Process and device for preparing lithium ceramic pellets through combination of extrusion forming and low-temperature cold molding
By combining extrusion molding with low-temperature cold plasticizing, the problems of particle size uniformity and density of lithium ceramic microspheres were solved, improving the density and mechanical strength of lithium ceramic microspheres and meeting the high-quality production requirements of fusion reactor fuel.
Patent Information
- Application Number
- CN202511759460.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-27
- Publication Date
- 2026-02-10
AI Technical Summary
The existing lithium ceramic microspheres have poor particle size uniformity, structural consistency and compactness, and thermal stress is difficult to control, which affects tritium release performance and blanket breeding efficiency, becoming a key bottleneck restricting the reliability of fusion reactor fuel cycle.
The process combines extrusion molding and low-temperature cold plasticizing, including raw material mixing and ball milling, extrusion molding, low-temperature freezing treatment and densification sintering. By controlling the diameter of the extrusion head and low-temperature cold plasticizing, combined with multi-stage sieving, the uniformity of particle size and the consistency of structure are improved.
It significantly improves the density and overall mechanical strength of lithium ceramic microspheres, achieving uniform particle size and structural consistency, thus meeting the high-quality production requirements of fusion reactor fuel.
Smart Images
Figure CN121494529A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of fusion reactor fuel technology, specifically to a process and apparatus for preparing lithium ceramic microspheres by a combination of extrusion molding and cryogenic cryopreservation. Background Technology
[0002] With the accelerated global transition to cleaner energy, the development of controlled nuclear fusion, especially DT reactors, has attracted much attention. Tritium, as the core fuel for fusion, needs to be produced through in-reactor lithium ceramic breeder cycles. Among them, 6Li-rich lithium-based ceramic Li₂TiO₃, with its high lithium atom density, low activation, excellent chemical stability, and good tritium release performance, is considered one of the most promising solid tritium breeders and has attracted the attention of researchers at home and abroad.
[0003] The preparation method of Li₂TiO₃ typically involves mixing raw materials into a ceramic slurry, which is then dripped into a curing agent using a syringe. The surface tension of the droplets forms small spheres, which are then sintered to obtain ceramic microspheres. However, this method produces microspheres with a wide particle size distribution, poor particle size uniformity, structural consistency, and density. Furthermore, the sintering process lacks precise temperature field control, leading to thermal stress concentration and poor process repeatability. These process shortcomings directly affect tritium release performance and blanket breeding efficiency, becoming key bottlenecks restricting the reliability of fusion reactor fuel cycles.
[0004] Therefore, it is necessary to design a new process and apparatus for lithium ceramic microspheres. Summary of the Invention
[0005] This invention aims to address the technical problems of poor particle size uniformity, structural consistency, and density, as well as the difficulty in controlling thermal stress, in lithium ceramic microspheres prepared by existing processes. The purpose is to provide a process and apparatus for preparing lithium ceramic microspheres by a combination of extrusion molding and low-temperature cold plastic molding. The lithium ceramic microspheres prepared by this process and apparatus have significantly improved density and comprehensive mechanical strength, and exhibit good particle size uniformity and structural consistency.
[0006] The present invention is achieved through the following technical solution.
[0007] The first aspect of this invention is to provide a process for preparing lithium ceramic microspheres by a combination of extrusion molding and low-temperature cryopreservation, comprising the following steps: TiO2, LiOH·H2O, and the solution were mixed and reacted in a certain proportion and then ball-milled to obtain Li2TiO3 slurry; Li2TiO3 slurry was extruded under a pressure of 90-110 N to obtain Li2TiO3 green spheres; The Li2TiO3 green blank spheres were frozen at -18℃ to 0℃ for 3-4 hours. Lithium ceramic microspheres were obtained by sintering the cryogenically treated Li2TiO3 green body microspheres.
[0008] This invention involves mixing and reacting raw materials, ball milling the reaction solution, then efficiently extruding and molding the mixture, controlling the diameter of the extrusion head, and then shaping the shaped microspheres through low-temperature cold plasticizing. Finally, a densification sintering process is performed, which significantly improves the density and overall mechanical strength of the final lithium ceramic microspheres, while also ensuring good particle size uniformity and structural consistency.
