ABSTRACT
Electrode Technique ................................................................................................. 459 14.2.6 Local Electrochemical Impedance Spectroscopy and Mapping .............................. 461
14.3 Applications of Scanning Electrochemical Probe Techniques in Corrosion Research ........ 462 14.3.1 Applications of SECM .............................................................................................. 462
14.3.1.1 Early Work ................................................................................................. 462 14.3.1.2 Stainless Steel ............................................................................................463 14.3.1.3 Nonferrous Metals .....................................................................................465 14.3.1.4 Coated Metals ............................................................................................ 467
14.3.2 Applications of Potentiometric SECM ..................................................................... 472 14.3.2.1 pH Mapping ............................................................................................... 472 14.3.2.2 Mapping of Other Ions ............................................................................... 475
14.3.3 Applications of Electrochemical Microcell and Scanning Capillary Microscopy ..... 479 14.3.3.1 Stationary Capillary Techniques ............................................................... 479 14.3.3.2 Scanning Capillary Techniques ................................................................. 479
14.3.4 Applications of SVET and LEIS/LEIM ...................................................................480 14.3.4.1 SVET..........................................................................................................480 14.3.4.2 LEIS/LEIM ................................................................................................ 482
14.4 Conclusions ........................................................................................................................... 482 Acknowledgments .......................................................................................................................... 483 References ...................................................................................................................................... 483
The corrosion of a pure metal or a metal alloy may be de–ned as the irreversible reaction of the metal with its environment, resulting in degradation of the metal and/or its properties. For environmental corrosion, the reactions are redox reactions involving the oxidation of one or more of the metals comprising the alloy, driven by reduction of one or more oxidants, such as hydrogen ion, dioxygen, and/or water. Such corrosion reactions have been called “extractive metallurgy in reverse” [1], reªecting the fact that considerable energy must be expended to extract and purify a metal such as Fe or Al from its ore (i.e., its oxide forms). Corrosion is the thermodynamically favored process by which the metal reverts to its oxide form(s). Since it is virtually impossible to completely stop such thermodynamically favorable processes, corrosion control strategies are designed to slow the corrosion rate by retarding the rate of metal oxidation, the rate of oxidant reduction, the rate of ion movement between sites of oxidation and reduction (such ion movement is required for maintaining overall charge balance), or some combination of these approaches.
