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Item Tribological behaviour of monolayer and multilayer Ti-based thin solid films deposited on alloy steel(2019) Badiger, P.V.; Desai, V.; Ramesh, M.R.; Joladarashi, S.; Gourkar, H.The fretting wear and adhesive wear resistance of Ti-based thin solid films deposited on MDN121 steel substrate are evaluated. Plasma-assisted cathodic arc evaporation technique is used to develop the TiC-C monolayer coating and Ti/TiN/TiCN/TiN/TiCN multilayer coatings used in the study. FESEM-EDS, nanoindentation, Raman spectroscopy, optical profiler, and confocal microscope are used to characterise the coatings and wear tracks. Diamond-like carbon is observed in the microstructure of both the coatings. During the fretting analysis, the coefficient of friction (COF) is reduced by 68.49% in the case of the TiC-C monolayer coating and 42.46% in the Ti multilayer coatings as compared to the substrate. The volumetric wear loss of the TiC-C monolayer coating is lower than the multilayer coating. The wear surface morphology reveals the abrasive form of the fretting wear mechanism in both the monolayer and multilayer coatings whereas the galling failure in the substrate. During adhesive wear, the COF is reduced by 71.73% in the monolayer coating and 59.33% in the multilayer coatings compared to the substrate. The monolayer coating exhibits low friction and low wear rate as compared to the multilayer coating. � 2018 IOP Publishing Ltd.Item Sintering metal injection molding parts of tungsten-based steel using microwave and conventional heating methods(2019) Veeresh, Nayak, C.; Ramesh, M.R.; Desai, V.; Samanta, S.K.In recent years, the near net shape metal injection molding process combines desirable features of plastic injection molding and powder metallurgy processes to gain high strength-to-weight ratio for manufacturing complex-shaped parts. The metal injection molding process consists of mixing, molding, debinding, and sintering. Microwave processing has attracted much attention in global research because of its unique features such as its ability to heat and sinter a wide variety of metals and its significant advantages in energy efficiency, processing speed, and compatibility. Also, it presents few environmental risks and can produce refined microstructures. The injected samples to be sintered are composed of fine tool steel metal powder and binders, stearic acid, paraffin wax, low-density polyethylene, and polyethylene glycol (600). In recent years, microwave-assisted post-treatment is considered a novel method for processing green parts. In this work, the green parts are subjected to high-intensity microwave fields which operate at a frequency of 2.45 GHz. Metal injection molding compacts were sintered using multi-mode microwave radiation. The sintering of a metal injection molding compact by microwaves has hardly been reported. The metal injection molding compact showed better results than those produced by sintering with conventional heating. This study evaluates the effect of conventional sintering and microwave sintering on mechanical properties. By optimizing the sintering process, increased sintered hardness, a more homogeneous microstructure, and greater shrinkage were obtained using microwave-assisted sintering. IMechE 2018.Item Thermal Analysis of a Plasma Sprayed Ceramic Coated Diesel Engine Piston(2018) Banka, V.K.; Ramesh, M.R.In this paper, we evaluated performance-enhancing modifications of the coating surface for a diesel engine piston. Thermal barrier coatings were applied to insulate the substrate from higher operating temperatures. A top coat (0.4 mm thick) and bond coat (0.1 mm thick) were applied to the aluminum alloy piston crown for analysis. Yttria-stabilized zirconia was used for the top coat and NiCrAl alloy was used for the bond coat. A static thermal analysis was performed to determine the temperature distribution at the top and substrate surface. Holes (2, 3, 4 and 5 mm in diameter) were created on the surface of the coating and the temperature distribution was analyzed. Comparison of the results with those of an uncoated piston revealed that the temperature of the substrate was decreased while temperature of the top surface was increased. Decreasing the temperature of the substrate reduced thermal fatigue while increasing the temperature of the top surface reduced fuel consumption thus leading to an overall improvement in performance. The lowest substrate temperature obtained was for a coated surface with 2 mm diameter holes, whereas the highest top surface temperature obtained was for a coated surface with 5 mm diameter holes. 