Rust is the common name for a chemical compound called iron oxide. It is formed when iron or an alloy that contains iron, such as steel, is exposed to oxygen and moisture for an extended period of time. The result is a reddish-brown, flaky substance that can weaken the metal and make it more susceptible to damage.
In the case of metal surfaces, rust forms when the metal is exposed to oxygen and moisture. The oxygen reacts with the metal to form metal oxide. In the presence of water, the metal oxide further reacts with the water to form hydrated metal oxides, commonly known as rust. The rust forms a coating on the surface of the metal and can continue to spread, penetrating deeper into the metal and weakening it over time.
Rust can occur on any metal surface, but is most common on iron and steel. It can be prevented by applying coatings such as paint, oil or wax,