| Rust causes corrosive metals to change in color and if | | | | handling. This completes the hot-dip galvanizing |
| an object is allowed to rust for a long time, there is a | | | | process. |
| gradual deformation in shape. There are many ways | | | | Hot Dip Galvanizing is done by bonding zinc with steel |
| to prevent rusting. Hot-dip galvanizing is one such | | | | at a molecular level. This allows the coat to cover the |
| option which is widely used for industrial purposes. | | | | whole surface including scratches, joints and even |
| Galvanization is a process by which zinc, a | | | | holes. Since, this process results in a metallurgical bond |
| non-corrosive metal, is coated over corrosive metals, | | | | between zinc and steel with a series of distinct |
| such as iron and steel. Because zinc is more reactive | | | | iron-zinc alloys, it covers the steel not only with a layer |
| than iron or steel, the zinc galvanized coating corrodes | | | | of zinc, but three other layers. The first three layers |
| first, protecting the steel or iron substratum. Hot-dip | | | | used are zinc-iron alloys and the fourth is pure zinc. |
| galvanizing is a form of galvanization. When exposed | | | | The zinc-iron alloy increases the strength of the steel |
| to the atmosphere, zinc reacts with oxygen to form | | | | while the final layer of pure steel prevents any form of |
| zinc oxide. This further reacts with carbon dioxide to | | | | corrosion. |
| form zinc carbonate, a fairly strong material that stops | | | | The appearance of the galvanized surface can vary |
| further corrosion by protecting the steel or iron from | | | | from shiny silver to a dull gray finish depending upon |
| the elements. | | | | factors such as the steel composition, degree of |
| The hot-dip galvanizing process starts by cleaning the | | | | withdrawal from the molten zinc bath and cooling |
| surface of the steel to prepare it for galvanizing. Then, | | | | method employed. The dull gray matte finish provides |
| the parts are dipped in a flux tank typically containing | | | | just as much protection from corrosion as the shiny |
| an aqueous solution of zinc ammonium chloride or they | | | | finish. |
| are fluxed by passing through a layer of molten zinc | | | | Galvanized steel is widely used in applications where |
| ammonium chloride floating on the top of the molten | | | | rust resistance is needed, such as roofing and walling, |
| zinc. | | | | handrails, consumer appliances and automotive body |
| The corrosive metals are coated with a thin zinc layer, | | | | parts. They can be identified by the crystallization |
| by passing the metal through a molten bath of zinc at | | | | pattern on the surface, called spangle. Galvanized |
| a temperature of around 860 °F (460 °C). After | | | | sheet-steel is often used in automotive manufacturing |
| slowly withdrawing the parts from the molten zinc, the | | | | to enhance the corrosion performance of exterior |
| fasteners are spun in a centrifuge while the zinc is still | | | | body panels. Galvanized iron is used in pipes, sheeting, |
| liquid to remove excess zinc. The parts are then either | | | | stakes and wire, among others. |
| air or water cooled to solidify the zinc and to permit | | | | |