High-strength phenolic aerogel nested thermal tile composite material and preparation method thereof

Abstract

The application belongs to the technical field of high-temperature-resistant heat-insulating materials, and discloses a high-strength phenolic aerogel nested heat-insulating tile composite material and a preparation method thereof; when the material is prepared, first, an epoxy silane coupling agent is added into an ethanol aqueous solution to catalyze hydrolysis, a silane hydrolysis solution obtained is mixed with a phenolic resin solution and a curing agent to prepare a silane coupling agent modified phenolic resin solution, the tile is vacuum impregnated with the resin solution to obtain an intermediate; then, methyltrimethoxysilane and tetraethyl orthosilicate are added into an ethanol aqueous solution to catalyze hydrolysis, aluminum isopropoxide and acetylacetone are added into an ethanol aqueous solution to catalyze hydrolysis, a silicon source hydrolysis solution and an aluminum source hydrolysis solution are obtained respectively, the two are mixed with the phenolic resin solution and the curing agent to prepare a silicon-aluminum modified phenolic resin solution, and the intermediate is vacuum impregnated with the resin solution to obtain the composite material. The application realizes twice glue injection impregnation of the heat-insulating tile by using different modified phenolic resins, so that the material has the characteristics of efficient heat insulation, high strength and self-hydrophobicity.

Description

Technical Field

[0001] This invention belongs to the technical field of high-temperature resistant thermal insulation materials, specifically relating to a high-strength phenolic aerogel nested thermal insulation tile composite material and its preparation method. Background Technology

[0002] Fibrous rigid thermal insulation tiles, due to their low density, low thermal conductivity, and excellent high-temperature resistance, have become a core thermal protection material for large-area thermal protection systems in aerospace vehicles. They are typically made by impregnating and bonding short-cut ceramic fibers (such as quartz fibers and alumina fibers) with silica sol and then sintering at high temperatures. However, this type of material still faces several challenges in practical engineering applications, specifically in the following aspects: Firstly, the heat insulation tile has a porous structure, with interconnected internal pores forming a continuous network of channels. Some channels extend to the outer surface of the tile, creating open pores. The pore size is mainly distributed in the range of 1–200 µm, providing a wide channel for gas convection heat transfer within the pores. Under medium- and high-temperature service conditions, the gas convection heat transfer within the pores is significantly enhanced, creating thermal short-circuit paths. This leads to a substantial decrease in overall heat insulation efficiency, making it difficult to meet the stringent requirements of aerospace vehicles for high-efficiency thermal protection.

[0003] Secondly, the mechanical properties of heat-insulating tiles are constrained by their microscopic sintering structure, resulting in inherent defects such as low strength and high brittleness. During the high-temperature sintering process, only localized point-like sintering necks, similar to "welding," can be formed between fibers and particles, and between particles themselves. The bonding area is small, and the bonding strength is insufficient, making it difficult to form continuous and strong inter-fiber bonds. This microstructural characteristic leads to low overall mechanical strength of the material, exhibiting typical brittle fracture characteristics, poor impact resistance, and low damage tolerance. It is prone to cracking and breakage under vibration, thermal shock, or minor mechanical collisions, severely restricting the material's processing reliability and reusability.

[0004] Third, the silanol groups formed after silica sol sintering have extremely strong polarity and readily combine with water molecules in the environment through hydrogen bonds, giving the heat insulation tiles significant hydrophilicity. Simultaneously, the interconnected porous structure between fibers provides channels for moisture intrusion, allowing environmental moisture to easily penetrate the material's interior. The adsorbed moisture rapidly vaporizes during high-temperature service, causing volume expansion and vapor pressure, inducing microcrack propagation and structural damage, accelerating material aging and performance degradation.

[0005] Therefore, developing a heat-insulating tile-based composite material that combines high thermal insulation performance, high mechanical strength, and self-hydrophobic properties is of great engineering value and scientific significance for improving the overall performance and service reliability of the thermal protection system of aerospace vehicles. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to address the shortcomings of the existing technology by providing a high-strength phenolic aerogel nested heat insulation tile composite material and its preparation method. By using different modified phenolic resins to impregnate the heat insulation tile twice, the material has the characteristics of high-efficiency heat insulation, high strength and self-hydrophobicity.

[0007] To address the technical problem proposed in this invention, this invention provides a method for preparing a high-strength phenolic aerogel nested thermal insulation tile composite material, comprising the following steps: 1) Add the epoxy silane coupling agent to an aqueous ethanol solution for catalytic hydrolysis to obtain a silane hydrolysate; add the silane hydrolysate to a phenolic resin solution, then add a curing agent and stir to obtain a silane coupling agent modified phenolic resin solution. 2) Place the heat insulation tile into the mold, close the mold and evacuate it. Then, inject the silane coupling agent modified phenolic resin solution into the mold to impregnate the heat insulation tile. After curing, demold to obtain the composite material intermediate. 3) Methyltrimethoxysilane and tetraethyl orthosilicate were added to an aqueous ethanol solution for catalytic hydrolysis to obtain a silicon source hydrolysate; aluminum isopropoxide and acetylacetone were added to an aqueous ethanol solution for catalytic hydrolysis to obtain an aluminum source hydrolysate; the silicon source hydrolysate and the aluminum source hydrolysate were added to a phenolic resin solution, and a curing agent was added and stirred to obtain a silicon-aluminum modified phenolic resin solution. 4) Place the composite intermediate into the mold, close the mold and evacuate it, then inject the silicon-aluminum modified phenolic resin solution into the mold to impregnate the composite intermediate. After curing, demold and dry to obtain the phenolic aerogel nested heat insulation tile composite material.

[0008] In the above scheme, the epoxy silane coupling agent is γ-glycidoxypropyltrimethoxysilane (KH-560).

[0009] In the above scheme, the molar ratio of the epoxy silane coupling agent to the ethanol in the aqueous ethanol solution used for catalytic hydrolysis is 1:3 to 1:5.

[0010] In the above scheme, the pH of the system is adjusted to 4-5.5 with acetic acid before the epoxy silane coupling agent is catalytically hydrolyzed, and then catalytic hydrolysis is performed for 0.5-1 h.

[0011] In the above scheme, in step 1), the mass of the silane hydrolysate is 5-10% of the mass of the solid phenolic resin in the phenolic resin solution.

[0012] In the above scheme, the viscosity of the silane coupling agent modified phenolic resin solution is 20~50 mPa·s.

