Science Fair Project Encyclopedia
Aluminum oxide (US)
|Appearance||White crystalline powder or solid|
|Formula weight||101.96 amu|
|Melting point at SP||2303 K|
|Boiling point at SP||3250 K|
|Density||3.97 × 103 kg/m3|
|Crystal structure||Trigonal (hex)|
|S0liquid, 1 bar||67.24 J/mol·K|
|Inhalation||May cause irritation or lung damage|
SI units were used where possible.
Aluminium oxide or aluminum oxide is a chemical compound of aluminium and oxygen with chemical formula 3. It is also commonly referred to as alumina in the mining, ceramic, and materials science communities.
Aluminium oxide is the main component of bauxite, the principal ore of aluminium. Industrially, bauxite is purified to aluminium oxide via the Bayer process, and then converted to aluminium metal in the Hall-Heroult process.
Aluminium oxide is responsible for metallic aluminium's resistance to weathering. Metallic aluminium is very reactive with atmospheric oxygen, and a thin layer of aluminium oxide quickly forms on any exposed aluminium surface. This layer protects the metal from further oxidation. The thickness and properties of this oxide layer can be enhanced using a process called anodising.
Aluminium oxide is an excellent thermal and electrical insulator. In its crystalline form, called corundum, its hardness makes it suitable for use as an abrasive and as a component in cutting tools.
Powdered aluminium oxide is frequently used as a medium for chromatography.
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