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Ganvir, A., Björklund, S., Yao, Y., Vadali, S. V., Klement, U. & Joshi, S. V. (2019). A facile approach to deposit graphenaceous composite coatings by suspension plasma spraying. Coatings, 9(3), Article ID 171.
Open this publication in new window or tab >>A facile approach to deposit graphenaceous composite coatings by suspension plasma spraying
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2019 (English)In: Coatings, ISSN 2079-6412, Vol. 9, no 3, article id 171Article in journal (Refereed) Published
Abstract [en]

This paper demonstrates, for the first time ever, the deposition of graphenaceous composite coatings using an easy, yet robust, suspension plasma spraying (SPS) process. As a case study, a composite coating comprising 8 wt.% of yttria-stabilized-zirconia (8YSZ) and reinforced with graphene oxide (GO) was deposited on a steel substrate. The coatings were sprayed using an 8YSZ-GO mixed suspension with varied plasma spray parameters. Establishing the possibility of retaining the graphene in a ceramic matrix using SPS was of specific interest. Electron microscopy and Raman spectroscopy confirmed the presence of graphenaceous material distributed throughout the coating in the 8YSZ matrix. The experimental results discussed in this work confirm that SPS is an immensely attractive pathway to incorporate a graphenaceous material into virtually any matrix material and can potentially have major implications in enabling the deposition of large-area graphene-containing coatings for diverse functional applications. © 2019 by the authors.

Place, publisher, year, edition, pages
MDPI AG, 2019
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-13737 (URN)10.3390/coatings9030171 (DOI)000465608700002 ()2-s2.0-85062495390 (Scopus ID)
Available from: 2019-03-21 Created: 2019-03-21 Last updated: 2019-05-10
Sadeghi, E. & Joshi, S. V. (2019). Chlorine-induced high-temperature corrosion and erosion-corrosion of HVAF and HVOF-sprayed amorphous Fe-based coatings. Surface & Coatings Technology, 1, 20-35
Open this publication in new window or tab >>Chlorine-induced high-temperature corrosion and erosion-corrosion of HVAF and HVOF-sprayed amorphous Fe-based coatings
2019 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 1, p. 20-35Article in journal (Refereed) Epub ahead of print
Abstract [en]

Chlorine-induced high-temperature corrosion and erosion-corrosion behavior of amorphous Fe-based coatings sprayed by high velocity air-fuel (HVAF) and high velocity oxy-fuel (HVOF) techniques were investigated. The coated specimens were first exposed to isothermal high-temperature corrosion at 600 °C in ambient air with and without KCl. The exposed specimens were then subjected to alumina erodent. The as-sprayed HVAF coating showed a more compact and uniform microstructure with a higher hardness leading to higher corrosion and erosion-corrosion resistance. After erosion, all the coatings similarly exhibited a combined brittle/ductile damage to surface oxide scale that previously formed in the corrosive environment. The corrosion and erosion-corrosion behavior of the coatings primarily relied on the uniformity of coatings’ microstructure and distribution of alloying elements to form the protective oxide scale in the corrosive environment, which can resist against erodent in the erosive media. © 2019 Elsevier B.V.

Keywords
Air, Alloying elements, Alumina, Aluminum oxide, Chlorine, Corrosion resistance, Corrosive effects, Erosion, Fuels, High temperature corrosion, HVOF thermal spraying, Microstructure, Potassium compounds, Scale (deposits), Sprayed coatings, Thermal spraying, Amorphous coating, Chlorine-induced high-temperature corrosion, Erosion - corrosions, HVAF, HVOF, Corrosion resistant coatings
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-13514 (URN)10.1016/j.surfcoat.2019.01.080 (DOI)2-s2.0-85060532855 (Scopus ID)
Funder
Knowledge Foundation, RUN 20160201Region Västra Götaland, 2016-01489
Available from: 2019-03-21 Created: 2019-03-21 Last updated: 2019-07-25Bibliographically approved
Goel, S., Ahlfors, M., Bahbou, F. & Joshi, S. V. (2019). Effect of Different Post-treatments on the Microstructure of EBM-Built Alloy 718. Journal of materials engineering and performance (Print), 28(2), 673-680
Open this publication in new window or tab >>Effect of Different Post-treatments on the Microstructure of EBM-Built Alloy 718
2019 (English)In: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024, Vol. 28, no 2, p. 673-680Article in journal (Refereed) Published
Abstract [en]