[0013] In the above scheme, the heat insulation tile is a silica-based rigid heat insulation tile, which has a porous structure with a pore size of 1~200μm and a density of 0.3~0.4 g / cm³.3 10% deformation compressive strength ≥1.5 MPa.

[0014] In the above scheme, in step 2), the vacuum degree of the vacuum pump is -0.03 to -0.05 MPa, and the holding time is 5 to 15 minutes.

[0015] In the above scheme, in step 2), the injection pressure of the silane coupling agent modified phenolic resin solution is 0.1~0.3MPa, and the pressure is maintained for 5~10 min after the resin solution fills the mold.

[0016] In the above scheme, in step 2), the curing temperature is 90~120 ℃ and the time is 6~8 h.

[0017] In the above scheme, the purity of methyltrimethoxysilane is ≥98%, and the purity of tetraethyl orthosilicate is ≥99%.

[0018] In the above scheme, the molar ratio of methyltrimethoxysilane to tetraethyl orthosilicate is 1:1 to 2:1, and the total molar ratio of the two to the molar ratio of ethanol in the aqueous ethanol solution used for catalytic hydrolysis is 1:3 to 1:5.

[0019] In the above scheme, the pH of the system is adjusted to 4.6-5.6 with acetic acid before the catalytic hydrolysis of methyltrimethoxysilane and tetraethyl orthosilicate, and then the hydrolysis is carried out for 1-2 hours.

[0020] In the above scheme, the purity of aluminum isopropoxide is ≥99%, and the purity of acetylacetone is ≥99%.

[0021] In the above scheme, the molar ratio of aluminum isopropoxide to acetylacetone is 1:1.5 to 1:2.5, and the total molar ratio of the two to the molar ratio of ethanol in the aqueous ethanol solution used for catalytic hydrolysis is 1:3 to 1:5.

[0022] In the above scheme, the catalytic hydrolysis time of aluminum isopropoxide and acetylacetone is 1~2h.

[0023] In the above scheme, in step 3), the mass ratio of silicon source hydrolysate to aluminum source hydrolysate is 1:1 to 1:6, and the total mass of the two is 10 to 20% of the mass of solid phenolic resin in the phenolic resin solution.

[0024] In the above scheme, in steps 1) and 3), the phenolic resin solution is prepared by dissolving solid phenolic resin in anhydrous ethanol, or by diluting liquid phenolic resin with a higher solid content with anhydrous ethanol. Preferably, the liquid phenolic resin has a room temperature viscosity of 1000~1300 mPa·s, a solid content of 67~73%, and a free phenol content ≤1%.

[0025] In the above scheme, in steps 1) and 3), the phenolic resin solution is a thermoplastic phenolic resin solution with a solid content of 5% to 40%. Preferably, the solid content of the phenolic resin solution in step 1) is 5% to 10%, and the solid content of the phenolic resin solution in step 3) is 20% to 40%.

[0026] In the above scheme, in steps 1) and 3), the volume fraction of ethanol in the ethanol aqueous solution is 80-90%.

[0027] In the above scheme, in steps 1) and 3), the curing agent is hexamethylenetetramine with a purity ≥99%.

[0028] In the above scheme, in steps 1) and 3), the amount of curing agent added is 10-20% of the mass of solid phenolic resin in the phenolic resin solution.

[0029] In the above scheme, in steps 1) and 3), after the curing agent is added, the stirring temperature is 30~40 ℃ and the stirring time is 0.5~1 h.

[0030] In the above scheme, the viscosity of the silicon-aluminum modified phenolic resin solution is 60~120 mPa·s.

[0031] In the above scheme, in step 4), the vacuum degree of the vacuum pump is -0.05 to -0.07 MPa, and the holding time is 5 to 15 minutes.

[0032] In the above scheme, in step 4), the injection pressure of the silicon-aluminum modified phenolic resin solution is 0.2~0.6 MPa, and after the resin solution fills the mold, it is held at 0.3~0.5 MPa for 5~10 min.

[0033] In the above scheme, in step 4), the curing process is a two-stage curing process. The first stage is at a temperature of 60~70 ℃ and is kept at that temperature for 2~4 h. The second stage is at a temperature of 90~120 ℃ and is kept at that temperature for 8~10 h.

[0034] In the above scheme, the drying temperature is 60~70 ℃, and the drying is carried out to constant weight.

[0035] The present invention also provides a high-strength phenolic aerogel nested thermal insulation tile composite material, which is prepared by the above method.

[0036] In the above scheme, the composite material includes a heat insulation tile matrix and an aerogel phase. The aerogel phase fills the pores inside the heat insulation tile matrix to form a multi-level nested pore structure. Specifically, the multi-level nested pore structure is that the heat insulation tile matrix provides a large pore skeleton, and the small pores formed by the aerogel are nested and distributed inside the large pores of the heat insulation tile to form a pore nesting structure of large pores surrounding small pores.

[0037] In the above scheme, the composite material has bulk hydrophobic properties, not just surface hydrophobicity. The water contact angle of the cross section obtained by cutting along the thickness direction is >140°, and the moisture absorption rate is <0.5%. It has excellent mechanical properties, with a flexural strength ≥3 MPa and a 10% deformation compressive strength ≥3 MPa. It also has excellent thermal insulation properties, with the temperature on the back of the sample <60 ℃ after 300 s under static heat flow test conditions of 700 ℃.

[0038] The main technical concept and technical principles of this invention are as follows: This invention employs a two-stage impregnation process, using different modified phenolic resins to impregnate the heat insulation tiles, thereby solving the technical problems of low heat insulation efficiency, poor mechanical properties, and easy moisture absorption in existing heat insulation tiles. Specific details are as follows: First, the phenolic aerogel-nested insulating tile composite material of the present invention can achieve high-efficiency heat insulation. After the phenolic aerogel is nested in the insulating tile, the material can be divided into two regions when heated on one side: a high-temperature zone and a medium-low temperature zone. In the high-temperature zone, the phenolic resin will decompose, and small molecules will volatilize, thereby reducing the surface temperature and achieving a self-cooling effect. The silane coupling agent modified phenolic resin impregnated in the first injection can adhere well to the insulating tile to form a good interface and suppress the generation of defects. The silicon-aluminum modified phenolic resin impregnated in the second injection increases the decomposition temperature of the phenolic resin, thereby improving the temperature resistance of the material. The combined effect of the two modified phenolic resins makes the thermal stability better than that of a single modification. In the low- and medium-low temperature range, aerogels exhibit three intrinsic thermal insulation mechanisms that work together to block heat transfer: First, the "zero convection" effect, where the pore size of aerogels (20-50 nm) is smaller than the mean free path of air (70 nm), thus preventing free airflow inside; second, the "infinitely long path" effect, where the network skeleton of aerogels infinitely extends the heat conduction path, making it difficult for heat to be conducted at the gas-solid interface; and third, the "infinite thermal barrier" effect, where the network skeleton of aerogels forms an "infinite thermal barrier" effect, shielding against thermal radiation; and finally, the high specific surface area, combined with special anti-radiation materials, effectively blocks radiative heat transfer.

