Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
11 results
Search Results
Item Metastable microstructures at the interface between AISI 321 steel and molten aluminum during hot-dip aluminizing(Elsevier B.V., 2018) Huilgol, P.; Udupa, K.R.; Bhat, K.U.The microstructure at the interface between AISI 321 stainless steel and molten aluminum was investigated which occurs during the process of hot-dip aluminizing. Microstructural characterization was carried out by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The study revealed the formation of metastable FeAlm and multiple twinned Al13Fe4 phases at the interface between steel and aluminum. Multiple twinned Al13Fe4 phase exhibits pseudo tenfold electron diffraction pattern. Another metastable phase Al3(NiFe) with an orthorhombic structure was formed as one of the eutectic phase mixture in the solidified aluminum topcoat. The Al3(NiFe) phase in the eutectic shares crystallographic orientation relationship with the Al matrix. Metastable intermetallic phases are being reported for the first time during hot-dip aluminizing. © 2018 Elsevier B.V.Item On the corrosion resistance of some selective laser melted alloys(Elsevier B.V., 2018) Suryawanshi, J.; Baskaran, T.; Prakash, O.; Arya, S.; Ramamurty, U.The electrochemical corrosion resistances of selective laser melted (SLM) 316 L austenitic stainless steel (SS), 18(Ni) 300-grade maraging steel (MS), and Al-12 wt.% Si (AS) alloy in a 0.1 M NaCl solution at room temperature were evaluated. The effects of laser scanning strategy (single melt vs. checker board styles), post-SLM heat treatment, and corroding surface orientation (with respect to the scan and build directions) on the corrosion behavior were examined. In all cases, results were compared with those obtained on samples with the same compositions, but manufactured using conventional means. The experimental results show that, for the particular set of experimental conditions employed in this study, SLM in general improves the corrosion resistances of Al-12 wt.% Si and stainless steel alloys and degrades the corrosion resistance of the maraging steel, in comparison to the respective corrosion resistances of their conventionally manufactured counterparts. These results are discussed in terms of microstructural refinement and porosity that are common to the SLM alloys. © 2018 Acta Materialia Inc.Item High-temperature wear and frictional behavior of partially oxidized Al with NiCr composite coating(Institute of Physics Publishing helen.craven@iop.org, 2019) Medabalimi, S.R.; Ramesh, M.R.; Kadoli, R.The influence of composite coating in improving wear and frictional behavior from room temperature to 600 °C was investigated. Partially oxidized Al powder was prepared with a flame spray process by spraying pure Al powder into distilled water. The composite powder is the mixture of 30 weight percent of partially oxidized Al and 70 weight percent of NiCr alloy powder. The composite powder was subsequently coated on MDN321 steel by air plasma spray process. The composite coatings are characterized with respect to adhesion strength, porosity, micro-hardness, and density. Wear and frictional behavior of coatings are evaluated under disc speed of 1 and 2 m s-1, loads of 10, 20 and 30 N and 3000 m sliding distance. The test results indicated that at room temperature, frictional heat generated due to applied load produce three-body abrasion at the interface caused to increase the wear and friction in the coating. The oxide film formed at high temperature due to plastic deformation avoids surface degradation at the interface and reduce the wear and friction. The worn surfaces at 600 °C consist phases of ?-Al2O3, NiO, and Cr3O. These phases are contributing to improving the wear resistance of the coating more than 4-times compared to uncoated steels under varying load and sliding velocities. The coefficient of friction reduced with increase in temperature due to generated oxides act as lubricants at the interface. © 2019 IOP Publishing Ltd.Item Microstructural investigations on the hot-dip aluminized AISI 321 stainless steel after diffusion treatment(Elsevier B.V., 2019) Huilgol, P.; Udupa, K.R.; Bhat, K.U.The microstructure of the hot-dip aluminized AISI 321 stainless steel was studied after diffusion treatment at 900 °C for 3 h. The microstructural characterization was carried out by scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry. The microstructure of the as aluminized steel consisted of two regions, viz.; aluminum topcoat and aluminide layer. During the diffusion treatment, the coating transformed into a layered structure consisting of four layers. The Fe2Al5 phase was formed in the outermost layer and the presence of Al13Fe4 quasicrystalline approximant phase was observed. The innermost layer adjacent to the base metal transformed to ferrite phase with NiAl precipitates. Next, to this layer, a disordered FeAl phase was observed. The lattice parameter of the disordered FeAl phase was found to be larger than that of the ordered B2 FeAl phase. The layer between outer Fe2Al5 phase and disordered FeAl