Corrosion
• Introduction
1. Corrosion is a general term used to describe various interactions between a material and it’s environment
leading to a degradation in the material properties.
2. Interaction with ambient oxygen can cause the formation of oxide layers via diffusion controlled growth.
These may passivate the material against further oxidation
3. In a wet environment, aqueous corrosion can occur due to electrochemical processes which depend upon
metal ion transport and reaction. Gradients of metallic and electrolytic ion concentrations, temperature,
ambient pressure, and the presence of other metals bacteria, or active cells, all influence the corrosion
rate.
4. Electric fields applied to corroding systems can accelerate or inhibit the rate of corrosion or material
deposition. Galvanic corrosion between different metals in am aqueous environment is due to the electric
field arising from the different electrode potential of the two materials. External fields may enhance or
supress this corrosion.
5. In all of these reactions, electrons and ionic transport occurs. The following sections will be concerned
with these processes and the effort of conditions on the corrosion rates.

Corrosion
CERTIFICATE
This is to certify that “ SYEDA NURIN HAQUE “ Student of class 10 has
successfully completed her Chemistry Project on “CORROSION “ Under the
guidance of teacher “MAINUL HAQUE”
Guardian‘s signature: Syed Amanul
Haque

Corrosion
• Methods of prevention for corrosion
• 1. Passivation :
• In passivation a light coat of a protective material, such as
metal oxide, creates a protective layer over the metal
which acts as a barrier against corrosion.
• The formation of a passivation layer is affected by
environmental pH , temperature, and chemical conditions.

Corrosion
• 2. Anodic Protection:
• Anodic protection involves in coating the iron alloy
steel with less a active metal, such as tin.
• Anodic protection is often applied to carbon steel
storage tanks used to store sulfuric acid and 50%
caustic soda.

Corrosion
• Definition:
• Chemical or electrochemical Process in which a solid, usually a metal, is attacked by
an environmental agent, resulting in portial or complete dissolution

Corrosion
• Fundam Basis of Corrosion :
• Corrosion occurs because most commonly used metal and alloys not in Locioest
energy state.
• Aluminium is extracted from Aluminium oxide and copper from copper sulphate

Corrosion
• Classification of corrosion:
• 1. Chemical corrosion
• 2. Electrochemical corrosion

Corrosion
• Chemical Corrosion:
• Chemical corrosion is the direct combination of metallic and non-metallic elements
to yield a chemical compound through oxidation reactions
• It can also be a corrosion product of dental gold alloys that contains silver.

Corrosion Formation