Corrosion: Definition and Types

Study Notes

Corrosion: a naturally occurring process that involves the deterioration of materials, usually metals, due to chemical reactions with their environment.
Types of corrosion:
- Uniform corrosion: even deterioration of the material surface.
- Pitting corrosion: localized damage in the form of small holes or pits.
- Crevice corrosion: corrosion that occurs in small, confined spaces.
- Galvanic corrosion: corrosion that occurs when two dissimilar metals are in contact.
- Intergranular corrosion: corrosion that occurs along the grain boundaries of a metal.

Environmental factors:
- Humidity
- Temperature
- Presence of corrosive substances (e.g., acid, saltwater)
Material factors:
- Type of material (e.g., iron, copper, aluminum)
- Surface finish and cleanliness
- Presence of impurities or defects
Other factors:
- Oxygen availability
- Presence of microorganisms (e.g., bacteria, fungi)

Coatings and linings:
- Paints and varnishes
- Metallic coatings (e.g., zinc, tin)
- Ceramic and polymeric coatings
Cathodic protection:
- Applying an electric current to drive the corrosion reaction in the opposite direction
Inhibitors:
- Adding substances to the environment to slow down or stop corrosion
Design and maintenance:
- Designing structures and equipment to minimize corrosion risks
- Regular cleaning, inspection, and maintenance

Laboratory tests:
- Immersion tests
- Salt spray tests
- Humidity tests
Field tests:
- Exposure tests
- Coupon tests
Monitoring techniques:
- Visual inspection
- Electrochemical measurements
- Acoustic emission testing

Corrosion is a natural process that involves the deterioration of materials, usually metals, due to chemical reactions with their environment.
Types of corrosion include:
- Uniform corrosion, which is an even deterioration of the material surface.
- Pitting corrosion, which is localized damage in the form of small holes or pits.
- Crevice corrosion, which occurs in small, confined spaces.
- Galvanic corrosion, which occurs when two dissimilar metals are in contact.
- Intergranular corrosion, which occurs along the grain boundaries of a metal.

Environmental factors that affect corrosion include:
- Humidity
- Temperature
- Presence of corrosive substances (e.g., acid, saltwater)
Material factors that affect corrosion include:
- Type of material (e.g., iron, copper, aluminum)
- Surface finish and cleanliness
- Presence of impurities or defects
Other factors that affect corrosion include:
- Oxygen availability
- Presence of microorganisms (e.g., bacteria, fungi)

Coatings and linings can prevent corrosion, including:
- Paints and varnishes
- Metallic coatings (e.g., zinc, tin)
- Ceramic and polymeric coatings
Cathodic protection involves applying an electric current to drive the corrosion reaction in the opposite direction.
Inhibitors can be added to the environment to slow down or stop corrosion.
Design and maintenance practices can also prevent corrosion, including:
- Designing structures and equipment to minimize corrosion risks
- Regular cleaning, inspection, and maintenance

Laboratory tests for corrosion include:
- Immersion tests
- Salt spray tests
- Humidity tests
Field tests for corrosion include:
- Exposure tests
- Coupon tests
Monitoring techniques for corrosion include:
- Visual inspection
- Electrochemical measurements
- Acoustic emission testing