Change search
Refine search result
123456 101 - 150 of 259
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 101. Joshi, S. V.
    et al.
    Srivastava, M. P.
    Chatterjee, M.
    Ray, J.
    Chatterjee, A.
    Ganguli, D.
    Plasma spraying of an indigenous yttria stabilized zirconia powder prepared by the sol-gel technique1993In: Bulletin of Materials Science, Vol. 16, no 1, p. 19-28Article in journal (Refereed)
    Abstract [en]

    An indigenous sol-gel derived yttria-partially stabilized zirconia (Y-PSZ) powder has been characterized and its suitability for plasma spraying applications evaluated. The powder, determined to have about 5·1% yttria content, predominantly consisted of spherical particles with an average equivalent particle diameter close to 25 μm. Furthermore, it was found that the powder did not contain any particles >50 μm, which is considered the ideal upper size limit for spray-grade ceramic powders in order to ensure complete melting during spraying. The sol-gel produced powder exhibited good flow characteristics and the plasma sprayed coatings developed using this powder were also found to have excellent thermal shock resistance. The corresponding results obtained using an imported Y-PSZ powder are also presented for the purpose of comparison. © 1993 Indian Academy of Sciences.

  • 102. Joshi, S. V.
    et al.
    Srivastava, M. P.
    Pal, A.
    Pal, S.
    Plasma spraying of biologically derived hydroxyapatite on implantable materials1993In: Journal of Materials Science: Materials in Medicine, Vol. 4, no 3, p. 251-255Article in journal (Refereed)
    Abstract [en]

    Plasma spraying of hydroxyapatite (HA) coatings on human implants is considered to provide a promising means of enhancing their biocompatibility and improving tissue growth. This paper briefly describes a method of extracting HA powder from a biological source, namely human teeth. The physical and chemical characteristics of the derived powder are studied and the suitability of this powder for plasma spraying applications is ascertained. The deposited coatings are found to retain the chemistry characteristic of the apatite. Typical results of metallographic and scanning electron microscopy (SEM) studies and hardness measurements on the sprayed HA coatings are presented. © 1993 Chapman & Hall.

  • 103. Joshi, S. V.
    et al.
    Srivastava, M. P.
    Sundararajan, G.
    Evidence of accelerated thermal cycling test schedules influencing the ranking of zirconia-base thermal barrier coatings1995In: Journal of Thermal Spray Technology, Vol. 4, no 3, p. 275-279Article in journal (Refereed)
    Abstract [en]

    Thermal barrier coatings (TBCs) often encounter temperature cycling in the course of normal operation. In the absence of actual or simulated engine test facilities, accelerated furnace thermal cycling experiments are frequently devised to evaluate the response of various TBCs. This study, which deals with yttria-stabilized and magnesia-stabilized zirconia systems, shows that the performance of a TBC is significantly governed by the severity of the time-temperature schedule employed. More importantly, the ranking of the two zirconia-base TBCs also is influenced by the adopted thermal cycling test schedule. These findings have ramifications in the design of suitable accelerated tests for TBC evaluation.

  • 104. Joshi, S. V.
    et al.
    Sundararajan, G.
    Bell, T.
    Surface engineering in India: On the upswing2004In: Surface Engineering, ISSN 0267-0844, E-ISSN 1743-2944, Vol. 20, no 2, p. 81-82Article in journal (Refereed)
  • 105. Joshi, S. V.
    et al.
    Thawari, G.
    Kumar, L. S.
    Sen, D.
    Sundararajan, G.
    Influence of Laser Glazing on the Characteristics and Tribological Performance of Plasma and Detonation Sprayed WC-Co Coatings2001In: Proceedings of the International Thermal Spray Conference, 2001, p. 583-592Conference paper (Refereed)
    Abstract [en]

    This paper deals with a comprehensive evaluation of the laser glazing or re-melting route as a possible means of specifically enhancing the performance of thermal sprayed WC-Co coatings. In the present study, a high-power continuous-wave 9kW CO2 laser was utilized for laser treatment of plasma sprayed as well as detonation sprayed WC-Co coatings. The influence of the two most important laser-related variables, namely laser power and scan speed, on the properties of the laser-treated layers was investigated. Both mere surface densification by melting a thin top layer of the coating as well as melting of the entire portion of the coated layer were targeted during laser treatment. In each case, the laser treated coatings were fully characterized by optical microscopy, scanning electron microscopy, and microhardness measurements. In addition, the influence of laser processing on the elemental distribution, phase constitution and extent of defects in the treated layers was investigated. The tribological performance of the laser-glazed coatings was also evaluated and compared against the performance of their as-sprayed counterparts. The study has revealed significant differences between the response of plasma and detonation sprayed WC-Co layers when subjected to laser treatment. The potential of plasma-sprayed coatings to match the performance of the inherently superior detonation sprayed coatings by adopting laser glazing as a post-processing step has also been assessed.

  • 106.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Coating formation by solution precursor plasma spraying and prospects for powder-solution hybrid processing2016Conference paper (Other academic)
  • 107.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Experiences of spraying fine powders dissolved in alcohol or water2016Conference paper (Other academic)
  • 108.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Special Issue: Advances in Thermal Spray Technology2020In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 13, no 16, article id E3521Article in journal (Refereed)
    Abstract [en]

    Coatings deposited utilizing different thermal spray variants have been widely used for diverse industrial applications [...].

    Download full text (pdf)
    fulltext
  • 109.
    Joshi, Shrikant V.
    et al.
    Defence Metallurgical Research Lab., Hyderabad, India.
    Ganguli, D.
    Central Glass and Ceramic Research Inst., Calcutta, India.
    Plasma spraying of ceramic powders produced by the sol-gel technique1992In: Metals Materials and Processes, ISSN 0970-423X, Vol. 4, no 1, p. 33-42Article in journal (Refereed)
    Abstract [en]

    The development of plasma-sprayed protective layers to enhance the surface properties of critical engineering components represents one of the most promising achievements of materials technology in recent times. The important aspects associated with plasma spraying of ceramic powders are discussed and the influence of the powder characteristics on the quality of sprayed coatings is highlighted. The advantages of the sol-gel technique for preparing spray grade powders are briefly outlined. The sol-gel synthesis of a Yttria-stabilized-zirconia powder is discussed as a case study. Results of powder characterization studies and evaluation of its plasma sprayed coating are also presented.

  • 110.
    Joshi, Shrikant V.
    et al.
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Goel, Sneha
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Björklund, S.
    Wiklund, U.
    Hybrid powder-suspension Al2O3-ZrO2 coatings by axial plasma spraying: Processing, characteristics & tribological behavior2017Conference paper (Other academic)
  • 111.
    Joshi, Shrikant V.
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Markocsan, Nicolaie
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Nylén, Per
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Sivakumar, G.
    International Advanced Research Centre for Powder Metallurgy & New Materials (ARCI), Hyderabad, India (IND).
    New Generation Ceramic Coatings for High-Temperature Applications by Liquid Feedstock Plasma Spraying: Defense, Security, Aerospace and Energy Applications2020In: Handbook of Advanced Ceramics and Composites / [ed] Mahajan, Yashwant; Roy, Johnson, Cham: Springer, 2020, p. 1-42Chapter in book (Other academic)
    Abstract [en]

    Plasma spraying with liquid feedstock offers an exciting opportunity to obtain coatings with characteristics that are vastly different from those produced using conventional spray-grade powders. The two extensively investigated variants of this technique are suspension plasma spraying (SPS), which utilizes a suspension of fine powders in an appropriate medium, and solution precursor plasma spraying (SPPS), which involves use of a suitable solution precursor that can form the desired particles in situ. The advent of axial injection plasma spray systems in recent times has also eliminated concerns regarding low deposition rates/efficiencies associated with liquid feedstock. The 10–100 μm size particles that constitute conventional spray powders lead to individual splats that are more than an order of magnitude larger compared to those resulting from the fine (approximately 100 nm–2 μm in size) particles already present in suspensions in SPS or formed in situ in SPPS. The distinct characteristics of the resulting coatings are directly attributable to the above very dissimilar splats (“building blocks” for coatings) responsible for their formation. This chapter discusses the salient features associated with SPS and SPPS processing, highlights their versatility for depositing a vast range of ceramic coatings with diverse functional attributes, and discusses their utility, particularly for high-temperature applications through some illustrative examples. A further extension of liquid feedstock plasma processing to enable use of hybrid powder-liquid combinations for plasma spraying is also discussed. This presents a novel approach to explore new material combinations, create various function-dependent coating architectures with multi-scale features, and enable convenient realization of layered, composite, and graded coatings as demonstrated through specific examples.

