Multiscale mullite fiber/whisker reinforced silica aerogel nanocomposites with enhanced compressive strength and thermal insulation performance

Abstract The multiscale architecture of the mullite fiber/mullite whisker was fabricated and applied for reinforcing silica aerogel. The mullite whisker could successfully grow on the mullite fiber, with a length of 5–10 μm and a diameter of about 100 nm. The mullite fiber/mullite whisker could be well-embedded in silica aerogel, which hold a mesoporous structure and a high specific surface area of 916.67 m2/g. The as-prepared mullite fiber/mullite whisker/silica aerogel possessed a low thermal conductivity of 0.034 W/(m·K) and a low density of 0.270 g/cm3. Thanks to the interface enhancement and the stress dispersion from the introduction of mullite whisker, the compressive stress of mullite fiber/mullite whisker/silica aerogel composite was 1.32 MPa (30% compression strain), 187% higher than that of the composite without mullite whiskers, meanwhile, a high resilience rate of 88.5% was maintained. The lightweight, heat-insulating, compression resilient composite exhibits huge prospects as the thermal barrier in the heat preservation field, especially in aerospace and aviation insulation.