CN109626954B - Temperature-resistant moisture-proof silicon dioxide aerogel composite material and preparation method and application thereof - Google Patents

Temperature-resistant moisture-proof silicon dioxide aerogel composite material and preparation method and application thereof Download PDF

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CN109626954B
CN109626954B CN201811506605.2A CN201811506605A CN109626954B CN 109626954 B CN109626954 B CN 109626954B CN 201811506605 A CN201811506605 A CN 201811506605A CN 109626954 B CN109626954 B CN 109626954B
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catalyst
fluorine
composite material
temperature
group
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CN109626954A (en
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黄红岩
张恩爽
刘韬
雷朝帅
贺丽娟
赵英民
李文静
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Aerospace Research Institute of Materials and Processing Technology
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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B30/00—Compositions for artificial stone, not containing binders
    • C04B30/02—Compositions for artificial stone, not containing binders containing fibrous materials
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/20—Resistance against chemical, physical or biological attack
    • C04B2111/27—Water resistance, i.e. waterproof or water-repellent materials
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
    • C04B2201/20—Mortars, concrete or artificial stone characterised by specific physical values for the density
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
    • C04B2201/30—Mortars, concrete or artificial stone characterised by specific physical values for heat transfer properties such as thermal insulation values, e.g. R-values
    • C04B2201/32—Mortars, concrete or artificial stone characterised by specific physical values for heat transfer properties such as thermal insulation values, e.g. R-values for the thermal conductivity, e.g. K-factors

Abstract

The invention relates to a preparation method of a temperature-resistant moisture-proof silicon dioxide aerogel composite material, which comprises the following steps: (1) preparing a silica sol by hydrolysis-polycondensation reaction with a silicon-containing coupling reagent in the presence of a catalytic amount of a first catalyst, and the silicon-containing coupling reagent comprises a fluorine-containing coupling agent; (2) and (2) impregnating a fiber reinforcement with the silica sol in the presence of a catalytic amount of a second catalyst, and carrying out sol-gel, aging, solvent replacement and drying to obtain the hydrophobic fiber-reinforced aerogel composite material. The invention also provides a temperature-resistant moisture-proof silicon dioxide aerogel composite material and application thereof. The method has the advantages of simple process, few operation steps and low equipment cost; the composite material has good temperature resistance, particularly high temperature resistance, excellent moisture resistance, low room temperature thermal conductivity, stable thermal conductivity, adjustable density and stable and controllable impurity content.

Description

Temperature-resistant moisture-proof silicon dioxide aerogel composite material and preparation method and application thereof
Technical Field
The invention belongs to the technical field of thermal protection, and particularly relates to a temperature-resistant moisture-proof silicon dioxide aerogel composite material and a preparation method and application thereof.
Background
Aerogel is a light material with a unique nanometer three-dimensional porous network structure, is a solid substance with the lowest known thermal conductivity at present, and is called super heat insulation material. The silica aerogel is the most commonly used aerogel material, has the characteristics of high porosity, large specific surface, rich surface hydrophilic group content and the like, and is easy to adsorb moisture in the air to influence the heat insulation performance of the material. Thus, hydrophobicization is often required during the production of silica aerogel materials to increase their stability in air and their useful life.
At present, it has been proposed to achieve hydrophobic modification by several means: (1) the obtained gel is subjected to solvent substitution in an inert solvent by using trimethylchlorosilane, hexamethyldisilazane, hexamethyldisiloxane or the like as a modifier, and then modified by adding the modifier (see, for example, CN 107337424A). In addition, hydrophobic modification by cogelling of silicone ester precursors with hydrophobic group-containing siloxanes (e.g., methyltrimethoxysilane, etc.) or directly with hydrophobic group-containing siloxane gels has also been proposed (see, e.g., CN104016360A and CN 106745004A). However, the above solution uses a hydrophobic solution for moisture resistance to construct the hydrophobic layer of the material as an alkane group, which is generally not more than 350 ℃. Moreover, due to the incompleteness of the sol-gel reaction, the hydrophobically treated aerogel surface still contains a significant amount of alkoxy groups, such groups having a temperature resistance of less than 300 ℃. This makes the material lose the moisture-proof property after being used at high and low temperature of more than 350 ℃ for one time under the air condition. Silica aerogel materials that lose moisture resistance can become extremely hygroscopic (moisture absorption rate even greater than 30% in the relevant constant temperature and humidity test), thereby losing reliability of use as high performance reusable insulation materials. In summary, current hydrophobization processes do not achieve the desired performance stability and repeatability improvements. Therefore, there is an urgent need to develop a silica aerogel composite material that can be recycled at high and low temperatures and has good moisture resistance and excellent heat insulation properties.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a method for preparing a temperature-resistant moisture-proof silicon dioxide aerogel composite material, which comprises the following steps: (1) preparing a silica sol by hydrolysis-polycondensation reaction with a silicon-containing coupling reagent in the presence of a catalytic amount of a first catalyst, and the silicon-containing coupling reagent comprises a fluorine-containing coupling agent; (2) and (2) impregnating a fiber reinforcement with the silica sol in the presence of a catalytic amount of a second catalyst, and carrying out sol-gel, aging, solvent replacement and drying to obtain the hydrophobic fiber-reinforced aerogel composite material.
