Definition - What does Evans Diagram mean?
An Evans diagram is a pictorial that depict the graphical representation between an electrode’s kinetic data (or current densities) and thermodynamics (or potential) in a corrosive process. An Evans diagram is also known as a mixed potential plot, where the mixed potential is the effective potential of a metallic surface in contact with an electrolyte that is driving electrochemical corrosion. Mixed potential theory explains metal corrosion as a reaction of two or more electrodes working simultaneously at the interface of the metal's surface and an electrolyte.
An Evans diagram is useful for understanding and determining the corrosion process.
An Evans diagrams may also be known as a polarization diagram, mixed potential diagram or mixed potential plot.
Corrosionpedia explains Evans Diagram
Two partial reactions occur when a metal object corrodes: oxidation and reduction. A basic premise in any corrosion reaction is that it will only occur when the total rate of oxidation becomes equal to the total rate of reduction. This means that the sum of anodic oxidation currents must equal the sum of cathodic reduction currents.