Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
18 results
Search Results
Item Developing partially oxidized NiCr coatings using the combined flame spray and plasma spray process for improved wear behaviour at high temperature(Elsevier Ltd, 2021) Medabalimi, S.R.; Ramesh, M.R.; Kadoli, R.The powders of NiCrBSiFe and NiCr are partially oxidized using a flame spray process and are deposited on MDN321 steel substrate using a plasma spray process. The effect of partial oxidization on microstructure, microhardness, density, bond strength, and porosity of the coatings is analyzed. The friction and wear behaviour of the coatings was assessed using a pin-on-disc tribometer by varying loads (10, 20 and 30 N), sliding velocities (1, 2 m/s) and temperatures (RT, 200, 400 and 600 °C). Worn surfaces of NiCrBSiFe and NiCr coatings consist of oxide phases of SiO2, NiO, Cr2O3 and NiCr2O4 at elevated temperatures. These phases contributed to reducing the wear rate by five folds in coated steels compared to uncoated steels at 600 °C. The wear rate in coating decreases with an increase in temperature. The coefficient of friction was reduced gradually with the temperature in coatings and substrate. The wear rate coefficient of NiCr coating was 1.7 times higher than the NiCrBSiFe coating. © 2021 Elsevier B.V.Item Friction and wear study of graphite and bronze filled epoxy matrix composites(Elsevier Ltd, 2022) Patil, N.; Krishna, P.The composite material is made of different materials. It retains the advantages of the original material and reflects combined characteristics of all the constituents. Polymer matrix composites are popular in the recent industrial applications. Friction and wear governs the tribological aspects of polymer composites. This paper revel the experimental study of friction and wears behavior of epoxy composites filled with bronze and graphite fillers as per ASTM standards. Three compositions were studied and it was found that composition ‘A’ has lowest coefficient of friction (0.281) whereas composition ‘C’ has highest coefficient of friction (0.325). The composition ‘A’ has lowest wear rate of 0.5 μm/s and composition ‘C’ showed highest wear rate of 3.25 μm/s. Use of graphite and bronze along with epoxy exhibited formation of lubricating layer and enhanced friction and wear behavior of the composites. © 2021Item Optimization of tribological parameters to enhance wear and friction properties of Ti6Al4V alloy using Taguchi method(SAGE Publications Ltd, 2022) Sreesha, R.B.; Chandraker, S.; Kumar, D.The present study is an endeavor to investigate the wear and friction behavior of Ti6Al4V against alumina (Al2O3) using a pin-on-disc tribometer at room temperature. The tests were performed for a given range of loads (10–90 N) and sliding velocities (0.5–4 m/s) for a sliding distance of 3000 m. The wear rate increased continuously with load and showed transition behavior with respect to the sliding velocity. Minimum friction was observed at the intermediate sliding velocities. Using the Taguchi tool, it was found that the load influenced the wear rate more significantly than the sliding velocity and the behavior was the opposite for the coefficient of friction. A wear model was predicted using regression, and subsequent confirmatory tests were carried out to validate the same. The ex-situ characterization of both worn-out surfaces and wear debris was conducted using Scanning Electron Microscope (SEM) along with the Energy Dispersion Spectroscopy (EDS) to study the surface morphology and level of oxidation, respectively. The wear mechanism was found to be a combination of adhesion, abrasion, oxidation, and delamination wear. The distinct lower wear rates at higher loads and velocities were attributed to the formation of Ti8O15 revealed by the X-ray diffraction (XRD) study. © IMechE 2022.Item Effect of Wollastonite Filler on the Experimental and Microstructural Analysis of Epoxy Composite Reinforced with E-glass Fibre(Springer, 2022) Lokesh, K.S.; Pinto, T.; Shrinivasa Mayya, D.; Shanmugam, B.K.; Panduranga, B.P.; Hanumanthappa, H.; Mohanraj, G.T.In the present study, the polymer composite was produced with epoxy, E-glass and wollastonite as the matrix, reinforcement and filler material, respectively. The present study investigates the effect of the filler material on the mechanical performance of developed composite specimens. The reinforcement material selected was woven and chopped-type fibre material. The filler material composition in the woven and chopped-type specimens was individually varied with 0%, 1%, 3%, 5% and 7%. The specimen was subject to mechanical testing, viz., tensile and flexural strength tests. Further, the wear rate of the normal specimen was tested to 5, 10 and 15 min. Additionally, the specimen was subjected to SEM (scanning electron microscope) analysis after attaining fracture for each study. The results showed that the specimen with 1% filler