Abstract: Room temperature corrosion behavior of cast aluminum-silicon alloy in engine coolant containing proprietary inhibitors in the presence of varying chloride concentrations was investigated. Potentiodynamic polarization curves with chloride contaminated inhibited coolant solutions showed an increase in anodic kinetics with chloride additions from 1000 ppm. A large passive range (with no breakdown till ~ 1 V vs open circuit potential) was observed for chloride concentrations up to 500 ppm suggesting effective inhibition. The pitting potential decreased with an increased in chloride concentration from 1000 ppm to 2000 ppm. Potentiostatic studies at 0.0V vs Ag/AgCl also showed that 1000 ppm is the threshold limit for chloride contamination with an order of magnitude increase in current after three hours of exposure. SEM analysis on the potentiostatic coupons tested in 2000 ppm chloride showed localized pitting and trenching around the silicon particles and intermetallics.
Authors: Anusha Chilukuri, Gaurav Argade, Justin Perry, Corey Trobaugh, Randy Schafer, Erica Raisor, Jacob Steenhoek, and Glenia Pena Lugo
Keywords: Cast aluminum; Potentiodynamic polarization; Corrosion inhibition; Electrochemical impedance spectroscopy