Evaluation of Thermal Cycle Durability of Thermal Barrier Coating by Laser Speckle Method and AE Method with Continuous Waveform Recording

Abstract

This study focuses on two advanced techniques applied to evaluate the thermal cycle durability of TBC, which were developed in joint research with NIMS. The first technique utilizes a new AE Method with Continuous Waveform Recording, which can detect AE events more precisely than conventional AE systems. The second technique is a non-contact strain measurement method using laser speckles, which can measure the strain on the TBC surface at high temperature. These techniques were combined with a laser thermal cycle test to establish the “∈_H-N diagram”, which shows the relationships between the hot shock strain ∈_H in the laser thermal cycle test and the cycle number N to failure for different TBC thicknesses. The obtained ∈_H-N diagram revealed the durability of TBC for various thicknesses and was transformed to an evaluation map to predict the TBC thickness limitation. MHI will apply the map to utilize the optimum thickness of TBC.