... point 24500c, 3.density 2.51g/cm3 Boron Carbide, a black powder, is the hardest of the conventional abrasives ... Boron carbide is widely used to grind and polish hard metal alloy, super-hard metal, high carbide steel, jewel, hard ceramic and other hard materials ... additive for compound materials for military planes and as raw materials for matal boride, metal ceramic, boron steel, boron alloy and for ...