Why doesn't aluminum rust?

This question is wrong. Aluminum also rusts, but aluminum doesn't rust like iron until it's finished.

When metal is oxidized by oxygen in the air, it is rust. Aluminum reacts with oxygen to form alumina, which is aluminum rust. Aluminum rust is very thin. Its thickness is only one tenth of a millimetre, but it is very hard and very wear-resistant. It is close to the surface of aluminum, so that the aluminum inside can not contact the external air and prevent the aluminum from rusting.

(tip: alumina film also has "Nemesis" : one is alkali and the other is acid. When alumina meets them, it will react chemically to form compounds, which are very easy to fall off. Dishes often contain acid and alkali components, so, no! Yes! Put the dish fruit wine in an aluminum vessel to avoid corrosion and damage of the aluminum pot. In addition, no! Yes! Because the surface of the aluminum pot is gray, it is difficult to wipe it with sand, even if you wipe a layer of oxide film, the aluminum pot It's brighter, but it can only make you happy for a while. Without the protective film on the surface, the aluminum pot will continue to oxidize, and the gray color of alumina will still show in front of you; and the aluminum pot is getting thinner and thinner, affecting its service life)

Why is aluminum a non-ferrous metal?

Non ferrous metals in a narrow sense, also known as non-ferrous metals, are a general term for all metals except iron, manganese and chromium; Nonferrous Metals in a broad sense also include nonferrous alloys (alloys formed by taking a nonferrous metal as the matrix (usually greater than 50%) and adding one or several other elements).