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  • 1.
    Adli, E.
    et al.
    University of Oslo, Oslo, Norway.
    Gjersdal, H.
    University of Oslo, Oslo, Norway.
    Røhne, O.M.
    University of Oslo, Oslo, Norway.
    Dorholt, O.
    University of Oslo, Oslo, Norway.
    Bang, D.M.
    University of Oslo, Oslo, Norway.
    Thomas, D,
    ESS ERIC, Lund, Sweden.
    Shea, T.
    ESS ERIC, Lund, Sweden.
    Andersson, R.
    ESS ERIC, Lund, Sweden.
    Ibison, M.G.
    University of Liverpool and Cockcroft Institute, Daresbury, UK.
    Welsch, C.P
    University of Liverpool and Cockcroft Institute, Daresbury, UK.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. University West, Department of Engineering Science, Research Enviroment Production Technology West.
    THE ESS TARGET PROTON BEAM IMAGING SYSTEMAS IN-KIND CONTRIBUTION2017In: Proceedings of IPAC2017, Copenhagen, Denmark, 2017, 3422-3425 p.Conference paper (Refereed)
  • 2. Ajay, A.
    et al.
    Raja, V. S.
    Sivakumar, G.
    Joshi, Shrikant V.
    Hot corrosion behavior of solution precursor and atmospheric plasma sprayed thermal barrier coatings2015In: Corrosion Science, Vol. 98, 271-279 p.Article in journal (Refereed)
    Abstract [en]

    Hot corrosion behavior of solution precursor plasma spray (SPPS) thermal barrier coating (TBC) in molten salt mixtures of 90wt.% Na<inf>2</inf>SO<inf>4</inf>+5wt.% V<inf>2</inf>O<inf>5</inf>+5wt.% NaCl and 50wt.% Na<inf>2</inf>SO<inf>4</inf>+50wt.% V<inf>2</inf>O<inf>5</inf> at 900°C is compared vis-à-vis atmospheric plasma spray (APS) coating. APS TBCs show better hot corrosion resistance than SPPS TBCs in both the salt mixtures. The vertical cracks in SPPS coatings, meant for strain tolerance and high thermal cycling life, serve as channels for transporting salts across the coating to bond coat/top coat interface and accelerate failure. © 2015 Elsevier Ltd.

  • 3. Archana, M. S.
    et al.
    Gundakaram, R. C.
    Rao, Y. S.
    Srikanth, Vvss
    Joshi, S. V.
    Joardar, J.
    Rapid consolidation of FeAl-Fe3AlCx ultrafine composites by mechanically activated field-assisted technique2014In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 611, 298-305 p.Article in journal (Refereed)
    Abstract [en]

    Rapid sintering of FeAl based ultrafine composites by a mechanically activated field-assisted process was evaluated. The influence of applied load and isothermal holding time on the as-sintered microstructure and mechanical properties was investigated. Hardness of the nanocomposite was determined by micro- and nano-indentation techniques, while the grain size was ascertained from electron backscatter diffraction and image analysis of scanning electron micrographs. A higher applied load as well as the isothermal holding time led to better dispersion of the in situ grown Fe3AlCx carbide particles in FeAl matrix. Significant improvement in the hardness and marginal rise in elastic constant were also observed in the fast sintered ultrafine composites when compared to previous reports. The increase in hardness was attributed to the presence of a carbide phase and fine-grained microstructure. (C) 2014 Elsevier B.V. All rights reserved.

  • 4. Archana, M. S.
    et al.
    Ramakrishna, M.
    Gundakaram, R. C.
    Srikanth, Vvss
    Joshi, S. V.
    Joardar, J.
    Nanocrystalline Phases During Mechanically Activated Processing of an Iron (Fe) Aluminum (40 at% Al) Alloy2014In: Materials and Manufacturing Processes, ISSN 1042-6914, E-ISSN 1532-2475, Vol. 29, no 7, 864-869 p.Article in journal (Refereed)
    Abstract [en]

    Influence of processing conditions on in situ generation of nanocrystalline Fe(3)AlCx and Fe-Al phases during mechanically activated annealing and sintering of Fe-40 at% Al alloy was evaluated. Fe(3)AlCx, Fe3Al and ordered FeAl phases evolved even at a low temperature of 400 degrees C. The presence of carbide phase was attributed to the free carbon originating from the organic process control agent while its formation at low temperature was correlated to fast diffusion of C in the lattice assisted by the nanocrystalline structure coupled with the presence of thermal vacancies in the Fe-40 at% Al alloy. The as-sintered composite showed improved mechanical properties.

  • 5. Archana, M. S.
    et al.
    Srikanth, Vvss
    Joshi, Shrikant. V.
    Joardar, J.
    Influence of applied pressure during field-assisted sintering of Ti(C,N)-WC-FeAl based nanocomposite2015In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 41, no 2, 1986-1993 p.Article in journal (Refereed)
    Abstract [en]

    Ti(C,N)-WC-FeAl based nanocomposites are processed by field-assisted sintering at 1500 degrees C. The phase and microstructural evolution during the process under the influence of different applied pressures of 30, 50 and 100 MPa are studied using x-ray diffraction and scanning electron microscopy. Lattice parameters of (Ti,W)(C,N) solid solution and binder phases after sintering are found to vary with applied pressure. The nanocomposite grains are observed to possess a core-rim microstructure. Microstructural variations in terms of type, size and fraction of "corerim" structure as a function of applied pressure are investigated. The hardness and indentation fracture toughness values are in the range of 17.6-18.4 GPa and 5.9-6.8 MPa root m, respectively. These values are comparable with those reported for Ti(C,N)-based composites with metal binder. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

  • 6. Aulenbach, Donald B.
    et al.
    Clesceri, Nicholas L.
    Meyer, Michael A.
    Vasundevan, Chittibabu
    Beckwith, Eileen
    Joshi, Shrikant
    Removal of heavy metals in potw using alum or sodium aluminate for phosphorus removal1984In: Proceedings of Mid-Atlantic Industrial Waste Conference, 1984, 318-330 p.Conference paper (Refereed)
    Abstract [en]

    The addition of alum or sodium aluminate at dosages which effectively remove phosphorus is beneficial in removing copper, chromium, and lead when present in wastewaters. Chromium removal is enhanced by sodium aluminate addition, but alum does not affect chromium removal. Both types of aluminum salts appear to increase the removal of lead, but the large variance in the data does not allow this to be confirmed by the t-tests. Of the remaining metals analyzed, no difference in removal was observed with and without aluminum salt addition for cadmium or antimony, nor was there any difference in TOC removal. Mercury was effectively removed to below the detection limit by primary sedimentation, so no further removal was achieved during secondary treatment when the alum/aluminate was added. Other metals were not present in amounts above detection limits.

  • 7. Aulenbach, Donald B.
    et al.
    Meyer, Michael A.
    Beckwith, Eileen
    Joshi, Shrikant
    Vasudevan, Chittibabu
    Clesceri, Nicholas L.
    Removal of Heavy Metals in Publicly Owned Treatment Works1987In: Environmental Progress, Vol. 6, no 2, 91-98 p.Article in journal (Refereed)
    Abstract [en]

    Studies were conducted at three activated sludge treatment plants during normal operation. The heavy metals were measured in the influent to each plant, the primary sedimentation effluent where applicable, the discharge after activated sludge treatment and secondary sedimentation, and in one case after a final polishing filter. Both the soluble and the total portions were measured. Beryllium, nickel, and thallium were not found in detectable levels in any of the plant influents. Mercury was found in only trace amounts. The removals of the other metals varied considerably. No consistent conclusions can be made from the data; each metal, soluble or total fraction, and unit treatment operation must be interpreted individually. The only metal in the plant effluents consistently above the recommended limit was arsenic, and this barely above the limit, and the lead content from Fitchburg, despite 83% removal.

