CN114394612B - High-temperature-resistant low-density alumina nano rod aerogel and preparation method thereof - Google Patents

High-temperature-resistant low-density alumina nano rod aerogel and preparation method thereof Download PDF

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CN114394612B
CN114394612B CN202210105725.1A CN202210105725A CN114394612B CN 114394612 B CN114394612 B CN 114394612B CN 202210105725 A CN202210105725 A CN 202210105725A CN 114394612 B CN114394612 B CN 114394612B
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alumina
aerogel
temperature
resorcinol
nano rod
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CN114394612A (en
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冯坚
柳凤琦
姜勇刚
冯军宗
李良军
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National University of Defense Technology
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    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F7/00—Compounds of aluminium
    • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
    • C01F7/021—After-treatment of oxides or hydroxides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F7/00—Compounds of aluminium
    • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
    • C01F7/021—After-treatment of oxides or hydroxides
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    • C01P2006/13—Surface area thermal stability thereof at high temperatures
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Abstract

The invention discloses a high-temperature-resistant low-density alumina nano rod aerogel and a preparation method thereof. Gel, aging and supercritical drying; through pyrolysis, resorcinol-formaldehyde is converted into a carbon shell layer in the pyrolysis, and shrinkage force generated in the conversion process effectively inhibits crystal phase conversion and lattice rearrangement of core layer alumina to alpha phase at high temperature, so that sintering and great reduction of specific surface area caused by rapid growth of alpha phase crystal grains are avoided. Finally, the carbon template is removed by heating treatment, and the alumina nano rod aerogel with the three-dimensional network structure is obtained. The alumina nano rod aerogel prepared by the method has good high temperature resistance, and can be applied to the fields of heat insulation and heat preservation of aerospace, petrochemical industry, industrial kilns and the like.

Description

High-temperature-resistant low-density alumina nano rod aerogel and preparation method thereof
Technical Field
The invention relates to the technical field of aerogel preparation, in particular to a high-temperature-resistant low-density alumina nano rod aerogel and a preparation method thereof.
Background
Aerogel is a novel nano material with a three-dimensional porous network structure taking solid as a framework and gas as a dispersion medium, and has excellent performances such as high specific surface area, high porosity, low density and the like, so that the aerogel has great application prospects in the fields such as adsorption, catalysis, sensing, heat insulation and the like. SiO (SiO) 2 Aerogel is a relatively mature aerogel heat insulation material under current research, but at the high temperature of above 800 ℃, grains can grow rapidly, and structural collapse and performance reduction are shown. The carbon aerogel has good high temperature resistance, can bear high temperature of more than 1800 ℃ in an anaerobic environment, but has insufficient oxidation resistance, which severely limits the application field.
In contrast, the alumina aerogel has more excellent temperature resistance and oxidation resistance, does not generate obvious sintering even under the aerobic condition of 1000 ℃, can keep higher specific surface area, is a good high-temperature-resistant light heat-insulating material, and is expected to be applied to the field of high-temperature heat insulation.
Existing aluminaIn the aerogel preparation method, fibrous boehmite is used as a raw material to prepare transparent alumina aerogel, boehmite fibers prepared by a hydrothermal method are used as a raw material, and ultra-light Al with optical transparency is prepared by supercritical carbon dioxide 2 O 3 Fiber aerogel (ρ=1.2 mg/cm) 3 ). The aerogel material can resist 1000 ℃ high temperature, but after 1300 ℃ heat treatment, the volume of the aerogel is greatly contracted, the density is increased by 150 times, and the specific surface area is also 382m 2 /g drop to 4m 2 The specific surface area retention per gram was only 1.05%, and the microstructure was crimped from a fibrous structure into a sphere, and the optical transparency was lost. This is because boehmite phase is unstable at high temperature, dehydration and crystal form transformation to alpha-phase alumina occur with temperature rise, and rapid growth of alpha-phase alumina crystal grains leads to a large decrease in specific surface area and volume shrinkage of alumina fiber aerogel. It can be seen that the temperature resistance of the existing pure alumina aerogel still needs to be further improved.
Disclosure of Invention
The invention provides an alumina nano rod aerogel, a preparation method and application thereof, which are used for overcoming the defects of insufficient temperature resistance and the like of pure alumina aerogel in the prior art.
