Corrosion Examples, Reactions and Effects

When materials react with the surrounding environment or medium, electrochemical and chemical reactions occur which destroy the material. This is called corrosion of materials. Most of the time, the term corrosion is used in the case of metals. Rusting iron is the best example of metal corrosion. Corrosion is an undesirable event that happens to metals and other materials. The phase of corrosion may be slow but it will affect the core of the metal and decrease stability. There are different types of corrosion according to varying conditions of the material. Pitting Corrosion, Uniform Corrosion, Metal Dusting, High-temperature Corrosion, Microbial Corrosion, Galvanic Corrosion are some types of Corrosions.

Corrosion Example

If we observe our surroundings, corrosion is a visible event present everywhere. Corrosion may inhibit all the good properties of a material, and gradually it will destroy the whole material. Anode reactions, silver corrosion, copper corrosion, corrosion of iron are some examples of corrosion. 

Now we will briefly discuss all these examples.

Copper Corrosion:

This type of corrosion affects the things that are made with copper and copper alloys. The main reason for copper corrosion is exposure to the atmospheric air. The exposure will oxidise the copper. Oxidation will tarnish the surface of copper. Gradually, after years, the tarnish which was there on the surface will change colour into brown or black, and at last into the green.

Cu + H2O + CO2 + O2→ Cu(OH)2 + CuCO3

Here this is a simple reaction of mist air with copper. The formed Cu(OH)2 (Copper hydroxide) and  CuCO3 (Copper carbonate) is the green deposit seen on the surface of things that are made with copper.

Iron Corrosion: Rusting which is known as Corrosion of iron occurs in presence of moisture and water. The chemistry involved in the corrosion of metals is difficult to understand, that’s why we use an electrochemical phenomenon to make it easy to understand. The oxidation reaction of corrosion of iron is given below:

Anode:  2Fe→ 2Fe2+ + 4e-

Electrons given out during anode reaction move through the metal and move to another spot on the metal and that reduces oxygen in presence of H+. The reaction is given below for the following process,

Cathode:  O2+ 4H+ + 4e- → 2H2O 

The overall reaction is given below:

2Fe + O2 + 4H+ → 2Fe2+ + 2H2O

Silver Corrosion: Resistance of silver towards corrosions is well known. When the exposure of silver happens to the air, on the surface of silver we can observe a thin layer of (Ag2S) silver sulphide. A chemical reaction occurs when sulphur attacks silver. This attack of sulphur will cause a little colour change into brownish-black. Pits and black fissures are also seen. Although the colour change is visible, the chance of metal loss is very less. 

Salts can catalyse this reaction. There is sulphur present in the rubber band, this is why a black strip is seen on metals that are tied by rubber bands.

Polishing is done to remove the black matter that has been deposited over silverware. But polishing may result in the removal of a thin layer of silver.

As we said before, When the exposure of silver happens to the air, on the surface of silver we can observe a thin layer of (Ag2S) silver sulphide. Now the formed (Ag2S) silver sulphide will react with (H2S) Hydrogen sulphide which is present in the atmosphere. 

Here is the reaction to this:

2Ag(s) + H2S(g)  →  Ag2S(s) + H2(g)

Effects of Corrosions:

We are aware that corrosion is an undesirable event that happens to metals and other materials. The phase of corrosion may be slow but it will affect the core of the metal and decrease stability. There are many severe changes that happen due to corrosion. Deterioration of historical monuments, failure of equipment, deterioration of pipelines, are some examples. Most of these happen due to severe air pollution. We know that air pollution in the whole world is becoming worse day by day. Almost all man-made monuments and equipment are affected by air pollution. When the air pollution increases, the rate of corrosion also increases. The hike in the rate of corrosion will affect almost all industries, communication systems, monuments, vessels, cars, gates, household electronics, outdoor furniture, and household tools. Decreasing air pollution and taking the necessary measures to prevent corrosion are the only ways to decrease the rate of corrosion.

Prevention of  Corrosion:

Corrosion as we said before is an undesirable event that happens to metals and other materials.  Preventing metals from corrosion plays an important role in increasing the life of equipment or an object. A very common method of preventing such corrosion is to prevent the surface of the metallic object from coming in contact with the earth’s atmosphere. This can be achieved by painting the surface with paints or chemicals like bisphenol. Like this, there are different methods to overcome Corrosion some of them are: 

1.Painting

2.Enameling

3.Tarring

4.Galvanizing 

5.Electroplating

6.Tin plating

Conclusion 

In this article, we discussed what corrosion is, examples of corrosion with many types of reactions and their effects, and also methods to prevent corrosion. When materials react with the surrounding environment or medium, electrochemical and chemical reactions destroy the material. This is called corrosion of materials. Most of the time, the term corrosion is used in the case of metals. Corrosion affects the surfaces of metallic objects with oxides present in the moisture or water. A few general examples of corrosion are the rusting of iron, tarnishing of silver, and the appearance of green colour in copper. Due to corrosion, lots of buildings, bridges, and ships that are constructed using iron get affected. There are so many effects that happen due to corrosion. Deterioration of historical monuments, failure of equipment, deterioration of pipelines, are some examples. Most of these happen due to severe air pollution.