What Is Aluminum Oxide?
Aluminum oxide, commonly known as alumina, is an oxide of aluminum. It encompasses various forms including γ-alumina and the stable α-alumina, along with several intermediate types.
Naturally occurring as corundum or bauxite, aluminum oxide is abundantly found in mineral deposits. Bauxite, in particular, serves as the primary source for industrial extraction of alumina and aluminum.
Uses of Aluminum Oxide
Renowned for its exceptional physical and chemical properties, aluminum oxide finds versatile applications as an oxide-based ceramic material. Its notable attributes include a high melting point and superior heat resistance.
These properties make it indispensable in the production of refractory materials such as bricks and aggregates, offering excellent resistance to heat and corrosion. It is also employed in chemical-resistant porcelain and piping for handling corrosive liquids.
With remarkable mechanical strength and wear resistance, aluminum oxide is extensively utilized in precision equipment components requiring durability and precision. Additionally, its biocompatibility renders it valuable in medical applications for artificial joints and implants.
Properties of Aluminum Oxide
Aluminum oxide has a melting point of 2,072°C and a boiling point of 2,977°C. It exists as a white powder and remains insoluble in water, diethyl ether, and ethanol, displaying robust chemical stability.
Its strong bond between oxygen and aluminum makes it challenging to separate individual aluminum pieces. However, the Hall-Héroult process offers a practical method for aluminum smelting through electrolysis.
Structure of Aluminum Oxide
Aluminum oxide, represented by the chemical formula Al2O3, exhibits a molar mass of 101.96 g/mol and a density ranging from 3.95 to 4.1 g/cm3.
The pure form, known as α-alumina, undergoes dehydration to form γ-alumina, which typically contains a small amount of water. α-alumina features a triangular crystal structure, while γ-alumina adopts a cubic crystal structure. Notably, γ-alumina is valued for its high specific surface area, making it useful as a catalyst.
Other Information on Aluminum Oxide
1. Production and Synthesis
Aluminum oxide occurs naturally as sapphire, ruby, and corundum. Synthetic production methods involve thermal decomposition of salts like aluminum sulfate or reaction of aluminum chloride vapor with oxygen or water vapor.
2. Additional Forms
Besides aluminum oxide (III) (Al2O3), other forms such as aluminum oxide (II) (AlO) and aluminum oxide (I) (Al2O) also exist. These forms have been observed in specific conditions, including high-altitude explosions and astronomical observations.
Aluminum oxide (I) is typically gaseous and exists within a specific temperature range, typically from 1,050°C to 1,600°C.