CN110894166B - Preparation method of mullite porous graded fibrous material - Google Patents

Preparation method of mullite porous graded fibrous material Download PDF

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CN110894166B
CN110894166B CN201911222689.1A CN201911222689A CN110894166B CN 110894166 B CN110894166 B CN 110894166B CN 201911222689 A CN201911222689 A CN 201911222689A CN 110894166 B CN110894166 B CN 110894166B
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fiber
aqueous solution
acid aqueous
aluminum
fibrous material
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CN110894166A (en
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何飞
李文洁
杨立娟
宋大君
于明
王林
李宏博
朱振
李明伟
赫晓东
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Harbin Institute Of Technology Beijing Military And Civil Integration Innovation Institute Co ltd
Harbin Institute of Technology
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Harbin Institute Of Technology Beijing Military And Civil Integration Innovation Institute Co ltd
Harbin Institute of Technology
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Abstract

A preparation method of mullite porous graded fibrous material relates to a preparation method of mullite graded material. The invention aims to solve the technical problem that the quality of whiskers and fibers cannot be accurately regulated and controlled in a large range in the conventional mullite porous graded fibrous material. Firstly, the invention uses the low-cost polycrystalline mullite fiber to be dedicated to the research of low-cost high-performance samples. The mullite graded fibrous material prepared by combining the control of fiber sedimentation and the injection method can regulate and control the proportion of whiskers and fibers in a graded structure on the premise of controlling low density.

Description

Preparation method of mullite porous graded fibrous material
Technical Field
The invention relates to a preparation method of a mullite grading material.
Background
The mullite porous fibrous material is an aluminosilicate material and has the advantages of a three-dimensional network structure similar to a bird nest, good high-temperature mechanical property, good chemical stability, low thermal conductivity, good creep property, good thermal shock resistance and the like. The preparation process can be adjusted to meet the performance requirements of different application occasions, such as gas and wastewater filters, separation membranes, catalyst carriers, heat-insulating materials and other fields with special requirements on pore diameter and structure. At present, a plurality of synthesis methods are used for obtaining a mullite whisker/fiber hierarchical structure with a three-dimensional structure, and mainly comprise a fluorine catalytic gas phase reaction method, a molten salt method and the like. Many researchers have attempted to produce mullite whiskers from different aluminum sources (e.g., bauxite, aluminum nitrate), different silicon sources (e.g., silica, ethyl orthosilicate), and different catalysts (e.g., aluminum fluoride, ammonia fluoride, silicon fluoride) that have a significant impact on whisker morphology and synthesis conditions.
At present, research on the grading material mostly focuses on exploration of a whisker growth mechanism and influence of the proportion of effective components (an aluminum source, a silicon source and a catalyst) in raw materials on the organizational structure and the performance of the grading material, the research on the influence of the whisker to fiber mass ratio in the grading structure on the organizational structure and the performance of the grading material is less, researchers mostly adopt a suction filtration method to change the mass ratio of the whisker to the fiber in the grading material, and the method cannot accurately regulate and control the quality ratio of the whisker to the fiber in a large range. On the basis, the development of a method for preparing the grading material with the adjustable whisker-to-fiber mass ratio is of great significance.
Disclosure of Invention
The invention provides a preparation method of a mullite porous graded fibrous material, aiming at solving the technical problem that the quality of whiskers and fibers cannot be accurately regulated and controlled in a large range in the existing mullite porous graded fibrous material.