  • 8. Aulenbach, Donald B.
    et al.
    Meyer, Michael A.
    Vaseduvan, Chittibabu
    Beckwith, Eileen
    Greaves, Kathryn
    Joshi, Shrikant
    Cleseri, Nicholas L.
    Removal of several heavy metals in potw using aluminum salts for phosphorus removal1983In: Proceedings of the Industrial Wastes Symposia, 56th Annual WPCF Conference.; Atlanta, Ga, USA; ; Code 3809, 1983Conference paper (Refereed)
  • 9. Ayyangar, N. R.
    et al.
    Joshi, S. V.
    Srinivasan, K. V.
    Puranik, V. G.
    Tavale, S. S.
    Row, T. N. G.
    Polycyclic compounds. Part III1 1 For Part II, see Ref. 2.-colour and chemical constitution of 2-aryl phenalen-1-one derivatives1986In: Dyes and Pigments, Vol. 7, no 2, 81-92 p.Article in journal (Refereed)
    Abstract [en]

    The UV-visible spectra of several 3-substituted 2-aryl phenalen-1-ones and dyes such as C.I. Disperse Red 303 which incorporate the phenalen-1-one as the basic chromophore are recorded and colour-chemical constitution aspects of these compounds have been studied. The fluorescence spectral data of C.I. Disperse Red 303 revealed that the component 1 was more fluorescent than the component 2, although 2 was more bathochromic compared with 1. The difference in the fluorescence intensity has been explained on the basis of difference in polarity of the carbonyl group brought about by the positional difference of the electron donor ring sulphur atom. Confirmation of these observations was obtained by X-ray crystallographic study of component 1 of C.I. Disperse Red 303. © 1986.

  • 10. Badgujar, A. C.
    et al.
    Dhage, S. R.
    Joshi, Shrikant V.
    Process parameter impact on properties of sputtered large-area Mo bilayers for CIGS thin film solar cell applications2015In: Thin Solid Films, Vol. 589, 79-84 p.Article in journal (Refereed)
    Abstract [en]

    Copper indium gallium selenide (CIGS) has emerged as a promising candidate for thin film solar cells, with efficiencies approaching those of silicon-based solar cells. To achieve optimum performance in CIGS solar cells, uniform, conductive, stress-free, well-adherent, reflective, crystalline molybdenum (Mo) thin films with preferred orientation (110) are desirable as a back contact on large area glass substrates. The present study focuses on cylindrical rotating DC magnetron sputtered bilayer Mo thin films on 300 mm × 300 mm soda lime glass (SLG) substrates. Key sputtering variables, namely power and Ar gas flow rates, were optimized to achieve best structural, electrical and optical properties. The Mo films were comprehensively characterized and found to possess high degree of thickness uniformity over large area. Best crystallinity, reflectance and sheet resistance was obtained at high sputtering powers and low argon gas flow rates, while mechanical properties like adhesion and residual stress were found to be best at low sputtering power and high argon gas flow rate, thereby indicating a need to arrive at a suitable trade-off during processing. © 2015 Elsevier B.V.

  • 11. Balakrishnan, A.
    et al.
    Martin, C. L.
    Saha, B. P.
    Joshi, S.
    Modelling of compaction and green strength of aggregated ceramic powders2011In: Journal of the American Ceramic Society, Vol. 94, no 4, 1046-1052 p.Article in journal (Refereed)
    Abstract [en]

    The behavior of aggregated ceramic powders is investigated using discrete element simulations. Aggregation (particles bonded by fused necks, resulting from calcination) is a common phenomenon observed during ceramic powder processing. In the present study, a small volume element of aggregated powder made of 40 spherical aggregates is modelled. Each aggregate comprises ∼500 spherical crystallites of 100 nm size. Mechanical interactions between crystallites are modelled to take into account strong bonds that form during calcination (with the possibility of breakage to model crushability), and adhesive contacts that form between submicrometer particles due to surface energy effects. The impact of having strongly bonded crystallites (high degree of calcination) or of having strongly adhesive particles (to mimic the use of a binder) is also investigated. Close die compaction and unloading from different compaction densities are carried out. It is observed that the final densification of the powder depends on the selection of process parameters like bond strength and work of adhesion between particles. This study also demonstrates a proportional relationship between the number of broken bonds in the green compacts and its strength. © 2010 The American Ceramic Society.

  • 12. Balakrishnan, A.
    et al.
    Pizette, P.
    Martin, C. L.
    Joshi, S. V.
    Saha, B. P.
    Effect of particle size in aggregated and agglomerated ceramic powders2010In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 58, no 3, 802-812 p.Article in journal (Refereed)
    Abstract [en]

    This work describes the compaction of agglomerated and aggregated ceramic powders with special emphasis on the role of primary particle size. Discrete element simulations are used to model weakly bonded agglomerates as well as strongly bonded aggregates. Crushing tests are carried out to obtain the characteristic strength of single agglomerate and aggregate. Microstructure evolution and stress-strain curves indicate that aggregates undergo a brittle to plastic-like transition as particle size decreases below 50 nm. It is shown that agglomerates made of nanoparticles exhibit much greater strength than those made of micron-sized particles, with an approximately inverse linear relationship with primary particle size. Simulation of the uniaxial compaction of a representative volume element of powder demonstrates that adhesive effects are responsible for the difficulty to compact nanopowders and for the heterogeneity of microstructure prior to sintering. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  • 13. Bandyopadhyay, S.
    et al.
    Gokhale, H.
    Sundar, J. K. S.
    Sundararajan, G.
    Joshi, S. V.
    A statistical approach to determine process parameter impact in Nd: YAG laser drilling of IN718 and Ti-6Al-4V sheets2005In: Optics and Lasers in Engineering, Vol. 43, no 2, 163-182 p.Article in journal (Refereed)
    Abstract [en]

    The numerous unique advantages afforded by pulsed Nd:YAG laser systems have led to their increasing utility for producing high aspect ratio holes in a wide range of materials. Notwithstanding the growing industrial acceptance of the technique, the increasingly tighter geometrical tolerances and more stringent hole quality requirements of modern industrial components demand that "defects" such as taper, recast, spatter etc., in laser-drilled holes are minimized. Process parameters like pulse energy, pulse repetition rate, pulse duration, focal position, nozzle standoff, type of gas and gas pressure of the assist gas are known to significantly influence hole quality during laser drilling. The present study reports the use of Taguchi design of experiments technique to study the effects of the above process variables on the quality of the drilled holes and ascertain optimum processing conditions. Minimum taper in the drilled hole was considered as the desired target response. The entire study was conducted in three phases:(a) screening experiments, to identify process variables that critically influence taper in laser drilled holes, (b) Optimization experiments, to ascertain the set of parameters that would yield minimum taper and (c) validation trials, to assess the validity of the experimental procedures and results. Results indicate that laser drilling with focal position on the surface of the material being drilled and employing low level values of pulse duration and pulse energy represents the ideal conditions to achieve minimum taper in laser-drilled holes. Thorough assessment of results also reveals that the laser-drilling process, optimized considering taper in the drilled hole as the target response, leads to very significant improvements in respect of other hole quality attributes of interest such as spatter and recast as well. © 2004 Elsevier Ltd. All rights reserved.

