Electrochemical Characteristics of Mechanically Treated Metallic Surfaces

Abstract

The paper presents the results of research aimed at determining the corrosive properties of steel surfaces after mechanical treatment by grinding and blasting. The aim of the study was to determine the changes in the electrochemical characteristics of the material during exposure in the 1 M NaCl solution in distilled water, and establish the optimal time of application the coatings on pre-treated surface without reducing the adhesion. With help of potentiodynamic tests and electrochemical impedance spectroscopy there were determined polarization resistance (Rp), the anodic and cathodic Tafel plots, corrosion current (Icorr)​​, corrosion rate (rcorr) and corrosion potential (Ecorr). The results pointed to the fact that after the mechanical treatment by grinding and blasting with aluminum oxide and steel shot the highest surface activity was found within 1 hour since the pretreatment. After this time, the activity decreases and corrosion products appear causing a reduction in adhesion of subsequently applied coatings. After blasting with cut wire the reduction of the adhesion appear not before 8 hours after blasting because of the different shape of the resulting surface. Potentiodynamic test proved that the highest corrosion rate showed a ground surface. Lower corrosion rate reached blasted surfaces depending on the type of abrasive used, which is closely related to the kinetic energy of the impacting grains and the actual surface area.