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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
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
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: 2018-02-05Bibliographically 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
Jafari, R., Sadeghimeresht, E., Shahrabi Farahani, T., Huhtakangas, M., Markocsan, N. & Joshi, S. V. (2018). KCl-Induced High Temperature Corrosion Behavior of HVAF-Sprayed Ni-Based Coatings in Ambient Air. Paper presented at International Thermal Spray Conference & Exposition, ITSC 2017, Düsseldorf, Germany, June 7-9, 2017. Journal of thermal spray technology (Print), 27(3), 500-511
Open this publication in new window or tab >>KCl-Induced High Temperature Corrosion Behavior of HVAF-Sprayed Ni-Based Coatings in Ambient Air
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2018 (English)In: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 27, no 3, p. 500-511Article in journal (Refereed) Published
Abstract [en]

KCl-induced high temperature corrosion behavior of four HVAF-sprayed Ni-based coatings (Ni21Cr, Ni5Al, Ni21Cr7Al1Y, and Ni21Cr9Mo) under KCl deposit has been investigated in ambient air at 600°C up to 168h. The coatings were deposited onto 16Mo3 steel - a widely used boiler tube material.Uncoated substrate, 304L and Sanicro25 were used as reference materials in the test environment.SEM/EDS and XRD techniques were utilized to characterize the as-sprayed and exposed samples.The results showed that the small addition of KCl significantly accelerated degradation to the coatings. All coatings provided better corrosion resistance compared to the reference materials. The alumina-forming Ni5Al coating under KCl deposit was capable of forming a more protective oxide scale compared to the chromia-forming coatings as penetration of Cl through diffusion paths was hindered. Both active corrosion and chromate formation mechanisms were found to be responsible for Page 1 of 23ASM the corrosion damages. The corrosion resistance of the coatings based on the microstructure analysis and kinetics had the following ranking (from the best to worst): Ni5Al >Ni21Cr> Ni21Cr7Al1Y>Ni21Cr9Mo.

Place, publisher, year, edition, pages
Springer, 2018
National Category
Manufacturing, Surface and Joining Technology Metallurgy and Metallic Materials Composite Science and Engineering
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-11959 (URN)10.1007/s11666-017-0684-9 (DOI)000425622500022 ()
Conference
International Thermal Spray Conference & Exposition, ITSC 2017, Düsseldorf, Germany, June 7-9, 2017
Funder
Knowledge Foundation, SCoPe: Dnr 20160201
Note

This article is an invited paper selected from presentations at the 2017 International Thermal Spray Conference, held June 7–9, 2017, in Düsseldorf, Germany, that has been expanded from the original presentation.

Available from: 2017-12-29 Created: 2017-12-29 Last updated: 2018-05-03Bibliographically approved
Murray, J. W., Leva, A., Joshi, S. V. & Hussain, T. (2018). Microstructure and wear behaviour of powder and suspension hybrid Al2O3–YSZ coatings. Ceramics International, 44(7), 8498-8504
Open this publication in new window or tab >>Microstructure and wear behaviour of powder and suspension hybrid Al2O3–YSZ coatings
2018 (English)In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 44, no 7, p. 8498-8504Article in journal (Refereed) Published
Abstract [en]

Abstract Suspension based plasma sprayed coatings can yield superior microstructural and tribological properties compared to conventional powder based plasma sprayed coatings. This study investigates a new hybrid method, using simultaneous spraying from powder and suspension, to produce composite coatings using alumina and yttria stabilised zirconia (YSZ), with potentially excellent wear and thermal properties. Dry sliding wear showed the alumina suspension-YSZ suspension coating yielded half the specific wear rate of the alumina powder-YSZ suspension, explained by preferential gamma alumina formation and increased porosity in the latter. Both YSZ-containing samples showed superior toughness and wear rate than simple alumina powder and suspension coatings.

