CN112408949B - Device and method for preparing alumina microfiber by using microfluidic chip and application - Google Patents
Device and method for preparing alumina microfiber by using microfluidic chip and application Download PDFInfo
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Abstract
The invention relates to a device and a method for preparing alumina microfibers by utilizing a microfluidic chip and application. The device for preparing the alumina microfiber by using the microfluidic chip comprises a microfluidic channel and a metal microtube, wherein the microfluidic channel is divided into a feeding area, a mixing area and a heating area along the flowing direction of slurry, the mixing area is positioned between the feeding area and the heating area, the feeding area is connected with the metal microtube, and one end of the metal microtube is inserted into the microfluidic channel. The prepared ceramic microfiber green body has the characteristics of uniform and controllable size, round and round section, good flexibility, smooth surface and high operability, so that the ceramic microfiber green body can be better applied to the fields of aviation, catalyst carriers, biology, buildings and the like.
Description
Technical Field
The invention belongs to the technical field of ceramic microfiber preparation, and particularly relates to a device and a method for preparing aluminum oxide microfibers by using a microfluidic chip, and application of the device and the method.
Background
The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.
The ceramic material has better high temperature resistance, wear resistance and chemical corrosion resistance, and excellent mechanical property, so that the ceramic material becomes a substitute of various metals or alloys in the industrial field. The ceramic microfiber not only has the general properties of ceramic materials, but also conforms to the development trend of the structural materials for adjusting the miniaturization and the precision of the habitat. With the development of ceramic microfibers in applications such as toughening, sound absorption, adsorption, bone tissue culture, fuel cells, micro-electromechanical system micro-components and the like, the ceramic microfibers show unprecedented development prospects in the fields of aviation, catalyst carriers, biology, buildings and the like. The traditional methods for preparing ceramic microfibers include centrifugal spinning by a sol-gel method, electrostatic spinning, extrusion molding and the like, and the alumina ceramic microfibers can be obtained by calcining alumina nascent fibers prepared by sol-gel electrostatic spinning at high temperature according to records in the prior art. Meanwhile, in the prior art, after ceramic slurry mixed with ceramic powder, a polymer microsphere pore-forming agent and aluminum phosphate sol is printed by an ink direct writing 3D printer, drying, curing and sintering are carried out, so that a microstructure formed by stacking porous ceramic microfibers is obtained. These methods produce ceramic microfiber green bodies that lack flexibility, are less workable, and, in the case of larger sizes, are more difficult to control the size of the microfibers.
Microfluid is a cross discipline developed on the basis of microelectronics, microfabrication, bioengineering, nanotechnology, etc., and micro-channels in a microfluid device are utilized to manipulate, process and control trace liquids or samples on a micro-scale. In the prior art, a method for preparing porous silica microfibers with controllable size and structure in a coaxial glass capillary by utilizing multiphase flow is described, the microfibers have flexibility and strong operability under the condition of water, and can be braided and sintered at high temperature to form a specific shape. However, the ceramic microfiber materials that can be prepared by using a microfluid method are limited, and at present, the method of performing photocuring molding on a microfluidic column formed by a silicon oxide transparent precursor in a channel is mainly used, which limits the further development of the ceramic microfiber preparation technology.
Disclosure of Invention
In view of the problems in the prior art, the present invention provides an apparatus and a method for preparing alumina microfiber using microfluidic chip, and applications thereof.
In order to solve the technical problems, the technical scheme of the invention is as follows:
in a first aspect, an apparatus for preparing an alumina microfiber using a microfluidic chip comprises a microfluidic channel and a metal microtube, wherein the microfluidic channel is divided into a feeding region, a mixing region and a heating region along a flow direction of slurry, the mixing region is located between the feeding region and the heating region, the feeding region is connected with the metal microtube, and one end of the metal microtube is inserted into the microfluidic channel.
The microfluid device for preparing the alumina microfiber is provided, ceramic slurry is mixed and thermally cured and formed in a microfluid channel by utilizing the microfluid channel, and the alumina microfiber is obtained at the outlet of the microfluid channel.
The preparation technology of the ceramic microfiber is further developed, and compared with the existing technology which only can prepare the silicon oxide microfiber, the preparation method of the alumina ceramic microfiber is realized.
Ceramic microfiber green bodies prepared by relying on a microfluid technology are mainly formed by photocuring at present, photocuring has high requirements on the transparency of precursors, and few materials capable of realizing high-concentration nanoparticle dispersion and maintaining the high transparency of the precursors are available at present.
