An apparatus for preparing porous materials based on the ice template method

Abstract

This invention discloses an apparatus for preparing porous materials based on the ice template method, relating to the field of cryogenic casting technology for porous materials. It includes a slurry mold, a temperature-controlled substrate, a triaxial nested Helmholtz coil structure, and a controller. The slurry mold has several injection holes and is located within the triaxial nested Helmholtz coil structure. The slurry mold is mounted on the temperature-controlled substrate, which is equipped with thermocouples for detecting the temperature of the substrate. The temperature-controlled substrate also includes a heating tube and a liquid nitrogen channel. The heating tube is connected to an external power source, and the liquid nitrogen channel is used to introduce liquid nitrogen. The controller is electrically connected to the thermocouples, heating tube, and triaxial nested Helmholtz coil structure. This invention overcomes the problems of low heating and freezing efficiency, uneven heating of the slurry, and inability to simultaneously freeze multiple samples. By constructing a triaxial nested Helmholtz coil structure, a uniform magnetic field in any direction can be applied, achieving magnetically assisted cryogenic casting.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of porous material freeze casting, in particular to a device for preparing porous material based on ice template method. BACKGROUND

[0002] Biological materials in nature have attracted people's attention due to their excellent mechanical properties, and researchers have explored and designed excellent bionic materials inspired by them. Ice template method, also known as freeze casting, is a relatively novel method for preparing bionic materials, mainly used for the preparation of porous materials, and a second phase can be added to prepare more complex composite materials. The freezing temperature, solidification front speed, solute particle size, and temperature gradient, wettability gradient, and applied external force field such as magnetic field, electric field during the preparation process will affect the final material structure. Due to the advantages of controllable material structure, rapid preparation, simple preparation process, wide application, environmental friendliness, etc., the method has attracted more and more attention and has evolved into a fixed and mature processing route.

[0003] When preparing porous materials by ice template method, the material is first mixed with solute and other additives, stirred into a suspension, poured into a mold for cooling, then freeze-dried, and finally porous materials are prepared. The experimental equipment requirements are as simple as possible, and the freezing process is crucial, otherwise it will affect the subsequent material structure formation.

[0004] The invention patent "A directional solidification device and method for preparing porous ceramics based on ice template method" (publication number CN105541369A) discloses a freeze casting device with one end heating and one end refrigeration. The device uses a hydrothermal copper pipe to heat the slurry, which is a slow process and difficult to achieve uniform heating of the slurry, ultimately affecting the quality of the sample. In addition, the lowest temperature achieved by the low-temperature circulation machine in this process can only reach -40℃, resulting in low freezing efficiency, and due to the limitation of temperature gradient, it is difficult to further refine the lamellar spacing. SUMMARY

[0005] The purpose of the present application is to provide a device for preparing porous materials based on ice template method, which overcomes the problems of low heating and freezing efficiency, uneven heating of the slurry, and inability to freeze multiple samples at the same time. A three-axis nested Helmholtz coil structure is built, which can apply a uniform magnetic field in any direction and realize magnetic-assisted freeze casting.

[0006] To achieve the above purpose, the present application provides the following solutions:

[0007] The application provides a kind of including slurry mould, temperature control substrate, three-axis nested Helmholtz coil structure and controller, the slurry mould is provided with several grouting holes, the grouting hole is used to hold suspension, the slurry mould is located in the three-axis nested Helmholtz coil structure, the slurry mould is arranged on the temperature control substrate, the temperature control substrate is provided with thermocouple, the thermocouple is used to detect the temperature of the temperature control substrate, heating tube and liquid nitrogen channel are provided in the temperature control substrate, the heating tube is connected with external power supply, the liquid nitrogen channel is used to pass into liquid nitrogen, the controller is electrically connected with the thermocouple, the heating tube and the three-axis nested Helmholtz coil structure respectively.