The invention provides in a second aspect a temperature resistant moisture proof silica aerogel composite comprising a fluorine-containing hydrophobic layer structure;
in a third aspect, the present invention provides the use of a composite material according to any one of the first aspect of the invention or a composite material according to the second aspect of the invention in the manufacture of a composite component; preferably, the composite material member is selected from the group consisting of a plate-shaped member, a hemispherical member, a quasi-hemispherical member, a conical member and a profiled surface member.
Compared with the prior art, the invention has at least the following beneficial effects:
(1) the method has the advantages of simple process, few operation steps and low equipment cost.
(2) The composite material has good temperature resistance and can be repeatedly used within the range of 25-600 ℃.
(3) The composite material of the invention has good high temperature resistance and can be repeatedly used at the temperature of 600 ℃.
(4) The composite material has excellent moisture resistance, and the moisture absorption rate of the composite material is not more than 6 percent, even not more than 2 percent after the composite material is repeatedly used for more than 10 times within the range of 600 ℃.
(5) The composite material of the present invention has low room temperature thermal conductivity, which may be no more than 0.025W/mK.
(6) The composite material has stable thermal conductivity, and the change of the thermal conductivity of the material is not more than 6% after the composite material is repeatedly used for more than 10 times at 25-600 ℃.
(7) The density can be between 0.20g/cm3 and 0.40g/cm3Is adjustable within the range of (1).
(8) The content of impurities is stable and controllable, and the aerogel still has good moisture resistance after being used for many times, and is obviously superior to the common aerogel.
In summary, the aerogel composite material prepared by the invention has good temperature resistance, especially good high temperature resistance, and excellent moisture resistance, breaks through the temperature resistance limit of the hydrophobicity of the existing aerogel material, can meet the requirement of stable reusability, can be stored for a long time under a humid condition without influencing the performance, and can be used as a thermal protection material for insulating heat in a large area in an aircraft with high Mach number and long voyage. The composite aerogel material disclosed by the invention can be used for preparing flat, hemispherical, quasi-hemispherical, conical and various large special-shaped surface components, and has guiding significance for the production of special-shaped rigid heat-insulating components used in service in complex high-low temperature alternating environments.
Detailed Description
The present invention is described in further detail below, but the present invention is not limited thereto.
As described above, the present invention provides, in a first aspect, a method for preparing a temperature-resistant moisture-proof silica aerogel composite, the method comprising the steps of: (1) preparing a silica sol by hydrolysis-polycondensation reaction with a silicon-containing coupling reagent in the presence of a catalytic amount of a first catalyst, and the silicon-containing coupling reagent comprises a fluorine-containing coupling agent; (2) and (2) impregnating a fiber reinforcement with the silica sol in the presence of a catalytic amount of a second catalyst, and carrying out sol-gel, aging, solvent replacement and drying to obtain the hydrophobic fiber-reinforced aerogel composite material.
The inventors have discovered that the hydrophobic temperature resistance range of aerogel materials can be greatly improved by using fluorine-containing groups and even perfluoro groups.
