High-strength mullite fibers reinforced ZrO2–SiO2 aerogels fabricated by rapid gel method

A rapid gelation process is adopted to fabricate mullite fibers-reinforced ZrO2–SiO2 (M/ZrO2–SiO2) aerogels. The short-cut mullite fibers are introduced into ZrO2–SiO2 sol via aging and supercritical drying, and the epoxides are used as gelation accelerators. The as-prepared M/ZrO2–SiO2 aerogels have a three-dimensional reticulated porous structure similar to those of pure ZrO2–SiO2 aerogels observed by scanning electron microscopy, which indicates that the addition of fibers does not obviously affect the morphology of aerogels. It is observed that the mullite fibers disperse in the aerogels homogeneously, and fibers combine well with aerogels. M/ZrO2–SiO2 aerogel composites exhibit high compressive strengths up to 0.438 MPa, which indicates that this structure benefits the loading transfer and thus enhances their mechanical properties. Moreover, the thermal conductivity of M/ZrO2–SiO2 aerogel composites is as low as that of the pure ZrO2–SiO2 aerogels (~0.0270 W m−1 K−1).