Hot Dip Galvanized
Hot Dip Galvanizing is the process of coating iron or steel materials with molten zinc. This process protects the materials against corrosion and extends their life. The Hot Dip Galvanizing process consists of the following stages:
Surface preparation: Rust, oil, dirt and other contaminants on the material are cleaned. For this purpose, alkali bath, acid bath and washing bath are used.
Flux coating: The material is immersed in a bath containing zinc ammonium chloride solution. This process makes it easier for the material to react with zinc and prevents oxides on the surface.
Galvanizing: The material is immersed in a molten zinc bath at 450-465 °C and its entire surface is coated with zinc. During this process, an alloy layer is formed between the iron and zinc.
Cooling: After the material is removed from the zinc bath, it is cooled in air or in a water bath. This process allows the zinc layer to harden and adhere.
Hot Dip Galvanizing process is a method that increases the quality and durability of iron and steel products used in various sectors. Companies that perform this process are located in different regions of Turkey. Hot Dip Galvanizing prices vary depending on the companies, size, weight and shape of the material.
Hot dip galvanizing (HDG) is the process of dipping steel into a pool of molten zinc. It has a distinct advantage over similar corrosion prevention methods. While the steel material is in the zinc pool, it reacts with molten zinc and an alloy coating is formed that provides superior protection to the steel. A hot dip galvanized (HDG) product can last for years without requiring any maintenance or repairs.
The causes and mechanism of corrosion are the same for almost all metals. While the main cause and formation mechanism is based on electro-chemical reasons, the effect characteristic on different metals also varies due to changing parameters.
Corrosion poses a serious danger to structural steel. Corrosion formation; It starts with rusting, which is the result of different atmospheric environments, and increases faster on unprotected surfaces than on protected ones.
Corrosion that occurs as a result of atmospheric conditions is a chemical degradation. Iron and steel materials are affected by these different atmospheric conditions and lose their physical, chemical, electrical and other properties. Therefore, rust that occurs as a result of corrosion is not only an appearance defect, but also a chemical reaction that corrodes the metal and reduces its lifespan.
Iron and steel are the metals that are most rapidly oxidized and destroyed in the atmosphere. Therefore, the most effective, economical and definitive solution to protect steel surfaces from contact with the atmosphere is to coat them with zinc using the hot dip galvanization method.
Hot dip galvanized coating is the coating of steel and iron by dipping them in molten zinc. The entire surface of the material is covered with zinc up to the most critical points. The coating surface, which initially has a shiny appearance, becomes matte over time and forms a protective zinc layer in matte gray color.
Hot Dip Galvanizing is the process of applying a protective coating containing zinc and zinc compounds to the surface of iron and steel materials immersed in a molten zinc bath. The protective coating usually consists of several layers. Those close to the base metal are composed of iron-zinc compounds. The outermost of these layers, which are located on top of each other, is a layer consisting entirely of zinc.
As a result of the reactions developing between Fe-Zn in materials coated with zinc by the Hot Dip Galvanizing method, Fe-Zn phases are formed within the coating. (eta, zeta, delta, gamma). Starting from the base of the steel, each layer contains zinc in increasing amounts up to the outer surface. Therefore, there is a gradual transition towards Fe-Zn phases, which provide a strong bond between the base metal and the coating. The top layer is the zinc layer and provides shine. Over time, this layer leaves itself to nature under atmospheric conditions and the brightness disappears. After this stage, the second layer, the zeta layer, provides the real protection.
This protection delays corrosion from 15 years to 80-100 years. Such protection is not available in any biologically based protection (paint). In places of damage to the paint and plastic coating, the metal rusts and removes the coating layer. Therefore, such coatings are not safe and long-lasting compared to hot-dip zinc coating. It also requires constant maintenance over time. Just as you cannot prevent the material from being damaged; You cannot prevent the formation of rust in the damaged area, which progresses into the material. In this sense, the most rational and definitive solution to protect iron and steel against rust is to coat metal surfaces with the "hot dip galvanization" method. This method provides a coating that is more resistant to external influences and has the longest protection life, with the alloy layers formed on the material surface as a result of the metallurgical bond between the metal surface and zinc.
In the hot-dip galvanizing process, molten zinc reaches all the details of the steel, such as edges and corners, and forms a holistic coating, protecting iron and steel materials against atmospheric, underground and underwater corrosion, and ensuring sealing. Thus, it prevents corrosion of steel in areas where paint cannot reach. In paint coating applied directly to metal surfaces, rain or air humidity leaking through the cracks reaches the steel and causes rust to form, which causes the paint to peel off over time.
Although paint seems more appropriate when evaluated in terms of cost, it is also understood that hot dip galvanization is more economical, considering the ability of galvanized steel to resist corrosive environments and its long life.
Corrosion protection is crucial for projects where steel is exposed to the atmosphere and other harsh environments. Generally, for large construction projects, the goal of long life, durability and 50 - 100 years of corrosion protection is emphasized.
The reason for the wide usage area of hot dip galvanization is the three-layer protective feature of the coating. Like a barrier coating, it completely covers the steel surface and protects the steel from corrosive effects by creating a metallurgical bond. Even if damage or a small discontinuity occurs in the coating, zinc protects the steel by sacrificing itself in this area. Finally, when the coating decomposes naturally, an additional layer of protection is created on the surface.