In some preferred embodiments, the method further comprises the steps of: (3) and carrying out surface activation treatment on the hydrophobic fiber reinforced aerogel composite material at high temperature to obtain the surface activated fiber reinforced aerogel composite material. Preferably, the activation temperature of the surface activation is 400 to 600 ℃ (e.g., 400, 450, 500, 550 or 600 ℃), preferably 450 to 550 ℃ (e.g., 500 ℃), and the activation time is 0.5 to 1.5 hours (e.g., 0.5, 1, or 1.5 hours). The inventor finds that, aiming at the problem that unstable residues exist locally after the material is dried and molded, unstable residual active groups and water on the surface can be removed through high-temperature treatment to realize surface activation, and the hydrophobic fiber-reinforced aerogel composite material with better temperature resistance and more damp-proof surface local activation is obtained.
In some preferred embodiments, the method further comprises the steps of: (4) and (3) carrying out hydrophobization treatment on the surface activated fiber reinforced aerogel composite material by using a hydrophobization reagent, and drying to obtain the hydrophobization aerogel composite material. The inventor finds that if the material is molded and subjected to surface activation, and then is subjected to further modification, particularly fluorine-containing group modification, by using a hydrophobizing agent, the distribution and content of fluorine-containing groups in the hydrophobic layer can be further enhanced, so that the temperature resistance and moisture resistance of the material are further enhanced.
In some preferred embodiments, the hydrophobizing treatment is carried out in the presence of a catalytic amount of a third catalyst. More preferably, the mass of the hydrophobizing agent is controlled to be 5 to 20 mass% of the total mass of the material. More preferably, the hydrophobization treatment is performed in a vacuum or atmospheric state by fumigation or/and spraying, the hydrophobization temperature is 40 to 120 ℃ (e.g., 40, 60, 80, 100 or 120 ℃), and the hydrophobization time is 6 to 72 hours (e.g., 12, 24, 36, 48 or 60 hours).
In some embodiments, in step (1), the fluorine-containing coupling agent comprises a fluorine-containing silane coupling agent; and/or in step (3), the hydrophobizing agent is a fluorochemical silane hydrophobizing agent. Preferably, the fluorochemical silane coupling agent and/or the fluorochemical silane hydrophobizing agent is selected from the group consisting of those of formula R4-n-(Si)-(O-R’)nWherein n is 1 to 3 (e.g., 1, 2 or 3), R is selected from the group consisting of a fluoroalkyl group of 1 to 10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10) carbons, a fluoroaryl group of 6 to 12 (e.g., 6, 7, 8, 9, 10, 11 or 12) carbons, or a single fluorine atom, wherein the number of fluoroalkyl groups is 1 to 19 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16 or 18) fluorine atoms, and the fluoroaryl group contains a fluoroaryl groupAn atomic number of 1-10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10); O-R' is selected from the group consisting of alkoxy groups having 1 to 5 (e.g., 1, 2, 3, 4, or 5) carbons in number. It is further preferred that the fluorine-containing silane coupling agent and/or fluorine-containing silane hydrophobizing agent is selected from the group consisting of tridecafluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane or pentafluorophenyltrimethoxysilane (by way of example, but not by way of limitation, of these three).
In some embodiments, the first catalyst is an acidic catalyst. Preferably, the first catalyst is one or more selected from the group consisting of oxalic acid, acetic acid, formic acid and hydrochloric acid solution. More preferably, the concentration of the first catalyst is 0.01-0.1M; even more preferably, the molar ratio of the first catalyst to the silicon-containing coupling agent is 1:20 to 10000 (e.g., 1:20, 1:50, 1:100, 1:1000, or 1: 10000).
In some further embodiments, the second catalyst is an acidic catalyst or a basic catalyst. Preferably, in the case where the second catalyst is an acidic catalyst, the second catalyst is one or more selected from the group consisting of oxalic acid, acetic acid, formic acid, and hydrochloric acid solution. In the case where the second catalyst is a basic catalyst, the second catalyst is selected from one or more of the group consisting of ammonia, sodium hydroxide and ammonium fluoride.
The amount of the catalyst used in the present invention is not particularly limited as long as it can exert the intended flower-forcing effect (for example, catalytic amount). Preferably, however, the molar ratio of the second catalyst to the silicon-containing coupling agent is 1:20 to 10000 (e.g., 1:20, 1:50, 1:100, 1:1000, or 1: 10000). In the present invention, the concentration of the second catalyst is not particularly limited, and may be, for example, 0.01 to 0.1M (e.g., 0.01M, 0.02M, 0.04M, 0.06M, 0.08M, 0.1M).