Keywords
A suspensions, B composites, C wear resistance, D Al2O3
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-12076 (URN)10.1016/j.ceramint.2018.02.048 (DOI)000428974300150 ()2-s2.0-85043470134 (Scopus ID)
Note

Available online 6 February 2018

Available from: 2018-02-22 Created: 2018-02-22 Last updated: 2018-04-19Bibliographically approved
Ganvir, A., Joshi, S. V., Markocsan, N. & Vassen, R. (2018). Tailoring columnar microstructure of axial suspension plasma sprayed TBCs for superior thermal shock performance. Materials & design, 144, 192-208
Open this publication in new window or tab >>Tailoring columnar microstructure of axial suspension plasma sprayed TBCs for superior thermal shock performance
2018 (English)In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 144, p. 192-208Article in journal (Refereed) Published
Abstract [en]

This paper investigates the thermal shock behavior of thermal barrier coatings (TBCs) produced by axial suspension plasma spraying (ASPS). TBCs with different columnar microstructures were subjected to cyclic thermal shock testing in a burner rig. Failure analysis of these TBCs revealed a clear relationship between lifetime and porosity. However, tailoring the microstructure of these TBCs for enhanced durability is challenging due to their inherently wide pore size distribution (ranging from few nanometers up to few tens of micrometers). This study reveals that pores with different length scales play varying roles in influencing TBC durability. Fracture toughness shows a strong correlation with the lifetime of various ASPS TBCs and is found to be the prominent life determining factor. Based on the results, an understanding-based design philosophy for tailoring of the columnar microstructure of ASPS TBCs for enhanced durability under cyclic thermal shock loading is proposed. © 2018 The Authors

Place, publisher, year, edition, pages
Elsevier Ltd, 2018
Keywords
Coatings; Durability; Fracture toughness; Microstructure; Plasma jets; Plasma spraying; Pore size; Shock testing; Size distribution; Thermal shock; Thermal spraying, Columnar microstructures; Cyclic thermal shocks; Design philosophy; Different length scale; Strong correlation; Superior performance; Suspension plasma spraying; Thermal barrier coating (TBCs), Thermal barrier coatings
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-12192 (URN)10.1016/j.matdes.2018.02.011 (DOI)2-s2.0-85042178578 (Scopus ID)
Available from: 2018-03-05 Created: 2018-03-05 Last updated: 2018-05-23Bibliographically approved
Goel, S., Björklund, S., Curry, N., Wiklund, U. & Joshi, S. V. (2017). Axial suspension plasma spraying of Al2O3 coatings for superior tribological properties. Surface & Coatings Technology, 315, 80-87
Open this publication in new window or tab >>Axial suspension plasma spraying of Al2O3 coatings for superior tribological properties
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2017 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 315, p. 80-87Article in journal (Refereed) Published
Abstract [en]

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

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2017
Keywords
Atmospheric plasma spray; Suspension plasma spray; Axial injection; Alumina; Coating; Microstructure; Micro-hardness; Scratch; Wear
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-10931 (URN)10.1016/j.surfcoat.2017.02.025 (DOI)000399268100009 ()2-s2.0-85013027004 (Scopus ID)
Available from: 2017-09-20 Created: 2017-09-20 Last updated: 2018-06-18Bibliographically approved
Kumar, S., Ramakrishna, M., Chavan, N. & Joshi, S. V. (2017). Correlation of splat state with deposition characteristics of cold sprayed niobium coatings. Acta Materialia, 130, 177-195
Open this publication in new window or tab >>Correlation of splat state with deposition characteristics of cold sprayed niobium coatings
2017 (English)In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 130, p. 177-195Article in journal (Refereed) Published
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.

Keywords
Cold spray, Niobium, Bonding, Microstructure
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology; ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-12001 (URN)10.1016/j.actamat.2017.03.023 (DOI)
Available from: 2018-01-15 Created: 2018-01-15 Last updated: 2018-01-15Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-5521-6894

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