Question

What is done to prevent corrosion of metals?

Answer 1

To answer this question, you must recall the necessary conditions for corrosion to occur. The three things that are required for corrosion are the metal surface, an electrolyte and a substance that can accept an electron or an oxidizing agent. Corrosion can be prevented by removing any one of these three requirements.

Complete step by step solution:
Corrosion of a metal can be prevented by the following methods.
Application of a protective coating over the surface of metal:
A cost-effective way for preventing corrosion is the application of a paint coating. The paint coating acts as a shield between the surface of metal and atmospheric moisture thus, avoiding their contact and preventing corrosion. Another alternative is the application of a powder coating. We apply a dry powder over the surface of metal thereby averting its contact with the surrounding corroding agents.
Using Sacrificial Coatings:
Sacrificial coatings involve the coating of the surface of the metal with another metal which oxidizes more readily than the primary metal hence avoiding its corrosion. It can be of two types, namely cathodic protection or anodic protection.

Note:
-Cathodic Protection:
It involves the coating of the surface of metal with another metal which is much more reactive than it. A common example of cathodic protection is galvanization in which zinc, which is a more active metal than iron forms the coating and when in contact with oxygen, it corrodes before the iron surface thus preventing its corrosion.
-Anodic Protection:
Anodic protection involves the coating of the surface of the metal with a less active metal, like tin coating on iron. The protective layer does not corrode, and thus will protect the surface as long as it is in place.