A reusable and packaged aerogel composite material under high temperature conditions and a preparation method thereof

Abstract

The present invention discloses a reusable, encapsulated aerogel composite material capable of being reused under high-temperature conditions and a method for preparing the same. The resulting aerogel composite material maintains excellent thermal insulation and waterproof and oil-resistant properties even after heat treatment at 650°C. After multiple 650°C heat treatments, its performance exhibits no significant degradation, extending the aerogel composite material's service life and significantly reducing surface dusting and shedding.

Description

Technical Field

[0001] The present invention belongs to the technical field of aerogel thermal insulation composite materials, and in particular relates to an aerogel composite material that can be reusable and packaged under high temperature conditions and a preparation method thereof. Background Art

[0002] Aerogel is a nanomaterial composed of nanoscale colloidal particles aggregated together to form a nanoporous network structure. It can be obtained through processes such as atmospheric drying, freeze-drying, or supercritical extraction. The goal is to evaporate the liquid in the wet gel and replace it with a gas component, while maintaining the three-dimensional porous nanomaterial in a gel-like state. Aerogel materials have low density, large specific surface area, high porosity, and exceptional thermal, optical, electrical, and acoustic properties, including high-temperature resistance, low thermal conductivity, low refractive index, and low sound propagation velocity. Aerogel is one of the world's lowest-density solid materials and has applications in aerospace, adsorbents, catalysts, and life sciences.

[0003] In the field of thermal insulation, the main factors affecting the service life of aerogel thermal insulation materials are the following two points: 1. The mechanical properties and temperature resistance of the aerogel itself are poor. After exceeding a certain threshold, the interface between the aerogel and the reinforcing phase fails, causing the thermal insulation performance of the aerogel thermal insulation material to drop rapidly; 2. The hydrophobic properties of the aerogel thermal insulation material fail, causing the aerogel to absorb water molecules in the air, shortening the service life of the aerogel thermal insulation material.

[0004] Without considering external damage and overheating, the service life of aerogel is closely related to its hydrophobic properties. Aerogel insulation materials have a special three-dimensional network structure with pores smaller than air molecules, which can absorb water molecules in the air. In addition, there are a large number of hydrophilic groups such as hydroxyl groups on the surface of aerogel insulation materials, which easily adsorb water molecules in the air. When aerogel insulation materials absorb a large number of water molecules, it will cause changes in its internal structure, such as the collapse of the pore structure and a sharp increase in the thermal conductivity coefficient, which will significantly reduce the thermal insulation performance. In addition, the absorption of water molecules by aerogel insulation materials may also cause other problems, such as corrosion and changes in surface structure, further affecting its thermal insulation performance and service life.

[0005] At present, in order to extend the storage period and service life of aerogel products, organic modifiers can be added to modify aerogel composite materials during the production process to make them have good hydrophobic properties, such as hexamethyldisilazane. However, the temperature resistance of organic groups is usually below 350°C, and the hydrophobic properties cannot be maintained below this temperature, which becomes the main factor hindering the repeated use of aerogels at high temperatures. At the same time, in applications in fields such as aerospace or new energy, there are usually some non-polar liquid substances (such as lubricating oils). Even if aerogel materials have good hydrophobicity, they will still absorb such non-polar liquid substances, resulting in a decrease in thermal insulation performance and inability to be reused for a long time.

[0006] In addition, inorganic (such as silica, alumina) aerogel materials are very brittle. During the storage, transportation, installation and use of inorganic aerogel products, a lot of dust will be generated. The falling silica and alumina particles will cause irreversible damage to the instruments and equipment in normal use, affecting the test results of the instruments or the normal operation of the equipment. Therefore, environmental friendliness needs to be further improved.

[0007] At present, aerogel composite materials prepared according to the preparation schemes disclosed in the art generally cannot maintain good waterproof and oil-proof properties at temperatures exceeding 350°C, can be reused, and reduce powder and dust loss. Summary of the Invention

[0008] To address the problems of existing aerogel composite materials in maintaining good water and oil resistance above 350°C, being unreusable, and shedding powder and dust, the present invention proposes a reusable and encapsulated aerogel composite material under high-temperature conditions and a preparation method. The resulting aerogel composite material maintains good thermal insulation after heat treatment at temperatures above 650°C, while also exhibiting excellent water and oil resistance. After multiple heat treatments at temperatures above 650°C, its performance shows no significant degradation, extending the lifespan of the aerogel composite material and significantly reducing the problem of powder and dust shedding on the aerogel surface.

