E Log I Fit

Description

The E Log I Fit is a classical Tafel analysis done using only one side only using one side (anodic or cathodic) of the log(I)-versus-E curve. It assumes that at least one of your corrosion reactions is under kinetic control. See the Basics of Corrosion Measurements if you’re not familiar with Tafel analysis and the mathematics describing kinetically-controlled corrosion reactions. To use the E Log I Fit calculation, you select a region on one side of Ecorr where the log(I) plot appears to be linear (the linear anodic or linear cathodic curve). The E Log I Fit command then performs a linear least-squares fit of log(I) versus potential in the selected region. The slope of the line is the β coefficient for the half-reaction under study. The current at which the fitted line goes through Ecorr is Icorr. In order to use this command, a region on either side of Ecorr must be specified on the Active trace.

Method

1. Make the trace on which to perform the fit the Active Trace. Do this by right-clicking on the trace and clicking Activate Trace.
2. Select a region on this trace using the mouse curve-selection tool .
3. After you select a region, choose the E Log I Fit command in the Experiment Specific menu. A dialog box presenting the Ecorr value appears. You may change this value, or you may leave it alone.
4. Once you are satisfied with the Ecorr value, click the Calculate button. The algorithm now fits a line to the selected region. When the fit is complete, a new trace is added to the chart.
5. View the results for the fit by moving the mouse cursor over the fit and watching the tool-tip. The results are also presented on their own tab with the caption E Log I.