Effect of CeO₂ in Ni-Cr coating to increase the corrosion resistance of carbon steel Available to Purchase

The addition of reactive element such as CeO₂ in Ni-Cr coating was studied in order to improve the corrosion resistance of carbon steels. Two coating methods were applied to deposit Ni layer followed by Cr layer on carbon steel substrate using electroplating and pack cementation method, respectively. The amount of CeO₂ is 10 wt.% which is mixed in chromium pack cementation process. The corrosion resistance was tested by potentiodynamic polarization method using 3.5 wt.% NaCl and analyzed using tafel extrapolation technique. The microstructure observation showed that the surface of Ni-Cr coating with CeO₂ addition was more homogeneous and denser compared to coating without CeO₂ addition. This structure effected to the lowering corrosion rate of carbon steel substrate because cerium could accelerate the diffusion of Cr into Ni layer and improved the compactness of the Ni-Cr coating sample. The corrosion rate of coating samples with CeO₂ addition, without CeO₂ addition, and carbon steel substrate were measured to reach 0.079, 0.2, and 3.39 mpy, respectively.