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Item Prediction and optimization of microhardness and corrosion behaviour of CuNi-Gr composite coatings(University of Politennica, 2024) Belgamwar, Sachin U.; Rathore, Jitendra S.Graphene nanoplatelets (Gr) as fillers for alloy composite coatings has increased due to their remarkable high aspect ratio and distinctive plate-like structure. Piping, condensers and heat exchangers in seawater systems, desalination plants, marine hardware and boat hulls are expected to exhibit high wear and corrosion resistance. For this purpose, CuNi-Gr composite coatings have been fabricated using electrodeposition technique and investigated their microhardness and anti-corrosion properties. During the electrodeposition of coatings, the various process variables such as pH, current density, Gr concentration and amount of nickel sulfate have been taken into account. To achieve the full potential of CuNi-Gr composite coating in engineering applications, this study optimizes the performance of the CuNi-Gr composite coating using an orthogonal array design of a Taguchi technique. By Taguchi and regression analysis, it was found that the Gr concentration in the electrolyte is the most influencing parameter of the process for microhardness and polarization resistance of the CuNi-Gr composite coatings. It has been observed that the microhardness and polarization resistance of the composite coatings increase with the increase in the Gr content up to 400 mg/L.Item Remarkable tribo-mechanical, anticorrosion and antibacterial properties of ZnCu/GNPs composite coatings prepared by electro-co-deposition technique(Elsevier, 2024-06) Rathore, Jitendra S.; Belgamwar, Sachin U.Herein, we report the fabrication of graphene nanoplatelets (GNPs) reinforced zinc-copper (ZnCu) matrix composite coatings on a stainless-steel substrate using electro-co-deposition technique. The influence of varying concentrations of GNPs in the acidic electrolyte bath on the microstructure, chemical composition, phase structure, hardness, wear resistance, corrosion resistance, and antibacterial activity of ZnCu/GNPs composite coating was investigated. The microhardness of the ZnCu/GNPs composite coating with a GNPs concentration of 100 mg/L is compared with pure ZnCu coating, which has a 90 % significant enhancement, while (50 mg/L) has 86 %, and (25 mg/L) has 50 %. Also, ZnCu/GNPs composite coating showed a wear loss of 10 mg for 100 mg/L GNPs sample with an increase in microhardness. The bacterial resistance assays were conducted against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The results reveal a notable improvement in the anti-bacterial activity of the ZnCu/GNPs composite coating. The corrosion rate of the ZnCu/GNPs composite coating in 3.5 wt % NaCl solution steadily decreased when the concentration of GNPs in the electrolyte bath was increased to 100 mg/L. These findings hold great potential for various applications, including healthcare settings where preventing healthcare-associated infections is critical, public infrastructure to prolong the lifespan of structures, and marine coatings to protect against corrosion in harsh marine environments.Item Electro-codeposited γ-Zn-Ni/Gr composite coatings: Effect of graphene concentrations in the electrolyte bath on tribo-mechanical, anti-corrosion and anti-bacterial properties(Taylor & Francis, 2021-10) Jha, Prabhat Nath; Rathore, Jitendra S.; Belgamwar, Sachin U.In this paper, low-cost and industrially scalable γ-Zn-Ni/Gr composite coatings were electro-codeposited from an acid-sulphate based electrolyte bath. The microstructure, morphology, composition, microhardness, wear performance, corrosion resistance and anti-bacterial properties of the composite coatings were investigated in detail and compared with a Zn-Ni alloy coating. The XRD diffraction peaks of prepared coatings confirm the presence of the γ phase of the Zn-Ni alloy. Results suggested that the addition of Gr effectively reduced the crystallite size and altered the morphology. As a result, the microhardness, wear performance and corrosion resistance were improved significantly. The γ-Zn-Ni/Gr composite coating prepared with 100 mg L−1 of Gr addition in the electrolyte bath displayed the highest microhardness of 243 HV and the lowest coefficient of friction of 0.32. The anti-bacterial activity tests confirmed that the γ-Zn-Ni/Gr composite coating (from the 100 mg L−1 bath) has the highest anti-bacterial activity against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus).Item Facile synthesis of graphene by ultrasonic-assisted electrochemical exfoliation of graphite(Elsevier, 2021) Belgamwar, Sachin U.; Rathore, Jitendra S.Graphene, a 2-dimensional form of carbon, attracted significant attention in a wide range of applications such as energy storage, power generation, chemical sensors, composite materials owing to its unmatched physical and chemical properties. In this study, graphene powder was synthesized by ultrasonic-assisted electrochemical exfoliation of the graphite electrode from acidic bath. An external ultrasonic bath (ultrasonic frequency of 40 kHz and ultrasonic power of 180 W) was employed to provide ultrasonic assistance during the electrochemical exfoliation process. The synthesized graphene powder was characterized with FTIR spectroscopy, Raman spectroscopy, XRD, and SEM techniques to study the chemical, microstructural and morphological properties. FTIR spectrum exhibited the C–O and O–H functional groups and the C=C stretching of the hexagonal ring of graphene. Raman spectrum showed two sharp peaks for ID and IG bands at ∼1350 cm−1 and ∼1580 cm−1, respectively. The XRD results revealed the polycrystalline nature of graphene powder. The SEM results showed various sizes and shapes of graphene powder. Our proposed method shows huge potentials for facile synthesis of graphene powder on a large scale.