advantages such as low cost, uniform size, and continuous production.
[0005] Specifically, the present invention provides the following technical solutions: A system for preparing micron-sized metal powder includes a raw material system, a gas supply system, and an atomizing tower; The atomizing tower includes an atomizing chamber, a droplet collector is provided at the bottom of the atomizing chamber, a reaction vessel is provided below the droplet collector, and the outlet of the droplet collector is connected to the inlet of the reaction vessel; The atomization chamber is equipped with a micro-mixer and an atomizing device. The micro-mixer includes a sol-generating unit and a droplet-generating unit. The inlet of the sol-generating unit is connected to the raw material system, the outlet of the sol-generating unit is connected to the inlet of the droplet-generating unit, and the outlet of the droplet-generating unit is connected to the inlet of the atomizing device. The droplet-generating unit is also equipped with a first gas inlet, which is connected to the gas supply system.
[0006] In this invention, the raw material system includes a metal precursor raw material and a reducing agent raw material. The metal precursor raw material and the reducing agent raw material are respectively connected to the inlet of the sol-gel generation unit. The metal precursor solution and the reducing agent are fed into the sol-gel generation unit of the micro-mixer in a certain proportion. The micro-mixer replaces the dispersant in traditional chemical reduction methods, achieving rapid and uniform mixing of the precursor and reducing agent to form a homogeneous and stable sol. However, the application of micro-mixers in the reduction preparation of metal powders also faces problems such as solid particles clogging microchannels and difficulty in scaling up production. To address these issues, the sol-gel generation unit of the micro-mixer in this invention utilizes heart-shaped / cross-finger-shaped flow channels, widens them to millimeter-level channels, and employs hydrophobic materials, ensuring that it only performs mixing functions without producing sediment to prevent clogging.
[0007] Simultaneously, the droplet generation unit of the micro-mixer of this invention introduces an inert gas as a continuous phase, dividing the uniform and stable sol fluid from the sol generation unit into discrete droplets. Then, an atomizing device breaks the uniformly mixed droplets into countless micron-sized droplets with uniform height. Each droplet becomes a tiny, independent "reactor." These micron-sized droplets float within the atomizing tower and fall under gravity, allowing the metal powder to nucleate uniformly during this process. A bottom droplet collector collects the droplets while simultaneously venting the gas. The droplets further reach the bottom reaction vessel, where, by controlling the reaction time and temperature, the metal nuclei continue to grow, yielding the desired metal powder.
[0008] Preferably, the sol-gel generation unit consists of a main channel and several heart-shaped or interdigitated channels spaced apart on the main channel, wherein the diameter of the heart-shaped or interdigitated channels is half the diameter of the main channel. This invention utilizes heart-shaped / interdigitated channels to continuously separate and polymerize the fluid, improving mixing efficiency, shortening mixing time, and preventing the metal precursor and reducing agent from reacting and forming precipitates that clog the channels during the mixing stage.
[0009] More preferably, the diameter of the main channel is 1-5 mm; And / or, the micromixer is made of polytetrafluoroethylene. The micromixer of this invention, by employing millimeter-level flow channels and hydrophobic materials, further avoids the formation of sediment, thus enabling it to perform only a mixing function.
[0010] To prevent collisions between micron-sized droplets due to turbulence during their descent, this invention utilizes laminar flow or an electric field to provide a stable, isothermal, inert flow field. During this process, the metal powder undergoes uniform nucleation, and the descent time is the uniform nucleation time. Specifically: In a preferred embodiment, a gas distributor is provided at the top of the atomizing chamber, and a second gas inlet is provided on the tower body above the gas distributor, the second gas inlet being connected to the gas supply system. The gas distributor causes the airflow inside the tower to form laminar flow to prevent collisions between droplets.