In some embodiments, the third catalyst may be an acid catalyst. Preferably, the third catalyst may be one or more selected from the group consisting of trifluoroacetic acid, acetic acid, formic acid and hydrochloric acid. More preferably, the concentration of the third catalyst is 0.01 to 0.1M (e.g., 0.01M, 0.02M, 0.04M, 0.06M, 0.08M, 0.1M), and still more preferably, the molar ratio of the third catalyst to the hydrophobizing agent is 1: 5000-10000 (e.g., 1: 5000, 1: 7500, or 1: 10000).
The invention can effectively adjust the structure and the content of the hydrophobic layer of the material by adjusting the type or the addition amount of the catalyst, optionally adjusting the surface activation time, the type or the addition amount of the surface modification reagent and optionally adjusting the proportion of the fluorine-containing silane coupling agent and the orthosilicate reagent, ensures that the material has excellent heat insulation and temperature resistance, and still has good heat insulation performance and moisture resistance after repeated use.
The fibers in the fiber reinforcement are not particularly limited in the present invention, but preferably the fibers in the fiber reinforcement are selected from one or more of the group consisting of basalt fibers, glass fibers, quartz fibers, mullite fibers, or alumina fibers.
In preferred embodiments, the first catalyst is an acidic catalyst and the second catalyst is a basic catalyst. In some further embodiments, the first catalyst, the second catalyst, and the third catalyst are each independently an acidic catalyst. The first catalyst, the second catalyst, and the third catalyst may be the same or different, provided that the first catalyst cannot use a basic catalyst.
In preferred embodiments, the fluorine-containing coupling reagent further comprises an orthosilicate;
preferably, the molar ratio of the orthosilicate to the fluorine-containing silane coupling agent is 0 to 100:1 (e.g., 0:1, 0.5:1, 1:1, 5:1, 10:1, 20:1, 50:1, or 100: 1). More preferably, the orthosilicate and the fluorine-containing silane coupling agent are first stirred at room temperature for 6 to 24 hours (e.g., 12 or 18 hours) at the time of use.
In some more specific embodiments, the method of the present invention comprises steps (1) to (4) described above. Specifically, the method comprises the following steps:
step (1)
The fluorine-containing silane coupling agent and optional orthosilicate ester are subjected to hydrolysis-polycondensation reaction for 6-24 hours in an alcohol solvent under the acidic catalysis condition serving as a first catalyst, and a temperature-resistant hydrophobic layer structure is constructed on the surface of sol particles to form the temperature-resistant hydrophobic layer structure.
In the presence of an orthosilicate, the fluorine-containing silane coupling agent and the orthosilicate may be blended under acidic catalytic conditions with an alcohol (e.g., ethanol, methanol) solvent, for example, in a mixing ratio of 1:0 to 100 (e.g., 1:0, 1:0.5, 1:1, 1:5, 1:10, 1:20, 1:50, or 1:100) as described above, and stirred at room temperature for 6h to 24h (e.g., 12 or 18 h). Wherein the first catalyst is selected from the group consisting of oxalic acid, acetic acid, formic acid, and hydrochloric acid solutions, may be at a concentration of 0.01 to 0.1M (e.g., 0.01M, 0.02M, 0.04M, 0.06M, 0.08M, 0.1M), and may be in a molar ratio to the silicon-containing coupling reagent of 1:20 to 10000 (e.g., 1:20, 1:50, 1:100, 1:1000, or 1: 10000).
Step (2)
Adding a second catalyst (which can be an acid catalyst or a basic catalyst) into the treated silica sol, and impregnating the reinforced fiber matrix in a vacuum impregnation mode, a pressure impregnation mode or a vacuum-pressure impregnation mode. Wherein, in case that the second catalyst is an acid catalyst, the second catalyst may be one or more selected from the group consisting of oxalic acid, acetic acid, formic acid and hydrochloric acid solution; preferably, the concentration of the second catalyst is 0.01-0.1M; more preferably, the molar ratio of the second catalyst to the silicon-containing coupling agent is 1:20 to 10000 (e.g., 1:20, 1:50, 1:100, 1:1000, or 1: 10000). More preferably, in the case where the second catalyst is a basic catalyst, the second catalyst is selected from the group consisting of ammonia, sodium hydroxide and ammonium fluoride solutions having a concentration of 0.001 to 0.1M, and may have a concentration of 0.01 to 0.1M (e.g., 0.01M, 0.02M, 0.04M, 0.06M, 0.08M, 0.1M), and may have a molar ratio to the silicon-containing coupling agent of 1:20 to 10000 (e.g., 1:20, 1:50, 1:100, 1:1000, or 1: 10000). Then carrying out sol-gel reaction, and carrying out solvent replacement and drying after the aging is finished. Sol-gel reaction, aging and solvent displacement of silica sols are all techniques known to those skilled in the art. The solvent substitution can be performed using a substitution solvent such as acetone. The drying method is not particularly limited in the present invention, but a supercritical drying method is preferably used, and a supercritical carbon dioxide drying method is particularly preferably used, and these drying methods are known in the art.
