Atomistic modelling of the thermo-mechanical behaviour of GDZ/YSZ interphase region in bilayer thermal barrier coatings

Current gas turbine engines use Yttria-Stabilized Zirconia (YSZ) as the top coat for heat shielding in HP turbines as well as combustors. Unfortunately, YSZ suffers from many drawbacks once the temperature reaches 1200[Formula: see text]C. This limits the long-term application temperature of YSZ, and a few top coat replacements have been suggested and examined. In our study, we make two major changes to the top coat. The first is to use Gadolinium Zirconate (Gd 2 Zr 2 O 7 or GDZ) which enjoys better thermal properties. The second is to combine it with YSZ in a bilayer configuration, thus, making use of the combined beneficial effects of thermal shielding and mechanical strength of these top coats. In spite of the fact that GDZ/YSZ has been suggested by other authors, no work has been devoted to study the role played by the GDZ–YSZ interphase region, possible interdiffusion, its thermal properties and interphase region strength. In this study, we developed comprehensive atomistic models of the GDZ/YSZ interface using molecular dynamics (MD) with emphasis on thermo-mechanical properties of the GDZ/YSZ interphase region. This allowed us to examine the evolution of the GDZ/YSZ interphase region and compute the interface bond strength with temperature.