[0008] Preferably, the temperature control substrate includes an upper substrate, a middle substrate and a lower substrate arranged from top to bottom, the upper substrate is provided with the thermocouple, the lower surface of the upper substrate forms a first S-shaped path with the upper surface of the middle substrate, the first S-shaped path is provided with the heating tube, the lower surface of the middle substrate forms a second S-shaped path with the upper surface of the lower substrate, and the second S-shaped path is the liquid nitrogen channel.

[0009] Preferably, the extension direction of the first S-shaped path is perpendicular to the extension direction of the second S-shaped path.

[0010] Preferably, the upper substrate and the middle substrate are made of red copper, and the lower substrate is made of polytetrafluoroethylene.

[0011] Preferably, the liquid inlet of the second S-shaped path communicates with a liquid nitrogen tank through a first low-temperature conduit, an electromagnetic valve is arranged between the liquid inlet and the first low-temperature conduit, the electromagnetic valve is electrically connected with the controller, and the liquid outlet of the second S-shaped path communicates with a recovery tank through a second low-temperature conduit.

[0012] Preferably, it further includes a liquid nitrogen pressure gun, the upper end of the liquid nitrogen pressure gun is connected with an electric pump, the lower end of the liquid nitrogen pressure gun extends into the liquid nitrogen tank, the first low-temperature conduit communicates with a valve on the left side of the liquid nitrogen pressure gun, and a safety valve is arranged on the right side of the liquid nitrogen pressure gun.

[0013] Preferably, the three-axis nested Helmholtz coil structure includes a coil base, a first coil, a second coil and a third coil, the first coil, the second coil and the third coil are all Helmholtz coils, the first coil is arranged on the coil base, the second coil is nested in the first coil, and the third coil is nested in the second coil, the first coil is orthogonally arranged with the second coil and the third coil, and the second coil and the third coil are orthogonally arranged.

[0014] Preferably, a spacer is arranged between the slurry mould and the temperature control substrate.

[0015] Preferably, a heat shield is further included, which is covered outside the three-axis nested Helmholtz coil structure.

[0016] The present application has the following technical effects relative to the prior art:

[0017] 1. The present application uses liquid nitrogen cooling, greatly reduces the minimum freezing temperature, and improves the freezing efficiency;

[0018] 2. The present application uses a heating pipe to heat the slurry, which has a fast heating rate;

[0019] 3. The slurry mold of the present application has multiple slurry injection holes, which can realize the simultaneous freezing of multiple materials, save multiple sample material freezing time, and improve the freezing efficiency;

[0020] 4. The present application adds a three-axis nested Helmholtz coil structure, which can apply a uniform magnetic field in any direction, and the magnetic field size can be freely controlled, realizing magnetic freezing casting. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0022] Figure 1 It is a whole schematic view of the device for preparing porous materials based on ice template method of the present application;

[0023] Figure 2 It is a schematic view of the three-axis nested Helmholtz coil structure of the present application;

[0024] Figure 3 It is a schematic view of the temperature control base plate of the present application;

[0025] Figure 4 It is an explosion of the temperature control base plate of the present application Figure 1 ;

[0026] Figure 5 It is an explosion of the temperature control base plate of the present application Figure 2 ;

[0027] Figure 6 It is a schematic view of the slurry mold of the present application;

[0028] Wherein: 100-Apparatus for preparing porous materials based on ice template method, 1-Triaxial nested Helmholtz coil structure, 2-Thermocouple, 3-Heating tube, 4-Solenoid valve, 5-Controller, 6-Liquid nitrogen press gun, 7-Liquid nitrogen tank, 8-Electric pump, 9-Slurry mold, 10-Separator, 11-Upper substrate, 12-Liquid outlet, 13-Middle substrate, 14-Lower substrate, 15-Insulated base, 16-Second cryogenic conduit, 17-Recovery tank, 18-Liquid inlet, 19-First cryogenic conduit, 20-Insulated cover, 21-First coil, 22-Second coil, 23-Third coil, 24-Coil base, 25-Slurry injection hole. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] The purpose of this invention is to provide a device for preparing porous materials based on the ice template method, which overcomes the problems of low heating and freezing efficiency, inability to uniformly heat the slurry, and inability to freeze multiple samples simultaneously. It constructs a triaxial nested Helmholtz coil structure, which can apply a uniform magnetic field in any direction to achieve magnetically assisted cryogenic casting.

