Galvanic corrosion ohmic potential drop

The passage of current through an ionic electrolyte of finite resistivity results in an ohmic potential drop along the current path according to Ohm s law. There are two aspects of corrosion that are influenced by ohmic potential drops measured polarization curves and any form of corrosion in which the anodic and cathodic reactions are separated spatially, such as in galvanic corrosion. 

Ohmic potential drops also play a role in galvanic corrosion and other forms of localized corrosion, in which the anodes and cathodes are spatially separated. Ionic current must then flow some distance through the electrolyte. Two galvanically coupled electrodes will not reach the exact same potential as a result of the ohmic potential drop that will occur along the current path through the electrolyte. 

Figure 7.9 Simplified illustration of how an ohmic potential drop in the electrolyte between the metals reduces die rate of galvanic corrosion.

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