[0009] The purpose of the present invention is achieved through the following technical solutions:

[0010] A method for preparing a reusable encapsulated aerogel composite material under high temperature conditions comprises the following steps:

[0011] S1, machining: machining the aerogel composite material to the set specifications and dimensions;

[0012] The aerogel composite material is selected from composite materials with a temperature resistance of 900°C or above;

[0013] S2. Pre-sewing: Using the aerogel composite material processed by S1 as the base material, wrap it with a lightweight, heat-resistant fiber cloth, and sew it with thread of the same material to obtain a pre-sewn aerogel sample;

[0014] The light and heat-resistant fiber cloth has a surface density of ≥0.3g / cm 2 , selected from specialty fiber cloth, including but not limited to glass fiber cloth, quartz fiber cloth, alumina fiber cloth or zirconia fiber cloth;

[0015] S3, pre-packaging: using the aerogel pre-sewn sample obtained in S2 as a substrate, selecting a ceramic powder material whose thermal expansion coefficient matches that of the lightweight, heat-resistant fiber cloth, and evenly coating the ceramic coating on the surface of the aerogel pre-sewn sample by a thermal spraying process to obtain an aerogel pre-packaged sample;

[0016] The ceramic powder material is selected from one of silicon oxide, aluminum oxide, zirconium oxide, silicon nitride, glass-ceramics, silicon boron oxynitride, and boron nitride;

[0017] The thickness of the ceramic coating is controlled to be 0.1 to 5 mm;

[0018] S4, sealing: The aerogel pre-packaged sample obtained in step S3 is coated with a sealing agent material on the pre-packaged sample through a coating process to perform a sealing treatment, and after curing, an aerogel composite material that can be reusable and packaged under high temperature conditions is obtained;

[0019] The sealing material is selected from one of microcrystalline wax system sealing materials, silicone resin system sealing materials, aluminum-containing polymer sealing materials or phosphorus-containing polymer sealing materials;

[0020] The obtained aerogel composite material that can be reusable and packaged under high temperature conditions has a thermal conductivity coefficient growth rate of 10-20% at room temperature and a thermal conductivity coefficient growth rate of 15-30% at a high temperature of 300°C.

[0021] The composite material was heat treated in a muffle furnace at 650°C for 2 hours, repeated 10 times, with a mass loss rate of less than 2.1% and a mass moisture absorption rate of less than 1%.

[0022] It has excellent dielectric resistance, with thermal conductivity of 0.032W / (m·K)-0.043W / (m·K) at room temperature and 0.058W / (m·K)-0.089W / (m·K) at 300℃.

[0023] In the present invention:

[0024] The machining process described in step S1 is to select an aerogel composite material as the substrate for mechanical processing. In order to ensure that the specifications and dimensions of the encapsulated aerogel composite material product meet the application requirements during the mechanical processing, the encapsulation material is no longer suitable for processing to avoid damage to the structure of the encapsulated sample. At the same time, it is necessary to chamfer the right-angled parts of the substrate to reduce the coating cracking caused by excessive stress and strain after the ceramic powder is sprayed on the right-angled parts of the sewn parts during the pre-packaging process and heated.

[0025] The composite material with a temperature resistance of above 900° C. described in step S1 is selected from one of high-temperature resistant silica aerogel, alumina aerogel or alumina-silicon oxide aerogel composite material, so as to avoid the temperature during the thermal spraying process causing the aerogel composite material structure to collapse or shrink.

[0026] In the pre-sewing described in step S2, the lightweight and heat-resistant fiber cloth used is mainly selected from special fiber cloth, including but not limited to glass fiber cloth, quartz fiber cloth, alumina fiber cloth and zirconia fiber cloth, etc. Its main advantages are high temperature resistance, chemical corrosion resistance, and good insulation. The surface of the aerogel material is prone to powdering and falling off, and the ceramic coating is difficult to spray directly and well bonded to the outer layer of the aerogel. It is easy to cause uneven force to cause the coating to crack and collapse. A layer of fiber cloth is sewn on the outside of the aerogel composite material. On the one hand, it can stabilize the shape of the aerogel product. On the other hand, the fiber cloth can be combined with the ceramic coating as a supporting structure to ensure that the composite material does not collapse, delaminate, crack, etc.

