... contains a small amount of SiO2 and Fe2O3, microhardness HV1800-2200, toughness than SiC high, use it made of grinding tool, ... and different. Outstanding characteristic is crystal size small impact resistance, because use since the mill processing broken, grain much ... and special process of reprocessing, reduce brown corundum of residual carbon content, and make product in use not pulverization, not ...