Recent Natural Corrosion Inhibitors for Mild Steel: An Overview

Table 1

Types of corrosion.

Type of corrosion	Description
Uniform corrosion	Deteriorates the whole surface of the metal and makes the surface thin.
Galvanic corrosion	Occurs with an electrolyte with metals having different values of electrical potentials.
Pitting corrosion	Occurs because of random attacks on particular parts of the metal’s surface to form pits. The pit acts as the anode, while the undamaged part of the metal is the cathode.
Stress corrosion cracking	A complex form of corrosion which arises due to stress and corrosive environment.
Corrosion fatigue	A combination of cyclic stress and corrosion.
Intergranular corrosion	Corrosion occurs on or near the grain boundaries of a metal.
Crevice corrosion	Concentration cell corrosion due to the trapping of corrosive liquid between the gaps of the metal.
Filiform corrosion	Concentration cell corrosion on metallic surfaces coated with a thin organic film.
Erosion corrosion	Flow-assisted corrosion which is due to the movement of corrosive liquids on metal surface.
Fretting corrosion	A form of erosion-corrosion which shows the combined effect of corrosion and fretting of metal.