[0027] The surface density of the pre-sewn fiber cloth in step S2 should be ≥0.3g / cm 2 Fiber cloth with high surface density is denser and has better bonding effect with the sprayed ceramic material, which is beneficial to improving the density of the packaging layer. If the surface density of the fiber cloth is too small, the ceramic coating and the fiber cloth cannot be effectively combined into an integral structure, and are prone to cracking and collapse.

[0028] The pre-packaging described in step S3 uses a ceramic coating material that is a ceramic powder material, mainly including one or more system materials such as silicon oxide, aluminum oxide, zirconium oxide, silicon nitride, microcrystalline glass, silicon boron oxynitride, and boron nitride. Its main advantages are high temperature resistance, ablation resistance, and high density. The thermal expansion coefficient of the ceramic coating is well matched with the thermal expansion coefficient of aerogel materials such as silicon oxide and aluminum oxide and ceramic fiber cloth materials. It is not easy to crack and fall off due to the mismatch of expansion coefficients after heating. The performance of the ceramic powder material is better, and it is superior to a single powder material in terms of temperature resistance and density.

[0029] The pre-packaging described in step S3, wherein the thermal spraying process, the thickness of the thermally sprayed ceramic coating should be controlled at 0.1 to 5 mm, further, 0.2 to 1 mm. The function of the ceramic coating is to form a dense insulating layer to ensure that water and other media in the environment do not enter the substrate. The dense ceramic coating has a high thermal conductivity. When the thickness of the ceramic coating is too high, the overall thermal conductivity of the composite thermal insulation material will increase, thereby affecting the thermal insulation performance of the material; and when the thickness of the ceramic coating reaches a certain value, the waterproof effect of the insulating layer is not significantly improved. Excessive thickness of the ceramic coating also affects the overall density of the composite material. When the thickness of the ceramic coating is too thin, it is difficult to ensure the bonding effect between the ceramic coating and the fiber. On the other hand, when the thickness of the ceramic coating is too thin, the waterproof and oil-proof effect is reduced.

[0030] The sealing agent materials in step S4 mainly include microcrystalline wax system sealing materials, silicone resin system sealing materials, aluminum-containing polymer sealing materials, phosphorus-containing polymer sealing materials, etc. The main components of the composite material sealing agent include resin materials, glass fiber, curing agent and toughening agent, etc. Its main purpose is to improve the solid strength of the sealing agent, and it also has a certain improvement in the operating temperature. However, since the main components still contain resin organic matter, its maximum operating temperature is still difficult to reach above 350°C. Inorganic composite material sealing agents with relatively good temperature resistance are preferred, whose main components are mainly inorganic salts, cement-based materials, diatomaceous earth and calcium sulfate, etc., so as to ensure that the aerogel composite material maintains good waterproof and oil-proof properties in an environment above 350°C.

[0031] The present invention also relates to an aerogel composite material that can be reusably packaged under high temperature conditions, which is obtained by using the above-mentioned method for preparing an aerogel composite material that can be reusably packaged under high temperature conditions. The obtained aerogel composite material that can be reusably packaged under high temperature conditions has a thermal conductivity coefficient growth rate of 10-20% at room temperature and a thermal conductivity coefficient growth rate of 15-30% at 300°C.

[0032] The composite material was heat treated in a muffle furnace at 650°C for 2 hours, repeated 10 times, with a mass loss rate of less than 2.1% and a mass moisture absorption rate of less than 1%.

[0033] It has excellent dielectric resistance, with thermal conductivity of 0.032W / (m·K)-0.043W / (m·K) at room temperature and 0.058W / (m·K)-0.089W / (m·K) at 300℃.

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] 1. The present invention discloses a method for preparing a reusable, encapsulated aerogel composite material under high-temperature conditions. The thermal spraying process uses a ceramic powder material whose thermal expansion coefficient matches that of the fiber cloth. This allows the ceramic coating to bond with the fiber cloth on the aerogel substrate to form a high-strength, high-density ceramic coating. Furthermore, it prevents cracking and shedding of the coating caused by a mismatch in the expansion coefficients of the composite material after heating.

[0036] 2. The present invention discloses a method for preparing a reusable, encapsulated aerogel composite material capable of high-temperature use. The thickness of the ceramic coating is controlled, as it influences key performance indicators such as thermal insulation and density. After pre-encapsulation, the surface of the material forms a high-strength, dense fiber-ceramic composite coating that bonds closely to the aerogel substrate, effectively preventing the aerogel composite from shedding. A sealing material smaller than ceramic particles is used to further densify the ceramic coating. The sealing material is then applied to the pre-encapsulated sample by brushing, spraying, or dipping, and cured to produce the encapsulated aerogel composite product.

[0037] 3. The aerogel composite material that can be reusably packaged under high temperature conditions described in the present invention has a dense ceramic coating after being treated with a ceramic coating and a sealing agent, which can effectively isolate water molecules in the air and prevent the internal pore structure of the aerogel substrate from collapsing under high temperature conditions, thereby greatly improving the service life of the aerogel material. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a process flow chart of a method for preparing a reusable encapsulated aerogel composite material under high temperature conditions according to the present invention;

[0039] Figure 2 This is a graph showing the surface hydrophobicity of an aerogel composite material that can be reusably packaged under high temperature conditions and prepared in Example 5 of the present invention after being heat-treated 10 times in a muffle furnace at 650° C. for 2 hours;

[0040] Figure 3 This is a diagram showing a medium resistance test of a reusable encapsulated aerogel composite material prepared under high temperature conditions in Example 5 of the present invention (left: water; right: lubricating oil);

[0041] Figure 4 This is a diagram showing a dust adhesion test on the surface of an aerogel composite material that can be reusably packaged under high temperature conditions, prepared in Example 5 of the present invention (left: substrate; right: aerogel composite material that can be reusably packaged under high temperature conditions);

[0042] Figure 5 This is a graph showing the surface hydrophobic effect of the sample prepared in Comparative Example 2 after 10 heat treatments in a muffle furnace at 650°C for 2h. DETAILED DESCRIPTION

[0043] The present invention is further described in detail below by way of examples, but these examples should not be considered as limiting the present invention.

[0044] In the Examples and Comparative Examples:

[0045] The mass moisture absorption rate data is measured in accordance with GB / T 5480-2008.

[0046] Room-temperature thermal conductivity data were measured in accordance with GB / T 10295-2008.

[0047] The high-temperature thermal conductivity at 300°C was measured according to GB / T 10295-2008.

[0048] Example 1:

[0049] A method for preparing a reusable encapsulated aerogel composite material under high temperature conditions comprises the following steps:

[0050] 1) Machining: machining a piece of silica aerogel thermal insulation composite material into an aerogel thermal insulation flat plate with a specification of 200×200×20 mm;

[0051] 2) Sewing: Use 0.1 mm thick quartz fiber cloth and quartz thread to sew the aerogel flat plate obtained in the previous step with a stitch spacing of 20 mm, hem it, and cut off the excess thread ends;

[0052] 3) Spraying: Using a plasma spraying process, set the spraying power to 80 kW, the spraying rate to 5 kg / h, and the spraying angle to 60°, spray the silicon oxide powder material evenly on the surface of the sewn sample prepared in step 2), controlling the coating thickness to be between 0.5 mm. After cooling, polish the surface with sandpaper;

[0053] 4) Sealing: The aluminum-containing polymer sealing agent is evenly applied to the pre-packaged sample in step 3), and placed in a 100° C. oven for 2 hours for curing to obtain an aerogel composite material that can be reusably packaged under high temperature conditions.

[0054] The obtained aerogel composite material that can be reusable and packaged under high temperature conditions has the following properties:

[0055] The reusable packaged aerogel composite material was placed in a muffle furnace and heated and cooled as the furnace rose and fell, heat treated at 650°C for 2 hours, and repeated 10 times; the mass loss rate was 2.1%, the mass moisture absorption rate was 0.9%, and it had excellent medium resistance, thermal conductivity of 0.043 W / (m·K) at room temperature, and thermal conductivity of 0.085 W / (m·K) at 300°C.

