Browsing by Author "Bhat, K."

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A continuous flow microreactor as a practical tool for the synthesis of active pharmaceutical ingredients
(Institution of Chemical Engineers, 2024) Bhaskar, K.; Rashed, M.; Bhat, K.; Lee, J.; Kim, K.-H.; Buruga, K.
Continuous flow processing has become a key technology to maximize the capabilities of chemical syntheses. Numerous new tactics have been devised to synthesize various chemicals including active pharmaceutical ingredients (APIs) via a continuous flow system using microreactors. This review aims to illustrate the holistic system approach and diverse applications of continuous flow microreactors for the synthesis of APIs (with respect to type, design, and fabrication). This review also highlights the applicability of continuous flow microreactors in the synthesis of APIs in contrast to conventional batch-type methods along with a discussion of their merits and demerits. Overall, this review is expected to offer valuable insights into the utility of continuous flow microreactor technology for the upscaled production of commercially feasible APIs. © 2024 The Institution of Chemical Engineers
Aluminising of mild steel using Al-11Si-1.2Cu baths
(2013) Shashibhushan Raju, M.; Prashanth, H.; Bhat, K.
Hot-dip aluminising of mild steel was done using Al-11Si-1.2Cu (at %) bath at 750°C for dipping time ranging from 300 to 3600 seconds. Aluminised layer was investigated using scanning electron microscope and energy dispersive spectroscopy. The intermetallic layer consisted of 4 distinct layers, namely, ?5-(Al7Fe2Si), ?-FeAl3, ?-Fe2Al5 and ?1-(Al,Si)5Fe3. Total intermetallic layer thickness was following parabolic growth kinetics with time. Total thickness was increasing predominantly due to increase in Fe2Al5 layer, which itself was following parabolic growth behaviour. Total intermetallic layer thickness was smaller compared to intermetallic layer thickness reported using pure aluminium or aluminium silicon baths. © 2013 CAFET-INNOVA TECHNICAL SOCIETY.
Binder free MoO3/multiwalled carbon nanotube thin film electrode for high energy density supercapacitors
(2013) Aravinda, L.S.; Bhat, K.; Badekai Ramachandra, B.
MoO3/multiwalled carbon nanotube (MWCNT) composites were prepared by Magnetron sputtering in Ar/O2 atmosphere. This will provide a greener alternative for the fabrication of binder free composite electrode for supercapacitor applications. MWCNT provides good support for the growth of MoO3 thin films. This integrated composite electrode exhibited specific capacitance of 93 F g-1 and a corresponding energy density of 7.28 Wh kg-1 in non-aqueous electrolyte, which is almost fourfold increase compared to the bare MWCNT. Also the electrode maintains high power density of 4930 W kg-1 at high current rates, suggesting a potential energy storage material for portable and consumer electronics. © 2013 Elsevier Ltd. All rights reserved.
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. Â© (2015) Trans Tech Publications, Switzerland.
Combating corrosion degradation of turbine materials using HVOF sprayed 25% (Cr3C2-25(Ni20Cr)) + NiCrAlY coating
(2013) Jegadeeswaran, N.; Ramesh, M.R.; Bhat, K.
High velocity oxy fuel process (HVOF) is an advanced coating process for thermal spraying of coatings on to components used in turbines. HVOF process is a thermal spray coating method and is widely used to apply wear, erosion, and corrosion protective coatings to the components used in industrial turbines. 25% (Cr3C2-25(Ni20Cr)) + NiCrAlY based coatings have been sprayed on to three turbine materials, namely, Ti-31, Superco-605, and MDN-121. Coated and uncoated substrates were subjected to hot corrosion study under cyclic conditions. Each cycle consisted of 1 hour heating at 800°C followed by 20 minutes air cooling. Gravimetric measurements were done after each cycle and a plot of weight gain as a function of number of cycles is drawn. Parabolic rate constants were estimated for the understanding of corrosion behaviour. It was observed that coated Ti-31 and MDN-121 were more resistant compared to the uncoated ones. Uncoated superco-605 was undergoing sputtering during corrosion study and hence comparison between coated and uncoated superco-605 was difficult. The cross-sectional analysis of the corroded, coated samples indicated the presence of a thin layer of chromium oxide scale on the top of the coating and it imparted better corrosion resistance. Parabolic rate constants also indicated that coating is more beneficial to Ti-31 than to MDN-121. © 2013 N. Jegadeeswaran et al.
