Fracture behavior of ceramic coatings during thermal cycling evaluated by acoustic emission method using laser interferometers

This paper describes an application of laser techniques for the detection of acoustic emission (AE) signals at elevated temperature. The AE signals from an Al2O3 plasma sprayed coating on a SUS304 substrate were detected using four laser Doppler vibrometers during thermal cycling between 1000 °C and room temperature. The event location and the fracture mode of each AE could be determined due to the benefit of the laser techniques, non-contact measurement and absolute value measurement of surface velocity. This approach revealed the advantage and the disadvantages of the application of laser techniques for AE measurement in high temperature environment.