CN114773092A - Method for improving mechanical property and heat-insulating property of silicon carbide nanowire aerogel through oxidation treatment - Google Patents
Method for improving mechanical property and heat-insulating property of silicon carbide nanowire aerogel through oxidation treatment Download PDFInfo
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- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 title claims abstract description 139
- 239000004964 aerogel Substances 0.000 title claims abstract description 133
- 230000003647 oxidation Effects 0.000 title claims abstract description 42
- 238000007254 oxidation reaction Methods 0.000 title claims abstract description 42
- 238000000034 method Methods 0.000 title claims abstract description 33
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 20
- 229910052814 silicon oxide Inorganic materials 0.000 claims abstract description 16
- 238000009413 insulation Methods 0.000 claims description 11
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- 238000007906 compression Methods 0.000 claims 1
- 229910010271 silicon carbide Inorganic materials 0.000 abstract description 20
- 238000002360 preparation method Methods 0.000 abstract description 4
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- 229920000049 Carbon (fiber) Polymers 0.000 description 5
- 229910000831 Steel Inorganic materials 0.000 description 5
- 239000004917 carbon fiber Substances 0.000 description 5
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- KPUWHANPEXNPJT-UHFFFAOYSA-N disiloxane Chemical class [SiH3]O[SiH3] KPUWHANPEXNPJT-UHFFFAOYSA-N 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 229920000642 polymer Polymers 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 239000000969 carrier Substances 0.000 description 2
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- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical compound [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 2
- 229910052682 stishovite Inorganic materials 0.000 description 2
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- 229910021641 deionized water Inorganic materials 0.000 description 1
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- JJQZDUKDJDQPMQ-UHFFFAOYSA-N dimethoxy(dimethyl)silane Chemical compound CO[Si](C)(C)OC JJQZDUKDJDQPMQ-UHFFFAOYSA-N 0.000 description 1
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- BFXIKLCIZHOAAZ-UHFFFAOYSA-N methyltrimethoxysilane Chemical compound CO[Si](C)(OC)OC BFXIKLCIZHOAAZ-UHFFFAOYSA-N 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
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- C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
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Abstract
The invention discloses a method for improving the mechanical property and the heat-insulating property of a silicon carbide nanowire aerogel through oxidation treatment, and belongs to the technical field of preparation of silicon carbide aerogel. The thickness of an oxide layer of the silicon carbide nanowire aerogel is regulated and controlled through reasonable oxidation treatment, the microstructure of the silicon carbide nanowire is changed by means of the oxide layer, the number of nodes in a silicon carbide nanowire network is increased, and meanwhile, the strength and the elasticity are improved; the intrinsic thermal conductivity of silicon oxide is far lower than that of silicon carbide, and the content of silicon oxide is increased, so that the thermal conductivity of the oxidized silicon carbide nanowire aerogel is reduced; and a silicon carbide/silicon oxide interface is introduced to enhance phonon scattering, so that the mechanical property and the heat-insulating property of the silicon carbide nanowire aerogel are improved simultaneously. According to the invention, the mechanical property and the heat-insulating property of the silicon carbide nanowire aerogel are improved through simple oxidation treatment, and the practical application of the silicon carbide nanowire aerogel is promoted.
Description
Technical Field
The invention belongs to the technical field of preparation of silicon carbide nanowire aerogels, and particularly relates to a method for improving the mechanical property and the heat-insulating property of a silicon carbide nanowire aerogel through oxidation treatment.
Background
The aerogel is a nano-scale porous light material constructed by a network framework with open pores, has a plurality of unexpected excellent characteristics, such as ultralow density, high porosity, low thermal conductivity and good chemical stability, attracts the attention of researchers, and has an extraordinarily attractive application prospect under severe service conditions such as high-temperature heat insulation, catalyst carriers, filters and the like, particularly under high-temperature and aerobic environments. Aerogels can be classified into carbon-based aerogels, polymer-based aerogels, and ceramic-based aerogels, depending on the composition. Among them, carbon-based aerogels and polymer-based aerogels are easily damaged in a high-temperature aerobic environment due to poor high-temperature stability of their constituent elements (carbon materials, polymers). The ceramic-based aerogel has good thermal stability and chemical stability, so that the ceramic-based aerogel becomes one of ideal candidate materials in high-temperature aerobic environments such as high-temperature heat insulation materials, catalyst carriers, filters and the like. Conventional ceramic-based aerogel materials, such as Silica (SiO)2) Aerogel, alumina (Al)2O3) Aerogel, usually by nano ceramic particle necklace form link, intensity is very low, often need in the practical application to carry on the complex use with the fibre, in addition, because the intrinsic fragility of the pottery, the application of traditional ceramic aerogel has received the very big restriction. For example pure SiO2The aerogel is formed by amorphous SiO in the interior at a temperature of over 600 DEG C2Sintering of the particles occurs with severe volume shrinkage, resulting in SiO2Aerogels are difficult to apply in high temperature environments. Al (Al)2O3The aerogel can generate crystal form transformation at 1000 ℃, and the transformation from gamma form to alpha form can generate obvious volume shrinkage, thereby causing the rapid reduction of volume stability and greatly limiting Al2O3Further application of the aerogel.
