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 (icorr) 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 icorr 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.