[0009] Further, TiO2 and LiOH·H2O account for 4-6% and 2-3% of the weight percentage of the solution, respectively. The solution is a mixture of HPMC, ethanol and deionized water, with a mass ratio of (0.5-1.5):(10-12):(7-9). Preferably, TiO2 and LiOH·H2O account for 5% and 2.5% of the weight percentage of the solution, respectively, and the optimal mass ratio of HPMC, ethanol and deionized water is 1:12:8.
[0010] Furthermore, the sintering process is as follows: holding at 280-320℃ for 1.5-2.5 hours, then raising the temperature to 780-820℃ and holding for 1.5-2.5 hours, then raising the temperature to 950-1100℃ and holding for 0.5-1.5 hours. This sintering process incorporates a temperature gradient, which significantly promotes the diffusion and rearrangement of particles within the green body, effectively eliminating residual porosity and greatly improving the final density and overall mechanical strength of the material.
[0011] Furthermore, the process also includes multi-stage sieving of the sintered lithium ceramic microspheres. This process involves multi-stage sieving based on preset equal particle size specifications to achieve precise grading of the particle size range, classifying and collecting microspheres of each grade to ensure sample integrity and batch consistency.
[0012] A second aspect of the present invention is to provide an apparatus for preparing lithium ceramic microspheres by a combination of extrusion molding and cryopreservation, comprising: A material synthesis device used to react raw materials; The ball milling device is connected to the outlet of the material synthesis device and is used to ball mill the reactants to obtain a tritium breeder slurry. The material extrusion device is connected to the outlet of the ball mill and is used to extrude the tritium breeder slurry to obtain raw pellets; The low-temperature cryopreservation system is connected to the outlet of the material extrusion device and is used to freeze the preform pellets. The sintering device is connected to the outlet of the low-temperature cold plasticizing system and is used to sinter the green blank spheres.
[0013] This invention utilizes the aforementioned apparatus to first synthesize the product through a material synthesis device, then perform a thorough ball milling process to generate a high-energy ball milling reaction, thereby improving the uniformity of the slurry and ensuring subsequent particle size uniformity and density. Next, the particle size of the microspheres is further controlled by extrusion molding to control the diameter of the extruder head. Then, the microspheres are cold-plasticized at low temperature and sintered to further effectively improve the density and mechanical strength of the material. Under this system, the density and overall mechanical strength of the lithium ceramic microspheres are significantly improved, and the particle size uniformity and structural consistency are good.
[0014] Furthermore, it also includes a multi-stage screening device and a collection device connected in sequence, wherein the multi-stage screening device is connected to the outlet of the sintering device. Through multi-stage screening, precise grading of the particle size range is achieved, further improving the particle size uniformity of the product.
[0015] Furthermore, it also includes a dust treatment system, which is connected to the material synthesis device and the ball milling device for collecting and purifying dust. During the production process, each device generates dust. By collecting and purifying the generated dust, clean production and factory protection can be achieved. The dust treatment system can use any dust removal device available in the prior art.
[0016] Furthermore, it also includes a monitoring and early warning system, which is connected to the dust treatment system, ball mill, and sintering device for monitoring temperature and pressure. By intelligently analyzing data such as temperature, it accurately identifies potential risks and issues early warnings. The monitoring and early warning system integrates perception, decision-making, and execution: it is both the "nerve endings" for sensing risks, the "intelligent central hub" for judging and issuing early warnings, and the "execution terminal" for realizing on-site alarms through sound and light signals, comprehensively improving risk prevention and response capabilities.
[0017] Furthermore, the ball mill is connected to the material extrusion device via a material supply device and a feeding pipe.
[0018] Furthermore, the low-temperature cryopreservation system includes a vacuum chamber and a refrigeration device. The refrigeration device is located inside the vacuum chamber to generate a refrigeration environment, and the blank pellets extruded by the extrusion device are fed into the vacuum chamber.
