Thermal System Group

Bhubaneshwar, India

Thermal System Group

Bhubaneshwar, India
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Bandyopadhyay P.,Indian Central Glass and Ceramic Research Institute | Dey A.,Indian Central Glass and Ceramic Research Institute | Dey A.,Thermal System Group | Mukhopadhyay A.K.,Indian Central Glass and Ceramic Research Institute
International Journal of Applied Glass Science | Year: 2012

Many advanced applications of glass demand fabrication of engineering parts of utmost dimensional precision which require very accurate grinding and polishing that involves controlled removal of glass. Despite the wealth of literature, however; the mechanism of material removal in glass grinding and polishing is still far from well understood. For instance, it is not known at all to what extent the mechanical properties are compromised inside a scratch groove so as to optimize the machining parameters. Therefore, to develop better understanding about the mechanism of material removal, a series of combined nanoindentation and single pass scratch experiments were conducted on a commercially available soda-lime-silica glass as a function of various normal loads (2-20 N) and scratch speeds (0.1-1 mm/s). It was found that the nanohardness and Young's modulus at the local microstructural length scale inside the scratch groove could decrease quite dramatically (~30% to 70%) depending on the combination of load and scratching speed. Further, the tribological properties, the severity and the spatial density of damage evolution were sensitive to the normal loads, scratching speeds, and tensile stresses. Extensive scanning electron microscopy leads to interesting observations on material removal mechanisms. These observations were explained by the theoretical predictions of a model for a brittle, microcracked solid. © 2012 The American Ceramic Society and Wiley Periodicals, Inc.


Chakraborty R.,Indian Central Glass and Ceramic Research Institute | Dey A.,Indian Central Glass and Ceramic Research Institute | Dey A.,Thermal System Group | Mukhopadhyay A.K.,Indian Central Glass and Ceramic Research Institute | And 6 more authors.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2012

To understand how high-strain rate, flyer-plate impact affects the nanohardness of a coarse (∼10 μm) grain, high-density (∼3.978 gm cc -1) alumina, load controlled nanoindentation experiments were conducted with a Berkovich indenter on as-sintered disks and shock-recovered alumina fragments obtained from an earlier flyer-plate shock impact study. The nanohardness of the shock-recovered alumina was much lower than that of the as-sintered alumina. The indentation size effect was severe in the shock-recovered alumina but only mild in the as-sintered alumina. Extensive additional characterization by field emission scanning electron microscopy, transmission electron microscopy, and analysis of the experimental load depth data were used to provide a new explanation for the presence of strong indentation size effect in the shock-recovered alumina. Finally, a qualitative model was proposed to provide a rationale for the whole scenario of nanoindentation responses in the as-sintered and shock-recovered alumina ceramics. © The Minerals, Metals & Materials Society and ASM International 2011.


Bandyopadhyay P.,Indian Central Glass and Ceramic Research Institute | Dey A.,Indian Central Glass and Ceramic Research Institute | Roy S.,Indian Central Glass and Ceramic Research Institute | Dey N.,Indian Central Glass and Ceramic Research Institute | And 2 more authors.
Applied Physics A: Materials Science and Processing | Year: 2012

Advanced applications of glass span the range from biomedical technology to special optical lenses to mobile phones and computers. Such advanced applications demand high-precision machining, which is like multiple single scratches occurring simultaneously on the glass surface. However, in spite of the wealth of literature on scratch deformation behavior of glass there is no significant information available on whether the nanomechanical properties are affected inside the scratch grooves. Therefore, nanoindentation experiments were deliberately conducted at a fixed load of 100 mN through the scratch grooves made at various applied normal loads (5-15 N) at a constant speed of 200 μm s -1 on polished soda-lime-silica (SLS) glass slides. The results showed that depending upon the applied normal load used to generate the scratch grooves, the nanohardness and Young's modulus inside the scratch grooves de- creased by about ∼30-60% from the corresponding data of the undamaged SLS glass due to the presence of subsurface shear deformation and microcracking as observed by optical, scanning and field emission scanning electron microscopy. A model for microcracked brittle solids was utilized to explain these results. © 2012 Springer-Verlag.


