Factors Influencing Corrosion Essay

Factors influencing corrosion and its control

Corrosion is a process by which metals get converted into their more stable oxide. It is the process of the gradual eroding of metals by chemical reaction with their environment. When corrosion happens in the case of Iron, it is called Rusting and in the case of silver, it is called Tarnishing. Corrosion degrades the structural property of the materials like strength and appearance.

There are two types of corrosion:

• Dry or Chemical Corrosion

• Wet or Electrochemical Corrosion

Dry or Chemical Corrosion: Dry or Chemical corrosion occurs by chemical attack of atmospheric gases like Oxygen , halogens or Hydrogen Sulphide etc. on the surface of the metal.

Wet or Electrochemical Corrosion: Wet or Electrochemical Corrosion occurs when a liquid medium is involved. One part behaves like an anode and undergoes oxidation and other part behaves like a cathode and undergoes reduction. The liquid medium

Relative area of anode and cathode: Corrosion also depends upon the area of the anode and cathode. Smaller the anodic area more is the rate of corrosion because oxidation of anode occurs at faster rate.

2. Nature of corroding environment:

i. Temperature: Corrosion depends on the temperature of the environment. The rate of corrosion increases with increase in temperature. ii. Moisture: Corrosion depends on the amount of moisture present in the environment The rate of corrosion increases with increase in the moisture or humidity iii. pH Value: Corrosion depends on the pH value of the surrounding environment. Lesser the pH (i.e. in acidic conditions), more is the corrosion. iv. Nature of electrolyte: Presence of salts in the electrolyte increases the corrosion rate.

v. Presence of impurities in atmosphere: Impurities increase the rate of corrosion. Corrosion is more around industrial areas and sea. This is because of presence of gases in the atmosphere like CO2, H2S, SO2

Control of corrosion

Why control