Department of Chemistry, KUET

1. WELCOME
To my presentation

2. Presentation On
Various factors that influencing the rate of Corrosion.

3. Presented By
Ariful Islam
Roll No: 2053506
Presented To
Dr. A.B.M. Mamun Jamal
Department of Chemistry
Khulna University of Engineering & Technology
Khulna-9203,Bangladesh

4.  Nature of Metal
 Surface State of the Metal
 Nature of the Corrosion Product
Primary factors related to metal:

5. Nature of Metal
The tendency of a metal to undergo
corrosion is dependent on the nature of the
metal.
Metals with lower reduction potential
undergo corrosion easily where as metals
with higher reduction potential do not
undergo corrosion easily .

6. Surface state of the
metal
Corrosion is a surface
phenomenon ,larger the surface
area or finer the grain size of the
metal,more will be the
corrosion. smooth surface resist
corrosion than the rough
surface.

7. Nature of corrosion products
If the corrosion product is
insoluble, stable, uniform, and
nonporous, it acts as a
protective film preventing the
further corrosion. If the
corrosion product formed is
soluble, unstable porous and
non-uniform the corrosion
continues.

8. Secondary factors related to
environment
pH of the medium
Temperature
Presence of oxidizing agents
Humidity
Area effect

9. pH of the medium
In general, lower the pH higher is the
rate of corrosion.
If the pH is greater than 10, corrosion
of iron is very less due to the formation
of protective coating of hydrous oxide
of iron.
If the pH is between 10 and 3, then
presence of oxygen is essential for
corrosion of iron.

10. Temperature
As temperature increases, rate of
corrosion also increases.
This is because increase in temperature
increases the conductance of the
aqueous medium.
As a result rate of diffusion also
increases.

11. Presence of oxidizing agents
The presence of oxidizing agents increases the corrosion rate of
the metal.
Some of the best oxidizing agents include:
• Oxygen
• Hydrogen peroxide
• Sulfuric acid
• Nitrous oxide
• Potassium nitrate
Even noble metals undergo corrosion in the presence of
oxidizing agents.
•Sulfuric acid
•Nitrous oxide
•Peroxydisulfuric acid
•Potassium nitrate
•Hydrogen peroxide
•Sulfuric acid
•Nitrous oxide
•Peroxydisulfuric acid
•Potassium nitrate

12. Humidit
y
Most of the metals corrode faster in a humid atmosphere than in dry air.
There is a particular value of humidity called critical humidity above which
corrosion rate is steeply increases.
VS

13. Area effect
Smaller the anodic area, larger
the cathodic area, faster will be
the rate of corrosion and
conversely, larger the anodic
area, slower will be the rate of
corrosion.

14. Any Queries
?

15. …….Thanks to all…..