Delamination failure monitoring of plasma sprayed composite ceramic coatings in rolling contact by acoustic emission

The aim of present study is to monitor the delamination failure of plasma sprayed Al2O3-40 wt% TiO2 composite ceramic coating (AT40 coating) in rolling contact condition by acoustic emission (AE) technology. The AE signals of the delamination failure process were divided into three types (type I: normal contact; type II: fatigue crack initiation; type III: delamination failure) based on the feature of AE count. The waveforms and frequency spectrums of different types of AE signals during delamination failure process of the coatings were obtained by Empirical mode decomposition (EMD) method. The relationship between the waveform/frequency of the AE signals and the delamination failure mechanism of the AT40 coatings were discussed in detail.