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ABSTRACT: In the current study, TiN–MoS
x
composite coatings were deposited by co-sputtering of MoS2 and Ti targets under a mixture of Ar and N2 gas environment using pulsed DC closed-field unbalanced magnetron sputtering. The tribological response of TiN–MoS
x
composite coatings was studied against two different counter bodies: cemented carbide (WC–6% Co) ball and pin made of aluminium
alloy (AlSiMg). First, the effect of substrate bias was studied on tribological properties using cemented carbide ball. Lowest
coefficient of friction in the range of 0.03–0.04 was obtained for the specimen deposited at a substrate bias of −60V. Wear
coefficient was also found to be minimum for the same specimen. Coatings were further deposited at an optimum bias of −60V
in order to vary MoS
x
content of TiN–MoS
x
composite coating. Effect of variation of chemical composition of the coating was then studied on tribological performance
of the coating against aluminium alloy counterface. Excellent anti-sticking property of MoS
x
was found to have enabled the TiN–MoS
x
composite coating to achieve considerably low coefficient of friction against aluminium alloy. It was shown that with optimum
MoS
x
content of TiN–MoS
x
composite coating, it was possible to attain as low coefficient of friction as 0.09 against aluminium alloy even under normal
atmospheric condition.
KeywordsSelf-lubricating composite-Molybdenum disulphide-Solid lubrication friction-Solid lubricated wear-Non-ferrous alloy-Hardness-SEM-EDS
Tribology Letters 04/2012; 37(3):487-496. · 1.58 Impact Factor
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ABSTRACT: Here we describe the superiority of Bessel function as base function for radial expansion over Zernicke polynomial in the
tomographic reconstruction technique. The causes for the superiority have been described in detail. The superiority has been
shown both with simulated data for Kadomtsev’s model for saw-tooth oscillation and real experimental x-ray data from W7-AS
Stellarator.
Pramana 04/2012; 61(1):141-152. · 0.57 Impact Factor
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Materials and Manufacturing Processes 01/2011; 26:982-990. · 1.06 Impact Factor
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International Journal of Advanced Manufacturing Technology 01/2011; 57:927–943. · 1.10 Impact Factor
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Surface and Coatings Technology 01/2010; 205:658–667. · 1.87 Impact Factor
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Surface and Coatings Technology. 01/2010; 205:658–667.
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Surface and Coatings Technology. 01/2010; 204:3818–3832.
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Wear 01/2010; 268:1053–1065. · 1.87 Impact Factor
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Surface and Coatings Technology 01/2010; 204:3818–3832. · 1.87 Impact Factor
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ABSTRACT: An x-ray imaging system for tomographic reconstruction of two-dimensional emissivity is being developed for the SST-1 tokamak. In this article it is shown that for circular plasma, which will be generated in the first phase of operation of the machine, 7 arrays and 115 detectors are adequate to reconstruct the simulated data. Sawtooth phenomena depicted by both the Wesson model and the Kadomtsev model and the disruption phenomenon associated with m=2 mode are reconstructed well with the help of this imaging system. © 2003 American Institute of Physics.
Review of Scientific Instruments 03/2003; 74(4):2353-2356. · 1.37 Impact Factor
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ABSTRACT: Photocatalytic reduction of two textile azo dyes, Naphthol Blue Black (NBB) and Disperse Blue 79 (DB79) has been carried out
in colloidal WO3 and TiO2 suspensions. Under bandgap excitation of the semiconductor colloids these dyes undergo irreversible reduction as they react
with the trapped electrons. The quantum efficiency for the photocatalytic reduction of these dyes were 5.4% and 4.8% for NBB
and DB79 respectively. The kinetics and mechanism of the interfacial charge transfer in these colloidal suspension has been
elucidated with transient absorption spectroscopy. The reaction between the dye and trapped electrons is diffusion limited
and occurs with rate constants of 1.1×108 M−1s−1 and 4.0×107 M−1s−1 for NBB and DB79 respectively.