The preparation method of the mullite porous graded fibrous material is carried out according to the following steps:
firstly, preparing a fiber blank:
firstly, cutting polycrystalline mullite fiber into granular fiber by using scissors, sieving the granular fiber by using a 40-mesh sieve, and repeatedly sieving the granular fiber until no slag balls are sieved out; the diameter of the granular fiber is 0.5 mm-3 mm;
secondly, putting the screened granular fibers in the step I into a soybean milk machine, adding water, and chopping for 20-22 min, wherein the rotating speed of the soybean milk machine is 10000-11000 r/min; the mass ratio of the screened granular fibers to the water in the first step is 1 (100-110);
thirdly, after the short cutting, pouring all the mixture in the soymilk machine obtained in the second step into a container, standing for 20-25 s, then pouring out and retaining the upper layer of fibers, and removing the slag balls at the bottom;
fourthly to five times of the operation of the third step is repeated to remove the slag balls, and the upper layer of the fiber is filtered by gauze to remove water, so that chopped fiber is obtained;
fifthly, dispersing the chopped fibers in the fourth step into an acetic acid aqueous solution containing a binder, and then stirring for 30-35 min to obtain slurry; the mass of the chopped fiber is 1.5-2% of that of an acetic acid aqueous solution containing a binder; the concentration of acetic acid in the acetic acid aqueous solution containing the binder is 0.5-0.6 mol/L; the adhesive in the acetic acid aqueous solution containing the adhesive is chitosan, and the mass of the adhesive is 0.5-2% of that of the acetic acid aqueous solution containing the adhesive;
pouring the slurry prepared in the fifth step into a mold, putting the mold into a refrigerator, freezing at the temperature of minus 18-minus 20 ℃ until the slurry is completely frozen, putting the mold into a freeze dryer, freeze-drying at the temperature of minus 60-minus 65 ℃ and the vacuum degree of 150-200 Pa for 72-74 h, and finally demolding to obtain a fiber blank;
secondly, preparing active slurry:
preparing an aluminum sol:
mixing aluminum sec-butoxide with water, refluxing and stirring for 1-1.5 h under the condition of 70-100 ℃ water bath, then adding dilute nitric acid aqueous solution to promote further hydrolysis, clarifying the solution from milky color, then continuously refluxing and stirring for 9-10 h under the condition of 70-100 ℃ water bath to obtain mixed sol, and putting the mixed sol into a constant-temperature stirring heater at 100-110 ℃ until the content of Al element in the mixed sol is 1-1.1 mol/L to obtain aluminum sol; the molar ratio of the aluminum sec-butoxide to the water is 0.12 (9.5-10); the mass ratio of the dilute nitric acid aqueous solution to the secondary aluminum butoxide is 1 (6-7);
preparing silica sol:
pouring tetraethoxysilane into a beaker, adding absolute ethyl alcohol, adding deionized water to form a mixed solution, putting the mixed solution into a water bath at the temperature of 40-50 ℃ for heat preservation for 10-15 min, dripping hydrochloric acid aqueous solution, and preserving the heat for 1-1.5 h in the water bath at the temperature of 40-50 ℃ to obtain silica sol; the molar ratio of the tetraethoxysilane to the deionized water is 1 (4-5); the molar ratio of the tetraethoxysilane to the absolute ethyl alcohol is 1 (4-5); the molar ratio of the ethyl orthosilicate to the hydrogen chloride in the hydrochloric acid aqueous solution is 1 (7.5 multiplied by 10)-4~10-3) (ii) a The concentration of the hydrochloric acid aqueous solution is 0.2-0.3 mol/L;
thirdly, mixing the aluminum sol obtained in the second step and the silica sol obtained in the second step, adding a catalyst, and stirring for 12-15 hours to obtain active slurry; the catalyst is aluminum fluoride powder, and the molar ratio of aluminum element in the catalyst to aluminum element in the aluminum sol is 3 (6-8); the molar ratio of the aluminum element to the silicon element in the active slurry is 3 (1.1-1.3);
thirdly, injection:
injecting the active slurry in the step two into the fiber blank in the step one by using an injection device, wherein the injection device is provided with an injection head, the side wall of the injection head is provided with a plurality of holes, and the active slurry flows into the fiber blank through the holes in the side wall and the holes at the bottom of the injection head;
fourthly, freezing and freeze-drying:
and putting the injected fiber blank into a refrigerator, freezing at the temperature of minus 18-minus 20 ℃ until the fiber blank is completely frozen, putting the sample into a freeze drier, freeze-drying for 72-74 h at the temperature of minus 50-minus 60 ℃ and the vacuum degree of 150-200 Pa, and taking out to obtain a graded sample blank.
Fifthly, heat treatment:
and (3) placing the graded sample blank prepared in the fourth step into a crucible, covering the crucible with a cover, then placing the crucible into a muffle furnace, heating the crucible to 800-1200 ℃ from room temperature at a heating rate of 3-5 ℃/min in the air atmosphere, preserving the heat at 800-1200 ℃ for 2-3 h, and then cooling along with the furnace to obtain the mullite porous graded fibrous material.