[0019] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. This invention involves mixing and reacting raw materials, ball milling the reaction solution, then efficiently extruding and molding the mixture, controlling the diameter of the extrusion head, and then shaping the shaped microspheres through low-temperature cold plasticizing. Finally, a densification sintering treatment is performed, which significantly improves the density and overall mechanical strength of the final lithium ceramic microspheres, and also results in good particle size uniformity and structural consistency. 2. The apparatus of the present invention first synthesizes the product through a material synthesis device, and then performs a high-energy ball milling reaction to improve the uniformity of the slurry, which ensures the uniformity and density of the particle size in the subsequent process. Then, the particle size of the microspheres is further controlled by controlling the diameter of the extruder head through extrusion molding. Then, the microspheres are shaped by low-temperature cold plastic molding and then densified by sintering to further effectively improve the density and mechanical strength of the material. Under this system, the density and comprehensive mechanical strength of the lithium ceramic microspheres are significantly improved, and the particle size uniformity and structural consistency are good. Attached Figure Description
[0020] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:
[0021] Figure 1 This is a schematic diagram of the structure of the device of the present invention; The attached diagram shows the markings and corresponding component names: 1-PLC control system, 2-monitoring and early warning system, 3-dust treatment system, 4-material synthesis device, 5-conveying pipeline, 6-ball mill device, 7-material supply device, 8-feeding pipeline, 9-material extrusion device, 10-low temperature cold plasticizing system, 11-vacuum chamber, 12-refrigeration device, 13-sintering device, 14-multi-stage screening device, 15-collection device. Detailed Implementation
[0022] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.
[0023] The following detailed description, with appropriate reference to the accompanying drawings, details an embodiment of the process and apparatus for the combined extrusion molding and cryogenic cryopreservation of lithium ceramic microspheres according to the present invention. However, unnecessary details may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art.
[0024] The "scope" disclosed in this invention is defined in the form of a lower limit and an upper limit. A given scope is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific scope. The scope defined in this way can include or exclude end values, and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a scope.
[0025] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.
[0026] Unless otherwise specified, all technical features and optional technical features of this invention can be combined to form new technical solutions.
[0027] Unless otherwise specified, the terms "comprising" and "including" as used in this invention can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other substances not listed may also be included, or that only the listed substances may be included.
[0028] Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.
[0029] In the description of this invention, the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship that the product of this application is usually placed in when in use, or the orientation or positional relationship that is commonly understood by those skilled in the art. It is only for the convenience of describing this application and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this application.
[0030] Meanwhile, the terms "set up," "assemble," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.
[0031] The technical solution of the present invention will be further described in detail below with reference to the embodiments.
[0032] It should be noted that, unless otherwise specified, the experimental methods used in the embodiments are conventional methods. Unless otherwise specified, the materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.
[0033] Example 1
[0034] This embodiment provides an apparatus for preparing lithium ceramic microspheres by extrusion molding and low-temperature cryopreservation, comprising a material synthesis device 4, a ball milling device 6, a material supply device 7, a material extrusion device 9, a low-temperature cryopreservation system 10, a sintering device 13, a multi-stage screening device 14, and a collection device 15 connected in sequence. The material synthesis device 4 is used to provide space for the raw material reaction; The ball milling device 6 is connected to the outlet of the material synthesis device 4 via the conveying pipe 5, and is used to ball mill the reactants to obtain a tritium breeder slurry. The material extrusion device 9 is connected to the outlet of the ball mill device 6 through the material supply device 7 and the feeding pipe 8, and is used to extrude the tritium breeding agent slurry to obtain raw pellets. The low-temperature cold plastic system 10 is connected to the outlet of the material extrusion device 9 and is used to freeze the raw preform balls. The sintering device 13 is connected to the outlet of the low-temperature cold plasticizing system 10 and is used to sinter the green blank spheres. The inlet of the multi-stage screening device 14 is connected to the outlet of the sintering device 13, and the outlet of the multi-stage screening device 14 is connected to the inlet of the collecting device 15.
[0035] Preferably, the device further includes a dust treatment system 3, which is connected to the material synthesis device 4 and the ball mill device 6 for collecting and purifying dust. During the production process, each device will generate dust. By collecting and purifying the generated dust, the effect of clean production and protection of the factory can be achieved. The dust treatment system 3 can be any dust removal device in the prior art.
