Structural Characterization of Electrodeposited Ni Coatings Filled with Graphite or MoS2 Particles

Electrodeposited nickel layers filled with various amounts of graphite or MoS2 particles were prepared on the surface of mild steel substrate (S 235). The weight fractions of solid lubricants in the obtained coatings were determined by atomic absorption. The structural and morphological changes induced by these particles within the nickel matrix were then investigated through X-ray diffraction (XRD), Scanning electron microscopy (SEM), and optical microscopy (OM). It was found that the introduction of lubricating particles had a profound impact on the nickel coatings. In the case of nickel-graphite coatings, while the morphology was transitioned from a pyramidal structure to a local nodular one, nickel-MoS2 coatings exhibited a cluster-like structure. These changes resulted in a more randomized structure and a reduction in nickel grain size. Furthermore, the topographical characteristics of the coatings were assessed using a tactile profilometer. The roughness of the composite coatings increased with higher lubricant particle content, reaching its peak at 29% MoS2 in Ni-MoS2 layers.