  • 112.
    Joshi, Shrikant V.
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Nylén, Per
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Advanced Coatings by Thermal Spray Processes2019In: Technologies, E-ISSN  2227-7080, Vol. 7, no 4, p. 1-14, article id 79Article in journal (Refereed)
    Abstract [en]

    Coatings are pivotal in combating problems of premature component degradation in aggressive industrial environments and constitute a strategic area for continued development. Thermal spray (TS) coatings offer distinct advantages by combining versatility, cost-effectiveness, and the ability to coat complex geometries without constraints of other in-chamber processes. Consequently, TS techniques like high-velocity oxy-fuel (HVOF) and atmospheric plasma spray (APS) are industrially well-accepted. However, they have reached limits of their capabilities while expectations from coatings progressively increase in pursuit of enhanced efficiency and productivity. Two emerging TS variants, namely high-velocity air-fuel (HVAF) and liquid feedstock thermal spraying, offer attractive pathways to realize high-performance surfaces superior to those hitherto achievable. Supersonic HVAF spraying provides highly adherent coatings with negligible porosity and its low processing temperature also ensures insignificant thermal ‘damage’ (oxidation, decarburization, etc.) to the starting material. On the other hand, liquid feedstock derived TS coatings, deposited using suspensions of fine particles (100 nm–5 µm) or solution precursors, permits the production of coatings with novel microstructures and diverse application-specific architectures. The possibility of hybrid processing, combining liquid and powder feedstock, provides further opportunities to fine tune the properties of functional surfaces. These new approaches are discussed along with some illustrative examples.

    Download full text (pdf)
    fulltext
  • 113. Joshi, Shrikant V.
    et al.
    Sivakumar, G.
    Hybrid Processing with Powders and Solutions: A Novel Approach to Deposit Composite Coatings2015In: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 24, no 7, p. 1166-1186Article in journal (Refereed)
    Abstract [en]

    Thermal spraying employing either solution precursor or suspension feedstock offers an exciting opportunity to obtain coatings with microstructures and characteristics that differ vastly compared to those conventionally produced using spray-grade powders. Both solution precursor plasma spray and suspension plasma spray techniques have been explored extensively in recent years for depositing wide ranging ceramic coatings for various functional applications. Encouraged by the properties achieved using the above solution-based feedstocks, a hybrid approach involving dual injection of solutions and powders, either simultaneously or sequentially, has been proposed and demonstrated to yield novel coating architectures. Although prior work on such hybrid processing is very limited, this overview seeks to present the concept, outline associated challenges, and demonstrate its efficacy to realize coatings with exciting and unusual properties using some illustrative examples. © 2015 ASM International

  • 114. Joshi, Shrikant V.
    et al.
    Sivakumar, R.
    An Analytical Approach to Plasma Spraying1993In: Plasma spraying: Theory and applications / [ed] Suryanarayanan, R., New Jersey: World Scientific, 1993, p. 121-137Chapter in book (Refereed)
  • 115. Joshi, Shrikant V.
    et al.
    Srivastava, P.
    Lifetime determining factors during thermal cycling of zirconia based thermal barrier coatings1995In: Surface Engineering, ISSN 0267-0844, E-ISSN 1743-2944, Vol. 11, no 3, p. 233-239Article in journal (Refereed)
    Abstract [en]

    Plasma sprayed yttria stabilised zirconia (YSZ) coatings were investigated to assess the factors influencing their durability during thermal cycling. For any given powder, the best performance was found to be achieved at an optimum plasma arc current, all other spray parameters being held constant. The YSZ overlayer thickness was found to be an important lifetime determining factor. Use of a NiCoCrAlY bond coat instead of Ni–Cr led to a substantial improvement in coating lifetime, with the enhancement provided by NiCoCr AlY becoming more pronounced with increasing porosity level of the ceramic overlayer. A post-coating heat treatment was also found to be beneficial to coating longevity. The relative ranking of magnesium zirconate and YSZ coatings was found to depend upon the thermal cycle adopted during testing, which has important implications in designing accelerated tests to evaluate coating performance.

  • 116.
    Karthick Raaj, R.
    et al.
    VIT, School of Mechanical Engineering,Vellore, India (IND).
    Vijay Anirudh, P.
    Anna University, Department of Manufacturing Engineering, College of Engineering, Chennai, India (IND).
    Karunakaran, C.
    VIT, School of Mechanical Engineering,Vellore, India (IND).
    Kannan, C.
    VIT, School of Mechanical Engineering,Vellore, India (IND).
    Jahagirdar, Adwait
    Anna University, Department of Manufacturing Engineering, College of Engineering, Chennai, India (IND).
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Balan, A. S. S.
    NIT, Department of Mechanical Engineering, Surathkal, Karnataka, India (IND).
    Exploring grinding and burnishing as surface post-treatment options for electron beam additive manufactured Alloy 7182020In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 397, article id 126063Article in journal (Refereed)
    Abstract [en]

    Numerous additive manufacturing (AM) techniques have been developed over the past decade. Features like immense freedom of intricate part design and shorter lead time make AM routes promising for a wide range of applications spanning aerospace, marine and automobile sectors. Among the various metal AM processes, Electron Beam Additive Manufacturing (EBAM) is being widely explored to realise the potential of Ni-based superalloys and Ti alloys for varied high-performance applications. A novel attempt has been made in this paper to assess the surface integrity of as-built EBAM nickel-based superalloy 718 (AB) subjected to grinding (G), Low Plasticity Burnishing (LPB) and their sequential combination. Apart from their influence on sub-surface microstructures, the effect of process variables during the above post-treatments on the residual stress profiles was also investigated. Results revealed that G + LPB results in about 0.6 ÎŒm lower surface roughness, 17% improved microhardness compared to AB + LPB, and higher compressive surface residual stress as compared to LPB processed EBAM samples. The sequential grinding and LPB - improved microhardness, was also found to extend about 500 ÎŒm more when compared to the LPB process. The G + LPB, which is greatly influenced by the prior grinding, smoothens the surface and thus results in a better surface finish. Highest hardness, superior surface finish, reduced porosity and improved compressive residual stress were observed in samples that adopted the AB + G + LPB sequence over other samples, with the LPB step at 40 MPa yielding the best results. © 2020 Elsevier B.V.

  • 117. Karthik, Dhadala
    et al.
    Pendse, Saloni
    Sakthivel, Shanmugasundaram
    Ramasamy, Easwaramoorthi
    Joshi, Shrikant Vishwanath
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    High performance broad band antireflective coatings using a facile synthesis of ink-bottle mesoporous MgF2 nanoparticles for solar applications2017In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 159, p. 204-211Article in journal (Refereed)
    Abstract [en]

    Ultra-low refractive index thin films suitable for practical antireflective (AR) applications must be highly transparent, economical, and durable against temperature and weather conditions. In this work, we present a high performance broad band antireflective coating using a facile synthesis of Ink-Bottle mesoporous MgF2 nanoparticles. The nanoparticles having high crystalline and dispersible properties were prepared by a deformation-reformation route from coarse commercial MgF2 hydrate powder by Lyothermal synthesis. These nanoparticles, after dispersion in a suitable solvent were used to develop a single layer AR coating by dip-coating technique. We precisely developed coatings tunable to achieve minimum reflection losses between 400 and 1500 nm. The AR coating exhibited nearly 100% transmittance within visible range (615–660 nm) and an average transmittance of 99% and 97% in the visible (400–800 nm) and active solar range (300–1500 nm) respectively. Further, use of the AR coating on PV glass led to a net improvement of 6% in efficiency for c-Si solar cells. This work opens a promising approach to improve the device performance of solar cells as well as solar collectors by developing broad band antireflective surfaces using mesoporous nanoparticles.

  • 118. 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.

