Browsing by Author "Raveendran, M.N."

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    Anomalous codeposition of NiCo alloy coatings and their corrosion behaviour
    (Elsevier Ltd, 2022) Raveendran, M.N.; Hegde, A.C.
    Here, we report the electrodeposition NiCo alloy coatings from a new bath using the glycine, as additive. A bright and uniform coatings NiCo alloy have been developed at different current densities and their corrosion performances have been evaluated. The surface morphology, composition and phase structure of alloy coatings have been analyzed using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS) and X-ray diffraction (XRD) techniques, respectively. The compositional information of NiCo alloy coatings revealed that the proposed bath follows anomalous type of codeposition over range of current density studied (1.0–4.0 A dm−2), by demonstrating more Wt. % of Co in the deposits, than in the bath. A constant increase in the Wt. % of Ni with current density was found, supported by XRD analyses; and it may be attributed to the depletion of more readily depositable Co+2 ions at cathode film by following the principle of codeposition of NiCo alloy. The corrosion study revealed that NiCo alloy deposited at 4.0 A dm−2, represented as (NiCo) 4.0 A dm-2 coating is the most corrosion resistant compared to all other coatings. The highest corrosion stability of (NiCo) 4.0 A dm-2 alloy attributed to its highest Ni content (38.6 wt%) and increased surface smoothness, supported by EDS and SEM study. © 2022
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    Electrodeposition of multilayer NiW alloy coating for improved anticorrosion performance
    (Springer, 2021) Raveendran, M.N.; Hegde, A.C.
    The attractiveness of electroplating linked to cathodic current density (CD) has tried to exploit here to the development of coatings of high corrosion resistance. Multilayer NiW alloy coatings of better anticorrosion performance were electrodeposited from a tartrate bath by periodic pulsing of CD between two values, during the process of deposition. The multilayer coatings of different configurations, in terms of composition and thickness of individual layers were developed by proper modulation of amplitude and duration of the square current pulse, respectively. The deposition conditions were optimized for best performance of the coatings against corrosion. Our experimental study revealed that under optimal condition, multilayer NiW coating having (NiW)1.0/3.0/120 configuration is almost six times more corrosion resistant than its monolayer coating, deposited from same bath for same duration. The reason for improved corrosion performance in multilayer NiW alloy coating was explained in the light of effect of larger interfaces affected due to layered deposition and confirmed by scanning electron microscopy analysis, energy dispersive spectroscopy and X-ray diffraction study. The mechanism of corrosion responsible for its better performance, in relation to its monolayer coating is given, and results are discussed. © 2021, Indian Academy of Sciences.