The invention is characterized in that:
compared with the porous fibrous material prepared by the traditional process methods such as the gravity precipitation method, the pressurized liquid discharge method, the vacuum filtration method and the like, the invention adopts the freezing injection molding method to change the viscosity of the slurry by adding the chitosan in the step one to control the fiber sedimentation so as to realize more accurate control on the density of the fiber blank; compared with the traditional method for preparing the graded fibrous material by blending and sintering the fiber and the active powder, the method firstly prepares a fiber blank with lower density, and then realizes the regulation and control of the proportion of the whiskers and the fibers in the graded fibrous material by controlling the dosage of the active slurry injected into the network structure of the fiber, thereby realizing the regulation and control of the performance of the graded fibrous material and further realizing the preparation of the optimal graded structure.
The invention has the beneficial effects that:
firstly, the invention uses the low-cost polycrystalline mullite fiber to be dedicated to the research of low-cost high-performance samples. The invention can control the low density (0.03 g/cm) of the mullite graded fibrous material prepared by combining the control of fiber sedimentation and the injection method3~0.08g/cm3) The ratio of whiskers to fibers in the hierarchical structure is regulated and controlled on the premise of (1).
Drawings
Fig. 1 is an SEM image of mullite porous graded fibrous material prepared in run one.
Detailed Description
The first embodiment is as follows: the embodiment is a preparation method of a mullite porous graded fibrous material, which is specifically carried out according to the following steps:
firstly, preparing a fiber blank:
firstly, cutting polycrystalline mullite fiber into granular fiber by using scissors, sieving the granular fiber by using a 40-mesh sieve, and repeatedly sieving the granular fiber until no slag balls are sieved out; the diameter of the granular fiber is 0.5 mm-3 mm;
secondly, placing the screened granular fibers in a soybean milk machine, adding water, and chopping for 20-22 min, wherein the rotation speed of the soybean milk machine is 10000-11000 r/min; the mass ratio of the screened granular fibers to the water in the first step is 1 (100-110);
thirdly, after the short cutting, pouring all the mixture in the soymilk machine obtained in the second step into a container, standing for 20-25 s, then pouring out and retaining the upper layer of fibers, and removing the slag balls at the bottom;
fourthly, repeating the operation of the third step for four to five times to remove the slag balls, and filtering the upper layer fiber by using gauze to remove water to obtain chopped fiber;
fifthly, dispersing the chopped fibers in the step IV into an acetic acid aqueous solution containing a binder, and then stirring for 30-35 min to obtain slurry; the mass of the chopped fiber is 1.5-2% of that of an acetic acid aqueous solution containing a binder; the concentration of acetic acid in the acetic acid aqueous solution containing the binder is 0.5-0.6 mol/L; the adhesive in the acetic acid aqueous solution containing the adhesive is chitosan, and the mass of the adhesive is 0.5-2% of that of the acetic acid aqueous solution containing the adhesive;
pouring the slurry prepared in the fifth step into a mold, putting the mold into a refrigerator, freezing at the temperature of minus 18-minus 20 ℃ until the slurry is completely frozen, putting the mold into a freeze dryer, freeze-drying at the temperature of minus 60-minus 65 ℃ and the vacuum degree of 150-200 Pa for 72-74 h, and finally demolding to obtain a fiber blank;
secondly, preparing active slurry:
preparation of aluminum sol:
mixing aluminum sec-butoxide with water, refluxing and stirring for 1-1.5 h under the condition of 70-100 ℃ water bath, then adding dilute nitric acid aqueous solution to promote further hydrolysis, clarifying the solution from milky color, then continuously refluxing and stirring for 9-10 h under the condition of 70-100 ℃ water bath to obtain mixed sol, and putting the mixed sol into a constant-temperature stirring heater at 100-110 ℃ until the content of Al element in the mixed sol is 1-1.1 mol/L to obtain aluminum sol; the molar ratio of the aluminum sec-butoxide to the water is 0.12 (9.5-10); the mass ratio of the dilute nitric acid aqueous solution to the secondary aluminum butoxide is 1 (6-7);
preparing silica sol:
