A novel methodology for monitoring low-temperature corrosion caused by hygroscopic salts using linear polarization resistance

A new methodology for monitoring low-temperature corrosion caused by hygroscopic salts was developed and tested with ZnCl₂. First, deliquescence and efflorescence points of ZnCl₂ were determined by electrochemical impedance spectroscopy and chronoamperometry measurements in the range of 10–35 vol % H₂O. Then, low-temperature corrosion was monitored using a probe that combines linear polarization resistance and mass loss measurements. Suitable potential and scan rate for the linear polarization resistance measurements were experimentally determined. The feasibility of the probe was tested by monitoring the corrosiveness of ZnCl₂ on P235GH steel under different temperatures (100–180 °C) and water vapor concentrations (15–35 vol %). With the developed corrosion probe, corrosion caused by hygroscopic salts during changes in testing conditions can be monitored and evaluated.