phase consists of a mixture of three phases, namely Fe2Al5, disordered FeAl and a new phase with the simple cubic structure. The phase with simple cubic structure shares cube on cube crystallographic orientation relationship with the disordered FeAl phase. © 2019 Elsevier B.V.Item Evaluation of artificial neural network in data reduction for a natural convection conjugate heat transfer problem in an inverse approach: experiments combined with CFD solutions(Springer, 2020) Kumar, M.K.H.; Vishweshwara, P.S.; Gnanasekaran, N.In this work, natural convection fin experiments are performed with mild steel as the fin and an aluminium plate as base. The dimension of the mild steel fin is 250 mm × 150 mm × 6 mm and the aluminium base plate is 250 mm × 150 mm × 8 mm. A heater is provided on one side of the aluminium base plate and the mild steel fin emerges on the other side of the plate. The heater provides required heat flux to the fin base; several steady-state natural convection experiments are performed for different heat fluxes and corresponding temperature distributions are recorded using thermocouples at different locations of the fin. In addition, a numerical model is developed that contains the dimensions of the fin set-up along with extended domain to capture the information of the fluid. Air is treated as a working fluid that enters the extended domain and absorbs heat from the heated fin. The temperature and the velocity of the fluid in the extended domain are obtained by solving the Navier–Stokes equation. The numerical model is now treated as a forward model that provides the temperature distribution of the fin for a given heat flux. An inverse problem is proposed to determine the heat flux that leads to the temperature distributions during experiments. The temperature distributions of the experiments and forward model are compared to identify the unknown heat flux. In order to reduce computational cost of the inverse problem the forward model is then replaced with artificial neural network (ANN) as data reduction, which is developed using several computational fluid dynamics solutions, and the inverse estimation is accomplished. The results indicate that a quick solution can be obtained using ANN with a limited number of experiments. © 2020, Indian Academy of Sciences.Item Studies on free and forced vibration of functionally graded back plate with brake insulator of a disc brake system(Springer Science and Business Media Deutschland GmbH info@springer-sbm.com, 2020) Patil, R.; Joladarashi, S.; Kadoli, R.The back plate with brake insulator of a disc brake system used in automobile is a sandwich structure. Mitigating brake squeal associated with the operation of the disc brake has been a focus of many automobile researchers. As on today’s practice, steel–acrylic–steel is used for back plate–brake insulator assembly. The present study focuses on proposing Al - Al 2O 3 functionally graded metal ceramic composite material (FGM) for the back plate attached with conventional Steel–Acrylic brake insulator. Accordingly, a comparison study is presented in terms of the free and forced vibration characteristics of different material combinations for back plate–brake insulator sandwich beams such as steel–acrylic–steel, FGM–acrylic–steel, FGM–acrylic–aluminium and steel–acrylic–aluminium. The associated governing equations for sandwich beam which are well established in the literature are presented, and they are solved for simply supported conditions using trigonometric displacement functions. The real and imaginary parts of the various parameters come into the picture because of complex shear modulus of viscoelastic core. The comparison study among the combinations reveals that the natural frequency, loss factor and with regard to dynamic loading the imaginary part of transverse displacement, axial displacement, stress and strain of FGM–acrylic–steel are higher. As a result, FGM–acrylic–steel is suitable combination for back plate and brake insulator assembly which enhances the damping capacity of overall disc brake system and also helps in reducing brake squeal problem associated with operation of disc brake system. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.Item Deposition of TiN and TiAlN Thin Films on Stainless Steel Tubes by a Cylindrical Magnetron Sputtering Method(ASTM International, 2021) Trivedi, K.; Rane, R.; Joseph, A.; Arya, S.B.Titanium nitride (TiN) and titanium aluminum nitride (TiAlN) coatings are very hard materials that are mostly coated on cutting tools to increase the tool life. These coatings have also been successfully applied as a coating material for biomedical applications mainly due to their tribological properties, biocompatibility, and affordable price. In an attempt to develop transition metal nitride coatings on specimens of cylindrical geometry, TiN and TiAlN thin films were deposited successfully on stainless steel tubes using a direct-current cylindrical magnetron cosputtering method. Both types of coatings were uniform in nature and had good adherence to the substrate. TiN and TiAlN thin films were characterized