[0011] In another preferred embodiment, an electrode plate is respectively provided at the top and bottom of the atomization chamber, and the atomization device is an electrostatic atomization device. The electrostatic atomization device uses electrostatic force to stretch and break the liquid flow into charged micron-sized droplets. Each droplet carries the same charge, and because they carry the same charge, they repel each other, fundamentally preventing collisions and aggregation. Two electrode plates of different polarities are respectively installed at the top and bottom of the atomization chamber, forming a uniform electric field that controls the falling speed of the charged droplets, thereby controlling the degree of crystal nucleus growth.
[0012] Preferably, the atomizing tower is covered with an external heat tracing layer and a tower insulation layer in sequence to provide a constant temperature environment for the atomizing tower.
[0013] Preferably, a heater is also included; the pipeline connecting the gas supply system to the first gas inlet and the pipeline connecting the raw material system to the inlet of the sol generation unit both pass through the heater. The metal precursor, reducing agent, and compressed gas need to be heated to a set temperature by the heater before entering the micromixer. The heater can be, but is not limited to, electric heating, water / oil bath, or laser irradiation.
[0014] Preferably, the system also includes a separation system, a washing system, and a drying system connected in sequence. The inlet of the separation system is connected to the outlet of the reactor. The metal powder obtained from the reactor growth is sequentially passed through the separation system, washing system, and drying system for solid-liquid separation, washing, and drying to obtain micron-sized metal powder products.
[0015] The beneficial effects of this invention are at least as follows: 1) The present invention provides a micron-scale metal powder preparation system that inherits the advantages of low cost and controllable morphology of chemical reduction method. It achieves instantaneous and uniform mixing of metal precursors through micro mixer and forms a micro "reactor" through atomization device. It overcomes the shortcomings of insufficient particle size dispersion and low purity of existing technology, and has the characteristics of large-scale and continuous production. 2) The present invention provides a micron-sized metal powder preparation system, which has the advantages of low cost, uniform size, controllable morphology and continuous production, and is particularly suitable for the controllable preparation of powders with specific morphology and multi-component composite powders; 3) The present invention provides a micron-scale metal powder preparation system, wherein the micro mixer uses a heart-shaped flow channel / cross-finger flow channel to continuously separate and aggregate the fluid, thereby improving the mixing efficiency, shortening the mixing time, and avoiding the reaction between the metal precursor and the reducing agent during the mixing stage to generate precipitates that block the flow channels; 4) The present invention provides a micron-sized metal powder preparation system. In order to prevent collisions between droplets caused by turbulence interference during the falling of micron-sized droplets, a stable and constant-temperature inert flow field is provided by laminar flow or electric field, in which metal powder is uniformly nucleated. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the structure of a micron-scale metal powder preparation system in Example 1; Figure 2 This is a schematic diagram of the atomizing tower in a micron-scale metal powder preparation system of Example 1; Figure 3 This is a schematic diagram of the micromixer in a micron-scale metal powder preparation system according to Example 1; Figure 4 This is an electron microscope image of the metal powder prepared by a micron-scale metal powder preparation system in Example 1; Figure 5 This is a schematic diagram of the atomizing tower in a micron-scale metal powder preparation system according to Example 2; Figure 6 This is an electron microscope image of the metal powder prepared by a micron-scale metal powder preparation system in Example 2; In the diagram above, 1. Raw material system; 1-1. Metal precursor raw material; 1-2. Reducing agent raw material; 2. Gas supply system; 3. Atomizing tower; 4. Separation system; 5. Washing system; 6. Drying system; 7. First heater; 8. Second heater; 9. Droplet collector; 10. Reactor; 11. Micromixer; 12. Atomizing device; 13. Gas distributor; 14. Positive electrode plate; 15. Negative electrode plate. Detailed Implementation
[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in the art, or in accordance with the product manual.
