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  • 1. 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, p. 271-279Article 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.

  • 2.
    Arsenault, B.
    et al.
    Industrial Materials Institute, NRC, Boucherville, Que., Canada.
    Gougeon, P.
    University West, Department of Technology, Mathematics and Computer Science.
    Verdier, M.
    Université de Technologie Belfort-Montbéliard, Laboratoire d'Etudes et des Recherches sur les Materiaux les Procedes et les Surfaces (LERMPS).
    Duquesnay, D. L.
    Royal Military College of Canada, Department of Mechanical Engineering.
    Aluminum protective coatings - Fatigue and bond strength properties with respect to surface preparation techniques: Laser ablation, shot peening and grit blasting2006In: Canadian metallurgical quarterly, ISSN 0008-4433, E-ISSN 1879-1395, Vol. 45, no 1, p. 49-58Article in journal (Refereed)
    Abstract [en]

    Aluminum coatings can provide galvanic cathodic protection for several metals and alloys. In order to be a suitable protective solution on structural components, the mechanical integrity must be preserved. In particular, the fatigue properties are a challenge for thermal spray protective coatings on mechanical structures. To address the issue of the fatigue integrity of 7075 aluminum alloy with an arc sprayed protective coating, different surface preparations prior to arc spraying were considered. In the present work, a feasibility study was performed using laser ablation as a surface preparation technique before or during arc spraying of coatings through collaboration between the LERMPS laboratory in France, the National Research Council of Canada and the Royal Military College of Canada. Both fatigue and adhesive properties of aluminum coatings were evaluated in relation to substrate surface preparation techniques including laser ablation (PROTAL® process), grit blasting and shot peening. Results indicate that a combination of key conditions including using nitrogen as the arc spray gas, shot peening and proper laser energy density for ablation provides high fatigue resistance of metallic coated 7075 alloy substrates. Specimens prepared under these conditions show a similar fatigue resistance to uncoated substrates. © Canadian Institute of Mining, Metallurgy and Petroleum.

  • 3. 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, p. 318-330Conference 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.

  • 4. 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, p. 91-98Article 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.

  • 5. 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)
  • 6.
    Azar, Amin S.
    et al.
    SINTEF Mat & Chem, Oslo, Norway.
    Svensson, Lars-Erik
    University West, Department of Engineering Science, Division of Production Engineering.
    Nyhus, Bård
    SINTEF Mat & Chem, Oslo, Norway.
    Effect of crystal orientation and texture on fatigue crack evolution in high strength steel welds2015In: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 77, p. 95-104Article in journal (Refereed)
    Abstract [en]

    In the present study, electron backscattered diffraction is used to analyze the fatigue crack evolution in a high strength steel weld that was loaded cyclically in the plastic regime. Three prominent regions of a fatigue crack are investigated separately: crack tip, crack trajectory and crack initiation. Taylor and Schmid factors are mapped with respect to the defined loading matrix. Possible effective mechanisms are proposed based on the local plasticity properties like lattice rotation and misorientation. The analyses of the crack tip and trajectory regions show that although the critical resolved shear stresses in some regions are low, small deformation resistance of these regions can compromise the dislocation immobility and cause local fracture. It is shown that if the crack grows transgranularly, at least one side of the crack may show low lattice rotation or strain equivalent values, which indicates the relaxation of elastic stresses after fracture. The crack initiation is determined to be dominantly controlled by transcrystalline mechanism of initiation that takes place under plastic loading conditions. It is also shown that the secondary < 123 >11 (1) over bar type of slip systems were the most activated under such loading conditions. (C) 2015 Elsevier Ltd. All rights reserved.

  • 7. 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, p. 79-84Article 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.

