Tabular alumina is aluminum oxide that has been heated to temperatures above 1,650 °C (3,000 °F). Composed of tabletlike crystals, it has high heat capacity and thermal conductivity as well as exceptional strength and volume stability at high temperatures. For these reasons, a major use of tabular alumina is in the production of high-quality refractories, the materials used for lining industrial furnaces. High-alumina refractories are used in the metal and glass industries in boiler installations, in large furnaces and kilns for smelting metals and firing glass, pottery and porcelain, and in the manufacture of building bricks.
Most refractories are produced in the form of brick, bonded and fired in furnaces. Some castable refractories are made in the form of mortars, usually tabular alumina with calcium aluminate cement as a binder. These mortars, called grog, are sprayed under pressure to form the linings of the steel industry’s electric and basic oxygen furnaces, ladles, and coke ovens and for steam boilers, rotary kilns, and many other high-temperature applications.