In situ corrosion monitoring by electrochemical techniques: assessment of experimental procedures

Electrochemical techniques, well established in industrial field, have been successfully adapted with promising results as Non-destructive Techniques (NdT) for the diagnostic of metallic cultural heritage only from the second half of the 90s. For a better exploitation of the analytical results, there is still the need for further systematic studies in order to fully understand the influence of the different parameters of the experimental setup on the recorded data. A series of tests was performed on bronze artefacts to evaluate the impact of different experimental procedures on electrochemical measurements such as Liner Polarization Resistance (LPR) and Electrochemical Impedance Spectroscopy (EIS). Based on the ContactProbe setup, several variables were considered, such as the electrolyte, the type of sponge/cloth to be used to keep the electrolyte on the artwork surface, the stabilization time before measurements, the sampling rate for EIS spectra and the equipment. Particular attention was given to all the parameters affecting the duration of measurement with the scope of optimising both the time required for each acquisition and its quality (reproducibility and reliability).