Question

How is the cathodic protection of iron different from its galvanisation?

Answer 1

Sr. No.	Feature	Cathodic Protection	Galvanisation
1.	Definition:	It is a method in which a more reactive metal is connected to iron so that it acts as a sacrificial anode.	It is a method of coating iron with a thin layer of zinc to prevent rusting.
2.	Mechanism:	The more electropositive metal (like Mg or Zn) gets oxidised instead of iron, thereby protecting iron from corrosion.	The zinc layer oxidises preferentially and protects the underlying iron even if the coating is scratched or cracked.
3.	Type of Application:	Mostly used for large structures like underground iron pipes, tanks, and ships.	Commonly used for smaller objects like iron sheets, nails, buckets, etc.
4.	Physical Coating:	No physical coating of the protective metal is applied directly on iron; the metals are electrically connected.	A thin physical layer of zinc is deposited over the surface of iron.
5.	Nature of Protection:	Sacrificial protection through electrical connection; iron acts as a cathode.	Sacrificial protection by coating: zinc sacrifices itself and protects iron.
6.	Maintenance:	The sacrificial metal (e.g., Mg block) needs to be replaced periodically after it corrodes.	Once galvanised, it requires less frequent maintenance, as the zinc layer protects until fully consumed.
7.	Example:	Protection of underground pipelines using magnesium blocks connected by wires.	Dipping iron sheets in molten zinc to coat them.