A comprehensive investigation of the effect of pulse plating parameters on the electrodeposition of Ni/ZrO2 composite coatings

This study investigates the pulsed electrodeposition of Ni/ZrO 2 composite coatings under different frequency ( f ) and duty cycle ( γ ) values. It was found that these pulse conditions significantly influence the physicochemical phenomena at the cathode-electrolyte interface, which, in turn, impacts the electrocrystallization process of the electrodeposited metal. X-ray diffraction (XRD) analysis revealed that the crystalline orientation of the Ni/ZrO 2 coatings varied with the applied f and γ values. Specifically, deposits made at f =10 and 100 Hz with γ =30% and 90% followed a [100] fibre texture, while coatings produced at f =0.01 and 0.1 Hz under the same γ values exhibited a predominant [211] orientation. A mixed [100]+[200] orientation was observed in all other coatings. By adjusting the f and γ values, the mean crystallite size ranged from 19 to 33 nm. Energy-dispersive X-ray spectroscopy (EDS) results showed that the zirconia particle incorporation varied from 1.70% wt to 15.5% wt, depending on the pulsed current conditions. Coatings produced at lower f and γ values exhibited higher particle content, whereas those with γ=90% showed the lowest incorporation rates. Scanning electron microscopy (SEM) images revealed a cauliflower-like morphology, with zirconia particles evenly distributed across the surface. Transmission electron microscopy (TEM) further confirmed sub-micron particle clusters within the metal matrix. Atomic force microscopy (AFM) analysis indicated an uneven topography with no surface defects. The surface roughness varied between Ra=0.22 μ m and Ra=0.80 μ m. Additionally, microhardness testing showed a significant increase in hardness, reaching a maximum of HV = 476 kp∙mm -2 under f =10 Hz and γ =70%. • The Ni microcrystalline aggregates impose the cauliflower-like surface morphology. • The particles incorporation increases nine-fold by the variation of the f and . • The mechanistic aspects of the resulting textural modifications are revealed. • Crystalline refinement resulted by the particles embedment and P.C. application. • By altering the P.C. parameters, the microhardness increases by 133 kp∙mm -2 .