The enhanced mechanical properties for Hf6Ta2O17 thin film through component segregation

With outstanding thermal and mechanical properties, Hf6Ta2O17 emerges as an ideal candidate for next-generation thermal barrier coatings (TBC) material. However, high-temperature process during TBC fabrication will inevitably lead to Ta2O5/HfO2 component segregation because large differences in vapor pressure. In this paper, Hf6Ta2O17 polycrystalline film with different Ta2O5/HfO2 component was prepared on sapphire substrate by sol-gel method through spin coating. Morphological analysis indicates the excessive Ta2O5 can reduce the porosity in Hf6Ta2O17 thin film through eutectic process, while excessive HfO2 will lead to a worse morphology and smaller average grain size. Nanoindentation reveals that component segregation of excessive Ta2O5/HfO2 could both be used to strengthen of Hf6Ta2O17 through different mechanisms. In addition, a higher elastic recovery rate in excessive Ta2O5 system indicates Ta2O5Hf6Ta2O17 eutectic system could accelerate energy dissipation and further enhance the toughness for Hf6Ta2O17. This work provides a deep insight into the strengthening mechanism of ceramics Hf6Ta2O17 with component segregation and paves the way to design of next-generation TBCs.