Electrodeposition of Ni-Fe and Ni-Fe-(nano Al2O3) multilayer coatings

In this study, production of multilayer (ML) coatings of Ni-Fe-Al2O3 has been carried out by using the pulse electrodeposition. The substrate was low carbon steel and the number of consecutively deposited layers was in eight layers. At the first step of investigation, the eight consecutive layers were deposited one after another on the surface with frequency of 100 and 6400 Hz at constant duty cycle of 88%. At the second step, the frequency was constant and the duty cycles of 11% and 88% were considered in order to electrodeposit eight layers from a bath. The results of EDS the exhibited that the variation of frequency had no significant effect either on the adsorption of nanoparticles or on the contents of Ni and Fe. In contrast, the changing of the duty cycle has been led to the coatings with different contents of Fe and nanoparticles. The deposited layers with duty cycles of 88% and 11% contained 15 wt.% and 37 wt.% Fe respectively. The fraction of trapped particles also is further in the deposited layers with duty cycle of 11%. The potentiodynamic and wear tests were performed on the alloy and nanocomposite coatings. Comparing the results of the ML coatings electrodeposited by two above methods showed that the corrosion and wear resistance are greater in the coatings which its consecutive layers have been deposited with the continuous changing of frequency between two values of 100 and 6400 Hz.