Corrosion is a natural process that occurs when a refined metal reacts with its environment, causing it to deteriorate gradually. It is a common result of electrochemical reactions between materials and substances in their environment. Corrosion engineering is the field dedicated to controlling and preventing corrosion. The most common type of corrosion is electrochemical oxidation of metal in reaction with an oxidant such as oxygen, hydrogen, or hydroxide. Rusting, the formation of iron oxides, is a well-known example of electrochemical corrosion. Corrosion can also occur in materials other than metals, such as ceramics or polymers, although in this context, the term "degradation" is more common.
Corrosion can cause a variety of problems, including the degradation of useful properties of materials and structures such as mechanical strength, appearance, and permeability to liquids and gases. Corrosion is also a dangerous and extremely costly problem that can cause buildings and bridges to collapse, oil pipelines to break, chemical plants to leak, and bathrooms to flood. Corroded electrical contacts can cause fires and other problems, corroded medical implants may lead to blood poisoning, and air pollution has caused corrosion damage to works of art around the world. Corrosion threatens the safe disposal of radioactive waste that must be stored in containers for tens of thousands of years.
The science of corrosion prevention and control is highly complex, and corrosion takes many different forms and is affected by numerous outside factors. Factors to be understood include the effects of environmental conditions such as soil resistivity, humidity, and exposure to saltwater on various types of materials, the type of product to be processed, handled, or transported, and the required lifetime of the structure or component. Once the forms of corrosion have been identified, it is time to look at corrosion prevention and mitigation strategies.
