LAUSR

Abstract This study investigates steam corrosion of bulk ZrSi 2 , pure Si, and zirconium-silicide coatings as well as water quenching behavior of ZrSi 2 coatings to evaluate its feasibility as a potential accident-tolerant fuel cladding coating material in light water nuclear reactor. The ZrSi 2 coating and Zr 2 Si-ZrSi 2 coating were deposited on Zircaloy-4 flats, SiC flats, and cylindrical Zircaloy-4 rodlets using magnetron sputter deposition. Bulk ZrSi 2 and pure Si samples showed weight loss after the corrosion test in pure steam at 400 °C and 10.3 MPa for 72 h. Silicon depletion on the ZrSi 2 surface during the steam test was related to the surface recession observed in the silicon samples. ZrSi 2 coating (∼3.9 μm) pre-oxidized in 700 °C air prevented substrate oxidation but thin porous ZrO 2 formed on the coating. The only condition which achieved complete silicon immobilization in the oxide scale in aqueous environments was the formation of ZrSiO 4 via ZrSi 2 coating oxidation in 1400 °C air. In addition, ZrSi 2 coatings were beneficial in enhancing quenching heat transfer - the minimum film boiling temperature increased by 6–8% in the three different environmental conditions tested. During repeated thermal cycles (water quenching from 700 °C to 85 °C for 20 s) performed as a part of quench tests, no spallation and cracking was observed and the coating prevented oxidation of the underlying Zircaloy-4 substrate.