Galvanizing is one of the most widely used to methods for protecting metal from corrosion.It’s the process of applying a protective zinc coating to steel or iron, to prevent rusting. The most common method is hot-dip galvanizing, in which parts are submerged in a bath of molten zinc.The part is passed through a molten zinc bath, providing a much thicker coating of zinc at a somewhat higher cost compared to electrogalv.
Quite simply, galvanizing a metal gives it anti-corrosion properties. Without the protective zinc coating, the metal would remain exposed to the elements and potentially oxidize and corrode much faster. Galvanized Steelis a cost effective alternative to using materials such as austenitic stainless steel or aluminum in order to prevent corrosion.
Galvanizing is a great rust preventer,there are some advantage:
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Galvanized coatings are metal (zinc), so they are much stronger and harder than paint or powder coating; they will adhere where paint may scrape off or chip off.
Zinc is "anodic" to iron and steel. This means it will corrode preferentially, electrochemically protecting the steel. Even if the coating is scratched through and the steel is exposed, it will be protected the same way zinc anodes protect steel-hulled ships. It will protect iron and steel from rusting where the coating is scratched.
Galvanized coatings are thick. Alternatives like zinc plating (electro-galvanizing) are usually only something like one-fifth to one-tenth as thick as hot dip galvanized coatings. The life of the coating, and the part, is essentially proportional to the thickness of the zinc coating.
What are the down sides of galvanizing?
Because galvanizing is thick, it can't be done on standard nuts and bolts;
Galvanizing is not a very decorative finish,the decoration effect are not better than chrome plating.
Some parts can't be easily galvanized. For example, sealed tubes would be very dangerous to dip into molten zinc because water trapped inside could flash to steam and blow molten zinc out of the dip tank.