Method for mechanically shaping superfine powder

Abstract

The invention discloses a method for mechanically shaping superfine powder, and relates to the preparation field of particle size control and morphology control of glass superfine powder, and the method comprises the following steps: 1, conveying a primarily crushed powder raw material into a multi-stage turbo-type shaping cavity which is composed of a fixed wall and a high-speed rotor, and the high-speed rotor is provided with a shaping medium; 2, synchronously applying an impact, shearing and rolling composite force field; 3, treating for 5-30 minutes in a low-temperature environment from-50 DEG C to normal temperature; 4, monitoring the sphericity degree and the particle size distribution of the powder in real time through an online particle image analyzer; 5, collecting the sphericity gt through a cyclone separator; and 0.95 of the superfine powder finished product is obtained. The sphericity gt of the powder is produced; 0.95, the surface roughness is Rat; the sphericity degree of the traditional ball milling process is generally 1t; and 0.75, microcracks generated by impact crushing are avoided through the synergistic effect of shearing and rolling.

Description

Technical Field

[0001] This invention relates to the field of preparation technology for controlling the particle size and morphology of ultrafine glass powders, and specifically to a method for mechanically shaping ultrafine powders. Background Technology

[0002] Glass microspheres are a widely used inorganic filler material. They are made from borosilicates and have a particle size of 1-250 μm. Glass microspheres have the same chemical composition as glass fibers and also have advantages such as low thermal conductivity and good chemical stability. Due to their spherical appearance, glass microspheres have excellent flowability and dispersibility. In practical applications, the particle size and distribution of powders are the most basic yet critical performance characteristics, which basically determine the overall and surface properties of the powder. In addition, the structural morphology characteristics of powders also include the shape, chemical composition, internal and external surface area, volume, and surface defects, which together determine the comprehensive performance of the powder. Therefore, in recent years, the control of powder structure morphology and particle size has gradually become an important part of powder research.

[0003] In the preparation of most powder materials, there are special requirements for particle size and morphology. The diverse requirements of different application fields for the morphology and particle size of functional powder materials have raised new challenges for the development of powder material preparation technology, namely, the control of particle morphology and particle size in its preparation and processing. Therefore, in the preparation of spherical glassy powder, it is of great significance to control the powder structure and morphology according to its application needs.

[0004] When preparing spherical glassy materials, the particle size must be determined based on the spherical particle size, and a certain distribution width must be maintained around the specified particle size so that small particles can fill the gaps between large particles. Because spherical glassy materials are spherical, they have the low porosity of ideal fillers (referring to the proportion of the volume of the granular material to the volume of the voids between the particles). At the same time, they can make the stress distribution of the final product reasonable, especially the stress is evenly distributed along the surface of the product, improving the rigidity, hardness, and dimensional stability of the material. Therefore, the particle size and morphology of the powder are particularly important.

[0005] The process by which large particles of vitreous materials are broken into smaller particles by overcoming the cohesive forces of the material under the action of external forces is called crushing. Material crushing is mainly accomplished by crushers and pulverizers. The purposes of crushing are as follows: (1) Homogenization As the crushing process proceeds, the specific surface area of ​​the material increases continuously. Increasing the specific surface area of ​​the material can increase the contact area between the material and the surrounding medium, thereby accelerating the reaction rate.

[0006] (2) Particle size classification In the subsequent production of spherical glass, due to the specific production process requirements, there are relatively strict particle size requirements for glass materials, and the crushing machinery must meet the particle size of its products.

[0007] Traditional powder crushing methods (such as jaw crushers, ball mills, and hammer crushers) have a significant negative impact on the morphology of powder particles. Mechanical extrusion and shear-dominated crushing (jaw crushers, roller crushers) subject materials to high pressure between fixed and moving toothed plates, resulting in irregular fracture surfaces. Random collision crushing (ball milling) causes particles to break along cleavage planes due to disordered impacts of the grinding balls, forming multi-faceted fragments. These commonly used powder crushing methods easily produce high-angle and sharp-edged particles (accounting for >60%). These morphological defects in powders can easily lead to the deterioration of application performance, such as deteriorated flowability (reduced filling rate), reduced bulk density (bridging effect caused by angular particles), reduced interfacial bonding strength (local electric field concentration at the edges during sintering, inducing abnormal grain growth), and abnormal chemical activity (surge in the specific surface area of ​​cracks and rough surfaces). In order to reduce the impact of the decline in processing performance index caused by the above-mentioned morphological defects, it is urgent to mechanically shape the crushed powder to achieve or approach the ideal morphology. Therefore, we provide a method for mechanical shaping of ultrafine powders to solve the above problems. Summary of the Invention

