Effects of Ce4 + on the structure and corrosion resistance of electroless deposited Ni–Cu–P coating

In this paper, the effects of Ce4 + concentration on the structure and corrosion resistance of electroless deposited Ni–Cu–P coatings were investigated using microscopy, energy dispersive X-ray spectroscopy (EDX), inductively coupled plasma atomic emission spectrometry (ICP-AES), X-ray diffraction spectrometer (XRD), polarization curve (PC) and electrochemical impedance spectroscopy (EIS). The results show that the proper addition of Ce4 + can apparently refine the grain size and make the coating surface denser and more uniform, resulting in the enhancement of corrosion resistance of Ni–Cu–P coatings in the flue gas condensate. When the Ce4 + concentration is 8 mg/L, the corrosion current density of Ni–Cu–P coating was reduced by nearly 60% as compared to that prepared without Ce4 + in the bath. However, the excessive addition of Ce4 + can degrade the homogeneity, resulting in the decrease of the corrosion resistance of Ni–Cu–P coatings.

► Ce4 + ions affect the electroless deposition of Ni–Cu–P coatings.
► Proper addition of Ce4 + ions refines the average grain size of Ni–Cu–P coatings.
► The refinement of grain size enhances the corrosion resistance of Ni–Cu–P coatings.
► Excess addition of Ce4 + ions degrades the quality of Ni–Cu–P coatings.