Carbon-Nanotube-Doped Aerogels Comprised of Ordered Curvature Nanofibers with Polysilazane as Shell and Nomex as Core for Crack-Resistant Thermally Insulating Structural Composites

The polymer-derived ceramics (PDCs) aerogels have been extensively employed in the field of high-temperature thermal insulation with unique nanoporous structures and excellent chemical stability. However, conventional ceramic aerogels were susceptible to structural collapse and volume shrinkage during the pyrolysis process, leading to strength degradation and reduced thermal insulation. In this article, an ordered curvature structure was fabricated to avoid the defects of inferior mechanical properties of composites caused by the shrinkage of ceramic precursor polymers during the pyrolysis process. The ceramic fiber aerogel composites with ordered curvature were obtained through off-center coaxial electrospinning combined with a ceramic precursor transformation. The effective load transfer along the axial direction of the helical fibers facilitated rapid stress dissipation in the ceramic fiber aerogel during pyrolysis, thereby preventing structural damage. The multilayered heterogeneous interfaces within the fibers imparted exceptional thermal insulation properties to the aerogels (0.0349 W/m·K). The unique load transfer mechanism and nanoporous structure endowed the aerogel with excellent mechanical properties, allowing it to exhibit significant structural stability under high-temperature reversible cycle compression. The excellent mechanical and thermal insulation properties of ceramic fiber aerogels render them a promising wide range of applications in high-temperature thermal protection systems.