In order to achieve the above purpose, the invention provides a preparation method of alumina nanorod aerogel, comprising the following steps:
s1: mixing aluminum isopropoxide and deionized water under stirring, heating to 50-80 ℃, preserving heat for 0.5-3 h at 50-80 ℃, then heating to 85-100 ℃ from 50-80 ℃, preserving heat for 0.5-2 h at 85-100 ℃, adding acid substances, performing hydrothermal reaction, and cooling to room temperature to obtain aluminum oxide nanorods;
s2: mixing resorcinol with deionized water under stirring, dropwise adding sodium carbonate solution, stirring for 5-60 min, adding formaldehyde, uniformly mixing, and standing to obtain resorcinol-formaldehyde solution; adding the alumina nano rod into resorcinol-formaldehyde solution, heating and stirring to obtain alumina/resorcinol-formaldehyde reaction solution;
s3: heating the alumina/resorcinol-formaldehyde reaction liquid to 50-90 ℃ under normal pressure, preserving heat for 2-5 h at 50-90 ℃, aging, replacing alcohol solvent, and performing supercritical drying by taking carbon dioxide as a drying medium to obtain alumina/resorcinol-formaldehyde composite aerogel;
s4: and (3) cracking the alumina/resorcinol-formaldehyde composite aerogel in an inert atmosphere, and then performing heating treatment in an air atmosphere to obtain the alumina nano rod aerogel.
In order to achieve the aim, the invention also provides the alumina nano rod aerogel prepared by the preparation method.
In order to achieve the above purpose, the invention also provides an application of the alumina nano rod aerogel, wherein the alumina nano rod aerogel prepared by the preparation method or the alumina nano rod aerogel is applied to the heat insulation and preservation fields of aerospace, petrochemical industry and industrial kilns.
Compared with the prior art, the invention has the beneficial effects that:
1. the preparation method of the alumina nano rod aerogel provided by the invention adopts a carbon template method, firstly prepares the alumina nano rod, adopts the one-dimensional alumina nano rod with higher length-diameter ratio as a basic construction unit, and is more beneficial to the formation of a three-dimensional network structure compared with the traditional spherical nano particles, so that the former framework structure can be inherited even after a carbon shell layer is removed, the self-support of the alumina nano rod is realized, and the unique porous structure also endows the alumina nano rod aerogel with ultra-light property (rho < 0.1g/cm 3 ). Resorcinol-formaldehyde is used as a carbon source, and the alumina nano rod is completely coated by the carbon source through gel, aging and supercritical drying; and then the resorcinol-formaldehyde is converted into a carbon shell layer in the high-temperature pyrolysis, and the shrinkage force generated in the conversion process effectively inhibits the crystal phase conversion and lattice rearrangement of the nuclear layer alumina to alpha phase at high temperature, so that sintering and great reduction of specific surface area caused by rapid growth of alpha phase grains are avoided, and the temperature resistance of the alumina nano rod is improved. Finally, heating to remove the carbon template to obtain the alumina nano rod gas with a three-dimensional network structureAnd (5) gel. The preparation method provided by the invention has the advantages of simple and controllable process, short period of the whole process flow and suitability for batch preparation.
2. The alumina nano rod aerogel prepared by the invention has good high temperature resistance. After the aerogel is treated at high temperature, the specific surface area retention rate and the mesoporous structure are still high. After being treated for 30min at 1300 ℃ and 1400 ℃, the specific surface area retention rates can reach 81.3% and 36.4% respectively. According to the invention, resorcinol-formaldehyde with higher carbon residue rate is used as a carbon source, the adsorption effect between rich hydrophilic groups on resorcinol-formaldehyde molecules and the alumina nanorods is utilized, so that the alumina nanorods can be fully coated, carbon after high-temperature pyrolysis in inert atmosphere can effectively isolate the alumina nanorods, fusion and sintering of contact points at high temperature are avoided, the prepared aerogel material can still keep a complete mesoporous three-dimensional network structure even at high temperature of 1400 ℃, and high-efficiency heat insulation at high temperature is facilitated. The alumina nano rod aerogel prepared by the method can be applied to the fields of heat insulation and preservation of aerospace, petrochemical industry, industrial kilns and the like.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to the structures shown in these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for preparing an alumina nanorod aerogel according to the present invention;
FIG. 2a is an SEM image of an alumina/carbon composite aerogel prepared in example 1;
FIG. 2b is a macroscopic photograph of the alumina/carbon composite aerogel prepared in example 1;
FIG. 3 is an SEM image of an alumina nanorod aerogel prepared in example 1;
fig. 4 is an XRD spectrum of the alumina nanorod aerogel prepared in example 1.
