Corrosion fundamentals: Thermodynamics, rate, passivity, types, and control mechanism

ABSTRACT Corrosion is a spontaneous type of materials’ destruction due to its interaction with the environment, which causes devastating failures and substantial damage. In certain environmental situations, some metals and metal alloys become inert and lose their reactivity owing to their passivity, which could be the main reason for their extensive utilization in industrial settings. However, in certain situations, the passive film, which is the corrosion attack defensive barrier, may break down, leading to corrosion. Therefore, the aim of this review was to provide detailed fundamental concepts on metals and their alloys corrosion. When dealing with corrosion, thermodynamics and kinetics play a key role in determining corrosion behavior based on the fundamental concept of electrochemistry and metallurgical understanding. In a given environment, thermodynamics predict the likelihood of metals to corrosion risk (when a metal will corrode), whereas the kinetics indicate corrosion rate, or how quickly the metal will erode. Since corrosion processes are mostly electrochemical, they are roughly classified into various forms, viz., uniform, pitting, crevice, intergranular, galvanic, stress corrosion cracking, erosion, and fretting/wear corrosion. The nature of the metal (such as its purity, physical state, position in galvanic and electrochemical series, and oxide film nature) and the corroding environment (temperature, humidity, moisture and dew, and atmospheric pollutants) are the main factors inducing corrosion. However, surface coating of metals, cathodic protection, changing the corrosive environment, using pure metal and alloys, and design changes can inhibit the corrosion processes. Moreover, future directions for corrosion prevention will require the implementation of new technologies that rely on advanced monitoring techniques and a commitment to sustainability. Some strategies to prevent and/or minimize corrosion phenomena include the use of nanomaterials, smart coatings, electrochemical processes, and data analytics. This review, in general, offers a solid foundation for further research on specific corrosion type characteristics.