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. Â© (2012) Trans Tech Publications.
Effect of substrate temperature on the characteristics of ZnO films produced by a combination of thermal vapor deposition and oxidation processes
(Springer New York LLC barbara.b.bertram@gsk.com, 2017) Sneha, C.; Prabukumar, C.; Jayalakshmi, M.; Bhat, S.; Bhat, K.
In the present work, ZnO semiconductor films were prepared by following two step processes, namely, thermal vapor deposition of the zinc on the glass substrate followed by oxidative annealing. Substrate temperature during deposition of the zinc was varied. Structural properties and morphology of the ZnO films were investigated by using X-ray diffraction and scanning electron microscopy techniques. Hydrophobic nature of the film was confirmed by using contact angle analyser. Hall measurements facilitated the estimation of the carrier concentration, their mobility and their effect on the conductivity. Photoluminescence spectroscopy was used to analyse the lattice defect concentration in the film. Further, the sensor response of the ZnO film to CO gas was analysed. Sensor fabricated with ZnO films which were prepared by oxidizing Zn films deposited at higher substrate temperature were found to possess better response and faster response-recovery time than the film prepared using lower substrate temperature for zinc deposition. © 2017, Springer Science+Business Media, LLC.
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 Î¼m to 8 Î¼m, 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. Â© (2015) Trans Tech Publications, Switzerland.
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 Î¼m. 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 Â°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. Â© (2015) Trans Tech Publications, Switzerland.
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 Â°C for 30 seconds. The samples were further heat treated at 750 Â°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. Â© (2015) Trans Tech Publications, Switzerland.
Layered coating of Zn-Co alloys on mild steel using triangular current pulses for better corrosion protection
(2013) Bhat, S.R.; Bhat, K.; Hegde, A.C.
Cyclic multilayer alloy (CMA) coatings of Zn-Co were electrodeposited on to mild steel (MS) from acid sulphate bath having thiamine hydrochloride and citric acid as additives. Depositions were carried out galvanostatically from a single bath containing Zn+2 and Co+2 ions. The triangular current pulses cycling between two cathode current densities were used for gradual change in composition in each layer. CMA coatings were developed under different sets of cathode current densities and number of layers, their corrosion resistances were evaluated by potentiodynamic polarization and Electrochemical Impedance Spectroscopy method, results were compared with that of monolayer Zn-Co alloy coatings. At optimal configuration, CMA coating represented as (Zn-Co)3.0/5.0/300 was found to exhibit ∼11 times better corrosion resistance compared to monolayer, (Zn-Co)4.0, deposited for same length of time from same bath. The formation of layered and corrosion mechanism was analyzed using Scanning Electron Microscopy. The corrosion protection of layered coatings of Zn-Co alloy was attributed to the different phase structure of the alloys in alternate layers, evidenced by XRD analysis. © 2013 Indian Institute of Metals.
Magnetron sputtered MoO3/carbon nanotube composite electrodes for electrochemical supercapacitor
(Elsevier B.V., 2013) Aravinda, L.S.; Nagaraja, K.K.; Bhat, K.; Badekai Ramachandra, B.
Molybdenum oxide (MoO3) has been deposited on multiwalled carbon nanotubes (MWCNTs) using DC reactive magnetron sputtering of molybdenum for supercapacitor applications. The deposits of MoO3 have been developed under different intervals of time. The structure and surface morphology of the deposits have been characterized by means of X-ray diffraction (XRD) analysis and field emission scanning electron microscopy (FESEM). X-ray diffraction peaks of the composite films reveal the formation of crystalline structure of MoO3. The electrochemical performance of the composite films was studied using cyclic voltammetry (CV), galvanostatic charge discharge and electrochemical impedance spectroscopy measurements. The composite film exhibits maximum specific capacitance of 70 F g-1 at a scan rate of 10 mV s-1 in 1 M Na2SO4 electrolyte. The nanocomposite electrode material shows specific capacitance which is almost four fold increase with respect to that of bare MWCNTs. The effect of coating duration on specific capacitance has been studied. The nanocomposite film is found to display good cycleability, even up to 1000 cycles. © 2013 Elsevier Inc. All rights reserved.
Mechanical and sliding wear properties of multi-layered laminates from glass fabric/graphite/epoxy composites
(Elsevier Ltd, 2013) Shivamurty, B.; Bhat, K.; Anandhan, S.