Step (3)
In the step (3), the surface activation temperature may be 400 to 600 ℃, preferably 450 to 550 ℃ (for example, 500), and the total time of the surface activation may be 0.5 to 1.5 hours (for example, 0.5, 1 or 1.5 hours). In some embodiments, the aerogel material obtained in the above steps can be subjected to high temperature activation using different temperature control procedures to obtain a surface-activated composite. The temperature programming stage can be, for example, one or more of (a)400 ℃, the heat preservation time is 0.5-1 h, or (b)500 ℃, the heat preservation time is 1-1.5 h, or (c)600 ℃, and the heat preservation time is 0.5-1 h, so that the surface of the material is fully activated and the surface structure composition is not obviously changed.
Step (4)
In step (4), the hydrophobizing agent may include, but is not limited to: tridecafluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane or pentafluorophenyl trimethoxysilane. In the hydrophobizing treatment of the aerogel material in the container, which is cooled to room temperature after surface activation, a hydrophobizing agent and a third catalyst, which may be an acidic catalyst, for example, selected from the group consisting of trifluoroacetic acid, acetic acid, formic acid and hydrochloric acid solutions, may be added thereto at a concentration of 0.01 to 0.1M (for example, 0.01M, 0.02M, 0.04M, 0.06M, 0.08M, 0.1M), and may be in a molar ratio to the hydrophobizing agent, such as a fluorine-containing silane hydrophobizing agent, of 1: 5000-10000 (such as 1: 5000, 1: 7500, or 1: 10000), wherein the mass of the hydrophobic agent is controlled to be 5-20% (such as 5%, 10%, 15%, or 20%) of the total mass of the material, the hydrophobic manner can be fumigation or/and spraying, the hydrophobic treatment is carried out in a vacuum or normal pressure state, the hydrophobic temperature is 40-120 ℃ (such as 40, 60, 80, 100, or 120 ℃), and the hydrophobic time is 6-72 h (such as 6, 12, 24, 48, or 72 h). After the hydrophobic treatment, the material can be dried, and the drying and impurity removal processes of the material can be realized by adopting a vacuumizing or 150 ℃ air blasting mode, so that the heat-insulating material with excellent high-temperature heat-insulating effect and good moisture resistance after multiple high-temperature and low-temperature cycles is obtained.
According to the invention, the fluorine-containing hydrophobic layer structure on the surface layer of the aerogel nanoparticles is constructed in a copolycondensation mode, and the 600 ℃ resistant moistureproof aerogel composite material is obtained in a fiber composite silicon dioxide aerogel mode. In some preferred embodiments, the material is subjected to high-temperature activation treatment to remove impurities fully, the further improvement of the fluorine-containing temperature-resistant hydrophobic layer structure is realized in a catalytic hydrophobic mode, and finally the 600 ℃ resistant reusable moisture-proof silica aerogel composite material with excellent heat insulation performance is obtained.
The present invention provides, in a second aspect, a temperature-resistant, moisture-proof silica aerogel composite comprising a fluorine-containing hydrophobic layer structure. Preferably, the temperature-resistant moisture-proof silica aerogel composite material has the following properties: (1) the heat conductivity at room temperature is less than or equal to 0.025W/mK; (2) the moisture absorption rate of the material is less than or equal to 2% after the material is repeatedly used for more than 10 times at 600 ℃, and/or (3) the thermal conductivity change of the material is less than or equal to 5% after the material is repeatedly used for more than 10 times at 600 ℃. More preferably, the composite material is made by the method of any one of claims 1 to 8.
In a third aspect, the present invention provides the use of a composite material produced by a process according to the first aspect of the invention or a composite material according to the second aspect of the invention in the manufacture of a composite component; preferably, the composite material member is selected from the group consisting of a plate-shaped member, a hemispherical member, a quasi-hemispherical member, a conical member and a profiled surface member.