Dey A.,Thermal System Group | Mukhopadhyay A.K.,Indian Central Glass and Ceramic Research Institute
International Journal of Applied Ceramic Technology | Year: 2014

Hydroxyapatite coating was developed with high degree of crystallinity on SS316L substrate by the microplasma spraying technique. Systematic in vitro study of the coating was conducted after the immersion into the simulated body fluid for 1-14 days. Inductively coupled plasma-atomic emission spectroscopy, X-ray diffraction, Fourier transformed infrared spectroscopy, and scanning electron microscopy were utilized for physicochemical and microstructural characterizations. Nanoindentation technique employed to evaluate the nanohardness and Young's modulus of the coating at a constant load of 100 mN. Further, the tribological characteristic was also examined by microscratch testing at a ramping normal load of 10-10.6 N. © 2013 The American Ceramic Society.


Dey A.,Thermal System Group | Sinha A.,Bengal Engineering and Science University | Banerjee K.,Bengal Engineering and Science University | Mukhopadhyay A.K.,Indian Central Glass and Ceramic Research Institute
Materials Technology | Year: 2014

For bioactive prosthetic implant applications, the present work reports the tribolgical behaviour of the recently developed, microplasma (e.g. plasmatron power <1·5 kW) sprayed (MIPS) hydroxyapatite (HAp) coatings on Ti6Al4V substrates at low constant normal load, e.g. 200 mN. Conventionally, the macroplasma (e.g. plasmatron power < 25 kW) sprayed (MAPS) HAp coatings are used for such purpose. The phase analysis and microstructural studies of the HAp coatings were carried out by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. Further, the single pass scratch tests were conducted on both the bare substrates and the HAp coatings at an applied normal load of 200 mN. The average coefficient of friction (COF, μ) of the HAp coatings developed by MIPS (e.g. μ∼0·7) was slightly higher than that (e.g. μ∼0·5) of the bare Ti6Al4V substrates. The characteristic, high variability of the m data of the HAp coatings developed by MIPS; was explained in terms of the intrinsic microstructural heterogeneity and the local differences in orientations of the splats. © 2014 W. S. Maney & Son Ltd.


Dey A.,Thermal System Group | Banerjee K.,Bengal Engineering and Science University | Mukhopadhyay K.,Indian Central Glass and Ceramic Research Institute
Materials Technology | Year: 2014

Highly crystalline (∼80%) yet porous (∼20%) hydroxyapatite (HAp) coating was developed on surgical grade SS316L substrate by the microplasma spraying (MIPS) technique. Phase analysis and microstructural characterisations were carried out by X-ray diffraction, scanning electron microscopy and field emission scanning electron microscopy. Nanohardness and Young's modulus were measured by the nanoindentation technique at 100 mN load. Further, the Hap coatings were immersed in simulated body fluid (SBF) environment for 1-14 days to investigate their in vitro properties. Finally, single pass microscratch test was also conducted on the MIPSHAp coatings after immersion in SBF. © 2014 W. S. Maney & Son Ltd.


Sen P.,Variable Energy Cyclotron Center | Dey A.,Indian Central Glass and Ceramic Research Institute | Dey A.,Thermal System Group | Mukhopadhyay A.K.,Indian Central Glass and Ceramic Research Institute | And 2 more authors.
Ceramics International | Year: 2012

Bismuth ferrite (BiFeO 3) is a unique magnetoelectric multiferroic that exhibits the coexistence of ferroelectricity and antiferromagnetism at room temperature. This unique combination of properties has pumped a huge surge in current research on BiFeO 3 as a future material for very important technological applications such as magnetic detectors and as an active layer in magnetoelectric memories. For such applications involving miniaturized components and devices, it is essentially important to have an idea of the mechanical integrity of the system at the scale of the microstructure. In spite of the wealth of the literature, however, the attempt to evaluate the mechanical integrity of nano BiFeO 3 at a scale comparable with the local microstructural length scale was almost non-existent. Here we report, possibly for the first time the nanoindentation behaviour of a sol-gel process derived nano BiFeO 3 having particle size of 5-25 nm. The nanoindentation studies were conducted at 100-1000 μN loads on a green pellet annealed at a low temperature of only 300 °C to avoid particle coarsening. The results showed interesting dependence of nanohardness and Young's modulus on the nanoindentation load which could be explained in terms of elastic recovery and plastic deformation energy concepts. © 2011 Elsevier Ltd and Techna Group S.r.l. All rights reserved.