[0039] Secondly, the phenolic aerogel-nested thermal insulation tile composite material of this invention can achieve high mechanical strength. Thermal insulation tiles are limited by the structural characteristics of local bonding at the sintering neck, resulting in high brittleness and poor mechanical properties, making them prone to cracking and damage during use. In this invention, after the micron-sized thermal insulation tile is filled and cured with phenolic aerogel, the continuous aerogel matrix wraps around the sintering neck and fills the fiber gaps, forming a covering and anchoring effect on the point-connected sintering neck, compensating for the weak bonding defects of the sintering neck. Firstly, the silane coupling agent in the phenolic resin is modified with a silane coupling agent, which, after hydrolysis, bridges the inorganic fibers of the thermal insulation tile, while on the other side it combines with the organic phenolic resin, strengthening the internal fiber skeleton and improving the interfacial bonding strength. Secondly, after the hydrolysis and condensation of MTMS and TEOS in the silicon-aluminum modified phenolic resin, they not only self-polymerize to form silica nanoclusters, providing a nano-reinforcing effect, but also undergo dehydration condensation with the unreacted silanol groups in the first impregnation layer, achieving secondary reinforcement. The combined effect significantly improves the overall mechanical strength. Meanwhile, the phenolic aerogel composite is nested in the micron-sized pores of the heat insulation tile, filling the original large pores and large diameters into small pores, that is, "small pores filling large pores", which provides comprehensive microstructural support and reinforcement for the heat insulation tile, resulting in a heat insulation tile with high mechanical strength and high toughness.

[0040] Finally, the phenolic aerogel-nested thermal insulation tile composite material of this invention can achieve self-hydrophobicity. When directly impregnating thermal insulation tiles with a hydrophobic modifier, it is difficult to stably achieve a hydrophobic effect due to the micron-level interconnected pores and poor interfacial compatibility of the tiles. This invention solves this problem through a two-stage impregnation process. In the composite intermediate obtained after the first impregnation and pre-curing of the phenolic resin solution modified by the silane coupling agent, the coupling agent KH560 achieves perfect interfacial bonding and uniform dispersion, which is more conducive to the subsequent bonding of the silicon-aluminum modified phenolic resin. After the second hydrolysis and condensation of MTMS and TEOS, their active silanol groups undergo a condensation reaction with the phenolic resin network and the aluminum hydroxyl groups of the aluminum source, firmly grafting onto the skeleton surface. Furthermore, the hydrophobic methyl groups provided by MTMS synergize more uniformly and efficiently with the silicon-oxygen network from the first impregnation, blocking water vapor penetration and maximizing its hydrophobic effect, giving the phenolic aerogel-nested thermal insulation tile composite material self-hydrophobicity and low moisture absorption.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention utilizes different modified phenolic resins to impregnate heat-insulating tiles twice, constructing a multi-level porous composite structure with large pores nested within aerogel pores. The resulting composite material exhibits excellent thermal insulation performance, with a back surface temperature <60℃ after 300 s under static heat flow testing at 700℃. It also possesses excellent mechanical properties, with a flexural strength ≥3 MPa and a 10% deformation compressive strength ≥3 MPa. Furthermore, it exhibits inherent hydrophobicity, not just surface hydrophobicity, with a water contact angle >140° at the cross-section obtained along the thickness direction and a moisture absorption rate <0.5%. This invention solves the problems of low thermal insulation efficiency, poor mechanical properties, and overall moisture absorption in existing heat-insulating tiles, making it a heat-insulating tile-based composite material that combines high thermal insulation performance, high mechanical strength, and self-hydrophobic properties.

[0042] This invention uses a two-stage glue impregnation process combined with atmospheric pressure drying to prepare composite materials. The preparation process is simple to operate, has a short preparation cycle, low production cost, and is easy to mass-produce. Attached Figure Description

[0043] Figure 1 This is a process flow diagram for preparing high-strength phenolic aerogel nested thermal insulation tile composite material according to an embodiment of the present invention.

[0044] Figure 2 This is a physical image of the high-strength phenolic aerogel nested thermal insulation tile composite material prepared in Example 1.

[0045] Figure 3 Comparison of SEM microstructures of the original heat insulation tile (left) and the high-strength phenolic aerogel nested heat insulation tile composite material prepared in Example 1 (right) after being cut along the thickness direction.

[0046] Figure 4 Comparison of the SEM microstructure of the high-strength phenolic aerogel nested thermal insulation tile composite material prepared in Example 1 (left) and the composite material prepared in Comparative Example 4 (right) after being cut along the thickness direction.

[0047] Figure 5 Back temperature diagram of the high-strength phenolic aerogel nested thermal insulation tile composite material prepared in each embodiment, subjected to a static heat flow heating test at 700 °C.

[0048] Figure 6 The back temperature diagrams are obtained from the static heat flow heating test at 700 °C for the high-strength phenolic aerogel nested heat insulation tile composite material prepared in Example 1, the composite materials prepared in each comparative example, and the original heat insulation tile.

[0049] Figure 7 The figure shows the water contact angle test results of the cross section after the high-strength phenolic aerogel nested thermal insulation tile composite material prepared in Example 1 was cut along the thickness direction.

[0050] Figure 8The image shows a hydrophobic test result of the cross-section of the high-strength phenolic aerogel nested thermal insulation tile composite material prepared in Example 1 after being cut along the thickness direction.

[0051] Figure 9 This is a diagram showing the water contact angle test results of the cross-section after the original insulation tile was cut along its thickness direction.

