Ultralight mullite nanofibrous aerogel with thermal insulation performance and robust mechanical property

The fabrication of ceramic aerogel with ultralow density, excellent thermal insulation performance, high temperature stability and robust mechanical property has remained a great challenge. In this study, ceramic nanofibrous aerogel with three-dimensional network structure was prepared via directional freeze-drying method, which combined mullite nanofibres with binders. The unique multi-level pore structure, ie., the major micro-pores induced by the formation of ice crystals and the minor micro-pores derived from the connection of nanofibres, could be observed, leading to the integrated properties of the ultralow density (29mg/cm$^{3}$), low thermal conductivity at room temperature (0.036W/(m$\cdot$K)), and high compressive strength (0.33Mpa at strain of 0.9). Furthermore, the nanofibrous aerogel can be readily produced with adjustable density and shape, providing a new perspective in the advancement of thermal insulation materials characterized by high strength, ultralow density, and structural adaptability.