  • 14. Bandyopadhyay, S.
    et al.
    Sarin Sundar, J. K.
    Sundararajan, G.
    Joshi, S. V.
    Geometrical features and metallurgical characteristics of Nd: YAG laser drilled holes in thick IN718 and Ti-6Al-4V sheets2002In: Journal of Materials Processing Technology, Vol. 127, no 1, 83-95 p.Article in journal (Refereed)
    Abstract [en]

    Laser drilling is increasingly becoming the method of choice for precision drilling of a variety of components, particularly in the aircraft industry. Notwithstanding the current level of acceptance of laser drilling in the aerospace industry, a number of defects such as spatter, recast and taper are associated with laser drilled holes and elimination of these defects is the subject of intense research. The present paper deals with Nd:YAG laser drilling of 4 and 8mm thick sections of IN718 and Ti-6Al-4V materials. The influence of type of material and its thickness, as well as parametric impact of key process variables like pulse frequency and pulse energy, have been determined. In the course of this study, relevant geometrical features of the drilled holes, like hole diameter and taper angle, have been comprehensively investigated. In addition, all metallurgical characteristics of interest, viz extent and nature of spatter, recast and heat-affected zone, have been evaluated. Effort has also been made to obtain some insights into the evolution of a through-thickness hole during laser percussion drilling of thick sections by careful experimentation involving monitoring the progression of the drilled hole with increasing number of laser pulses. Issues pertaining to variation of taper with depth of hole, change in crater depth with progressive drilling and specific energy consumption are also discussed. © 2002 Elsevier Science B.V. All rights reserved.

  • 15. Banerjee, D.
    et al.
    Joshi, Shrikant V.
    Accuracy, Reliability and Reproducibility of Various Mechanical Test Techniques: Preface1996In: Transactions of the Indian Institute of Metals, ISSN 0019-493X, Vol. 49, no 5, R1-R2 p.Article in journal (Other academic)
  • 16. Barick, P.
    et al.
    Prasad Saha, B.
    Mitra, R.
    Joshi, Shrikant V.
    Effect of concentration and molecular weight of polyethylenimine on zeta potential, isoelectric point of nanocrystalline silicon carbide in aqueous and ethanol medium2015In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 41, no 3, 4289-4293 p.Article in journal (Refereed)
    Abstract [en]

    The effect of dispersant concentration and its molecular weight on zeta potential of nanocrystalline silicon carbide in an aqueous medium was investigated. An increase in the concentration of the dispersant, such as polyethylenimine (PEI), in slurry prepared from nanosized silicon carbide, was found to augment the iso-electric point and zeta potential. However, the zeta potential was observed to decline as the pH of the slurry shifts towards the basic region. This aforementioned behavior is attributed to the enhanced mutual repulsion between the polymer chains of the dispersant adsorbed on the surfaces of SiC particles and those approaching the surfaces. The higher ionization potential of polymers in the acidic region compared to the basic region increases the adsorption. The relationship between zeta potential and pH is however, noted to remain virtually unchanged with molecular weight of PEI. Further, it is observed that zeta potential of SiC decreases with the increase in solid content of the slurry. Rheology study reveals that the ethanol based slurry has a lower viscosity than the water based slurry, making ethanol the preferred dispersing medium for colloidal processing of nanometric SiC powder. © 2014 Elsevier Ltd and Techna Group S.r.l.

  • 17.
    Barick, Prasenjit
    et al.
    International Advanced Research Centre for Powder Metallurgy and New Materials, Balapur Post, Hyderabad, 500005 Telangana, India.
    Chakravarty, Dibyendu
    International Advanced Research Centre for Powder Metallurgy and New Materials, Balapur Post, Hyderabad, 500005 Telangana, India.
    Saha, Bhaskar Prasad
    International Advanced Research Centre for Powder Metallurgy and New Materials, Balapur Post, Hyderabad, 500005 Telangana, India.
    Nitra, Rahul
    Department of Metallurgical and Materials Engineering, Indian Institute of Technology Kharagpur, Kharagpur, 721302 West Bengal, India.
    Joshi, Shrikant
    University West, Department of Engineering Science, Research Enviroment Production Technology West. International Advanced Research Centre for Powder Metallurgy and New Materials, Balapur Post, Hyderabad, 500005 Telangana, India.
    Effect of pressure and temperature on densification, microstructure and mechanical properties of spark plasma sintered silicon carbide processed with β-silicon carbide nanopowder and sintering additives2016In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 42, no 3, 3836-3848 p.Article in journal (Refereed)
    Abstract [en]

    The effects of applied pressure and temperature during spark plasma sintering (SPS) of additive-containing nanocrystalline silicon carbide on its densification, microstructure, and mechanical properties have been investigated. Both relative density and grain size are found to increase with temperature. Furthermore, with increase in pressure at constant temperature, the relative density improves significantly, whereas the grain size decreases. Reasonably high relative density (~96%) is achieved on carrying out SPS at 1300 °C under applied pressure of 75 MPa for 5 min, with a maximum of ~97.7% at 1500 °C under 50 MPa for 5 min. TEM studies have shown the presence of an amorphous phase at grain boundaries and triple points, which confirms the formation of liquid phase during sintering and its significant contribution to densification of SiC at relatively lower temperatures (≤1400 °C). The relative density decreases on raising the SPS temperature beyond 1500 °C, probably due to pores caused by vaporization of the liquid phase. Whereas β-SiC is observed in the microstructures for SPS carried out at temperatures ≤1500 °C, α-SiC evolves and its volume fraction increases with further increase in SPS temperatures. Both hardness and Young׳s modulus increase with increase in relative density, whereas indentation fracture toughness appears to be higher in case of two-phase microstructure containing α and β-SiC.

  • 18.
    Barick, Prasenjit
    et al.
    International Advanced Research Centre for Powder Metallurgy and New Materials, Balapur Post, Hyderabad-500005, Telangana, India.
    Saha, Bhaskar Prasad
    International Advanced Research Centre for Powder Metallurgy and New Materials, Balapur Post, Hyderabad-500005, Telangana, India.
    Joshi, Shrikant
    University West, Department of Engineering Science, Research Enviroment Production Technology West. International Advanced Research Centre for Powder Metallurgy and New Materials, Balapur Post, Hyderabad-500005, Telangana, India.
    Mitra, Rahul
    Department of Metallurgical and Materials Engineering, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, 721302, India.
    Spray-freeze-dried nanosized silicon carbide containing granules: Properties, compaction behaviour and sintering2016In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 36, no 16, 3863-3877 p.Article in journal (Refereed)
    Abstract [en]

    Spherical granules comprising silicon carbide nanoparticles have been produced with the help of sprayfreeze-drying (SFD) technique. The effect of solid loading of slurries on rheological properties, flowability and morphology of the resulting SFD granules has been studied. Further, a systematic study has been performed to investigate the effect of applied pressures and granule density on the relative densities and microstructures of the green compacts. A marginal increase in viscosity is noted as the solid content of slurries increases from 5 to 15 vol% with significant increase in viscosity being observed in case of 18 vol% slurry. The granules prepared from SiC slurries are spherical in shape with their mean size, density, gravimetric flow rate, and yield strength increasing with the increase in solid content. The mechanical properties of sintered SiC produced from SFD granules are found relatively superior to that made from commercially available spray-dried (SD) granules.

  • 19. Basu, A.
    et al.
    Chakraborty, J.
    Shariff, S. M.
    Padmanabham, G.
    Joshi, S. V.
    Sundararajan, G.
    Dutta Majumdar, J.
    Manna, I.
    Laser surface hardening of austempered (bainitic) ball bearing steel2007In: Scripta Materialia, Vol. 56, no 10, 887-890 p.Article in journal (Refereed)
    Abstract [en]

    This study concerns laser surface hardening (LSH) of austempered SAE 52100 steel to enhance hardness and wear resistance. Following LSH with selected laser parameters, surface microstructure and mechanical properties were evaluated by optical/scanning electron microscopy, X-ray diffraction, hardness measurement and wear studies, and thermal profile modeling. The results suggest that LSH could develop residual compressive stress and high hardness and wear resistance in this steel without affecting the bainitic core. © 2007 Acta Materialia Inc.

