Aluminum Oxide and Alumina Ceramics

Aluminum oxide and alumina ceramics have excellent wear characteristics, chemical resistance, compressive strength, high-temperature properties, and dielectric strength. Alumina or aluminum oxide is a compound of aluminum metal and oxygen used in the alpha alumina structural form. In its pure form, alumina is a white, high-hardness ceramic. Fully-dense alumina can be translucent. Aluminum oxide and alumina ceramics are used widely because of their high electrical insulation, high mechanical strength, high wear resistance, and good chemical resistance. Alumina’s main drawback, however, is its relatively poor thermal-shock resistance due its higher coefficients of thermal expansion and lower thermal conductivity compared to other pure ceramic materials.

Aluminum oxide and alumina ceramics are categorized by phase and grade. There are several phases of aluminum oxide, including a, c, h, d, k, q, g, and r. Similarly, there are many commercial grades of alumina. Examples include smelter-grade, calcined, low soda, reactive, tabular, fused, and high-purity. Smelter alumina is used in the manufacture of aluminum metal, typically in fluid bed or fluid flash calciners. Calcined alumina may use mineralizing catalysts and contain sodium oxide as the main impurity. Low soda alumina is used mainly in electrical and electronic components. Reactive alumina has a relatively high purity and small crystal size. Tabular alumina is re-crystallized or sintered alpha alumina. Fused alumina is made in electric arc furnaces. High-purity alumina is used in the manufacture of synthetic gem stones, laser components, and instrument windows. Other types of aluminum oxide and alumina ceramics are also available.

Aluminum oxide and alumina ceramics are used in many applications and industries. Aluminum oxide abrasives are used in sand blasting, polishing, and surface preparation. For example, aluminum oxide grit powder is used to clean engine heads, valves, pistons, and turbine blades. Aluminum oxide abrasive grains are also used in metallizing, plating, and welding operations. Depending on their purity and density, aluminum ceramics may be used in refractory tubes, industrial crucibles, analytical labware, dielectric substrates, wear components, refractory cements, and abrasives. Some alumina ceramics are also used in machine parts. Other aluminum oxide and alumina ceramics are used in specialty applications.

• Alumina
  Alumina or aluminum oxide (Al2O3) is a compound that consists of aluminum and oxygen. It is typically used in the alpha alumina structural form. In its pure form, alumina is a white ceramic material...
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• Optical Properties of Aluminum Oxide: Determined from Vacuum Ultraviolet and Electron Energy-Loss Spectroscopies
  Alumina has a variety of applications as a structural ceramic and as an optical material, for example, in sodium-vapor arc lamps and in thin-film devices. The latter applications make use of the...
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• Laser Scribing of Ceramics
  Alumina (also known as Aluminum Oxide, Al2O3) is an extremely good electrical insulator with fantastic thermal properties - for this reason it is often used in the electronics sector for thin film...
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