2017, The Indian Institute of Metals - IIM.Item Plasma sprayed Cr3C2-NiCr/fly ash cenosphere coating: Cyclic oxidation behavior at elevated temperature(2018) Doddamani, M.; Mathapati, M.; Ramesh, M.R.Oxidation is one of the major degradation phenomena observed in components subjected to higher temperatures like in thermal power plants (boiler tubes), steam and gas turbines blades etc. Developing protective coatings for such components mitigate oxidation. In the present study, plasma spray technique is utilized to deposit the Cr3C2-NiCr/Cenospheres coating on MDN 321 steel substrate. Thermo cyclic oxidation test is conducted at 600 C (20 cycles) on both the coating and MDN 321 steel substrate. The thermogravimetric methodology is employed to estimate the oxidation kinetics. Energy Dispersive Spectroscopy (EDS), x-ray Diffraction (XRD), Scanning Electron Microscope (SEM) and x-ray mapping technique is employed to characterize the oxidized samples. Cr3C2-NiCr/Cenosphere coating displayed lower rate of oxidation as compared to substrate implying its suitability in high-temperature applications. Protective oxides like Al2O3, Cr2O3, and NiCr2O4 are observed on the uppermost layer of the coating lowering the oxidation rate in the developed coating. 2018 IOP Publishing Ltd.Item Microstructure and Wear Performance of ECAP Processed Cast Al Zn Mg Alloys(2018) Manjunath, G.K.; Udaya, Bhat, K.; Preetham, Kumar, G.V.; Ramesh, M.R.In the present investigation, wear performance of equal channel angular pressing (ECAP) processed cast Al Zn Mg alloys under dry sliding wear conditions was studied against a steel disc. Initially, Al Zn Mg alloys (with 5, 10, 15% zinc and 2% magnesium) were ECAP processed. After ECAP, grain size was reduced and enhancement in the hardness was observed. Wear resistance of the alloys increased after ECAP processing. Wear resistance of the alloys also increased when the quantity of the zinc was increased in the alloys. But, wear resistance of all three alloys decreased with increase in the load and the sliding speed. Coefficient of friction of the alloys decreased after ECAP processing. Coefficient of friction of the alloys also decreased when the quantity of the zinc was increased in the alloys. Coefficient of friction of all three alloys increased with increase in the load and the sliding speed. Irrespective of the alloy composition and applied load, worn surfaces of the cast and homogenized samples were composed of plastic deformation, scratches and micro-ploughing. On the other hand, in ECAP processed samples, morphology of the worn surfaces depended on the applied load. Abrasive wear is the main wear mechanism perceived in cast and homogenized samples at all loads. While in ECAP processed samples, the wear mechanism shifted from adhesive and oxidation wear to abrasive wear with increase in the load. Formation of oxide layers on the surface of the sample increased with increase in the ECAP passes. In ECAP processed samples, transfer of iron content from the disc to the sample surface was identified. 2018, The Indian Institute of Metals - IIM.Item Microstructure and tribological characteristics of APS sprayed NiCrBSi/flyash cenosphere/Cr2O3 and NiCrBSi/flyash cenosphere/Mo composite coatings at elevated temperatures(2019) Nagabhushana, N.; Rajanna, S.; Mathapati, M.; Ramesh, M.R.; Koppad, P.G.; Reddy, N.C.In the present investigation NiCrBSi/flyash/Cr2O3 and NiCrBSi/flyash/Mo composite coatings are developed using atmospheric plasma spray technique on superni 76 alloy. Coatings are characterized in terms of microstructure, phase analysis, and microhardness. Tribological properties of the coatings are evaluated using a pin on disc tribometer. Test is conducted under dry sliding conditions at room temperature, 200 C, 400 C, and 600 C respectively. Microstructure and worn surfaces of the coatings are analyzed by utilizing Scanning Electron Microscope (SEM) where in phase analysis is carried out using x-ray diffractometer (XRD). XRD results revealed the presence of ?-Ni as primary phase along with Ni3B, Cr7C3, SiO2 and Al2O3 as minor phases in both the NiCrBSi/flyash/Cr2O3 and NiCrBSi/flyash/Mo coatings. Among the two coatings, Mo composite coating exhibited lower porosity and higher microhardness. The friction coefficient of both the coatings decreased with increasing temperature. The wear rate is found to decrease at lower temperatures but increased at a higher temperature (>400 C) for Cr2O3 composite coating wherein Friction coefficient is decreased with increase in the temperature for Mo composite coatings. The worn surface analysis conducted revealed abrasive wear at lower temperatures while the transition from abrasive to adhesive is observed at higher temperatures. 2019 IOP Publishing Ltd.Item Microstructure and tribological behavior of plasma sprayed NiCrAlY/WC-Co/cenosphere/solid lubricants composite coatings(2018) Doddamani, M.; Mathapati, M.; Ramesh, M.R.Present investigation deal with NiCrAlY/WC-Co/Cenosphere/MoS2/CaF2, NiCrAlY/WC-Co/Cenosphere/MoS2/CaSO4 and NiCrAlY/WC-Co/Cenosphere coatings deposited on MDN 321 steel using atmospheric plasma spraying. Tribological properties of MDN 321 steel and coatings are evaluated from room temperature (RT) to 600 C under dry lubrication conditions using a pin on disc high-temperature tribometer. Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and Energy Dispersive Spectroscopy (EDS) are used to characterize the coatings. Presence of cenospheres in these coatings might effectively reduce wear acting as localized regions accumulating wear debris. The result shows that wear rate of all the coatings are lower as compared to MDN 321 substrate at all the test conditions. NiCrAlY/WC-Co/Cenosphere/MoS2/CaF2 and NiCrAlY/WC-Co/Cenosphere/MoS/CaSO4 coatings registered lower friction coefficient as compared to NiCrAlY/WC-Co/Cenosphere coating and MDN 321 substrate. Characterization of the NiCrAlY/WC-Co/Cenosphere/MoS2/CaF2 and NiCrAlY/WC-Co/Cenosphere/MoS2/CaSO4 coatings worn out surface suggests that MoS2 provides lubrication at 200 C and formation of CaMoO4, MoO3 through tribo chemistry reaction at higher temperature provides lubrication at 600 C. SEM micrograph of worn surface demonstrates that the main wear mechanism is plowing and delamination. 2018 Elsevier B.V.Item Microstructure and tribological behavior of flame sprayed and microwave fused CoMoCrSi/CoMoCrSi-Cr3C2 coatings(2019) Prasad, C.D.; Joladarashi, S.; Ramesh, M.R.; Srinath, M.S.; Channabasappa, B.H.This present work deals with the investigation of dry sliding wear behavior of CoMoCrSi and CoMoCrSi-Cr3C2 depositing on titanium substrate through Flame spray process, subsequently fused by the microwave hybrid heating process. Prior to the deposition of the coating, CoMoCrSi powder is milled by using high energy ball milling (HEBM) process and later 30% of Cr3C2 powder is added. Microstructural features and phase analysis of milled powders, as-coated and microwave fused coatings are inspected by using SEM with EDS and XRD process respectively. The coatings before and after fusing are tested for microhardness and bond strength by using a Vickers microhardness and universal tensile machines respectively. Dry sliding wear behavior of coatings before and after fusing is conducted against alumina counter face at ambient and elevated temperatures, also normal load is varied. The wear mechanism of both coatings is examined by employing XRD, SEM-EDS techniques. The fused coatings exhibit lower friction and better wear resistance compared with as-deposited coatings. The detailed results of each test of their coatings are discussed in this paper. 2018 IOP Publishing Ltd.Item Microstructure and Adhesion Strength of Ni3Ti Coating Prepared by Mechanical Alloying and HVOF(2018) Reddy, N.C.; Ajay, Kumar, B.S.; Ramesh, M.R.; Koppad, P.G.In the present work we report the development of Ni3Ti intermetallic compound by high energy ball milling of Ni and Ti powders. The ball milled powders were taken at various intervals (4, 6, 8, 10, and 11 h) to analyze the formation of NixTix intermetallic compounds. The ball milled powders were analyzed using scanning electron microscopy and X-ray diffraction. The layered shaped powder particles of Ni3Ti phase were formed after 11 h of ball milling, which was confirmed by X-ray peaks. Further High-Velocity Oxy-Fuel (HVOF) process was used to coat Ni3Ti and Ni3Ti + (Cr3C2 + 20NiCr) on MDN 420 steel. Both the coated materials displayed excellent cohesion with minimal porosity less than 2%. The tensile adhesion strength test was carried out on these coatings to check the bond strength. Out of the two the Ni3Ti coating showed excellent bond strength of 41.04 MPa compared to that of Ni3Ti + (Cr3C2 + 20NiCr) coating. 2018, Pleiades Publishing, Ltd.Item Optimization of machining parameters in turning process of mdn431 using ti-multilayer coated tool(2018) Badiger, P.V.; Desai, V.; Ramesh, M.R.; Raveendra, K.WC-Co Cutting tool inserts are coated with tailored composition of Ti/TiCN/TiN/TiCN/TiN using cathodic arc evaporation technique. MDN431 is one of highly alloyed steel with tailored mechanical properties. MDN431 material is machined with Ti/TiCN/TiN/TiCN/ TiN coated and uncoated Co-based WC tool inserts. Machining parameters; cutting speed (398-625rpm), feed rate (0.093-0.175mm/rev) and depth of cut (0.1-0.5mm) and experiments are conducted according to response surface methodology center composite rotatable design. Surface roughness and cutting forces are measured for each iteration and the same analyzed for significance. Result reveals that for optimum surface roughness is obtained at the condition of high speed, low feed and low depth of cut. For optimum cutting force high speed, low feed and low depth of cut is preferred. Coated tools performed better in the study with increased tool life, reduced cutting force & surface roughness. At the optimum machined conditions machined surface are analyzed using optical profilometer. Central composite rotatable design developed mathematical models for cutting force and surface roughness for the prediction of results. The predicted results are minimum error and developed model is adequate for further usage. International Journal of Modern Manufacturing Technologies.