CN107954687A - A kind of aerosil with ultralow thermal conductivity and preparation method thereof - Google Patents
A kind of aerosil with ultralow thermal conductivity and preparation method thereof Download PDFInfo
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- CN107954687A CN107954687A CN201711248883.8A CN201711248883A CN107954687A CN 107954687 A CN107954687 A CN 107954687A CN 201711248883 A CN201711248883 A CN 201711248883A CN 107954687 A CN107954687 A CN 107954687A
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- thermal conductivity
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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
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
- B01J13/0091—Preparation of aerogels, e.g. xerogels
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/113—Silicon oxides; Hydrates thereof
- C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
- C01B33/14—Colloidal silica, e.g. dispersions, gels, sols
- C01B33/157—After-treatment of gels
- C01B33/158—Purification; Drying; Dehydrating
- C01B33/1585—Dehydration into aerogels
-
- 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
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Dispersion Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Inorganic Chemistry (AREA)
- Silicon Compounds (AREA)
Abstract
The invention discloses a kind of aerosil with ultralow thermal conductivity and preparation method thereof.Using ethyl orthosilicate it is silicon source in the preparation method of aeroge, graphite is opacifier.The preparation method of the present invention by adjust the volume ratio of ethyl orthosilicate, absolute ethyl alcohol and water, graphite mass fraction, control ageing time, obtain the aerosil with ultralow thermal conductivity, obtained aeroge thermal conductivity in 0.02W/ (mK) below.Al is used using the aeroge ratio obtained by preparation method of the present invention2O3More than 48.72% is reduced as the aeroge thermal conductivity obtained by opacifier, the obtained aerosil with ultralow thermal conductivity can use in the dual-use field such as aerospace, high temperature catalyst support, building energy conservation as high efficiency heat insulation material.
Description
Technical field
The invention belongs to gel preparation field, and in particular to prepared by a kind of aerosil with ultralow thermal conductivity
Method.
Background technology
Aerosil is a kind of amorphous solid-state material, have high voidage, high-specific surface area, lower thermal conductivity it is excellent
Point, it has potential application value in fields such as mechanics, acoustics, electricity, calorifics and optics.
It is reported that the thermal conductivity of pure silicon dioxide aeroge at normal temperatures can reach 0.02W/ (mK).However, due to
3~8 μm in infrared band of pure silicon dioxide aeroge is to pass through, and causes the radiant heat conductanc of aeroge with the rise of temperature
And significantly increase.For this reason, being directed to this problem, substantial amounts of correlative study is come into being, such as：The introducing of opacifier, passes through drop
Low emissivity heat transfer and further reduce the thermal conductivity of aeroge.However, research, which has found that while, introduces aeroge after opacifier
Thermal conductivity reduces, for example adds Al2O3The thermal conductivity of aeroge is down to 0.023W/ (mK) during opacifier, but still higher than pure
The thermal conductivity 0.020W/ (mK) of silica；At the same time high density and opacifier doping number to also limit these compound
Application of the aeroge in terms of aerospace.At this moment, the carbon material of low-density causes the attention of scientist.For example, carbon black is made
For opacifier be added in aerosil reduce aeroge radiation thermal conduction, but carbon black it is unstable at high temperature and
Limit the extensive use of its composite aerogel.
The content of the invention
For the above-mentioned existing prior art, the invention solves aerosil thermal conductivity height and addition opacifier
The unstable technical problem of aeroge afterwards.
In order to achieve the above object, the technical solution adopted in the present invention is：There is provided it is a kind of with ultralow thermal conductivity two
Silica aerogel preparation method.Preparation method concretely comprises the following steps：
(1) it is 1 according to volume ratio by ethyl orthosilicate, absolute ethyl alcohol and water:2:1~1:5:1 mixing, is stirred at normal temperatures
80~100min；
(2) pH value of resulting solution in step (1) is adjusted to 3~4 with the hydrochloric acid of 0.2mol/L, places water at room temperature
24~36h is solved, obtains precursor solution；
(3) aquadag is scattered in absolute ethyl alcohol, it is 0.2~0.6wt% graphite solution to obtain mass fraction；Then will
Gained graphite solution is 1 according to volume ratio with gained precursor solution in step (2):3~4 are uniformly mixed；
(4) pH value of gained mixed solution in step (3) is adjusted to 6~7 with the weak aqua ammonia of 0.2mol/L, gel aging
2~3 days, obtain graphite-silica wet gel；
(5) graphite-silica wet gel obtained by step (4) is sequentially placed into progress solvent friendship in absolute ethyl alcohol and acetone
Change；
(6) supercritical drying is carried out to the graphite-silica wet gel for completing exchange of solvent, obtains graphite-silica
Aeroge.
