Highly Oriented SiC@SiO 2 Ceramic Fiber Aerogels with Good Anisotropy of the Thermal Conductivity and High‐Temperature Resistance

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.