Browsing by Author "Alok Kumar Chaudhari"

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A review of fundamental aspects, characterization and applications of electrodeposited nanocrystalline iron group metals, Ni-Fe alloy and oxide ceramics reinforced nanocomposite coatings
(Elsevier Ltd, 2018) Alok Kumar Chaudhari; V.B. Singh
Electrochemical co-deposition of materials offers some unique advantages over competing technologies and therefore occupies special place in science and technology. Ni-Fe alloys are of great commercial interest owing to their interesting mechanical, electrical, magnetic and corrosion resistant properties. In this communication the present state of art on the electrodeposition of iron group metals and specially Ni-Fe alloy and oxide ceramic reinforced nanocomposites is reported along with a brief overview of fundamental principles, techniques and engineering applications of these metal matrix composites (MMCs) which include their ductility, hardness, electrical resistivity, thermal stability, corrosion resistance, soft magnetic and superparamagnetic properties. These properties of the deposits are mainly dependent on their composition, plating parameters and nature, size, content and distribution of the incorporated ceramic particles in the matrix. Potential commercial applications of these coatings have been discussed and attempts have been made to define accurate and predictive correlations with plating parameters. © 2018 Elsevier B.V.
Erratum: Studies on electrodeposition, microstructure and physical properties of Ni-Fe/In2O3 nanocomposite (Journal of The Electrochemical Society (2015) 162 (D341))
(Electrochemical Society Inc., 2015) Alok Kumar Chaudhari; V.B. Singh
[No abstract available]
Impact of CeO2 incorporation in electrodeposited Ni-Fe on structure and physical properties of multifunctional nanocomposites
(Elsevier B.V., 2019) Alok Kumar Chaudhari; V.B. Singh
A new type of nanocomposite, Ni-Fe/CeO2 (∼40 nm) was prepared by cathodic co-deposition at several current densities (1.0–5.0 A dm−2) from an ethylene glycol bath. Coatings obtained from optimized bath were characterized by field emission scanning electron microscope (FESEM), energy dispersed X-ray analyzer (EDAX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Electrochemical and physical properties of the coatings were studied as a function of variation in current density and in CeO2 particle content. Compared to Ni-Fe alloy, these nanocomposites exhibited finer grains, higher microhardness, better electrical conductivity, improved corrosion resistance and enhanced soft magnetic properties. The effect of annealing temperature on surface morphology, microstructure, texture and microhardness was also studied. CeO2 particles were found involved in managing textural evolution of Ni-Fe growth resulting in a shift in preferred orientation from (1 1 1) to (2 2 0) crystallographic plane with increasing current density. The incorporation of CeO2 particles (up to 5 wt%) also results in improvement in surface smoothness, and physical and electrochemical properties. © 2016 The Authors
Impact of ZrO2 reinforcement on the surface roughness, electrical and magnetic properties of the nano-permalloy
(Web Portal IOP, 2019) Alok Kumar Chaudhari; V.B. Singh
Ni-Fe alloy and Ni-Fe/ZrO2 nanocomposite, electro co-deposited from ethylene glycol bath, were evaluated in terms of magnetic, electrical, surface roughness and corrosion resistant properties. The properties of the nanocomposite coating were found to mainly depend on the ZrO2 particle content of the coatings. The surface of the Ni-Fe/ZrO2 nanocomposite coating was found to be smoother and more resistant to corrosion than the alloy because of the inert nature of the embedded ceramic particles. The electrical resistivity of the electro deposits increased with the increasing content of the ZrO2 particles in the coating. Magnetic studies revealed that the composite coatings have very small magnetic remanence and coercivity. Saturation magnetization (Ms) of the composite was reduced after incorporation of nonmagnetic ZrO2 nanoparticles in the Ni-Fe alloy matrix. © 2019 The Korean Society for Composite Materials and IOP Publishing Limited
Improvement in different properties of the permalloy by nano-Cr2O3 incorporation
(Springer Netherlands, 2017) Alok Kumar Chaudhari; V.B. Singh
Abstract: This paper deals with the study of improvement in different properties of the Ni–Fe alloy matrix by incorporation of Cr2O3 nanoparticles. Ni–Fe/Cr2O3 nanocomposite coatings were electrodeposited from ethylene glycol bath at several current densities using nickel sulfamate and ferrous sulfate. The coatings were characterized by powder X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray analysis, transmission electron microscopy, and atomic force microscopy. Although a change in the surface morphology from fine granular to coarse granular was observed on the incorporation of Cr2O3 nanoparticles, surface roughness of the composite coatings was found lower than the alloy at the optimum current density. At lower current density, preferred orientation of the coating was found along (111) plane while at higher current densities it was along (200) plane. An improvement in the microhardness of the Ni–Fe alloy was recorded (>900 HV) after the nano-Cr2O3 incorporation. Despite incorporation of ceramic particles above 5 wt%, lower electrical resistivity and higher corrosion resistance of the alloy matrix were retained in the nanocomposite coatings. The deposits have shown soft magnetic characteristics. © 2017, Springer Science+Business Media B.V.