  • 8.
    Battabyal, Manjusha
    et al.
    Chalmers University of Technology.
    Klement, Uta
    Chalmers University of Technology.
    Norell, Mats
    Chalmers University of Technology.
    Goutier, Simon
    University of Limoges.
    Markocsan, Nicolaie
    University West, Department of Engineering Science, Division of Production Engineering.
    Comparison of microstructure in Ni-Al single splats and millimeter sized droplets2011In: Surface Modification Technologies XXV : Proceedings of the Twenty Fith International Conference on Surface Modification Technologies - SMT25: Trolhättan June 20-22, 2011, 2011, p. 3-12Conference paper (Refereed)
  • 9. 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, p. 53-60Article in journal (Refereed)
  • 10. 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)
  • 11. 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, ISSN 0972-5784, 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.

  • 12. 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, p. 4534-4543Article 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.

  • 13.
    Charles, Corinne
    University West, Department of Engineering Science, Division of Production Engineering.
    Modelling microstructure evolution of weld deposited Ti-6Al-4V2008Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The microstructure and consequently the mechanical properties of titanium alloys are highly dependent on the temperature history endured by the material. The manufacturing process of metal deposition induces repetitive cooling and heating in the material determining a specific microstructure. The presented study is devoted to developing and implementing a microstructure model for Ti-6Al-4V intended to be coupled to a thermo- mechanical model of the metal deposition process.

    Microstructural analysis of the metal deposited samples was first performed to understand the formed microstructure. A set of representative parameters for microstructure modelling were then selected as representative for the known impact of Ti-6Al-4V microstructure on mechanical properties. Evolution equations for these parameters were implemented for thermal finite element analysis of the process. Six representative state variables are modelled: the phase volume fraction of total alpha, beta, Widmanstätten alpha, grain boundary alpha, martensite alpha, and the alpha lath thickness. Heating, cooling and repeated re-heating involved in the process of metal deposition are taken into account in the model. The phase transformations were modelled based on a diffusionnal theory described by a Johnson-Mehl-Avrami formulation, as well as diffusionless transformations for the martensite alpha formation and the beta reformation during reheating. The Arrhenius equation is applied as a simplification to model temperature dependent alpha lath size calculation. Grain growth is not included in the present formulation, but would have to be added for capturing alpha lath coarsening during long term heat treatment.

    The temperature history during robotised tungsten inert gas deposition welding is simulated together with the microstructure. The implementation of the model handles well the complex cyclic thermal loading from the metal deposition process. A particular banded structure observed in the metal deposited microstructure is partially explained using the proposed microstructure model. It is concluded that although qualitatively interesting results have been achieved, further calibration testing over a wider range of temperature histories must be performed to improve the transformation kinetic parameters for reliable quantitative predictions of the microstructure.

  • 14.
    Charles, Corinne
    et al.
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Järvstråt, Niklas
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Finite Element Modelling of Microstructure on GTAW Metal Deposition of Ti-6Al-4V alloy2006In: Computer Technology in Welding and Manufacturing : 16th International Conference & Mathematical Modelling and Information Technologies in Welding and Related Processes: Kiev, Ukraine, June 6-8, 2006Conference paper (Other academic)
  • 15.
    Chen, Y.
    et al.
    University of Manchester, School of Materials, Manchester, United Kingdom.
    Zhao, X.
    Shanghai Jiao Tong University, Shanghai Key Laboratory of Advanced High-Temperature Materials and Precision Forming, Shanghai, China .
    Dang, Y.
    University of Manchester, School of Materials, Manchester, United Kingdom.
    Xiao, Ping
    University of Manchester, School of Materials, Manchester, United Kingdom.
    Curry, Nicholas
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Markocsan, Nicolaie
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Nylén, Per
    University West, Department of Engineering Science, Division of Production Engineering.
    Characterization and understanding of residual stresses in a NiCoCrAlY bond coat for thermal barrier coating application2015In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 94, p. 1-14Article in journal (Refereed)
    Abstract [en]

