Pre-oxidation and TGO growth behaviour of an air-plasma-sprayed thermal barrier coating

Chen, W.R.; Wu, Xijia; Marple, Basil R.; Lima, Rogerio S.; Patnaik, P. C.

doi:10.1016/j.surfcoat.2008.01.021

Cited by 137 publications

(60 citation statements)

References 19 publications

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“…A semi-quantitative SEM/ EDS analysis showed that the aluminum concentration was highly nonuniform in the as-sprayed APS bond coat, with some regions having very low Al content (Table 3), compared to that in the CoNiCrAlY powder (%16 at.%). This nonuniformity of Al distribution in the bond coat was documented in some previous researches (Ref 9), and can probably be attributed to the preferential oxidation and/or vaporization in the plasma, because the particle surface temperature was much higher than the melting point of the CoNiCrAlY.…”

Section: Coating Microstructuressupporting

confidence: 64%

The Oxidation Behavior of TBC with Cold Spray CoNiCrAlY Bond Coat

Chen

Irissou²,

et al. 2010

J Therm Spray Tech

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Cold gas dynamic spray (CGDS) has been considered a potential technique to produce the metallic bond coat for TBC applications, because of its fast deposition rate and low deposition temperature. This article presents the influence of spray processes for bond coat, including air plasma spray, high velocity oxy-fuel, and in particular CGDS, on the oxidation performance of TBCs with a Co-32Ni-21Cr-8Al-0.5Y (wt.%) bond coat and an air plasma sprayed topcoat. Oxidation behavior of the TBCs was evaluated by examining the coating microstructural evolution, TGO growth behavior, and crack propagation during thermal exposure at 1050°C. The relationship between the TGO growth and crack propagation will be discussed.

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Section: Coating Microstructuressupporting

confidence: 64%

The Oxidation Behavior of TBC with Cold Spray CoNiCrAlY Bond Coat

Chen

Irissou²,

et al. 2010

J Therm Spray Tech

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“…Low pressure plasma spraying (LPPS) and high velocity oxy-fuel (HVOF) spraying have been widely employed to prepare bond coat ( Ref 14,[27][28][29]. The typical feature of these processes is that a bond coat is deposited usually by semi-melted spray droplets.…”

Section: Introductionmentioning

confidence: 99%

Influence of TGO Composition on the Thermal Shock Lifetime of Thermal Barrier Coatings with Cold-sprayed MCrAlY Bond Coat

Zhang

2009

J Therm Spray Tech

102

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NiCoCrAlTaY bond coat was deposited by cold spraying to assemble thermal barrier coatings (TBCs). The microstructure of the cold-sprayed bond coat was examined using scanning electron microscopy. TBCs consisting of cold-sprayed bond coat and plasma-sprayed YSZ were pretreated at different conditions to form different thermally grown oxides (TGOs) before thermal cycling test. The influence of the TGO composition on the thermal cyclic lifetime was quantitatively examined through the measurement of the coverage ratio of the mixed oxides on the bond coat surface. The results showed that the bond coat exhibited a dense oxidation-free microstructure, and TGOs in different morphologies and constituents were present after thermal cyclic test. The formation of TGOs was significantly influenced by pretreatment conditions. Two kinds of TGO were detected on the surface of bond coat after the spallation of YSZ coatings. One is the a-Al 2 O 3 -based TGO and the other is the mixed oxide. It was found that the thermal cyclic lifetime is inversely proportional to the coverage ratio of the mixed oxides formed at the bond coat/YSZ interface. The high coverage ratio of the mixed oxide on the interface leads to the early spalling of YSZ coating.

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“…The conventional 8YSZ coating has obvious gaps, cracks and pores, and the thickness of the TGO is larger than nanostructured 8YSZ coating. And the TGO of the bond coat which has been recognized as the cause for separation of the ceramic layer from the bond coat when the thickness of the TGO more than 10 m [31,32]. At the same time, it can be seen that there are some "oxidized isolated islands" in the bond coat which are distributed at random, but the area of the "oxidized isolated islands" in the nanostructured 8YSZ is smaller.…”

Section: Oxidation Kineticsmentioning

confidence: 98%