  • 20. Bharadwaj, Sanjay
    et al.
    Jain, Karuna
    Joshi, Shrikant V.
    A Review of Technology Commercialization Models: Suitability for Indian Research and Technology Organizations (RTOs) in Advanced Materials Sector2012In: International Journal of Business Administration & Management, Vol. 2, no 1, 53-60 p.Article in journal (Refereed)
  • 21. Bharadwaj, Sanjay
    et al.
    Padmanabham, G.
    Jain, Karuna
    Momaya, K.
    Joshi, Shrikant V.
    Strategic Alliances for Advanced Materials Technologies' Value Chain: Research and Technology Organisation (RTO)’s Perspective2014In: Proceedings of 2nd International Conference on Management of Intellectual Property Rights and Strategy / [ed] Shishir K Jha & Gouri Gargate (eds.), 2014Conference paper (Refereed)
  • 22. Bhardwaj, Sanjay
    et al.
    Jain, Karuna
    Joshi, Shrikant V.
    Technology Commercialization by Micro, Small and Medium Enterprises (MSMEs) in Indian Context: Challenges and Governmental Support Systems2013In: Indian Journal of Economics and Business, Vol. 12Article in journal (Refereed)
    Abstract [en]

    Post-liberalization, level of protection imparted by Indian government to Micro, Small and Medium Enterprises (MSMEs) is gradually reducing. In the changed scenario, MSMEs need to complete with large companies, both Indian and foreign, with cost-competitive and good quality products. Due to limited resources available with MSMEs, they find it difficult to develop internal technologies and hence need to access technologies developed elsewhere. Technologies developed by public funded Research and Technology Organizations (RTOs) can support MSMEs. However, MSMEs should develop competence to commercialize technologies procured from public-funded RTOs, and also utilize available governmental support to meet the emerging challenges. This paper discusses the challenges and governmental support systems for technology commercialization, with relevant examples, from Indian MSMEs’ perspective.

  • 23.
    Bhardwaj, Sanjay
    et al.
    International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Hyderabad, India.
    Padmanabham, G.
    International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Hyderabad, India.
    Jain, Karuna
    National Institute of Industrial Engineering (NITIE), Mumbai, India.
    Srinivasa Rao, D.
    International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Hyderabad, India.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Technology commercialization in advanced materials sector: Indian context2017In: Journal of Intellectual Property Rights, ISSN 0971-7544, E-ISSN 0975-1076, Vol. 22, no 3, 154-167 p.Article in journal (Refereed)
    Abstract [en]

    This study is aimed at developing insights into the Technology Value Chain (TVC) of advanced materials-based technologies using a scenario in which technology has been transferred by a Research and Technology Organization (RTO) to a Small and Medium Enterprise (SME) in the Indian context. A Conceptual Theoretical Model (CTM) using constructs from existing TVC models is used as a basis for the case study described in this paper. This model is refined using actual evidence from an Indian RTO - the International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Hyderabad. The TVC of ARCI’s proprietary Detonation Spray Coating (DSC) technology is used to expand upon the CTM as well as to provide new insights wherever possible. The TVC adopted for DSC includes technology incubation and proof of concept in advance of transferring the technology. These strategies, aided by government funding of the technology recipient companies, were observed to play an important role in successful commercialization. © 2017, National Institute of Science Communication and Information Resources (NISCAIR). All rights reserved.

  • 24. Chakravarty, D.
    et al.
    Tiwary, C. S.
    Machado, L. D.
    Brunetto, G.
    Vinod, S.
    Yadav, R. M.
    Galvao, D. S.
    Joshi, Shrikant V.
    Sundararajan, G.
    Ajayan, P. M.
    Zirconia-Nanoparticle-Reinforced Morphology-Engineered Graphene-Based Foams2015In: Advanced Materials, Vol. 27, no 31, 4534-4543 p.Article in journal (Refereed)
    Abstract [en]

    The morphology of graphene-based foams can be engineered by reinforcing them with nanocrystalline zirconia, thus improving their oil-adsorption capacity; This can be observed experimentally and explained theoretically. Low zirconia fractions yield flaky microstructures where zirconia nanoparticles arrest propagating cracks. Higher zirconia concentrations possess a mesh-like interconnected structure where the degree of coiling is dependant on the local zirconia content. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  • 25. Chatterjee, M.
    et al.
    Ray, J.
    Chatterjee, A.
    Ganguli, D.
    Joshi, S. V.
    Srivastava, M. P.
    Thermal barrier coatings from sol-gel-derived spray-grade Y2O3-ZrO2 microspheres1993In: Journal of Materials Science, Vol. 28, no 10, 2803-2807 p.Article in journal (Refereed)
    Abstract [en]

    For the development of ceramic thermal barrier coatings, spray-grade yttria-stabilized zirconia microspheres were prepared by the sol-gel technique. Oxide microspheres were obtained by calcination of the corresponding gel spheres at 1000 °C. Scanning electron microscopic and optical microscopic observations revealed the material thus obtained to have a predominantly spherical morphology and the requisite size distribution (5-50 μm). The dense, calcined microspheres showed good flowability. X-ray diffraction studies indicated the presence of the tetragonal polymorph of ZrO2 as the major phase, in addition to about 14% monoclinic ZrO2. The plasma-sprayed YSZ coatings made from the sol-gel-derived microspheres showed a further decrease in the monoclinic ZrO2 content (6%). The coatings survived 40-50 thermal cycles (30 min at 1200 °C followed by a water quench), indicating good thermal shock resistance. © 1993 Chapman &amp; Hall.

  • 26. Das, D. K.
    et al.
    Roy, M.
    Singh, V.
    Joshi, S. V.
    Microstructural degradation of plain and platinum aluminide coatings on superalloy CM247 during isothermal oxidation1999In: Materials Science and Technology, Vol. 15, no 10, 1199-1208 p.Article in journal (Refereed)
    Abstract [en]

    Isothermal oxidation at 1100°C of a high activity plain aluminide coating and a platinum aluminide coating, developed by the pack cementation technique, on cast nickel base superalloy CM247 has been carried out with the primary objective of systematically understanding the coating degradation process during oxidation. While the weight gains during oxidation for both plain aluminide and platinum aluminide coatings follow parabolic kinetics from the very beginning of oxidation exposure, the bare alloy was seen to exhibit a considerably long initial transient oxidation period (∼20 h), beyond which the parabolic law was followed. The parabolic rate constant for the platinum aluminide coating was found to be nearly two orders of magnitude lower than that for the plain aluminide coating. Alumina was identified as the only oxide phase that formed on both plain aluminide and platinum aluminide coatings during most of the oxidation exposure, although NiAl2O4 was also found in the case of the plain aluminide coating beyond ∼200 h. The oxide layer on the bare alloy, however, was found to consist of Al2O3, Cr2O3, and NiAl2O4. The microstructural degradation of both the plain aluminide and platinum aluminide coatings during oxidation was seen to occur in three distinct stages which, however, differed for each coating. This stagewise degradation, which involves final obliteration of the interdiffusion layer in each case, is discussed in detail. © 1999 IoM Communications Ltd.

  • 27. Das, D. K.
    et al.
    Singh, V.
    Joshi, S. V.
    Effect of Al content on microstructure and cyclic oxidation performance of Pt-aluminide coatings2002In: Oxidation of Metals, Vol. 57, no 3-4, 245-266 p.Article in journal (Refereed)
    Abstract [en]

    The effect of Al content, i.e., the amount of Al picked up during aluminizing, on the microstructure and cyclic oxidation properties of Pt-aluminide coatings has been investigated. The cast Ni-base superalloy CM-247 was used as the substrate material and a single-step, high-activity pack aluminizing process was used to produce the Pt-aluminide coatings. The Al content of these coatings was varied by using packs with different compositions of the Al source. Pt-aluminide coatings having three different Al contents, namely 6.5, 16, and 21 mg cm-2, were evaluated for their cyclic oxidation resistance at 1200°C in air. It was found that the Pt-aluminide coatings, irrespective of their Al contents, evolve in the same manner during aluminizing and result in a three-layer structure with an outer PtAl2 + NiAl two-phase layer, an intermediate NiAl layer, and the inner interdiffusion layer. The stability of this three-layer coating structure over long periods of aluminizing, however, is dependent on the availability of Al from the pack during this period. Below a certain threshold Al availability, the two-phase outer layer transforms to a single-phase NiAl structure causing the coating to change from its three-layer structure to a two-layer one. Cyclic oxidation results indicate that, while a minimum Al content in Pt-aluminide coatings is essential for deriving the best oxidation performance, increasing the Al content beyond a certain level does not significantly enhance oxidation behavior. The effect of Al content on aspects, such as coating degradation and nature of coating-surface damage during cyclic oxidation, is also discussed.

