The Rust Process
Rust is the common name for a very common compound, iron oxide. Iron oxide, or its chemical name Fe2O3, is common because iron combines very readily with oxygen.
Iron or steel rusting is a common example of corrosion — an electrochemical process involving an anode, an electrolyte and a cathode. When a piece of metal corrodes, the electrolyte helps provide oxygen to the anode.
As oxygen combines with the iron of the anode, electrons are freed and the anode becomes rusted. When they flow through the electrolyte and try to combine with any free ions.
For iron to rust, three things are needed: iron, water and oxygen.
The chemical compounds found in liquids like rain, seawater and the salt-loaded spray from winter roads make them better electrolytes than pure water, allowing their presence to speed the process of rusting on iron and other forms of corrosion on other metals.
