CN114918406A - Novel freezing casting device and method for preparing porous material - Google Patents
Novel freezing casting device and method for preparing porous material Download PDFInfo
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- CN114918406A CN114918406A CN202210439323.5A CN202210439323A CN114918406A CN 114918406 A CN114918406 A CN 114918406A CN 202210439323 A CN202210439323 A CN 202210439323A CN 114918406 A CN114918406 A CN 114918406A
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- 239000011148 porous material Substances 0.000 title claims abstract description 48
- 238000000034 method Methods 0.000 title claims abstract description 36
- 238000007710 freezing Methods 0.000 title claims abstract description 34
- 230000008014 freezing Effects 0.000 title claims abstract description 34
- 229910052802 copper Inorganic materials 0.000 claims abstract description 88
- 239000010949 copper Substances 0.000 claims abstract description 88
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 87
- 239000007788 liquid Substances 0.000 claims abstract description 85
- 238000001816 cooling Methods 0.000 claims abstract description 58
- 238000007711 solidification Methods 0.000 claims abstract description 27
- 230000008023 solidification Effects 0.000 claims abstract description 27
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 120
- 239000002002 slurry Substances 0.000 claims description 84
- 239000010410 layer Substances 0.000 claims description 74
- 229910052757 nitrogen Inorganic materials 0.000 claims description 60
- 238000002347 injection Methods 0.000 claims description 33
- 239000007924 injection Substances 0.000 claims description 33
- 230000006698 induction Effects 0.000 claims description 23
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 15
- 238000003860 storage Methods 0.000 claims description 10
- 238000002360 preparation method Methods 0.000 claims description 8
- 239000013078 crystal Substances 0.000 claims description 6
- 229910001220 stainless steel Inorganic materials 0.000 claims description 6
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Images
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D25/00—Special casting characterised by the nature of the product
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D15/00—Casting using a mould or core of which a part significant to the process is of high thermal conductivity, e.g. chill casting; Moulds or accessories specially adapted therefor
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
- B22D27/04—Influencing the temperature of the metal, e.g. by heating or cooling the mould
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
- B22D27/04—Influencing the temperature of the metal, e.g. by heating or cooling the mould
- B22D27/045—Directionally solidified castings
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
- B22D27/09—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting by using pressure
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D46/00—Controlling, supervising, not restricted to casting covered by a single main group, e.g. for safety reasons
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B1/00—Producing shaped prefabricated articles from the material
- B28B1/007—Producing shaped prefabricated articles from the material by freezing the material
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/25—Process efficiency
Abstract
The invention provides a novel freezing casting device and a novel freezing casting method for preparing a porous material, belongs to the field of freezing casting of porous materials, and particularly relates to a novel freezing casting device and a novel freezing casting method for preparing a porous material. The problem of be difficult to realize among the prior art freezing temperature, temperature gradient, solidification front speed, porous material shape and the accurate control of external force field is solved. It includes thick liquids mould, two copper caps, two double-deck cooling bar copper and temperature control system, the both sides of thick liquids mould all are provided with the copper cap, two copper cap symmetry settings, copper cap one end and ground paste mould clearance fit, the one end clearance fit of the other end and double-deck cooling bar copper, double-deck cooling bar copper includes inlayer cavity and outer cavity, the inlayer cavity sets up inside outer cavity. It is mainly used for freezing casting of porous materials.
Description
Technical Field
The invention belongs to the field of porous material freeze casting, and particularly relates to a novel freeze casting device and a novel freeze casting method for preparing a porous material.
Background
In recent years, there has been an increasing interest in creating biomimetic materials by looking for inspiration in natural organisms. Currently, many processing techniques, such as layer-by-layer deposition, gel casting, electrophoretic deposition, sacrificial template methods, additive manufacturing, etc., have been proposed to prepare biomimetic materials in various forms. Most of these techniques have the disadvantages of time consuming, complex processes, very high costs and limited dimensions, which results in their limitation in the production of actual material products. Freeze casting (also known as ice-templated) is a wet processing technique that uses a water-based (or other solvent) suspension (ceramic, metal or polymer) to achieve directional solidification, allowing the particles to self-assemble directly to form highly porous bulk materials. It can build a variety of microstructures and macrostructures such as isotropic porous structures, honeycomb structures, fishbone structures, layered interconnected structures, nacreous layers or layered structures and radially aligned structures as well as complex structures that are difficult to create by traditional processing routes. The technology has the advantages of flexible technology, economy, environmental protection and the like, and is widely applied to the preparation of various bionic porous materials such as ceramics, metals, polymers, biomacromolecules, carbon nano materials and the like, so that the bionic porous materials have new performance and the application range of the bionic porous materials is widened.
However, it is currently challenging to produce porous materials with a regular and controllable shape using freeze casting techniques. In the process of freezing and casting, the key means for preparing the porous material is to regulate and control the freezing temperature, the speed of the solidification front and the temperature gradient and apply an external force field. At present, devices for preparing porous materials by utilizing a freezing casting technology can be divided into two types: one-way freezing and two-way freezing. Etienne Munch, American researcher, at "architecture Control of Freeze-case Ceramics Through Additives and templates" ("Journal of the American Ceramics Society" 2009, No. 92P) 1534-1539 ) In the method, a one-way freezing casting device is adopted to prepare lamellar porous Al 2 O 3 The scaffold was found to have non-uniform lamella spacing, increasing from bottom to top, and random structural orientation. The solidification temperature is controlled through the heating sleeve heating copper rod and the liquid nitrogen cooling, the temperature gradient and the solidification speed are difficult to accurately control, the distance between the sheet layers and the thickness are difficult to control, and the performance of preparing the porous material of the sheet layers by utilizing the freeze casting technology at present is severely limited. In addition, the heating sleeve is used for heating, so that the slurry inside the die is difficult to be uniformly heated, and the performance of preparing the porous material is influenced. Sylvain Deville, American scientific research, at Ice-mapped pore alumina structures (Acta Materialia, 2007, No. 55P) 1965–1974 ) In the method, a bidirectional freezing casting device is utilized, and the solidification front speed and the temperature gradient are jointly adjusted through liquid nitrogen and a heating sleeve. In the solidification process, the initial temperature of the upper cooling end is higher than that of the lower cooling end, the cooling rate is kept consistent, and the two ends always keep the same temperature gradient. Prepared flaky Al 2 O 3 The longitudinal section of the ceramic skeleton shows a good lamellar bridging structure, but the structural orientation of the cross section is random, which may be caused by a small temperature gradient. Furthermore, the coagulation front speed is relatively low (< 100 μm/s), and the low coagulation front temperature makes it difficult to further reduce the lamella spacing. The invention patent' an ice template method based directional coagulation for preparing porous ceramicsThe solid device and the method (publication number CN105541369A) disclose a freeze casting device with one end heating and one end refrigerating, which realize the obvious speed increase (Tg > 500 μm/s) at the solidification front. However, the device heats the slurry by using the hydrothermal copper pipe, the process is slow, uniform heating of the slurry is difficult to realize, and the quality of the sample is finally affected. In addition, the lowest temperature achieved by the process using a cryogenic circulator can only reach-40 ℃, making freezing less efficient and further refinement of the lamella spacing difficult due to the temperature gradient limitations. Moreover, the temperature gradient in the process is difficult to control, so that the speed of the solidification front is difficult to control, and the performance of the porous material is influenced. The utility model discloses an "automatic quick freezing device based on ice template method" (publication number CN212619533U) improves on the basis of above-mentioned invention patent, utilizes liquid nitrogen to cool down, has reduced the cryogenic minimum temperature, has improved freezing efficiency and has also increased temperature gradient simultaneously. However, the method cannot accurately control the solidification front speed and the temperature gradient during cooling. Therefore, accurate control of the slice pitch and thickness is not achieved. The above studies all have a common disadvantage in that the porous material is prepared in a single shape.
