关键词: 碳粘结碳纤维复合材料, 隔热, 抗烧蚀, 力学性能, 涂层改性

Abstract: Carbon-bonded carbon fiber (CBCF) composites, renowned for their lightweight, thermal insulation properties, high-temperature resistance (>2,800 ℃), and stable thermomechanical performance, have emerged as key materials in the aerospace, defense, and other related fields. However, CBCF composites are susceptible to oxidation in high-temperature aerobic environments, leading to a rapid degradation in their properties and thus constraining their practical applications. Therefore, the development of effective protective modification methods is of utmost importance. Existing studies have demonstrated that the introduction of ultra-high temperature oxidation-resistant ceramic particles can effectively enhance the oxidation resistance of composites. Incorporating boron (B) elements into the matrix is an effective modification method that can simultaneously enhance the mechanical properties and high-temperature oxidation resistance of CBCF materials. The mechanism lies in the fact that, under high-temperature oxidative conditions, B elements generate an in-situ, flowable B2O3 glassy protective layer. This coating not only effectively blocks oxygen diffusion, but also repairs micro-cracks on the material surface through self-healing, thereby significantly slowing down the high-temperature oxidative degradation rate of the polymer. TiO2 crystals exhibit excellent oxidation resistance and heat resistance, showcasing unique advantages in the field of infrared shading. Using its excellent infrared blocking properties, TiO2 can not only efficiently shield a large amount of radiant energy, but also achieve reverse heat transfer, playing a crucial role in thermal management, energy conversion, and other fields. To address the weak chemical bonding defects of TiO2, the co-gel method can be employed to strengthen the cross-linked structure and achieve microstructural control. In addition, aerogels, due to their unique nanoporous structure, possess ultra-low thermal conductivity, making them excellent thermal insulation materials. Based on the above principles, this study devised a multi-scale structure construction strategy. Firstly, a dense and uniform TiO2-B2O3 ceramic coating was formed on the carbon fiber surfaces of CBCF via the co-gel method to effectively block the corrosion of the material. Subsequently, phenolic aerogels were in-situ constructed within the material using the sol-gel technique to repair the defects in the material and further reduce internal thermal conduction, thereby enhancing its thermal insulation capability. The results show that the prepared CBCF/TB-PR composites exhibit excellent performance in terms of mechanical properties, thermal insulation properties, and ablation resistance, and have a broad engineering application prospect in thermal protection for hypervelocity vehicles, aerospace re-entry vehicles, rockets, and other related fields.

Key words: carbon-bonded carbon fiber composites, thermal insulation, ablation resistance, mechanical properties, coating modification