The silicon carbide nanowire aerogel is a novel ceramic aerogel, and a three-dimensional network structure is formed by mutually lapping, winding and self-assembling one-dimensional silicon carbide nanowires. The silicon carbide nanowire aerogel has the advantages that the silicon carbide nanowire aerogel not only has high-temperature stability and chemical stability of a silicon carbide ceramic body, but also is flexible due to the one-dimensional nanowires, so that the silicon carbide nanowire aerogel has good elastic recovery performance, excellent high-temperature stability and fire resistance and low thermal conductivity, and the problems of high brittleness and poor thermal stability of the traditional ceramic material are solved. However, because the silicon carbide nanowires in the silicon carbide nanowire aerogel are lapped together by van der waals force, the strength and the elastic modulus are low, and the mechanical property is poor. In addition, the thermal conductivity of the silicon carbide nanowire aerogel rapidly increases with an increase in ambient temperature, resulting in deterioration of thermal insulation properties.
Based on the above, considering reliable and efficient service in a high-temperature aerobic environment, the mechanical properties and the heat-insulating properties of the silicon carbide nanowire aerogel need to be further improved. At present, the mainstream means for improving the mechanical property of the silicon carbide aerogel material is to prepare the silicon carbide aerogel material into a composite aerogel with multiple components so as to improve the mechanical property, and the purpose of improving the heat insulation property is achieved by reducing the porosity, reducing the density of the material, reducing the heat conductivity and the like.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a method for improving the mechanical property and the heat-insulating property of the silicon carbide nanowire aerogel through oxidation treatment, which has simple process and low requirement on equipment and can simultaneously improve the mechanical property and the heat-insulating property of the silicon carbide nanowire aerogel.
In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:
the invention discloses a method for improving the mechanical property and the heat-insulating property of a silicon carbide nanowire aerogel through oxidation.
Preferably, the high-temperature oxidation treatment temperature is 900-1200 ℃, and the treatment time is 0.5-1.6 h.
Preferably, the high temperature oxidation treatment is performed in a high temperature box-type resistance furnace.
Preferably, the diameter of the silicon carbide nanowire aerogel used is 50nm to 300 nm.
Preferably, the thickness of the silicon oxide layer is 10nm to 160 nm.
Preferably, the mechanical property and the heat insulation property of the silicon carbide nanowire aerogel can be regulated and controlled by changing the high-temperature oxidation temperature or the treatment time.
Preferably, the elastic modulus of the treated silicon carbide nanowire aerogel is improved from 49.4kPa to 68.6 kPa-265.0 kPa.
Preferably, the stress of the treated silicon carbide nanowire aerogel at 40% compressive strain is increased from 21.7kPa to 33.2 kPa-78.5 kPa.
Preferably, the rebound rate of the treated silicon carbide nanowire aerogel is improved from 51.9% to 54.8% -63.5%.
