CN-121991401-A - Ablation-resistant carborane phenolic aerogel and preparation method thereof

Abstract

The invention discloses an ablation-resistant carborane phenolic aerogel and a preparation method thereof, and belongs to the technical field of aerogel materials. The invention aims to solve the technical problems that the existing phenolic aerogel is insufficient in ablation resistance and the carborane phenolic aerogel is difficult to prepare, and the main chain carborane structure-containing phenolic aerogel is prepared by performing sol-gel reaction on meta-carborane bisphenol monomer and formaldehyde under the catalysis of strong alkali, and sequentially performing gelation, solvent replacement and supercritical drying. The invention can obviously improve the residual weight rate and the ablation resistance of the aerogel in nitrogen and air atmosphere, and is suitable for the field of external heat-proof and heat-insulating materials.

Inventors

• LIU TAO
• HE LIJUAN
• ZHU YUE
• ZHANG SHIZHONG
• LI WENJING
• HUANG HONGYAN

Assignees

• 航天特种材料及工艺技术研究所

Dates

Publication Date

20260508

Application Date

20251223

Claims (10)

1. 1. The preparation method of the ablation-resistant carborane phenolic aerogel is characterized by comprising the following steps of: 1) Dissolving meta-carborane bisphenol monomer, formaldehyde aqueous solution and strong alkali in an organic solvent to obtain a uniform composite solution; 2) Pouring the composite solution into a mold, and heating to carry out gelation reaction to obtain carborane phenolic wet gel; 3) And (3) performing solvent replacement and supercritical drying on the carborane phenolic wet gel to obtain the carborane phenolic aerogel.
2. 2. The method of claim 1, wherein the meta-carborane bisphenol monomer has the formula: 。
3. 3. the method of claim 1, wherein the molar ratio of meta-carborane bisphenol monomer to formaldehyde in the composite solution is 1:2.4-4.
4. 4. The method of claim 1, wherein the strong base is NaOH or KOH.
5. 5. The method of claim 1 or 4, wherein the molar ratio of meta-carborane bisphenol monomer and strong base in the composite solution is 1:0.05-0.2.
6. 6. The method of claim 1, wherein the organic solvent is one or more of n-butanol, n-pentanol, 2-methyl-2, 4-pentanediol, or a mixture thereof in any ratio.
7. 7. The method of claim 1, wherein the solids content of the composite solution is 20% -50%.
8. 8. The method of claim 1, wherein the gelation reaction is carried out at a temperature of 120 to 180 ℃ for a time of 8 to 96 hours.
9. 9. The method of claim 1, wherein the solvent used in the solvent displacement is ethanol or acetone.
10. 10. An ablation resistant carborane phenolic aerogel prepared by the process of any one of claims 1 to 9.

Description

Ablation-resistant carborane phenolic aerogel and preparation method thereof Technical Field The invention relates to an ablation-resistant carborane phenolic aerogel and a preparation method thereof, and belongs to the technical field of aerogel materials. Background Phenolic resin is an organic resin material with the advantage of high carbon residue rate, and is commonly used as a resin matrix of an ablative thermal protection composite material. With the trend of the novel heat protection material towards light weight and multifunctional integration, phenolic aerogel and a composite material thereof are developed through a sol-gel technology, the organic combination of ablation heat protection and excellent heat insulation performance is realized, and engineering application is realized. However, when the phenolic aerogel composite material is used for a long time in an aerobic environment, the problems of poor oxidation resistance and high quality ablation rate exist, and ablation resistance modification is needed. The boron element is introduced into a phenolic resin system, and the carbon generated by high-temperature pyrolysis of the liquid film bundle formed by high-temperature melting of the boron oxide is one of important ways for improving the oxidation resistance of the phenolic resin. The common B element modification is mainly to graft boron-containing functional groups on the side chains of phenolic resin or to physically dope boron-containing compounds, and the improvement of the oxidation resistance of the phenolic resin is not ideal due to the limited residual impurity amount. Carborane is a regular icosahedron cage structure composed of 2C atoms and 10B atoms, and can be introduced into a main chain structure of phenolic resin, so that the oxidation resistance of the phenolic resin can be greatly improved. Ji Shicheng et al report that carborane bisphenol, formaldehyde and a base catalyst are taken as raw materials to synthesize carborane phenolic oligomer first, and then the carborane phenolic oligomer is cured at a high temperature to obtain carborane phenolic resin, wherein the residual weight rate of the carborane phenolic resin at 900 ℃ can reach 88.9% under the air atmosphere, and the carborane phenolic resin shows excellent oxidation resistance (journal of aviation materials, vol.34, no.1, february 2014). The carborane phenolic aldehyde is prepared into the aerogel material, so that the oxidation resistance of the phenolic aerogel and the thermal protection composite material thereof is greatly improved, and the application range of the phenolic aerogel is widened. At present, no report exists on carborane phenolic aerogel. Disclosure of Invention The invention aims to overcome the defects of the prior art and provides an ablation-resistant carborane phenolic aerogel and a preparation method thereof. In order to achieve the above purpose, the technical scheme adopted by the invention is as follows. The preparation method of the ablation-resistant carborane phenolic aerogel comprises the following steps: 1) Dissolving meta-carborane bisphenol monomer, formaldehyde aqueous solution and strong alkali in an organic solvent to obtain a uniform composite solution; 2) Pouring the composite solution into a mold, and heating to carry out gelation reaction to obtain carborane phenolic wet gel; 3) And (3) performing solvent replacement and supercritical drying on the carborane phenolic wet gel to obtain the carborane phenolic aerogel. Further, the meta-carborane bisphenol monomer has a structural formula: 。 Further, the molar ratio of meta-carborane bisphenol monomer to formaldehyde of the composite solution is 1:2.4-4. If the proportion of formaldehyde is too high, the thermal stability of the prepared carborane phenolic aerogel is poor, and if the proportion of formaldehyde is too low, the reaction system is difficult to gel. Further, the strong base is NaOH or KOH. Further, the molar ratio of the meta-carborane bisphenol monomer to the strong base of the composite solution is 1:0.05-0.2. If the proportion of the alkali is too high, the prepared carborane phenolic aerogel is in a hard and brittle state and is easy to crack, and if the proportion of the alkali is too low, the reaction system is difficult to gel. Further, the organic solvent is one or a mixture of more of n-butanol, n-amyl alcohol and 2-methyl-2, 4-pentanediol in any proportion. Further, the solid content of the composite solution is 20% -50%. If the solid content is too high, the prepared carborane phenolic aerogel has high density and loses the advantage of low density, and if the solid content is too low, the obtained carborane phenolic wet gel has poor strength, is easy to crack after supercritical drying and is severely shrunk. Further, the temperature of the gelation reaction is 120-180 ℃ and the time is 8-96 h. If the reaction temperature is too low, the wet gel reaction degree is insufficient, the obtained carborane