Iron and steel can get a red coating with the passage of time which is generally known as Rust or iron oxide. Rusting occurs when iron or any other alloy contains iron or steel, is exposed to oxygen or hydrogen for a long period of time. Over time, the oxygen and hydrogen particles presented in the air combines with the metal at an atomic level, forming a new compound called an oxide. The actual chemical equation of rust is –
4Fe + 3O2 = 2Fe2O3
Rusting may have various effects on iron and other alloys made up of iron or steel. Firstly, rust can make the metal weaker. Secondly, it affects the magnetic properties of the metal. Thirdly, iron is a good conductor of electricity but rust is an insulator and when it affects iron, it decreases its conductivity.
There have been various methods to prevent rusting. Some of the methods are:
Galvanizing is the method of applying a layer of zinc over iron or steel to prevent rusting. The layer of zinc becomes a barrier between the atmosphere and the metal underneath.
Rusting inhibitor sprays can form a layer, coating the metals and preventing access of any corrosive substance to the metal inside a sealed system.
Bluing is also a useful technique to prevent rusting.