Faculty Publications
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Item Development and Sliding Wear Behavior of Co-Mo-Cr-Si Cladding through Microwave Heating(Springer editorial@springerplus.com, 2019) Prasad, C.D.; Joladarashi, S.; Ramesh, M.R.; Srinath, M.S.; Channabasappa, B.H.The aim of the present study is to improve the sliding wear resistance of pure titanium grade-2 substrate by developing CoMoCrSi (Tribaloy T400) cladding on it by using microwave hybrid heating technique. The developed cladding is characterized by microstructural features, phase analysis, measurement of microhardness by employing a scanning electron microscope (SEM), X-ray diffraction (XRD) and Vickers microhardness. The cladding and substrate are subjected to sliding wear test against alumina counterpart at elevated temperatures under dry conditions using a pin on disc tribometer. The test is performed by varying normal load and temperatures, whereas sliding speed is maintained constant. The developed clad shown partial melting of CoMoCrSi powders and obtained sound metallurgical bonding with the substrate. The high specific energy of microwave diluted the substrate atoms into cladding region which forms Cr3C2, Co3Ti, and TiC, phases confirmed by phase analysis. The cladding obtained better porosity and microhardness are 1.5 ± 0.2% ?m and 760 ± 35 Hv respectively. The substrate exhibits low microhardness of 182 ± 25 Hv. The cladding exhibits 6 times of lower volume loss and 70.14% of less wear rate with respect to the substrate. The cladding experienced least coefficient of friction is 0.55 compared with the substrate. The worn surfaces of cladding and substrate are examined. The detailed mechanism of wear is discussed in this paper. © 2019, Springer Nature B.V.Item Effect of Mo- and SiC-Reinforced NiCr Microwave Cladding on Microstructure, Mechanical and Wear Properties(Springer, 2023) Sharanabasava, H.; Prasad, C.D.; Ramesh, M.R.A microwave hybrid heating technique was applied to produce the NiCr-Mo-SiC composite cladding on Titan-31. The developed claddings were tested for microstructural features, phase analysis, microhardness, and surface roughness parameters using scanning electron microscopy (SEM), X-ray diffraction (XRD), Vickers Microhardness, and 3D optical profilometers, respectively. Using a static alumina indenter on microwave clads, the linear reciprocator ball on plate wear test was performed. Both friction and wear track metrics have been studied. A dense microstructure without observable holes or fractures has been achieved, together with a homogeneous distribution of hard phases and strong metallurgical bonding. Cladding is typically three times tougher than the underlying metal. Due to the formation of hard carbide phases, which increased hardness and internal lubricity, cladding has a lower coefficient of friction than the substrate. © 2023, The Institution of Engineers (India).Item Characterization and Wear Behavior of NiCrMoSiC Microwave Cladding(Springer, 2024) Sharanabasava, H.; Prasad, C.D.; Ramesh, M.R.A microwave hybrid heating technique has been employed to develop NiCr-Mo-SiC composite cladding on titanium alloy (Grade-5/Ti-6Al-4 V/Titan-31). The developed claddings have been characterized for microstructural features, phase analysis, microhardness measurements, and 3D optical profile parameters by employing scanning electron microscopy, x-ray diffraction, Vickers microhardness tester, and 3D optical profilometer, respectively. Microwave clads have been subjected to linear reciprocator ball on plate wear test with static alumina indenter. Wear track parameters and friction coefficients have been studied. A dense microstructure with uniform distribution of hard phases and good metallurgical bonding with no visible pores and cracks has been obtained. Cladding exhibits nearly 2 times higher hardness than the base alloy. Coefficient of friction studies revealed that higher molybdenum content enhances internal lubricity. © 2023, ASM International.Item Effect of dilution on the microstructure and high-temperature wear resistance of self-lubricating nickel alloy claddings(SAGE Publications Inc., 2024) Gudala, S.; Rokkala, U.; Rao Medabalimi, S.; M.r, R.; Konovalov, K.S.In this study, the impact of substrate dilution on the microstructure and tribological properties of tungsten inert gas (TIG)-deposited self-lubricating claddings was investigated. The dilution of Ti content on cladding increased as the TIG current increased, and the microhardness of the cladding decreased. The content of intermetallic phases such as TiNi and TiC increased with the increase in TIG current. The tribological studies revealed that coating dilution at higher TIG currents has prominent effects on wear behaviour at elevated temperatures. In both clads, the percentage decrease in hardness from higher TIG current to lower TIG current was noted as 31%. The higher dilution of Ti content in the cladding was found to be beneficial in tribological studies performed, especially at higher temperatures (≥400). Also, solid lubricants such as MoS2 and BaF2 encapsulation in the nickel alloy were found to be beneficial at both low and high temperatures. © The Author(s) 2024.Item An Assessment of Coating Thickness on the Microstructure and Mechanical Behavior of IN625 Coating on Ni-Based Superalloy Substrate Deposited by High Velocity Air Fuel Technique(Springer, 2024) Prashanth, M.; Babu, N.; Kumari, S.; Maurya, S.S.; Keshri, A.K.; Cadambi, S.; Nand Gosvami, N.N.; Bhowmik, A.High velocity air fuel (HVAF) technique, an innovative thermal spraying method, has proven more promising than traditional methods for both coating and repairing surfaces. This study focuses on the application of different thicknesses of IN625 superalloy coatings using HVAF to assess its potential for repair and cladding applications. Detailed coating characteristics of IN625 superalloy coating have been examined based on various techniques like nanoindentation, adhesion, micro-tensile and flexural strength of the