The thermally grown oxide (TGO), formed on the bond coat (BC) surface of thermal barrier coatings (TBCs), has a significant impact on the TBCs life time. In order to reduce growth kinetics of TGO, vacuum pre-treatment was taken for some bond coats before pre-oxidation and isothermal oxidation in air. The other bond coats were directly subjected to pre-oxidation and isothermal oxidation. The grain size and grain boundary distribution of the TGO were analyzed by electron backscattered diffraction (EBSD). Element diffusion was taken into account to analyze growth kinetics of the TGO. Results indicate that the change of Al2O3 TGO thickness with isothermal oxidation duration doesn’t fit well to conventional oxidation theory, i.e. exponential function. It is attributed to the change of the grain structure during the pre-treatment. This mechanism would benefit the development of long-life and highly reliable TBCs.

alumina ceramics, electron backscattered diffraction, nickel-cobalt-chromium-aluminum-yttrium alloys, thermal barrier coatings, thermal spraying, thermally grown oxide
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Copyright © 2015 ASM International. All rights reserved.
2015
ASM International
Topics
Thermal barrier coatings Nickel-cobalt-chromium alloys Alumina ceramics Thermal spray coating Electron backscatter diffraction
Issue Section:
Advanced Coatings for Aerospace Components
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