What is the oxide layer on aluminum?

The oxide layer on aluminum is a thin, transparent, and hard layer of aluminum oxide (Al2O3) that forms naturally when aluminum is exposed to air. This layer is highly resistant to corrosion and protects the underlying aluminum from further oxidation. It is chemically inert, which means it does not react easily with other substances, and it has a high melting point, making it stable at high temperatures. The oxide layer also has a high hardness, which helps to prevent scratching and wear. This protective oxide layer is self-healing, meaning that if it is damaged, it can regenerate and continue to protect the aluminum.