Lightweight high-strength three-dimensional ordered structure silicon-boron modified phenolic aerogel and preparation method thereof

Abstract

The invention relates to the technical field of aerogel, in particular to light-weight high-strength three-dimensional ordered structure silicon-boron modified phenolic aerogel and a preparation method of the light-weight high-strength three-dimensional ordered structure silicon-boron modified phenolic aerogel. The aerogel is prepared from raw materials including boron phenolic resin, an organic solvent, organic silicon resin, organic silicon, acidic pH adjusting liquid and a cross-linking agent, the mass ratio of the boron phenolic resin to the organic solvent is 1: (2.3-3.3), the molecular weight of the boron phenolic resin is 3000-5000, and the content of boron is 2%-10%; the aerogel forms a three-dimensional ordered pore structure. The aerogel provided by the invention has the characteristics of small shrinkage rate, high compression strength, small density, uniform and ordered pore size distribution and the like.

Description

Technical Field

[0001] The present application relates to the field of aerogel technology, and more specifically, to a lightweight, high-strength, three-dimensional ordered structured silicon-boron modified phenolic aerogel and a preparation method thereof. Background Art

[0002] In the field of aerospace, aircraft structural parts need to withstand extreme temperature changes, high stress and other conditions. As a common thermal protection material, phenolic aerogel has low density, low thermal conductivity and excellent thermal stability. It can effectively isolate the aerodynamic heating generated by the aircraft during high-speed flight. Its nanopore structure (smaller than the mean free path of air) can reduce air convection heat transfer and solid-phase heat conduction, and can be used to protect the aircraft from extreme temperatures. However, the temperature resistance of phenolic aerogel is limited, the volume shrinks severely after high-temperature carbonization, and the antioxidant performance is insufficient; the complex process increases the cost and limits large-scale applications; and the mechanical properties of phenolic aerogel are relatively weak, especially in high-temperature environments, its strength and toughness may decrease, which is a challenge for aerospace applications that need to withstand high stress. Therefore, there is an urgent need to synthesize a lightweight, high-strength, ablation-resistant thermal insulation material.

[0003] CN110408071A discloses a normal pressure dry phenolic aerogel and a preparation method thereof, which uses linear phenolic resin as the main raw material, uses silane as a grafting agent to react at 75-120°C, adds an organic solvent and a curing agent to cure at 70-180°C, and dries at room temperature to obtain a phenolic aerogel with a low shrinkage rate. The preparation process of this method is simple, but a high-pressure reactor is required as a container, and the curing reaction temperature must reach a maximum of 120°C.

[0004] CN117624514A discloses a water-based boron-modified phenolic aerogel and a preparation method thereof, wherein phenolic compounds and aldehyde compounds are used as raw materials, water is used as the main reaction solvent, and an acidic boron source is used as a boron modifier and catalyst. After heating and curing and drying at normal pressure, a boron-doped phenolic aerogel is obtained. The method is simple to operate and environmentally friendly, but has a high density (0.38-0.47 g / cm 2 ).

[0005] CN118978703A discloses a boron-containing polysilsesquioxane, a modified aerogel, a boron-silicon hybrid phenolic-based composite material, and a preparation method and application thereof, wherein phenolic resin is used as the main raw material, boron-containing polysilsesquioxane is added, methanol is used as a pore-forming agent, benzenesulfonyl chloride is used as a catalyst for curing, and drying is performed at room temperature and pressure to obtain a phenolic aerogel with heat resistance and thermal stability. The phenolic aerogel prepared by the method has a low thermal conductivity (0.0477W / m·K), but the process is relatively complicated and the compressive strength is low (1.76MPa).

