What is Galvanization? Definition, Meaning, Process, Applications


In this article, we will learn what is galvanization along with definition, meaning, process, working procedure, terminologies, types, applications, etc.

Let’s explore!

What is Galvanization? Definition, Meaning

Let’s try to understand the basics of galvanization with definition & meaning!

Galvanization Basics

Let’s learn the galvanization basics! The inventions of metals have been quite essential for humankind. The base of development in any sector is the use of metal.

While using different metals, there are different kinds of prerequisites that are mandatory to be followed.

  • Numerous processes either make the metals stronger or prevent them from getting deficient in their core properties.
  • Corrosion and rust are among the most prominent enemy of any metal.
  • They don’t only make them lose their effective properties but also corrodes them till their extinction.
  • To combat these, there are numerous processes in which Galvanization is the most effective one.

Meaning of Galvanization

So, what is the meaning of galvanization? Galvanization meaning is simply a process that allows the metal to withstand the ill effects of rust and corrosion. Here we are going to discuss the process of Galvanization in detail.

This article will help you understand the core importance of Galvanization and the different techniques engaged in it. It will also help us clear the process’s ideas and get the maximum out of this. Let’s start with the core definition and then to other aspects of the Galvanization.

Definition of Galvanization

Galvanization is the process in which there is an application of protective zinc coating to iron or steel that helps prevent premature corrosion and rust.

One of the prominent advantages of Galvanization is that it helps in the construction and repairing work of steel structures. We can easily attain maximum benefits that lower the repairing and maintenance costs due to its effective properties.

  • There are numerous protective methods available apart from this, but they do have their limitations.
  • When it gets damaged, these methods, such as plastic coating or protective coating, the different parts of the steel get corroded, and any protective coating falls away.
  • This makes any type of protective coating relatively inefficient as well as no-lasting.
  • We cannot expect reliability on these methods, which ultimately needs regular maintenance.

Why Does Galvanization Require?

When we delve into this question, the answer lies in a simplistic approach that helps us understand the core function of Galvanization. Galvanizing a metal provided anti-corrosion properties to the same.

The absence of protective zinc coating exposes the elements and increases the chance of oxidizing, resulting in faster corrosion.

Also, galvanizing steel is cost-efficient as other processes such as using aluminum or stainless steel coating are pretty expensive.

Apart from the corrosion, the following are the probable needs that make Galvanization quite efficient are as follows:

  • Without any protective covering, steel acquired rust because of atmospheric conditions over a gradual period. Though the magnitude of the rust depends upon the environment that the product is in. this makes galvanizing quite important for steel or metals.
  • The comparative corrosion of steel in respect to zinc is relatively high. In Galvanization, we provide a protective film of zinc on steel or any base metal. Because of the protection of zinc to the iron, cathode protection takes place, which prevents even a small part of the base metal from getting into the damages that make it rusty. This cathode protection lies there till the zinc layer is present.

How Does Galvanization Work?

Galvanizing can protect metal in several ways. Firstly, it creates a protective coating that shields the metal from the surrounding environment.

The layer of zinc prevents water, moisture, and other elements in the air from corroding the steel underneath. Should the zinc coating be scratched deep enough, the metal would become exposed and susceptible to corrosion.

  • Galvanizing can also protect metal through a process called “galvanic corrosion.”
  • Galvanic corrosion occurs when two metals of a different electrochemical stage contact an electrolyte present, such as salty water.
  • Depending on the atomic structure of the two metals, one metal is the anode, and the other is the cathode.
  • The anode corrodes more rapidly than it would by itself, and the cathode corrodes at a slower pace than it would.
  • Zinc is used for galvanizing because it has an affinity towards being the anode when in contact with many different types of metals.
  • Since the zinc coating in contact with the base metal is usually the anode, it slows the corrosion of the base metal or the cathode.

Terminologies for Galvanization

Before further discussing Galvanization, it is better to understand some of the basic terminologies that will help us get the holistic idea of Galvanization.

After this, we can situate to the core working procedure of Galvanization.

  • Ash

It is a mixture of zinc oxide and different measures of metallic zinc. The zinc oxide is formed when oxidation takes the place of the zinc on the surface.

In this process, the mere quantity of metallic zinc gets entrapped, removed with the oxide.

  • Dross

This is a compound that is equipped with a metallic mixture of iron and zinc. It forms the galvanizing bath, which results in the reaction of molten zinc with iron.

