Where does rust come from? How does it begin to form and why only on certain metals?
In: Chemistry
“Rust” is iron oxide, which is a combination of iron and oxygen. Having these two elements, however, will not cause it to form: it needs the presence of a third substance. That substance (or “catalyst”) is water, either in liquid form or as moisture in the air. Many metals are subject to corrosion of this type, but in general useage only those that contain iron are considered to be rusting.
Some metals, like copper and its alloys (brass and bronze) develop something called a patina instead. The patina protects the body of the metal from further chemical changes. This is different from rust, which does not form a protective layer. Given enough time and the right conditions, any iron mass will eventually convert totally into iron oxide or rust.
Latest Answers