An Experimental Investigation of Interface Fracture Characteristic of APS Thermal Barrier Coating System under Bending at 1000 °C

This paper investigated the thermo-mechanical bending failure characteristic of air plasma-sprayed (APS) thermal barrier coating (TBC) system at 1000 oC by three-point bending test. A through-width surface pre-crack on the centre surface of the top ceramic coating (TC) in TBC sample was firstly designed and made by air plasma spraying technology. The fracture characteristic and spallation phenomena of the TBC were investigated under bending test in air at 1000 oC. The effects of constant displacement rate, span width of bending equipment and thermal aging time on the thermo-mechanical bending failure of the APS TBC system were slight at 1000 oC. Using SEM observations and EDX analysis, the interface cracks initiation, propagation and coalescence were discussed in detail. Furthermore, the fracture surface located within the TBC close to the TBC/TGO interface for all APS TBC samples under bending at 1000 oC.