Evolution of hot corrosion resistance of YSZ, Gd2Zr2O7, and Gd2Zr2O7+YSZ composite thermal barrier coatings in Na2SO4+V2O5 at 1050°C

Habibi, M. H.; Wang, Li; Guo, Shengmin

doi:10.1016/j.jeurceramsoc.2012.01.006

Cited by 156 publications

(59 citation statements)

References 26 publications

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“…However, a further improvement of the efficiency of gas turbines is intended by further improvement of the combustion and cooling technology in combination with higher turbine inlet temperature. This also implies that the standard material YSZ is approaching certain limitation due to its sintering and phase transformation at elevated temperatures [2][3][4][5]. In order to overcome disadvantages of YSZ and meet the ambitious design goal, the feasible and economic method is to search for new candidate ceramic materials with even lower thermal conductivity, higher operating temperature, better sintering resistance and phase stability at higher temperature on the premise of the usage of advanced superalloys and cooling technique [6,7].…”

Section: Introductionmentioning

confidence: 99%

Investigation about thermal conductivities of La2Ce2O7 doped with calcium or magnesium for thermal barrier coatings

Zhang

Yuan

et al. 2012

Journal of Alloys and Compounds

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Section: Introductionmentioning

confidence: 99%

Investigation about thermal conductivities of La2Ce2O7 doped with calcium or magnesium for thermal barrier coatings

Zhang

Yuan

et al. 2012

Journal of Alloys and Compounds

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“…For the Ni-based bond coat ( Fig. 6(B-2)), the gray region (position (2)) is composed of Ni, Cr, O, and Al elements, whereas the black region (position (1) based coatings, and they concluded the Gd2Zr2O7-based coating is more thermally and chemically stable than the YSZ-based coating [44].…”

Section: Furnace Cyclic Thermal Fatigue Testmentioning

confidence: 99%

Thermal durability and fracture behavior of layered Yb-Gd-Y-based thermal barrier coatings in thermal cyclic exposure

Jung

et al. 2017

Surface and Coatings Technology

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The effects of structural design on the thermal durability of Yb-Gd-Y-based thermal barrier coatings (TBCs) were investigated through thermal cyclic exposure tests, such as furnace cyclic thermal fatigue (FCTF) and jet engine thermal shock (JETS) tests. The effects of composition in the bond coat and feedstock purity for the buffer layer on its lifetime performance were also examined. To overcome the drawbacks of Yb-Gd-Y material with poor thermal durability due to poor mechanical properties and low coefficient of thermal expansion, a buffer layer was introduced in the Yb-Gd-Y-based TBC systems. In the FCTF tests, the TBC with the CoNi-based bond coat and the buffer layer of regular purity showed a longer lifetime performance than other TBCs, especially the TBCs without the buffer layer.In the JETS tests, the TBC with the Ni-based bond coat and the buffer layer of high purity showed a sound condition after 2000 cycles, showing better interfacial stability for TBC with the Ni-based bond coat rather than that with the CoNi-based bond coat in the single layer coatings without the buffer layer. The buffer layer effectively enhanced the thermal durability in slow temperature change, while the bond-coat composition and the feedstock purity for the buffer layer were found to be important factor to improve the thermal durability of the TBC in fast temperature change. Finally, these research findings allow us to control the structure, composition, and feedstock purity in TBC system for improving the thermal durability in cyclic thermal environments.

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“…Pure Na2SO4 does not directly react with YSZ layer in a TBC although its infiltration into pores and cracks may eventually cause thermo-mechanical damage [46]. There has been considerable research on the corrosion behavior in thermal barrier coatings either in the presence of Na2SO4 and V2O5 or only V2O5 [19,[47][48][49][50][51][52][53][54]. The tests reported in the literature have been conducted from 700 o C to about 1050 o C using different salt concentrations, with a majority of the tests focused on YSZ thermal barrier coatings.…”

Section: Hot Corrosion Tests -Failure Mechanismsmentioning

confidence: 99%

“…The tests reported in the literature have been conducted from 700 o C to about 1050 o C using different salt concentrations, with a majority of the tests focused on YSZ thermal barrier coatings. Limited research on the corrosion mechanism of other top coat materials such as gadolinium zirconate [48,49,55], ceria-stabilized zirconia [56][57][58], titaniastabilized zirconia [58], scandia and yttria co-stabilized zirconia [59] and zirconia-alumina [54] have been reported as well.…”

Section: Hot Corrosion Tests -Failure Mechanismsmentioning

confidence: 99%

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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Evolution of hot corrosion resistance of YSZ, Gd2Zr2O7, and Gd2Zr2O7+YSZ composite thermal barrier coatings in Na2SO4+V2O5 at 1050°C

Cited by 156 publications

References 26 publications

Investigation about thermal conductivities of La2Ce2O7 doped with calcium or magnesium for thermal barrier coatings

Investigation about thermal conductivities of La2Ce2O7 doped with calcium or magnesium for thermal barrier coatings

Thermal durability and fracture behavior of layered Yb-Gd-Y-based thermal barrier coatings in thermal cyclic exposure

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

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