  • 28. Das, D. K.
    et al.
    Singh, V.
    Joshi, S. V.
    Effect of prealuminizing diffusion treatment on microstructural evolution of high-activity pt-aluminide coatings2000In: Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science, Vol. 31, no 8, 2037-2047 p.Article in journal (Refereed)
    Abstract [en]

    The effect of prealuminizing (or prior) diffusion treatment on the evolution of Pt-aluminide coatings on the Ni-based superalloy CM-247 has been studied by using a single-step, high-activity aluminizing process. Coatings generated without any prior diffusion treatment, as well as those formed by adopting two extreme prior-diffusion schedules (at 850 °C for 0.5 hours and at 1034 °C for 5 hours), were investigated by analyzing the coating structures at various stages of aluminizing. When the dilution of the Pt layer, caused by its interdiffusion with the substrate during the prior diffusion treatment, is only marginal (as in the case of no prior diffusion and diffusion at 850 °C for 0.5 hours), the equilibrium Pt-aluminide coating structure evolves through the formation of two transient layers during the initial stages of aluminizing. In contrast, for diffusion at 1034 °C for 5 hours, which results in extensive dilution of the Pt layer, the two-phase equilibrium structure (PtAl2 in a matrix of NiAl) in the outer layer of the coating is found to develop during very early stages of aluminizing and remains unchanged, even over extended periods of aluminizing. Further, in the case of prior diffusion at 1034 °C for 5 hours, Pt is found to remain distributed to a greater extent over the entire thickness of the coating than in the cases of limited prior diffusion treatment. The present findings underline the significance of the nature of the prior-diffusion schedule on the microstructural evolution of Pt-aluminide coatings. It has also been found that a prealuminizing diffusion treatment is particularly important for Pt-aluminide coatings from the point of view of coating adhesion to the substrate.

  • 29. Das, D. K.
    et al.
    Srivastava, M. P.
    Joshi, S. V.
    Sivakumar, R.
    Scratch adhesion testing of plasma-sprayed yttria-stabilized zirconia coatings1991In: Surface and Coatings Technology, Vol. 46, no 3, 331-345 p.Article in journal (Refereed)
    Abstract [en]

    The suitability of scratch adhesion testing, usually used for determining the critical load for thin hard coatings like TiC and TiN, in characterizing plasma-sprayed yttria-stabilized zirconia coatings is demonstrated. The effects of loading rate and scratching speed on the critical load of these sprayed coatings were studied. Although some peculiarities in acoustic signal-load plot were observed at high values of loading rate and scratching speed, it was found that these intrinsic parameters, at low and medium values, do not have any prominent effect on the critical load. © 1991.

  • 30. DAS, D.K.
    et al.
    Singh, Vakil
    Joshi, Shrikant V.
    High temperature oxidation behaviour of directionally solidified nickel base superalloy CM–247LC2003In: Materials Science and Technology, ISSN 0267-0836, E-ISSN 1743-2847, Vol. 19, no 6, 695-708 p.Article in journal (Refereed)
    Abstract [en]

    The present paper describes the isothermal and cyclic oxidation behaviour of the technologically important nickel base directionally solidified superalloy CM-247LC in air in the temperature range 1000-1200°C. This superalloy behaves as a transition nickel base alloy under isothermal oxidation conditions and exhibits a fairly long transient oxidation period (~20 h at 1100°C). Irrespective of the temperature of exposure and nature of oxidation (isothermal or cyclic), a composite oxide scale develops on CM-247LC. While the outer portion of the oxide scale consists of either spinel (NiAl2O4) or a mixture of spinel and NiO, depending on oxidation temperature, the inner portion is always constituted of alumina. Beyond the transient period, the alloy is found to follow parabolic oxidation kinetics. The oxide layer that forms is invariably very non-uniform in thickness, and is dispersed with two types of oxide particles. While tantalum rich oxide particles are found scattered in the outer zone of the oxide layer, hafnium rich oxide particles lie close to the oxide/metal interface. Results also reveal that the nature of oxidation associated with the CM-247LC superalloy causes entrapment of metal islands in the oxide layer.

  • 31. Das, O. K.
    et al.
    Singh, V.
    Joshi, S. V.
    Evolution of aluminide coating microstructure on nickel-base cast superalloy CM-247 in a single-step high-activity aluminizing process1998In: Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science, Vol. 29, no 8, 2173-2188 p.Article in journal (Refereed)
    Abstract [en]

    This study deals with the aluminizing of a directionally cast Ni-base superalloy, namely CM-247, by a single-step process using a high-activity pack. It is observed that significant incorporation of Al into the substrate surface during aluminizing continues over a period of about 1 hour and is not restricted merely to the first few minutes, as reported in the literature. Based on the microstructural details of the coatings formed at various stages of aluminizing, it is concluded that the coating growth in the above process takes place primarily by inward Al diffusion initially, followed by an intermediate stage when the growth involves both inward Al and outward Ni diffusion. In the final stages, the outward diffusion of Ni dominates the coating formation process. The above mechanism of coating formation is different from the one that prevails in the conventional two-step high-activity coating process in that the reaction front for the formation of NiAl remains spatially stationary despite the outward diffusion of nickel during the intermediate stage. It is also shown in the present study that the content of the Al source in the pack affects the coating structure significantly. It is further demonstrated that the microstructure of the aluminide coatings depends not only on the amount of Al incorporated in the sample during aluminizing but also on the time over which the uptake of this Al takes place.

  • 32. Dhage, S. R.
    et al.
    Chandrasekhar, P. S.
    Chandrasekhar, S. B.
    Joshi, S. V.
    CIGS absorber layer by single-step non-vacuum intense pulsed light treatment of inkjet-printed film2014In: 2014 IEEE 40th Photovoltaic Specialist Conference, PVSC 2014, 2014, 1607-1610 p., 6925227Conference paper (Refereed)
    Abstract [en]

    Non-vacuum processes are of great interest for development of low-cost chalcopyrite-based photovoltaic technologies. Apart from the expensive vacuum-based routes that are widely adopted, another negative feature of the popularly employed methods is the need for selenization treatment, which significantly impacts the microstructure of the absorber layer and, in turn, also determines the performance of the device. A novel process for preparation of Cu(In0.7Ga0.3)Se2 (CIGS) films from an ink constituted of CIGS nanoparticles utilizing a convenient intense pulsed light (IPL) treatment is investigated in the present study. Initially, a thorough optimization of ink formulation variables was carried out in order to make the CIGS ink suitable for ink jet printing. The home-made CIGS ink, comprising CIGS nanoparticles with appropriate additives, was then successfully deposited with a print head having 256 nozzles on Mo coated soda lime glass substrate. Subsequently, IPL was used to treat the printed CIGS ink. Post IPL treatment, a CIGS film retaining the chalcopyrite structure even after melting and recrystallization, with no secondary phase formation, was realized. The phase constitution, thickness and morphology of prepared films were determined using X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF) and field emission scanning electron microscopy (FESEM). The above non-vacuum, room temperature process not requiring any selenization treatment can have important implications in realization of cost-effective CIGS absorber layers.

