Several silicon carbide-based monolithic refractories were subjected to static coal ash corrosion tests to determine corrosion mechanisms and rates. Two castable refractories with 75% and 85% SiC were exposed to two types of coal ash at temperatures from 1090 degrees C to 1430 degrees C. Several plastic refractories were exposed to a high-calcium coal ash at 1430 degrees C for over 100 h. Optical microscopy and scanning electron microscopy with energy-dispersive X-ray analysis were used to determine the corrosion mechanisms and rates of these materials.