LAUSR

Abstract New ceramic materials for thermal barrier coating (TBC) are a key to more powerful and efficient next-generation gas turbines. Here, we investigate the effect of the two novel dopants, Ta2O5 and Y2O3, on the phase stability, thermophysical and mechanical properties of the HfO2-based ceramic systems (i.e., Ta2O5-HfO2; Y2O3-HfO2). For the Ta2O5-HfO2 system, we observe the formation of a new compound, Hf6Ta2O17. In the Y2O3-HfO2 system, stabilized HfO2 with up to 18 mol% YO1.5 (YSH) is generated, whereby monoclinic HfO2 transforms to cubic HfO2. The cubic YSH ceramics demonstrate enhanced phase stability, compared with Hf6Ta2O17 at temperatures up to 1300 °C. The mechanical properties, thermal expansion and fracture toughness of 18–24 mol% YSH (YO1.5 = 18–24 mol%) indicate that cubic YSH exhibits enhanced suitability for higher-temperature.