Inhibiting Effect of Mg-Rich Coating on Pitting Corrosion of LY12 Aluminum Alloy

Mg-rich coating and epoxy coating were painted respectively on the surface of LY12 aluminum alloy with pits prepared through potentiodynamic polarization. The effect of Mg-rich coating on pitting corrosion of aluminum alloy substrate was studied with electrochemical impedance spectroscopy (EIS). Results show that the Mg-rich coating could make the open circuit potential of aluminum alloy move negatively and maintained it stable for an extended period, showing good cathodic protection for aluminum alloy. The time for corrosion of the Al substrate was significantly prolonged. On the Al substrate with pits the dissolution rate of Mg particles in the coating increased, which would protect the substrate more effectively. The pits on the substrate surface showed no obvious changes for the Mg-rich coated sample, indicating that the Mg-rich coating could inhibit the generation and development of pitting corrosion on the aluminum alloy to some extent.