Mechanical and physical properties of electrodeposited Ni-Fe, WO3 doped nanocomposite
(Elsevier B.V., 2016) Alok Kumar Chaudhari; V.B. Singh
The mechanical and magnetic properties of Ni-Fe alloy deposits may be controlled by compositional tailoring and reinforcement by ceramics. The incorporation of high content of ceramic particles in the alloy matrix has, however, detrimental effect on electrical and magnetic properties of the nanocomposites. Here, electrodeposition of WO3 nanoparticle (spheroidal shaped, 20–40 nm) doped Ni-Fe nanocomposites has been carried out in an organic bath at various current densities. The particle content in coating was found up to ~ 2.0 wt%. Field emission scanning electron microscope (FESEM), energy dispersed X-ray analyzer (EDAX) and atomic force microscopic (AFM) examinations revealed a distinct change in morphology of the deposit due to inclusion of the particles in the matrix. X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies showed fcc lattice of the matrix and a shift in preferred orientation of the coating from (111) to (220) crystallographic planes with increasing current density. Significant enhancement in the microhardness of the coatings was observed on incorporation of only 1.25 wt% WO3 particles due to solid solution hardening and dispersion hardening. An improvement in the conduction and corrosion resistance of the coatings over matrix has also been noticed due to dispersion of the ceramic particles in the matrix. Magnetic studies point to ferromagnetic behavior of the nanocomposite which also has the tendency of superparamagnetism. © 2016 Elsevier B.V.
Nanomaterials in Electrochemical Synthesis
(CRC Press, 2024) Alok Kumar Chaudhari; V.B. Singh
Nanomaterials in electrochemical synthesis for energy storage applications have enabled a rapid expansion in the scope of this sustainable technology. Electrochemical synthetic approaches are a convenient and greener alternative to the harsh chemical redox reagents used in conventional synthetic approaches. Nanomaterials have excellent electrical, magnetic, mechanical, optical and surface properties and can be synthesized in various shapes and sizes, which make them a potential candidate for energy storage materials. Electrochemical synthetic routes and energy storage nanomaterials have greatly developed in the past few decades, resulting in an improved understanding of structure-property-performance relationships. This chapter highlights the basic principles, requirements and influencing factors of electrochemical synthesis and recent developments in the electrochemical synthesis of energy storage nanomaterials. Applications of some electrochemically synthesized novel nanomaterials for different energy storage systems such as electrochemical capacitors, Li-ion batteries and hydrogen energy storage have been described briefly. Finally, we have outlined the important aspects of this chapter and included our personal perspectives on this dynamic emerging field. © 2025 selection and editorial matter, Piyush Kumar Sonkar and Vellaichamy Ganesan.
Structural Features and Functional Properties of Y2O3 Reinforced Nickel Matrix Nanocomposites
(Wiley-Blackwell, 2020) Alok Kumar Chaudhari; Vijai Bahadur Singh; Bachcha Singh
Metal matrix composites with yttria as reinforcement are mostly produced because of it's improved mechanical properties while thermal stability, electrochemical and magnetic properties of the yttria based composites are rarely considered. In the present study, the feasibility of incorporating yttria nanoparticles into nickel matrix from ethylene glycol bath by electro-codeposition method is demonstrated. The particle content of the coatings was strongly influenced by current density i. e. the rate of metal deposition. Particle content, surface morphology and microstructural changes of the deposits were investigated by scanning electron microscope (SEM) equipped with energy dispersed X-ray analyzer (EDAX). A dense, compact and smoother composite surface with lower particle content was obtained at higher current densities. Crystallographic structure, texture and lattice strain have been evaluated using X-ray diffraction (XRD). Incorporation of yttria particles inhibits the grain growth and causes grain refinement of the nickel matrix. Annealed nanocomposite deposits revealed thermal stability up to 700 °C. The comparative electrochemical corrosion behavior of the electrodeposited coatings in 3.5 % NaCl solution and their deposition potential were evaluated. Magnetic studies showed nearly complete absence of hysteresis i. e. soft magnetic nature of the coatings. © 2020 Wiley-VCH GmbH
Structure and properties of dual oxide particles doped Ni-Fe/In2O3-WO3 functional nanocomposite coatings
(Electrochemical Society Inc., 2017) Alok Kumar Chaudhari; V.B. Singh
In the present study two types of oxide ceramic particles In2O3 (2.0 g/L) and WO3 (4.0 g/L) were reinforced into the Ni-Fe alloy matrix by electro-codeposition for the first time. Despite lower concentration in the bath solution, incorporation of In2O3 particles was higher (up to 5.5 wt%) as compared to the WO3 particles (up to ∼3.0 wt%). Coatings obtained under optimum condition show permalloy composition (80 wt% Ni-20 wt% Fe) between the range of current density 3.0-5.0 A dm-2. The coatings were characterized by XRD, FESEM, EDAX, TEM and AFM. The effect of incorporation of these oxide particles and current density on the structure and properties of the nanocomposite coatings was investigated. XRD and TEM studies showed fcc lattice of the matrix with preferred orientation along (111) plane but the relative texture coefficient along (111) plane decreases with increasing current density. Dominance of In2O3 particles on the surface morphology of the coatings was also observed. However, results showed that electrical resistivity, corrosion resistance and microhardness (up to 1025 Hv) of the Ni-Fe/In2O3-WO3 nanocomposite were found between those for the Ni-Fe/In2O3 and Ni-Fe/WO3 nanocomposite coatings. Magnetic studies revealed the soft magnetic nature of the nanocomposite coatings. © 2017 The Electrochemical Society. All rights reserved.