[0052] Figure 10 This is a photograph of the hydrophobicity test results of the cross-section of the original heat insulation tile after it was cut along the thickness direction. Detailed Implementation

[0053] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0054] The raw materials used in the following examples include: phenolic resin is Henan Zhongfan Dongsheng PF5435 thermoplastic phenolic resin, with a room temperature viscosity of 1200 mPa·s, a solid content of 71%, and a free phenol content ≤1%. In each example, it was diluted with anhydrous ethanol to a phenolic resin solution with a lower solid content before use; the heat insulation tile is a silica-based rigid heat insulation tile produced by Shandong Industrial Ceramics Design and Research Institute, which has a porous structure with an open pore diameter of 5~50 μm and a density of 0.35 g / cm³. 3 10% deformation compressive strength ≥1.5 MPa; silane coupling agent is KH560; methyltrimethoxysilane purity ≥98%; tetraethyl orthosilicate purity ≥99%; aluminum isopropoxide purity ≥99%; acetylacetone purity ≥99%; curing agent is hexamethylenetetramine purity ≥99%.

[0055] Example 1 This embodiment prepares a high-strength phenolic aerogel nested thermal insulation tile composite material. The preparation steps are as follows: (1) KH560 was added to an ethanol aqueous solution with a volume fraction of 90%, the molar ratio of KH560 to ethanol in the aqueous solution was 1:3, the pH of the system was adjusted to 5 with a trace amount of glacial acetic acid, and hydrolysis was carried out at room temperature for 0.5 h to obtain a silane hydrolysate. The silane hydrolysate was added to a phenolic resin solution with a solid content of 10%, the mass of the silane hydrolysate being 10% of the mass of the phenolic resin solids in the phenolic resin solution, and then a curing agent was added, the amount of the curing agent being 15% of the mass of the phenolic resin solids in the phenolic resin solution, and the mixture was stirred continuously at 35°C for 0.5 h to obtain a silane coupling agent modified phenolic resin solution with a viscosity of 39 mPa·s.

[0056] (2) Place heat insulation tiles in the mold, close the mold and evacuate to a vacuum of -0.04 MPa for 10 min, then turn off the vacuum pump. Then, use the injection method to inject silane coupling agent modified phenolic resin solution into the cavity through the injection port of the mold, control the injection pressure to 0.2 MPa, and wait until the silane coupling agent modified phenolic resin solution fills the mold and there are no bubbles in the silane coupling agent modified phenolic resin solution discharged from the outlet, then close the outlet. Keep the injection port open and maintain the injection pressure at 0.2 MPa for 5 min. Transfer the impregnated body after injection into the oven for curing treatment at a curing temperature of 90 ℃ for 8 h. Finally, let it cool naturally to room temperature and demold to obtain the composite material intermediate.

[0057] (3) Methyltrimethoxysilane and tetraethyl orthosilicate were added to an ethanol aqueous solution with a volume fraction of 90%, the molar ratio of methyltrimethoxysilane, tetraethyl orthosilicate, and ethanol in the aqueous solution being 1:1:6. The pH of the system was adjusted to 5 using a trace amount of glacial acetic acid, and pre-hydrolyzed at room temperature for 1 hour to obtain a silicon source hydrolysate. Aluminum isopropoxide and acetylacetone were added to an ethanol aqueous solution with a volume fraction of 90%, the molar ratio of aluminum isopropoxide, acetylacetone, and ethanol in the aqueous solution being 1:2:9. Hydrolyzed at room temperature for 1 hour to obtain an aluminum source hydrolysate. The silicon source hydrolysate and aluminum source hydrolysate were added sequentially to a phenolic resin solution with a solid content of 35%, controlling the mass ratio of silicon source hydrolysate to aluminum source hydrolysate to be 1:2, and the total mass of the two being 15% of the solid mass of phenolic resin in the phenolic resin solution. A curing agent was then added, the amount of which was 15% of the solid mass of phenolic resin in the phenolic resin solution. The mixture was stirred at 35°C for 0.5 minutes. h, a silicon-aluminum modified phenolic resin solution was obtained with a viscosity of 94 mPa·s.

[0058] (4) Place the composite intermediate in the mold, close the mold and evacuate to a vacuum of -0.05 MPa for 5 minutes, then turn off the vacuum pump. Then, use the injection method to inject the silicon-aluminum modified phenolic resin solution into the cavity through the injection port of the mold, control the injection pressure to 0.2 MPa, and close the injection port when the silicon-aluminum modified phenolic resin solution fills the mold and there are no bubbles in the silicon-aluminum modified phenolic resin solution discharged from the outlet. Keep the injection port open and maintain the injection pressure at 0.3 MPa for 5 minutes. After the injection is completed, transfer the impregnated body into the oven for curing treatment, which is divided into two stages. The first stage is 60 ℃ and the heat is kept for 4 h. The second stage is 90 ℃ and the heat is kept for 10 h. Finally, after natural cooling to room temperature, demold to obtain the phenolic aerogel nested heat insulation tile molded body.

[0059] (5) The obtained phenolic aerogel nested heat insulation tile molded body was placed in an oven and dried at normal pressure at a drying temperature of 60℃. After drying at a constant temperature for 24 h, it was taken out and weighed after cooling to room temperature. It was then dried again for 1 h. When the mass change rate was ≤0.1%, it was considered to be dried to constant weight, and the phenolic aerogel nested heat insulation tile composite material was obtained.

[0060] Figure 2 The image shows a physical sample of the high-strength phenolic aerogel nested thermal insulation tile composite material prepared in Example 1. It can be seen that the sample is intact and has a good surface morphology.

[0061] Figure 3 The image shows a comparison of the SEM microstructure of the original heat insulation tile (left) and the high-strength phenolic aerogel-nested heat insulation tile composite material prepared in Example 1 (right) after being cut along the thickness direction. It can be seen that in the composite material prepared in Example 1, the aerogel was successfully nested in the pores of the heat insulation tile.

[0062] Example 2 This embodiment prepares a high-strength phenolic aerogel nested thermal insulation tile composite material. The preparation steps are as follows: (1) KH560 was added to an 85% (v / v) aqueous ethanol solution, with a molar ratio of KH560 to ethanol in the aqueous ethanol solution of 1:4. The pH of the system was adjusted to 4 using a trace amount of glacial acetic acid. The solution was hydrolyzed at room temperature for 1 h to obtain a silane hydrolysate. The silane hydrolysate was added to a 5% (w / v) phenolic resin solution, with the mass of the silane hydrolysate being 5% of the mass of the phenolic resin solids in the phenolic resin solution. A curing agent was then added, with the amount of curing agent being 10% of the mass of the phenolic resin solids in the phenolic resin solution. The mixture was stirred continuously at 30°C for 1 h to obtain a silane coupling agent modified phenolic resin solution with a viscosity of 26 mPa·s.

