Substrate Effects on the High-Temperature Oxidation Behavior of Thermal Barrier Coatings
Zhenhua Xu,Jianping Li,Rende Mu,Shimei He
Journal of Materials Sciences & Technology (J. Mater. Sci. Technol.)
Abstract
The high-temperature oxidation behaviors of the NiCrAlYSi/P-YSZ thermal barrier coatings (TBCs) pro- duced by electron beam-physical vapor deposition (EB-PVD) on directionally solidied (DS) and single crys- talline (SC) Ni-based superalloy substrates were investigated. The cross-sectional microstructure investigation, isothermal and cyclic oxidation tests were conducted for the comparison of oxidation behaviors of TBCs on dierent substrates. Although TBC on DS substrate has a relatively higher oxidation rate, it has a longer thermal cycling lifetime than that on SC substrate. The primary factor for TBC spallation is the mismatch of thermal expansion coecient (TEC) of the bond coat and substrate. The morphological feature of thermally grown oxide (TGO) has a strong inuence on the TBC performance. By optimizing the elemental interdiusion between bond coat and substrate, a high quality TGO layer is formed on the DS substrate, and therefore the TBC oxidation behavior is improved.
keywords:Thermal barrier coatings; Thermally grown oxide; Electron beam-physical vapor deposition; Single crystalline superalloy; Directionally solidified superalloy
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