Boron nitride (BN) is based on compounds of boron and nitrogen. It is relatively inert and has good thermal conductivity combined with good electrical insulation, making this material useful in fabricating substrates and insulators in microelectronics applications. Boron nitride is polymorphic, meaning that it occurs in a wide variety of crystalline structure forms. BN is available as amorphous or vitreous, pyrolytic, hexagonal and cubic crystal structures. Cubic boron nitride (CBN) is a superabrasive that is second only to diamond in hardness. BN is more resistant to oxidation than carbon. Depending on the purity, density and crystal structure, boron nitride is used for refractory linings, industrial crucibles, arc furnace electrodes, analytical labware, composites, refractory cements and super abrasives. Hexagonal BN is structurally weak and used as a high temperature lubricant, coating or release agent.