Based on the above technical solutions, the present invention can also be improved as follows.
Further, silester, the volume ratio of second alcohol and water are 1 in step (1):4:1.
Further, hydrolysis time is 24h in step (2).
Further, aquadag ultrasonic disperse is in absolute ethyl alcohol in step (3), and jitter time is 5~10min, gained
The mass fraction of graphite solution is 0.4wt%；Product is than being 1 when graphite solution is mixed with precursor solution:4, when mixing, first stirs
10min, then with ultrasonic disperse 25min.
Further, gel ageing time is 2 days in step (4).
Further, the detailed process of step (5) is that graphite-silica wet gel is first placed three in absolute ethyl alcohol
My god, then it is placed in acetone and places three days again；A fresh solution is replaced daily.
Further, supercritical drying carries out in supercritical carbon dioxide extracting instrument in step (6), drying temperature 40
DEG C, dry pressure is 12MPa, drying time 24h.
The beneficial effects of the invention are as follows：Graphite-aerosil heat obtained by preparation method using the present invention
In 0.02W/ (mK) below, and the radiant heat conductanc of aeroge will not increase conductance with the rise of temperature.In addition, gas
Hardness, dimensional stability, the fracture toughness of gel improve, meanwhile, the water imbibition of aeroge does not have significant changes, is reducing heat
While conductance, stability of material increases substantially.
After ethyl orthosilicate, the mixing of second alcohol and water, 90min is stirred at normal temperatures, component can not only be sufficiently mixed, and respectively
The internal structure of a component will not be also destroyed, and ensure that the stability of resulting materials.With salt acid for adjusting pH, it is not introduced
His impurity, will not have an impact the thermal conductivity of final aeroge；PH value is adjusted to acidity, and ethyl orthosilicate can be more preferable
Hydrolysis, is met the precursor solution of requirement.
During aquadag is distributed to ethanol solution, aid dispersion is carried out using ultrasonic wave, aquadag is not only
Can be with rapid dispersion into ethanol solution, and disperse more uniform；Graphite solution is same with super after being mixed with precursor solution
Sound wave is disperseed, both mix more uniformly with fully, last obtained graphite-aerosil quality is more equal
Even, material property is more stablized.
The pH of solution is adjusted with weak aqua ammonia, will not equally introduce impurity, and ammonia is volatile, in drying process below
It can evaporate into air, aeroge will not be impacted.Solution ph is easier to occur old under subacidity or neutrallty condition
Change, aging is more thorough, and obtained graphite-aerosil structure is more stablized.
Due to having the not volatile solvents such as water in graphite-silica wet gel for being obtained after aging, later into
Row is possible to dry and is not thorough when dry, so as to influence the performance of aeroge；Therefore with volatile ethanol and acetone successively
Exchange of solvent is carried out to graphite-silica wet gel, ethanol first comes out the exchange of moisture in wet gel, and then acetone is by second
Alcohol exchanges, and acetone is a kind of readily volatilized solvent, and in the drying process, acetone all volatilizees, to the performance of aeroge
Will not radiography sound.
It is dried in carbon dioxide abstraction instrument, it is not only dry thorough, but also the internal structure of aeroge will not be destroyed,
It ensure that the stability of product.
The present invention also protects a kind of aerosil with ultralow thermal conductivity, aeroge gas using the present invention
Gel process for preparing prepare, its superconductivity in 0.02W/ (mK) below.
Embodiment
In the embodiment of the present invention, there is provided a kind of aerosil preparation method with ultralow thermal conductivity.Should
Method is 1 according to volume ratio first by ethyl orthosilicate, absolute ethyl alcohol and water:2:1~1:5:1 ratio uniform mixing, then
80~100min is stirred at normal temperatures.The internal structure of component is not destroyed in order to be sufficiently mixed component, when stirring stirs
Speed is 50~100r/min.After the completion of stirring, 10min is stood, is then adjusted the pH value of solution with the hydrochloric acid of 0.2mol/L
To between 3~4,24~36h is placed under room temperature, the ethyl orthosilicate in solution is fully hydrolyzed, obtains precursor solution.
