Corrosion behavior of ZrC–SiC composite ceramics in LiF–NaF–KF molten salt at high temperatures

The suitability of ZrC–SiC-based ceramics was assessed as candidate materials for fluoride. An immersion corrosion with ZrC–SiC composites was performed in molten FLiNaK salts (LiF–NaF–KF: 46.5/11.5/42 mol%) at 850 °C. Results indicated that ZrC–SiC-based ceramics were more corrosion resistant than the ZrC ceramic. ZrC–40SiC ceramic exhibited 50% weight-loss to ZrC. This carbide exhibited minimal corrosion attack because of strong resistance to dissolution in molten fluorides. Furthermore, XRD results were consistent with weight-loss and SEM results. The corrosion behavior of ZrC–SiC-based ceramics was affected by impurities, particularly oxygen content. Oxygen and/or oxygen ion participated in corrosion of ceramic. Corrosion of carbide ceramics is mainly due to C4− in ceramics. This ion is oxidized to elemental C by oxidants or impurities in the molten salt. The addition of C may inhibit corrosion of molten salts and thus improve the corrosion resistance of carbide ceramics.