Dissemination of IT for the Promotion of Materials Science (DoITPoMS)

DoITPoMS Teaching & Learning Packages The Nernst Equation and Pourbaix Diagrams Examples of a Pourbaix Diagram
The Nernst Equation and Pourbaix Diagrams AimsBefore you startIntroductionBackgroundThe Nernst equationConstruction of a Pourbaix DiagramAnatomy of a Pourbaix DiagramExamples of a Pourbaix DiagramConstructing a 3D Pourbaix DiagramSummaryQuestionsGoing further
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Examples of a Pourbaix Diagram

Pourbaix diagrams for gold, zinc and aluminium

Gold’s Pourbaix diagram explains why it is the most immune substance known. It is immune in all regions in which cathodic reactions can take place. So gold never* corrodes in an aqueous environment.

Immunity of aluminium only occurs at lower potentials. Therefore, unless under conditions that cause it to passivate, it is much more susceptible to corrosion than gold or zinc.

* provided that the water is pure; that no ion complexes are present to provide a cathodic half cell reaction that occurs at a potential higher than +1.5 V(SHE).

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