Galvanized Metal: Process, Benefits, Applications

1. Definition of Galvanizing

Galvanizing refers to a surface treatment technology that coats a layer of zinc on the surface of metal, alloy, or other materials for aesthetic and rust-proof purposes.

This method mainly uses hot-dip galvanizing, the purpose of which is to form a layer of zinc on the metal surface to achieve aesthetic and rust-proof effects.

2. What is galvanized metal?

‌Galvanized metal‌ refers to the process of adding a layer of zinc to the outer surface of a metal, such as steel or iron. The main purpose of this process is to add a protective coating to the underlying metal to reduce the likelihood of corrosion or rust.

This zinc coating acts as a shield, ensuring that the metal underneath is not affected by environmental factors such as moisture, chemicals, or salt. This makes galvanized metal an ideal choice for projects that require longevity and durability.

3. What Types of Metals Can Be Galvanized?

Galvanization works primarily with iron and steel. These metals are commonly used in construction, automotive, and industrial applications, where their strength is needed but must be protected against rust.

Other types of metal can also be galvanized. Generally, ferrous metals like cast steel, cast iron, malleable iron, hot-rolled steel, and cold-rolled steel can all receive this treatment.

Other metals, such as aluminum, are not typically galvanized because they have natural corrosion resistance.

4. Galvanization Process: How Does Galvanizing Protect the Base Metal?

Galvanization involves adding a layer of zinc to the surface of metals like steel and iron. There are various methods of galvanizing, each with its process, though they all share a common goal: to surround the steel or iron with zinc.

Zinc can be applied in liquid or powder form. Upon the introduction of zinc, the iron present in the metal substrate will react with the zinc to create tightly bonded alloy coatings. It is a relatively straightforward coating that makes a fairly thick coating.

The galvanization process can be divided into three main stages:

1. Preparation of the Metal Surface: Ensures the metal is clean and ready for coating.
2. The Actual Galvanizing: Applies the zinc coating.
3. Post-Galvanizing Surface Treatment: Enhances the final coating’s appearance and durability.

Galvanization protects the metal based on several principles:

• Barrier Protection: The zinc coating forms a physical barrier against corrosive substances like acids, caustics, alkalis, and gases.
• Sacrificial Anode: If the coating is scratched, zinc acts as a sacrificial anode, corroding itself instead of the base metal to prevent rusting.
• Enhanced Corrosion: Zinc corrodes faster than the base metal, further protecting it. Some manufacturers add chromate to accelerate this process.

Importance of Proper Preparation and Post-Treatment

• Preparation: Insufficient preparation can hinder the reaction between the base metal and the molten zinc.
• Post-Treatment: Inadequate post-treatment can compromise the appearance and quality of the final coating.

By ensuring thorough preparation and proper post-treatment, the effectiveness and quality of the galvanized product can be maximized.

5. Different Methods of Galvanizing

Galvanizing is a common metal surface treatment technology used to improve the corrosion resistance and service life of metals. According to different process principles and application scenarios, galvanizing can be divided into the following categories:

• ‌Hot-dip galvanizing‌ (also known as hot-dip galvanizing):

This is a method of immersing metal parts in molten zinc to cover their surface with a layer of zinc. Hot-dip galvanizing has good bonding strength, but the process is relatively complex and the production cost is high.

The coating thickness of hot-dip galvanizing is between 45~55μm, with good corrosion resistance. It is mostly used in steel pipe towers, steel pipe poles, angle steel towers, photovoltaic power generation, and other projects‌.

• Electro galvanizing:

This is a method of attaching zinc ions to the metal surface using an electrolytic reaction. Electro galvanizing has a simple process and high production efficiency and can be widely used in the anti-corrosion treatment of various metal materials.

Electro galvanizing can be divided into many types, such as hanging galvanizing and rolling galvanizing, and according to the different chemical solutions used, it can also be divided into acid galvanizing alkaline galvanizing, etc.‌

• ‌Mechanical galvanizing‌:

This is a relatively traditional galvanizing process. The zinc powder is attached to the plated part by mechanical collision and chemical adsorption to form a coating.

However, with the continuous maturity of new processes, mechanical galvanizing has been eliminated. The commonly used processes are hot-dip galvanizing and electrogalvanizing‌.

• ‌Powder zincification‌:

This is a coating formed by the diffusion reaction of zinc and iron, and its main component is δ phase (FeZn17). The characteristics of powder zincification are that the infiltration layer is relatively uniform, and no hydrogen embrittlement and deformation will occur.

It is particularly suitable for fasteners such as nuts and bolts and small hardware products.

