Give an account of the methods to prevent corrosion of metals.

Explanation

Some of the physical methods used for preventing rusting are:
Painting
Applying grease or oil
Galvanizing or tinning
Alloying
Painting: Iron articles are coated with paints, which in turn acts as a barrier and prevent the contact of iron with air and moisture, thus preventing rusting. This is usually done for window grills, gates, furniture, vehicle bodies, etc.
Applying grease and oil: Iron articles are coated with grease or oil, whcih acts as a barrier, preventing the contact of air and moisture with iron. This technique is usually used for machinery parts, hinges, and tools.
Galvanizing or tinning: A more reactive metal like zinc (galvanising) or tin is coated on the surface of iron by dipping iron in these molten metals. When the more reactive metal comes in contact with air and moisture, it undergoes oxidation forming the respective metal oxide, these metal oxides, stable and impervious, act as a protective layer preventing the oxidation or iron. Even if there is a crak on the surface of zinc, it still prevents rusting as zinc being more reactive, prevents iron from reacting.
Alloying: Iron is alloyed with other metals like chromium, nickel, etc. to obtain it in the form of stainless steel, the stainless steel is resistant to corrosion. This method is used in manufacturing cooking utensils, surgical instruments, scissors, etc.