[0056] Example 2:

[0057] A method for preparing a reusable encapsulated aerogel composite material under high temperature conditions comprises the following steps:

[0058] 1) Machining: machining a piece of alumina aerogel thermal insulation composite material into an aerogel thermal insulation flat plate with a specification of 200×200×20 mm;

[0059] 2) Sewing: Use 0.1 mm thick quartz fiber cloth and quartz thread to sew the aerogel flat plate obtained in the previous step with a stitch spacing of 20 mm, hem it, and cut off the excess thread ends;

[0060] 3) Spraying: Using a plasma spraying process, set the spraying power to 80 kW, the spraying rate to 5 kg / h, and the spraying angle to 60°, spray the silicon oxide powder material evenly on the surface of the sewn sample prepared in step 2), controlling the coating thickness to be between 0.5 mm. After cooling, polish the surface with sandpaper;

[0061] 4) Sealing: The aluminum-containing polymer sealing agent is evenly applied to the pre-packaged sample in step 3), and placed in a 100° C. oven for 2 hours for curing to obtain an aerogel composite material that can be reusably packaged under high temperature conditions.

[0062] The obtained aerogel composite material that can be reusable and packaged under high temperature conditions has the following properties:

[0063] The reusable packaged aerogel composite material was heat-treated 10 times in a muffle furnace at 650°C for 2 hours; the mass loss rate was 1.9%, the mass moisture absorption rate was 0.8%, and it had excellent medium resistance, a thermal conductivity of 0.032 W / (m·K) at room temperature, and a thermal conductivity of 0.058 W / (m·K) at 300°C.

[0064] Example 3:

[0065] A method for preparing a reusable encapsulated aerogel composite material under high temperature conditions comprises the following steps:

[0066] 1) Machining: machining a piece of silica aerogel thermal insulation composite material into an aerogel thermal insulation flat plate with a specification of 200×200×20 mm;

[0067] 2) Sewing: Use 0.1 mm thick quartz fiber cloth and quartz thread to sew the aerogel flat plate obtained in the previous step with a stitch spacing of 20 mm, hem it, and cut off the excess thread ends;

[0068] 3) Spraying: Using a plasma spraying process with a spray power of 80 kW, a spray rate of 5 kg / h, and a spray angle of 60°, the silicon oxide / aluminum oxide mixed powder material was evenly sprayed onto the surface of the sewn sample prepared in step 2), with the coating thickness controlled to be between 0.5 mm. After cooling, the surface was polished with sandpaper;

[0069] 4) Sealing: The aluminum-containing polymer sealing agent is evenly applied to the pre-packaged sample in step 3), and placed in a 100° C. oven for 2 hours for curing to obtain an aerogel composite material that can be reusably packaged under high temperature conditions.

[0070] The obtained aerogel composite material that can be reusable and packaged under high temperature conditions has the following properties:

[0071] The reusable packaged aerogel composite material was heat-treated 10 times in a muffle furnace at 650°C for 2 hours; the mass loss rate was 1.2%, the mass moisture absorption rate was 0.5%, and it had excellent medium resistance, a thermal conductivity of 0.041 W / (m·K) at room temperature, and a thermal conductivity of 0.087 W / (m·K) at 300°C.

[0072] Example 4:

[0073] A method for preparing a reusable encapsulated aerogel composite material under high temperature conditions comprises the following steps:

[0074] 5) Machining: machining a piece of silica aerogel thermal insulation composite material into an aerogel thermal insulation flat plate with a specification of 200×200×20 mm;

[0075] 6) Sewing: Use 0.1 mm thick alumina fiber cloth and alumina thread to sew the aerogel flat plate obtained in the previous step with a stitch pitch of 20 mm, hem it, and cut off the excess thread ends;

[0076] 7) Spraying: Using a plasma spraying process, set the spraying power to 80 kW, the spraying rate to 5 kg / h, and the spraying angle to 60°, spray the silicon oxide powder material evenly on the surface of the sewn sample in step 2), controlling the coating thickness to be between 0.5 mm. After cooling, polish the surface with sandpaper;

[0077] 8) Sealing: The aluminum-containing polymer sealing agent is evenly applied to the pre-packaged sample in step 3), and placed in a 100° C. oven for 2 hours for curing to obtain an aerogel composite material that can be reusably packaged under high temperature conditions.

[0078] The obtained aerogel composite material that can be reusable and packaged under high temperature conditions has the following properties:

[0079] The reusable packaged aerogel composite material was heat-treated 10 times in a muffle furnace at 650°C for 2 hours; the mass loss rate was 1.7%, the mass moisture absorption rate was 0.8%, and it had excellent medium resistance, a thermal conductivity of 0.040 W / (m·K) at room temperature, and a thermal conductivity of 0.087 W / (m·K) at 300°C.