Research on Chemical Intermediates 04/1997; 23(3):219-231. · 0.70 Impact Factor
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ABSTRACT: The absorption and fluorescenc of 9-chloro-10,10′-bis-(dichloromethyleno)-(9′H)-10,10′-dihydro-9,9′-bianthryl (CDDB) has been studied in polar and nonpolar solvents and also in
microcrystal. In polar solvents CDDB emits from two molecular forms, the normal charge transfer form (locally excited, LE
form) and the solvent-induced twisted intramolecular charge transfer (TICT) form. Electrically, CDDB possesses semiconducting
property with conductivity approximately 10−9 S cm−1 and this conductivity further increases to 10−7 S cm−1 on photoexcitation. Intramolecular charge transfer by hopping mechanism is assumed to be the main process for controlling
activation energy and electronic conduction.
Bulletin of Materials Science 05/1993; 16(4):287-296. · 0.88 Impact Factor
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ABSTRACT: An investigation has been carried out to gain information about the capabilities of some filler alloys for direct brazing of CBN (cubic boron nitride) grits to a steel substrate. It has been found that a Ni-Cr alloy, known for effective diamond brazing, failed to show satisfactory wetting and bonding characteristics towards CBN under the same brazing conditions as that of diamond. The situation could not be improved either by increasing the wt% of Cr or the brazing temperature. Also, prolongation of the brazing time did not show any significant change. It was further revealed that a Ag-Cu-Ti alloy, which is well established for the brazing of diamond and ceramics, exhibited good wetting and bonding towards CBN at moderate temperature. Based on the thermodynamic properties of various materials, characteristic properties of elements of group IV B to VI B and the physical observations made during the investigation, it is suggested that the transition elements of group IV B, such as Ti or Zr, are preferred to transition elements of group VI B, such as Cr, as an activator to promote the wetting characteristics of the braze alloy towards CBN, which is far more chemically stable than diamond.
Journal of Materials Science 12/1992; 28(21):5887-5893. · 2.02 Impact Factor
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ABSTRACT: In recent years direct brazing of a monolayer of diamond crystals on a steel substrate with active filler metals has gained tremendous importance in the industry, with a view to developing tools which can out-perform the conventional galvanically bonded diamond tools. An existing proprietary process uses a specially prepared Ni-Cr filler metal to facilitate its application on a steel substrate. The brazing is done either in a vacuum or a dry hydrogen furnace. The present study has shown that a commercially available Ni-Cr hardfacing alloy, flame-sprayed on a steel substrate with an oxyacetylene gun, could be used for direct brazing of diamond particles. Induction brazing was carried out in an argon atmosphere only for short durations. During brazing under such conditions, the chromium present in the alloy segregated preferentially to the interface with diamond to form a chromium-rich reaction product promoting the wettability of the alloy. It has been further revealed that under a given set of brazing conditions, the wettability of the Ni-Cr hardfacing alloy towards diamond grits primarily depended on its layer thickness. Such dependence resulted in significant variation of topographical features of the tool and its wear mode in simulated grinding tests.
Journal of Materials Science 12/1990; 26(18):5093-5100. · 2.02 Impact Factor
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ABSTRACT: In recent years, in many applications, brazed bonded single layer diamond tools are getting preference over galvanically bonded counterpart because of their outstanding performance. High crystal exposure is reported to be one of the most distinguished features of the brazed tool. The present study, however, has revealed that commercially fabricated brazed tools do not necessarily provide high crystal exposure as claimed by the manufacturer because of accumulation of bonding material in the space between the grits during brazing. Performance of such commercially manufactured wheels, relative to that of brazed tools fabricated according to CSEM's new process, with improved uniformity of bond level and grit protrusion, is reported in this paper. Oxide ceramic and cast iron were used as work materials during grinding experiments.
CIRP Annals - Manufacturing Technology 40(1):347-350. · 1.71 Impact Factor
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ABSTRACT: In the present work, an attempt has been made to modify the surface of diamond and CBN grits in order to enhance their adhesion with the metal matrix. Chromium CVD process was used for this purpose. SEM and EPMA studies have shown that the type of chemical reagents, deposition time. deposition temperature and the type of abrasive grit substrate could influence the morphology and composition of the film deposited. Such surface modification was found to be more effective for diamond than for CBN in improving wettability and bondability of the Ni-based matrix. This was confirmed by improved retentivity of the diamond grits in the Ni-based matrix during simulated grinding test.
CIRP Annals - Manufacturing Technology 41(1):381-385. · 1.71 Impact Factor