[0031] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] like Figures 1 to 6 As shown: This embodiment provides an apparatus 100 for preparing porous materials based on the ice template method, including a slurry mold 9, a temperature control substrate, a triaxial nested Helmholtz coil structure 1, and a controller 5. The slurry mold 9 is provided with several cylindrical injection holes 25, which are used to hold suspensions, enabling simultaneous freezing of multiple samples, saving preparation time and improving freezing efficiency. The slurry mold 9 is located in the triaxial nested Helmholtz coil structure 1 and is set on the temperature control substrate. The temperature control substrate is provided with a heating tube 3 and a liquid nitrogen channel. The heating tube 3 is connected to an external power supply and can be a 400W heating tube. The liquid nitrogen channel is used to introduce liquid nitrogen. The controller 5 is an integrated controller 5, which is electrically connected to the heating tube 3 and the triaxial nested Helmholtz coil structure 1.

[0033] Specifically, in this embodiment, the suspension can be a suspension of ceramics, metals, polymers, etc. formed in water or other solvents. Taking alumina ceramics as an example, the volume fraction of alumina ceramics in water is 5%-30%vol, and 1%wt of dispersant is added to the suspension.

[0034] In this embodiment, the temperature control substrate includes an upper substrate 11, a middle substrate 13 and a lower substrate 14 arranged from top to bottom, and the upper substrate 11 and the middle substrate 13 and the middle substrate 13 and the lower substrate 14 are connected by bolts respectively; the upper substrate 11 and the middle substrate 13 are made of red copper, which has fast heat conduction, realizes uniform heating of the slurry, and realizes sensitive regulation and control of the temperature of the temperature control substrate; the lower substrate 14 is made of polytetrafluoroethylene, which has poor thermal conductivity and reduces heat loss; the upper substrate 11 is provided with a thermocouple 2, one end of the thermocouple 2 extends into the upper substrate 11, and the other end of the thermocouple 2 is electrically connected with the controller 5, which monitors the temperature of the temperature control substrate in real time and feeds back to the controller 5; a spacer 10 is arranged between the slurry mold 9 and the upper surface of the upper substrate 11 to prevent the sample from adhering to the upper substrate 11 and causing damage to the sample structure, making it easy to demold the material and protecting the material structure from being damaged; the lower surface of the upper substrate 11 and the upper surface of the middle substrate 13 are respectively milled to form a first S-shaped path, and the first S-shaped path is provided with an S-shaped heating pipe 3, which realizes rapid heating of the temperature control substrate and ensures uniform heating of the slurry; the lower surface of the middle substrate 13 and the upper surface of the lower substrate 14 are respectively milled to form a second S-shaped path, the extension direction of the first S-shaped path is perpendicular to the extension direction of the second S-shaped path, and the second S-shaped path is a liquid nitrogen channel, which realizes rapid cooling of the temperature control substrate.

[0035] In this embodiment, the liquid inlet 18 of the second S-shaped path is communicated with the liquid nitrogen tank 7 through the first low-temperature conduit 19, and the electromagnetic valve 4 is arranged between the liquid inlet 18 and the first low-temperature conduit 19, the electromagnetic valve 4 is preferably a low-temperature electromagnetic valve, the electromagnetic valve 4 is electrically connected with the controller 5, and the liquid outlet 12 of the second S-shaped path is communicated with the recovery tank 17 through the second low-temperature conduit 16. In this example, the settings of the controller 5 and the electromagnetic valve 4 can be adjusted to control the temperature and cooling speed of the temperature control substrate.

[0036] In this embodiment, the outer side of the first low-temperature conduit 19 and the outer side of the second low-temperature conduit 16 are wrapped with a heat insulation layer to reduce the vaporization of liquid nitrogen during transmission.