During precursor solution is configured, while configure graphite solution.Graphite solution preparation method is：Weigh certain
The aquadag of amount, is distributed it in absolute ethyl alcohol using ultrasonic wave, the mass fraction of graphite in final gained graphite solution
For 0.2~0.6wt%, ultrasonic disperse time 5min.After graphite solution allocation is good, it is mixed with precursor solution, during mixing,
The volume ratio of graphite solution and precursor solution is 1:3~4.10min, then ultrasonic disperse 25min are first stirred after mixing, is obtained uniformly
Solution.
The dilute ammonia solution of 0.2mol/L is added dropwise into gained homogeneous solution, between the pH to 6~7 for adjusting homogeneous solution,
Then 2~3 days are stood at room temperature, makes its abundant aging, obtain graphite-silica wet gel.Graphite-silica will first be obtained
Wet gel, which is positioned in ethanol solution, carries out exchange of solvent, and the time is 2~3 days, in order to ensure that solvent is fully exchanged,
The ethanol solution that will more renew daily；After 3 days, graphite-silica wet gel is taken out from ethanol solution,
It is then placed into acetone and continues solution exchange, swap time is 3 days, equally, in order to ensure that solvent is fully exchanged,
The acetone that will more renew daily.
After the completion of exchange of solvent, graphite-silica wet gel is put into supercritical carbon dioxide extracting instrument and is surpassed
Critical drying.When dry, drying temperature is 40 DEG C, drying pressure 12MPa, and drying time is 24h~48h.Walked by dry
It is less than 0.02W/ (mK) after rapid up to aerosil, the thermal conductivity of the gel at normal temperatures.
With reference to embodiment, the present invention is further illustrated.
(1) embodiment one:
The volume for measuring ethyl orthosilicate, absolute ethyl alcohol and water is respectively 6.7ml, 26.7ml, 6.7ml, is stirred after mixing
90min, adds between the pH to 3~4 of hydrochloric acid solution adjusting solution of 130 μ l 0.2mol/L, is positioned in room temperature and hydrolyzes 24h
Obtain precursor solution；The aquadag for weighing 0.0010g is scattered in the ethanol solution of 10ml, ultrasonic disperse 5min, is added
In above-mentioned precursor solution, ultrasonic disperse 25min after stir about 10min；Resulting solution stirring is added into 3.4ml after five minutes
The weak aqua ammonia of 0.2mol/L, gel aging two days；The wet gel of gained is first placed on progress volume friendship in absolute ethyl alcohol, acetone
Change, replace fresh absolute ethyl alcohol and acetone daily, each 3 days；The good wet gel of exchange of solvent is put into supercritical extract instrument, in T
=40 DEG C, through CO under P=12MPa experiment conditions2Aerosil is obtained after supercritical drying 24h.
(2) embodiment two to five:
The aerosil with ultralow thermal conductivity is prepared using the method identical with embodiment one.Difference
The volume ratio that is silester, absolute ethyl alcohol and water is different, hydrolysis time is different, graphite mass fraction is different, aging when
Between it is different.
(3) comparative example one:
By ethyl orthosilicate:Absolute ethyl alcohol:Hydromassage that ratio 1:10:9 sequentially add in container, are stirred in 390r/min
Under, hydrochloric acid alcoholic solution is added, it is 2 to adjust pH value, stirs 11 hours, adds nanometer Al2O3, it is uniformly mixed, ultrasonic disperse 5 divides
Clock, adds ammonium hydroxide alcoholic solution, and it is 8 to adjust pH value, continue stirring 1 it is small when, pour into mould, seal at room temperature and stand two
My god, silica dioxide gel is formed, atomization process is carried out, obtains silica gel microspheres, particle diameter is at 1-300 μm；The hydrochloric acid
Alcoholic solution is hydrochloric acid:Ethanol volume ratio=1:49, ammonium hydroxide alcoholic solution is ammonium hydroxide:Ethanol volume ratio=1:49.
Interpretation of result：
Observe upper table to understand, utilize the preparation method of the present invention, the thermal conductivity of obtained graphite-aerosil
Below 0.020.Especially work as silester:Ethanol:The volume ratio of water is 1:4:1, hydrolysis time 24h, the matter of graphite
Amount fraction is 0.4wt%, and when ageing time is 2 days, the thermal conductivity of obtained graphite-aerosil is minimum, is
0.017W/(m·K).Al is used using the thermal conductivity ratio of the aerosil obtained by preparation method of the present invention2O3It is made
The thermal conductivity of dioxide composite silica aerogel reduce more than 48.72%, can be widely applied to aerospace, high temperature catalyst
Carrier, building energy conservation etc. by the use of and civil field used as high efficiency heat insulation material.