The achievement of the objects, functional features and advantages of the present invention will be further described with reference to the accompanying drawings, in conjunction with the embodiments.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In addition, the technical solutions of the embodiments of the present invention may be combined with each other, but it is necessary to be based on the fact that those skilled in the art can implement the technical solutions, and when the technical solutions are contradictory or cannot be implemented, the combination of the technical solutions should be considered as not existing, and not falling within the scope of protection claimed by the present invention.
The drugs/reagents used are all commercially available without specific description.
The invention provides a preparation method of alumina nano rod aerogel, which is shown in figure 1 and comprises the following steps:
s1: aluminum isopropoxide (Al (OCHCH) 3 CH 3 ) 3 ) Mixing with deionized water under stirring, heating to 50-80 ℃, preserving heat for 0.5-3 h at 50-80 ℃, then heating to 85-100 ℃ from 50-80 ℃, preserving heat for 0.5-2 h at 85-100 ℃, adding acid substances as morphology regulators, carrying out hydrothermal reaction, and cooling to room temperature to obtain the aluminum oxide nanorods.
Preserving heat for 0.5-3 h at 50-80 ℃ to obtain fully hydrolyzed alumina solution.
Preserving the temperature for 0.5 to 2 hours at the temperature of 85 to 100 ℃ to evaporate the isopropanol generated by the hydrolysis.
Preferably, the mol ratio of the aluminum isopropoxide to the deionized water is (10-50): 1; the molar ratio of the acid substances to the aluminum isopropoxide is 4-18:1.
Preferably, the acid substance is one of dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid and acetic acid.
Preferably, the hydrothermal reaction is carried out at 160-220 ℃ for 4-24 hours.
The control of the molar ratio of aluminum isopropoxide to deionized water, the molar ratio of acid substances to aluminum isopropoxide and hydrothermal conditions is to control and obtain rod-shaped alumina, otherwise, the normal conditions are to obtain leaf-packed or feather-shaped alumina.
S2: mixing resorcinol with deionized water under stirring, dropwise adding sodium carbonate solution as a catalyst, stirring for 5-60 min, adding formaldehyde, uniformly mixing, and standing to obtain resorcinol-formaldehyde solution; adding the alumina nano rod into resorcinol-formaldehyde solution, heating and stirring to obtain alumina/resorcinol-formaldehyde reaction solution.
Preferably, the molar ratio of resorcinol to formaldehyde to sodium carbonate to deionized water is 1:2:0.002 (4-64), at which resorcinol and formaldehyde form resorcinol-formaldehyde under sodium carbonate catalysis; the mass ratio of the resorcinol-formaldehyde solution to the alumina nano rod is (0.05-2) 1, and the aim of controlling the ratio is to control the carbon content, so that the formation after carbon removal is not facilitated due to excessive carbon, the alumina is not fully wrapped due to insufficient carbon, and the temperature resistance is not facilitated.
Preferably, the temperature of the heating and stirring is 30-60 ℃ so as to fully and uniformly mix resorcinol-formaldehyde with alumina; the heating and stirring process is followed by vacuumizing for 10-60 min at 15-25 ℃ and 0.1-0.5 MPa to avoid bubbles, which is detrimental to the preparation of high specific surface area aerogel.
S3: heating the alumina/resorcinol-formaldehyde reaction liquid to 50-90 ℃ under normal pressure, preserving heat for 2-5 h at 50-90 ℃, aging, replacing alcohol solvent, and performing supercritical drying by taking carbon dioxide as a drying medium to obtain the alumina/resorcinol-formaldehyde composite aerogel.
Aging, and preserving heat for 2-5 days at 50-90 ℃.