[0006] The above-mentioned method for modifying phenolic aerogel has the following disadvantages:

[0007] (1) The phenolic aerogel in the reported method has a high curing temperature and high requirements for equipment. (2) The phenolic aerogel in the reported method has improved mechanical properties to a certain extent, but the aerogel density is low. (3) The phenolic aerogel in the reported method has low thermal conductivity, but the aerogel process is complex and the mechanical properties are low. The above methods fail to take into account the low density, high mechanical properties and simple and safe synthesis route of phenolic aerogel.

[0008] Therefore, in order to solve the above problems, the present invention provides a lightweight, high-strength, three-dimensional ordered structured boron-silicon modified phenolic aerogel and a preparation method thereof. Summary of the invention

[0009] The present application provides a lightweight, high-strength, three-dimensional ordered structured boron-silicon modified phenolic aerogel and a preparation method thereof, which solves the technical problem in the prior art that the low density and high mechanical properties of the phenolic aerogel as well as a simple and safe synthesis route are not taken into account to meet the thermal protection requirements of aerospace vehicles.

[0010] In the first aspect, the present application provides a lightweight, high-strength, three-dimensional ordered structured boron-silicon modified phenolic aerogel, which adopts the following technical solution:

[0011] A light, high-strength, three-dimensional ordered structured boron-silicon modified phenolic aerogel is prepared from raw materials including boron phenolic resin, organic solvent, silicone resin, silicone, acidic pH regulating liquid and cross-linking agent, wherein the mass ratio of the boron phenolic resin to the organic solvent is 1:(2.3-3.3), the molecular weight of the boron phenolic resin is 3000-5000, and the boron content is 2%-10%.

[0012] Furthermore, the molecular weight of the organic silicon resin is 1000-2500, and the mass ratio of the organic silicon resin to the boron phenolic resin is (0.27-0.4):1.

[0013] Furthermore, the mass ratio of the organosilicon to the boron phenolic resin is (0.2-0.3):1.

[0014] Furthermore, the organosilicon is one of methyl orthosilicate, ethyl orthosilicate, methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane and phenyltriethoxysilane.

[0015] Furthermore, the organic solvent is one of anhydrous ethanol, ethylene glycol or isopropanol.

[0016] Furthermore, the mass ratio of the cross-linking agent to the boron phenolic resin is (0.25-0.3):1.

[0017] Furthermore, the cross-linking agent is hexamethylenetetramine.

[0018] In a second aspect, the present application provides a method for preparing a lightweight, high-strength, three-dimensional ordered structured boron-silicon modified phenolic aerogel, using the following technical solution:

[0019] A method for preparing a lightweight, high-strength, three-dimensional ordered structured boron-silicon modified phenolic aerogel comprises the following steps:

[0020] Adding the boron phenolic resin into an organic solvent and dissolving it at 45-55° C. to obtain a boron-containing phenolic resin solution;

[0021] Adding organosilicon resin, organosilicon and acidic pH adjusting liquid to the boron-containing resin solution, dissolving at 45-55° C., to obtain a silicon-boron-containing resin solution;

[0022] Adding hexamethylenetetramine to the silicon-boron resin solution and dissolving it at room temperature to obtain a curable reaction solution;

[0023] The curable reaction liquid is placed in a sealed container and cured at 60-90° C. for 20-50 hours to obtain a boron-silicon modified phenolic resin wet gel;

[0024] The boron-silicon modified phenolic resin wet gel is subjected to gradient drying to obtain the boron-silicon modified phenolic resin aerogel.

[0025] Furthermore, the gradient drying of the silicon-modified phenolic wet gel is divided into two temperature gradients, the first temperature gradient is 20-40° C., the second temperature gradient is 68-88° C., and the drying time of each gradient is 15-30 hours.

[0026] Furthermore, an acidic pH adjusting liquid is added to adjust the pH value to 4.5-5.5.

[0027] In summary, this application has the following beneficial effects:

[0028] 1. The method for preparing a lightweight, high-strength, three-dimensional ordered structured boron-silicon modified phenolic aerogel provided in the present application ultimately reduces the curing temperature to below 90°C, does not involve high temperature and high pressure reactions, and reduces the requirements for production equipment.