[0018] Example 1 Example 1 provides a system for preparing micron-sized metal powders, such as Figure 1-3The system includes a raw material system 1, an air supply system 2, an atomizing tower 3, a separation system 4, a washing system 5, a drying system 6, a first heater 7, and a second heater 8. The atomizing tower includes an atomizing chamber, a droplet collector 9 at the bottom of the atomizing chamber, a reaction vessel 20 below the droplet collector 9, the outlet of the droplet collector 9 being connected to the inlet of the reaction vessel 20, and the outlet of the reaction vessel 20 being sequentially connected to the separation system 4, the washing system 5, and the drying system 6; a gas distributor 13 is provided at the top of the atomizing chamber, and a second gas inlet is provided on the tower body above the gas distributor 13, the second gas inlet being connected to the gas supply system 2; The atomization chamber is equipped with a micro-mixer 11 and an atomizing device 12. The micro-mixer 11 is made of polytetrafluoroethylene and includes a sol-generating unit 11-1 and a droplet-generating unit 11-2. The inlet of the sol-generating unit 11-1 is connected to the metal precursor raw material 1-1 and the reducing agent raw material 1-2 in the raw material system 1, respectively. The outlet of the sol-generating unit 11-1 is connected to the inlet of the droplet-generating unit 11-2, and the outlet of the droplet-generating unit 11-2 is connected to the inlet of the atomizing device 12. The droplet-generating unit 11-2 is also equipped with a first gas inlet, which is connected to the gas supply system 2. The sol-generating unit 11-1 consists of a main channel and several heart-shaped channels spaced apart on the main channel. The diameter of the main channel is 1-5 mm, and the diameter of the heart-shaped channels is half the diameter of the main channel.
[0019] To provide a constant temperature environment for the atomizing tower, the tower body is sequentially covered with an external heat tracing layer and a tower body insulation layer; the pipeline connecting the gas supply system 2 to the first gas inlet and the pipeline connecting the raw material system 1 to the sol generation unit inlet both pass through the first heater 7; the pipeline connecting the gas supply system 2 to the second gas inlet passes through the second heater 8.
[0020] The high sphericity gold powder was prepared using the preparation system provided in Example 1, and the steps are as follows: (1) Preparation of raw materials: 100ml chloroauric acid solution (0.05mol / L) is the metal precursor raw material, and 100ml ascorbic acid solution (0.1mol / L) is the reducing agent raw material; (2) Microreactor mixing: The metal precursor raw material and the reducing agent raw material are mixed in equal proportions at a total flow rate of 100 mL / min in a microreactor at 40 °C. The residence time in the sol generation unit is 2 s. In the droplet generation unit, the droplets are divided into droplets with a diameter of 2-5 mm by the continuous phase. The continuous phase is nitrogen gas at 40 °C introduced by the first gas inlet. (3) Spray nucleation: The droplets formed by the micro mixer are atomized into 2-5 μm micron-sized droplets by the gas atomizing device and diffused into the atomizing chamber, where they stay for 300 s in a nitrogen atmosphere at 40°C; the nitrogen gas at 40°C introduced by the second gas inlet forms a laminar flow after passing through the gas distributor to prevent collisions between droplets. (4) Solution growth: The solution collected in the reactor is diluted 10 times with water and then grown at 40°C for 1-10 hours; (5) Post-processing: After allowing the precipitate to stand for 6-12 hours in the separation system, pour off the supernatant; then wash the precipitate three times each with water and ethanol in the washing system; finally, vacuum dry it at 70℃ for 1 hour in the drying system to obtain micron-sized monodisperse spherical gold powder. Figure 4 As shown, the obtained gold powder has a uniform size with a particle size of 1-2 μm, and can be used to prepare gold-based electronic pastes.
[0021] Example 2 Example 2 provides a system for preparing micron-sized metal powders. The only difference from Example 1 is that Example 2 utilizes an electric field to provide a stable, constant-temperature, inert flow field. Specifically, as shown... Figure 5 As shown, the atomizing tower 3 in Embodiment 2 is not equipped with a gas distributor and a second gas inlet, and a positive electrode plate 14 and a negative electrode plate 15 are respectively provided at the top and bottom of the atomizing chamber. The atomizing device 12 is an electrostatic atomizing device.
