Nanometer metal material container-free synthesis device and synthesis method

Abstract

The invention discloses a container-free synthesis device and method for nano-metal materials, and relates to the technical field of nano-metal synthesis, the container-free synthesis device for the nano-metal materials comprises an operation unit, an acoustic levitation unit, a temperature and humidity unit and a gas unit, the acoustic levitation unit is provided with a levitation station, and the temperature and humidity unit is provided with a temperature and humidity unit; the sound suspension unit can make the nano metal suspend at the suspension station, the temperature and humidity unit can detect the temperature and humidity in the synthesis cavity and adjust the temperature and humidity in the synthesis cavity, the gas unit communicates with the synthesis cavity, and the gas unit can detect and adjust the gas pressure in the synthesis cavity; the gas flow mode in the synthesis chamber can also be adjusted to a constant gas mode or a flowing gas mode. According to the container-free synthesis device and the synthesis method for the nano-metal material, the temperature, the humidity, the gas flowing mode and other conditions can be accurately controlled in the synthesis process of the nano-metal material, so that the performance of the nano-metal material is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of nano-metal synthesis, and particularly to a containerless synthesis device and a synthesis method for nano-metal materials. Background Art

[0002] When the material is reduced to the nanoscale, due to the existence of the quantum size effect, its physical and chemical properties will be significantly different from those of macroscopic materials. Among them, nano-metal materials have higher reaction activity and have been widely used in various fields. At present, the preparation of nano-metal materials is mostly carried out in test tubes, beakers or reaction kettles. Since the preparation materials are in direct contact with the container, it is easy for impurities to mix in and introduce heterogeneous nucleation, which in turn affects the nucleation and growth of nano-metal materials. The acoustic levitation technology is an important containerless material processing technology, which can synthesize and prepare nano-metal materials in a containerless state, avoiding adverse situations for nano-metal materials. However, most of the nano-metal materials currently prepared by acoustic levitation devices cannot control conditions such as temperature, humidity, and gas flow mode during synthesis. Therefore, there is an urgent need for a containerless synthesis device and a synthesis method for nano-metal materials that can precisely control conditions such as temperature, humidity, and gas flow mode during the synthesis of nano-metals, so as to further improve the performance of nano-metal materials. Summary of the Invention

[0003] The purpose of the present invention is to provide a containerless synthesis device and a synthesis method for nano-metal materials to solve the problems existing in the above-mentioned prior art, and to be able to precisely control conditions such as temperature, humidity, and gas flow mode during the synthesis of nano-metals, so as to further improve the performance of nano-metal materials.

[0004] To achieve the above purpose, the present invention provides the following solutions:

[0005] The present invention provides a containerless synthesis device for nano-metal materials, including: an operation unit, an acoustic levitation unit, a temperature and humidity unit, and a gas unit. There is a synthesis cavity in the operation unit. The acoustic levitation unit and the temperature and humidity unit are both arranged in the synthesis cavity. The acoustic levitation unit has a suspension station, and the acoustic levitation unit can levitate nano-metal at the suspension station. The temperature and humidity unit can detect the temperature and humidity in the synthesis cavity and adjust the temperature and humidity in the synthesis cavity. The gas unit is communicated with the synthesis cavity. The gas unit can detect and adjust the air pressure in the synthesis cavity, and can also adjust the gas flow mode in the synthesis cavity to a constant gas mode or a flowing gas mode.

[0006] In some embodiments, the acoustic levitation unit includes: an ultrasonic emission structure and an ultrasonic reflection structure. Both the ultrasonic emission structure and the ultrasonic reflection structure are fixedly connected in the synthesis cavity. The emission end of the ultrasonic emission structure and the reflection end of the ultrasonic reflection structure are oppositely arranged with a spacing therebetween, and a levitation station is formed between the emission end of the ultrasonic emission structure and the reflection end of the ultrasonic reflection structure.

[0007] In some embodiments, the acoustic levitation unit further includes: a lifting device and a bracket. The lifting device is fixedly connected in the operation unit. The lifting device has a free end, and the ultrasonic reflection structure is fixedly connected to the free end. The free end can move in the vertical direction. The bracket is fixedly connected in the synthesis cavity. The bracket has a mounting section located above the ultrasonic reflection structure, and the ultrasonic emission structure is fixedly connected to the mounting section.

[0008] In some embodiments, the gas unit includes: a pressure detector, a vacuum gauge, a mechanical pump, an exhaust pipe, a gate valve, an intake valve, a bleed valve, a gas source, a connecting pipe, and a pressure reducing valve. An exhaust port communicating the synthesis cavity with the outside is provided on the operation unit. One end of the exhaust pipe is communicated with the mechanical pump, and the other end is connected and communicated with the exhaust port. The gate valve is provided on the exhaust pipe, and the vacuum gauge is provided in the synthesis cavity. An intake port communicating the synthesis cavity with the outside is provided on the operation unit, and an air outlet communicating the synthesis cavity with the outside is provided on the operation unit. One end of the connecting pipe is connected and communicated with the gas source, and the other end is connected and communicated with the intake port. The intake valve and the pressure reducing valve are both provided on the connecting pipe, the bleed valve is provided on the air outlet, and the pressure detector is provided in the synthesis cavity.