  • 119.
    Khan, Pearlin Amaan
    et al.
    Centre for Biomaterials, Cellular & Molecular Theranostics (CBCMT), Vellore Institute of Technology, Vellore 632014 (IND).
    Thoutam, Aravind Kumar
    University West, Department of Engineering Science.
    Gopal, Vasanth
    Centre for Biomaterials, Cellular & Molecular Theranostics (CBCMT), Vellore Institute of Technology, Vellore 632014, (IND); School of Advanced Sciences, Vellore Institute of Technology, Vellore 632014 (IND).
    Gurumallesh, Aswin
    Centre for Biomaterials, Cellular & Molecular Theranostics (CBCMT), Vellore Institute of Technology, Vellore 632014, (IND); School of Advanced Sciences, Vellore Institute of Technology, Vellore 632014 (IND).
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Palaniappan, Arunkumar
    Centre for Biomaterials, Cellular & Molecular Theranostics (CBCMT), Vellore Institute of Technology, Vellore 632014, (IND).
    Markocsan, Nicolaie
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Manivasagam, Geetha
    Centre for Biomaterials, Cellular & Molecular Theranostics (CBCMT), Vellore Institute of Technology, Vellore 632014, (IND) .
    Influence of Graphene Nanoplatelets on the Performance of Axial Suspension Plasma-Sprayed Hydroxyapatite Coatings.2022In: Bioengineering, E-ISSN 2306-5354, Vol. 10, no 1, p. -22, article id 44Article in journal (Refereed)
    Abstract [en]

    Axial suspension plasma spraying (ASPS) is an alternative technique to atmospheric plasma spraying (APS), which uses a suspension of much finer powders (<5-micron particle size) as the feedstock. It can produce more refined microstructures than APS for biomedical implants. This paper highlights the influence of incorporated graphene nanoplatelets (GNPs) on the behavior of ASPS hydroxyapatite (HAp) coatings. The characterization of the ASPS coatings (HAp + varying GNP contents) was carried out using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), confocal Raman microscopy (CRM), white light interferometry (WLI), and contact angle measurements. The evaluation of the mechanical properties such as the hardness, roughness, adhesion strength, and porosity was carried out, along with a fretting wear performance. Additionally, the biocompatibility of the Hap + GNP coatings was evaluated using cytotoxicity testing which revealed a decrease in the cell viability from 92.7% to 85.4%, with an increase in the GNP wt.%. The visualization of the cell's components was carried out using SEM and Laser Scanning Microscopy. Furthermore, the changes in the genetic expression of the various cellular markers were assessed to analyze the epigenetic changes in human mesenchymal stem cells. The gene expression changes suggested that GNPs upregulated the proliferation marker and downregulated the pluripotent markers by a minimum of three folds.

    Download full text (pdf)
    fulltext
  • 120.
    Kiilakoski, Jarkko
    et al.
    Tampere University, Materials Science and Environmental Engineering, Tampere Finland.
    Trache, Richard
    Treibacher Industrie AG, Althofen, Austria.
    Björklund, Stefan
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Vuoristo, Petri
    Tampere University, Materials Science and Environmental Engineering, Tampere Finland.
    Process Parameter Impact on Suspension-HVOF-Sprayed Cr2O3 Coatings2019In: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 28, no 8, p. 1933-1944Article in journal (Refereed)
    Abstract [en]

    Chromium oxide (Cr2O3) is commonly used as an atmospheric plasma-sprayed (APS) coating from powder feedstock in applications requiring resistance to sliding wear and corrosion, as well as amenability to texturing, e.g., in anilox rolls. Recently, high-velocity oxy-fuel spray methods involving suspension feedstock have been considered an extremely promising alternative to produce denser and more homogeneous chromium oxide coatings with lower as-sprayed surface roughness, higher hardness and potentially superior wear performance compared to conventional APS-sprayed coatings. In this study, the impact of process parameters namely auxiliary air cleaning nozzles and a transverse air curtain on suspension high-velocity oxy-fuel-sprayed Cr2O3 suspensions is presented. The produced coatings are characterized for their microstructure, mechanical properties and wear resistance by cavitation erosion. The results reveal the importance of optimized air nozzles and air curtain to achieve a vastly improved coating structure and performance.

  • 121.
    Kiilakoski, Jarmo
    et al.
    Tampere University, Materials Science and Environmental Engineering, Tampere Finland.
    Trache, Richard
    Treibacher Industrie AG, Althofen, Austria..
    Björklund, Stefan
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Vuoristo, Petri
    Tampere University, Materials Science and Environmental Engineering, Tampere Finland.
    Correction to: Process Parameter Impact on Suspension-HVOF-Sprayed Cr2O3 Coatings (Journal of Thermal Spray Technology, (2019), 28, 8, (1933-1944), 10.1007/s11666-019-00940-7)2019In: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 28, no 8Article in journal (Refereed)
    Abstract [en]

    In the references section there is a correction to reference number 41. It should read as follows: V. Matikainen, S. Rubio Peregrina, N. Ojala, H. Koivuluoto, J. Schubert, S. HoudkovaÂŽ, and P. Vuoristo, Erosion Wear Performance of WC-10Co4Cr and Cr3C2– 25NiCr Coatings Sprayed with High-Velocity Thermal Spray Processes, Surf. Coat. Technol., 2019, 370, p 196- 212. © 2019, ASM International.

  • 122. Koppoju, S.
    et al.
    Shariff, S. M.
    Singh, A. K.
    Mantripragada, R.
    Gadhe, P.
    Joshi, S. V.
    Evolution of texture during laser surface treatment of an austenitic manganese steel2015In: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 102, p. 29-34Article in journal (Refereed)
    Abstract [en]

    This work describes the evolution of microstructure and texture of an austenitic manganese steel (1.34C-13.6Mn-0.45Si-Fe, wt.%) during surface modification using a high power diode laser. Strong (002) texture has been observed on the surface of the steel with increase in interaction time. It has been found that columnar type dendrites are responsible for the strong texture which is favorably grown in the < 001 > direction perpendicular to the substrate plane. The growth of dendrites with specific crystallographic direction is governed by the interfacial energy anisotropy and thermal gradient direction. (C) 2015 Elsevier Inc. All rights reserved.

  • 123. Krishna, G. R.
    et al.
    Das, D. K.
    Singh, V.
    Joshi, S. V.
    Role of Pt content in the microstructural development and oxidation performance of Pt-aluminide coatings produced using a high-activity aluminizing process1998In: Materials Science and Engineering A, Vol. 251, no 1-2, p. 40-47Article in journal (Refereed)
    Abstract [en]

    The present study highlights the effect of Pt content on the microstructure of Pt-aluminide coatings produced using a single-step high-activity aluminizing process. The amount of Pt in the coating was varied by changing the thickness of the initial electroplated Pt layer between 1 and 15 μm. The aluminium uptake from the pack was found to be almost the same for all the coatings produced using a Pt layer of thickness 2.5 μm and above, with a somewhat lower uptake for the coating corresponding to a 1 μm thick Pt layer. The coating microstructure, which consisted of an outer two-phase (PtAl2 in a matrix of NiAl) layer, an intermediate NiAl layer and an interdiffusion layer, was also found to be independent of the Pt layer thickness when it was in the range 2.5-10 μm. In the case of the 1 μm Pt layer, however, the whole of the Pt remained in solid solution in the NiAl phase. For a Pt layer thickness exceeding 10 μm, on the other hand, a continuous surface layer of PtAl2 phase was observed. The above mentioned influence of the thickness of the Pt plated layer on the microstructure of the Pt-aluminide coatings observed in the present investigation could be explained in terms of the Pt concentration in the diffusion layer resulting from the interdiffusion between the Pt layer and the superalloy substrate during the pre-aluminizing diffusion treatment. Cyclic oxidation tests on these Pt-aluminide coatings reveal that the presence of Pt in aluminide coatings, in general, enhances oxidation resistance. However, in order to fully realize the beneficial effects of Pt on oxidation behaviour, a certain minimum Pt content in the coating was found to be necessary.

  • 124.
    Kumar, M.
    et al.
    CGC College of Engineering, Landran, India.
    Singh, H.
    Singh, N.
    Chavan, N.
    Kumar, S.
    Joshi, Shrikant
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Development of high-performance cols-sprayed nano-structured NI-20Cr coatings for hash environment of power plant boilers2017Conference paper (Other academic)
  • 125. Kumar, M.
    et al.
    Singh, H.
    Singh, N.
    Hong, S. M.
    Choi, I. S.
    Suh, J. Y.
    Chavan, N. M.
    Kumar, S.
    Joshi, S. V.
    Development of nano-crystalline cold sprayed Ni-20Cr coatings for high temperature oxidation resistance2015In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 266, p. 122-133Article in journal (Refereed)
    Abstract [en]

    In the current investigation a pre-synthesized nano-crystalline Ni-20Cr powder was deposited by cold-spray technique on SA 516 steel. The powder was synthesized by ball milling approach. The nano-crystallinity of the developed coating was established by crystallite size measurements from XRD profile, which was further endorsed by TEM analysis. High-temperature oxidation behavior of uncoated and coated samples was studied under cyclic isothermal conditions at 900 degrees C for 50 cycles in a laboratory tube furnace. The oxidation rates for the bare and coated steel were evaluated in terms of weight gain data. Different characterization techniques, such as X-ray diffraction (XRD), scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), and transmission electron microscopy (TEM) analyses were utilized to characterize the oxide scale. The hardness and oxidation resistance of the steel increased after the application of coating. The reduction in oxidation rate of the base steel was 94%. Moreover, the developed nanostructured coating was observed to reduce weight gain by 64% in comparison with micron-sized Ni-20Cr cold spray coating thus offers a higher oxidation resistance. This may be attributed to relatively denser structure, lower porosity and lower oxide content of the nanostructured coating. (C) 2015 Elsevier B.V. All rights reserved.

