Abstract
When a macrocell is formed in a corrosion process, an electrical field is established in the environment because a net current flows from the anode to the cathode , which are physically separated. This situation occurs in galvanic corrosion , differential aeration , localized attacks such as pitting and crevice, and cathodic protection. Potential and current distributions are extremely important because they determine the corrosion rate . Analytical solutions of electric fields exist only for very simple geometry and simplified conditions. In the last two decades, the use of numerical calculations based on Finite Element Methods (FEM ) has overcome these difficulties. This Chapter gives an overview of macrocell electrical field and current distribution, giving analytical solutions for both quantities in simple geometries, such as inside and outside a pipe. In some of these geometries the throwing power is also evaluated.
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Notes
- 1.
Examples of field problems are: heat transmission (E = temperature, Q = heat, κ = transport coefficient), mass transport (E = pressure, Q = mass, κ = transport coefficient) and the transportation of current as in the case of cathodic protection , where E is electric potential , Q is electrical charge and κ is conductivity .
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Pedeferri (Deceased), P. (2018). Macrocell Corrosion Mechanism. In: Corrosion Science and Engineering. Engineering Materials. Springer, Cham. https://doi.org/10.1007/978-3-319-97625-9_9
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DOI: https://doi.org/10.1007/978-3-319-97625-9_9
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