pouring tetraethoxysilane into a beaker, adding absolute ethyl alcohol, adding deionized water to form a mixed solution, putting the mixed solution into a water bath at the temperature of 40-50 ℃ for heat preservation for 10-15 min, dripping hydrochloric acid aqueous solution, and preserving the heat for 1-1.5 h in the water bath at the temperature of 40-50 ℃ to obtain silica sol; the molar ratio of the ethyl orthosilicate to the deionized water is 1 (4-5); the molar ratio of the ethyl orthosilicate to the absolute ethyl alcohol is 1 (4-5); the molar ratio of the ethyl orthosilicate to the hydrogen chloride in the hydrochloric acid aqueous solution is 1 (7.5 multiplied by 10)-4~10-3) (ii) a The concentration of the hydrochloric acid aqueous solution is 0.2-0.3 mol/L;
thirdly, mixing the aluminum sol obtained in the second step and the silica sol obtained in the second step, adding a catalyst, and stirring for 12-15 hours to obtain active slurry; the catalyst is aluminum fluoride powder, and the molar ratio of aluminum element in the catalyst to aluminum element in the aluminum sol is 3 (6-8); the molar ratio of the aluminum element to the silicon element in the active slurry is 3 (1.1-1.3);
thirdly, injection:
injecting the active slurry in the step two into the fiber blank in the step one by using an injection device, wherein the injection device is provided with an injection head, the side wall of the injection head is provided with a plurality of holes, and the active slurry flows into the fiber blank through the holes in the side wall and the holes at the bottom of the injection head;
fourthly, freezing and freeze drying:
putting the injected fiber blank into a refrigerator, freezing at the temperature of minus 18-minus 20 ℃ until the fiber blank is completely frozen, putting the sample into a freeze dryer, freeze-drying for 72-74 h at the temperature of minus 50-minus 60 ℃ and the vacuum degree of 150-200 Pa, and taking out to obtain a graded sample blank;
fifthly, heat treatment:
and (3) placing the graded sample blank prepared in the fourth step into a crucible, covering the crucible with a cover, then placing the crucible into a muffle furnace, heating the crucible to 800-1200 ℃ from room temperature at a heating rate of 3-5 ℃/min in the air atmosphere, preserving the heat at 800-1200 ℃ for 2-3 h, and then cooling along with the furnace to obtain the mullite porous graded fibrous material.
The second embodiment is as follows: the first difference between the present embodiment and the specific embodiment is: step one, putting the screened granular fibers in the step one into a soybean milk machine, adding water, and chopping for 20min, wherein the rotating speed of the soybean milk machine is 10000 r/min; the mass ratio of the screened granular fibers to the water in the step I is 1: 100. The rest is the same as the first embodiment.
The third concrete implementation mode: the present embodiment differs from the first or second embodiment in that: dispersing the chopped fibers in the step (IV) into an acetic acid aqueous solution containing a binder, and then stirring for 30min to obtain slurry; the mass of the chopped fiber is 1.5 percent of that of an acetic acid aqueous solution containing a binder; the concentration of acetic acid in the acetic acid aqueous solution containing the binder is 0.5 mol/L; the adhesive in the acetic acid aqueous solution containing the adhesive is chitosan, and the mass of the adhesive is 0.5 percent of that of the acetic acid aqueous solution containing the adhesive. The others are the same as in the first or second embodiment.
The fourth concrete implementation mode: the difference between this embodiment mode and one of the first to third embodiment modes is: pouring the slurry prepared in the fifth step into a mold, putting the mold into a refrigerator, freezing at the temperature of 18 ℃ below zero until the slurry is completely frozen, putting the mold into a freeze dryer, freeze-drying for 72 hours at the temperature of 60 ℃ below zero and the vacuum degree of 150Pa, and finally demolding to obtain a fiber blank. The rest is the same as one of the first to third embodiments.
The fifth concrete implementation mode: the fourth difference between this embodiment and the specific embodiment is that: and the concentration of the dilute nitric acid aqueous solution in the second step is 1 mol/L. The rest is the same as the fourth embodiment.
The sixth specific implementation mode: the fourth difference between this embodiment and the specific embodiment is that: mixing the aluminum sol obtained in the step two and the silica sol obtained in the step two, adding a catalyst, and stirring for 12 hours to obtain active slurry; the catalyst is aluminum fluoride powder, and the molar ratio of aluminum element in the catalyst to aluminum element in the aluminum sol is 3: 7; the molar ratio of the aluminum element to the silicon element in the active slurry is 3: 1.2. The rest is the same as the fourth embodiment.