[0036] Preferably, the device also includes a PLC control system 1 and a monitoring and early warning system 2. The PLC control system 1, with a central processing unit (CPU) as its core, is integrated in the electrical control cabinet. By coordinating the operation of input / output (I / O) modules, power supply modules, and communication units, it jointly constructs a complete intelligent control hub for the preparation of tritium breeding microspheres. The monitoring and early warning system 2 is connected to the dust treatment system 3, the ball milling device 6, and the sintering device 13 for monitoring temperature and pressure. By intelligently analyzing data such as temperature, it accurately identifies potential risks and issues early warnings. The monitoring and early warning system 2 integrates perception, decision-making, and execution: it is both the "nerve endings" for perceiving risks, the "intelligent central hub" for judging and issuing early warnings, and the "execution terminal" for realizing on-site alarms through sound and light signals, comprehensively improving risk prevention and response capabilities.
[0037] It should be noted that the device of the present invention, by integrating an intelligent PLC control system 1 with engineering equipment, can construct an automated production line with precisely adjustable process parameters, effectively controlling the particle size distribution and thermal stress level of tritium breeding microspheres, overcoming the problems of limited production capacity, intermittent operation and poor product consistency in traditional laboratory preparation, and meeting the large-scale, high-quality production requirements of fusion reactors for tritium breeding materials; through the monitoring and early warning system 2, the entire process from material handling to molding and sintering is monitored online and controlled in a closed loop, strictly controlling the material composition, microstructure and key performance indicators, significantly improving the reliability and consistency of the product under extreme operating conditions.
[0038] Preferably, the low-temperature cold plastic system 10 includes a vacuum chamber 11 and a cooling device 12. The cooling device 12 is located inside the vacuum chamber 11 to generate a cooling environment, and the blank spheres extruded by the extrusion device are sent into the vacuum chamber 11.
[0039] This invention utilizes the aforementioned apparatus. First, the product is synthesized through the material synthesis device 4. Then, a high-energy ball milling reaction is carried out to improve the uniformity of the slurry, ensuring the uniformity and density of the particle size. Next, the particle size of the microspheres is further controlled by controlling the diameter of the extruder head through extrusion molding. Then, low-temperature cold plastic shaping is performed, followed by densification sintering to further effectively improve the density and mechanical strength of the material. Finally, the particle size is accurately classified by sieving. Under this system, the density and comprehensive mechanical strength of the lithium ceramic microspheres are significantly improved, and the particle size uniformity and structural consistency are good.
[0040] Example 2
[0041] A process for preparing lithium ceramic microspheres by a combination of extrusion molding and low-temperature cold plasticizing includes the following steps: (1) Start the PLC control system, load the control program, and after the system self-test is completed, check the communication connection status with each functional module in turn to ensure that the link is stable and reliable; (2) Set safety threshold parameters for key analog quantities (e.g., ball milling time (24h), dust concentration (< 1 mg / m³)). 3 (1) Temperature limit (≤60℃) and extrusion device flow rate (1-2 mL / min), and monitor the response mechanism of the monitoring and early warning system in real time to ensure that it responds quickly and acts accurately; (3) Start the dust handling system and put it into standby mode; (4) The raw materials are added to the material synthesis system in proportion (TiO2 accounts for 5% of the weight of the solution, LiOH·H2O accounts for 2.5% of the weight of the solution, and the mass ratio of HPMC:ethanol:deionized water in the solution is 1:12:8) to carry out the reaction. The synthesis product is transported to the ball milling device through the conveying pipeline. After thorough ball milling and initiation of high-energy ball milling reaction, a tritium breeding agent (Li2TiO3) slurry that meets the standard requirements is finally formed. (5) The tritium breeding agent (Li2TiO3) slurry that meets the process requirements is absorbed by the material supply device and transported to the material extrusion device through the feeding pipeline. Under the set pressure of 100N, it is uniformly extruded through the precision extrusion head and shaped, and finally tritium breeding agent (Li2TiO3) green pellets with complete structure and no internal stress are obtained. (6) Load the stress-free tritium breeding agent (Li2TiO3) blank small balls into the vacuum chamber, seal it and start the vacuuming program; when the vacuum degree of the chamber reaches ≤0.6pa, turn on the refrigeration device to carry out deep freezing treatment for 3 hours, and set the refrigeration temperature to -18℃. (7) The lithium ceramic microsphere blanks after low-temperature cold plasticizing are densified and sintered in a sintering device. The sintering process is as follows: hold at 280℃ for 2 hours, then raise the temperature to 780℃ for 2 hours, and then raise the temperature to 950℃ for 1 hour. A temperature field gradient is set in this sintering process. Through this sintering process, the diffusion and rearrangement of particles inside the blank can be significantly promoted, thereby effectively eliminating residual pores and greatly improving the final density and comprehensive mechanical strength of the material. (8) Precise sieving and efficient collection of the densified tritium amplifying agent microspheres: The process first involves multi-stage sieving using a sample sieving device according to the preset equal particle size specifications to achieve precise grading of the particle size range; after the sieving operation is completed, an automatic collection device classifies and collects the microspheres of each level to ensure sample integrity and batch consistency.