Structure and properties of electro co-deposited Ni-Fe/ZrO2 nanocomposites from ethylene glycol bath
(Electrochemical Science Group, 2014) Alok Kumar Chaudhari; V.B. Singh
Ni-Fe/ZrO2 nanocomposite coatings were prepared by electrodeposition under direct current condition from nickel sulfamate and ferrous sulphate bath with ZrO2 nanopowder using ethylene glycol as a solvent. Plating parameters like current density, concentration of ZrO2 particles and electrolytes, temperature and agitation were optimized in terms of particle incorporation, microhardness and brightness of the deposits. Morphology, composition, micro and crystallographic structures of the coatings were investigated by SEM, EDAX, XRD and TEM. The iron content in the deposit varies from 38.2% to 19.1% showing fcc lattice by the Ni-Fe alloy matrix. Due to incorporation of ZrO2 particles in Ni-Fe matrix average crystallite size of the deposit reduces to ≈11 nm. The effect of current density and annealing temperature on microstructure, texture and microhardness was studied. With increasing current density from 1.0 to 5.0 A/dm2 there is shifting of preferred orientation from (111) to (220) crystallographic plane.
Structure, mechanical and magnetic properties of Al4C3 reinforced nickel matrix nanocomposites
(Institute of Physics Publishing, 2018) Alok Kumar Chaudhari; Dhananjay Kumar Singh; V.B. Singh
A new type of nanocomposite, Ni-Al4C3 was prepared using Al4C3 as reinforcement by cathodic co-deposition at different current densities (1.0 to 5.0 A dm-2) from a nickel acetate-N-methyl formamide (non-aqueous) bath. Influence of current density and incorporation of Al4C3 particles in nickel matrix on the structure and properties of the composite coatings was investigated. Surface morphology and composition of the deposits were determined by SEM and EDAX. Crystallographic structure and orientation of the electrodeposited Ni-Al4C3 composite were studied by x-ray diffraction. Compared to nickel metal, these nanocomposites exhibited finer grains, higher microhardness, improved corrosion resistance and enhanced soft magnetic properties. Composite deposited at higher current densities (>2 A dm-2) shows mild texturing along (200) plane. The effect of heat treatment on the microstructure, texture and microhardness of the nanocomposites was also investigated. © 2018 IOP Publishing Ltd.
Studies on electrodeposition, microstructure and physical properties of Ni-Fe/In2O3 nanocomposite
(Electrochemical Society Inc., 2015) Alok Kumar Chaudhari; V.B. Singh
In2O3 nanoparticles (<100 nm) up to 5 wt% are incorporated into Ni-Fe alloy matrix by electrodeposition which enhance both corrosion resistance and hardness. Plating parameters like current density, concentration of metal ions and In2O3 particles, agitation and the temperature of the bath were optimized to achieve acceptable quality of the coatings. Effect of current density on the development of Ni-Fe/In2O3 nanocomposites and their physical properties was mainly studied. Coatings thus obtained were characterized by SEM-EDAX, XRD, TEM and AFM and surface morphology, crystal structure, microhardness, corrosion resistance, magnetic behavior and electrical resistivity of the nanocomposites were studied. The incorporation of conducting In2O3 particles in a alloy matrix resulted in a higher electrical conductivity than the matrix. X-ray diffraction results showed that the incorporation of In2O3 particles does not affect the Ni-Fe alloy fcc structure but alters the texture of the deposits favoring (111) crystallographic orientation and is independent of the applied current density for deposition. The crystallite size of the nanocomposites is found in the range of 5-13 nm with almost negligible strain. © 2015 The Electrochemical Society.
Synthesis, Characterization and Physical Properties of Tantalum Pentoxide Reinforced Ni-Fe Alloy Matrix Nanocomposites
(Wiley-Blackwell, 2018) Alok Kumar Chaudhari; Vijai Bahadur Singh
Soft magnetic Ni−Fe/Ta2O5 nanocomposites were synthesized by electro-codeposition on a copper substrate from an ethylene glycol bath. Formation of the composites, tantalum oxide particle content and structure evolution were investigated using X-ray diffractometer (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM) and energy dispersive X-ray analyzer (EDAX). Maximum particle content of the deposits was up to 5.7 wt% and clusters of Ta2O5 particles were found on the coating surface. This appears beneficial for improving the corrosion resistance of the coatings. With increasing current density, relative texture coefficient of the coatings shifted from (111) to (200) and followed (220) crystallographic plane. Although crystallite size was recorded approximately 15 nm in the entire current density range studied, remarkable enhancement in the microhardness of the Ni−Fe/Ta2O5 nanocomposite coatings was noticed (up to 870 HV) owing to reinforcement of ceramic particles. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim