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Publications (10 of 178) Show all publications
Sadeghimeresht, E., Reddy, L., Hussein, T., Markocsan, N. & Joshi, S. V. (2018). Chlorine-induced high temperature corrosion of HVAF-sprayed Ni-based alumina and chromia forming coatings. Corrosion Science, 132(March), 170-184
Open this publication in new window or tab >>Chlorine-induced high temperature corrosion of HVAF-sprayed Ni-based alumina and chromia forming coatings
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2018 (English)In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 132, no March, p. 170-184Article in journal (Refereed) Published
Abstract [en]

Chlorine-induced corrosion of HVAF-sprayed Ni21Cr and Ni5Al coatings was investigated in 5 vol.% O2 + 500vppm HCl + N2 with and without KCl at 600 °C up to 168 h. Both coatings were protective in the absence of KCl. With KCl, Ni21Cr degraded through a two-stage mechanism: 1) formation of K2CrO4 followed by diffusion of Cl− through the oxide grain boundaries to yield chlorine and a non-protective oxide, and 2) inward diffusion of chlorine though defects in the non-protective oxide, leading to breakaway oxidation. Cl−/Cl2 could not diffuse through the protective alumina scale formed on Ni5Al, hence the corrosion resistance increased.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Thermal spray coating, NiCr, NiAl, High-Velocity Air Fuel (HVAF), biomass-/waste-fired boiler, fireside corrosion
National Category
Manufacturing, Surface and Joining Technology Metallurgy and Metallic Materials Composite Science and Engineering
Identifiers
urn:nbn:se:hv:diva-11960 (URN)10.1016/j.corsci.2017.12.033 (DOI)
Funder
Knowledge Foundation, DNR 20160201
Available from: 2017-12-29 Created: 2017-12-29 Last updated: 2018-05-03Bibliographically approved
Mandati, S., Dey, S. R., Joshi, S. V. & Bulusu, S. V. V. (2018). Cu(In,Ga)Se2 Films with Branched Nanorod Architectures Fabricated by Economic and Environmentally Friendly Pulse-Reverse Electrodeposition Route. ACS Sustainable Chemistry and Engineering
Open this publication in new window or tab >>Cu(In,Ga)Se2 Films with Branched Nanorod Architectures Fabricated by Economic and Environmentally Friendly Pulse-Reverse Electrodeposition Route
2018 (English)In: ACS Sustainable Chemistry and Engineering, ISSN 2168-0485Article in journal (Refereed) Epub ahead of print
Abstract [en]

Cu(In,Ga)Se2 (CIGS) materials are one of the most promising solar cell technologies owing to their large absorption coefficient and tunable direct bandgap, and they have gained considerable commercial maturity. The study herein puts forward the preparation of nanostructured CIGS films containing branched nanorod architectures, which is reported for the first time. The process employs an economic pulse-reverse electrodeposition technique by utilizing the fundamentals of electro-reduction and oxidation to fabricate nanostructured CIGS and completely avoids conventional energy-intensive high-temperature annealing/selenization step. Comprehensive characterization of nanoarchitectured films reveals the stoichiometric composition and chalcopyrite structure with dominant (112) orientation. Nanostructured CIGS exhibits excellent photoactivity with a photocurrent density of 4.31 mA/cm2 at -0.13 V vs RHE in a liquid junction, which is highest for a bare CIGS film and is attributable to its inherent high interface area and better charge transport properties compared to planar films. The ability to produce such efficient nanostructures using an economic, scalable, sustainable, and eco-friendly approach can considerably reduce fabrication costs compared with existing high-temperature bulk material preparation methods. © 2018 American Chemical Society.

Place, publisher, year, edition, pages
American Chemical Society, 2018
Keywords
Copper indium gallium selenide, Nanostructured films, Photoelectrochemical cells, Pulse-reverse electrodeposition, Solar cells, Copper compounds, Electrodeposition, Electrodes, Fabrication, Gallium compounds, Indium compounds, Layered semiconductors, Nanorods, Nanostructured materials, Chalcopyrite structures, Gallium selenides, High-temperature annealing, Large absorption coefficient, Solar cell technology, Stoichiometric compositions, Film preparation
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-13068 (URN)10.1021/acssuschemeng.8b01840 (DOI)2-s2.0-85054617835 (Scopus ID)
Available from: 2018-10-29 Created: 2018-10-29 Last updated: 2018-10-29
Goel, S., Ahlfors, M., Bahbou, F. & Joshi, S. V. (2018). Effect of Different Post-treatments on the Microstructure of EBM-Built Alloy 718. Journal of materials engineering and performance (Print)
Open this publication in new window or tab >>Effect of Different Post-treatments on the Microstructure of EBM-Built Alloy 718
2018 (English)In: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024Article in journal (Refereed) Epub ahead of print
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).