Preferably, the supercritical drying specifically comprises:
carbon dioxide is used as a drying medium, liquid carbon dioxide with the pressure of 5-7 MPa is pre-charged, the heating is carried out at the speed of 1-2 ℃/min, the temperature (30-60 ℃) and the pressure (8-15 MPa) reach to be above the supercritical point of the carbon dioxide, and the pressure is released at the speed of 30-60 kPa/min after the heat preservation for 2-8 hours. The drying mode is favorable for forming the nano porous aerogel, and the pore structure is collapsed due to the surface tension generated by solvent evaporation in the normal pressure drying process.
S4: and (3) cracking the alumina/resorcinol-formaldehyde composite aerogel in an inert atmosphere, and then performing heating treatment in an air atmosphere to obtain the alumina nano rod aerogel.
Cracking to carbonize resorcinol-formaldehyde and form a carbon layer on the surface of the alumina nanorods.
And (3) heating to remove the carbon layer on the surface of the alumina nano rod.
Preferably, the cracking temperature is 1000-1500 ℃ and the time is 1-10 h; the temperature of the heating treatment is 500-1000 ℃ and the time is 1-10 h.
The invention also provides the alumina nano rod aerogel prepared by the preparation method.
The invention also provides application of the alumina nano rod aerogel, and the alumina nano rod aerogel prepared by the preparation method or the alumina nano rod aerogel is applied to the heat insulation and preservation fields of aerospace, petrochemical industry and industrial kilns.
Example 1
The embodiment provides a preparation method of alumina nano rod aerogel, which comprises the following steps:
s1: aluminum isopropoxide (Al (OCHCH) 3 CH 3 ) 3 ) With deionized water (H) 2 O) mixing under stirring, heating to 70 ℃ and preserving heat for 5 hours to obtain fully hydrolyzed alumina hydrolysate; further raising the temperature to 90 ℃ and preserving the heat for 0.5h, evaporating isopropanol generated by hydrolysis to obtain alumina sol; alumina sol and acetic acid were mixed according to a ratio of 10:1, after fully mixing, placing the mixture in a hydrothermal kettle, heating the mixture to 160 ℃, preserving the heat for 10 hours, and cooling the mixture to room temperature to obtain the oxidationAluminum nanorod dispersion.
S2: fully mixing resorcinol and deionized water under stirring, dropwise adding a sodium carbonate solution into the solution after the resorcinol and the deionized water are fully dissolved, stirring for 30min, adding a certain amount of formaldehyde into the mixed solution, and standing for 1h after stirring for a period of time to obtain a resorcinol-formaldehyde solution, wherein the molar ratio of resorcinol to formaldehyde to sodium carbonate to deionized water is 1:2:0.002:32. Mixing resorcinol-formaldehyde with the alumina nano rod dispersion liquid obtained in the step one according to the mass ratio of 0.8:1, stirring for 1h at 25 ℃, and vacuumizing to obtain the alumina/resorcinol-formaldehyde sol.
S3: heating the alumina/resorcinol-formaldehyde sol to 50 ℃ under normal pressure, preserving heat for 5 hours to form alumina/resorcinol-formaldehyde composite gel, maintaining aging for 3 days at 50 ℃ and replacing with ethanol solvent to obtain replaced alumina/resorcinol-formaldehyde composite gel. Placing the replaced composite gel in an autoclave, adopting carbon dioxide (mass fraction is more than or equal to 99.5%) as a drying medium, pre-charging liquid carbon dioxide with the pressure of 7MPa, heating to 50 ℃ at the speed of 1-2 ℃/min, enabling the temperature and the pressure (12 MPa) to reach above the supercritical point of the carbon dioxide, preserving heat for 6 hours, slowly releasing the pressure at the speed of 30 kPa/min, and finally obtaining the alumina/resorcinol-formaldehyde composite aerogel.
S4: cracking the alumina/resorcinol-formaldehyde composite aerogel obtained in the step S3 for 2 hours under the condition of inert atmosphere and 1400 ℃ to obtain alumina/carbon composite aerogel (shown in figure 2 b); further, the alumina/carbon composite aerogel is placed in an air atmosphere and is subjected to heat treatment for 5 hours at the temperature of 600 ℃ to obtain the high-temperature-resistant low-density alumina nano rod aerogel.
