Chem

1. CORROSION CONTROL
METHODS, CAUSES AND
EFFECTS OF CORROSION
P. SAI CHARAN GOUD
R. SANDEEP GOUD
U. ASISH VARMA

2. WHAT IS CORROSION?
Corrosion is the gradual deterioration of a material, usually a metal, due to chemical or
electrochemical reactions with its environment. It often results in the loss of structural integrity and
can lead to the failure of the material or the system it's a part of. Corrosion can be caused by a variety
of factors, including exposure to moisture, air, salt, acids, and other chemicals. It can occur in various
forms, such as uniform corrosion, pitting corrosion, galvanic corrosion, crevice corrosion, and stress
corrosion cracking. Corrosion prevention techniques include the use of protective coatings, sacrificial
anodes, cathodic protection, and proper material selection. Regular inspection and maintenance are
also important to detect and prevent corrosion before it causes significant damage.

3. CORROSION CONTROL METHODS:
. Protective coatings
. Cathodic protection
. Regular inspection and maintenance
. Galvanizing

4. PROTECTIVE COATINGS: Applying a protective layer, such as paint
or a coating, can prevent the metal from coming into contact with the
environment and reduce the risk of corrosion.
CATHODICPROTECTION:This method involves applying a direct
electrical current to the metal, which can help to prevent corrosion. Cathodic
protection can be achieved through sacrificialanodes, impressed current
systems, or a combination of both.

5. REGULAR INSPECTIONAND MAINTENANCE: Regular
inspection and maintenance can help to detect and prevent corrosion before it
causes significant damage. This can include cleaning the surface of the metal,
repairing damaged coatings, and replacing corroded components.
GALVANIZING: This method involves coating the metal with a
layer of zinc, which can protect the metal from corrosion. Zinc is more
reactive than the metal it is protecting, so it corrodes in preference to
the underlying metal.

6. NOTE:
It's important to note that different corrosion control methods may be
more or less effective depending on the specific circumstances and the
type of corrosion that is occurring. A combination of methods may be
necessary to effectively prevent or control corrosion.

7. CAUSES OF CORROSION:
Metal corrodes when it reacts with another substance such as oxygen, hydrogen, an
electricalcurrent or evendirtand bacteria. Corrosion can also happen when metals like
steel are placed under too much stress causing the material to crack.
CORROSIONCAN BE CAUSED BYA VARIETY OF FACTORS,
INCLUDING:
Exposure to moisture: Moisture, especially in the form of water, is one of
the primary causes of corrosion. When metals are exposed to water or high humidity,
they can begin to corrode.
Exposure to air: Oxygen in the air can react with the metal and cause
corrosion, especially in the presence of moisture.

8. Exposure to salt: Salt, such as in seawater or road salt, can be particularly
corrosive to metals.
Exposure to acids and other chemicals: Acids and other chemicals
can react with the metal and cause corrosion.
Galvanic reactions: when two dis-
Similar metals are in contact, an electrochemical
reaction can occur that leads to corrosion of one
of the metals.

9. FACTORS AFFECTING CORROSION:
 Nature of Metal:
• Purityof metal.
• over voltage.
• Positionof metalin Galvanicseries.
• Nature of surfacefilm.
• grain size.
• Relativeareasof Cathodic& anodicparts.
 Nature of Corroding Environment:
• Temperature &Humidity .
• Effectof pH.
• Amountof 02inatmosphere .

10. NOTE:
Overall, the negative effects of corrosion can be significant and costly.
Implementing effective corrosion control methods can help to prevent
or minimize these effects and extend the lifespan of metal components.

11. TYPES OFCORROSION:
 Dry or Chemical Corrosion
Wet or Electrochemical
Corrosion

12. CHEMICAL ( OR DRY ) CORROSION:
Chemical corrosion is a type of corrosion that is caused by chemical reactions
between a metal and its environment. This can occur when the metal is exposed to
acids, bases, salts, or other chemicals. Chemical corrosion can take several different
forms, including uniform corrosion, pitting corrosion, and intergranular corrosion .
The chemical reactions that cause corrosion typically involve the transfer of electrons
between the metal and the environment, leading to the formation of metal ions and the
release of hydrogen gas. In some cases, the reaction can be accelerated by the presence
of catalysts or other factors.

13. ELECTROCHEMICAL ( OR WET ) CORROSION:
Electrochemical corrosion, also known as galvanic corrosion, is a type of corrosion that
occurs when two different metals are in contact with each other in the presence of an
electrolyte, such as saltwater or an acidic solution. The two metals form a galvanic cell,
with one metal acting as the anode and the other metal acting as the cathode .
The anode, which is the metal that is less noble, undergoes oxidation and corrodes,
while the cathode, which is the more noble metal, is protected. The corrosion can occur at
the interface between the two metals or at the surface of the anode.

14. PROTECTIVE MEASURES AGAINST CORROSION: