Alumina powder is frequently used as a car for chromatography.
Alumina is the main reason metal aluminum isn't readily corroded from the atmosphere. Pure metallic aluminum is extremely vulnerable to oxidation at the atmosphere, making a thin coating of the aluminum oxide film which covers the aluminum surface of the building's atmosphere.
It's employed as a high-temperature refractory material, refractory bricks, ceramic, synthetic diamonds and so on. Alumina is also a raw material for aluminum smelting.