Preparation and Properties of Al2O3–SiO2 Aerogel Composite Mullite Fiber Felt

Silica aerogel has rec eived more and more attention in the field of thermal insulation. However, the poor mechanical properties and high temperature instability of pure silica aerogels seriously restrict the development and application of silica aerogels. Fiber reinforcement is an effective way to improve the mechanical properties of silica aerogels. In this paper, Al2O3–SiO2 aerogel was compounded with mullite fiber to prepare silicon–aluminum aerogel fiber felt. When the strain value reaches 30%, the compressive strength of the fiber felt with aerogel content of 50.1 wt % reaches 0.21 MPa, and the thermal conductivity of fiber felt decreases from 0.0425 to 0.0322 W/m K when the aerogel content increases to 50.1 wt %. The thermal insulation performance test of fiber felt also showed that the addition of aerogel could significantly improve the heat insulation of fiber felt, and the cold surface temperature of fiber felt was only about 33°C when the flame exceeding 1000°C calcined the fiber felt for 10 s. This work provides a simple solution to prepare aerogel/nanofiber felt with good mechanical properties and low thermal insulation. Highlights: silicon–aluminum composite aerogel felt (AS/ASNFAs) has been prepared by sol-gel and impregnation method, AS/ASNFAs has good mechanical properties (the compressive strength reaches 0.21 MPa) and thermal insulation (0.0322 W/m K), AS/ASNFAs has good flame retardancy, and it remains stable after being burned at 1000 degrees butane for 10 min.