Disclosure of Invention
In view of this, the present invention aims to provide a novel freeze casting apparatus and a novel freeze casting method for preparing a porous material, so as to solve the problem that precise control over a freezing temperature, a temperature gradient, a solidification front speed, a shape of the porous material and an external force field is difficult to achieve in the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme: a novel freezing and casting device for preparing porous materials comprises a slurry mould, two copper caps, two double-layer cooling copper rods and a temperature control system, copper caps are arranged on two sides of the slurry mold, the two copper caps are symmetrically arranged, one end of each copper cap is in clearance fit with the slurry mold, the other end of each copper cap is in clearance fit with one end of the double-layer cooling copper rod, the double-layer cooling copper rod comprises an inner-layer cavity and an outer-layer cavity, the inner-layer cavity is arranged inside the outer-layer cavity, the temperature control system comprises a temperature controller, two thermocouples, a solid-state relay, a power supply and an induction coil, the temperature controller, the two thermocouples, the solid-state relay, the power supply and the induction coil form a series loop, the temperature control system is closed-loop feedback control, the induction coil is arranged on the outer side of the slurry mold in a surrounding mode, and the two thermocouples are arranged at the connecting positions of the two ends of the slurry mold and the copper cap respectively.
Furthermore, one end of the top of the inner cavity is provided with a liquid nitrogen injection port, one end of the top of the outer cavity is provided with an absolute ethyl alcohol injection port, and the absolute ethyl alcohol injection port penetrates through the inner wall of the outer cavity.
Furthermore, a slurry filling opening is formed in the top of the slurry mold.
Furthermore, a liquid nitrogen control system is arranged at the liquid nitrogen injection port and comprises a liquid nitrogen storage chamber and an electromagnetic valve, the liquid nitrogen storage chamber is connected with the liquid nitrogen injection port, and the electromagnetic valve is arranged at the connection position of the liquid nitrogen storage chamber and the liquid nitrogen injection port.
Furthermore, the liquid nitrogen storage chamber is a liquid nitrogen storage tank which is made of double-layer stainless steel, and a middle interlayer of the double-layer stainless steel is vacuum.
Furthermore, a pressurizing system is arranged at the slurry filling opening and comprises a pressurizing pump, the pressurizing pump comprises a motor and a pump body, the pump body is connected with the motor, a water inlet and a water outlet are further formed in the pump body, and the water outlet is connected with the slurry filling opening.
Furthermore, a moving device is arranged at the bottom of the double-layer cooling copper rod, a guide rail is arranged below the moving device, and the moving device is in sliding fit with the guide rail.
Furthermore, the material of the slurry mould is polytetrafluoroethylene.
Further, the thermocouple has a measurement range of-200 ℃ to 600 ℃.
The invention also provides a casting method of the novel freezing casting device for preparing the porous material, which comprises the following steps:
the method comprises the following steps: the two double-layer cooling copper rods are respectively moved to required positions through a moving device and a guide rail to be fixed, after the positions of the double-layer cooling copper rods are fixed, the front ends of the double-layer cooling copper rods and copper caps are fixed in a clearance fit mode, different shapes can be designed and selected on the surfaces of the copper caps according to preparation requirements, then the front ends of the copper caps and a slurry mold are in clearance fit, and the periphery of the copper caps is sealed through rubber pads;
step two: injecting the slurry into the slurry mold through the slurry injection port, and continuously pressurizing the slurry in the slurry mold through a pressurizing system after the slurry is injected into the slurry mold, wherein the thermal conductivity of the slurry and the appearance of solidified crystal grains can be changed through the liquid pressurization;
step three: opening a temperature control system, and respectively inserting two thermocouples into the joints between the two ends of the slurry mold and the copper caps;
step four: injecting absolute ethyl alcohol into the outer layer cavity of the double-layer cooling copper rod through an absolute ethyl alcohol injection port and sealing, and introducing liquid nitrogen into the inner layer cavity of the double-layer cooling copper rod through a liquid nitrogen injection port for freezing casting, wherein the injection speed of the liquid nitrogen is controlled by a liquid nitrogen control system;
step five: the control of the freezing casting temperature and the cooling speed is realized by adjusting electromagnetic valves in a temperature control system and a liquid nitrogen control system in the casting process, wherein a temperature controller in the temperature control system can control the directional solidification speed of the left surface and the right surface of the slurry by controlling the cooling speed of the front ends of double-layer cooling copper rods on two sides, the temperature controller adopts closed-loop feedback control, the temperature of the left surface and the right surface of the slurry is measured in real time by a thermocouple, and meanwhile, the on-off of an induction coil is controlled by adjusting the on-off of a solid relay, the duty ratio is adjusted, and the power of the induction coil is controlled in real time to feed back and adjust the measured temperature so that the slurry works according to preset temperature rising and cooling programs.
