Direct 3D Electrospinning of Phase-Locked Amorphous/Crystalline Ceramic Fiber Aerogels with Enhanced Mechanical Properties and Thermal Stability

Ceramic fiber aerogels have emerged as promising candidates for thermal insulation in extreme environments, yet their mechanical toughness and high-temperature stability remain critical bottlenecks. To address this challenge, we propose a multiscale structural engineering strategy integrated with scalable direct three-dimensional (3D) electrospinning technology to fabricate silicon–aluminum ceramic fiber aerogels (SACFAs) with a phase-locked amorphous/crystalline architecture. The entangled network constructed by crimped ribbon-shaped fibers reinforces the fiber junctions and provides ample deformation space. Concurrently, aluminum doping introduces Si–O–Al bonds and forms a phase-locked structure wherein nano-alumina/mullite crystallites are uniformly embedded within the amorphous silica matrix. This unique architecture intrinsically reinforces the fibers through grain boundary pinning, thereby synergistically enhancing both mechanical properties and thermal stability. The SACFAs exhibit a superior combination of tensile performance (a high tensile strength of 0.4772 MPa with a fracture strain of 47.58%), compressive resilience (complete recovery after 80% compressive strain, corresponding to a maximum compressive stress of 120.92 kPa), and near-zero Poisson’s ratio. The material maintains stable mechanical properties from −196 °C to 1200 °C, with a low thermal conductivity of 0.03254 W·m −1 ·K −1 , a low density of 22.70 mg·cm −3 , and a high porosity of 98.72%. Additionally, the direct 3D electrospinning method delivers a single-nozzle production rate of 1800 cm 3 ·h −1 , highlighting its scalability for industrial production. This work provides a promising strategy for developing lightweight, flexible thermal insulation materials for aerospace and advanced energy applications. Graphical