Preferably, the thermal conductivity of the treated silicon carbide nanowire aerogel is 39.1 mW-m-1·K-1Reducing the power to 27.7-37.4 mW.m-1·K-1。
Compared with the prior art, the invention has the following beneficial effects:
according to the method for improving the mechanical property and the heat-insulating property of the silicon carbide nanowire aerogel through oxidation treatment, the mechanical property and the heat-insulating property of the silicon carbide nanowire aerogel are improved by improving the oxidation degree of the silicon carbide nanowires, because the higher the oxidation degree of the silicon carbide nanowire aerogel is, the thicker the silicon oxide layer of the silicon carbide nanowires inside is, the easier the oxide layer flows, and the silicon carbide nanowires are bonded together, so that the strength is structurally improved, and the silicon carbide nanowires are prevented from slipping and deforming, so that the elastic modulus, the strength and the rebound resilience of the silicon carbide nanowire aerogel after being oxidized are improved. The silicon oxide generated by oxidation is an amorphous substance, and the intrinsic thermal conductivity of the silicon oxide is low; meanwhile, phonon scattering is increased by an interface between an oxidation layer and silicon carbide introduced by oxidation, so that the thermal conductivity of the oxidized silicon carbide nanowire aerogel is reduced, and the heat insulation performance is improved. The method has the advantages of simple oxidation treatment mode, simple required equipment and process, and suitability for greatly improving the mechanical property and the heat insulation property of the silicon carbide nanowire aerogel in the actual production process.
Furthermore, after the silicon carbide nanowire aerogel is treated by the method, the elastic modulus of the silicon carbide nanowire aerogel is increased by 38.9-436.4 percent and is within the range of 68.6 kPa-265.0 kPa; the stress of the silicon carbide nanowire aerogel is increased by 53.9% -261.8% when the silicon carbide nanowire aerogel bears 40% of compressive strain, and is within the range of 33.2 kPa-78.5 kPa; the rebound rate of the silicon carbide nanowire aerogel is increased by 5.6-22.4% when the silicon carbide nanowire aerogel bears 40% of compressive strain, and is within the range of 54.8-63.5%; the thermal conductivity of the silicon carbide nano-wire aerogel is reduced by 4.3 to 41.2 percent and is reduced to 27.7 mW.m-1·K-1～37.4mW·m-1·K-1Within the range.
Drawings
FIG. 1 is an SEM image of a silicon carbide nanowire aerogel;
FIG. 2 shows diameter distribution statistics (1000) of silicon carbide nanowires contained in a silicon carbide nanowire aerogel;
FIG. 3 is a compressive stress-strain curve of a silicon carbide nanowire aerogel that has not been subjected to an oxidation treatment;
FIG. 4 is a compressive stress-strain curve of the silicon carbide nanowire aerogel of example 1 after being oxidized at 1000 ℃ for 0.5 h;
FIG. 5 is a compressive stress-strain curve of the silicon carbide nanowire aerogel in example 2 after being oxidized at 1000 ℃ for 1 h;
FIG. 6 is a compressive stress-strain curve of the silicon carbide nanowire aerogel in example 3 after being oxidized at 1000 ℃ for 8 h;
FIG. 7 is a compressive stress-strain curve of the silicon carbide nanowire aerogel in example 4 after being oxidized at 1000 ℃ for 16 h;
fig. 8 is a graph of thermal conductivity after oxidation at 1000 ℃ for 0.5h, 1h, 8h, and 16h without oxidation treatment and for the silicon carbide nanowire aerogels of examples 1-4.
Detailed Description
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The invention is described in further detail below with reference to the accompanying drawings:
the method for improving the mechanical property and the heat-insulating property of the silicon carbide nanowire aerogel disclosed by the invention realizes the improvement of the property of the silicon carbide nanowire aerogel by controlling the thickness range of the oxide layer only through oxidation treatment. The silicon oxide layer is formed on the surface of the silicon carbide nanowire through high-temperature oxidation treatment, so that the lap joint between the nanowires in the silicon carbide nanowire aerogel can be strengthened, and the silicon oxide layer plays a role of a binder to bind the silicon carbide nanowire, so that the number of nodes in a nanowire framework is increased, and the strength and elasticity of the silicon carbide nanowire network are improved at the same time; in addition, a silicon carbide/silicon oxide interface is introduced, the thickness of a silicon oxide layer is increased, the thermal conductivity of the silicon carbide nanowire aerogel is reduced, and the mechanical property and the heat-insulating property of the silicon carbide nanowire aerogel are synergistically improved.
The thickness of an oxide layer of the silicon carbide nanowire aerogel is regulated and controlled through reasonable oxidation treatment, the microstructure of the silicon carbide nanowire is changed by means of the oxide layer, the number of nodes in a silicon carbide nanowire network is increased, and meanwhile, the strength and the elasticity are improved; the intrinsic thermal conductivity of silicon oxide is far lower than that of silicon carbide, and the content of silicon oxide is increased, so that the thermal conductivity of the oxidized silicon carbide nanowire aerogel is reduced; and a silicon carbide/silicon oxide interface is introduced to enhance phonon scattering, so that the mechanical property and the heat-insulating property of the silicon carbide nanowire aerogel are improved simultaneously.