Compared with the prior art, the invention has the beneficial effects that:
1. according to the invention, the double-layer cooling copper rod is arranged, the inner layer cavity is injected with liquid nitrogen, so that the circulating flow of the liquid nitrogen can be realized, the outer layer cavity is injected with absolute ethyl alcohol as a temperature buffer medium, so that the slurry can be uniformly cooled, and the rapid cooling and the low-temperature solidification at-114 ℃ can be realized;
2. the surface of the copper cap can have different shapes, the copper caps with different surface shapes can be designed and selected according to the preparation requirements for preparation, and the different shapes of the surface of the copper cap can be used as ice crystal nucleation points in the solidification process, so that porous materials with different shapes can be prepared, and the controllability of the shape of the porous material is realized;
3. according to the invention, the induction coil is utilized to heat the slurry in the slurry mold, so that the rapid and uniform heating of the slurry can be realized, and the heat loss is reduced, thereby achieving the purposes of energy conservation and emission reduction;
4. according to the invention, by arranging the liquid nitrogen control system, the pressurization system, the temperature control system, the double-layer cooling copper rod and the copper cap in the casting process, the fine regulation and control of the freezing temperature, the solidification front speed, the temperature gradient, the shape of the porous material and the external force field in the casting process are realized, so that the microstructure of the prepared porous material can be accurately controlled, and the material with required performance can be obtained;
5. the invention simultaneously realizes the fine control of the freezing temperature, the speed of the solidification front, the temperature gradient, the shape of the porous material and the external force field;
6. the invention has simple operation and realizes full automation when the freezing casting device works.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention, illustrate embodiments of the invention and together with the description serve to explain the invention and do not constitute a limitation of the invention. In the drawings:
FIG. 1 is a schematic diagram of the overall structure of a novel freeze casting device for preparing porous materials according to the present invention;
FIG. 2 is a schematic structural cross-sectional view of a double-layer cooling copper rod of the novel freeze casting device for preparing porous materials, which is disclosed by the invention;
FIG. 3 is a schematic structural diagram of copper caps with different shapes of the novel freeze casting device for preparing porous materials, which is disclosed by the invention;
FIG. 4 is a schematic sectional view of the structure of a slurry mold of the novel freeze casting device for preparing porous materials according to the present invention;
1-double-layer cooling copper rod, 2-absolute ethyl alcohol injection port, 3-liquid nitrogen injection port, 4-copper cap, 5-slurry injection port, 6-slurry mold, 7-induction coil, 8-temperature controller, 9-thermocouple, 10-moving device, 11-guide rail, 12-inner layer cavity and 13-outer layer cavity.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely explained below with reference to the drawings in the embodiments of the present invention. It should be noted that, in the present invention, the embodiments and features of the embodiments may be combined with each other without conflict, and the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments.