    The residual stresses in a NiCoCrAlY bond coat deposited on a Ni-base superalloy substrate after oxidation at 1150 °C were studied by X-ray diffraction using the sin2Ψ technique. The stresses were found to be tensile; they first increased and then decreased with oxidation time. High temperature stress measurement indicated that the stress developed and built up upon cooling, predominantly within the temperature range from 1150 °C to 600 °C. Microstructural examination suggested that, due to the limited penetration depth into the bond coat, the X-ray only probed the stress in a thin surface layer consisting of the single γ-phase formed through Al depletion during oxidation. Quantitative high temperature X-ray diffraction analysis revealed that, above 600 °C, the volume fraction of the β-phase in the bond coat increased with decreasing temperature. The mechanisms of stress generation in the bond coat were examined and are discussed based on the experiments designed to isolate the contribution of possible stress generation factors. It was found that the measured bond coat stresses were mainly induced by the volume change of the bond coat associated with the precipitation of the β-phase upon cooling.

  • 16.
    Curry, Nicholas
    et al.
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Tang, Zhaolin
    Northwest Mettech Corp., Vancouver, Canada.
    Markocsan, Nicolaie
    University West, Department of Engineering Science, Division of Production Engineering.
    Nylén, Per
    University West, Department of Engineering Science, Division of Production Engineering.
    Influence of Bond Coat Surface Roughness on the Structure of Axial Suspension Plasma Spray Thermal Barrier Coatings - Thermal and Lifetime Performance2015In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 268, no April, p. 15-23Article in journal (Refereed)
  • 17. Davies, P.
    et al.
    Pederson, Robert
    University West, Department of Engineering Science, Division of Welding Technology. University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. Institute of Structural Materials, College of Engineering, Swansea University, Bay Campus, Fabian Way, Swansea SA1 8EN, United Kingdom.
    Coleman, M.
    Institute of Structural Materials, College of Engineering, Swansea University, Bay Campus, Fabian Way, Swansea SA1 8EN, United Kingdom.
    Birosca, S.
    Institute of Structural Materials, College of Engineering, Swansea University, Bay Campus, Fabian Way, Swansea SA1 8EN, United Kingdom.
    The hierarchy of microstructure parameters affecting the tensile ductility in centrifugally cast and forged Ti-834 alloy during high temperature exposure in air2016In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 117, p. 51-67Article in journal (Refereed)
    Abstract [en]

    Ductility regression is the main concern in using Ti-834 titanium alloy at temperatures above 500 °C for aerospace applications. The reduction of ductility in titanium alloys at high temperatures is strongly correlated to the exposure time. In the current study the effect of prolonged exposure at 500 °C on the tensile ductility of two differently processed Ti-834 alloys was investigated. In order to simulate actual Ti-834 processing routes, forged and centrifugally cast materials were used. The tensile tests were conducted on various specimens exposed at 500 °C for 100, 200 and 500 h to observe microstructure feature changes. Moreover, the effect of microstructure, microtexture, α-case, α2 and silicide precipitate coarsening during high temperature exposure was studied thoroughly. The cast alloy was found to have a minimum ductility and failed at 1.8% strain after exposure at 500 °C/500 h when the α-case layer was retained during testing, whilst, the ductility of the forged alloy was unaffected. The effects of individual microstructural parameters on the ductility regression in Ti-834 alloy were quantified. The results showed that 7.1% strain differences between the cast and forged alloy are related to microstructural variations including; morphology, lath widths, grain size and shape, grain orientations and microtexture. A total of 9.6% strain loss was observed in centrifugally cast Ti-834 after aging at 500°C/500 h and quantified as follow; 3.6% due to α-case formation during high temperature exposure, 0.2% due to α2-precipitates coarsening, 4.4% due to further silicide formation and coarsening, 1.4% due to additional microstructure changes during high temperature exposure. Furthermore, silicide coarsening on α/β phase boundaries caused large void formation around the precipitates. A theoretical model supported by experimental observations for silicide precipitation in fully colony and duplex microstructures was established. The element partitioning during exposure caused Al and Ti depletion in the vicinity of the β phase in the lamellae, i.e., αs area. This resulted in lowering the strength of the alloy and facilitated the formation of Ti3(SiZr)2 precipitates. The Al depletion and nano-scale partitioning observed at the αs/β boundaries resulted in easy crack initiation and promoted propagation in the centrifugally cast colony microstructure and reduced the basal slip τcrss. Furthermore, silicides were not formed in αp (high Al, Ti and low Zr areas) in the forged duplex microstructure that promoted superior mechanical performance and ductility over the cast alloy.

