The lifetime of thermal barrier coating systems is determined by fracture processes in the region between the bond coat and the ceramic top coat which are strongly influenced by the oxidation processes going on at service temperature. In order to assess the quantitative effect of oxidation on the mechanical behavior of TBC systems, an investigation technique has been developed which combines a modified 4-point bending test at temperatures up to 1323 K with in-situ acoustic emission measurements. Mechanical data are measured by a load cell and a strain gauge yielding stress-strain data which are converted into data describing the load/strain situation in the layered system with the help of finite element calculations. The load/strain situation is correlated with the acoustic emission data which allows the determination of critical levels for layer fracture (cracking, detachment, spallation, etc.). A description of the technique and first measurements on the model system NiO/Ni are reported.
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