[0029] 2. The method for preparing the lightweight, high-strength, three-dimensional ordered structured boron-silicon modified phenolic aerogel provided in the present application produces less or no volatilization of highly toxic gases during the implementation process, and has less impact on the health of the operator.

[0030] 3. The aerogel obtained in the present application is an aerogel with a three-dimensional ordered pore structure. Such a pore structure skeleton is finer and more stable. While ensuring low density, it also has excellent mechanical properties. The present application can form a three-dimensional ordered pore structure. It relies on a boron phenolic resin with a fixed molecular weight and boron content. After it forms a solution with a suitable solid content with an organic solvent, the addition of a silicon component can significantly improve the flexibility of the phenolic resin molecular chain, so that the pore structure skeleton formed by it is finer; the cured organosilicon resin, organosilicon and boron phenolic resin form physical entanglement and chemical bonding, so that the pore structure skeleton formed by it is finer, thereby significantly increasing the flexibility of the phenolic resin molecular chain, greatly improving the mechanical properties of the aerogel; in addition, in terms of preparation process, the present application uses gradient drying to prepare aerogel materials with high specific surface area and stable pore structure. In order to promote the hydrolysis of the silicon source, a catalyst needs to be introduced. The curing time of the boron phenolic resin is short. In order to allow the silicon source to hydrolyze active silanols in a short period of time, an acidic pH regulating liquid with high hydrolysis efficiency is selected. Moreover, the acidic pH regulating liquid of the present application can make the curing time of the silicon component match the curing time of the phenolic resin, thereby achieving the best curing effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a physical picture of the lightweight, high-strength, three-dimensional ordered structured boron-silicon modified phenolic aerogel obtained in Example 1;

[0032] Figure 2 This is a scanning electron microscope image of the lightweight, high-strength, three-dimensional ordered structured boron-silicon modified phenolic aerogel obtained in Example 1;

[0033] Figure 3 This is a scanning electron microscope image of the lightweight, high-strength, three-dimensional ordered structured silicon-boron modified phenolic aerogel obtained in Example 1;

[0034] Figure 4 This is a pore size distribution diagram of the lightweight, high-strength, three-dimensional ordered structured boron-silicon modified phenolic aerogel obtained in Example 1;

[0035] Figure 5 This is a physical picture of the lightweight, high-strength, three-dimensional ordered structured boron-silicon modified phenolic aerogel obtained in Example 2;

[0036] Figure 6 This is a scanning electron microscope image of the lightweight, high-strength, three-dimensional ordered structured silicon-boron modified phenolic aerogel obtained in Example 2;

[0037] Figure 7 This is the EDS elemental analysis diagram of the lightweight, high-strength, three-dimensional ordered structured silicon-boron modified phenolic aerogel obtained in Example 2;

[0038] Figure 8This is the pore size distribution diagram of the lightweight, high-strength, three-dimensional ordered structured boron-silicon modified phenolic aerogel obtained in Example 2. DETAILED DESCRIPTION

[0039] The present application is further described in detail below with reference to the accompanying drawings and embodiments.

[0040] Example 1

[0041] This embodiment provides a lightweight, high-strength, three-dimensional ordered structure of silicon-boron modified phenolic aerogel, and the preparation method thereof comprises the following steps:

[0042] 101) Add 15 g of boron phenolic resin into a sealable glass bottle, pour 50 g of isopropanol into the bottle, and stir to dissolve at 50° C. to obtain a boron phenolic resin solution; the mass ratio of the boron phenolic resin to the organic solvent is 1:3.3.

[0043] 102) Add 6 g of silicone resin, 3 g of methyltriethoxysilane and 0.75 mL of hydrochloric acid to the boron phenolic resin solution, adjust the pH value to 4.5, stir at 50°C for 4 h, and obtain a silicon-boron containing resin solution, wherein the hydrochloric acid concentration is 0.5 mol / L; the mass ratio of silicone resin to boron phenolic resin is 0.4:1; the mass ratio of silicone to boron phenolic resin is 0.2:1;.