The seventh embodiment: the fourth difference between this embodiment and the specific embodiment is that: and step four, putting the injected fiber blank into a refrigerator, freezing the fiber blank to be completely frozen at the temperature of 18 ℃ below zero, putting the sample into a freeze dryer, freeze-drying the sample for 72 hours at the temperature of 50 ℃ below zero and the vacuum degree of 150Pa, and taking out the sample to obtain a graded sample blank. The rest is the same as the fourth embodiment.
The specific implementation mode is eight: the fourth difference between this embodiment and the specific embodiment is that: and fifthly, placing the graded sample blank prepared in the fourth step into a crucible, covering the crucible with a cover, then placing the crucible into a muffle furnace, heating the crucible to 1000 ℃ from room temperature at a heating rate of 3 ℃/min in the air atmosphere, preserving the heat for 2h at 1000 ℃, and then cooling the crucible along with the furnace to obtain the mullite porous graded fibrous material. The rest is the same as the fourth embodiment.
The invention was verified with the following tests:
the first test: the test is a preparation method of mullite porous graded fibrous material, which is specifically carried out according to the following steps:
firstly, preparing a fiber blank:
firstly, cutting polycrystalline mullite fiber into granular fiber by using scissors, sieving the granular fiber by using a 40-mesh sieve, and repeatedly sieving the granular fiber until no slag balls are sieved out; the diameter of the granular fibers is 2 mm;
secondly, putting the screened granular fibers in the step I into a soybean milk machine, adding water, and chopping for 20min, wherein the rotating speed of the soybean milk machine is 10000 r/min; the mass ratio of the screened granular fibers to the water in the step I is 1: 100;
thirdly, after the short cutting, pouring all the mixture in the soymilk machine obtained in the second step into a container, standing for 20s, pouring out and reserving the fibers on the upper layer, and removing the slag balls at the bottom;
fourthly, the operation of the third step is repeated for four times to remove the slag balls, and the upper layer of the fiber is filtered by gauze to remove water, so that chopped fiber is obtained;
fifthly, dispersing the chopped fibers in the step IV into an acetic acid aqueous solution containing a binder, and then stirring for 30min to obtain slurry; the mass of the chopped fiber is 1.5 percent of that of an acetic acid aqueous solution containing a binder; the concentration of acetic acid in the acetic acid aqueous solution containing the binder is 0.5 mol/; the adhesive in the acetic acid aqueous solution containing the adhesive is chitosan, and the mass of the adhesive is 0.5 percent of that of the acetic acid aqueous solution containing the adhesive;
pouring the slurry prepared in the fifth step into a mold, putting the mold into a refrigerator, freezing at the temperature of 18 ℃ below zero until the slurry is completely frozen, putting the mold into a freeze dryer, freeze-drying for 72 hours at the temperature of 60 ℃ below zero and the vacuum degree of 150Pa, and finally demolding to obtain a fiber blank;
the test shows that the density of the fiber blank is 0.022g/cm3
The fiber blank is a cylinder, the diameter of the bottom surface is 3.8cm, and the height is 2.8 cm;
secondly, preparing active slurry:
preparing an aluminum sol:
mixing aluminum sec-butoxide with water, refluxing and stirring for 1h under the condition of 70 ℃ water bath, then adding dilute nitric acid aqueous solution to promote further hydrolysis, changing the solution from milky color to clear, continuously refluxing and stirring for 9h under the condition of 70 ℃ water bath to obtain mixed sol, and putting the mixed sol into a constant-temperature stirring heater at 100 ℃ until the content of Al element in the mixed sol is 1mol/L to obtain aluminum sol; the molar ratio of the aluminum sec-butoxide to the water is 0.12: 10; the mass ratio of the dilute nitric acid aqueous solution to the aluminum sec-butoxide is 1: 7; the concentration of the dilute nitric acid aqueous solution is 1 mol/L;
preparing silica sol:
