High-temperature compressive creep behavior and mechanism of Hf6Ta2O17 ceramic as a candidate for thermal barrier coatings

A novel Hf6Ta2O17 ceramics is prepared by a solid-state reaction method. High-temperature creep behavior of Hf6Ta2O17 and 8YSZ ceramics are investigated by compressive creep test combined with a digital image correlation (DIC) method. It is found that the creep mechanism of Hf6Ta2O17 ceramics is controlled by grain boundary sliding associated with dislocation movement (stress exponent-2-3, and activation energy of 600-620 kJ/mol). Grain boundary sliding accommodated to the interface reaction is the main creep mechanism of 8YSZ ceramics (stress exponent-2, and activation energy of 425-465 kJ/mol). Hf6Ta2O17 ceramics have higher creep resistance than 8YSZ ceramics under the same conditions.