[0063] (2) Place heat insulation tiles in the mold, close the mold and evacuate to a vacuum of -0.03 MPa for 5 minutes, then turn off the vacuum pump. Then, use the injection method to inject silane coupling agent modified phenolic resin solution into the cavity through the injection port of the mold, control the injection pressure to 0.1 MPa, and wait until the silane coupling agent modified phenolic resin solution fills the mold and there are no bubbles in the silane coupling agent modified phenolic resin solution discharged from the outlet, then close the outlet. Keep the injection port open and maintain the injection pressure at 0.1 MPa for 10 minutes. Transfer the impregnated body after injection into the oven for curing treatment at a curing temperature of 120 ℃ for 6 h. Finally, let it cool naturally to room temperature and demold to obtain the composite material intermediate.

[0064] (3) Methyltrimethoxysilane and tetraethyl orthosilicate were added to an 85% (v / v) aqueous solution of ethanol, with a molar ratio of 1.5:1:8 for methyltrimethoxysilane, tetraethyl orthosilicate, and ethanol in the aqueous solution. The pH of the system was adjusted to 5.6 with a trace amount of glacial acetic acid, and the solution was pre-hydrolyzed at room temperature for 1.5 h to obtain a silicon source hydrolysate. Aluminum isopropoxide and acetylacetone were added to an 85% (v / v) aqueous solution of ethanol, with a molar ratio of 1:1.5:10 for aluminum, and the solution was hydrolyzed at room temperature for 1.5 h to obtain an aluminum source hydrolysate. The silicon source hydrolysate and aluminum source hydrolysate were added sequentially to a phenolic resin solution with a solid content of 20%, with the mass ratio of silicon source hydrolysate to aluminum source hydrolysate controlled at 1:4, and the total mass of the two being 10% of the solid mass of phenolic resin in the phenolic resin solution. A curing agent was then added, with the amount of curing agent being 10% of the solid mass of phenolic resin in the phenolic resin solution. The mixture was stirred at 30°C for 1 hour. h, a silicon-aluminum modified phenolic resin solution was obtained with a viscosity of 68 mPa·s.

[0065] (4) Place the composite intermediate in the mold, close the mold and evacuate to a vacuum of -0.06 MPa for 10 minutes, then turn off the vacuum pump. Then, use the injection method to inject the silicon-aluminum modified phenolic resin solution into the cavity through the injection port of the mold, control the injection pressure to 0.4 MPa, and close the injection port when the silicon-aluminum modified phenolic resin solution fills the mold and there are no bubbles in the silicon-aluminum modified phenolic resin solution discharged from the outlet. Keep the injection port open and maintain the injection pressure at 0.4 MPa for 8 minutes. Transfer the impregnated body after injection into the oven for curing treatment in two stages: the first stage is 65 ℃ and the heat is kept for 3 h; the second stage is 100 ℃ and the heat is kept for 9 h. Finally, after natural cooling to room temperature, demold to obtain the phenolic aerogel nested heat insulation tile molded body.

[0066] (5) The obtained phenolic aerogel nested heat insulation tile molded body was placed in an oven and dried at normal pressure at a drying temperature of 65℃. After drying at a constant temperature for 24 h, it was taken out and weighed after cooling to room temperature. It was then dried again for 1 h. When the mass change rate was ≤0.1%, it was considered to be dried to constant weight, and the phenolic aerogel nested heat insulation tile composite material was obtained.

[0067] Example 3 This embodiment prepares a high-strength phenolic aerogel nested thermal insulation tile composite material. The preparation steps are as follows: (1) KH560 was added to an 80% (v / v) aqueous ethanol solution, with a molar ratio of KH560 to ethanol in the aqueous ethanol solution of 1:5. The pH of the system was adjusted to 5.5 using a trace amount of glacial acetic acid. The solution was hydrolyzed at room temperature for 40 min to obtain a silane hydrolysate. The silane hydrolysate was added to a 10% (v / v) phenolic resin solution, with the mass of the silane hydrolysate being 7% of the mass of the phenolic resin solids in the phenolic resin solution. A curing agent was then added, with the amount of curing agent being 20% ​​of the mass of the phenolic resin solids in the phenolic resin solution. The mixture was stirred continuously at 40°C for 40 min to obtain a silane coupling agent modified phenolic resin solution with a viscosity of 48 mPa·s.

[0068] (2) Place heat insulation tiles in the mold, close the mold and evacuate to a vacuum of -0.05 MPa for 15 minutes, then turn off the vacuum pump. Then, use the injection method to inject silane coupling agent modified phenolic resin solution into the cavity through the injection port of the mold, control the injection pressure to 0.3 MPa, and wait until the silane coupling agent modified phenolic resin solution fills the mold and there are no bubbles in the silane coupling agent modified phenolic resin solution discharged from the outlet, then close the outlet. Keep the injection port open and maintain the injection pressure at 0.3 MPa for 5 minutes. Transfer the impregnated body after injection into the oven for curing treatment at a curing temperature of 100 ℃ for 7 h. Finally, let it cool naturally to room temperature and then demold to obtain the composite material intermediate.

[0069] (3) Methyltrimethoxysilane and tetraethyl orthosilicate were added to an 80% (v / v) aqueous solution of ethanol, with a molar ratio of 2:1:12. The pH of the system was adjusted to 4.6 using a trace amount of glacial acetic acid, and pre-hydrolyzed at room temperature for 2 h to obtain a silicon source hydrolysate. Aluminum isopropoxide and acetylacetone were added to an 80% (v / v) aqueous solution of ethanol, with a molar ratio of 1:2.5:14. Hydrolyzed at room temperature for 2 h to obtain an aluminum source hydrolysate. The silicon source hydrolysate and aluminum source hydrolysate were added sequentially to a phenolic resin solution with a solid content of 40%, controlling the mass ratio of silicon source hydrolysate to aluminum source hydrolysate to be 1:5, and the total mass of the two was 20% of the solid mass of phenolic resin in the phenolic resin solution. A curing agent was then added, with the amount of curing agent added being 20% ​​of the solid mass of phenolic resin in the phenolic resin solution. The mixture was stirred at 40°C for 40 h. After min, a silicon-aluminum modified phenolic resin solution was obtained with a viscosity of 118 mPa·s.

