1. CORROSION
CONTROL

2. What is corrosion?
How corrosion occurs?
Corrosion is the gradual
destruction of material, In the presence of moisture,
an oxidation reaction takes place on
usually metals, by chemical
the energized area of the metal surface
reaction with its environment. to elute metal as an ion (anode).
A reduction takes place on low energy
area (cathode).

3. WHAT IS CORROSION
CONTROL?
• Protecting the surface of the metal so
that corrosion reaction don't take place at
surface is known as corrosion control.
• There are several methods to control
corrosion which are described below.

4. Corrosion control
Metallic Organic Electrochemical
coating coating Using alloys protection
Corrosion Using pure By modifying Proper
inhibitors metal environment designing
•Paint
•Enamel Inorganic •Sacrificial
•Electroplating •Varnish coating Anodic
•Metal cladding •lacquers protection
•Hot dipping •Impressed
•Cementation current cathodic
•Metal Spraying
protection

5. 1. Metallic coating
Metallic coatings provide a layer that changes the surface properties of
the work piece to those of the metal being applied.
• Electroplating
It is the process by whish a coating metal is deposited on the base
metal by passing a direct current through an electrolyte solution.
• Metal cladding
• The base metal to be protected and coating metal are sandwiched by
pressing through rollers under the action of heat and pressure.
• Hot dipping
The base metal to be coated is immersed in a bath of the molten
coating metal
• Cementation
In this process a uniform surface coating is obtained by heating the
base metal in a power of coating metal.
• Metal Spraying
The coating metal in molten state is sprayed on base metal by
means of spraying gun.

6. 2. Corrosion inhibitors
It is the substances which when added in a small amount in an
environment reduces the rate of corrosion of a metal exposed to that
environment. These are of two types anodic and cathodic.
3. Organic coating
These are applied on metallic surface for protection from
corrosion and also to impart decorative value. It includes :
• Paints
These are mechanical dispersion mixtures of finely divided solid called
pigments in a fluid medium.
• Enamel
It is a dispersion of pigments in a varnish.
• Varnishes
it is a colloidal solution of natural or synthetic resin in solvents like oil
or sprit.
• Lacquers
It is a colloidal dispersion of a solution of cellulose derivatives like
cellulose nitrates, resins and plasticizers in a solvent.

7. 4. Using pure metal
Pure metals are homogenous and corrosion resistance . The
greater the purity of metal more it will be corrosion resistant.
5. Using alloys
It is a homogenous mixture of two or more metals. The homogenous alloys
are more corrosion resistant then pure metals.
6. Inorganic coating
The in organic coatings are produced by chemical or electro
chemical reactions at a surface of metal. This coating provides
protection to the base metal from corrosion. Some inorganic coating
are chome,phospate,oxides etc.

8. 7. By modifying environment
• Lowering the temperature reduces the corrosion .
• The removal of moisture by the addition of adsorbents like alumina or
silica gel leads to decrease in corrosion.
• The acidic corroding environment can be neutralized by addition of
ammonia, lime or sodium hydroxide.
8. Proper designing
• Proper designing of the equipment plays a significant role in controlling the
corrosion.
• Proper designing can slow down or even avoid corrosion .
• Avoid the contact of dissimilar metals in the presence of corroding
environment

9. 9. Electrochemical protection
The Electrochemical protection or cathodic protection
evolves the supply of electrons to metal there by forcing the metal
behave as cathode and as the result metal is not corroded.
Cathodic protection can be achieved in two ways:
• Sacrificial Anodic protection
In this protection the metallic equipment to be protected is
connected to a more anodic metal so the metallic equipment acts as cathode.
As a result corrosion take place at anodic metal and cathodic metallic
equipment is saved from corrosion
• Impressed current cathodic protection
This process consist of connecting the material to be protected to
negative terminal of DC source. The positive terminal of DC source is
connected to a insoluble anode like graphite, carbon, scrap iron . The current
supplied is in opposite direction to the corrosion current. Thus the metal to be
protected act as cathode and get protected.

10. THANK YOU.......