Corrosion may be defined as the deterioration of a material resulting from chemical attack by its environment. Most corrosion of materials involves the chemical attack of metals by electrochemical cells. By studying equilibrium conditions, the tendencies of pure metal to
corrode in a standard aqueous environment can be related to the standard electrode potentials of the metals. However, since corroding systems are not at equilibrium, the kinetics
of corrosion reactions must also be studied. Some examples of kinetic factors affecting
corrosion reaction rates are the polarization of the corrosion reactions and the formation
of passive films on the metals.
There are many types of corrosion. Some of the important types discussed are uniform or general attack corrosion, galvanic or two-metal corrosion, pitting corrosion, crevice corrosion, intergranular corrosion, stress corrosion, erosion corrosion, cavitation damage, fretting corrosion, selective leaching or dealloying, and hydrogen embrittlement.
The oxidation of metals and alloys is also important for some engineering designs such as gas turbines, rocket engines, and high-temperature petrochemical installations. The study of the rates of oxidation of metals for some applications is very important. At high temperatures, care must be taken to avoid catastrophic oxidation.
Corrosion can be controlled or prevented by many different methods. To avoid corrosion,
materials that are corrosion-resistant for a particular environment should be used where feasible. For many cases corrosion can be prevented by the use of metallic, inorganic, or organic coatings. The proper engineering design of equipment can also be very important for many situations. For some special cases, corrosion can be controlled by using cathodic or anodic protection systems.