[0070] (4) Place the composite intermediate in the mold, close the mold and evacuate to a vacuum of -0.07 MPa for 15 minutes, then turn off the vacuum pump. Then, use the injection method to inject the silicon-aluminum modified phenolic resin solution into the cavity through the injection port of the mold, control the injection pressure to 0.6 MPa, and close the injection port when the silicon-aluminum modified phenolic resin solution fills the mold and there are no bubbles in the silicon-aluminum modified phenolic resin solution discharged from the outlet. Keep the injection port open and maintain the injection pressure at 0.5 MPa for 10 minutes. Transfer the impregnated body after injection into the oven for curing treatment in two stages: the first stage is 70 ℃ and the heat is kept for 2 h; the second stage is 120 ℃ and the heat is kept for 8 h. Finally, after natural cooling to room temperature, demold to obtain the phenolic aerogel nested heat insulation tile molded body.

[0071] (5) The obtained phenolic aerogel nested heat insulation tile molded body was placed in an oven and dried at normal pressure at a drying temperature of 70℃. After drying at a constant temperature for 24 h, it was taken out and weighed after cooling to room temperature. It was then dried again for 1 h. When the mass change rate was ≤0.1%, it was considered to be dried to constant weight, and the phenolic aerogel nested heat insulation tile composite material was obtained.

[0072] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that steps (3) and (4) are not performed; instead, the heat insulation tile is impregnated with a silane coupling agent modified phenolic resin solution and then cured.

[0073] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that steps (1) and (2) are omitted, and the heat insulation tile is directly impregnated with a silicon-aluminum modified phenolic resin solution and then cured.

[0074] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that no heat-insulating tile skeleton is introduced. Preparation process: A silane coupling agent modified phenolic resin solution is injected into a mold and cured to obtain a primary aerogel; then, a silica-alumina modified phenolic resin solution is injected into the pores of the gel and impregnated, and cured again to finally obtain a skeletonless blended modified phenolic aerogel.

[0075] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that in step (1), the epoxy silane coupling agent is not added to the ethanol aqueous solution for hydrolysis beforehand, but is directly added to the phenolic resin solution to prepare the silane coupling agent modified phenolic resin solution; in step (3), methyltrimethoxysilane, tetraethyl orthosilicate, aluminum isopropoxide and acetylacetone are not added to the ethanol aqueous solution for hydrolysis beforehand, but are directly added to the phenolic resin solution to prepare the silicon aluminum modified phenolic resin solution.

[0076] Figure 4The image shows a comparison of the SEM microstructures of the high-strength phenolic aerogel nested thermal insulation tile composite material prepared in Example 1 (left) and the composite material prepared in Comparative Example 4 (right) after being cut along the thickness direction. It can be seen that direct mixing without prior hydrolysis results in poor compatibility between organic and inorganic components, incomplete hydrolysis and condensation reaction, and a significant decrease in the uniformity of the aerogel pore structure.

[0077] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that steps (1) and (3) are reversed. That is, the heat insulation tile is first impregnated with a silicon-aluminum modified phenolic resin solution and then cured to obtain a composite material intermediate. Then, the composite material intermediate is impregnated with a silane coupling agent modified phenolic resin solution and cured to obtain a phenolic aerogel nested heat insulation tile molded body. Finally, it is dried to obtain a phenolic aerogel nested heat insulation tile composite material.

[0078] Comparative Example 6 The difference between Comparative Example 6 and Example 1 is that steps (1) and (2) are omitted, and step (3) is modified as follows: silane hydrolysate, silicon source hydrolysate and aluminum source hydrolysate are added to a phenolic resin solution with a solid content of 20% in a mass ratio of 3:1:4. The total mass of the three is 15% of the solid mass of phenolic resin in the phenolic resin solution. Then, a curing agent is added, and the amount of curing agent added is 10% of the solid mass of phenolic resin in the phenolic resin solution. The mixture is stirred at 30°C for 1 h to obtain a modified phenolic resin solution. Then, the phenolic aerogel nested heat insulation tile is obtained by impregnation with glue in step (4). Finally, the phenolic aerogel nested heat insulation tile composite material is obtained by drying in step (5).

[0079] Nitrogen adsorption-desorption test According to GB / T 19587-2017, the intrinsic pore structure of phenolic aerogel nested thermal insulation tiles was tested. The composite materials prepared in Example 1 and Comparative Example 3 were ground into powder and subjected to nitrogen adsorption-desorption tests. The results are shown in Table 1.

[0080] Table 1

[0081] As shown in Table 1, the BET specific surface area of ​​Example 1 is 58.2 m². 2 / g, BJH pore volume 0.61 cm³ 3 The average pore size of BJH is 22.8 nm, similar to that of pure phenolic aerogel, exhibiting typical mesoporous material characteristics. This indicates that even after being nested with insulating tiles, it retains the microporous structure of phenolic aerogel, without collapsing or overfilling due to the two impregnation processes.

[0082] drop test Drop tests were conducted according to GB / T 4857.5-1992 standard. Each sample weighed 100 g and was dropped from a height of 0.75 m onto a rigid cement floor. The drop slag rate of Examples 1-3, Comparative Examples 1-2, and the original insulation tile was tested. The results are shown in Table 2.

[0083] Table 2

[0084] As can be seen from the drop slag rate in Table 2, the toughness of the composite material obtained by two injection impregnations in Example 1 is two orders of magnitude higher than that of the composite material obtained by one injection impregnation in Comparative Example 1 and Comparative Example 2, as well as the original heat insulation tile, demonstrating high strength and toughness.

[0085] Density and mechanical strength test The density of the samples was tested according to GB / T 6343-2009. The bending and compressive mechanical properties of each embodiment, comparative example, and original heat insulation tile were tested using an electronic universal testing machine according to GB / T 1449-2005 and GB / T1448-2005. The test results are shown in Table 3.

