返回Google圖書搜尋

Non-destructive Evaluation of Thermal Barrier Coatings with Thermal Wave Imaging and Photostimulated Luminescence Spectroscopy

出版	University of Central Florida, 2005
URL	http://books.google.com.hk/books?id=V_Q-yQEACAAJ&hl=&source=gbs_api

註釋TWI is a promising NDE technique with the ability to detect integrity and thickness of TBCs. In this study, TWI was employed as an NDE technique to examine as-coated TBCs with varying thicknesses, and thermally-cycled TBCs for initiation and progression of subcritical-subsurface damage as a function of thermal cycling. TWI and thermal response amplitude were correlated to the microstructural characteristics and damage progression of TBCs based on phenomenological expressions of thermal diffusion. The TBC specimens examined consisted of air plasma sprayed ZrO- 7wt.% Y2O3 on NiCoCrAlY bond coats with Haynes 230 superalloy substrate. As-coated specimens of varying thicknesses were evaluated by TWI to examine its applicability as a thickness measurement tool. It was found that heat dissipation through the TBC following pulsed excitation by xenon flash lamps initially followed the 1-D law of conduction and deviated from it as a function of thickness and time. The deviation resulted from quick dissipation of heat into the conductive metallic substrate. Therefore, with calibration, TWI can be used as a tool for YSZ thickness measurements of APS TBCs in the as-coated condition for quality control measures.