Thermal conductivity and thermal cyclic fatigue of multilayered Gd2Zr2O7/YSZ thermal barrier coatings processed by suspension plasma spray

Mahade, Satyapal; Curry, Nicholas; Björklund, Stefan; Markocsan, Nicolaie; Nylén, Per

doi:10.1016/j.surfcoat.2015.11.009

Cited by 91 publications

(34 citation statements)

References 52 publications

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“…Especially, vertically cracked and columnar structured coatings with high strain tolerance make SPS a great potential process to apply high‐performance TBCs. As first reported by Mahade et al, multilayer high strain tolerant columnar GZO TBCs has been successfully deposited with SPS. This has proven that SPS is a practical process to deposit high strain tolerance GZO coating.…”

Section: Introductionmentioning

confidence: 79%

“…2,6,10 Gadolinium zirconate (Gd 2 Zr 2 O 7 , GZO) as a very promising top coat material has attracted a lot of interest for the last two decades. It has a high melting point (2570°C), 6,11 very good phase stability, 12 a considerably low thermal conductivity (1.2 W/mK), 13,14 excellent calcium-magnesium-alumino-silicates (CMAS) infiltration resistance [15][16][17] and a high CTE (10.5 × 10 −6 /K) 18 which is close to that of YSZ. However, the relatively low fracture toughness of GZO which facilitates crack propagation is its drawback for the applications as TBC.…”

Section: Introductionmentioning

confidence: 99%

“…However, the relatively low fracture toughness of GZO which facilitates crack propagation is its drawback for the applications as TBC. 14,19,20 Furthermore, GZO tends to react with alumina forming a porous GdAlO 3 interphase. 12,21 This reaction weakens the protective function of the thermally grown oxide (TGO) which is formed due to the oxidation of the bond coat in service.…”

Section: Introductionmentioning

confidence: 99%

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Thermal cycling performances of multilayered yttria‐stabilized zirconia/gadolinium zirconate thermal barrier coatings

et al. 2019

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Gadolinium zirconate (Gd2Zr2O7, GZO) as an advanced thermal barrier coating (TBC) material, has lower thermal conductivity, better phase stability, sintering resistance, and calcium‐magnesium‐alumino‐silicates (CMAS) attack resistance than yttria‐stabilized zirconia (YSZ, 6‐8 wt%) at temperatures above 1200°C. However, the drawbacks of GZO, such as the low fracture toughness and the formation of deleterious interphases with thermally grown alumina have to be considered for the application as TBC. Using atmospheric plasma spraying (APS) and suspension plasma spraying (SPS), double‐layered YSZ/GZO TBCs, and triple‐layered YSZ/GZO TBCs were manufactured. In thermal cycling tests, both multilayered TBCs showed a significant longer lifetime than conventional single‐layered APS YSZ TBCs. The failure mechanism of TBCs in thermal cycling test was investigated. In addition, the CMAS attack resistance of both TBCs was also investigated in a modified burner rig facility. The triple‐layered TBCs had an extremely long lifetime under CMAS attack. The failure mechanism of TBCs under CMAS attack and the CMAS infiltration mechanism were investigated and discussed.

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Section: Introductionmentioning

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermal cycling performances of multilayered yttria‐stabilized zirconia/gadolinium zirconate thermal barrier coatings

et al. 2019

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“…This led to the use of multi-layer coatings with YSZ as the inner layer (on top of the bond coat) and gadolinium zirconate coating as the outer layer. It has also been shown that these multi-layer coatings may provide better thermal cycling life compared to single-layer YSZ coatings [26]. These results show that the focus of research on new TBC materials may shift more towards pyrochlores.…”

Section: Top Coatmentioning

confidence: 86%

Failure mechanisms in APS and SPS thermal barrier coatings during cyclic oxidation and hot corrosion

