The present work presents a comprehensive and systematic study of the degreasing and etching processes which are an important part of the pre-treatment of dielectric materials. The reported investigations aim to select the appropriate operating regimes and compositions of the solutions used in these two operations. The criteria for their effectiveness are properties of subsequent nickel-phosphorus coatings deposited by chemical nickel plating process included as a finishing stage in the dielectric pretreatment. The polymer Acrylonitrile Butadiene Styrene is used as а dielectric. The changes in the roughness and surface morphology of dielectrics as a result of the degreasing and etching operations are evaluated by a profilometer-profilograph device and by scanning electron microscopy. The degreasing operation carried out in a solution of the surfactant SLS (0.3 g L⁻¹) provides more uniform etching of the surface of the dielectric. Furthermore, the addition of SLS and Pd(II) in the etching solution leads to increase in the degree of roughness of ABS compared to the samples treated in a non-additive solution, to better adhesion between the deposited metal coating and the substrate, as well as increasing of the thickness of the subsequent Ni-P coating.

Composite coatings, based on nickel or cobalt matrix with incorporated boron nitride particles (BN) as dispersoid, have been chemically deposited and investigated. The mass, and relative thicknesses, of the obtained composite coatings, as well as the number of co-deposited particles, depending on the type (alpha boron nitride – BN(h) or cubic boron nitride – BN(c)) and particle size of the dispersoid, as a function of dispersoid concentration in the working electrolyte and the concentration of the reducing agent in the plating electrolyte have been determined. The morphology, structure and chemical composition of the deposited coatings have been characterised by means of SEM and EDS analysis.

The present study investigates the effect of synthetic diamond nanoparticles as functional modifiers of NiCoP coatings, simultaneously addressing their corrosion resistance and bifunctional HER/OER electrocatalytic performance on Fe-steel substrates. A direct comparison between electroless and electrodeposition routes is presented. The corrosion behaviour of the coatings was evaluated ex situ in 1 M and 6 M KOH electrolytes to assess their stability under both operating and accelerated degradation conditions. The as-prepared and alkali-treated coatings were characterized by potentiodynamic polarization measurements, X-ray diffraction (XRD), field-emission scanning electron microscopy coupled with energy-dispersive spectroscopy (FE-SEM/EDS), and X-ray fluorescence (XRF) analysis. In addition, their bifunctional electrocatalytic performance toward the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) was evaluated. The results demonstrate that synthetic diamond incorporation influences the corrosion behaviour of NiCoP coatings; however, the magnitude and direction of this effect depend strongly on both the deposition route and the electrolyte concentration. Furthermore, co-electrodeposition combined with synthetic diamond nanoparticles emerges as a promising approach for developing PGM-free, diamond-modified NiCoP composite coatings on commercially available Fe-steel substrates, providing an effective balance between coating microstructure, corrosion resistance, and bifunctional electrocatalytic performance.