Title

Microstructural Characterization Of Thermal Barrier Coatings On High Pressure Turbine Blades

Keywords

Failure analysis; Photostimulated luminescence spectroscopy; Scanning electron microscopy; Thermal barrier coatings; Turbine blade; X-Ray diffraction

Abstract

Thermal barrier coated high pressure turbine blades were characterized before and after the service by microstructural analysis and Cr3+ photostimulated luminescence piezo-spectroscopy. Thermal barrier coatings, in this study, consisted of electron beam physical vapor deposited yttria partially stabilized zirconia (YSZ; ZrO2-8 wt.% Y2O3), vapor-deposited aluminide bond coat and Ni-base superalloy. Compressive residual stress in thermally grown oxide, measured by Cr3+ photostimulated luminescence piezospectroscopy, was observed to be in the order of 2.5 ~ 3.0 GPa and varied slightly as a function of substrate geometry. X-Ray diffraction and scanning electron microscopy equipped with energy dispersive X-ray spectroscopy were utilized to investigate the microstructural development of thermal barrier coatings. The as-deposited non-equilibrium tetragonal (t′) phase in the YSZ coatings was observed to decompose after the service, but the monoclinic (m) phase was only found in the YSZ coatings with concave substrate curvature on the pressure side of the HPT blade. Also, a significant sintering of ZrO2-8 wt.% Y2O3 coating after the service was observed in the microstructure. Localized spallation of YSZ occurred within the thermally grown oxide (mostly α-Al2O3) and within the ZrO2-8 wt.% Y2O3 coating for pressure and suction sides of the serviced high pressure turbine blade near the tip, respectively. © 2001 Elsevier Science B.V. All rights reserved.

Publication Date

9-1-2001

Publication Title

Surface and Coatings Technology

Volume

146-147

Number of Pages

132-139

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1016/S0257-8972(01)01369-X

Socpus ID

17544388839 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/17544388839

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