[0042] Example 3
[0043] A process for preparing lithium ceramic microspheres by a combination of extrusion molding and low-temperature cold plasticizing includes the following steps: (1) Start the PLC control system, load the control program, and after the system self-test is completed, check the communication connection status with each functional module in turn to ensure that the link is stable and reliable; (2) Set safety threshold parameters for key analog quantities (e.g., ball milling time (24h), dust concentration (< 1 mg / m³)). 3 (1) Temperature limit (≤60℃) and extrusion device flow rate (1-2 mL / min), and monitor the response mechanism of the monitoring and early warning system in real time to ensure that it responds quickly and acts accurately; (3) Start the dust handling system and put it into standby mode; (4) The raw materials are added to the material synthesis system in proportion (TiO2 accounts for 5% of the weight of the solution, LiOH·H2O accounts for 2.5% of the weight of the solution, and the mass ratio of HPMC:ethanol:deionized water in the solution is 0.5:11:7) to carry out the reaction. The synthesis product is transported to the ball milling device through the conveying pipeline. After thorough ball milling and initiation of high-energy ball milling reaction, a tritium breeding agent (Li2TiO3) slurry that meets the standard requirements is finally formed. (5) The tritium breeding agent (Li2TiO3) slurry that meets the process requirements is absorbed by the material supply device and transported to the material extrusion device through the feeding pipeline. Under the set pressure of 100N, it is uniformly extruded through the precision extrusion head and shaped, and finally tritium breeding agent (Li2TiO3) green pellets with complete structure and no internal stress are obtained. (6) Load the stress-free tritium breeding agent (Li2TiO3) blank small balls into the vacuum chamber, seal it and start the vacuuming program; when the vacuum degree of the chamber reaches ≤0.6pa, turn on the refrigeration device to carry out deep freezing treatment for 3 hours, and set the refrigeration temperature to -10℃. (7) The lithium ceramic microsphere blanks after low-temperature cold plasticizing are densified and sintered in a sintering device. The sintering process is as follows: hold at 300℃ for 2 hours, then raise the temperature to 800℃ and hold for 2 hours, then raise the temperature to 1000℃ and hold for 1 hour. A temperature field gradient is set in this sintering process. Through this sintering process, the diffusion and rearrangement of particles inside the blank can be significantly promoted, thereby effectively eliminating residual pores and greatly improving the final density and comprehensive mechanical strength of the material. (8) Precise sieving and efficient collection of the densified tritium amplifying agent microspheres: The process first involves multi-stage sieving using a sample sieving device according to the preset equal particle size specifications to achieve precise grading of the particle size range; after the sieving operation is completed, an automatic collection device classifies and collects the microspheres of each level to ensure sample integrity and batch consistency.
