Tailoring effect of Cr and graphene particles on the microstructure and properties of Ni matrix nanocomposite coatings.

Ni matrix nanocomposite coatings with a microstructure tailored by Cr and graphene particles were assembled at various current densities by electroplating. The tailoring effect of particles on the surface morphology, composition, microstructure, and properties of the nanocomposite coating was comprehensively explored. The results revealed that the contents of Cr and graphene particles in the nanocomposite coating were elevated by decreasing the current density, resulting in an increased amount of small dendrite-like surface structures. The embedded particles blocked the formation of [200] fiber texture and concurrently brought about crystallite refinement of the Ni deposits. A COMSOL simulation and BSE images revealed that the embedded particles tailored the microstructure of Ni deposits by heterogeneous nucleation, rearrangement, and local current density concentration. The current density concentration on the particles contributed to the selective growth of Ni deposits on the particles. The synergistic effect of the tailored microstructure and embedded particles substantially enhanced the corrosion resistance of the Ni–Cr–graphene nanocomposite coating. In 3.5 wt% NaCl media, the I corr of the nanocomposite coating electroplated at 1 A/dm2 (0.1 μA/cm2) was an order of magnitude lower than that at 20 A/dm2 (2.63 μA/cm2) owing to the strengthened synergistic effect. [Display omitted] • Cr and graphene tailored Ni matrix nanocomposite coatings were electroplated. • COMSOL simulation reflected the electroplating condition distorted by particles. • Current density concentrated on particles led to the tailored Ni microstructures. • The selective growth of Ni on particles induced the formation of valleys and voids. • Tailored microstructure and particles together enhanced the corrosion resistance. [ABSTRACT FROM AUTHOR]