Faculty Publications
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Item Wetting behaviour of a Green cutting fluid (GCF); influence of surface roughness and surface energy of AA5052, Ti6Al4V and EN31(Elsevier Ltd, 2022) Edachery, V.; Ravi, S.; Badiuddin, A.F.; Tomy, A.; Kailas, S.V.; Suvin, P.S.Green Cutting fluids (GCFs) are biodegradable and eco-friendly alternatives that can be employed in metalworking processes. They facilitate better tool service life and surface quality by removing the heat built, reducing coefficients of friction at tool-chip, and tool-work interfaces, flushing away the chip and preventing the formation of Built-up edges (BUEs). Conventionally, mineral oil (MO) based CFs are used, which can cause serious health hazards in humans as well as negatively impact the environment. Sustainable Green-cutting fluids (GCF) were found to be the solution for reducing the issues raised by the MO-based cutting fluids. The GCF used in the present study was synthesized using coconut oil (Cocos Nucifera) as the base, which is a clean, bio-degradable and eco-friendly substitute for petroleum-based mineral oils. This work is focused on experimentally determining the effectiveness of green cutting fluids on surfaces of (Aluminium)AA5052, (Titanium alloy)Ti6AL4V and Steel(EN31) with various surface topographies. In order to do so, the wetting properties were measured by a stable contact angle θ between the solid–liquid surface and the vapour-liquid interface. Wettability responses from the roughened surfaces in the range of 0.06–2.1 µm was evaluated using a profilometer and contact angle goniometer. Results show that the wetting characteristics of GCF are comparable to that of the MO-based CFs and can be a viable alternative, thus reducing the adverse effects on the environment. In conclusion, this study shows the potential of GCFas an alternative to MO-based cutting fluids used in machining operations in the manufacturing industries. © 2022Item Micro-tribological Characteristics of Ti6Al4V Alloy Subjected to Shot Blasting Surface Treatment Process(Springer, 2023) John, A.; Showket, J.; Joseph Babu, K.; Edachery, V.; Suvin, P.S.Ti6Al4V has remarkable mechanical and physical qualities, but its usage in many applications is constrained by its inferior tribological properties. In this study, Ti6Al4V was shot-blasted with aluminum oxide to enhance the surface hardness and reduce the real area of contact, thereby improving the tribological properties of the metal surface. The data obtained from reciprocating tribometer, optical profilometer, SEM, and EPMA infer considerable improvement in tribological properties and impart information on wear mechanisms attributing to an increase in wear resistance up to 76%. © 2023, The Indian Institute of Metals - IIM.Item Enhanced tribological performance of laser directed energy deposited Inconel 625 achieved through laser surface remelting(Elsevier B.V., 2024) Praharaj, A.K.; Chaurasia, J.K.; Gurugubelli, R.C.; Bontha, S.; Suvin, P.S.Inconel 625 (IN625) is an essential material for the manufacture of turbine blades and seals, aircraft ducting systems, engine components, and pressure valves. Laser Directed Energy Deposition (LDED) process has shown the potential to fabricate IN625 parts with superior mechanical properties and higher corrosion resistance when compared to those fabricated using conventional manufacturing techniques. However, the poor surface quality limits the practical application of LDED fabricated parts, especially in sectors that demand high tribological performance. To this end, this study focuses on improving the surface quality and tribological performance of LDED fabricated IN625 components using Laser Surface Remelting (LSR) as a postprocessing operation. The tribological performance was evaluated using a linear reciprocating ball-on-flat wear test setup. The surface roughness, remelting depth (RD), microstructure, hardness, and tribological performance (coefficient of friction and wear rate) of the remelted (RM) samples were compared with that of as-deposited (AD) samples. Microstructural characterization revealed that LSR resulted in grain refinement, reduced dendrite size, and primary dendritic arm spacing (PDAS). Laser scanning speed effects RD, dendrite size and PDAS via its effect on cooling rates. SEM + EDS analysis confirmed the presence of Laves phase in both AD and RM samples. XRD analysis of RM samples showed an increase in the amount of Laves phase. The refinement in microstructural features and the increased amount of Laves phase among the RM samples led to improvement in microhardness when compared to AD samples. Wear test results revealed a reduction in the coefficient of friction (COF) and wear rate after LSR