Browsing by Author "Sampath, S."

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Crystallisation kinetics study in stabilisation treatment of sol-gel derived 45S5 bioglass
(American Institute of Physics Inc. subs@aip.org, 2018) Sampath, S.; Matin, M.; Kiran, P.; Manne, B.; Ramesh, M.R.
Solgel gel derived bioglasses require stabilisation heat treatment to decompose nitrates and to improve mechanical stability. While decomposing nitrate phases especially in solgel derived 45S5 bioglass, it is difficult to avoid crystallisation of silicate crystalline phases (Na2CaSi2O6, Na2Ca2Si3O9) due to overlapping of nitrates decomposition and silicates crystallisation temperatures. Control of such crystallinity amount in bioglasses is at most important during stabilisation as it affects the dissolution rates of bioglassesin body fluids. Controlling and quantifying of this crystallinity helps in engineering bioglasses for specific period in application. In this work, synthesis of 45S5 bioglass through solgel method is presented. Here, temperature and time dependent crystallisation kinetics were estimated using a quality parameter derived from X-ray diffraction (XRD) patterns of bioglass during stabilisation treatment. Quality parameter derived from XRD patterns is termed as IPB which is the ratio of integral area of peaks to the integral area of background. It is proposed that IPB can be used as quality parameter to assess crystallinity and to study crystallisation kinetics in bioglasses. Â© 2018 Author(s).
Hot corrosion behaviour of HVOF sprayed stellite-6 coatings on gas turbine alloys
(2014) Jegadeeswaran, N.; Ramesh, M.R.; Sampath, S.; Bhat, K.U.
The coal burned natural gas in contact with gas turbine can contain impurities of sodium, sulfur, vanadium, silicon and possibly lead and phosphorous, induce accelerated hot corrosion during long term operation. Coatings are frequently applied on gas turbine components in order to restrict surface degradation and to obtain accurate lifetime expectancies. High velocity oxy-fuel thermal spraying has been used to deposit Stellite-6 alloy coatings on turbine alloys. Hot corrosion behavior of the coatings were investigated for 50 cycles of 1 h heating at 800 C followed by 20 min cooling in presence of Na 2SO4 + 50 % V2O5 measuring weight gain (or loss). X-ray diffraction and SEM/EDAX techniques were used to characterize the oxide scale formed. The superior performance of Stellite-6 coating can be attributed to continuous and protective thin oxide scale of CoO, Cr2O3 and SiO2 formed on the surface. The coating region beneath this thin oxide scale was partially oxidized. Uncoated SuperCo-605 and MDN-121 showed less weight gain than Stellite-6 coated samples, but they showed spalling or sputtering during cyclic oxidation. Stellite-6 coating was dense and pore free even after 50 cycles, indicating that it can resist the hot corrosion cycle. © 2013 Indian Institute of Metals.
Load Scheduling Algorithm Design for Smart Home Energy Management System
(2018) Pawar, P.; Sampath, S.; Ghosh, T.; Vittal, K.P.
In a world of diminishing energy stores and heightening economic crises, it is imperative to develop systems that diminish our dependence on non-renewable resources. There is a growing trend of Smart Home Energy Management Systems (SHE) which use smart switches to actively monitor the energy consumption by each load, the power available and other factors to switch between renewable resources and the main power grid. An extensive literature survey was conducted and results of various approaches were consolidated and analyzed. The approach detailed is a combination of the merits of all the most popular approaches. The methodology proposed hopes to carry out demand response management on both the grid power and solar power in unison. The problem was split in two: scheduling assuming only solar power is available and scheduling assuming only grid power is available. The two halves are then merged together to have the most efficient utilization of the resources available. Further, after analysing the simulation results, the validity of such a solution is presented while adhering to various real world variables. � 2018 IEEE.
Load Scheduling Algorithm Design for Smart Home Energy Management System
(Institute of Electrical and Electronics Engineers Inc., 2018) Pawar, P.; Sampath, S.; Ghosh, T.; Vittal, K.P.
In a world of diminishing energy stores and heightening economic crises, it is imperative to develop systems that diminish our dependence on non-renewable resources. There is a growing trend of Smart Home Energy Management Systems (SHE) which use smart switches to actively monitor the energy consumption by each load, the power available and other factors to switch between renewable resources and the main power grid. An extensive literature survey was conducted and results of various approaches were consolidated and analyzed. The approach detailed is a combination of the merits of all the most popular approaches. The methodology proposed hopes to carry out demand response management on both the grid power and solar power in unison. The problem was split in two: scheduling assuming only solar power is available and scheduling assuming only grid power is available. The two halves are then merged together to have the most efficient utilization of the resources available. Further, after analysing the simulation results, the validity of such a solution is presented while adhering to various real world variables. Â© 2018 IEEE.
Microstructure and Impression Creep Behavior of Al Based Surface Composite Produced by Friction Stir Processing
(Springer India sanjiv.goswami@springer.co.in, 2016) Bhat, K.U.; Udupa, R.K.; Sampath, S.; Huilgol, P.
Al–Fe surface composites were prepared through friction stir processing route by using commercial pure aluminium sheet and iron powder. Friction stir processing was done with a tool made up of high speed steel having a 3 mm pin at the tip. Microstructural features of the friction stir nuggets were characterized by using X-ray diffractometry, scanning electron microscopy, energy dispersive spectroscopy and transmission electron microscopy. Creep behaviour of the friction stir zone was studied using impression creep techniques. Impression creep experiments were done on substrate aluminium and friction stir region. The results show that the surface of Al substrate is converted into a composite, consisting of Al, Fe powders and iron aluminides. The aluminium grain size is drastically reduced, with a large fraction of crystallites having size in the range of 70 nm. Fe particle size was reduced drastically resulting in interparticle spacing in the range of 500 nm. Dislocation density was drastically increased. Impression creep experiments indicated that friction stirred region shows marginally lower activation energy compared to the base metal. This is attributed to the metastability in the structure in the form of extremely fine grain size and high dislocation density. Because of the combined effect, creep in stir zone takes place with a smaller activation energy compared to creep in base aluminium. © 2016, The Indian Institute of Metals - IIM.