    Graphical abstract

  • 18.
    Edstorp, Marcus
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    A Comparison between Moving Mesh Implementations for Metal Deposition Simulations2006In: Proceedings of the Nordic COMSOL Conference: Lyngby, Denmark, 2006, p. 107-110Conference paper (Other academic)
  • 19.
    Fasth, Angelica
    et al.
    University West, Department of Engineering Science, Division of Production Engineering.
    Nylen, Per
    University West, Department of Engineering Science, Division of Production Engineering.
    Choi, B.
    Center for Theraml Spray Research, Stony Brook, New York.
    Klement, Uta
    Chalmers University.
    A Comparative studey of Mechanical Properties Between HVOF-spryed Maxphase Materials and Plasma Sprayed MCrAIY Coatings2009In: Surface Modification Technologies XXII: Proceedings of the Twenty Second International Conference on Surface Modification Technologies Held at University West, Trollhättan, Sweden September 22-24 2008 / [ed] T.S. Sudarshan & Per Nylen, VALAR Docs , 2009, p. 149-156Conference paper (Other academic)
  • 20.
    Harati, Ebrahim
    et al.
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Karlsson, Leif
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Svensson, Lars-Erik
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Dalaei, Kamellia
    ESAB AB, Gothenburg.
    The relative effects of residual stresses and weld toe geometry on fatigue life of weldments2015In: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 77, p. 160-165Article in journal (Refereed)
    Abstract [en]

    The weld toe is one of the most probable fatigue crack initiation sites in welded components. In this paper, the relative influences of residual stresses and weld toe geometry on the fatigue life of cruciform welds was studied. Fatigue strength of cruciform welds produced using Low Transformation Temperature (LTT) filler material has been compared to that of welds produced with a conventional filler material. LTT welds had higher fatigue strength than conventional welds. A moderate decrease in residual stress of about 15% at the 300 MPa stress level had the same effect on fatigue strength as increasing the weld toe radius by approximately 85% from 1.4 mm to 2.6 mm. It was concluded that residual stress had a relatively larger influence than the weld toe geometry on fatigue strength.

  • 21. Kaur, N.
    et al.
    Kumar, M.
    Sharma, S. K.
    Kim, D. Y.
    Kumar, S.
    Chavan, N. M.
    Joshi, Shrikant V.
    Singh, N.
    Singh, H.
    Study of mechanical properties and high temperature oxidation behavior of a novel cold-spray Ni-20Cr coating on boiler steels2015In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 328, p. 13-25Article in journal (Refereed)
    Abstract [en]

    In the current investigation, high temperature oxidation behavior of a novel cold-spray Ni-20Cr nano-structured coating was studied. The nanocrystalline Ni-20Cr powder was synthesized by the investigators using ball milling, which was deposited on T22 and SA 516 steels by cold spraying. The crystallite size based upon Scherrer's formula for the developed coatings was found to be in nano-range for both the substrates. The accelerated oxidation testing was performed in a laboratory tube furnace at a temperature 900 degrees C under thermal cyclic conditions. Each cycle comprised heating for one hour at 900 degrees C followed by cooling for 20 min in ambient air. The kinetics of oxidation was established using weight change measurements for the bare and the coated steels. The oxidation products were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy/Energy Dispersive Spectroscopy (SEM/EDS) and X-ray mapping techniques. It was found from the results that the coating was successful in reducing the weight gain of SA213-T22 and SA 516-Grade 70 steel by 71% and 94%, respectively. This may be attributed to relatively denser structure, lower porosity and lower oxide content of the coating. Moreover, the developed nano-structured Ni-20Cr powder coating was found to perform better than its counterpart micron-sized Ni-20Cr powder coating, in terms of offering higher oxidation resistance and hardness. (C) 2014 Elsevier B.V. All rights reserved.

