Faculty Publications
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Item Influence of Impact Angle and Temperature on Solid Particle Erosion Behavior of Titanium-31(Springer Nature, 2024) Behera, N.; Chandramouli, T.V.; Aprameya, C.R.; Ramesh, M.R.The present work shows the effects of impact angles and temperatures on volumetric erosion loss of titanium-31 alloy. An erosion tester was used to perform the erosion tests with temperatures (200, 400, 600, and 800 °C) and impact angles (30°, 60°, and 90°). The alumina particles (Al2O3) are used as an erodent particle with an average particle size of 50 μm. The microhardness, porosity, and surface roughness of titanium-31 alloy are evalu-ated. SEM/EDS and XRD were used to analyze tita-nium-31 alloy eroded samples. The weight loss method and 3D profilometer determined the volumetric erosion loss. The microhardness of titanium-31 alloy is found to be 337 ± 15HV0.3. The Volumetric erosion loss of tita-nium-31 alloy increased with increasing temperatures from 200 to 800 °C, whereas decreased with increasing impact angle from 30° to 90° for all temperatures. The volumetric erosion loss is higher at a 30° impact angle and lower at a 90° impact angle for all temperatures. As a result, titanium-31 alloy shows the ductile erosion mode for all temperatures. The volumetric erosion loss at 30° impact angles is due to micro-cutting and plough-ing, whereas deep crater, groove, and raised lips are for 90° impact angles. The results of volumetric erosion loss obtained by the weight loss method exhibit a good cor-relation with a 3D optical profilometer. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2024.Item DRY SLIDING WEAR RESISTANCE OF HVOF SPRAYED IRON-BASED COMPOSITE COATINGS ALLOYED WITH CARBIDES ACROSS VARIOUS TEMPERATURES(American Society of Mechanical Engineers (ASME), 2025) Aprameya, C.R.; Chandramouli, T.V.; Joladarashi, S.; Ramesh, M.R.Maraging steel, widely used in aerospace applications for its remarkable strength and toughness, often faces challenges related to surface wear resistance in high-stress environments. This study investigates the dry sliding wear performance of Fe-based coatings allied with carbides, applied onto maraging 250-grade steel using the High-Velocity Oxy-Fuel (HVOF) thermal spraying surface modification technique. The objective is to assess the tribological behavior of these as-sprayed samples under varying circumstances. Dry wear tests were conducted at both room temperature and 300 °C under a normal load of 30 N. The study comprehensively investigates the factors influencing wear resistance by analysing key microstructural and mechanical properties, including microhardness, porosity, and bond strength. Advanced characterisation techniques were employed, including Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS) for surface morphology and elemental analysis and X-ray diffraction (XRD) for phase identification. A 3D profilometer was utilised to measure wear scar volume and quantify volumetric wear loss precisely. At room temperature, abrasive wear dominated, with ploughing and furrows as primary material removal mechanisms. Notably, the 316L-20%Cr3C2 coating exhibited better wear resistance compared to the 17-4ph-20%Cr3C2 coating. This enhanced performance is attributed to the carbide reinforcements, which significantly increased hardness and improved wear resistance under high temperatures. These findings emphasize the potential of carbide-reinforced HVOF coatings as an effective surface engineering approach for enhancing the performance and service life of maraging steel under harsh operational conditions, particularly those involving high temperatures and severe wear. © © 2025 by ASME.Item Dry linear reciprocating wear behavior of molybdenum-reinforced SS316 laser claddings deposited by laser directed energy deposition(Elsevier B.V., 2025) Aprameya, C.R.; Joladarashi, S.; Ramesh, M.R.This study aims to improve the wear resistance and extend the service life of AISI 304 stainless steel, which is extensively used in marine impellers, chemical reactors, and industrial mixers. The improvement is achieved using Laser Directed Energy Deposition (LDED) cladding of molybdenum-reinforced SS316 powders onto AISI 304 stainless steel. Dry linear reciprocating wear experiments were conducted on the claddings of SS316 and Mo (10 and 20 wt%) reinforced SS316 at ambient temperature under varying normal loads of 10 N and 20 N. The worn scar was examined using a 3D non-contacting profilometer. Microstructure and wear mechanism were analyzed using Field emission scanning electron microscopy (FE-SEM). The micro-hardness test revealed that the hardness of SS316 + 20% Mo claddings was nearly 1.10 and 1.41 times higher than that of SS316 + 10% Mo, and SS316 claddings respectively. The study also revealed that SS316 + 20% Mo Cladding provides better wear resistance and lower Coefficient of Friction (CoF) compared to SS316 + 10% Mo and SS316 claddings, due to the formation of the hard carbide phases like MoC and Fe2C during LDED process. The wear analysis indicated the presence of both abrasive and adhesive wear mechanisms, especially under higher load conditions. At a 20 N load, the SS316 + 20% Mo cladding demonstrated a 2.55-fold reduction in wear rate compared to SS316. © 2024 The AuthorsItem Surface enhancement of SS304 for high-temperature wear resistance using laser cladded Mo-alloyed stellite 6 coatings(Elsevier B.V., 2025) Aprameya, C.R.; Joladarashi, S.; Ramesh, M.R.Severe wear often limits the high-temperature durability of SS304 components, necessitating the development of surface-engineered solutions. In this investigation, Mo-reinforced Stellite 6 claddings were developed using Laser Directed Energy Deposition (L-DED) to provide enhanced surface protection. Claddings with (3, 6, and 9 wt%) Mo reinforcement enhanced hardness by 2.9, 3.1, and 3.3 times, respectively, compared to the SS304 substrate. This improvement is attributed to Mo-induced solid solution strengthening and the formation of hard intermetallic phases. Dry sliding wear tests were conducted at RT and 600 °C under (10 and 20 N) loads. Wear characterisation of the clads was performed using OM, XRD, FE-SEM, EDX, and Raman spectroscopy. At RT, claddings primarily exhibited abrasive wear with minor plastic deformation. However, at 600 °C, the wear mechanism evolved into a combination of severe adhesive, oxidative, abrasive, and plastic deformation modes, with oxidative wear governing the tribological behavior. Stellite 6 with 9 wt% Mo clads exhibited better tribological performance than the other two variants, owing to the development of oxide glaze layers of Cr2O3, NiO, CoO2, and Co3O4. Enhanced performance of the claddings is attributed to solid solution strengthening, Cr-rich carbide formation, increased dislocation density, and the L-DED technology enabling refined microstructure and strong metallurgical bonding. These findings highlight the potential for further advancements in Mo-reinforced Stellite 6 L-DED claddings for high-temperature wear applications. © 2025 Elsevier B.V.Item Investigation of high-temperature wear behaviour of Mo-alloyed SS316 laser claddings deposited by LDED for heat exchanger tubes(Elsevier B.V., 2025) Aprameya, C.R.; Joladarashi, S.; Ramesh, M.R.Pronounced surface degradation due to high-temperature wear remains a significant challenge for SS304-based components, particularly in heat exchanger tubes that endure harsh loading conditions. SS316 and Mo-reinforced composite claddings (10 and 20 wt%) were developed on SS304 substrate through laser direct energy deposition (LDED) to enhance high-temperature wear resistance. This research evaluated the high-temperature wear performance of these composite claddings using ball-on-flat tribological testing under applied loads of 10 and 20 N at 400°C. Microstructural evolution, wear mechanisms, and oxide formation were comprehensively analyzed using FE-SEM, XRD, EDS, and Raman spectroscopy, while surface topography was assessed with 3D non-contact profilometry. Compared to SS316 clads, the SS316 with 10 wt% Mo clads exhibited increased hardness and facilitated the formation of stable oxide films, leading to a shift from severe adhesive wear to a more stable oxidative wear mechanism. The development of protective glaze layers, including Fe2O3, Fe3O4, and MoO3 in the SS316+20 wt% Mo composite clads resulted in reduced plastic deformation, yielding smoother wear scars and lower wear rates. The SS316 + 20 wt% Mo composite clads demonstrated enhanced wear resistance, achieving a 60 % reduction in wear rate compared to SS316 clads and a 29 % improvement over the SS316+10 wt% Mo composite clads. This study highlights the potential of Mo-reinforced SS316 claddings deposited via LDED for high-temperature industrial applications. © 2025 The Authors