Flexible SiC nanowire/mullite fiber composite aerogel with adjustable strength based on micromechanical design

Abstract

Owing to excellent high temperature resistance, high porosity and light weight, SiC aerogels possess great application prospects in thermal insulation and adsorption. However, poor mechanical properties of SiC aerogels, such as brittleness and non-bendability, hinder its application; it is still a challenge to improve and regulate the mechanical properties of SiC aerogels. Here, for the first time, we propose a micromechanical design strategy to prepare flexible SiC nanowire/mullite fiber composite aerogels (SMCAs). By optimizing the aspect ratio of the skeleton fibers to regulate the stress state of microstructures, the maximum compressive stress of that SMCAs could bear can be tuned systematically from 1.2 kPa to 1254.8 kPa, spanning 3 orders of magnitude. More importantly, thanks to its micromechanical design, SMCAs can withstand up to 80% compression deformation and up to 90° bending deformation. The present work provides a new idea for the regulation of mechanical properties of ceramic aerogels.