Estimation of thermal barrier coating fracture toughness using integrated computational materials engineering

The fracture toughness of thermal barrier coatings (TBC) is a critical mechanical property that governs damage resistance. Catastrophic delamination of TBC under erosion conditions occurs in TBC with low toughness. Prior research has explored indirect and complex experiments to measure TBC toughness, but the miniaturized nature of the multi-layered coating makes it difficult to quantify its intrinsic toughness. This paper integrates computational modeling and experimental approaches to estimate the TBC toughness and the substrate delamination strength. The results show that a typical newly fabricated yttrium stabilized zirconia coating under service conditions has a toughness estimated in the range of 0.1–0.5 MPa m1/2 and a toughness of thermally grown oxide layer in between 1.5 and 1.7 MPa m1/2. The analysis also determined that a thermally grown oxide with a fracture toughness above 2.0 MPa m1/2 would not delaminate under the service conditions. Overall, the approach demonstrates the value of integrated computational material approaches, which can save time and enhance predictive power.