Morphological and Corrosion Characterization of Electroless Ni-P Coatings Deposited on Ductile Iron

Ductile iron is distinguished by its balance of mechanical properties and other advantageous characteristics, including its capacity to absorb energy. This makes it suitable for applications requiring high strength. However, its performance is impaired by its low corrosion resistance. In this study, a Ni-P coating was applied to the surface of ductile cast iron using electroless nickel plating to increase its corrosion resistance in 0.1 M NaCl. The characterization of the substrate and the coated materials was conducted using scanning electron microscopy, X-ray diffraction, electrochemical impedance spectroscopy, and electrochemical noise. The results show that the coating deposited on a ductile iron is amorphous, compact, homogeneous, and well-adhered. The surface hardness is increased by 53%. Also, a notable increase in corrosion resistance is evidenced by the blocking effect of the coating that delimits the access of the electrolyte to the ductile iron coating. The corrosion mechanism is related to the mixed and localized corrosion phenomena for the different evaluation times.