CorroZone Podcast · 16 Jun 2026
Current-Potential Diagrams
- Free
- Lecture
- Beginner
- ~23 min
The kinetics of a single electrode reaction: reading the anodic and cathodic branches of a polarisation curve, the Butler–Volmer equation, exchange current density and transfer coefficients, extracting Tafel slope and exchange current density from a Tafel plot, and where concentration polarisation and passivation break Tafel behaviour.
Show notes
What you'll learn
- Sketch and interpret a current-potential (polarisation) curve for a single electrochemical reaction, identifying the anodic and cathodic branches and the equilibrium potential
- State and apply the Butler-Volmer equation, explaining the physical meaning of exchange current density and transfer coefficients
- Apply the Tafel approximation to the high-overpotential regime and extract Tafel slope and exchange current density graphically from a Tafel plot
- Explain the physical significance of the Tafel slope and how it relates to the transfer coefficient and the activation energy barrier
- Define exchange current density and explain its role in determining the kinetic facility of an electrochemical reaction
- Describe how concentration polarisation and passivation cause deviations from Tafel behaviour, and identify these features on a polarisation curve
Who this is for
Anyone beginning their study of corrosion — students, engineers, and technical staff who want a solid foundation in why metals corrode and what can be done about it. No prior background assumed.
What you'll learn
- Sketch and interpret a current-potential (polarisation) curve for a single electrochemical reaction, identifying the anodic and cathodic branches and the equilibrium potential
- State and apply the Butler-Volmer equation, explaining the physical meaning of exchange current density and transfer coefficients
- Apply the Tafel approximation to the high-overpotential regime and extract Tafel slope and exchange current density graphically from a Tafel plot
- Explain the physical significance of the Tafel slope and how it relates to the transfer coefficient and the activation energy barrier
- Define exchange current density and explain its role in determining the kinetic facility of an electrochemical reaction
- Describe how concentration polarisation and passivation cause deviations from Tafel behaviour, and identify these features on a polarisation curve