Browsing by Author "Nagabhushana, N."

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    Erosion studies of Plasma-Sprayed NiCrBSi, Mo and Flyash Cenosphere coating
    (IOP Publishing Ltd, 2020) Nagabhushana, N.; Rajanna, S.; Ramesh, M.R.
    The erosion studies of plasma sprayed NiCrBSi / Mo / Flyash Cenosphere and NiCrBSi / Flyash Cenosphere on Superni 76 at room temperature for 30° and 90° impact angle were studied. The microstructure, adhesion properties, microhardness and porosity were investigated. Using SEM, EDS and EDAX techniques, the effect of phase change in the coating during the erosion was analyzed. The NiCrBSi/Mo/Cenosphere coating exhibits greater erosion resistance, and its loss of volume accounting nearly to 50% of the NiCrBSi / Cenosphere coating. Compared to a 90° impact angle, the smallest erosion loss was observed at 30°. The erosion process assessed using SEM micrographs showed that the coating suffered ductile fracture, exhibited acute deformation and had abnormal oxide cracks. The enhanced metal oxide has a shielding effect, can resist erosion, and thus has better erosion resistance. © Published under licence by IOP Publishing Ltd.
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    Influence of temperature on friction and wear behavior of aps sprayed nicrbsi/flyash and nicrbsi/flyash/tio2 coatings
    (Alpha Publishers, 2020) Nagabhushana, N.; Rajanna, S.; Ramesh, M.R.; Pushpa, N.
    Present work reports on the development of two different NiCrBSi based coatings reinforced with flyash and flyash/TiO2. Dense coatings with lamellar structure were establishedvia atmospheric plasma spray (APS) method on nickel based superalloy Superni 76. Coatings were subjected to scanning X-ray deflection and electron microscopy to study the microstructure and phase analysis. Microhardness and elevated temperature wear tests were conducted to analyze the coating hardness, wear andfriction characteristics. Worn surface and wear debris obtained once wear experiment was calculatedvia scanning electron microscopy. Both the coatings exhibited lamellar structure with flyash and TiO2 particles present at the inter-splat boundaries. Mcirohardness of both the coatings were significantly greater than theSuperni 76 substrate. The wear rate of both the coatings was found to increase with the increase in load as well as temperature. Worn surface analysis revealed mild abrasion and adhesion for NiCrBSi/flyash coatings while brittle fracture for NiCrBSi/flyash/TiO2 coatings as major wear mechanism. © 2020, Alpha Publishers. All rights reserved.
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    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.
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    Microstructure and tribological characteristics of APS sprayed NiCrBSi/flyash cenosphere/Cr2O3 and NiCrBSi/flyash cenosphere/Mo composite coatings at elevated temperatures
    (Institute of Physics Publishing helen.craven@iop.org, 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.