[0009] In some embodiments, the temperature and humidity unit includes: a controller, and a temperature sensor, a heater, a cooler, a humidity sensor, and a humidity controller provided in the synthesis cavity. The controller is respectively in signal connection with the temperature sensor, the heater, the cooler, the humidity sensor, and the humidity controller.

[0010] In some embodiments, it further includes a monitoring unit, the monitoring unit has an image monitoring end and a temperature monitoring end, and the monitoring unit can collect images of the mixed droplets carrying nano-metal and monitor the temperature of the mixed droplets carrying nano-metal; the surface of the operation unit is made of a transparent material, and the monitoring unit includes: an infrared thermal imager and a high-speed camera, both the infrared thermal imager and the high-speed camera are arranged outside the operation unit, an infrared window and an imaging window are fixedly connected to the operation unit, the infrared emission head of the infrared thermal imager faces the infrared window, and the infrared thermal imager can detect the temperature of the mixed droplets carrying nano-metal through the infrared window; the camera of the high-speed camera faces the imaging window, and the high-speed camera can collect images of the mixed droplets carrying nano-metal through the imaging window.

[0011] In some embodiments, it further includes a metal heating device, the metal heating device is arranged outside the operation unit, a heating port is arranged on one side of the synthesis cavity, the axis of the heating port passes through the suspension station, the metal heating device has a heat output end, and the heat output end can heat the preparation raw materials on the suspension station through the heating port.

[0012] In some embodiments, it further includes a laser protection plate and a laser window, the metal heating device includes: a laser emitter and a laser controller, the laser window has a laser channel, the laser window is fixedly connected to the outer side wall of the operation unit, one end of the laser channel communicates with the heating port, a transparent protection sheet is arranged in the laser channel, the laser controller is signal-connected to the laser emitter, the inner side wall of the operation unit where the heating port is arranged is the first side wall, and the inner side wall opposite to the first side wall is the second side wall, the laser protection plate is fixedly connected to the second side wall, the laser emitter is arranged outside the operation unit, and the laser emitter can emit laser to the preparation raw materials on the suspension station through the laser window under the control of the laser controller.

[0013] In some embodiments, the operation unit includes a box body and operation gloves, two glove openings are arranged on the side surface of the box body, the circumferential edges of the openings of the two operation gloves are respectively fixedly connected to the circumferential edges of the two glove openings, the space inside the box body forms the synthesis cavity, and both of the two operation gloves are located inside the synthesis cavity.

[0014] The present invention also provides a method for containerless synthesis of nano-metal materials, including the following steps:

[0015] Place the preparation raw materials in the synthesis cavity, adjust the air pressure in the synthesis cavity to a preset air pressure value through the gas unit, adjust the gas flow pattern in the synthesis cavity to a constant gas mode or a flowing gas mode through the gas unit, and adjust the temperature and humidity in the synthesis cavity to a preset temperature and a preset humidity through the temperature and humidity unit; turn on the acoustic levitation unit, move the preparation raw materials to the levitation station, make the preparation raw materials levitate through the acoustic levitation unit, and after the reaction of the preparation raw materials at the levitation station reaches the preset time, a liquid droplet carrying a nano-metal material is obtained.

[0016] The present invention has achieved the following technical effects compared with the prior art:

[0017] The containerless synthesis device for nano-metal materials provided by the present invention can adjust the air pressure in the synthesis cavity to a preset air pressure value through the gas unit, adjust the gas flow rate in the synthesis cavity to a constant gas mode or a flowing gas mode, and adjust the temperature and humidity in the synthesis cavity to a preset temperature and a preset humidity through the temperature and humidity unit, so as to provide a suitable environment for the preparation and synthesis of nano-metal materials; then, turn on the acoustic levitation unit, place the preparation raw materials at the levitation station, make the preparation raw materials levitate through the acoustic levitation device, after a period of time, the reaction of the preparation raw materials is completed, a mixed liquid droplet carrying a nano-metal material is obtained, and finally the mixed liquid droplet is dried to obtain the finished nano-metal material. Since the preparation environment of the mixed liquid droplet is always suitable, the performance of the finally obtained finished nano-metal material is relatively high.

[0018] Furthermore, the monitoring unit can obtain the temperature and image of the mixed liquid droplet of nano-metal in real time, and the obtained temperature information and image information can be used in subsequent simulation calculations.

