Academic literature on the topic 'Corrosion galvanique'

Most metals used by our society corrode, from the mild tarnish on silver to the green patina that coats our copper statues and electrical wiring to the red rust on our cars and iron bridges (Fig. 12.1, Plate 17). Metal corrosion often involves the conversion of metals into either oxides or their soluble hydrolysis products. The metals we use in our structures, as well as in electronic and magnetic devices, are destroyed as a result of this conversion. It has been estimated that the annual cost of metallic corrosion to the U.S. economy is hundreds of billions of dollars (5% of the gross national product). Therefore, enormous efforts have been made to understand why metals corrode, and what can be done to inhibit corrosion processes. Stainless steel is just one example of humankind’s attempts to limit corrosion processes. Other examples include the use of inert paints on ships to prevent saline corrosion, coating iron with zinc to galvanize it, and exploiting electrochemical strategies, such as using sacrificial anodes that corrode instead of iron, as a means of protecting more important materials’ components. The number of comprehensive texts and reviews regarding metal corrosion scales with its economic impact, with more than 1000 articles being published on the topic per year. Those of you interested in more comprehensive discussions regarding how specific metals corrode in specific environments such as seawater and acid rain should see other works. Our focus in this chapter is to highlight how metal corrosion is mediated by the presence of oxides, with an emphasis on reactions that occur in water. This overview highlights the basic properties of oxide films that give rise to a wide range of complicated metal corrosion phenomena. The discussion draws on many concepts highlighted in other chapters of this book: surface chemistry (Chapter 6), electrochemistry (Chapter 11), and oxide dissolution (Chapter 16). Metal corrosion often involves electrochemical reactions in which the metal is oxidized by either water or O2.