aluminium oxide

Thân thiện

Aluminium oxide is used as an abrasive in sandpaper.

Definition

Noun 1. A chemical compound: Aluminium oxide is a chemical compound of aluminium and oxygen with the formula Al₂O₃. It occurs naturally in various crystalline forms, most notably as the mineral corundum.

Usage

• Aluminium oxide is valued for its hardness and is used as an abrasive and as a refractory material.
• In its gemstone forms, such as ruby and sapphire, aluminium oxide is highly prized.
• The primary ore of aluminium, bauxite, contains aluminium oxide along with other minerals.

Examples

• Industrial Use: "The grinding wheel is coated with aluminium oxide for cutting metal."
• Natural Occurrence: "Aluminium oxide in the form of corundum is one of the hardest naturally occurring substances."
• Scientific Context: "The layer of aluminium oxide on the surface of the metal protects it from further corrosion."

Advanced Usage

• "Activated alumina": This refers to a highly porous form of aluminium oxide used as a desiccant (drying agent) and as a filter medium.
  • Example: "The laboratory uses activated alumina to dry the compressed air stream."
• In materials science, specific crystalline structures of aluminium oxide have designations like "alpha-alumina" (the most stable form, e.g., corundum) and "gamma-alumina" (a porous form used as a catalyst support).

Variants and Related Words

• Alumina: This is the most common name for aluminium oxide, especially in industrial and chemical contexts.
  • Example: "The refinery produces alumina from bauxite ore."
• Corundum: The natural crystalline mineral form of aluminium oxide.
• Sapphire/Ruby: Gemstone varieties of corundum (aluminium oxide), where trace impurities provide color (blue for sapphire, red for ruby).

Synonyms

• Alumina (n): The most frequent synonym, particularly in technical and commercial language.
• Corundum (n): Specifically denotes the natural mineral form.

Notes on Different Meanings

The term "aluminium oxide" consistently refers to the compound Al₂O₃. Its different meanings or applications stem from its various physical forms (e.g., powdered abrasive, synthetic gemstone, porous catalyst support) and natural occurrences (corundum, ruby, sapphire), not from a change in its fundamental chemical definition.

Học thuật

Noun

1. any of various forms of aluminum oxide occurring naturally as corundum

Từ đồng nghĩa

• alumina
• aluminum oxide