In situ characterization of high temperature elastic modulus and fracture toughness in air plasma sprayed thermal barrier coatings under bending by using digital image correlation

The evolutions of elastic modulus and fracture toughness are the key factors affecting the failure mechanism and durability of thermal barrier coatings (TBCs). Combined the high temperature three-point bending with the digital image correlation (DIC) method, the variations of high temperature elastic modulus and fracture toughness of air plasma sprayed TBCs with temperature are determined. The surface and interfacial cracking information can be monitored real-time by DIC system. The results show that when the temperature rises from 30 °C to 800 °C, the elastic modulus and fracture toughness of TC decrease from 20.3 GPa to 13.1 GPa and from 1.31 MPa m^1/2 to 1.16 MPa m^1/2, respectively. And the interfacial fracture toughness increases from 83.7 J/m² to 156.3 J/m². These results are consistent with the available values determined in literatures, which ensures the validity of this method.