Effective electrode preparation to prevent crevice in steel electrodes

M.A. FRONTINI; VAZQUEZ M.; M. B. VALCARCE

Mar del Plata

Congreso; 34th Topical Meeting of the International Society of Electrochemistry.; 2023

International Society of Electrochemistry

Crevice corrosion is hard to avoid when the corrosion resistance of steel electrodes needs to be evaluated, particularly when chloride ions are present in the electrolyte. For instance, this problem is recurrent when studying the performance of construction steel in concrete pore simulating solutions that aim to replicate a marine exposure. Other applications such a steel buried in saline soils or steel in industrial atmospheres face the same problem.Steel electrodes were mounted by cutting disks from construction steel bars (Mn 0.635 wt%, C 0.299 wt%, Si 0.258 wt%, Cu 0.227 wt% and other impurities 0.245 wt%) and embedding them in epoxy resin using polyvinyl chloride (PVC) tubes. The geometrical area exposed was 0.5 cm2 and the electrodes’ surface was abraded with emery paper down to grade 1000. More experimental details can be found in previous publications [1-3].This study describes how a pre-treatment, where the electrode is passivated at open circuit potential (OCP) for 24 hours in an alkaline solution, effectively helps to minimize the risk of electrodes showing crevice after an electrochemical evaluation in the anodic potential range. It will also be shown how the quality of electrode preparation can be evaluated by simply registering a cyclic voltammogram in NaOH pH 13 (see Figure 1). Polarization curves and electrochemical impedance spectra on electrodes with and without the pre-treatment will be presented to demonstrate the effectiveness of the treatment.