Half-Cell Potential

Definition - What does Half-Cell Potential mean?

Half-cell potential refers to the potential developed at the electrode of each half cell in an electrochemical cell. In an electrochemical cell, the overall potential is the total potential calculated from the potentials of two half cells. The measurement of half-cell potential is used to evaluate:

  • Presence of corrosion
  • Potential vulnerability of element surface area to corrosion

The half-cell potential measurement can only indicate the corrosion probability at a given location and time, but long-term monitoring of the half-cell potential reading is necessary to correctly assess and predict the corrosion severity.

Corrosionpedia explains Half-Cell Potential

The half-cell potential is the potential developed at the electrode of a half cell due to the process of oxidation or reduction. This potential is used to indicate corrosion activity, and measures the tendency of one reaction, like oxidation, to proceed at its one half-cell electrode and similarly measures the corresponding tendency for reduction to proceed at the other half-cell electrode.

Each half-cell potential is associated with an electrode-solution potential difference. The potential magnitude depends on the nature of the specific electrode reaction and on the concentrations of the dissolved solution. The sign of this potential difference depends on the direction (oxidation or reduction) in which the electrode reaction proceeds.

A half-cell potential measurement is a non-destructive method to assess the corrosion risk of steels in concrete. This method is cheaper and can be easily used. In reinforcing concrete, an electrode forms one half of the cell and the reinforcing steels in the concrete form the other half cell. The behavior of steel in concrete can be characterized by measuring its half-cell potential. The chances of corrosion occurring on the steel in concrete and half-cell potential are directly proportional; the higher the potential, the higher the risk of corrosion occurrence.

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