  • 22.
    Lyphout, Christophe
    et al.
    University West, Department of Engineering Science, Division of Production Engineering.
    Nylén, Per
    University West, Department of Engineering Science, Division of Production Engineering.
    Manescu, A
    Università Politecnica delle Marche, Ancona, Italy.
    Pirling, T.
    Laue-Langevin Institute (ILL), Grenoble, France.
    Residual stresses distribution through thick HVOF sprayed inconel 718 coatings2008In: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 17, no 5-6, p. 915-923Article in journal (Refereed)
  • 23. Mandati, S.
    et al.
    Sarada, B. V.
    Dey, S. R.
    Joshi, Shrikant V.
    Photoelectrochemistry of Cu(In,Ga)Se2 thin-films fabricated by sequential pulsed electrodeposition2015In: Journal of Power Sources, Vol. 273, p. 149-157Article in journal (Refereed)
    Abstract [en]

    A novel approach for the fabrication of compact stoichiometric copper indium gallium selenium (CIGS) thin-films is reported. It uses a solution of CuCl2, GaCl3 and H2SeO3, pH adjusted with HCl with LiCl as additive employing a high purity graphite plate anode and Mo sputtered glass cathode during a simplified sequential pulsed current electrodeposition which avoids impurities from the use of a reference electrode during deposition and a separate selenization step. A Cu-Ga-Se film is optimally deposited by optimizing the deposition voltage, followed by deposition of In from InCl3 solution, and then annealing of the Cu-Ga-Se/In thin-film in an Argon atmosphere at 550 °C. A single phase chalcopyrite CIGS forms with a compact morphology and well-controlled composition of individual elements. The flat-band potential and carrier density of CIGS thin-films are -0.15 V and 2.6 × 1016 cm-3, respectively, as determined by Mott-Schottky studies. The photoelectrochemical performance of CIGS films shows a photocurrent density of -0.8 mA cm-2 at -0.4 V vs. SCE, an eight fold increment compared to our previous reported value. This simplified preparation using pulse plating gives superior quality CIGS films which are promising for application in thin-film solar cells and photoelectrochemical cells. © 2014 Elsevier B.V. All rights reserved.

  • 24.
    Medricky, Jan
    et al.
    Czech Technical University in Prague, Prague, Czech Republic.
    Curry, Nicholas
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Pala, Zdenek
    Institute of Plasma Physics AS CR, Prague, Czech Republic.
    Vilemova, Monika
    Institute of Plasma Physics AS CR, Prague, Czech Republic.
    Chraska, Tomas
    Institute of Plasma Physics AS CR, Prague, Czech Republic.
    Johansson, Jimmy
    GKN Aerospace Engine Systems, Trollhättan, Darrasa, Sweden.
    Markocsan, Nicolaie
    University West, Department of Engineering Science, Division of Production Engineering.
    Optimization of High Porosity Thermal Barrier Coatings Generated with a Porosity Former2015In: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 24, no 4, p. 622-628Article in journal (Refereed)
    Abstract [en]

