Load sharing and accumulated bond fracture in ion-irradiated carbon mat for energy dissipation

Multiwalled carbon nanotube (MWNT) aerogel mats were irradiated with carbon ions to explore the effect of irradiation-induced sp³ bonds and sp² bond defects on ultrahigh strain rate mechanical properties. Energy dissipation was measured using a microprojectile impact test. Specific penetration energy [Formula: see text] increased strongly with irradiation with a maximum [Formula: see text] of ~26 megajoules per kilogram, over 200% higher than the previous best energy-absorbing material of pristine MWNT mats and at least an order of magnitude higher than any other material tested at the microscale. Perforation morphologies observed by electron microscopy show that a much larger network region is deformed due to sp³ bond enhanced load sharing within and between tubes, while defects introduced by the radiation induce more bond, shell, and tube damage leading to strongly enhanced energy dissipation.