[0044] 103) Add 3.75 g of hexamethylenetetramine to the silicon-boron resin solution, stir and dissolve at 50° C. to obtain a curable reaction solution; the mass ratio of hexamethylenetetramine to boron phenolic resin is 0.25:1.

[0045] 104) placing the curable reaction solution in a sealed container, curing at 60° C. for 50 h to obtain a boron-silicon modified phenolic resin wet gel;

[0046] 105) The boron-silicon modified phenolic resin wet gel was subjected to gradient drying treatment, wherein the first temperature gradient was 20° C., the second temperature gradient was 68° C., the first temperature gradient drying time was 30 h, and the second temperature gradient drying time was 15 h, to obtain boron-silicon modified phenolic resin aerogel.

[0047] The molecular weight of the boron phenolic resin in this embodiment is 3500, and the boron content is 5%.

[0048] The molecular weight of the silicone resin is 1500, and its active functional group is a silicon-oxygen bond.

[0049] Example 2

[0050] This embodiment provides a lightweight, high-strength, three-dimensional ordered structure of silicon-boron modified phenolic aerogel, and the preparation method thereof comprises the following steps:

[0051] 201) Add 20 g of boron phenolic resin into a sealable glass bottle, pour 60 g of isopropanol into the bottle, and stir to dissolve at 50° C. to obtain a boron phenolic resin solution; the mass ratio of the boron phenolic resin to the organic solvent is 1:3.

[0052] 202) Add 6 g of silicone resin, 6 g of methyltriethoxysilane and 0.85 mL of acetic acid to the boron phenolic resin solution, adjust the pH to 4.9, and stir at 50°C for 4 h to obtain a silicon-boron containing resin solution, wherein the acetic acid concentration is 1 mol / L; the mass ratio of silicone resin to boron phenolic resin is 0.3:1; the mass ratio of silicone to boron phenolic resin is 0.3:1.

[0053] 203) Add 6 g of hexamethylenetetramine to the silicon-boron resin solution, stir and dissolve at 50° C. to obtain a curable reaction solution; the mass ratio of hexamethylenetetramine to boron phenolic resin is 0.3:1.

[0054] 204) placing the curable reaction solution in a sealed container, curing at 70° C. for 40 h to obtain a silicon-boron modified phenolic resin wet gel;

[0055] 205) The boron-silicon modified phenolic resin wet gel was subjected to gradient drying treatment, wherein the first temperature gradient was 20°C, the second temperature gradient was 88°C, the first temperature gradient drying time was 15h, and the second temperature gradient drying time was 30h, to obtain boron-silicon modified phenolic resin aerogel.

[0056] The molecular weight of the boron phenolic resin in this embodiment is 3000, and the boron content is 2%.

[0057] The molecular weight of silicone resin is 1000, and its active functional group is silicon-oxygen bond.

[0058] Example 3

[0059] 301) Add 20 g of boron phenolic resin into a sealable glass bottle, pour 50 g of isopropanol into the bottle, stir and dissolve at 50° C. to obtain a boron phenolic resin solution; the mass ratio of the boron phenolic resin to the organic solvent is 1:2.5.

[0060] 302) Add 8 g of silicone resin, 5 g of methyltriethoxysilane and 0.5 mL of sulfuric acid to the boron phenolic resin solution, adjust the pH to 4.7, and stir at 50°C for 4 h to obtain a silicon-boron containing resin solution, wherein the sulfuric acid concentration is 0.5 mol / L; the mass ratio of silicone resin to boron phenolic resin is 0.4:1; the mass ratio of silicone to boron phenolic resin is 0.25:1.