Examples
The present invention is described in detail below with reference to specific examples, but the scope of the present invention is not limited to these examples. Reagents used in the examples such as tridecafluorooctyltrimethoxysilane, pentafluorophenyl trimethoxysilane, heptadecafluorodecyltrimethoxysilane, and methyl orthosilicate are commercially available from Technoluke technologies, Inc. of Beijing; the fiber mat preform is commercially available from Nanjing glass fiber research design institute.
Example 1
Dissolving tridecafluorooctyltrimethoxysilane, methyl orthosilicate, formic acid and deionized water in a molar ratio of 10:50:4.8:240 in 600 molar equivalents of ethanol solution, and stirring at room temperature for 12 h. The density is 0.1g/cm3Putting the quartz fiber felt preform into a mold, carrying out composite molding on the silica sol and the preform under the alkali catalysis condition (the pH value is controlled to be between 8 and 9) by adopting a vacuum pressing molding mode, ageing at room temperature for 36h and at the high temperature of 90 ℃ for 36h after gelling, carrying out acetone solvent replacement for 3 times after ageing, and then carrying out supercritical carbon dioxide drying to obtain the fiber reinforced silica aerogel composite material. The density of the prepared material is detected to be 0.25g/cm3The spherical heat shield can resist the temperature of 600 ℃, the room-temperature thermal conductivity is 0.021W/m.K (according to the standard GB/T10295-2008), the moisture absorption rate of the spherical heat shield after the spherical heat shield is repeatedly used at the temperature of 600 ℃ is 5.5% (according to the standard GB/T21655.1-2008), the repeated use performance of the material is obviously superior to that of the aerogel material subjected to common hydrophobic treatment, and the moisture absorption rate after the spherical heat shield is used at high temperature is far lower than that of the existing aerogel material.
Example 2
The procedure was carried out in substantially the same manner as in example 1 except that in step (1), tridecafluorooctyltrimethoxysilane was not added, but instead, methyl orthosilicate was used in place of tridecafluorooctyltrimethoxysilane, so that tridecafluorooctyltrimethoxysilane, methyl orthosilicate, formic acid, deionized water were dissolved in 600 molar equivalents of ethanol solution in a molar ratio of 0:60:4.8: 240; in addition, no surface modification was performed. As a result, the product is poor in hydrophobic effect, and the sample does not have the moisture-proof effect (according to the standard GB/T21655.1-2008). The inventor also observes the constant temperature and humidity examination moisture absorption rate of the composite sample after 600 ℃/3600s/10 times of use, and the result is shown in the following table 1.
Example 3
In substantially the same manner as in example 1, except thatPlacing the treated material in a closed container after being placed at room temperature, adding a catalytic amount of formic acid solution and pentafluorophenyl trimethoxy silane accounting for 5 mass percent of the total amount of the material, vacuumizing, performing hydrophobic treatment, wherein the treatment temperature is 50 ℃, the treatment time is 8 hours, and then drying in a vacuumizing manner to obtain the fiber reinforced silica aerogel composite material. The density of the obtained material is detected to be 0.24g/cm3The spherical heat shield can resist the temperature of 600 ℃, the room-temperature thermal conductivity is 0.022W/m.K (according to the standard GB/T10295-2008), the moisture absorption rate of the spherical heat shield after the spherical heat shield is repeatedly used at the temperature of 600 ℃ is 3.6% (according to the standard GB/T21655.1-2008), the repeated use performance of the material is obviously superior to that of the aerogel material subjected to common hydrophobic treatment, and the moisture absorption rate after the spherical heat shield is used at high temperature is far lower than that of the existing aerogel material.
Example 4
The procedure was carried out in substantially the same manner as in example 3 except that, after the supercritical drying and before being placed in a closed vessel after leaving at room temperature, the material was treated in a muffle furnace at 500 ℃ for 0.5 hour.
