- Volume 3 Issue 2
Use of Modern Nondestructive Techniques in High Temperature Degradation of Material and Coatings
- Lee, C. K. (Department of Mechanical Engineering, Seoul National University of Technology) ;
- Y. H. Sohn (Advanced Materials Processing and Analysis Center(AMPAC), University of Central Florida)
- Published : 2003.12.01
The durability and reliability of thermal barrier coatings (TBCs) play an important role in the service reliability, availability and maintainability (RAM) of hotsection components in advanced turbine engines for aero and utility applications. Photostimulated luminescence spectroscopy (PSLS) and electrochemical impedance spectroscopy (EIS) are being concurrently developed as complimentary nondestructive evaluation (NDE) techniques for quality control and liferemain assessment of TBCs. This paper overviews the governing principles and applications of the luminescence and the impedance examined in the light of residual stress, phase constituents and resistance (or capacitance) in TBC constituents including the thermally grown oxide (TGO) scale. Results from NDE by PSLS and EIS are discussed and related to the microstructural development during high temperature thermal cycling, examined by using a variety of microscopic techniques including focused ion beam (FIB) insitu liftout (INLO), transmission and scanning transmission electron microscopy (TEM and STEM).