Bubble-Templated Assembly of Ceramic Nanofibrous Aerogels: Effects of Fiber Content on Microstructure, Mechanical Properties, and Thermal Insulation Performance

Lightweight ceramic nanofibrous aerogels with elastic 3D networks show a strong potential for thermal insulation. As the main structural units, nanofibers play a key role in determining the aerogel integrity and performance. In this study, a ceramic nanofibrous aerogel was prepared via a bubble-templated assembly strategy. Nanofibers assembled at the gas-liquid interface to form a foam template, followed by freeze-drying and heat treatment. The effects of fiber content on the aerogel's structure, mechanical behavior, and thermal insulation were systematically examined. The results indicated that a higher nanofiber content increased the number of nanofibers at junction points within the aerogel, resulting in a denser 3D network structure and a reduction in the pore size. Meanwhile, its density increased from 50.08 to 63.95 mg/cm³, while the porosity decreased from 96.59 to 95.68%. Mechanical evaluations indicated that all aerogels were able to fully recover their original shape, even under 60% compressive strain. As the nanofiber content increased, the fatigue resistance of the aerogel first improved and then declined. At the same time, thermal insulation performance deteriorated, with thermal conductivity increasing from 0.0364 to 0.0466 W/(m·K). This study offers valuable insights into optimizing the microstructure and properties of ceramic nanofibrous aerogels prepared by using the direct foaming method.