These settle down at the bath. In this, the Zinc content is available between 95 to 97%.

  • Flux

This is the chemical compound applied on the metal in an aqueous solution and dried on the base metal that is spread over like a blanket with a zinc protective casing.

The prominent function of flux is to keep the surface of the base metal and molten zinc away from the oxide. Keeping the surface free from oxide is quite essential. 

  • White rust

This white corrosion material contains basic zinc carbonate and zinc oxide that gets deposited on the galvanized surface, which is exposed to a moist atmosphere and the water film.

What are the Process of Galvanization?

The process of Galvanization has different sub-processes that should be executed with much care. These processes not only help attain the galvanized products but also helps to attain the same with proper safety; it also helps in efficient preparation that gradually helps in the best possible ways. The following are the core steps that should be considered to get effective results for the metals.

The steps involved in the whole galvanization process are divided into three parts, preparatory, Galvanization, post-treatment, and inspection. In these, the preparation for Galvanization holds the top place. Here we are discussing the same:

Preparation of surface

This is amongst the most crucial step in which the surface of the material is being prepared for the coating process. It is because zinc doesn’t react with unclean materials. This preparation helps remove all the dirt, grease, and other contamination from the surface of the metal. The process is completed by degreasing the metal surface in an acidic bath or hot alkali solution.

Pickling

After cleaning or surface preparation, the material is pickled with the help of an acidic solution which is diluted to an extent. This helps in the removal of rust buildup or scaling deposits. There are some alternatives for this process, such as shot blasting or air blasting that depends on specific industrial needs.

Fluxing

This is the utmost step of the surface preparation. The core objective of this procedure is the elimination of oxides while creating a protective coating. This protection helps in the prevention of the formation of extra oxides.

Process of Galvanizing

After preparing the surface, the core step takes place, which is the galvanizing of metal. The metal, after getting prepped it is submerged in a large pool equipped with pure molten zinc at 460 degrees Celsius. In this, the zinc reacts to the cleaned material and provides a protective layer. When the material or steel gets at the same temperature as the molten zinc, it is withdrawn from the pool. It is then drained and cooled off. This process can take 10 to 15 minutes, depending upon the thickness of the material.

Post-Treatment Processes

The post-treatment process is the last step in which the results are obtained. This process is also termed quenching. In this, the steel is dipped in water or any chemical that helps in creating a protective coating. At last, the excessive zinc drips down off the materials and provides a smooth and clear finish.

Additionally, there are some more steps involved in this last step, which are majorly related to quality checks.

End results inspection

In this inspection phase, the material is checked for different specifications such as weight, the thickness of coating, appearance, etc. it is also being compared with the standards preferred for the same such as ASTM. The coating level can be inspected with the help of two different types of equipment, such as an optical microscope or magnetic gauges. The magnetic gauge is among the most popular ones as it comes under the NDT process.

Weight analysis of protective coating

This is the consecutive step through which the material’s coating weight is being measured. It specifically provides the idea for the volume of zinc-coated on the surface of the material. There are two techniques to get the weight of zinc coating, weight strip weighs and galvanize weigh. It depends on the requirement of the industry to choose the desired technique.

Final step to check for Galvanizing

This is the final step of the whole galvanizing procedure. In this, we check the appearance as well as the finish of the protective coating. Here every section of the material is inspected for coating quality that depends on the specified standards. As we know, zinc reacts with unclean materials, which makes it quite evident to get proper information regarding the same. It also helps in extracting the probable defects which can be rectified after production.

Critical Parameters for effective Galvanization

In the process of galvanizing, some critical parameters play an important role. These parameters are pretty useful and make a chain that ultimately provides effective coating. Here we are going to discuss some of them based on their importance.

  • Zinc quality

The quality ofZincc holds massive importance in the galvanization process as in this process, almost 98% of zinc is used.

  • Galvanizing bath

The galvanizing bath should contain 98% molten zinc, which evenly gets on to make the protective coating.

  • Aluminum additives

Most of the time, aluminum additives are added in the galvanizing bath; however, there is a minimum concentration of the additives. It is used in this process to minimize the rate of oxidation. The continuous addition of additives helps to control the layer thickness.