material had better tensile strength. It was also found that the flexural strength was good and was increasing with the filler material. The wear rate was reduced with the increase in filler material composition in the specimen. The results show that the woven fabric specimen shows better mechanical performance than the chopped specimen. © 2022, The Institution of Engineers (India).Item Effect of thermal expansion on the high temperature wear resistance of Ni-20%Cr detonation spray coating on IN718 substrate(Elsevier B.V., 2023) Purushotham, N.; Parthasarathi, N.L.; Babu, P.S.; Govindarajan, G.; Rajasekaran, B.The temperature-dependent materials properties on the dry sliding wear resistance of the detonation sprayed Ni-20%Cr coating have been studied. In-situ high-temperature X-ray diffraction (HT-XRD) was used to investigate high-temperature properties such as stress relieving, recrystallization, and thermal expansion. The dry sliding wear test was performed by using a ball-on-disc tribometer by sliding velocities (0.1 m/s), varying loads (6 N and 10 N), and temperatures (25 °C and 850 °C) against alumina (Al2O3) ball. The phase evolution, thermal expansion, crystallite size, and lattice strain were determined by the Williamson-Hall method. Field emission scanning electron microscopy and a non-contact optical profilometer was used to characterize the wear scar and calculate the wear rate. The wear test results demonstrated that the as-deposited coatings coefficient of friction (CoF) and wear rate (ω) continuously decreased as the temperature increased. The primary wear mechanism changed from abrasive and surface fatigue to adhesive and oxidative wear. The impact of stress relieving, recrystallization, and forming a composite tribolayer (Cr2O3, NiO) at elevated temperatures reduced the friction and enhanced the wear resistance. The effect of stress relieving, recrystallization, thermal expansion, and oxidation on the wear resistance of the coating has been discussed with a suitable mechanism. © 2023 Elsevier B.V.Item Effect of Microwave Hybrid Heating on High-Temperature Adhesive Wear Behavior of High-Velocity Oxygen Fuel-Sprayed WC-CrC-Ni and WC-Co/NiCrFeSiB Coatings(Springer, 2023) Medabalimi, S.; Ananthu, M.R.; Gudala, S.; Ramesh, M.R.HVOF-processed coatings are chemically inhomogeneous and are not metallurgically bonded to the substrate. As a result, components coated with HVOF experience considerable material degradation during sliding wear. Microwave hybrid heating (MHH) is a novel surface modification technique for modifying the as-sprayed properties of the coating. Hence, this paper investigates and compares the wear and frictional behavior of HVOF as-sprayed coatings against MHH samples of WC-CrC-Ni and WC-Co/NiCrFeSiB coatings at elevated temperatures. MHH had a significant impact on wear rate and coefficient of friction by optimizing the porosity, integrated oxide phases and intersplat cohesion strength of the coatings. A modified domestic oven was used to perform MHH on HVOF-coated samples for 5 min at 1200 °C. Wear tests were performed using a pin-on-disk tribometer from room temperature to 200, 400, and 600 °C with Al2O3 disk as a counterface. SEM/EDS and XRD were utilized to examine the microstructural characterization of the coatings and substrate. Both the coatings showed higher wear resistance than the substrate at all temperatures. The WC-Co/NiCrFeSiB coating produced an oxide layer on the worn surfaces and integrated WC, CoWO4, and Fe2SiO4 splats, enhancing wear resistance. The MHH WC-CrC-Ni coating formed Cr2O3 and NiWO4 phases on the worn surfaces, increasing the intersplat cohesion strength between matrix and carbide splats, lowering the overall wear rate. After MHH, the wear rate of a substrate and WC-CrC-Ni coating was 3.5 and 1.12 times more at room temperature and 8.07 and 2.92 times more at 600 °C than WC-Co/NiCrFeSiB coating. © 2022, ASM International.Item High temperature sliding wear behavior of detonation sprayed Ni-5wt%Al coating(Elsevier Ltd, 2023) N, P.; N.l, P.; P, S.B.; G, S.; Rajasekaran, R.The tribological behavior of detonation (DSC) sprayed Ni-5%wtAl coatings at room temperature (25 °C) and elevated temperature (850 °C) has been studied in this work. Dry sliding wear experiments were done by using alumina (Al2O3) ball-on-disc tribometer. FESEM-EDS and a non-contact 3D profilometer microanalysis were used to evaluate the worn scar and wear rate and identify the wear mechanism. X-ray diffraction (XRD) investigation indicated that the Ni-5wt%Al coating predominantly consists of γ-Ni phases at 25 °C and 850 °C conditions. The phase evolution, thermal expansion, crystallite size, and lattice strain were evaluated using in-situ high-temperature X-ray diffraction (HT-XRD). The crystallite size (D) and lattice strain (ε) were determined by Williamson-Hall analysis using a uniform deformation model (UDM), employing X-ray peak profile analysis (XPPA). In high-temperature conditions, the thermal expansion mismatch between the coating and substrate is negligible, with reduced spallation and cracking at the interface. The findings of the wear tests revealed that as the temperature increased, the coefficient of friction (CoF) and wear rate (ω) significantly decreased as the wear mechanism changed from abrasive to adhesive. The improvement of wear resistance of Ni-5wt%Al coating at high temperatures has been evaluated and discussed from the perspective of thermal expansion and tribo-layer formation. © 2023 Elsevier B.V.Item Scratch and wear resistance of interstitial-free steel subjected to severe shot peening(SAGE Publications Inc., 2024) Sahoo, B.; Bhat K, U.; Rao, M.Surface integrity in terms of scratch and wear resistance is the major concern of any engineering component, which is attributed to most of the surface damages. A popular way of improving such behaviours is the mechanical treatment of the surface. The current investigation studied the improvement of scratch and wear properties by performing shot peening on the Ti–Nb stabilised interstitial free steel, a popular choice in automotive industries. The samples were shot-peened at different coverages. It was found that the shot-peened samples showed a superior scratch and wear behaviour as compared to as-received samples. The scratch hardness was improved by 2.4 times, the wear volume was decreased by 59.6%, and the wear rate was minimal for the 2000% peened sample. © Institute of Materials, Minerals and Mining 2024.Item Effects of Addition of Graphite on the Tribological Behaviour of Al7075-SiC Hybrid Composites Using Design of Experiments(Springer Science and Business Media Deutschland GmbH, 2024) Gudipalli, K.R.V.; Chapke, Y.; Hareesha, H.; Doddamani, S.Despite the widespread use of Al7075-SiC composites in various engineering applications, their tribological performance remains a subject of interest due to challenges related to friction and wear. This study addresses the need for improved lubrication in such composites by investigating the potential of Al7075-SiC/Graphite hybrid materials. The incorporation of graphite particles, up to 9% by weight, aims to enhance the self-lubricating properties of these composites. Stir casting is employed to fabricate specimens with varying graphite content (3–9% by weight), followed by comprehensive tribological assessments under dry sliding conditions. Factors including sliding distance, load, and graphite composition are systematically evaluated using Taguchi’s optimization techniques, including design of experiments, ANOVA, and regression analyses. Results reveal that the addition of 9% graphite content notably reduces both the coefficient of friction and wear rate. According to the data, sliding distance significantly impacts wear behaviour, followed by the applied load. In contrast, the composition has a 77% impact on the coefficient of friction than load, while the sliding distance has a relatively small impact. As a result, the Al7075-SiC/Graphite composite material demonstrated its suitability as a self-lubricating substance. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.Item Elevated temperature wear and friction performance of WC-CoCr/Mo and WC-Co/NiCr/Mo coated Ti-6Al-4V alloy(Elsevier Inc., 2024) Behera, N.; Ramesh, M.R.; Rahman, M.R.The effect of adding Mo to WC-based coatings on the microstructure and dry sliding wear performance at elevated temperatures is investigated. The WC-based coatings are deposited using a high-velocity oxy-fuel process on the titanium-31 substrate. The coating was characterized by microstructure, microhardness, porosity, surface roughness, density, and bond strength. The wear and friction behavior of coatings was evaluated using a ball-on disc tribometer at temperatures of 200, 400, 600, and 800 °C and loads of 20 and 30 N. SEM-EDS and an optical profilometer were utilized to evaluate the wear rate and mechanism. The microhardness and bond strength of WC-CoCr/10%Mo coating is more than that of WC-Co/20%NiCr/10%Mo coatings. The WC-CoCr, WC-CoCr/10%Mo, and WC-Co/20%NiCr/10%Mo coatings exhibited decreasing wear rates up to 600 °C, transitioning to an increase at 800 °C. The oxide phases of CoWO4 WO3 MoO3, CoMoO4, and NiMoO4, formed at 600 °C, aid in reducing the rate of wear and friction coefficient. However, the wear rate slightly increased at 800 °C due to vigorous oxidation and softness of coatings. The friction coefficient of WC-CoCr, WC-CoCr/10%Mo, and WC-Co/20%NiCr/10%Mo coating decreases with increasing temperatures due to the lubricating properties of oxide phases on the worn surface. The WC-CoCr/10%Mo coating demonstrates a lower friction and wear rate than the WC-CoCr and WC-Co/20%NiCr/10%Mo coating. At 200 °C, the predominant wear mechanisms were abrasive and fatigue wear, while at 800 °C, oxidative wear, abrasive wear, and adhesive wear were observed. © 2024