SiC performance of coated fuel particles under high-temperature atmosphere of air

Abstract

To better understand whether the SiC layer can withstand the corrosion given by the chemical reaction between SiC and O2, our experiments focused mainly on the effect of oxygen on SiC-coated fuel particles at high temperature. Tests were conducted on non-irradiated coated fuel particles in an atmosphere of air over a range of temperatures between 800 and 1600°C.This paper summarizes the failure fractions, surface morphology and microstructure of the SiC coating, etc. The morphology of SiC-coated particles surfaces, optical and scanning electron micrographs and the oxygen distribution of polished SiC layers at 800, 1000 and 1200°C for 200h under air atmosphere showed that the features of SiC layers did not change in these cases. In contrast with the aforementioned cases, the behavior of SiC layers was deteriorated when the oxidation temperature was beyond 1400°C. More serious the deterioration, higher the oxidation temperature is. The thickness of SiO2 layer from outside to inside SiC layers reached 6 ∼8μm, and a large number of SiC-coated particles were broken into fragment at 1600°C. The experiment results show that the oxidation of the SiC layer proceeds slowly at temperatures around 1400°C and more rapidly as the temperature approaches 1600°C.