Example 5
The procedure was carried out in substantially the same manner as in example 4 except that heptadecafluorodecyltrimethoxysilane was used in place of tridecafluorooctyltrimethoxysilane, oxalic acid was used in place of formic acid, and 600 molar equivalents of ethanol solution was used and stirred at room temperature for 10 hours. The treatment was carried out in a muffle furnace at 500 ℃ for 1 h. The density of the obtained material is detected to be 0.24g/cm3The material can resist the temperature of 600 ℃, the room temperature thermal conductivity is 0.024W/m.K (according to the standard GB/T10295-2008), the moisture absorption rate of the conical heat shield after being reused at the temperature of 600 ℃ is less than 2% (according to the standard GB/T21655.1-2008), the material reusability is obviously superior to that of the aerogel material subjected to common hydrophobization treatment, and the moisture absorption rate after being used at high temperature is far less than that of the existing aerogel material.
Example 6
The procedure was carried out in substantially the same manner as in example 4, except that heptadecafluorodecyltrimethoxysilane, methyl orthosilicate, hydrochloric acid and deionized water were dissolved in 600 molar equivalents of ethanol solution in a molar ratio of 60:0:2.4:240, and the mixture was stirred at room temperature for 6 hours. Put into a muffle furnace at 450 DEG CLine treatment was 1.5 h. The density of the obtained material is detected to be 0.22g/cm3The spherical heat shield can resist the temperature of 600 ℃, the room temperature thermal conductivity is 0.021W/m.K (according to the standard GB/T10295-2008), the moisture absorption rate of the spherical heat shield after the spherical heat shield is repeatedly used at the temperature of 600 ℃ is less than 2% (according to the standard GB/T21655.1-2008), the repeated use performance of the material is obviously superior to that of the aerogel material subjected to common hydrophobic treatment, and the moisture absorption rate after the spherical heat shield is used at high temperature is far less than that of the existing aerogel material.
Example 7
The procedure is carried out in substantially the same manner as in example 6 except that tridecafluorooctyltrimethoxysilane is used in place of heptadecafluorodecyltrimethoxysilane. The density of the obtained material is detected to be 0.23g/cm3The material can resist the temperature of 600 ℃, the room temperature thermal conductivity is 0.023W/m.K (according to the standard GB/T10295-2008), the moisture absorption rate of the conical heat shield after the conical heat shield is repeatedly used at the temperature of 600 ℃ is less than 2% (according to the standard GB/T21655.1-2008), the repeated use performance of the material is obviously superior to that of the aerogel material subjected to common hydrophobic treatment, and the moisture absorption rate after the material is used at high temperature is far less than that of the existing aerogel material.
TABLE 1
Figure BDA0001899603620000101
Figure BDA0001899603620000111
Finally, it should be noted that: the present invention is not described in detail and is known to those skilled in the art, and the above embodiments are only used for illustrating the technical solution of the present invention and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit of the corresponding technical solutions of the embodiments of the present invention.

Claims (22)

1. A method for preparing a temperature-resistant, moisture-proof silica aerogel composite, comprising the steps of:
(1) preparing a silica sol by hydrolysis-polycondensation reaction with a silicon-containing coupling reagent in the presence of a catalytic amount of a first catalyst, and the silicon-containing coupling reagent comprises a fluorine-containing coupling agent;
(2) soaking a fiber reinforcement by using the silica sol in the presence of a catalytic amount of a second catalyst, and obtaining a hydrophobic fiber reinforced aerogel composite material through sol-gel, aging, solvent replacement and drying;
(3) carrying out surface activation treatment on the hydrophobic fiber reinforced aerogel composite material at high temperature to obtain a surface activated fiber reinforced aerogel composite material;
(4) carrying out hydrophobization treatment on the surface-activated fiber reinforced aerogel composite material by using a hydrophobization reagent, and drying to obtain a hydrophobization aerogel composite material;
wherein the activation temperature of the surface activation is 400-600 ℃, and the activation time is 0.5-1.5 h;
the treatment temperature of the hydrophobization treatment is 40-120 ℃, and the treatment time of the hydrophobization treatment is 6-72 hours.
2. The method according to claim 1, wherein the activation temperature of the surface activation is 450 to 550 ℃.
3. The method of claim 1, wherein the hydrophobizing treatment is performed in the presence of a catalytic amount of a third catalyst.
4. The method of claim 1, wherein the hydrophobization treatment is performed by fumigation or/and spraying under vacuum or atmospheric pressure.
5. The method according to any one of claims 1 to 4, characterized in that:
in step (1), the fluorine-containing coupling agent comprises a fluorine-containing silane coupling agent; and/or
In the step (4), the hydrophobizing agent is a fluorine-containing silane hydrophobizing agent.
