Realistic structure-guided C@SiC opacifiers for mechanically robust and super-insulating silica aerogels

Real-structure DDA guides optimization of C@SiC infrared opacifiers. • C@SiC enables superior mid-IR extinction and carbon core oxidation resistance. • Multiple interfaces promote stress transfer and suppress solid conduction. • CGSA withstands >6000× its own weight and retains 90.82% modulus after 50 cycles. • CGSA achieves a super-low thermal conductivity of 26.2 mW m −1  K −1 at 600 °C in air. Driven by the increasing demand for high-temperature energy systems, the development of robust thermal insulation materials capable of maintaining structural integrity and suppressing radiative heat transfer remains highly challenging. Silica aerogels, as representative lightweight super-insulators, suffer from intrinsic brittleness and pronounced thermal degradation caused by pore coarsening and enhanced infrared radiation at elevated temperatures. Here, we report a multi-scale structural engineering strategy to construct C@SiC core-shell particle-reinforced glass fiber/silica composite aerogels (CGSAs). Guided by realistic structural modeling, C@SiC particles maintain outstanding stability under service conditions and act as robust oxygen diffusion barriers and precise mid-infrared opacifiers. Furthermore, the abundant particle-aerogel-fiber interfaces promote efficient stress transfer and energy dissipation under severe thermal-mechanical coupling. Consequently, the CGSA exhibits exceptional mechanical robustness, supporting over 6000 times its weight (112 kPa at 15% strain) with 90.82% modulus retention after 50 fatigue cycles. It also delivers an ultra-low thermal conductivity of 0.0262 W m −1  K −1 at 600 °C in air, representing a 30.3% reduction compared to the glass fiber/silica composite aerogel. This multi-scale design provides a promising strategy to address the inherent performance limitations of silica aerogels and facilitates the development of highly durable thermal insulators for medium- and high-temperature applications.