ASTM C704 specifiessilicon carbideas the standard abrasive media used in the abrasion resistance test for refractories. This test simulates service wear caused by mechanical erosion (e.g., in FCC units). Silicon carbide is used because of its consistent hardness, angularity, and wear characteristics that represent severe operational conditions.
Reference:
API Std 936 references ASTM C704 for erosion-resistant testing and confirms silicon carbide as the specified media.
API TR 977 also documents improvements to test reproducibility with silicon carbide use