[0019] Furthermore, during the preparation process, the environmental temperature may not be able to make the preparation raw materials reach the required temperature. At this time, the preparation raw materials can be directly heated by the metal heating device and lifted to the temperature required for preparation. Description of the Drawings

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0021] Figure 1 It is a three-dimensional structure diagram of one perspective of the containerless synthesis device for nano-metal materials in some embodiments of the present invention;

[0022] Figure 2 For Figure 1Three-dimensional structure diagram of the containerless synthesis device for medium and nano metal materials from another perspective;

[0023] Figure 3 For Figure 1 Internal structure diagram of the containerless synthesis device for medium and nano metal materials;

[0024] Figure 4 In (a) is the image captured by a high-speed CCD during the preparation process of the medium and nano metal materials, and (b) is the image captured by an infrared thermal imager during the preparation process of the medium and nano metal materials;

[0025] Figure 5 Is the reflection loss projection diagram of the microwave absorption performance of the ZIF-67 derivative Co@CNTs obtained in Example 3 and Comparative Example 1;

[0026] In the figure: 1. Operating unit; 2. Acoustic suspension unit; 3. Suspension station; 4. Ultrasonic emission structure; 5. Ultrasonic reflection structure; 6. Lifting equipment; 7. Bracket; 8. Ultrasonic power supply; 9. Mechanical pump; 10. Exhaust pipe; 11. Gate valve; 12. Intake valve; 13. Exhaust valve; 14. Connecting pipe; 15. Temperature sensor; 16. Heater; 17. Refrigerator; 18. Humidity sensor; 19. Humidity controller; 20. Infrared thermal imager; 21. High-speed camera; 22. Laser emitter; 23. Infrared window; 24. Imaging window; 25. Laser protection plate; 26. Laser window; 27. Glove port; 28. Beaker; 29. Balance; 30. Pipette; 31. Tip storage box. Detailed implementation manners

[0027] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0028] The purpose of the present invention is to provide a containerless synthesis device and synthesis method for medium and nano metal materials to solve the problems existing in the above-mentioned prior art, and can accurately control conditions such as temperature, humidity, and gas flow pattern during the synthesis of medium and nano metals, thereby further improving the performance of medium and nano metal materials.

[0029] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0030] Example 1

[0031] This embodiment provides a containerless synthesis device for nano-metal materials, as Figures 1-3 shown, which includes: an operation unit 1, an acoustic levitation unit 2, a temperature and humidity unit, and a gas unit. There is a synthesis cavity in the operation unit 1. The acoustic levitation unit 2 and the temperature and humidity unit are both arranged in the synthesis cavity. The acoustic levitation unit 2 has a suspension station 3. The acoustic levitation unit 2 can levitate the nano-metal at the suspension station 3. The temperature and humidity unit can detect the temperature and humidity in the synthesis cavity and adjust the temperature and humidity in the synthesis cavity. The gas unit is communicated with the synthesis cavity. The gas unit can detect and adjust the air pressure in the synthesis cavity, and can also adjust the gas flow mode in the synthesis cavity to a constant gas mode or a flowing gas mode.

[0032] For the containerless synthesis device for nano-metal materials provided in this embodiment, the air pressure in the synthesis cavity can be adjusted to a preset air pressure value through the gas unit, the gas flow velocity in the synthesis cavity can be adjusted to a constant gas mode or a flowing gas mode, and the temperature and humidity in the synthesis cavity can be adjusted to a preset temperature and a preset humidity through the temperature and humidity unit, so as to provide a suitable environment for the preparation and synthesis of nano-metal materials; then, the acoustic levitation unit 2 is turned on, the preparation raw materials are arranged at the suspension station 3, and the preparation raw materials are levitated by the acoustic levitation device. After a period of time, the reaction of the preparation raw materials is completed, and a mixed liquid droplet carrying nano-metal materials is obtained. Finally, the mixed liquid droplet is dried to obtain the finished nano-metal materials. Since the preparation environment of the mixed liquid droplet is always in suitable conditions, the performance of the finally obtained finished nano-metal materials is relatively high. Among them, for the convenience of operation, test tools such as a beaker 28, a balance 29, and a medicine spoon are also arranged in the operation unit 1, as well as a pipette 30 for transferring liquids and a pipette tip storage box 31 for storing the tips of the pipette 30.

[0033] In an implementation manner of this embodiment, the acoustic levitation unit 2 includes: an ultrasonic emission structure 4 and an ultrasonic reflection structure 5. The ultrasonic emission structure 4 and the ultrasonic reflection structure 5 are both fixedly connected in the synthesis cavity. The emission end of the ultrasonic emission structure 4 and the reflection end of the ultrasonic reflection structure 5 are oppositely arranged with a spacing. A suspension station 3 is formed between the emission end of the ultrasonic emission structure 4 and the reflection end of the ultrasonic reflection structure 5. The ultrasonic emission structure 4 and the ultrasonic reflection structure 5 can form a standing wave sound field with an ultrasonic potential well at the suspension station 3 and realize the suspension of the preparation raw materials or the mixed liquid droplets carrying nano-metal. Among them, the ultrasonic frequency is 20 - 22 kHz, the ultrasonic power is 400 - 500 W, the end face of the emission end is a plane, the cross-sectional area of the end face is 20 mm 2 , the end face of the reflection end is a spherical concave surface, the radius of curvature is 25 mm - 50 mm, and the cross-sectional diameter of the end face is 35 mm - 45 mm; both the ultrasonic emission structure 4 and the ultrasonic reflection structure 5 are connected to an ultrasonic power supply 8.

