Browsing by Author "Ramesh, M."

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Adsorption and photocatalytic properties of NiO nanoparticles synthesized via a thermal decomposition process
(Cambridge University Press, 2018) Ramesh, M.; Rao, M.P.C.; Anandan, S.; Nagaraja, H.S.
NiO nanoparticles (NPs) were synthesized at different annealing temperatures via a thermal decomposition process and characterized using X-ray diffraction, scanning electron microscopy, and UV-vis spectroscopy. The NiO NPs prepared at higher annealing temperature (400 °C) were shown excellent adsorption and photocatalytic activity toward textile dyes reactive black 5 (RB-5) and methylene blue (MB). About 87.2% of RB-5 in 60 min and 70.2% of MB in 5 h was removed using NiO NPs synthesized at 400 °C. The photocatalytic degradation of MB was found to increase with an increase in the annealing temperature of the catalyst. Moreover, the kinetic study revealed that the adsorption and photocatalytic activity of NiO NPs followed the second and first-order kinetics, respectively. The enhanced performance of NiO NPs toward dye removal might be related to its optical and structural properties. © Materials Research Society 2018.
The effect of etching time on structural properties of Porous silicon at the room temperature
(2016) Ramesh, M.; Nagaraja, H.S.
Nano-porous silicon (PS) layers have been prepared by electrochemical etching of (100) silicon wafer in the solution of hydrofluoric acid (HF) and ethanol (C2H5OH). In this paper, XRD and FTIR confirm the formation of PS. The size of crystallites in the porous Si layers was found from XRD, which isaround ~2.4 nm. The evolution of morphology of PS as a function of etching time is imaged using SEM. The average pore-diameter has been calculated from the image j software, which is in the range of 238-1117nm. The Raman spectra reveal that the peak intensities sharply increase with etching time due to presence of nancrystals on the surface of PS. It was observed that the peak of Raman signal was around ~520.5cm-1. Luminescence studies revealedthat the strong photoluminescence emission was observed at about ~660nm. It possesses a broad red emission band on the surface of PS due to the growth of Si=O bonds and the formation of silicon hydrides (SiHx), which is caused to trapped electron states at the interface between the crystalline Si and SiO2. � 2016 Elsevier Ltd.
Effect of Lateral Vibrations during Directional solidification on Mechanical Properties of Al-18%wt Si Alloys
(2018) Ramesh, Babu, N.; Ramesh, M.; Kiran, Aithal, S.; Kotresh, K.
Experimental Investigation on the effect of mold vibration on the mechanical properties of Al-18%WtSi have been carried out using Taguchi Technique, as the molten metal at 750�C is poured in to the insulated mold which is subjected to lateral vibrations, directional solidification takes place due to the presence of chill at the bottom which gives rise to a functionally graded alloy. Due to the excitation, silicon present in the molten metal precipitates along its length. The castings are prepared with varying chill materials and chill volumes without vibrations and with a vibrating frequency of 50Hz. ANOVA was applied to optimize the process parameters. Hardness and Tensile test for the samples was carried out. Improvements in the properties can be attributed to the grain refinement of the casting prepared under vibrations. � 2017 Elsevier Ltd.
Fabrication of stainless steel based composite by metal injection moulding
(2018) Veeresh, Nayak, C.; Ramesh, M.; Desai, V.; Kumar, Samanta, S.
Metal injection moulding (MIM) is large scale manufacturing method, for creation of complex shapes and miniature parts by a combination of plastic injection moulding with the flexibility in sintering of metal particulates. In current investigation binder comprised of paraffin wax, polyethylene glycol, stearic acid and low-density polyethylene are developed for moulding of composite powders of SS316L+WC-CrC-Ni, and sintered at 1200�C under hydrogen purged atmosphere. Composites are characterised with respect to rheological, thermal properties and microstructure by scanning electron microscopy, microhardness and density. Properties of sintering temperature and heating rate on the above properties have been evaluated to obtain a defect-free composite. � 2017 Elsevier Ltd.
Fabrication, characterization and catalytic activity of ?-MnO2 nanowires for dye degradation of reactive black 5
(Elsevier B.V., 2016) Ramesh, M.; Nagaraja, H.S.; Rao, M.P.; Anandan, S.; Huang, N.M.
?-MnO2 nanowires (NWs) prepared by hydrothermal method are characterized using XRD and FT-IR. The crystallite size, surface area of NWs increases, whereas dislocation density and band gap decreases with an increase in oxidizer molarity. The band gap decreases from 2.55 to 1.27 eV. The above observations correlate well with the enhanced catalytic activity of MnO2 NWs for degradation of azo dye reactive black 5 (RB5). About 70% of the dye were successfully removed in 60 min using 20 mg of MnO2 NWs in the presence of 6 mL of H2O2. MnO2 NWs show a good reusability, suggesting it as an effective and recyclable catalyst. © 2016 Elsevier B.V. All rights reserved.
