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Assessment of the Spent Life Fraction of Gas Turbine Blades by Coating Life

pubblicazioni - Articolo

Assessment of the Spent Life Fraction of Gas Turbine Blades by Coating Life

Modelling and Photostimulated Luminescence Piezospectroscopy Claudia Rinaldi*, Letizia De Maria*, Marco Mandelli** ASME Journal of Engineering of Gas Turbines and Power Vol. 132 N. 11, Novembre 2010 ASME USA * RSE SpA **PROING ITALIA This paper describes the application of a double-sided approach to assess the spent life fraction of thermal barrier coatings (TBCs)at local positions of ex-service blades with NiCoCrAlY-Re bond coat and EB-PVD TBC. A life prediction code implemented with inverse problem solution routines was applied to determine the mean local temperature. On the single blades, large differences (>150 °C) of mean local temperature were estimated between regions just after the cooling holes and far from them. A self development portable photostimulated luminescence piezospectroscopy (PLPS) instrument was also applied and the coating spent life fraction was avaluated with a recently proposed PLPS diagnostic parameter. The spent life fractions avaluated from mean local temperature values were in good agreement with those estimated from PLPS measurements. Lower spent life fractions were found in well cooled regions of all blades, while higher spent life fractions were calculated at the hottest positions of the blades, particularly on components coming from a plant with a double number of starts. The results confirm the reliability of the PLPS technique and its diagnostic compatibility also for NiCoCrAlY-Re bond coats, both local different on the single component and blade-to blade variations in coating spent life can be evidenced in a non-destructive way. [DOI: 10.115/1.4000804].

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