with wear mechanism being either abrasive or delamination. Reduction in the size of dendrites and refinement in grain size are attributed to the enhanced tribological performance after LSR. © 2023 Elsevier B.V.Item Effect of Heat Treatment on Microstructure and Dry Sliding Wear Behavior of Laser Directed Energy Deposited Inconel 625(Springer, 2025) Praharaj, A.K.; Chaurasia, J.K.; Suvin, P.S.; Narayanan, J.A.; Paul, C.P.; Balla, V.K.; Chakrapani, S.K.; Bontha, S.Laser directed energy deposition (LDED) is a promising technology for manufacturing and repair of Inconel 625 (IN625) components used in critical sectors requiring enhanced tribological performance due to harsh operating environments. Hence, the current work focuses on the evaluation of the tribological performance of LDED-built IN625 with the implementation of different heat treatment methods, i.e., solution treatment (ST), direct aging (AG), and solution treatment + aging (ST + AG). A detailed microstructural analysis, hardness, and wear testing were performed for the as-deposited (AD) and heat-treated (HT) samples, and the results were compared. The analysis revealed coarser grains in the case of ST and ST + AG samples, whereas finer grains for AD and AG samples, indicating grain coarsening after solution treatment. Further, the brittle laves phase gets dissolved after ST, whereas the AG and ST + AG samples resulted in the precipitation of metal carbides and strengthening phases. The microhardness of the ST sample (193.2 HV) was lower compared to the AD (211.6 HV) sample, whereas the AG and ST + AG samples exhibited 25.6 and 9.3% higher hardness than the AD sample. Considering tribological performance, the AG sample illustrated a maximum reduction of 61.4% in the coefficient of friction (COF) and 36.5% in wear rate when compared to the AD sample. This could be attributed to the presence of finer grains and strengthening phases. © ASM International 2025.Item Investigation on the tribological performance of protic ionic liquid as an additive in PEG200 for steel–steel contact(SAGE Publications Ltd, 2025) Depu Kumar Patro, B.D.K.; Suvin, P.S.Ionic liquids (ILs) offer multifunctional capabilities as lubricant additives. However, many conventional ILs contain moisture-sensitive halogen-based anions that may hydrolyze to form corrosive halogen acids, leading to surface degradation. This study explored halogen-free, amine-based protic ionic liquids (PILs) as additives in polar base oil polyethylene glycol (PEG200). Anti-corrosion tests revealed that incorporating PILs into PEG200 significantly improves corrosion resistance. Lubrication tests performed at various PIL concentrations showed that the blend containing 5wt% PIL exhibited the best performance, reducing the friction coefficient by 26.12% and wear volume by 90.61% compared to neat PEG200. Spectroscopic analysis confirms the formation of a protective tribofilm within the wear tracks, consisting of oxy-organic compounds and metal oxides such as FeOOH, Fe2O3and Fe3O4. This tribofilm minimizes direct contact between sliding surfaces and facilitates effective lubrication. These findings demonstrate the potential of amine-based PILs as efficient and environmentally friendly additives for PEG-based lubricants. © IMechE 2025Item Enhancing the tribological performance of PEG 200 using oil-miscible deep eutectic solvents as lubricant additives(Elsevier Ltd, 2025) Kumar Patro, B.D.; Suvin, P.S.This study investigated a comprehensive assessment of the tribological and anti-corrosion behavior of a novel, halogen-free, and oil-miscible deep eutectic solvent (DES) additive in PEG 200. The DES, referred to as DOA, was synthesized from naturally derived L-Proline and oxalic acid and exhibited good miscibility with PEG 200 due to its polar functional groups. Corrosion tests, including electrochemical and copper strip experiments, confirmed that the DOA/PEG blends maintained consistent anti-corrosion performance. Tribological evaluations revealed that incorporating 3 wt% DOA resulted in a 30 % reduction in the coefficient of friction and a 60.3 % decrease in wear volume compared to PEG 200 alone. ANOVA analysis validated the statistical significance (p < 0.05) of DOA concentration on friction and wear responses, confirming a synergistic effect between DOA and PEG 200. These improvements are attributed to strong interfacial interactions and the formation of a protective tribo-chemical film. Surface characterization identified the presence of hydrocarbons (CxHy), iron oxides, and FeOOH layers, which improved lubrication in the steel–steel contact pair. These findings highlight the potential of DOA as a promising green additive for advancing sustainable lubrication technologies. © 2025 Elsevier Ltd