[0034] In an implementation manner of this first embodiment, the acoustic levitation unit 2 further includes: a lifting device 6 and a bracket 7. The lifting device 6 is fixedly connected inside the operation unit 1. The lifting device 6 has a free end, and the ultrasonic reflection structure 5 is fixedly connected to the free end. The free end can move in the vertical direction. The bracket 7 is fixedly connected inside the synthesis cavity. The bracket 7 has a mounting section located above the ultrasonic reflection structure 5, and the ultrasonic emission structure 4 is fixedly connected to the mounting section. During preparation, the vertical position of the ultrasonic reflection structure 5 can be adjusted by the lifting device 6 to change the distance between the ultrasonic emission structure 4 and the ultrasonic reflection structure 5, thereby changing the parameters of the standing wave sound field, so that the preparation raw materials or the mixed droplets carrying nano metals can be stably levitated.

[0035] In an implementation manner of this first embodiment, the gas unit includes: a pressure detector, a vacuum gauge, a mechanical pump 9, an exhaust pipe 10, a gate valve 11, an intake valve 12, a bleed valve 13, a gas source, a connecting pipe 14, and a pressure reducing valve. An exhaust port communicating the synthesis cavity with the outside is provided on the operation unit 1. One end of the exhaust pipe 10 is communicated with the mechanical pump 9, and the other end is connected and communicated with the exhaust port. The gate valve 11 is provided on the exhaust pipe 10, and the vacuum gauge is provided inside the synthesis cavity; an intake port communicating the synthesis cavity with the outside is provided on the operation unit 1, and an air outlet communicating the synthesis cavity with the outside is provided on the operation unit 1. One end of the connecting pipe is connected and communicated with the gas source, and the other end is connected and communicated with the intake port. Both the intake valve 12 and the pressure reducing valve are provided on the connecting pipe, and the bleed valve 13 is provided on the air outlet, and the pressure detector is provided inside the synthesis cavity. Before preparation, the gate valve 11 can be opened, and the gas inside the operation unit 1 can be pumped out by the mechanical pump 9. At the same time, the air pressure inside the operation unit 1 can be detected by the vacuum gauge until the operation unit 1 is in a vacuum state; then, the gate valve 11 is closed, and the intake valve 12 is opened to allow the gas in the gas source to enter the operation unit 1. At the same time, the flow rate of the gas is controlled by controlling the opening degree of the pressure reducing valve until the value on the pressure detector reaches the preset pressure. At this time, if it is necessary to enter the constant air flow mode, the intake valve 12 is closed; if it is necessary to enter the flowing air flow mode, the intake valve 12 and the throttle valve are kept open, and at the same time the bleed valve 13 is opened. The gas source continuously inputs gas into the operation unit 1 and discharges it from the air outlet, and the air pressure inside the synthesis cavity remains unchanged while the gas is always in a flowing state.

[0036] In an implementation manner of the first embodiment, the temperature and humidity unit includes: a controller, and a temperature sensor 15, a heater 16, a cooler 17, a humidity sensor 18, and a humidity controller 19 disposed in the synthesis cavity. The controller is respectively in signal connection with the temperature sensor 15, the heater 16, the cooler 17, the humidity sensor 18, and the humidity controller 19. Under the control of the controller, the heater 16 can increase the temperature in the synthesis cavity according to the temperature obtained by the temperature sensor 15, the cooler 17 can decrease the temperature in the synthesis cavity according to the temperature obtained by the temperature sensor 15, the humidity sensor 18 can obtain the humidity in the synthesis cavity, and the humidity controller 19 can control the humidity in the synthesis cavity according to the humidity obtained by the humidity sensor 18 under the control of the controller. Through the temperature and humidity unit, the temperature and humidity in the synthesis cavity are accurately and real-time obtained and controlled, thereby providing a better environment for the synthesis of nano-metal materials.

[0037] In an implementation manner of the first embodiment, a monitoring unit is further included. The monitoring unit has an image monitoring end and a temperature monitoring end, and the monitoring unit can collect the image of the mixed droplet carrying nano-metal and monitor the temperature of the mixed droplet carrying nano-metal. The monitoring unit can obtain the temperature and image of the mixed droplet of nano-metal in real time, and the obtained temperature information and image information can be used for subsequent simulation calculations.

