Aerogels are ultralight materials in which a microporous solid is filled with a gas. Ceramic aerogels composed of nanowires or nanosheets, for example, can be lightweight and show high porosity in addition to low thermal conductivity and excellent thermal stability. These materials have possible applications, e.g., in heat insulation, catalysis, and filtration.

Hongjie Wang, Xi’an Jiaotong University, China, and colleagues have developed a strategy for the fabrication of SiC nanowire aerogels with complex, hierarchical structures. The team used direct ink writing to prepare templates based on short carbon fibers, which were then infiltrated with a siloxane gel and pyrolyzed at 1550 °C, leading to the growth of SiC nanowires. The templates are then removed in air at 700 °C to obtain the desired aerogels.

The shapes of the resulting SiC nanowire aerogels depend on those of the 3D-printed templates. This allowed the researchers to modify the densities and the mechanical properties of the aerogels by changing the printed structures, e.g., by printing square or hexagonal lattices. This could be used to prepare aerogels that are tailored to specific applications. The aerogels, for example, showed low thermal conductivity suitable for heat insulation applications.

• Additive Manufacturing of Resilient SiC Nanowire Aerogels,
  Pengfei Guo, Lei Su, Kang Peng, De Lu, Liang Xu, Mingzhu Li, Hongjie Wang,
  ACS Nano 2022.
  https://doi.org/10.1021/acsnano.2c01039