Methods of Prevention of Corrosion

Corrosion is the refined metal that is naturally changed to a stable form such as oxide, hydroxide, or sulphide, this causes material degradation. And it is an oxidation process.

When a metal reacts with oxygen, hydrogen, electricity, or another substance like dust or bacteria, it degrades. Even when metals such as steel are exposed to heavy pressures, corrosion can occur, causing the substance to split.

When iron is exposed to oxygen and water, it corrodes and produces red iron oxide, which is generally known as rust. Iron alloys, such as steel, are also subject to corrosion. Iron corrosion can also occur when iron reacts with chloride in an oxygen-free environment, while green corrosion is created when iron or iron hydroxide reacts directly with oxygen.

Iron converts to Iron (III) oxide in the presence of atmospheric oxygen. The chemical reaction of the rusting process of iron is as follows;

Types of corrosion:

• Uniform corrosion:

The most prevalent type of corrosion is uniform corrosion. It is defined as the corrosive environment attacking the entire metal surface exposed to it, resulting in homogeneous metal loss from the exposed surface. The metal thins out and eventually breaks down.

• Galvanic corrosion:

Galvanic corrosion, also known as bimetallic corrosion, is an electrochemical process in which one metal corrodes more quickly than another when in contact with an electrolyte. Galvanic corrosion happens when two different metals are electrically linked and submerged in a conductive solution.

• Crevice corrosion:

Crevice corrosion occurs when a stagnant solution in crevices, such as around the edges of nuts and rivet heads, attacks metal surfaces. When dust, grit, and other corrosive particles are accumulated on surfaces, they create an environment in which water collects and corrodes the component.

• Pitting corrosion:

It is a type of corrosion that results in cavities or “holes” in the material. Pitting is regarded as a more harmful form of corrosion than uniform corrosion because it is more difficult to detect, anticipate, and design against. Corrosion products are frequently used to cover pits.

• Exfoliation Corrosion:

It is a type of intergranular corrosion in which a metal is attacked selectively at or near grain boundaries. Corrosion products generated in this process compel metal to move away from the material’s body, resulting in a layered structure.

• Dealloying:

Dealloying is an electrochemical reaction in which one of the alloy’s constituent elements is selectively separated and eliminated, causing the alloy’s essential properties to deteriorate.

• Erosion Corrosion:

Erosion Corrosion is the breakdown of a material’s surface caused by mechanical activity, such as impinging liquid, slurry abrasion, or suspended particles.

• Stress corrosion:

Another type of corrosion that is essential in many industries, including civil structures, is stress corrosion. When a material exists in a relatively inert environment yet corrodes due to applied stress, it is called stress-corrosion. Externally applied or residual stress are both possibilities.

How to prevent Corrosion:

• Make use of drying agents.

• Backfill with a layer of backfill, such as limestone, then install underground plumbing.

• Use corrosion-resistant metals like stainless steel or aluminium.

• Maintain the cleanliness and dryness of the metal surface.

• Use a grease, oil, paint, or carbon fibre coating as a barrier or coating.

• Backfill with a layer of backfill, such as limestone, then install underground plumbing.

Different methods of prevention of corrosion:

• Galvanization:

The process of applying a protective layer of zinc to steel or iron to prevent corrosion is known as galvanization or galvanising. Hot-dip galvanising is the most prevalent procedure, in which the pieces are immersed in a bath of molten hot zinc. 

• Anodization:

Anodizing is the electrolytic process of coating metals such as aluminium and copper with a thin and strong layer of their oxides.

When aluminium is anodized, it forms a thin film of aluminium oxide on the surface. This reduces the amount of time that aluminium metal comes into contact with oxygen and water, preventing corrosion.

As a result, the anodization procedure is beneficial in preventing aluminium corrosion.

The following chemical reactions occur during the anodization reaction:

Negative terminal (cathode):

Reduction:

Positive terminal (anode):

Oxidation:

(Oxidation)

The aluminium ions now react:

Overall reaction:

• Alloying:

Alloying prevents rust by mixing multiple metals or elements that interact with one another to generate a protective layer on top of the metal’s surface. This barrier prevents oxygen and air from passing through the metal’s surface and into the interior structure.

• Electroplating:

The electrodeposition of a metal onto the surface of a steel or iron product is known as electroplating. This metal coating functions as a sacrificial barrier, slowing or even preventing corrosion on the underlying material, referred to as the substrate.

For example, Nickel electroplating:

• Tinning:

Tinning is the process of applying a thin layer of tin to sheets of wrought iron or steel, resulting in a tinplate.

Conclusion:

Corrosion occurs when a refined metal is naturally transformed into a stable state like oxide, hydroxide, or sulphide, resulting in material degradation. It’s also an oxidation procedure. When iron comes into contact with oxygen and water, it corrodes and creates red iron oxide, sometimes known as rust.