In situ characterizations of mechanical behaviors of freestanding (Gd_0.9Yb_0.1)₂Zr₂O₇ coatings by bending tests under different temperatures based on digital image correlation

It is important to investigate the high-temperature mechanical properties and failure mechanisms of Gd₂Zr₂O₇ ceramic materials for the development of novel thermal barrier coatings. Freestanding (Gd_0.9Yb_0.1)₂Zr₂O₇ (GYbZ) coatings were prepared by supersonic plasma sprayed technique. A modified high-temperature in situ experimental system (up to 1500 °C) with the aid of digital image correlation technique was used to evaluate the fracture strength and flexural modulus of GYbZ coatings using three-point bending tests, and the fracture toughness was studied by single edge notched beam experiments. In addition, the extended finite element analysis was used to estimate the critical energy release rate of GYbZ coatings through the aforementioned experimental data. The effect of test temperature on the mechanical properties, cracking and fracture morphology of freestanding GYbZ coatings was discussed under bending loads. The results are useful for understanding high-temperature failure mechanisms of multilayered GYbZ thermal barrier coatings.