Black Fused Alumina, Black corundum is produced by a reduction fusion of high quality bauxites in electric arc furnaces. Black Fused Alumina, Black corundum is both a hard and tough material with high strength, making it an excellent abrasive grain for applications such as grinding wheels, sandpaper, blasting media, metal preparation, lapping, polishing, and grinding. Black Fused Alumina, Black corundum thermal properties make it an excellent raw material for refractory applications.