    Yttria-stabilized zirconia thermal barrier coatings are extensively used in turbine industry; however, increasing performance requirements have begun to make conventional air plasma sprayed coatings insufficient for future needs. Since the thermal conductivity of bulk material cannot be lowered easily; the design of highly porous coatings may be the most efficient way to achieve coatings with low thermal conductivity. Thus the approach of fabrication of coatings with a high porosity level based on plasma spraying of ceramic particles of dysprosia-stabilized zirconia mixed with polymer particles, has been tested. Both polymer and ceramic particles melt in plasma and after impact onto a substrate they form a coating. When the coating is subjected to heat treatment, polymer burns out and a complex structure of pores and cracks is formed. In order to obtain desired porosity level and microstructural features in coatings; a design of experiments, based on changes in spray distance, powder feeding rate, and plasma-forming atmosphere, was performed. Acquired coatings were evaluated for thermal conductivity and thermo-cyclic fatigue, and their morphology was assessed using scanning electron microscopy. It was shown that porosity level can be controlled by appropriate changes in spraying parameters.

  • 25.
    Nylén, Per
    University West, Department of Engineering Science, Division of Production Engineering.
    Applications of thermal spray technology for aerospace and automotive industry2013In: Heat Treatment and Surface Engineering - Proceedings of Heat Treatment and Surface Engineering, HTSE 20132013: HT & SE 2013, 16 to 18 May 2013, Chennai Trade Centre, Chennai, India / [ed] Bakshi S.R.,Kamaraj M.,Mudali U.K.,Sudarshan T.S.,Raj B.,Murty B.S., ASM International, 2013, p. 65-68Conference paper (Refereed)
    Abstract [en]

    Thermal spraying can provide thick coatings (approx. thickness range is 20 micrometers to several mm, depending on the process and feedstock), over a large area at high deposition rate as compared to other coating processes such as electroplating, physical and chemical vapour deposition. Coating materials available for thermal spraying include metals, alloys, ceramics, ptastics and composites Thermal spraying provides engineered coating solutions for a wide range of industrial applications. The aerospace industry was one of the first to exploit the benefits of thermal spray coatings. Nowadays, thermal spray technology is used in a large number of applications within this industry meeting high performance and quality requirements. Examples of applications within the aerospace sector are landing gears, abrasion wear resistant coatings, engines (combustion liners, discharge nozzles, blades, and compressor casings), and wing structures. An emerging application area for thermal spraying is the automotive area. Examples of applications within this area are synchronisation rings, piston rings, cylinder heads, turbocharger abradables, brake discs, cylinder bores, and hard chrom replacement This talk discusses some thermal spray applications within the aerospace and automotive sectors.

  • 26.
    Odenberger, Eva-Lis
    et al.
    Luleå University of Technology, Division of Mechanics of Solid Materials, Luleå, SE-971 87, Sweden; Division Materials and Production, RISE IVF AB, RISE Research Institutes of Sweden, Vällaregatan 30, Olofström, SE-293 38, Sweden.
    Pederson, Robert
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Oldenburg, Mats
    Luleå University of Technology, Division of Mechanics of Solid Materials, Luleå, SE-971 87, Sweden.
    Finite element modeling and validation of springback and stress relaxation in the thermo-mechanical forming of thin Ti-6Al-4V sheets2019In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 104, no 9-12, p. 3429-3455Article in journal (Refereed)
    Abstract [en]

    In this work, a hot forming procedure is developed using computer-aided engineering (CAE) to produce thin Ti-6Al-4V sheet components in an effective way. Traditional forming methods involve time- and cost-consuming furnace heating and subsequent hot sizing steps. A material model for finite element (FE) analyses of sheet metal forming and springback at elevated temperatures in Ti-6Al-4V is calibrated and evaluated. The anisotropic yield criterion proposed by Barlat et al. 2003 is applied, and the time- and temperature-dependent stress relaxation behavior for elastic and inelastic straining are modeled using a Zener–Wert–Avrami formulation. Thermo-mechanical uniaxial tensile tests, a biaxial test, and uniaxial stress relaxation tests are performed and used as experimental reference to identify material model parameters at temperatures up to 700 °C. The hot forming tool setup is manufactured and used to produce double-curved aero engine components at 700 °C with different cycle times for validation purposes. Correlations between the predicted and measured responses such as springback and shape deviation show promising agreement, also when the forming and subsequent holding time was as low as 150 s. The short cycle time resulted in elimination of a detectable alpha case layer. Also, the tool surface coating extends the tool life in combination with a suitable lubricant. © 2019, The Author(s).