  • 126. Kumar, M.
    et al.
    Singh, H.
    Singh, N.
    Joshi, Shrikant. V.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Chavan, N.
    Kumar, S.
    Evaluation of high temperature oxidation behavior of a cold spray Ni-20Cr nano-structured coating2016Conference paper (Other academic)
  • 127.
    Kumar, Nitish
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Mahade, Satyapal
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Ganvir, Ashish
    University of Turku, Turku (FIN).
    Joshi, Shrikant
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Understanding the influence of microstructure on hot corrosion and erosion behavior of suspension plasma sprayed thermal barrier coatings2021In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 419, article id 127306Article in journal (Refereed)
    Abstract [en]

    Thermal barrier coatings (TBCs) are bilayer systems comprising a 7–8 wt% yttria partially stabilized zirconia (YSZ) top coat deposited over a metallic bond coat. Suspension plasma spraying (SPS) is an advanced and attractive top coat processing technique due to its capability to yield a variety of microstructures, including the desired columnar microstructure for enhanced strain tolerance and durability. This work attempts to investigate the desirable microstructural features in an SPS processed TBCs to mitigate hot corrosion and minimize erosion related losses that are often responsible for coating degradation. SPS processed TBCs were deposited utilizing three different spray conditions to obtain distinct microstructural features (column density, interpass [IP] porosity bands, column width), porosity content, and mechanical properties. Apart from comprehensive characterization utilizing SEM, XRD and micro-indentation tests, the as-deposited TBCs were subjected to hot-corrosion tests in the presence of vanadium pentoxide and sodium sulfate as corrosive salts. Post-corrosion analysis revealed complete infiltration of the molten salts in all the investigated TBCs. However, the delamination cracks generated due to the infiltrated corrosive species were minimal in case of TBCs with higher fracture toughness. The differences in microstructure and mechanical properties also led to differences in erosion performance, with TBCs possessing minimal total porosity content and high fracture toughness best resisting erosion related damage. Post-erosion analysis revealed that the TBCs with higher fracture toughness and micro-hardness showed superior erosion resistance. Based on the erosion and corrosion results and subsequent post-mortem of failed specimens, plausible damage mechanisms are proposed. Findings from this work provide new insights on developing damage tolerant TBCs microstructures with enhanced durability when exposed to erosion and hot corrosion environments.

    Download full text (pdf)
    fulltext
  • 128.
    Kumar, Rajiv
    et al.
    IITB-Monash Research Academy, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
    Joardar, Joydip
    International Advanced Research Centre for Powder Metallurgy and New Materials, Hyderabad, India.
    Raman, R.K. Singh
    Department of Mechanical and Aerospace Engineering, Monash University, VIC 3800 Australia.
    Raja, V.S.
    Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
    Joshi, Shrikant
    University West, Department of Engineering Science, Research Enviroment Production Technology West. International Advanced Research Centre for Powder Metallurgy and New Materials, Hyderabad, India.
    Parida, S.
    Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
    Effect of chromium and aluminum addition on anisotropic and microstructural characteristics of ball milled nanocrystalline iron2016In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 671, p. 164-169Article in journal (Refereed)
    Abstract [en]

    Prior studies on synthesis of nanocrystalline elements have discussed the effect of ball milling on lattice parameter, crystallite size, and micro-strain. For elemental milled powders, the anisotropic peak broadening does not change with increasing milling time. However, the effect of alloying addition on the anisotropic behavior of ball milled nanocrystalline powders remains an unexplored area. Here we report the effect of chromium and aluminum addition on the anisotropic behavior of iron in nanocrystalline Fe–20Cr–5Al (wt%) alloy powders synthesized by ball milling. The experimental results show that the anisotropic behavior of iron changes towards isotropic with milling. This change was also correlated to the theoretically calculated anisotropic factor from the change in elastic constant of iron due to milling. Addition of alloying elements exhibited a monotonic rise in the lattice parameter with crystallite size, which was attributed to the excess grain boundary interfacial energy and excess free volume at grain boundaries. Transmission electron microscopy image confirmed the crystallite size and nature of dislocation obtained using modified Williamson-Hall method.

  • 129.
    Kumar, Raju
    et al.
    Centre for Nanomaterials, International Advanced Research Centre for Powder Metallurgy and New Materials, Hyderabad 500005, India.
    Govinadarajan, Sivakumar
    Centre for Engineered Coatings, International Advanced Research Centre for Powder Metallurgy and New Materials, Hyderabad 500005, India.
    Janardhana, Reddy Kunda Siri Kiran
    Centre for Nanomaterials, International Advanced Research Centre for Powder Metallurgy and New Materials, Hyderabad 500005, India.
    Rao, Tata Narasinga
    Centre for Nanomaterials, International Advanced Research Centre for Powder Metallurgy and New Materials, Hyderabad 500005, India.
    Joshi, Shrikant
    University West, Department of Engineering Science, Research Enviroment Production Technology West. Centre for Engineered Coatings, International Advanced Research Centre for Powder Metallurgy and New Materials, Hyderabad 500005, India.
    Anandan, Srinivasan
    Centre for Nanomaterials, International Advanced Research Centre for Powder Metallurgy and New Materials, Hyderabad 500005, India.
    Facile One-Step Route for the Development of in Situ Cocatalyst-Modified Ti3+ Self-Doped TiO2 for Improved Visible-Light Photocatalytic Activity2016In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 41, p. 27642-27653Article in journal (Refereed)
    Abstract [en]

    Development of visible-light-driven photocatalysts by employing a relatively simple, efficient, and cost-effective one-step process is essential for commercial applications. Herein, we report for the first time the synthesis of in situ Cu-ion modified Ti3+ self-doped rutile TiO2 by such a facile one-step solution precursor plasma spray (SPPS) process using a water-soluble titanium precursor. In the SPPS process, Ti3+ self-doping on Ti4+ of rutile TiO2 is found to take place because of electron transfer from the created oxygen vacancies to Ti4+-ions. In situ Cu modification of the above Ti3+ self-doped rutile TiO2 by additionally introducing a Cu solution into plasma plume is also demonstrated. While the Ti3+ self-doping induces broad absorption in the visible-light region, the addition of Cu ion leads to even broader absorption in the visible region owing to resulting synergistic properties. The above materials were evaluated for various self-cleaning photocatalytic applications under visible-light illumination. Cu-ion modified Ti3+ self-doped rutile TiO2 is noted to exhibit a remarkably enhanced visible-light activity in comparison with Ti3+ self-doped rutile TiO2, with the latter itself outperforming commercial TiO2photocatalysts, thereby suggesting the suitability of the material for indoor applications. The broad visible-light absorption by Ti3+ self-doping, the holes with strong oxidation power generated in the valence band, and electrons in Ti3+ isolated states that are effectively separated into the high reductive sites of Cu ions upon visible-light irradiation, accounts for improved photocatalytic activity. Moreover, the synthesis process (SPPS) provides a valuable alternative to orthodox multistep processes for the preparation of such visible-light-driven photocatalysts.

  • 130.
    Kumar, S.
    et al.
    International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Balapur.Po, Hyderabad 500 005, India.
    Jyothirmayi, A.
    International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Balapur.Po, Hyderabad 500 005, India.
    Wasekar, Nitin
    International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Balapur.Po, Hyderabad 500 005, India.
    Joshi, Shrikant
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Influence of annealing on mechanical and electrochemical properties of cold sprayed niobium coatings2016In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 296, p. 124-135Article in journal (Refereed)
    Abstract [en]

    Abstract In the present study, thick and dense niobium coatings were obtained using cold spray technique by using air as a process gas. Inter-splat boundaries are completely removed in the coatings heat treated at 1500 °C by the formation of equiaxed grains. Heat treatment reduces the porosity level to 0.1%. Inter-splat boundary bonding state of the heat treated coatings was investigated using micro-tensile testing, scratch testing and nanoindentation and compared with the bulk niobium. The elastic modulus of the cold spray coatings heat treated at 1500 °C exhibits as high as 103 GPa whereas the same for bulk is 105 GPa. The increase in mechanical strength of inter-splat boundary from as-sprayed condition to 1500 °C was estimated to be 750%. Similarly corrosion performance of heat treated coatings was also evaluated in 1 M KOH solution through potentiodynamic polarization as well as impedance spectroscopy studies. The corrosion rate for the coatings heat treated at 1500 °C was estimated to be 0.443 MPY which is comparable for the bulk (0.498 MPY). Coatings annealed at 1250 °C and above, which is very close to the recrystallization temperature of niobium, were found to perform almost as bulk niobium indicating exciting implications for various applications. Assessment of structure–property correlations was done based on the microstructure, porosity and inter-splat bonding state, together with the mechanical and corrosion properties of the heat treated tantalum cold sprayed coatings.

