Interface Chemical Welding by Nanoparticles Endow Ceramic Aerogels with Broad-Temperature Microwave Absorption and Thermal Insulation

Ceramic aerogels are promising lightweight microwave absorbing materials, but generally face challenges in achieving excellent mechanical properties and robust microwave absorption over a wide temperature range. Herein, an in situ “chemical welding” strategy is proposed, which uses Ti₂SnC-derived TiO₂/SnO₂ composite nanoparticles as “welding agents” to interconnect the SiC/SiO₂ core-shell nanofiber network. These nanoparticles construct robust chemical bonding between adjacent fibers to enhance the mechanical properties, achieving a 33% increase in compressive strength and an 88% reduction in plastic deformation after 150 compression cycles. Experimental and theoretical calculations reveal the fundamental differences between chemically-bonded and physically-contacted interfaces in regulating microwave absorption. Chemical interfaces exhibit significant advantages in strengthening built-in electric field, promoting charge separation and carrier transport, and optimizing the temperature response of permittivity. The as-prepared SiC/SiO₂@TiO₂/SnO₂ aerogel with an ultrathin thickness of only 1.8 mm consistently maintains a reflection loss below −20 dB from 298 to 1073 K, outperforming previously reported ceramic aerogels. Additionally, the aerogel exhibits outstanding thermal insulation, showing great potential for infrared stealth. This chemical welding strategy is a general nanotechnology for developing high-performance aerogels.