The invention provides a method for preparing a ceramic microfiber green compact by adopting instant heat curing, which is used for microfluid forming of a ceramic slurry precursor with low transparency, and in addition, the invention also provides a method for shunting and mixing the ceramic slurry precursor on line in consideration of the blockage problem in the heat curing forming process. After the micro fiber green compact is generated, the micro fiber green compact has high flexibility in water, the micro fiber can be bent and woven by utilizing the flexibility to form a certain structure, and then the micro fiber is sintered after drying and shaping.
The solidified phase fluid and the base phase fluid are vertically intersected, and the microfiber obtained after the ceramic slurry is subjected to thermosetting molding in the microfluidic channel has a smooth surface and uniform size.
In some embodiments of the present invention, a plurality of stirring rods are disposed inside the mixing region, two ends of each stirring rod are respectively connected to the inner wall of the microfluidic channel, and two adjacent stirring rods are spatially perpendicular. Preferably, the stirring rods are divided into a horizontally arranged stirring rod and a vertically arranged stirring rod.
In some embodiments of the invention, the end of the feed zone remote from the mixing zone is connected to an inlet pipe.
In some embodiments of the invention, the heating device is disposed outside the heating zone of the microfluidic channel.
In a second aspect, a method for preparing an alumina microfiber by using an alumina microfiber preparation apparatus of a microfluidic chip comprises the steps of:
introducing a base phase fluid into the microfluidic channel through an inlet pipe, introducing a solidification phase through a metal micro-tube when the base phase fluid flows out of an outlet of the microfluidic channel, and obtaining a fiber green compact at the outlet of the microfluidic channel;
and introducing the fiber green compact into a cleaning solution, placing the fiber into an aging solution for standing and curing after cleaning, drying the cured fiber to obtain a ceramic microfiber green compact, and sintering the ceramic microfiber green compact to obtain the alumina ceramic microfiber.
The solidified phase fluid and the base phase fluid meet vertically, the microfibers are vertically introduced into deionized water, and the uncured base phase is dissolved in water due to the oxygen barrier layer on the surface of the microfibers, which is done in such a way that the microfiber surface is smooth and prevents bonding between microfibers during drying.
In some embodiments of the present invention, the base phase fluid is a mixed solution of alumina nano-dispersion and prepolymer, the content of alumina nano-particles in the base phase fluid is 70-75 wt.%, and the content of prepolymer is 8-10 wt.%.
Further, the content of alumina nanoparticles in the base phase fluid was 72.7 wt.%, and the content of the prepolymer was 8.7 wt.%.
Further, the prepolymer is prepared from the following raw materials in parts by weight: 85-86 parts of acrylamide and 14-15 parts of N, N' -methylene bisacrylamide.
Further, the preparation method of the alumina dispersion liquid comprises the steps of mixing alumina powder, ammonium citrate and deionized water, and performing ball milling to obtain the alumina dispersion liquid; further, the alumina powder has an average particle diameter of 0.8 to 1.2 μm; the volume ratio of the deionized water to the alumina powder is 1-1.2:1, and further, the mass of the ammonium citrate accounts for 0.6-1% of that of the alumina powder.
In some embodiments of the invention, the solidification phase fluid is a mixed solution of ammonium persulfate, tetramethylethylenediamine, and water, the content of the solidification phase initiator is 9 to 10 wt.%, and the content of the catalyst is 2 to 3 wt.%.
Further, the content of the curing phase initiator was 9.5 wt.%, and the content of the catalyst was 2.3 wt.%. Ammonium persulfate is an initiator of the ceramic slurry, and tetramethylethylenediamine is a catalyst.
In some embodiments of the invention, the flow rate ratio of the base phase fluid and the solidified phase fluid is 4-6:1, and the total flow rate is 11-13 μ L/min.
In some embodiments of the invention, the heating zone of the microfluidic channel is set at a temperature of 45 ℃ to 70 ℃; preferably 50-60 deg.C. The surface appearance of the obtained ceramic microfiber is uniform, smooth and clean, and the size of the obtained ceramic microfiber is uniform in the temperature range.
