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

Abstract

The application relates to the technical field of aerogels, in particular to a lightweight high-strength three-dimensional ordered structure silicon-boron modified phenolic aerogel and a preparation method thereof. The aerogel is made of raw materials including boron phenolic resin, an organic solvent, an organic silicon resin, organic silicon, an acidic pH adjusting liquid and a crosslinking agent, the mass ratio of the boron phenolic resin and the organic solvent is 1:(2.3-3.3), the molecular weight of the boron phenolic resin is 3000-5000, and the boron element content is 2%-10%; the aerogel forms a three-dimensional ordered pore structure. The aerogel has the characteristics of small shrinkage, high compressive 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 structure 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 nanoporous 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 aircraft from extreme temperatures. However, the temperature resistance of phenolic aerogel is limited, and its volume shrinks severely after high-temperature carbonization, and its 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 phenolic aerogel dried at room temperature and its preparation method. The method uses linear phenolic resin as the main raw material, silane as a grafting agent, and reacts at 75-120°C. An organic solvent and a curing agent are added, and the reaction is cured at 70-180°C. The phenolic aerogel is then dried at room temperature to produce a low-shrinkage phenolic aerogel. This method is simple to prepare, but requires an autoclave as the container, and the curing reaction temperature must reach a maximum of 120°C.

[0004] CN117624514A discloses a water-based boron-modified phenolic aerogel and its preparation method. It uses linear phenolic compounds and aldehyde compounds as raw materials, water as the main reaction solvent, and an acidic boron source as a boron modifier and catalyst. After heating, 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 (0.38-0.47g / cm 2 ).

[0005] CN118978703A discloses a boron-containing polysilsesquioxane, a modified aerogel, and a boron-silicon hybrid phenolic-based composite material, as well as its preparation method and application. The composite material uses phenolic resin as the main raw material, adds the boron-containing polysilsesquioxane, uses methanol as a pore-forming agent, and uses benzenesulfonyl chloride as a catalyst for curing. The resulting composite material is then dried at room temperature and pressure to produce a heat-resistant and thermally stable phenolic aerogel. The phenolic aerogel prepared by this method has low thermal conductivity (0.0477 W / m·K), but the process is relatively complex and results in low compressive strength (1.76 MPa).

[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 structure silicon-boron modified phenolic aerogel and a preparation method thereof. Summary of the Invention

[0009] The present application provides a lightweight, high-strength, three-dimensional ordered structure silicon-boron modified phenolic aerogel and a preparation method thereof, which solves the technical problem in the prior art that the low density, high mechanical properties and simple and safe synthesis route of the phenolic aerogel cannot be 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 structure of silicon-boron modified phenolic aerogel, which adopts the following technical solution:

[0011] A lightweight, high-strength, three-dimensional ordered structured silicon-boron modified phenolic aerogel is made from raw materials including boron phenolic resin, an organic solvent, an organosilicon resin, organosilicon, an acidic pH regulating 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 boron phenolic resin has a molecular weight of 3000-5000 and a boron content of 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 isopropyl alcohol.

[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 regulating liquid to the boron-containing resin solution and dissolving at 45-55° C. to obtain a silicon-boron-containing resin solution;

[0022] adding hexamethylenetetramine to the borosilicate 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., and the second temperature gradient is 68-88° C., and the drying time of each gradient is 15-30 hours.

[0026] Furthermore, an acidic pH regulating 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 this 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 this application produces less or no volatilization of highly toxic gases during implementation, and has little impact on the health of the operator.

[0030] 3、The aerogel obtained in the application is an aerogel with three-dimensional ordered pore structure, the pore structure skeleton of which is more fine and stable, and the aerogel has excellent mechanical properties while ensuring low density. The three-dimensional ordered pore structure can be formed by virtue of the boron phenolic resin with fixed molecular weight and boron content, and after the boron phenolic resin 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 molecular chain of the phenolic resin, so that the pore structure skeleton formed by the phenolic resin is more fine; the physical entanglement and chemical bonding between the cured organosilicon resin and the organosilicon and the boron phenolic resin make the pore structure skeleton formed by the phenolic resin more fine, so that the flexibility of the molecular chain of the phenolic resin is significantly increased, and the mechanical properties of the aerogel are greatly improved; in addition, in the preparation process, the gradient drying used in the application can prepare an aerogel material 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, and the curing time of the boron phenolic resin is short, so as to enable the silicon source to hydrolyze active silicon hydroxyl in a short period of time, and an acidic pH adjusting liquid with high hydrolysis efficiency is selected. Moreover, the acidic pH adjusting liquid of the application can make the curing time of the silicon component match the curing time of the phenolic resin, so as to achieve the best curing effect. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 A physical picture of the lightweight high-strength three-dimensional ordered structure silicon-boron modified phenolic aerogel obtained in Example One;

