Influence of physical electrodeposition attributes on mechano-tribo and wettability characteristics of Ni-Co enhanced nanocoating.

Abstract

The current work presents a systematic exploration of the pulse electrodeposition process for Ni-Co nanocoating, with a focus on the impact of varying duty cycles (20% to 100%) and current density (3 A/dm² to 9 A/dm²). The work is marked by incremental changes in duty cycle and current density and employs state-of-the-art characterisation techniques to analyse surface properties, mechanical strength, tribological behaviour and wettability. Ni-Co pulse electrodeposition at 20% duty cycle and 3 A/dm² current density dominates with desired attributes for the electronics and aerospace sectors with improved mechano-tribo and contact angle properties. These coatings exhibited superior performance across all aspects that have been studied. The nanotribological experiments were conducted using a novel approach to look into the nanoscale tribological behaviours, thus setting a pioneering effort in this field. Reduction in grain size (~57-83%) and enhancement in surface roughness (~64-65%) were the crucial factors contributing to improved mechanical and tribological properties. The nanohardness of the coating increased to 4.36 GPa for the optimum coating, compared to other coatings with varying properties. Similar improvements were recorded in nanotribological properties, with an improvement of ~30%-70% for coatings at 20% duty cycle and 3 A/dm2. The synergetic effect of lower grain size, nano-hardness and surface roughness properties leads to an improved mechano-tribo coating. This advancement holds good potential for industrial applications where wear resistance and surface durability are critical. The optimal coating was analysed by employing X-ray photoelectron spectroscopy (XPS) for chemical compositions of coatings, which confirms the formation of nickel oxide and cobalt oxide. This chemical insight adds a valuable layer of understanding, reinforcing the coatings' potential for corrosion resistance and other chemical interactions in a wide range of operation environments.