Jonnalagadda¹

2017

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Linköping 2017Front page image: The top view of yttria stabilized zirconia thermal barrier coating after exposure to a salt mixture of vanadium pentoxide and sodium sulfate at 900 o C.During the course of research underlying this thesis, Krishna Praveen Jonnalagadda was enrolled in Agora Materiae, a multidisciplinary doctoral program at Linköping University, Sweden.ISBN: 978-91-7685-594-2 ISSN: 0280-7971Printed by LiU-Tryck 2017 iii AbstractThermal Barrier Coatings (TBCs) are advanced material systems that are being used in the hot sections of gas turbines such as combustor, turbine blades, and vanes. The top ceramic coating in TBCs provides insulation against the hot gases and the intermediate metallic bond coat provides oxidation and corrosion resistance to the underlying turbine components.Durability of thermal barrier coatings is very important for the overall performance of the gas turbine. TBCs can fail in several different ways and there is a combination of more than one failure mechanism in most situations. One of the most widely used TBC is atmospheric plasma sprayed (APS) yttria stabilized zirconia (YSZ). Both the deposition technique and the TBC material have certain limitations. The main aim of this research is to study new TBC materials and/or new deposition techniques and compare with the conventional YSZ and understand their failure mechanisms during cyclic oxidation and hot corrosion.Thermal cyclic oxidation of a newly developed high purity nano YSZ thermal barrier coating has been studied. Cross sectional analysis of exposed as well as completely failed samples showed a mixed-type failure caused by crack propagation parallel to the bond coat/top coat interface. The majority of the damage occurred towards the end of the coating life. A finite element model has been developed to study the probability of crack growth along different paths that leads to the final failure.Hot corrosion mechanism in suspension plasma sprayed two-layer gadolinium zirconate/YSZ, three-layer dense gadolinium zirconate/gadolinium zirconate/YSZ, and a single-layer YSZ has been studied in the presence of sodium sulfate and vanadium pentoxide. The test results showed that gadolinium zirconate coatings were more susceptible to corrosion compared to YSZ coatings despite gadolinium zirconate coatings having lower reactivity with the corrosive salts.Thermal cycling behavior of a high chromium bond coat has been studied. Cross-sectional analysis showed formation of sandwich type microstructure with chromium rich oxide and alumina as the top and the bottom layers.Inter-diffusion of minor elements between different MCrAlY coatings -substrate systems has been studied using, diffusion simulation software, DICTRA. The simulation results showed that the diffusion of minor elements in the coatings is dependent on the rate of β phase depletion in the beginning. After the depletion of β phase there was no clear dependence of the coating composition on the diffusion of minor elements.v SammanfattningTermiska barriärskikt, eller TBC från...

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“…16. with double layer TBC (c), which improve the possibility of working in higher operational temperature [87] Intensive researches carried out by Mahade et al [88,89] concern double (DL) and triple layer (TL) thermal barrier coating systems. In DL they propose in ceramic top coat first layer as YSZ and second one from pyrochlore, in this case gadolinum zirconate (GZ).…”

Section: News In the Field Of Thermal Barrier Coatingsmentioning

confidence: 99%

Thermal Barrier Coatings Manufactured by Suspension Plasma Spraying - A Review

Łatka

2018

Advances in Materials Science

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Thermal barrier coatings (TBC) is one of the most intensively studied of coatings’ applications area. From 1970’s TBC are developed in two independent ways: (i) development in new materials, with lower thermal conductivity, better erosion resistance and better thermal shock resistance or (ii) development in new deposition techniques. On this field besides conventional atmospheric plasma spraying (APS) and almost conventional (because of very common use) EB-PVD method, in the past 20 years two new techniques have been developed, namely suspension plasma spraying (SPS) and solution precursor plasma spraying (SPPS). In this paper only SPS method was described, as well as, new materials, which could be used in industrial applications of TBC. Moreover, the key issues, like suspension preparation, type of suspension injection, interaction between liquid droplets and plasma jet and deposition mechanism were described.

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Thermal conductivity and thermal cyclic fatigue of multilayered Gd2Zr2O7/YSZ thermal barrier coatings processed by suspension plasma spray

Cited by 91 publications

References 52 publications

Thermal cycling performances of multilayered yttria‐stabilized zirconia/gadolinium zirconate thermal barrier coatings

Thermal cycling performances of multilayered yttria‐stabilized zirconia/gadolinium zirconate thermal barrier coatings

Failure mechanisms in APS and SPS thermal barrier coatings during cyclic oxidation and hot corrosion

Thermal Barrier Coatings Manufactured by Suspension Plasma Spraying - A Review

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