PubMed | Thermal System Group and Indian Central Glass and Ceramic Research Institute
Type: | Journal: The open biomedical engineering journal | Year: 2015

The present contribution has originated from a critical biomedical engineering issue e.g., loosening of metallic prostheses fixed with poly(methyl methylacrylate) (PMMA) bone cement especially in the case of hip joint replacement which ultimately forces the patient to undergo a revision surgery. Subsequently surgeons invented a cementless fixation technology introducing a bioactive hydroxyapatite (HAp) coating to the metallic implant surface. A wide variety of different coating methods have been developed to make the HAp coating on metallic implants more reliable; of which ultimately the plasma spraying method has been commercially accepted. However, the story was not yet finished at all, as many questions were raised regarding coating adherence, stability and bio-functionality in both in vitro and in vivo environments. Moreover, it has been now realized that the conventional high power plasma spraying (i.e. conventional atmospheric plasma spraying, CAPS) coating method creates many disadvantages in terms of phase impurity; reduced porosity limiting osseointegration and residual stresses which ultimately lead to inadequate mechanical properties and delamination of the coating. Further, poor crystallinity of HAp deposited by CAPS accelerates the rate of bioresorption, which may cause poor adhesion due to quick mass loss of HAp coatings. Therefore, in the present work a very recently developed method e.g. low power microplasma spraying method was utilized to coat HAp on SS316L substrates to minimize the aforementioned problems associated with commercial CAPS HAp coatings. Surgical grade SS316L has been chosen as the substrate material because it is more cost effective than Ti6Al4V and CoCrMo alloys.


Rai P.K.,Thermal System Group | Chikkala S.R.,Thermal System Group | Adoni A.A.,Thermal System Group | Kumar D.,Thermal System Group
Journal of Thermal Science and Engineering Applications | Year: 2015

Advances in the design and development of communication spacecraft are associated with an increase in power consumption and heat dissipation in the spacecraft. As a consequence, advanced thermal control technologies like mechanical pumped fluid loop (MPFL) are increasingly being considered for spacecraft temperature management. These technologies generally use radiative sinks (often deployable) to reject heat. Since mass is a critical parameter in space applications, mass-optimized radiator design is paramount. This paper presents semi-analytical approach to evolve design of a massoptimized space radiator panel for single-phase MPFL.


Sibin K.P.,National Aerospace Laboratories, Bangalore | Sibin K.P.,National Institute of Technology Karnataka | Swain N.,National Aerospace Laboratories, Bangalore | Chowdhury P.,National Aerospace Laboratories, Bangalore | And 6 more authors.
Solar Energy Materials and Solar Cells | Year: 2016

ITO thin films were deposited on flexible fluorinated ethylene propylene (FEP) substrates by pulsed direct current reactive magnetron sputtering system using an In:Sn (90%-10% wt.) alloy target. The influence of the deposition parameters (argon and oxygen flow rates, and substrate temperature) and effect of coating thickness on the optical, electrical, structural and microstructural properties of ITO thin films deposited on FEP was investigated. The thickness of the ITO coatings was varied from 5 to 180 nm. The optimized ITO coating (10 nm thick) exhibited high IR emittance (79%) on FEP substrate with high average solar transmittance (94.0%) and moderate sheet resistance (3 kΩ/sq.). We also investigated in detail the angular dependence of reflectance as well as haze factor of thin ITO coatings. Our results suggest that 10 nm thick ITO coating exhibits an average haze factor of 8.6%. The high value of IR emittance, moderate sheet resistance and high solar transmittance along with low haze factor indicate the suitability of ITO thin films on FEP substrates as flexible optical solar reflector for space applications. © 2015 Elsevier B.V. All rights reserved.

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