Helium ion irradiation effects on microstructure evolution and mechanical properties of silicon oxycarbide

Abstract

In this study, silicon oxycarbide (SiOC) was fabricated by pyrolysis of a polysiloxane precursor at 1000 °C and 1500 °C in an Ar atmosphere and evaluated as a new nuclear fuel coating material. The 1000 °C pyrolyzed SiOC is fully amorphous while the 1500 °C sample contains crystalline β-SiC nanodomains, a turbostratic carbon network, and an amorphous SiOC matrix. After 100 keV He ion irradiation, no detectable microstructural changes are observed for the 1000 °C pyrolyzed SiOC. However, the 1500 °C pyrolyzed SiOC shows amorphization of crystalline phases. Neither sample has He bubbles, elemental segregation, or voids after irradiation. Irradiation induced hardening is observed for all the samples. Both hardness and elastic modulus values increase with irradiation. These high temperature stable and amorphous phase dominant SiOC materials are promising systems for the development of irradiation-tolerant fuels for advanced nuclear reactors.