It is generally believed that a thermally grown oxide (TOO) layer of alumina provides enhanced protection to the metallic bond coat in thermal barrier coating (TBC) systems at elevated temperatures. However, in an air...It is generally believed that a thermally grown oxide (TOO) layer of alumina provides enhanced protection to the metallic bond coat in thermal barrier coating (TBC) systems at elevated temperatures. However, in an air-plasma-sprayed (APS) TBC system with Co-32Ni-21Cr-8Al-0.5Y (wt%) bond coat, the TGO layer formed upon thermal exposure in air was predominantly chromia and spinels, which would not effectively protect the bond coat at above 1000°C. In addition, mixed oxides of chromia, spinel and nickel oxide formed heterogeneously between the ceramic coating and CoNiCrAlY bond coat, which would promote crack initiation and lead to premature TBC failure. A heat treatment in a low-pressure condition was applied to the as-sprayed TBC system, with the aim to produce an alumina layer as well as reduce the amount of detrimental oxides. The influence of this low-pressure oxidation treatment (LPOT) on the bond coat cyclic oxidation behaviour of the TBC system was also investigated.展开更多
文摘It is generally believed that a thermally grown oxide (TOO) layer of alumina provides enhanced protection to the metallic bond coat in thermal barrier coating (TBC) systems at elevated temperatures. However, in an air-plasma-sprayed (APS) TBC system with Co-32Ni-21Cr-8Al-0.5Y (wt%) bond coat, the TGO layer formed upon thermal exposure in air was predominantly chromia and spinels, which would not effectively protect the bond coat at above 1000°C. In addition, mixed oxides of chromia, spinel and nickel oxide formed heterogeneously between the ceramic coating and CoNiCrAlY bond coat, which would promote crack initiation and lead to premature TBC failure. A heat treatment in a low-pressure condition was applied to the as-sprayed TBC system, with the aim to produce an alumina layer as well as reduce the amount of detrimental oxides. The influence of this low-pressure oxidation treatment (LPOT) on the bond coat cyclic oxidation behaviour of the TBC system was also investigated.
