Corrosion characteristics of silicon carbide fiber-reinforced composites in beryllium-bearing molten fluoride salt

Abstract

Corrosion of SiC-fiber reinforced SiC matrix composites in 2LiF-BeF2 molten salt was examined following static molten salt exposure for 1000 h at 650 and 750 °C. Composites were fabricated with either Tyranno SA3 or Hi-Nicalon type-S fibers and a chemical vapor infiltration SiC matrix. Both composites showed minimal weight loss after salt exposure and maintained shape. Corrosion was characterized by comprehensive electron microscopy and Raman spectroscopy. Based on the results of experimental and thermodynamic analysis, a corrosion mechanism for SiC/SiC is proposed where both the salt and SiC materials play a key role in the phase stability of the composite.