The separation of the ceramic slurry base phase and the solidified phase, and the on-line heating and solidification for forming the microfiber green body are more critical operation methods. Most of the traditional methods for preparing ceramic microfibers at present are based on sol-gel mixed single-phase spinning or extrusion molding, and the green microfibers are poor in flexibility and low in operability; the ceramic microfiber green compact prepared based on oil-water two phases used by microfluid is cured by ultraviolet light, the oil phase only plays a role in coating a water phase liquid column, and photocuring is not suitable for opaque ceramic slurry systems such as alumina; the invention mixes the catalyst and initiator in the alumina ceramic slurry system into the second phase different from the base phase, and mixes and reacts with the slurry base phase in the channel, and heats to form a microfiber green compact. The obtained microfiber green compact has good flexibility and operability.
In some embodiments of the invention, the cleaning solution for the fiber green body is an aqueous ammonium persulfate solution, and the mass fraction of the ammonium persulfate is 2-4%; preferably 3%.
In some embodiments of the invention, the aging solution is a 2-3% mass fraction aqueous ammonium persulfate solution; preferably 3%.
In some embodiments of the invention, the aging time is greater than or equal to 1 hour and the aging temperature is greater than or equal to 65 ℃, preferably from 1 to 1.5 hours, 65 to 75 ℃. And further crosslinking the prepolymer which is not completely crosslinked in the microfiber green body, and completely curing the prepolymer.
In some embodiments of the invention, the green microfiber mass is collected after aging and placed on a teflon film and dried at ambient temperature for 10 to 14 hours.
In some embodiments of the invention, the process of sintering is: respectively preserving heat at the temperature of 110-. The sintering adopts a step heating mode to burn off organic matters such as polyacrylamide and the like, and then the heating is carried out to bond the alumina nano particles to form an alumina ceramic structure.
One or more technical schemes of the invention have the following beneficial effects:
(1) the ceramic microfiber green body prepared based on the microfluidic chip reactor has the characteristics of uniform and controllable size, round and round section, good flexibility, smooth surface and high operability, and thus can be better applied to the fields of aviation, catalyst carriers, biology, buildings and the like.
(2) The invention solves the technical problem of preparing the ceramic microfiber with the opaque precursor ceramic slurry in a microfluid mode by utilizing the preparation process of online mixing and thermal polymerization molding of the base phase and the curing phase, so that the preparation material of the ceramic microfiber is more diversified.
(3) The invention separates the initiator and the catalyst from the traditional ceramic slurry system to be mixed to form a curing phase, and the curing phase is mixed with other components of the slurry system on line to form a ceramic microfiber green compact, thereby overcoming the defects of unstable microfiber production, uneven production size, channel blockage and the like after the slurry system is directly introduced into a microchannel.
(4) The invention can simply and easily control and prepare the microfiber green compact with certain diameter and surface smoothness by adjusting the total flow rate and the curing temperature of the base phase and the curing phase. The formula has a guiding effect on the application of the ceramic microfiber in the fields of aviation, navigation, catalyst carriers, biology, buildings and the like.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the invention and not to limit the invention.
FIG. 1 is a schematic diagram of the structure of an apparatus for producing a green alumina microfiber according to example 1 of the present invention.
FIG. 2 is an optical microscope photograph of example 4 of the present invention in an aqueous solution to prepare a green alumina fiber.
FIG. 3 is a three-dimensional scanning optical microscope image of the cross section of a ceramic microfiber obtained by drying and sintering the green microfiber prepared in example 4 of the present invention and an electron microscope image of the side morphology of the microfiber at different magnifications.
Fig. 4 is an optical microscope photograph of the microfiber green compact prepared in example 4 of the present invention, which is bent and cross-woven into a chinese knot.
Wherein the symbols represent: 1-inlet pipe, 2-microfluidic channel, 3-metal microtube, 4-first metal stirring micro-rod, 5-second metal stirring micro-rod, 6-third metal stirring micro-rod, 7-fourth metal stirring micro-rod and 8-copper ring.
Detailed Description
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
As shown in fig. 1, the apparatus for preparing alumina microfibers using a microfluidic chip comprises a microfluidic channel 2 and a metal microtube 3, wherein the microfluidic channel 2 is divided into a feeding region, a mixing region and a heating region along the flow direction of a slurry, the mixing region is located between the feeding region and the heating region, the feeding region is connected with the metal microtube 3, and one end of the metal microtube 3 is inserted into the microfluidic channel 2.
The microfluid channel is used as a reaction channel, so that the obtained fiber has the advantages of smooth surface, good flexibility, round section and uniform size.
The micro-fluid channel is divided into a feeding zone, a mixing zone and a heating zone according to the flowing direction, so that the uniform mixing of the base phase fluid and the solidified phase fluid is realized, the alumina nano-particles and the polymer in the cross section of the colloidal microfiber flowing out of the micro-fluid channel are respectively in a uniform distribution state, and the polymer is distributed among the alumina nano-particles in a net shape.