The silicon carbide nanowire aerogel adopted by the invention is prepared according to the method disclosed by the Chinese invention patent CN109627006B, and a microscopic SEM image of the silicon carbide nanowire aerogel is shown in figure 1. Referring to fig. 2, statistics of the diameter distribution of the silicon carbide nanowires contained in the silicon carbide nanowire aerogel are shown, and the number of the statistics is 1000.
The initial diameter of the silicon carbide nanowires contained in the silicon carbide nanowire aerogel is distributed between 50nm and 300nm, and the thickness of an oxidation layer of the oxidized silicon carbide nanowire aerogel is 10nm to 160 nm.
The temperature range of the high-temperature oxidation treatment is as follows: 900-1200 ℃; the oxidation time ranges from 0.5h to 16 h.
Example 1
In this embodiment, the silicon carbide nanowire aerogel is oxidized at 1000 ℃ for 0.5h, and the oxidized properties are as follows:
1) the elastic modulus of the silicon carbide nanowire aerogel oxidized at 1000 ℃ for 0.5h is increased from 49.4kPa to 68.6kPa, which is increased by 38.9%;
2) the stress of the silicon carbide nanowire aerogel oxidized at 1000 ℃ for 0.5h is increased from 21.7kPa to 33.2kPa and is increased by 53.0 percent when the silicon carbide nanowire aerogel bears 40 percent of compressive strain;
3) the silicon carbide nanowire aerogel oxidized at 1000 ℃ for 0.5h has the rebound rate increased from 51.9% to 54.8% when bearing 40% of compressive strain, and is increased by 5.6%;
4) the thermal conductivity of the silicon carbide nanowire aerogel oxidized for 0.5h at 1000 ℃ is 39.1 mW.m-1·K-1Reduced to 37.4 mW.m-1·K-1The reduction is 4.3%.
Example 2
In the embodiment, the silicon carbide nanowire aerogel is oxidized for 1 hour at 1000 ℃, and the performance after oxidation is as follows:
1) the elastic modulus of the silicon carbide nanowire aerogel oxidized at 1000 ℃ for 1h is increased from 49.4kPa to 76.8kPa, and is increased by 55.5%;
2) the stress of the silicon carbide nanowire aerogel oxidized for 1 hour at 1000 ℃ is increased from 21.7kPa to 39.6kPa when the silicon carbide nanowire aerogel bears 40% of compressive strain, and is increased by 8.2%;
3) the silicon carbide nanowire aerogel oxidized at 1000 ℃ for 1h has the rebound rate increased from 51.9% to 57.5% when bearing 40% compressive strain, and is increased by 10.8%;
4) the thermal conductivity of the silicon carbide nanowire aerogel oxidized for 1h at 1000 ℃ is 39.1 mW.m-1·K-1Reduced to 35.1 mW.m-1·K-1The reduction is 10.2%.
Example 3
In this embodiment, the silicon carbide nanowire aerogel is oxidized at 1000 ℃ for 8 hours, and the oxidized properties are as follows:
1) the elastic modulus of the silicon carbide nanowire aerogel oxidized for 8 hours at 1000 ℃ is increased from 49.4kPa to 235.4kPa, and is increased by 376.5%;
2) the stress of the silicon carbide nanowire aerogel oxidized for 8 hours at 1000 ℃ is increased from 21.7kPa to 47.8kPa when the silicon carbide nanowire aerogel bears 40% of compressive strain, and is increased by 120.3%;
3) the silicon carbide nanowire aerogel oxidized at 1000 ℃ for 8 hours has the resilience rate increased from 51.9% to 66.5% when the silicon carbide nanowire aerogel bears 40% of compressive strain, and the resilience rate is increased by 28.1%;
4) silicon carbide nanowire gas oxidized for 8 hours at 1000 DEG CThe thermal conductivity of the gel is 39.1 mW.m-1·K-1Reducing the temperature to 27.8 mW.m-1·K-1And the reduction is 28.9 percent.