pouring tetraethoxysilane into a beaker, adding absolute ethyl alcohol, adding deionized water to form a mixed solution, putting the mixed solution into a water bath at 40 ℃ for heat preservation for 10min, dripping hydrochloric acid aqueous solution, and preserving the heat in the water bath at 40 ℃ for 1h to obtain silica sol; the molar ratio of the ethyl orthosilicate to the deionized water is 1: 4; the molar ratio of the ethyl orthosilicate to the absolute ethyl alcohol is 1: 4; the molar ratio of the tetraethoxysilane to the hydrogen chloride in the hydrochloric acid aqueous solution is 1:7.5 multiplied by 10-4(ii) a The concentration of the hydrochloric acid aqueous solution is 0.2 mol/L;
thirdly, mixing the aluminum sol obtained in the second step and the silica sol obtained in the second step, adding a catalyst, and stirring for 12-15 hours to obtain active slurry; the catalyst is aluminum fluoride powder, and the molar ratio of aluminum element in the catalyst to aluminum element in the aluminum sol is 3: 7; the molar ratio of the aluminum element to the silicon element in the active slurry is 3: 1.2;
thirdly, injection:
injecting the active slurry obtained in the step two into the fiber blank obtained in the step one by using an injection device, wherein the injection device is provided with an injection head, the side wall of the injection head is provided with a plurality of holes, and 3mL of active slurry flows into the fiber blank through the holes in the side wall and the holes at the bottom of the injection head; injection depth: repeatedly moving the injection head up and down within the range of 0.9-2.8 cm away from the bottom layer of the fiber blank body for injection; injection speed: 0.05 mL/s; the injection head is a needle head;
fourthly, freezing and freeze drying:
putting the injected fiber blank into a refrigerator, freezing the fiber blank at the temperature of minus 18 ℃ until the fiber blank is completely frozen, putting the sample into a freeze drier, freeze-drying the sample for 72 hours at the temperature of minus 50 ℃ and the vacuum degree of 150Pa, and taking out the sample to obtain a graded sample blank;
fifthly, heat treatment:
and (3) placing the graded sample blank prepared in the fourth step into a crucible, covering the crucible with a cover, then placing the crucible into a muffle furnace, heating the crucible to 1000 ℃ from room temperature at a heating rate of 3 ℃/min in the air atmosphere, preserving the heat at 1000 ℃ for 2h, and then cooling along with the furnace to obtain the mullite porous graded fibrous material.
Fig. 1 is an SEM image of the mullite porous graded fibrous material prepared in the first experiment, from which it can be seen that the mullite fiber surface is a well-developed whisker secondary structure shaped like needles and densely grown.
The mullite graded fibrous material prepared by combining the control of fiber sedimentation and the injection method in the test can control the low density (0.06 g/cm)3) And the ratio of the whiskers to the fibers in the hierarchical structure is regulated and controlled on the premise of low thermal conductivity (0.04667W/mK).

Claims (8)

1. A preparation method of a mullite porous graded fibrous material is characterized by comprising the following steps:
firstly, preparing a fiber blank:
firstly, cutting polycrystalline mullite fiber into granular fiber by using scissors, sieving the granular fiber by using a 40-mesh sieve, and repeatedly sieving the granular fiber until no slag balls are sieved out; the diameter of the granular fiber is 0.5 mm-3 mm;
secondly, putting the screened granular fibers in the step I into a soybean milk machine, adding water, and chopping for 20-22 min, wherein the rotating speed of the soybean milk machine is 10000-11000 r/min; the mass ratio of the screened granular fibers to the water in the first step is 1 (100-110);
thirdly, after the short cutting, pouring all the mixture in the soymilk machine obtained in the second step into a container, standing for 20-25 s, then pouring out and retaining the upper layer of fibers, and removing the slag balls at the bottom;
fourthly, repeating the operation of the third step for four to five times to remove the slag balls, and filtering the upper layer fiber by using gauze to remove water to obtain chopped fiber;
