Definition - What does Galvanized Steel mean?
Galvanized Steel is an alloy of iron and other elements covered by a zinc coating so as to protect it from corrosion or rust. Galvanized steel has a longer life and is durable as compared to non-galvanized steel. The application process of zinc on a steel structure is called galvanization. This process was invented in France and England in 1837, in which a sheet of steel was dipped in a molten zinc bath (a method called hot dip galvanization).
Petropedia explains Galvanized Steel
When steel is inserted in molten zinc, a chemical reaction takes place, which bonds zinc on the surface of steel. Thus, a zinc layer over steel acts as a layer that protects it from being corroded. The most common method of applying a zinc coating over steel is hot dip galvanization, whereby a steel sheet is dipped in a bath of molten zinc kept at a temperature of 860°F (460°C). When the steel comes into contact with this molten zinc, an iron zinc alloy is formed and when the steel sheet is taken out in a normal atmosphere, zinc oxide is formed. However, there are various other processes that are also used for galvanizing steel, such as:
- Zinc electroplating – In this method, a steel sheet is dipped into the zinc ion solution and an electric current is passed through it, which uniformly spreads zinc ion solution on the metal sheet.
- Mechanical plating – In this method, zinc powder, along with glass beads and a special reducing agent, are coated on the steel sheet, which bonds zinc particles on the surface of the sheet.
- Sherardizing – In this method, a steel sheet is heated up to a temperature of 752°F (400°C) and passed through zinc powder. At this high temperature, diffusion between zinc and steel molecules occurs.
- Continuous strip galvanizing and galvanized wire – In this method, a steel strip or steel wire is passed through a solution of molten zinc at a high speed of 590 feet (180 meters) per minute in a controlled air pumping. This applies a zinc coat on the metal sheet.
- Zinc metal spray – In this method, a steel sheet is cleaned to Class III level and then zinc powder is sprayed on top of it with the help of plasma flame gun.