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

Here electrospinning and freeze-drying techniques are combined to fabricate an anisotropic SiC@SiO ceramic fiber aerogels (A-SiC@SiO-FAs). The anisotropic structure of the A-SiC@SiO-FAs features aligned layers stacking layer-by-layer with the same direction and highly oriented 1D fibers inside each layer. The A-SiC@SiO-FAs exhibit anisotropic thermal properties with an extremely low thermal conductivity of 0.018 W m K in the transverse direction (perpendicular to the SiC@SiO nanofibers) and ≈5 times higher thermal conductivity of 0.0914 W m K in the axial direction due to the highly oriented SiC@SiO nanofibers. The anisotropy factor of the A-SiC@SiO-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-FAs also have excellent thermal stability, maintaining structural integrity in oxidative environments at temperatures up to 1300C. Moreover, these structurally distinct A-SiC@SiO-FAs result in superior elastic deformation with a radial recoverable strain exceeding 60% and an axial specific modulus of 5.72 kN m kg. These findings emphasize the potential of SiC nanofiber aerogels in extreme thermal environments and provide valuable insights for designing anisotropic insulation materials.