What is Galvanizing or Zinc plating?

Describe the process of Galvanization. Give its importance.

ANS:

            Galvanizing means zinc plating and is done to protect the steel from getting rusted. This is the cheapest form of coating and is in use since several years. It is mainly used for coating materials like pipes, sheets, wires, fence-wires, screws etc. made of mild steel or medium carbon steel.

            Galvanizing or zinc coating is done by any of the three processes as below….

1. Dipping process: The metal to be coated is dipped in molten zinc bath and taken out after some minutes. The zinc film adheres to the metal and serves as a protective layer against rusting. Prior to dipping the metal part must be cleaned by dilute sulphuric acid or by suitable cleaning agent in order to remove the dirt, scales or grease etc.

            2. Spray galvanizing: The metal part is first cleaned by cleaning agents like dilute sulphuric acid. The metal parts are hung in the spraying booth systematically. Then in the spraying booth, the parts are sprayed with the molten zinc through the nozzles, which are controlled and monitored externally.  

            3. Dry galvanizing: In this method, the metal to be coated is cleaned first and the buried in zinc powder for about 2 to 3 hours at a temperature of about 350° C. The zinc dust gets cemented to the metal and forms a good protective layer. The coating applied by this method is more durable.