[0080] Example 5:

[0081] A method for preparing a reusable encapsulated aerogel composite material under high temperature conditions comprises the following steps:

[0082] 9) Machining: machining a piece of silica aerogel thermal insulation composite material into an aerogel thermal insulation flat plate with a specification of 200×200×20 mm;

[0083] 10) Sewing: Use 0.1 mm thick quartz fiber cloth and quartz thread to sew the aerogel flat plate obtained in the previous step with a stitch spacing of 20 mm, hem it, and cut off the excess thread ends;

[0084] 11) Spraying: Using a plasma spraying process, set the spraying power to 80 kW, the spraying rate to 5 kg / h, and the spraying angle to 60°, spray the silicon oxide powder material evenly on the surface of the sewn sample prepared in step 2), controlling the coating thickness to be between 1 mm. After cooling, polish the surface with sandpaper;

[0085] 12) Sealing: The aluminum-containing polymer sealing agent is evenly applied to the pre-packaged sample in step 3), and placed in a 100° C. oven for 2 hours for curing to obtain an aerogel composite material that can be reusably packaged under high temperature conditions.

[0086] The obtained aerogel composite material that can be reusable and packaged under high temperature conditions has the following properties:

[0087] The reusable packaged aerogel composite material was heat-treated 10 times in a muffle furnace at 650°C for 2 hours; the mass loss rate was 0.5%, the mass moisture absorption rate was 0.7%, and it had excellent medium resistance, a thermal conductivity of 0.043 W / (m·K) at room temperature, and a thermal conductivity of 0.089 W / (m·K) at 300°C.

[0088] like Figure 2 As shown in FIG, a graph showing the surface hydrophobic effect of a reusable encapsulated aerogel composite material prepared in Example 5 under high temperature conditions after being heat-treated 10 times in a muffle furnace at 650° C. for 2 h; Figure 2 As shown, a hydrophobicity test was conducted on a reusable and packaged aerogel composite material obtained in Example 5 under high temperature conditions. After multiple heat treatments at 650°C, its hydrophobicity did not significantly attenuate, thereby improving the service life of the aerogel composite material.

[0089] like Figure 3 As shown, a reusable encapsulated aerogel composite material obtained in Example 5 under high temperature conditions was subjected to a medium resistance test. After being immersed in water and lubricating oil for 72 hours, the mass increase rate was ≤3%, and the mass moisture absorption rate was ≤3%. After multiple heat treatments at 650°C, its performance did not significantly attenuate, which extended the service life of the aerogel composite material and greatly reduced the problem of powder and dust falling on the aerogel surface.

[0090] like Figure 4 As shown, an adhesion test was performed on the surface of a reusable packaged aerogel composite material obtained in Example 5 under high temperature conditions, and the ash on the surface of the reusable packaged aerogel composite material was significantly reduced.

[0091] Comparative Example 1:

[0092] The difference between Comparative Example 1 and Example 1 is that a silicone resin sealing agent is used instead of an aluminum-containing polymer sealing agent for sealing. The other steps are the same as those of Example 1, including the following steps:

[0093] 1) Machining: machining a piece of silica aerogel thermal insulation composite material into an aerogel thermal insulation flat plate with a specification of 200×200×20 mm;

[0094] 2) Sewing: Use 0.1 mm thick quartz fiber cloth and quartz thread to sew the aerogel flat plate obtained in the previous step with a stitch spacing of 20 mm, hem it, and cut off the excess thread ends;

[0095] 3) Spraying: Using a plasma spraying process, set the spraying power to 80kW, the spraying rate to 5kg / h, and the spraying angle to 60°, the silicon oxide powder material was evenly sprayed on the surface of the sewn sample in step 2), and the coating thickness was controlled to be between 0.5mm and 1mm. After cooling, the surface was polished with sandpaper;

[0096] 4) Sealing: The silicone resin sealing agent is evenly applied to the pre-packaged sample in step 3), and placed in a 100° C. oven for 2 hours for curing to obtain an aerogel composite material that can be reusable and packaged under high temperature conditions.

