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

Immersion corrosion tests of TiC0.8, TiC, TiC-20 vol% SiC, TiC-40 vol% SiC and SiC have been performed in molten FLiNaK salt at 800 °C for 25-200 h 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-20 vol% 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.