  • 131.
    Kumar, S.
    et al.
    International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Hyderabad, India.
    Ramakrishna, M.
    International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Balapur Po, Hyderabad, 500 005, India.
    Chavan, N.M.
    International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Balapur Po, Hyderabad, 500 005, India.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Balapur Po, Hyderabad, 500 005, India.
    Correlation of splat state with deposition characteristics of cold sprayed niobium coatings2017In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 130, p. 177-195Article in journal (Refereed)
    Abstract [en]

    The cold spray technique has a great potential to deposit refractory metals for a variety of potential applications. Cold spraying of different metals have been addressed comprehensively to understand the deposition characteristics of the coatings. Since there is no available data on the deposition characteristics of cold sprayed Niobium, impact behavior of splats at different deposition conditions were simulated and numerically analyzed using Finite Element Modeling (FEM) and correlated with the experimental observations that highlight the role of the velocity and temperature of the particle upon impact on the bonding features. The increase in temperature of the splat drastically reduces the flow stress at the interface leading to best inter-splat bonding state. The synergistic effect of the temperature and the velocity leads to the formation of very dense, defect free niobium coating associated with deformation localization including interface melting. Formation of nanocrystalline grains at the inter-splat boundary was confirmed through TEM and compared with the FEM findings. Finally, understanding the deformation and deposition behavior of refractory metal such as niobium will be helpful to engineer the coatings for potential applications.

  • 132.
    Kumar, S.
    et al.
    International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Hyderabad, India.
    Reddy, S.K.
    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.
    Microstructure and performance of cold sprayed Al-SiC composite coatings with high fraction of particulates2017In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 318, p. 62-71Article in journal (Refereed)
    Abstract [en]

    Deposition of metal matrix composites (MMCs) through thermal spraying has traditionally presented problems associated with heterogeneity, porosity, and low wettability of particulates with matrix. Cold spray is a very rapid deposition process which is suitable for depositing a variety of ductile materials without any thermal degradation. Many researchers have attempted to deposit Al-SiC MMCs with 10–20% SiC using this technique. In the present study, three different powder compositions (FAl-23SiC, FAl-46SiC, FAl-71SiC) obtained by mixing Al and SiC powders were cold sprayed on aluminum substrates. The volume percentage and the average size of the SiC particulates in the cold sprayed coatings were estimated and found to be 23%, 47% and 52% for FAl-23SiC, FAl-46SiC and FAl-71SiC feedstocks, respectively. Effects of percentage and size of the SiC particulate retained in the composite coatings on the mechanical properties and the sliding wear performance were studied at different sliding conditions in the as-sprayed and heat treated conditions. The results were comprehensively analyzed and found to correlate well with the microstructure of the coatings.

  • 133.
    Kumar, S.
    et al.
    International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Hyderabad, India.
    Vidyasagar, V.
    International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Hyderabad,India.
    Jyothirmayi, A.
    International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Hyderabad, India.
    Joshi, Shrikant
    University West, Department of Engineering Science, Research Enviroment Production Technology West. International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Hyderabad, India.
    Effect of Heat Treatment on Mechanical Properties and Corrosion Performance of Cold-Sprayed Tantalum Coatings2016In: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 25, no 4, p. 745-756Article in journal (Refereed)
    Abstract [en]

    The cold-spray technique is of significant interest to deposit refractory metals with relatively high melting point for a variety of demanding applications. In the present study, mechanical properties of cold-sprayed tantalum coatings heat treated at different temperatures were investigated using microtensile testing, scratch testing, and nanoindentation. The corrosion performance of heat-treated coatings was also evaluated in 1 M KOH solution, and potentiodynamic polarization as well as impedance spectroscopy studies were carried out. Assessment of structure–property correlations was attempted based on microstructure, porosity, and intersplat bonding state, together with mechanical and corrosion properties of the heat-treated cold-sprayed tantalum coatings. Coatings annealed at 1500 °C, which is very close to the recrystallization temperature of tantalum, were found to perform almost as bulk tantalum, with exciting implications for various applications.

  • 134.
    Kumara, Chamara
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Segerstark, Andreas
    GKN Aerospace Engine Systems AB, Trollhättan, SE-461 81, Sweden.
    Hanning, Fabian
    Chalmers University of Technology, Department of Industrial and Materials Science, 412 96 Gothenburg, Sweden.
    Dixit, Nikhil
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Moverare, Johan
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. Division of Engineering Materials, Department of Management and Engineering, Linköping University, SE-58183 Linköping, Sweden.
    Nylén, Per
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Microstructure modelling of laser metal powder directed energy deposition of alloy 7182019In: Additive Manufacturing, ISSN 2214-8604, E-ISSN 2214-7810, Vol. 25, p. 357-364Article in journal (Refereed)
    Abstract [en]

    A multi-component and multi-phase-field modelling approach, combined with transformation kinetics modelling, was used to model microstructure evolution during laser metal powder directed energy deposition of Alloy 718 and subsequent heat treatments. Experimental temperature measurements were utilised to predict microstructural evolution during successive addition of layers. Segregation of alloying elements as well as formation of Laves and δ phase was specifically modelled. The predicted elemental concentrations were then used in transformation kinetics to estimate changes in Continuous Cooling Transformation (CCT) and Time Temperature Transformation (TTT) diagrams for Alloy 718. Modelling results showed good agreement with experimentally observed phase evolution within the microstructure. The results indicate that the approach can be a valuable tool, both for improving process understanding and for process development including subsequent heat treatment.

  • 135. Lohia, A.
    et al.
    Sivakumar, G.
    Ramakrishna, M.
    Joshi, S. V.
    Deposition of Nanocomposite Coatings Employing a Hybrid APS + SPPS Technique2014In: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 23, no 7, p. 1054-1064Article in journal (Refereed)
    Abstract [en]

    A novel approach hybridizing the conventional atmospheric plasma spraying and the solution precursor plasma spraying techniques has been explored to develop nanocomposite coatings. The above hybrid processing route involves simultaneous feeding of an appropriate solution precursor and commercially available spray-grade powder feedstock to realize microstructures comprising nanostructured and micron-sized features, which are unique in thermal spraying. The attractive prospects offered by this hybrid technique for deposition of nanocomposite coatings are specifically highlighted in this paper through a case study. Plasma sprayed Mo-alloy coatings are known for their good tribological characteristics and widely used in many applications. Further augmentation in performance of these coatings is expected through incorporation of distributed nanostructured oxide phases in the microstructure. Successful development of such coatings using a spray-grade Mo-alloy powder and a suitable oxide-forming solution precursor has been demonstrated. Splat formation under varied processing conditions has been comprehensively investigated and related to microstructure and tribological behavior of the coatings to assess the efficacy of the above nanocomposite coatings for wear resistant applications. © 2014, ASM International.

  • 136.
    Löbel, Martin
    et al.
    Materials and Surface Engineering Group, Institute of Materials Science and Engineering, Chemnitz University of Technology, Chemnitz, (DEU).
    Lindner, Thomas
    Materials and Surface Engineering Group, Institute of Materials Science and Engineering, Chemnitz University of Technology, 09107, Chemnitz, (DEU).
    Mehner, Thomas
    Materials and Surface Engineering Group, Institute of Materials Science and Engineering, Chemnitz University of Technology, 09107, Chemnitz, (DEU).
    Rymer, Lisa-Marie
    Materials and Surface Engineering Group, Institute of Materials Science and Engineering, Chemnitz University of Technology, 09107, Chemnitz, (DEU).
    Björklund, Stefan
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Lampke, Thomas
    Materials and Surface Engineering Group, Institute of Materials Science and Engineering, Chemnitz University of Technology, 09107, Chemnitz, (DEU).
    Microstructure and Corrosion Properties of AlCrFeCoNi High-Entropy Alloy Coatings Prepared by HVAF and HVOF2022In: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, no 1-2, p. 247-255Article in journal (Refereed)
    Abstract [en]

    High-entropy alloys (HEAs) represent an innovative development approach for new alloy systems. These materials have been found to yield promising properties, such as high strength in combination with sufficient ductility as well as high wear and corrosion resistance. Especially for alloys with a body-centered cubic (bcc) structure, advantageous surface properties have been revealed. However, typical HEA systems contain high contents of expensive or scarce elements. Consequently, applying them as coatings where their use is limited to the surface represents an exciting pathway enabling economical exploitation of their superior properties. Nevertheless, processing conditions strongly influence the resulting microstructure and phase formation, which in turn has a considerable effect on the functional properties of HEAs. In the presented study, microstructural differences between high-velocity oxygen fuel (HVOF) and high-velocity air fuel (HVAF) sprayed coatings of the alloy AlCrFeCoNi are investigated. A metastable bcc structure is formed in both coating processes. Precipitation reactions are suppressed by the rapid solidification during atomization and by the relatively low thermal input during spraying. The coating resistance to corrosive media was investigated in detail, and an improved passivation behavior was observed in the HVAF coatings. 

