Pore Defect Modulation Enables Excellent Mechanical Properties in Oxide Ceramic Nanofiber Aerogels for Long-Term Thermal Insulation

Ultralight oxide ceramic nanofiber aerogels are widely used as thermal protection materials due to their excellent structural and functional properties. However, the presence of numerous pore defects in nanofibers can easily lead to brittle fracture or even pulverization of nanofiber aerogels due to stress concentration under external force, and this problem might lead to catastrophic accidents, which is currently a great challenge for oxide ceramic nanofiber aerogels currently. Here, we propose a pore defect regulation strategy, which realizes the effective regulation of microstructure on a ceramic nanofiber by strictly controlling the content of organic components in the ceramic nanofiber precursor, thus avoiding generating numerous pore defects during the ceramization process. The zirconia ceramic nanofiber aerogel prepared as a proof-of-concept exhibits temperature-invariant superelasticity (up to 1300 °C) and fatigue resistance against thousands of compressions, which remains superelastic after 1 week of holding time at 1000 °C, and the thermal conductivity is only 0.026 W m–1 K–1. This research provides insights into developing advanced oxide ceramic materials that can be used for long periods of time in high-temperature environments.