[0038] In an implementation manner of the first embodiment, the surface of the operation unit 1 is made of a transparent material. The monitoring unit includes: an infrared thermal imager 20 and a high-speed camera 21 (high-speed CCD). Both the infrared thermal imager 20 and the high-speed camera 21 are disposed outside the operation unit 1. An infrared window 23 and an imaging window 24 are fixedly connected to the operation unit 1. The infrared emission head of the infrared thermal imager 20 faces the infrared window 23, and the infrared thermal imager 20 can detect the temperature of the mixed droplet carrying nano-metal through the infrared window 23; the camera of the high-speed camera 21 faces the imaging window 24, and the high-speed camera 21 can collect the image of the mixed droplet carrying nano-metal through the imaging window 24. The temperature measurement range of the common infrared thermal imager 20 on the market is -20 to 2000 °C, and it can meet the detection requirements in the preparation after calibration; the maximum number of frames of the high-speed CCD can reach 10,000 frames, which can provide rich process images and detailed information. Among them, the images obtained by using the infrared thermal imager 20 and the high-speed camera 21 (high-speed CCD) are as Figure 4 shown.

[0039] In one implementation of this first embodiment, it further includes a metal heating device. The metal heating device is arranged outside the operation unit. There is a heating port on one side of the synthesis chamber. The axis of the heating port passes through the suspension station 3. The metal heating device has a heat output end, and the heat output end can heat the nano metal on the suspension station 3 through the heating port. During the preparation process, the ambient temperature may not be able to raise the preparation raw materials to the required temperature. At this time, the metal heating device can be directly used to heat the preparation raw materials and raise the preparation raw materials to the required temperature for preparation. Generally, within 50 °C, the heater 16 can be used to change the ambient temperature. If a higher temperature is required, the suspension droplets are heated separately by the metal heating device.

[0040] In one implementation of this first embodiment, it further includes a laser protection plate 25 and a laser window 26. The metal heating device includes: a laser emitter 22 and a laser controller. The laser window 26 has a laser channel. The laser window 26 is fixedly connected to the outer side wall of the operation unit 1. One end of the laser channel communicates with the heating port. A transparent protection sheet is arranged in the laser channel. The laser controller is signal-connected to the laser emitter 22. The inner side wall of the operation unit 1 where the heating port is arranged is the first side wall, and the inner side wall opposite to the first side wall is the second side wall. The laser protection plate 25 is fixedly connected to the second side wall. The laser emitter 22 is arranged outside the operation unit 1. The laser emitter 22 can emit laser to the preparation raw materials on the suspension station 3 through the laser window 26 under the control of the laser controller. The laser can pass through the heating port and irradiate the preparation raw materials through the transparent protection sheet, so as to quickly heat the preparation raw materials to the required temperature for preparation; the laser protection plate 25 can prevent the laser from irradiating the operation unit 1 and damaging the operation unit 1; the transparent protection sheet can play a sealing role for the interior of the operation unit 1. Among them, the laser emitter 22 can be selected from a fiber laser or a neodymium-doped yttrium aluminum garnet laser (YAG laser). The power range of the laser is preferably 10 W - 2000 W. The laser controller can also switch to a continuous laser mode or a pulsed laser mode according to the laser power and preparation requirements.

[0041] It should be noted that the laser emitter 22, the infrared thermal imager 20, and the high-speed camera 21 in this embodiment can all be supported outside the operation unit 1 by support devices such as tripods; the infrared window 23, the imaging window 24, and the laser window 26 are all flange windows.

[0042] In an implementation manner of this first embodiment, the operation unit 1 includes a box body and operation gloves. There are two glove openings 27 provided on the side surface of the box body. The circumferential edges of the openings of the two operation gloves are respectively fixedly connected to the circumferential edges of the two glove openings 27. The space inside the box body forms a synthesis cavity, and both operation gloves are located inside the synthesis cavity. When conducting the preparation, the staff can operate the preparation raw materials and the like inside the operation unit 1 through the operation gloves, so as to complete the preparation of nano metals under the condition of ensuring good sealing and suitable environment inside the synthesis cavity. Among them, the box body includes a bottom platform and a protective shell. One end of the protective shell has an opening, and the circumferential edge of the opening of the protective shell is fixedly connected to the upper side of the bottom platform. The protective shell is preferably made of transparent acrylic material, with a controllable temperature range of -10 to 50 °C and an error of ±0.5 °C. The controllable humidity range is 10 to 90% RH, with an error of ±3% RH, and the pressure-bearing range is -0.1 to 0.3 MPa.

[0043] It should be noted that in addition to operating with operation gloves, a robotic arm signal-connected to a computer can also be provided inside the box body, and the staff controls the robotic arm through the computer outside the box body to conduct the preparation operation.