  • 27.
    Puneet, C.
    et al.
    International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Hyderabad, India.
    Valleti, Krishna
    International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Hyderabad, India.
    Venu Gopal, A.
    National Institute of Technology, Warangal, India.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Research Enviroment Production Technology West. International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Hyderabad, India.
    CrAlSiN nanocomposite thin films for high-speed machining applications2018In: Materials and Manufacturing Processes, ISSN 1042-6914, E-ISSN 1532-2475, Vol. 33, no 4, p. 371-377Article in journal (Refereed)
    Abstract [en]

    CrAlSiN nanocomposite thin films with varying film chemistry were developed on tungsten carbide (WC)specimens using cylindrical cathodic arc physical vapor deposition (c-CAPVD) technique. The physical, mechanical, and tribological properties of all the films were comprehensively investigated for arriving at the film chemistry leading to the best properties with respect to mechanical applications. The best tribo-mechanical properties were obtained in films with Cr/(AlþSi) ratio of 1.2. This coating with best properties was translated on to WC drill bits for machining tests. The Al and Si content has shown major influence on the adhesion strength and phase constitution of the films, with a considerable change in residual stress too. The superior properties achieved could be attributed to the formation of an ear-perfect nanocomposite structure, with the crystalline CrAlN phase surrounded by an amorphous Si3N4 phase. The tool life of the coated CrAlSiN tools was investigated during dry machining of EN 24material. In comparison to the tool life of an uncoated tool and a TiAlSiN-coated tool, the best CrAlSiN coatings synthesized in this study performed exceedingly well. The present study clearly demonstrates the advantages of CrAlSiN over other existing similar coatings for high-speed machining.

  • 28.
    Sefer, Birhan
    et al.
    Division of Materials Science, Luleå University of Technology, Luleå, Sweden / Department of Materials Science and Metallurgical Engineering, Universitat Politècnica de Catalunya, Barcelona, Spain.
    Dobryden, Illia
    Division of Materials Science, Luleå University of Technology, Luleå, Sweden / Division of Surface and Corrosion Science, KTH Royal Institute of Technology, Stockholm, Sweden.
    Almqvist, Nils
    Division of Materials Science, Luleå University of Technology, Luleå, Sweden.
    Pederson, Robert
    University West, Department of Engineering Science, Division of Welding Technology. Division of Materials Science, Luleå University of Technology, Luleå, Sweden / Research and Technology Centre, GKN Aerospace Engine Systems, Trollhättan, Sweden.
    Antti, Marta-Lena
    Division of Materials Science, Luleå University of Technology, Luleå, Sweden.
    Chemical Milling of Cast Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo Alloys in Hydrofluoric-Nitric Acid Solutions2017In: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 73, no 4, p. 394-407Article in journal (Refereed)
    Abstract [en]

    The behavior of cast Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo during chemical milling in hydrofluoric-nitric (HF-HNO3) acid solutions with 1:3 and 1:11 molar ratios was investigated using electrochemical and atomic force microscopy (AFM) techniques. Faster corrosion rate in 1:3 solutions was measured for Ti-6Al-4V than for Ti-6Al-2Sn-4Zr-2Mo, whereas in 1:11 solution Ti-6Al-2Sn-4Zr-2Mo exhibited higher corrosion rate. Scanning Kelvin probe force microscopy measurements revealed difference in the Volta potential between the α-laths and the β-layers in the Widmansttäten microstructure indicating operation of microgalvanic cells between the microconstituents when in contact with HF-HNO3 solution. The AFM topography measurements demonstrated faster corrosion of the α-laths compared to the β-layers, in both alloys. In 1:3 solutions, higher α/β height difference was measured in Ti-6Al-4V, whereas in 1:11 solution, the difference was higher in Ti-6Al-2Sn-4Zr-2Mo. The results revealed that the chemical milling behavior of the two investigated alloys is controlled by the microscopic corrosion behavior of the individual microconstituents.

