Electromagnetic wave transparent BN composite nanobelts aerogel with improved thermal insulation property

As the speed of the aircraft increases, the shell of the aircraft faces the challenge of high temperatures due to aerodynamic heating. Thus, high-performance thermal insulators with exceptional thermal stability and electromagnetic wave-transparent properties are attracting more and more attention. BN aerogel is an ideal candidate for thermal insulators in wave transparency fields due to the low thermal conductivity and simultaneous electrical insulation. However, the poor thermal stability of BN aerogel in the air restricts the practical application. Herein, in this work, we prepared a Si-N-O or Si-B-N-O amorphous ceramic layer on the surface of BN nanobelts to block the oxidation of BN. The oxidation resistance temperature of BN/Si-N-O and BN/Si-B-N-O composite aerogels was up to 800°C and 900°C, respectively. Remarkably, such composite aerogel still presented low dielectric loss and thermal conductivity at both room temperature and high temperature, which was expected to be flame-erosion resistance and electromagnetic wave-transparent thermal insulators for high-temperature applications. Such an idea of preparing BN composite aerogels can offer a strategy for developing and manufacturing advanced aerogels and further expanding their applications in harsh environments.