Low‐Thermal‐Conductivity Rare‐Earth Zirconates for Potential Thermal‐Barrier‐Coating Applications

Rare‐earth zirconates have been identified as a class of low‐thermal‐conductivity ceramics for possible use in thermal barrier coatings (TBCs) for gas‐turbine engine applications. To document and compare the thermal conductivities of important rare‐earth zirconates, we have measured the thermal conductivities of the following hot‐pressed ceramics: (i) Gd 2 Zr 2 O 7 (pyrochlore phase), (ii) Gd 2 Zr 2 O 7 (fluorite phase), (iii) Gd 2.58 Zr 1.57 O 7 (fluorite phase), (iv) Nd 2 Zr 2 O 7 (pyrochlore phase), and (v) Sm 2 Zr 2 O 7 (pyrochlore phase). We have also measured the thermal conductivity of pressureless‐sintered 7 wt% yttria‐stabilized zirconia (7YSZ)—the commonly used composition in current TBCs. All…