Aluminum oxide is an odorless white amorphous powder or crystalline solid; it has a Mohs hardness of 8.8–9, features stable chemical properties, high temperature resistance, electrical insulation and wear resistance. Its common crystal forms include α-Al₂O₃ (corundum, stable phase) and γ-Al₂O₃ (active phase, porous structure).

1. Metallurgical industry: Core raw material for electrolytic aluminum production (approximately 90% of global output is used in aluminum smelting)
2. Refractory materials: Refractory bricks, crucibles, furnace linings, high-temperature furnace tubes
3. Abrasive & polishing industry: Sandpaper, grinding wheels, abrasives, polishing powder (corundum)
4. Ceramics & electronics: Special ceramics, LED substrates, electronic insulation parts, thermal conductive materials
5. Chemical industry: Catalyst carriers, adsorbents, desiccants (activated alumina), fillers
6. Others: Artificial gemstones (ruby, sapphire), refractory coatings, flame retardants