Question

Necessity of galvanisation of iron articles.

Answer 1

Hint: Galvanisation is the process of applying the protective zinc coating to iron or steel articles to prevent rusting.
The most common method is hot dip galvanizing which iron or steel sections are submerged in a bath of molten zinc.

Complete step by step answer:
Galvanisation is primarily done to prevent rusting of iron and steel. In this process, the steel or iron surface is dripped and coated with melted zinc. The corrosion of zinc is a slow process which gives the article an extended life. After galvanising an article, it would need less maintenance and hence less maintenance cost in the mechanical industrial sector.
The zinc forms a boories that prevents corrosive substances from reaching the underlying steel or iron.
Hence, zinc serves as a sacrificial anode; the exposed steel will still be scratched by the remaining zinc.
Therefore, the zinc protects its base metal by corroding before them.
The outer layer of the zinc of any galvanised material, reacts with the atmospheric oxygen to form zinc oxide $(ZnO)$, which is stronger than zinc. Thus, even if the outer layer of zinc undergoes corrosion, the material is getting coated with a stronger substance $(ZnO)$ and thus its better able to resist corrosion.

Note: 1. The process of galvanisation has three major steps: surface preparation, galvanising process and post surface treatment.
2. Two type of galvanising processing methods have been know for a long time
(a) Hot – dip galvanising
(b) Electro Galvanising