Claims (8)
1. a kind of aerosil preparation method with ultralow thermal conductivity, it is characterized in that, comprise the following steps：
(1) it is 1 according to volume ratio by ethyl orthosilicate, absolute ethyl alcohol and water:2:1~1:5:1 mixing, stirring 80 at normal temperatures~
100min；
(2) pH value of resulting solution in step (1) is adjusted to 3~4 with the hydrochloric acid of 0.2mol/L, placement hydrolyzes 24 at room temperature
~36h, obtains precursor solution；
(3) aquadag is scattered in absolute ethyl alcohol, it is 0.2~0.6wt% graphite solution to obtain mass fraction；Then by gained
Graphite solution is 1 according to volume ratio with gained precursor solution in step (2):3~4 are uniformly mixed；
(4) pH value of gained mixed solution in step (3) is adjusted to 6~7 with the weak aqua ammonia of 0.2mol/L, gel aging 2~3
My god, obtain graphite-silica wet gel；
(5) graphite-silica wet gel obtained by step (4) is sequentially placed into absolute ethyl alcohol and acetone and carries out exchange of solvent；
(6) supercritical drying is carried out to the graphite-silica wet gel for completing exchange of solvent, obtains graphite-silica airsetting
Glue.
2. the aerosil preparation method according to claim 1 with ultralow thermal conductivity, it is characterized in that：Step
(1) silester, the volume ratio of second alcohol and water are 1 in:4:1.
3. the aerosil preparation method according to claim 1 with ultralow thermal conductivity, it is characterized in that：Step
(2) hydrolysis time is 24h in.
4. the aerosil preparation method according to claim 1 with ultralow thermal conductivity, it is characterized in that：Step
(3) for aquadag ultrasonic disperse in absolute ethyl alcohol, jitter time is 5~10min in, and the mass fraction of gained graphite solution is
0.4wt%；Product is than being 1 when graphite solution is mixed with precursor solution:4, when mixing, first stirs 10min, then uses ultrasonic disperse
25min。
5. the aerosil preparation method according to claim 1 with ultralow thermal conductivity, it is characterized in that：Step
(4) gel ageing time is 2 days in.
6. the aerosil preparation method according to claim 1 with ultralow thermal conductivity, it is characterized in that：Step
(5) detailed process is that graphite-silica wet gel is first placed three days in absolute ethyl alcohol, is then placed in again in acetone
Place three days；A fresh solution is replaced daily.
7. the aerosil preparation method according to claim 1 with ultralow thermal conductivity, it is characterized in that：Step
(6) supercritical drying carries out in supercritical carbon dioxide extracting instrument in, and drying temperature is 40 DEG C, and dry pressure is 12MPa, is done
The dry time is 24h.
8. the silica airsetting with ultralow thermal conductivity is made in the preparation method as described in any one in claim 1~7
Glue.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201711248883.8A CN107954687A (en) | 2017-12-01 | 2017-12-01 | A kind of aerosil with ultralow thermal conductivity and preparation method thereof |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201711248883.8A CN107954687A (en) | 2017-12-01 | 2017-12-01 | A kind of aerosil with ultralow thermal conductivity and preparation method thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114620736A (en) * | 2021-12-15 | 2022-06-14 | 航天海鹰(镇江)特种材料有限公司 | Compression-controllable SiO2Aerogel composite material preparation method |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105797680A (en) * | 2016-04-05 | 2016-07-27 | 黑龙江科技大学 | Preparation method of reduced graphite oxide-attapulgite composite aerogel |
| CN107304052A (en) * | 2016-04-22 | 2017-10-31 | 北京化工大学 | A kind of preparation method of graphene oxide doped aerosil |
-
2017
- 2017-12-01 CN CN201711248883.8A patent/CN107954687A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105797680A (en) * | 2016-04-05 | 2016-07-27 | 黑龙江科技大学 | Preparation method of reduced graphite oxide-attapulgite composite aerogel |
| CN107304052A (en) * | 2016-04-22 | 2017-10-31 | 北京化工大学 | A kind of preparation method of graphene oxide doped aerosil |
Non-Patent Citations (1)
| Title |
|---|
| QINFENG XU ET.AL: "Facile fabrication of graphite-doped silica aerogels with ultralow thermal conductivity by precise control", 《JOURNAL OF NON-CRYSTALLINE SOLIDS》 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114620736A (en) * | 2021-12-15 | 2022-06-14 | 航天海鹰(镇江)特种材料有限公司 | Compression-controllable SiO2Aerogel composite material preparation method |
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