[0044] Example 4
[0045] A process for preparing lithium ceramic microspheres by a combination of extrusion molding and low-temperature cold plasticizing includes the following steps: (1) Start the PLC control system, load the control program, and after the system self-test is completed, check the communication connection status with each functional module in turn to ensure that the link is stable and reliable; (2) Set safety threshold parameters for key analog quantities (e.g., ball milling time (24h), dust concentration (< 1 mg / m³)). 3 (1) Temperature limit (≤60℃) and extrusion device flow rate (1-2 mL / min), and monitor the response mechanism of the monitoring and early warning system in real time to ensure that it responds quickly and acts accurately; (3) Start the dust handling system and put it into standby mode; (4) The raw materials are added to the material synthesis system in proportion (TiO2 accounts for 5% of the weight of the solution, LiOH·H2O accounts for 2.5% of the weight of the solution, and the mass ratio of HPMC:ethanol:deionized water in the solution is 1.5:10:9) to carry out the reaction. The synthesis product is transported to the ball milling device through the conveying pipeline. After thorough ball milling and initiation of high-energy ball milling reaction, a tritium breeding agent (Li2TiO3) slurry that meets the standard requirements is finally formed. (5) The tritium breeding agent (Li2TiO3) slurry that meets the process requirements is absorbed by the material supply device and transported to the material extrusion device through the feeding pipeline. Under the set pressure of 100N, it is uniformly extruded through the precision extrusion head and shaped, and finally tritium breeding agent (Li2TiO3) green pellets with complete structure and no internal stress are obtained. (6) Load the stress-free tritium breeding agent (Li2TiO3) blank small balls into the vacuum chamber, seal it and start the vacuuming program; when the vacuum degree of the chamber reaches ≤0.6pa, turn on the refrigeration device to carry out deep freezing treatment for 3 hours, and set the refrigeration temperature to -5℃; (7) The lithium ceramic microsphere blanks after low-temperature cold plasticizing are densified and sintered in a sintering device. The sintering process is as follows: hold at 320℃ for 1.5h, then raise the temperature to 820℃ for 1.5h, then raise the temperature to 1100℃ for 1h. A temperature field gradient is set in this sintering process. Through this sintering process, the diffusion and rearrangement of particles inside the blank can be significantly promoted, thereby effectively eliminating residual pores and greatly improving the final density and comprehensive mechanical strength of the material. (8) Precise sieving and efficient collection of the densified tritium amplifying agent microspheres: The process first involves multi-stage sieving using a sample sieving device according to the preset equal particle size specifications to achieve precise grading of the particle size range; after the sieving operation is completed, an automatic collection device classifies and collects the microspheres of each level to ensure sample integrity and batch consistency.
[0046] Comparative Example 1
[0047] This comparative example is based on Example 3. The difference between this comparative example and Example 3 is that the synthesized product was not ball-milled. The specific process is as follows: A process for preparing lithium ceramic microspheres by a combination of extrusion molding and low-temperature cold plasticizing includes the following steps: (1) Start the PLC control system, load the control program, and after the system self-test is completed, check the communication connection status with each functional module in turn to ensure that the link is stable and reliable; (2) Set the safety threshold parameters for key analog quantities (dust concentration < 1 mg / m³). 3 (1) Temperature limit (≤60℃) and extrusion device flow rate (1-2 mL / min), and monitor the response mechanism of the monitoring and early warning system in real time to ensure that it responds quickly and acts accurately; (3) Start the dust handling system and put it into standby mode; (4) The raw materials were added to the material synthesis system in the proportions of Example 3 to react and obtain the synthesis product—tritium breeder (Li2TiO3) slurry; (5) The tritium breeding agent (Li2TiO3) slurry that meets the process requirements is absorbed by the material supply device and transported to the material extrusion device through the feeding pipeline. Under the set pressure of 100N, it is uniformly extruded through the precision extrusion head and shaped, and finally tritium breeding agent (Li2TiO3) green pellets with complete structure and no internal stress are obtained. (6) Load the stress-free tritium breeding agent (Li2TiO3) blank small balls into the vacuum chamber, seal it and start the vacuuming program; when the vacuum degree of the chamber reaches ≤0.6pa, turn on the refrigeration device to carry out deep freezing treatment, and set the refrigeration temperature to -10℃. (7) The lithium ceramic microsphere blanks after low-temperature cold plasticizing are densified and sintered in a sintering device. The sintering process is as follows: hold at 300℃ for 2 hours, then raise the temperature to 800℃ and hold for 2 hours, then raise the temperature to 1000℃ and hold for 1 hour. A temperature field gradient is set in this sintering process. Through this sintering process, the diffusion and rearrangement of particles inside the blank can be significantly promoted, thereby effectively eliminating residual pores and greatly improving the final density and comprehensive mechanical strength of the material. (8) Precise sieving and efficient collection of the densified tritium amplifying agent microspheres: The process first involves multi-stage sieving using a sample sieving device according to the preset equal particle size specifications to achieve precise grading of the particle size range; after the sieving operation is completed, an automatic collection device classifies and collects the microspheres of each level to ensure sample integrity and batch consistency.
