Influence of mechanical properties on thermal shock resistance of TBCs

In this study, thermal barrier coatings with different porosities were prepared using 8 wt-% yttria-stabilized zirconia by atmospheric plasma spray on a superalloy substrate. The porosity of the ceramic coating was increased by modulating the primary gas flow rate and the secondary gas flow rate. The elastic modulus and fracture toughness of the coatings were measured by the indentation method, and the thermal shock resistance was evaluated by quenching the samples from 1050°C to room temperature. The Vickers hardness and elastic modulus of the coating were decreased by increasing the volume of the pores, and the fracture toughness was enhanced. It was found that the thermal shock resistance was improved owing to the stress release due to the pores.