Screening rare‐earth aluminates as promising thermal barrier coatings by high‐throughput first‐principles calculations

Abstract

AbstractThermal barrier coatings (TBCs) play an important role in gas turbines to protect the turbine blades from the high‐temperature airflow damage. In this work, we use first‐principles calculations to investigate a specific class of rare‐earth (RE) aluminates, including cubic‐REAlO3(c‐REAlO3), orthorhombic‐REAlO3(o‐REAlO3),RE3Al5O12, andRE4Al2O9, to predict their structural stability, bonding characteristics, and mechanical and thermal properties. The polyhedron structures formed by the Al–O bonds are stronger and exhibit rigid characteristics, whereas the polyhedra formed by theRE–O bonds are relatively weak and soft. The alternating stacking of AlO4tetrahedra, AlO6octahedra, andRE–O polyhedra, as well as the selection ofREelements, shows intensive influences on the expected mechanical and thermal properties. TheB,G, andEof these four types of aluminates decrease in the order of c‐REAlO3 > o‐REAlO3 > RE3Al5O12 > RE4Al2O9.REAlO3andRE4Al2O9are brittle and quasi‐ductile ceramics, respectively, whereasRE3Al5O12is tailorable. The minimum thermal conductivity is in the range of 1.4–1.5 W m−1 K−1for c‐REAlO3, 1.3–1.4 W m−1 K−1for o‐REAlO3, 1.25–1.35 W m−1 K−1forRE3Al5O12, and 0.8–0.9 W m−1 K−1forRE4Al2O9.RE4Al2O9with low thermal conductivity and damage tolerance is predicted to be the potential candidates for next‐generation TBC materials.