Corrosion is the slow process of eating away of metals by the reaction of atmospheric air, moisture or a chemical (such as an acid). For example rusting of iron, tarnishing of silver, formation of green coating over copper.
Methods to prevent corrosion are as follows
Galvanization
The process of depositing a thin layer of zinc metal on an iron object is called galvanization. It is done by dipping the object in molten zinc .A thin layer of zinc metal is then form all over the iron object. Zinc metal on the surface of an object protects them from resting because zinc metal does not corrode on exposure to damp air. The Galvanized Iron object is protected against rusting even if the zinc coating is broken.
Alloying
It is the method of improving the properties of a metal by mixing the metal with another metal or nonmetal. When iron is alloyed with chromium and nickel in stainless steel is obtained. Stainless steel does not rust at all.
Painting
Rusting of iron can be easily prevented by coating the surface with the paint which protects iron from air and moisture.
Greasing or oiling
When some grease oil is applied to the surface of an iron object, then air and moisture cannot come in contact with it and hence rusting is prevented.
For example tools and machine parts made up of iron are smeared with Grease.
Tin plating and chromium plating
Tin and chromium metals are resistant to corrosion. So when a thin layer of tin metal is deposited on iron by electroplating then the iron object is protected from rusting.
Electroplating is the process of coating of metal with the help of electricity by making the use of other metals.
