Metallic coatings contain a metallic element or alloy. Metallic coatings can be applied by using a sprayer, electrochemically, chemically or mechanically. These coatings are applied on equipment requiring a shiny or glossy appearance and protection from sunlight, corrosion and oxidation.
A metallic coating forms a corrosion resistant protective layer that can withstand harsh environmental conditions by changing the surface properties of the material on which it is applied. Metallic coatings are usually applied on steel surfaces using one of four common methods:
- Hot dip galvanizing – A process of coating iron, steel or ferrous materials with a layer of zinc. This done by passing the metal through molten zinc at a temperature of 860°F (460°C) to form zinc carbonate (ZnCO3). Zinc carbonate is a strong material that protects steel and can prevent corrosion in many circumstances.
- Thermal spraying – A group of coating processes in which finely divided metallic coating materials are deposited in a molten or semi-molten condition to form a coating. The coating material may be in the form of powder, ceramic rod, wire or molten materials.
- Electroplating – A process of coating a metal with a thin layer of another metal by electrolysis to improve the metal's corrosion resistance.
- Sherardizing – The formation of a corrosion-resistant, zinc-iron alloy coating on the surface of steel or iron. The method involves heating the object in an airtight container that has zinc powder. A thermal diffusion process occurs and the zinc diffuses into the object’s metal surface, forming the zinc-iron alloy.