systematically to determine their structure, surface morphology, chemical states, chemical structure, and electrochemical behavior using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and potentiodynamic methods, respectively. The XRD patterns of the TiN and TiAlN coatings indicated (111) preferential orientation. Crosssectional SEM images revealed a columnar growth of the coatings with an arrow-headed geometry. XPS characterization showed the presence of TiN, Titanium dioxide, titanium oxynitride, aluminum oxide, and aluminum nitride phases. Potentiodynamic polarization tests in 3.5 % sodium chloride solution revealed that the TiAlN coating exhibited superior corrosion resistance compared with the TiN coating. Furthermore, TiAlN coating showed 94 % of average absorption in ultraviolet-visible region using photospectrometry. The cylindrical magnetron sputter deposition technique enables development of uniform protective coatings on tubular geometries, which are frequently employed in solar thermal and nuclear applications. © 2021 by ASTM International.Item Solid Particle Erosion Behavior of Partially Oxidized Al with NiCr Composite Coating at Elevated Temperature(Springer, 2021) Subba Rao, M.; Ramesh, M.R.; Kadoli, R.The composite coating was developed and investigated the solid particle erosion performance at elevated temperature by varying impact angles. Al2O3 erodent of grit size 50 µm was used in air-jet erosion tester to investigate the resistance to erosion at RT, 200, 400, 600, and 800 °C by varying 30, 45, 60, 75, and 90° impact angles. The composite coating was deposited on MDN321 steel by plasma spray process with feedstock of “30 weight percent of partially oxidized Al powder and 70 wt.% of NiCr alloy powder.” The composite coating was characterized by bond strength, porosity, micro-hardness, and density. Volumetric erosion loss concerning temperature and impact angle was studied using SEM, EDAX, and XRD analysis. Non-contact three-dimensional optical profilometer was used to quantify the volumetric erosion loss. MDN321 steel showed better erosion resistance than composite coating at all the temperatures. Due to the formation of stable oxides at 800 °C the erosion resistance of the coating was improved. © 2021, ASM International.Item Experimental and Numerical Study of Applicability of Euler's Buckling Theory for Laminated Plates(The Aeronautical and Astronautical Society of the Republic of China, 2025) Puranik, A.M.; Kaliveeran, V.This study investigates the accuracy of Euler’s theory for predicting the critical buckling load of a laminated plate comprising a 2.4 mm steel core sandwiched between 1.3 mm aluminum layers, with dimensions 500 mm × 100 mm. Analytical solutions are based on Euler's buckling theory. The theoretical values are verified through ANSYS simulation and experimental testing. The results reveal the limitations of classical buckling assumptions when applied to laminated composites, emphasizing the effects of material heterogeneity. Numerical and experimental analyses confirm the influence of these factors on the critical load, providing insights into the adaptation of classical theory for complex material systems. This research offers a comprehensive framework for the buckling mechanism of laminates, bridging theoretical, computational, and experimental approaches. © 2025 The Aeronautical and Astronautical Society of the Republic of China. All rights reserved.Item Wear and Friction Behavior of Stainless Steel and Aluminium Alloys: Role of Pin Diameter and Track Size in Dry Sliding Experiments(The Aeronautical and Astronautical Society of the Republic of China, 2025) Raveesh, R.M.; Kaliveeran, V.; Kundapura, S.Tribological characterization of materials is critical due to their extensive use in various industrial applications, where friction and wear significantly affect performance and longevity. Tribological studies helps to identify the material suitability for specific applications based on wear resistance, frictional performance, and durability under given conditions. Stainless steel (SS304, SS304L, SS316) and aluminium (Al6061, Al6082) alloys, were selected to understand their performance in dry sliding conditions. This study presents a comparative tribological analysis of stainless steels (SS304, SS304L, SS316) and aluminium alloys (Al6061, Al6082) under dry sliding conditions using a pin-on-disk tribometer. The novelty lies in evaluating the influence of pin diameter (6 mm and 8 mm) and track diameter (60–120 mm) on wear rate and coefficient of friction (CoF). Results show that Al6061 exhibited the highest wear rate (0.0676 mm3/N·m) and CoF up to 0.7, particularly under 20 N load and small track diameter (60 mm). In contrast, SS316 demonstrated the lowest wear rate (0.0023 mm3/N·m) and stable CoF (0.4), particularly under 10 N load and larger track diameter (120 mm), indicating superior wear resistance. The study reveals that smaller pin and track diameters intensify contact stress, accelerating wear in softer materials. © 2025 The Aeronautical and Astronautical Society of the Republic of China. All rights reserved.