High-Temperature Stability of SiO2 Oxide Film on Surface of SiC

Abstract

SiC, which is a promising accident-tolerant fuel cladding, is a non-oxide, and it is known that pas-sive oxidation occurs, where by a protective oxide fi lm of SiO 2 is formed under atmospheric conditions above 900 ℃ . The reaction occurring at this high temperature is important in assessing the soundness of SiC during a severe accident, but the understanding of it is still insuf fi cient. In this study, to evalu-ate the high-temperature oxidation behavior when SiC cladding is exposed to the atmosphere （ 10 5 Pa ） during an accident involving a light-water reactor, an oxidation test was performed for up to 100 h at 1100 to 1500 ℃ . As a result, a SiO 2 oxide fi lm was formed on the surface of SiC, but the formation of bubbles originating from impurities and cracks due to a phase transformation was con fi rmed. In addi-tion, it was observed, for the fi rst time in this research, that a multilayered SiO 2 oxide fi lm was formed at 1500 ℃ . Therefore, it was shown that the oxidation reaction of SiC does not stop depending on the surrounding conditions under high temperature and atmospheric conditions.