Department of Mechanical engineering
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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 Co-deposited Zn-Cu/Gr nanocomposite: Corrosion behaviour and in-vitro cytotoxicity assessment(Taylor & Francis, 2021-04) Belgamwar, Sachin U.; Rathore, Jitendra S.Zn-Cu alloys have been considered as potential candidates for bioimplant applications due to their moderate corrosion rate and admirable mechanical properties with non-toxic nature to the human body. However, with the incorporation of advanced reinforcements, such as carbon allotropes, the properties and applicability of a Zn-Cu alloy matrix can be further enhanced. In this research, graphene (Gr) nanoplatelets reinforced Zn-Cu/Gr nanocomposites were synthesised through a modified electro-codeposition method with different concentrations of Gr (25, 50 and 100 mg L−1) in the electrolyte bath. The prepared powder samples were compacted and sintered to form pellets. The pellets were tested for mechanical and in-vitro corrosion. The obtained micro-hardness, compressive yield strength (CYS) and ultimate compressive strength (UCS) of Zn-Cu/Gr (100 mg L−1) nanocomposite are 151 HV, 340 MPs and 362 MPa with increments of 84.1%, 118% and 70.7% compared to pure Zn-Cu alloy, respectively. The reduced wear rates and friction coefficients of Zn-Cu/Gr nanocomposites are attributed to crystallite size refinement and Gr content. The electrochemical corrosion rate is reduced by 66.6% from 33 × 10−3 mm year−1 for pure Zn-Cu alloy to 11 × 10−3 mm year−1 for Zn-Cu/Gr (100 mg L−1) nanocomposites, owing to Gr barrier protection. The in-vitro cytotoxicity assessment reveals that the prepared Zn-Cu/Gr nanocomposite is non-toxic for Gr concentration up to 50 mg L−1 in the electrolyte bath. The results show that a non-toxic Zn-Cu/Gr nanocomposite with outstanding tribo-mechanical and anti-corrosion properties can be synthesised by the proposed method.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).