fifthly, dispersing the chopped fibers in the step IV into an acetic acid aqueous solution containing a binder, and then stirring for 30-35 min to obtain slurry; the mass of the chopped fiber is 1.5-2% of that of an acetic acid aqueous solution containing a binder; the concentration of acetic acid in the acetic acid aqueous solution containing the binder is 0.5-0.6 mol/L; the adhesive in the acetic acid aqueous solution containing the adhesive is chitosan, and the mass of the adhesive is 0.5-2% of that of the acetic acid aqueous solution containing the adhesive;
pouring the slurry prepared in the fifth step into a mold, putting the mold into a refrigerator, freezing at the temperature of minus 18-minus 20 ℃ until the slurry is completely frozen, putting the mold into a freeze dryer, freeze-drying at the temperature of minus 60-minus 65 ℃ and the vacuum degree of 150-200 Pa for 72-74 h, and finally demolding to obtain a fiber blank;
II, preparing active slurry:
preparation of aluminum sol:
mixing aluminum sec-butoxide with water, refluxing and stirring for 1-1.5 h under the condition of 70-100 ℃ water bath, then adding dilute nitric acid aqueous solution to promote further hydrolysis, clarifying the solution from milky color, then continuously refluxing and stirring for 9-10 h under the condition of 70-100 ℃ water bath to obtain mixed sol, and putting the mixed sol into a constant-temperature stirring heater at 100-110 ℃ until the content of Al element in the mixed sol is 1-1.1 mol/L to obtain aluminum sol; the molar ratio of the aluminum sec-butoxide to the water is 0.12 (9.5-10); the mass ratio of the dilute nitric acid aqueous solution to the secondary aluminum butoxide is 1 (6-7);
preparing silica sol:
pouring tetraethoxysilane into a beaker, adding absolute ethyl alcohol, adding deionized water to form a mixed solution, putting the mixed solution into a water bath at the temperature of 40-50 ℃ for heat preservation for 10-15 min, dripping hydrochloric acid aqueous solution, and preserving the heat for 1-1.5 h in the water bath at the temperature of 40-50 ℃ to obtain silica sol; the molar ratio of the ethyl orthosilicate to the deionized water is 1 (4-5); the molar ratio of the ethyl orthosilicate to the absolute ethyl alcohol is 1 (4-5); the molar ratio of the ethyl orthosilicate to the hydrogen chloride in the hydrochloric acid aqueous solution is 1 (7.5 multiplied by 10)-4~10-3) (ii) a The concentration of the hydrochloric acid aqueous solution is 0.2-0.3 mol/L;
thirdly, mixing the aluminum sol obtained in the second step and the silica sol obtained in the second step, adding a catalyst, and stirring for 12-15 hours to obtain active slurry; the catalyst is aluminum fluoride powder, and the molar ratio of aluminum element in the catalyst to aluminum element in the aluminum sol is 3 (6-8); the molar ratio of the aluminum element to the silicon element in the active slurry is 3 (1.1-1.3);
thirdly, injection:
injecting the active slurry in the step two into the fiber blank in the step one by using an injection device, wherein the injection device is provided with an injection head, the side wall of the injection head is provided with a plurality of holes, and the active slurry flows into the fiber blank through the holes in the side wall and the holes at the bottom of the injection head;
fourthly, freezing and freeze drying:
putting the injected fiber blank into a refrigerator, freezing at the temperature of minus 18-minus 20 ℃ until the fiber blank is completely frozen, putting the sample into a freeze dryer, freeze-drying for 72-74 h at the temperature of minus 50-minus 60 ℃ and the vacuum degree of 150-200 Pa, and taking out to obtain a graded sample blank;
fifthly, heat treatment:
and (3) placing the graded sample blank prepared in the fourth step into a crucible, covering the crucible with a cover, then placing the crucible into a muffle furnace, heating the crucible to 800-1200 ℃ from room temperature at a heating rate of 3-5 ℃/min in the air atmosphere, preserving the heat at 800-1200 ℃ for 2-3 h, and then cooling along with the furnace to obtain the mullite porous graded fibrous material.
2. The preparation method of the mullite porous graded fibrous material as claimed in claim 1, wherein the screened granular fibers in the first step are put into a soybean milk machine, water is added for chopping for 20min, and the rotation speed of the soybean milk machine is 10000 r/min; the mass ratio of the screened granular fibers to the water in the step I is 1: 100.
3. The method for preparing the mullite porous graded fibrous material as claimed in claim 1, wherein the fibers chopped in the step (iv) are dispersed in an acetic acid aqueous solution containing a binder, and then stirred for 30min to obtain a slurry; the mass of the chopped fiber is 1.5 percent of that of an acetic acid aqueous solution containing a binder; the concentration of acetic acid in the acetic acid aqueous solution containing the binder is 0.5 mol/L; the adhesive in the acetic acid aqueous solution containing the adhesive is chitosan, and the mass of the adhesive is 0.5 percent of that of the acetic acid aqueous solution containing the adhesive.
4. The method for preparing mullite porous graded fibrous material as claimed in claim 1, wherein the slurry prepared in the fifth step is poured into a mold, the mold is placed into a refrigerator and is frozen at a temperature of-18 ℃ until the slurry is completely frozen, then the mold is placed into a freeze dryer and is freeze-dried for 72 hours at a temperature of-60 ℃ and a vacuum degree of 150Pa, and finally the fiber blank is obtained after demolding.
5. The method for preparing a mullite porous graded fibrous material as claimed in claim 1, wherein the concentration of the dilute aqueous nitric acid solution in the second (r) step is 1 mol/L.
6. The method for preparing the mullite porous graded fibrous material according to claim 1, wherein in the second third step, the alumina sol in the second third step and the silica sol in the second third step are mixed, then a catalyst is added, and the mixture is stirred for 12 hours to obtain active slurry; the catalyst is aluminum fluoride powder, and the molar ratio of aluminum element in the catalyst to aluminum element in the aluminum sol is 3: 7; the molar ratio of the aluminum element to the silicon element in the active slurry is 3: 1.2.
7. The method for preparing the mullite porous graded fibrous material according to claim 1, wherein the injected fiber blank is placed in a refrigerator in the fourth step, and is frozen at-18 ℃ until the blank is completely frozen, and then the sample is placed in a freeze dryer, is freeze-dried for 72 hours at-50 ℃ and 150Pa of vacuum degree, and is taken out to obtain a graded sample blank.
8. The method for preparing the mullite porous graded fibrous material according to claim 1, wherein the graded sample blank prepared in the fourth step is placed in a crucible in the fifth step, the crucible is covered by a cover, then the crucible is placed in a muffle furnace, the temperature is raised to 1000 ℃ from room temperature at the heating rate of 3 ℃/min in the air atmosphere, the temperature is kept at 1000 ℃ for 2h, and then the mullite porous graded fibrous material is obtained after furnace cooling.
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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5340516A (en) * 1989-07-28 1994-08-23 Engelhard Corporation Thermal shock and creep resistant porous mullite articles prepared from topaz and process for manufacture
CN105036780A (en) * 2015-08-26 2015-11-11 哈尔滨工业大学 Preparation method of mullite-fiber-reinforced fused quartz composite material
CN105110779A (en) * 2015-01-02 2015-12-02 海南大学 Preparation method of mullite porous ceramic by welding whisker
CN108610086A (en) * 2018-06-01 2018-10-02 哈尔滨工业大学 A kind of preparation method of three-dimensional network shape porous fibre matter heat-barrier material
CN109320193A (en) * 2017-07-31 2019-02-12 天津大学 Mullite fiber/mullite crystal whisker/aerosil multilevel structure and its preparation method and application
CN110468453A (en) * 2019-09-23 2019-11-19 哈工大(北京)军民融合创新研究院有限公司 A kind of preparation method of growth in situ high length-diameter ratio mullite crystal whisker

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5340516A (en) * 1989-07-28 1994-08-23 Engelhard Corporation Thermal shock and creep resistant porous mullite articles prepared from topaz and process for manufacture
CN105110779A (en) * 2015-01-02 2015-12-02 海南大学 Preparation method of mullite porous ceramic by welding whisker
CN105036780A (en) * 2015-08-26 2015-11-11 哈尔滨工业大学 Preparation method of mullite-fiber-reinforced fused quartz composite material
CN109320193A (en) * 2017-07-31 2019-02-12 天津大学 Mullite fiber/mullite crystal whisker/aerosil multilevel structure and its preparation method and application
CN108610086A (en) * 2018-06-01 2018-10-02 哈尔滨工业大学 A kind of preparation method of three-dimensional network shape porous fibre matter heat-barrier material
CN110468453A (en) * 2019-09-23 2019-11-19 哈工大(北京)军民融合创新研究院有限公司 A kind of preparation method of growth in situ high length-diameter ratio mullite crystal whisker

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