Set up a plurality of stirring rods in the inside of mixing area, two adjacent stirring rod spaces are perpendicular, and a plurality of stirring rods divide into the stirring rod of level setting and the stirring rod of vertical setting. The two ends of the stirring rod are respectively connected with the inner wall of the microfluid channel, so that the fluid inevitably passes through the stirring rod to play a role in stirring.
The end of the feeding zone remote from the mixing zone is connected to an inlet pipe. The inlet pipe is an inlet pipeline of the base phase fluid, and the inlet pipe is in interference fit with the microfluidic channel.
The microfluidic channels are cast from wires of different diameters to give microfluidic channels of different dimensions. The cross-section of the microfluidic channel is circular.
The heating device is arranged outside the heating zone of the microfluidic channel. As shown in figure 1, the outer surface of the heating area can be coated with a copper ring, the copper ring can be fixed on the heating plate in an adhesive mode, and the bottom surface of the copper ring is kept to be firmly attached to the heating plate, so that the heating purpose is realized.
The invention will be further illustrated by the following examples
Example 1
The device for preparing the ceramic microfiber based on the microreactor comprises a microfluidic channel 2 and a metal micro-tube 3, wherein the microfluidic channel 2 is divided into a feeding region, a mixing region and a heating region along the flowing direction of slurry, the mixing region is positioned between the feeding region and the heating region, the feeding region is connected with the metal micro-tube 3, and one end of the metal micro-tube 3 is inserted into the microfluidic channel 2. The end of the feeding zone remote from the mixing zone is connected to an inlet pipe. A copper ring is arranged outside the heating zone of the microfluidic channel. Four metal rods are arranged in the mixing area, namely a first metal stirring rod 4, a second metal stirring rod 5, a third metal stirring rod 6 and a fourth metal stirring rod 7.
The diameter of the microfluidic channel is 0.64mm, the inner diameter of the inlet pipe 1 is 0.43mm, the outer diameter of the inlet pipe is 0.76mm, the inner diameter of the metal micro-pipe 3 is 0.11mm, the outer diameter of the metal micro-pipe is 0.23mm, the first metal stirring rod 4, the second metal stirring rod 5, the third metal stirring rod 6 and the fourth metal stirring rod 7 are all 0.23mm, the thickness of the copper ring 8 is 0.15mm, the width of the heating area in the flowing direction is 5mm, the non-copper ring contact area of the microfluidic channel 2 is arranged in the air, and the copper ring 8 area is arranged above the heater.
Example 2
Preparing an alumina nano dispersion liquid: weighing 19.5g of alumina powder, 0.195g of ammonium citrate and 5g of deionized water, mixing, and ball-milling for 24 hours at 450 revolutions per minute in a planetary ball mill to obtain alumina dispersion liquid with the volume ratio of the alumina powder being 50%.
Preparation of slurry-based phase liquid: 0.2g of acrylamide, 0.033g N, N' -methylenebisacrylamide and 1mL of the alumina nanodispersion described in step 1 of this example were weighed and mixed, followed by vortex shaking for 5 minutes to obtain a base phase fluid.
Preparation of a solidified phase fluid: weighing 1g of ammonium persulfate and 9g of deionized water, and carrying out vortex oscillation for 2 minutes to obtain 10 wt.% of ammonium persulfate aqueous solution, and weighing 20 mu L of tetramethylethylenediamine and 20 mu L of deionized water, and carrying out vortex oscillation for 30 seconds to obtain 50 vt.% of tetramethylethylenediamine aqueous solution; 500. mu.L of a 10 wt.% aqueous ammonium persulfate solution and 20. mu.L of a 50 vt.% aqueous tetramethylethylenediamine solution were weighed and mixed, and vortexed for 2 minutes to obtain a solidified-phase fluid.
Example 3
Preparing an alumina nano dispersion liquid: weighing 19.5g of alumina powder, 0.195g of ammonium citrate and 5g of deionized water, mixing, and ball-milling for 24 hours at 450 revolutions per minute in a planetary ball mill to obtain alumina dispersion liquid with the volume ratio of the alumina powder being 50%.
Preparation of slurry-based phase liquid: 0.2g of acrylamide, 0.033g of N, N' -methylenebisacrylamide and 1mL of the alumina nanodispersion described in step 1 of this example were weighed and mixed, followed by vortex shaking for 5 minutes to obtain a base phase fluid.
