Corrosion behavior of TiC–SiC composite ceramics in molten FLiNaK salt

Abstract

Immersion corrosion tests of TiC0.8, TiC, TiC–20vol% SiC, TiC–40vol% SiC and SiC have been performed in molten FLiNaK salt at 800°C for 25–200h under argon cover gas. All of these five samples showed small mass loss and relatively good corrosion resistance in molten FLiNaK salt. The corrosion patterns of TiC0.8, TiC, TiC–20vol% SiC and TiC–40 vol% SiC were inter-granular corrosion, which were attributed to the depletion of Ti along the grain boundaries. SiC exhibited a general corrosion process in which a carbon-rich layer formed on the surface, resulting from the depletion of Si. The carbon-rich layer protected SiC against further corrosion, hence lowering the corrosion rate. The corrosion results of TiC–20% SiC and TiC–40% SiC revealed the corrosion resistance of TiC could be improved by adding SiC. And the contribution of SiC to better corrosion resistance has been elucidated.