  • Temperature of bath

The bath temperature also holds adequate importance as most of the protective coating of materials depends on the consistency ofZincc. The material should be galvanized at the lowest possible temperature. It helps in the even drainage ofZincc over the surface. The continuous lower temperature minimizes the formation of dross and ash. The bath temperature should vary from 440 to 460 degrees celsius. The working temperature of the same should lie to 450 degrees Celsius. The temperature of the molten metal shouldn’t exceed 470 degrees celsius.

  • Suspended dross

Dross is the material that should settle at the bottom after the zinc bath. It shouldn’t be disturbed when it lies at the bottom after the dipping operation. The material or metal sheet should be prevented to sunk at the bottom.

  • Immersion rate

The rate of immersion is quite important in the wet galvanizing process. It affects the smoothness and uniformity of the zinc coating. For long metal sheets, the immersion rate should be accurate, and sync of Galvanization should be maintained to provide ultimate precision.

  • Immersion time

Immersion time holds the critical position, which depends on different parameters such as temperature, the thickness of materials, type of job, pre-cleaning of the material, etc.

  • Rate of withdrawal

The rate of withdrawal specifically determines the protective layer thickness of the material. The withdrawal speed of the material helps in attaining the best quality of galvanization product. It should be given proper importance as it is the decisive step when the protective layer is on the material. The withdrawal rate should be maintained effectively in a controlled environment; thus, the zinc drains freely from the material surface.

  • Quenching

Water quenching is the process in which the material is withdrawn through the blanket of flux. The quench water needs to be changed frequently, which helps minimize the formation of the corrosive salts. This needs the tanks to be equipped with overflow weir.

  • Centrifuging

Centrifuging is the process that is needed in the case of small materials Galvanization. The small articles should be centrifuged just after the galvanizing. It should take place when the molten metal is inapt condition. The quality of Galvanization depends on the shift of galvanized material to centrifuge. After the centrifuging process, the materials should be dipped immediately in water, which helps in the complete coating on the material. It also helps in reducing the probability of sticking the materials after Galvanization.

  • Post-treatment

The post-treatment is the last step that helps in the proper inspection of the galvanized materials. In this stepstep, the materials are exposed to different conditions such as moisture, CO2, oxygen, etc. after this, and it is sure that the galvanized material is up to the mark and can be used for production.

The above processes are the core steps in Galvanization that hold practical importance. Without complying with these steps attaining the par level galvanizing products is impossible. 

Types of Galvanizing Processes

When it comes to different kinds of methods of Galvanization, the following are the best ones:

Hot-Dip Galvanizing

This is one of the prominent and popular methods of galvanizing. As the name suggests, this method is also conducted by heating the solution. In this, the steel or iron is dipped in a molten pool ofZincc. This molten zinc is maintained at a temperature of 450 degrees Celsius. This process provides a metallurgical bond between the metal used and the zinc. After this process, the material is dipped out of the solution, reacting with atmospheric oxygen that forms zinc oxide. Gradually the zinc oxide reacts with carbon dioxide to form zinc carbonate, forming a final layer of protective coating. This is among the most economical ways that can be easily executed on different kinds of complex and simplistic shapes. It is prescribed to use these galvanized steel or metals at high temperatures, but when it exceeds the limit of 400degree Celsius, the chances for peeling off the zinc carbonate coating are pretty high.

Galvannealing

This method of Galvanization is the combination of hot-dip Galvanizing and annealing. It is specifically used for providing a specialized coating on the material or steel. This process is also performed via hot dipping annealing, which ultimately produces a matter gray finish touch.  Galvanized steel is quite effective for all the welding operations and also generated a par level of adhesion for paint.

Pre-galvanizing

This is the process of Galvanization that is being attained at the very first stage of production. This process involves rolling the sheet metal with the help of a cleansing agent that makes a path for the prime material of Galvanization. Gradually the material is passed through the molten liquid zinc and effectively recoiled. The main advantage of this process is that the coil of steels can easily be galvanized on a massive scale with a more efficient coating than the other process.  

Electro Galvanizing

Electro galvanizing is one of the rare processes that are unique from others. It doesn’t involve the dipping of the material in the molten zinc. In this process, the electric current is being applied in an electrolytic solution which is gradually applied to the steel. It reduces the positively charged zinc ions to zinc metal. The zinc metal is then deposited into the steel. This is the prior stepstep that has to be attained at the start of the production of any material.

