Highly Oriented SiC@SiO <sub>2</sub> Ceramic Fiber Aerogels with Good Anisotropy of the Thermal Conductivity and High‐Temperature Resistance
Zheng Zhang, Cui Liu, Nian Li, Wei Guo, Ying Li, Pengzhan Yang, S.Y. Zhang, Zhenyang Wang
Abstract
Abstract Here electrospinning and freeze‐drying techniques are combined to fabricate an anisotropic SiC@SiO 2 ceramic fiber aerogels (A‐SiC@SiO 2 ‐FAs). The anisotropic structure of the A‐SiC@SiO 2 ‐FAs features aligned layers stacking layer‐by‐layer with the same direction and highly oriented 1D fibers inside each layer. The A‐SiC@SiO 2 ‐FAs exhibit anisotropic thermal properties with an extremely low thermal conductivity of 0.018 W m −1 K −1 in the transverse direction (perpendicular to the SiC@SiO 2 nanofibers) and ≈5 times higher thermal conductivity of 0.0914 W m −1 K −1 in the axial direction due to the highly oriented SiC@SiO 2 nanofibers. The anisotropy factor of the A‐SiC@SiO 2 ‐FAs is as high as 5.08, which exceeds most of the currently reported thermal insulation materials with anisotropic structural design, such as anisotropic wood aerogels, biaxially anisotropic PI/BC aerogels and anisotropic MXene foam, etc. The A‐SiC@SiO 2 ‐FAs also have excellent thermal stability, maintaining structural integrity in oxidative environments at temperatures up to 1300 ° C. Moreover, these structurally distinct A‐SiC@SiO 2 ‐FAs result in superior elastic deformation with a radial recoverable strain exceeding 60% and an axial specific modulus of 5.72 kN m kg −1 . These findings emphasize the potential of SiC nanofiber aerogels in extreme thermal environments and provide valuable insights for designing anisotropic insulation materials.