The layer coverage protection ability of powder zincification is good, and its ability to resist atmospheric corrosion is better than electro-galvanizing.

• ‌Coating galvanizing‌:

This is a method of directly coating zinc paint on the metal surface to form an anti-corrosion protective layer.

The coating galvanizing process is simple, but the coating bonding force is relatively weak, which is suitable for occasions with low anti-corrosion requirements‌.

 

These different galvanizing methods have their characteristics and are suitable for different application scenarios and needs.

Choosing a suitable galvanizing method is crucial to improving the corrosion resistance and service life of metal products‌

6. Benefits of Galvanizing Sheet Metals

• Enhanced Durability: The zinc coating provides a strong layer of protection, increasing the lifespan of the metal by preventing rust and corrosion.
• Comprehensive Protection: Galvanizing offers complete coverage, ensuring the base metal is fully protected, even in corners and hard-to-reach areas.
• Cost-Effective Solution: Galvanizing is a relatively affordable process compared to other corrosion prevention methods, offering long-term savings due to reduced maintenance needs.
• Reliable Coating: The galvanized layer is tightly bonded to the metal, providing a dependable barrier against environmental factors, especially in harsh conditions.
• Fast Turnaround: The galvanizing process is efficient, allowing for quicker production times compared to other surface treatments.
• Low Maintenance: Galvanized metals require minimal upkeep, lowering the need for frequent repairs or replacements.
• Sacrificial Protection: The zinc layer acts as a sacrificial coating, meaning it corrodes in place of the base metal, ensuring the integrity of the core material.

7. Industry Applications of Galvanized Metal

‌Galvanized metal is widely used in the industrial field, mainly due to its excellent anti-corrosion properties, which can significantly improve the durability and safety of metal products. ‌

Applications for galvanized metal cover a variety of industries, including but not limited to:

• ‌Construction Industry‌:

In the construction industry, galvanizing lines are used to process steel and metal structural parts for construction. The zinc layer formed through the galvanizing process can effectively prevent rust and corrosion and extend the service life of structural parts.

Whether it is building framing, roof panels, or exterior wall decoration, the use of galvanized steel can significantly improve the durability and safety of your building‌1.

• ‌Automotive Industry‌:

The automotive industry has high requirements for the corrosion resistance of metal materials. Galvanizing lines are widely used in automobile manufacturing and are mainly used to process body steel plates and chassis components.

The galvanized layer can effectively prevent body parts from being corroded by environmental factors such as salt and moisture during driving, thereby improving the durability and safety of the car.

• ‌Power Industry‌:

Metal structural parts such as transmission lines and substation equipment in the power industry need to be exposed to the outdoor environment for a long time and face harsh natural conditions.

Galvanized wire can provide effective anti-corrosion protection for these equipment, ensuring stable operation under various environmental conditions.

• ‌Agricultural machinery‌:

Agricultural machinery is often exposed to wet soil and chemical fertilizers during work and faces a greater risk of corrosion. Galvanized wire provides effective protection for metal parts of agricultural machinery and reduces damage caused by corrosion‌.

• ‌Transportation facilities‌:

Transportation facilities such as bridges, light poles, signs, etc. need to withstand the influence of the external environment for a long time.

The application of galvanized wire can provide these facilities with a durable protective layer to prevent rust and corrosion, increase the service life of transportation facilities, and reduce maintenance frequency‌.

• Marine and Outdoor Applications:

Boats, docks, and outdoor furniture benefit from the corrosion-resistant properties of galvanized metals.

In addition, galvanized metal also plays an important role in many aspects such as industrial manufacturing, safety protection, and equipment protection.

For example, in factory workshops, warehouses, and other places, galvanized mesh is used to make industrial protective nets and isolation nets to protect equipment and personnel.

8. How to Identify Galvanized Metal?

The methods of identifying galvanized metal mainly include observing the process, appearance, coating thickness, and the use of paint. The following are specific identification methods:

• ‌Observe the process‌:

Hot-dip galvanizing is to immerse the workpiece in molten zinc liquid to form a uniform and non-porous coating, while cold-dip galvanizing (electro galvanizing) is to place the workpiece in a solution containing zinc salt through electrolysis and pass the current to deposit zinc ions on the surface of the workpiece to form a coating.

Therefore, the processing technology of hot-dip galvanizing includes degreasing, pickling, and immersion in a molten zinc liquid pool, while cold-dip galvanizing is processed by electrolytic equipment‌.

