Thermal insulation characteristics of a lightweight, porous nanomaterial in high-temperature environments

Thermal-insulating nanomaterials with excellent thermal insulation performance are one type of thermal protection material used in spacecraft. In this study, the high-temperature insulation characteristics of a lightweight, porous aluminum oxide (Al₂O₃) nanomaterial were studied through experimentation using a self-developed thermal testing system for high-speed spacecraft, and were calculated by numerical simulation. The results showed that in a 1200 °C front-surface, high-temperature environment, an Al₂O₃ nanomaterial sheet with a thickness of only 10 mm could reduce the temperature by over 70% while exhibiting stable thermal insulation performance. This demonstrates that the Al₂O₃ nanomaterial has excellent high-temperature insulation performance. The scanning electron microscopy (SEM) images showed that, after the temperature exceeded 1200 °C, the aggregation and growth of the Al₂O₃ nanoparticles accelerated, and single Al₂O₃ nanoparticles and voids increased significantly in size; in addition, the fibers inside the material started to melt, and the cracks started to increase considerably in number, depth, and width. Furthermore, a significant contraction and bending deformation occurred at the edges of the Al₂O₃ nanomaterial sheet; therefore, the Al₂O₃ nanomaterial is suitable for use in a thermal environment below 1200 °C. The results provide an important reference basis for the design of thermal protection systems for spacecraft.