Example 4
In this embodiment, the silicon carbide nanowire aerogel is oxidized at 1000 ℃ for 16h, and the oxidized properties are as follows:
1) the elastic modulus of the silicon carbide nanowire aerogel oxidized for 16 hours at 1000 ℃ is increased from 49.40kPa to 265.0kPa, which is increased by 436.4%;
2) the stress of the silicon carbide nanowire aerogel oxidized at 1000 ℃ for 16h is increased from 21.7kPa to 78.5kPa and is increased by 261.8 percent when the silicon carbide nanowire aerogel bears 40 percent of compressive strain;
3) the silicon carbide nanowire aerogel oxidized at 1000 ℃ for 16h has the rebound rate increased from 51.9% to 63.5% when bearing 40% compressive strain, and is increased by 22.4%;
4) the thermal conductivity of the silicon carbide nanowire aerogel oxidized for 16 hours at 1000 ℃ is 39.1 mW.m-1·K-1Reduced to 27.7 mW.m-1·K-1The reduction is 29.2%.
Comparative example 1
The silicon carbide nanowire aerogel which is not treated by the method disclosed by the invention is prepared according to the method disclosed by the Chinese patent CN109627006B, and the specific preparation steps of the silicon carbide nanowire aerogel treated by the method disclosed by the invention are as follows: the preparation method disclosed by the Chinese invention patent CN109627006B comprises the following specific steps:
1) preparing siloxane sol by using four raw materials of dimethyl dimethoxy silane, methyl trimethoxy silane, deionized water and absolute ethyl alcohol according to a mass ratio of 2:0.5:5: 3;
2) adding carbon fibers into siloxane sol according to a certain proportion, wherein the mass ratio of the carbon fibers to the siloxane sol is 1:160, uniformly dispersing the carbon fibers into the siloxane sol by a mechanical stirring method, wherein the stirring time is 10min, and the rotating speed of a mechanical stirrer is 1000 r/min. (ii) a
3) Adopting a vacuum filtration method to enable the chopped carbon fibers dispersed in the sol to be mutually lapped into a block body with a three-dimensional structure;
4) applying a pressure of 10kPa to the block;
5) heating to curing temperature (80 deg.C) in air, and holding for 6 hr;
6) heating to 1550 ℃ in argon with the pressure of 0.25MPa, carrying out heat preservation treatment for 3h, and cracking the xerogel to generate silicon carbide nanowires;
7) cooling to room temperature along with the furnace, heating to 700 ℃ at the heating rate of 1 ℃/min, carrying out heat preservation treatment for 3h, and oxidizing in the air to remove the carbon fiber framework to obtain the silicon carbide nanowire aerogel.
Referring to fig. 3, the compressive stress-strain curves of silicon carbide nanowire aerogels untreated by the method of the present invention are shown as follows: the stress when it was subjected to 40% compressive strain was 21.7kPa, the elastic modulus was 49.4kPa, the spring back ratio was 51.9%, and the thermal conductivity was 39.1 mW.m-1·K-1。
Referring to fig. 4, a compressive stress-strain curve of the silicon carbide nanowire aerogel treated by the present invention in example 1 is shown. As can be seen from the figure, the elastic modulus of the alloy is increased to 68.6kPa after being oxidized at 1000 ℃ for 0.5h, and is increased by 38.9 percent compared with that before being oxidized; the stress of the steel is increased to 33.2kPa when the steel bears 40% of compressive strain, and is increased by 53.0%; the rebound rate is increased to 54.8 percent and is improved by 5.6 percent;
referring to fig. 5, a compressive stress-strain curve of the silicon carbide nanowire aerogel treated by the present invention in example 2 is shown. As can be seen from the figure, the elastic modulus of the alloy is increased to 76.8kPa after being oxidized for 1h at 1000 ℃, and is increased by 55.5 percent compared with that before being oxidized; the stress of the steel plate bearing 40% of compressive strain is increased to 39.6kPa, which is increased by 8.2%; the rebound resilience is increased to 57.5 percent and is improved by 10.8 percent;
referring to fig. 6, a compressive stress-strain curve of the silicon carbide nanowire aerogel treated by the present invention in example 3 is shown. As can be seen from the figure, the elastic modulus of the alloy is increased to 235.4kPa after being oxidized for 8 hours at 1000 ℃, and is increased by 376.5 percent compared with that before being oxidized; the stress of the steel is increased to 47.8kPa when the steel bears 40% of compressive strain, and the stress is increased by 120.3%; the rebound resilience is increased to 66.5 percent and is improved by 28.1 percent;