[0044] Second Embodiment

[0045] This embodiment provides a method for containerless synthesis of nano metal materials, including the following steps: setting the preparation raw materials in the synthesis cavity, adjusting the air pressure in the synthesis cavity to a preset air pressure value through the gas unit, adjusting the gas flow mode in the synthesis cavity to a constant gas mode or a flowing gas mode through the gas unit, adjusting the temperature and humidity in the synthesis cavity to a preset temperature and a predetermined humidity through the temperature and humidity unit; turning on the acoustic levitation unit 2, moving the preparation raw materials to the suspension station 3, and suspending the preparation raw materials through the acoustic levitation unit 2. After the preparation raw materials react at the suspension station 3 for a preset time, nano metal material droplets are obtained.

[0046] The method for containerless synthesis of nano metal materials provided in this embodiment, using the nano metal material containerless synthesis device in the first embodiment, can precisely control conditions such as temperature, humidity, and gas flow mode, improving the performance of the nano metal finished product. Among them, the reaction time of the preparation raw materials at the suspension station 3 can be calculated according to conditions such as the mass and purity of the preparation raw materials to obtain an appropriate preset time.

[0047] Third Embodiment

[0048] This embodiment provides a specific example of nano metal synthesis using the nano metal synthesis device in some implementation manners of the first embodiment:

[0049] Place chemicals such as deionized water, cobalt(II) nitrate hexahydrate powder, and 2-methylimidazole powder in the synthesis chamber. Open the gate valve 11, turn on the mechanical pump 9 and evacuate the air. When the pressure in the synthesis chamber reaches -0.1 MPa, close the gate valve 11, open the intake valve 12 and adjust the pressure reducing valve, and backfill argon gas into the synthesis chamber through the gas source. When the vacuum degree displayed on the vacuum gauge returns to one standard atmosphere, keep the intake valve 12 open, and at the same time open the bleed valve, and adjust the opening degree of the throttle valve so that the gas in the synthesis chamber is in a flowing gas mode with the pressure maintained at one standard atmosphere.

[0050] Operate the controller and set the temperature in the synthesis chamber to 20 °C and the humidity to 66% RH.

[0051] Weigh 500 mg of cobalt(II) nitrate hexahydrate powder with a balance 29 and dissolve it in 4.25 mL of deionized water to obtain an aqueous cobalt nitrate solution. Dissolve 8185 mg of 2-methylimidazole powder in 29.75 mL of water to obtain an aqueous 2-methylimidazole solution.

[0052] Turn on the ultrasonic power supply 8, output ultrasonic waves with a power of 450 W and a frequency of 21.8 kHz. Pre-drop the liquid at the suspension station 3 and observe the changes in the liquid. Visually search for the position of the ultrasonic potential well. After determining the position of the ultrasonic potential well, use a pipette 30 to aspirate 10 μL of the aqueous cobalt nitrate solution and place it in the ultrasonic potential well, and adjust the position of the free end of the lifting device 6 to change the distance between the reflection end and the emission end, and make the cobalt nitrate aqueous droplet reach a stable suspension state.

[0053] Turn on the infrared thermal imager 20 and the high-speed CCD. Calibrate the emissivity of the infrared thermal imager 20 according to the ambient temperature (20 °C) in the cavity. Adjust the high-speed CCD to focus on the preparation raw materials, set the number of frames of the high-speed CCD to 1000 frames, and start collecting temperature and image data.

[0054] Use a pipette 30 to quickly inject 70 μL of the aqueous 2-methylimidazole solution into the suspended cobalt nitrate aqueous droplet to form a finished product mixed droplet. During the injection process, it is necessary to avoid introducing the residual gas in the pipette 30 into the droplet to prevent the appearance of bubbles, and at the same time appropriately adjust the height of the free end of the lifting table to avoid the droplet from falling.

[0055] After 3 minutes, use a pipette 30 to aspirate the reacted finished product mixed droplet to obtain a finished product mixed droplet carrying the nanometal material.

[0056] Turn off the infrared thermal imager 20 and the high-speed CCD. Close the intake valve 12, the gate valve 11 and the ultrasonic power supply 8. When the temperature in the synthesis chamber returns to room temperature, close the bleed valve, and take out the finished product mixed droplet carrying the nanometal material.

[0057] In the above steps, the finished product mixed liquid droplets carry ZIF-67 nanoparticles, whose size distribution ranges from 100 to 450 nm, and the average particle size is 263 nm.

[0058] Comparative Example 1

[0059] This example provides a comparative experiment for Example 3. The difference from Example 3 is that a acoustic levitation device is not used.

[0060] Inject 4.25 mL of deionized water into one container and 29.75 mL of water into another container. After the temperature in the synthesis chamber is stabilized at 20 °C and the humidity is stabilized at 66% RH, weigh 500 mg of cobalt(II) nitrate hexahydrate powder with a balance 29 and dissolve it in 4.25 mL of deionized water to obtain an aqueous cobalt(II) nitrate solution; dissolve 8185 mg of 2-methylimidazole powder in 29.75 mL of water to obtain an aqueous 2-methylimidazole solution. Use a pipette 30 to take 1.25 mL of the aqueous cobalt(II) nitrate solution and inject it into a container, and then add 8.75 mL of the aqueous 2-methylimidazole solution to the container containing 1.25 mL of the aqueous cobalt(II) nitrate solution. After a period of time, collect the comparative mixed liquid droplets carrying the nanometal material.