Inrush Current Parameters Associated with Back-to-Back Switching of Capacitors in a Bank
(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2017) Ramesh, M.; Nagamani, H.N.; Vaidhyanathan, V.; Punekar, G.S.
Back-to-back switching of 50 kVAr capacitors, in a capacitor bank of 200 kVAr is investigated experimentally. The switching inrush currents in a three-phase, 200 kVAr, 415 V Automatic Power Factor Correction panel at power frequency are captured in the laboratory. The characterizing features of inrush current are reported and analyzed. The commercially available two makes of switches (contactors) are used to compare the inrush currents with and without their pre-insertion resistors (PIR). The inrush current scenario of the experimental setup is modeled in EMTDC/PSCAD to ascertain the results. The ratio Ipeak/IN for both the contactors without PIR exceeded the limit mentioned in IEC 60831-1 Ed 3.0 : 2014. © 2017, Copyright © Taylor & Francis Group, LLC.
Optimisation of machining parameters for end milling of maraging steel MDN 250 using TiAlSiN and TiSiN coated WC-Co inserts
(2020) Varghese, V.; Jagmalpuria, A.; Badiger, P.V.; Ramesh, M.
Thin film coatings TiSiN, TiAlSiN were deposited on WC-Co milling inserts using RF magnetron sputtering. The machinability studies of maraging steel is carried out using thin film coatings of TiSiN TiAlSiN. The maching parameters of cutting speed, feed rate and depth of cut will be varied to analyse machining responses such as surface roughness and cutting force. The performance of each coating will be evaluated and compared along with tool wear and tool life. A Taguchi based grey relational analysis will be used to optimize the machining parameters and analysis of variance (ANOVA) is used to find the most significant factor. � 2020 Author(s).
rGO/MnO2 nanowires for ultrasonic-combined Fenton assisted efficient degradation of Reactive Black 5
(IWA Publishing 12 Caxton Street London SW1H 0QS, 2017) Ramesh, M.; Rao, M.P.; Rossignol, F.; Nagaraja, H.S.
Reduced graphene oxide (rGO) coated manganese dioxide (MnO2) nanowires (NWs) were prepared by the hydrothermal method. Raman spectra confirmed the presence of rGO and the Brunauer-Emmett-Teller surface area of rGO/MnO2 NWs was found to be 59.1 m2g-1. The physico-chemical properties of prepared catalysts for the degradation of Reactive Black 5 (RB5) dye were investigated. 84% of RB5 dye in hydrogen peroxide solution was successfully degraded using rGO/MnO2 NWs, while only 63% was successfully degraded with pristine ?-MnO2 NWs in 60 min owing to the smaller crystallite size and large surface area. Further, the ultrasonic-combined Fenton process significantly enhanced the degradation rate to 95% of RB5 by the catalyst rGO/MnO2 NWs due to synergistic effects. The decomposition products identified using gas chromatography-mass spectrometry revealed a higher production rate of fragments in the ultrasonic-combined Fenton process. Therefore, rGO/MnO2 NWs with the ultrasonic-combined Fenton process is an efficient catalyst for the degradation of RB5, and may be used for environmental protection. © IWA Publishing 2017.
The effect of etching time on structural properties of Porous silicon at the room temperature
(Elsevier Ltd, 2016) Ramesh, M.; Nagaraja, H.S.
Nano-porous silicon (PS) layers have been prepared by electrochemical etching of (100) silicon wafer in the solution of hydrofluoric acid (HF) and ethanol (C2H5OH). In this paper, XRD and FTIR confirm the formation of PS. The size of crystallites in the porous Si layers was found from XRD, which isaround ~2.4 nm. The evolution of morphology of PS as a function of etching time is imaged using SEM. The average pore-diameter has been calculated from the image j software, which is in the range of 238-1117nm. The Raman spectra reveal that the peak intensities sharply increase with etching time due to presence of nancrystals on the surface of PS. It was observed that the peak of Raman signal was around ~520.5cm-1. Luminescence studies revealedthat the strong photoluminescence emission was observed at about ~660nm. It possesses a broad red emission band on the surface of PS due to the growth of Si=O bonds and the formation of silicon hydrides (SiHx), which is caused to trapped electron states at the interface between the crystalline Si and SiO2. Â© 2016 Elsevier Ltd.