Ultra-low thermal conductivity and high strength of aerogels/fibrous ceramic composites

Novel aerogels/fibrous ceramic composite, inspired by the bird's nest structure in nature, is synthesized using mullite fibers as matrix and ZrO2-SiO2 aerogels as filler through vacuum impregnation. Thus, the macropore of mullite fiber perform are filled by aerogels to form similar bird's nest structure with high porosity (85%) with a large amount of mesoporous. The as-prepared aerogels/fibrous ceramic composite exhibits high compressive strength of up to 1.05 MPa which is approximately two times as much as that of mullite fiber perform and ten times higher than that of pure aerogels, and the compressive failure mechanism is analyzed. Compared to conventional fibrous materials, the aerogels/fibrous ceramic composite shows a much lower thermal conductivity of 0.0524 W m−1 K−1 at room temperature and 0.082-0.182 W m−1 K−1 during 500 °C and 1200 °C indicating its excellent thermal insulation property in a wide temperature range. Therefore, this ultra-low thermal conductivity aerogels/fibrous ceramic composite with high strength is an excellent heat-insulation material applied in the fields of aerospace.