Preparation of a solidified phase fluid: weighing 1g of ammonium persulfate and 9g of deionized water, and carrying out vortex oscillation for 2 minutes to obtain 10 wt.% of ammonium persulfate aqueous solution, and weighing 30 mu L of tetramethylethylenediamine and 20 mu L of deionized water, and carrying out vortex oscillation for 30s to obtain 60 vt.% of tetramethylethylenediamine aqueous solution; 500. mu.L of a 10 wt.% aqueous solution of ammonium persulfate and 20. mu.L of a 60 vt.% aqueous solution of tetramethylethylenediamine were weighed and mixed, and vortexed for 2 minutes to obtain a solidified-phase fluid.
Example 4
A method for preparing alumina ceramic microfiber based on micro-fluid micro-reactor comprises the following steps:
the preparation of the ceramic microfiber green body was performed using the apparatus described in example 1 and the base phase and solidified phase fluids described in example 2, specifically:
(1) introducing the prepared base phase fluid of this example into an inlet tube (made of teflon) through a syringe, and then entering a microfluidic channel (made of polydimethylsiloxane); and when the base phase fluid stably flows in the microfluidic channel, introducing the solidified phase fluid into the metal microtube through the injector. The flow rates of the base phase fluid and the solidified phase fluid in the microfluidic channel are respectively fixed at 10 muL/min and 2 muL/min, and the heating temperature is 60 ℃ for testing.
(2) The green microfiber prepared at the end of the microreactor was received in a plastic cup into which a 3 wt.% aqueous ammonium persulfate solution was poured, and the uncured slurry liquid on the surface of the green microfiber was washed with the 3 wt.% aqueous ammonium persulfate solution and aged in a fresh 3 wt.% aqueous ammonium persulfate solution at 65 ℃ for 1 hour after the washing was completed.
(3) After aging the microfibers were allowed to dry on a teflon film for 12 hours, the average diameter of the microfibers would shrink.
(4) After drying, placing the microfiber green body in a sintering furnace, heating to 600 ℃ from room temperature at 1 ℃/min, and then heating to 1550 ℃ at 5 ℃/min; wherein the temperature is respectively kept at 114 ℃,235 ℃,374 ℃,495 ℃ and 600 ℃ for 1 hour, and at 1550 ℃ for 2 hours, and then the alumina ceramic microfiber can be obtained after furnace cooling.
Example 5
In contrast to example 4, the preparation of alumina ceramic microfibers was carried out using the base phase fluid, the solidified phase fluid obtained in example 2 and the apparatus of example 1.
Example 6
The difference from example 4 is that the reaction heating temperature of the base phase fluid and the solidified phase fluid in the microfluidic channel in step (1) was 50 ℃.
Comparative example 1
The differences from example 4 are: the heating temperature for the reaction of the base phase fluid and the solidified phase fluid in the microfluidic channel in step (1) was 30 ℃.
Comparative example 2
After the base phase and the solidified phase are mixed, a precursor (a traditional gel-casting slurry system) is introduced into a microfluidic channel by adopting a traditional gel-casting method, a precursor liquid column in the channel is solidified within 10s under the normal-temperature condition that a copper ring is not heated, so that the channel is blocked, and the precursor in an injector is solidified within 10s correspondingly. Even if the concentration of the solidification phase component is diluted, it is difficult to increase the ratio of the base phase and the solidification phase so that a green microfiber can be stably produced in a microfluidic channel for a long time with a small injection power.
Performance testing
FIG. 3 is a representation of the sintered alumina ceramic microfiber prepared in example 4, and FIG. 4, panel a, is an optical microscope image of the side and cross-section of a segment of ceramic fiber obtained by high temperature sintering of a green microfiber; b is a scanning electron microscope image of two microfibers; and c is a scanning electron microscope image of the surface topography of the microfibers under higher magnification. As can be seen from the figure: the cross section of the ceramic microfiber is circular, the fiber surface is smooth, and the fiber is in a porous structure after being amplified.
FIG. 4 is an optical microscope photograph of the fiber green body prepared in example 4 after knotting and braiding, wherein the images a and b are respectively the appearances of the green body and the ceramic before and after sintering of the bent round, cross knotted and braided knot. As can be seen from the figure: the microfibrils have high flexibility and good bending ability when not completely dried, and become rigid after dehydration, which is reversible with the addition of water and dehydration. Upon sintering, the flexibility of the microfibers ceases to exist and instead becomes a ceramic microfiber of higher strength and stiffness. By utilizing the method and the fiber characteristics, a more complex micro-fiber structure than 3D printing can be manufactured, so that the application of the micro-fiber in the fields of biology, aerospace, construction, catalyst carriers and the like is expanded.