[0032] Figure 2 A scanning electron microscope picture of the lightweight high-strength three-dimensional ordered structure silicon-boron modified phenolic aerogel obtained in Example One;

[0033] Figure 3 A scanning electron microscope picture of the lightweight high-strength three-dimensional ordered structure silicon-boron modified phenolic aerogel obtained in Example One;

[0034] Figure 4 A pore size distribution picture of the lightweight high-strength three-dimensional ordered structure silicon-boron modified phenolic aerogel obtained in Example One;

[0035] Figure 5 A physical picture of the lightweight high-strength three-dimensional ordered structure silicon-boron modified phenolic aerogel obtained in Example Two;

[0036] Figure 6 A scanning electron microscope picture of the lightweight high-strength three-dimensional ordered structure silicon-boron modified phenolic aerogel obtained in Example Two;

[0037] Figure 7 An EDS element analysis picture of the lightweight high-strength three-dimensional ordered structure silicon-boron modified phenolic aerogel obtained in Example Two;

[0038] Figure 8This is the pore size distribution diagram of the lightweight, high-strength, three-dimensional ordered structure silicon-boron 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 examples.

[0040] Example 1

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

[0042] 101) Add 15 g of boron phenolic resin to a sealable glass bottle, pour 50 g of isopropyl alcohol 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 organosilicon resin, 3 g of methyltriethoxysilane, and 0.75 mL of hydrochloric acid to the boron phenolic resin solution, adjust the pH to 4.5, and stir at 50°C for 4 h to obtain a silicon-boron containing resin solution, wherein the hydrochloric acid concentration is 0.5 mol / L; the mass ratio of organosilicon resin to boron phenolic resin is 0.4:1; the mass ratio of organosilicon 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, with the first temperature gradient being 20° C., the second temperature gradient being 68° C., the first temperature gradient drying time being 30 h, and the second temperature gradient drying time being 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, the preparation method of which includes the following steps:

[0051] 201) Add 20 g of boron phenolic resin into a sealable glass bottle, pour 60 g of isopropyl alcohol 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) To the boron phenolic resin solution, 6 g of organosilicon resin, 6 g of methyltriethoxysilane, and 0.85 mL of acetic acid were added, the pH was adjusted to 4.9, and the mixture was stirred at 50°C for 4 h to obtain a boron-silicon-containing resin solution, wherein the acetic acid concentration was 1 mol / L; the mass ratio of organosilicon resin to boron phenolic resin was 0.3:1; and the mass ratio of organosilicon to boron phenolic resin was 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 boron-silicon modified phenolic resin wet gel;

[0055] 205) The boron-silicon modified phenolic resin wet gel was subjected to gradient drying treatment, with the first temperature gradient being 20°C, the second temperature gradient being 88°C, the first temperature gradient drying time being 15h, and the second temperature gradient drying time being 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 the silicone resin is 1000, and its active functional group is a silicon-oxygen bond.

[0058] Example 3

[0059] 301) Add 20 g of boron phenolic resin into a sealable glass bottle, pour 50 g of isopropyl alcohol 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 1:2.5.

[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 the silicone resin to the boron phenolic resin is 0.4:1; and the mass ratio of the silicone to the 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 boron-silicon modified phenolic resin wet gel;

[0063] 305) The silicon boron modified phenolic resin wet gel was subjected to gradient drying treatment, with the first temperature gradient being 40°C at room temperature, the second temperature gradient being 88°C, and the drying time for each gradient being 24 hours to obtain silicon boron 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 isopropyl alcohol 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 1:2.3.

[0068] 402) Add 4 g of organosilicon 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 organosilicon resin to boron phenolic resin is 0.27:1; and the mass ratio of organosilicon 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 boron-silicon modified phenolic resin wet gel;

[0071] 405) The boron-silicon modified phenolic resin wet gel was subjected to gradient drying treatment, with the first temperature gradient being 40°C, the second temperature gradient being 88°C, and the drying time for each gradient being 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 isopropyl alcohol 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 1:2.6.

