Radiative properties of non-spherical opacifiers doped in silica aerogels for high-temperature thermal insulation

Silica aerogel, a super-insulating material, has garnered significant attention due to its extensive thermal insulation applications. However, the high-temperature performance of silica aerogel is compromised due to its infrared transparency. This study tackles this issue by investigating the influence of opacifier shape on the insulation properties of silica aerogel composite. Based on the Discrete Dipole Approximation (DDA) theory, the radiative properties of opacifiers of varying shapes are investigated. The study also employs a theoretical model to ascertain the effective thermal conductivity of silica aerogel doped with non-spherical opacifiers. To counter oxidation at ultra-high temperatures, an innovative ellipsoidal Carbon@SiC core–shell opacifier is introduced. Non-spherical opacifiers are further optimized to identify the ideal particle diameters and volume fractions for specific temperature ranges. The investigation uncovers that non-spherical carbon black opacifiers with low shape parameter ratios considerably enhance the insulating performance at elevated temperatures. Carbon@SiC core–shell opacifiers, distinguished by high inner/outer radius ratios, offer superior thermal stability and great infrared radiation extinction. In summary, this study offers a pragmatic approach to fabricating aerogels with enhanced insulation properties at high temperatures.