The specific surface area of the alumina nanorod aerogel (after carbon removal) prepared in this example was 107m 2 Per g, the specific surface area and the retention rate after 1300 ℃ heat treatment are 87m respectively 2 Specific surface area and retention after heat treatment at 1400℃were 29m for each of/g and 81.3% 2 /g and 36.4%. FIG. 2a is a microscopic morphology of an alumina/carbon composite aerogel taken with a scanning electron microscope, in which it can be seen that the rod-shaped alumina is coarsenedThe rough carbon shell is fully wrapped, and the wrapping is uniform. Fig. 3 is a microscopic morphology of a high temperature resistant alumina nanorod aerogel photographed by a scanning electron microscope, which shows that sufficient overlap between the nanorods can be achieved and a three-dimensional network structure can be formed after carbon removal. Fig. 4 is an XRD spectrum of the high temperature resistant alumina nanorod aerogel, which shows that after high temperature cracking, alumina is not converted into alpha phase, but forms theta phase with smaller crystal grains, indicating that the carbon shell layer effectively inhibits the crystal phase conversion of alumina, thereby improving the temperature resistance of alumina.
Example 2
In step S4, the alumina/carbon composite aerogel material is subjected to heat treatment under an air atmosphere at 800 ℃ for 5 hours to obtain the high-temperature-resistant low-density alumina nanorod aerogel. The other procedure was as in example 1.
The high-temperature-resistant alumina nanorod aerogel prepared in the embodiment is subjected to temperature resistance examination, and the specific surface area of the sample after 1300 ℃ thermal examination (air atmosphere) for 30min is found to be 72m 2 G, the surface of the sample is not obviously changed and cracking and structural collapse do not occur; the specific surface area of the sample after 30min of thermal examination (air atmosphere) at 1400 ℃ is 26m 2 And/g, the surface of the sample has no obvious change and has no cracking and structural collapse, which indicates that the sample can resist the high temperature of 1400 ℃, and other performance parameters are shown in table 1.
Example 3
In step S2, resorcinol-formaldehyde is mixed with the alumina nanorod dispersion liquid according to a mass ratio of 0.8:1, and then the alumina/resorcinol-formaldehyde sol is directly obtained without vacuumizing. The other procedure was as in example 1.
The high-temperature-resistant alumina nanorod aerogel prepared in the embodiment is subjected to temperature resistance examination, and the specific surface area of the sample after 1300 ℃ thermal examination (air atmosphere) for 30min is found to be 62m 2 G, the surface of the sample is not obviously changed and cracking and structural collapse do not occur; the sample was checked (empty) by heat at 1400 ℃Atmosphere) for 30min, the specific surface area is 20m 2 And/g, the surface of the sample has no obvious change and has no cracking and structural collapse, which indicates that the sample can resist the high temperature of 1400 ℃, and other performance parameters are shown in table 1.
Example 4
In step S4, the alumina/resorcinol-formaldehyde composite aerogel is cracked for 1h under an inert atmosphere at 1400 ℃ to obtain an alumina/carbon composite aerogel material. The other procedure was as in example 1.
The high-temperature-resistant alumina nanorod aerogel prepared in the embodiment is subjected to temperature resistance examination, and the samples are found to have no obvious change in surface and no cracking and structural collapse after 1300 ℃ thermal examination (air atmosphere) for 30 min; after the sample is subjected to thermal examination (air atmosphere) at 1400 ℃ for 30min, the surface of the sample is not obviously changed, and cracking and structural collapse do not occur, so that the sample can resist the high temperature of 1400 ℃, and other performance parameters are shown in table 1.
Example 5
In the present example, compared with example 1, in step S2, resorcinol-formaldehyde is mixed with the alumina nanorod dispersion according to a mass ratio of 0.3:1. The other procedure was as in example 1.
The high-temperature-resistant alumina nanorod aerogel prepared in the embodiment is subjected to temperature resistance examination, and the samples are found to have no obvious change in surface and no cracking and structural collapse after 1300 ℃ thermal examination (air atmosphere) for 30 min; after the sample is subjected to thermal examination (air atmosphere) at 1400 ℃ for 30min, the surface of the sample is not obviously changed, and cracking and structural collapse do not occur, so that the sample can resist the high temperature of 1400 ℃, and other performance parameters are shown in table 1.
