http://localhost:8081/jspui/handle/123456789/15 2026-10-17T15:46:04Z http://localhost:8081/jspui/handle/123456789/21541 Title: Composite Solid-State Sulphur based electrolyte for Lithium-Sulphur system Authors: Basu, Arka Abstract: In the present spectrum, the world requires a new generation of energy storage systems with high energy density, lightweight, durability and low cost. The liquid electrolyte currently being used in batteries have safety concerns as these are highly volatile and flammable; loss of active material causes a reduction in discharge capacity and short-circuiting due to dendrite formation. For some time now, solid-state batteries have garnered much attention, given their ability to exhibit high safety, high energy density and better cycling efficiency. But the success of these batteries has been hindered by the low ionic conductivity and poor transfer of ions across electrolyte and electrode interface. To improve these properties, a composite solid electrolyte is synthesised. The ceramic electrolyte provides the system with high conductivity and thermal stability; the polymer matrix improves the interfacial properties for better transfer kinetics. In this work, we have fabricated a CSE with Li6PS5Cl electrolyte dispersed in a PVDF matrix. The pristine electrolyte offered an ionic conductivity of 1.227 X 10-4 S/cm. The cell testing gives a 1st discharge capacity of 436.3 mAh/g. This finding opens up the possibility of making high-capacity solid state batteries for the Lithium-Sulphur system. 2023-05-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/21540 Title: Estimation of Temperature and Residual Stress Distribution During Surface Modification Using Tungsten Inert Gas Arcing Authors: Guntupalli, Bramarambika Abstract: This work aims to examine the distribution of temperature and residual stress during surface modification of AISI8620 steel using tungsten inert gas (TIG) arcing. Utilizing the COMSOL software, a 3D finite element analysis is performed to determine the stress and thermal profile at each point of the entire sample. The experimental findings were utilized to determine the properties of the heat source, which was modelled using a double ellipsoid equation. During surface modification, highly localized heating followed by rapid cooling exposes the components to complicated thermal and mechanical loads and creates large residual stress fields, which may enhance the chance of time-dependent failure by encouraging crack initiation. The simulation program is run by coupling solid mechanics and heat transfer in solid. Peak temperature, cooling rate, temperature, and stress distribution along and transverse to the heat load are observed. 2023-05-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/21539 Title: Microstructural and Mechanical properties of Ni-based high entropy superalloys prepared by mechanical alloying and spark plasma sintering Authors: Patel, Bhupendra Abstract: Recently, high entropy superalloys (HESAs) have attracted a lot of research attention for possible medium to high temperature applications such as various parts of jet turbine, aerospace, energy industries and gas turbine due to its high thermal stability and mechanical properties. In this study, nickel-based HESAs were designed based on three different compositions, i.e., Ni45Fe12Co15Cr11.75Al9.75Ti6.5 (HESA-1), Ni43Fe12Co15Cr11.75Al9.75Ti8.5 (HESA-2) and Ni41Fe12Co15Cr11.75Al11.75Ti8.5 (HESA-3). All three compositions were developed by mechanical alloying (MA) technique using a high energy ball-mill (HEBM) followed by spark plasma sintering (SPS). Change in crystallite size with respect to milling time was evaluated by analyzing x-ray diffraction (XRD) profiles of the milled samples, and milling time was optimized to achieve super-saturated alloys. Formation of FCC phase was confirmed after 25h of milling producing a uniform and homogeneous structure. The 25h milled samples were compacted and consolidated using SPS at 1000 °C for a duration of 5 min at an applied pressure of 60MPa. The SPS was performed using 10mm diameter graphite die-punch. Relative density of all three-samples was evaluated using Archimedes method. All three sintered samples were subjected to XRD for phase analysis. Electron backscatter diffraction (EBSD) technique and transmission electron microscopy (TEM) were used to study micrographical features such as grain size, and its homogeneity for all three SPSed alloy specimens. Mechanical properties of the SPSed samples were evaluated using Vickers microhardness and uniaxial compression tests. Various second phases such as γ′ (Ni3Al), γ′ (Ni3Ti), Cr2Ti are found to evolve after the SPS, which are crucial for precipitation strengthening of metal-matrix. Stress-strain plot generated through compression tests were analyzed to assess and equivalent ultimate compression strength (UCS) yield strength (YS). The HESA-3 alloy specimen resulted with better mechanical properties as compared to other two compositions. This is ascribed to higher Al content in the HESA-3, which participated to evolve more amount of γ′ (Ni3Al) precipitates within the matrix. Various strengthening mechanisms were analyzed to correlate mechanical properties of the alloys, especially, the YS. 2023-05-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/21538 Title: REATION OF ORTHOPAEDIC SCAFFOLDS FROM Mg-SUBSTITUTED HYDROXYAPATITE USING 3D PRINTING Authors: Sharma, Divya Abstract: Synthetic hydroxyapatite [HA; Ca10(PO4)6(OH)2] is a well-researched bioceramic material for orthopaedic applications because of its chemical similarity to the inorganic constituent of bone, which accounts for nearly 70% of its mass. Nonetheless, several attempts of cationic and anionic substitutions are continuously being made in order to produce HA with increased compositional resemblance to the biological apatite, hence providing an improved therapeutic potential for bone regeneration. Magnesium (Mg) is a secondary element linked to the bone apatite, but plays a fundamental role in bone remodelling and is known to decrease bone fragility. Zinc (Zn) also demonstrates a favourable effect on the formation of bone, and its deficiency leads to a lessening in bone density & ductility. Therefore in the present study, Mg2+ & Zn2+ substituted HA was synthesized using the wet chemical precipitation route (with Mg as the major dopant) followed by a calcination treatment at various temperatures and dwell periods. The powder samples were characterized using X-Ray Diffractometry (XRD), Field-Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive X-Ray Spectroscopy (EDX), Fourier Transform Infrared Spectroscopy (FTIR), and Thermogravimetric Analysis (TGA) to ascertain the structural, morphological, compositional, molecular, and thermal properties of doped-HA. The material with the most effective synthesis parameters, namely 800ᵒC–calcined (Mg,Zn)–HA, was then selected for the creation of bone-tissue scaffolds. For any material to be 3D printed via extrusion, it should be first converted into a viscous slurry or paste (i.e. ink) and then repeatedly checked for its delicate balance of consistency and flowability. In this project, two different ink systems (non-aqueous & aqueous) were carefully formulated with the selected base material. After multiple trials and errors, thin and thick scaffolds were created using an extrusion-based 3D printer. The basic input models were designed using AutoCAD (2023) and the printer was operated via a personal computer through the DNA Studio software, from where the printing parameters were varied and controlled. The printed and sintered thin scaffolds, prepared from the non-aqueous ink system, were cut into small pieces and characterized for their morphology, elemental composition and biocompatibility. 2023-05-01T00:00:00Z