    Download full text (pdf)
    fulltext
  • 137.
    Mahade, Satyapal
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Aranke, Omkar
    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.
    Dizdar, Senad
    Höganäs AB, Höganäs, (SWE).
    Awe, Samuel
    Automotive Components Floby AB, Floby (SWE).
    Musalek, Radek
    Institute of Plasma Physics CAS, Prague (CZE).
    Lukac, Frantisek
    Institute of Plasma Physics, Academy of Sciences of the Czech Republic, Prague (CZE).
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Influence of processing conditions on the microstructure and sliding wear of a promising Fe-based coating deposited by HVAF2021In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 409, p. 1-17, article id 126953Article in journal (Refereed)
    Abstract [en]

    Thermal spray is a versatile and cost-effective process to deposit wear and corrosion resistant coatings. In this work, a relatively new ‘Fe-based’ chemistry comprising boride and carbides, is explored as a ‘greener’ alternative to the relatively expensive and carcinogenic Co-based coatings to mitigate wear. The emergent thermal spray process of high-velocity air-fuel (HVAF) spraying was chosen to deposit the Fe-based coatings, with the high-velocity oxy-fuel (HVOF) also being employed solely for the purpose of preliminary comparison. Detailed characterization of the HVOF and HVAF sprayed Fe-based coatings was carried out. Microstructure, porosity, hardness and phase analysis results demonstrate the influence of processing conditions, where specific spray conditions yielded minimal undeformed particulates content, high hardness, low porosity and feedstock phase retention. Differences in microstructural features of the as-deposited coatings in relation to their processing conditions are discussed in detail. The coatings were subjected to ball-on-disc tribometry tests at different load conditions and their friction and wear performance were evaluated. The coefficient of friction results of investigated coatings concurred with their respective microstructural features. Post-mortem of the worn coating surface, the mating alumina ball surface and wear debris was performed using SEM/EDS analysis to understand the associated wear mechanisms and material transfer. This work provides new insights on identifying appropriate HVAF processing conditions to achieve acceptable microstructural features and phases in Fe-based coatings for improved wear performance.

    Download full text (pdf)
    fulltext
  • 138.
    Mahade, Satyapal
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. GKN Aerospace Sweden AB, Trollhattan, 46153, (SWE).
    Awe, Samuel A.
    Automotive Components Floby AB, Floby (SWE).
    Björklund, Stefan
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Lukáč, František
    Institute of Plasma Physics CAS, Prague, (CZE).
    Mušálek, Radek
    Institute of Plasma Physics CAS, Prague, (CZE).
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Sliding wear behavior of a sustainable Fe-based coating and its damage mechanisms2022In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 500-501, article id 204375Article in journal (Refereed)
    Abstract [en]

    The current industry demand is to identify suitable alternatives to the risk-of-supply prone and/or toxic, WC-Co and electrolytic hard chrome coatings without comprising the desired wear performance. Therefore, compositions based on abundantly available elements (e.g. ‘Fe’) that possess adequate wear resistance are desirable from health, sustainability and economic standpoints. In this work, crystalline Fe-based (Rockit-401) coatings were processed using two different thermal spray routes, i.e. HVOF and HVAF spraying. The influence of deposition route and processing conditions on the microstructure, porosity content, hardness and phase composition was examined. The as-deposited coatings were subjected to mild (5 N) and harsh (15 N) dry sliding wear test conditions by employing alumina ball as the counter surface material, and their wear performance was examined. Mild sliding wear test conditions (5 N) resulted in anomalous wear behavior, where the abrupt drop in CoF at several instances during the test was observed in all the investigated coatings. On the other hand, under harsh wear test conditions (15 N), such an abrupt dip in CoF was not observed. Detailed wear mechanisms of the coatings were revealed under different test conditions (5 N and 15 N). This work sheds light on processing, wear behavior and wear mechanisms of a sustainable and high-performance coating that fulfills non-toxic and sustainability goals in tandem for tribological applications. © 2022 The Authors

    Download full text (pdf)
    fulltext
  • 139.
    Mahade, Satyapal
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Baiamonte, Lidia
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. Department of Chemical Engineering Materials Environment, Sapienza University of Rome, (ITA).
    Sadeghi, Esmaeil
    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.
    Marra, Francesco
    Department of Chemical Engineering Materials Environment, Sapienza University of Rome, (ITA).
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Novel utilization of powder-suspension hybrid feedstock in HVAF spraying to deposit improved wear and corrosion resistant coatings2021In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 412, article id 127015Article in journal (Refereed)
    Abstract [en]

    Deployment of a suspension feedstock has been known to alleviate problems associated with using sub-micron and nanosized powder feedstock for thermal spraying of monolithic as well as powder-suspension ‘hybrid’ composite coatings. However, a powder-suspension hybrid feedstock has never been previously used in high-velocity air-fuel (HVAF) spraying. In this work, for the very first time, a chromium carbide (Cr3C2) suspension has been co-sprayed along with an Inconel-625 (IN-625) powder by the HVAF process as an illustrative case study. Two variants of the IN-625 + Cr3C2 hybrid coatings were produced by varying relative powder-suspension feed rates. For comparison, pure IN-625 coating was also deposited utilizing identical spray parameters. Detailed microstructural characterization, porosity content, hardness measurement and phase analysis of the as-deposited coatings was performed. The suspension-derived carbides were retained in the bulk of the coating, resulting in higher hardness. In the dry sliding wear test, the hybrid coatings demonstrated lower wear rate and higher coefficient of friction (CoF) compared to the conventional, powder-derived IN-625 coatings. Furthermore, the wear rate improved slightly with an increase in Cr3C2 content in the hybrid coating. Post-wear analysis of the worn coating, worn alumina ball and the wear debris was performed to understand the wear mechanisms and material transfer in the investigated coatings. In the potentiodynamic polarization test, higher corrosion resistance for hybrid coatings than conventional IN-625 coatings was achieved, indicating that the incorporation of a secondary, carbide phase in the IN-625 matrix did not compromise its corrosion performance. This work demonstrates a novel approach to incorporate any finely distributed second phase in HVAF sprayed coatings to enhance their performance when exposed to harsh environments.

    Download full text (pdf)
    fulltext
  • 140.
    Mahade, Satyapal
    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.
    Govindarajan, Sivakumar
    International Advanced Research Center for Powder Metallurgy and New Materials, Hyderabad, India (IND).
    Olsson, Mikael
    Dalarna University, Sweden.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Novel wear resistant carbide-laden coatings deposited by powder-suspension hybrid plasma spray: Characterization and testing2020In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 399, article id 126147Article in journal (Refereed)
    Abstract [en]

    Thermal spraying with a hybrid powder-suspension feedstock presents a novel approach to conveniently realize coatings with unusual chemistries and unique microstructures. In this study, coatings were deposited by simultaneous spraying of T-400 (Tribaloy-400) powder and Cr3C2 suspension with varying relative feed rates. For comparison, pure T-400 coating was also deposited using powder feedstock via atmospheric plasma spray (APS) route to assess the role of incorporating a hard, finely distributed carbide phase in the coating. SEM (Scanning electron microscopy)/EDS (Energy-dispersive X-ray spectroscopy) investigation of the hybrid coatings revealed a lamellar microstructure with distributed fine carbides. XRD (X-ray diffraction) analysis of the feedstock and hybrid coatings showed the presence of original feedstock constituents, along with some oxides of chromium, in the deposited coating. Hardness measurements on the as-sprayed coatings indicated higher hardness in hybrid coatings than in the pure T-400 coating. The deposited coatings were subjected to scratch testing on polished surfaces as well as on polished cross sections. The scratching response of the coatings was examined by SEM analysis. Results demonstrated that the hybrid coatings possess excellent scratch resistance, superior compared to the pure T-400 coating, which is promising for extending the durability of engineering components operating under severe wear conditions. This was confirmed by abrasion test results which established the superior wear resistance of hybrid coatings. The above hybrid approach is easily extendable to other material systems and can have important implications in the realization of next-generation wear resistant coatings. © 2020 Elsevier B.V.

