The corrosion behavior of CVD SiC coatings on SiCf/SiC composites in a simulated molten salt reactors environment

The corrosion behavior of SiC coatings deposited at 1000, 1150 and 1200 ℃ on SiCf/SiC composites was investigated. CVD SiC coatings deposited at higher temperatures provided better corrosion resistance in molten salt. SiC coating at 1200 ℃ showed the best resistance due to the high crystallinity. In addition, multi-scale characterization revealed that the dissolution of Si into molten salt resulted in the formation of a C-rich amorphous layer on SiC coatings. The fluorine was observed to diffuse through corrosion layer. According to DFT calculation, the diffusion of molten salt elements was assisted with Si vacancies and fluorine diffused fastest.