[0097] The obtained aerogel composite material that can be reusable and packaged under high temperature conditions has the following properties:

[0098] The reusable packaged aerogel composite material was heat-treated 10 times in a muffle furnace at 650°C for 2 hours; the mass loss rate was 2.0%, the mass moisture absorption rate was 13.7%, and it had excellent medium resistance, a thermal conductivity of 0.042 W / (m·K) at room temperature, and a thermal conductivity of 0.086 W / (m·K) at 300°C.

[0099] The results show that:

[0100] The silicone resin sealing agent used in Comparative Example 1 has relatively poor temperature resistance. After ten heat treatments in a muffle furnace at 650°C for 2 hours, the sealing agent coating is destroyed by the high temperature, resulting in a higher mass moisture absorption rate, indicating that the surface waterproofing effect has failed.

[0101] Comparative Example 2:

[0102] The difference between Comparative Example 2 and Example 1 is that quartz fiber cloth is not used for the overlocking treatment. The other steps are the same as Example 1, including the following steps:

[0103] 1) Machining: machining a piece of silica aerogel thermal insulation composite material into an aerogel thermal insulation flat plate with a specification of 200×200×20 mm;

[0104] 2) Spraying: Using a plasma spraying process, setting the spraying power to 80 kW, the spraying rate to 5 kg / h, and the spraying angle to 60°, the silicon oxide powder material was evenly sprayed on the surface of the aerogel insulation plate in step 1, and the thickness of the coating was controlled to be between 0.5 mm. After cooling, the surface was polished with sandpaper;

[0105] 3) Sealing: The aluminum-containing polymer sealing agent is evenly applied to the pre-packaged sample in step 3), and placed in a 100° C. oven for 2 hours for curing to obtain an aerogel composite material that can be reusably packaged under high temperature conditions.

[0106] The obtained aerogel composite material that can be reusable and packaged under high temperature conditions has the following properties:

[0107] The reusable packaged aerogel composite material was heat-treated 10 times in a muffle furnace at 650°C for 2 hours; the mass loss rate was 24.2%, the mass moisture absorption rate was 32.3%, the thermal conductivity at room temperature was 0.041 W / (m·K), and the thermal conductivity at 300°C was 0.082 W / (m·K).

[0108] Figure 5 This is a surface diagram of the reusable packaged aerogel composite material of Comparative Example 2 after heat treatment 10 times in a muffle furnace at 650°C for 2 hours.

[0109] The results show that:

[0110] The sample of Comparative Example 2 that was not treated with fiber cloth wrapping had a significantly increased mass moisture absorption rate after 10 heat treatments in a muffle furnace at 650°C for 2 hours. At the same time, combined with the pictures, the ceramic coating of the sample of Comparative Example 2 fell off.

[0111] Table 1: Comparison of properties of reusable encapsulated aerogel composites prepared by different processes after ten heat treatments in a muffle furnace at 650°C for 2 hours:

[0112]

[0113] The results show that:

[0114] 1. The aerogel composite material prepared by the present invention can be reusable and packaged under high temperature conditions. After heat treatment at a high temperature of 650°C, it still maintains a good thermal insulation effect. Taking the silica aerogel composite material obtained in Example 1 as an example, the thermal conductivity of the aerogel thermal insulation composite material product at room temperature is ≤0.037W / (m·K), and the thermal conductivity at 300°C is ≤0.071W / (m·K). Using this as a substrate, a reusable and packaged aerogel composite material with a specification of 200×200×20mm is prepared. The thermal conductivity at room temperature is ≤0.043W / (m·K), and the thermal conductivity at 300°C is ≤0.087W / (m·K). The thermal conductivity at room temperature is increased by 16.21%, and the thermal conductivity at 300°C is increased by 19.72%, but it can still maintain a good thermal insulation effect and has excellent waterproof and oil-proof properties. Figure 3 As shown in the figure, the inventors conducted a medium resistance test. After immersing in water and lubricating oil for 72 hours, the mass increase rate was ≤3%, and the mass moisture absorption rate was ≤3%. After multiple heat treatments at 650°C, its performance did not significantly attenuate, which improved the service life of the aerogel composite material and greatly reduced the problem of powder and dust falling on the aerogel surface. Figure 4 As shown, the inventors conducted an adhesion test on the aerogel surface, and the dust on the surface of the reusable packaged aerogel composite material was significantly reduced.

