High-purity alumina: what are the basic uses of alumina

High-purity alumina: Introduction of the main function of alumina.

1. The main components of ruby and sapphire are alumina, and they have different colors due to other impurities. Ruby contains iron oxide and titanium oxide, giving it a red color, while sapphire contains chromium oxide, giving it a blue color.

2. Among the main components of bauxite, alumina has the highest content. Industrially, bauxite is purified to alumina by the Bayer process, and then converted to aluminum metal by the Hall-Heroult process.

3. High-purity alumina is the reason why metal aluminum is not easily corroded in the air. Pure metal aluminum reacts easily with oxygen in the air, resulting in a dense aluminum oxide film covering the surface of aluminum exposed to air. This layer of aluminum oxide film can prevent aluminum from being further oxidized. The thickness and properties of this oxide film can be enhanced by a process called anodization (anodic corrosion protection).

4. Aluminum is a good conductor of electricity and heat. Emery, the crystal form of aluminum, is suitable for abrasive materials and cutting tools because of its high hardness.

5. High-purity alumina powder is often used as a medium for chromatographic analysis.