High temperature corrosion resistance of electrically conductive nitrogen doped silicon carbide ceramics in molten fluorides

Electrically conductive nitrogen-doped SiC ceramics were exposed to molten FLiNaK at 700 degrees C for 100, 200, and 500 h, and at 1000 degrees C for 100 h in Ar atmosphere. The SEM-EDX investigations of corroded samples showed that the main corrosion attack proceeds through the intergranular phase, where the fluoride melt interacts with the oxide phases and partly dissolves also the SiC grains. It was proved that N-doped SiC has good corrosion resistance against molten FLiNaK. After corrosion at 700 degrees C for 100, 200, and 500 h the corroded layer thick-nesses were 85, 90, and 120 & mu;m, respectively.