[0061] Using the above method, the comparative mixed liquid droplets carry ZIF-67 nanoparticles, whose size distribution ranges from 150 to 650 nm, and the average particle size is 381 nm.

[0062] Compare the products in Example 3 and Comparative Example 1:

[0063] Perform the following operations on the collected finished product mixed liquid droplets and comparative mixed liquid droplets respectively: Let them stand for 1 h, then place them in a centrifuge with a rotation speed of 9000 rpm and centrifuge for 3 min to obtain the lower layer precipitate. Wash the lower layer precipitate 5 times with methanol, and place the washed lower layer precipitate in an oven and dry it at 60 °C for 12 h to obtain the finished product ZIF-67 powder particles and the comparative ZIF-67 powder particles respectively.

[0064] Weigh 80 mg each of the finished product ZIF-67 powder particles and the comparative ZIF-67 powder particles, and perform the following operations respectively: Grind and mix them evenly with 480 mg of melamine powder in a mortar to obtain a mixed solid powder. Place the solid powder in a crucible, and then place the crucible in a tube furnace. Under the protection of flowing nitrogen, keep it at a temperature of 50 °C for 1 h, then heat it to 700 °C at a heating rate of 5 °C / min and keep it for 2 h to cause the carbonization reaction of ZIF-67 and melamine, and then naturally cool it with the furnace to obtain the finished product Co@CNTs powder and the comparative Co@CNTs powder.

[0065] The following operations were performed on the finished Co@CNTs powder and the comparative Co@CNTs powder respectively: The Co@CNTs powder was placed in a mortar and ground thoroughly to obtain a ground product, which was mixed with paraffin in a ratio of 1:9, heated to 60 °C, and then poured into a mold and pressed into shape to obtain a ring with an inner diameter of 3 mm and an outer diameter of 7 mm.

[0066] The electromagnetic wave absorption performance of the ring was tested by a vector network analyzer using the coaxial method. The test frequency band was 2 - 18 GHz, and the test results are as Figure 5 shown: The minimum reflection loss of the finished Co@CNTs was as low as -49.4 dB, and the maximum effective bandwidth could reach 6 GHz. The minimum reflection loss of the comparative Co@CNTs was -33.4 dB, and the maximum effective bandwidth was 5.4 GHz.

[0067] Figure 5 It shows the variation trend of the reflection loss of Co@CNTs with the matching thickness in the frequency range of 2 - 18 GHz. It can be seen from the figure that under the condition of acoustic levitation, the minimum reflection loss of the finished Co@CNTs was as low as -49.4 dB, the maximum effective bandwidth was 6 GHz, and the corresponding material thickness was 2 mm. The minimum reflection loss of the comparative Co@CNTs was as low as -33.4 dB, the maximum effective bandwidth was 5.4 GHz, and the corresponding material thickness was 1.8 mm.

[0068] According to the above detections, it can be concluded that the finished Co@CNTs prepared from the derivative of ZIF-67 prepared by the containerless synthesis device of the nano-metal material in Example 1 is superior to the comparative Co@CNTs prepared from the derivative of ZIF-67 in Comparative Example 1 in terms of electromagnetic wave absorption intensity and absorption width.

[0069] In the present invention, specific examples are used to elaborate the principle and implementation mode of the present invention. The description of the above examples is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A containerless synthesis device for nano metal materials, characterized in that: Comprising: An operation unit, an acoustic levitation unit, a temperature and humidity unit, and a gas unit. There is a synthesis chamber within the operation unit. The acoustic levitation unit and the temperature and humidity unit are both disposed within the synthesis chamber. The acoustic levitation unit has a levitation station, and the acoustic levitation unit can levitate nano metals at the levitation station. The temperature and humidity unit can detect the temperature and humidity within the synthesis chamber and adjust the temperature and humidity within the synthesis chamber. The gas unit is in communication with the synthesis chamber. The gas unit can detect and adjust the air pressure within the synthesis chamber and can also adjust the gas flow mode within the synthesis chamber to a constant gas mode or a flowing gas mode.

2. The containerless synthesis device for nano metal materials according to claim 1, characterized in that: The acoustic levitation unit includes: an ultrasonic emission structure and an ultrasonic reflection structure. Both the ultrasonic emission structure and the ultrasonic reflection structure are fixedly connected within the synthesis chamber. The emission end of the ultrasonic emission structure and the reflection end of the ultrasonic reflection structure are oppositely arranged with a spacing therebetween, and a levitation station is formed between the emission end of the ultrasonic emission structure and the reflection end of the ultrasonic reflection structure.

