Rust

Rust, the most familiar example of corrosion, in an old train. It gets brown/red.

Rust is a type of corrosion. It happens to metals when they are exposed to air or water for a long time. Rust slowly breaks metals down into other chemicals, due to a reaction with the oxygen molecules. Air and Water both contain oxygen so they are usually what make metals rust. Almost all metals rust, but they can be protected from things that make them rust by painting them. Alloys (mixes of metals) such as stainless steel, rust much slower than non-mixed metals like pure iron. When a piece of metal rusts, it changes to a different color, (ex. iron turns red/brown) and the metal eventually falls apart.

Rust appears on metal if it is left outside in the damp air. For example rust occures mostly in cracks, or where two parts meet on metal. If it rains the water will enter the cracks and make it easier to rust because it would be hard to remove the water from the cracks. So since the water stays in the cracks, the metal starts to corrode. Which at the end it turns into rust. The iron cannot be used or reused as it is completely wrecked once it rusts.

Some metals, such as aluminum, form a very very thin coating of corrosion on the metal. The metal cannot continue corroding since the coating isolates the rest of the metal from the source of oxygen. That is why aluminum keeps its shine. It also makes aluminum seem very unreactive, even though it is reactive enough to react with water!

basidiomycete fungus on a plant

Some kinds of basidiomycete fungi can be mistaken for Rust because these kinds of fungi look a lot like rust in color and texture and sometimes latch on to metals.

Other pages

• Iron(III) oxide
• Hematite
• Corrosion