Question

Define corrosion. List the factors affecting rate of corrosion.

Answer 1

Corrosion.

Definition -

 Corrosion is the gradual deterioration or destruction of materials (usually metals and alloys) by chemical or electrochemical reactions with its environment.

 Corrosion is defined as the gradual deterioration or destruction of a metal by chemical or electrochemical reactions with its environment.

 Any process of deterioration and consequent loss of a solid metallic material through undesired chemical or electrochemical attack by its environment starting at the surface.

Factors affecting rate of corrosion –

The factors affecting rate of corrosion are :

A) Nature of the material (metal dependent factors) -

1) Position of the metal in the electrochemical or galvanic series

2) Purity of the metal

3) Surface of the metal

4) Relative area of cathodic and anodic part ( anodeto cathode area ratio)

5) Nature of the oxide film

6) Solubility of the corrosion product

7) Physical state of the metal

8) Volatility of the corrosion product

B) Nature of the environment (environment dependent factors) –

1) Temperature of the environment

2) pH of the environment

3) Humidity of the environment/presence of the moisture in the environment

4) Presence of impurities in the environment

5) Amount of oxygen in the environment

6) Nature of anions and cations present in the environment

7) Presence of suspended particles in the environment