Materials in nuclear reactor applications must be able to withstand harsh environmental conditions that include high temperature, radiation, and chemically aggressive environments. Radiation introduces defects into the solid and these defects can subsequently lead to degradation of critical materials properties, such as corrosion resistance, thermal conductivity, and mechanical behavior. A promising strategy for improving radiation resistance that has been shown to work in metals, is to engineer materials with high density of interfaces because interfaces provide sinks for defects. The role of interfaces during irradiation of ceramics is more unclear because of the complex defect energy landscape in these materials. In this talk, I will demonstrate that in ceramics interfaces can be a boon or a bane with respect to radiation resistance, using a multi-layer SiC/ Ti3SiC2 /TiC system as an example. In addition, in both metals and ceramics, the atomic structure of interfaces is not static when material is irradiated. I will demonstrate that even in ceramics that form line compounds, it is possible to segregate constituent elements of the material to interfaces through radiation-induced segregation (RIS). Since interfaces often provide fast pathway for chemical reactions, RIS is expected to impact corrosion of ceramics. I will discuss this coupling of radiation and corrosion based on our joint experimental and computational study of SiC. Coupling of radiation and corrosion occurs not only through interfaces, but also because defects in the solid can impact the rate of surface reactions. In some of the most aggressive chemical environments of nuclear reactors, such as high-temperature water or molten salts, the solid may not form a protective surface layer or such layer might not be stable and as a result, the raw solid is continuously exposed to the corrosive fluid. It is therefore critical to understand the rate limiting steps in the solid dissolution as well as their dependence on radiation-induced defects. I will demonstrate the coupling of radiation-induced defects and corrosion based on our computational studies of SiC. Finally, we have recently discovered that in ceramics the rate of surface reaction is affected not only by the chemical bonding right at the surface, but also by the overall properties of the solids, such as the elastic modulus. Our results show new pathways for improving the properties of ceramics under extreme conditions.

Radiation and environmental degradation of ceramics in nuclear applications

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.