An Electrochemical Study of Ferrous and Nonferrous Materials in an Engine Coolant Environment

A study was conducted to identify the threshold concentrations of chloride contaminant in an inhibited engine coolant on three different metallic substrates-cast iron, cast aluminum, and brass. All three metallic systems showed a reduction in the breakdown potentials during potentiodynamic polarization carried out with increasing chloride concentrations from 0 to 1000 ppm. Higher anodic current densities and lower breakdown potentials were observed for cast aluminum at 1000 ppm chloride concentration compared to the other twometals. However, intermittent electrochemical testing of the immersion tested cast aluminum and cast iron samples at 90 degrees C in inhibited coolants containing up to 1000 ppm Cl additions showed increased corrosion resistance of cast aluminum (similar to 1.5 orders of magnitude lower corrosion currents and anodic currents) compared to cast iron.