3. The containerless synthesis device for nano-metal materials according to claim 2, wherein: The acoustic levitation unit further includes: a lifting device and a bracket. The lifting device is fixedly connected within the operation unit. The lifting device has a free end, and the ultrasonic reflection structure is fixedly connected to the free end. The free end can move in the vertical direction. The bracket is fixedly connected within the synthesis chamber. The bracket has a mounting section located above the ultrasonic reflection structure, and the ultrasonic emission structure is fixedly connected to the mounting section.

4. The containerless synthesis device for nano metal materials according to claim 1, characterized in that: The gas unit includes: a pressure detector, a vacuum gauge, a mechanical pump, an extraction pipe, a gate valve, an intake valve, a bleed valve, a gas source, a connecting pipe, and a pressure reducing valve. An extraction port communicating the synthesis chamber with the outside is provided on the operation unit. One end of the extraction pipe is in communication with the mechanical pump, and the other end is connected and in communication with the extraction port. The gate valve is provided on the extraction pipe, and the vacuum gauge is provided within the synthesis chamber. An intake port communicating the synthesis chamber with the outside is provided on the operation unit, and an outlet port communicating the synthesis chamber with the outside is provided on the operation unit. One end of the connecting pipe is connected and in communication with the gas source, and the other end is connected and in communication with the intake port. The intake valve and the pressure reducing valve are both provided on the connecting pipe, the bleed valve is provided on the outlet port, and the pressure detector is provided within the synthesis chamber.

5. The containerless synthesis device for nano metal materials according to claim 1, characterized in that: The temperature and humidity unit includes: a controller, and a temperature sensor, a heater, a cooler, a humidity sensor, and a humidity controller provided within the synthesis chamber. The controller is in signal connection with the temperature sensor, the heater, the cooler, the humidity sensor, and the humidity controller respectively.

6. The containerless synthesis device for nano metal materials according to claim 1, wherein: It further includes a monitoring unit. The monitoring unit has an image monitoring end and a temperature monitoring end. The monitoring unit can collect images of the mixed droplets carrying nano metals and monitor the temperature of the mixed droplets carrying nano metals. The surface of the operation unit is made of a transparent material. The monitoring unit includes an infrared thermal imager and a high-speed camera. Both the infrared thermal imager and the high-speed camera are arranged outside the operation unit. An infrared window and an imaging window are fixedly connected to the operation unit. The infrared emission head of the infrared thermal imager faces the infrared window, and the infrared thermal imager can detect the temperature of the mixed droplets carrying nano-metal through the infrared window; the camera of the high-speed camera faces the imaging window, and the high-speed camera can collect images of the mixed droplets carrying nano-metal through the imaging window.

7. The containerless synthesis device for nano metal materials according to claim 1, characterized in that: It further includes a metal heating device. The metal heating device is arranged outside the operation unit. A heating port is arranged on one side of the synthesis chamber. The axis of the heating port passes through the suspension station. The metal heating device has a heat output end, and the heat output end can heat the preparation raw materials at the suspension station through the heating port.

8. The containerless synthesis device for nano metal materials according to claim 7, wherein: It further includes a laser protection plate and a laser window. The metal heating device includes a laser emitter and a laser controller. The laser window has a laser channel. The laser window is fixedly connected to the outer side wall of the operation unit. One end of the laser channel is communicated with the heating port. A transparent protection sheet is arranged in the laser channel. The laser controller is signal-connected to the laser emitter. The inner side wall of the operation unit where the heating port is arranged is the first side wall, and the inner side wall opposite to the first side wall is the second side wall. The laser protection plate is fixedly connected to the second side wall. The laser emitter is arranged outside the operation unit, and the laser emitter can emit laser to the preparation raw materials at the suspension station through the laser window under the control of the laser controller.

9. The containerless synthesis device for nano-metal materials according to claim 1, characterized in that: The operation unit includes a box body and operation gloves. Two glove openings are arranged on the side surface of the box body. The circumferential edges of the openings of the two operation gloves are respectively fixedly connected to the circumferential edges of the two glove openings. The space inside the box body forms the synthesis chamber, and both of the two operation gloves are located inside the synthesis chamber.

10. A method for containerless synthesis of a nano metal material, characterized in that: It includes the following steps: Set the preparation raw materials in the synthesis chamber, adjust the air pressure in the synthesis chamber to a preset air pressure value through the gas unit, adjust the gas flow mode in the synthesis chamber to a constant gas mode or a flowing gas mode through the gas unit, and adjust the temperature and humidity in the synthesis chamber to a preset temperature and a preset humidity through the temperature and humidity unit; turn on the acoustic suspension unit, move the preparation raw materials to the suspension station, suspend the preparation raw materials through the acoustic suspension unit, and after the preparation raw materials react at the suspension station for a preset time, obtain the droplets carrying nano-metal materials.

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