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Item Electrodeposition of laminar coatings of Ni-W alloy and their corrosion behaviour(Elsevier, 2015) Elias, L.; Hegde, A.The attractiveness of electroplating for the synthesis of advanced materials is linked to large selection of plating conditions coupled with different mass transfer processes towards the cathode, and this allows the tailoring of different properties of many electrodeposited coatings. This theme has been exploited effectively in the development of a new class of coatings; called composition modulated multilayered (CMM), or in short laminar coatings. The work embodied in this paper is to demonstrate how the corrosion resistance of monolayer Ni-W alloys can be increased to many fold of its magnitude by multilayer deposition. Ni-W coatings have been deposited on mild steel (MS) in a laminar multilayer pattern from a citrate bath using single bath technique (SBT). Electrodeposits having alternate layers of alloys, having different compositions were developed by modulating the direct current (DC). CMM coating configurations have been optimized from a newly developed bath, in terms of current pulse height and thickness of each layer to maximize its corrosion protection ability, in relation to its monolayer coating, developed from same bath for same time. The process and product of the Ni-W coatings have been characterized using different instrumental methods, such as cyclic voltammetry (CV), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) study. The better corrosion resistance behaviour of CMM Ni-W coatings has been analysed in the light of increased surface areas of the coatings due to layering, and results are discussed. © 2015 Elsevier B.V.Item Multilayered Zn-Ni alloy coatings for better corrosion protection of mild steel(Elsevier B.V., 2017) Rashmi, S.; Elias, L.; Hegde, A.C.A simple aqueous electrolyte for the deposition of anti-corrosive Zn-Ni alloy coatings was optimized using conventional Hull cell method. The corrosion protection value of the electrodeposited coatings at a current density (c.d.) range of 2.0–5.0 A dm?2 has been testified in 5 wt% NaCl solution, as representative corrosion medium. The electrochemical behavior of the coatings towards corrosion was related to its surface topography, elemental composition and phase structure using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analyses, respectively. Among the monolithic coatings developed at different c.d.’s, the coating obtained at 3.0 A dm?2 was found to be the best with least corrosion current (icorr) value. Further, the corrosion protection efficacy of the monolayer coatings were improved to many folds through multilayer coating approach, by modulating the cyclic cathode current densities (CCCD's). The composition modulated multilayer (CMM) Zn-Ni alloy coating with 60 layers, developed from the combination of CCCD's 3.0 and 5.0 A dm?2 was found to be the best with 3 fold enhancement in corrosion protection efficiency. The formation of multilayer coatings was confirmed using cross-sectional SEM, and the experimental results are discussed with tables and figures. © 2016 Karabuk UniversityItem Effect of Magnetic Field on HER of Water Electrolysis on Ni–W Alloy(Springer New York LLC barbara.b.bertram@gsk.com, 2017) Elias, L.; Hegde, A.C.Electroactive Ni–W alloy coating with a specific composition was developed as an efficient electrode material for hydrogen evolution reaction (HER) through electrodeposition technique. The high overvoltage towards HER at the electrode surface was reduced by an applied magnetic field during water electrolysis. The effect of introduced magnetic was studied under different applied magnetic field strengths (varying from 0.1 T to 0.4 T) to epitomize the HER efficiency. The enhancement in HER efficiency of the Ni–W alloy electrode in the presence of the applied magnetic field was established through electrochemical analysis and also by quantifying the amount of H2 gas evolved during the analysis. The improvement in HER efficiency of Ni–W alloy under induced magnetic field may be attributed to the magnetohydrodynamic (MHD) force-induced convection and H2 bubble disentanglement. The coating was characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) analyses. The magnetic field-induced efficient water electrolysis is explained with plausible mechanisms, and the results are discussed. © 2017, Springer Science+Business Media New York.Item Electrolytic Synthesis of Ni-W-MWCNT Composite Coating for Alkaline Hydrogen Evolution Reaction(Springer New York LLC barbara.b.bertram@gsk.com, 2018) Elias, L.; Hegde, A.C.Nickel–tungsten multi-walled carbon nanotube (Ni-W-MWCNT) composite films were fabricated by an electrodeposition technique, and their electrocatalytic activity toward hydrogen evolution reaction (HER) was studied. Ni-W-MWCNT composite films with a homogeneous dispersion of MWCNTs were deposited from an optimal Ni-W plating bath containing functionalized MWCNTs, under galvanostatic condition. The presence of functionalized MWCNT was found to enhance the induced codeposition of the reluctant metal W and resulted in a W-rich composite coating with improved properties. The electrocatalytic behaviors of Ni-W-MWCNT composite coating toward HER were studied by cyclic voltammetry (CV) and chronopotentiometry techniques in 1.0 M KOH medium. Further, Tafel polarization and electrochemical impedance spectroscopy (EIS) studies were carried out to establish the kinetics of HER on the alloy and composite electrodes. The experimental results revealed that the addition of MWCNTs (having a diameter of around 10-15 nm) into the alloy plating bath has a significant effect on the electrocatalytic behavior of Ni-W alloy deposit. The Ni-W-MWCNT composite coating was found to show better HER activity than the conventional Ni-W alloy coating. The enhanced electrocatalytic activity of Ni-W-MWCNT composite coating is attributed to the MWCNT intersticed in the deposit matrix, evidenced by surface morphology, composition and phase structure of the coating through SEM, EDS and XRD analyses, respectively. © 2018, ASM International.Item Effect of TiO2 nanoparticles on hydrogen evolution reaction activity of Ni coatings(University of Science and Technology Beijing, 2018) Kullaiah, R.; Elias, L.; Hegde, A.C.The electrocatalytic activity of electrodeposited Ni and Ni–TiO2 coatings with regard to the alkaline hydrogen evolution reaction (HER) was investigated. The Ni coatings were electrodeposited from an acid chloride bath at different current densities, and their HER activities were examined in a 1.0-mol·L-1 KOH medium. The variations in the HER activity of the Ni coatings with changes in surface morphology and composition were examined via the electrochemical dissolution and incorporation of nanoparticles. Electrochemical analysis methods were used to monitor the HER activity of the test electrodes; this activity was confirmed via the quantification of gases that evolved during the analysis. The obtained results demonstrated that the Ni–TiO2 nanocomposite test electrode exhibited maximum activity toward the alkaline HER. The surface appearance, composition, and the phase structure of all developed coatings were analyzed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD), respectively. The improvement in the electrocatalytic activity of Ni–TiO2 nanocomposite coating toward HER was attributed to the variation in surface morphology and increased number of active sites. © 2018, University of Science and Technology Beijing and Springer-Verlag GmbH Germany, part of Springer Nature.