Carbides

Carbides, compounds of carbon with metals or metalloids. These compounds have high melting points and are not readily volatilized. They are produced by heating appropriate mixtures to high temperatures in electric furnaces. The largest group of carbides is the acetyledic group, including the carbides of beryllium, calcium, strontium, sodium, potassium, copper, silver, gold, and nickel. The acetylides, the most important of which is calcium carbide, form acetylene by reaction with water or acids. Another group, consisting of aluminum, beryllium, and manganese carbides, is termed the methanides. These yield methane on reaction with water or acids.

Important metallic carbides include iron carbide, or cementite, the hardening constituent in steel; tungsten carbide, from which are made hard tools for the machining of tough metals; and boron carbide, a material almost as hard as diamond. An important nonmetallic carbide is silicon carbide, or carborundum, which is used as an abrasive.