| 1. |
- Musalek, Radek, et al.
(författare)
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Microstructures and properties of thermal barrier coatings deposited by hybrid water-stabilized plasma torch
- 2019
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Ingår i: Proceedings of the International Thermal Spray Conference. - : ASM International. - 9781510888005 ; , s. 738-745
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Konferensbidrag (refereegranskat)abstract
- Hybrid Water-Stabilized Plasma (WSP-H) torch provides high-enthalpy plasma which may be utilized for high-throughput and yet economical spraying of coatings from powders, suspensions, and solutions. It was previously demonstrated that microstructures and functional properties of the WSP-H coatings may be tailored to a wide extent for various new applications, namely those requiring high coating thickness and/or coating of large components. In this study, applicability of WSP-H technology for spraying of novel thermal barrier coatings (TBCs) is demonstrated. WSP-H technology was used for spraying of yttria-stabilized zirconia (YSZ) top-coats from powder, suspension and solution. Yttria content in the top-coat feedstock was 7-8 wt.%. NiCrAlY bond-coat was also sprayed by WSP-H and Hastelloy-X alloy was used as substrate material. Microstructure, phase composition, and endurance of the deposited coatings in thermal cycling fatigue (TCF) test were evaluated. Each thermal cycle consisted of rapid heating to 1100 °C, followed by one hour dwell and rapid cooling. All coatings showed excellent stability and TCF resistance withstanding more than 700 cycles surpassing in TCF test some of the currently commercially used TBCs. Lifetime of TBC with columnar top-coat deposited from suspension exceeded even more than 900 cycles. © 2019 ASM International. All rights reserved.
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| 2. |
- Musalek, Radek, et al.
(författare)
-
Microstructures and Thermal Cycling Properties of Thermal Barrier Coatings Deposited by Hybrid Water-Stabilized Plasma Torch
- 2020
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Ingår i: Journal of thermal spray technology (Print). - : Springer Science and Business Media LLC. - 1059-9630 .- 1544-1016. ; 29:3, s. 444-461
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Tidskriftsartikel (refereegranskat)abstract
- Hybrid water-stabilized plasma (WSP-H) torches provide high-enthalpy plasma which may be utilized for high-throughput and yet economical spraying of coatings from powders, suspensions, and solutions. It was previously demonstrated that microstructures and functional properties of the WSP-H coatings may be tailored to a wide extent for new applications, namely those requiring high coating thickness and/or coating of large components. In this study, applicability potential of WSP-H technology for spraying of novel thermal barrier coatings (TBCs) is demonstrated. WSP-H technology was used for spraying of yttria-stabilized zirconia (YSZ) top-coats from powder, suspension, and solution. Yttria content in the top-coat feedstock was 7-8 wt.%. In addition, gadolinium zirconate (Gd2Zr2O7-GZO) was sprayed from suspension for comparison. NiCrAlY bond-coat was also deposited by WSP-H, and Hastelloy-X alloy was used as substrate material. Microstructure, phase composition, and endurance of the deposited coatings in thermal cycling fatigue (TCF) test and during high-temperature short-term annealing were evaluated. All coatings showed excellent high-temperature stability and TCF resistance withstanding more than 650 cycles, surpassing some of the currently commercially used TBCs. Lifetime of the TBC with columnar top-coat deposited from YSZ suspension exceeded even more than 900 cycles.
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| 3. |
- Tesar, Tomas, et al.
(författare)
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Increasing α-phase content of alumina-chromia coatings deposited by suspension plasma spraying using hybrid and intermixed concepts
- 2019
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Ingår i: Surface & Coatings Technology. - : Elsevier BV. - 0257-8972 .- 1879-3347. ; 371:S1, s. 298-311
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Tidskriftsartikel (refereegranskat)abstract
- 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
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| 4. |
- Gupta, Mohit Kumar, 1986-, et al.
(författare)
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Microstructure and failure analysis of suspension plasma sprayed thermal barrier coatings
- 2020
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Ingår i: Surface & Coatings Technology. - : Elsevier BV. - 0257-8972 .- 1879-3347. ; 382
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Tidskriftsartikel (refereegranskat)abstract
- Improvements in performance of thermal barrier coatings (TBCs) used in gas turbine engines are highly desired as they can result in higher engine efficiency leading to reduction of harmful emissions. Suspension plasma spraying (SPS) has been shown to produce high performance porous columnar TBCs that can provide low thermal conductivity and high durability. Apart from the topcoat microstructure and chemistry, the lifetime of TBCs is also dependent on bondcoat microstructure and chemistry, and topcoat-bondcoat interface roughness. In case of SPS TBCs, the interface roughness can significantly affect the columnar topcoat microstructure, thus making the bondcoat selection even more crucial. In this work, six different sets of samples were produced by fabricating bondcoats with conventional atmospheric plasma spraying (APS), high velocity air fuel (HVAF) spraying, or hybrid water/argon stabilised plasma (WSP-H) gun, and SPS topcoats using axial SPS (ASPS) or WSP-H spray guns. The objective of this study was to investigate the influence of varying the topcoat microstructure, bondcoat microstructure and topcoat-bondcoat interface roughness on oxide growth behaviour and thermal cyclic fatigue (TCF) lifetime of SPS TBCs. Samples after failure were investigated to understand the failure mechanism in each case. The results showed that changing the bondcoat spray process and spray gun resulted in significant variation in bondcoat surface roughness. A porous columnar structure was created by the ASPS process, while a feathery columnar structure was created by the WSP-H spray gun in this study. Samples with WSP-H bondcoat resulted in highest cyclic lifetime in this study, despite showing severe oxidation of the bondcoat as compared to APS and HVAF bondcoats. This result could be attributed to the very high bondcoat surface roughness in these samples that could have resulted in improved mechanical anchoring of the topcoat. The HVAF bondcoats showed the best oxidation resistance in this study. © 2019 Elsevier B.V.
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