Protectiveness of Pt and Gd2Zr2O7 layers on EB-PVD YSZ thermal barrier coatings against calcium–magnesium–alumina–silicate (CMAS) attack

Wang, Lu; Guo, Liu; Li, Zhuomin; Peng, Hui; Ma, Yue; Gong, Shengkai; Guo, Hongjian

doi:10.1016/j.ceramint.2015.05.128

Cited by 76 publications

(24 citation statements)

References 27 publications

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“…First, residual CMAS can be observed on the surfaces of these pellets, which indicates that the CMAS applied is enough. Second, CMAS did not cover the whole surfaces of the pellets; this indicates that the contact angle between liquid CMAS and YSZ is larger than 0°, which is in agreement with the results reported in previous literature . Third, bubbles are observed in the upper zones of CMAS on Pellet32 and Pellet77, whereas such bubbles can hardly be observed in CMAS on Pellet6 and Pellet13.…”

Section: Resultssupporting

confidence: 90%

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Pore filling behavior of YSZ under CMAS attack: Implications for designing corrosion‐resistant thermal barrier coatings

et al. 2018

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To understand the pore filling behavior in thermal barrier coatings during calcium‐magnesium‐alumino‐silicate (CMAS) infiltration process, porous yttria‐stabilized zirconia pellets with different sizes of spherical pores were prepared to simulate thermal barrier coatings. The pores (D50 ranging from 6 to 77 μm) were introduced to the pellets using poly methyl methacrylate as pore forming agents. Then the pellets were sintered to remove the pore forming agents and to achieve a similar volume fraction of porosity with thermal barrier coatings. After CMAS infiltration, only some small pores in the CMAS‐infiltrated zones were filled by CMAS, whereas all large pores (larger than 13 μm) remained unfilled; besides, the results also show that even open pores can resist filling by CMAS. The reason may relate to pore diameters; if the diameter of a pore is relatively large, the pore surface will not be completely wetted by liquid CMAS, the liquid meniscus will be discontinuous, and therefore the pore cannot be filled. The key insight gained from this study is that introducing “CMAS‐proof” pores into thermal barrier coatings may be a potential way to mitigate CMAS damage.

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Section: Resultssupporting

confidence: 90%

“…Many CMAS mitigation strategies have been proposed in the literature . Most approaches aim to manipulate the chemical reaction between TBCs and CMAS by changing the chemical composition of TBCs.…”

Section: Introductionmentioning

confidence: 99%

Pore filling behavior of YSZ under CMAS attack: Implications for designing corrosion‐resistant thermal barrier coatings

et al. 2018

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“…The lifetime of all samples with all layered structure was longer than that without the buffer layer. The relatively early failure of the SLC TBCs can be 11 attributed to its lower fracture toughness of the YGYZ top coat, compared with the buffer layer. The DLC TBCs with the CoNi-based bond coat were sustained for a longer lifetime than those with the Ni-based bond coat, independent of the buffer layer species.…”

Section: Furnace Cyclic Thermal Fatigue Testmentioning

confidence: 99%

“…The most effective approach to meeting these needs appears to be the use of low thermal conductivity materials of RE-stabilized cubic zirconia (where RE indicates a rareearth element) type for the outer ceramic layer [10][11][12]. The advanced TBCs with a low thermal conductivity have been continuously investigated with zirconate materials doped with lanthanum, gadolinium (Gd), ytterbium (Yb), etc.…”

Section: Introductionmentioning

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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“…Furthermore, recent studies show that lanthanide zirconates with the pyrochlore structure have better resistance to corrosion by CMAS. 6,7 Compared to common applied YSZ, lanthanide zirconates have a slightly lower thermal expansion coefficient, which may result in lower compatibility with the bond coat and superalloy substrate. 1,[8][9][10] However, the better corrosion resistance can still contribute to improving the lifetime of the thermal barrier coatings.…”

mentioning

confidence: 99%

CaO-MgO-Al₂O₃-SiO₂(CMAS) Corrosion of Gd₂Zr₂O₇and Sm₂Zr₂O₇

Wang

Bakal

Zhang

et al. 2016

J. Electrochem. Soc.

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Ceramic thermal barrier coatings are applied to superalloys used in gas turbine engineering to increase the operating temperature and the energy conversion efficiency. However, dust consisting of CaO-MgO-Al 2 O 3 -SiO 2 (CMAS) from the air can be injected into the engines and corrode the thermal barrier coatings. Lanthanide zirconates are promising materials in thermal barrier coatings due to their low thermal conductivities, good phase stability and good corrosion resistance. However, the corrosion resistance mechanism of CMAS on lanthanide zirconates is still not clearly understood. In this work, the corrosion mechanism of Gd 2 Zr 2 O 7 and Sm 2 Zr 2 O 7 in CMAS is studied. The results show that the CMAS can easily react with lanthanide zirconate thermal barrier coatings to form a dense layer, which can resist further corrosion.

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Protectiveness of Pt and Gd2Zr2O7 layers on EB-PVD YSZ thermal barrier coatings against calcium–magnesium–alumina–silicate (CMAS) attack

Cited by 76 publications

References 27 publications

Pore filling behavior of YSZ under CMAS attack: Implications for designing corrosion‐resistant thermal barrier coatings

Pore filling behavior of YSZ under CMAS attack: Implications for designing corrosion‐resistant thermal barrier coatings

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

CaO-MgO-Al₂O₃-SiO₂(CMAS) Corrosion of Gd₂Zr₂O₇and Sm₂Zr₂O₇

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Protectiveness of Pt and Gd2Zr2O7 layers on EB-PVD YSZ thermal barrier coatings against calcium–magnesium–alumina–silicate (CMAS) attack

Cited by 76 publications

References 27 publications

Pore filling behavior of YSZ under CMAS attack: Implications for designing corrosion‐resistant thermal barrier coatings

Pore filling behavior of YSZ under CMAS attack: Implications for designing corrosion‐resistant thermal barrier coatings

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

CaO-MgO-Al2O3-SiO2(CMAS) Corrosion of Gd2Zr2O7and Sm2Zr2O7

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CaO-MgO-Al₂O₃-SiO₂(CMAS) Corrosion of Gd₂Zr₂O₇and Sm₂Zr₂O₇