Laser and Plasma Technology Division

BARC, India

Laser and Plasma Technology Division

BARC, India
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Bhuyan S.K.,National Institute of Technology Rourkela | Thiyagarajan T.K.,Laser and Plasma Technology Division | Mishra S.C.,National Institute of Technology Rourkela
IOP Conference Series: Materials Science and Engineering | Year: 2017

The technological advancement in modern era has a boon for enlightening human life; but also is a bane to produce a huge amount of (industrial) wastes, which is of great concern for utilization and not to create environmental threats viz. polution etc. In the present piece of research work, attempts have been made to utilize fly ash (wastes of thermal power plants) and along with alumina bearing ore i.e. bauxite, for developing plasma spray ceramic coatings on metals. Fly ash and with 10 and 20% bauxite addition is used to deposit plasma spray coatings on a metal substrate. The surface morphology of the coatings deposited at different power levels of plasma spraying investigated through SEM and EDS analysis. The coating thickness is measured. The porosity levels of the coatings are evaluated. The coating hardness isalso measured. This piece of research work will be beneficial for future development and use of industrial waste and ore minerals for high-valued applications. © Published under licence by IOP Publishing Ltd.

Satapathy A.,National Institute of Technology Rourkela | Mishra D.,Sambalpur University | Patnaik A.,National Institute of Technology Hamirpur | Sreekumar K.P.,Laser and Plasma Technology Division
Tribology Transactions | Year: 2010

This article proposes the application of an artificial neural network (ANN) to a Taguchi orthogonal experiment to develop a robust and efficient method of analyzing and predicting the solid particle erosion wear response of a new class of metal-ceramic coatings. An ANN model based on data obtained from experiments performs self-learning by updating weightings and repeated learning epochs. In this work, plasma-sprayed coatings of fly ash premixed with aluminum powder in different weight proportions are deposited on aluminum substrates at various input power levels of the plasma torch. Erosion wear characteristics of these coatings are investigated following a plan of experiments based on the Taguchi technique, which is used to acquire the erosion test data in a controlled way. The study reveals that the impact velocity is the most significant among various factors influencing the wear rate of these coatings. An ANN approach is then implemented taking into account training and test procedure to predict the tribo-performance under different erosive wear conditions. This technique helps in saving time and resources for a large number of experimental trials and successfully predicts the wear rate of the coatings both within and beyond the experimental domain. © Society of Tribologists and Lubrication Engineers.

Kakati M.,Dibrugarh University | Das A.K.,Laser and Plasma Technology Division
Journal of Plasma Physics | Year: 2010

The distribution of temperature in an expanded thermal plasma jet is investigated by modified Langmuir probes. The validation of classical probe theory in the entire experimental chamber pressure range of 10-100 mbar is thoroughly established before the measurements. The average temperature of the plasma jet at the nozzle exit was also measured by calorimetric estimation of total heat loss from the plasma upstream of that point. A correlation is made using simple analytical expression in between the average temperature measured from the heat loss data and the centerline temperature at the nozzle exit measured by Langmuir probe. The profile parameter n for the radial distribution of temperature in a plasma jet is calculated for different operating current and gas flow rates. Copyright © Cambridge University Press 2010.

Punjabi S.B.,V. J.T.I | Punjabi S.B.,University of Mumbai | Mangalvedekar H.A.,V. J.T.I | Lande B.K.,V. J.T.I | And 2 more authors.
Physics of Plasmas | Year: 2012

A numerical study is done to understand the possible operating regimes of RF-ICP torch (3 MHz, 50 kW) using different gases for plasma formation at atmospheric pressure. A two dimensional numerical simulation of RF-ICP torch using argon, nitrogen, oxygen, and air as plasma gas has been investigated using computational fluid dynamic (CFD) software fluent. The operating parameters varied here are central gas flow, sheath gas flow, RF-power dissipated in plasma, and plasma gas. The temperature contours, flow field, axial, and radial velocity profiles were investigated under different operating conditions. The plasma resistance, inductance of the torch, and the heat distribution for various plasma gases have also been investigated. The plasma impedance of ICP torch varies with different operating parameters and plays an important role for RF oscillator design and power coupling. These studies will be useful to decide the design criteria for ICP torches required for different material processing applications. © 2012 American Institute of Physics.