Referring to fig. 1-4 to illustrate the present embodiment, a novel freeze casting device for preparing a porous material includes a slurry mold 6, two copper caps 4, two double-layer cooling copper rods 1 and a temperature control system, wherein a slurry injection port 5 is formed at the top of the slurry mold 6, the copper caps 4 are respectively disposed at two sides of the slurry mold 6, the two copper caps 4 are symmetrically disposed, one end of each copper cap 4 is in clearance fit with the slurry mold 6, the other end of each copper cap is in clearance fit with one end of each double-layer cooling copper rod 1, each double-layer cooling copper rod 1 includes an inner layer cavity 12 and an outer layer cavity 13, the inner layer cavity 12 is disposed inside the outer layer cavity 13, a liquid nitrogen injection port 3 is formed at one end of the top of the inner layer cavity 12, an absolute ethyl alcohol injection port 2 is formed at one end of the top of the outer layer cavity 13, the absolute ethyl alcohol 2 penetrates through the inner wall of the outer layer cavity 13, the temperature control system includes a temperature controller 8, Two thermocouples 9, solid state relay, power and induction coil 7, temperature controller 8, two thermocouples 9, solid state relay, power and induction coil 7 constitute series circuit, temperature control system is closed loop feedback control, induction coil 7 is around setting up in the thick liquids mould 6 outside, two thermocouples 9 set up respectively in the junction of thick liquids mould 6 both ends and copper cap 4.
In the embodiment, the double-layer cooling copper rod 1 is arranged by adopting an inner layer cavity and an outer layer cavity, the inner layer cavity 12 is filled with liquid nitrogen through the liquid nitrogen filling opening 3, the liquid nitrogen can flow circularly, the outer layer cavity 13 is filled with absolute ethyl alcohol through the absolute ethyl alcohol filling opening 2 to serve as a temperature buffer medium, the slurry can be uniformly cooled, and not only can quick cooling be realized, but also low-temperature solidification at-114 ℃ can be realized.
In this embodiment, the surface of the copper cap 4 may be designed into different shapes, specifically, the copper cap 4 with different surface shapes may be designed and selected according to the preparation requirements for preparation, and the surface of the copper cap 4 may be designed into different shapes to serve as ice crystal nucleation points in the solidification process, so that porous materials with different shapes may be prepared, and controllability of the shape of the porous material may be achieved.
In this embodiment, the top of the slurry mold 6 is provided with a slurry injection port 5, which can be used for injecting slurry into the slurry mold 6, and in addition, slurry can be continuously injected in the solidification process to pressurize the slurry inside the slurry mold 6, and the thermal conductivity and the shape of the crystal grains can be controlled by controlling the pressure intensity.
In the temperature control system described in this embodiment, the temperature controller 8, the two thermocouples 9, the solid-state relay, the power supply and the induction coil 7 form a series loop, the temperature controller 8 can control the directional solidification speed of the left and right surfaces of the slurry by controlling the cooling rate of the front end of the double-layer cooling copper rod 1 on both sides, the temperature controller 8 adopts closed-loop feedback control, the thermocouples 9 measure the temperatures of the left and right surfaces of the slurry in real time, and simultaneously, the on-off of the solid-state relay is adjusted to control the on-off of the induction coil 7, adjust the duty ratio, and control the power of the induction coil 7 in real time to feed back and adjust the measured temperature, so that the temperature control system works according to the preset temperature increasing and cooling program.
In this embodiment, the thermocouples 9 are disposed at the left and right ends of the slurry mold 6 and used for detecting the temperature of the slurry solidification end in real time, and a thermocouple may also be disposed at a certain distance on the side of the slurry mold 6 to detect the solidification front temperature and obtain a temperature gradient, so as to regulate and control the solidification front temperature and the temperature gradient.
In this embodiment induction coil 7 arranges the outside in thick liquids mould 6 for thick liquids heat in the thick liquids mould 6, mix the liquid can directly carry out even regulation and control to the thick liquids temperature through induction heating to the metal thick liquids, and to ceramic thick liquids, can mix 2-3 wt.% metal particle in thick liquids inside and carry out induction heating, thereby not only can realize regulating and controlling the temperature of mixing thick liquids, but also can prepare the mixed porous ceramic material of metal, the introduction of this induction coil 7 can overcome traditional chill casting technique heating slowly and energy loss, realize carrying out rapid heating and thermal zero loss to thick liquids, thereby improved heating efficiency and reached energy saving and emission reduction's purpose.