[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 hydrochloric acid concentration is 1 mol / L; the mass ratio of the silicone resin to the boron phenolic resin is 0.33:1; and the mass ratio of the silicone to the 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 boron-silicon modified phenolic resin wet gel;

[0079] 505) The silicon boron modified phenolic resin wet gel was subjected to gradient drying treatment, with the first temperature gradient being 40°C, the second temperature gradient being 70°C, the first temperature gradient drying time being 20h, and the second temperature gradient drying time being 30h to obtain silicon boron 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 isopropyl alcohol used is 75 g.

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

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

[0087] The difference between Comparative Example 5 and Example 1 is that 3g of silicone resin and 1.5g of methyltriethoxysilane were 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 the product is directly dried 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. 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 examples 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. Figures 1-8 As can be seen from the accompanying drawings, the aerogel obtained in this application has a three-dimensional ordered pore structure. This pore structure has a denser skeleton and a more stable pore structure, ensuring low density while also possessing excellent mechanical properties. Furthermore, the method for preparing a lightweight, high-strength, three-dimensional ordered silicon-boron-modified phenolic aerogel provided in this application ultimately reduces the curing temperature to below 90°C, eliminating the need for high-temperature and high-pressure reactions and reducing the requirements for production equipment.

[0097] Furthermore, analysis of the performance of Comparative Examples 2 and 3 revealed 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 decreased. 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] Combining the performance of Comparative Examples 4 and 5, it was found that adding too much or too little silicon component resulted in 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 resulting pore structure framework finer and denser. Moreover, after curing, the organosilicon resin and the boron phenolic resin form physical entanglements and chemical bonds, forming a finer and denser pore structure framework, thereby significantly increasing the flexibility of the phenolic resin molecular chain and greatly improving the mechanical properties of the aerogel. However, too little silicon component results in the silicon component failing to achieve the desired effect, while too much silicon component can lead to uncontrolled physical entanglement and chemical bonding processes, which in turn affects product performance.

[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 the amount of boron introduced is too much or too little, the performance of the product, especially the compressive strength, decreases. This shows that an 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 produce 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 non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A lightweight, high-strength, three-dimensional ordered structured boron-silicon modified phenolic aerogel, characterized in that: The invention is prepared from raw materials including boron phenolic resin, organic solvent, organosilicon resin, organosilicon, acidic pH regulating liquid and 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 boron content is 2%-10%. The mass ratio of the organosilicon resin to the boron phenolic resin is (0.27-0.4):1, the mass ratio of the organosilicon to the boron phenolic resin is (0.2-0.3):1, the molecular weight of the organosilicon resin is 1000-2500, and the organosilicon is one of methyl orthosilicate, ethyl orthosilicate, methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane and phenyltriethoxysilane. In the process of preparing the boron-silicon-modified phenolic aerogel, a boron-silicon-modified phenolic resin wet gel is first prepared, and the boron-silicon-modified phenolic resin wet gel is subjected to a gradient drying treatment to obtain the boron-silicon-modified phenolic aerogel.

2. 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 isopropyl alcohol.

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 the cross-linking agent to the boron phenolic resin is (0.25-0.3):

1.

4. The lightweight, high-strength, three-dimensional ordered structured boron-silicon modified phenolic aerogel according to claim 3, characterized in that: The cross-linking agent is hexamethylenetetramine.

5. A method for preparing a lightweight, high-strength, three-dimensional ordered structure silicon-boron modified phenolic aerogel according to any one of claims 1 to 4, 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 regulating liquid to the boron-containing resin solution and dissolving at 45-55° C. to obtain a silicon-boron-containing resin solution; Adding hexamethylenetetramine to the borosilicate 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 boron-silicon 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.

6. The method for preparing a lightweight, high-strength, three-dimensional ordered structure boron-silicon modified phenolic aerogel according to claim 5, characterized in that: The gradient drying of the boron-silicon modified phenolic resin wet gel is divided into two temperature gradients, the first temperature gradient is 20-40°C, and the second temperature gradient is 68-88°C. The drying time of each gradient is 15-30 hours.

7. The method for preparing a lightweight, high-strength, three-dimensional ordered structure boron-silicon modified phenolic aerogel according to claim 5, characterized in that: Add acidic pH adjusting solution to adjust the pH value to 4.5-5.5.

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