Comparative example 6
The comparative example provides a method for preparing an alumina nanorod aerogel, and compared with the embodiment 1, in the step S4, the alumina/resorcinol-formaldehyde composite aerogel is cracked for 2 hours under the condition of inert atmosphere and 1300 ℃ to obtain the alumina/carbon composite aerogel material. The other procedure was as in example 1.
The high temperature resistant alumina nano rod aerogel prepared in the comparative example is subjected to temperature resistance examination, and the specific surface area of the sample after 1300 ℃ thermal examination (air atmosphere) for 30min is found to be 24m 2 G, the surface of the sample is not obviously changed and cracking and structural collapse do not occur; the specific surface area of the sample after being subjected to 1400 ℃ heat examination (air atmosphere) for 30min is less than 10m 2 And/g, the sample is obviously shrunk and cracks appear on the surface, which indicates that the sample cannot withstand the high temperature of 1400 ℃, and other performance parameters are shown in table 1.
Comparative example 1
This comparative example provides a method for preparing an alumina nanorod aerogel, in which resorcinol-formaldehyde is mixed with an alumina nanorod dispersion in a mass ratio of 3:1 in step S2, compared with example 1. The other procedure was as in example 1.
In the process of performing temperature resistance assessment on the high-temperature-resistant alumina nanorod aerogel prepared in the comparative example, the strength of the sample is extremely low after carbon removal, the sample is crushed after slight vibration, and further temperature resistance test cannot be performed, because the excessive isolation effect is generated on the alumina nanorod due to the excessive carbon content, the alumina nanorod after the carbon shell is removed cannot be effectively lapped and self-supported, so that the strength of the sample is greatly reduced, and other performance parameters are shown in table 1.
Comparative example 2
This comparative example provides a method for preparing an alumina nanorod aerogel, in which resorcinol-formaldehyde is mixed with an alumina nanorod dispersion in a mass ratio of 0.02:1 in step S2, as compared with example 1. The other procedure was as in example 1.
The high temperature resistant alumina nanorod aerogel prepared in the comparative example is subjected to temperature resistance examination, and after the high temperature resistant alumina nanorod aerogel is subjected to 1300 ℃ thermal examination (air atmosphere) for 30min, the sample is obviously shrunk and has cracks on the surface, which indicates that the sample cannot bear the high temperature of 1300 ℃, because the carbon content is too low, the alumina nanorod cannot be fully coated, the carbon template does not have the function of fully isolating and inhibiting the transformation of the crystal form of the alumina, the sample is sintered in the high temperature examination process, and other performance parameters are shown in table 1.
Table 1 shows comparison tables of performance parameters of the high temperature resistant alumina nanorod aerogels prepared in examples 1 to 5 and comparative examples 1 to 3, and as can be seen from Table 1, the main parameters affecting the performance of the aerogel in the present invention are the molar ratio of the carbon source precursor to alumina, the cracking temperature and the time.
TABLE 1 Performance parameters of high temperature resistant alumina nanorod aerogels prepared in examples 1-5 and comparative examples 1-3
The foregoing description is only of the preferred embodiments of the present invention and is not intended to limit the scope of the invention, and all equivalent structural changes made by the description of the present invention and the accompanying drawings or direct/indirect application in other related technical fields are included in the scope of the invention.

