Critical aspects in the electrochemical study of unstable coated metallic substrates

The measurements under current control enable to avoid sample damage due to system polarization that might occur when the open circuit potential significantly changes during the measurement. Moreover, the current control approach guarantees the stability of the system during the impedance measurement. However, measurements under current control carried out using the equipment and the software available in our laboratory have some drawbacks. The frequency range available for the measurements is reduced for data acquisition under current control. In addition, the output signal/noise ratio can be altered for measurements at high frequency. Moreover, input parameters must be carefully selected depending on the system investigated for measurements under current control. Nevertheless, impedance measurements under current control might be very useful for the study of unstable systems.