referring to fig. 7, a compressive stress-strain curve of the silicon carbide nanowire aerogel treated by the present invention in example 4 is shown. As can be seen from the figure, the elastic modulus of the alloy is increased to 265.0kPa after being oxidized for 16h at 1000 ℃, and is increased by 436.4 percent compared with that before being oxidized; the stress of the alloy is increased to 78.5kPa and increased by 261.8 percent when the alloy bears 40 percent of compressive strain; the rebound resilience is increased to 63.5 percent and is increased by 22.4 percent;
referring to fig. 8, the thermal conductivity change of the silicon carbide nanowire aerogels treated by the present invention in examples 1-4 is shown. As can be seen from the figure, the thermal conductivity of the material is 39.1 mW.m after being oxidized for 0.5h at 1000 DEG C-1·K-1Reduce to 37.4 mW.m-1·K-1The reduction is 4.3%; oxidizing at 1000 deg.C for 1 hr, and having thermal conductivity of 39.1 mW.m-1·K-1Reduce to 35.1 mW.m-1·K-1The reduction is 10.2%; oxidized at 1000 ℃ for 8h, and the thermal conductivity is 39.1 mW.m-1·K-1Reducing the temperature to 27.8 mW.m-1·K-1And the reduction is 28.9 percent. Oxidized at 1000 ℃ for 16h, and the thermal conductivity is 39.1 mW.m-1·K-1Reduced to 27.7 mW.m-1·K-1And the reduction is 29.2 percent.
The above contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention should not be limited thereby, and any modification made on the basis of the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.
Claims (10)
1. A method for improving the mechanical property and the heat-insulating property of a silicon carbide nanowire aerogel through oxidation is characterized in that a silicon oxide layer is formed on the surface of the silicon carbide nanowire aerogel through high-temperature oxidation treatment, so that the strength, the compression resilience and the heat-insulating property of the silicon carbide nanowire aerogel are improved.
2. The method for improving the mechanical property and the heat-insulating property of the silicon carbide nanowire aerogel through oxidation according to claim 1, wherein the high-temperature oxidation treatment temperature is 900-1200 ℃, and the treatment time is 0.5-1.6 h.
3. The method for improving the mechanical property and the thermal insulation property of the silicon carbide nanowire aerogel through oxidation according to claim 1, wherein the high-temperature oxidation treatment is performed in a high-temperature box-type resistance furnace.
4. The method for improving the mechanical property and the heat-insulating property of the silicon carbide nanowire aerogel through oxidation according to claim 1, wherein the diameter of the silicon carbide nanowire aerogel is 50nm to 300 nm.
5. The method for improving the mechanical property and the heat-insulating property of the silicon carbide nanowire aerogel through oxidation according to claim 1, wherein the thickness of the silicon oxide layer is 10nm to 160 nm.
6. The method for improving the mechanical property and the heat-insulating property of the silicon carbide nanowire aerogel through oxidation according to claim 1, wherein the mechanical property and the heat-insulating property of the silicon carbide nanowire aerogel can be controlled by changing the high-temperature oxidation temperature or the treatment time.
7. The method for improving the mechanical property and the heat insulation property of the silicon carbide nanowire aerogel through oxidation according to any one of claims 1 to 6, wherein the elastic modulus of the treated silicon carbide nanowire aerogel is increased from 49.4kPa to 68.6kPa to 265.0 kPa.
8. The method for improving the mechanical property and the heat insulation property of the silicon carbide nanowire aerogel through oxidation according to any one of claims 1 to 6, wherein the stress corresponding to 40% of the compressive strain of the treated silicon carbide nanowire aerogel is increased from 21.7kPa to 33.2kPa to 78.5 kPa.
9. The method for improving the mechanical property and the heat insulation property of the silicon carbide nanowire aerogel through oxidation according to any one of claims 1 to 6, wherein the rebound rate of the treated silicon carbide nanowire aerogel is improved from 51.9% to 54.8% -63.5%.
10. The method for improving the mechanical property and the heat insulation property of the silicon carbide nanowire aerogel through oxidation according to any one of claims 1 to 6, wherein the thermal conductivity of the treated silicon carbide nanowire aerogel is 39.1 mW-m-1·K-1Reducing the power to 27.7-37.4 mW/m-1·K-1。
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