[0022] The flake-shaped gold powder was prepared using the preparation system provided in Example 2, and the steps are as follows: (1) Preparation of precursors: 100 ml of chloroauric acid solution (0.05 mol / L) is used as the raw material for metal precursors, and 100 ml of oxalic acid solution (0.15 mol / L) is used as the raw material for reducing agents; (2) Microreactor mixing: The metal precursor raw material and the reducing agent raw material are mixed in equal proportions at a total flow rate of 100 mL / min in a microreactor at 40 °C. The residence time in the sol generation unit is 2-3 s, and the droplet generation unit is divided into droplets with a diameter of 2-5 mm by the continuous phase. The continuous phase is nitrogen gas at 40 °C introduced by the first gas inlet. (3) Spray nucleation: The droplets formed by the micro mixer are atomized into 5-10 μm micron-sized droplets by an electrostatic atomization device and diffused into the atomization chamber, where they remain for 600 s in an electric field at 40 °C; (4) Solution growth: Add an appropriate amount of oxalic acid solution to the solution collected in the reactor to prepare a solution with an oxalic acid concentration of 0.01 mol / L, and grow at 40℃ for 1-10 hours; (5) Post-processing: After allowing the precipitate to stand for 6-12 hours in the separation system, pour off the supernatant. Then, wash the precipitate three times each with water and ethanol in the washing system. Finally, vacuum dry it at 70°C for 1 hour in the drying system to obtain micron-sized flake-like gold powder containing a small amount of spherical particles. Figure 6 As shown, the obtained gold powder is a mixture of spherical and flake-shaped powders, with spherical particles having a diameter of 0.5-0.8 μm and flake particles having a diameter of 4-8 μm and a thickness of 0.3-0.5 μm. It can be used to prepare gold-based electronic pastes and pigments.
[0023] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A system for preparing micron-sized metal powder, characterized in that, This includes the raw material system, the gas supply system, and the atomizing tower; The atomizing tower includes an atomizing chamber, a droplet collector is provided at the bottom of the atomizing chamber, a reaction vessel is provided below the droplet collector, and the outlet of the droplet collector is connected to the inlet of the reaction vessel; The atomization chamber is equipped with a micro-mixer and an atomizing device. The micro-mixer includes a sol-generating unit and a droplet-generating unit. The inlet of the sol-generating unit is connected to the raw material system, the outlet of the sol-generating unit is connected to the inlet of the droplet-generating unit, and the outlet of the droplet-generating unit is connected to the inlet of the atomizing device. The droplet-generating unit is also equipped with a first gas inlet, which is connected to the gas supply system.
2. The system for preparing micron-sized metal powder according to claim 1, characterized in that, The sol-generating unit consists of a main channel and several heart-shaped channels or several interdigitated channels spaced on the main channel. The diameter of the heart-shaped channels or several interdigitated channels is half the diameter of the main channel.
3. The system for preparing micron-sized metal powder according to claim 2, characterized in that, The diameter of the main channel is 1-5mm; And / or, the micromixer is made of polytetrafluoroethylene.
4. A system for preparing micron-sized metal powder according to any one of claims 1-3, characterized in that, A gas distributor is provided at the top of the atomizing chamber, and a second gas inlet is provided on the tower body above the gas distributor. The second gas inlet is connected to the gas supply system.
5. A system for preparing micron-sized metal powder according to any one of claims 1-3, characterized in that, An electrode plate is provided at the top and bottom of the atomization chamber, and the atomization device is an electrostatic atomization device.
6. A system for preparing micron-sized metal powder according to any one of claims 1-3, characterized in that, The atomizing tower is covered with an external heat tracing layer and a tower insulation layer in sequence.
7. A system for preparing micron-sized metal powder according to any one of claims 1-3, characterized in that, It also includes a heater; the pipeline connecting the gas supply system to the first gas inlet and the pipeline connecting the raw material system to the inlet of the sol generation unit both pass through the heater.
8. A system for preparing micron-sized metal powder according to any one of claims 1-3, characterized in that, It also includes a separation system, a washing system, and a drying system connected in sequence; The inlet of the separation system is connected to the outlet of the reactor.