[0048] Comparative Example 2
[0049] This comparative example is based on Example 3. The difference between this comparative example and Example 3 is that: instead of using low-temperature cold plasticizing, a direct vacuuming method is used. The specific process is as follows: Includes the following steps: (1) Start the PLC control system, load the control program, and after the system self-test is completed, check the communication connection status with each functional module in turn to ensure that the link is stable and reliable; (2) Set safety threshold parameters for key analog quantities (e.g., ball milling time (24h), dust concentration (< 1 mg / m3), upper temperature limit (≤60℃) and extrusion device flow rate (1-2 mL / min)), and check the response mechanism of the monitoring and early warning system in real time to ensure that it responds quickly and acts accurately; (3) Start the dust handling system and put it into standby mode; (4) Each raw material is added to the material synthesis system in the proportion of Example 3 for reaction. The synthesis product is transported to the ball milling device through the conveying pipeline. Through full ball milling and initiation of high-energy ball milling reaction, a tritium breeder (Li2TiO3) slurry that meets the standard requirements is finally formed. (5) The tritium breeding agent (Li2TiO3) slurry that meets the process requirements is absorbed by the material supply device and transported to the material extrusion device through the feeding pipeline. Under the set pressure of 100N, it is uniformly extruded through the precision extrusion head and shaped, and finally tritium breeding agent (Li2TiO3) green pellets with complete structure and no internal stress are obtained. (6) Load the stress-free tritium breeding agent (Li2TiO3) blank small balls into the vacuum chamber, seal it and start the vacuuming program; wait until the vacuum degree of the chamber reaches ≤0.6pa; (7) The lithium ceramic microsphere blanks after vacuuming are densified by sintering in a sintering device. The sintering process is as follows: hold at 300℃ for 2 hours, then raise the temperature to 800℃ and hold for 2 hours, then raise the temperature to 1000℃ and hold for 1 hour. A temperature field gradient is set in this sintering process. Through this sintering process, the diffusion and rearrangement of particles inside the blank can be significantly promoted, thereby effectively eliminating residual pores and greatly improving the final density and comprehensive mechanical strength of the material. (8) Precise sieving and efficient collection of the densified tritium amplifying agent microspheres: The process first involves multi-stage sieving using a sample sieving device according to the preset equal particle size specifications to achieve precise grading of the particle size range; after the sieving operation is completed, an automatic collection device classifies and collects the microspheres of each level to ensure sample integrity and batch consistency.
[0050] The lithium ceramic microspheres obtained by sintering in Example 3, Comparative Examples 1 and 2 were subjected to relevant tests (100 microspheres were selected from each process), and the results are shown in Table 1.
[0051] Table 1. Relevant test data of lithium ceramic microspheres obtained by sintering in Example 3 and Comparative Examples 1 and 2. Differences in process Particle size uniformity Density Crushing strength Example 3 Ball milling + extrusion molding + low temperature cold plasticizing 95% 92% 50N-80N Comparative Example 1 Extrusion molding + low temperature cold plastic 70% 80% 30N-40N Comparative Example 2 Ball milling + extrusion molding + conventional molding 40% 75% 10N-20N
[0052] As can be seen from the data in Table 1: Comparative Example 1, by omitting the ball milling process, resulted in a slurry with a wide particle size distribution and hard agglomerates, leading to poor uniformity of the formed green body. This directly manifested as surface cracks and decreased density of the tritium breeder microspheres, a significant decrease in mechanical properties such as crushing strength, and a low sphericity qualification rate. This demonstrates that the ball milling process plays a crucial role in improving the density, uniformity, and final performance of the finished product by optimizing powder characteristics. Comparative Example 2 used conventional vacuum micro-shaping instead of low-temperature cold plasticizing, which directly resulted in insufficient structural strength of the green body and severe deformation during high-temperature sintering. This significantly reduced the yield of qualified small balls with uniform particle size, and also greatly reduced the density and mechanical properties of the small balls, such as crushing strength. This confirms that low-temperature cold plasticizing is crucial for maintaining the dimensional stability and final performance of uniform spherical products during the sintering process.
