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

Thermal-insulating nanomaterialswith 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 degrees 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 degrees 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, andwidth. 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 below1200 degrees C. The results provide an important reference basis for the design of thermal protection systems for spacecraft. (C) 2017 Elsevier Ltd. All rights reserved.