[0008] To address the problems existing in the prior art, this invention provides a method for mechanical shaping of ultrafine powders. By integrating composite force fields, low-temperature environments, intelligent control, and in-situ surface repair technology, raw materials (whether brittle, tough, or composite materials) are efficiently transformed into high-quality powders with high sphericity, smooth surfaces, no internal damage, and concentrated particle size distribution in a single process within a closed system. This method meets the extreme performance requirements of spherical glass powders in fields such as additive manufacturing, high-end powder metallurgy, and new energy electrode materials.

[0009] To achieve the above objectives, the present invention employs a method for mechanical shaping of ultrafine powders, comprising: The first step involves conveying the pre-crushed powder raw material into a multi-stage turbine-type shaping chamber, which consists of a fixed wall and a high-speed rotor, with a shaping medium on the high-speed rotor. The second step involves using a high-speed rotor to drive the powder and shaping medium to form a vortex fluidized bed under conditions of airflow velocity of 10-50 m / s and rotor speed of 2000-8000 r / min, while simultaneously applying a composite force field of impact, shearing and rolling. The third step is to treat the cavity in a low-temperature environment of -50℃ to room temperature for 5-30 minutes, during which time a surface repair agent of 0.1-0.5% of the powder mass is sprayed into the cavity. The fourth step involves real-time monitoring of powder sphericity and particle size distribution using an online particle image analyzer. When the sphericity deviates from the set threshold, the rotor speed or airflow parameters are automatically adjusted to achieve closed-loop feedback control. The fifth step involves collecting the ultrafine powder product with a sphericity >0.95 using a cyclone separator.

[0010] As a further optimization of the above scheme, the inner diameter of the multi-stage turbine-type shaping cavity is 400-800mm and the height is 600-1200mm; The inner wall of the fixed wall is provided with a turbulence guide groove with a semi-circular cross-section, the groove depth is 10-30mm, and the helix angle is 30-45°.

[0011] As a further optimization of the above solution, the shaping medium is a hard ceramic sheet or alloy microspheres, and the filling amount is 15-30% of the cavity volume; The high-speed rotor includes blades, and the hard ceramic sheet or alloy microspheres are rolled and mounted on the high-speed rotor.

[0012] As a further optimization of the above scheme, the surface repair agent is an atomized solution prepared by mixing silane coupling agent and anhydrous ethanol at a volume ratio of 1:50-1:100. The spraying time is 3-5 minutes after the shaping begins, and the spraying lasts for 2-8 minutes.

[0013] As a further optimization of the above scheme, the closed-loop feedback control is based on a machine learning model, which associates the online monitored morphology data with the equipment parameters. When the sphericity decreases by more than 0.02, the system automatically increases the rotor speed by 200-500 r / min or increases the airflow pressure by 0.02-0.05 MPa.

[0014] As a further optimization of the above solution, differentiated process parameters are adopted for materials with different hardness: Brittle materials: rotation speed 3000-5000 r / min, temperature -40℃ to -50℃, processing time 8-15 minutes; Tough metals: Rotation speed 5000-8000 r / min, temperature -20℃ to -30℃, processing time 15-25 minutes; Composite materials: Use alternating pulsed treatment at 2000-4000 r / min and 6000-8000 r / min, with a cycle of 3 minutes, for a total of 3-5 cycles.

[0015] As a further optimization of the above solution, the online particle image analyzer has a detection frequency of ≥1000 particles / second, a defect detection rate of >99.5%, and a batch-to-batch product quality fluctuation rate of <±2%.

[0016] The present invention provides a method for mechanical shaping of ultrafine powders, which has the following beneficial effects: The present invention provides a method for mechanical shaping of ultrafine powder, producing powder with a sphericity >0.95 and a surface roughness Ra <0.5μm. The sphericity of traditional ball milling is usually <0.75. Through the synergistic effect of "shearing-rolling", microcracks caused by impact crushing are avoided.