[0086] Table 3

[0087] As shown in Table 3, the mechanical strength of the composite materials in the examples is improved compared to the original heat insulation tiles. The flexural strength of the examples is >3 MPa, and the specific flexural strength is >7 MPa. cm 3 / g, 10% strain compressive strength > 3 MPa, 10% strain specific compressive strength > 6 MPa cm 3 / g. Comparative Example 1 only underwent silane coupling agent-modified phenolic resin impregnation, resulting in only partial interface optimization. While flexural and compressive properties improved slightly compared to the original insulation tile, the difference was not significant. Comparative Example 2 only underwent silica-alumina-modified phenolic resin impregnation, without the initial interface optimization. The resulting nested structure and the interfacial bonding between the internal phenolic resin and fibers were unstable, leading to low mechanical strength. Comparative Example 3 was a blended modified phenolic aerogel without nested insulation tiles. Due to the lack of skeletal support, shrinkage during drying resulted in a significant increase in density and a decrease in flexural and compressive properties. Comparative Example 4, lacking pre-hydrolysis, even after secondary impregnation, exhibited a disordered mix of internal silane coupling agents and silica-alumina modifiers, with some directly agglomerated, resulting in significantly reduced mechanical properties compared to the examples. Comparative Example 5 involved switching the order of the impregnation solutions twice. The first impregnation used a silica-alumina modified phenolic resin, which lacked a coupling agent for bridging, resulting in weak interfacial bonding between the fiber and resin. Subsequent impregnation with a silane coupling agent-modified phenolic resin failed to guide wetting, leading to localized accumulation, increased density, and decreased mechanical properties. Comparative Example 6 involved adding a single mixture of silane hydrolysate, silica-based hydrolysate, and aluminum-based hydrolysate to the phenolic resin. This diluted the silane coupling agent, preventing directional bridging between the fiber and resin, resulting in weak interfacial bonding. Furthermore, the lack of stepwise impregnation eliminated the secondary condensation reinforcement mechanism. In addition, the three hydrolysates competed for hydrolysis and condensation, interfering with the crosslinking of the phenolic resin. The concentrated condensation shrinkage caused gel network collapse, leading to increased density and decreased mechanical properties.

[0088] 700 ℃ Static heat flow heating experiment The samples were statically heated using a quartz lamp. The temperature of the heated surface was monitored and controlled at 700℃ using a type K thermocouple. Heating was initiated in 60 seconds to reach 700℃ and maintained for 240 seconds before stopping. The total heating time was 300 seconds. The back temperature change curves of each embodiment, each comparative example, and the original insulation tile were recorded. The test results are as follows: Figure 5 , Figure 6 As shown.

[0089] from Figure 5 As can be seen from the above, the back surface temperature of the phenolic aerogel nested thermal insulation tile composite material in the embodiments of the present invention is <60 ℃ and the thermal insulation efficiency is >91%.

[0090] from Figure 6As can be seen from the data, the final back temperature of the phenolic aerogel nested insulation tile composite material in the embodiments of the present invention is the lowest. The back temperature from low to high is as follows: Embodiment < Comparative Example 1 < Comparative Example 5 < Comparative Example 2 < Comparative Example 4 < Comparative Example 6 < Original insulation tile < Comparative Example 3. Comparative Example 1 only underwent silane coupling agent modified phenolic resin impregnation. Although the interface of the insulation tile was optimized, the lack of a second silicon-aluminum modified phenolic resin impregnation resulted in no increase in the phenolic resin decomposition temperature, and the insulation effect was not as good as that of the Embodiment. Comparative Example 2 only underwent silicon-aluminum modified phenolic resin solution impregnation. The lack of silane coupling agent pre-optimization of the interface led to poor bonding between the skeleton and the fiber, which easily caused defects and reduced the insulation effect. Comparative Example 3 did not have an insulation tile skeleton. In the early stage, it could maintain a low temperature by relying on the decomposition temperature, but after a long time, problems such as the collapse, shrinkage, and cracking of the nano-skeleton of phenolic resin caused the back temperature to rise sharply and could not be maintained. Comparative Example 4, lacking pre-hydrolysis, exhibited uneven distribution of the silane coupling agent and aluminosilicate modifier, resulting in insufficient interfacial bridging and nano-reinforcement, poor aerogel skeleton quality, and thermal insulation primarily relying on the endothermic decomposition of phenolic resin. Comparative Example 5 reversed the impregnation order twice, first impregnating with aluminosilicate modified phenolic resin. Lacking pre-optimization of the interface with the silane coupling agent, the bonding between the aluminosilicate layer and the fiber interface was poor; subsequently, the silane coupling agent-modified phenolic resin could not penetrate to the internal bridging fibers, rendering interface optimization ineffective and reducing thermal insulation performance. Comparative Example 6 involved a single impregnation with a mixture of all hydrolysates. The silane coupling agent was diluted and unable to directionally bridge the fibers, resulting in poor compatibility with the insulation tile interface, uneven distribution of the aluminosilicate modifier, limited increase in the phenolic resin decomposition temperature, and reduced thermal insulation performance.

[0091] Hydrophobicity test The contact angles of each embodiment, comparative example, and original insulation tile were tested using a JY-82B Kruss DSA contact angle measuring instrument according to GB / T 30693-2014. The moisture absorption rates of each embodiment, comparative example, and original insulation tile were tested according to GB / T 41767-2022. The test results are shown in Table 4.

[0092] Table 4

[0093] Table 3 shows that the composite materials obtained by two injection impregnations in the embodiments of the present invention have an average contact angle >140° and an average moisture absorption rate <0.5%, exhibiting high hydrophobicity and low moisture absorption. In contrast, the composite material obtained by one injection impregnation using a silane coupling agent modified phenolic resin solution in Comparative Example 1 is essentially hydrophobic. Although the composite material obtained by one injection impregnation using a silicon-aluminum modified phenolic resin solution in Comparative Example 2 is hydrophobic, its performance is significantly inferior to that of the embodiments of the present invention. In Comparative Example 3, without rigid heat insulation tiles as support, some mesoporous structures shrink and collapse, while the "large pores within small pores" of the embodiments allows hydrophobic groups to be more stably distributed in the channels. In Comparative Example 4, the silicon and aluminum source precursors were not pre-hydrolyzed, and small molecule alkoxysilane and aluminum salts were directly mixed into the phenolic system. The hydrolysis and condensation reactions were asynchronous, making it easy for inorganic phase agglomeration and severe phase separation to occur. The hydrophobic silicon-oxygen network could not be continuously formed, and the hydrophobic performance was greatly reduced. Comparative Example 5 reversed the order of the impregnation solutions twice. First, the silicon-aluminum modified phenolic resin was impregnated. Subsequently, very little of the silane coupling agent-modified phenolic resin penetrated into the interior of the insulation tile, failing to optimize the interface and resulting in a weaker hydrophobic effect compared to the example. Comparative Example 6 mixed all hydrolysates and impregnated and cured them in one step. Methyltrimethoxysilane rapidly gelled and cured with the silicon-aluminum modified phenolic resin solution. During curing, the hydrolysates could not work synergistically, resulting in an uneven distribution of the internal hydrophobic network and hydrophobic groups, leading to a reduced hydrophobic effect compared to the example.