[0053] Finally, it should be noted that the above specific embodiments are only used to describe the purpose, technical solution, and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation of the present invention and is not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the foregoing specific 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 or improvements can be made to some or all of the technical features. These modifications, equivalent substitutions, and improvements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.
Claims
1. A process for preparing lithium ceramic microspheres by a combination of extrusion molding and low-temperature cryopreservation, characterized in that, Includes the following steps: TiO2, LiOH·H2O, and the solution were mixed and reacted in a certain proportion and then ball-milled to obtain Li2TiO3 slurry; Li2TiO3 slurry was extruded under a pressure of 90-110 N to obtain Li2TiO3 green spheres; The Li2TiO3 green blank spheres were frozen at -18℃ to 0℃ for 3-4 hours. Lithium ceramic microspheres were obtained by sintering the cryogenically treated Li2TiO3 green body microspheres.
2. The process for preparing lithium ceramic microspheres by a combination of extrusion molding and low-temperature cold plasticizing according to claim 1, characterized in that, TiO2 and LiOH·H2O account for 4-6% and 2-3% of the weight of the solution, respectively. The solution is a mixture of HPMC, ethanol and deionized water, with a mass ratio of (0.5-1.5):(10-12):(7-9).
3. The process for preparing lithium ceramic microspheres by a combination of extrusion molding and low-temperature cold plasticizing according to claim 1, characterized in that, The sintering process is as follows: hold at 280-320℃ for 1.5-2.5 hours, then raise the temperature to 780-820℃ and hold for 1.5-2.5 hours, then raise the temperature to 950-1100℃ and hold for 0.5-1.5 hours.
4. The process for preparing lithium ceramic microspheres by a combination of extrusion molding and low-temperature cold plasticizing according to claim 1, characterized in that, Also includes: The sintered lithium ceramic microspheres were subjected to multi-stage sieving.
5. An apparatus for preparing lithium ceramic microspheres by a combination of extrusion molding and low-temperature cryopreservation, characterized in that, include: Material synthesis device (4), used for reacting raw materials; The ball milling device (6) is connected to the outlet of the material synthesis device (4) and is used to ball mill the reactants to obtain tritium breeder slurry; The material extrusion device (9) is connected to the outlet of the ball mill device (6) and is used to extrude the tritium breeding agent slurry to obtain raw pellets; The low-temperature cold plastic system (10) is connected to the outlet of the material extrusion device (9) and is used to freeze the green preform balls. The sintering device (13) is connected to the outlet of the low-temperature cold plastic system (10) and is used to sinter the green blank spheres.
6. The apparatus for preparing lithium ceramic microspheres by a combination of extrusion molding and low-temperature cryopreservation according to claim 5, characterized in that, It also includes a multi-stage screening device (14) and a collection device (15) connected in sequence, wherein the multi-stage screening device (14) is connected to the outlet of the sintering device (13).
7. The apparatus for preparing lithium ceramic microspheres by a combination of extrusion molding and low-temperature cryopreservation according to claim 5, characterized in that, It also includes a dust treatment system (3), which is connected to the material synthesis device (4) and the ball mill device (6) for collecting and purifying dust.
8. The apparatus for preparing lithium ceramic microspheres by a combination of extrusion molding and low-temperature cryopreservation according to claim 7, characterized in that, It also includes a monitoring and early warning system (2), which is connected to the dust treatment system (3), the ball mill (6), and the sintering device (13) for monitoring temperature and pressure.
9. The apparatus for preparing lithium ceramic microspheres by a combination of extrusion molding and low-temperature cryopreservation according to claim 5, characterized in that, The ball mill (6) is connected to the material extrusion device (9) via the material supply device (7) and the feeding pipe (8).
10. The apparatus for preparing lithium ceramic microspheres by a combination of extrusion molding and low-temperature cryopreservation according to claim 5, characterized in that, The low-temperature cryopreservation system (10) includes a vacuum chamber (11) and a refrigeration device (12). The refrigeration device (12) is located inside the vacuum chamber (11) to generate a refrigeration environment. The blank spheres extruded by the extrusion device are sent into the vacuum chamber (11).