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 High temperature tribological studies of cold sprayed nickel based alloy on low carbon steels(Elsevier Ltd, 2019) Padmini, B.V.; Mathapati, M.; Niranjan, H.B.; Sampathkumaran, P.; Seetharamu, S.; Ramesh, M.R.; Mohan, N.The boiler steels of grades SAE213 T11 and T22, find extensive applications in heat exchanger tubes, paper and pulp, chemical industries and refineries. Further, these steels are also used in shafts, cylinders, bearings, and in automotive transmission parts and these aspects are less explored. They experience low wear life in specific components, both at room and slightly higher temperature regimes. In order to protect them from these damages, coatings are deployed involving many techniques like HVOF, Plasma spray, Cold spray etc. so that the life of the components get extended. In cold spray coatings, the powders are fed at very high impact velocities of up to 1200 m/s on the substrate and undergo plastic deformation during the impact. There is no oxidation of the powder takes place during the process, as the coating is done at very less temperature and this is one of the lead characteristic of cold spray technique. This particular work mainly focuses on evaluating the tribological behaviour of nickel based super alloy powder on T11 and T22 low alloy steels by cold spray method, using pin on disc machine both at room temperature as well as at 200, 300 and 400 °C. The associated tests such as hardness, porosity, and microstructure have been undertaken to support the wear data. The wear damage assessment has been carried out using scanning electron microscope to arrive at the mechanism and also to give credence to the wear data. © 2019 Elsevier Ltd.Item HVOF sprayed Ni3Ti and Ni3Ti+(Cr3C2+20NiCr) coatings: Microstructure, microhardness and oxidation behaviour(Elsevier Ltd, 2018) Reddy, N.C.; Kumar, B.S.A.; Reddappa, H.N.; Ramesh, M.R.; Koppad, P.G.; Kord, S.This paper reports the development of Ni3Ti and Ni3Ti+(Cr3C2+20NiCr) coatings on AISI 420 stainless steel (MDN-420) and titanium alloy ASTM B265 (Ti-15) by HVOF technique. Microstructure, microhardness and high temperature oxidation behaviour of coatings were investigated. Microstructure of coatings was dense and displayed layers depicting lamellar structure. The microhardness of coatings was significantly higher than that of substrate owing to higher density and cohesive strength between individual splats of coating materials. Cyclic oxidation studies conducted on Ni3Ti and Ni3Ti+(Cr3C2+20NiCr) coatings showed oxide scale was composed of various oxides like NiO, NiCr2O4 and Cr2O3 phases. The formation of compact and protective NiO phase in case of Ni3Ti coatings; NiO and Cr2O3 phases in Ni3Ti+(Cr3C2+20NiCr) coatings stabilised the weight gain exhibited slow oxidation rate at higher temperatures. © 2017 Elsevier B.V.Item High-Temperature Solid-Particle Erosion Behaviour of Plasma-Sprayed Fe17Cr2Ni0.18C/Cenosphere-Based Composite Coating(Springer Science and Business Media Deutschland GmbH, 2021) Hanumanthlal, S.; Siddaraju, C.; Ramesh, M.R.The present investigation deals to improve the solid-particle erosion resistance of boiler steel material. FeCrNiC and FeCrNiC with 5, 10 and 15wt.% cenosphere composite coatings were deposited on A387 Grade 22 steel using plasma spray technique. Powder and as-sprayed coatings are characterized using Scanning Electron Microscope (SEM), X-ray diffraction to study the surface morphology and cross section to study the nature of coatings deposited. Microhardness and adhesion strength of the coatings are evaluated. High-temperature solid-particle erosion behavior of these coating is evaluated at 300 ºC and 600 ºC at different impact angles. FeCrNiC + 15%Cenosphere designates higher hardness and adhesion strength. Convention weight change method cannot be used to validate the erosion performance due to undesirable variation. Optical profiler is used to determine erosion volume loss. The FeCrNiC coatings with the addition of cenospheres showed better erosion resistance than as-sprayed FeCrNiC and substrate. FeCrNiC + 10%Cenosphere coating shows the highest erosion resistance as compared to other coatings and substrate. Further increase in cenosphere percentage leads to reduction in erosion resistance due to predominant brittle fracture. High-temperature erosion is a concurrent erosion–oxidation process which shows combination of ductile and brittle erosion mechanism. © 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG.Item Development of Self-lubricating Nickel Based Composite Clad using Microwave Heating in Improving Resistance to Wear at Elevated Temperatures(Korean Institute of Metals and Materials, 2022) Gudala, S.; Ramesh, M.R.; Srinath, M.S.This paper reports on a study of the high-temperature tribological performance of self-lubricating nickel-based composite clad. A porous and crack free clad containing matrix, reinforcement, and lubricant phase is developed on titanium 31 alloy using microwave irradiation. The microstructure of both NiCrSiB/WC and NiCrSiB/WC/Ag/BaF2 clad revealed very good metallurgical bonding with the substrate. The average microhardness of NiCrSiB/WC and NiCrSiB/WC/Ag/BaF2 clad is 710.58 HV and 650.25 HV respectively, is comparatively higher than the titanium 31 substrate (320 HV). The addition of Ag and BaF2 solid lubricants in the clad endowing clad to operate at a broad temperature range. Compared with the NiCrSiB/WC clad, solid lubricant encapsulate clad has shown very low friction coefficient and wear rates. The sliding wear characteristics of the clad were investigated by varying load and temperatures. The results revealed that oxide phases (NiO and Cr3O) and lubricant phases (Ag and BaWO4) formed at low and high temperatures are adequate to reduce delamination and material loss. Graphical abstract: [Figure not available: see fulltext.] © 2021, The Korean Institute of Metals and Materials.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