Galvanization is the process of applying a zinc coating to steel or iron. Zinc can prolong the life of metal objects because it serves as a sacrificial layer, protecting the steel or iron below.
However, galvanization is a multifaceted process that may be executed in a number of ways. There are several types of galvanizing, including thermal diffusion galvanizing and hot-dip galvanizing, and each has unique benefits and drawbacks. Before using galvanization in a manufacturing or prototype project, it is vital to comprehend its many forms.
Which is why in this reading, we’ll explore what galvanisation is, its application, diagram, types, and how it works. We’ll also explore the advantages and Disadvantages.
Let’s begin!
What is Galvanization?
Galvanization (or galvanizing) is the process of adding a layer of zinc to the outer surface of a metal, namely steel or iron. This lowers the chance of corrosion or rusting by applying a protective covering to the underlying metal.
It may surprise you to learn how ubiquitous galvanized metal is. To guarantee a longer lifespan and sufficient protection from corrosion and damage, galvanized metal can be used to make structures such as building frames, metal benches, balconies, ladders, and fire escapes. Electrical appliances and car parts provide further instances.
Additionally, the usage of galvanized steel and galvanized iron in a variety of industrial processes, such as CNC machining and sheet metal fabrication, makes them indispensable in the manufacturing industry.
The precise method used determines the galvanization process. The most crucial aspect of the procedure, though, is that it usually entails encasing steel or iron in zinc, which can be liquid or dust-like. The iron in the surrounding metal interacts with the zinc when it is added, forming a strongly bound alloy layer.
Application
The following are the applications of galvanization:
- It prevents corrosion in steel and iron, making it widely used in various industries.
- It is commonly used in construction for building frameworks, street furniture, fire escapes, ladders, and balconies.
- It is used in the automotive industry for rust-resistant parts like skeletal foundation, bumpers, beams, frames, and chassis.
- It enhances the lifespan of phone lines and electrical boxes in telecommunications.
Diagram
Types Of Galvanization
These are the main types of Galvanizing:
Hot-dip Galvanizing:
Metal is submerged in a bath of hot zinc that is approximately 450 °C during the hot-dip galvanization process. Upon removal, the coated surface first forms zinc oxide through a reaction with oxygen, followed by zinc carbonate through a reaction with carbon dioxide.
The metal must first be cleansed with a caustic solution and then pickled in an acidic solution before galvanization can occur. Zinc ammonium chloride can also be used to stop the metal from oxidising too quickly before galvanization.
Electro-galvanizing:
Combining galvanization with electroplating, electrogalvanizing involves passing an electrical current through a zinc bath that has a steel conductor and a zinc anode. In addition to producing a brighter surface finish appropriate for cosmetic applications, the method yields a thinner coating than hot-dip galvanization.
Sherardizing:
Sherardising, dry galvanizing, vapour galvanizing, and thermal diffusion galvanizing are some of the names for this type of galvanization. It entails heating steel components in a closed rotating drum filled with zinc dust to 500 °C.
A solidly bonded coating is created on the steel part’s surface by the diffusion of the evaporated zinc. It is perfect for tiny components and those that need interior areas coated.
Galvannealing:
Hot-drip galvanizing and annealing are combined to create galvanising. Before the coated metal is run through air knives to remove any surplus zinc, the hot-dip galvanization process is completed as usual.
After that, the metal is heated to 500–565 °C for a relatively short time in an annealing furnace, which causes the layers of iron and zinc to diffuse into one another and form layers of zinc-iron alloy.
How Does Galvanizing Works
There are several ways that galvanizing may preserve metal. The metal is first shielded from the environment by a protective covering. Water, moisture, and other airborne elements cannot harm the steel underlying because of the zinc coating. The metal would be exposed and prone to corrosion if the zinc covering were sufficiently damaged.
Galvanic corrosion is another way that galvanizing may shield metal. When two metals with dissimilar electrochemical compositions come into contact with an electrolyte that already exists, such as seawater, galvanic corrosion takes place. One metal is the anode and the other is the cathode, depending on their respective atomic structures.
Both the cathode and the anode corrode more slowly and more quickly than one another. Because zinc has an affinity for the anode when it comes into contact with a wide variety of metals, it is used in electroplating. The corrosion of the base metal or cathode is slowed down because the zinc coating that comes into contact with the base metal is typically the anode.
Advantages Of Galvanizing
Here are the following advantages of Galvanizing:
- Blocks Corrosive Substances: Galvanised metal prevents corrosive substances from reaching the weaker substrate, prolonging its lifespan.
- Prevents Rust: Galvanization significantly delays the onset of rust.
- Creates Sacrificial Anode: Zinc coating is consumed by corrosive substances, providing protection until fully used up.
- Lasts a Long Time: Zinc coatings created by galvanization are tough and long-lasting, providing decades of protection.
- Is Affordable: Galvanization is a simple, affordable procedure with minimal expenditure.
- Creates a Thick Coating: Galvanization produces a thicker coating than electroplating.
Disadvantages Of Galvanizing
- Initial Cost: Galvanized can be more expensive than untreated steel or other coated metals, such as aluminum.
- Limited Aesthetics: Galvanized has a distinctive look that may not fit with all design schemes.
- Environmental Concerns: The process of galvanization can have environmental impacts, as it involves the use of toxic chemicals and the production of hazardous waste.
FAQs
What is galvanization process?
Galvanisation or galvanization (or galvanizing as it is most commonly called) is the process of applying a protective zinc coating to iron or steel, to prevent rusting. The most common method is hot dip galvanizing, in which steel sections are submerged in a bath of molten zinc.
Why is zinc used in galvanizing?
The reason that the galvanizing process uses zinc instead of other metals is that zinc oxidizes and experiences acid corrosion “sacrificially” to steel. That means that when zinc is in contact with steel, oxygen and acids will attack the zinc rather than the steel beneath it.
Why is it called galvanization?
This process was one in which cleaned steel was dipped into molten zinc. Because Sorel understood the electrochemical nature of corrosion and why zinc protected the steel, he named the process “galvanization,” after the Italian scientist Luigi Galvani, who had done early experiments in electricity.
What is galvanising in chemistry?
The process of depositing a protective layer of zinc on steel or iron is called galvanization. It is a method used to prevent corrosion.