• ‌Observe the appearance‌:

The appearance of hot-dip galvanizing is slightly rough and may produce process watermarks, drips, etc., and the overall appearance is silvery white.

The appearance of cold-dip galvanizing is relatively smooth, and the color may be yellow-green or colorful, such as seven colors, bluish-white, white with green light, etc.‌.

• ‌Measure the coating thickness‌:

The coating thickness of hot-dip galvanizing is usually above 10 microns, while the coating thickness of cold-dip galvanizing is generally between 3-5 microns.

This can be accurately measured by professional thickness measurement tools ‌.

• ‌Observe the paint surface‌:

In some cases, the condition of the paint surface can be observed to assist in judgment.

The hot-dip galvanized paint surface is uniform and has no pores, while the cold-dip galvanized paint surface may have more pores, which can be observed by the naked eye or after simple surface treatment ‌.

In summary, by combining the above methods, it is possible to more accurately identify whether it is hot-dip galvanizing or cold-dip galvanizing.

It should be noted that these methods require certain professional knowledge and practical experience. For non-professionals, it may be necessary to use professional tools or consult professionals to make accurate judgments ‌

9. Galvanized Metal vs. Non-Galvanized Metal

• Corrosion Resistance: Galvanized metals outperform non-galvanized metals in terms of corrosion resistance.
• Maintenance Requirements: Non-galvanized metals require more frequent maintenance to prevent corrosion.
• Lifespan Comparison: Galvanized metal lasts significantly longer in harsh environments compared to untreated metal.
• Cost Differences: Though galvanized metals may be more expensive initially, their long-term cost savings in reduced maintenance and replacements make them a more economical choice.

10. Challenges and Limitations of Galvanized Metal

While galvanized metals offer many benefits, they come with a few challenges:

• Welding Difficulties: Welding galvanized metals can release toxic fumes and may require additional precautions.
• High-Temperature Limitations: Galvanized coatings may deteriorate under high-heat applications, making them unsuitable for certain environments.
• Galvanic Corrosion: When galvanized metals are paired with dissimilar metals, galvanic corrosion can occur, potentially degrading both materials.

11. How to Care for and Maintain Galvanized Metal

• Cleaning Methods: Regular cleaning with mild detergent and water can help maintain the appearance and integrity of galvanized metals.
• Inspecting for Damage or Rust: Periodic inspections for signs of damage or corrosion are recommended to catch issues early.
• Best Practices for Extending the Life of Galvanized Products: Avoid prolonged exposure to harsh chemicals and maintain a protective coating where necessary.

12. Sustainability and Environmental Impact

The sustainability and environmental impact of galvanized metal are crucial, especially considering its production and use. Galvanizing, which coats metal with zinc to prevent corrosion and extend service life.

However, traditional methods can lead to environmental pollution, including waste emissions and water resource consumption.

To promote sustainability, environmentally friendly galvanizing equipment uses closed systems and recycling technologies to reduce waste and pollution.

These systems isolate and treat harmful substances while recycling solutions and waste liquids, improving resource efficiency. Energy-saving features like advanced heating and electrolysis technologies further reduce resource consumption.

Manufacturers are also adopting green practices by promoting energy conservation, reducing emissions, recycling waste, and encouraging green procurement.

These initiatives protect the environment and enhance resource recycling, supporting sustainable development.

The long lifespan of galvanized metal helps minimize environmental impacts by reducing the demand for new materials.

In summary, adopting eco-friendly technologies in galvanizing improves environmental outcomes and promotes sustainability through reduced pollution and efficient resource use.

13. Conclusion

Galvanized metal provides a durable, cost-effective solution for a wide range of industrial and commercial applications.

Its ability to resist corrosion, withstand tough environmental conditions, and offer longevity makes it invaluable in industries such as construction, automotive, and telecommunications.

With proper care and maintenance, galvanized metal can continue to perform reliably for decades.

If you are not sure which material or surface treatment to choose for your product, let the experts at DEZE help you. We have extensive knowledge of surface treatment and quality manufacturing services.

The perfect combination of professional technicians and advanced technology helps us provide excellent service.

Contact us for metal processing today and let us turn your ideas into reality.

FAQs

How can I tell if a metal is galvanized?

Look for a uniform, dull gray coating with a slight texture. Alternatively, use a magnet to test if the metal is magnetic, as some galvanized coatings can affect magnetism.

Which is better, aluminum or galvanized steel?

The choice depends on the application. Aluminum is lighter and naturally corrosion-resistant, while galvanized steel is stronger and can be more cost-effective.

Both have their strengths, so the decision should be based on specific project requirements.