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

Abstract

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 10mm 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.