Place, publisher, year, edition, pages
Springer New York LLC, 2018
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)2-s2.0-85055983075 (Scopus ID)
Note

First Online: 29 October 2018

Available from: 2018-11-19 Created: 2018-11-19 Last updated: 2018-11-19
Sadeghimeresht, E., Markocsan, N., Hussain, T., Huhtakangas, M. & Joshi, S. V. (2018). Effect of SiO2 Dispersion on Chlorine-Induced High-Temperature Corrosion of High-Velocity Air-Fuel Sprayed NiCrMo Coating. Corrosion, 74(9), 984-1000
Open this publication in new window or tab >>Effect of SiO2 Dispersion on Chlorine-Induced High-Temperature Corrosion of High-Velocity Air-Fuel Sprayed NiCrMo Coating
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2018 (English)In: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 74, no 9, p. 984-1000Article in journal (Refereed) Published
Abstract [en]

NiCrMo coatings with and without dispersed SiO2 were deposited using high-velocity air-fuel technique. Thermogravimetric experiments were conducted in 5% O-2 + 500 vppm HCl + N-2 with and without a KCl deposit at 600 degrees C for up to 168 h. The SiO2-containing coating showed lower weight change as a result of formation of a protective and adherent Cr-rich oxide scale. SiO2 decelerated short-circuit diffusion of Cr3+ through scale's defects, e.g., vacancies, and promoted the selective oxidation of Cr to form the protective Cr-rich oxide scale. Furthermore, the presence of SiO2 led to less subsurface depletion of Cr in the coating, and accordingly less corrosion of the substrate. The formed corrosion product on the SiO2-free coating was highly porous, non-adherent, and thick.

Place, publisher, year, edition, pages
NACE International, 2018
Keywords
Thermal Spray Coating, Chlorine-Induced High Temperature Corrosion, NiCrMo, SiO2Dispersion, HighVelocity Air-Fuel (HVAF), Biomass-/Waste-Fired Boiler
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-12903 (URN)10.5006/2802 (DOI)000442637200005 ()
Note

Published Online: April 24, 2018

Available from: 2018-09-13 Created: 2018-09-13 Last updated: 2018-09-27Bibliographically approved
Sadeghimeresht, E., Eklund, J., Simon, J. P., Liske, J., Markocsan, N. & Joshi, S. V. (2018). Effect of water vapor on the oxidation behavior of HVAF-sprayed NiCr and NiCrAlY coatings. Materials and corrosion - Werkstoffe und Korrosion, 69(10), 1431-1440
Open this publication in new window or tab >>Effect of water vapor on the oxidation behavior of HVAF-sprayed NiCr and NiCrAlY coatings
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2018 (English)In: Materials and corrosion - Werkstoffe und Korrosion, ISSN 0947-5117, E-ISSN 1521-4176, Vol. 69, no 10, p. 1431-1440Article in journal (Refereed) Published
Abstract [en]

Isothermal oxidation behavior of NiCr and NiCrAlY coatings deposited onto low alloy 16Mo3 steel by high-velocity air fuel (HVAF) process was investigated in 5% O-2+20% H2O+N-2 at 600 degrees C for 168h. Whereas NiCrAlY showed lower mass gain compared to NiCr, both coatings succeeded in maintaining the integrity with the substrate during the exposure without any breakaway oxidation. A thin Cr-rich oxide scale (Cr2O3) formed on NiCr, and a thin mixed oxide scale (Al2O3 with NiCr2O4) formed on NiCrAlY significantly increasing the oxidation protection in the presence of water vapor.

