The galvanised iron article is protected against rusting even if the zinc layer is broken?

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Zinc in more reactive in comparison 2 iron....and zinc is react with oxygen n become zno.....but iron is not react because it is less reactive than zn...

Answer

Zinc(Zn) is more reactive in comparison to iron. Zinc(Zn) react with oxygen to become Zinc Oxide(ZnO) but iron does not react because it is less reactive than Zinc.ッッ

Answer

Introduction:

Galvanised iron is a type of iron that has been coated with a layer of zinc to protect it from rusting. This process, known as galvanization, creates a barrier between the iron and the surrounding environment, preventing corrosion and extending the lifespan of the material. While the zinc layer provides excellent protection, it is important to understand what happens if this layer is broken.

The Role of Zinc:

Zinc plays a crucial role in protecting galvanised iron from rusting. When the iron is coated with a layer of zinc, it forms a sacrificial anode. This means that in the presence of moisture or corrosive substances, the zinc will corrode instead of the iron. The zinc layer acts as a physical barrier, preventing direct contact between the iron and the surrounding environment. This barrier is effective in preventing rusting as long as the zinc layer remains intact.

What Happens if the Zinc Layer is Broken:

1. Formation of a Localized Cell:
If the zinc layer is broken, exposing the underlying iron, a localized cell is formed. This occurs due to the difference in electrical potential between the zinc and the iron. The exposed iron acts as the anode, while the surrounding zinc acts as the cathode. This localized cell initiates a corrosion process.

2. Galvanic Protection:
Even if the zinc layer is broken, it still provides galvanic protection to the nearby iron. The zinc, being more electronegative than iron, will continue to corrode sacrificially to protect the exposed iron. This sacrificial corrosion slows down the rate of rusting on the iron surface.

3. Self-Healing:
When the zinc layer is damaged, it can also undergo a process called self-healing. This occurs when the zinc reacts with moisture and carbon dioxide present in the air to form a protective layer of zinc carbonate. This layer acts as a barrier, preventing further corrosion of the underlying iron.

Maintenance and Repair:

In cases where the zinc layer is significantly damaged or corroded, maintenance and repair are necessary to ensure continued protection against rusting. This can involve re-galvanizing the iron by applying a new layer of zinc through hot-dip galvanization or electro-galvanization processes.

Conclusion:

In conclusion, while the zinc layer on galvanized iron provides excellent protection against rusting, it is still possible for the iron to rust if the zinc layer is broken. However, even in such cases, the sacrificial and self-healing properties of zinc continue to provide some level of protection to the exposed iron. Regular maintenance and repair are essential to ensure the long-term durability and rust resistance of galvanized iron.

Similar Class 10 Doubts

Galvanised article is protected against rusting even if the zinc coating is broken. Why?

Why galvanized article is protected even if the zinc coat is broken ?

Which of the following is the incorrect method of preventing rusting?

Which of the following is the incorrect method of preventing rusting?

Which of the following is the incorrect method of preventing rusting?

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