Faculty Publications

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Production of layer by layer Zn-Fe compositional multilayer alloy coatings using triangular current pulses for better corrosion protection
(Maney Publishing, 2015) Bhat, R.S.; Hegde, A.
Multiple-layer coatings of Zn-Fe alloy having alternatively the same compositions have been developed galvanostatically on mild steel (MS) from a single plating bath using triangular current pulses. Thiamine hydrochloride (THC) and citric acid (CA) were used as additives. Multiple-layer coatings were developed under different conditions of cyclic cathode current density (CCCD) and number of layers. Cyclic voltammetry demonstrated that the addition of THC and CA improves the deposit character by increasing the Ni content (through suppressing the deposition of Zn) via preferential adsorption on the cathode surface. The corrosion behaviours of the coatings were evaluated by electrochemical AC and DC methods. The optimum multiple-layer coating, represented as (Zn-Fe)3.0/5.0/300, was found to exhibit about four to five times better corrosion resistance when compared with monolayer (Zn-Fe)3.0 alloy, developed from the same bath for the same duration. Distinct phase structures responsible for interface formation between successive layers (which changes alternatively) were confirmed by X-ray diffraction analysis. Better corrosion resistance afforded by multiple-layer coating was attributed to the increased specific surface area of the coating because of layering. A synergistic effect of both structural difference between layers and individual layer thickness is responsible for enhanced corrosion resistance of the multiple-layer coatings. The formation of multiple layers and corrosion mechanism were analysed by scanning electron microscopy. © 2015 Institute of Materials Finishing.
Ultrasound induced multilayer Ni-Co alloy coatings for better corrosion protection
(Elsevier B.V., 2017) Shetty, A.R.; Hegde, A.
Ultrasound induced multilayer Ni-Co alloy coatings have been developed galvanostatically by periodic modulation of ultrasound effect, parallel to the process of conventional electroplating. Multilayer Ni-Co alloy having alternative layers of different composition were developed by turning the sonicator probe, ON and OFF periodically, while keeping the current density (c.d.) constant. The deposition conditions, in terms of pulsing power density (p.d.) and degree of layering have been optimized for the highest performance of coating against corrosion, evaluated by electrochemical testing methods. Corrosion data revealed that under optimal conditions, multilayer Ni-Co alloy coating having 150 layers, represented as (Ni-Co)2/2/150 is about 11 times more corrosion resistant than its homogeneous coating, represented as (Ni-Co)4.0 A dm ? 2, deposited from the same bath for same duration of time. Improved corrosion resistance of multilayer Ni-Co alloy coatings was attributed to an increase in the number of interfaces, separating the layers of alloys of different composition, affected due to periodic pulsing of the sonicator. The dependence of corrosion behaviors at different combination of c.d. and p.d., on surface morphology, composition and phase structures were analyzed, using scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS) and X-ray diffraction (XRD) technique, respectively. Experimental results are compared, and discussed. © 2017 Elsevier B.V.
Development of Composition Modulated Multilayer (NiTi) Alloy Coatings for Improved Corrosion Protection of Mild Steel
(Pleiades Publishing, 2024) Harshini Sa, G.; Hegde, A.
Abstract: A new class of materials known as composition modulated multilayer (CMM) alloy coatings has created an ever-increasing interest in materials research due to their improved functional properties. In this direction, an effort has been made to improve the poorer corrosion resistance performance of conventional monolayer nickel–titanium (NiTi) alloy coatings (due to inherent induced type of codeposition), their multilayer alloy coatings have been developed. CMM (NiTi) alloy coatings have been fabricated electrolytically on mild steel (MS) from a citrate bath, using the glycerol as additive. Multilayer alloy coatings of varying matrices have been developed by periodic modulation of direct current (DC), in terms of pulse height and pulse duration. Coating configurations in both composition and thickness of alternate layers were optimized for best performance of the alloy coatings against corrosion. Corrosion behaviours were evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization methods. Experimental study revealed that the corrosion rate (CR) of CMM coatings decreased successively with increase in number of layers up to certain limit, and then started increased. Experimental findings demonstrated that CMM (NiTi) alloy coating having optimal configuration, represented as (NiTi)2.0/4.0/120 is approximately five times more corrosion resistant than its monolayer counterpart, deposited from the same bath for same duration. Development of coatings in layered pattern was confirmed by scanning electron microscopy (SEM) analyses. EDX and XRD techniques confirms the composition and phase structure of alloy coatings. The corrosion mechanism responsible for delayed corrosion of multilayer coatings has been explained, and experimental results are discussed. © Pleiades Publishing, Ltd. 2024. ISSN 2070-2051, Protection of Metals and Physical Chemistry of Surfaces, 2024, Vol. 60, No. 2, pp. 178–189. Pleiades Publishing, Ltd., 2024.
Magnetic field-induced codeposition of (Ni–Co) alloy coatings for better corrosion protection
(SAGE Publications Ltd, 2025) Yathish Rai, T.; Hegde, A.
This paper explores the benefit of induced magnetic field (B) in the co-deposition of (Ni–Co) alloy coatings for better corrosion protection. The phenomenon of magnetohydrodynamic (MHD) convection has been used as the tool to deposit (Ni–Co) alloy coatings of high corrosion protection from an electrolytic bath having low [Co+2] ions. Experimental studies demonstrated that under optimal conditions of magnetic field intensity (B), magneto-electrodeposited (MED) coatings, developed under parallel (

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