[0037] The embodiment also comprises a liquid nitrogen pressure gun 6, the upper end of the liquid nitrogen pressure gun 6 is connected with the electric pump 8, the lower end of the liquid nitrogen pressure gun 6 extends into the liquid nitrogen tank 7, the first low-temperature conduit 19 is communicated with the valve on the left side of the liquid nitrogen pressure gun 6, and the right side of the liquid nitrogen pressure gun 6 is provided with a safety valve which is opened to release gas to prevent the pressure in the liquid nitrogen tank 7 from being too large. When the electromagnetic valve 4 is opened, the nitrogen gas is pressurized by the electric pump 8 and discharged from the liquid nitrogen tank 7, sequentially passes through the liquid nitrogen pressure gun 6, the first low-temperature conduit 19, the electromagnetic valve 4, the liquid inlet 18, and then enters the second S-shaped path, is discharged from the liquid outlet 12 and enters the recovery tank 17, realizes the cooling of the temperature-controlled substrate, and recovers the liquid nitrogen to save experimental consumables.

[0038] In the embodiment, the side surface of the temperature-controlled substrate is wrapped with heat insulation cotton, and the material of the heat insulation cotton is aluminum silicate ceramic fiber, so as to reduce heat dissipation in the cooling process.

[0039] In the embodiment, the three-axis nested Helmholtz coil structure 1 comprises a coil base 24, a first coil 21, a second coil 22 and a third coil 23, and a heat insulation base 15 is arranged between the lower substrate 14 and the coil base 24 to reduce heat loss of the temperature-controlled substrate in the freezing process. The first coil 21, the second coil 22 and the third coil 23 are all Helmholtz coils, that is, the first coil 21, the second coil 22 and the third coil 23 are all composed of a pair of coaxial coils which are parallel to each other and communicated. The radii and the number of turns of the two coils are the same, the current directions in the two coils are consistent and the same, such a coil can generate a wide and uniform magnetic field near the midpoint of the common axis, and the current and the magnetic field have a good linear relationship. The first coil 21 is arranged on the coil base 24, the second coil 22 is nested in the first coil 21, and the third coil 23 is nested in the second coil 22. The first coil 21 is orthogonally arranged with the second coil 22 and the third coil 23, and the second coil 22 and the third coil 23 are orthogonally arranged. The third coil 23 generates a magnetic field in the Y direction, the second coil 22 generates a magnetic field in the X direction, and the first coil 21 generates a magnetic field in the Z direction. By controlling the current of the first coil 21, the second coil 22 and the third coil 23 through the controller 5, a uniform magnetic field can be generated in any direction, the microstructure of the magnetic particles can be controlled, magnetic-assisted freeze casting can be realized, and thus a porous material with more excellent performance can be obtained.

[0040] The embodiment comprises a heat insulation cover 20 which covers the outside of the three-axis nested Helmholtz coil structure 1 to reduce the contact with air and reduce heat dissipation in the freezing process.

[0041] In this example, thermocouple 2, heating tube 3, solenoid valve 4, and triaxial nested Helmholtz coil structure 1 are all connected to controller 5. Thermocouple 2 constantly monitors the temperature of the temperature control substrate and feeds it back to controller 5. Controller 5 controls heating tube 3 to rapidly increase the temperature of the temperature control substrate, controller 5 controls solenoid valve 4 to adjust the output of liquid nitrogen to achieve rapid cooling, and controller 5 controls triaxial nested Helmholtz coil structure 1 to supply power to the first coil 21, second coil 22, and third coil 23 to achieve free control of the magnetic field. Based on the real-time feedback from thermocouple 2, controller 5 uses PID automatic control of heating tube 3 and solenoid valve 4 to control the temperature and cooling rate during the freezing process, eliminating the need for manual temperature control. After cooling using the apparatus 100 for preparing porous materials based on the ice template method in this embodiment, other devices are used for freeze-drying.

