Effect of γ-radiation on silica aerogel and composite material for thermal insulation applications in nuclear power pipeline

SiO₂ aerogel and its composite materials are considered as promising high-temperature thermal insulation materials due to their high porosity, low density and low thermal conductivity. However, a major obstacle for their application in nuclear power systems is the currently insufficient mechanism of the radiation effect. This study therefore aimed to investigated the changes in the microstructure, hydrophobic properties and thermal insulation properties of aerogel and ultrafine glass fiber reinforced aerogel composite (uGF/SiO₂ aerogel) before and after γ-radiation, and explore the mechanism of the γ-radiation effect of aerogel materials. With an increase in cumulative radiation dose, the microstructure of aerogel suffered significant radiation damage, causing a gradual increase in crystallinity and thermal conductivity. When the cumulative dose reached 1700 kGy, the nanoparticles in the aerogel agglomerated and crystallized significantly, leading to an approximately 30 % increase in thermal conductivity. Notably, at the radiation of 1700 kGy, the uGF/SiO₂ aerogel exhibited excellent structure stability, with a thermal conductivity of 31.60 mW/m·K, which was 3.27 % higher than that of unirradiated sample. This indicated the uGF/SiO₂ aerogel exhibited excellent thermal performance and thermal stability even after γ-radiation. The study on the radiation effect of aerogel materials offers valuable insights for the composition optimization of aerogel used in nuclear power applications.