Panda A.B.,Birla Institute of Technology | Mahapatra S.K.,Birla Institute of Technology | Barhai P.K.,Birla Institute of Technology | Das A.K.,Laser and Plasma Technology Division | And 2 more authors.
Applied Surface Science | Year: 2012

Nanostructured TiO 2 thin films were deposited using RF reactive magnetron sputtering at different O 2 flow rates (20, 30, 50 and 60 sccm) and constant RF power of 200 W. In situ investigation of the nucleation and growth of the films was made by Optical Emission Spectroscopy (OES). The nano amorphous nature as revealed from X-ray diffraction (XRD) of the as deposited films and abundance of the Ti 3+ surface oxidation states and surface hydroxyl group (OH -) in the films deposited at 50 sccm as determined from X-ray photo electron spectroscopy (XPS) was explained on the basis of emission spectra studies. The increase in band gap and decrease in particle size with O 2 flow rate was observed from transmission spectra of UV-vis spectroscopy. Photoinduced hydrophilicity has been studied using Optical Contact Angle (OCA) measurement. The post irradiated films showed improved hydrophilicity. The bactericidal efficiency of these films was investigated taking Escherichia coli as model bacteria. The films deposited at 50 sccm shows better bactericidal activity as revealed from the optical density (OD) measurement. The qualitative analysis of the bactericidal efficiency was depicted from Scanning Electron Microscope images. A correlation between bactericidal efficiency and the deposited film has been established and explained on the basis of nucleation growth, band gap and hydrophilicity of the films. © 2012 Elsevier B.V.

Mullick S.,Indian Institute of Technology Kharagpur | Madhukar Y.K.,Indian Institute of Technology Kharagpur | Roy S.,Indian Institute of Technology Kharagpur | Kumar S.,Laser and Plasma Technology Division | And 2 more authors.
International Journal of Machine Tools and Manufacture | Year: 2013

The conventional underwater laser cutting process usually utilizes a high pressure gas jet along with the laser beam to create a dry condition in the cutting zone and eject out the molten material. This causes a lot of gas bubbles and turbulence in water, and produces aerosols and waste gas. This may cause contamination in the surrounding atmosphere, while cutting the radioactive components. In order to minimize this effect, a water-jet assisted underwater laser cutting technique has been developed using a high power fiber laser. A high velocity coaxial water-jet has been employed in place of gas-jet to remove the molten material through the kerf. Some amount of water vapour bubbles is formed at the laser-metal-water interface; however, they tend to condense as they rise up through the surrounding water. AISI 304 stainless steel sheet of maximum 1.5 mm thickness was cut at 1.4 m/min cutting speed with the present setup at 1800 W CW laser power, and the resulting average kerf-width was about 0.75 mm. The heat convection by water jet and the scattering of laser beam by vapour were found to influence significantly the energy efficiency of the cutting process. The effects of various processing parameters on the cutting performance were investigated. The energy efficiency improved at higher cutting speeds. An energy balance model with various loss mechanisms included has been also developed. © 2013 Elsevier Ltd.

Mullick S.,Indian Institute of Technology Kharagpur | Madhukar Y.K.,Indian Institute of Technology Kharagpur | Kumar S.,Laser and Plasma Technology Division | Shukla D.K.,Reactor Operation Divisions | Nath A.K.,Indian Institute of Technology Kharagpur
Applied Optics | Year: 2011

Absorption of CW Yb-fiber laser light of 1.07μm wavelength in water has been measured at different water temperatures and laser intensities. The absorption coefficient was estimated to be 0.135 cm-1 at 25°C water temperature, and this was found to decrease with temperature at a rate of 5.7 × 10-4 cm-1 °C-1. The absorption coefficient increased significantly when the laser beam was focused in water, and the increase depended on the distance of the focal point from the water surface. This has been attributed to the absorption and scattering losses of laser radiation in a cavity formed in water by the focused beam at laser intensities in the megawatts per square centimeter and higher range. © 2011 Optical Society of America.