Electron beam melting (EBM) of Alloy 718 is of rapidly growing interest as it allows cost-effective production of complex components. However, the inherent flaws in the component in as-built state are of concern in view of the severe working conditions in which Alloy 718 components typically operate. The present work entails an investigation of changes in microstructure that accompany some post-treatments that are being widely considered to address defects in EBM processed Alloy 718. The effect of two different post-treatments, namely hot isostatic pressing (HIP) and a combined HIP + heat treatment (HT) carried out inside the HIP vessel, have been studied and results from as-built and post-treated specimens were compared in terms of porosity/lack-of-fusion, microstructure, phase constitution (NbC content, ÎŽ-phase) and micro-hardness. Post-treatment resulted in reduction in defect content by more than an order of magnitude. HIPing led to complete dissolution of ÎŽ phase. In comparison to as-built material, HIPed specimens exhibited significant drop in hardness. However, a sharp ‘recovery’ of hardness to yield values higher than in as-built condition was observed after HIP + HT and can be attributed to precipitation of γ′′ phase. © 2018, The Author(s).

Keywords
3D printers, Cost effectiveness, Defects, Electron beam melting, Electron beams, Hardness, Heat treatment, Hot isostatic pressing, Microhardness, Microstructure, Alloy 718, Complete dissolution, Complex components, Cost-effective production, Defect contents, Phase constitution, Post treatment, Yield value, Niobium compounds
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-13133 (URN)10.1007/s11665-018-3712-0 (DOI)000458782100012 ()2-s2.0-85055983075 (Scopus ID)
Funder
Knowledge Foundation, 20160281
Note

First Online: 29 October 2018

Available from: 2018-11-19 Created: 2018-11-19 Last updated: 2019-06-12Bibliographically approved
Zhang, P., Sadeghi, E., Chen, S., Li, X.-H., Markocsan, N., Joshi, S. V., . . . Peng, R. L. n. (2019). Effects of surface finish on the initial oxidation of HVAF-sprayed NiCoCrAlY coatings. Surface & Coatings Technology, 364, 43-56
Open this publication in new window or tab >>Effects of surface finish on the initial oxidation of HVAF-sprayed NiCoCrAlY coatings
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2019 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 364, p. 43-56Article in journal (Refereed) Published
Abstract [en]

Oxide scale formed on HVAF-sprayed NiCoCrAlY coatings and the effect of surface treatment were investigated by a multi-approach study combining photo-stimulated luminescence, microstructural observation and mass gain. The initial oxidationbehaviour of as-sprayed, polished and shot-peened coatings at 1000 °C is studied. Both polished and shot-peened coatings exhibited superior performance due to rapid formation of α-Al2O3 fully covering the coating and suppressing the growth of transient alumina, assisted by a high density of α-Al2O3 nuclei on surface treatment induced defects. Moreover, the fast development of a two-layer alumina scale consisting of an inward-grown inner α-Al2O3 layer and an outer layer transformed from outward-grown transient alumina resulted in a higher oxide growth rate of the as-sprayed coating.