  • 29.
    Stenbacka, Nils
    University West, Department of Engineering Science, Research Environment Production Technology West.
    On arc efficiency in gas tungsten arc welding: Sobre eficiência de arco em soldagem GTAW2013In: Soldagem & Inspeção, ISSN 0104-9224, E-ISSN 1980-6973, Vol. 18, no 4, p. 380-390Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to review the literature on published arc efficiency values for GTAW and, if possible, propose a narrower band. Articles between the years 1955 - 2011 have been found. Published arc efficiency values for GTAW DCEN show to lie on a wide range, between 0.36 to 0.90. Only a few studies covered DCEP - direct current electrode positive and AC current. Specific information about the reproducibility in calorimetric studies as well as in modeling and simulation studies (considering that both random and systematic errors are small) was scarce. An estimate of the average arc efficiency value for GTAW DCEN indicates that it should be about 0.77. It indicates anyway that the GTAW process with DCEN is an efficient welding method. The arc efficiency is reduced when the arc length is increased. On the other hand, there are conflicting results in the literature as to the influence of arc current and travel speed.

  • 30. Sudarshan, T.S.
    et al.
    Nylen, PerUniversity West, Department of Engineering Science, Division of Production Engineering.
    Surface Modification Technologies XXII: Proceedings of the Twenty Second International Conference on Surface Modification Technologies  Held at University West, Trollhättan, Sweden September 22-24, 20082009Conference proceedings (editor) (Other academic)
  • 31.
    Zou, Zhonghua
    et al.
    Shanghai Jiao Tong University, Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming, Shanghai 200240, China .
    Donoghue, Jack
    University of Manchester, School of Materials, Grosvenor Street, Manchester M1 7HS, UK .
    Curry, Nicholas
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Yang, Lixia
    Shanghai Jiao Tong University, Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming, Shanghai 200240, China .
    Guo, Fangwei
    Shanghai Jiao Tong University, Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming, Shanghai 200240, China .
    Nylén, Per
    University West, Department of Engineering Science, Division of Production Engineering.
    Zhao, Xiaofeng
    Shanghai Jiao Tong University, Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming, Shanghai 200240, China .
    Xiao, Ping
    Shanghai Jiao Tong University, Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming, Shanghai 200240, China .
    A comparative study on the performance of suspension plasma sprayed thermal barrier coatings with different bond coat systems2015In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 275, p. 276-282Article in journal (Refereed)
    Abstract [en]

    The performance of suspension plasma sprayed (SPS) yttria stabilized zirconia (YSZ) thermal barrier coatings (TBCs) after isothermal treatment at 1150. °C was investigated. The NiCoCrAlY bond coats were applied by air plasma spray (APS) and high velocity oxygen fuel (HVOF) techniques. It was found that the microstructure of SPS TBCs depends on the surface morphology of the bond coat. The SPS TBCs with a rough APS bond coat exhibited a longer lifetime than those with a smooth HVOF bond coat. To understand this phenomenon, the evolution of the microstructure, mechanical properties and the residual stresses in the TBCs and TGO were systematically studied. Results showed that the surface roughness and oxidation behavior of the bond coat play dominant roles in the SPS TBC failure. © 2015.

  • 32.
    Åström, Hans
    et al.
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Stenbacka, Nils
    University West, Department of Engineering Science, Research Environment Production Technology West.
    Hurtig, Kjell
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Arc Efficiency for Gas Tungsten Arc Welding DCEN-GTAW2013Conference paper (Refereed)
1 - 32 of 32
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