Definition - What does Aluminum Oxide mean?
Aluminum oxide is a solid crystalline powder and a compound formed from oxygen and aluminum. Aluminum oxide is the key property that generates aluminum's high rate of corrosion resistance.
Corrosionpedia explains Aluminum Oxide
Aluminum oxide is formed on aluminum metal material that has been exposed to air. It forms a thin protective layer on the aluminum surface, to which it closely adheres. This prevents further penetration of other oxides and corrosion-causing elements.