From Simple English Wikipedia, the free encyclopedia
Aluminium oxide, also known as aluminum oxide, is a chemical compound made from aluminium and oxygen. Its chemical formula is Al2O3. It is a normally white, powdery solid. It does not exist in a particular form. It can dissolve in acids and bases. It is used as an abrasive (sandpaper is an abrasive). It comes in bauxite and corundum. It does not melt easily. It is dissolved in a cryolite melt and electrolyzed to make aluminium.
Corundum is the most common naturally occurring crystalline form of aluminium oxide.[1]Rubies and sapphires are types of corundum. The reason why they have different colors is because there are other elements in it.[2][3]
Aluminium oxide is the reason why aluminium cannot corrode. When aluminium reacts with atmospheric oxygen, a thin layer of aluminium oxide (4 nm thickness) forms on any exposed aluminium surface.[5] This layer protects the metal from more oxidation.