Asymmetric lattice evolution in carbon fibers and nanopore coarsening in aerogel matrix under irradiation

Next-generation nuclear reactors demand internal thermal insulation materials that integrate exceptional thermal insulation, mechanical strength, and irradiation resistance. Here, we investigate the near-surface irradiation response of carbon fiber/carbon aerogel (C_f/CA) composites under 2 MeV C⁺ irradiation at fluences of 1×10¹⁵-4.2 × 10¹⁶ n/cm² (0.095-4.0 dpa). Multiscale characterization of the ion-damaged layer reveals asymmetric lattice damage in carbon fibers leading to macroscopic bending, and nanopore coarsening with sp²/sp³ bond rearrangement in the aerogel matrix. Notably, irradiated composites retain overall compressive strength of 153% and thermal conductivity of 96.43% relative to the pristine values. This study not only proposes a promising insulation material candidate for next-generation nuclear systems, but also provides a fundamental understanding of the structure-property evolution in porous carbon materials under extreme irradiation environments.