Multi-layered laminates of bi-directionally woven E-glass fabric/epoxy with different loading of graphite particles were made by hand layup followed by compression molding. Tensile and flexural behaviors, impact strength, hardness and density of these laminates were determined. Wear behaviors of these composites were investigated by a pin-on-disc wear test apparatus. Specific wear rates of these composites strongly depend on their filler content and applied normal loads. The hybrid composite containing 3 wt% of graphite exhibits the optimum mechanical and wear performances. A further increase in the graphite content increases the specific wear rate and deteriorates the mechanical behavior. The lowest (? e)-1 factor (the reciprocal of the product of tensile strength and elongation at break) signifies the lowest specific wear rate. The results of the morphology study of the wear test specimens support the results of the wear test. © 2012 Elsevier Ltd.
Nano CeO2/activated carbon based composite electrodes for high performance supercapacitor
(2013) Aravinda, L.S.; Bhat, K.; Badekai Ramachandra, B.
Cerium oxide (CeO2)/Activated carbon (AC) based composite were prepared by simple mechanical mixing method with high degree of scalability. The samples were characterized using X-ray diffraction (XRD), Field emission scanning electron microscope (FESEM) and Transmission electron microscope (TEM). The composite mixture with 10 wt% (weight %) CeO2 exhibits a specific capacitance of 162 F g-1 in two electrode configuration. The test cell retains 86% specific capacitance even at high current density with excellent cycle stability. The composite electrode exhibits a power density of 3500 W kg-1 at a high current density, suggesting a good electrode material for supercapacitor. © 2013 Elsevier B.V. All rights reserved.
Organoclay enabled nanofiber formation from a polyolefin elastomer
(John Wiley and Sons Inc. P.O.Box 18667 Newark NJ 07191-8667, 2018) Kumar, B.; Prakrthi, A.N.; Senthil, T.; Bhat, K.; Anandhan, S.
The solution electrospinning of polyolefins has not been deeply studied mainly due to the difficulty in dissolving these polymers in appropriate solvents. In this study, composite nanofibers of organically modified montmorillonite/ethylene-octene random copolymer were produced for the first time with a mixture of cyclohexane and xylene as a solvent by solution electrospinning. Montmorillonite was used as an additive to increase the electrical charge density of the polymer solution. The influence of solution and process parameters on the electrospun ethylene-octene copolymer fibers' morphology and diameter was investigated using the design of experiment. Multiple regression analysis was used for the optimization of the electrospinning parameters. Ultrafine fibers, with diameters in the range of 150–350 nm were obtained; these nanofibers exhibited an excellent hydrophobicity over a period of 10 min as revealed by contact angle measurements. © 2016 Wiley Periodicals, Inc.
Porous MnO2 nano whiskers bunch/activated carbon based composite electrodes for high energy density supercapacitor
(2013) Aravinda, L.S.; Bhat, K.; Badekai Ramachandra, B.
A simple room temperature method was used to synthesize Porous ?-MnO2 nano whiskers bunch. The porous ?-MnO2 /Activated carbon (AC) composites were prepared by very simple mechanical mixing method with varying amount of MnO2. A symmetric supercapacitor stack was fabricated using the prepared composite electrode material. The composite with 30% MnO2 exhibit a maximum specific capacitance of 107 Fg-1 at 1 mAcm-2 in non-aqueous electrolyte. The corresponding energy density was found to be 8.35 Whkg-1. The electrode also exhibits excellent cyclic stability. © 2013 The Electrochemical Society.
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. Â© (2012) Trans Tech Publications.
Synthesis, Characterization, Thermal and Antimicrobial studies of N-substituted Sulfanilamide derivatives
(2014) Lahtinen, M.; Kudva, J.; Hegde, P.; Bhat, K.; Kolehmainen, E.; Nonappa; Venkatesh; Naral, D.