[0061] 303) Add 6 g of hexamethylenetetramine to the silicon-boron resin solution, stir and dissolve at 50° C. to obtain a curable reaction solution; the mass ratio of hexamethylenetetramine to boron phenolic resin is 0.3:1.

[0062] 304) placing the curable reaction solution in a sealed container, curing at 80° C. for 35 h to obtain a silicon-boron modified phenolic resin wet gel;

[0063] 305) The boron-silicon modified phenolic resin wet gel was subjected to gradient drying treatment, wherein the first temperature gradient was 40°C in the room, the second temperature gradient was 88°C, and the drying time of each gradient was 24h to obtain boron-silicon modified phenolic resin aerogel.

[0064] The molecular weight of the boron phenolic resin in this embodiment is 4000, and the boron content is 5%.

[0065] The molecular weight of the silicone resin is 2000, and its active functional group is a silicon-oxygen bond.

[0066] Example 4

[0067] 401) Add 15 g of boron phenolic resin into a sealable glass bottle, pour 35 g of isopropanol into the bottle, stir and dissolve at 50° C. to obtain a boron phenolic resin solution; the mass ratio of the boron phenolic resin to the organic solvent is 1:2.3.

[0068] 402) Add 4 g of silicone resin, 3 g of phenyltriethoxysilane and 0.3 mL of sulfuric acid to the boron phenolic resin solution, adjust the pH to 5.5, and stir at 50°C for 4 h to obtain a silicon-boron containing resin solution, wherein the sulfuric acid concentration is 0.5 mol / L; the mass ratio of silicone resin to boron phenolic resin is 0.27:1; the mass ratio of silicone to boron phenolic resin is 0.2:1.

[0069] 403) Add 4 g of hexamethylenetetramine to the silicon-boron resin solution, stir and dissolve at 50° C. to obtain a curable reaction solution; the mass ratio of hexamethylenetetramine to boron phenolic resin is 0.27:1.

[0070] 404) placing the curable reaction solution in a sealed container, curing at 90° C. for 20 h to obtain a silicon-boron modified phenolic resin wet gel;

[0071] 405) The boron-silicon modified phenolic resin wet gel was subjected to gradient drying treatment, wherein the first temperature gradient was 40°C, the second temperature gradient was 88°C, and the drying time of each gradient was 30 hours to obtain boron-silicon modified phenolic resin aerogel.

[0072] The molecular weight of the boron phenolic resin in this embodiment is 5000, and the boron content is 10%.

[0073] The molecular weight of the silicone resin is 2500, and its active functional group is a silicon-oxygen bond.

[0074] Example 5

[0075] 501) Add 30 g of boron phenolic resin into a sealable glass bottle, pour 80 g of isopropanol into the bottle, stir and dissolve at 50°C to obtain a boron phenolic resin solution; the mass ratio of the boron phenolic resin to the organic solvent is 1:2.6.

[0076] 502) Add 10 g of silicone resin, 8 g of phenyltriethoxysilane and 0.8 mL of hydrochloric acid to the boron phenolic resin solution, adjust the pH to 5.2, and stir at 50°C for 4 h to obtain a silicon-boron containing resin solution, wherein the concentration of hydrochloric acid is 1 mol / L; the mass ratio of silicone resin to boron phenolic resin is 0.33:1; the mass ratio of silicone to boron phenolic resin is 0.27:1.

[0077] 503) Add 8 g of hexamethylenetetramine to the silicon-boron resin solution, stir and dissolve at 50° C. to obtain a curable reaction solution; the mass ratio of hexamethylenetetramine to boron phenolic resin is 0.27:1.

[0078] 504) placing the curable reaction solution in a sealed container, curing at 70° C. for 40 h to obtain a silicon-boron modified phenolic resin wet gel;

[0079] 505) The boron-silicon modified phenolic resin wet gel was subjected to gradient drying treatment, wherein the first temperature gradient was 40°C, the second temperature gradient was 70°C, the first temperature gradient drying time was 20h, and the second temperature gradient drying time was 30h to obtain boron-silicon modified phenolic resin aerogel.

