Galvanization is a simple, cost-effective, and highly practical process used to enhance the surface properties of various materials. By depositing a thin layer of zinc (Zn) on the surface of metals and alloys, this process creates a protective coating that plays a crucial role in preventing corrosion and oxidation, thereby improving the resistance of the materials to environmental factors. While stainless steels can be used for applications requiring high corrosion resistance, they are often expensive. As a result, galvanization becomes a popular method for enhancing the chemical resistance of metals, especially steels.
Galvanized products tend to have a higher price compared to those without coating, mainly due to the added cost of the zinc layer. However, the overall cost of the galvanization process and the finished products remains lower than that of stainless steels. Before buy zinc ingot for the galvanizing process, it is suggested that you read this article carefully to familiarize yourself with the tips of this process.
What is Galvanization?
Galvanization is a surface coating method that uses zinc as a protective layer. By depositing zinc on the surface of metals, the resistance to corrosion and rust is improved, leading to increased lifespan and performance of the treated components.
In this process, a very thin layer of zinc, with a thickness of a few microns, is applied to the surface. However, if zinc is directly applied to the steel surface, it forms a brittle iron-zinc (Fe-Zn) intermetallic compound that easily breaks during forming processes, compromising the coating. To prevent this, aluminum is used. An aluminum layer is applied to the steel surface first, followed by the galvanized layer, ensuring proper adhesion without brittleness.
Types of Galvanization Methods
There are two main methods for applying galvanized coating on metal surfaces, each with differences in achievable thickness, surface quality, coating uniformity, and cost.
Hot-Dip Galvanization
In this method, the desired metals are immersed in a molten zinc bath to form a coating on their surfaces. The metal surface is first well-polished to remove any impurities and oxides, ensuring better adhesion of the coating. An intermediate aluminum layer is applied before the piece is immersed in the molten zinc bath.
Advantages of this method include high production speed, substantial coating thickness, cost-effectiveness, and process simplicity. However, the coating created by the hot-dip method may not be as uniform as that achieved by the cold galvanization method, and there is limited control over the thickness.
Cold Galvanization or Electro-Galvanization
In this method, zinc is deposited on the cathode (steel substrate) by applying an electric current between cathode and anode (zinc metal). Unlike hot-dip galvanization, there is no use of a molten zinc bath in electro-galvanization. To improve the coating quality, various materials are used for refining the grain structure continuously.
Advantages include the ability to control coating thickness and uniformity, but the coating is generally thinner compared to the hot-dip method. Cold galvanization tends to be more expensive than hot-dip galvanization.
Advantages and Disadvantages of Galvanization
In general, the galvanization process is simple, cost-effective, and suitable for large-scale implementation. It provides acceptable chemical properties and proves to be economical compared to using expensive alloys like stainless steel. However, galvanized coatings are susceptible to mechanical damage such as scratches and impacts. If the coating is separated, the underlying steel is exposed to corrosion, necessitating reapplication or painting.
Welding Galvanized Products
One challenge with galvanized products is the difficulty in welding them. The melting point of zinc is around 420 degrees Celsius, and the boiling temperature is 907 degrees Celsius. During welding, the zinc coating evaporates due to the high heat input (900 to 1100 degree Celsius), leading to increased fumes and the removal of more protective coating. To weld galvanized products, the galvanized coating must be removed from the welding area, and after welding, the area should be re-galvanized or repaired using painting.
Applications of Galvanized Products
Galvanized products find applications in various industries due to their desirable corrosion resistance and reasonable pricing. They are used in constructing tanks, containers, capsules, pipes, various structural sections, and roofing. Galvanized steel sheets are crucial in shipbuilding and automotive industries. Additionally, galvanized sheets serve as a base material for producing colored sheets used in manufacturing household appliances and various roofing types.
Buying Zinc Ingots for the Galvanization Process
As zinc is a crucial element in the galvanization process, industries involved plating or electrodeposition and coating seek high-quality zinc at reasonable prices. If you are looking to procure zinc ingots, we recommend considering buy zinc ingot from Iran. Iran stands as one of the world’s leading producers of zinc, and the quality of zinc ingots produced in Iran is commendable. For more information on import zinc from Iran at competitive prices, feel free to contact us.
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