Question

What is key mechanism of defence by hot dip galvanizing?

Answer

Hot dip galvanizing protects steel or iron from corrosion by-

(i) It figures a metallic zinc and zinc-iron alloy covering on top of steel surface. This zinc coating reacts with humidity in atmosphere to from zinc salts that act as an insulating layer for steel or iron.

(ii) Zinc is higher than steel or iron in galvanic series and when these different metals with unlike electrical potential are in contact, zinc anode corrodes and offers sacrificial guard to steel or iron and hence steel or iron is protected from corrosion.