In this embodiment 3 departments of liquid nitrogen filling opening are provided with liquid nitrogen control system, liquid nitrogen control system includes liquid nitrogen apotheca and solenoid valve, the liquid nitrogen apotheca links to each other with liquid nitrogen filling opening 3, the liquid nitrogen apotheca is equipped with the solenoid valve with 3 junctions of liquid nitrogen filling opening, the liquid nitrogen apotheca is low temperature liquid nitrogen holding vessel, the material of low temperature liquid nitrogen holding vessel is double-deck stainless steel, double-deck stainless steel intermediate layer is the vacuum, thereby liquid nitrogen control system passes through the injection velocity realization of solenoid valve control liquid nitrogen to freezing temperature's regulation and control.
In this embodiment 5 departments of thick liquids filling opening are provided with the pressurization system, the pressurization system includes the booster pump, the booster pump includes the motor and the pump body, the pump body links to each other with the motor, still be equipped with water inlet and delivery port on the pump body, the delivery port links to each other in thick liquids filling opening 5, and the pressurization system can be continuously realized pressurizeing the thick liquids of 6 inside thick liquids moulds to thick liquids mould 6 injection thick liquids in the solidification process through the booster pump, realizes the control to coefficient of heat conductivity and crystalline grain shape through the size of control pressure.
In this embodiment, a moving device 10 is arranged at the bottom of the double-layer cooling copper rod 1, a guide rail 11 is arranged below the moving device 10, the moving device 10 is in sliding fit with the guide rail 11, and the moving device 10 and the guide rail 11 jointly control the movement of the double-layer cooling copper rod 1.
In this embodiment, the material of the slurry mold 6 is teflon.
The thermocouple 9 in this embodiment measures a temperature in the range of-200 ℃ to 600 ℃.
The present embodiment also provides a casting method of a novel freeze casting apparatus for preparing a porous material, which includes the steps of:
the method comprises the following steps: the two double-layer cooling copper rods 1 are respectively moved to required positions to be fixed through a moving device 10 and a guide rail 11, after the positions of the double-layer cooling copper rods 1 are fixed, the front ends of the double-layer cooling copper rods 1 and copper caps 4 are fixed in a clearance fit mode, wherein the surfaces of the copper caps 4 can be designed and selected to be different in shape according to preparation requirements, then the front ends of the copper caps 4 are in clearance fit with a slurry mold 6, and the peripheries of the copper caps are sealed through rubber pads;
step two: injecting the slurry into the slurry mold 6 through the slurry injection port 5, and continuously pressurizing the slurry in the slurry mold 6 through a pressurization system after the slurry is injected, wherein the thermal conductivity of the slurry and the appearance of solidified crystal grains can be changed through liquid pressurization;
step three: opening a temperature control system, and respectively inserting two thermocouples 9 into the connection parts of the two ends of the slurry mould 6 and the copper caps 4;
step four: injecting absolute ethyl alcohol into an outer layer cavity 13 of the double-layer cooling copper rod 1 through an absolute ethyl alcohol injection port 2, sealing, and introducing liquid nitrogen into an inner layer cavity 12 of the double-layer cooling copper rod 1 through a liquid nitrogen injection port 3 for freezing casting, wherein the injection speed of the liquid nitrogen is controlled by a liquid nitrogen control system;
step five: the control of the freezing casting temperature and the cooling speed is realized by adjusting the electromagnetic valves in the temperature control system and the liquid nitrogen control system in the casting process, wherein the temperature controller 8 in the temperature control system can control the directional solidification speed of the left and right surfaces of the slurry by controlling the cooling speed of the front ends of the double-layer cooling copper rods 1 at the two sides, the temperature controller 8 adopts closed-loop feedback control, the temperature of the left and right surfaces of the slurry is measured in real time by a thermocouple 9, and meanwhile, the on-off of a solid-state relay is adjusted to control the on-off of an induction coil 7, adjust the duty ratio and control the power of the induction coil 7 in real time to feed back and adjust the measured temperature so that the slurry works according to preset temperature rising and cooling programs.
In the method of the embodiment, the control of the freezing and casting temperature and the cooling speed can be realized by adjusting the temperature control program of the temperature control system and the electromagnetic valve of the liquid nitrogen control system.
