Galvanostatic cathodic polarization studies on anomalously co-electrodeposited Ni2–18Co13–97 solid solution nano films

Electrochemical kinetics of NiCo electrodeposited solid solution under galvanostatic condition was studied. Tafel slopes, galvanostatic transients, exchange current density data showed that the deposition kinetics of Ni2 + is more sluggish than Co2 +. Factors that enhance the concentration overpotential of Co2 +, facilitates the Ni2 + deposition rate by lowering its activation as well as nucleation overvoltage. Through convection, mass-transfer limitations can be eliminated which in turn raises the activation overpotential. Metal hydroxide and hydride formation steps were proposed, from hydrogen evolution reactions. Co2 + deposition follows predicted Faradaic electron transfer processes at lower cathodic current density rather than Ni2 +. Partial current densities of individual elements were correlated to surface coverage of intermediates. Microhardness as well as yield strength were estimated. EDTA and the additives sulfacetamide, niacin alters the atomic % of alloying elements and refines the morphology. Polyhedral morphology was more dominant than acicular. HCP 002 and FCC 220/111 planes are prevailing for Co rich and relatively higher Ni content deposits, respectively. HCP lattice distortion is insignificant (0.74%) and this leads to form homogeneous solid solution with ‘ε’ phase by encompassing, solute fcc ‘Ni’ in hcp ‘Co’ cluster base. Numerical models were proposed to interpose anomalously deposited Ni atomic %. Standard deviation is minimum for Cubic Hermite interpolation polynomial followed by Lagrange and Neville models. The deposition rate of Ni2 + should be decoupled from Co2 + while interposing the partial current densities with cathodic current density. Computer simulation programs in Visual Studio and MATLAB were designed for the determination of deposition parameters, XRD lattice data analysis and for numerical simulation.