  • 141.
    Mahade, Satyapal
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Curry, Nicholas
    Treibacher Industrie AG, Auer von Welsbachstr, 1, A-9330 Althofen, Austria.
    Björklund, Stefan
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Markocsan, Nicolaie
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Durability of Gadolinium Zirconate/YSZ Double-Layered Thermal Barrier Coatings under Different Thermal Cyclic Test Conditions2019In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, no 14, article id E2238Article in journal (Refereed)
    Abstract [en]

    Higher durability in thermal barrier coatings (TBCs) is constantly sought to enhance the service life of gas turbine engine components such as blades and vanes. In this study, three double layered gadolinium zirconate (GZ)-on-yttria stabilized zirconia (YSZ) TBC variants with varying individual layer thickness but identical total thickness produced by suspension plasma spray (SPS) process were evaluated. The objective was to investigate the role of YSZ layer thickness on the durability of GZ/YSZ double-layered TBCs under different thermal cyclic test conditions i.e., thermal cyclic fatigue (TCF) at 1100 °C and a burner rig test (BRT) at a surface temperature of 1400 °C, respectively. Microstructural characterization was performed using SEM (Scanning Electron Microscopy) and porosity content was measured using image analysis technique. Results reveal that the durability of double-layered TBCs decreased with YSZ thickness under both TCF and BRT test conditions. The TBCs were analyzed by SEM to investigate microstructural evolution as well as failure modes during TCF and BRT test conditions. It was observed that the failure modes varied with test conditions, with all the three double-layered TBC variants showing failure in the TGO (thermally grown oxide) during the TCF test and in the ceramic GZ top coat close to the GZ/YSZ interface during BRT. Furthermore, porosity analysis of the as-sprayed and TCF failed TBCs revealed differences in sintering behavior for GZ and YSZ. The findings from this work provide new insights into the mechanisms responsible for failure of SPS processed double-layered TBCs under different thermal cyclic test conditions.

    Download full text (pdf)
    fulltext
  • 142.
    Mahade, Satyapal
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Mulone, Antonio
    Department of Industrial and Materials Science, Chalmers University of Technology, Gothenburg (SWE).
    Björklund, Stefan
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Klement, U.
    Department of Industrial and Materials Science, Chalmers University of Technology, Gothenburg (SWE).
    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.
    Investigating load-dependent wear behavior and degradation mechanisms in Cr3C2-NiCr coatings deposited by HVAF and HVOF2021In: Journal of Materials Research and Technology, ISSN 2238-7854, Vol. 15, p. 4595-4609Article in journal (Refereed)
    Abstract [en]

    Wear resistant coatings that comply with non-toxic environment goals are highly desirable. Cr3C2–NiCr is a promising alternative to the toxic, ‘Co’- containing WC–Co coatings to mitigate wear. The purpose of this study was to examine the suitability of Cr3C2–NiCr coatings for automotive brake disc application by systematically investigating their dry sliding wear behavior at different test conditions. Therefore, High Velocity Air Fuel (HVAF) and High Velocity Oxy Fuel (HVOF) were employed to deposit Cr3C2–NiCr coatings. The powder feedstock and as-deposited Cr3C2–NiCr coatings were characterized for their microstructure and phase composition using SEM and XRD. Mechanical properties (hardness, fracture toughness), porosity and surface topography of the as-deposited coatings were evaluated. The coatings were subjected to sliding wear tests at different normal loads (5 N, 10 N and 15 N) using alumina ball as the counter surface. Coefficient of friction (CoF) evolution of HVAF and HVOF deposited coatings, along with their wear performance, was obtained for different normal load conditions. The wear performance ranking of HVAF and HVOF processed coatings was influenced by the test conditions, with HVAF coatings demonstrating better wear resistance than HVOF coatings at harsh test conditions and the HVOF coatings performing better under mild wear test conditions. Detailed post-wear analysis of worn coatings, the alumina ball counter-body and the resulting debris was performed to reveal the degradation mechanisms at different test conditions. Findings from this work provide new insights into the desirable microstructural features to mitigate wear, which can be further exploited to deposit wear-resistant coatings.

    Download full text (pdf)
    JMR& T
  • 143.
    Mahade, Satyapal
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Mulone, Antonio
    University of Chalmers, Göteborg.
    Björklund, Stefan
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Klement, Uta
    University of Chalmers, Göteborg.
    Joshi, Shrikant
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Novel suspension route to incorporate graphene nano-platelets in HVAF-sprayed Cr3C2–NiCr coatings for superior wear performance2021In: Journal of Materials Research and Technology, ISSN 2238-7854, Vol. 13, p. 498-512Article in journal (Refereed)
    Abstract [en]

    Graphene nano platelets (GNP) have several attractive properties, including excellent lubricity that can be used to develop wear-resistant coatings. Thermally sprayed chromium carbide–nickel chromium (Cr3C2–NiCr) coatings are widely employed to impart wear resistance to engineering components. This work attempts to improve the wear resistance of high velocity air fuel (HVAF) sprayed Cr3C2–NiCr coatings by incorporating GNP using a hybrid approach in which Cr3C2–NiCr (powder) and GNP (suspension) are co-axially injected. Two different powder-to-suspension delivery ratios were employed in this study that utilizes a liquid feedstock in tandem with a HVAF system. Furthermore, for comparison, a pure (without graphene) Cr3C2–NiCr reference coating was deposited by the HVAF process using identical spray parameters. The as-sprayed coatings were characterized for their microstructure and phase constitution by SEM/EDS and X-Ray Diffraction. Mechanical properties such as hardness and fracture toughness were evaluated using micro-indentation technique. The hybrid coatings were subjected to dry sliding wear tests and wear performance was compared with reference Cr3C2–NiCr. The GNP incorporated hybrid coatings exhibited lower CoF and lower wear rates than the reference Cr3C2–NiCr coating. Post wear SEM/EDS analysis revealed different wear mechanisms predominant in the investigated coatings. Utilizing the above as a case study, this work provides key insights into a new approach to produce GNP incorporated coatings for mitigating wear.

    Download full text (pdf)
    fulltext
  • 144.
    Mahade, Satyapal
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Mulone, Antonio
    Department of Industrial and Materials Science, Chalmers University of Technology, Gothenburg (SWE).
    Björklund, Stefan
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Klement, Uta
    Department of Industrial and Materials Science, Chalmers University of Technology, Gothenburg (SWE).
    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.
    Incorporation of graphene nano platelets in suspension plasma sprayed alumina coatings for improved tribological properties2021In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 570, article id 151227Article in journal (Refereed)
    Abstract [en]

    Graphene possesses high fracture toughness and excellent lubrication properties, which can be exploited to enhance tribological performance of coating systems utilized to combat wear. In this work, suspension plasma spray (SPS) process was employed to deposit a composite, graphene nano-platelets (GNP) incorporated alumina coating. For comparison, monolithic alumina was also deposited utilizing identical spray conditions. The as-deposited coatings were characterized in detail for their microstructure, porosity content, hardness, fracture toughness and phase composition. Raman analysis of the as-deposited composite coating confirmed retention of GNP. The composite coating also showed good microstructural integrity, comparable porosity, higher fracture toughness and similar alumina phase composition as the monolithic alumina coating. The as-deposited coatings were subjected to dry sliding wear tests. The GNP incorporated composite coating showed lower CoF and lower specific wear rate than the pure alumina coating. Additionally, the counter surface also showed a lower wear rate in case of the composite coating. Post-wear analysis performed by SEM/EDS showed differences in the coating wear track and in the ball wear track of monolithic and composite coatings. Furthermore, Raman analysis in the wear track of composite coating confirmed the presence of GNP. The micro-indentation and wear test results indicate that the presence of GNP in the composite coating aided in improving fracture toughness, lowering CoF and specific wear rate compared to the monolithic coating. Results from this work demonstrated retention of GNP in an SPS processed coating, which can be further exploited to design superior wear-resistant coatings. 