Place, publisher, year, edition, pages
Weinheim: Wiley-VCH Verlagsgesellschaft, 2018
Keywords
NiCr, NiCrAlY, oxidation protection, thermal spray coating, water vapor
National Category
Manufacturing, Surface and Joining Technology Corrosion Engineering
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-13036 (URN)10.1002/maco.201710005 (DOI)000446266800012 ()
Available from: 2018-10-29 Created: 2018-10-29 Last updated: 2018-11-23Bibliographically approved
Ganvir, A., Calinas, R. F., Markocsan, N., Curry, N. & Joshi, S. V. (2018). Experimental visualization of microstructure evolution during suspension plasma spraying of thermal barrier coatings. Journal of the European Ceramic Society
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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2018 (English)In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619XArticle in journal (Refereed) Epub ahead of print
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
Identifiers
urn:nbn:se:hv:diva-12948 (URN)10.1016/j.jeurceramsoc.2018.09.023 (DOI)2-s2.0-85053889817 (Scopus ID)
Available from: 2018-10-26 Created: 2018-10-26 Last updated: 2018-12-05
Björklund, S., Goel, S. & Joshi, S. V. (2018). Function-dependent coating architectures by hybrid powder-suspension plasma spraying: Injector design, processing and concept validation. Materials & design, 142, 56-65
Open this publication in new window or tab >>Function-dependent coating architectures by hybrid powder-suspension plasma spraying: Injector design, processing and concept validation
2018 (English)In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 142, p. 56-65Article in journal (Refereed) Published
Abstract [en]

The attractive properties achieved by Suspension Plasma Spraying (SPS), combined with the availability of high throughput capable plasma spray systems that permit axial feeding, provide encouragement to explore use of suspensions for next generation functional applications. This paper deals with realization of coatings with various pre-determined function-dependent architectures by employing a hybrid powder-suspension feedstock. Some illustrative application-relevant coating architecture designs are discussed, along with the specific benefits that can accrue by deploying a multi-scale powder-suspension feedstock combination. An elegant feedstock delivery arrangement to enable either simultaneous or sequential feeding of powders and suspensions to enable convenient processing of coatings with desired architectures is presented. As proof-of-concept, deposition of layered, composite and functionally graded coatings using the above system is also demonstrated using appropriate case studies

Keywords
Suspension, Hybrid feedstock, Layered, Composite, Functionally graded, Coatings
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-11993 (URN)10.1016/j.matdes.2018.01.002 (DOI)
Note

Available online 4 January 2018

Available from: 2018-01-16 Created: 2018-01-16 Last updated: 2018-11-13Bibliographically approved
Sivakumar, G., Banerjee, S., Raja, V. S. & Joshi, S. V. (2018). Hot corrosion behavior of plasma sprayed powder-solution precursor hybrid thermal barrier coatings. Surface & Coatings Technology, 349, 452-461
Open this publication in new window or tab >>Hot corrosion behavior of plasma sprayed powder-solution precursor hybrid thermal barrier coatings
2018 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 349, p. 452-461Article in journal (Refereed) Published
Abstract [en]

In recent times, plasma sprayed powder-solution precursor hybrid composite thermal barrier coatings have been developed to harness the dual benefits of both conventional atmospheric plasma spraying (APS) and solution precursor plasma spraying (SPPS) processes. In this study, hot corrosion behavior of plasma sprayed powder-solution precursor composite (PSP-SPC) YSZ TBCs in molten salt mixtures of 90 wt.% Na2SO4 + 5 wt.% V2O5 + 5 wt.% NaCl and 50 wt.% Na2SO4 + 50 wt.% V2O5 at 900 °C was investigated. The employed coating showed a bimodal microstructure comprising coarse splats derived from the powder feedstock as in the APS process and fine splats resulting from the solution precursor as typical of SPPS process. The PSP-SPC coatings showed a significantly higher resistance to spallation than APS, SPPS and EB-PVD coatings in both the salt environments. These coatings showed shorter life in vanadate environment compared to that of the chloride environments as the former promotes the formation of monoclinic ZrO2 and YVO4 phases more than the latter. © 2018

Place, publisher, year, edition, pages
Elsevier B.V., 2018
Keywords
Composite coatings; Corrosive effects; High temperature corrosion; Plasma jets; Powder coatings; Scanning electron microscopy; Sodium chloride; Sodium sulfate; Sprayed coatings; Superalloys; Surface plasmon resonance; Thermal barrier coatings; Thermal spraying; Vanadium pentoxide; Yttria stabilized zirconia; Zirconia, Atmospheric plasma spraying; Bi-modal microstructures; Ceramic; Chloride environment; Hot corrosion; Molten salt mixtures; Solution precursor; Solution precursor plasma spraying, Plasma spraying
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-12658 (URN)10.1016/j.surfcoat.2018.06.021 (DOI)000441492600048 ()2-s2.0-85048712238 (Scopus ID)
Note

 Available online 15 June 2018.

