Influence of substrate material on the life of atmospheric plasma sprayed thermal barrier coatings

Eriksson, Robert; Johansson, Sten; Brodin, Hå̊kan; Broitman, Esteban; Östergren, Lars; Li, Xinhai

doi:10.1016/j.surfcoat.2013.06.101

Cited by 20 publications

(9 citation statements)

References 25 publications

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“…Therefore, the internal oxidation 1 of the rough bond coat layer is inevitable during long-term exposure at high temperature. Actually, the internal oxidation is a common phenomenon even for a single layered bond coat [10,[14][15][16]. For example, it was reported that, for an APS bond coat, the amount of the internal oxides can be up to 50% (in volume) after 120 cycles at 1121 °C [15].…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Role of internal oxidation on the failure of air plasma sprayed thermal barrier coatings with a double-layered bond coat

Zou

Jia

Yang

et al. 2017

Surface and Coatings Technology

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Failure of air plasma sprayed (APS) thermal barrier coatings (TBCs) with a double-layered bond coat was investigated. The bond coat consists of a dense layer near the substrate side and a porous layer on the surface. Both were made of NiCoCrAlY alloy and deposited using high velocity oxygen-fuel technique. After thermal cycling, a large amount of internal oxides formed (up to 45% in volume fraction), introducing a significant volume expansion both in in-plane and perpendicular direction in the bond coat. However, the presence of the ceramic top coat can suppress the bond coat in-plane swelling thus lowering the internal oxidation rate.Compared with the fully dense bond coat, the interface roughness of the porous bond coat increases significantly when internal oxidation occurs. There is a strong correlation between the internal oxidation and the interface roughness. In addition, both the beneficial and detrimental effects of internal oxidation on TBC failure were discussed. It is proposed that a fully dense bond coat with a proper surface roughness should have a longer thermal cycling

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Section: Accepted Manuscriptmentioning

confidence: 99%

Role of internal oxidation on the failure of air plasma sprayed thermal barrier coatings with a double-layered bond coat

Zou

Jia

Yang

et al. 2017

Surface and Coatings Technology

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“…The thicker TGO layer results in a markedly large stress intensity factor during the intermediate and late stage of crack growth, although it is slightly lower during the initiation of crack. As a result, the fast growth rate of the TGO layer leads to the short lifetime performance of the TBC [45]. The TBC is a multilayer coating system including superalloy, intermetallic bond coat, TGO layer, and 13 ceramic top coat.…”

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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“…Faster Al depletion may promote the formation of spinels in the coating and eventually reduce the overall thermal fatigue life of the TBC system. Eriksson et.al have found a significant difference in the TCF life time for the same TBC coatings but on two different substrates [40]. Apart from the Al inter-diffusion, diffusion of other elements between the coating and the substrate is also undesirable as the elements that give the properties and functionality for coating/substrate tend to diffuse out.…”

Section: Fig 8 Schematic Illustration Of a Thermal Cycling Test Rigmentioning

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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Influence of substrate material on the life of atmospheric plasma sprayed thermal barrier coatings

Cited by 20 publications

References 25 publications

Role of internal oxidation on the failure of air plasma sprayed thermal barrier coatings with a double-layered bond coat

Role of internal oxidation on the failure of air plasma sprayed thermal barrier coatings with a double-layered bond coat

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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