Method OF prevention of corrosion

PREVENTION OF CORROSION
There are several methods for protecting metals from corrosion(iron from rusting ).Some of these methods are discussed below :
1. Barrier Protection
In this method, a barrier film is introduced between iron and atmospheric oxygen and moisture. Barrier protection can be achieved by any of the following methods.
Painting the surface.
By coating the surface with a thin film of oil or grease.
By electroplating iron by some non-corrosive metal such as nickel, chromium, copper etc.
In this type of protection, if scratches or cracks appear in the protective layer,then the surface of iron may get exposed. In this region, moisture and oxygen may come in contact with iron and rusting starts. This rusting extends beneath the protective layer and eventually peels off the protective layer.
2. Sacrificial Protection
Sacrificial protection means covering of the surface of iron with a layer of metalwhich is more active than iron and thus prevents the loss of electrons from iron. The active metal loses electrons in preference of iron and goes into the ionic state. With the passage oftime, the covering metal gets consumed. But as long as it is present on the surface of iron, it will protect theiron from rusting and does not allow even nearly exposed surface of iron to corrode. Zinc is commonly used to coat iron surfaces. The process of coating a thin film of zinc on iron is known as galvanisation .