Keywords
Oxidation, Transient to alpha transformation, Surface treatment, Polishing, Shot-peening, Photo-stimulated luminescence spectroscopy
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-13736 (URN)10.1016/j.surfcoat.2019.02.068 (DOI)000463302800006 ()2-s2.0-85062231529 (Scopus ID)
Funder
Swedish Energy Agency, KME-703
Available from: 2019-03-21 Created: 2019-03-21 Last updated: 2019-07-01Bibliographically approved
Ganvir, A., Calinas, R. F., Markocsan, N., Curry, N. & Joshi, S. V. (2019). Experimental visualization of microstructure evolution during suspension plasma spraying of thermal barrier coatings. Journal of the European Ceramic Society, 39(2-3), 470-481
Open this publication in new window or tab >>Experimental visualization of microstructure evolution during suspension plasma spraying of thermal barrier coatings
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2019 (English)In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 39, no 2-3, p. 470-481Article in journal (Refereed) Published
Abstract [en]

This paper investigates the evolution of microstructure of thermal barrier coatings (TBCs) produced by suspension plasma spraying (SPS) through a careful experimental study. Understanding the influence of different suspension characteristics such as type of solvent, solid load content and median particle size on the ensuing TBC microstructure, as well as visualizing the early stages of coating build-up leading to formation of a columnar microstructure or otherwise, was of specific interest. Several SPS TBCs with different suspensions were deposited under identical conditions (same substrate, bond coat and plasma spray parameters). The experimental study clearly revealed the important role of suspension characteristics, namely surface tension, density and viscosity, on the final microstructure, with study of its progressive evolution providing invaluable insights. Variations in suspension properties manifest in the form of differences in droplet momentum and trajectory, which are found to be key determinants governing the resulting microstructure (e.g., lamellar/vertically cracked or columnar).

Keywords
Suspension plasma spraying, Thermal barrier coatings, Droplet momentum, Columnar microstructure, Microstructure evolution
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-12948 (URN)10.1016/j.jeurceramsoc.2018.09.023 (DOI)000450379400042 ()2-s2.0-85053889817 (Scopus ID)
Funder
Region Västra Götaland, RUN 612-0974-13
Available from: 2018-10-26 Created: 2018-10-26 Last updated: 2018-12-20Bibliographically approved
Eklund, J., Phother, J., Sadeghi, E., Joshi, S. V. & Liske, J. (2019). High-Temperature Corrosion of HVAF-Sprayed Ni-Based Coatings for Boiler Applications. Oxidation of Metals, 91(5-6), 729-747
Open this publication in new window or tab >>High-Temperature Corrosion of HVAF-Sprayed Ni-Based Coatings for Boiler Applications
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2019 (English)In: Oxidation of Metals, ISSN 0030-770X, E-ISSN 1573-4889, Vol. 91, no 5-6, p. 729-747Article in journal (Refereed) Published
Abstract [en]

The present study investigates the initial corrosion behaviour of HVAF-sprayed NiCr, NiAl and NiCrAlY coatings in two different environments, O 2 + H 2 O and O 2 + H 2 O + KCl at 600 °C for up to 168 h in order to evaluate the possibility of utilizing such coatings in biomass- and waste-fired boilers. SEM/EDX analysis showed that all coatings displayed a protective behaviour in O 2 + H 2 O. Upon addition of KCl (O 2 + H 2 O + KCl), the corrosion behaviour of the NiCr coating drastically changed as it formed a thick oxide layer and displayed major chlorine diffusion down to the substrate. The NiCrAlY coating displayed a significantly better corrosion resistance with only minor oxide formation. The NiAl coating exhibited a protective behaviour similar to when exposed in the absence of KCl indicating that a thin protective oxide has formed on the coating surface. The performance of the NiAl and NiCrAlY coatings is promising for future studies with long-term exposures in more corrosive environments such as in a biomass- and waste-fired boiler. © 2019, The Author(s).