  • 33. Dhage, S. R.
    et al.
    Tak, M.
    Joshi, S. V.
    Fabrication of CIGS thin film absorber by laser treatment of pre-deposited nano-ink precursor layer2014In: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 134, 302-305 p.Article in journal (Refereed)
    Abstract [en]

    A process to prepare Copper Indium Gallium Selenide (CIGS) absorber thin films by laser treatment of pre-deposited nano-inks has been investigated. Two approaches were followed, one using an ink of CIGS nanoparticles and other employing an ink comprising a mixture of a CIG metallic alloy and Se nanoparticles. Laser post treatment of the film applied with the CIGS ink was found to retain the chalcopyrite structure following melting and recrystallization, with no additional phases being generated during the process. Single-phase, highly crystalline CIGS thin films were also found to result from the ink made of CuIn0.7Ga0.3 and Se nanoparticles precursor following laser treatment. The CuIn0.7Ga 0.3Se2 thin films obtained in both cases were consistent with the initial constitution of the precursor materials used in terms of the Ga/(Ga+In) ratio. The prepared films were comprehensively characterized using XRD, SEM-EDS and XRF. Results reveal that the above non-vacuum approach obviating the need for a selenization step is simple, quick and expected to have a large impact on the overall process economics for fabrication of CIGS thin film solar cells. © 2014 Elsevier B.V.

  • 34. Dineshram, R.
    et al.
    Subasri, R.
    Somaraju, K. R. C.
    Jayaraj, K.
    Vedaprakash, L.
    Ratnam, K.
    Joshi, S. V.
    Venkatesan, R.
    Biofouling studies on nanoparticle-based metal oxide coatings on glass coupons exposed to marine environment2009In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 74, no 1, 75-83 p.Article in journal (Refereed)
    Abstract [en]

    Titania, niobia and silica coatings, derived from their respective nanoparticle dispersions or sols and fabricated on soda lime glass substrates were subjected to field testing in marine environment for anti-macrofouling applications for marine optical instruments. Settlement and enumeration of macrofouling organisms like barnacles, hydroides and oysters on these nanoparticle-based metal oxide coatings subjected to different heat treatments up to 400 degrees C were periodically monitored for a period of 15 days. The differences observed in the antifouling behaviour between the coated and uncoated substrates are discussed based on the solar ultraviolet light induced photocatalytic activities as well as hydrophilicities of the coatings in case of titania and niobia coatings and the inherent hydrophilicity in the case of silica coating. The effect of heat treatment on the photocatalytic activity of the coatings is also discussed. (C) 2009 Elsevier B.V. All rights reserved.

  • 35. Dom, R.
    et al.
    Kumar, G. S.
    Hebalkar, N. Y.
    Joshi, S. V.
    Borse, P. H.
    Eco-friendly ferrite nanocomposite photoelectrode for improved solar hydrogen generation2013In: RSC Advances, Vol. 3, no 35, 15217-15224 p.Article in journal (Refereed)
    Abstract [en]

    For the first time, a ferrite nanocomposite photoelectrode (FNCP) has been fabricated and investigated for photoelectrochemical hydrogen production from water under simulated solar light. The ZnFe2O4:Fe 2O3 nanocomposite photoanode has been fabricated via a single step methodology using a novel approach involving the solution precursor plasma spraying technique. The FNCP is achieved by optimal phase formation during the deposition of the ferrite film (∼10 μm) over a stainless steel substrate. It exhibits an enhanced photoactivity 6 times higher compared to pure ZnFe2O4 (ZFO), under simulated-solar (AM1.5 G) illumination. Its Mott-Schottky characterization reveals an n-type semiconducting behaviour, indicating an order of magnitude higher donor density (Nd ∼ 1017 cm-3) than the pure phase ZnFe2O4 electrode. It also exhibits a low band gap of 1.94 eV demonstrating that it can more efficiently absorb visible light photons than other systems comprising of bare zinc ferrite or iron oxide. The FNCP yielded a solar-to-hydrogen conversion efficiency of 1.25% under simulated solar radiation (AM1.5 G) with a hydrogen evolution rate of 99 μmol h-1. Electrochemical impedance spectroscopy of the FNCP revealed a significantly improved charge transfer characteristic compared to ZnFe2O 4. An enhanced photoactivity for the oxidation of water from the FNCP is attributed to its improved optical absorption and better charge transfer properties induced by the existence of Fe2O3 in ZnFe 2O4. © The Royal Society of Chemistry 2013.

  • 36. Dom, R.
    et al.
    Kumar, G. S.
    Kim, H. G.
    Joshi, S. V.
    Chary, S.
    Borse, P. H.
    Design and development of ferrite composite film electrode for photoelectrochemical energy application2014In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 781, 45-61 p.Article in journal (Refereed)
    Abstract [en]

    Development of efficient photoanodes for water splitting under solar light is desirable to surmount the possible fuel crisis in future. Ferrite systems, with their excellent visible light absorption capability, stability, non-toxicity, cost-effectiveness and abundance, are being preferred to titanates, niobates and sulfides. The present work briefly reviews the modified form of ferrites. Additionally, ZnFe2O4 an n-type semiconductor with the low band gap (~1.9eV) has been considered as special case of visible light PEC application. The work further emphasizes on the utilization of solution processed techniques to develop the ferrite photoanodes. The tuning of photoanode properties by virtue of electrode fabrication parameters say deposition parameters viz., precursor concentration, pH, stoichiometry has been reviewed and discussed. © (2014) Trans Tech Publications, Switzerland.

  • 37. Dom, R.
    et al.
    Sivakumar, G.
    Hebalkar, N. Y.
    Joshi, S. V.
    Borse, P. H.
    Deposition of nanostructured photocatalytic zinc ferrite films using solution precursor plasma spraying2012In: Materials Research Bulletin, Vol. 47, no 3, 562-570 p.Article in journal (Refereed)
    Abstract [en]

    Deposition of pure spinel phase, photocatalytic zinc ferrite films on SS-304 substrates by solution precursor plasma spraying (SPPS) has been demonstrated for the first time. Deposition parameters such as precursor solution pH, concentration, film thickness, plasma power and gun-substrate distance were found to control physico-chemical properties of the film, with respect to their crystallinity, phase purity, and morphology. Alkaline precursor conditions (7 &lt; pH ≤ 10) were found to favor oxide film formation. The nanostructured films produced under optimized conditions, with 500 mM solution at pH ∼ 8.0, yielded pure cubic phase ZnFe 2O 4 film. Very high/low precursor concentrations yielded mixed phase, less adherent, and highly inhomogeneous thin films. Desired spinel phase was achieved in as-deposited condition under appropriately controlled spray conditions and exhibited a band gap of ∼1.9 eV. The highly porous nature of the films favored its photocatalytic performance as indicated by methylene blue de-coloration under solar radiation. These immobilized films display good potential for visible light photocatalytic applications. © 2012 Elsevier Ltd. All rights reserved.