Industrial Applications of Galvanization

There are numerous applications of Galvanization that make it quite efficient. The information about all these applications will help us in a critical understanding of the Galvanization:

  • Solar and wind industries

Sustainable industries are increasing at an exponential pace. Some of the industries, such as wind and solar industries, need Galvanized steel in bulk. This not only reduces the maintenance cost but also decreases the probability of disruption in the service. Most solar projects need galvanized steels that save them from corrosion and rust. These are also popular as they are sustainable and environmentally friendly. It reduces emissions and provides a maintenance-free approach. These galvanized steels are also used for agricultural processes as these types of equipment are prone to water and moisture, which are the main reasons for corrosion or rust. Galvanization effectively provides these industries resilient equipment.

  • Construction industry

Whether it is for commercial or residential purposes, the need for galvanized steel is in demand. Galvanized steel is among the prominent material that has been pretty popular in this industry. Apart from durability, aesthetics is among the best property. Galvanized steel provides a shiny touch and also provides a modern to contemporary touch. These are also used for subsidiary structural construction such as gutters, poles, tubing, fencing, etc.

  • Automotive industry

Galvanization is widely used in the automotive sector for quite a long time. The prominent use of zinc-coated automobile bodies has acquired maximum popularity. Most automotive vehicles use galvanized metals, as we know that the body of a car acquired the maximum percentage of the whole car. The rust and corrosion resistive property make it quite apt for being the marketing tool. With this process, this industry provides its customers anti-rust warranties.

  • Telecommunication industry

As the advancement in technology has increased substantially, the need for low-maintenance tower lines has increased. Hot galvanized steel is prominently used on equipment boxes, phone wiring, etc. that mitigates the need for maintenance and the probable damages.

Benefits of Galvanization

The core benefits of Galvanization will help us to understand the effect of the same. The following are some of the pretty informative advantages as numerous industries utilize galvanized steel to attain the array of benefits it holds. With these advantages, we can understand it deeply:

  • Cost-effectiveness

As compared to other steel treatment processes, Galvanization has a minimal cost associated. In addition to that, the galvanized steel is ready to utilize the product. It effectively doesn’t need additional chores such as inspections, outer film or surface preparation, paintings, protective coatings, etc., which saves a substantial cost.

  • Extended life

The overall life of the industrial steel increases after galvanizing the same. It is expected to withstand a normal environment for 50 years which is substantially low compared to without its usage. Normally these steel withstand 20 years with regular water exposure. In addition to this, it doesn’t need specific maintenance, and also the yield has increased durability, which ultimately helps it be more reliable than normal.

  • The outer coating of zinc

When the material is on the verge of corrosion, the outer coating gets corroded first, saving the steel from rust. The specific areas get minimally corroded as the zinc anode functions as a protective layer for the steel.

  • Resistance against rust

Rust resistance is attained through the zinc coating. As we know that the iron element is quite prone to rust, but the protective film acts as a fire protection for the steel. It acts as a trap for oxygen or moisture, which is the main cause of rust. It also helps to withstand the steel sharp corner and recesses to get damaged from rust or corrosion.

Safety Measures while Performing Galvanization

While performing the Galvanization, it is mandatory to keep a check on the whole process. It includes safety precautions that should be performed while carrying out the process. The following are some of the points that help in performing this process.

  • The galvanizing area should be kept clean and tidy. It is recommended to increase extraction ducts, hoods, and exhaust fans that keep the whole area safe.
  • If the galvanizing is executed in an industrial setup, the workers should be given all the personal protective equipment such as eye or face shield, steel-capped boots, rubber boots, leather or woolen gloves, rubber or leather aprons, long rubber or PVC gloves.
  • While cleaning the materials with sodium hydroxide solution, proper training should be given to them as the solution can cause severe flash burns.
  • There are instances where we use hydrofluoric acids that are used for pickling of casting. It can be very lethal and cause severe burns after it gets into contact with the skin. It should be handled carefully with appropriate PPE’s.
  • There should be arrangements that can protect the Galvanizer from the fumes.

Summary

With all the above information, it is evident that Galvanization acquires a prominent place for the safekeeping of any metal. It not only saves them from corrosion or rust but makes them withstand environmental threats. This excerpt holds all the information about the Galvanization of metals; not only that, with the proper idea about the working procedure and core benefits, we can safely keep the metals. The prominent importance of Galvanization is for industries that deal with metals. Apart from that, the different kinds of galvanization processes make this article worth reading. However, there are more to describe the Galvanization, which needs more time and analysis.

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