[0080] The molecular weight of the boron phenolic resin in this embodiment is 4000, and the boron content is 10%.

[0081] The molecular weight of the silicone resin is 2000, and its active functional group is a silicon-oxygen bond.

[0082] Comparative Example

[0083] The difference between Comparative Example 1 and Example 1 is that the boron phenolic resin is replaced by an equal amount of phenolic resin, and the molecular weight of the phenolic resin is 3500.

[0084] The difference between Comparative Example 2 and Example 1 is that the amount of isopropanol used is 75 g.

[0085] The difference between Comparative Example 3 and Example 1 is that the amount of isopropanol used is 25 g.

[0086] The difference between Comparative Example 4 and Example 1 is that 12 g of silicone resin and 6 g of methyltriethoxysilane are added to the boron phenolic resin solution.

[0087] The difference between Comparative Example 5 and Example 1 is that 3 g of silicone resin and 1.5 g of methyltriethoxysilane are added to the boron phenolic resin solution.

[0088] The difference between Comparative Example 6 and Example 1 is that the molecular weight of the boron phenolic resin is 3500 and the boron content is 15%.

[0089] The difference between Comparative Example 7 and Example 1 is that the molecular weight of the boron phenolic resin is 3500 and the boron content is 1%.

[0090] The difference between Comparative Example 8 and Example 1 is that gradient drying is not used, and drying is directly performed at 68° C. for 45 hours.

[0091] Performance Testing

[0092] The density and mechanical properties of the aerogels obtained in the examples and comparative examples were tested, wherein the density test was conducted in accordance with GB / T 6343-2009, and the compressive strength test was conducted in accordance with GB-T 1448-2005. The test results are shown in Table 1.

[0093] Table 1 Performance test results of embodiments and comparative examples

[0094]

[0095]

[0096] Through the performance comparison between the embodiment and comparative example 1, it is found that the aerogel obtained in the embodiment of the present application has a low density and a better compression strength. Figure 1-Figure 8 As can be seen from the attached drawings, the aerogel obtained in the present application is an aerogel with a three-dimensional ordered pore structure. Such a pore structure has a finer skeleton and a more stable pore structure. While ensuring low density, it also has excellent mechanical properties. In addition, the preparation method of the lightweight and high-strength three-dimensional ordered structure silicon-boron modified phenolic aerogel provided in the present application ultimately reduces the curing temperature to below 90°C, does not involve high temperature and high pressure reactions, and reduces the requirements for production equipment.

[0097] Furthermore, by analyzing the performance of Comparative Examples 2 and 3, it was found that when the solid content of the solution formed by the boron phenolic resin and the solvent in the preparation process was too high or too low, the product performance would decrease. This is because the boron phenolic resin solution with an appropriate solid content lays the foundation for the subsequent introduction of the silicon component and the formation of the pore structure skeleton, making the pore structure of the present application more stable, while ensuring low density, it also has excellent mechanical properties.

[0098] Combined with the performance of Comparative Examples 4 and 5, it is found that the addition of too much or too little silicon component leads to a decrease in product performance. This is because in the present application, the silicon component can improve the flexibility of the phenolic resin molecular chain, making the pore structure skeleton formed by it finer and denser, and the cured organic silicon resin, organic silicon and boron phenolic resin form physical entanglement and chemical bonding, so that the pore structure skeleton formed by it is finer and denser, thereby significantly increasing the flexibility of the phenolic resin molecular chain and greatly improving the mechanical properties of the aerogel. If the silicon component is too little, the silicon component cannot achieve the desired effect, and if the silicon component is too much, the physical entanglement and chemical bonding process will be out of control, which will affect the performance of the product.