Keywords
Aluminum alloys; Aluminum corrosion; Binary alloys; Biomass; Boiler corrosion; Boilers; Chlorine compounds; Chromium alloys; Corrosion resistance; Corrosion resistant coatings; Corrosive effects; Diffusion coatings; High temperature applications; High temperature corrosion; Sprayed coatings; Wastes, Corrosion behaviour; Corrosive environment; HVAF; Long term exposure; Ni-based coatings; NiCrAlY coating; Protective oxides; Waste-fired boilers, Potassium compounds
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-13758 (URN)10.1007/s11085-019-09906-0 (DOI)000467574600011 ()2-s2.0-85062942037 (Scopus ID)
Funder
Knowledge Foundation, RUN 2016-0201Region Västra Götaland, RUN 2016-01489
Available from: 2019-05-17 Created: 2019-05-17 Last updated: 2019-06-05
Tesar, T., Musalek, R., Lukac, F., Medricky, J., Cizek, J., Rimal, V., . . . Chraska, T. (2019). Increasing α-phase content of alumina-chromia coatings deposited by suspension plasma spraying using hybrid and intermixed concepts. Surface & Coatings Technology, 71, 298-311
Open this publication in new window or tab >>Increasing α-phase content of alumina-chromia coatings deposited by suspension plasma spraying using hybrid and intermixed concepts
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2019 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 71, p. 298-311Article in journal (Refereed) Epub ahead of print
Abstract [en]

The novel method of hybrid suspension plasma spraying of dry coarse aluminum oxide powder with chromium oxide suspension using hybrid water/argon-stabilized (WSP-H 500) plasma torch was utilized for the deposition of coatings with very high α-phase content reaching up to 90%. The deposition mechanism and phase composition were compared with those of coatings deposited from i) intermixed alumina-chromia suspension and ii) alumina suspension doped with chromium nitrate nonahydrate solution. All deposition routes showed alternative ways of preparation of novel multimaterial coatings. It was demonstrated that the chromia addition and the deposition route play the crucial role in the pronounced formation of the thermodynamically stable α-phase. © 2019

Keywords
Alumina; Aluminum oxide; Chromium compounds; Phase composition; Plasma jets; Plasma spraying; Powder coatings; Waterworks, Alumina suspensions; Aluminum oxide powders; Chromium oxides; Deposition mechanism; Hybrid suspension; Suspension plasma spraying; Thermodynamically stable; WSP-H, Aluminum coatings
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-13876 (URN)10.1016/j.surfcoat.2019.04.091 (DOI)2-s2.0-85065121437 (Scopus ID)
Note

Funders: Technology Agency of the Czech Republic, TE02000011; Operational Programme Prague – Competitiveness, CZ.2.16/3.1.00/21566

Available from: 2019-05-24 Created: 2019-05-24 Last updated: 2019-07-26Bibliographically approved
Kumara, C., Segerstark, A., Hanning, F., Dixit, N., Joshi, S. V., Moverare, J. & Nylén, P. (2019). Microstructure modelling of laser metal powder directed energy deposition of alloy 718. Additive Manufacturing, 25, 357-364
Open this publication in new window or tab >>Microstructure modelling of laser metal powder directed energy deposition of alloy 718
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2019 (English)In: Additive Manufacturing, ISSN 2214-8604, Vol. 25, p. 357-364Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Phase-field, DED, Heat treatment, Thermal cycle, Modelling
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology; ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-13195 (URN)10.1016/j.addma.2018.11.024 (DOI)000456378800034 ()2-s2.0-85057193791 (Scopus ID)
Funder
Knowledge Foundation
Note

Funders: European Regional Development Fund for project 3Dprint

Available from: 2018-12-12 Created: 2018-12-12 Last updated: 2019-04-03Bibliographically approved
Venkatesh, L. N., Venkataraman, B., Tak, M., Sivakumar, G. S., Gundakaram, R. C., Joshi, S. V. & Samajdar, I. S. (2019). Room temperature and 600 °C erosion behaviour of various chromium carbide composite coatings. Wear, 422-423, 44-53
Open this publication in new window or tab >>Room temperature and 600 °C erosion behaviour of various chromium carbide composite coatings
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2019 (English)In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 422-423, p. 44-53Article in journal (Refereed) Published
Abstract [en]