coated samples. Within the coating, ? (NiCr rich), secondary peaks ?? and carbide phases were identified. Particle deformation under impact and rapid cooling resulting in the formation of ?? precipitates enhances the coating strength. However, the decrease in the adhesion strength with increasing coating thicknesses results from the defects formed at the coating–substrate interface and also influenced by thermal stresses and oxidation. Coating microstructure revealed a strong particle-to-substrate adhesion and varied splat morphologies dependent on degree of particle melting—at higher particle velocities in-flight oxidation of the powders was also minimal. Furthermore, the in-plane cohesive strength of the coating approaches 50% of the wrought alloy's yield strength, attributed to strain hardening from the peening effect. However, decrease in flexural strength as coating thickness increases due to compressive residual stress and coating delamination. The flexural strength of the as-sprayed coating exhibits up to 70% of the flexural strength of the wrought material with thicker coatings exhibiting lower strength. © ASM International 2024.Item Meltpool characteristics, microstructure, and corrosion performance of laser-directed energy deposition cladded 316L SS/X70 steel for oilfield applications(Elsevier Ltd, 2025) Singh, R.K.; Arya, S.B.; Nayak, J.In oilfield pipeline transmission, complex geometries such as elbows, reducers, tees, and orifices face significant corrosion risks, especially in aggressive environments where multiphase turbulent flow and chloride ions cause sharp variations in hydrodynamic parameters. This study explores a laser cladding approach to mitigate internal corrosion in these complex geometries. The Laser-Directed Energy Deposition (L-DED) technique, known for its precision and efficiency, is employed to apply corrosion-resistant 316 L stainless steel (SS) over API X70 steel. Key parameters, including laser power and scan speed, were varied across nine combinations to evaluate their effects on melt pool characteristics, microstructure, and corrosion properties of the clads. Results showed that as laser energy increased (higher power and lower scan speed), melt pool dimensions and heat-affected zone (HAZ) thickness also increased, with clad thickness and HAZ ranging from 172 to 504 µm and 159–272 µm, respectively. Cellular and columnar sub-grain structures were present across all process combinations, with sub-grain size increasing at higher laser energy. A notable variation in chromium content was detected, with the clad produced at 500 W and 720 mm/min exhibiting superior pitting and corrosion resistance. This high-energy clad featured 16.3 % chromium and larger sub-grain sizes, facilitating stable passive film formation during corrosion. The optimized clad demonstrated approximately two orders better corrosion performance than the base X70 steel. © 2025Item 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 dielectric properties and shore hardness of 3D-printed PLA core sandwich disc with functional ceramics surface cladding(KeAi Publishing Communications Ltd., 2025) Senthil Murugan, S.S.; Kattimani, S.; Bharadwaj, N.Poly-lactic acid (PLA), a popular biodegradable polymer for 3D printing, has limited dielectric strength and surface hardness, restricting its use in advanced electronic and structural applications. Existing enhancement methods are often complex or yield inconsistent results. Therefore, a straightforward and scalable approach is necessary to enhance the properties of 3D-printed PLA. This study aims to explore the enhancement of the dielectric and surface hardness of printed PLA discs through surface cladding using nano-functional ceramics and graphene for next-generation multifunctional applications. PLA discs were fabricated via Fused Deposition Modelling (FDM) and subsequently cladded using hand layup with Araldite resin as a binder. Cladding materials included cobalt ferrite (CF), barium titanate (BTO), and graphene (Gr), individually and in combinations. Dielectric properties—capacitance, impedance, dielectric constant, dielectric loss, dissipation factor, and AC conductivity—were analyzed using an impedance analyzer, while surface hardness was measured using a Shore-D durometer. Results revealed that cladding led to uniform particle dispersion with effective surface bonding, improved dielectric performance, and significantly enhanced surface hardness. The CF + BTO + Gr combination exhibited superior dielectric behaviour, balancing high polarization with low energy dissipation, while BTO contributed to an enhanced dielectric constant and graphene improved charge transfer. All cladded samples showed frequency-dependent dielectric responses, with stability at higher frequencies. The highest surface hardness was achieved with CF + BTO, attributed to rigid, uniform reinforcement. © 2025 The Authors. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltdé This is an open access article under the CC BY-NC-ND license. http://creativecommons.org/licenses/by-nc-nd/4.0/Item Enhancing X70 steel durability: Tribo-corrosion resistance through protective laser cladding(Elsevier Ltd, 2025) Singh, R.K.; Bhole, K.B.; Arya, S.B.; Nayak, J.This study investigates the effects of laser surface cladding (L-DED technique) on the tribo-corrosion behavior of API X70 steel in the simulated Indian oilfield water. Using optimized parameters, 500 W laser power, 720 mm/min scan speed, and 4.2 g/min powder feed rate, 316 L SS was successfully clad onto X70 steel without any significant defects. The results showed a significant improvement in corrosion resistance, with the SS clad exhibiting a corrosion rate of 131.3 ?m/year at 20 N, compared to 287.9 ?m/year for the X70 substrate. SEM and 3D profilometer analyses revealed a more stable tribo-layer on the SS clad, with less damage and debris accumulation. These findings highlight the potential of laser cladding to enhance the durability and lifespan of steel components. © 2025 Elsevier Ltd