    Download full text (pdf)
    Applied Surface Science
  • 145.
    Mahade, Satyapal
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Narayan, Karthik
    University West, Department of Engineering Science.
    Govindarajan, Sivakumar
    International Advanced Research Center for Powder Metallurgy and New Materials, Hyderabad 500069, India.
    Björklund, Stefan
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Curry, Nicholas
    Treibacher Industrie AG, 9330 Althofen, Austria.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Exploiting Suspension Plasma Spraying to Deposit Wear-Resistant Carbide Coatings.2019In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, no 15, article id E2344Article in journal (Refereed)
    Abstract [en]

    Titanium- and chromium-based carbides are attractive coating materials to impart wear resistance. Suspension plasma spraying (SPS) is a relatively new thermal spray process which has shown a facile ability to use sub-micron and nano-sized feedstock to deposit high-performance coatings. The specific novelty of this work lies in the processing of fine-sized titanium and chromium carbides (TiC and Cr3C2) in the form of aqueous suspensions to fabricate wear-resistant coatings by SPS. The resulting coatings were characterized by surface morphology, microstructure, phase constitution, and micro-hardness. The abrasive, erosive, and sliding wear performance of the SPS-processed TiC and Cr3C2 coatings was also evaluated. The results amply demonstrate that SPS is a promising route to manufacture superior wear-resistant carbide-based coatings with minimal in situ oxidation during their processing.

    Download full text (pdf)
    fulltext
  • 146.
    Mahade, Satyapal
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Venkat, Abhilash
    SASTRA University, Thanjavur, Tamil Nadu (IND).
    Curry, Nicholas
    Thermal Spray Innovations, Salzburg, (AUT).
    Leitner, Matthias
    Thermal Spray Innovations, Althofen (AUT).
    Joshi, Shrikant
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Erosion Performance of Atmospheric Plasma Sprayed Thermal Barrier Coatings with Diverse Porosity Levels2021In: Coatings, ISSN 2079-6412, Vol. 11, no 1, p. 1-21Article in journal (Refereed)
    Abstract [en]

    Thermal barrier coatings (TBCs) prolong the durability of gas turbine engine componentsand enable them to operate at high temperature. Several degradation mechanisms limit the durability of TBCs during their service. Since the atmospheric plasma spray (APS) processed 7–8 wt.% yttria stabilized zirconia (YSZ) TBCs widely utilized for gas turbine applications are susceptible to erosion damage, this work aims to evaluate the influence of their porosity levels on erosion behavior. Eight different APS TBCs were produced from 3 different spray powders with porosity ranging from 14% to 24%. The as-deposited TBCs were examined by SEM analysis. A licensed software was used to quantify the different microstructural features. Mechanical properties of the as-deposited TBCs were evaluated using micro-indentation technique. The as-deposited TBCs were subjected to erosion tests at different angles of erodent impact and their erosion performance was evaluated. Based on the results, microstructure-mechanical property-erosion performance was correlated. Findings from this work provide new insights into the microstructural features desired for improved erosion performance of APS deposited YSZ TBCs.

    Download full text (pdf)
    fulltext
  • 147. Mandati, S.
    et al.
    Sarada, B. V.
    Dey, S. R.
    Joshi, S. V.
    CuIn1-xGaxSe2 thin-film absorber layers for solar photovoltaics fabricated by two-stage pulsed current electrodeposition2014In: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 118, p. 158-160Article in journal (Refereed)
    Abstract [en]

    Single phase polycrystalline Copper Indium Gallium Diselenide (CIGS) thin-films for solar photovoltaic applications were fabricated by an economical two-stage method of Pulsed Current (PC) electrodeposition. Cu, Ga and Se were first co-deposited onto a Mo foil followed by deposition of In. The as-deposited films were annealed in Argon atmosphere at 550 C for 30 min and were further characterized to study their morphology, phase constitution, and optical absorption. The results revealed that the films have a compact morphology and are comprised of a crystalline chalcopyrite single phase CIGS. The bandgap of the CIGS films was found to be 1.27 eV from absorption studies. The photoelectrochemical studies revealed the p-type nature of CIGS films with improved photocurrent over that obtained for one-stage PC electrodeposited CIGS thin-films. © 2013 Elsevier B.V.

  • 148. Mandati, S.
    et al.
    Sarada, B. V.
    Dey, S. R.
    Joshi, S. V.
    Enhanced photoresponse of Cu(In,Ga)Se2/CdS heterojunction fabricated using economical non-vacuum methods2015In: Electronic Materials Letters, ISSN 1738-8090, Vol. 11, no 4, p. 618-624Article in journal (Refereed)
    Abstract [en]

    The present study demonstrates the fabrication of a CIGS/CdS heterojunction with enhanced photoelectrochemical performance using low-cost non-vacuum methods. A simplified economical pulse electrodeposition technique, with a two-electrode system in an additive-free electrolyte, has been used for the preparation of chalcopyrite Cu(In,Ga)Se<inf>2</inf> (CIGS) thin-films avoiding the selenization process and CdS subsequently chemical bath deposited onto these CIGS films. Photoelectrochemical (PEC) performance of bare CIGS and the CIGS/CdS heterojunction has been investigated in conventional Na<inf>2</inf>SO<inf>4</inf> electrolyte under chopped solar simulated light. The PEC analysis reveals nearly twenty-fold increase in the photoresponse of the CIGS/CdS heterojunction compared to bare CIGS films. The CIGS/CdS junction has also been tested in a PEC cell using a novel sulphide/sulphite electrolyte for the first time and found to yield further enhancement in photocurrent density with exceptional stability. Thus, apart from fabrication of an efficient CIGS/CdS heterojunction economically, the present study proposes use of a novel electrolyte yielding superior performance and showing potential for commercialization of CIGS devices and their use in photoelectrochemical cells.[Figure not available: see fulltext.] © 2015, The Korean Institute of Metals and Materials and Springer Science+Business Media Dordrecht.

  • 149. Mandati, S.
    et al.
    Sarada, B. V.
    Dey, S. R.
    Joshi, S. V.
    Improved photoelectrochemical performance of Cu(In,Ga)Se2 thin films prepared by pulsed electrodeposition2013In: Journal of Renewable and Sustainable Energy, E-ISSN 1941-7012, Vol. 5, article id 031602Article in journal (Refereed)
    Abstract [en]

    Solar cells based on polycrystalline Cu(In,Ga)Se2 absorber layers have yielded the highest conversion efficiency among all the thin-film technologies. CIGS thin-films possess large optical absorption coefficient (≈105 cm-1) and a suitable bandgap of ≈ 1.20 eV for an ideal stoichiometry of CuIn0.7Ga0.3Se2. In the present study, Direct Current (DC) and Pulsed Current (PC) electrodeposition techniques are employed to obtain the near ideal stoichiometric CIGS thin-films on a Mo foil using a two electrode system at a constant potential. Deposited films are annealed at 550 °C under Ar atmosphere. Characterization of the annealed CIGS films is performed using SEM-energy dispersive X-ray spectroscopy, X-ray diffraction, Raman spectroscopy, and photoelectrochemistry to study the morphology, stoichiometry, phase constitution, and the photoelectrochemical response. PC deposition offered suitable manipulation of various parameters, which has helped in obtaining a better quality stoichiometric single phase chalcopyrite structured CIGS thin films with the elimination of unwanted secondary phases like Cu2-xSe. An improved photoelectrochemical performance, characteristic of a p-type semiconductor, is observed for the PC deposited CIGS films. © 2013 AIP Publishing LLC.

  • 150. Mandati, S.
    et al.
    Sarada, B. V.
    Dey, S. R.
    Joshi, S. V.
    Pulsed electrodeposition of Cuinse2 thin films with morphology for solar cell applications2013In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 160, no 4, p. D173-D177Article in journal (Refereed)
    Abstract [en]

    Copper indium diselenide (CuInSe2) films have been prepared by pulse electrodeposition technique on Molybdenum substrate followed by post-deposition annealing at 550°C. Optimization of pulse parameters by varying the pulse duration (duty cycle) in order to achieve high quality films has been reported. Appropriate manipulation of pulse parameters has resulted in a novel flake-like crystallite morphology and better control over the composition of individual elements. The CIS thin films were comprehensively characterized using SEM-EDS, FIB, XRD and UV-DRS to study their morphology, phase constitution, etc. and PEC (photoelectrochemistry) measurements were also carried out to ascertain the photoelectrochemical performance of the CIS absorber layer. The bandgap of the CIS films was determined to be 1.02 eV. The flake like crystallite morphology observed in CIS thin films under the optimized processing conditions was found to yield enhanced cathodic photoresponse under solar simulated light with a photocurrent density of 20 μA/cm2 (observed at a potential of -0.6 V vs. SCE). The films exhibited a photoresponse typical of a p-type semiconductor. © 2013 The Electrochemical Society.

123456 101 - 150 of 259
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf