Chemical formula: WC. Black hexagonal crystal, metal luster, high hardness similar to that of diamond, good conductor of electricity and heat. Melting point: 2,870℃; boiling point: 6,000℃; relative density: 15.63(18℃). Tungsten carbide is insoluble in water, hydrochloric acid and sulfuric acid, but is freely soluble in the mixture of nitric acid and hydrofluoric acid. Pure tungsten carbide is fragile; but its fragility can be reduced if a small amount of titanium, cobalt and other metals are added. Titanium carbide, tantalum carbide or their mixture is frequently added into tungsten carbide applied to steel cutting tools, to improve its anti-explosion capacity. Tungsten carbide has stable chemical properties.