Thermal insulated and mechanical enhanced silica aerogel nanocomposite with in-situ growth of mullite whisker on the surface of aluminum silicate fiber

Fiber-reinforced silica aerogel composite has attracted increasing attention in thermal insulation area. Nevertheless, the suboptimal mechanical properties from the weak fiber-aerogel interface seriously restricted the development and application of the composite. In this work, mullite whisker was synthesized in-situ on the surface of aluminum silicate fiber to fabricate the fiber/whisker multiscale structure. The needle-like monocrystalline mullite whiskers were uniformly grown on the surface of fiber, with a length of about 15 μm and a diameter of 100–120 nm. Owing to the pinning effect of mullite whiskers, the fiber-aerogel interface was enhanced immensely. The aluminum silicate fiber/mullite whisker/silica aerogel demonstrated a remarkable high compression strength of 2.33 MPa, 9.32 times higher than that of the composite without whiskers, a low density of 0.26 g/cm3, and a low thermal conductivity of 37.3 mW/(m·K). These results indicate that the fiber/whisker/aerogel nanocomposite is a sort of promising thermal insulation material for heat preservation.