In this work, we focused on the experimental arrangement of thermal wave imaging (TWI) methods for the quantitative evaluation of non-uniform topcoat thickness of thermal barrier coatings (TBCs). Two TWI techniques, pulsed thermography (PT) and lock-in thermography (LIT) were implemented on plasma sprayed TBCs with varied topcoat ranging from 0.1 mm to 0.6 mm. In PT, a short and high energy light pulse was applied on a sample surface whereas, in LIT, the sample surface was excited by a sinusoidal heat flux at several modulation frequencies ranging from 2Hz down to 0.01 Hz. |
