Superelastic SiC Aerogels Prepared Based on Biobased Materials with Superior Microwave-Absorbing and Thermal-Protective Performance

The use of environment friendly and sustainable biobased materials to synthesize high-performance silicon carbide (SiC) aerogel electromagnetic wave-absorbing (EMW) materials is an important trend, which helps to promote their development and application. However, due to the inherent pore structure of biobased templates, the structural design of SiC aerogels is limited. Here, a salt-induced sol–gel strategy is proposed to fabricate high-performance SiC aerogels by crushing the biobased material and then cleverly using the DLVO colloid stability theory to restructure the biobased template. This strategy gets rid of the shackles of the inherent pore structure of biobased materials and designs aerogels composed of oriented SiC nanowire bundles. Benefiting from the unique structure, the obtained aerogel has a porosity of ∼98%, while enhancing the multiple reflection absorption effect of the aerogel on EMWs (effective absorption bandwidth = 4.2 GHz) and extending the thermal performance of the aerogel transmission path (thermal conductivity reduced to 0.019 W·m –1 ·K –1 ). The salt-induced sol–gel strategy paves the way for the structural design of high-performance ceramic aerogel electromagnetic absorbers.