  • 38.
    Ganvir, Ashish
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Joshi, Shrikant
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Influence of Isothermal Heat Treatment on Porosity and Crystallite Size in Axial Suspension Plasma Sprayed Thermal Barrier Coatings for Gas Turbine Applications2017In: Coatings, ISSN 2079-6412, Vol. 7, no 1, 4Article in journal (Refereed)
    Abstract [en]

    xial suspension plasma spraying (ASPS) is an advanced thermal spraying technique, which enables the creation of specific microstructures in thermal barrier coatings (TBCs) used for gas turbine applications. However, the widely varying dimensional scale of pores, ranging from a few nanometers to a few tenths of micrometers, makes it difficult to experimentally measure and analyze porosity in SPS coatings and correlate it with thermal conductivity or other functional characteristics of the TBCs. In this work, an image analysis technique carried out at two distinct magnifications, i.e., low (500×) and high (10,000×), was adopted to analyze the wide range of porosity. Isothermal heat treatment of five different coatings was performed at 1150 °C for 200 h under a controlled atmosphere. Significant microstructural changes, such as inter-columnar spacing widening or coalescence of pores (pore coarsening), closure or densification of pores (sintering) and crystallite size growth, were noticed in all the coatings. The noted changes in thermal conductivity of the coatings following isothermal heat treatment are attributable to sintering, crystallite size growth and pore coarsening

  • 39.
    Ganvir, Ashish
    et al.
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Curry, Nicholas
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Markocsan, Nicolaie
    University West, Department of Engineering Science, Division of Production Engineering.
    Nylén, Per
    University West, Department of Engineering Science, Division of Production Engineering.
    Joshi, Shrikant
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Vilemova, Monika
    IPP.
    Pala, Zdenek
    IPP.
    Influence of Microstructure on Thermal Properties of Axial Suspension Plasma-Sprayed YSZ Thermal Barrier Coatings2016In: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 25, no 1-2, 202-212 p.Article in journal (Refereed)
    Abstract [en]

    Suspension plasma spraying is a relatively new thermal spaying technique to produce advanced thermal barrier coatings (TBCs) and enables production of coatings with a variety of structures—highly dense, highly porous, segmented, or columnar. This work investigates suspension plasma-sprayed TBCs produced using axial injection with different process parameters. The influence of coating microstructure on thermal properties was of specific interest. Tests carried out included microstructural analysis, phase analysis, determination of porosity, and pore size distribution, as well as thermal diffusivity/conductivity measurements. Results showed that axial suspension plasma spraying process makes it possible to produce various columnar-type coatings under different processing conditions. Significant influence of microstructural features on thermal properties of the coatings was noted. In particular, the process parameter-dependent microstructural attributes, such as porosity, column density, and crystallite size, were shown to govern the thermal diffusivity and thermal conductivity of the coating.

  • 40. Geetha, M.
    et al.
    Sathish, S.
    Chava, K.
    Joshi, S. V.
    Detonation gun sprayed Al2O3-13TiO(2) coatings for biomedical applications2014In: Surface Engineering, ISSN 0267-0844, E-ISSN 1743-2944, Vol. 30, no 4, 229-236 p.Article in journal (Refereed)
    Abstract [en]

    The present work deals with the investigation of the corrosion and sliding wear behaviour of detonation gun sprayed (DG) conventional and nanostructured Al2O3-13TiO(2) coatings deposited on a biomedical grade Ti-13Nb-13Zr alloy. The microstructure and phase composition of the coatings were characterised by scanning electron microscopy (SEM) and X-ray diffraction ( XRD). Hardness measurements were carried out using a Vickers hardness testing machine. The experimental results suggested that the nano structured Al2O3- 13TiO(2) coating exhibited 43 and 33% increase respectively in corrosion and wear resistances compared to the conventional Al2O3-13TiO(2) coating. This improvement in the above properties of nanostructured Al2O3-13TiO(2) coating is due to the presence of larger volume fraction of nanosized particles and lower porosity attained by spraying using DG.

  • 41. George, J.
    et al.
    Bhargava, P.
    Rao, D. S.
    Joshi, S. V.
    Integrity of detonation sprayed CrxCy-NiCr coating under exposure to thermal cycling2006In: Advances in Applied Ceramics: Structural, Functional and Bioceramics, ISSN 1743-6753, E-ISSN 1743-6761, Vol. 105, no 3, 148-152 p.Article in journal (Refereed)
    Abstract [en]

    CrxCy-NiCr coatings with thickness in the range 200-250 mu m were deposited by detonation spray coating on a nickel base superalloy (IN718) substrate and subjected to thermal cycling. Each thermal cycle involved heating to 650 degrees C, the creep temperature of the IN718 substrate, followed by a dwell and then natural cooling to ambient temperature. With thermal cycling, the bulk of the coatings experienced preferential oxidation along the splat boundaries, contributing to an increase in porosity and cracking. Despite the development of porosity and cracks, no spallation of coatings was observed even after nearly 600 thermal cycles. The microhardness of coatings did not undergo significant change, owing to oxide formation and retention of the total carbide content of Cr3C2, Cr7C3 and Cr23C6. The wear behaviour of the as sprayed and thermally cycled coated samples was evaluated in abrasive and erosive wear modes. Wear measurements on as sprayed and thermally cycled coatings showed virtually no deterioration in properties even after exposure to nearly 600 thermal cycles.

  • 42.
    Goel, Sneha
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Björklund, Stefan
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Curry, Nicholas
    Treibacher Ind AG, Althofen, Austria.
    Wiklund, U.
    Uppsala Univ, Dept Technol, Mat Sci Div, S-75121 Uppsala, Swede.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Axial suspension plasma spraying of Al2O3 coatings for superior tribological properties2017In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 315, 80-87 p.Article in journal (Refereed)
    Abstract [en]

    Suspension plasma spray is a relatively new thermal spray technique which enables feeding of fine powder to produce advanced coatings for varied applications. This work investigates the difference in structure and performance of Al2O3 coatings manufactured using conventional micron-sized powder feedstock and a suspension of sub-micron to few micron sized powder. Axial injection was implemented for deposition in both cases. The effect of feedstock size and processing on the tribological performance of the two coatings was of specific interest. The coatings were characterized by Optical and Scanning Electron Microscopy, micro-hardness and scratch resistance testing, and their dry sliding wear performance evaluated. The suspension sprayed coatings yielded significantly higher scratch resistance, lower friction coefficient and reduced wear rate compared to conventional coatings. The improved tribological behaviour of the former is attributable to finer porosity, smaller splat sizes, and improved interlamellar bonding. (C) 2017 Elsevier B.V. All rights reserved.

  • 43.
    Goel, Sneha
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Björklund, Stefan
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Joshi, Shrikant
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Deposition of Novel Composite Coatings by Suspension-Powder Hybrid Plasma Spraying2016In: The 7th International Swedish Production Symposium, SPS16, Conference Proceedings: 25th – 27th of October 2016, Lund: Swedish Production Academy , 2016, 1-8 p.Conference paper (Refereed)
    Abstract [en]

    Suspension Plasma Spray (SPS) is an emerging technique which overcomes the difficulties typically associated with feeding of fine (submicron or nano-sized) powders in conventional atmospheric plasma spraying (APS) to obtain superior coating properties for various engineering applications. The advent of plasma spray systems that allow axial injection of feedstock, which considerably improves thermal exchange between the plasma plume and the injected feedstock, has enabled substantial enhancement in deposition rates/efficiencies to make SPS techno-commercially exciting. The present study utilizes both the above advances in plasma spraying to demonstrate the ability to deposit novel coating architectures by sequential/simultaneous axial injection of both powder and a suspension feedstock. The results reveal that composite coatings uniquely combining the micron-size features arising from the spray-grade powder and the submicron or nano-sized features attributable to the suspension, can be conveniently realized using the above approach. Three different kinds of coating architectures were generated, namely layered, composite, and functionally graded. The sprayed coatings were extensively characterized for attributes such as surface morphology, microstructure, and composition particularly in the case of composite coatings.

  • 44. Govindarajan, S.
    et al.
    Dusane, R. O.
    Joshi, S. V.
    In situ particle generation and splat formation during solution precursor plasma spraying of yttria-stabilized zirconia coatings2011In: Journal of the American Ceramic Society, Vol. 94, no 12, 4191-4199 p.Article in journal (Refereed)
    Abstract [en]

    Thermal barrier coatings (TBCs) based on Yttria-stabilized Zirconia (YSZ) deposited by the solution precursor plasma spray (SPPS) technique have been claimed to exhibit superior durability compared to conventional plasma spraying and even electron-beam physical vapor deposition. This has been attributed to the interesting features, like vertical cracks, nanosized pores, and fine splats that are inherent to SPPS-deposited YSZ coatings. However, the mechanism of coating formation during SPPS processing is not yet well understood. This study is aimed at understanding the influence of some key SPPS process variables on in situ generated particles and subsequent splat formation to augment the current level of understanding. The plasma power employed was found to play a major role in governing the morphology and phase constitution of in situ generated particles. The shape and size of the YSZ splats were also significantly influenced by the plasma power, but the substrate pre-heat was also noted to be a major determining factor. It was further observed that the SPPS typically involved in situ generation of very fine particulates (50-500 nm) and splats (typically 200-2000 nm), which lead to its nano-porous and homogeneous microstructure. The YSZ coating characteristics were also found to correlate well with the above results. © 2011 The American Ceramic Society.