[0094] Figure 7 The image shows the contact angle test results of the cross-section after cutting along the thickness direction in Example 1. It can be concluded that the hydrophobic angle of the cut cross-section is 156.62°. Figure 8 The image shows a cross-section of the hydrophobic material after cutting along the thickness direction in Example 1. It can be seen that the water droplets formed by deionized water are stable spherical in the cross-section of the phenolic aerogel nested thermal insulation tile composite material, indicating good hydrophobicity.

[0095] Figure 9 The image shows the dynamic contact angle test results after the original heat insulation tile was cut along the thickness direction. The dynamic contact angle of the heat insulation tile, captured by a high-speed camera, is 46.31°. Figure 10 This is a picture of the original heat insulation tile after it was cut along the thickness direction for hydrophobicity testing, which shows that the heat insulation tile itself is super hydrophilic, and the deionized water dripped on it immediately penetrates and is absorbed.

[0096] The above embodiments are merely examples for clear illustration and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations, and any obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a high-strength phenolic aerogel nested thermal insulation tile composite material, characterized in that, Includes the following steps: 1) Add the epoxy-based silane coupling agent to an aqueous ethanol solution for catalytic hydrolysis to obtain a silane hydrolysate; Add silane hydrolysate to phenolic resin solution, the mass of silane hydrolysate being 5-10% of the mass of solid phenolic resin in phenolic resin solution, then add curing agent and stir to obtain silane coupling agent modified phenolic resin solution. 2) Place the heat insulation tile into the mold, close the mold and evacuate it. Then, inject the silane coupling agent modified phenolic resin solution into the mold to impregnate the heat insulation tile. After curing, demold to obtain the composite material intermediate. 3) Methyltrimethoxysilane and tetraethyl orthosilicate are added to an aqueous ethanol solution in a molar ratio of 1:1 to 2:1 for catalytic hydrolysis to obtain a silicon-based hydrolysate; aluminum isopropoxide and acetylacetone are added to an aqueous ethanol solution in a molar ratio of 1:1.5 to 1:2.5 for catalytic hydrolysis to obtain an aluminum-based hydrolysate; the silicon-based and aluminum-based hydrolysates are added to a phenolic resin solution, with a mass ratio of silicon-based to aluminum-based hydrolysates of 1:1 to 1:6, and the total mass of the two is 10 to 20% of the solid mass of phenolic resin in the phenolic resin solution; a curing agent is then added and stirred to obtain a silicon-aluminum modified phenolic resin solution; 4) Place the composite intermediate into the mold, close the mold and evacuate it, then inject the silicon-aluminum modified phenolic resin solution into the mold to impregnate the composite intermediate. After curing, demold and dry to obtain the phenolic aerogel nested heat insulation tile composite material.

2. The preparation method of the high-strength phenolic aerogel nested thermal insulation tile composite material according to claim 1, characterized in that, The epoxy silane coupling agent is γ-glycidoxypropyltrimethoxysilane; the molar ratio of the epoxy silane coupling agent to the ethanol in the aqueous ethanol solution used for catalytic hydrolysis is 1:3 to 1:5; the pH of the system is adjusted to 4 to 5.5 with acetic acid before catalytic hydrolysis of the epoxy silane coupling agent, and then catalytic hydrolysis is performed for 0.5 to 1 hour.

3. The method for preparing the high-strength phenolic aerogel nested thermal insulation tile composite material according to claim 1, characterized in that, The ratio of the total amount of methyltrimethoxysilane and tetraethyl orthosilicate to the amount of ethanol in the aqueous ethanol solution used for catalytic hydrolysis is 1:3 to 1:5; the pH of the system is adjusted to 4.6 to 5.6 with acetic acid before catalytic hydrolysis of methyltrimethoxysilane and tetraethyl orthosilicate, and then catalytic hydrolysis is performed for 1 to 2 hours.

4. The preparation method of the high-strength phenolic aerogel nested thermal insulation tile composite material according to claim 1, characterized in that, The ratio of the total amount of aluminum isopropoxide and acetylacetone to the amount of ethanol in the aqueous ethanol solution used for catalytic hydrolysis is 1:3 to 1:5; the catalytic hydrolysis time of aluminum isopropoxide and acetylacetone is 1 to 2 hours.

5. The method for preparing the high-strength phenolic aerogel nested thermal insulation tile composite material according to claim 1, characterized in that, In step 1), the viscosity of the silane coupling agent modified phenolic resin solution is 20~50 mPa·s; in step 3), the viscosity of the silicon-aluminum modified phenolic resin solution is 60~120 mPa·s.

6. The method for preparing the high-strength phenolic aerogel nested thermal insulation tile composite material according to claim 1, characterized in that, In step 2), the vacuum degree of the vacuuming is -0.03 to -0.05 MPa, and the holding time is 5 to 15 min; the injection pressure of the silane coupling agent modified phenolic resin solution is 0.1 to 0.3 MPa, and the pressure is maintained for 5 to 10 min after the resin solution fills the mold; in step 2), the curing temperature is 90 to 120 ℃, and the time is 6 to 8 h.

7. The method for preparing the high-strength phenolic aerogel nested thermal insulation tile composite material according to claim 1, characterized in that, In step 4), the vacuum degree of the vacuuming is -0.05 to -0.07 MPa, and the holding time is 5 to 15 min; the injection pressure of the silicon-aluminum modified phenolic resin solution is 0.2 to 0.6 MPa, and after the resin solution fills the mold, it is held at 0.3 to 0.5 MPa for 5 to 10 min; in step 4), the curing treatment is a two-stage curing process, with the first stage temperature at 60 to 70 ℃ and the holding time at 2 to 4 h; and the second stage temperature at 90 to 120 ℃ and the holding time at 8 to 10 h.

8. The method for preparing the high-strength phenolic aerogel nested thermal insulation tile composite material according to claim 1, characterized in that, The heat insulation tile is a silica-based rigid heat insulation tile with a porous structure, a pore size of 1~200 μm, and a density of 0.3~0.4 g / cm³. 3 10% deformation compressive strength ≥1.5 MPa.

9. The preparation method of the high-strength phenolic aerogel nested thermal insulation tile composite material according to claim 1, characterized in that, The phenolic resin solution is a thermoplastic phenolic resin solution with a solid content of 5% to 40%; the volume fraction of ethanol in the ethanol aqueous solution is 80% to 90%; the curing agent is hexamethylenetetramine, and the amount of curing agent added is 10% to 20% of the solid mass of phenolic resin in the phenolic resin solution.

10. A high-strength phenolic aerogel nested thermal insulation tile composite material prepared by the method of any one of claims 1 to 9.

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