[0115] 2. By comparing Example 1 with Comparative Example 1, the silicone resin sealant is an organic sealant with relatively poor temperature resistance. After ten heat treatments at 650°C and 2h in a muffle furnace, the sealant coating is destroyed by high temperature, resulting in a higher mass moisture absorption rate, indicating that the surface waterproofing effect has failed. The aluminum-containing polymer sealant is an inorganic sealant. After ten heat treatments at 650°C and 2h in a muffle furnace, the mass moisture absorption rate remains at ≤3%, indicating that the inorganic sealant has better temperature resistance.

[0116] 3. By comparing Example 1 with Comparative Example 2, the sample that was not treated with fiber cloth wrapping had a significantly higher mass moisture absorption rate after 10 heat treatments in a muffle furnace at 650°C for 2 hours. At the same time, combined with the pictures, the ceramic coating of the sample in Comparative Example 2 fell off, indicating that the quartz fiber cloth can enhance the strength of the ceramic coating and will not cause the coating to fall off due to high temperature.

[0117] The above are only preferred embodiments of the present invention. The protection scope of the present invention is not limited to the above embodiments. Various process solutions that have no substantial difference from the concept of the present invention are within the protection scope of the present invention.

Claims

1. A method for preparing a reusable encapsulated aerogel composite material under high temperature conditions, characterized by: The following steps are involved: S1, machining: machining the aerogel composite material to the set specifications and dimensions; The aerogel composite material is selected from composite materials with a temperature resistance of 900°C or above; S2. Pre-sewing: Using the aerogel composite material processed by S1 as the base material, wrap it with a lightweight, heat-resistant fiber cloth, and sew it with thread of the same material to obtain a pre-sewn aerogel sample; The light and heat-resistant fiber cloth has a surface density of ≥0.3g / cm 2 , selected from specialty fiber cloth, including but not limited to glass fiber cloth, quartz fiber cloth, alumina fiber cloth or zirconia fiber cloth; S3, pre-packaging: using the aerogel pre-sewn sample obtained in S2 as a substrate, selecting a ceramic powder material whose thermal expansion coefficient matches that of the lightweight, heat-resistant fiber cloth, and evenly coating the ceramic coating on the surface of the aerogel pre-sewn sample by a thermal spraying process to obtain an aerogel pre-packaged sample; The ceramic powder material is selected from one of silicon oxide, aluminum oxide, zirconium oxide, silicon nitride, glass-ceramics, silicon boron oxynitride, and boron nitride; The thickness of the ceramic coating is controlled to be 0.1 to 5 mm; S4, sealing: The aerogel pre-packaged sample obtained in step S3 is coated with a sealing agent material on the pre-packaged sample through a coating process to perform a sealing treatment, and after curing, an aerogel composite material that can be reusable and packaged under high temperature conditions is obtained; The sealing material is selected from one of microcrystalline wax system sealing materials, silicone resin system sealing materials, aluminum-containing polymer sealing materials or phosphorus-containing polymer sealing materials; The obtained aerogel composite material which can be reusable and packaged under high temperature conditions has a thermal conductivity coefficient growth rate of 10-20% at room temperature and a thermal conductivity coefficient growth rate of 15-30% at a high temperature of 300°C. The composite material was heat treated in a muffle furnace at 650°C for 2 hours, repeated 10 times, with a mass loss rate of less than 2.1% and a mass moisture absorption rate of less than 1%. It has excellent medium resistance, with thermal conductivity of 0.032-0.043W / (m·K) at room temperature and 0.058-0.087W / (m·K) at 300℃.

2. The method for preparing a reusable and packaged aerogel composite material under high temperature conditions according to claim 1, characterized in that: In the pre-packaging described in step S3, the thermal spraying process is performed, and the thickness of the thermally sprayed ceramic coating is controlled to be 0.2 to 1 mm.

3. An aerogel composite material that can be reusable and packaged under high temperature conditions, characterized in that: The composite material is obtained by the method for preparing a reusable encapsulated aerogel composite material under high temperature conditions as claimed in claim 1 or 2, wherein the thermal conductivity of the composite material increases by 10-20% at room temperature and by 15-30% at a high temperature of 300°C; The composite material was heat treated in a muffle furnace at 650°C for 2 hours, repeated 10 times, with a mass loss rate of less than 2.1% and a mass moisture absorption rate of less than 1%. It has excellent medium resistance, with thermal conductivity of 0.032-0.043W / (m·K) at room temperature and 0.058-0.087W / (m·K) at 300℃.

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