  • 45.
    Govindararajan, S.
    et al.
    International Advanced Research Center for Powder Metallurgy and New Materials, Balapur, Hyderabad, India.
    Dusane, R. O.
    Department of Metallurgical Engineering & Materials Science, Indian Institute of Technology, Powai, Mumbai, India.
    Joshi, Shrikant V.
    Understanding the Formation of Vertical Cracks in Solution Precursor Plasma Sprayed Yttria-Stabilized-Zirconia Coatings2014In: Journal of The American Ceramic Society, ISSN 0002-7820, E-ISSN 1551-2916, Vol. 97, 3396-3406 p.Article in journal (Refereed)
    Abstract [en]

    Yttria-stabilized zirconia (YSZ) deposition by the solution precursor plasma spraying (SPPS) route has been of interest for potential thermal barrier coating (TBC) applications. It has been surmised that realization of unique microstructural features like vertical cracks, nanosized pores and fine splats in the TBCs can significantly enhance coating durability and performance. However, satisfactory control over the YSZ coating microstructure has been elusive in the absence of an adequate understanding of the mechanism responsible for coating deposition in SPPS. This study demonstrates the ability to tailor microstructure of deposited YSZ coatings over a wide range, from nano-porous coatings to a vertically cracked microstructure. Varying of precursor flow rate has been shown to dictate the pyrolysis events occurring in situ and, adopting this approach, YSZ coatings with widely varying microstructural features have been developed. The coatings have been characterized in detail and the observations correlated with in-flight particle generation and splat formation. These studies also provide useful insights into the possible origin of vertical cracks in the coating for which a mechanism is proposed.

  • 46. Islavath, N.
    et al.
    Ramasamy, E.
    Das, D.
    Joshi, Shrikant. V.
    Spray coated seed layer for scalable synthesis of aligned ZnO nanowire arrays on FTO substrate and their photovoltaic properties2015In: Ceramics International, Vol. 41, no 3, 4118-4122 p.Article in journal (Refereed)
    Abstract [en]

    Spray coating has been employed as a non-vacuum route for deposition of a ZnO seed layer on large-area fluorine-doped tin oxide (FTO) glass substrates. Optimization of spray parameters, particularly precursor flow rate and volume, was found to yield preferably oriented and uniform ZnO seed layer. Vertically aligned single crystalline ZnO nanowire arrays with controlled features were grown on aforementioned substrate at 95 °C by a hydrothermal method. The current-voltage characteristics of dye-sensitized solar cells fabricated with the aligned ZnO nanowire arrays as photoanode have demonstrated a maximum photocurrent density of 1.86 mA cm-2 under 1 sun illumination (100 mW cm-2, AM 1.5G). © 2014 Elsevier Ltd and Techna Group S.r.l.

  • 47.
    Islavath, Nanaji
    et al.
    Centre for Solar Energy Materials, International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Hyderabad 500005, India; School of Engineering Sciences and Technology, University of Hyderabad, Hyderabad 500046, India.
    Das, Dibakar
    School of Engineering Sciences and Technology, University of Hyderabad, Hyderabad 500046, India.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Ramasamy, Easwaramoorthi
    Centre for Solar Energy Materials, International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Hyderabad 500005, India.
    Seed layer-assisted low temperature solution growth of 3D ZnO nanowall architecture for hybrid solar cells2017In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 116, 219-226 p.Article in journal (Refereed)
    Abstract [en]

    Aligned metal oxide nanostructures carry electrons efficiently, and are therefore ideal building blocks for next-generation optoelectronic devices. Herein, we report the seed-layer-assisted low-temperature solution growth of aligned 3D ZnO nanowall architecture on arbitrary substrates. By introducing a controlled amount of Al into a seed-layer, the morphology of ZnO nanostructure is gradually changed from nanowire to 3D nanowalls. Time-dependent growth experiments suggest that hydroxyl-ions present in growth solution react with Al to form Al(OH)4 which in turn binds to the positively charged Zn2 +surface and partially blocking ZnO growth along the (0001) direction and promoting lateral growth. Such aligned 3D ZnO nanowall architecture, with the unique combination of high surface-area and cage-like pores, grown on seed-layer coated transparent conductive substrate is found to be beneficial for electron transporting material (ETM) in perovskite solar cells and a maximum photocurrent density (JSC) of 7.5 mA.cm− 2 and a power conversion efficiency (η) of 2.4% are demonstrated. Our facile approach readily allows further growth of ZnO nanowires on 3D ZnO nanowall surface; thereby improving the perovskite-ZnO interface and increasing the JSC and η to 9.7 and 3.3%, respectively. This 3D ZnO nanowall-nanowire architecture opens up a novel configuration for designing high-performance optoelectronic devices.

  • 48. Joshi, S. V.
    A prediction model to assist plasma and HVOF spraying1992In: Materials Letters, Vol. 14, no 1, 31-36 p.Article in journal (Refereed)
    Abstract [en]

    A theoretical prediction model is developed to estimate the in-flight velocity, temperature and size of a particle during plasma and HVOF spraying. The salient features of this model are outlined and the model predictions are examined through some example calculations performed under typical spraying conditions. Comparison with experimental data reveals that the present method enables accurate predictions. The principal advantages and shortcomings of the plasma and HVOF systems are also discussed based on the model estimates. © 1992.

  • 49. Joshi, S. V.
    Comparison of particle heat-up and acceleration during plasma and high velocity oxy-fuel spraying1992In: Powder Metallurgy International, Vol. 24, no 6, 373-378 p.Article in journal (Refereed)
    Abstract [en]

    Development of protective coatings by means of the thermal spray techniques known as atmospheric plasma spraying and high velocity oxy-fuel (HVOF) spraying is gaining widespread industrial acceptability. The temperature and velocity profiles in a plasma flame and an oxy-fuel combustion flame are distinctly different and this is primarily responsible for the significantly varied behaviour of injected particles in the two cases. This study deals primarily with the comparison of particle heat-up and acceleration during powder spraying by the two above methods and is based on a recently developed prediction model to assist plasma and HVOF spraying. Illustrative results for a few powder materials are presented. The results reveal that the high-temperature plasma flame is capable of completely melting even high melting point ceramic powders which are extremely difficult to melt in an oxy-fuel combustion flame. However, the hypersonic oxy-fuel flame is found to accelerate the powder particles to considerably higher velocities than a plasma flame and is, therefore, better suited to obtaining dense and well-bonded coatings using metal and low-melting alloy powders. The influence of the powder injection parameters on particle behaviour in plasma and HVOF spraying is also investigated.

  • 50. Joshi, S. V.
    Plasma spraying of Wc-Co part I: Theoretical investigation of particle heating and acceleration during spraying1993In: Journal of Thermal Spray Technology, Vol. 2, no 2, 127-130 p.Article in journal (Refereed)
    Abstract [en]

    Plasma-sprayed WC-Co coatings are used extensively in a variety of wear-resistant applications. The quality of these sprayed coatings depends greatly on the temperature and velocity of the powder particles impacting the substrate. Because it is both expensive and difficult to experimentally determine these particle parameters, the present study deals with a theoretical investigation of particle heatup and acceleration during plasma spraying of WC-Co based on a recently developed model. The effect of WC-Co particle size on the evolution of particle temperature and velocity is examined through calculations performed under typical spraying conditions. The implications of the powder particles, assuming an off-axis trajectory during their traverse through the plasma flame, are also discussed. © 1993 ASM International.

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