Electrochemical corrosion behavior of the cobalt modified aluminide coating in 3.5 wt% NaCl solutions

In this paper, we achieved the Co modified aluminide coating on nickel base superalloys by pack cementation process. The corrosion currents (i_corr) of coated and uncoated substrate after 1?h of immersion tested by potentiodynamic polarization in 3.5?wt% NaCl solutions are 9.73b × 10^?7 A/cm² and 1.31 × 10^?6 A/cm², respectively. With the immersion time extension, the i_corr of the coating decreases and the values of |Z| by EIS increase, indicating that the electrochemical reaction rate of the coating becomes slower. The coating presents good corrosion resistance due to the Al₂O₃ formed on the surface.