In this study, the erosion behaviour of laser clad chromium carbide-Ni rich alloy composite coatings with a wide range of carbide contents at room temperature and 600 °C were investigated. The variation in carbide content of the coatings was due to dilution from the substrate and the high cooling rate in the laser cladding process preventing re-solidification of the molten carbides. Erosion rate was observed to be a function of carbide content alone and was significantly higher at 600 °C as compared to room temperature. Erosion wear ratio (E90/E30) was also dependent on carbide content but decreased at higher temperature and higher carbide contents. A comparison of erosion behaviour with detonation and plasma sprayed counterparts showed the superior performance of laser clad coatings at 600 °C. The poor erosion performance of the detonation and plasma sprayed coatings was due to weak splat bonding. Thick oxide layer formed on the steel substrate after pre-oxidation resulted in its poor erosion performance.

Keywords
Laser processing, Thermal spray coatings, Solid particle erosion, Metal matrix composites, Hardness
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-13462 (URN)10.1016/j.wear.2019.01.025 (DOI)2-s2.0-85059935850 (Scopus ID)
Available from: 2019-02-07 Created: 2019-02-07 Last updated: 2019-07-25Bibliographically approved
Mandati, S., Dey, S. R., Joshi, S. V. & Sarada, B. V. (2019). Two-dimensional CuIn1−xGaxSe 2 nano-flakes by pulse electrodeposition for photovoltaic applications. Solar Energy, 181, 396-404
Open this publication in new window or tab >>Two-dimensional CuIn1−xGaxSe 2 nano-flakes by pulse electrodeposition for photovoltaic applications
2019 (English)In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 181, p. 396-404Article in journal (Refereed) Published
Abstract [en]

Fabrication of Cu(In,Ga)Se 2 (CIGS) absorber layers containing two-dimensional nano-flake structures using a single stage pulse electrodeposition technique is reported for the first time, wherein CuCl 2 , InCl 3 , GaCl 3 and H 2 SeO 3 are used as precursors in a pH 3 buffer. The method employs tri-sodium citrate as complexing agent. The phenomenon of intrinsic electrochemical dissolution associated with pulse electrodeposition technique is efficiently utilized to obtain CIGS nano-flakes. The presence of tri-sodium citrate and the relaxation time during pulse electrodeposition play crucial role in achieving control over composition and morphology of CIGS films thereby aiding in the formation of nano-flakes. Evolution of nano-flake structures is systematically investigated with the increase in deposition time during pulse electrodeposition. Elemental analysis reveals the stoichiometric composition of nano-flake films while the formation of chalcopyrite phase-pure CIGS is confirmed by XRD and Raman analyses. The bandgap of CIGS nano-flakes is inferred to be about 1.21 eV from Tauc's plot. Mott-Schottky studies unveil the p-type conductivity of the CIGS with a flat-band potential and carrier density values of −0.15 V and 5.2 × 10 16 cm −3 , respectively. Photoelectrochemical characterization of CIGS films affirms their photoactivity and the photoresponse is almost 20 times compared to the traditional planar CIGS films. Nanostructured CIGS films fabricated by low-cost pulse electrodeposition method reduce materials consumption while promising excellent photoresponse and are suitable for photovoltaic and photoelectrochemical applications. © 2019 International Solar Energy Society

Keywords
Electrochemical dissolution, Nano flakes, Copper indium gallium selenide, Pulse electrodeposition, Photoelectrochemical cells, Solar cells
National Category
Energy Engineering
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-13742 (URN)10.1016/j.solener.2019.02.022 (DOI)000463120700043 ()2-s2.0-85061605835 (Scopus ID)
Note

Funders: U.S. Department of Energy, DE-AC36-08GO28308; Government of India, IUSSTF/JCERDC-SERIIUS/2012

Available from: 2019-03-21 Created: 2019-03-21 Last updated: 2019-07-25Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-5521-6894

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