In the method of the embodiment, different cooling temperatures, cooling rates, pressurizing pressures and moving speeds of the solidification front can be selected according to the characteristics of the components of different slurries, and in addition, the shape of the surface of the copper cap 4 can be changed according to requirements, so that the porous material with an ideal shape is obtained, and the performance is optimal.
The embodiments of the invention disclosed above are intended merely to aid in the explanation of the invention. The examples are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention.
Claims (10)
1. A novel freezing casting device for preparing porous materials is characterized in that: the novel cooling device comprises a slurry mold (6), two copper caps (4), two double-layer cooling copper bars (1) and a temperature control system, wherein the copper caps (4) are arranged on two sides of the slurry mold (6), the two copper caps (4) are symmetrically arranged, one end of each copper cap (4) is in clearance fit with the slurry mold (6), the other end of each copper cap is in clearance fit with one end of each double-layer cooling copper bar (1), each double-layer cooling copper bar (1) comprises an inner-layer cavity (12) and an outer-layer cavity (13), the inner-layer cavity (12) is arranged inside the outer-layer cavity (13), the temperature control system comprises a temperature controller (8), two thermocouples (9), a solid-state relay, a power supply and an induction coil (7), the temperature controller (8), the two thermocouples (9), the solid-state relay, the power supply and the induction coil (7) form a series loop, and the temperature control system is closed-loop feedback control, the induction coil (7) is arranged on the outer side of the slurry mold (6) in a surrounding mode, and the two thermocouples (9) are respectively arranged at the connecting positions of the two ends of the slurry mold (6) and the copper cap (4).
2. The novel freeze casting apparatus for producing porous materials as claimed in claim 1, wherein: one end of the top of the inner cavity (12) is provided with a liquid nitrogen injection port (3), one end of the top of the outer cavity (13) is provided with an absolute ethyl alcohol injection port (2), and the absolute ethyl alcohol injection port (2) penetrates through the inner wall of the outer cavity (13).
3. The novel freeze casting apparatus for preparing a porous material according to claim 1, wherein: and a slurry filling opening (5) is formed in the top of the slurry mold (6).
4. The novel freeze casting apparatus for producing porous materials as claimed in claim 2, wherein: and a liquid nitrogen control system is arranged at the liquid nitrogen injection port (3), and comprises a liquid nitrogen storage chamber and an electromagnetic valve, wherein the liquid nitrogen storage chamber is connected with the liquid nitrogen injection port (3), and the electromagnetic valve is arranged at the joint of the liquid nitrogen storage chamber and the liquid nitrogen injection port (3).
5. The novel freeze casting apparatus for preparing a porous material according to claim 4, wherein: the liquid nitrogen storage chamber is a liquid nitrogen storage tank which is made of double-layer stainless steel, and the interlayer in the middle of the double-layer stainless steel is vacuum.
6. The novel freeze casting apparatus for preparing a porous material according to claim 3, wherein: the thick liquids filling opening (5) department is provided with the pressurization system, the pressurization system includes the booster pump, the booster pump includes the motor and the pump body, the pump body links to each other with the motor, still be equipped with water inlet and delivery port on the pump body, the delivery port links to each other in thick liquids filling opening (5).
7. The novel freeze casting apparatus for producing porous materials as claimed in claim 1, wherein: double-deck cooling bar copper (1) bottom is equipped with mobile device (10), mobile device (10) below is equipped with guide rail (11), mobile device (10) and guide rail (11) sliding fit.
8. The novel freeze casting apparatus for producing porous materials as claimed in claim 1, wherein: the slurry mould (6) is made of polytetrafluoroethylene.
9. The novel freeze casting apparatus for producing porous materials as claimed in claim 1, wherein: the measuring range of the thermocouple (9) is-200 ℃ to 600 ℃.
10. A casting method of a novel freeze casting apparatus for preparing a porous material according to claim 1, characterized in that: it comprises the following steps:
the method comprises the following steps: the two double-layer frozen copper rods are respectively moved to required positions to be fixed through a moving device (10) and a guide rail (11), after the positions of the double-layer frozen copper rods are fixed, the front ends of the double-layer frozen copper rods and copper caps (4) are fixed in a clearance fit mode, different shapes can be designed and selected on the surfaces of the copper caps (4) according to preparation requirements, then the front ends of the copper caps (4) are in clearance fit with a slurry mold (6), and the peripheries of the copper caps are sealed through rubber pads;
step two: injecting the slurry into the slurry mold (6) through the slurry injection port (5), and continuously pressurizing the slurry in the slurry mold (6) through a pressurizing system after the slurry is injected, wherein the thermal conductivity of the slurry and the morphology of solidified crystal grains can be changed through liquid pressurization;
step three: opening a temperature control system, and respectively inserting two thermocouples (9) into the connection positions of two ends of the slurry mold (6) and the copper cap (4);
step four: absolute ethyl alcohol is injected into an outer layer cavity (13) of the double-layer cooling copper rod (1) through an absolute ethyl alcohol injection port (2) and is sealed, liquid nitrogen is injected into an inner layer cavity (12) of the double-layer cooling copper rod (1) through a liquid nitrogen injection port (3) for freezing casting, wherein the injection speed of the liquid nitrogen is controlled by a liquid nitrogen control system;
step five: the control of the freezing casting temperature and the cooling speed is realized by adjusting electromagnetic valves in a temperature control system and a liquid nitrogen control system in the casting process, wherein a temperature controller (8) in the temperature control system can control the cooling speed of the front ends of double-layer cooling copper rods (1) at two sides to control the directional solidification speed of the left and right surfaces of the slurry, the temperature controller (8) adopts closed-loop feedback control, a thermocouple (9) measures the temperatures of the left and right surfaces of the slurry in real time, and simultaneously controls the on-off of an induction coil (7) by adjusting the on-off of a solid-state relay, adjusts the duty ratio, controls the power of the induction coil (7) in real time, feeds back and adjusts the measured temperature, so that the casting machine works according to preset temperature rising and cooling programs.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210439323.5A CN114918406B (en) | 2022-04-25 | Novel freezing casting device and casting method for preparing porous material |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210439323.5A CN114918406B (en) | 2022-04-25 | Novel freezing casting device and casting method for preparing porous material |
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| CN114918406A true CN114918406A (en) | 2022-08-19 |
| CN114918406B CN114918406B (en) | 2024-04-26 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116589299A (en) * | 2023-05-05 | 2023-08-15 | 哈尔滨工业大学 | Porous silicon carbide ceramic framework with bionic annual ring structure, preparation method thereof and application thereof in high-performance composite phase change material |
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| CN1153090A (en) * | 1995-12-25 | 1997-07-02 | 丁桂秋 | Ice mould casting method for metals |
| CN201825998U (en) * | 2010-07-30 | 2011-05-11 | 中国科学院金属研究所 | Device for adopting thermal resistance structure to assist water cooled crystallizer in unidirectional solidification |
| CN112553494A (en) * | 2020-11-13 | 2021-03-26 | 南京航空航天大学 | Refrigeration device and method for preparing high-strength and high-toughness layered porous titanium alloy material by using same |
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| CN1153090A (en) * | 1995-12-25 | 1997-07-02 | 丁桂秋 | Ice mould casting method for metals |
| CN201825998U (en) * | 2010-07-30 | 2011-05-11 | 中国科学院金属研究所 | Device for adopting thermal resistance structure to assist water cooled crystallizer in unidirectional solidification |
| CN112553494A (en) * | 2020-11-13 | 2021-03-26 | 南京航空航天大学 | Refrigeration device and method for preparing high-strength and high-toughness layered porous titanium alloy material by using same |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116589299A (en) * | 2023-05-05 | 2023-08-15 | 哈尔滨工业大学 | Porous silicon carbide ceramic framework with bionic annual ring structure, preparation method thereof and application thereof in high-performance composite phase change material |
| CN116589299B (en) * | 2023-05-05 | 2023-11-24 | 哈尔滨工业大学 | Porous silicon carbide ceramic framework with bionic annual ring structure, preparation method thereof and application thereof in high-performance composite phase change material |
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