[0042] This embodiment overcomes the shortcomings of existing technologies, such as low freezing efficiency, uneven heating of the slurry, and inability to freeze multiple samples simultaneously. This embodiment constructs a triaxial nested Helmholtz coil structure 1, which can apply a uniform magnetic field in any direction to achieve magnetically assisted cryogenic casting. The temperature of the temperature-controlled substrate is controlled by thermocouples 2, heating tubes 3, liquid nitrogen cooling, and a controller 5, enabling automatic and precise temperature control, rapid response, and high robustness for material freezing. Using heating tubes 3 and liquid nitrogen cooling allows for faster adjustment of the temperature-controlled substrate temperature, ensuring uniform heating of the material during freezing and generating porous materials with more ideal structures. The controller 5 controls the current magnitude of the triaxial nested Helmholtz coil structure 1, forming a uniform magnetic field in any direction, enabling the manipulation of the microstructure of magnetic particles.

[0043] This specification uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. An apparatus for preparing a porous material based on an ice templating method, characterized by: The device comprises a slurry mold, a temperature control substrate, a three-axis nested Helmholtz coil structure and a controller, the slurry mold is provided with a plurality of grouting holes for containing suspension, the slurry mold is located in the three-axis nested Helmholtz coil structure, the slurry mold is arranged on the temperature control substrate, the temperature control substrate is provided with a thermocouple for detecting the temperature of the temperature control substrate, the temperature control substrate is provided with a heating tube and a liquid nitrogen channel, the heating tube is connected with an external power supply, the liquid nitrogen channel is used for introducing liquid nitrogen, and the controller is electrically connected with the thermocouple, the heating tube and the three-axis nested Helmholtz coil structure respectively; The three-axis nested Helmholtz coil structure comprises a coil base, a first coil, a second coil and a third coil, the first coil, the second coil and the third coil are all Helmholtz coils, the first coil is arranged on the coil base, the second coil is nested in the first coil, the third coil is nested in the second coil, and the first coil is orthogonally arranged with the second coil and the third coil, and the second coil and the third coil are orthogonally arranged; The temperature control substrate comprises an upper substrate, a middle substrate and a lower substrate arranged from top to bottom, the upper substrate is provided with the thermocouple, a lower surface of the upper substrate and an upper surface of the middle substrate form a first S-shaped path, the first S-shaped path is provided with the heating tube, a lower surface of the middle substrate and an upper surface of the lower substrate form a second S-shaped path, the second S-shaped path is the liquid nitrogen channel, the upper substrate and the middle substrate are made of red copper, and the lower substrate is made of polytetrafluoroethylene.

2. The apparatus for preparing a porous material based on an ice template method according to claim 1, wherein: The extension direction of the first S-shaped path is perpendicular to the extension direction of the second S-shaped path.

3. The apparatus for preparing porous materials based on ice templating according to claim 1, wherein: The liquid inlet of the second S-shaped path is communicated with a liquid nitrogen tank through a first low-temperature conduit, an electromagnetic valve is arranged between the liquid inlet and the first low-temperature conduit, the electromagnetic valve is electrically connected with the controller, and the liquid outlet of the second S-shaped path is communicated with a recovery tank through a second low-temperature conduit.

4. The apparatus for preparing porous materials based on ice templating according to claim 3, wherein: Further comprising a liquid nitrogen pressure gun, the upper end of the liquid nitrogen pressure gun is connected with an electric pump, the lower end of the liquid nitrogen pressure gun extends into the liquid nitrogen tank, the first low-temperature conduit is communicated with a valve on the left side of the liquid nitrogen pressure gun, and a safety valve is arranged on the right side of the liquid nitrogen pressure gun.

5. The apparatus for preparing porous materials based on ice templating according to claim 1, wherein: A partition is arranged between the slurry mold and the temperature control substrate.

6. The apparatus for preparing porous materials based on ice templating according to claim 1, wherein: Further comprising a heat shield, the heat shield is arranged outside the three-axis nested Helmholtz coil structure.

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