Four sulfanilamide derivatives N-[4-(phenylsulfamoyl)phenyl]acetamide (1), 4-amino-N-phenylbenzenesulfonamide (2), N-[4-(phenylsulfamoyl)phenyl]benzamide (3) and N-{4-[(3-chlorophenyl)sulfamoyl]phenylbenzamide (4) were synthesized and characterized by Infra-Red (IR), Nuclear Magnetic Resonance (NMR) and UV-visible (UV-Vis) spectra. Also Liquid Chromatographic (LCMS) and High Resolution Mass Spectrometric (HRMS) methods were used. Crystal structures of 1-4 were determined by single crystal X-ray diffraction (XRD) and their conformational and hydrogen bond (HB) network properties were examined with survey of the literature data. Compounds 1 and 2 crystallize in the same orthorhombic Pbca symmetry with equivalent molecular conformation (tilted V-shape) but showed distinct packing and hydrogen bonding models. Compounds 3 and 4 crystallize in monoclinic and triclinic crystal systems, albeit exhibiting identical molecular conformation (L-shaped). Same donor acceptor pairs both on 3 and 4 result to different kind of HB network. Thermogravimetric (TG) and differential scanning calorimetric (DSC) methods were used to evaluate thermal properties of the substances. All sulfanilamide derivatives have melting points between195-227 C, initiation of thermal decomposition between 259-271 C and enthalpies of fusion ?HfusT = 38.96, 36.60, 46.23 and 44.81 kJ mol -1 were determined for 1-4, respectively. The derivatives were screened for their antibacterial and antifungal activities against various bacterial and fungal strains. It is observed that there is no significant antibacterial activity with the introduction of the benzene ring to CO-NH group or SO2-NH moiety, and none of the compounds exhibited antifungal activity. 2013 Elsevier B.V. All rights reserved.
Synthesis, Characterization, Thermal and Antimicrobial studies of N-substituted Sulfanilamide derivatives
(2014) Lahtinen, M.; Kudva, J.; Hegde, P.; Bhat, K.; Kolehmainen, E.; Nonappa, N.; Venkatesh; Naral, D.
Four sulfanilamide derivatives N-[4-(phenylsulfamoyl)phenyl]acetamide (1), 4-amino-N-phenylbenzenesulfonamide (2), N-[4-(phenylsulfamoyl)phenyl]benzamide (3) and N-{4-[(3-chlorophenyl)sulfamoyl]phenylbenzamide (4) were synthesized and characterized by Infra-Red (IR), Nuclear Magnetic Resonance (NMR) and UV-visible (UV-Vis) spectra. Also Liquid Chromatographic (LCMS) and High Resolution Mass Spectrometric (HRMS) methods were used. Crystal structures of 1-4 were determined by single crystal X-ray diffraction (XRD) and their conformational and hydrogen bond (HB) network properties were examined with survey of the literature data. Compounds 1 and 2 crystallize in the same orthorhombic Pbca symmetry with equivalent molecular conformation (tilted V-shape) but showed distinct packing and hydrogen bonding models. Compounds 3 and 4 crystallize in monoclinic and triclinic crystal systems, albeit exhibiting identical molecular conformation (L-shaped). Same donor acceptor pairs both on 3 and 4 result to different kind of HB network. Thermogravimetric (TG) and differential scanning calorimetric (DSC) methods were used to evaluate thermal properties of the substances. All sulfanilamide derivatives have melting points between195-227 C, initiation of thermal decomposition between 259-271 C and enthalpies of fusion ?HfusT = 38.96, 36.60, 46.23 and 44.81 kJ mol -1 were determined for 1-4, respectively. The derivatives were screened for their antibacterial and antifungal activities against various bacterial and fungal strains. It is observed that there is no significant antibacterial activity with the introduction of the benzene ring to CO-NH group or SO2-NH moiety, and none of the compounds exhibited antifungal activity. © 2013 Elsevier B.V. All rights reserved.
ZnO/carbon nanotube nanocomposite for high energy density supercapacitors
(2013) Aravinda, L.S.; Nagaraja, K.K.; Nagaraja, H.S.; Bhat, K.; Badekai Ramachandra, B.
A facile, green and highly efficient method for the decoration of carbon nanotubes with ZnO was developed for the fabrication of binder-free composite electrode for supercapacitor applications. The nano composite was prepared by using reactive magnetron sputtering in Ar/O2 environment. This approach leads to more uniform coating with tuneable thickness, which alters the electrochemical performance of the nano composite electrodes. The structure and surface morphology of the composite film have been studied by means of X-ray diffraction (XRD) analysis, scanning electron microscopy and field emission scanning electron microscopy (FESEM). The XRD study reveals the formation of Wurtzite ZnO structure. The electrochemical performance of nano composite electrode was investigated using cyclic voltammetry, chronopotentiometry and electrochemical impedance measurements in non-aqueous electrolyte. The nano composite electrode shows significant increase in the specific capacitance up to 48 F g-1 with an energy density 13.1 Wh kg-1 in the potential range -2 V to 1 V. © 2013 Elsevier Ltd. All rights reserved.