6. The method of claim 5, wherein the fluorochemical silane coupling agent and/or the fluorochemical silane hydrophobizing agent is selected from the group consisting of formula R4-n-(Si)-(O-R’)nWherein n =1 to 3, and R is selected from the group consisting of a fluorine-containing alkyl group having 1 to 10 carbons, a fluorine-containing aryl group having 6 to 12 carbons, or a single fluorine atom, wherein the number of fluorine-containing atoms of the fluorine-containing alkyl group is 1 to 19, and the number of fluorine-containing atoms of the fluorine-containing aryl group is 1 to 10; O-R' is selected from the group consisting of alkoxy groups having 1 to 5 carbon atoms.
7. The method of claim 6, wherein the fluorochemical silane coupling agent and/or fluorochemical silane hydrophobizing agent is selected from the group consisting of tridecafluoroctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, or pentafluorophenyl trimethoxysilane.
8. The method according to claim 1 or 2, characterized in that:
the first catalyst is an acidic catalyst; and/or
The second catalyst is an acidic catalyst or a basic catalyst.
9. The method of claim 3, wherein:
the first catalyst is an acidic catalyst; and/or
The second catalyst is an acidic catalyst or a basic catalyst; and/or
The third catalyst is an acid catalyst.
10. The method of claim 9, wherein:
the first catalyst is one or more selected from the group consisting of oxalic acid, acetic acid, formic acid, and hydrochloric acid solution; and/or
In the case where the second catalyst is an acidic catalyst, the second catalyst is selected from one or more of the group consisting of oxalic acid, acetic acid, formic acid, and hydrochloric acid solution, and in the case where the second catalyst is a basic catalyst, the second catalyst is selected from one or more of the group consisting of ammonia, sodium hydroxide, and ammonium fluoride; and/or
The third catalyst is selected from one or more of the group consisting of trifluoroacetic acid, acetic acid, formic acid and hydrochloric acid.
11. The method of claim 10, wherein:
the concentration of the first catalyst is 0.01-0.1M; and/or
The concentration of the second catalyst is 0.01-0.1M; and/or
The concentration of the third catalyst is 0.01-0.1M.
12. The method of claim 10, wherein:
the molar ratio of the first catalyst to the silicon-containing coupling agent is 1: 20-10000; and/or
The molar ratio of the second catalyst to the silicon-containing coupling agent is 1: 20-10000; and/or
The molar ratio of the third catalyst to the hydrophobizing agent is 1: 5000-10000.
13. A method according to any one of claims 1 to 4, characterised in that the fibres in the fibre reinforcement are selected from one or more of the group consisting of basalt fibres, glass fibres, quartz fibres, mullite fibres or alumina fibres.
14. The method of claim 5, wherein the fibers in the fiber reinforcement are selected from one or more of the group consisting of basalt fibers, glass fibers, quartz fibers, mullite fibers, or alumina fibers.
15. The process of any one of claims 1 to 4, wherein the first catalyst is an acidic catalyst and the second catalyst is a basic catalyst.
16. The method of claim 3, wherein:
the first catalyst, the second catalyst, and the third catalyst are each independently an acidic catalyst.
17. The method of claim 5, wherein the fluorine-containing coupling agent further comprises an orthosilicate.
18. The method according to claim 17, wherein the molar ratio of the orthosilicate to the fluorine-containing silane coupling agent is 0 to 100: 1.
19. The method of claim 17, wherein the orthosilicate and the fluorine-containing silane coupling agent are stirred at room temperature for 6-24 hours before use.
20. A temperature and moisture resistant silica aerogel composite made according to the method of any of claims 1-19, comprising a fluorine-containing hydrophobic layer structure and having the following properties: (1) the heat conductivity at room temperature is less than or equal to 0.025W/(m.K); (2) the material has a moisture absorption rate of less than or equal to 2 percent after being repeatedly used for more than 10 times at 600 ℃; (3) the thermal conductivity change of the material is less than or equal to 5 percent after the material is repeatedly used for more than 10 times at 600 ℃.
21. Use of a composite material produced by the process of any one of claims 1 to 19 or the composite material of claim 20 in the manufacture of a composite component.
22. The use according to claim 21, wherein the composite material member is selected from the group consisting of a plate-shaped member, a hemispherical member, a quasi-hemispherical member, a conical member and a profiled surface member.
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