[0017] Specific embodiments of the present invention are disclosed in detail with reference to the following description and accompanying drawings, indicating how the principles of the present invention can be adopted. It should be understood that the embodiments of the present invention are not limited in scope as a result, and that the embodiments of the present invention include many changes, modifications and equivalents within the spirit and scope of the appended claims. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the method for mechanical shaping of ultrafine powder according to the present invention; Figure 2 This is a schematic diagram of the internal structure of the multi-stage turbine-type shaping cavity of the present invention; Figure 3 This is a real-time particle size distribution diagram of the present invention; Figure 4 This is a diagram showing the measured sphericity distribution before shaping in this invention; Figure 5 This is a diagram showing the measured sphericity distribution after shaping in this invention.

[0019] In the diagram: 1. Multi-stage turbine-type shaping cavity; 2. Fixed wall; 3. Power shaft; 4. Discharge area; 5. Feeding area; 6. Blades; 7. Alloy microspheres; 8. Hard ceramic sheet; 9. Turbulent flow guide channel. Detailed Implementation

[0020] Powder shaping is essentially the localized breaking of the powder surface. By changing the type and mode of force, the surface morphology of the powder can be altered. During the powder shaping process, it is subject to the interaction of various forces, such as abrasive forces between powder particles, shear forces, or pressure generated by gas impact. Different shaping mechanisms are adopted according to the desired powder morphology. The purpose of this invention is to shape the sharp corners of broken glass powder to make it smoother and easier to press. Therefore, the powder shaping method must be mainly based on frictional shear forces, cutting or grinding away the sharp edges of the powder surface to make the particle surface smooth rather than breaking the powder into two or more pieces.

[0021] The core objective of this invention is to completely overcome the inherent drawbacks of traditional crushing technologies, such as uncontrollable particle morphology, severe internal damage, and low efficiency. By integrating composite force fields, low-temperature environments, intelligent control, and in-situ surface repair technologies, raw materials (whether brittle, tough, or composite materials) can be efficiently transformed into high-quality powders with high sphericity, smooth surfaces, no internal damage, and concentrated particle size distribution in a single process within a closed system. This will meet the ultimate performance requirements of spherical glass powders in fields such as additive manufacturing, high-end powder metallurgy, and new energy electrode materials.

[0022] Please refer to the instruction manual appendix. Figure 1-5 The present invention provides a technical solution: a method for mechanical shaping of ultrafine powder.

[0023] Example 1 This method for mechanically shaping ultrafine powders uses composite force field shaping technology.

[0024] Objective: To upgrade simple impact and collision crushing to a controllable multi-mode collaborative shaping process of "impact-shear-rolling" to actively "grind" irregular particles into spherical shapes.

[0025] Implementation plan: refer to Figure 2 As shown, a multi-stage turbine-type shaping cavity 1 is designed, which consists of a fixed wall 2 and a high-speed rotor. The high-speed rotor is not a simple blade 6, but is equipped with a hard ceramic sheet 8 or alloy microspheres 7 that can roll freely (as a shaping medium).

[0026] The inner wall of the fixed wall 2 is designed with a specific turbulence guide groove 9 to guide the airflow and particles to generate strong vortex motion. The treatment lasts for 5-30 minutes. During this period, a surface repair agent of 0.1-0.5% of the powder mass is sprayed into the cavity (the surface repair agent is an atomized solution prepared by mixing silane coupling agent and anhydrous ethanol at a volume ratio of 1:50-1:100. The spraying time is 3-5 minutes after the shaping begins, and it lasts for 2-8 minutes).

[0027] Multi-stage turbine-type shaping cavity 1 specifications: inner diameter 400-800mm, height 600-1200mm, grade 3-5, material is tungsten carbide coated wear-resistant steel.

[0028] High-speed rotor operating conditions: 2000-8000 r / min, frequency adjustable.

[0029] Shaping media specifications: Zirconia spheres or cemented carbide spheres with a diameter of 0.5-5mm, filling volume of 15-30% of the cavity volume.

[0030] Turbulent guide channel 9: The cross-section is semi-circular, the depth is 10-30mm, and the helix angle is 30-45°.

[0031] The airflow velocity is 10-50 m / s (adjusted by the rotor speed and the fan frequency). Processing time: 5-30 minutes per batch; Feed rate: 0.5-5kg / batch (adjusted according to material density); Operating temperature: -50℃ to room temperature (low temperature environment achieved through liquid nitrogen injection).

[0032] Different process parameters are used for materials with different hardness: Brittle materials: rotation speed 3000-5000 r / min, temperature -40℃ to -50℃, processing time 8-15 minutes; Tough metals: Rotation speed 5000-8000 r / min, temperature -20℃ to -30℃, processing time 15-25 minutes; Composite materials: Use alternating pulsed treatment at 2000-4000 r / min and 6000-8000 r / min, with a cycle of 3 minutes, for a total of 3-5 cycles.