Madhukar Y.K.,Indian Institute of Technology Kharagpur | Mullick S.,Indian Institute of Technology Kharagpur | Shukla D.K.,Reactor Operation Division | Kumar S.,Laser and Plasma Technology Division | Nath A.K.,Indian Institute of Technology Kharagpur
Applied Surface Science | Year: 2013

The laser paint removal behavior with the continuous wave (CW) beam and repetitive pulses has been investigated using an Yb:fiber laser. The specific energy, which is defined as the amount of laser energy needed to remove unit volume of paint prior to the onset of substrate damage and is a measure of the process efficiency, was found to be dependent on the laser processing parameters. In CW mode the specific energy reduced with the increase of laser scan speed and corresponding increase of laser power. In case of repetitive pulsed mode the specific energy was found to depend on the pulse on-time as well as on the time interval between two successive pulses. At 1 kHz repetition rate, the specific energy reduced with the increase of duty cycle and corresponding increase in scanning speed, but at relatively low frequencies of 50-150 Hz and 50% overlap between two pulses specific energy was found to increase with increasing duty cycle. Irrespective of the mode of operation specific energy increased with the increase of average line energy. During the laser paint irradiation a plume of burning fume was formed over the surface and the variation in specific energy with laser processing parameters has been attributed to the absorption of laser radiation in the plume. Since the dimension of plume and fume particle density in it will depend on the laser energy absorbed in paint, the absorption loss in plume will depend on the laser parameters. This was confirmed by measuring the plume temperature for different laser processing conditions. Based on this and considering that the actual specific energy absorbed by paint should be constant, the absorption characteristic of plume was modeled applying Beer Lambert's law. © 2012 Elsevier B.V. All rights reserved.

Tank C.M.,University of Pune | Sakhare Y.S.,University of Pune | Kanhe N.S.,University of Pune | Nawale A.B.,University of Pune | And 3 more authors.
Solid State Sciences | Year: 2011

The paper emphasizes the effect of electric field on photocatalytic efficiency of nanoparticles of TiO2 (nano TiO2). The effect was observed by applying electric field to nano TiO2 during the photocatalytic degradation process of methylene blue. Porous silicon was used as a template to immobilize the nano TiO2 and to facilitate the application of electric field. Nano TiO2, having an average particle size of 15 nm, was synthesized by thermal plasma assisted gas phase condensation. A critically selected negative bias potential, applied on the catalyst with reference to the solution, is shown to enhance the photocatalytic efficiency by 18%. The observed effect is explained on the basis of band movements at the TiO2/solution interface. Band movement influences the oxidation and reduction reactions at the interface and thus controls the photocatalytic degradation. © 2011 Elsevier Masson SAS. All rights reserved.

Suri B.M.,Laser and Plasma Technology Division
Springer Proceedings in Physics | Year: 2015

Classical high-resolution spectroscopy had been of interest for the sake of studies related to isotope shifts and hyperfine interactions and for resolving complex spectra associated with heavy elements like lanthanides and actinides. In this chapter, some of the history of classical high-resolution spectroscopy has been described. The highest-resolution laser spectroscopy is usually performed with CW lasers which have inherent ultra-narrow linewidths. Pulsed dye lasers though have relatively large linewidth because of Fourier transform limit but can still be usefully employed for multicolor laser spectroscopy of various elements with complex spectra. We have demonstrated the utility of pulsed dye lasers for studying lanthanides and actinides by employing techniques like multicolor optogalvanic spectroscopy in hollow cathode discharges, multicolor laser-induced fluorescence, and resonance ionization spectroscopy in atomic beams. We have for the first time utilized ICCD-based spectrograph for some of the measurements. These techniques have yielded excellent new information on atomic parameters like radiative lifetimes, branching ratios, and absolute transition probabilities of singly or multiply excited atomic levels. These techniques have inherent simplicity and may offer themselves as excellent alternative to conventional techniques and have universal applications of interest to wide cross section of atomic spectroscopists. © Springer India 2015.

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