Claims (7)

1. The preparation method of the high-temperature-resistant low-density alumina nano rod aerogel is characterized by comprising the following steps of:
s1: mixing aluminum isopropoxide and deionized water under stirring, heating to 50-80 ℃, preserving heat for 0.5-3 h at 50-80 ℃, then heating from 50-80 ℃ to 85-100 ℃, preserving heat for 0.5-2 h at 85-100 ℃, adding acid substances, performing hydrothermal reaction, and cooling to room temperature to obtain aluminum oxide nanorods; the mol ratio of the acid substance to the aluminum isopropoxide is (4-18): 1; the acid substance is one of dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid and acetic acid;
s2: mixing resorcinol with deionized water under stirring, dropwise adding a sodium carbonate solution, stirring for 5-60 min, adding formaldehyde, uniformly mixing, and standing to obtain a resorcinol-formaldehyde solution; adding the alumina nano rod into resorcinol-formaldehyde solution, heating and stirring to obtain alumina/resorcinol-formaldehyde reaction solution; the mass ratio of the resorcinol-formaldehyde solution to the alumina nano rod is (0.05-2) 1;
s3: heating the alumina/resorcinol-formaldehyde reaction liquid to 50-90 ℃ under normal pressure, preserving heat for 2-5 hours at 50-90 ℃, aging, replacing alcohol solvent, and performing supercritical drying by taking carbon dioxide as a drying medium to obtain alumina/resorcinol-formaldehyde composite aerogel; the supercritical drying specifically comprises the following steps: pre-charging liquid carbon dioxide with the pressure of 5-7 MPa by taking carbon dioxide as a drying medium, heating at the speed of 1-2 ℃/min to ensure that the temperature and the pressure reach above the supercritical point of the carbon dioxide, preserving heat for 2-8 hours, and then releasing the pressure at the speed of 30-60 kPa/min; the temperature is 30-60 ℃, and the pressure is 8-15 MPa;
s4: cracking the alumina/resorcinol-formaldehyde composite aerogel in an inert atmosphere, and then performing heating treatment in an air atmosphere to obtain an alumina nano rod aerogel; the cracking temperature is 1000-1500 ℃ and the cracking time is 1-10 h; the temperature of the heating treatment is 500-1000 ℃ and the time is 1-10 h.
2. The method according to claim 1, wherein in the step S1, the molar ratio of the aluminum isopropoxide to the deionized water is (10-50): 1.
3. The method according to claim 1, wherein in the step S1, the hydrothermal reaction is performed at 160 to 220 ℃ for 4 to 24 hours.
4. The method according to claim 1, wherein in the step S2, the molar ratio of resorcinol, formaldehyde, sodium carbonate and deionized water is 1:2:0.002 (4-64).
5. The preparation method according to claim 1 or 4, wherein in the step S2, the temperature of heating and stirring is 30-60 ℃; and vacuumizing is carried out for 10-60 min under the conditions that the temperature is 15-25 ℃ and the vacuum degree is 0.1-0.5 MPa.
6. The high-temperature-resistant low-density aluminum oxide nanorod aerogel is characterized by being prepared by the preparation method of any one of claims 1-5.
7. The application of the high-temperature-resistant low-density alumina nano rod aerogel is characterized in that the alumina nano rod aerogel prepared by the preparation method of any one of claims 1-5 or the alumina nano rod aerogel of claim 6 is applied to the heat insulation and preservation fields of aerospace, petrochemical industry and industrial kilns.
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102716700A (en) * 2012-06-18 2012-10-10 南京工业大学 Preparation method of high-strength high-temperature-resistant blocky C-AlN composite aerogel
WO2017211227A1 (en) * 2016-06-08 2017-12-14 中国科学院金属研究所 High-strength large dimension block-form aerographite, and manufacturing method and application thereof
CN111252789A (en) * 2020-01-18 2020-06-09 航天特种材料及工艺技术研究所 High-temperature-resistant alumina nanocrystalline aerogel material and preparation method thereof
CN111943704A (en) * 2020-08-18 2020-11-17 航天特种材料及工艺技术研究所 Reusable high-temperature-resistant nanocrystalline aerogel material and preparation method thereof

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102716700A (en) * 2012-06-18 2012-10-10 南京工业大学 Preparation method of high-strength high-temperature-resistant blocky C-AlN composite aerogel
WO2017211227A1 (en) * 2016-06-08 2017-12-14 中国科学院金属研究所 High-strength large dimension block-form aerographite, and manufacturing method and application thereof
CN111252789A (en) * 2020-01-18 2020-06-09 航天特种材料及工艺技术研究所 High-temperature-resistant alumina nanocrystalline aerogel material and preparation method thereof
CN111943704A (en) * 2020-08-18 2020-11-17 航天特种材料及工艺技术研究所 Reusable high-temperature-resistant nanocrystalline aerogel material and preparation method thereof

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