Electrochemical Study of 1018 Steel Exposed to Different Soils from South of México

Abstract

ABSTRACTPhysicochemical effect on the corrosion process of AISI 1018 steel exposed to five type of soils from South of México at different moisture content using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves was studied. Two soils were collected in the state of Veracruz (clay of high plasticity and silt) and three soils from the state of Campeche (sand, clay and clay-silt). Moisture values were determined by addition of 0, 20, 40 and 60 ml of deionized water in a volume of 125 cm3of each soil. The corrosion behavior of uncoated and coated steel with a viscoelastic polymer was analyzed. Effect of damage on the coating when the steel is exposed to corrosive soils was studied. EIS evaluations indicate that 1018 steel without coating is more susceptible to corrosion in the clay at the maximum moisture content (39.7 wt. %). However, for sand the more corrosive moisture belong to 12.8 wt. %, which is not the maximum moisture, which is agree with the lower polarization resistance (52.21 Ω.cm2). Potentiodynamic polarization curves suggested that uncoated steel exposed to clay-silt from state of Campeche exhibited the higher corrosion rate (0.698 mm/year) at 53.1 wt. % moisture. Meanwhile, in the coated steel with induced damage, the higher corrosion rate was obtained in the clay (0.0018 mm/year) at 34.2 wt. % moisture. 1018 steel coated with induced damage exposed to clay displayed the higher Ecorrvalues, which means that clay is more susceptible to overprotection as consequence of any change in the voltages originated by moisture content.