[0033] In actual setup, the multi-stage turbine-type shaping cavity 1 is a cylindrical structure. A fixed wall 2 is installed on the inner wall of the multi-stage turbine-type shaping cavity 1. Turbulent guide grooves 9 are provided on the surface of the fixed wall 2. The turbulent guide grooves 9 are distributed in a spiral trajectory. A power shaft 3 is also provided in the multi-stage turbine-type shaping cavity 1. A high-speed rotor is fixedly installed on the power shaft 3. The high-speed rotor includes blades 6. Multiple blades 6 are provided. Multiple blades 6 are distributed at equal distances along the axis of the power shaft 3. A shaping medium is provided on the blades 6. The shaping medium includes hard ceramic sheets 8 and alloy microspheres 7. The hard ceramic sheets 8 are rotatably and slidably disposed on the side of the blades 6 away from the power shaft 3. Multiple alloy microspheres 7 are provided. The alloy microspheres 7 are movably embedded on the surface of the blades 6.

[0034] It should be noted that the hard ceramic sheet 8 and the blade 6 are connected by a sliding groove and a T-shaped slider structure. A limit plate is provided at the end of the sliding groove to prevent the hard ceramic sheet 8 from detaching from the blade 6. These are all common sliding connection structures and will not be described in detail here. The multi-stage turbine-type shaping cavity 1 has a feeding area 5 on one end face and a discharging area 4 on the other end face. Both the feeding area 5 and the discharging area 4 are provided with openable and closable sealing covers. The multi-stage turbine-type shaping cavity 1 is also equipped with a servo motor and a reducer for rotating the power shaft 3. This is a common technology and is not shown in the figure.

[0035] 2. Workflow and Principles: Primary crushing zone: The material enters the bottom of the multi-stage turbine-type shaping chamber through the feeding system. It is first accelerated by high-speed airflow, and the particles collide with each other and with the wall at high speed (impact crushing) to achieve preliminary crushing.

[0036] Fine shaping zone: Accelerated particles, along with shaped microspheres mixed in the airflow, are drawn into the rotor area. Driven by the rotor, the mixture forms a high-speed rotating "fluidized bed".

[0037] Shear force: Strong relative motion and shear friction are generated between particles and between particles and microspheres, effectively grinding away the edges and burrs of the particles.

[0038] Rolling force: Under the action of centrifugal force, the particles are pressed against the cavity wall and rolled into shape under the action of the wall guide groove and microspheres, similar to the "rolling polishing" process of metal, gradually tending to become spherical.

[0039] 3. Intelligent control: By adjusting the rotor speed and airflow velocity, the magnitude of shear force and rolling force can be precisely controlled, thereby adapting to the shaping requirements of materials with different hardness (such as ceramics requiring high shear and metals requiring high rolling force).

[0040] Example 2 Intelligent control and optimization system: Objective: To enable the entire system to perceive, make decisions, and optimize, thereby ensuring the stability and consistency of product quality.

[0041] Implementation plan: 1. Perception layer: An online real-time particle image analyzer (PIA) or laser particle size distribution analyzer is installed at the discharge port to continuously monitor key indicators such as sphericity and particle size distribution of the finished powder. The detection frequency of the online particle image analyzer is ≥1000 particles / second, the defect detection rate is >99.5%, and the batch-to-batch product quality fluctuation rate is <±2%.

[0042] 2. Decision-making and execution level: Establish a machine learning model to perform correlation analysis between the monitored morphology data and the current equipment parameters (rotor speed, airflow pressure, liquid nitrogen flow rate, and remedial agent injection volume). For example, by adjusting parameters such as rotor speed and airflow pressure, it can be detected that the particles to be crushed have different morphologies, sphericity, and particle size distributions. By comparing these data, the range of equipment parameters with different morphologies, sphericity, and particle size distributions can be obtained.

[0043] The system has a built-in expert database containing the optimal morphology and process parameters for various materials. Once the product quality deviates from the set value (such as the sphericity dropping from 0.92 to 0.88), the control system will automatically adjust the relevant parameters in reverse (such as increasing the rotor speed to increase the shear force) to achieve closed-loop feedback control and ensure zero batch-to-batch differences. Example 3 System integration and expected results: like Figures 3-5 As shown, Figure 2 The real-time particle size distribution map is obtained by online real-time high-resolution flow cytometry imaging microscope, which can measure all real-time particle size parameters of powder through high-speed image capture, and obtain the true particle size distribution of powder through software analysis. Figure 4 This is a diagram showing the measured sphericity distribution before the procedure. Figure 5 This is a diagram showing the measured sphericity distribution after reshaping. Figure 4 and Figure 5 Both are online real-time high-resolution flow cytometry microscopes that can measure all real-time sphericity parameters of powder through high-speed image capture, and obtain the true sphericity map of powder through software analysis.

