Investigating the Use of Scanning Kelvin Probe (SKP) in Evaluating the Effectiveness of Ammonium-Based Corrosion Inhibitors to Control Steel Corrosion in the Sour Media

The scanning Kelvin probe (SKP) is a non-destructive and non-contact method for surface inspection, which is widely used in evaluating the performance of corrosion inhibitors, investigating the mechanism of inhibition, determining the optimal concentration, and evaluating the effectiveness of inhibitors in different environments. This method provides information about the electrochemical behavior of the surface based on the measurement of the contact potential difference (CPD) between the sample surface and the reference electrode. A more comprehensive understanding of the corrosion process can be achieved by using the SKP method and comparing its results with electrochemical measurements such as electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). In this research, the inhibition behavior of quaternary ammonium salts (QAS) against the corrosion of X65 carbon steel in the sour environment (H2S) at 60 °C was investigated using EIS and PDP tests, then the results were confirmed with the scanning Kelvin probe.