The microfiber obtained in comparative example 1 had poor surface quality and low smoothness.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (15)
1. The preparation method of the alumina microfiber by using the alumina microfiber preparation device of the microfluidic chip is characterized by comprising the following steps of: the method comprises the following specific steps:
introducing a base phase fluid into the microfluidic channel through an inlet pipe, introducing a solidified phase fluid through a metal micro-pipe when the base phase fluid flows out of an outlet of the microfluidic channel, and obtaining a fiber green compact at the outlet of the microfluidic channel;
introducing the fiber green compact into a cleaning solution, placing the fiber into an aging solution for standing and curing after cleaning, drying the cured fiber to obtain a ceramic microfiber green compact, and sintering the ceramic microfiber green compact to obtain alumina ceramic microfiber;
the device for preparing the alumina microfiber by using the microfluidic chip comprises a microfluidic channel and a metal microtube, wherein the microfluidic channel is divided into a feeding area, a mixing area and a heating area along the flowing direction of slurry, the mixing area is positioned between the feeding area and the heating area, the feeding area is connected with the metal microtube, and one end of the metal microtube is inserted into the microfluidic channel.
2. A method of preparing an alumina microfiber according to claim 1, wherein: a plurality of stirring rods are arranged in the mixing area, two ends of each stirring rod are respectively connected with the inner wall of the microfluid channel, and two adjacent stirring rods are vertical in space.
3. A method of preparing an alumina microfiber according to claim 2, wherein: the stirring rods are horizontally arranged and vertically arranged.
4. A method of preparing an alumina microfiber according to claim 1, wherein: the end of the feeding zone remote from the mixing zone is connected to an inlet pipe.
5. A method of preparing an alumina microfiber according to claim 1, wherein: the heating device is arranged outside the heating zone of the microfluidic channel.
6. A method of preparing an alumina microfiber according to claim 1, wherein: the base phase fluid is a mixed solution of alumina nano dispersion liquid and prepolymer, the content of alumina nano particles in the base phase fluid is 70-75 wt%, and the content of the prepolymer is 8-10 wt%.
7. The method of producing an alumina microfiber according to claim 6, wherein: the content of alumina nanoparticles in the base phase fluid was 72.7 wt.%, and the content of prepolymer was 8.7 wt.%.
8. The method of producing an alumina microfiber according to claim 6, wherein: the prepolymer is prepared from the following raw materials in parts by weight: 85-86 parts of acrylamide and 14-15 parts of N, N' -methylene bisacrylamide.
9. The method of producing an alumina microfiber according to claim 6, wherein: the preparation method of the alumina nano dispersion liquid comprises the steps of mixing alumina powder, ammonium citrate and deionized water, and performing ball milling to obtain the alumina nano dispersion liquid.
10. A method of preparing an alumina microfiber according to claim 9, wherein: the average grain size of the alumina powder is 0.8-1.2 μm; the volume ratio of the deionized water to the alumina powder is 1-1.2: 1.
11. A method of preparing an alumina microfiber according to claim 9, wherein: the ammonium citrate accounts for 0.6-1% of the weight of the alumina powder.
12. A method of preparing an alumina microfiber according to claim 11, wherein: the curing phase fluid is a mixed solution of ammonium persulfate, tetramethylethylenediamine and water, the content of the curing phase initiator ammonium persulfate is 9-10 wt.%, and the content of the catalyst tetramethylethylenediamine is 2-3 wt.%;
or the flow rate ratio of the base phase fluid to the solidified phase fluid is 4-6:1, and the total flow rate is 11-13 muL/min;
or the heating area of the microfluid channel is set at 45-70 ℃;
or the cleaning solution of the fiber green body is an ammonium persulfate aqueous solution, and the mass fraction of the ammonium persulfate is 2-4%;
or the aging solution is 2-4% of ammonium persulfate aqueous solution in mass fraction.
13. A method of preparing an alumina microfiber according to claim 1, wherein: the sintering process comprises the following steps: respectively preserving heat at the temperature of 110-.
14. Alumina microfibers obtained by the process for the preparation of alumina microfibers according to any one of claims 1 to 13.
15. Use of the alumina microfibrils according to claim 14 in the fields of aviation, catalyst support, biology and construction.
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