Conference Papers

Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/28506

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Author: search.filters.author.Bhat, K.

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    Surface modification of steels using friction stir surfacing
    (Trans Tech Publications Ltd ttp@transtec.ch, 2012) Janakiraman, S.; Reddy, J.; Kailas, S.V.; Bhat, K.
    Friction stir surfacing is done to deposit commercial pure Al on medium carbon steel under open atmosphere conditions. Roughness of the substrate, normal load and tool rotation are the variables. Deposition is analysed with respect to continuity, width, composition and phase parameters. Good deposition is observed under a limited set of load and rotation speed. The deposit contains a mixture of steel and aluminium particles. © (2012) Trans Tech Publications.
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    Effect of deposition time on the characteristics of high phosphorous nickel deposit, deposited using electroless route
    (Trans Tech Publications Ltd ttp@transtec.ch, 2012) Reddy, V.R.; Dixit, B.; Bhat, K.
    Electroless Ni-high P alloy is deposited on commercial aluminium. Parameters are set so that deposit will be crystalline in nature with a very high phosphorous content. Deposition time is the variable. It is observed that all the deposits have nodular morphology indicating nucleation and growth phenomena. The nodules become coarse with increase in the deposition time. The deposit changes from clear crystalline to nanocrystalline with increase in deposition time. Coatings with lower deposition times have porosity in it. © (2012) Trans Tech Publications.
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    Characterization of ZnO films produced by thermal evaporation and oxidation
    (Trans Tech Publications Ltd ttp@transtec.ch, 2015) Prabukumar, C.; Jayalakshmi, M.; Bhat, K.
    ZnO nanostructures such as nanowires and nanorods are beneficial in solar energy harvesting because they provide a structure with a large surface area. Also, they provide a direct pathway to electron transportation, eliminating the scope for grain boundary scattering. In this investigation, thin ZnO films were prepared by thermal evaporation of the Zn metal, which was followed by oxidation. Evaporation parameters and oxidation temperatures were fixed. The oxidation duration was the variable. The effect of oxidation time, on the morphology and structural properties were studied by using scanning electron microscopy and X-ray diffractometry. The study shows that with increase in oxidation time, the morphology changed to nanorods from initial flake morphology. As a function of oxidation time, the crystallinity and texture became more dominant. By using, I-V characteristic curves, it was found that the morphology changes alter the surface electrical conductivity of the prepared ZnO films. © (2015) Trans Tech Publications, Switzerland.
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    Hot dip aluminizing of 9Cr-1Mo steels and their heat treatment
    (Trans Tech Publications Ltd ttp@transtec.ch, 2015) Patel, J.; Huilgol, P.; Jamnapura, N.; Bhat, K.
    Coupons of 9Cr-1Mo steels of type SA 387 Grade 9 class 2 were hot dip aluminized using Al bath at a temperature of 700 °C for 30 seconds. The samples were further heat treated at 750 °C for durations of 1, 3 and 5 hours, respectively. The samples were characterized using X-ray diffractometry, scanning electron microscopy and energy dispersive spectroscopy. The investigation showed that as coated samples contain an aluminum top coat, a reaction layer and substrate material. Within the reaction layer, two distinct regions corresponding to Fe2Al5 and Fe4Al13 were identified. Chromium up to 2 at% was observed. After heat treatment Al coat was not existing. Two distinct layers, corresponding to a thick Fe2Al5 and a thin FeAl were observed at shorter heat treatment duration. Under longer heat treatment durations, multiple phases, namely, Fe2Al5, FeAl, Fe3Al and solid solution of Al in Fe were observed. © (2015) Trans Tech Publications, Switzerland.
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    Heat treatment of friction surfaced steel-aluminum couple
    (Trans Tech Publications Ltd ttp@transtec.ch, 2015) Bhat, K.; Nithin; Bhat, S.; Sudeendran
    Friction surfacing is a solid state process and it is amenable for deposition of aluminum on steel. In this investigation, the mild steel surface was coated with a layer of aluminum using friction surfacing route. The aluminum thickness was in the range of 40-50 μm. It was followed by a heat treatment step to convert aluminum layer in to an aluminide layer. Heat treatment was done in open atmosphere at 700 °C for 2 hours. Microstuctural analysis showed that the aluminide layer is mainly made of Fe2Al5 and Fe4Al13, FeAl and Fe3Al are minor in fraction. Formation of Fe2Al5 is discussed. The aluminide layer also has some amount of porosities. © (2015) Trans Tech Publications, Switzerland.
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    Electron microscopic study of nodules formed during electrodeposition of copper on aluminium
    (Trans Tech Publications Ltd ttp@transtec.ch, 2015) Augustin, A.; Bhat, K.; Udupa, K.R.; Hegde, A.C.
    Copper thin film was deposited on double zincated aluminium using electrodeposition route. To understand the growth behavior of copper nodules, deposition was done by varying coating current density. The topography and cross section of the coating was analyzed by using SEM. The structural details of copper nodules were studied by using TEM. Deposited copper thin film was made up of pomegranate like nodules with size varying from 5 μm to 8 μm, varying as a function of coating current density. At higher current density, the coating was made up of multiple layers of nodules having defects like twins, dislocations and stacking faults. The nodules had fine crystallites of size in the range of 50 nm. © (2015) Trans Tech Publications, Switzerland.