Available from: 2018-07-04 Created: 2018-07-04 Last updated: 2018-09-13Bibliographically approved
Sadeghimeresht, E., Reddy, L., Hussain, T., Huhtakangas, M., Markocsan, N. & Joshi, S. V. (2018). Influence of KCl and HCl on high temperature corrosion of HVAF-sprayed NiCrAlY and NiCrMo coatings. Materials & design, 148, 17-29
Open this publication in new window or tab >>Influence of KCl and HCl on high temperature corrosion of HVAF-sprayed NiCrAlY and NiCrMo coatings
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2018 (English)In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 148, p. 17-29Article in journal (Refereed) Published
Abstract [en]

The oxidation performance of NiCrAlY and NiCrMo coatings thermally sprayed by high velocity air-fuel (HVAF) technique has been investigated in a chloridizing-oxidizing environment, with and without a KCl deposit, at 600 °C for up to 168 h. Both coatings protected the substrate in the absence of KCl due to formation of a dense Cr-rich oxide scale. In the presence of KCl, Cl−/Cl2 diffused through a non-protective and porous NiCr2O4 scale formed on NiCrAlY, leading to formation of volatile CrCl3. On the other hand, Mo in NiCrMo stimulated the formation of a more protective Cr-rich oxide scale which increased the corrosion resistance by reducing Cl−/Cl2 diffusion.

Place, publisher, year, edition, pages
Elsevier Ltd, 2018
Keywords
Air; Aluminum corrosion; Boiler corrosion; Chromium compounds; Corrosion protection; Corrosion resistance; High temperature corrosion; Potassium compounds; Scale (deposits); Sprayed coatings; Ternary alloys, Fireside corrosion; High velocity air fuels; NiCrAlY; NiCrMo; Thermal spray coatings, Chlorine compounds
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-12245 (URN)10.1016/j.matdes.2018.03.048 (DOI)000430079200003 ()2-s2.0-85044482024 (Scopus ID)
Note

Available online 22 March 2018.

Available from: 2018-04-09 Created: 2018-04-09 Last updated: 2018-05-14Bibliographically approved
Sadeghimeresht, E., Karimi Neghlani, P., Zhang, P., Peng, R., Andersson, J., Pejryd, L. & Joshi, S. V. (2018). Isothermal Oxidation Behavior of EBM-Additive Manufactured Alloy 718. In: Proceedings of the 9th International Symposium on Superalloy 718 & Derivatives: Energy, Aerospace, and Industrial Applications. Paper presented at 9th International Symposium on Superalloy 718 & Derivatives, Energy, Aerospace, and Industrial Applications (pp. 219-240). Springer
Open this publication in new window or tab >>Isothermal Oxidation Behavior of EBM-Additive Manufactured Alloy 718
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2018 (English)In: Proceedings of the 9th International Symposium on Superalloy 718 & Derivatives: Energy, Aerospace, and Industrial Applications, Springer, 2018, p. 219-240Conference paper, Published paper (Refereed)
Abstract [en]

Oxidation of Alloy 718 manufactured by electron beam melting (EBM) process has been undertaken in ambient air at 650, 700, and 800 °C for up to 168 h. At 800 °C, a continuous external chromia oxide enriched in (Cr, Ti, Mn, Ni) and an internal oxide that was branched structure of alumina formed, whereas at 650 and 700 °C, a continuous, thin and protective chromia layer was detected. The oxidation kinetics of the exposed EBM Alloy 718 followed the parabolic rate law with an effective activation energy of ~248 ± 22 kJ/mol in good agreement with values in the literature for conventionally processed chromia-forming Ni-based superalloys. The oxide scale formed on the surface perpendicular to the build direction was slightly thicker, and more adherent compared to the scale formed on the surface along the build direction, attributed to the varied grain texture in the two directions of the EBM-manufactured specimens. The increased oxygen diffusion and high Cr depletion found on the surface along the build direction were attributed to the fine grains and formation of vacancies/voids along this grain orientation.

Place, publisher, year, edition, pages
Springer, 2018
Series
The Minerals, Metals & Materials Series, ISSN 2367-1181, E-ISSN 2367-1696
Keywords
Additive manufacturing, Electron beam melting, Alloy 718, Oxidation behavior, Grain texture
National Category
Metallurgy and Metallic Materials Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-12347 (URN)10.1007/978-3-319-89480-5_13 (DOI)978-3-319-89479-9 (ISBN)
Conference
9th International Symposium on Superalloy 718 & Derivatives, Energy, Aerospace, and Industrial Applications
Note

First Online: 13 May 2018

Available from: 2018-10-26 Created: 2018-10-26 Last updated: 2018-11-08Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-5521-6894

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