[0099] In the technical solution of the present application, boron is introduced to improve the mechanical properties of the product. However, in combination with the performance of Comparative Examples 6 and 7, it is found that when too much or too little boron is introduced, the performance of the product, especially the compressive strength, decreases. This indicates that inappropriate boron content will affect the physical entanglement and chemical bonding between the silicon component and the phenolic resin.

[0100] In addition, analysis of the performance of Comparative Example 8 shows that, in the preparation process of the present application, gradient drying can prepare an aerogel material with a high specific surface area and a stable pore structure, otherwise it will cause the aerogel to shrink and the product will be unqualified.

[0101] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A lightweight, high-strength, three-dimensional ordered structured boron-silicon modified phenolic aerogel, characterized in that: The invention is made of raw materials including boron phenolic resin, organic solvent, organosilicon resin, organosilicon, acidic pH regulating liquid and cross-linking agent, wherein the mass ratio of the boron phenolic resin to the organic solvent is 1:(2.3-3.3), the molecular weight of the boron phenolic resin is 3000-5000, and the boron content is 2%-10%.

2. The lightweight, high-strength, three-dimensional ordered structured boron-silicon modified phenolic aerogel according to claim 1, characterized in that: The molecular weight of the organic silicon resin is 1000-2500, and the mass ratio of the organic silicon resin to the boron phenolic resin is (0.27-0.4):

1.

3. The lightweight, high-strength, three-dimensional ordered structured boron-silicon modified phenolic aerogel according to claim 1, characterized in that: The mass ratio of organosilicon to boron phenolic resin is (0.2-0.3):

1.

4. The lightweight, high-strength, three-dimensional ordered structured boron-silicon modified phenolic aerogel according to claim 3, characterized in that: The organic silicon is one of methyl orthosilicate, ethyl orthosilicate, methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane and phenyltriethoxysilane.

5. The lightweight, high-strength, three-dimensional ordered structured boron-silicon modified phenolic aerogel according to claim 1, characterized in that: The organic solvent is one of anhydrous ethanol, ethylene glycol or isopropanol;.

6. The lightweight, high-strength, three-dimensional ordered structured boron-silicon modified phenolic aerogel according to claim 1, characterized in that: The mass ratio of the cross-linking agent to the boron phenolic resin is (0.25-0.3):

1.

7. The lightweight, high-strength, three-dimensional ordered structured boron-silicon modified phenolic aerogel according to claim 6, characterized in that: The cross-linking agent is hexamethylenetetramine.

8. A method for preparing a lightweight, high-strength, three-dimensional ordered structured boron-silicon modified phenolic aerogel according to any one of claims 1 to 7, characterized in that: The following steps are involved: Adding the boron phenolic resin into an organic solvent and dissolving it at 45-55° C. to obtain a boron-containing phenolic resin solution; Adding organosilicon resin, organosilicon and acidic pH adjusting liquid to the boron-containing resin solution, dissolving at 45-55° C., to obtain a silicon-boron-containing resin solution; Adding hexamethylenetetramine to the silicon-boron resin solution and dissolving it at room temperature to obtain a curable reaction solution; The curable reaction liquid is placed in a sealed container and cured at 60-90° C. for 20-50 hours to obtain a silicon-boron modified phenolic resin wet gel; The boron-silicon modified phenolic resin wet gel is subjected to gradient drying to obtain the boron-silicon modified phenolic resin aerogel.

9. The method for preparing a lightweight, high-strength, three-dimensional ordered structured boron-silicon modified phenolic aerogel according to claim 8, characterized in that: The gradient drying of the silicon-modified phenolic wet gel is divided into two temperature gradients, the first temperature gradient is 20-40°C, the second temperature gradient is 68-88°C, and the drying time of each gradient is 15-30h.

10. The method for preparing a lightweight, high-strength, three-dimensional ordered structured boron-silicon modified phenolic aerogel according to claim 8, characterized in that: Add acidic pH adjusting solution to adjust the pH value to 4.5-5.5.

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