[0044] Expected results: I. Morphology control: The sphericity of the produced powder is >0.95 (1.0 for a perfect sphere), and the surface is smooth and burr-free.

[0045] II. Performance Improvement: Powder flowability (Hall flow rate) is improved by more than 50%, and tap density is improved by 20-35%.

[0046] III. Quality Consistency: The fluctuation rate of particle size and morphology between batches is < ±2%.

[0047] IV. Application Scope: It can handle a wide range of materials, from vitreous materials and hard ceramics to tough metals and thermoplastics.

[0048] This invention leads powder processing from the traditional "extensive crushing" to a new stage of "precision morphology manufacturing," providing key technical support for breakthroughs in the performance of core materials.

Claims

1. A method for mechanical shaping of ultrafine powder, characterized in that, include: The first step is to transport the pre-crushed powder raw material to a multi-stage turbine-type shaping chamber (1), which is composed of a fixed wall (2) and a high-speed rotor, and the high-speed rotor has a shaping medium. The second step involves using a high-speed rotor to drive the powder and shaping medium to form a vortex fluidized bed under conditions of airflow velocity of 10-50 m / s and rotor speed of 2000-8000 r / min, while simultaneously applying a composite force field of impact, shearing and rolling. The third step is to treat the cavity in a low-temperature environment of -50℃ to room temperature for 5-30 minutes, during which time a surface repair agent of 0.1-0.5% of the powder mass is sprayed into the cavity. The fourth step involves real-time monitoring of powder sphericity and particle size distribution using an online particle image analyzer. When the sphericity deviates from the set threshold, the rotor speed or airflow parameters are automatically adjusted to achieve closed-loop feedback control. The fifth step involves collecting the ultrafine powder product with a sphericity >0.95 using a cyclone separator.

2. The method for mechanical shaping of ultrafine powder according to claim 1, characterized in that: The multi-stage turbine-type shaping cavity (1) has an inner diameter of 400-800mm and a height of 600-1200mm; The inner wall of the fixed wall (2) is provided with a turbulent guide groove (9) with a semi-circular cross-section, a groove depth of 10-30mm, and a spiral angle of 30-45°.

3. The method for mechanical shaping of ultrafine powder according to claim 1, characterized in that: The shaping medium is a hard ceramic sheet (8) or an alloy microsphere (7), and the filling amount is 15-30% of the cavity volume; The high-speed rotor includes blades (6), and the hard ceramic sheet (8) or alloy microsphere (7) is rolled on the high-speed rotor.

4. The method for mechanical shaping of ultrafine powder according to claim 1, characterized in that: The surface repair agent is an atomized solution prepared by mixing silane coupling agent and anhydrous ethanol at a volume ratio of 1:50-1:

100. The spraying time is 3-5 minutes after the shaping begins, and it lasts for 2-8 minutes.

5. The method for mechanical shaping of ultrafine powder according to claim 1, characterized in that: The closed-loop feedback control is based on a machine learning model, which associates the online monitored morphology data with the equipment parameters. When the sphericity decreases by more than 0.02, the system automatically increases the rotor speed by 200-500 r / min or increases the airflow pressure by 0.02-0.05 MPa.

6. The method for mechanical shaping of ultrafine powder according to claim 1, characterized in that: Different process parameters are used for materials with different hardness: Brittle materials: rotation speed 3000-5000 r / min, temperature -40℃ to -50℃, processing time 8-15 minutes; Tough metals: Rotation speed 5000-8000 r / min, temperature -20℃ to -30℃, processing time 15-25 minutes; Composite materials: Use alternating pulsed treatment at 2000-4000 r / min and 6000-8000 r / min, with a cycle of 3 minutes, for a total of 3-5 cycles.

7. The method for mechanical shaping of ultrafine powder according to claim 1, characterized in that: The online particle image analyzer has a detection frequency of ≥1000 particles / second, a defect detection rate of >99.5%, and a batch-to-batch product quality fluctuation rate of <±2%.

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