A research group led by Prof. WANG Zhenyang and ZHANG Shudong from the Hefei Institutes of Physical Science of the Chinese Academy of Sciences has developed a new type of ceramic fiber aerogel, SiC@SiO₂, which exhibits highly anisotropic thermal conductivity and exceptional thermal stability through directional bio-inspired design. 

The work was published in Advanced Science.

In nature, many biological structures, such as wood's vascular systems or the layered architecture of silkworm cocoons, demonstrate directional heat management thanks to their well-organized internal structures. 

Inspired by these natural designs, the team employed a bio-inspired fabrication strategy to create aerogels with similarly ordered architecture. They used electrospinning and freeze-drying techniques to fabricate a highly ordered structure. The process began with the synthesis of thermally stable SiC nanofibers, known for their excellent chemical resilience. An amorphous SiO₂ shell was then built around these fibers, forming a phonon barrier that facilitates both intra-layered alignment and inter-layered stacking, resulting in the highly oriented SiC@SiO₂ ceramic fiber aerogel.

The anisotropic aerogel demonstrates ultralow cross-plane thermal conductivity as low as 0.018 W/m·K, and an anisotropy coefficient as high as 5.08, surpassing the performance of comparable materials. 

In addition to thermal performance, the aerogel shows excellent mechanical resilience, with radial elastic deformation over 60% and axial specific modulus reaching 5.72 kN·m/kg

Most impressively, it maintains structural and functional stability across an ultra-wide temperature range from -196°C to 1,300°C, making it a ideal candidate for aerospace, energy systems, and other extreme environments where advanced thermal insulation is critical.  

This work offers a new pathway for developing ultralight, high-performance insulation materials for demanding applications, according to the team. 

Lightweight and compression properties of highly oriented SiC@SiO₂ nanofiber aerogel (Image by LIU Cui)

Anisotropic thermal conductivity and extreme thermal stability of highly oriented SiC@SiO₂ nanofiber aerogel (Image by LIU Cui)