Influence of Three-Dimensional Skeletal Support by Different Fiber Felts on Thermal Protection Properties of Aerogel Composites

The rapid development of the aerospace industry urgently requires high-performance lightweight ablators to provide cost-effective thermal protection. Herein, we selected three fiber felts as the reinforcing materials and prepared three aerogel composites by a multistage robust strategy of sol–gel and polymerization-induced phase separation. The relationship between the molecular structure of the fiber felt and the properties of the composite was investigated. We mainly focused on the differences in pyrolysis behavior and reinforcement effect of the three fiber felts in the environment of high-speed high-temperature oxygenated gas flow. The results show that under low heat flow, high-silica fiber felt and mullite fiber felt have a better three-dimensional skeleton support effect due to their own oxidation resistance, while carbon fiber felt is more excellent under high heat flow due to its high melting point. This work can provide guidance for the selection of fiber felt in the preparation of a new generation of ablators.